Increment 2: Implement major ops and add structure similar to cuda

.circleci/config.yml

@@ -16,9 +16,6 @@ parameters:
   linux_release:
     type: boolean
     default: false
-  cuda_release:
-    type: boolean
-    default: false
 
 jobs:
   build_documentation:
@@ -41,7 +38,7 @@ jobs:
             pip install --upgrade pip
             pip install --upgrade cmake
             pip install -r docs/requirements.txt
-            pip install . -v
+            CMAKE_BUILD_PARALLEL_LEVEL=`sysctl -n hw.ncpu` pip install . -v
       - when:
           condition:
             not: << parameters.upload-docs >>
@@ -97,15 +94,17 @@ jobs:
           name: Install Python package
           command: |
             CMAKE_ARGS="-DMLX_BUILD_METAL=OFF" \
+              CMAKE_BUILD_PARALLEL_LEVEL=`nproc` \
               python3 setup.py build_ext --inplace
             CMAKE_ARGS="-DMLX_BUILD_METAL=OFF" \
+              CMAKE_BUILD_PARALLEL_LEVEL=`nproc` \
               python3 setup.py develop
       - run:
           name: Generate package stubs
           command: |
             echo "stubs"
             pip install typing_extensions
-            python setup.py generate_stubs
+            python setup.py generate_stubs 
       - run:
           name: Run Python tests
           command: |
@@ -155,14 +154,15 @@ jobs:
           name: Install Python package
           command: |
             source env/bin/activate
-            DEBUG=1 CMAKE_ARGS="-DCMAKE_COMPILE_WARNING_AS_ERROR=ON" \
+            DEBUG=1 CMAKE_BUILD_PARALLEL_LEVEL=`sysctl -n hw.ncpu` \
+            CMAKE_ARGS="-DCMAKE_COMPILE_WARNING_AS_ERROR=ON" \
               pip install -e . -v
       - run:
           name: Generate package stubs
           command: |
             source env/bin/activate
             pip install typing_extensions
-            python setup.py generate_stubs
+            python setup.py generate_stubs 
       - run:
           name: Run Python tests
           command: |
@@ -205,7 +205,8 @@ jobs:
           name: Run Python tests with JIT
           command: |
             source env/bin/activate
-            CMAKE_ARGS="-DMLX_METAL_JIT=ON" \
+            CMAKE_BUILD_PARALLEL_LEVEL=`sysctl -n hw.ncpu` \
+              CMAKE_ARGS="-DMLX_METAL_JIT=ON" \
               pip install -e . -v
             LOW_MEMORY=1 DEVICE=gpu METAL_DEVICE_WRAPPER_TYPE=1 \
               METAL_DEBUG_ERROR_MODE=0 \
@@ -222,9 +223,11 @@ jobs:
           command: |
             sudo apt-get update
             sudo apt-get install libblas-dev liblapack-dev liblapacke-dev
+            sudo apt-get install openmpi-bin openmpi-common libopenmpi-dev
             python -m venv env
             source env/bin/activate
-            CMAKE_ARGS="-DMLX_BUILD_CUDA=ON -DCMAKE_CUDA_COMPILER=`which nvcc`" \
+            CMAKE_BUILD_PARALLEL_LEVEL=`nproc` \
+              CMAKE_ARGS="-DMLX_BUILD_CUDA=ON -DCMAKE_CUDA_COMPILER=`which nvcc`" \
               pip install -e ".[dev]"
       - run:
           name: Run Python tests
@@ -273,18 +276,21 @@ jobs:
           command: |
             source env/bin/activate
             env -u MACOSX_DEPLOYMENT_TARGET DEV_RELEASE=1 \
+              CMAKE_BUILD_PARALLEL_LEVEL=`sysctl -n hw.ncpu` \
               pip install . -v
       - run:
           name: Generate package stubs
           command: |
             source env/bin/activate
             pip install typing_extensions
-            python setup.py generate_stubs
+            python setup.py generate_stubs 
       - run:
           name: Build Python package
           command: |
             source env/bin/activate
-            << parameters.build_env >> python -m build -w
+            << parameters.build_env >> \
+              CMAKE_BUILD_PARALLEL_LEVEL=`sysctl -n hw.ncpu` \
+              python -m build -w
       - when:
           condition: << parameters.build_env >>
           steps:
@@ -332,10 +338,14 @@ jobs:
             pip install patchelf
             pip install build
             pip install twine
-            << parameters.extra_env >> pip install . -v
+            << parameters.extra_env >> \
+              CMAKE_BUILD_PARALLEL_LEVEL=`nproc` \
+              pip install . -v
             pip install typing_extensions
-            python setup.py generate_stubs
-            << parameters.extra_env >> python -m build --wheel
+            python setup.py generate_stubs 
+            << parameters.extra_env >> \
+              CMAKE_BUILD_PARALLEL_LEVEL=`nproc` \
+              python -m build --wheel
             auditwheel show dist/*
             auditwheel repair dist/* --plat manylinux_2_31_x86_64
       - run:
@@ -346,46 +356,6 @@ jobs:
       - store_artifacts:
           path: wheelhouse/
 
-  build_cuda_release:
-    parameters:
-      python_version:
-        type: string
-        default: "3.9"
-      extra_env:
-        type: string
-        default: "DEV_RELEASE=1"
-    machine:
-      image: linux-cuda-12:default
-      resource_class: gpu.nvidia.small.gen2
-    steps:
-      - checkout
-      - run:
-          name: Build wheel
-          command: |
-            sudo apt-get update
-            sudo apt-get install libblas-dev liblapack-dev liblapacke-dev
-            python -m venv env
-            source env/bin/activate
-            pip install auditwheel
-            pip install patchelf
-            pip install build
-            pip install twine
-            << parameters.extra_env >> \
-              CMAKE_ARGS="-DMLX_BUILD_CUDA=ON -DCMAKE_CUDA_COMPILER=`which nvcc`" \
-              pip install ".[dev]" -v
-            python setup.py generate_stubs
-            << parameters.extra_env >> \
-              CMAKE_ARGS="-DMLX_BUILD_CUDA=ON -DCMAKE_CUDA_COMPILER=`which nvcc`" \
-              python -m build --wheel
-            bash python/scripts/repair_cuda.sh
-      - run:
-          name: Upload package
-          command: |
-            source env/bin/activate
-            twine upload wheelhouse/*.whl
-      - store_artifacts:
-          path: wheelhouse/
-
 workflows:
   build_and_test:
     when:
@@ -492,16 +462,6 @@ workflows:
             branches:
               ignore: /.*/
           upload-docs: true
-      - build_linux_release:
-          filters:
-            tags:
-              only: /^v.*/
-            branches:
-              ignore: /.*/
-          matrix:
-            parameters:
-              python_version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
-              extra_env: ["PYPI_RELEASE=1"]
 
   prb:
     when:
@@ -665,14 +625,3 @@ workflows:
             parameters:
               python_version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
               extra_env: ["PYPI_RELEASE=1"]
-  cuda_test_release:
-    when:
-      and:
-        - equal: [ main, << pipeline.git.branch >> ]
-        - << pipeline.parameters.cuda_release >>
-    jobs:
-      - build_cuda_release:
-          matrix:
-            parameters:
-              python_version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
-              extra_env: ["PYPI_RELEASE=1"]

CMakeLists.txt

@@ -35,6 +35,7 @@ option(MLX_BUILD_PYTHON_BINDINGS "Build python bindings for mlx" OFF)
 option(MLX_BUILD_METAL "Build metal backend" ON)
 option(MLX_BUILD_CPU "Build cpu backend" ON)
 option(MLX_BUILD_CUDA "Build cuda backend" OFF)
+option(MLX_BUILD_ROCM "Build ROCm backend" OFF)
 option(MLX_METAL_DEBUG "Enhance metal debug workflow" OFF)
 option(MLX_ENABLE_X64_MAC "Enable building for x64 macOS" OFF)
 option(MLX_BUILD_GGUF "Include support for GGUF format" ON)
@@ -88,6 +89,10 @@ if(MLX_BUILD_CUDA)
   enable_language(CUDA)
 endif()
 
+if(MLX_BUILD_ROCM)
+  enable_language(HIP)
+endif()
+
 if(MLX_BUILD_METAL AND NOT METAL_LIB)
   message(STATUS "Metal not found. Unable to build GPU")
   set(MLX_BUILD_METAL OFF)

benchmarks/cpp/single_ops.cpp

@@ -192,22 +192,6 @@ void time_reductions() {
 
   auto argmin_along_1 = [&a]() { return mx::argmin(a, 1, false); };
   TIME(argmin_along_1);
-
-  auto indices = mx::array({1});
-  auto updates = mx::reshape(mx::array({NAN}), {1, 1, 1});
-  std::vector<int> axes{0};
-  auto b = scatter(a, {indices}, updates, axes);
-  mx::eval(b);
-
-  auto max_along_0 = [&b]() { return mx::max(b, 0, false); };
-  TIME(max_along_0);
-  auto max_along_1 = [&b]() { return mx::max(b, 1, false); };
-  TIME(max_along_1);
-
-  auto min_along_0 = [&b]() { return mx::min(b, 0, false); };
-  TIME(min_along_0);
-  auto min_along_1 = [&b]() { return mx::min(b, 1, false); };
-  TIME(min_along_1);
 }
 
 void time_gather_scatter() {

benchmarks/python/comparative/bench_torch.py

@@ -5,7 +5,6 @@ import os
 import time
 
 import torch
-import torch.cuda
 import torch.mps
 
 
@@ -45,10 +44,8 @@ def bench(f, *args):
 
 
 def sync_if_needed(x):
-    if x.device == torch.device("mps"):
+    if x.device != torch.device("cpu"):
         torch.mps.synchronize()
-    elif x.device == torch.device("cuda"):
-        torch.cuda.synchronize()
 
 
 @torch.no_grad()
@@ -102,14 +99,6 @@ def reduction(op, axis, x):
     sync_if_needed(x)
 
 
-@torch.no_grad()
-def sum_and_add(axis, x, y):
-    z = x.sum(axis=axis, keepdims=True)
-    for i in range(50):
-        z = (z + y).sum(axis=axis, keepdims=True)
-    sync_if_needed(x)
-
-
 @torch.no_grad()
 def softmax(axis, x):
     ys = []
@@ -351,11 +340,7 @@ if __name__ == "__main__":
         args.axis.pop(0)
 
     torch.set_num_threads(1)
-    device = "mps"
-    if torch.cuda.is_available():
-        device = "cuda"
-    if args.cpu:
-        device = "cpu"
+    device = "cpu" if args.cpu else "mps"
 
     types = args.dtype
     if not types:
@@ -475,8 +460,5 @@ if __name__ == "__main__":
     elif args.benchmark == "selu":
         print(bench(selu, x))
 
-    elif args.benchmark == "sum_and_add":
-        print(bench(sum_and_add, axis, *xs))
-
     else:
         raise ValueError(f"Unknown benchmark `{args.benchmark}`.")

benchmarks/python/single_ops.py

@@ -51,20 +51,6 @@ def time_maximum():
     time_fn(mx.maximum, a, b)
 
 
-def time_max():
-    a = mx.random.uniform(shape=(32, 1024, 1024))
-    a[1, 1] = mx.nan
-    mx.eval(a)
-    time_fn(mx.max, a, 0)
-
-
-def time_min():
-    a = mx.random.uniform(shape=(32, 1024, 1024))
-    a[1, 1] = mx.nan
-    mx.eval(a)
-    time_fn(mx.min, a, 0)
-
-
 def time_negative():
     a = mx.random.uniform(shape=(10000, 1000))
     mx.eval(a)
@@ -122,8 +108,6 @@ if __name__ == "__main__":
 
     time_add()
     time_matmul()
-    time_min()
-    time_max()
     time_maximum()
     time_exp()
     time_negative()

docs/src/install.rst

@@ -30,16 +30,6 @@ MLX is also available on conda-forge. To install MLX with conda do:
 
    conda install conda-forge::mlx
 
-CUDA
-^^^^
-
-MLX has a CUDA backend which you can use on any Linux platform with CUDA 12
-and SM 7.0 (Volta) and up. To install MLX with CUDA support, run:
-
-.. code-block:: shell
-
-    pip install mlx-cuda
-
 
 Troubleshooting
 ^^^^^^^^^^^^^^^
@@ -75,8 +65,6 @@ Build Requirements
 Python API
 ^^^^^^^^^^
 
-.. _python install:
-
 To build and install the MLX python library from source, first, clone MLX from
 `its GitHub repo <https://github.com/ml-explore/mlx>`_:
 
@@ -88,20 +76,20 @@ Then simply build and install MLX using pip:
 
 .. code-block:: shell
 
-  pip install .
+  CMAKE_BUILD_PARALLEL_LEVEL=8 pip install .
 
 For developing, install the package with development dependencies, and use an
 editable install:
 
 .. code-block:: shell
 
-  pip install -e ".[dev]"
+  CMAKE_BUILD_PARALLEL_LEVEL=8 pip install -e ".[dev]"
 
 Once the development dependencies are installed, you can build faster with:
 
 .. code-block:: shell
 
- python setup.py build_ext --inplace
+ CMAKE_BUILD_PARALLEL_LEVEL=8 python setup.py build_ext --inplace
 
 Run the tests with:
 
@@ -119,8 +107,6 @@ IDE:
 C++ API
 ^^^^^^^
 
-.. _cpp install:
-
 Currently, MLX must be built and installed from source.
 
 Similarly to the python library, to build and install the MLX C++ library start
@@ -199,7 +185,6 @@ should point to the path to the built metal library.
 
       xcrun -sdk macosx --show-sdk-version
 
-
 Binary Size Minimization
 ~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -228,50 +213,6 @@ be anwywhere from a few hundred millisecond to a few seconds depending on the
 application. Once a kernel is compiled, it will be cached by the system. The
 Metal kernel cache persists across reboots.
 
-Linux
-^^^^^
-
-To build from source on Linux (CPU only), install the BLAS and LAPACK headers.
-For example on Ubuntu, run the following:
-
-.. code-block:: shell
-
-   apt-get update -y
-   apt-get install libblas-dev liblapack-dev liblapacke-dev -y
-
-From here follow the instructions to install either the :ref:`Python <python
-install>` or :ref:`C++ <cpp install>` APIs.
-
-CUDA
-^^^^
-
-To build from source on Linux with CUDA, install the BLAS and LAPACK headers
-and the CUDA toolkit. For example on Ubuntu, run the following:
-
-.. code-block:: shell
-
-   wget https://developer.download.nvidia.com/compute/cuda/repos/ubuntu2204/x86_64/cuda-keyring_1.1-1_all.deb
-   dpkg -i cuda-keyring_1.1-1_all.deb
-   apt-get update -y
-   apt-get -y install cuda-toolkit-12-9
-   apt-get install libblas-dev liblapack-dev liblapacke-dev -y
-
-
-When building either the Python or C++ APIs make sure to pass the cmake flag
-``MLX_BUILD_CUDA=ON``. For example, to build the Python API run:
-
-.. code-block:: shell
-
-  CMAKE_ARGS="-DMLX_BUILD_CUDA=ON" pip install -e ".[dev]"
-
-To build the C++ package run:
-
-.. code-block:: shell
-
-   mkdir -p build && cd build
-   cmake .. -DMLX_BUILD_CUDA=ON && make -j
-
-
 Troubleshooting
 ^^^^^^^^^^^^^^^
 

mlx/CMakeLists.txt

@@ -60,7 +60,16 @@ else()
                  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/backend/cuda/no_cuda.cpp)
 endif()
 
-if(MLX_BUILD_METAL OR MLX_BUILD_CUDA)
+if(MLX_BUILD_ROCM)
+  add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/backend/rocm)
+else()
+  target_sources(mlx
+                 PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/backend/rocm/no_rocm.cpp)
+endif()
+
+if(MLX_BUILD_METAL
+   OR MLX_BUILD_CUDA
+   OR MLX_BUILD_ROCM)
   add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/backend/gpu)
 else()
   add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/backend/no_gpu)

mlx/backend/common/compiled.cpp

@@ -14,8 +14,6 @@ void print_constant(std::ostream& os, const array& x) {
       return print_float_constant<float16_t>(os, x);
     case bfloat16:
       return print_float_constant<bfloat16_t>(os, x);
-    case float64:
-      return print_float_constant<double>(os, x);
     case complex64:
       return print_complex_constant<complex64_t>(os, x);
     case int8:
@@ -52,8 +50,6 @@ std::string get_type_string(Dtype d) {
       return "float16_t";
     case bfloat16:
       return "bfloat16_t";
-    case float64:
-      return "double";
     case complex64:
       return "complex64_t";
     case bool_:

mlx/backend/common/compiled.h

@@ -18,12 +18,8 @@ std::string get_type_string(Dtype d);
 template <typename T>
 void print_float_constant(std::ostream& os, const array& x) {
   auto old_precision = os.precision();
-  if constexpr (std::is_same_v<T, double>) {
-    os << std::setprecision(std::numeric_limits<double>::digits10 + 1);
-  } else {
-    os << std::setprecision(std::numeric_limits<float>::digits10 + 1);
-  }
-  os << x.item<T>() << std::setprecision(old_precision);
+  os << std::setprecision(std::numeric_limits<float>::digits10 + 1)
+     << x.item<T>() << std::setprecision(old_precision);
 }
 
 template <typename T>

mlx/backend/common/matmul.h

@@ -12,11 +12,16 @@ namespace mlx::core {
 inline std::tuple<Shape, Strides, Strides> collapse_batches(
     const array& a,
     const array& b) {
-  if (a.ndim() == 2) {
-    return {{1}, {0}, {0}};
+  // Get and check the shape for the batched dims
+  Shape A_bshape{a.shape().begin(), a.shape().end() - 2};
+  Shape B_bshape{b.shape().begin(), b.shape().end() - 2};
+  if (A_bshape != B_bshape) {
+    std::ostringstream msg;
+    msg << "[matmul] Got matrices with incorrectly broadcasted shapes: " << "A "
+        << a.shape() << ", B " << b.shape() << ".";
+    throw std::runtime_error(msg.str());
   }
 
-  Shape A_bshape{a.shape().begin(), a.shape().end() - 2};
   Strides A_bstride{a.strides().begin(), a.strides().end() - 2};
   Strides B_bstride{b.strides().begin(), b.strides().end() - 2};
 
@@ -37,11 +42,17 @@ inline std::tuple<Shape, Strides, Strides> collapse_batches(
 
 inline std::tuple<Shape, Strides, Strides, Strides>
 collapse_batches(const array& a, const array& b, const array& c) {
-  if (a.ndim() == 2) {
-    return {{1}, {0}, {0}, {0}};
+  // Get and check the shape for the batched dims
+  Shape A_bshape{a.shape().begin(), a.shape().end() - 2};
+  Shape B_bshape{b.shape().begin(), b.shape().end() - 2};
+  Shape C_bshape{c.shape().begin(), c.shape().end() - 2};
+  if (A_bshape != B_bshape || A_bshape != C_bshape) {
+    std::ostringstream msg;
+    msg << "[addmm] Got matrices with incorrectly broadcasted shapes: " << "A "
+        << a.shape() << ", B " << b.shape() << ", B " << c.shape() << ".";
+    throw std::runtime_error(msg.str());
   }
 
-  Shape A_bshape{a.shape().begin(), a.shape().end() - 2};
   Strides A_bstride{a.strides().begin(), a.strides().end() - 2};
   Strides B_bstride{b.strides().begin(), b.strides().end() - 2};
   Strides C_bstride{c.strides().begin(), c.strides().end() - 2};

mlx/backend/common/reduce.cpp

@@ -5,9 +5,11 @@
 namespace mlx::core {
 
 std::pair<Shape, Strides> shapes_without_reduction_axes(
-    Shape shape,
-    Strides strides,
+    const array& x,
     const std::vector<int>& axes) {
+  auto shape = x.shape();
+  auto strides = x.strides();
+
   for (int i = axes.size() - 1; i >= 0; i--) {
     int a = axes[i];
     shape.erase(shape.begin() + a);
@@ -17,15 +19,6 @@ std::pair<Shape, Strides> shapes_without_reduction_axes(
   return std::make_pair(shape, strides);
 }
 
-std::pair<Shape, Strides> shapes_without_reduction_axes(
-    const array& x,
-    const std::vector<int>& axes) {
-  auto shape = x.shape();
-  auto strides = x.strides();
-  return shapes_without_reduction_axes(
-      std::move(shape), std::move(strides), axes);
-}
-
 ReductionPlan get_reduction_plan(const array& x, const std::vector<int>& axes) {
   // The data is all there and we are reducing over everything
   if (x.size() == x.data_size() && axes.size() == x.ndim() &&

mlx/backend/common/reduce.h

@@ -51,9 +51,5 @@ ReductionPlan get_reduction_plan(const array& x, const std::vector<int>& axes);
 std::pair<Shape, Strides> shapes_without_reduction_axes(
     const array& x,
     const std::vector<int>& axes);
-std::pair<Shape, Strides> shapes_without_reduction_axes(
-    Shape shape,
-    Strides strides,
-    const std::vector<int>& axes);
 
 } // namespace mlx::core

mlx/backend/common/utils.cpp

@@ -199,15 +199,12 @@ Dims get_2d_grid_dims_common(
       }
     }
   }
-  if (grid_y > UINT32_MAX || grid_x > UINT32_MAX) {
+  if (grid_y > UINT32_MAX || grid_x > UINT32_MAX || divisor > 1) {
     throw std::runtime_error("Unable to safely factor shape.");
   }
   if (grid_y > grid_x) {
     std::swap(grid_x, grid_y);
   }
-  if (divisor > 1) {
-    grid_x = ((grid_x + divisor - 1) / divisor) * divisor;
-  }
   return std::make_tuple(
       static_cast<uint32_t>(grid_x), static_cast<uint32_t>(grid_y), 1);
 }

mlx/backend/cpu/masked_mm.cpp

@@ -6,7 +6,6 @@
 #include "mlx/backend/common/utils.h"
 #include "mlx/backend/cpu/copy.h"
 #include "mlx/backend/cpu/encoder.h"
-#include "mlx/backend/cpu/gemm.h"
 #include "mlx/backend/cpu/lapack.h"
 #include "mlx/primitives.h"
 
@@ -53,58 +52,6 @@ inline void mask_matrix(
   }
 }
 
-template <typename T>
-inline void segmented_mm(
-    const T* a,
-    const T* b,
-    const uint32_t* segments,
-    T* out,
-    bool a_transposed,
-    bool b_transposed,
-    size_t lda,
-    size_t ldb,
-    const Shape& a_shape,
-    const Strides& a_strides,
-    const Shape& b_shape,
-    const Strides& b_strides,
-    size_t num_segments,
-    const Shape& segments_shape,
-    const Strides& segments_strides) {
-  int ndim = a_shape.size();
-  Shape a_copy = a_shape;
-  Shape b_copy = b_shape;
-  int32_t M = a_copy[ndim - 2];
-  int32_t N = b_copy[ndim - 1];
-  for (int i = 0; i < num_segments; i++) {
-    uint32_t k_start =
-        segments[elem_to_loc(2 * i, segments_shape, segments_strides)];
-    uint32_t k_end =
-        segments[elem_to_loc(2 * i + 1, segments_shape, segments_strides)];
-    if (k_end <= k_start) {
-      std::fill_n(out + i * M * N, M * N, T(0));
-      continue;
-    }
-    a_copy[ndim - 1] = k_end - k_start;
-    b_copy[ndim - 2] = k_end - k_start;
-    matmul<T>(
-        a + k_start * a_strides[ndim - 1],
-        b + k_start * b_strides[ndim - 2],
-        out + i * M * N,
-        a_transposed,
-        b_transposed,
-        lda,
-        ldb,
-        N,
-        1.0,
-        0.0,
-        1,
-        a_copy,
-        a_strides,
-        b_copy,
-        b_strides);
-  }
-}
-
 } // namespace
 
 void BlockMaskedMM::eval_cpu(const std::vector<array>& inputs, array& out) {
@@ -490,121 +437,4 @@ void GatherMM::eval_cpu(const std::vector<array>& inputs, array& out) {
   encoder.add_temporaries(std::move(temps));
 }
 
-void SegmentedMM::eval_cpu(const std::vector<array>& inputs, array& out) {
-  out.set_data(allocator::malloc(out.nbytes()));
-
-  auto& s = stream();
-  auto& encoder = cpu::get_command_encoder(stream());
-  auto check_transpose = [&s, &encoder](const array& x) {
-    auto stx = x.strides()[x.ndim() - 2];
-    auto sty = x.strides()[x.ndim() - 1];
-    if (stx == x.shape(-1) && sty == 1) {
-      return std::make_tuple(false, stx, x);
-    } else if (stx == 1 && sty == x.shape(-2)) {
-      return std::make_tuple(true, sty, x);
-    } else {
-      array xc(x.shape(), x.dtype(), nullptr, {});
-      copy(x, xc, CopyType::General, s);
-      encoder.add_temporary(xc);
-      int64_t stx = x.shape(-1);
-      return std::make_tuple(false, stx, xc);
-    }
-  };
-
-  auto [a_transposed, lda, a] = check_transpose(inputs[0]);
-  auto [b_transposed, ldb, b] = check_transpose(inputs[1]);
-  auto& segments = inputs[2];
-
-  encoder.set_input_array(a);
-  encoder.set_input_array(b);
-  encoder.set_input_array(segments);
-  encoder.set_output_array(out);
-  encoder.dispatch([a = array::unsafe_weak_copy(a),
-                    b = array::unsafe_weak_copy(b),
-                    segments = array::unsafe_weak_copy(segments),
-                    out_ptr = out.data<void>(),
-                    a_transposed = a_transposed,
-                    b_transposed = b_transposed,
-                    lda = lda,
-                    ldb = ldb]() {
-    switch (a.dtype()) {
-      case float64:
-        segmented_mm<double>(
-            a.data<double>(),
-            b.data<double>(),
-            segments.data<uint32_t>(),
-            static_cast<double*>(out_ptr),
-            a_transposed,
-            b_transposed,
-            lda,
-            ldb,
-            a.shape(),
-            a.strides(),
-            b.shape(),
-            b.strides(),
-            segments.size() / 2,
-            segments.shape(),
-            segments.strides());
-        break;
-      case float32:
-        segmented_mm<float>(
-            a.data<float>(),
-            b.data<float>(),
-            segments.data<uint32_t>(),
-            static_cast<float*>(out_ptr),
-            a_transposed,
-            b_transposed,
-            lda,
-            ldb,
-            a.shape(),
-            a.strides(),
-            b.shape(),
-            b.strides(),
-            segments.size() / 2,
-            segments.shape(),
-            segments.strides());
-        break;
-      case float16:
-        segmented_mm<float16_t>(
-            a.data<float16_t>(),
-            b.data<float16_t>(),
-            segments.data<uint32_t>(),
-            static_cast<float16_t*>(out_ptr),
-            a_transposed,
-            b_transposed,
-            lda,
-            ldb,
-            a.shape(),
-            a.strides(),
-            b.shape(),
-            b.strides(),
-            segments.size() / 2,
-            segments.shape(),
-            segments.strides());
-        break;
-      case bfloat16:
-        segmented_mm<bfloat16_t>(
-            a.data<bfloat16_t>(),
-            b.data<bfloat16_t>(),
-            segments.data<uint32_t>(),
-            static_cast<bfloat16_t*>(out_ptr),
-            a_transposed,
-            b_transposed,
-            lda,
-            ldb,
-            a.shape(),
-            a.strides(),
-            b.shape(),
-            b.strides(),
-            segments.size() / 2,
-            segments.shape(),
-            segments.strides());
-        break;
-      default:
-        throw std::invalid_argument(
-            "Segmented mm supports only real float types.");
-    }
-  });
-}
-
 } // namespace mlx::core

mlx/backend/cpu/reduce.cpp

@@ -325,15 +325,7 @@ struct MaxReduce {
   };
 
   template <int N, typename T>
-  std::enable_if_t<std::is_integral_v<T>, T> operator()(simd::Simd<T, N> x) {
-    return simd::max(x);
-  };
-
-  template <int N, typename T>
-  std::enable_if_t<!std::is_integral_v<T>, T> operator()(simd::Simd<T, N> x) {
-    if (simd::any(x != x)) {
-      return static_cast<T>(NAN);
-    }
+  T operator()(simd::Simd<T, N> x) {
     return simd::max(x);
   };
 };
@@ -350,15 +342,7 @@ struct MinReduce {
   };
 
   template <int N, typename T>
-  std::enable_if_t<std::is_integral_v<T>, T> operator()(simd::Simd<T, N> x) {
-    return simd::min(x);
-  };
-
-  template <int N, typename T>
-  std::enable_if_t<!std::is_integral_v<T>, T> operator()(simd::Simd<T, N> x) {
-    if (simd::any(x != x)) {
-      return static_cast<T>(NAN);
-    }
+  T operator()(simd::Simd<T, N> x) {
     return simd::min(x);
   };
 };
@@ -543,10 +527,10 @@ void Reduce::eval_cpu(const std::vector<array>& inputs, array& out) {
             reduce_dispatch_min_max<uint64_t>(in, out, reduce_type_, axes_);
             break;
           case int8:
-            reduce_dispatch_min_max<int8_t>(in, out, reduce_type_, axes_);
+            reduce_dispatch_min_max<uint8_t>(in, out, reduce_type_, axes_);
             break;
           case int16:
-            reduce_dispatch_min_max<int16_t>(in, out, reduce_type_, axes_);
+            reduce_dispatch_min_max<uint16_t>(in, out, reduce_type_, axes_);
             break;
           case int32:
             reduce_dispatch_min_max<int32_t>(in, out, reduce_type_, axes_);

mlx/backend/cuda/CMakeLists.txt

@@ -8,7 +8,6 @@ target_sources(
   PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/allocator.cpp
           ${CMAKE_CURRENT_SOURCE_DIR}/arg_reduce.cu
           ${CMAKE_CURRENT_SOURCE_DIR}/binary.cu
-          ${CMAKE_CURRENT_SOURCE_DIR}/binary_two.cu
           ${CMAKE_CURRENT_SOURCE_DIR}/compiled.cpp
           ${CMAKE_CURRENT_SOURCE_DIR}/copy.cu
           ${CMAKE_CURRENT_SOURCE_DIR}/copy/copy_contiguous.cu
@@ -29,13 +28,11 @@ target_sources(
           ${CMAKE_CURRENT_SOURCE_DIR}/primitives.cu
           ${CMAKE_CURRENT_SOURCE_DIR}/random.cu
           ${CMAKE_CURRENT_SOURCE_DIR}/reduce.cu
-          ${CMAKE_CURRENT_SOURCE_DIR}/reduce/all_reduce.cu
           ${CMAKE_CURRENT_SOURCE_DIR}/reduce/col_reduce.cu
-          ${CMAKE_CURRENT_SOURCE_DIR}/reduce/init_reduce.cu
           ${CMAKE_CURRENT_SOURCE_DIR}/reduce/row_reduce.cu
+          ${CMAKE_CURRENT_SOURCE_DIR}/reduce/segmented_reduce.cu
           ${CMAKE_CURRENT_SOURCE_DIR}/rms_norm.cu
           ${CMAKE_CURRENT_SOURCE_DIR}/rope.cu
-          ${CMAKE_CURRENT_SOURCE_DIR}/scan.cu
           ${CMAKE_CURRENT_SOURCE_DIR}/slicing.cpp
           ${CMAKE_CURRENT_SOURCE_DIR}/softmax.cu
           ${CMAKE_CURRENT_SOURCE_DIR}/sort.cu
@@ -68,11 +65,6 @@ target_include_directories(mlx PRIVATE "${CMAKE_CURRENT_BINARY_DIR}/gen")
 target_compile_options(mlx
                        PRIVATE "$<$<COMPILE_LANGUAGE:CUDA>:--extended-lambda>")
 
-# Enable calling host constexpr functions from device. This is needed because
-# the constexpr version of isnan is host only.
-target_compile_options(
-  mlx PRIVATE "$<$<COMPILE_LANGUAGE:CUDA>:--expt-relaxed-constexpr>")
-
 # CUDA 12.8 emits warning #20280-D for copy kernels which is a false positive.
 # Explicitly pass this flag to suppress the warning, it is safe to set it to
 # true but the warning wouldn't be suppressed.

mlx/backend/cuda/allocator.cpp

@@ -3,7 +3,6 @@
 #include "mlx/backend/cuda/allocator.h"
 #include "mlx/backend/cuda/utils.h"
 #include "mlx/backend/cuda/worker.h"
-#include "mlx/utils.h"
 
 #include <cuda_runtime.h>
 #include <fmt/format.h>
@@ -15,11 +14,9 @@ namespace mlx::core {
 
 namespace cu {
 
-constexpr int page_size = 16384;
-
 CudaAllocator::CudaAllocator()
     : buffer_cache_(
-          page_size,
+          getpagesize(),
           [](CudaBuffer* buf) { return buf->size; },
           [this](CudaBuffer* buf) {
             cuda_free(buf->data);
@@ -34,14 +31,7 @@ CudaAllocator::CudaAllocator()
 
 Buffer CudaAllocator::malloc(size_t size) {
   // Find available buffer from cache.
-  auto orig_size = size;
   std::unique_lock lock(mutex_);
-  if (size < page_size) {
-    size = next_power_of_2(size);
-  } else {
-    size = page_size * ((size + page_size - 1) / page_size);
-  }
-
   CudaBuffer* buf = buffer_cache_.reuse_from_cache(size);
   if (!buf) {
     // If we have a lot of memory pressure or are over the maximum cache size,
@@ -116,6 +106,7 @@ void CudaAllocator::cuda_free(void* buf) {
       return;
     }
   }
+
   cudaFree(buf);
 }
 

mlx/backend/cuda/arg_reduce.cu

@@ -1,7 +1,6 @@
 // Copyright © 2025 Apple Inc.
 #include "mlx/backend/common/utils.h"
 #include "mlx/backend/cuda/device.h"
-#include "mlx/backend/cuda/device/fp16_math.cuh"
 #include "mlx/backend/cuda/iterators/strided_iterator.cuh"
 #include "mlx/backend/cuda/kernel_utils.cuh"
 #include "mlx/dtype_utils.h"
@@ -152,29 +151,36 @@ void ArgReduce::eval_gpu(const std::vector<array>& inputs, array& out) {
   auto& encoder = cu::get_command_encoder(s);
   encoder.set_input_array(in);
   encoder.set_output_array(out);
-  dispatch_real_types(in.dtype(), "ArgReduce", [&](auto type_tag) {
-    using T = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-    constexpr uint32_t N_READS = 4;
-    dispatch_block_dim(cuda::ceil_div(axis_size, N_READS), [&](auto block_dim) {
-      dim3 num_blocks = get_2d_grid_dims(out.shape(), out.strides());
-      auto kernel =
-          cu::arg_reduce_general<T, cu::ArgMax<T>, block_dim(), N_READS>;
-      if (reduce_type_ == ArgReduce::ArgMin) {
-        kernel = cu::arg_reduce_general<T, cu::ArgMin<T>, block_dim(), N_READS>;
-      }
-      encoder.add_kernel_node(
-          kernel,
-          num_blocks,
-          block_dim(),
-          in.data<T>(),
-          out.data<uint32_t>(),
-          out.size(),
-          const_param(shape),
-          const_param(in_strides),
-          const_param(out_strides),
-          ndim,
-          axis_stride,
-          axis_size);
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_REAL_TYPES_CHECKED(in.dtype(), "ArgReduce", CTYPE, {
+      using InType = cuda_type_t<CTYPE>;
+      constexpr uint32_t N_READS = 4;
+      MLX_SWITCH_BLOCK_DIM(cuda::ceil_div(axis_size, N_READS), BLOCK_DIM, {
+        dim3 num_blocks = get_2d_grid_dims(out.shape(), out.strides());
+        dim3 block_dims{BLOCK_DIM, 1, 1};
+        auto kernel = &cu::arg_reduce_general<
+            InType,
+            cu::ArgMax<InType>,
+            BLOCK_DIM,
+            N_READS>;
+        if (reduce_type_ == ArgReduce::ArgMin) {
+          kernel = &cu::arg_reduce_general<
+              InType,
+              cu::ArgMin<InType>,
+              BLOCK_DIM,
+              N_READS>;
+        }
+        kernel<<<num_blocks, block_dims, 0, stream>>>(
+            in.data<InType>(),
+            out.data<uint32_t>(),
+            out.size(),
+            const_param(shape),
+            const_param(in_strides),
+            const_param(out_strides),
+            ndim,
+            axis_stride,
+            axis_size);
+      });
     });
   });
 }

mlx/backend/cuda/binary.cu

@@ -17,86 +17,35 @@ namespace cu {
 
 namespace cg = cooperative_groups;
 
-template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
+template <typename Op, typename In, typename Out, typename IdxT>
 __global__ void binary_ss(const In* a, const In* b, Out* out, IdxT size) {
   IdxT index = cg::this_grid().thread_rank();
-
-  if ((index + 1) * N_READS > size) {
-    for (int i = index * N_READS; i < size; ++i) {
-      out[i] = Op{}(a[0], b[0]);
-    }
-  } else {
-    AlignedVector<Out, N_READS> out_vec;
-#pragma unroll
-    for (int i = 0; i < N_READS; ++i) {
-      out_vec.val[i] = Op{}(a[0], b[0]);
-    }
-
-    store_vector<N_READS>(out, index, out_vec);
+  if (index < size) {
+    out[index] = Op{}(a[0], b[0]);
   }
 }
 
-template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
+template <typename Op, typename In, typename Out, typename IdxT>
 __global__ void binary_sv(const In* a, const In* b, Out* out, IdxT size) {
   IdxT index = cg::this_grid().thread_rank();
-
-  if ((index + 1) * N_READS > size) {
-    for (IdxT i = index * N_READS; i < size; ++i) {
-      out[i] = Op{}(a[0], b[i]);
-    }
-  } else {
-    auto b_vec = load_vector<N_READS>(b, index);
-
-    AlignedVector<Out, N_READS> out_vec;
-#pragma unroll
-    for (int i = 0; i < N_READS; ++i) {
-      out_vec.val[i] = Op{}(a[0], b_vec.val[i]);
-    }
-
-    store_vector<N_READS>(out, index, out_vec);
+  if (index < size) {
+    out[index] = Op{}(a[0], b[index]);
   }
 }
 
-template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
+template <typename Op, typename In, typename Out, typename IdxT>
 __global__ void binary_vs(const In* a, const In* b, Out* out, IdxT size) {
   IdxT index = cg::this_grid().thread_rank();
-
-  if ((index + 1) * N_READS > size) {
-    for (IdxT i = index * N_READS; i < size; ++i) {
-      out[i] = Op{}(a[i], b[0]);
-    }
-  } else {
-    auto a_vec = load_vector<N_READS>(a, index);
-
-    AlignedVector<Out, N_READS> out_vec;
-#pragma unroll
-    for (int i = 0; i < N_READS; ++i) {
-      out_vec.val[i] = Op{}(a_vec.val[i], b[0]);
-    }
-
-    store_vector<N_READS>(out, index, out_vec);
+  if (index < size) {
+    out[index] = Op{}(a[index], b[0]);
   }
 }
 
-template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
+template <typename Op, typename In, typename Out, typename IdxT>
 __global__ void binary_vv(const In* a, const In* b, Out* out, IdxT size) {
   IdxT index = cg::this_grid().thread_rank();
-
-  if ((index + 1) * N_READS > size) {
-    for (IdxT i = index * N_READS; i < size; ++i) {
-      out[i] = Op{}(a[i], b[i]);
-    }
-  } else {
-    auto a_vec = load_vector<N_READS>(a, index);
-    auto b_vec = load_vector<N_READS>(b, index);
-
-    AlignedVector<Out, N_READS> out_vec;
-#pragma unroll
-    for (int i = 0; i < N_READS; ++i) {
-      out_vec.val[i] = Op{}(a_vec.val[i], b_vec.val[i]);
-    }
-
-    store_vector<N_READS>(out, index, out_vec);
+  if (index < size) {
+    out[index] = Op{}(a[index], b[index]);
   }
 }
 
@@ -176,12 +125,13 @@ constexpr bool supports_binary_op() {
 template <typename Op>
 void binary_op_gpu_inplace(
     const std::vector<array>& inputs,
-    array& out,
+    std::vector<array>& outputs,
     std::string_view op,
     const Stream& s) {
   assert(inputs.size() > 1);
   const auto& a = inputs[0];
   const auto& b = inputs[1];
+  auto& out = outputs[0];
   if (out.size() == 0) {
     return;
   }
@@ -190,103 +140,99 @@ void binary_op_gpu_inplace(
   encoder.set_input_array(a);
   encoder.set_input_array(b);
   encoder.set_output_array(out);
-  dispatch_all_types(a.dtype(), [&](auto in_type_tag) {
-    dispatch_all_types(out.dtype(), [&](auto out_type_tag) {
-      using CTYPE_IN = MLX_GET_TYPE(in_type_tag);
-      using CTYPE_OUT = MLX_GET_TYPE(out_type_tag);
-      if constexpr (cu::supports_binary_op<Op, CTYPE_IN, CTYPE_OUT>()) {
-        using InType = cuda_type_t<CTYPE_IN>;
-        using OutType = cuda_type_t<CTYPE_OUT>;
-        auto bopt = get_binary_op_type(a, b);
-        if (bopt == BinaryOpType::General) {
-          dispatch_bool(
-              a.data_size() > INT32_MAX || b.data_size() > INT32_MAX ||
-                  out.data_size() > INT32_MAX,
-              [&](auto large) {
-                using IdxT = std::conditional_t<large(), int64_t, int32_t>;
-                Shape shape;
-                std::vector<Strides> strides;
-                std::tie(shape, strides) = collapse_contiguous_dims(a, b, out);
-                auto& a_strides = strides[0];
-                auto& b_strides = strides[1];
-                int ndim = shape.size();
-                if (ndim <= 3) {
-                  dispatch_1_2_3(ndim, [&](auto dims_constant) {
-                    auto kernel = cu::
-                        binary_g_nd<Op, InType, OutType, IdxT, dims_constant()>;
-                    auto [num_blocks, block_dims] =
-                        get_launch_args(kernel, out, large());
-                    encoder.add_kernel_node(
-                        kernel,
-                        num_blocks,
-                        block_dims,
-                        a.data<InType>(),
-                        b.data<InType>(),
-                        out.data<OutType>(),
-                        out.size(),
-                        const_param<dims_constant()>(shape),
-                        const_param<dims_constant()>(a_strides),
-                        const_param<dims_constant()>(b_strides));
-                  });
-                } else {
-                  auto kernel = cu::binary_g<Op, InType, OutType, IdxT>;
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_ALL_TYPES(a.dtype(), CTYPE_IN, {
+      MLX_SWITCH_ALL_TYPES(out.dtype(), CTYPE_OUT, {
+        if constexpr (cu::supports_binary_op<Op, CTYPE_IN, CTYPE_OUT>()) {
+          using InType = cuda_type_t<CTYPE_IN>;
+          using OutType = cuda_type_t<CTYPE_OUT>;
+
+          auto bopt = get_binary_op_type(a, b);
+          if (bopt == BinaryOpType::General) {
+            auto [shape, strides] = collapse_contiguous_dims(a, b, out);
+            auto& a_strides = strides[0];
+            auto& b_strides = strides[1];
+            bool large = a.data_size() > INT32_MAX ||
+                b.data_size() > INT32_MAX || out.data_size() > INT32_MAX;
+            MLX_SWITCH_BOOL(large, LARGE, {
+              using IdxT = std::conditional_t<LARGE, int64_t, int32_t>;
+              int ndim = shape.size();
+              if (ndim <= 3) {
+                MLX_SWITCH_1_2_3(ndim, NDIM, {
+                  auto kernel =
+                      &cu::binary_g_nd<Op, InType, OutType, IdxT, NDIM>;
                   auto [num_blocks, block_dims] =
-                      get_launch_args(kernel, out, large());
-                  encoder.add_kernel_node(
-                      kernel,
-                      num_blocks,
-                      block_dims,
+                      get_launch_args(kernel, out, large);
+                  kernel<<<num_blocks, block_dims, 0, stream>>>(
                       a.data<InType>(),
                       b.data<InType>(),
                       out.data<OutType>(),
                       out.size(),
-                      const_param(shape),
-                      const_param(a_strides),
-                      const_param(b_strides),
-                      ndim);
-                }
-              });
+                      const_param<NDIM>(shape),
+                      const_param<NDIM>(a_strides),
+                      const_param<NDIM>(b_strides));
+                });
+              } else {
+                auto kernel = cu::binary_g<Op, InType, OutType, IdxT>;
+                auto [num_blocks, block_dims] =
+                    get_launch_args(kernel, out, large);
+                kernel<<<num_blocks, block_dims, 0, stream>>>(
+                    a.data<InType>(),
+                    b.data<InType>(),
+                    out.data<OutType>(),
+                    out.size(),
+                    const_param(shape),
+                    const_param(a_strides),
+                    const_param(b_strides),
+                    ndim);
+              }
+            });
+          } else {
+            MLX_SWITCH_BOOL(out.data_size() > UINT32_MAX, LARGE, {
+              using IdxT = std::conditional_t<LARGE, int64_t, uint32_t>;
+              auto kernel = cu::binary_ss<Op, InType, OutType, IdxT>;
+              if (bopt == BinaryOpType::ScalarVector) {
+                kernel = cu::binary_sv<Op, InType, OutType, IdxT>;
+              } else if (bopt == BinaryOpType::VectorScalar) {
+                kernel = cu::binary_vs<Op, InType, OutType, IdxT>;
+              } else if (bopt == BinaryOpType::VectorVector) {
+                kernel = cu::binary_vv<Op, InType, OutType, IdxT>;
+              }
+              auto [num_blocks, block_dims] = get_launch_args(
+                  kernel, out.data_size(), out.shape(), out.strides(), LARGE);
+              kernel<<<num_blocks, block_dims, 0, stream>>>(
+                  a.data<InType>(),
+                  b.data<InType>(),
+                  out.data<OutType>(),
+                  out.data_size());
+            });
+          }
         } else {
-          dispatch_bool(out.data_size() > UINT32_MAX, [&](auto large) {
-            using IdxT = std::conditional_t<large(), int64_t, uint32_t>;
-            // TODO: Choose optimized value based on type size.
-            constexpr int N_READS = 4;
-            auto kernel = cu::binary_ss<Op, InType, OutType, IdxT, N_READS>;
-            if (bopt == BinaryOpType::ScalarVector) {
-              kernel = cu::binary_sv<Op, InType, OutType, IdxT, N_READS>;
-            } else if (bopt == BinaryOpType::VectorScalar) {
-              kernel = cu::binary_vs<Op, InType, OutType, IdxT, N_READS>;
-            } else if (bopt == BinaryOpType::VectorVector) {
-              kernel = cu::binary_vv<Op, InType, OutType, IdxT, N_READS>;
-            }
-            auto [num_blocks, block_dims] = get_launch_args(
-                kernel,
-                out.data_size(),
-                out.shape(),
-                out.strides(),
-                large(),
-                N_READS);
-            encoder.add_kernel_node(
-                kernel,
-                num_blocks,
-                block_dims,
-                a.data<InType>(),
-                b.data<InType>(),
-                out.data<OutType>(),
-                out.data_size());
-          });
+          throw std::runtime_error(fmt::format(
+              "Can not do binary op {} on inputs of {} with result of {}.",
+              op,
+              dtype_to_string(a.dtype()),
+              dtype_to_string(out.dtype())));
         }
-      } else {
-        throw std::runtime_error(fmt::format(
-            "Can not do binary op {} on inputs of {} with result of {}.",
-            op,
-            dtype_to_string(a.dtype()),
-            dtype_to_string(out.dtype())));
-      }
+      });
     });
   });
 }
 
+template <typename Op>
+void binary_op_gpu(
+    const std::vector<array>& inputs,
+    std::vector<array>& outputs,
+    std::string_view op,
+    const Stream& s) {
+  auto& a = inputs[0];
+  auto& b = inputs[1];
+  auto bopt = get_binary_op_type(a, b);
+  set_binary_op_output_data(a, b, outputs[0], bopt);
+  set_binary_op_output_data(a, b, outputs[1], bopt);
+  binary_op_gpu_inplace<Op>(inputs, outputs, op, s);
+}
+
 template <typename Op>
 void binary_op_gpu(
     const std::vector<array>& inputs,
@@ -297,7 +243,8 @@ void binary_op_gpu(
   auto& b = inputs[1];
   auto bopt = get_binary_op_type(a, b);
   set_binary_op_output_data(a, b, out, bopt);
-  binary_op_gpu_inplace<Op>(inputs, out, op, s);
+  std::vector<array> outputs{out};
+  binary_op_gpu_inplace<Op>(inputs, outputs, op, s);
 }
 
 #define BINARY_GPU(func)                                                 \
@@ -307,6 +254,14 @@ void binary_op_gpu(
     binary_op_gpu<cu::func>(inputs, out, get_primitive_string(this), s); \
   }
 
+#define BINARY_GPU_MULTI(func)                                               \
+  void func::eval_gpu(                                                       \
+      const std::vector<array>& inputs, std::vector<array>& outputs) {       \
+    nvtx3::scoped_range r(#func "::eval_gpu");                               \
+    auto& s = outputs[0].primitive().stream();                               \
+    binary_op_gpu<cu::func>(inputs, outputs, get_primitive_string(this), s); \
+  }
+
 BINARY_GPU(Add)
 BINARY_GPU(ArcTan2)
 BINARY_GPU(Divide)

mlx/backend/cuda/binary_two.cu

@@ -1,335 +0,0 @@
-// Copyright © 2025 Apple Inc.
-
-#include "mlx/backend/common/binary.h"
-#include "mlx/backend/cuda/device.h"
-#include "mlx/backend/cuda/device/binary_ops.cuh"
-#include "mlx/backend/cuda/device/cucomplex_math.cuh"
-#include "mlx/backend/cuda/kernel_utils.cuh"
-#include "mlx/dtype_utils.h"
-#include "mlx/primitives.h"
-
-#include <cooperative_groups.h>
-#include <nvtx3/nvtx3.hpp>
-
-namespace mlx::core {
-
-namespace cu {
-
-namespace cg = cooperative_groups;
-
-template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
-__global__ void
-binary_two_ss(const In* a, const In* b, Out* out_a, Out* out_b, IdxT size) {
-  IdxT index = cg::this_grid().thread_rank();
-
-  if ((index + 1) * N_READS > size) {
-    for (IdxT i = index * N_READS; i < size; ++i) {
-      auto out = Op{}(a[0], b[0]);
-      out_a[i] = out[0];
-      out_b[i] = out[1];
-    }
-  } else {
-    AlignedVector<Out, N_READS> out_a_vec;
-    AlignedVector<Out, N_READS> out_b_vec;
-#pragma unroll
-    for (int i = 0; i < N_READS; ++i) {
-      auto out = Op{}(a[0], b[0]);
-      out_a_vec.val[i] = out[0];
-      out_b_vec.val[i] = out[1];
-    }
-
-    store_vector<N_READS>(out_a, index, out_a_vec);
-    store_vector<N_READS>(out_b, index, out_b_vec);
-  }
-}
-
-template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
-__global__ void
-binary_two_sv(const In* a, const In* b, Out* out_a, Out* out_b, IdxT size) {
-  IdxT index = cg::this_grid().thread_rank();
-
-  if ((index + 1) * N_READS > size) {
-    for (IdxT i = index * N_READS; i < size; ++i) {
-      auto out = Op{}(a[0], b[i]);
-      out_a[i] = out[0];
-      out_b[i] = out[1];
-    }
-  } else {
-    auto b_vec = load_vector<N_READS>(b, index);
-
-    AlignedVector<Out, N_READS> out_a_vec;
-    AlignedVector<Out, N_READS> out_b_vec;
-#pragma unroll
-    for (int i = 0; i < N_READS; ++i) {
-      auto out = Op{}(a[0], b_vec.val[i]);
-      out_a_vec.val[i] = out[0];
-      out_b_vec.val[i] = out[1];
-    }
-
-    store_vector<N_READS>(out_a, index, out_a_vec);
-    store_vector<N_READS>(out_b, index, out_b_vec);
-  }
-}
-
-template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
-__global__ void
-binary_two_vs(const In* a, const In* b, Out* out_a, Out* out_b, IdxT size) {
-  IdxT index = cg::this_grid().thread_rank();
-
-  if ((index + 1) * N_READS > size) {
-    for (IdxT i = index * N_READS; i < size; ++i) {
-      auto out = Op{}(a[i], b[0]);
-      out_a[i] = out[0];
-      out_b[i] = out[1];
-    }
-  } else {
-    auto a_vec = load_vector<N_READS>(a, index);
-
-    AlignedVector<Out, N_READS> out_a_vec;
-    AlignedVector<Out, N_READS> out_b_vec;
-#pragma unroll
-    for (int i = 0; i < N_READS; ++i) {
-      auto out = Op{}(a_vec.val[i], b[0]);
-      out_a_vec.val[i] = out[0];
-      out_b_vec.val[i] = out[1];
-    }
-
-    store_vector<N_READS>(out_a, index, out_a_vec);
-    store_vector<N_READS>(out_b, index, out_b_vec);
-  }
-}
-
-template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
-__global__ void
-binary_two_vv(const In* a, const In* b, Out* out_a, Out* out_b, IdxT size) {
-  IdxT index = cg::this_grid().thread_rank();
-
-  if ((index + 1) * N_READS > size) {
-    for (IdxT i = index * N_READS; i < size; ++i) {
-      auto out = Op{}(a[i], b[i]);
-      out_a[i] = out[0];
-      out_b[i] = out[1];
-    }
-  } else {
-    auto a_vec = load_vector<N_READS>(a, index);
-    auto b_vec = load_vector<N_READS>(b, index);
-
-    AlignedVector<Out, N_READS> out_a_vec;
-    AlignedVector<Out, N_READS> out_b_vec;
-#pragma unroll
-    for (int i = 0; i < N_READS; ++i) {
-      auto out = Op{}(a_vec.val[i], b_vec.val[i]);
-      out_a_vec.val[i] = out[0];
-      out_b_vec.val[i] = out[1];
-    }
-
-    store_vector<N_READS>(out_a, index, out_a_vec);
-    store_vector<N_READS>(out_b, index, out_b_vec);
-  }
-}
-
-template <typename Op, typename In, typename Out, typename IdxT, int NDIM>
-__global__ void binary_two_g_nd(
-    const In* a,
-    const In* b,
-    Out* out_a,
-    Out* out_b,
-    IdxT size,
-    const __grid_constant__ cuda::std::array<int32_t, NDIM> shape,
-    const __grid_constant__ cuda::std::array<int64_t, NDIM> a_strides,
-    const __grid_constant__ cuda::std::array<int64_t, NDIM> b_strides) {
-  IdxT index = cg::this_grid().thread_rank();
-  if (index < size) {
-    auto [a_idx, b_idx] = elem_to_loc_nd<NDIM>(
-        index, shape.data(), a_strides.data(), b_strides.data());
-    auto out = Op{}(a[a_idx], b[b_idx]);
-    out_a[index] = out[0];
-    out_b[index] = out[1];
-  }
-}
-
-template <typename Op, typename In, typename Out, typename IdxT>
-__global__ void binary_two_g(
-    const In* a,
-    const In* b,
-    Out* out_a,
-    Out* out_b,
-    IdxT size,
-    const __grid_constant__ Shape shape,
-    const __grid_constant__ Strides a_strides,
-    const __grid_constant__ Strides b_strides,
-    int ndim) {
-  IdxT index = cg::this_grid().thread_rank();
-  if (index < size) {
-    auto [a_idx, b_idx] = elem_to_loc_4d(
-        index, shape.data(), a_strides.data(), b_strides.data(), ndim);
-    auto out = Op{}(a[a_idx], b[b_idx]);
-    out_a[index] = out[0];
-    out_b[index] = out[1];
-  }
-}
-
-template <typename Op, typename In, typename Out>
-constexpr bool supports_binary_two_op() {
-  if (std::is_same_v<Op, DivMod>) {
-    return std::is_same_v<In, Out> &&
-        (std::is_integral_v<Out> || is_floating_v<Out>);
-  }
-  return false;
-}
-
-} // namespace cu
-
-template <typename Op>
-void binary_two_op_gpu_inplace(
-    const std::vector<array>& inputs,
-    std::vector<array>& outputs,
-    std::string_view op,
-    const Stream& s) {
-  assert(inputs.size() > 1);
-  const auto& a = inputs[0];
-  const auto& b = inputs[1];
-  auto& out_a = outputs[0];
-  auto& out_b = outputs[1];
-  auto bopt = get_binary_op_type(a, b);
-  set_binary_op_output_data(a, b, out_a, bopt);
-  set_binary_op_output_data(a, b, out_b, bopt);
-
-  if (out_a.size() == 0) {
-    return;
-  }
-
-  auto& encoder = cu::get_command_encoder(s);
-  encoder.set_input_array(a);
-  encoder.set_input_array(b);
-  encoder.set_output_array(out_a);
-  encoder.set_output_array(out_b);
-  dispatch_all_types(a.dtype(), [&](auto in_type_tag) {
-    dispatch_all_types(out_a.dtype(), [&](auto out_type_tag) {
-      using CTYPE_IN = MLX_GET_TYPE(in_type_tag);
-      using CTYPE_OUT = MLX_GET_TYPE(out_type_tag);
-      if constexpr (cu::supports_binary_two_op<Op, CTYPE_IN, CTYPE_OUT>()) {
-        using InType = cuda_type_t<CTYPE_IN>;
-        using OutType = cuda_type_t<CTYPE_OUT>;
-
-        auto bopt = get_binary_op_type(a, b);
-        if (bopt == BinaryOpType::General) {
-          dispatch_bool(
-              a.data_size() > INT32_MAX || b.data_size() > INT32_MAX ||
-                  out_a.data_size() > INT32_MAX,
-              [&](auto large) {
-                using IdxT = std::conditional_t<large(), int64_t, int32_t>;
-                Shape shape;
-                std::vector<Strides> strides;
-                std::tie(shape, strides) =
-                    collapse_contiguous_dims(a, b, out_a);
-                auto& a_strides = strides[0];
-                auto& b_strides = strides[1];
-                int ndim = shape.size();
-                if (ndim <= 3) {
-                  dispatch_1_2_3(ndim, [&](auto dims_constant) {
-                    auto kernel = cu::binary_two_g_nd<
-                        Op,
-                        InType,
-                        OutType,
-                        IdxT,
-                        dims_constant()>;
-                    auto [num_blocks, block_dims] =
-                        get_launch_args(kernel, out_a, large());
-                    encoder.add_kernel_node(
-                        kernel,
-                        num_blocks,
-                        block_dims,
-                        a.data<InType>(),
-                        b.data<InType>(),
-                        out_a.data<OutType>(),
-                        out_b.data<OutType>(),
-                        out_a.size(),
-                        const_param<dims_constant()>(shape),
-                        const_param<dims_constant()>(a_strides),
-                        const_param<dims_constant()>(b_strides));
-                  });
-                } else {
-                  auto kernel = cu::binary_two_g<Op, InType, OutType, IdxT>;
-                  auto [num_blocks, block_dims] =
-                      get_launch_args(kernel, out_a, large());
-                  encoder.add_kernel_node(
-                      kernel,
-                      num_blocks,
-                      block_dims,
-                      a.data<InType>(),
-                      b.data<InType>(),
-                      out_a.data<OutType>(),
-                      out_b.data<OutType>(),
-                      out_a.size(),
-                      const_param(shape),
-                      const_param(a_strides),
-                      const_param(b_strides),
-                      ndim);
-                }
-              });
-        } else {
-          dispatch_bool(out_a.data_size() > UINT32_MAX, [&](auto large) {
-            using IdxT = std::conditional_t<large(), int64_t, uint32_t>;
-            // TODO: Choose optimized value based on type size.
-            constexpr int N_READS = 4;
-            auto kernel = cu::binary_two_ss<Op, InType, OutType, IdxT, N_READS>;
-            if (bopt == BinaryOpType::ScalarVector) {
-              kernel = cu::binary_two_sv<Op, InType, OutType, IdxT, N_READS>;
-            } else if (bopt == BinaryOpType::VectorScalar) {
-              kernel = cu::binary_two_vs<Op, InType, OutType, IdxT, N_READS>;
-            } else if (bopt == BinaryOpType::VectorVector) {
-              kernel = cu::binary_two_vv<Op, InType, OutType, IdxT, N_READS>;
-            }
-            auto [num_blocks, block_dims] = get_launch_args(
-                kernel,
-                out_a.data_size(),
-                out_a.shape(),
-                out_a.strides(),
-                large(),
-                N_READS);
-            encoder.add_kernel_node(
-                kernel,
-                num_blocks,
-                block_dims,
-                a.data<InType>(),
-                b.data<InType>(),
-                out_a.data<OutType>(),
-                out_b.data<OutType>(),
-                out_a.data_size());
-          });
-        }
-      } else {
-        throw std::runtime_error(fmt::format(
-            "Can not do binary op {} on inputs of {} with result of {}.",
-            op,
-            dtype_to_string(a.dtype()),
-            dtype_to_string(out_a.dtype())));
-      }
-    });
-  });
-}
-
-template <typename Op>
-void binary_two_op_gpu(
-    const std::vector<array>& inputs,
-    std::vector<array>& outputs,
-    std::string_view op,
-    const Stream& s) {
-  auto& a = inputs[0];
-  auto& b = inputs[1];
-  auto bopt = get_binary_op_type(a, b);
-  set_binary_op_output_data(a, b, outputs[0], bopt);
-  set_binary_op_output_data(a, b, outputs[1], bopt);
-  binary_two_op_gpu_inplace<Op>(inputs, outputs, op, s);
-}
-
-void DivMod::eval_gpu(
-    const std::vector<array>& inputs,
-    std::vector<array>& outputs) {
-  nvtx3::scoped_range r("DivMod::eval_gpu");
-  auto& s = outputs[0].primitive().stream();
-  binary_two_op_gpu<cu::DivMod>(inputs, outputs, get_primitive_string(this), s);
-}
-
-} // namespace mlx::core

mlx/backend/cuda/compiled.cpp

@@ -3,7 +3,6 @@
 #include "mlx/backend/common/compiled.h"
 #include "mlx/backend/cuda/device.h"
 #include "mlx/backend/cuda/jit_module.h"
-#include "mlx/backend/cuda/kernel_utils.cuh"
 #include "mlx/graph_utils.h"
 #include "mlx/primitives.h"
 
@@ -179,7 +178,6 @@ void Compiled::eval_gpu(
   // Whether to use large index.
   bool large = compiled_use_large_index(inputs, outputs, contiguous);
 
-  cu::KernelArgs args;
   // Put inputs.
   int strides_index = 1;
   for (size_t i = 0; i < inputs.size(); ++i) {
@@ -187,26 +185,26 @@ void Compiled::eval_gpu(
       continue;
     }
     const auto& x = inputs[i];
-    args.append(x);
+    mod.append_arg(x);
     if (!contiguous && !is_scalar(x)) {
-      args.append_ptr(strides_vec[strides_index++].data());
+      mod.append_arg(strides_vec[strides_index++]);
     }
   }
 
   // Put outputs.
   compiled_allocate_outputs(inputs, outputs, is_constant_, contiguous);
   for (auto& x : outputs) {
-    args.append(x);
+    mod.append_arg(x);
   }
 
   // Put shape and size.
   if (!contiguous) {
-    args.append_ptr(shape.data());
+    mod.append_arg(shape);
   }
   if (large) {
-    args.append<int64_t>(outputs[0].data_size());
+    mod.append_arg<int64_t>(outputs[0].data_size());
   } else {
-    args.append<uint32_t>(outputs[0].data_size());
+    mod.append_arg<uint32_t>(outputs[0].data_size());
   }
 
   // Launch kernel.
@@ -224,10 +222,9 @@ void Compiled::eval_gpu(
   for (const auto& out : outputs) {
     encoder.set_output_array(out);
   }
-
-  auto kernel = mod.get_kernel(kernel_name);
-  auto [num_blocks, block_dims] = get_launch_args(kernel, outputs[0], large);
-  encoder.add_kernel_node(kernel, num_blocks, block_dims, args.args());
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    mod.launch_kernel(stream, kernel_name, outputs[0], large);
+  });
 }
 
 } // namespace mlx::core

mlx/backend/cuda/copy.cu

@@ -24,6 +24,7 @@ void copy_gpu_inplace(
   auto& encoder = cu::get_command_encoder(s);
   encoder.set_input_array(in);
   encoder.set_output_array(out);
+
   if (ctype == CopyType::Scalar || ctype == CopyType::Vector) {
     copy_contiguous(encoder, ctype, in, out, offset_in, offset_out);
     return;

mlx/backend/cuda/copy/copy.cuh

@@ -10,6 +10,15 @@
 
 namespace mlx::core {
 
+#define MLX_SWITCH_COPY_TYPES(in, out, InType, OutType, ...) \
+  MLX_SWITCH_ALL_TYPES(in.dtype(), CTYPE_IN, {               \
+    MLX_SWITCH_ALL_TYPES(out.dtype(), CTYPE_OUT, {           \
+      using InType = cuda_type_t<CTYPE_IN>;                  \
+      using OutType = cuda_type_t<CTYPE_OUT>;                \
+      __VA_ARGS__;                                           \
+    });                                                      \
+  })
+
 void copy_contiguous(
     cu::CommandEncoder& encoder,
     CopyType ctype,

mlx/backend/cuda/copy/copy_contiguous.cu

@@ -10,43 +10,19 @@ namespace cu {
 
 namespace cg = cooperative_groups;
 
-template <typename In, typename Out, typename IdxT, int N_READS>
+template <typename In, typename Out, typename IdxT>
 __global__ void copy_s(const In* in, Out* out, IdxT size) {
   IdxT index = cg::this_grid().thread_rank();
-
-  if ((index + 1) * N_READS > size) {
-    for (IdxT i = index * N_READS; i < size; ++i) {
-      out[i] = cast_to<Out>(in[0]);
-    }
-  } else {
-    AlignedVector<Out, N_READS> out_vec;
-#pragma unroll
-    for (int i = 0; i < N_READS; ++i) {
-      out_vec.val[i] = cast_to<Out>(in[0]);
-    }
-
-    store_vector<N_READS>(out, index, out_vec);
+  if (index < size) {
+    out[index] = CastOp<In, Out>{}(in[0]);
   }
 }
 
-template <typename In, typename Out, typename IdxT, int N_READS>
+template <typename In, typename Out, typename IdxT>
 __global__ void copy_v(const In* in, Out* out, IdxT size) {
   IdxT index = cg::this_grid().thread_rank();
-
-  if ((index + 1) * N_READS > size) {
-    for (IdxT i = index * N_READS; i < size; ++i) {
-      out[i] = cast_to<Out>(in[i]);
-    }
-  } else {
-    auto in_vec = load_vector<N_READS>(in, index);
-
-    AlignedVector<Out, N_READS> out_vec;
-#pragma unroll
-    for (int i = 0; i < N_READS; ++i) {
-      out_vec.val[i] = cast_to<Out>(in_vec.val[i]);
-    }
-
-    store_vector<N_READS>(out, index, out_vec);
+  if (index < size) {
+    out[index] = CastOp<In, Out>{}(in[index]);
   }
 }
 
@@ -59,29 +35,17 @@ void copy_contiguous(
     array& out,
     int64_t in_offset,
     int64_t out_offset) {
-  dispatch_all_types(in.dtype(), [&](auto in_type_tag) {
-    dispatch_all_types(out.dtype(), [&](auto out_type_tag) {
-      dispatch_bool(out.data_size() > UINT32_MAX, [&](auto large) {
-        using InType = cuda_type_t<MLX_GET_TYPE(in_type_tag)>;
-        using OutType = cuda_type_t<MLX_GET_TYPE(out_type_tag)>;
-        using IdxT = std::conditional_t<large(), int64_t, uint32_t>;
-        // TODO: Choose optimized value based on type size.
-        constexpr int N_READS = 4;
-        auto kernel = cu::copy_s<InType, OutType, IdxT, N_READS>;
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_COPY_TYPES(in, out, InType, OutType, {
+      MLX_SWITCH_BOOL(out.data_size() > UINT32_MAX, LARGE, {
+        using IdxT = std::conditional_t<LARGE, int64_t, uint32_t>;
+        auto kernel = cu::copy_s<InType, OutType, IdxT>;
         if (ctype == CopyType::Vector) {
-          kernel = cu::copy_v<InType, OutType, IdxT, N_READS>;
+          kernel = cu::copy_v<InType, OutType, IdxT>;
         }
         auto [num_blocks, block_dims] = get_launch_args(
-            kernel,
-            out.data_size(),
-            out.shape(),
-            out.strides(),
-            large(),
-            N_READS);
-        encoder.add_kernel_node(
-            kernel,
-            num_blocks,
-            block_dims,
+            kernel, out.data_size(), out.shape(), out.strides(), LARGE);
+        kernel<<<num_blocks, block_dims, 0, stream>>>(
             in.data<InType>() + in_offset,
             out.data<OutType>() + out_offset,
             out.data_size());

mlx/backend/cuda/copy/copy_general.cu

@@ -55,54 +55,39 @@ void copy_general(
     const Shape& shape,
     const Strides& strides_in,
     const Strides& strides_out) {
-  dispatch_all_types(in.dtype(), [&](auto in_type_tag) {
-    dispatch_all_types(out.dtype(), [&](auto out_type_tag) {
-      dispatch_bool(
-          in.data_size() > INT32_MAX || out.data_size() > INT32_MAX,
-          [&](auto large) {
-            using InType = cuda_type_t<MLX_GET_TYPE(in_type_tag)>;
-            using OutType = cuda_type_t<MLX_GET_TYPE(out_type_tag)>;
-            using IdxT = std::conditional_t<large(), int64_t, int32_t>;
-            const InType* in_ptr = in.data<InType>() + offset_in;
-            OutType* out_ptr = out.data<OutType>() + offset_out;
-            int ndim = shape.size();
-            size_t data_size = 1;
-            for (auto& s : shape)
-              data_size *= s;
-            if (ndim <= 3) {
-              dispatch_1_2_3(ndim, [&](auto ndim_constant) {
-                auto kernel =
-                    cu::copy_gg_nd<InType, OutType, IdxT, ndim_constant()>;
-                auto [num_blocks, block_dims] = get_launch_args(
-                    kernel, data_size, shape, out.strides(), large());
-                encoder.add_kernel_node(
-                    kernel,
-                    num_blocks,
-                    block_dims,
-                    in_ptr,
-                    out_ptr,
-                    data_size,
-                    const_param<ndim_constant()>(shape),
-                    const_param<ndim_constant()>(strides_in),
-                    const_param<ndim_constant()>(strides_out));
-              });
-            } else { // ndim >= 4
-              auto kernel = cu::copy_gg<InType, OutType, IdxT>;
-              auto [num_blocks, block_dims] = get_launch_args(
-                  kernel, data_size, shape, out.strides(), large());
-              encoder.add_kernel_node(
-                  kernel,
-                  num_blocks,
-                  block_dims,
-                  in_ptr,
-                  out_ptr,
-                  data_size,
-                  const_param(shape),
-                  const_param(strides_in),
-                  const_param(strides_out),
-                  ndim);
-            }
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_COPY_TYPES(in, out, InType, OutType, {
+      const InType* in_ptr = in.data<InType>() + offset_in;
+      OutType* out_ptr = out.data<OutType>() + offset_out;
+      bool large = in.data_size() > INT32_MAX || out.data_size() > INT32_MAX;
+      MLX_SWITCH_BOOL(large, LARGE, {
+        using IdxT = std::conditional_t<LARGE, int64_t, int32_t>;
+        int ndim = shape.size();
+        if (ndim <= 3) {
+          MLX_SWITCH_1_2_3(ndim, NDIM, {
+            auto kernel = cu::copy_gg_nd<InType, OutType, IdxT, NDIM>;
+            auto [num_blocks, block_dims] = get_launch_args(kernel, out, large);
+            kernel<<<num_blocks, block_dims, 0, stream>>>(
+                in_ptr,
+                out_ptr,
+                out.size(),
+                const_param<NDIM>(shape),
+                const_param<NDIM>(strides_in),
+                const_param<NDIM>(strides_out));
           });
+        } else { // ndim >= 4
+          auto kernel = cu::copy_gg<InType, OutType, IdxT>;
+          auto [num_blocks, block_dims] = get_launch_args(kernel, out, large);
+          kernel<<<num_blocks, block_dims, 0, stream>>>(
+              in_ptr,
+              out_ptr,
+              out.size(),
+              const_param(shape),
+              const_param(strides_in),
+              const_param(strides_out),
+              ndim);
+        }
+      });
     });
   });
 }

mlx/backend/cuda/copy/copy_general_dynamic.cu

@@ -61,55 +61,43 @@ void copy_general_dynamic(
     const Strides& strides_out,
     const array& dynamic_offset_in,
     const array& dynamic_offset_out) {
-  dispatch_all_types(in.dtype(), [&](auto in_type_tag) {
-    dispatch_all_types(out.dtype(), [&](auto out_type_tag) {
-      dispatch_bool(
-          in.data_size() > INT32_MAX || out.data_size() > INT32_MAX,
-          [&](auto large) {
-            using InType = cuda_type_t<MLX_GET_TYPE(in_type_tag)>;
-            using OutType = cuda_type_t<MLX_GET_TYPE(out_type_tag)>;
-            using IdxT = std::conditional_t<large(), int64_t, int32_t>;
-            const InType* in_ptr = in.data<InType>() + offset_in;
-            OutType* out_ptr = out.data<OutType>() + offset_out;
-            int ndim = shape.size();
-            if (ndim <= 3) {
-              dispatch_1_2_3(ndim, [&](auto dims_constant) {
-                auto kernel = cu::
-                    copy_gg_dynamic_nd<InType, OutType, IdxT, dims_constant()>;
-                auto [num_blocks, block_dims] =
-                    get_launch_args(kernel, out, large());
-                encoder.add_kernel_node(
-                    kernel,
-                    num_blocks,
-                    block_dims,
-                    in_ptr,
-                    out_ptr,
-                    out.size(),
-                    const_param<dims_constant()>(shape),
-                    const_param<dims_constant()>(strides_in),
-                    const_param<dims_constant()>(strides_out),
-                    dynamic_offset_in.data<int64_t>(),
-                    dynamic_offset_out.data<int64_t>());
-              });
-            } else { // ndim >= 4
-              auto kernel = cu::copy_gg_dynamic<InType, OutType, IdxT>;
-              auto [num_blocks, block_dims] =
-                  get_launch_args(kernel, out, large());
-              encoder.add_kernel_node(
-                  kernel,
-                  num_blocks,
-                  block_dims,
-                  in_ptr,
-                  out_ptr,
-                  out.size(),
-                  const_param(shape),
-                  const_param(strides_in),
-                  const_param(strides_out),
-                  ndim,
-                  dynamic_offset_in.data<int64_t>(),
-                  dynamic_offset_out.data<int64_t>());
-            }
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_COPY_TYPES(in, out, InType, OutType, {
+      const InType* in_ptr = in.data<InType>() + offset_in;
+      OutType* out_ptr = out.data<OutType>() + offset_out;
+      bool large = in.data_size() > INT32_MAX || out.data_size() > INT32_MAX;
+      MLX_SWITCH_BOOL(large, LARGE, {
+        using IdxT = std::conditional_t<LARGE, int64_t, int32_t>;
+        int ndim = shape.size();
+        if (ndim <= 3) {
+          MLX_SWITCH_1_2_3(ndim, NDIM, {
+            auto kernel = cu::copy_gg_dynamic_nd<InType, OutType, IdxT, NDIM>;
+            auto [num_blocks, block_dims] = get_launch_args(kernel, out, large);
+            kernel<<<num_blocks, block_dims, 0, stream>>>(
+                in_ptr,
+                out_ptr,
+                out.size(),
+                const_param<NDIM>(shape),
+                const_param<NDIM>(strides_in),
+                const_param<NDIM>(strides_out),
+                dynamic_offset_in.data<int64_t>(),
+                dynamic_offset_out.data<int64_t>());
           });
+        } else { // ndim >= 4
+          auto kernel = cu::copy_gg_dynamic<InType, OutType, IdxT>;
+          auto [num_blocks, block_dims] = get_launch_args(kernel, out, large);
+          kernel<<<num_blocks, block_dims, 0, stream>>>(
+              in_ptr,
+              out_ptr,
+              out.size(),
+              const_param(shape),
+              const_param(strides_in),
+              const_param(strides_out),
+              ndim,
+              dynamic_offset_in.data<int64_t>(),
+              dynamic_offset_out.data<int64_t>());
+        }
+      });
     });
   });
 }

mlx/backend/cuda/copy/copy_general_input.cu

@@ -50,49 +50,37 @@ void copy_general_input(
     int64_t offset_out,
     const Shape& shape,
     const Strides& strides_in) {
-  dispatch_all_types(in.dtype(), [&](auto in_type_tag) {
-    dispatch_all_types(out.dtype(), [&](auto out_type_tag) {
-      dispatch_bool(
-          in.data_size() > INT32_MAX || out.data_size() > INT32_MAX,
-          [&](auto large) {
-            using InType = cuda_type_t<MLX_GET_TYPE(in_type_tag)>;
-            using OutType = cuda_type_t<MLX_GET_TYPE(out_type_tag)>;
-            using IdxT = std::conditional_t<large(), int64_t, int32_t>;
-            const InType* in_ptr = in.data<InType>() + offset_in;
-            OutType* out_ptr = out.data<OutType>() + offset_out;
-            int ndim = shape.size();
-            if (ndim <= 3) {
-              dispatch_1_2_3(ndim, [&](auto dims_constant) {
-                auto kernel =
-                    cu::copy_g_nd<InType, OutType, IdxT, dims_constant()>;
-                auto [num_blocks, block_dims] =
-                    get_launch_args(kernel, out, large());
-                encoder.add_kernel_node(
-                    kernel,
-                    num_blocks,
-                    block_dims,
-                    in_ptr,
-                    out_ptr,
-                    out.size(),
-                    const_param<dims_constant()>(shape),
-                    const_param<dims_constant()>(strides_in));
-              });
-            } else { // ndim >= 4
-              auto kernel = cu::copy_g<InType, OutType, IdxT>;
-              auto [num_blocks, block_dims] =
-                  get_launch_args(kernel, out, large());
-              encoder.add_kernel_node(
-                  kernel,
-                  num_blocks,
-                  block_dims,
-                  in_ptr,
-                  out_ptr,
-                  out.size(),
-                  const_param(shape),
-                  const_param(strides_in),
-                  ndim);
-            }
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_COPY_TYPES(in, out, InType, OutType, {
+      const InType* in_ptr = in.data<InType>() + offset_in;
+      OutType* out_ptr = out.data<OutType>() + offset_out;
+      bool large = in.data_size() > INT32_MAX || out.data_size() > INT32_MAX;
+      MLX_SWITCH_BOOL(large, LARGE, {
+        using IdxT = std::conditional_t<LARGE, int64_t, int32_t>;
+        int ndim = shape.size();
+        if (ndim <= 3) {
+          MLX_SWITCH_1_2_3(ndim, NDIM, {
+            auto kernel = cu::copy_g_nd<InType, OutType, IdxT, NDIM>;
+            auto [num_blocks, block_dims] = get_launch_args(kernel, out, large);
+            kernel<<<num_blocks, block_dims, 0, stream>>>(
+                in_ptr,
+                out_ptr,
+                out.size(),
+                const_param<NDIM>(shape),
+                const_param<NDIM>(strides_in));
           });
+        } else { // ndim >= 4
+          auto kernel = cu::copy_g<InType, OutType, IdxT>;
+          auto [num_blocks, block_dims] = get_launch_args(kernel, out, large);
+          kernel<<<num_blocks, block_dims, 0, stream>>>(
+              in_ptr,
+              out_ptr,
+              out.size(),
+              const_param(shape),
+              const_param(strides_in),
+              ndim);
+        }
+      });
     });
   });
 }

mlx/backend/cuda/device.cpp

@@ -2,27 +2,36 @@
 
 #include "mlx/backend/cuda/device.h"
 #include "mlx/backend/cuda/worker.h"
-#include "mlx/utils.h"
+#include "mlx/backend/metal/metal.h"
 
 #include <fmt/format.h>
 #include <nvtx3/nvtx3.hpp>
-#include <future>
-#include <unordered_set>
 
 namespace mlx::core {
 
-// Can be tuned with MLX_MAX_OPS_PER_BUFFER
-// This should be less than 255
-constexpr int default_max_nodes_per_graph = 20;
+namespace cu {
 
-int cuda_graph_cache_size() {
-  static int cache_size = []() {
-    return env::get_var("MLX_CUDA_GRAPH_CACHE_SIZE", 100);
-  }();
-  return cache_size;
+DeviceStream::DeviceStream(Device& device) : device_(device), stream_(device) {}
+
+void DeviceStream::synchronize() {
+  cudaStreamSynchronize(stream_);
 }
 
-namespace cu {
+cudaStream_t DeviceStream::schedule_cuda_stream() {
+  // TODO: Return a stream that maximizes parallelism.
+  return stream_;
+}
+
+cudaStream_t DeviceStream::last_cuda_stream() {
+  return stream_;
+}
+
+CommandEncoder& DeviceStream::get_encoder() {
+  if (!encoder_) {
+    encoder_ = std::make_unique<CommandEncoder>(*this);
+  }
+  return *encoder_;
+}
 
 Device::Device(int device) : device_(device) {
   CHECK_CUDA_ERROR(cudaDeviceGetAttribute(
@@ -57,268 +66,45 @@ void Device::make_current() {
   }
 }
 
-CommandEncoder& Device::get_command_encoder(Stream s) {
-  auto it = encoders_.find(s.index);
-  if (it == encoders_.end()) {
-    it = encoders_.try_emplace(s.index, *this).first;
+DeviceStream& Device::get_stream(Stream s) {
+  auto it = streams_.find(s.index);
+  if (it == streams_.end()) {
+    it = streams_.try_emplace(s.index, *this).first;
   }
   return it->second;
 }
 
-CommandEncoder::CaptureContext::CaptureContext(CommandEncoder& enc) : enc(enc) {
-  CHECK_CUDA_ERROR(cudaGraphCreate(&graph, 0));
-  CHECK_CUDA_ERROR(
-      cudaStreamBeginCapture(enc.stream(), cudaStreamCaptureModeGlobal));
-}
-
-CommandEncoder::CaptureContext::~CaptureContext() {
-  CHECK_CUDA_ERROR(cudaStreamEndCapture(enc.stream(), &graph));
-  size_t num_nodes;
-  CHECK_CUDA_ERROR(cudaGraphGetNodes(graph, NULL, &num_nodes));
-  if (num_nodes == 1) {
-    cudaGraphNode_t captured_node;
-    CHECK_CUDA_ERROR(cudaGraphGetNodes(graph, &captured_node, &num_nodes));
-    CUDA_KERNEL_NODE_PARAMS params;
-    CHECK_CUDA_ERROR(cuGraphKernelNodeGetParams(captured_node, &params));
-    cudaGraphNode_t node;
-    CHECK_CUDA_ERROR(cuGraphAddKernelNode(&node, enc.graph_, NULL, 0, &params));
-    enc.insert_graph_dependencies(GraphNode{node, 'K'});
-  } else {
-    cudaGraphNode_t node;
-    CHECK_CUDA_ERROR(
-        cudaGraphAddChildGraphNode(&node, enc.graph_, NULL, 0, graph));
-    enc.insert_graph_dependencies(GraphNode{node, 'G'});
-  }
-  CHECK_CUDA_ERROR(cudaGraphDestroy(graph));
-}
-
-CommandEncoder::ConcurrentContext::ConcurrentContext(CommandEncoder& enc)
-    : enc(enc) {
-  enc.in_concurrent_ = true;
-}
-
-CommandEncoder::ConcurrentContext::~ConcurrentContext() {
-  enc.in_concurrent_ = false;
-
-  // Use an empty graph node for synchronization
-  CommandEncoder::GraphNode empty{NULL, 'E', std::to_string(enc.node_count_++)};
-  enc.empty_node_count_++;
-  CHECK_CUDA_ERROR(cudaGraphAddEmptyNode(&empty.node, enc.graph_, NULL, 0));
-
-  // Insert the concurrent -> empty node dependencies
-  for (auto& from : enc.concurrent_nodes_) {
-    enc.from_nodes_.push_back(from.node);
-    enc.to_nodes_.push_back(empty.node);
-    enc.graph_key_ += from.id;
-    enc.graph_key_ += from.node_type;
-    enc.graph_key_ += empty.id;
-    enc.graph_key_ += empty.node_type;
-  }
-
-  // Insert the input -> concurrent node dependencies without updating output
-  // nodes
-  auto outputs = std::move(enc.active_outputs_);
-  enc.insert_graph_dependencies(std::move(enc.concurrent_nodes_));
-
-  // Update output node to be the empty node
-  for (auto o : outputs) {
-    enc.node_map_.emplace(o, empty).first->second = empty;
-  }
-}
-
-void CommandEncoder::insert_graph_dependencies(GraphNode node) {
-  if (node.node_type == 'G') {
-    graph_node_count_++;
-  }
-  node.id = std::to_string(node_count_++);
-  if (in_concurrent_) {
-    concurrent_nodes_.push_back(std::move(node));
-  } else {
-    std::vector<GraphNode> nodes;
-    nodes.push_back(std::move(node));
-    insert_graph_dependencies(std::move(nodes));
-  }
-}
-
-void CommandEncoder::insert_graph_dependencies(std::vector<GraphNode> nodes) {
-  std::vector<GraphNode> deps;
-  {
-    // Dependencies must be added in the same order to produce a consistent
-    // topology
-    std::unordered_set<cudaGraphNode_t> set_deps;
-    for (auto d : active_deps_) {
-      if (auto it = node_map_.find(d); it != node_map_.end()) {
-        auto [_, inserted] = set_deps.insert(it->second.node);
-        if (inserted) {
-          deps.push_back(it->second);
-        }
-      }
-    }
-  }
-  active_deps_.clear();
-
-  for (auto o : active_outputs_) {
-    for (auto& node : nodes) {
-      node_map_.emplace(o, node).first->second = node;
-    }
-  }
-  active_outputs_.clear();
-
-  for (auto& from : deps) {
-    for (auto& to : nodes) {
-      from_nodes_.push_back(from.node);
-      to_nodes_.push_back(to.node);
-      graph_key_ += from.id;
-      graph_key_ += from.node_type;
-      graph_key_ += to.id;
-      graph_key_ += to.node_type;
-    }
-  }
-}
-
-CommandEncoder::CommandEncoder(Device& d) : device_(d), stream_(d) {
-  CHECK_CUDA_ERROR(cudaGraphCreate(&graph_, 0));
-}
-
-void clear_graphs(std::unordered_map<std::string, cudaGraphExec_t>& graphs) {
-  for (auto& [_, graph_exec] : graphs) {
-    CHECK_CUDA_ERROR(cudaGraphExecDestroy(graph_exec));
-  }
-  graphs.clear();
-}
-
-CommandEncoder::~CommandEncoder() {
-  clear_graphs(graph_cache_);
-}
+CommandEncoder::CommandEncoder(DeviceStream& s)
+    : device_(s.device()), stream_(s) {}
 
 void CommandEncoder::add_completed_handler(std::function<void()> task) {
   worker_.add_task(std::move(task));
 }
 
-void CommandEncoder::set_input_array(const array& arr) {
-  auto id = reinterpret_cast<std::uintptr_t>(arr.buffer().ptr());
-  active_deps_.push_back(id);
-}
+void CommandEncoder::end_encoding() {
+  if (!temporaries_.empty()) {
+    add_completed_handler([temporaries = std::move(temporaries_)]() {});
+  }
 
-void CommandEncoder::set_output_array(const array& arr) {
-  auto id = reinterpret_cast<std::uintptr_t>(arr.buffer().ptr());
-  active_deps_.push_back(id);
-  active_outputs_.push_back(id);
-}
+  // There is no kernel running, run completion handlers immediately.
+  if (!has_gpu_work_) {
+    worker_.consume_in_this_thread();
+    return;
+  }
+  has_gpu_work_ = false;
 
-void CommandEncoder::maybe_commit() {
-  if (node_count_ >= env::max_ops_per_buffer(default_max_nodes_per_graph)) {
+  // Put completion handlers in a batch.
+  worker_.end_batch();
+
+  // Signaling kernel completion is expensive, delay until enough batches.
+  // TODO: This number is arbitrarily picked, profile for a better stragety.
+  if (worker_.uncommited_batches() > 8) {
     commit();
   }
 }
 
-void CommandEncoder::add_kernel_node(
-    void* func,
-    dim3 grid_dim,
-    dim3 block_dim,
-    void** params) {
-  cudaKernelNodeParams kernel_params = {0};
-  kernel_params.func = func;
-  kernel_params.gridDim = grid_dim;
-  kernel_params.blockDim = block_dim;
-  kernel_params.kernelParams = params;
-  cudaGraphNode_t node;
-  CHECK_CUDA_ERROR(
-      cudaGraphAddKernelNode(&node, graph_, NULL, 0, &kernel_params));
-  insert_graph_dependencies(GraphNode{node, 'K'});
-}
-
-void CommandEncoder::add_kernel_node(
-    CUfunction func,
-    dim3 grid_dim,
-    dim3 block_dim,
-    void** params) {
-  CUDA_KERNEL_NODE_PARAMS kernel_params = {0};
-  kernel_params.func = func;
-  kernel_params.gridDimX = grid_dim.x;
-  kernel_params.gridDimY = grid_dim.y;
-  kernel_params.gridDimZ = grid_dim.z;
-  kernel_params.blockDimX = block_dim.x;
-  kernel_params.blockDimY = block_dim.y;
-  kernel_params.blockDimZ = block_dim.z;
-  kernel_params.kernelParams = params;
-  CUgraphNode node;
-  CHECK_CUDA_ERROR(
-      cuGraphAddKernelNode(&node, graph_, NULL, 0, &kernel_params));
-  insert_graph_dependencies(GraphNode{node, 'K'});
-}
-
 void CommandEncoder::commit() {
-  if (!temporaries_.empty()) {
-    add_completed_handler([temporaries = std::move(temporaries_)]() {});
-  }
-  if (node_count_ > 0) {
-    if (!from_nodes_.empty()) {
-      CHECK_CUDA_ERROR(cudaGraphAddDependencies(
-          graph_, from_nodes_.data(), to_nodes_.data(), from_nodes_.size()));
-    }
-
-    graph_key_ += ".";
-    graph_key_ += std::to_string(node_count_);
-    graph_key_ += ".";
-    graph_key_ += std::to_string(graph_node_count_);
-    graph_key_ += ".";
-    graph_key_ += std::to_string(empty_node_count_);
-
-    cudaGraphExec_t& graph_exec = graph_cache_[graph_key_];
-
-    if (graph_exec != nullptr) {
-      cudaGraphExecUpdateResult update_result;
-#if CUDART_VERSION >= 12000
-      cudaGraphExecUpdateResultInfo info;
-      cudaGraphExecUpdate(graph_exec, graph_, &info);
-      update_result = info.result;
-#else
-      cudaGraphNode_t error_node;
-      cudaGraphExecUpdate(graph_exec, graph_, &error_node, &update_result);
-#endif // CUDART_VERSION >= 12000
-      if (update_result != cudaGraphExecUpdateSuccess) {
-        cudaGetLastError(); // reset error
-        CHECK_CUDA_ERROR(cudaGraphExecDestroy(graph_exec));
-        graph_exec = nullptr;
-      }
-    }
-    if (graph_exec == nullptr) {
-      CHECK_CUDA_ERROR(
-          cudaGraphInstantiate(&graph_exec, graph_, NULL, NULL, 0));
-    }
-    device_.make_current();
-    CHECK_CUDA_ERROR(cudaGraphLaunch(graph_exec, stream_));
-
-    // TODO smarter cache policy
-    if (graph_cache_.size() > cuda_graph_cache_size()) {
-      clear_graphs(graph_cache_);
-    }
-
-    // Reset state
-    node_count_ = 0;
-    graph_node_count_ = 0;
-    from_nodes_.clear();
-    to_nodes_.clear();
-    graph_key_.clear();
-    node_map_.clear();
-    CHECK_CUDA_ERROR(cudaGraphDestroy(graph_));
-    CHECK_CUDA_ERROR(cudaGraphCreate(&graph_, 0));
-  }
-
-  // Put completion handlers in a batch.
-  worker_.end_batch();
-  worker_.commit(stream_);
-}
-
-void CommandEncoder::synchronize() {
-  cudaStreamSynchronize(stream_);
-  auto p = std::make_shared<std::promise<void>>();
-  std::future<void> f = p->get_future();
-  add_completed_handler([p = std::move(p)]() { p->set_value(); });
-  worker_.end_batch();
-  commit();
-  f.wait();
+  worker_.commit(stream_.last_cuda_stream());
 }
 
 Device& device(mlx::core::Device device) {
@@ -330,8 +116,12 @@ Device& device(mlx::core::Device device) {
   return it->second;
 }
 
+DeviceStream& get_stream(Stream s) {
+  return device(s.device).get_stream(s);
+}
+
 CommandEncoder& get_command_encoder(Stream s) {
-  return device(s.device).get_command_encoder(s);
+  return get_stream(s).get_encoder();
 }
 
 } // namespace cu

mlx/backend/cuda/device.h

@@ -7,109 +7,41 @@
 #include "mlx/stream.h"
 
 #include <cublasLt.h>
-#include <cuda.h>
 #include <thrust/execution_policy.h>
 
 #include <unordered_map>
 
 namespace mlx::core::cu {
 
-class CommandEncoder {
+class Device;
+class CommandEncoder;
+
+class DeviceStream {
  public:
-  struct CaptureContext {
-    CaptureContext(CommandEncoder& enc);
-    ~CaptureContext();
-    cudaGraph_t graph;
-    CommandEncoder& enc;
-  };
-  struct ConcurrentContext {
-    ConcurrentContext(CommandEncoder& enc);
-    ~ConcurrentContext();
-    CommandEncoder& enc;
-  };
+  explicit DeviceStream(Device& device);
 
-  explicit CommandEncoder(Device& d);
-  ~CommandEncoder();
+  DeviceStream(const DeviceStream&) = delete;
+  DeviceStream& operator=(const DeviceStream&) = delete;
 
-  CommandEncoder(const CommandEncoder&) = delete;
-  CommandEncoder& operator=(const CommandEncoder&) = delete;
-
-  CaptureContext capture_context() {
-    return CaptureContext{*this};
-  }
-  ConcurrentContext concurrent_context() {
-    return ConcurrentContext{*this};
-  }
-
-  void set_input_array(const array& arr);
-  void set_output_array(const array& arr);
-
-  template <typename F, typename... Params>
-  void
-  add_kernel_node(F* func, dim3 grid_dim, dim3 block_dim, Params&&... params) {
-    constexpr size_t num = sizeof...(Params);
-    void* ptrs[num];
-    size_t i = 0;
-    ([&](auto&& p) { ptrs[i++] = static_cast<void*>(&p); }(
-         std::forward<Params>(params)),
-     ...);
-    add_kernel_node((void*)func, grid_dim, block_dim, ptrs);
-  }
-
-  void add_kernel_node(
-      CUfunction func,
-      dim3 grid_dim,
-      dim3 block_dim,
-      void** params);
-
-  void
-  add_kernel_node(void* func, dim3 grid_dim, dim3 block_dim, void** params);
-
-  void add_temporary(const array& arr) {
-    temporaries_.push_back(arr.data_shared_ptr());
-  }
-
-  void add_completed_handler(std::function<void()> task);
-  void maybe_commit();
-  void commit();
-
-  CudaStream& stream() {
-    return stream_;
-  }
-
-  // Wait until kernels and completion handlers are finished
+  // Wait until kernels in the stream complete.
   void synchronize();
 
+  // Return a cuda stream for launching kernels.
+  cudaStream_t schedule_cuda_stream();
+
+  // Return the last cuda stream used.
+  cudaStream_t last_cuda_stream();
+
+  CommandEncoder& get_encoder();
+
+  Device& device() {
+    return device_;
+  }
+
  private:
-  struct GraphNode {
-    cudaGraphNode_t node;
-    // K = kernel
-    // E = empty
-    // G = subgraph
-    char node_type;
-    std::string id;
-  };
-
-  void insert_graph_dependencies(GraphNode node);
-  void insert_graph_dependencies(std::vector<GraphNode> nodes);
-
   Device& device_;
   CudaStream stream_;
-  cudaGraph_t graph_;
-  Worker worker_;
-  char node_count_{0};
-  char graph_node_count_{0};
-  char empty_node_count_{0};
-  bool in_concurrent_{false};
-  std::vector<cudaGraphNode_t> from_nodes_;
-  std::vector<cudaGraphNode_t> to_nodes_;
-  std::string graph_key_;
-  std::vector<GraphNode> concurrent_nodes_;
-  std::vector<std::shared_ptr<array::Data>> temporaries_;
-  std::unordered_map<std::string, cudaGraphExec_t> graph_cache_;
-  std::vector<std::uintptr_t> active_deps_;
-  std::vector<std::uintptr_t> active_outputs_;
-  std::unordered_map<std::uintptr_t, GraphNode> node_map_;
+  std::unique_ptr<CommandEncoder> encoder_;
 };
 
 class Device {
@@ -123,7 +55,7 @@ class Device {
   // Make this device the current cuda device, required by some cuda calls.
   void make_current();
 
-  CommandEncoder& get_command_encoder(Stream s);
+  DeviceStream& get_stream(Stream s);
 
   int cuda_device() const {
     return device_;
@@ -143,10 +75,64 @@ class Device {
   int compute_capability_major_;
   int compute_capability_minor_;
   cublasLtHandle_t lt_;
-  std::unordered_map<int, CommandEncoder> encoders_;
+  std::unordered_map<int, DeviceStream> streams_;
+};
+
+class CommandEncoder {
+ public:
+  explicit CommandEncoder(DeviceStream& stream);
+
+  CommandEncoder(const CommandEncoder&) = delete;
+  CommandEncoder& operator=(const CommandEncoder&) = delete;
+
+  void set_input_array(const array& arr) {}
+  void set_output_array(const array& arr) {}
+
+  void add_temporary(const array& arr) {
+    temporaries_.push_back(arr.data_shared_ptr());
+  }
+
+  void add_completed_handler(std::function<void()> task);
+  void end_encoding();
+  void commit();
+
+  // Schedule a cuda stream for |fun| to launch kernels, and check error
+  // afterwards.
+  template <typename F>
+  void launch_kernel(F&& fun) {
+    launch_kernel(stream_.schedule_cuda_stream(), std::forward<F>(fun));
+  }
+
+  template <typename F>
+  void launch_kernel(cudaStream_t stream, F&& fun) {
+    device_.make_current();
+    fun(stream);
+    check_cuda_error("kernel launch", cudaGetLastError());
+    has_gpu_work_ = true;
+  }
+
+  Device& device() {
+    return device_;
+  }
+
+  DeviceStream& stream() {
+    return stream_;
+  }
+
+  bool has_gpu_work() const {
+    return has_gpu_work_;
+  }
+
+ private:
+  Device& device_;
+  DeviceStream& stream_;
+  Worker worker_;
+  bool has_gpu_work_{false};
+  std::vector<std::shared_ptr<array::Data>> temporaries_;
 };
 
 Device& device(mlx::core::Device device);
+DeviceStream& get_stream(Stream s);
 CommandEncoder& get_command_encoder(Stream s);
 
 // Return an execution policy that does not sync for result.

mlx/backend/cuda/device/binary_ops.cuh

@@ -1,7 +1,10 @@
 // Copyright © 2025 Apple Inc.
 
-#include "mlx/backend/cuda/device/unary_ops.cuh"
+#include "mlx/backend/cuda/device/cucomplex_math.cuh"
+#include "mlx/backend/cuda/device/fp16_math.cuh"
+#include "mlx/backend/cuda/device/utils.cuh"
 
+#include <cuComplex.h>
 #include <cuda/std/array>
 
 namespace mlx::core::cu {
@@ -19,7 +22,7 @@ struct FloorDivide {
     if constexpr (cuda::std::is_integral_v<T>) {
       return x / y;
     } else {
-      return truncf(x / y);
+      return trunc(x / y);
     }
   }
 };
@@ -111,38 +114,36 @@ struct LessEqual {
 struct LogAddExp {
   template <typename T>
   __device__ T operator()(T x, T y) {
-    if constexpr (cuda::std::is_same_v<T, cuComplex>) {
-      if (isnan(cuCrealf(x)) || isnan(cuCimagf(x)) || isnan(cuCrealf(y)) ||
-          isnan(cuCimagf(y))) {
-        return {
-            cuda::std::numeric_limits<float>::quiet_NaN(),
-            cuda::std::numeric_limits<float>::quiet_NaN()};
-      }
-      auto max = cuCrealf(x) > cuCrealf(y) ? x : y;
-      auto min = cuCrealf(x) < cuCrealf(y) ? x : y;
-      auto min_real = cuCrealf(min);
-      auto max_real = cuCrealf(max);
-      if (!isfinite(min_real) && (min_real == max_real)) {
-        if (min_real < 0) {
-          return min;
-        } else {
-          return Log{}(Exp{}(min) + Exp{}(max));
-        }
-      } else {
-        return Log1p{}(Exp{}(min - max)) + max;
-      }
-    } else {
-      if (isnan(x) || isnan(y)) {
-        return cuda::std::numeric_limits<T>::quiet_NaN();
-      }
-      T maxval = max(x, y);
-      T minval = min(x, y);
-      return (minval == -cuda::std::numeric_limits<T>::infinity() ||
-              maxval == cuda::std::numeric_limits<T>::infinity())
-          ? maxval
-          : T(float(maxval) + log1p(expf(minval - maxval)));
+    if (isnan(x) || isnan(y)) {
+      return cuda::std::numeric_limits<T>::quiet_NaN();
     }
+    T maxval = max(x, y);
+    T minval = min(x, y);
+    return (minval == -cuda::std::numeric_limits<T>::infinity() ||
+            maxval == cuda::std::numeric_limits<T>::infinity())
+        ? maxval
+        : T(float(maxval) + log1p(expf(minval - maxval)));
   };
+
+  __device__ cuComplex operator()(cuComplex x, cuComplex y) {
+    if (isnan(cuCrealf(x)) || isnan(cuCimagf(x)) || isnan(cuCrealf(y)) ||
+        isnan(cuCimagf(y))) {
+      return {
+          cuda::std::numeric_limits<float>::quiet_NaN(),
+          cuda::std::numeric_limits<float>::quiet_NaN()};
+    }
+    constexpr float inf = cuda::std::numeric_limits<float>::infinity();
+    auto maxval = x > y ? x : y;
+    auto minval = x < y ? x : y;
+    if (cuCrealf(minval) == -inf || cuCrealf(maxval) == inf)
+      return maxval;
+    float m = exp(cuCrealf(minval) - cuCrealf(maxval));
+    cuComplex dexp{
+        m * cos(cuCimagf(minval) - cuCimagf(maxval)),
+        m * sin(cuCimagf(minval) - cuCimagf(maxval)),
+    };
+    return maxval + log1p(dexp);
+  }
 };
 
 struct Maximum {

mlx/backend/cuda/device/cast_op.cuh

@@ -3,8 +3,6 @@
 #pragma once
 
 #include <cuComplex.h>
-#include <cuda_bf16.h>
-#include <cuda_fp16.h>
 #include <thrust/iterator/transform_iterator.h>
 
 namespace mlx::core::cu {
@@ -19,26 +17,6 @@ struct CastOp {
   }
 };
 
-// Castings between complex and boolean.
-// TODO: Should make a custom complex type.
-template <>
-struct CastOp<cuComplex, bool> {
-  static constexpr bool is_castable = true;
-
-  __device__ bool operator()(cuComplex x) {
-    return x.x != 0 && x.y != 0;
-  }
-};
-
-template <>
-struct CastOp<bool, cuComplex> {
-  static constexpr bool is_castable = true;
-
-  __device__ cuComplex operator()(bool x) {
-    return x ? make_cuFloatComplex(1, 1) : make_cuFloatComplex(0, 0);
-  }
-};
-
 // Converting a complex number to real number discards the imaginary part.
 template <typename DstT>
 struct CastOp<
@@ -67,7 +45,6 @@ struct CastOp<
   }
 };
 
-// Do nothing when no casting is needed.
 template <typename SrcT, typename DstT>
 struct CastOp<
     SrcT,
@@ -80,53 +57,9 @@ struct CastOp<
   }
 };
 
-// In CUDA 11 the half types do not define conversions between some types,
-// provide fallbacks here.
-#if CUDART_VERSION < 12000
-template <typename SrcT, typename DstT>
-struct CastOp<
-    SrcT,
-    DstT,
-    cuda::std::enable_if_t<
-        !cuda::std::is_convertible_v<SrcT, DstT> &&
-        !cuda::std::is_same_v<SrcT, cuComplex> &&
-        (cuda::std::is_same_v<DstT, __half> ||
-         cuda::std::is_same_v<DstT, __nv_bfloat16>)>> {
-  static constexpr bool is_castable = true;
-
-  __device__ DstT operator()(SrcT x) {
-    return DstT(static_cast<float>(x));
-  }
-};
-
-template <typename SrcT, typename DstT>
-struct CastOp<
-    SrcT,
-    DstT,
-    cuda::std::enable_if_t<
-        !cuda::std::is_convertible_v<SrcT, DstT> &&
-        !cuda::std::is_same_v<DstT, cuComplex> &&
-        !cuda::std::is_same_v<DstT, __half> &&
-        !cuda::std::is_same_v<DstT, __nv_bfloat16> &&
-        (cuda::std::is_same_v<SrcT, __half> ||
-         cuda::std::is_same_v<SrcT, __nv_bfloat16>)>> {
-  static constexpr bool is_castable = true;
-
-  __device__ DstT operator()(SrcT x) {
-    return DstT(static_cast<float>(x));
-  }
-};
-#endif // CUDART_VERSION < 12000
-
-// Helper to deduce the SrcT.
-template <typename DstT, typename SrcT>
-inline __host__ __device__ auto cast_to(SrcT x) {
-  return CastOp<SrcT, DstT>{}(x);
-}
-
 // Return an iterator that cast the value to DstT using CastOp.
 template <typename DstT, typename Iterator>
-inline __host__ __device__ auto make_cast_iterator(Iterator it) {
+__host__ __device__ auto make_cast_iterator(Iterator it) {
   using SrcT = typename cuda::std::iterator_traits<Iterator>::value_type;
   if constexpr (std::is_same_v<SrcT, DstT>) {
     return it;

mlx/backend/cuda/device/cexpf.cuh

@@ -1,138 +0,0 @@
-// Copyright © 2025 Apple Inc.
-// Copyright © 2008-2013 NVIDIA Corporation
-// Copyright © 2013 Filipe RNC Maia
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-// Forked from
-// https://github.com/NVIDIA/cccl/blob/main/thrust/thrust/detail/complex/cexpf.h
-
-// TODO: We should use thrust::exp but the thrust header in old CUDA versions
-// can not be used in JIT.
-
-#pragma once
-
-#include <cuComplex.h>
-#include <cuda/std/cstdint>
-
-namespace mlx::core::cu::detail {
-
-using ieee_float_shape_type = union {
-  float value;
-  uint32_t word;
-};
-
-inline __device__ void get_float_word(uint32_t& i, float d) {
-  ieee_float_shape_type gf_u;
-  gf_u.value = (d);
-  (i) = gf_u.word;
-}
-
-inline __device__ void get_float_word(int32_t& i, float d) {
-  ieee_float_shape_type gf_u;
-  gf_u.value = (d);
-  (i) = gf_u.word;
-}
-
-inline __device__ void set_float_word(float& d, uint32_t i) {
-  ieee_float_shape_type sf_u;
-  sf_u.word = (i);
-  (d) = sf_u.value;
-}
-
-inline __device__ float frexp_expf(float x, int* expt) {
-  const uint32_t k = 235;
-  const float kln2 = 162.88958740F;
-
-  float exp_x;
-  uint32_t hx;
-
-  exp_x = expf(x - kln2);
-  get_float_word(hx, exp_x);
-  *expt = (hx >> 23) - (0x7f + 127) + k;
-  set_float_word(exp_x, (hx & 0x7fffff) | ((0x7f + 127) << 23));
-  return exp_x;
-}
-
-inline __device__ cuComplex ldexp_cexpf(cuComplex z, int expt) {
-  float x, y, exp_x, scale1, scale2;
-  int ex_expt, half_expt;
-
-  x = cuCrealf(z);
-  y = cuCimagf(z);
-  exp_x = frexp_expf(x, &ex_expt);
-  expt += ex_expt;
-
-  half_expt = expt / 2;
-  set_float_word(scale1, (0x7f + half_expt) << 23);
-  half_expt = expt - half_expt;
-  set_float_word(scale2, (0x7f + half_expt) << 23);
-
-  return cuComplex{
-      cosf(y) * exp_x * scale1 * scale2, sinf(y) * exp_x * scale1 * scale2};
-}
-
-inline __device__ cuComplex cexpf(const cuComplex& z) {
-  float x, y, exp_x;
-  uint32_t hx, hy;
-
-  const uint32_t exp_ovfl = 0x42b17218, cexp_ovfl = 0x43400074;
-
-  x = cuCrealf(z);
-  y = cuCimagf(z);
-
-  get_float_word(hy, y);
-  hy &= 0x7fffffff;
-
-  /* cexp(x + I 0) = exp(x) + I 0 */
-  if (hy == 0) {
-    return cuComplex{expf(x), y};
-  }
-  get_float_word(hx, x);
-  /* cexp(0 + I y) = cos(y) + I sin(y) */
-  if ((hx & 0x7fffffff) == 0) {
-    return cuComplex{cosf(y), sinf(y)};
-  }
-  if (hy >= 0x7f800000) {
-    if ((hx & 0x7fffffff) != 0x7f800000) {
-      /* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */
-      return cuComplex{y - y, y - y};
-    } else if (hx & 0x80000000) {
-      /* cexp(-Inf +- I Inf|NaN) = 0 + I 0 */
-      return cuComplex{0.0, 0.0};
-    } else {
-      /* cexp(+Inf +- I Inf|NaN) = Inf + I NaN */
-      return cuComplex{x, y - y};
-    }
-  }
-
-  if (hx >= exp_ovfl && hx <= cexp_ovfl) {
-    /*
-     * x is between 88.7 and 192, so we must scale to avoid
-     * overflow in expf(x).
-     */
-    return ldexp_cexpf(z, 0);
-  } else {
-    /*
-     * Cases covered here:
-     *  -  x < exp_ovfl and exp(x) won't overflow (common case)
-     *  -  x > cexp_ovfl, so exp(x) * s overflows for all s > 0
-     *  -  x = +-Inf (generated by exp())
-     *  -  x = NaN (spurious inexact exception from y)
-     */
-    exp_x = expf(x);
-    return cuComplex{exp_x * cosf(y), exp_x * sinf(y)};
-  }
-}
-
-} // namespace mlx::core::cu::detail

mlx/backend/cuda/device/config.h

@@ -5,7 +5,7 @@
 #pragma once
 
 // The maximum dimensions of shape/strides passed as kernel parameters.
-#define MAX_NDIM 10
+#define MAX_NDIM 8
 
 // All existing NVIDIA hardware has a fixed 32 warp size. Though a built-in
 // warpSize variable exists, using it would prevent compile-time optimizations.

mlx/backend/cuda/device/unary_ops.cuh

@@ -2,8 +2,6 @@
 
 #pragma once
 
-#include "mlx/backend/cuda/device/cexpf.cuh"
-#include "mlx/backend/cuda/device/cucomplex_math.cuh"
 #include "mlx/backend/cuda/device/fp16_math.cuh"
 #include "mlx/backend/cuda/device/utils.cuh"
 
@@ -29,8 +27,6 @@ struct ArcCos {
   __device__ T operator()(T x) {
     return acos(x);
   }
-
-  __device__ cuComplex operator()(cuComplex x);
 };
 
 struct ArcCosh {
@@ -45,8 +41,6 @@ struct ArcSin {
   __device__ T operator()(T x) {
     return asin(x);
   }
-
-  __device__ cuComplex operator()(cuComplex x);
 };
 
 struct ArcSinh {
@@ -61,8 +55,6 @@ struct ArcTan {
   __device__ T operator()(T x) {
     return atan(x);
   }
-
-  __device__ cuComplex operator()(cuComplex x);
 };
 
 struct ArcTanh {
@@ -152,7 +144,8 @@ struct Exp {
   template <typename T>
   __device__ T operator()(T x) {
     if constexpr (cuda::std::is_same_v<T, cuComplex>) {
-      return detail::cexpf(x);
+      auto m = exp(cuCrealf(x));
+      return {m * cos(cuCimagf(x)), m * sinh(cuCimagf(x))};
     } else {
       return exp(x);
     }
@@ -229,25 +222,8 @@ struct Log10 {
 
 struct Log1p {
   template <typename T>
-  __device__ T operator()(T z) {
-    if constexpr (cuda::std::is_same_v<T, cuComplex>) {
-      float x = cuCrealf(z);
-      float y = cuCimagf(z);
-      float zabs = cuCrealf(Abs{}(z));
-      float theta = atan2f(y, x + 1);
-      if (zabs < 0.5f) {
-        float r = x * (2 + x) + y * y;
-        if (r == 0) { // handle underflow
-          return {x, theta};
-        }
-        return {0.5f * log1pf(r), theta};
-      } else {
-        float z0 = hypotf(x + 1, y);
-        return {logf(z0), theta};
-      }
-    } else {
-      return log1p(z);
-    }
+  __device__ T operator()(T x) {
+    return log1p(x);
   }
 };
 
@@ -285,6 +261,13 @@ struct Round {
   }
 };
 
+struct Rsqrt {
+  template <typename T>
+  __device__ T operator()(T x) {
+    return rsqrt(x);
+  }
+};
+
 struct Sigmoid {
   template <typename T>
   __device__ T operator()(T x) {
@@ -350,29 +333,6 @@ struct Sqrt {
   __device__ T operator()(T x) {
     return sqrt(x);
   }
-
-  __device__ cuComplex operator()(cuComplex x) {
-    auto xr = cuCrealf(x);
-    auto xi = cuCimagf(x);
-    if (xr == 0.0f && xi == 0.0f) {
-      return {0.0f, 0.0f};
-    }
-    auto r = cuCrealf(Abs{}(x));
-    auto a = sqrt((r + xr) / 2.0f);
-    auto b_abs = sqrt((r - xr) / 2.0f);
-    auto b = copysign(b_abs, xi);
-    return {a, b};
-  }
-};
-
-struct Rsqrt {
-  template <typename T>
-  __device__ T operator()(T x) {
-    return rsqrt(x);
-  }
-  __device__ cuComplex operator()(cuComplex x) {
-    return 1.0f / Sqrt{}(x);
-  }
 };
 
 struct Tan {
@@ -405,22 +365,4 @@ struct Tanh {
   }
 };
 
-inline __device__ cuComplex ArcCos::operator()(cuComplex x) {
-  auto i = cuComplex{0.0, 1.0};
-  auto y = Log{}(x + i * Sqrt{}(1.0 - x * x));
-  return {cuCimagf(y), -cuCrealf(y)};
-};
-
-inline __device__ cuComplex ArcSin::operator()(cuComplex x) {
-  auto i = cuComplex{0.0f, 1.0f};
-  auto y = Log{}(i * x + Sqrt{}(1.0f - x * x));
-  return {cuCimagf(y), -cuCrealf(y)};
-};
-
-inline __device__ cuComplex ArcTan::operator()(cuComplex x) {
-  auto i = cuComplex{0.0f, 1.0f};
-  auto ix = i * x;
-  return (1.0f / cuComplex{0.0f, 2.0f}) * Log{}((1.0f + ix) / (1.0f - ix));
-};
-
 } // namespace mlx::core::cu

mlx/backend/cuda/device/utils.cuh

@@ -28,27 +28,6 @@ namespace mlx::core::cu {
 using Shape = cuda::std::array<int32_t, MAX_NDIM>;
 using Strides = cuda::std::array<int64_t, MAX_NDIM>;
 
-// Vectorized load/store.
-template <typename T, int N>
-struct alignas(sizeof(T) * N) AlignedVector {
-  T val[N];
-};
-
-template <int N, typename T>
-inline __device__ AlignedVector<T, N> load_vector(
-    const T* ptr,
-    uint32_t offset) {
-  auto* from = reinterpret_cast<const AlignedVector<T, N>*>(ptr);
-  return from[offset];
-}
-
-template <int N, typename T>
-inline __device__ void
-store_vector(T* ptr, uint32_t offset, const AlignedVector<T, N>& vec) {
-  auto* to = reinterpret_cast<AlignedVector<T, N>*>(ptr);
-  to[offset] = vec;
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 // Type limits utils
 ///////////////////////////////////////////////////////////////////////////////
@@ -99,20 +78,20 @@ struct Limits<
     return cuda::std::numeric_limits<T>::infinity();
   }
   static constexpr __host__ __device__ T min() {
-#if CUDART_VERSION < 12000 && __CUDA_ARCH__ < 800
-    return -cuda::std::numeric_limits<float>::infinity();
-#else
+#if defined(__CUDA_ARCH__) || CUDART_VERSION >= 12000
     return -cuda::std::numeric_limits<T>::infinity();
+#else
+    return -cuda::std::numeric_limits<float>::infinity();
 #endif
   }
   static constexpr __host__ __device__ T finite_max() {
     return cuda::std::numeric_limits<T>::max();
   }
   static constexpr __host__ __device__ T finite_min() {
-#if CUDART_VERSION < 12000 && __CUDA_ARCH__ < 800
-    return cuda::std::numeric_limits<float>::lowest();
-#else
+#if defined(__CUDA_ARCH__) || CUDART_VERSION >= 12000
     return cuda::std::numeric_limits<T>::lowest();
+#else
+    return cuda::std::numeric_limits<float>::lowest();
 #endif
   }
 };
@@ -176,8 +155,8 @@ inline __host__ __device__ cuda::std::tuple<IdxT, IdxT> elem_to_loc_nd(
 #pragma unroll
   for (int i = NDIM - 1; i >= 0; --i) {
     int dim_idx = elem % shape[i];
-    a_loc += dim_idx * IdxT(a_strides[i]);
-    b_loc += dim_idx * IdxT(b_strides[i]);
+    a_loc += dim_idx * a_strides[i];
+    b_loc += dim_idx * b_strides[i];
     elem /= shape[i];
   }
   return cuda::std::make_tuple(a_loc, b_loc);
@@ -196,9 +175,9 @@ inline __host__ __device__ cuda::std::tuple<IdxT, IdxT, IdxT> elem_to_loc_nd(
 #pragma unroll
   for (int i = NDIM - 1; i >= 0; --i) {
     int dim_idx = elem % shape[i];
-    a_loc += dim_idx * IdxT(a_strides[i]);
-    b_loc += dim_idx * IdxT(b_strides[i]);
-    c_loc += dim_idx * IdxT(c_strides[i]);
+    a_loc += dim_idx * a_strides[i];
+    b_loc += dim_idx * b_strides[i];
+    c_loc += dim_idx * c_strides[i];
     elem /= shape[i];
   }
   return cuda::std::make_tuple(a_loc, b_loc, c_loc);
@@ -227,8 +206,8 @@ inline __host__ __device__ cuda::std::tuple<IdxT, IdxT> elem_to_loc_4d(
   IdxT b_loc = 0;
   for (int i = ndim - 1; i >= 0; --i) {
     int dim_idx = elem % shape[i];
-    a_loc += dim_idx * IdxT(a_strides[i]);
-    b_loc += dim_idx * IdxT(b_strides[i]);
+    a_loc += dim_idx * a_strides[i];
+    b_loc += dim_idx * b_strides[i];
     elem /= shape[i];
   }
   return cuda::std::make_tuple(a_loc, b_loc);
@@ -247,9 +226,9 @@ inline __host__ __device__ cuda::std::tuple<IdxT, IdxT, IdxT> elem_to_loc_4d(
   IdxT c_loc = 0;
   for (int i = ndim - 1; i >= 0; --i) {
     int dim_idx = elem % shape[i];
-    a_loc += dim_idx * IdxT(a_strides[i]);
-    b_loc += dim_idx * IdxT(b_strides[i]);
-    c_loc += dim_idx * IdxT(c_strides[i]);
+    a_loc += dim_idx * a_strides[i];
+    b_loc += dim_idx * b_strides[i];
+    c_loc += dim_idx * c_strides[i];
     elem /= shape[i];
   }
   return cuda::std::make_tuple(a_loc, b_loc, c_loc);
@@ -359,4 +338,21 @@ struct LoopedElemToLoc<1, false, OffsetT> {
   }
 };
 
+inline __device__ cuComplex log1p(cuComplex in) {
+  float x = cuCrealf(in);
+  float y = cuCimagf(in);
+  float zabs = sqrt(x * x + y * y);
+  float theta = atan2f(y, x + 1);
+  if (zabs < 0.5f) {
+    float r = x * (2 + x) + y * y;
+    if (r == 0) { // handle underflow
+      return {x, theta};
+    }
+    return {0.5f * log1pf(r), theta};
+  } else {
+    auto z0 = sqrt((x + 1) * (x + 1) + y * y);
+    return {log(z0), theta};
+  }
+}
+
 } // namespace mlx::core::cu

mlx/backend/cuda/eval.cpp

@@ -37,20 +37,22 @@ void eval(array& arr) {
   }
 
   auto& encoder = cu::get_command_encoder(arr.primitive().stream());
-  // Keep used buffers alive until kernel finishes running.
-  std::unordered_set<std::shared_ptr<array::Data>> buffers;
-  for (auto& in : arr.inputs()) {
-    buffers.insert(in.data_shared_ptr());
+  if (encoder.has_gpu_work()) {
+    // Keep used buffers alive until kernel finishes running.
+    std::unordered_set<std::shared_ptr<array::Data>> buffers;
+    for (auto& in : arr.inputs()) {
+      buffers.insert(in.data_shared_ptr());
+    }
+    for (auto& s : arr.siblings()) {
+      buffers.insert(s.data_shared_ptr());
+    }
+    // Remove the output if it was donated to by an input.
+    if (auto it = buffers.find(arr.data_shared_ptr()); it != buffers.end()) {
+      buffers.erase(it);
+    }
+    encoder.add_completed_handler([buffers = std::move(buffers)]() {});
   }
-  for (auto& s : arr.siblings()) {
-    buffers.insert(s.data_shared_ptr());
-  }
-  // Remove the output if it was donated to by an input.
-  if (auto it = buffers.find(arr.data_shared_ptr()); it != buffers.end()) {
-    buffers.erase(it);
-  }
-  encoder.add_completed_handler([buffers = std::move(buffers)]() {});
-  encoder.maybe_commit();
+  encoder.end_encoding();
 }
 
 void finalize(Stream s) {
@@ -60,7 +62,7 @@ void finalize(Stream s) {
 
 void synchronize(Stream s) {
   nvtx3::scoped_range r("gpu::synchronize");
-  cu::get_command_encoder(s).synchronize();
+  cu::get_stream(s).synchronize();
 }
 
 } // namespace mlx::core::gpu

mlx/backend/cuda/event.cu

@@ -61,9 +61,7 @@ void CudaEvent::wait(Stream s) {
   if (s.device == mlx::core::Device::cpu) {
     scheduler::enqueue(s, [*this]() mutable { wait(); });
   } else {
-    auto& enc = cu::get_command_encoder(s);
-    enc.commit();
-    wait(enc.stream());
+    wait(cu::get_stream(s).last_cuda_stream());
   }
 }
 
@@ -76,9 +74,7 @@ void CudaEvent::record(Stream s) {
   if (s.device == mlx::core::Device::cpu) {
     throw std::runtime_error("CudaEvent can not wait on cpu stream.");
   } else {
-    auto& enc = cu::get_command_encoder(s);
-    enc.commit();
-    record(enc.stream());
+    record(cu::get_stream(s).last_cuda_stream());
   }
 }
 
@@ -140,9 +136,11 @@ void SharedEvent::wait(Stream s, uint64_t value) {
     scheduler::enqueue(s, [*this, value]() mutable { wait(value); });
   } else {
     auto& encoder = get_command_encoder(s);
-    encoder.commit();
-    wait(encoder.stream(), value);
+    encoder.launch_kernel(
+        encoder.stream().last_cuda_stream(),
+        [this, value](cudaStream_t stream) { wait(stream, value); });
     encoder.add_completed_handler([ac = ac_]() {});
+    encoder.end_encoding();
   }
 }
 
@@ -164,9 +162,11 @@ void SharedEvent::signal(Stream s, uint64_t value) {
     scheduler::enqueue(s, [*this, value]() mutable { signal(stream, value); });
   } else {
     auto& encoder = get_command_encoder(s);
-    encoder.commit();
-    signal(encoder.stream(), value);
+    encoder.launch_kernel(
+        encoder.stream().last_cuda_stream(),
+        [this, value](cudaStream_t stream) { signal(stream, value); });
     encoder.add_completed_handler([ac = ac_]() {});
+    encoder.end_encoding();
   }
 }
 

mlx/backend/cuda/indexing.cpp

@@ -3,16 +3,13 @@
 #include "mlx/backend/common/compiled.h"
 #include "mlx/backend/cuda/device.h"
 #include "mlx/backend/cuda/jit_module.h"
-#include "mlx/backend/cuda/kernel_utils.cuh"
 #include "mlx/backend/gpu/copy.h"
 #include "mlx/dtype_utils.h"
 #include "mlx/primitives.h"
 
 #include "cuda_jit_sources.h"
 
-#include <cuda.h>
 #include <fmt/format.h>
-#include <nvrtc.h>
 #include <nvtx3/nvtx3.hpp>
 
 #include <cassert>
@@ -25,7 +22,7 @@ namespace {
 constexpr const char* g_scatter_ops[] = {"Max", "Min", "Sum", "Prod", "Assign"};
 
 void append_indices_arg(
-    cu::KernelArgs& args,
+    cu::JitModule& mod,
     const std::vector<array>& inputs,
     int nidx,
     int idx_ndim) {
@@ -33,7 +30,7 @@ void append_indices_arg(
   for (int i = 0; i < nidx; ++i) {
     indices[i] = inputs[i + 1].data<void>();
   }
-  args.append(std::move(indices));
+  mod.append_arg(std::move(indices));
   std::vector<int32_t> indices_shape(nidx * idx_ndim);
   for (int i = 0; i < nidx; ++i) {
     std::copy_n(
@@ -41,7 +38,7 @@ void append_indices_arg(
         idx_ndim,
         indices_shape.data() + i * idx_ndim);
   }
-  args.append(std::move(indices_shape));
+  mod.append_arg(std::move(indices_shape));
   std::vector<int64_t> indices_strides(nidx * idx_ndim);
   for (int i = 0; i < nidx; ++i) {
     std::copy_n(
@@ -49,7 +46,7 @@ void append_indices_arg(
         idx_ndim,
         indices_strides.data() + i * idx_ndim);
   }
-  args.append(std::move(indices_strides));
+  mod.append_arg(std::move(indices_strides));
 }
 
 } // namespace
@@ -97,21 +94,20 @@ void Gather::eval_gpu(const std::vector<array>& inputs, array& out) {
     return std::make_pair(jit_source_gather, std::move(kernel_names));
   });
 
-  cu::KernelArgs args;
-  args.append(src);
-  args.append(out);
+  mod.append_arg(src);
+  mod.append_arg(out);
   if (large) {
-    args.append<int64_t>(out.size());
+    mod.append_arg<int64_t>(out.size());
   } else {
-    args.append<int32_t>(out.size());
+    mod.append_arg<int32_t>(out.size());
   }
-  args.append_ndim(src.shape());
-  args.append_ndim(src.strides());
-  args.append<int32_t>(src.ndim());
-  args.append_ndim(slice_sizes_);
-  args.append(slice_size);
-  args.append(axes_);
-  append_indices_arg(args, inputs, nidx, idx_ndim);
+  mod.append_ndim_arg(src.shape());
+  mod.append_ndim_arg(src.strides());
+  mod.append_arg<int32_t>(src.ndim());
+  mod.append_ndim_arg(slice_sizes_);
+  mod.append_arg(slice_size);
+  mod.append_arg(axes_);
+  append_indices_arg(mod, inputs, nidx, idx_ndim);
 
   std::string kernel_name = fmt::format(
       "mlx::core::cu::gather<{}, {}, {}, {}, {}>",
@@ -126,10 +122,9 @@ void Gather::eval_gpu(const std::vector<array>& inputs, array& out) {
     encoder.set_input_array(in);
   }
   encoder.set_output_array(out);
-
-  auto kernel = mod.get_kernel(kernel_name);
-  auto [num_blocks, block_dims] = get_launch_args(kernel, out, large);
-  encoder.add_kernel_node(kernel, num_blocks, block_dims, args.args());
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    mod.launch_kernel(stream, kernel_name, out, large);
+  });
 }
 
 void Scatter::eval_gpu(const std::vector<array>& inputs, array& out) {
@@ -192,27 +187,26 @@ void Scatter::eval_gpu(const std::vector<array>& inputs, array& out) {
     return std::make_pair(jit_source_scatter, std::move(kernel_names));
   });
 
-  cu::KernelArgs args;
-  args.append(upd);
-  args.append(out);
+  mod.append_arg(upd);
+  mod.append_arg(out);
   if (large) {
-    args.append<int64_t>(upd.size());
+    mod.append_arg<int64_t>(upd.size());
   } else {
-    args.append<int32_t>(upd.size());
+    mod.append_arg<int32_t>(upd.size());
   }
-  args.append_ndim(upd.shape());
-  args.append_ndim(upd.strides());
-  args.append<int32_t>(upd.ndim());
+  mod.append_ndim_arg(upd.shape());
+  mod.append_ndim_arg(upd.strides());
+  mod.append_arg<int32_t>(upd.ndim());
   if (large) {
-    args.append<int64_t>(upd_post_idx_size);
+    mod.append_arg<int64_t>(upd_post_idx_size);
   } else {
-    args.append<int32_t>(upd_post_idx_size);
+    mod.append_arg<int32_t>(upd_post_idx_size);
   }
-  args.append_ndim(out.shape());
-  args.append_ndim(out.strides());
-  args.append<int32_t>(out.ndim());
-  args.append(axes_);
-  append_indices_arg(args, inputs, nidx, idx_ndim);
+  mod.append_ndim_arg(out.shape());
+  mod.append_ndim_arg(out.strides());
+  mod.append_arg<int32_t>(out.ndim());
+  mod.append_arg(axes_);
+  append_indices_arg(mod, inputs, nidx, idx_ndim);
 
   std::string kernel_name = fmt::format(
       "mlx::core::cu::scatter<{}, {}, mlx::core::cu::Scatter{}, {}, {}, {}>",
@@ -228,9 +222,9 @@ void Scatter::eval_gpu(const std::vector<array>& inputs, array& out) {
     encoder.set_input_array(in);
   }
   encoder.set_output_array(out);
-  auto kernel = mod.get_kernel(kernel_name);
-  auto [num_blocks, block_dims] = get_launch_args(kernel, upd, large);
-  encoder.add_kernel_node(kernel, num_blocks, block_dims, args.args());
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    mod.launch_kernel(stream, kernel_name, upd, large);
+  });
 }
 
 void GatherAxis::eval_gpu(const std::vector<array>& inputs, array& out) {
@@ -281,26 +275,25 @@ void GatherAxis::eval_gpu(const std::vector<array>& inputs, array& out) {
   }
   size_t idx_size_axis = idx.shape(axis_);
 
-  cu::KernelArgs args;
-  args.append(src);
-  args.append(idx);
-  args.append(out);
+  mod.append_arg(src);
+  mod.append_arg(idx);
+  mod.append_arg(out);
   if (large) {
-    args.append<int64_t>(idx_size_pre);
-    args.append<int64_t>(idx_size_axis);
-    args.append<int64_t>(idx_size_post);
+    mod.append_arg<int64_t>(idx_size_pre);
+    mod.append_arg<int64_t>(idx_size_axis);
+    mod.append_arg<int64_t>(idx_size_post);
   } else {
-    args.append<int32_t>(idx_size_pre);
-    args.append<int32_t>(idx_size_axis);
-    args.append<int32_t>(idx_size_post);
+    mod.append_arg<int32_t>(idx_size_pre);
+    mod.append_arg<int32_t>(idx_size_axis);
+    mod.append_arg<int32_t>(idx_size_post);
   }
-  args.append(remove_index(idx.shape(), axis_));
-  args.append(remove_index(src.strides(), axis_));
-  args.append(remove_index(idx.strides(), axis_));
-  args.append<int32_t>(axis_);
-  args.append(src.shape(axis_));
-  args.append(src.strides(axis_));
-  args.append(idx.strides(axis_));
+  mod.append_arg(remove_index(idx.shape(), axis_));
+  mod.append_arg(remove_index(src.strides(), axis_));
+  mod.append_arg(remove_index(idx.strides(), axis_));
+  mod.append_arg<int32_t>(axis_);
+  mod.append_arg(src.shape(axis_));
+  mod.append_arg(src.strides(axis_));
+  mod.append_arg(idx.strides(axis_));
 
   std::string kernel_name = fmt::format(
       "mlx::core::cu::gather_axis<{}, {}, {}, {}, {}, {}>",
@@ -316,9 +309,9 @@ void GatherAxis::eval_gpu(const std::vector<array>& inputs, array& out) {
     encoder.set_input_array(in);
   }
   encoder.set_output_array(out);
-  auto kernel = mod.get_kernel(kernel_name);
-  auto [num_blocks, block_dims] = get_launch_args(kernel, idx, large);
-  encoder.add_kernel_node(kernel, num_blocks, block_dims, args.args());
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    mod.launch_kernel(stream, kernel_name, idx, large);
+  });
 }
 
 void ScatterAxis::eval_gpu(const std::vector<array>& inputs, array& out) {
@@ -384,26 +377,25 @@ void ScatterAxis::eval_gpu(const std::vector<array>& inputs, array& out) {
   }
   size_t idx_size_axis = idx.shape(axis_);
 
-  cu::KernelArgs args;
-  args.append(upd);
-  args.append(idx);
-  args.append(out);
+  mod.append_arg(upd);
+  mod.append_arg(idx);
+  mod.append_arg(out);
   if (large) {
-    args.append<int64_t>(idx_size_pre);
-    args.append<int64_t>(idx_size_axis);
-    args.append<int64_t>(idx_size_post);
+    mod.append_arg<int64_t>(idx_size_pre);
+    mod.append_arg<int64_t>(idx_size_axis);
+    mod.append_arg<int64_t>(idx_size_post);
   } else {
-    args.append<int32_t>(idx_size_pre);
-    args.append<int32_t>(idx_size_axis);
-    args.append<int32_t>(idx_size_post);
+    mod.append_arg<int32_t>(idx_size_pre);
+    mod.append_arg<int32_t>(idx_size_axis);
+    mod.append_arg<int32_t>(idx_size_post);
   }
-  args.append(remove_index(idx.shape(), axis_));
-  args.append(remove_index(upd.strides(), axis_));
-  args.append(remove_index(idx.strides(), axis_));
-  args.append<int32_t>(axis_);
-  args.append(out.shape(axis_));
-  args.append(upd.strides(axis_));
-  args.append(idx.strides(axis_));
+  mod.append_arg(remove_index(idx.shape(), axis_));
+  mod.append_arg(remove_index(upd.strides(), axis_));
+  mod.append_arg(remove_index(idx.strides(), axis_));
+  mod.append_arg<int32_t>(axis_);
+  mod.append_arg(out.shape(axis_));
+  mod.append_arg(upd.strides(axis_));
+  mod.append_arg(idx.strides(axis_));
 
   std::string kernel_name = fmt::format(
       "mlx::core::cu::scatter_axis<{}, {}, mlx::core::cu::Scatter{}, {}, {}, {}, {}>",
@@ -420,9 +412,9 @@ void ScatterAxis::eval_gpu(const std::vector<array>& inputs, array& out) {
     encoder.set_input_array(in);
   }
   encoder.set_output_array(out);
-  auto kernel = mod.get_kernel(kernel_name);
-  auto [num_blocks, block_dims] = get_launch_args(kernel, idx, large);
-  encoder.add_kernel_node(kernel, num_blocks, block_dims, args.args());
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    mod.launch_kernel(stream, kernel_name, idx, large);
+  });
 }
 
 } // namespace mlx::core

mlx/backend/cuda/jit_module.cpp

@@ -2,7 +2,6 @@
 
 #include "mlx/backend/cuda/jit_module.h"
 #include "mlx/backend/cuda/device.h"
-#include "mlx/version.h"
 
 #include "cuda_jit_sources.h"
 
@@ -27,48 +26,47 @@ void check_nvrtc_error(const char* name, nvrtcResult err) {
   }
 }
 
+#define CHECK_CU_ERROR(cmd) check_cu_error(#cmd, (cmd))
+
+void check_cu_error(const char* name, CUresult err) {
+  if (err != CUDA_SUCCESS) {
+    const char* err_str = "Unknown error";
+    cuGetErrorString(err, &err_str);
+    throw std::runtime_error(fmt::format("{} failed: {}", name, err_str));
+  }
+}
+
 // Return the location of the CUDA toolkit.
-const std::string& cuda_home() {
-  static std::string home = []() -> std::string {
-    const char* home = std::getenv("CUDA_HOME");
-    if (home) {
-      return home;
-    }
-    home = std::getenv("CUDA_PATH");
-    if (home) {
-      return home;
-    }
+const char* cuda_home() {
+  const char* home = std::getenv("CUDA_HOME");
+  if (home) {
+    return home;
+  }
+  home = std::getenv("CUDA_PATH");
+  if (home) {
+    return home;
+  }
 #if defined(__linux__)
-    home = "/usr/local/cuda";
-    if (std::filesystem::exists(home)) {
-      return home;
-    }
+  home = "/usr/local/cuda";
+  if (std::filesystem::exists(home)) {
+    return home;
+  }
 #endif
-    throw std::runtime_error(
-        "Environment variable CUDA_HOME or CUDA_PATH is not set.");
-  }();
-  return home;
+  throw std::runtime_error(
+      "Environment variable CUDA_HOME or CUDA_PATH is not set.");
 }
 
 // Get the cache directory for storing compiled results.
-const std::filesystem::path& ptx_cache_dir() {
-  static std::filesystem::path cache = []() -> std::filesystem::path {
-    std::filesystem::path cache;
-    if (auto c = std::getenv("MLX_PTX_CACHE_DIR"); c) {
-      cache = c;
-    } else {
-      cache =
-          std::filesystem::temp_directory_path() / "mlx" / version() / "ptx";
+bool get_ptx_cache_dir(std::filesystem::path* result) {
+  auto path = std::filesystem::temp_directory_path() / "mlx" / "ptx";
+  if (!std::filesystem::is_directory(path)) {
+    std::error_code error;
+    if (!std::filesystem::create_directories(path, error)) {
+      return false;
     }
-    if (!std::filesystem::exists(cache)) {
-      std::error_code error;
-      if (!std::filesystem::create_directories(cache, error)) {
-        return std::filesystem::path();
-      }
-    }
-    return cache;
-  }();
-  return cache;
+  }
+  *result = path;
+  return true;
 }
 
 // Try to read the cached |ptx| and |ptx_kernels| from |cache_dir|.
@@ -77,10 +75,6 @@ bool read_cached_ptx(
     const std::string& module_name,
     std::vector<char>* ptx,
     std::vector<std::pair<std::string, std::string>>* ptx_kernels) {
-  if (cache_dir.empty()) {
-    return false;
-  }
-
   auto ptx_path = cache_dir / (module_name + ".ptx");
   std::error_code error;
   auto ptx_size = std::filesystem::file_size(ptx_path, error);
@@ -111,10 +105,6 @@ void write_cached_ptx(
     const std::string& module_name,
     const std::vector<char>& ptx,
     const std::vector<std::pair<std::string, std::string>>& ptx_kernels) {
-  if (cache_dir.empty()) {
-    return;
-  }
-
   std::ofstream ptx_file(cache_dir / (module_name + ".ptx"), std::ios::binary);
   if (!ptx.empty()) {
     ptx_file.write(&ptx.front(), ptx.size());
@@ -161,7 +151,6 @@ constexpr const char* g_include_names[] = {
     INCLUDE_PREFIX "atomic_ops.cuh",
     INCLUDE_PREFIX "binary_ops.cuh",
     INCLUDE_PREFIX "cast_op.cuh",
-    INCLUDE_PREFIX "cexpf.cuh",
     INCLUDE_PREFIX "config.h",
     INCLUDE_PREFIX "cucomplex_math.cuh",
     INCLUDE_PREFIX "fp16_math.cuh",
@@ -178,7 +167,6 @@ constexpr const char* g_headers[] = {
     jit_source_atomic_ops,
     jit_source_binary_ops,
     jit_source_cast_op,
-    jit_source_cexpf,
     jit_source_config,
     jit_source_cucomplex_math,
     jit_source_fp16_math,
@@ -196,9 +184,11 @@ JitModule::JitModule(
     const std::string& module_name,
     const KernelBuilder& builder) {
   // Check cache.
+  std::filesystem::path cache_dir;
   std::vector<char> ptx;
   std::vector<std::pair<std::string, std::string>> ptx_kernels;
-  if (!read_cached_ptx(ptx_cache_dir(), module_name, &ptx, &ptx_kernels)) {
+  if (!get_ptx_cache_dir(&cache_dir) ||
+      !read_cached_ptx(cache_dir, module_name, &ptx, &ptx_kernels)) {
     // Create program.
     auto [source_code, kernel_names] = builder();
     nvrtcProgram prog;
@@ -256,7 +246,7 @@ JitModule::JitModule(
     } else {
       CHECK_NVRTC_ERROR(nvrtcGetPTX(prog, ptx.data()));
     }
-    write_cached_ptx(ptx_cache_dir(), module_name, ptx, ptx_kernels);
+    write_cached_ptx(cache_dir, module_name, ptx, ptx_kernels);
   }
 
   // Load module.
@@ -274,13 +264,60 @@ JitModule::JitModule(
   // Load kernels.
   for (const auto& [name, mangled] : ptx_kernels) {
     CUfunction kernel;
-    CHECK_CUDA_ERROR(cuModuleGetFunction(&kernel, module_, mangled.c_str()));
+    CHECK_CU_ERROR(cuModuleGetFunction(&kernel, module_, mangled.c_str()));
     kernels_[name] = kernel;
   }
 }
 
 JitModule::~JitModule() {
-  CHECK_CUDA_ERROR(cuModuleUnload(module_));
+  CHECK_CU_ERROR(cuModuleUnload(module_));
+}
+
+void JitModule::launch_kernel(
+    CUstream stream,
+    const std::string& kernel_name,
+    const array& arr,
+    bool large,
+    int work_per_thread) {
+  CUfunction kernel = get_kernel(kernel_name);
+  size_t nthreads = cuda::ceil_div(arr.size(), work_per_thread);
+  int _, block_dim;
+  CHECK_CU_ERROR(
+      cuOccupancyMaxPotentialBlockSize(&_, &block_dim, kernel, 0, 0, 0));
+  if (block_dim > nthreads) {
+    block_dim = nthreads;
+  }
+  Dims num_blocks{1, 1, 1};
+  if (large) {
+    num_blocks =
+        get_2d_grid_dims_common(arr.shape(), arr.strides(), work_per_thread);
+    std::get<0>(num_blocks) =
+        (std::get<0>(num_blocks) + block_dim - 1) / block_dim;
+  } else {
+    std::get<0>(num_blocks) = (nthreads + block_dim - 1) / block_dim;
+  }
+  launch_kernel(stream, kernel, num_blocks, Dims{block_dim, 1, 1});
+}
+
+void JitModule::launch_kernel(
+    CUstream stream,
+    CUfunction kernel,
+    Dims num_blocks,
+    Dims block_dims) {
+  CHECK_CU_ERROR(cuLaunchKernel(
+      kernel,
+      std::get<0>(num_blocks),
+      std::get<1>(num_blocks),
+      std::get<2>(num_blocks),
+      std::get<0>(block_dims),
+      std::get<1>(block_dims),
+      std::get<2>(block_dims),
+      0,
+      stream,
+      args_.data(),
+      nullptr));
+  args_.clear();
+  storage_.clear();
 }
 
 CUfunction JitModule::get_kernel(const std::string& kernel_name) {
@@ -292,6 +329,10 @@ CUfunction JitModule::get_kernel(const std::string& kernel_name) {
   return it->second;
 }
 
+void JitModule::append_ptr_arg(const void* v) {
+  args_.push_back(const_cast<void*>(v));
+}
+
 JitModule& get_jit_module(
     const mlx::core::Device& device,
     const std::string& name,

mlx/backend/cuda/jit_module.h

@@ -4,7 +4,6 @@
 
 #include "mlx/array.h"
 #include "mlx/backend/common/utils.h"
-#include "mlx/backend/cuda/device.h"
 #include "mlx/backend/cuda/device/config.h"
 
 #include <deque>
@@ -24,48 +23,72 @@ using KernelBuilderResult = std::pair<
     /* kernel names */ std::vector<std::string>>;
 using KernelBuilder = std::function<KernelBuilderResult()>;
 
-struct KernelArgs {
-  void** args() {
-    return args_.data();
-  }
+class JitModule {
+ public:
+  JitModule(
+      Device& device,
+      const std::string& module_name,
+      const KernelBuilder& builder);
+  ~JitModule();
 
-  void append(const array& a) {
-    append(reinterpret_cast<CUdeviceptr>(a.data<void>()));
+  JitModule(const JitModule&) = delete;
+  JitModule& operator=(const JitModule&) = delete;
+
+  void append_arg(const array& a) {
+    append_arg(reinterpret_cast<CUdeviceptr>(a.data<void>()));
   }
 
   template <typename T>
-  void append(T val) {
+  void append_arg(T val) {
     storage_.emplace_back(val);
-    append_ptr(&storage_.back());
+    append_ptr_arg(&storage_.back());
   }
 
   template <typename T>
-  void append(std::vector<T> vec) {
+  void append_arg(std::vector<T> vec) {
     if (vec.empty()) {
       // The nullptr can not be used as arg, pass something not null.
-      append(std::monostate{});
+      append_arg(std::monostate{});
     } else {
-      append_ptr(vec.data());
+      append_ptr_arg(vec.data());
       storage_.emplace_back(std::move(vec));
     }
   }
 
   // Make sure the arg is copied to an array with size of NDIM.
   template <size_t NDIM = MAX_NDIM, typename T>
-  void append_ndim(std::vector<T> vec) {
+  void append_ndim_arg(const std::vector<T>& vec) {
     if (vec.size() > NDIM) {
       throw std::runtime_error(
           fmt::format("ndim can not be larger than {}.", NDIM));
     }
-    vec.resize(NDIM);
-    append(std::move(vec));
+    std::vector<T> copied(NDIM);
+    std::copy(vec.begin(), vec.end(), copied.data());
+    append_arg(std::move(copied));
   }
 
-  void append_ptr(const void* v) {
-    args_.push_back(const_cast<void*>(v));
-  }
+  // Launch kernel with |kernel_name| that each thread works on
+  // |work_per_thread| elements of |arr|.
+  void launch_kernel(
+      CUstream stream,
+      const std::string& kernel_name,
+      const array& arr,
+      bool large,
+      int work_per_thread = 1);
+
+  void launch_kernel(
+      CUstream stream,
+      CUfunction kernel,
+      Dims num_blocks,
+      Dims block_dims);
+
+  CUfunction get_kernel(const std::string& kernel_name);
 
  private:
+  void append_ptr_arg(const void* v);
+
+  CUmodule module_{nullptr};
+  std::unordered_map<std::string, CUfunction> kernels_;
   std::vector<void*> args_;
 
   // The cuLaunchKernel API requires passing pointers to arguments so store
@@ -82,23 +105,6 @@ struct KernelArgs {
   std::deque<Arg> storage_;
 };
 
-class JitModule {
- public:
-  JitModule(
-      Device& device,
-      const std::string& module_name,
-      const KernelBuilder& builder);
-  ~JitModule();
-
-  JitModule(const JitModule&) = delete;
-  JitModule& operator=(const JitModule&) = delete;
-  CUfunction get_kernel(const std::string& kernel_name);
-
- private:
-  CUmodule module_{nullptr};
-  std::unordered_map<std::string, CUfunction> kernels_;
-};
-
 JitModule& get_jit_module(
     const mlx::core::Device& device,
     const std::string& name,

mlx/backend/cuda/kernel_utils.cuh

@@ -6,13 +6,10 @@
 
 #pragma once
 
-#include <type_traits>
-
 #include "mlx/array.h"
 #include "mlx/backend/cuda/device/utils.cuh"
 
 #include <cuComplex.h>
-#include <cuda.h>
 #include <cuda_bf16.h>
 #include <cuda_fp16.h>
 #include <fmt/format.h>
@@ -20,46 +17,60 @@
 
 namespace mlx::core {
 
-template <typename F>
-void dispatch_1_2_3(int n, F&& f) {
-  switch (n) {
-    case 1:
-      f(std::integral_constant<int, 1>{});
-      break;
-    case 2:
-      f(std::integral_constant<int, 2>{});
-      break;
-    case 3:
-      f(std::integral_constant<int, 3>{});
-      break;
+// Convert a number between 1~3 to constexpr.
+#define MLX_SWITCH_1_2_3(N, NDIM, ...) \
+  switch (N) {                         \
+    case 1: {                          \
+      constexpr int NDIM = 1;          \
+      __VA_ARGS__;                     \
+      break;                           \
+    }                                  \
+    case 2: {                          \
+      constexpr int NDIM = 2;          \
+      __VA_ARGS__;                     \
+      break;                           \
+    }                                  \
+    case 3: {                          \
+      constexpr int NDIM = 3;          \
+      __VA_ARGS__;                     \
+      break;                           \
+    }                                  \
   }
-}
 
-template <typename F>
-void dispatch_bool(bool v, F&& f) {
-  if (v) {
-    f(std::true_type{});
-  } else {
-    f(std::false_type{});
+// Like MLX_SWITCH_ALL_TYPES but for booleans.
+#define MLX_SWITCH_BOOL(BOOL, BOOL_ALIAS, ...) \
+  if (BOOL) {                                  \
+    constexpr bool BOOL_ALIAS = true;          \
+    __VA_ARGS__;                               \
+  } else {                                     \
+    constexpr bool BOOL_ALIAS = false;         \
+    __VA_ARGS__;                               \
   }
-}
 
-template <typename F>
-void dispatch_block_dim(int threads, F&& f) {
-  if (threads <= WARP_SIZE) {
-    f(std::integral_constant<int, WARP_SIZE>{});
-  } else if (threads <= WARP_SIZE * 2) {
-    f(std::integral_constant<int, WARP_SIZE * 2>{});
-  } else if (threads <= WARP_SIZE * 4) {
-    f(std::integral_constant<int, WARP_SIZE * 4>{});
-  } else if (threads <= WARP_SIZE * 8) {
-    f(std::integral_constant<int, WARP_SIZE * 8>{});
-  } else if (threads <= WARP_SIZE * 16) {
-    f(std::integral_constant<int, WARP_SIZE * 16>{});
-  } else {
-    f(std::integral_constant<int, WARP_SIZE * 32>{});
+// Convert a block_dim to constexpr between WARP_SIZE and WARP_SIZE ^ 2.
+#define MLX_SWITCH_BLOCK_DIM(NUM_THREADS, BLOCK_DIM, ...)   \
+  {                                                         \
+    uint32_t _num_threads = NUM_THREADS;                    \
+    if (_num_threads <= WARP_SIZE) {                        \
+      constexpr uint32_t BLOCK_DIM = WARP_SIZE;             \
+      __VA_ARGS__;                                          \
+    } else if (_num_threads <= WARP_SIZE * 2) {             \
+      constexpr uint32_t BLOCK_DIM = WARP_SIZE * 2;         \
+      __VA_ARGS__;                                          \
+    } else if (_num_threads <= WARP_SIZE * 4) {             \
+      constexpr uint32_t BLOCK_DIM = WARP_SIZE * 4;         \
+      __VA_ARGS__;                                          \
+    } else if (_num_threads <= WARP_SIZE * 8) {             \
+      constexpr uint32_t BLOCK_DIM = WARP_SIZE * 8;         \
+      __VA_ARGS__;                                          \
+    } else if (_num_threads <= WARP_SIZE * 16) {            \
+      constexpr uint32_t BLOCK_DIM = WARP_SIZE * 16;        \
+      __VA_ARGS__;                                          \
+    } else {                                                \
+      constexpr uint32_t BLOCK_DIM = WARP_SIZE * WARP_SIZE; \
+      __VA_ARGS__;                                          \
+    }                                                       \
   }
-}
 
 // Maps CPU types to CUDA types.
 template <typename T>
@@ -121,13 +132,7 @@ std::pair<dim3, dim3> get_grid_and_block(int dim0, int dim1, int dim2);
 template <typename T>
 inline uint max_occupancy_block_dim(T kernel) {
   int _, block_dim;
-  if constexpr (std::is_same_v<T, CUfunction>) {
-    CHECK_CUDA_ERROR(
-        cuOccupancyMaxPotentialBlockSize(&_, &block_dim, kernel, 0, 0, 0));
-  } else {
-    CHECK_CUDA_ERROR(
-        cudaOccupancyMaxPotentialBlockSize(&_, &block_dim, kernel));
-  }
+  CHECK_CUDA_ERROR(cudaOccupancyMaxPotentialBlockSize(&_, &block_dim, kernel));
   return block_dim;
 }
 

mlx/backend/cuda/layer_norm.cu

@@ -258,23 +258,22 @@ void LayerNorm::eval_gpu(
   encoder.set_input_array(w);
   encoder.set_input_array(b);
   encoder.set_output_array(out);
-  dispatch_float_types(out.dtype(), "layernorm", [&](auto type_tag) {
-    constexpr uint32_t N_READS = 4;
-    dispatch_block_dim(cuda::ceil_div(axis_size, N_READS), [&](auto block_dim) {
-      using DataType = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-      auto kernel = cu::layer_norm<DataType, block_dim(), N_READS>;
-      encoder.add_kernel_node(
-          kernel,
-          n_rows,
-          block_dim(),
-          x.data<DataType>(),
-          w.data<DataType>(),
-          b.data<DataType>(),
-          out.data<DataType>(),
-          eps_,
-          axis_size,
-          w_stride,
-          b_stride);
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_FLOAT_TYPES_CHECKED(out.dtype(), "layernorm", CTYPE, {
+      using DataType = cuda_type_t<CTYPE>;
+      constexpr uint32_t N_READS = 4;
+      MLX_SWITCH_BLOCK_DIM(cuda::ceil_div(axis_size, N_READS), BLOCK_DIM, {
+        auto kernel = cu::layer_norm<DataType, BLOCK_DIM, N_READS>;
+        kernel<<<n_rows, BLOCK_DIM, 0, stream>>>(
+            x.data<DataType>(),
+            w.data<DataType>(),
+            b.data<DataType>(),
+            out.data<DataType>(),
+            eps_,
+            axis_size,
+            w_stride,
+            b_stride);
+      });
     });
   });
 }
@@ -289,25 +288,21 @@ void LayerNormVJP::eval_gpu(
   // Ensure row contiguity. We could relax this step by checking that the array
   // is contiguous (no broadcasts or holes) and that the input strides are the
   // same as the cotangent strides but for now this is simpler.
-  auto check_input = [&s](const array& x, bool& copied) {
+  auto check_input = [&s](const array& x) -> std::pair<array, bool> {
     if (x.flags().row_contiguous) {
-      copied = false;
-      return x;
+      return {x, false};
     }
-    copied = true;
     array x_copy(x.shape(), x.dtype(), nullptr, {});
     copy_gpu(x, x_copy, CopyType::General, s);
-    return x_copy;
+    return {x_copy, true};
   };
   bool donate_x = inputs[0].is_donatable();
   bool donate_g = inputs[3].is_donatable();
-  bool copied;
-  auto x = check_input(inputs[0], copied);
+  auto [x, copied] = check_input(inputs[0]);
   donate_x |= copied;
   const array& w = inputs[1];
   const array& b = inputs[2];
-  bool g_copied;
-  auto g = check_input(inputs[3], g_copied);
+  auto [g, g_copied] = check_input(inputs[3]);
   donate_g |= g_copied;
   array& gx = outputs[0];
   array& gw = outputs[1];
@@ -338,58 +333,47 @@ void LayerNormVJP::eval_gpu(
   // gradient accumulators.
   array gw_temp =
       (has_w) ? array({n_rows, x.shape().back()}, gw.dtype(), nullptr, {}) : w;
-  bool g_in_gw = false;
   if (has_w) {
     if (!g_in_gx && donate_g) {
-      g_in_gw = true;
       gw_temp.copy_shared_buffer(g);
     } else {
       gw_temp.set_data(allocator::malloc(gw_temp.nbytes()));
       encoder.add_temporary(gw_temp);
     }
   }
+  gw.set_data(allocator::malloc(gw.nbytes()));
+  gb.set_data(allocator::malloc(gb.nbytes()));
 
-  // The gradient for b in case we had a b.
-  bool has_gb = (gb.ndim() == 1 && gb.size() == axis_size);
-  if (has_gb) {
+  // Finish with the gradient for b in case we had a b.
+  if (gb.ndim() == 1 && gb.size() == axis_size) {
     ReductionPlan plan(
         ReductionOpType::ContiguousStridedReduce, {n_rows}, {axis_size});
     col_reduce(encoder, g, gb, Reduce::ReduceType::Sum, {0}, plan);
   }
 
-  // Insert dependency if `g` was donated
-  if ((g_in_gx || g_in_gw) && has_gb) {
-    encoder.set_input_array(gb);
-  }
   encoder.set_input_array(x);
   encoder.set_input_array(w);
   encoder.set_input_array(g);
   encoder.set_output_array(gx);
   encoder.set_output_array(gw_temp);
-  dispatch_float_types(gx.dtype(), "layernorm_vjp", [&](auto type_tag) {
-    dispatch_bool(has_w, [&](auto has_w_constant) {
+  encoder.launch_kernel([&, x = x, g = g](cudaStream_t stream) {
+    MLX_SWITCH_FLOAT_TYPES_CHECKED(gx.dtype(), "layernorm_vjp", CTYPE, {
+      using DataType = cuda_type_t<CTYPE>;
       constexpr int N_READS = 4;
-      dispatch_block_dim(
-          cuda::ceil_div(axis_size, N_READS), [&](auto block_dim) {
-            using DataType = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-            auto kernel = cu::layer_norm_vjp<
-                DataType,
-                has_w_constant.value,
-                block_dim(),
-                N_READS>;
-            encoder.add_kernel_node(
-                kernel,
-                n_rows,
-                block_dim(),
-                x.data<DataType>(),
-                w.data<DataType>(),
-                g.data<DataType>(),
-                gx.data<DataType>(),
-                gw_temp.data<DataType>(),
-                eps_,
-                axis_size,
-                w_stride);
-          });
+      MLX_SWITCH_BOOL(has_w, HAS_W, {
+        MLX_SWITCH_BLOCK_DIM(cuda::ceil_div(axis_size, N_READS), BLOCK_DIM, {
+          auto kernel = cu::layer_norm_vjp<DataType, HAS_W, BLOCK_DIM, N_READS>;
+          kernel<<<n_rows, BLOCK_DIM, 0, stream>>>(
+              x.data<DataType>(),
+              w.data<DataType>(),
+              g.data<DataType>(),
+              gx.data<DataType>(),
+              gw_temp.data<DataType>(),
+              eps_,
+              axis_size,
+              w_stride);
+        });
+      });
     });
   });
 

mlx/backend/cuda/logsumexp.cu

@@ -143,18 +143,15 @@ void LogSumExp::eval_gpu(const std::vector<array>& inputs, array& out) {
 
   encoder.set_input_array(in);
   encoder.set_output_array(out);
-  dispatch_float_types(out.dtype(), "logsumexp", [&](auto type_tag) {
-    constexpr int N_READS = 4;
-    dispatch_block_dim(cuda::ceil_div(axis_size, N_READS), [&](auto block_dim) {
-      using DataType = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-      auto kernel = cu::logsumexp<DataType, float, block_dim(), N_READS>;
-      encoder.add_kernel_node(
-          kernel,
-          n_rows,
-          block_dim(),
-          in.data<DataType>(),
-          out.data<DataType>(),
-          axis_size);
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_FLOAT_TYPES_CHECKED(out.dtype(), "logsumexp", CTYPE, {
+      using DataType = cuda_type_t<CTYPE>;
+      constexpr int N_READS = 4;
+      MLX_SWITCH_BLOCK_DIM(cuda::ceil_div(axis_size, N_READS), BLOCK_DIM, {
+        auto kernel = cu::logsumexp<DataType, float, BLOCK_DIM, N_READS>;
+        kernel<<<n_rows, BLOCK_DIM, 0, stream>>>(
+            in.data<DataType>(), out.data<DataType>(), axis_size);
+      });
     });
   });
 }

mlx/backend/cuda/matmul.cpp

@@ -42,8 +42,7 @@ class MatMul {
       int64_t ldb,
       int32_t batch_count,
       int64_t a_batch_stride,
-      int64_t b_batch_stride)
-      : handle_(device.lt_handle()) {
+      int64_t b_batch_stride) {
     heuristic_.state = CUBLAS_STATUS_NOT_INITIALIZED;
 
     auto scale_type = dtype_to_cuda_type(dtype);
@@ -148,7 +147,7 @@ class MatMul {
     if (heuristic_.state != CUBLAS_STATUS_SUCCESS) {
       int ret = 0;
       CHECK_CUBLAS_ERROR(cublasLtMatmulAlgoGetHeuristic(
-          handle_,
+          encoder.device().lt_handle(),
           matmul_desc_,
           a_desc_,
           b_desc_,
@@ -163,34 +162,31 @@ class MatMul {
       }
     }
 
-    void* workspace_ptr = nullptr;
-    if (heuristic_.workspaceSize > 0) {
-      array workspace(
-          allocator::malloc(heuristic_.workspaceSize),
-          {static_cast<int>(heuristic_.workspaceSize)},
-          int8);
-      encoder.add_temporary(workspace);
-      workspace_ptr = workspace.data<void>();
-    }
+    array workspace(
+        allocator::malloc(heuristic_.workspaceSize),
+        {static_cast<int>(heuristic_.workspaceSize)},
+        int8);
+    encoder.add_temporary(workspace);
 
-    auto capture = encoder.capture_context();
-    CHECK_CUBLAS_ERROR(cublasLtMatmul(
-        handle_,
-        matmul_desc_,
-        &alpha,
-        a,
-        a_desc_,
-        b,
-        b_desc_,
-        &beta,
-        c ? c : out,
-        c ? c_desc_ : out_desc_,
-        out,
-        out_desc_,
-        &heuristic_.algo,
-        workspace_ptr,
-        heuristic_.workspaceSize,
-        encoder.stream()));
+    encoder.launch_kernel([&](cudaStream_t stream) {
+      CHECK_CUBLAS_ERROR(cublasLtMatmul(
+          encoder.device().lt_handle(),
+          matmul_desc_,
+          &alpha,
+          a,
+          a_desc_,
+          b,
+          b_desc_,
+          &beta,
+          c ? c : out,
+          c ? c_desc_ : out_desc_,
+          out,
+          out_desc_,
+          &heuristic_.algo,
+          workspace.data<void>(),
+          workspace.nbytes(),
+          stream));
+    });
   }
 
  private:
@@ -259,7 +255,6 @@ class MatMul {
     return desc;
   }
 
-  cublasLtHandle_t handle_{nullptr};
   cublasLtMatmulDesc_t matmul_desc_{nullptr};
   cublasLtMatmulPreference_t pref_{nullptr};
   cublasLtMatrixLayout_t a_desc_{nullptr};
@@ -274,7 +269,7 @@ class MatMul {
 namespace {
 
 std::tuple<bool, int64_t, array>
-check_transpose(cu::CommandEncoder& enc, const Stream& s, const array& arr) {
+check_transpose(std::vector<array>& copies, const Stream& s, const array& arr) {
   auto stx = arr.strides()[arr.ndim() - 2];
   auto sty = arr.strides()[arr.ndim() - 1];
   if (sty == 1 && stx == arr.shape(-1)) {
@@ -284,7 +279,7 @@ check_transpose(cu::CommandEncoder& enc, const Stream& s, const array& arr) {
   } else {
     array arr_copy(arr.shape(), arr.dtype(), nullptr, {});
     copy_gpu(arr, arr_copy, CopyType::General, s);
-    enc.add_temporary(arr_copy);
+    copies.push_back(arr_copy);
     return std::make_tuple(false, arr.shape(-1), arr_copy);
   }
 }
@@ -318,8 +313,13 @@ void Matmul::eval_gpu(const std::vector<array>& inputs, array& out) {
 
   // Keep a vector with copies to be cleared in the completed buffer to release
   // the arrays
-  auto [a_transposed, lda, a] = check_transpose(encoder, s, a_pre);
-  auto [b_transposed, ldb, b] = check_transpose(encoder, s, b_pre);
+  std::vector<array> copies;
+  auto [a_transposed, lda, a] = check_transpose(copies, s, a_pre);
+  auto [b_transposed, ldb, b] = check_transpose(copies, s, b_pre);
+
+  for (auto& temp : copies) {
+    encoder.add_temporary(temp);
+  }
 
   /////////////////////////////////////////////////////////////////////////////
   // Check and collapse batch dimensions
@@ -344,7 +344,7 @@ void Matmul::eval_gpu(const std::vector<array>& inputs, array& out) {
   // Invoke cublasLt
 
   cu::MatMul matmul(
-      cu::device(s.device),
+      encoder.device(),
       a.dtype(),
       a_transposed,
       M,
@@ -358,19 +358,9 @@ void Matmul::eval_gpu(const std::vector<array>& inputs, array& out) {
       a_batch_strides.back(),
       b_batch_strides.back());
 
-  encoder.set_input_array(a);
-  encoder.set_input_array(b);
-  encoder.set_output_array(out);
-  auto nbatch = batch_count / batch_shape.back();
-  if (nbatch == 1) {
-    matmul.run(encoder, out.data<int8_t>(), a.data<int8_t>(), b.data<int8_t>());
-    return;
-  }
-
   ContiguousIterator a_it(batch_shape, a_batch_strides, batch_shape.size() - 1);
   ContiguousIterator b_it(batch_shape, b_batch_strides, batch_shape.size() - 1);
-  auto concurrent = encoder.concurrent_context();
-  for (size_t i = 0; i < nbatch; ++i) {
+  for (size_t i = 0; i < batch_count / batch_shape.back(); ++i) {
     matmul.run(
         encoder,
         out.data<int8_t>() + out.itemsize() * i * batch_shape.back() * M * N,
@@ -402,9 +392,14 @@ void AddMM::eval_gpu(const std::vector<array>& inputs, array& out) {
 
   // Keep a vector with copies to be cleared in the completed buffer to release
   // the arrays
-  auto [a_transposed, lda, a] = check_transpose(encoder, s, a_pre);
-  auto [b_transposed, ldb, b] = check_transpose(encoder, s, b_pre);
-  auto [c_transposed, ldc, c] = check_transpose(encoder, s, c_pre);
+  std::vector<array> copies;
+  auto [a_transposed, lda, a] = check_transpose(copies, s, a_pre);
+  auto [b_transposed, ldb, b] = check_transpose(copies, s, b_pre);
+  auto [c_transposed, ldc, c] = check_transpose(copies, s, c_pre);
+
+  for (auto& temp : copies) {
+    encoder.add_temporary(temp);
+  }
 
   /////////////////////////////////////////////////////////////////////////////
   // Check and collapse batch dimensions
@@ -432,7 +427,7 @@ void AddMM::eval_gpu(const std::vector<array>& inputs, array& out) {
   // Invoke cublasLt
 
   cu::MatMul matmul(
-      cu::device(s.device),
+      encoder.device(),
       a.dtype(),
       a_transposed,
       M,
@@ -449,29 +444,10 @@ void AddMM::eval_gpu(const std::vector<array>& inputs, array& out) {
       b_batch_strides.back(),
       c_batch_strides.back());
 
-  encoder.set_input_array(a);
-  encoder.set_input_array(b);
-  encoder.set_input_array(c);
-  encoder.set_output_array(out);
-
-  auto nbatch = batch_count / batch_shape.back();
-  if (nbatch == 1) {
-    matmul.run(
-        encoder,
-        out.data<int8_t>(),
-        a.data<int8_t>(),
-        b.data<int8_t>(),
-        c.data<int8_t>(),
-        alpha_,
-        beta_);
-    return;
-  }
-
   ContiguousIterator a_it(batch_shape, a_batch_strides, batch_shape.size() - 1);
   ContiguousIterator b_it(batch_shape, b_batch_strides, batch_shape.size() - 1);
   ContiguousIterator c_it(batch_shape, c_batch_strides, batch_shape.size() - 1);
-  auto concurrent = encoder.concurrent_context();
-  for (size_t i = 0; i < nbatch; ++i) {
+  for (size_t i = 0; i < batch_count / batch_shape.back(); ++i) {
     matmul.run(
         encoder,
         out.data<int8_t>() + out.itemsize() * i * batch_shape.back() * M * N,

mlx/backend/cuda/primitives.cu

@@ -24,21 +24,22 @@ void Arange::eval_gpu(const std::vector<array>& inputs, array& out) {
   if (out.size() == 0) {
     return;
   }
-  auto& encoder = cu::get_command_encoder(stream());
+  auto& s = stream();
+  auto& encoder = cu::get_command_encoder(s);
   encoder.set_output_array(out);
-  auto capture = encoder.capture_context();
-  dispatch_int_float_types(out.dtype(), "Arange", [&](auto type_tag) {
-    using CTYPE = MLX_GET_TYPE(type_tag);
-    using OutType = cuda_type_t<CTYPE>;
-    CTYPE step =
-        static_cast<CTYPE>(start_ + step_) - static_cast<CTYPE>(start_);
-    thrust::transform(
-        cu::thrust_policy(encoder.stream()),
-        thrust::counting_iterator<uint32_t>(0),
-        thrust::counting_iterator<uint32_t>(out.data_size()),
-        thrust::device_pointer_cast(out.data<OutType>()),
-        cu::Arange<OutType>{
-            static_cast<OutType>(start_), static_cast<OutType>(step)});
+  encoder.launch_kernel([&, this](cudaStream_t stream) {
+    MLX_SWITCH_INT_FLOAT_TYPES_CHECKED(out.dtype(), "Arange", CTYPE, {
+      using OutType = cuda_type_t<CTYPE>;
+      CTYPE step =
+          static_cast<CTYPE>(start_ + step_) - static_cast<CTYPE>(start_);
+      thrust::transform(
+          cu::thrust_policy(stream),
+          thrust::counting_iterator<uint32_t>(0),
+          thrust::counting_iterator<uint32_t>(out.data_size()),
+          thrust::device_pointer_cast(out.data<OutType>()),
+          cu::Arange<OutType>{
+              static_cast<OutType>(start_), static_cast<OutType>(step)});
+    });
   });
 }
 
@@ -70,8 +71,10 @@ bool fast::ScaledDotProductAttention::use_fallback(
     throw std::runtime_error(#func " has no CUDA implementation.");   \
   }
 
+NO_GPU(ArgPartition)
 NO_GPU(BlockMaskedMM)
 NO_GPU(Convolution)
+NO_GPU_MULTI(DivMod)
 NO_GPU(DynamicSlice)
 NO_GPU(DynamicSliceUpdate)
 NO_GPU(FFT)
@@ -80,9 +83,10 @@ NO_GPU(GatherQMM)
 NO_GPU(Hadamard)
 NO_GPU(Load)
 NO_GPU_MULTI(LUF)
+NO_GPU(Partition)
 NO_GPU_MULTI(QRF)
 NO_GPU(QuantizedMatmul)
-NO_GPU(SegmentedMM)
+NO_GPU(Scan)
 NO_GPU_MULTI(SVD)
 NO_GPU(Inverse)
 NO_GPU(Cholesky)

mlx/backend/cuda/random.cu

@@ -156,39 +156,34 @@ void RandomBits::eval_gpu(const std::vector<array>& inputs, array& out) {
   auto& encoder = cu::get_command_encoder(s);
   encoder.set_input_array(keys);
   encoder.set_output_array(out);
-  dim3 grid_dims{num_keys, half_size + odd};
-  int64_t total = grid_dims.x * grid_dims.y;
-  int32_t threads_y = 1;
-  while ((total / threads_y) >= (1U << 31)) {
-    threads_y *= 2;
-  }
-  int32_t threads_x = cuda::ceil_div(total, threads_y);
-  auto [grid, block] = get_grid_and_block(threads_x, threads_y, 1);
-  auto& stream = encoder.stream();
-  if (keys.flags().row_contiguous) {
-    encoder.add_kernel_node(
-        cu::rbitsc,
-        grid,
-        block,
-        keys.data<uint32_t>(),
-        out.data<uint8_t>(),
-        grid_dims,
-        odd,
-        bytes_per_key);
-  } else {
-    encoder.add_kernel_node(
-        cu::rbits,
-        grid,
-        block,
-        keys.data<uint32_t>(),
-        out.data<uint8_t>(),
-        grid_dims,
-        odd,
-        bytes_per_key,
-        keys.ndim(),
-        const_param(keys.shape()),
-        const_param(keys.strides()));
-  }
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    dim3 grid_dims{num_keys, half_size + odd};
+    int64_t total = grid_dims.x * grid_dims.y;
+    int32_t threads_y = 1;
+    while ((total / threads_y) >= (1U << 31)) {
+      threads_y *= 2;
+    }
+    int32_t threads_x = cuda::ceil_div(total, threads_y);
+    auto [grid, block] = get_grid_and_block(threads_x, threads_y, 1);
+    if (keys.flags().row_contiguous) {
+      cu::rbitsc<<<grid, block, 0, stream>>>(
+          keys.data<uint32_t>(),
+          out.data<uint8_t>(),
+          grid_dims,
+          odd,
+          bytes_per_key);
+    } else {
+      cu::rbits<<<grid, block, 0, stream>>>(
+          keys.data<uint32_t>(),
+          out.data<uint8_t>(),
+          grid_dims,
+          odd,
+          bytes_per_key,
+          keys.ndim(),
+          const_param(keys.shape()),
+          const_param(keys.strides()));
+    }
+  });
 }
 
 } // namespace mlx::core

mlx/backend/cuda/reduce.cu

@@ -21,11 +21,28 @@ void Reduce::eval_gpu(const std::vector<array>& inputs, array& out) {
   assert(!axes_.empty());
   assert(out.size() != in.size());
 
+  out.set_data(allocator::malloc(out.nbytes()));
+
   auto& s = stream();
   auto& encoder = cu::get_command_encoder(s);
+  encoder.set_input_array(in);
+  encoder.set_output_array(out);
 
+  // Fill out with init value.
   if (in.size() == 0) {
-    init_reduce(encoder, in, out, reduce_type_);
+    encoder.launch_kernel([&](cudaStream_t stream) {
+      MLX_SWITCH_ALL_TYPES(in.dtype(), CTYPE, {
+        MLX_SWITCH_REDUCE_OPS(reduce_type_, OP, {
+          using InType = cuda_type_t<CTYPE>;
+          using OutType = cu::ReduceResult<OP, InType>::type;
+          thrust::fill_n(
+              cu::thrust_policy(stream),
+              thrust::device_pointer_cast(out.data<OutType>()),
+              out.data_size(),
+              cu::ReduceInit<OP, InType>::value());
+        });
+      });
+    });
     return;
   }
 
@@ -34,19 +51,7 @@ void Reduce::eval_gpu(const std::vector<array>& inputs, array& out) {
 
   // If it is a general reduce then copy the input to a contiguous array and
   // recompute the plan.
-  //
-  // TODO: Instead of copying we can use elem-to-loc to deal with broadcasting
-  //       like we do in Metal. When it comes to broadcasted reduction axes
-  //       some can be ignored eg for min/max.
-  bool broadcasted = false;
-  for (int i = 0, j = 0; i < in.ndim() && !broadcasted; i++) {
-    if (j < axes_.size() && axes_[j] == i) {
-      j++;
-    } else {
-      broadcasted = in.strides(i) == 0;
-    }
-  }
-  if (plan.type == GeneralReduce || broadcasted || !in.flags().contiguous) {
+  if (plan.type == GeneralReduce) {
     array in_copy(in.shape(), in.dtype(), nullptr, {});
     copy_gpu(in, in_copy, CopyType::General, s);
     encoder.add_temporary(in_copy);
@@ -54,8 +59,9 @@ void Reduce::eval_gpu(const std::vector<array>& inputs, array& out) {
     plan = get_reduction_plan(in, axes_);
   }
 
-  if (plan.type == ContiguousAllReduce) {
-    all_reduce(encoder, in, out, reduce_type_);
+  if ((plan.type == ContiguousAllReduce) ||
+      (plan.type == ContiguousReduce && plan.shape.size() == 1)) {
+    segmented_reduce(encoder, in, out, reduce_type_, axes_, plan);
     return;
   }
 

mlx/backend/cuda/reduce/all_reduce.cu

@@ -1,157 +0,0 @@
-// Copyright © 2025 Apple Inc.
-
-#include "mlx/backend/cuda/device.h"
-#include "mlx/backend/cuda/reduce/reduce.cuh"
-
-#include <cooperative_groups.h>
-#include <cooperative_groups/reduce.h>
-#include <cub/block/block_load.cuh>
-
-namespace mlx::core {
-
-namespace cu {
-
-namespace cg = cooperative_groups;
-
-template <typename T, typename U, typename ReduceOp, int N = 4>
-__global__ void all_reduce(T* in, U* out, size_t block_step, size_t size) {
-  // TODO: Process multiple "rows" in each thread
-  constexpr int M = 1;
-
-  auto grid = cg::this_grid();
-  auto block = cg::this_thread_block();
-  auto warp = cg::tiled_partition<WARP_SIZE>(block);
-
-  const U init = cu::ReduceInit<ReduceOp, T>::value();
-  ReduceOp op;
-
-  T vals[N];
-  U accs[M];
-  accs[0] = init;
-
-  size_t start = grid.block_rank() * block_step;
-  size_t end = start + block_step;
-  size_t check = min(end, size);
-
-  size_t i = start;
-  for (; i + block.size() * N <= check; i += block.size() * N) {
-    cub::LoadDirectBlockedVectorized<T, N>(block.thread_rank(), in + i, vals);
-    for (int j = 0; j < N; j++) {
-      accs[0] = op(accs[0], cast_to<U>(vals[j]));
-    }
-  }
-
-  if (i < check) {
-    cub::LoadDirectBlocked(
-        block.thread_rank(), in + i, vals, check - i, cast_to<T>(init));
-    for (int i = 0; i < N; i++) {
-      accs[0] = op(accs[0], cast_to<U>(vals[i]));
-    }
-  }
-
-  __shared__ U shared_accumulators[32];
-  block_reduce(block, warp, accs, shared_accumulators, op, init);
-
-  if (block.thread_rank() == 0) {
-    out[grid.block_rank()] = accs[0];
-  }
-}
-
-} // namespace cu
-
-void all_reduce(
-    cu::CommandEncoder& encoder,
-    const array& in,
-    array& out,
-    Reduce::ReduceType reduce_type) {
-  constexpr int N_READS = 8;
-
-  out.set_data(allocator::malloc(out.nbytes()));
-
-  auto get_args = [](size_t size, int N) {
-    int threads = std::min(512UL, (size + N - 1) / N);
-    threads = ((threads + WARP_SIZE - 1) / WARP_SIZE) * WARP_SIZE;
-    int reductions_per_step = threads * N;
-    size_t steps_needed =
-        (size + reductions_per_step - 1) / reductions_per_step;
-
-    int blocks;
-    if (steps_needed < 32) {
-      blocks = 1;
-    } else if (steps_needed < 128) {
-      blocks = 32;
-    } else if (steps_needed < 512) {
-      blocks = 128;
-    } else if (steps_needed < 1024) {
-      blocks = 512;
-    } else {
-      blocks = 1024;
-    }
-
-    size_t steps_per_block = (steps_needed + blocks - 1) / blocks;
-    size_t block_step = steps_per_block * reductions_per_step;
-
-    return std::make_tuple(blocks, threads, block_step);
-  };
-
-  int blocks, threads;
-  size_t block_step;
-  size_t insize = in.size();
-  Dtype dt = in.dtype();
-
-  // Cub doesn't like const pointers for load (sigh).
-  void* indata = const_cast<void*>(in.data<void>());
-
-  // Large array so allocate an intermediate and accumulate there
-  std::tie(blocks, threads, block_step) = get_args(insize, N_READS);
-  encoder.set_input_array(in);
-  if (blocks > 1) {
-    array intermediate({blocks}, out.dtype(), nullptr, {});
-    intermediate.set_data(allocator::malloc(intermediate.nbytes()));
-    encoder.add_temporary(intermediate);
-    encoder.set_output_array(intermediate);
-    dispatch_all_types(dt, [&](auto type_tag) {
-      dispatch_reduce_ops(reduce_type, [&](auto reduce_type_tag) {
-        using OP = MLX_GET_TYPE(reduce_type_tag);
-        using T = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-        using U = typename cu::ReduceResult<OP, T>::type;
-        auto kernel = cu::all_reduce<T, U, OP, N_READS>;
-        encoder.add_kernel_node(
-            kernel,
-            blocks,
-            threads,
-            static_cast<T*>(indata),
-            intermediate.data<U>(),
-            block_step,
-            insize);
-      });
-    });
-
-    // Set the input for the next step and recalculate the blocks
-    indata = intermediate.data<void>();
-    dt = intermediate.dtype();
-    insize = intermediate.size();
-    std::tie(blocks, threads, block_step) = get_args(insize, N_READS);
-    encoder.set_input_array(intermediate);
-  }
-
-  encoder.set_output_array(out);
-  dispatch_all_types(dt, [&](auto type_tag) {
-    dispatch_reduce_ops(reduce_type, [&](auto reduce_type_tag) {
-      using OP = MLX_GET_TYPE(reduce_type_tag);
-      using T = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-      using U = typename cu::ReduceResult<OP, T>::type;
-      auto kernel = cu::all_reduce<T, U, OP, N_READS>;
-      encoder.add_kernel_node(
-          kernel,
-          blocks,
-          threads,
-          static_cast<T*>(indata),
-          out.data<U>(),
-          block_step,
-          insize);
-    });
-  });
-}
-
-} // namespace mlx::core

mlx/backend/cuda/reduce/col_reduce.cu

@@ -1,8 +1,7 @@
 // Copyright © 2025 Apple Inc.
 
-#include <numeric>
-
 #include "mlx/backend/cuda/device.h"
+#include "mlx/backend/cuda/device/cast_op.cuh"
 #include "mlx/backend/cuda/reduce/reduce.cuh"
 
 #include <cooperative_groups.h>
@@ -37,36 +36,19 @@ struct ColReduceArgs {
       const array& in,
       const ReductionPlan& plan,
       const std::vector<int>& axes) {
-    using ShapeVector = decltype(plan.shape);
-    using StridesVector = decltype(plan.strides);
-
-    ShapeVector shape_vec;
-    StridesVector strides_vec;
-
     assert(!plan.shape.empty());
     reduction_size = plan.shape.back();
     reduction_stride = plan.strides.back();
 
     int64_t stride_back = 1;
-    std::tie(shape_vec, strides_vec) = shapes_without_reduction_axes(in, axes);
+    auto [shape_vec, strides_vec] = shapes_without_reduction_axes(in, axes);
     while (!shape_vec.empty() && stride_back < reduction_stride) {
       stride_back *= shape_vec.back();
       shape_vec.pop_back();
       strides_vec.pop_back();
     }
-    std::vector<int> indices(shape_vec.size());
-    std::iota(indices.begin(), indices.end(), 0);
-    std::sort(indices.begin(), indices.end(), [&](int left, int right) {
-      return strides_vec[left] > strides_vec[right];
-    });
-    ShapeVector sorted_shape;
-    StridesVector sorted_strides;
-    for (auto idx : indices) {
-      sorted_shape.push_back(shape_vec[idx]);
-      sorted_strides.push_back(strides_vec[idx]);
-    }
     std::tie(shape_vec, strides_vec) =
-        collapse_contiguous_dims(sorted_shape, sorted_strides);
+        collapse_contiguous_dims(shape_vec, strides_vec);
     shape = const_param(shape_vec);
     strides = const_param(strides_vec);
     ndim = shape_vec.size();
@@ -82,6 +64,86 @@ struct ColReduceArgs {
   }
 };
 
+template <typename T, typename U, typename Op, int NDIM, int N_READS = 4>
+__global__ void col_reduce_small(
+    const T* in,
+    U* out,
+    const __grid_constant__ ColReduceArgs args) {
+  auto grid = cg::this_grid();
+  auto block = cg::this_thread_block();
+
+  int column =
+      grid.block_index().x * block.dim_threads().x + block.thread_index().x;
+  if (column * N_READS >= args.reduction_stride) {
+    return;
+  }
+
+  int out_idx = grid.block_rank() / grid.dim_blocks().x;
+  in += elem_to_loc(out_idx, args.shape.data(), args.strides.data(), args.ndim);
+
+  Op op;
+  U totals[N_READS];
+  for (int i = 0; i < N_READS; i++) {
+    totals[i] = ReduceInit<Op, T>::value();
+  }
+
+  // Read input to local.
+  LoopedElemToLoc<NDIM, (NDIM > 2)> loop(args.reduce_ndim);
+  loop.next(
+      block.thread_index().y,
+      args.reduce_shape.data(),
+      args.reduce_strides.data());
+  for (size_t r = block.thread_index().y;
+       r < args.non_col_reductions * args.reduction_size;
+       r += block.dim_threads().y) {
+    U vals[N_READS];
+    cub::LoadDirectBlocked(
+        column,
+        make_cast_iterator<U>(in + loop.location()),
+        vals,
+        args.reduction_stride,
+        ReduceInit<Op, T>::value());
+    for (int i = 0; i < N_READS; i++) {
+      totals[i] = op(vals[i], totals[i]);
+    }
+    loop.next(
+        block.dim_threads().y,
+        args.reduce_shape.data(),
+        args.reduce_strides.data());
+  }
+
+  // Do block reduce when each column has more than 1 element to reduce.
+  if (block.dim_threads().y > 1) {
+    __shared__ U shared_vals[32 * 8 * N_READS];
+    size_t col =
+        block.thread_index().y * block.dim_threads().x + block.thread_index().x;
+    for (int i = 0; i < N_READS; i++) {
+      shared_vals[col * N_READS + i] = totals[i];
+    }
+    block.sync();
+    if (block.thread_index().y == 0) {
+      for (int i = 0; i < N_READS; i++) {
+        totals[i] = shared_vals[block.thread_index().x * N_READS + i];
+      }
+      for (int j = 1; j < block.dim_threads().y; j++) {
+        col = j * block.dim_threads().x + block.thread_index().x;
+        for (int i = 0; i < N_READS; i++) {
+          totals[i] = op(shared_vals[col * N_READS + i], totals[i]);
+        }
+      }
+    }
+  }
+
+  // Write result.
+  if (block.thread_index().y == 0) {
+    cub::StoreDirectBlocked(
+        column,
+        out + out_idx * args.reduction_stride,
+        totals,
+        args.reduction_stride);
+  }
+}
+
 template <
     typename T,
     typename U,
@@ -90,94 +152,67 @@ template <
     int BM,
     int BN,
     int N_READS = 4>
-__global__ void
-col_reduce_looped(T* in, U* out, const __grid_constant__ ColReduceArgs args) {
+__global__ void col_reduce_looped(
+    const T* in,
+    U* out,
+    const __grid_constant__ ColReduceArgs args) {
   auto grid = cg::this_grid();
   auto block = cg::this_thread_block();
   auto warp = cg::tiled_partition<WARP_SIZE>(block);
 
-  constexpr int threads_per_row = BN / N_READS;
+  constexpr int n_warps = BN / N_READS;
 
-  // Compute the indices for the tile
-  size_t tile_idx = grid.block_rank();
-  size_t tile_x = tile_idx % ((args.reduction_stride + BN - 1) / BN);
-  size_t tile_y = tile_idx / ((args.reduction_stride + BN - 1) / BN);
+  int out_idx = grid.block_rank() / grid.dim_blocks().x;
+  in += elem_to_loc(out_idx, args.shape.data(), args.strides.data(), args.ndim);
 
-  // Compute the indices for the thread within the tile
-  short thread_x = block.thread_rank() % threads_per_row;
-  short thread_y = block.thread_rank() / threads_per_row;
-
-  // Move the input pointer
-  in += elem_to_loc(tile_y, args.shape.data(), args.strides.data(), args.ndim) +
-      tile_x * BN;
-
-  // Initialize the running totals
   Op op;
   U totals[N_READS];
   for (int i = 0; i < N_READS; i++) {
     totals[i] = ReduceInit<Op, T>::value();
   }
 
+  // Read input to local.
+  int r = block.thread_rank() / n_warps;
+  int column = block.thread_rank() % n_warps;
+  int in_offset = grid.block_index().x * BN;
   LoopedElemToLoc<NDIM, (NDIM > 2)> loop(args.reduce_ndim);
-  loop.next(thread_y, args.reduce_shape.data(), args.reduce_strides.data());
-  size_t total = args.non_col_reductions * args.reduction_size;
-  if (tile_x * BN + BN <= args.reduction_stride) {
-    if (args.reduction_stride % N_READS == 0) {
-      for (size_t r = thread_y; r < total; r += BM) {
-        T vals[N_READS];
-        cub::LoadDirectBlockedVectorized(thread_x, in + loop.location(), vals);
-        for (int i = 0; i < N_READS; i++) {
-          totals[i] = op(totals[i], cast_to<U>(vals[i]));
-        }
-        loop.next(BM, args.reduce_shape.data(), args.reduce_strides.data());
-      }
-    } else {
-      for (size_t r = thread_y; r < total; r += BM) {
-        T vals[N_READS];
-        cub::LoadDirectBlocked(thread_x, in + loop.location(), vals);
-        for (int i = 0; i < N_READS; i++) {
-          totals[i] = op(totals[i], cast_to<U>(vals[i]));
-        }
-        loop.next(BM, args.reduce_shape.data(), args.reduce_strides.data());
-      }
-    }
-  } else {
-    for (size_t r = thread_y; r < total; r += BM) {
-      T vals[N_READS];
-      cub::LoadDirectBlocked(
-          thread_x,
-          in + loop.location(),
-          vals,
-          args.reduction_stride - tile_x * BN,
-          cast_to<T>(ReduceInit<Op, T>::value()));
-      for (int i = 0; i < N_READS; i++) {
-        totals[i] = op(totals[i], cast_to<U>(vals[i]));
-      }
-      loop.next(BM, args.reduce_shape.data(), args.reduce_strides.data());
+  loop.next(r, args.reduce_shape.data(), args.reduce_strides.data());
+  for (; r < args.non_col_reductions * args.reduction_size; r += BM) {
+    U vals[N_READS];
+    cub::LoadDirectBlocked(
+        column,
+        make_cast_iterator<U>(in + loop.location() + in_offset),
+        vals,
+        args.reduction_stride - in_offset,
+        ReduceInit<Op, T>::value());
+    for (int i = 0; i < N_READS; i++) {
+      totals[i] = op(vals[i], totals[i]);
     }
+    loop.next(BM, args.reduce_shape.data(), args.reduce_strides.data());
   }
 
   // Do warp reduce for each output.
-  constexpr int n_outputs = BN / threads_per_row;
+  constexpr int n_outputs = BN / n_warps;
   static_assert(BM == 32 && n_outputs == N_READS);
   __shared__ U shared_vals[BM * BN];
-  short s_idx = thread_y * BN + thread_x * N_READS;
+  size_t col = block.thread_index().y * BN + block.thread_index().x * N_READS;
   for (int i = 0; i < N_READS; i++) {
-    shared_vals[s_idx + i] = totals[i];
+    shared_vals[col + i] = totals[i];
   }
   block.sync();
-  s_idx = warp.thread_rank() * BN + warp.meta_group_rank() * n_outputs;
+  col = warp.thread_rank() * BN + warp.meta_group_rank() * n_outputs;
   for (int i = 0; i < n_outputs; i++) {
-    totals[i] = cg::reduce(warp, shared_vals[s_idx + i], op);
+    totals[i] = cg::reduce(warp, shared_vals[col + i], op);
   }
 
   // Write result.
   if (warp.thread_rank() == 0) {
+    size_t out_offset = grid.block_index().x * BN;
     cub::StoreDirectBlocked(
         warp.meta_group_rank(),
-        out + tile_y * args.reduction_stride + tile_x * BN,
+        out + out_idx * args.reduction_stride + out_offset,
         totals,
-        args.reduction_stride - tile_x * BN);
+        args.reduction_stride - out_offset);
   }
 }
 
@@ -185,55 +220,14 @@ col_reduce_looped(T* in, U* out, const __grid_constant__ ColReduceArgs args) {
 
 inline auto output_grid_for_col_reduce(
     const array& out,
-    const cu::ColReduceArgs& args,
-    int bn) {
-  int gx, gy = 1;
-  size_t n_inner_blocks = cuda::ceil_div(args.reduction_stride, bn);
-  size_t n_outer_blocks = out.size() / args.reduction_stride;
-  size_t n_blocks = n_outer_blocks * n_inner_blocks;
-  while (n_blocks / gy > INT32_MAX) {
-    gy *= 2;
+    const cu::ColReduceArgs& args) {
+  auto out_shape = out.shape();
+  auto out_strides = out.strides();
+  while (!out_shape.empty() && out_strides.back() < args.reduction_stride) {
+    out_shape.pop_back();
+    out_strides.pop_back();
   }
-  gx = cuda::ceil_div(n_blocks, gy);
-
-  return dim3(gx, gy, 1);
-}
-
-void col_reduce_looped(
-    cu::CommandEncoder& encoder,
-    const array& in,
-    array& out,
-    Reduce::ReduceType reduce_type,
-    const std::vector<int>& axes,
-    const ReductionPlan& plan,
-    cu::ColReduceArgs args) {
-  // Allocate data for the output using in's layout to access them as
-  // contiguously as possible.
-  allocate_same_layout(out, in, axes);
-
-  encoder.set_input_array(in);
-  encoder.set_output_array(out);
-  dispatch_all_types(in.dtype(), [&](auto type_tag) {
-    dispatch_reduce_ops(reduce_type, [&](auto reduce_type_tag) {
-      dispatch_reduce_ndim(args.reduce_ndim, [&](auto reduce_ndim) {
-        using OP = MLX_GET_TYPE(reduce_type_tag);
-        using T = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-        using U = typename cu::ReduceResult<OP, T>::type;
-        // Cub doesn't like const pointers for vectorized loads. (sigh)
-        T* indata = const_cast<T*>(in.data<T>());
-
-        constexpr int N_READS = 4;
-        constexpr int BM = 32;
-        constexpr int BN = 32;
-        dim3 grid = output_grid_for_col_reduce(out, args, BN);
-        int blocks = BM * BN / N_READS;
-        auto kernel =
-            cu::col_reduce_looped<T, U, OP, reduce_ndim(), BM, BN, N_READS>;
-        encoder.add_kernel_node(
-            kernel, grid, blocks, indata, out.data<U>(), args);
-      });
-    });
-  });
+  return get_2d_grid_dims(out_shape, out_strides);
 }
 
 void col_reduce(
@@ -243,23 +237,42 @@ void col_reduce(
     Reduce::ReduceType reduce_type,
     const std::vector<int>& axes,
     const ReductionPlan& plan) {
-  // Current col reduce options
-  //
-  // - col_reduce_looped
-  //
-  //   It is a general strided reduce. Each threadblock computes the output for
-  //   a subrow of the fast moving axis. For instance 32 elements.
-  //
-  // Notes: As in row reduce we opt to read as much in order as possible and
-  //        leave transpositions as they are (contrary to our Metal backend).
-  //
-  //        Moreover we need different kernels for short rows and tuning
-
-  // Make the args struct to help route to the best kernel
   cu::ColReduceArgs args(in, plan, axes);
 
-  // Fallback col reduce
-  col_reduce_looped(encoder, in, out, reduce_type, axes, plan, args);
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_ALL_TYPES(in.dtype(), CTYPE, {
+      using InType = cuda_type_t<CTYPE>;
+      MLX_SWITCH_REDUCE_OPS(reduce_type, OP, {
+        using OutType = cu::ReduceResult<OP, InType>::type;
+        MLX_SWITCH_REDUCE_NDIM(args.reduce_ndim, NDIM, {
+          constexpr int N_READS = 4;
+          dim3 block_dims;
+          dim3 num_blocks = output_grid_for_col_reduce(out, args);
+          num_blocks.z = num_blocks.y;
+          num_blocks.y = num_blocks.x;
+          auto kernel =
+              cu::col_reduce_small<InType, OutType, OP, NDIM, N_READS>;
+          size_t total = args.non_col_reductions * args.reduction_size;
+          if (total < 32) {
+            size_t stride_blocks =
+                cuda::ceil_div(args.reduction_stride, N_READS);
+            block_dims.x = std::min(stride_blocks, 32ul);
+            block_dims.y = std::min(total, 8ul);
+            num_blocks.x = cuda::ceil_div(stride_blocks, block_dims.x);
+          } else {
+            constexpr int BM = 32;
+            constexpr int BN = 32;
+            block_dims.x = BM * BN / N_READS;
+            num_blocks.x = cuda::ceil_div(args.reduction_stride, BN);
+            kernel = cu::
+                col_reduce_looped<InType, OutType, OP, NDIM, BM, BN, N_READS>;
+          }
+          kernel<<<num_blocks, block_dims, 0, stream>>>(
+              in.data<InType>(), out.data<OutType>(), args);
+        });
+      });
+    });
+  });
 }
 
 } // namespace mlx::core

mlx/backend/cuda/reduce/init_reduce.cu

@@ -1,49 +0,0 @@
-// Copyright © 2025 Apple Inc.
-
-#include "mlx/backend/cuda/device.h"
-#include "mlx/backend/cuda/reduce/reduce.cuh"
-
-#include <cooperative_groups.h>
-
-namespace mlx::core {
-
-namespace cu {
-
-namespace cg = cooperative_groups;
-
-template <typename T, typename U, typename Op>
-__global__ void init_reduce(U* out, size_t size) {
-  auto index = cg::this_grid().thread_rank();
-  if (index < size) {
-    out[index] = ReduceInit<Op, T>::value();
-  }
-}
-
-} // namespace cu
-
-void init_reduce(
-    cu::CommandEncoder& encoder,
-    const array& in,
-    array& out,
-    Reduce::ReduceType reduce_type) {
-  // Allocate if needed
-  if (out.data_shared_ptr() == nullptr) {
-    out.set_data(allocator::malloc(out.nbytes()));
-  }
-
-  encoder.set_output_array(out);
-  dispatch_all_types(in.dtype(), [&](auto type_tag) {
-    dispatch_reduce_ops(reduce_type, [&](auto reduce_type_tag) {
-      using OP = MLX_GET_TYPE(reduce_type_tag);
-      using T = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-      using U = typename cu::ReduceResult<OP, T>::type;
-      auto kernel = cu::init_reduce<T, U, OP>;
-      dim3 grid = get_2d_grid_dims(out.shape(), out.strides());
-      dim3 block(grid.x < 1024 ? grid.x : 1024, 1, 1);
-      grid.x = (grid.x + 1023) / 1024;
-      encoder.add_kernel_node(kernel, grid, block, out.data<U>(), out.size());
-    });
-  });
-}
-
-} // namespace mlx::core

mlx/backend/cuda/reduce/reduce.cuh

@@ -1,7 +1,5 @@
 // Copyright © 2025 Apple Inc.
 
-#include <type_traits>
-
 #include "mlx/backend/common/reduce.h"
 #include "mlx/backend/cuda/device/cucomplex_math.cuh"
 #include "mlx/backend/cuda/kernel_utils.cuh"
@@ -11,41 +9,51 @@
 
 namespace mlx::core {
 
-template <typename F>
-void dispatch_reduce_ndim(int ndim, F&& f) {
-  if (ndim == 1) {
-    f(std::integral_constant<int, 1>{});
-  } else if (ndim == 2) {
-    f(std::integral_constant<int, 2>{});
-  } else {
-    f(std::integral_constant<int, 5>{});
+// Dispatch dynamic ndim to constexpr.
+// The behavior follows get_kernel_reduce_ndim in metal/reduce.cpp file.
+#define MLX_SWITCH_REDUCE_NDIM(ndim, NDIM, ...) \
+  if (ndim == 1) {                              \
+    constexpr uint32_t NDIM = 1;                \
+    __VA_ARGS__;                                \
+  } else if (ndim == 2) {                       \
+    constexpr uint32_t NDIM = 2;                \
+    __VA_ARGS__;                                \
+  } else {                                      \
+    constexpr uint32_t NDIM = 5;                \
+    __VA_ARGS__;                                \
   }
-}
 
-template <typename F>
-void dispatch_reduce_ops(Reduce::ReduceType reduce_type, F&& f) {
-  if (reduce_type == Reduce::ReduceType::And) {
-    f(type_identity<cu::And>{});
-  } else if (reduce_type == Reduce::ReduceType::Or) {
-    f(type_identity<cu::Or>{});
-  } else if (reduce_type == Reduce::ReduceType::Sum) {
-    f(type_identity<cu::Sum>{});
-  } else if (reduce_type == Reduce::ReduceType::Prod) {
-    f(type_identity<cu::Prod>{});
-  } else if (reduce_type == Reduce::ReduceType::Max) {
-    f(type_identity<cu::Max>{});
-  } else if (reduce_type == Reduce::ReduceType::Min) {
-    f(type_identity<cu::Min>{});
-  } else {
-    throw std::invalid_argument("Unknown reduce type.");
+// Dispatch reduce ops to constexpr.
+#define MLX_SWITCH_REDUCE_OPS(REDUCE, OP, ...)           \
+  if (REDUCE == Reduce::ReduceType::And) {               \
+    using OP = cu::And;                                  \
+    __VA_ARGS__;                                         \
+  } else if (REDUCE == Reduce::ReduceType::Or) {         \
+    using OP = cu::Or;                                   \
+    __VA_ARGS__;                                         \
+  } else if (REDUCE == Reduce::ReduceType::Sum) {        \
+    using OP = cu::Sum;                                  \
+    __VA_ARGS__;                                         \
+  } else if (REDUCE == Reduce::ReduceType::Prod) {       \
+    using OP = cu::Prod;                                 \
+    __VA_ARGS__;                                         \
+  } else if (REDUCE == Reduce::ReduceType::Max) {        \
+    using OP = cu::Max;                                  \
+    __VA_ARGS__;                                         \
+  } else if (REDUCE == Reduce::ReduceType::Min) {        \
+    using OP = cu::Min;                                  \
+    __VA_ARGS__;                                         \
+  } else {                                               \
+    throw std::invalid_argument("Unknown reduce type."); \
   }
-}
 
-void all_reduce(
+void segmented_reduce(
     cu::CommandEncoder& encoder,
     const array& in,
     array& out,
-    Reduce::ReduceType reduce_type);
+    Reduce::ReduceType reduce_type,
+    const std::vector<int>& axes,
+    const ReductionPlan& plan);
 
 void row_reduce(
     cu::CommandEncoder& encoder,
@@ -63,10 +71,4 @@ void col_reduce(
     const std::vector<int>& axes,
     const ReductionPlan& plan);
 
-void init_reduce(
-    cu::CommandEncoder& encoder,
-    const array& in,
-    array& out,
-    Reduce::ReduceType reduce_type);
-
 } // namespace mlx::core

mlx/backend/cuda/reduce/reduce_ops.cuh

@@ -2,92 +2,49 @@
 
 #pragma once
 
-#include "mlx/backend/cuda/device/atomic_ops.cuh"
-#include "mlx/backend/cuda/device/cast_op.cuh"
 #include "mlx/backend/cuda/device/utils.cuh"
-#include "mlx/backend/cuda/reduce/reduce_utils.cuh"
 
 namespace mlx::core::cu {
 
 // Reduce ops.
 struct And {
-  __device__ __forceinline__ bool operator()(bool a, bool b) {
+  __device__ bool operator()(bool a, bool b) {
     return a && b;
   }
-
-  __device__ void atomic_update(bool* x, bool y) {
-    atomic_reduce<bool, And>(x, y);
-  }
 };
 
 struct Or {
-  __device__ __forceinline__ bool operator()(bool a, bool b) {
+  __device__ bool operator()(bool a, bool b) {
     return a || b;
   }
-
-  __device__ void atomic_update(bool* x, bool y) {
-    atomic_reduce<bool, Or>(x, y);
-  }
 };
 
 struct Sum {
   template <typename T>
-  __device__ __forceinline__ T operator()(T a, T b) {
+  __device__ T operator()(T a, T b) {
     return a + b;
   }
-
-  template <typename T>
-  __device__ void atomic_update(T* x, T y) {
-    atomic_reduce<T, Sum>(x, y);
-  }
-
-  __device__ void atomic_update(__nv_bfloat16* x, __nv_bfloat16 y) {
-    atomic_add(x, y);
-  }
-
-  __device__ void atomic_update(int* x, int y) {
-    atomic_add(x, y);
-  }
-
-  __device__ void atomic_update(float* x, float y) {
-    atomic_add(x, y);
-  }
 };
 
 struct Prod {
   template <typename T>
-  __device__ __forceinline__ T operator()(T a, T b) {
+  __device__ T operator()(T a, T b) {
     return a * b;
   }
-
-  template <typename T>
-  __device__ void atomic_update(T* x, T y) {
-    atomic_reduce<T, Prod>(x, y);
-  }
 };
 
 struct Min {
   template <typename T>
-  __device__ __forceinline__ T operator()(T a, T b) {
+  __device__ T operator()(T a, T b) {
     return a < b ? a : b;
   }
-
-  template <typename T>
-  __device__ void atomic_update(T* x, T y) {
-    atomic_reduce<T, Min>(x, y);
-  }
 };
 
 struct Max {
   template <typename T>
-  __device__ __forceinline__ T operator()(T a, T b) {
+  __device__ T operator()(T a, T b) {
     return a > b ? a : b;
   }
-
-  template <typename T>
-  __device__ void atomic_update(T* x, T y) {
-    atomic_reduce<T, Max>(x, y);
-  }
 };
 
 // Traits to get the result type of reduce op.
@@ -154,7 +111,7 @@ struct ReduceInit<Sum, T> {
     if constexpr (cuda::std::is_same_v<T, cuComplex>) {
       return T{0, 0};
     } else {
-      return cast_to<typename ReduceResult<Sum, T>::type>(0);
+      return typename ReduceResult<Sum, T>::type{0};
     }
   }
 };
@@ -163,9 +120,9 @@ template <typename T>
 struct ReduceInit<Prod, T> {
   static constexpr __host__ __device__ auto value() {
     if constexpr (cuda::std::is_same_v<T, cuComplex>) {
-      return T{1, 0};
+      return T{1, 1};
     } else {
-      return cast_to<typename ReduceResult<Prod, T>::type>(1);
+      return typename ReduceResult<Prod, T>::type{1};
     }
   }
 };

mlx/backend/cuda/reduce/reduce_utils.cuh

@@ -1,143 +0,0 @@
-// Copyright © 2025 Apple Inc.
-
-#pragma once
-
-#include <numeric>
-
-#include "mlx/backend/common/utils.h"
-#include "mlx/backend/cuda/device/utils.cuh"
-
-#include <cooperative_groups.h>
-#include <cooperative_groups/reduce.h>
-
-namespace mlx::core {
-
-namespace cu {
-
-namespace cg = cooperative_groups;
-
-template <size_t N>
-struct uint_by_size;
-template <>
-struct uint_by_size<2> {
-  using type = uint16_t;
-};
-template <>
-struct uint_by_size<4> {
-  using type = uint32_t;
-};
-template <>
-struct uint_by_size<8> {
-  using type = unsigned long long int;
-};
-
-template <typename T, typename Op>
-__device__ void atomic_reduce(T* x, T y) {
-  if constexpr (sizeof(T) == 1) {
-    using U = uint16_t;
-    U* x_int = (U*)((char*)x - ((size_t)x % 2));
-    int shift = ((char*)x - (char*)x_int) * 8;
-    int mask = 0xff << shift;
-    U old_val, new_val;
-    do {
-      old_val = *x_int;
-      T result = Op{}(static_cast<T>((old_val >> shift) & 0xff), y);
-      new_val = (old_val & ~mask) | (result << shift);
-    } while (atomicCAS(x_int, old_val, new_val) != old_val);
-  } else {
-    using U = typename uint_by_size<sizeof(T)>::type;
-    U* x_int = (U*)(x);
-    U old_val, new_val;
-    do {
-      old_val = *x_int;
-      T result = Op{}(*((T*)&old_val), y);
-      new_val = *((U*)&result);
-    } while (atomicCAS(x_int, old_val, new_val) != old_val);
-  }
-}
-
-template <typename T, int N, typename Block, typename Warp, typename Op>
-inline __device__ void
-block_reduce(Block block, Warp warp, T (&vals)[N], T* smem, Op op, T init) {
-  // First reduce in the current warp
-  for (int i = 0; i < N; i++) {
-    vals[i] = cg::reduce(warp, vals[i], op);
-  }
-
-  // Reduce across warps
-  if (warp.meta_group_size() > 1) {
-    if (warp.thread_rank() == 0) {
-      for (int i = 0; i < N; i++) {
-        smem[warp.meta_group_rank() * N + i] = vals[i];
-      }
-    }
-    block.sync();
-    if (warp.thread_rank() < warp.meta_group_size()) {
-      for (int i = 0; i < N; i++) {
-        vals[i] = smem[warp.thread_rank() * N + i];
-      }
-    } else {
-      for (int i = 0; i < N; i++) {
-        vals[i] = init;
-      }
-    }
-    for (int i = 0; i < N; i++) {
-      vals[i] = cg::reduce(warp, vals[i], op);
-    }
-  }
-}
-
-} // namespace cu
-
-inline void allocate_same_layout(
-    array& out,
-    const array& in,
-    const std::vector<int>& axes) {
-  if (in.flags().row_contiguous) {
-    out.set_data(allocator::malloc(out.nbytes()));
-    return;
-  }
-
-  if (out.ndim() < in.ndim()) {
-    throw std::runtime_error(
-        "Reduction without keepdims only supported for row-contiguous inputs");
-  }
-
-  // Calculate the transpositions applied to in in order to apply them to out.
-  std::vector<int> axis_order(in.ndim());
-  std::iota(axis_order.begin(), axis_order.end(), 0);
-  std::sort(axis_order.begin(), axis_order.end(), [&](int left, int right) {
-    return in.strides(left) > in.strides(right);
-  });
-
-  // Transpose the shape and calculate the strides
-  Shape out_shape(in.ndim());
-  Strides out_strides(in.ndim(), 1);
-  for (int i = 0; i < in.ndim(); i++) {
-    out_shape[i] = out.shape(axis_order[i]);
-  }
-  for (int i = in.ndim() - 2; i >= 0; i--) {
-    out_strides[i] = out_shape[i + 1] * out_strides[i + 1];
-  }
-
-  // Reverse the axis order to get the final strides
-  Strides final_strides(in.ndim());
-  for (int i = 0; i < in.ndim(); i++) {
-    final_strides[axis_order[i]] = out_strides[i];
-  }
-
-  // Calculate the resulting contiguity and do the memory allocation
-  auto [data_size, rc, cc] = check_contiguity(out.shape(), final_strides);
-  auto fl = in.flags();
-  fl.row_contiguous = rc;
-  fl.col_contiguous = cc;
-  fl.contiguous = true;
-  out.set_data(
-      allocator::malloc(out.nbytes()),
-      data_size,
-      final_strides,
-      fl,
-      allocator::free);
-}
-
-} // namespace mlx::core

mlx/backend/cuda/reduce/row_reduce.cu

@@ -1,8 +1,7 @@
 // Copyright © 2025 Apple Inc.
 
-#include <numeric>
-
 #include "mlx/backend/cuda/device.h"
+#include "mlx/backend/cuda/device/cast_op.cuh"
 #include "mlx/backend/cuda/reduce/reduce.cuh"
 
 #include <cooperative_groups.h>
@@ -56,108 +55,84 @@ struct RowReduceArgs {
       non_row_reductions *= reduce_shape[i];
     }
   }
-
-  // Convert shape and strides as if in was contiguous
-  void sort_access_pattern(const array& in, const std::vector<int>& axes) {
-    auto shape_vec = in.shape();
-    auto strides_vec = in.strides();
-    std::tie(shape_vec, strides_vec) =
-        shapes_without_reduction_axes(shape_vec, strides_vec, axes);
-    std::vector<int> indices(shape_vec.size());
-    std::iota(indices.begin(), indices.end(), 0);
-    std::sort(indices.begin(), indices.end(), [&](int left, int right) {
-      return strides_vec[left] > strides_vec[right];
-    });
-    decltype(shape_vec) sorted_shape;
-    decltype(strides_vec) sorted_strides;
-    for (auto idx : indices) {
-      sorted_shape.push_back(shape_vec[idx]);
-      sorted_strides.push_back(strides_vec[idx]);
-    }
-    std::tie(shape_vec, strides_vec) =
-        collapse_contiguous_dims(sorted_shape, sorted_strides);
-    shape = const_param(shape_vec);
-    strides = const_param(strides_vec);
-    ndim = shape_vec.size();
-  }
 };
 
-template <typename T, typename U, typename ReduceOp, int N = 4, int M = 1>
-__global__ void row_reduce_simple(T* in, U* out, size_t n_rows, int size) {
+template <typename T, typename U, typename Op, int NDIM, int N_READS = 4>
+__global__ void row_reduce_small(
+    const T* in,
+    U* out,
+    size_t out_size,
+    const __grid_constant__ RowReduceArgs args) {
+  size_t out_idx = cg::this_grid().thread_rank();
+  if (out_idx >= out_size) {
+    return;
+  }
+
+  Op op;
+
+  U total_val = ReduceInit<Op, T>::value();
+  LoopedElemToLoc<NDIM, (NDIM > 2)> loop(args.reduce_ndim);
+
+  in += elem_to_loc(out_idx, args.shape.data(), args.strides.data(), args.ndim);
+
+  for (size_t n = 0; n < args.non_row_reductions; n++) {
+    for (int r = 0; r < cuda::ceil_div(args.row_size, N_READS); r++) {
+      U vals[N_READS];
+      cub::LoadDirectBlocked(
+          r,
+          make_cast_iterator<U>(in + loop.location()),
+          vals,
+          args.row_size,
+          ReduceInit<Op, T>::value());
+      total_val = op(total_val, cub::ThreadReduce(vals, op));
+    }
+    loop.next(args.reduce_shape.data(), args.reduce_strides.data());
+  }
+
+  out[out_idx] = total_val;
+}
+
+template <typename T, typename U, typename Op, int NDIM, int N_READS = 4>
+__global__ void row_reduce_small_warp(
+    const T* in,
+    U* out,
+    size_t out_size,
+    const __grid_constant__ RowReduceArgs args) {
   auto grid = cg::this_grid();
   auto block = cg::this_thread_block();
   auto warp = cg::tiled_partition<WARP_SIZE>(block);
 
-  const U init = cu::ReduceInit<ReduceOp, T>::value();
-  ReduceOp op;
-
-  T vals[M][N];
-  U accs[M];
-  for (int i = 0; i < M; i++) {
-    accs[i] = init;
+  size_t out_idx = grid.thread_rank() / WARP_SIZE;
+  if (out_idx >= out_size) {
+    return;
   }
 
-  const size_t start_row =
-      min(n_rows - M, static_cast<size_t>(grid.block_rank() * M));
-  const size_t full_blocks = size / (block.size() * N);
-  const size_t final_offset = full_blocks * (block.size() * N);
-  in += start_row * size;
-  out += start_row;
+  Op op;
 
-  if (size % N == 0) {
-    for (size_t r = 0; r < full_blocks; r++) {
-      for (int k = 0; k < M; k++) {
-        cub::LoadDirectBlockedVectorized<T, N>(
-            block.thread_rank(),
-            in + k * size + r * (block.size() * N),
-            vals[k]);
-        for (int j = 0; j < N; j++) {
-          accs[k] = op(accs[k], cast_to<U>(vals[k][j]));
-        }
-      }
-    }
-  } else {
-    for (size_t r = 0; r < full_blocks; r++) {
-      for (int k = 0; k < M; k++) {
-        cub::LoadDirectBlocked(
-            block.thread_rank(),
-            in + k * size + r * (block.size() * N),
-            vals[k]);
-        for (int j = 0; j < N; j++) {
-          accs[k] = op(accs[k], cast_to<U>(vals[k][j]));
-        }
-      }
-    }
-  }
+  U total_val = ReduceInit<Op, T>::value();
+  LoopedElemToLoc<NDIM, (NDIM > 2)> loop(args.reduce_ndim);
 
-  if (final_offset < size) {
-    for (int k = 0; k < M; k++) {
+  in += elem_to_loc(out_idx, args.shape.data(), args.strides.data(), args.ndim);
+
+  for (size_t n = warp.thread_rank(); n < args.non_row_reductions;
+       n += WARP_SIZE) {
+    for (int r = 0; r < cuda::ceil_div(args.row_size, N_READS); r++) {
+      U vals[N_READS];
       cub::LoadDirectBlocked(
-          block.thread_rank(),
-          in + k * size + final_offset,
-          vals[k],
-          size,
-          cast_to<T>(init));
-      for (int j = 0; j < N; j++) {
-        accs[k] = op(accs[k], cast_to<U>(vals[k][j]));
-      }
+          r,
+          make_cast_iterator<U>(in + loop.location()),
+          vals,
+          args.row_size,
+          ReduceInit<Op, T>::value());
+      total_val = op(total_val, cub::ThreadReduce(vals, op));
     }
+    loop.next(WARP_SIZE, args.reduce_shape.data(), args.reduce_strides.data());
   }
 
-  __shared__ U shared_accumulators[32 * M];
-  block_reduce(block, warp, accs, shared_accumulators, op, init);
+  total_val = cg::reduce(warp, total_val, op);
 
-  if (block.thread_rank() == 0) {
-    if (grid.block_rank() * M + M <= n_rows) {
-      for (int i = 0; i < M; i++) {
-        out[i] = accs[i];
-      }
-    } else {
-      short offset = grid.block_rank() * M + M - n_rows;
-      for (int i = offset; i < M; i++) {
-        out[i] = accs[i];
-      }
-    }
+  if (warp.thread_rank() == 0) {
+    out[out_idx] = total_val;
   }
 }
 
@@ -166,167 +141,55 @@ template <
     typename U,
     typename Op,
     int NDIM,
-    int BLOCK_DIM,
+    int BLOCK_DIM_X,
     int N_READS = 4>
 __global__ void row_reduce_looped(
-    T* in,
+    const T* in,
     U* out,
     size_t out_size,
     const __grid_constant__ RowReduceArgs args) {
   auto grid = cg::this_grid();
   auto block = cg::this_thread_block();
-  auto warp = cg::tiled_partition<WARP_SIZE>(block);
 
-  size_t out_idx = grid.block_rank();
+  size_t out_idx = grid.thread_rank() / BLOCK_DIM_X;
+  if (out_idx >= out_size) {
+    return;
+  }
 
   Op op;
 
-  U total[1];
-  U init = ReduceInit<Op, T>::value();
-  total[0] = init;
+  U total_val = ReduceInit<Op, T>::value();
   LoopedElemToLoc<NDIM, (NDIM > 2)> loop(args.reduce_ndim);
-  size_t full_blocks = args.row_size / (BLOCK_DIM * N_READS);
-  size_t final_offset = full_blocks * BLOCK_DIM * N_READS;
 
   in += elem_to_loc(out_idx, args.shape.data(), args.strides.data(), args.ndim);
 
   for (size_t n = 0; n < args.non_row_reductions; n++) {
-    for (size_t r = 0; r < full_blocks; r++) {
-      T vals[N_READS];
-      cub::LoadDirectBlockedVectorized<T, N_READS>(
-          block.thread_rank(),
-          in + loop.location() + r * BLOCK_DIM * N_READS,
-          vals);
-      for (int i = 0; i < N_READS; i++) {
-        total[0] = op(total[0], cast_to<U>(vals[i]));
-      }
-    }
-    if (final_offset < args.row_size) {
-      T vals[N_READS];
+    for (size_t r = 0; r < cuda::ceil_div(args.row_size, BLOCK_DIM_X * N_READS);
+         r++) {
+      U vals[N_READS];
       cub::LoadDirectBlocked(
-          block.thread_rank(),
-          in + loop.location() + final_offset,
+          r * BLOCK_DIM_X + block.thread_index().x,
+          make_cast_iterator<U>(in + loop.location()),
           vals,
-          args.row_size - final_offset,
-          cast_to<T>(init));
-      for (int i = 0; i < N_READS; i++) {
-        total[0] = op(total[0], cast_to<U>(vals[i]));
-      }
+          args.row_size,
+          ReduceInit<Op, T>::value());
+      total_val = op(total_val, cub::ThreadReduce(vals, op));
     }
-    // TODO: Maybe block.sync() here?
     loop.next(args.reduce_shape.data(), args.reduce_strides.data());
   }
 
-  __shared__ U shared_accumulators[32];
-  block_reduce(block, warp, total, shared_accumulators, op, init);
+  typedef cub::BlockReduce<U, BLOCK_DIM_X> BlockReduceT;
+  __shared__ typename BlockReduceT::TempStorage temp;
+
+  total_val = BlockReduceT(temp).Reduce(total_val, op);
 
   if (block.thread_rank() == 0) {
-    out[out_idx] = total[0];
+    out[out_idx] = total_val;
   }
 }
 
 } // namespace cu
 
-void row_reduce_simple(
-    cu::CommandEncoder& encoder,
-    const array& in,
-    array& out,
-    Reduce::ReduceType reduce_type,
-    const std::vector<int>& axes,
-    const ReductionPlan& plan) {
-  constexpr int N_READS = 8;
-
-  // Allocate data for the output using in's layout to avoid elem_to_loc in the
-  // kernel.
-  allocate_same_layout(out, in, axes);
-
-  // TODO: If out.size() < 1024 which will be a common case then write this in
-  //       2 passes. Something like 32 * out.size() and then do a warp reduce.
-  encoder.set_input_array(in);
-  encoder.set_output_array(out);
-  dispatch_all_types(in.dtype(), [&](auto type_tag) {
-    dispatch_reduce_ops(reduce_type, [&](auto reduce_type_tag) {
-      using OP = MLX_GET_TYPE(reduce_type_tag);
-      using T = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-      using U = typename cu::ReduceResult<OP, T>::type;
-
-      // Cub doesn't like const pointers for vectorized loads. (sigh)
-      T* indata = const_cast<T*>(in.data<T>());
-
-      // Calculate the grid and block dims
-      size_t reductions = (plan.shape.back() + N_READS - 1) / N_READS;
-      dim3 grid = get_2d_grid_dims(out.shape(), out.strides());
-      int threads = std::min(1024UL, reductions);
-      threads = ((threads + WARP_SIZE - 1) / WARP_SIZE) * WARP_SIZE;
-      dim3 block(threads, 1, 1);
-
-      // Pick the kernel
-      auto kernel = cu::row_reduce_simple<T, U, OP, N_READS>;
-      if (grid.x >= 1024) {
-        grid.x = (grid.x + 1) / 2;
-        kernel = cu::row_reduce_simple<T, U, OP, N_READS, 2>;
-      }
-
-      int size = plan.shape.back();
-      encoder.add_kernel_node(
-          kernel, grid, block, indata, out.data<U>(), out.size(), size);
-    });
-  });
-}
-
-void row_reduce_looped(
-    cu::CommandEncoder& encoder,
-    const array& in,
-    array& out,
-    Reduce::ReduceType reduce_type,
-    const std::vector<int>& axes,
-    const ReductionPlan& plan,
-    cu::RowReduceArgs args) {
-  constexpr int N_READS = 8;
-
-  // Allocate data for the output using in's layout to access them as
-  // contiguously as possible.
-  allocate_same_layout(out, in, axes);
-
-  encoder.set_input_array(in);
-  encoder.set_output_array(out);
-  dispatch_all_types(in.dtype(), [&](auto type_tag) {
-    dispatch_reduce_ops(reduce_type, [&](auto reduce_type_tag) {
-      using OP = MLX_GET_TYPE(reduce_type_tag);
-      using T = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-      using U = typename cu::ReduceResult<OP, T>::type;
-      // Cub doesn't like const pointers for vectorized loads. (sigh)
-      T* indata = const_cast<T*>(in.data<T>());
-
-      // Calculate the grid and block dims
-      args.sort_access_pattern(in, axes);
-      dim3 grid = get_2d_grid_dims(out.shape(), out.strides());
-      size_t reductions = (args.row_size + N_READS - 1) / N_READS;
-      int threads = std::min(1024UL, reductions);
-      threads = ((threads + WARP_SIZE - 1) / WARP_SIZE) * WARP_SIZE;
-      dim3 block(threads, 1, 1);
-
-      // Pick the kernel
-      auto kernel = cu::row_reduce_looped<T, U, OP, 1, 32, N_READS>;
-      dispatch_reduce_ndim(args.reduce_ndim, [&](auto reduce_ndim) {
-        dispatch_block_dim(threads, [&](auto threads_constant) {
-          kernel = cu::row_reduce_looped<
-              T,
-              U,
-              OP,
-              reduce_ndim.value,
-              threads_constant.value,
-              N_READS>;
-          block.x = threads_constant.value;
-        });
-      });
-
-      encoder.add_kernel_node(
-          kernel, grid, block, indata, out.data<U>(), out.size(), args);
-    });
-  });
-}
-
 void row_reduce(
     cu::CommandEncoder& encoder,
     const array& in,
@@ -334,35 +197,54 @@ void row_reduce(
     Reduce::ReduceType reduce_type,
     const std::vector<int>& axes,
     const ReductionPlan& plan) {
-  // Current row reduction options
-  //
-  // - row_reduce_simple
-  //
-  //   That means that we are simply reducing across the fastest moving axis.
-  //   We are reducing 1 or 2 rows per threadblock depending on the size of
-  //   output.
-  //
-  // - row_reduce_looped
-  //
-  //   It is a general row reduction. We are computing 1 output per
-  //   threadblock. We read the fastest moving axis vectorized and loop over
-  //   the rest of the axes.
-  //
-  // Notes: We opt to read as much in order as possible and leave
-  //        transpositions as they are (contrary to our Metal backend).
-
-  // Simple row reduce means that we have 1 axis that we are reducing over and
-  // it has stride 1.
-  if (plan.shape.size() == 1) {
-    row_reduce_simple(encoder, in, out, reduce_type, axes, plan);
-    return;
-  }
-
-  // Make the args struct to help route to the best kernel
   cu::RowReduceArgs args(in, plan, axes);
 
-  // Fallback row reduce
-  row_reduce_looped(encoder, in, out, reduce_type, axes, plan, std::move(args));
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_ALL_TYPES(in.dtype(), CTYPE, {
+      using InType = cuda_type_t<CTYPE>;
+      MLX_SWITCH_REDUCE_OPS(reduce_type, OP, {
+        using OutType = cu::ReduceResult<OP, InType>::type;
+        MLX_SWITCH_REDUCE_NDIM(args.reduce_ndim, NDIM, {
+          constexpr size_t N_READS = 4;
+          dim3 out_dims = get_2d_grid_dims(out.shape(), out.strides());
+          dim3 block_dims, num_blocks;
+          auto kernel =
+              cu::row_reduce_small<InType, OutType, OP, NDIM, N_READS>;
+          if (args.row_size <= 64) {
+            if ((args.non_row_reductions < 32 && args.row_size <= 8) ||
+                (args.non_row_reductions <= 8)) {
+              block_dims.x = std::min(out_dims.x, 1024u);
+              num_blocks.x = cuda::ceil_div(out_dims.x, block_dims.x);
+              num_blocks.y = out_dims.y;
+            } else {
+              block_dims.x = WARP_SIZE;
+              num_blocks.y = out_dims.x;
+              num_blocks.z = out_dims.y;
+              kernel =
+                  cu::row_reduce_small_warp<InType, OutType, OP, NDIM, N_READS>;
+            }
+          } else {
+            size_t num_threads = cuda::ceil_div(args.row_size, N_READS);
+            num_threads = cuda::ceil_div(num_threads, WARP_SIZE) * WARP_SIZE;
+            MLX_SWITCH_BLOCK_DIM(num_threads, BLOCK_DIM_X, {
+              num_blocks.y = out_dims.x;
+              num_blocks.z = out_dims.y;
+              block_dims.x = BLOCK_DIM_X;
+              kernel = cu::row_reduce_looped<
+                  InType,
+                  OutType,
+                  OP,
+                  NDIM,
+                  BLOCK_DIM_X,
+                  N_READS>;
+            });
+          }
+          kernel<<<num_blocks, block_dims, 0, stream>>>(
+              in.data<InType>(), out.data<OutType>(), out.size(), args);
+        });
+      });
+    });
+  });
 }
 
 } // namespace mlx::core

mlx/backend/cuda/reduce/segmented_reduce.cu

@@ -0,0 +1,84 @@
+// Copyright © 2025 Apple Inc.
+
+#include "mlx/backend/cuda/device.h"
+#include "mlx/backend/cuda/device/cast_op.cuh"
+#include "mlx/backend/cuda/reduce/reduce.cuh"
+
+#include <thrust/device_ptr.h>
+#include <cub/device/device_reduce.cuh>
+#include <cub/device/device_segmented_reduce.cuh>
+
+namespace mlx::core {
+
+template <typename... Args>
+void cub_all_reduce(cu::CommandEncoder& encoder, Args&&... args) {
+  // Allocate temporary storage.
+  size_t size;
+  CHECK_CUDA_ERROR(cub::DeviceReduce::Reduce(nullptr, size, args...));
+  array temp(allocator::malloc(size), {static_cast<int>(size)}, uint8);
+  encoder.add_temporary(temp);
+  // Run op.
+  CHECK_CUDA_ERROR(cub::DeviceReduce::Reduce(temp.data<void>(), size, args...));
+}
+
+template <typename... Args>
+void cub_segmented_reduce(cu::CommandEncoder& encoder, Args&&... args) {
+  // Allocate temporary storage.
+  size_t size;
+  CHECK_CUDA_ERROR(cub::DeviceSegmentedReduce::Reduce(nullptr, size, args...));
+  array temp(allocator::malloc(size), {static_cast<int>(size)}, uint8);
+  encoder.add_temporary(temp);
+  // Run op.
+  CHECK_CUDA_ERROR(
+      cub::DeviceSegmentedReduce::Reduce(temp.data<void>(), size, args...));
+}
+
+struct MultiplyOp {
+  int factor;
+  __device__ int operator()(int i) {
+    return i * factor;
+  }
+};
+
+void segmented_reduce(
+    cu::CommandEncoder& encoder,
+    const array& in,
+    array& out,
+    Reduce::ReduceType reduce_type,
+    const std::vector<int>& axes,
+    const ReductionPlan& plan) {
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_ALL_TYPES(in.dtype(), CTYPE, {
+      MLX_SWITCH_REDUCE_OPS(reduce_type, OP, {
+        using InType = cuda_type_t<CTYPE>;
+        using OutType = cu::ReduceResult<OP, InType>::type;
+        auto in_iter = cu::make_cast_iterator<OutType>(
+            thrust::device_pointer_cast(in.data<InType>()));
+        auto out_ptr = thrust::device_pointer_cast(out.data<OutType>());
+        auto init = cu::ReduceInit<OP, InType>::value();
+
+        if (plan.type == ContiguousAllReduce) {
+          cub_all_reduce(
+              encoder, in_iter, out_ptr, in.data_size(), OP(), init, stream);
+        } else if (plan.type == ContiguousReduce) {
+          auto offsets = thrust::make_transform_iterator(
+              thrust::make_counting_iterator(0), MultiplyOp{plan.shape.back()});
+          cub_segmented_reduce(
+              encoder,
+              in_iter,
+              out_ptr,
+              out.size(),
+              offsets,
+              offsets + 1,
+              OP(),
+              init,
+              stream);
+        } else {
+          throw std::runtime_error("Unsupported plan in segmented_reduce.");
+        }
+      });
+    });
+  });
+}
+
+} // namespace mlx::core

mlx/backend/cuda/rms_norm.cu

@@ -74,7 +74,7 @@ __global__ void rms_norm(
   for (int r = 0; r < cuda::ceil_div(axis_size, BLOCK_DIM * N_READS); ++r) {
     auto index = r * BLOCK_DIM + block.thread_rank();
     T xn[N_READS];
-    cub::LoadDirectBlocked(index, x, xn, axis_size, cast_to<T>(0));
+    cub::LoadDirectBlocked(index, x, xn, axis_size, 0);
     for (int i = 0; i < N_READS; ++i) {
       float t = static_cast<float>(xn[i]);
       normalizer += t * t;
@@ -130,7 +130,7 @@ __global__ void rms_norm_vjp(
     T wn[N_READS] = {};
     T gn[N_READS] = {};
     auto index = r * BLOCK_DIM + block.thread_rank();
-    cub::LoadDirectBlocked(index, x, xn, axis_size, cast_to<T>(0));
+    cub::LoadDirectBlocked(index, x, xn, axis_size, 0);
     cub::LoadDirectBlocked(index, g, gn, axis_size);
     cub::LoadDirectBlocked(index, strided_iterator(w, w_stride), wn, axis_size);
     for (int i = 0; i < N_READS; i++) {
@@ -224,21 +224,20 @@ void RMSNorm::eval_gpu(
   encoder.set_input_array(x);
   encoder.set_input_array(w);
   encoder.set_output_array(out);
-  dispatch_float_types(out.dtype(), "rms_norm", [&](auto type_tag) {
-    constexpr uint32_t N_READS = 4;
-    dispatch_block_dim(cuda::ceil_div(axis_size, N_READS), [&](auto block_dim) {
-      using DataType = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-      auto kernel = cu::rms_norm<DataType, block_dim(), N_READS>;
-      encoder.add_kernel_node(
-          kernel,
-          n_rows,
-          block_dim(),
-          x.data<DataType>(),
-          w.data<DataType>(),
-          out.data<DataType>(),
-          eps_,
-          axis_size,
-          w_stride);
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_FLOAT_TYPES_CHECKED(out.dtype(), "rms_norm", CTYPE, {
+      using DataType = cuda_type_t<CTYPE>;
+      constexpr uint32_t N_READS = 4;
+      MLX_SWITCH_BLOCK_DIM(cuda::ceil_div(axis_size, N_READS), BLOCK_DIM, {
+        auto kernel = cu::rms_norm<DataType, BLOCK_DIM, N_READS>;
+        kernel<<<n_rows, BLOCK_DIM, 0, stream>>>(
+            x.data<DataType>(),
+            w.data<DataType>(),
+            out.data<DataType>(),
+            eps_,
+            axis_size,
+            w_stride);
+      });
     });
   });
 }
@@ -253,24 +252,20 @@ void RMSNormVJP::eval_gpu(
   // Ensure row contiguity. We could relax this step by checking that the array
   // is contiguous (no broadcasts or holes) and that the input strides are the
   // same as the cotangent strides but for now this is simpler.
-  auto check_input = [&s](const array& x, bool& copied) {
+  auto check_input = [&s](const array& x) -> std::pair<array, bool> {
     if (x.flags().row_contiguous) {
-      copied = false;
-      return x;
+      return {x, false};
     }
-    copied = true;
     array x_copy(x.shape(), x.dtype(), nullptr, {});
     copy_gpu(x, x_copy, CopyType::General, s);
-    return x_copy;
+    return {x_copy, true};
   };
   bool donate_x = inputs[0].is_donatable();
   bool donate_g = inputs[2].is_donatable();
-  bool copied;
-  auto x = check_input(inputs[0], copied);
+  auto [x, copied] = check_input(inputs[0]);
   donate_x |= copied;
   const array& w = inputs[1];
-  bool g_copied;
-  auto g = check_input(inputs[2], g_copied);
+  auto [g, g_copied] = check_input(inputs[2]);
   donate_g |= g_copied;
   array& gx = outputs[0];
   array& gw = outputs[1];
@@ -308,37 +303,31 @@ void RMSNormVJP::eval_gpu(
       encoder.add_temporary(gw_temp);
     }
   }
+  gw.set_data(allocator::malloc(gw.nbytes()));
 
   encoder.set_input_array(x);
   encoder.set_input_array(w);
   encoder.set_input_array(g);
   encoder.set_output_array(gx);
   encoder.set_output_array(gw_temp);
-  dispatch_float_types(gx.dtype(), "rms_norm_vjp", [&](auto type_tag) {
-    dispatch_bool(has_w, [&](auto has_w_constant) {
+  encoder.launch_kernel([&, x = x, g = g](cudaStream_t stream) {
+    MLX_SWITCH_FLOAT_TYPES_CHECKED(gx.dtype(), "rms_norm_vjp", CTYPE, {
+      using DataType = cuda_type_t<CTYPE>;
       constexpr int N_READS = 4;
-      dispatch_block_dim(
-          cuda::ceil_div(axis_size, N_READS), [&](auto block_dim) {
-            using DataType = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-            constexpr int N_READS = 4;
-            auto kernel = cu::rms_norm_vjp<
-                DataType,
-                has_w_constant.value,
-                block_dim(),
-                N_READS>;
-            encoder.add_kernel_node(
-                kernel,
-                n_rows,
-                block_dim(),
-                x.data<DataType>(),
-                w.data<DataType>(),
-                g.data<DataType>(),
-                gx.data<DataType>(),
-                gw_temp.data<DataType>(),
-                eps_,
-                axis_size,
-                w_stride);
-          });
+      MLX_SWITCH_BOOL(has_w, HAS_W, {
+        MLX_SWITCH_BLOCK_DIM(cuda::ceil_div(axis_size, N_READS), BLOCK_DIM, {
+          auto kernel = cu::rms_norm_vjp<DataType, HAS_W, BLOCK_DIM, N_READS>;
+          kernel<<<n_rows, BLOCK_DIM, 0, stream>>>(
+              x.data<DataType>(),
+              w.data<DataType>(),
+              g.data<DataType>(),
+              gx.data<DataType>(),
+              gw_temp.data<DataType>(),
+              eps_,
+              axis_size,
+              w_stride);
+        });
+      });
     });
   });
 

mlx/backend/cuda/rope.cu

@@ -308,89 +308,73 @@ void RoPE::eval_gpu(
   auto& encoder = cu::get_command_encoder(s);
   encoder.set_input_array(donated ? out : in);
   encoder.set_input_array(offset);
-  if (with_freqs) {
-    encoder.set_input_array(inputs[2]);
-  }
   encoder.set_output_array(out);
-  dispatch_float_types(out.dtype(), "rope", [&](auto type_tag) {
-    dispatch_bool(traditional_, [&](auto traditional) {
-      dispatch_bool(forward_, [&](auto forward) {
-        using DataType = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-        if (single && !with_freqs) {
-          auto kernel =
-              cu::rope_single<DataType, traditional.value, forward.value>;
-          uint2 dims = make_uint2(dims_ / 2, in.size() / mat_size);
-          auto [grid, block] = get_grid_and_block(dims.x, dims.y, 1);
-          encoder.add_kernel_node(
-              kernel,
-              grid,
-              block,
-              (donated ? out : in).data<DataType>(),
-              out.data<DataType>(),
-              offset.data<int32_t>(),
-              scale_,
-              std::log2(base_),
-              mat_size,
-              dims);
-        } else if (single) {
-          auto kernel =
-              cu::rope_single_freqs<DataType, traditional.value, forward.value>;
-          uint2 dims = make_uint2(dims_ / 2, in.size() / mat_size);
-          auto [grid, block] = get_grid_and_block(dims.x, dims.y, 1);
-          encoder.add_kernel_node(
-              kernel,
-              grid,
-              block,
-              (donated ? out : in).data<DataType>(),
-              out.data<DataType>(),
-              offset.data<int32_t>(),
-              inputs[2].data<float>(),
-              scale_,
-              mat_size,
-              dims,
-              inputs[2].strides(0));
-        } else if (with_freqs) {
-          auto kernel =
-              cu::rope_freqs<DataType, traditional.value, forward.value>;
-          uint3 dims =
-              make_uint3(dims_ / 2, in.shape(-2), in.size() / mat_size);
-          dims.z = (dims.z + 3) / 4;
-          auto [grid, block] = get_grid_and_block(dims.x, dims.y, dims.z);
-          encoder.add_kernel_node(
-              kernel,
-              grid,
-              block,
-              (donated ? out : in).data<DataType>(),
-              out.data<DataType>(),
-              offset.data<int32_t>(),
-              inputs[2].data<float>(),
-              scale_,
-              std::log2(base_),
-              strides,
-              out_strides,
-              in.size() / mat_size,
-              dims,
-              inputs[2].strides(0));
-        } else {
-          auto kernel = cu::rope<DataType, traditional.value, forward.value>;
-          uint3 dims =
-              make_uint3(dims_ / 2, in.shape(-2), in.size() / mat_size);
-          dims.z = (dims.z + 3) / 4;
-          auto [grid, block] = get_grid_and_block(dims.x, dims.y, dims.z);
-          encoder.add_kernel_node(
-              kernel,
-              grid,
-              block,
-              (donated ? out : in).data<DataType>(),
-              out.data<DataType>(),
-              offset.data<int32_t>(),
-              scale_,
-              std::log2(base_),
-              strides,
-              out_strides,
-              in.size() / mat_size,
-              dims);
-        }
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_FLOAT_TYPES_CHECKED(in.dtype(), "rope", CTYPE, {
+      using DataType = cuda_type_t<CTYPE>;
+      MLX_SWITCH_BOOL(traditional_, TRADITIONAL, {
+        MLX_SWITCH_BOOL(forward_, FORWARD, {
+          if (single && !with_freqs) {
+            auto kernel = cu::rope_single<DataType, TRADITIONAL, FORWARD>;
+            uint2 dims = make_uint2(dims_ / 2, in.size() / mat_size);
+            auto [grid, block] = get_grid_and_block(dims.x, dims.y, 1);
+            kernel<<<grid, block, 0, stream>>>(
+                (donated ? out : in).data<DataType>(),
+                out.data<DataType>(),
+                offset.data<int32_t>(),
+                scale_,
+                std::log2(base_),
+                mat_size,
+                dims);
+          } else if (single) {
+            auto kernel = cu::rope_single_freqs<DataType, TRADITIONAL, FORWARD>;
+            uint2 dims = make_uint2(dims_ / 2, in.size() / mat_size);
+            auto [grid, block] = get_grid_and_block(dims.x, dims.y, 1);
+            kernel<<<grid, block, 0, stream>>>(
+                (donated ? out : in).data<DataType>(),
+                out.data<DataType>(),
+                offset.data<int32_t>(),
+                inputs[2].data<float>(),
+                scale_,
+                mat_size,
+                dims,
+                inputs[2].strides(0));
+          } else if (with_freqs) {
+            auto kernel = cu::rope_freqs<DataType, TRADITIONAL, FORWARD>;
+            uint3 dims =
+                make_uint3(dims_ / 2, in.shape(-2), in.size() / mat_size);
+            dims.z = (dims.z + 3) / 4;
+            auto [grid, block] = get_grid_and_block(dims.x, dims.y, dims.z);
+            kernel<<<grid, block, 0, stream>>>(
+                (donated ? out : in).data<DataType>(),
+                out.data<DataType>(),
+                offset.data<int32_t>(),
+                inputs[2].data<float>(),
+                scale_,
+                std::log2(base_),
+                strides,
+                out_strides,
+                in.size() / mat_size,
+                dims,
+                inputs[2].strides(0));
+          } else {
+            auto kernel = cu::rope<DataType, TRADITIONAL, FORWARD>;
+            uint3 dims =
+                make_uint3(dims_ / 2, in.shape(-2), in.size() / mat_size);
+            dims.z = (dims.z + 3) / 4;
+            auto [grid, block] = get_grid_and_block(dims.x, dims.y, dims.z);
+            kernel<<<grid, block, 0, stream>>>(
+                (donated ? out : in).data<DataType>(),
+                out.data<DataType>(),
+                offset.data<int32_t>(),
+                scale_,
+                std::log2(base_),
+                strides,
+                out_strides,
+                in.size() / mat_size,
+                dims);
+          }
+        });
       });
     });
   });

mlx/backend/cuda/scan.cu

@@ -1,467 +0,0 @@
-// Copyright © 2025 Apple Inc.
-
-#include "mlx/backend/cuda/device.h"
-#include "mlx/backend/cuda/device/binary_ops.cuh"
-#include "mlx/backend/cuda/kernel_utils.cuh"
-#include "mlx/backend/cuda/reduce/reduce_ops.cuh"
-#include "mlx/backend/gpu/copy.h"
-#include "mlx/dtype_utils.h"
-#include "mlx/primitives.h"
-
-#include <cooperative_groups.h>
-#include <cooperative_groups/scan.h>
-#include <nvtx3/nvtx3.hpp>
-
-#include <cassert>
-
-namespace mlx::core {
-
-namespace cu {
-
-namespace cg = cooperative_groups;
-
-template <typename Op, typename T>
-struct ScanResult {
-  using type = T;
-};
-
-template <>
-struct ScanResult<Sum, bool> {
-  using type = int32_t;
-};
-
-template <typename T>
-struct ReduceInit<LogAddExp, T> {
-  static constexpr __host__ __device__ T value() {
-    return Limits<T>::min();
-  }
-};
-
-template <bool reverse, typename T, typename U, int N_READS>
-inline __device__ void
-load_values(int index, const T* in, U (&values)[N_READS], int size, U init) {
-  int remaining = size - index * N_READS;
-  if constexpr (reverse) {
-    in += remaining - N_READS;
-    if (remaining < N_READS) {
-      for (int i = 0; i < N_READS; ++i) {
-        values[N_READS - i - 1] =
-            (N_READS - i - 1 < remaining) ? cast_to<U>(in[i]) : init;
-      }
-    } else {
-      for (int i = 0; i < N_READS; ++i) {
-        values[N_READS - i - 1] = cast_to<U>(in[i]);
-      }
-    }
-  } else {
-    in += index * N_READS;
-    if (remaining < N_READS) {
-      for (int i = 0; i < N_READS; ++i) {
-        values[i] = (i < remaining) ? cast_to<U>(in[i]) : init;
-      }
-    } else {
-      for (int i = 0; i < N_READS; ++i) {
-        values[i] = cast_to<U>(in[i]);
-      }
-    }
-  }
-}
-
-template <bool reverse, int offset, typename T, int N_READS>
-inline __device__ void
-store_values(int index, T* out, T (&values)[N_READS], int size) {
-  int start = index * N_READS + offset;
-  int remaining = size - start;
-  if constexpr (reverse) {
-    out += remaining - N_READS;
-    if (remaining < N_READS) {
-      for (int i = 0; i < N_READS; ++i) {
-        if (N_READS - i - 1 < remaining) {
-          out[i] = values[N_READS - i - 1];
-        }
-      }
-    } else {
-      for (int i = 0; i < N_READS; ++i) {
-        out[i] = values[N_READS - i - 1];
-      }
-    }
-  } else {
-    out += start;
-    if (remaining < N_READS) {
-      for (int i = 0; i < N_READS; ++i) {
-        if (i < remaining) {
-          out[i] = values[i];
-        }
-      }
-    } else {
-      for (int i = 0; i < N_READS; ++i) {
-        out[i] = values[i];
-      }
-    }
-  }
-}
-
-template <
-    typename T,
-    typename U,
-    typename Op,
-    int N_READS,
-    bool inclusive,
-    bool reverse>
-__global__ void contiguous_scan(const T* in, U* out, int32_t axis_size) {
-  auto grid = cg::this_grid();
-  auto block = cg::this_thread_block();
-  auto warp = cg::tiled_partition<WARP_SIZE>(block);
-
-  in += grid.block_rank() * axis_size;
-  out += grid.block_rank() * axis_size;
-
-  __shared__ U warp_sums[WARP_SIZE];
-
-  Op op;
-  U init = ReduceInit<Op, T>::value();
-  U prefix = init;
-
-  // Scan per block.
-  for (int r = 0; r < cuda::ceil_div(axis_size, block.size() * N_READS); ++r) {
-    int32_t index = r * block.size() + block.thread_rank();
-    U values[N_READS];
-    load_values<reverse>(index, in, values, axis_size, init);
-
-    // Compute an inclusive scan per thread.
-    for (int i = 1; i < N_READS; ++i) {
-      values[i] = op(values[i], values[i - 1]);
-    }
-
-    // Compute exclusive scan of thread sums.
-    U prev_thread_sum = cg::exclusive_scan(warp, values[N_READS - 1], op);
-    if (warp.thread_rank() == 0) {
-      prev_thread_sum = init;
-    }
-
-    // Write wrap's sum to shared memory.
-    if (warp.thread_rank() == WARP_SIZE - 1) {
-      warp_sums[warp.meta_group_rank()] =
-          op(prev_thread_sum, values[N_READS - 1]);
-    }
-    block.sync();
-
-    // Compute exclusive scan of warp sums.
-    if (warp.meta_group_rank() == 0) {
-      U prev_warp_sum =
-          cg::exclusive_scan(warp, warp_sums[warp.thread_rank()], op);
-      if (warp.thread_rank() == 0) {
-        prev_warp_sum = init;
-      }
-      warp_sums[warp.thread_rank()] = prev_warp_sum;
-    }
-    block.sync();
-
-    // Compute the output.
-    for (int i = 0; i < N_READS; ++i) {
-      values[i] = op(values[i], prefix);
-      values[i] = op(values[i], warp_sums[warp.meta_group_rank()]);
-      values[i] = op(values[i], prev_thread_sum);
-    }
-
-    // Write the values.
-    if (inclusive) {
-      store_values<reverse, 0>(index, out, values, axis_size);
-    } else {
-      store_values<reverse, 1>(index, out, values, axis_size);
-      if (reverse) {
-        if (block.thread_rank() == 0 && index == 0) {
-          out[axis_size - 1] = init;
-        }
-      } else {
-        if (block.thread_rank() == 0 && index == 0) {
-          out[0] = init;
-        }
-      }
-    }
-    block.sync();
-
-    // Share the prefix.
-    if ((warp.meta_group_rank() == warp.meta_group_size() - 1) &&
-        (warp.thread_rank() == WARP_SIZE - 1)) {
-      warp_sums[0] = values[N_READS - 1];
-    }
-    block.sync();
-    prefix = warp_sums[0];
-  }
-}
-
-template <
-    typename T,
-    typename U,
-    typename Op,
-    int N_READS,
-    int BM,
-    int BN,
-    bool inclusive,
-    bool reverse>
-__global__ void strided_scan(
-    const T* in,
-    U* out,
-    int32_t axis_size,
-    int64_t stride,
-    int64_t stride_blocks) {
-  auto grid = cg::this_grid();
-  auto block = cg::this_thread_block();
-  auto warp = cg::tiled_partition<WARP_SIZE>(block);
-
-  constexpr int BN_pad = WARP_SIZE + 16 / sizeof(U);
-  constexpr int n_warps = BN / N_READS;
-  constexpr int n_scans = BN / n_warps;
-
-  __shared__ U read_buffer[BM * BN_pad];
-
-  Op op;
-  U init = ReduceInit<Op, T>::value();
-  U values[n_scans];
-  U prefix[n_scans];
-  for (int i = 0; i < n_scans; ++i) {
-    prefix[i] = init;
-  }
-
-  // Compute offsets.
-  int64_t offset = (grid.block_rank() / stride_blocks) * axis_size * stride;
-  int64_t global_index_x = (grid.block_rank() % stride_blocks) * BN;
-  uint read_offset_y = (block.thread_rank() * N_READS) / BN;
-  uint read_offset_x = (block.thread_rank() * N_READS) % BN;
-  uint scan_offset_y = warp.thread_rank();
-  uint scan_offset_x = warp.meta_group_rank() * n_scans;
-
-  uint stride_limit = stride - global_index_x;
-  in += offset + global_index_x + read_offset_x;
-  out += offset + global_index_x + read_offset_x;
-  U* read_into = read_buffer + read_offset_y * BN_pad + read_offset_x;
-  U* read_from = read_buffer + scan_offset_y * BN_pad + scan_offset_x;
-
-  for (uint j = 0; j < axis_size; j += BM) {
-    // Calculate the indices for the current thread.
-    uint index_y = j + read_offset_y;
-    uint check_index_y = index_y;
-    if (reverse) {
-      index_y = axis_size - 1 - index_y;
-    }
-
-    // Read in SM.
-    if (check_index_y < axis_size && (read_offset_x + N_READS) < stride_limit) {
-      for (int i = 0; i < N_READS; ++i) {
-        read_into[i] = in[index_y * stride + i];
-      }
-    } else {
-      for (int i = 0; i < N_READS; ++i) {
-        if (check_index_y < axis_size && (read_offset_x + i) < stride_limit) {
-          read_into[i] = in[index_y * stride + i];
-        } else {
-          read_into[i] = init;
-        }
-      }
-    }
-    block.sync();
-
-    // Read strided into registers.
-    for (int i = 0; i < n_scans; ++i) {
-      values[i] = read_from[i];
-    }
-
-    // Perform the scan.
-    for (int i = 0; i < n_scans; ++i) {
-      values[i] = cg::inclusive_scan(warp, values[i], op);
-      values[i] = op(values[i], prefix[i]);
-      prefix[i] = warp.shfl(values[i], WARP_SIZE - 1);
-    }
-
-    // Write to SM.
-    for (int i = 0; i < n_scans; ++i) {
-      read_from[i] = values[i];
-    }
-    block.sync();
-
-    // Write to device memory.
-    if (!inclusive) {
-      if (check_index_y == 0) {
-        if ((read_offset_x + N_READS) < stride_limit) {
-          for (int i = 0; i < N_READS; ++i) {
-            out[index_y * stride + i] = init;
-          }
-        } else {
-          for (int i = 0; i < N_READS; ++i) {
-            if ((read_offset_x + i) < stride_limit) {
-              out[index_y * stride + i] = init;
-            }
-          }
-        }
-      }
-      if (reverse) {
-        index_y -= 1;
-        check_index_y += 1;
-      } else {
-        index_y += 1;
-        check_index_y += 1;
-      }
-    }
-    if (check_index_y < axis_size && (read_offset_x + N_READS) < stride_limit) {
-      for (int i = 0; i < N_READS; ++i) {
-        out[index_y * stride + i] = read_into[i];
-      }
-    } else {
-      for (int i = 0; i < N_READS; ++i) {
-        if (check_index_y < axis_size && (read_offset_x + i) < stride_limit) {
-          out[index_y * stride + i] = read_into[i];
-        }
-      }
-    }
-  }
-}
-
-} // namespace cu
-
-template <typename F>
-void dispatch_scan_ops(Scan::ReduceType scan_op, F&& f) {
-  if (scan_op == Scan::ReduceType::Max) {
-    f(type_identity<cu::Max>{});
-  } else if (scan_op == Scan::ReduceType::Min) {
-    f(type_identity<cu::Min>{});
-  } else if (scan_op == Scan::ReduceType::Sum) {
-    f(type_identity<cu::Sum>{});
-  } else if (scan_op == Scan::ReduceType::Prod) {
-    f(type_identity<cu::Prod>{});
-  } else if (scan_op == Scan::ReduceType::LogAddExp) {
-    f(type_identity<cu::LogAddExp>{});
-  } else {
-    throw std::invalid_argument("Unknown reduce type.");
-  }
-}
-
-template <typename Op>
-const char* op_to_string() {
-  if (cuda::std::is_same_v<Op, cu::Max>) {
-    return "Max";
-  } else if (cuda::std::is_same_v<Op, cu::Min>) {
-    return "Min";
-  } else if (cuda::std::is_same_v<Op, cu::Sum>) {
-    return "Sum";
-  } else if (cuda::std::is_same_v<Op, cu::Prod>) {
-    return "Prod";
-  } else if (cuda::std::is_same_v<Op, cu::LogAddExp>) {
-    return "LogAddExp";
-  } else {
-    throw std::invalid_argument("Unknown op.");
-  }
-}
-
-template <typename Op, typename T>
-constexpr bool supports_scan_op() {
-  if constexpr (cuda::std::is_same_v<Op, LogAddExp>) {
-    return is_inexact_v<T>;
-  } else {
-    return true;
-  }
-}
-
-void Scan::eval_gpu(const std::vector<array>& inputs, array& out) {
-  nvtx3::scoped_range r("Scan::eval_gpu");
-  assert(inputs.size() == 1);
-  auto in = inputs[0];
-  auto& s = stream();
-
-  if (in.flags().contiguous && in.strides()[axis_] != 0) {
-    if (in.is_donatable() && in.itemsize() == out.itemsize()) {
-      out.copy_shared_buffer(in);
-    } else {
-      out.set_data(
-          allocator::malloc(in.data_size() * out.itemsize()),
-          in.data_size(),
-          in.strides(),
-          in.flags());
-    }
-  } else {
-    array arr_copy(in.shape(), in.dtype(), nullptr, {});
-    copy_gpu(in, arr_copy, CopyType::General, s);
-    in = std::move(arr_copy);
-    out.copy_shared_buffer(in);
-  }
-
-  constexpr int N_READS = 4;
-  int32_t axis_size = in.shape(axis_);
-  bool contiguous = in.strides()[axis_] == 1;
-
-  auto& encoder = cu::get_command_encoder(s);
-  encoder.set_input_array(in);
-  encoder.set_output_array(out);
-
-  dispatch_all_types(in.dtype(), [&](auto type_tag) {
-    using T = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-    dispatch_scan_ops(reduce_type_, [&](auto scan_op_tag) {
-      using Op = MLX_GET_TYPE(scan_op_tag);
-      if constexpr (supports_scan_op<Op, T>) {
-        using U = typename cu::ScanResult<Op, T>::type;
-        dispatch_bool(inclusive_, [&](auto inclusive) {
-          dispatch_bool(reverse_, [&](auto reverse) {
-            if (contiguous) {
-              auto kernel = cu::contiguous_scan<
-                  T,
-                  U,
-                  Op,
-                  N_READS,
-                  inclusive.value,
-                  reverse.value>;
-              int block_dim = cuda::ceil_div(axis_size, N_READS);
-              block_dim = cuda::ceil_div(block_dim, WARP_SIZE) * WARP_SIZE;
-              block_dim = std::min(block_dim, WARP_SIZE * WARP_SIZE);
-              encoder.add_kernel_node(
-                  kernel,
-                  in.data_size() / axis_size,
-                  block_dim,
-                  in.data<T>(),
-                  out.data<U>(),
-                  axis_size);
-            } else {
-              constexpr int BM = WARP_SIZE;
-              constexpr int BN = WARP_SIZE;
-              auto kernel = cu::strided_scan<
-                  T,
-                  U,
-                  Op,
-                  N_READS,
-                  BM,
-                  BN,
-                  inclusive.value,
-                  reverse.value>;
-              int64_t stride = in.strides()[axis_];
-              int64_t stride_blocks = cuda::ceil_div(stride, BN);
-              dim3 num_blocks = get_2d_grid_dims(
-                  in.shape(), in.strides(), axis_size * stride);
-              if (num_blocks.x * stride_blocks <= UINT32_MAX) {
-                num_blocks.x *= stride_blocks;
-              } else {
-                num_blocks.y *= stride_blocks;
-              }
-              int block_dim = (BN / N_READS) * WARP_SIZE;
-              encoder.add_kernel_node(
-                  kernel,
-                  num_blocks,
-                  block_dim,
-                  in.data<T>(),
-                  out.data<U>(),
-                  axis_size,
-                  stride,
-                  stride_blocks);
-            }
-          });
-        });
-      } else {
-        throw std::runtime_error(fmt::format(
-            "Can not do scan op {} on inputs of {} with result of {}.",
-            op_to_string<Op>(),
-            dtype_to_string(in.dtype()),
-            dtype_to_string(out.dtype())));
-      }
-    });
-  });
-}
-
-} // namespace mlx::core

mlx/backend/cuda/softmax.cu

@@ -43,7 +43,7 @@ __global__ void softmax(const T* in, T* out, int axis_size) {
   // Thread reduce.
   AccT prevmax;
   AccT maxval = Limits<AccT>::finite_min();
-  AccT normalizer = cast_to<AccT>(0);
+  AccT normalizer = 0;
   for (int r = 0; r < cuda::ceil_div(axis_size, BLOCK_DIM * N_READS); r++) {
     AccT vals[N_READS];
     cub::LoadDirectBlocked(
@@ -51,7 +51,7 @@ __global__ void softmax(const T* in, T* out, int axis_size) {
         make_cast_iterator<AccT>(in),
         vals,
         axis_size,
-        Limits<AccT>::min());
+        Limits<AccT>::finite_min());
     prevmax = maxval;
     maxval = max_op(maxval, cub::ThreadReduce(vals, max_op));
     // Online normalizer calculation for softmax:
@@ -79,7 +79,7 @@ __global__ void softmax(const T* in, T* out, int axis_size) {
   block.sync();
   maxval = warp.thread_rank() < warp.meta_group_size()
       ? local_max[warp.thread_rank()]
-      : Limits<AccT>::min();
+      : Limits<AccT>::finite_min();
   maxval = cg::reduce(warp, maxval, max_op);
   normalizer = normalizer * softmax_exp(prevmax - maxval);
   if (warp.thread_rank() == 0) {
@@ -141,21 +141,18 @@ void Softmax::eval_gpu(const std::vector<array>& inputs, array& out) {
   auto& encoder = cu::get_command_encoder(s);
   encoder.set_input_array(in);
   encoder.set_output_array(out);
-  dispatch_float_types(out.dtype(), "softmax", [&](auto type_tag) {
-    constexpr int N_READS = 4;
-    dispatch_block_dim(cuda::ceil_div(axis_size, N_READS), [&](auto block_dim) {
-      using DataType = cuda_type_t<MLX_GET_TYPE(type_tag)>;
-      auto kernel = cu::softmax<DataType, DataType, block_dim(), N_READS>;
-      if (precise) {
-        kernel = cu::softmax<DataType, float, block_dim(), N_READS>;
-      }
-      encoder.add_kernel_node(
-          kernel,
-          n_rows,
-          block_dim(),
-          in.data<DataType>(),
-          out.data<DataType>(),
-          axis_size);
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_FLOAT_TYPES_CHECKED(out.dtype(), "softmax", CTYPE, {
+      using DataType = cuda_type_t<CTYPE>;
+      constexpr int N_READS = 4;
+      MLX_SWITCH_BLOCK_DIM(cuda::ceil_div(axis_size, N_READS), BLOCK_DIM, {
+        auto kernel = cu::softmax<DataType, DataType, BLOCK_DIM, N_READS>;
+        if (precise) {
+          kernel = cu::softmax<DataType, float, BLOCK_DIM, N_READS>;
+        }
+        kernel<<<n_rows, BLOCK_DIM, 0, stream>>>(
+            in.data<DataType>(), out.data<DataType>(), axis_size);
+      });
     });
   });
 }

mlx/backend/cuda/sort.cu

@@ -50,21 +50,43 @@ array swapaxes_in_eval(const array& in, int axis1, int axis2) {
   return out;
 }
 
-struct OffsetTransform {
-  int nsort;
+template <typename... Args>
+void segmented_sort_pairs(cu::CommandEncoder& encoder, Args&&... args) {
+  // Allocate temporary storage.
+  size_t size;
+  CHECK_CUDA_ERROR(
+      cub::DeviceSegmentedSort::StableSortPairs(nullptr, size, args...));
+  array temp(allocator::malloc(size), {static_cast<int>(size)}, uint8);
+  encoder.add_temporary(temp);
+  // Run op.
+  CHECK_CUDA_ERROR(cub::DeviceSegmentedSort::StableSortPairs(
+      temp.data<void>(), size, args...));
+}
 
-  int __device__ operator()(int i) {
-    return i * nsort;
-  }
-};
+template <typename... Args>
+void segmented_sort(cu::CommandEncoder& encoder, Args&&... args) {
+  // Allocate temporary storage.
+  size_t size;
+  CHECK_CUDA_ERROR(
+      cub::DeviceSegmentedSort::StableSortKeys(nullptr, size, args...));
+  array temp(allocator::malloc(size), {static_cast<int>(size)}, uint8);
+  encoder.add_temporary(temp);
+  // Run op.
+  CHECK_CUDA_ERROR(cub::DeviceSegmentedSort::StableSortKeys(
+      temp.data<void>(), size, args...));
+}
 
 void gpu_sort(const Stream& s, array in, array& out_, int axis, bool argsort) {
   array out = out_;
   auto& encoder = cu::get_command_encoder(s);
+  encoder.set_input_array(in);
+  encoder.set_output_array(out);
+
   if (axis < 0) {
     axis += in.ndim();
   }
   int nsort = in.shape(axis);
+  int nsegments = in.data_size() / nsort;
   int last_dim = in.ndim() - 1;
 
   // If we are not sorting the innermost dimension of a contiguous array,
@@ -78,103 +100,60 @@ void gpu_sort(const Stream& s, array in, array& out_, int axis, bool argsort) {
     out = array(allocator::malloc(out.nbytes()), in.shape(), out.dtype());
     encoder.add_temporary(out);
   } else {
-    out.set_data(
-        allocator::malloc(in.data_size() * out.itemsize()),
-        in.data_size(),
-        in.strides(),
-        in.flags());
+    out.set_data(allocator::malloc(out.nbytes()));
   }
 
-  encoder.set_input_array(in);
-  encoder.set_output_array(out);
-  dispatch_all_types(in.dtype(), [&](auto type_tag) {
-    using CTYPE = MLX_GET_TYPE(type_tag);
-    auto& stream = encoder.stream();
-    if constexpr (!std::is_same_v<CTYPE, complex64_t>) {
-      using Type = cuda_type_t<CTYPE>;
-      auto offsets = thrust::make_transform_iterator(
-          thrust::make_counting_iterator(0), OffsetTransform{nsort});
-      if (argsort) {
-        // Indices in the sorted dimension.
-        array indices(allocator::malloc(out.nbytes()), in.shape(), out.dtype());
-        encoder.add_temporary(indices);
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_ALL_TYPES(in.dtype(), CTYPE, {
+      if constexpr (!std::is_same_v<CTYPE, complex64_t>) {
+        using Type = cuda_type_t<CTYPE>;
+        auto offsets = thrust::make_transform_iterator(
+            thrust::make_counting_iterator(0),
+            [nsort] __device__(int i) { return i * nsort; });
+        if (argsort) {
+          // Indices in the sorted dimension.
+          array indices(
+              allocator::malloc(out.nbytes()), in.shape(), out.dtype());
+          encoder.add_temporary(indices);
+          thrust::transform(
+              cu::thrust_policy(stream),
+              thrust::counting_iterator<uint32_t>(0),
+              thrust::counting_iterator<uint32_t>(indices.data_size()),
+              thrust::device_pointer_cast(indices.data<uint32_t>()),
+              ModOp<uint32_t>{static_cast<uint32_t>(nsort)});
 
-        // In argsort though we don't need the result of sorted values, the
-        // API requires us to provide an array to store it.
-        array discard(allocator::malloc(in.nbytes()), in.shape(), in.dtype());
-        encoder.add_temporary(discard);
+          // In argsort though we don't need the result of sorted values, the
+          // API requires us to provide an array to store it.
+          array discard(allocator::malloc(in.nbytes()), in.shape(), in.dtype());
+          encoder.add_temporary(discard);
 
-        size_t size;
-        CHECK_CUDA_ERROR(cub::DeviceSegmentedSort::StableSortPairs(
-            nullptr,
-            size,
-            in.data<Type>(),
-            discard.data<Type>(),
-            indices.data<uint32_t>(),
-            out.data<uint32_t>(),
-            in.data_size(),
-            in.data_size() / nsort,
-            offsets,
-            offsets + 1,
-            stream));
-
-        array temp(allocator::malloc(size), {static_cast<int>(size)}, uint8);
-        encoder.add_temporary(temp);
-
-        // Start capturing after allocations
-        auto capture = encoder.capture_context();
-        thrust::transform(
-            cu::thrust_policy(stream),
-            thrust::counting_iterator<uint32_t>(0),
-            thrust::counting_iterator<uint32_t>(indices.data_size()),
-            thrust::device_pointer_cast(indices.data<uint32_t>()),
-            ModOp<uint32_t>{static_cast<uint32_t>(nsort)});
-
-        CHECK_CUDA_ERROR(cub::DeviceSegmentedSort::StableSortPairs(
-            temp.data<void>(),
-            size,
-            in.data<Type>(),
-            discard.data<Type>(),
-            indices.data<uint32_t>(),
-            out.data<uint32_t>(),
-            in.data_size(),
-            in.data_size() / nsort,
-            offsets,
-            offsets + 1,
-            stream));
+          segmented_sort_pairs(
+              encoder,
+              in.data<Type>(),
+              discard.data<Type>(),
+              indices.data<uint32_t>(),
+              out.data<uint32_t>(),
+              in.data_size(),
+              nsegments,
+              offsets,
+              offsets + 1,
+              stream);
+        } else {
+          segmented_sort(
+              encoder,
+              in.data<Type>(),
+              out.data<Type>(),
+              in.data_size(),
+              nsegments,
+              offsets,
+              offsets + 1,
+              stream);
+        }
       } else {
-        size_t size;
-        CHECK_CUDA_ERROR(cub::DeviceSegmentedSort::StableSortKeys(
-            nullptr,
-            size,
-            in.data<Type>(),
-            out.data<Type>(),
-            in.data_size(),
-            in.data_size() / nsort,
-            offsets,
-            offsets + 1,
-            stream));
-
-        array temp(allocator::malloc(size), {static_cast<int>(size)}, uint8);
-        encoder.add_temporary(temp);
-
-        // Start capturing after allocations
-        auto capture = encoder.capture_context();
-        CHECK_CUDA_ERROR(cub::DeviceSegmentedSort::StableSortKeys(
-            temp.data<void>(),
-            size,
-            in.data<Type>(),
-            out.data<Type>(),
-            in.data_size(),
-            in.data_size() / nsort,
-            offsets,
-            offsets + 1,
-            stream));
+        throw std::runtime_error(
+            "CUDA backend does not support sorting complex numbers");
       }
-    } else {
-      throw std::runtime_error(
-          "CUDA backend does not support sorting complex numbers");
-    }
+    });
   });
 
   if (!is_segmented_sort) {
@@ -198,14 +177,4 @@ void Sort::eval_gpu(const std::vector<array>& inputs, array& out) {
   gpu_sort(stream(), inputs[0], out, axis_, false);
 }
 
-void ArgPartition::eval_gpu(const std::vector<array>& inputs, array& out) {
-  nvtx3::scoped_range r("ArgPartition::eval_gpu");
-  gpu_sort(stream(), inputs[0], out, axis_, true);
-}
-
-void Partition::eval_gpu(const std::vector<array>& inputs, array& out) {
-  nvtx3::scoped_range r("Partition::eval_gpu");
-  gpu_sort(stream(), inputs[0], out, axis_, false);
-}
-
 } // namespace mlx::core

mlx/backend/cuda/ternary.cu

@@ -15,27 +15,12 @@ namespace cu {
 
 namespace cg = cooperative_groups;
 
-template <typename Op, typename T, typename IdxT, int N_READS>
+template <typename Op, typename T, typename IdxT>
 __global__ void
 ternary_v(const bool* a, const T* b, const T* c, T* out, IdxT size) {
   IdxT index = cg::this_grid().thread_rank();
-
-  if ((index + 1) * N_READS > size) {
-    for (IdxT i = index * N_READS; i < size; ++i) {
-      out[i] = Op{}(a[i], b[i], c[i]);
-    }
-  } else {
-    auto a_vec = load_vector<N_READS>(a, index);
-    auto b_vec = load_vector<N_READS>(b, index);
-    auto c_vec = load_vector<N_READS>(c, index);
-
-    AlignedVector<T, N_READS> out_vec;
-#pragma unroll
-    for (int i = 0; i < N_READS; ++i) {
-      out_vec.val[i] = Op{}(a_vec.val[i], b_vec.val[i], c_vec.val[i]);
-    }
-
-    store_vector<N_READS>(out, index, out_vec);
+  if (index < size) {
+    out[index] = Op{}(a[index], b[index], c[index]);
   }
 }
 
@@ -106,87 +91,68 @@ void ternary_op_gpu_inplace(
   encoder.set_input_array(b);
   encoder.set_input_array(c);
   encoder.set_output_array(out);
-  dispatch_all_types(out.dtype(), [&](auto type_tag) {
-    using DType = cuda_type_t<MLX_GET_TYPE(type_tag)>;
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_ALL_TYPES(out.dtype(), CTYPE, {
+      using DType = cuda_type_t<CTYPE>;
 
-    auto topt = get_ternary_op_type(a, b, c);
-    if (topt == TernaryOpType::General) {
-      dispatch_bool(
-          a.data_size() > INT32_MAX || b.data_size() > INT32_MAX ||
-              c.data_size() > INT32_MAX || out.data_size() > INT32_MAX,
-          [&](auto large) {
-            using IdxT = std::conditional_t<large(), int64_t, int32_t>;
-            Shape shape;
-            std::vector<Strides> strides;
-            std::tie(shape, strides) = collapse_contiguous_dims(a, b, c, out);
-            auto& a_strides = strides[0];
-            auto& b_strides = strides[1];
-            auto& c_strides = strides[2];
-            int ndim = shape.size();
-            if (ndim <= 3) {
-              dispatch_1_2_3(ndim, [&](auto dims_constant) {
-                auto kernel =
-                    cu::ternary_g_nd<Op, DType, IdxT, dims_constant()>;
-                auto [num_blocks, block_dims] =
-                    get_launch_args(kernel, out, large());
-                encoder.add_kernel_node(
-                    kernel,
-                    num_blocks,
-                    block_dims,
-                    a.data<bool>(),
-                    b.data<DType>(),
-                    c.data<DType>(),
-                    out.data<DType>(),
-                    out.size(),
-                    const_param<dims_constant()>(shape),
-                    const_param<dims_constant()>(a_strides),
-                    const_param<dims_constant()>(b_strides),
-                    const_param<dims_constant()>(c_strides));
-              });
-            } else {
-              auto kernel = cu::ternary_g<Op, DType, IdxT>;
+      auto topt = get_ternary_op_type(a, b, c);
+      if (topt == TernaryOpType::General) {
+        auto [shape, strides] = collapse_contiguous_dims(a, b, c, out);
+        auto& a_strides = strides[0];
+        auto& b_strides = strides[1];
+        auto& c_strides = strides[2];
+        bool large = a.data_size() > INT32_MAX || b.data_size() > INT32_MAX ||
+            c.data_size() > INT32_MAX || out.data_size() > INT32_MAX;
+        MLX_SWITCH_BOOL(large, LARGE, {
+          using IdxT = std::conditional_t<LARGE, int64_t, int32_t>;
+          int ndim = shape.size();
+          if (ndim <= 3) {
+            MLX_SWITCH_1_2_3(ndim, NDIM, {
+              auto kernel = cu::ternary_g_nd<Op, DType, IdxT, NDIM>;
               auto [num_blocks, block_dims] =
-                  get_launch_args(kernel, out, large());
-              encoder.add_kernel_node(
-                  kernel,
-                  num_blocks,
-                  block_dims,
+                  get_launch_args(kernel, out, large);
+              kernel<<<num_blocks, block_dims, 0, stream>>>(
                   a.data<bool>(),
                   b.data<DType>(),
                   c.data<DType>(),
                   out.data<DType>(),
-                  out.data_size(),
-                  const_param(shape),
-                  const_param(a_strides),
-                  const_param(b_strides),
-                  const_param(c_strides),
-                  ndim);
-            }
-          });
-    } else {
-      dispatch_bool(out.data_size() > UINT32_MAX, [&](auto large) {
-        using IdxT = std::conditional_t<large(), int64_t, uint32_t>;
-        // TODO: Choose optimized value based on type size.
-        constexpr int N_READS = 4;
-        auto kernel = cu::ternary_v<Op, DType, IdxT, N_READS>;
-        auto [num_blocks, block_dims] = get_launch_args(
-            kernel,
-            out.data_size(),
-            out.shape(),
-            out.strides(),
-            large(),
-            N_READS);
-        encoder.add_kernel_node(
-            kernel,
-            num_blocks,
-            block_dims,
-            a.data<bool>(),
-            b.data<DType>(),
-            c.data<DType>(),
-            out.data<DType>(),
-            out.data_size());
-      });
-    }
+                  out.size(),
+                  const_param<NDIM>(shape),
+                  const_param<NDIM>(a_strides),
+                  const_param<NDIM>(b_strides),
+                  const_param<NDIM>(c_strides));
+            });
+          } else {
+            auto kernel = cu::ternary_g<Op, DType, IdxT>;
+            auto [num_blocks, block_dims] = get_launch_args(kernel, out, large);
+            kernel<<<num_blocks, block_dims, 0, stream>>>(
+                a.data<bool>(),
+                b.data<DType>(),
+                c.data<DType>(),
+                out.data<DType>(),
+                out.data_size(),
+                const_param(shape),
+                const_param(a_strides),
+                const_param(b_strides),
+                const_param(c_strides),
+                ndim);
+          }
+        });
+      } else {
+        MLX_SWITCH_BOOL(out.data_size() > UINT32_MAX, LARGE, {
+          using IdxT = std::conditional_t<LARGE, int64_t, uint32_t>;
+          auto kernel = cu::ternary_v<Op, DType, IdxT>;
+          auto [num_blocks, block_dims] = get_launch_args(
+              kernel, out.data_size(), out.shape(), out.strides(), LARGE);
+          kernel<<<num_blocks, block_dims, 0, stream>>>(
+              a.data<bool>(),
+              b.data<DType>(),
+              c.data<DType>(),
+              out.data<DType>(),
+              out.data_size());
+        });
+      }
+    });
   });
 }
 

mlx/backend/cuda/unary.cu

@@ -9,83 +9,49 @@
 #include "mlx/dtype_utils.h"
 #include "mlx/primitives.h"
 
-#include <cooperative_groups.h>
 #include <nvtx3/nvtx3.hpp>
+#include <thrust/device_ptr.h>
+#include <thrust/transform.h>
 
 namespace mlx::core {
 
 namespace cu {
 
-namespace cg = cooperative_groups;
-
-template <typename Op, typename In, typename Out, typename IdxT, int N_READS>
-__global__ void unary_v(const In* in, Out* out, IdxT size) {
-  IdxT index = cg::this_grid().thread_rank();
-
-  if ((index + 1) * N_READS > size) {
-    for (IdxT i = index * N_READS; i < size; ++i) {
-      out[i] = Op{}(in[i]);
-    }
-  } else {
-    auto in_vec = load_vector<N_READS>(in, index);
-
-    AlignedVector<Out, N_READS> out_vec;
-#pragma unroll
-    for (int i = 0; i < N_READS; ++i) {
-      out_vec.val[i] = Op{}(in_vec.val[i]);
-    }
-
-    store_vector<N_READS>(out, index, out_vec);
-  }
-}
-
-template <typename Op, typename In, typename Out, typename IdxT>
-__global__ void unary_g(
-    const In* in,
-    Out* out,
-    IdxT size,
-    const __grid_constant__ Shape shape,
-    const __grid_constant__ Strides strides,
-    int ndim) {
-  IdxT index = cg::this_grid().thread_rank();
-  if (index < size) {
-    auto idx = elem_to_loc_4d(index, shape.data(), strides.data(), ndim);
-    out[index] = Op{}(in[idx]);
-  }
-}
-
 template <typename Op, typename In, typename Out>
 constexpr bool supports_unary_op() {
   if (std::is_same_v<Op, Abs> || std::is_same_v<Op, Negative> ||
-      std::is_same_v<Op, Sign> || std::is_same_v<Op, Square>) {
+      std::is_same_v<Op, Sign>) {
     return std::is_same_v<In, Out>;
   }
-  if (std::is_same_v<Op, ArcCosh> || std::is_same_v<Op, ArcSinh> ||
-      std::is_same_v<Op, ArcTanh> || std::is_same_v<Op, Erf> ||
-      std::is_same_v<Op, ErfInv> || std::is_same_v<Op, Expm1> ||
-      std::is_same_v<Op, Sigmoid>) {
+  if (std::is_same_v<Op, ArcCos> || std::is_same_v<Op, ArcCosh> ||
+      std::is_same_v<Op, ArcSin> || std::is_same_v<Op, ArcSinh> ||
+      std::is_same_v<Op, ArcTan> || std::is_same_v<Op, ArcTanh> ||
+      std::is_same_v<Op, Erf> || std::is_same_v<Op, ErfInv> ||
+      std::is_same_v<Op, Expm1> || std::is_same_v<Op, Sigmoid> ||
+      std::is_same_v<Op, Sqrt> || std::is_same_v<Op, Rsqrt>) {
     return std::is_same_v<In, Out> && is_floating_v<In>;
   }
+  if (std::is_same_v<Op, Log> || std::is_same_v<Op, Log2> ||
+      std::is_same_v<Op, Log10> || std::is_same_v<Op, Log1p>) {
+    return std::is_same_v<In, Out> && is_inexact_v<In>;
+  }
   if (std::is_same_v<Op, BitwiseInvert>) {
     return std::is_same_v<In, Out> && std::is_integral_v<In> &&
         !std::is_same_v<In, bool>;
   }
-  if (std::is_same_v<Op, Ceil> || std::is_same_v<Op, Floor>) {
+  if (std::is_same_v<Op, Ceil> || std::is_same_v<Op, Floor> ||
+      std::is_same_v<Op, Square>) {
     return std::is_same_v<In, Out> && !std::is_same_v<In, complex64_t>;
   }
   if (std::is_same_v<Op, Conjugate>) {
     return std::is_same_v<In, Out> && std::is_same_v<In, complex64_t>;
   }
-  if (std::is_same_v<Op, ArcCos> || std::is_same_v<Op, ArcSin> ||
-      std::is_same_v<Op, ArcTan> || std::is_same_v<Op, Cos> ||
-      std::is_same_v<Op, Cosh> || std::is_same_v<Op, Exp> ||
-      std::is_same_v<Op, Log> || std::is_same_v<Op, Log2> ||
-      std::is_same_v<Op, Log10> || std::is_same_v<Op, Log1p> ||
-      std::is_same_v<Op, Round> || std::is_same_v<Op, Rsqrt> ||
-      std::is_same_v<Op, Sqrt> || std::is_same_v<Op, Sin> ||
-      std::is_same_v<Op, Sinh> || std::is_same_v<Op, Tan> ||
-      std::is_same_v<Op, Tanh>) {
-    return std::is_same_v<In, Out> && is_inexact_v<In>;
+  if (std::is_same_v<Op, Cos> || std::is_same_v<Op, Cosh> ||
+      std::is_same_v<Op, Exp> || std::is_same_v<Op, Round> ||
+      std::is_same_v<Op, Sin> || std::is_same_v<Op, Sinh> ||
+      std::is_same_v<Op, Tan> || std::is_same_v<Op, Tanh>) {
+    return std::is_same_v<In, Out> &&
+        (is_floating_v<In> || std::is_same_v<In, complex64_t>);
   }
   if (std::is_same_v<Op, Imag> || std::is_same_v<Op, Real>) {
     return std::is_same_v<In, complex64_t> && std::is_same_v<Out, float>;
@@ -108,68 +74,36 @@ void unary_op_gpu_inplace(
   if (in.size() == 0) {
     return;
   }
-  bool contig = in.flags().contiguous;
-  bool large;
-  if (!contig) {
-    large = in.data_size() > INT32_MAX || out.size() > INT32_MAX;
-  } else {
-    large = in.data_size() > UINT32_MAX;
-  }
 
   auto& encoder = cu::get_command_encoder(s);
   encoder.set_input_array(in);
   encoder.set_output_array(out);
-  dispatch_all_types(in.dtype(), [&](auto in_type_tag) {
-    dispatch_all_types(out.dtype(), [&](auto out_type_tag) {
-      using CTYPE_IN = MLX_GET_TYPE(in_type_tag);
-      using CTYPE_OUT = MLX_GET_TYPE(out_type_tag);
-      if constexpr (cu::supports_unary_op<Op, CTYPE_IN, CTYPE_OUT>()) {
-        dispatch_bool(large, [&](auto large) {
+  encoder.launch_kernel([&](cudaStream_t stream) {
+    MLX_SWITCH_ALL_TYPES(in.dtype(), CTYPE_IN, {
+      MLX_SWITCH_ALL_TYPES(out.dtype(), CTYPE_OUT, {
+        if constexpr (cu::supports_unary_op<Op, CTYPE_IN, CTYPE_OUT>()) {
           using InType = cuda_type_t<CTYPE_IN>;
           using OutType = cuda_type_t<CTYPE_OUT>;
-          if (contig) {
-            using IdxT = std::conditional_t<large(), int64_t, uint32_t>;
-            // TODO: Choose optimized value based on type size.
-            constexpr int N_READS = 4;
-            auto kernel = cu::unary_v<Op, InType, OutType, IdxT, N_READS>;
-            auto [num_blocks, block_dims] = get_launch_args(
-                kernel,
-                out.data_size(),
-                out.shape(),
-                out.strides(),
-                large,
-                N_READS);
-            encoder.add_kernel_node(
-                kernel,
-                num_blocks,
-                block_dims,
-                in.data<InType>(),
-                out.data<OutType>(),
-                out.data_size());
+          auto policy = cu::thrust_policy(stream);
+          auto in_ptr = thrust::device_pointer_cast(in.data<InType>());
+          auto out_ptr = thrust::device_pointer_cast(out.data<OutType>());
+          if (in.flags().contiguous) {
+            thrust::transform(
+                policy, in_ptr, in_ptr + in.data_size(), out_ptr, Op());
           } else {
-            using IdxT = std::conditional_t<large(), int64_t, int32_t>;
             auto [shape, strides] = collapse_contiguous_dims(in);
-            auto kernel = cu::unary_g<Op, InType, OutType, IdxT>;
-            auto [num_blocks, block_dims] = get_launch_args(kernel, out, large);
-            encoder.add_kernel_node(
-                kernel,
-                num_blocks,
-                block_dims,
-                in.data<InType>(),
-                out.data<OutType>(),
-                out.data_size(),
-                const_param(shape),
-                const_param(strides),
-                shape.size());
+            auto [in_begin, in_end] = cu::make_general_iterators<int64_t>(
+                in_ptr, in.size(), shape, strides);
+            thrust::transform(policy, in_begin, in_end, out_ptr, Op());
           }
-        });
-      } else {
-        throw std::runtime_error(fmt::format(
-            "Can not do unary op {} on input of {} with output of {}.",
-            op,
-            dtype_to_string(in.dtype()),
-            dtype_to_string(out.dtype())));
-      }
+        } else {
+          throw std::runtime_error(fmt::format(
+              "Can not do unary op {} on input of {} with output of {}.",
+              op,
+              dtype_to_string(in.dtype()),
+              dtype_to_string(out.dtype())));
+        }
+      });
     });
   });
 }

mlx/backend/cuda/utils.cpp

@@ -24,47 +24,23 @@ void check_cuda_error(const char* name, cudaError_t err) {
   }
 }
 
-void check_cuda_error(const char* name, CUresult err) {
-  if (err != CUDA_SUCCESS) {
-    const char* err_str = "Unknown error";
-    cuGetErrorString(err, &err_str);
-    throw std::runtime_error(fmt::format("{} failed: {}", name, err_str));
-  }
-}
-
 const char* dtype_to_cuda_type(const Dtype& dtype) {
-  switch (dtype) {
-    case bool_:
-      return "bool";
-    case int8:
-      return "int8_t";
-    case int16:
-      return "int16_t";
-    case int32:
-      return "int32_t";
-    case int64:
-      return "int64_t";
-    case uint8:
-      return "uint8_t";
-    case uint16:
-      return "uint16_t";
-    case uint32:
-      return "uint32_t";
-    case uint64:
-      return "uint64_t";
-    case float16:
-      return "__half";
-    case bfloat16:
-      return "__nv_bfloat16";
-    case float32:
-      return "float";
-    case float64:
-      return "double";
-    case complex64:
-      return "cuComplex";
-    default:
-      return "unknown";
+  if (dtype == float16) {
+    return "__half";
   }
+  if (dtype == bfloat16) {
+    return "__nv_bfloat16";
+  }
+  if (dtype == complex64) {
+    return "cuComplex";
+  }
+#define SPECIALIZE_DtypeToString(CPP_TYPE, DTYPE) \
+  if (dtype == DTYPE) {                           \
+    return #CPP_TYPE;                             \
+  }
+  MLX_FORALL_DTYPES(SPECIALIZE_DtypeToString)
+#undef SPECIALIZE_DtypeToString
+  return nullptr;
 }
 
 } // namespace mlx::core

mlx/backend/cuda/utils.h

@@ -4,7 +4,6 @@
 
 #pragma once
 
-#include <cuda.h>
 #include <cuda_runtime.h>
 
 namespace mlx::core {
@@ -34,7 +33,6 @@ class CudaStream {
 
 // Throw exception if the cuda API does not succeed.
 void check_cuda_error(const char* name, cudaError_t err);
-void check_cuda_error(const char* name, CUresult err);
 
 // The macro version that prints the command that failed.
 #define CHECK_CUDA_ERROR(cmd) check_cuda_error(#cmd, (cmd))

mlx/backend/cuda/worker.cpp

@@ -80,9 +80,7 @@ void Worker::thread_fn() {
       }
       worker_tasks_.erase(worker_tasks_.begin(), end);
     }
-    // Make sure tasks are cleared before the next wait
-    for (int i = 0; i < tasks.size(); ++i) {
-      auto task = std::move(tasks[i]);
+    for (auto& task : tasks) {
       task();
     }
     worker_event_.wait(batch + 1);

mlx/backend/metal/CMakeLists.txt

@@ -63,7 +63,6 @@ if(MLX_METAL_JIT)
   make_jit_source(steel/gemm/kernels/steel_gemm_masked kernels/steel/defines.h)
   make_jit_source(steel/gemm/kernels/steel_gemm_gather)
   make_jit_source(steel/gemm/kernels/steel_gemm_splitk)
-  make_jit_source(steel/gemm/kernels/steel_gemm_segmented)
   make_jit_source(
     steel/conv/conv
     kernels/steel/utils.h

mlx/backend/metal/indexing.cpp

@@ -575,17 +575,9 @@ void ScatterAxis::eval_gpu(const std::vector<array>& inputs, array& out) {
   compute_encoder.set_output_array(out, 2);
 
   // Set source info
-  if (ndim > 1) {
-    compute_encoder.set_vector_bytes(remove_index(idx.shape(), axis_), 3);
-    compute_encoder.set_vector_bytes(remove_index(upd.strides(), axis_), 4);
-    compute_encoder.set_vector_bytes(remove_index(idx.strides(), axis_), 5);
-  } else {
-    // The following will be ignored in the kernel but we still have to set
-    // some value so that metal validation passes.
-    compute_encoder.set_vector_bytes(idx.shape(), 3);
-    compute_encoder.set_vector_bytes(upd.strides(), 4);
-    compute_encoder.set_vector_bytes(idx.strides(), 5);
-  }
+  compute_encoder.set_vector_bytes(remove_index(idx.shape(), axis_), 3);
+  compute_encoder.set_vector_bytes(remove_index(upd.strides(), axis_), 4);
+  compute_encoder.set_vector_bytes(remove_index(idx.strides(), axis_), 5);
   compute_encoder.set_bytes(ndim - 1, 6);
   compute_encoder.set_bytes(axis_, 7);
   compute_encoder.set_bytes(out.shape(axis_), 8);

mlx/backend/metal/jit/includes.h

@@ -34,7 +34,6 @@ const char* steel_gemm_fused();
 const char* steel_gemm_masked();
 const char* steel_gemm_splitk();
 const char* steel_gemm_gather();
-const char* steel_gemm_segmented();
 const char* conv();
 const char* steel_conv();
 const char* steel_conv_general();

mlx/backend/metal/jit_kernels.cpp

@@ -652,43 +652,6 @@ MTL::ComputePipelineState* get_steel_gemm_gather_kernel(
   return d.get_kernel(kernel_name, lib, hash_name, func_consts);
 }
 
-MTL::ComputePipelineState* get_steel_gemm_segmented_kernel(
-    metal::Device& d,
-    const std::string& kernel_name,
-    const std::string& hash_name,
-    const metal::MTLFCList& func_consts,
-    const array& out,
-    bool transpose_a,
-    bool transpose_b,
-    int bm,
-    int bn,
-    int bk,
-    int wm,
-    int wn) {
-  const auto& lib_name = kernel_name;
-  auto lib = d.get_library(lib_name, [&]() {
-    std::string kernel_source;
-    concatenate(
-        kernel_source,
-        metal::utils(),
-        metal::gemm(),
-        metal::steel_gemm_segmented(),
-        get_template_definition(
-            lib_name,
-            "segmented_mm",
-            get_type_string(out.dtype()),
-            bm,
-            bn,
-            bk,
-            wm,
-            wn,
-            transpose_a,
-            transpose_b));
-    return kernel_source;
-  });
-  return d.get_kernel(kernel_name, lib, hash_name, func_consts);
-}
-
 MTL::ComputePipelineState* get_gemv_masked_kernel(
     metal::Device& d,
     const std::string& kernel_name,

mlx/backend/metal/kernels.h

@@ -175,20 +175,6 @@ MTL::ComputePipelineState* get_steel_gemm_gather_kernel(
     int wn,
     bool rhs);
 
-MTL::ComputePipelineState* get_steel_gemm_segmented_kernel(
-    metal::Device& d,
-    const std::string& kernel_name,
-    const std::string& hash_name,
-    const metal::MTLFCList& func_consts,
-    const array& out,
-    bool transpose_a,
-    bool transpose_b,
-    int bm,
-    int bn,
-    int bk,
-    int wm,
-    int wn);
-
 MTL::ComputePipelineState* get_steel_conv_kernel(
     metal::Device& d,
     const std::string& kernel_name,

mlx/backend/metal/kernels/CMakeLists.txt

@@ -71,7 +71,6 @@ set(STEEL_HEADERS
     steel/gemm/kernels/steel_gemm_fused.h
     steel/gemm/kernels/steel_gemm_gather.h
     steel/gemm/kernels/steel_gemm_masked.h
-    steel/gemm/kernels/steel_gemm_segmented.h
     steel/gemm/kernels/steel_gemm_splitk.h
     steel/utils/type_traits.h
     steel/utils/integral_constant.h)
@@ -121,7 +120,6 @@ if(NOT MLX_METAL_JIT)
   build_kernel(steel/gemm/kernels/steel_gemm_gather ${STEEL_HEADERS})
   build_kernel(steel/gemm/kernels/steel_gemm_masked ${STEEL_HEADERS})
   build_kernel(steel/gemm/kernels/steel_gemm_splitk ${STEEL_HEADERS})
-  build_kernel(steel/gemm/kernels/steel_gemm_segmented ${STEEL_HEADERS})
   build_kernel(gemv_masked steel/utils.h)
 endif()
 

mlx/backend/metal/kernels/cexpf.h

@@ -1,134 +0,0 @@
-// Copyright © 2025 Apple Inc.
-// Copyright © 2008-2013 NVIDIA Corporation
-// Copyright © 2013 Filipe RNC Maia
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-//
-// Forked from
-// https://github.com/NVIDIA/cccl/blob/main/thrust/thrust/detail/complex/cexpf.h
-
-// TODO: We should use thrust::exp but the thrust header in old CUDA versions
-// can not be used in JIT.
-
-#pragma once
-
-#include <metal_math>
-
-using ieee_float_shape_type = union {
-  float value;
-  uint32_t word;
-};
-
-inline void get_float_word(thread uint32_t& i, float d) {
-  ieee_float_shape_type gf_u;
-  gf_u.value = (d);
-  (i) = gf_u.word;
-}
-
-inline void get_float_word(thread int32_t& i, float d) {
-  ieee_float_shape_type gf_u;
-  gf_u.value = (d);
-  (i) = gf_u.word;
-}
-
-inline void set_float_word(thread float& d, uint32_t i) {
-  ieee_float_shape_type sf_u;
-  sf_u.word = (i);
-  (d) = sf_u.value;
-}
-
-inline float frexp_expf(float x, thread int* expt) {
-  const uint32_t k = 235;
-  const float kln2 = 162.88958740F;
-
-  float exp_x;
-  uint32_t hx;
-
-  exp_x = metal::exp(x - kln2);
-  get_float_word(hx, exp_x);
-  *expt = (hx >> 23) - (0x7f + 127) + k;
-  set_float_word(exp_x, (hx & 0x7fffff) | ((0x7f + 127) << 23));
-  return exp_x;
-}
-
-inline complex64_t ldexp_cexpf(complex64_t z, int expt) {
-  float x, y, exp_x, scale1, scale2;
-  int ex_expt, half_expt;
-
-  x = z.real;
-  y = z.imag;
-  exp_x = frexp_expf(x, &ex_expt);
-  expt += ex_expt;
-
-  half_expt = expt / 2;
-  set_float_word(scale1, (0x7f + half_expt) << 23);
-  half_expt = expt - half_expt;
-  set_float_word(scale2, (0x7f + half_expt) << 23);
-
-  return complex64_t{
-      metal::cos(y) * exp_x * scale1 * scale2,
-      metal::sin(y) * exp_x * scale1 * scale2};
-}
-
-inline complex64_t cexpf(const thread complex64_t& z) {
-  float x, y, exp_x;
-  uint32_t hx, hy;
-
-  const uint32_t exp_ovfl = 0x42b17218, cexp_ovfl = 0x43400074;
-
-  x = z.real;
-  y = z.imag;
-
-  get_float_word(hy, y);
-  hy &= 0x7fffffff;
-
-  /* cexp(x + I 0) = exp(x) + I 0 */
-  if (hy == 0) {
-    return complex64_t{metal::exp(x), y};
-  }
-  get_float_word(hx, x);
-  /* cexp(0 + I y) = cos(y) + I sin(y) */
-  if ((hx & 0x7fffffff) == 0) {
-    return complex64_t{metal::cos(y), metal::sin(y)};
-  }
-  if (hy >= 0x7f800000) {
-    if ((hx & 0x7fffffff) != 0x7f800000) {
-      /* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */
-      return complex64_t{y - y, y - y};
-    } else if (hx & 0x80000000) {
-      /* cexp(-Inf +- I Inf|NaN) = 0 + I 0 */
-      return complex64_t{0.0, 0.0};
-    } else {
-      /* cexp(+Inf +- I Inf|NaN) = Inf + I NaN */
-      return complex64_t{x, y - y};
-    }
-  }
-
-  if (hx >= exp_ovfl && hx <= cexp_ovfl) {
-    /*
-     * x is between 88.7 and 192, so we must scale to avoid
-     * overflow in expf(x).
-     */
-    return ldexp_cexpf(z, 0);
-  } else {
-    /*
-     * Cases covered here:
-     *  -  x < exp_ovfl and exp(x) won't overflow (common case)
-     *  -  x > cexp_ovfl, so exp(x) * s overflows for all s > 0
-     *  -  x = +-Inf (generated by exp())
-     *  -  x = NaN (spurious inexact exception from y)
-     */
-    exp_x = metal::exp(x);
-    return complex64_t{exp_x * metal::cos(y), exp_x * metal::sin(y)};
-  }
-}

mlx/backend/metal/kernels/layer_norm.metal

@@ -31,7 +31,6 @@ inline void threadgroup_sum(
   for (int i = 0; i < N; i++) {
     x[i] = simd_sum(x[i]);
   }
-  threadgroup_barrier(mem_flags::mem_threadgroup);
   if (simd_lane_id == 0) {
     for (int i = 0; i < N; i++) {
       xs[N * simd_group_id + i] = x[i];

mlx/backend/metal/kernels/quantized.h

@@ -643,14 +643,14 @@ struct QuantizedBlockLoader {
       return;
     }
 
-    if (reduction_dim == 1 && bi >= src_tile_dim.x) {
+    if (reduction_dim == 1 && bi >= src_tile_dim.y) {
       for (int i = 0; i < n_reads * pack_factor; i++) {
         dst[i] = T(0);
       }
       return;
     }
 
-    if (reduction_dim == 0 && bi >= src_tile_dim.y) {
+    if (reduction_dim == 0 && bi >= src_tile_dim.x) {
       for (int i = 0; i < n_reads * pack_factor; i++) {
         dst[i] = T(0);
       }

mlx/backend/metal/kernels/reduction/ops.h

@@ -164,15 +164,7 @@ struct Min {
   DEFINE_SIMD_REDUCE()
 
   template <typename T>
-  metal::enable_if_t<metal::is_integral_v<T>, T> simd_reduce_impl(T val) {
-    return simd_min(val);
-  }
-
-  template <typename T>
-  metal::enable_if_t<!metal::is_integral_v<T>, T> simd_reduce_impl(T val) {
-    if (simd_any(val != val)) {
-      return static_cast<T>(NAN);
-    }
+  T simd_reduce_impl(T val) {
     return simd_min(val);
   }
 
@@ -184,52 +176,17 @@ struct Min {
   }
 
   // Operator
-  template <typename T>
-  metal::enable_if_t<metal::is_integral_v<T>, T> operator()(T a, T b) {
+  U operator()(U a, U b) {
     return a < b ? a : b;
   }
-
-  template <typename T>
-  metal::enable_if_t<!metal::is_integral_v<T>, T> operator()(T a, T b) {
-    if (metal::isnan(a) || metal::isnan(b)) {
-      return static_cast<T>(NAN);
-    } else {
-      return a < b ? a : b;
-    }
-  }
-
-  template <>
-  complex64_t operator()(complex64_t a, complex64_t b) {
-    bool real_is_nan = metal::isnan(a.real) || metal::isnan(b.real);
-    bool imag_is_nan = metal::isnan(a.imag) || metal::isnan(b.imag);
-
-    if (!real_is_nan && !imag_is_nan) {
-      return a < b ? a : b;
-    } else if (real_is_nan && !imag_is_nan) {
-      return complex64_t(
-          static_cast<float>(NAN), a.imag < b.imag ? a.imag : b.imag);
-    } else if (!real_is_nan && imag_is_nan) {
-      return complex64_t(
-          a.real < b.real ? a.real : b.real, static_cast<float>(NAN));
-    } else {
-      return complex64_t(static_cast<float>(NAN), static_cast<float>(NAN));
-    }
-  };
 };
+
 template <typename U>
 struct Max {
   DEFINE_SIMD_REDUCE()
 
   template <typename T>
-  metal::enable_if_t<metal::is_integral_v<T>, T> simd_reduce_impl(T val) {
-    return simd_max(val);
-  }
-
-  template <typename T>
-  metal::enable_if_t<!metal::is_integral_v<T>, T> simd_reduce_impl(T val) {
-    if (simd_any(val != val)) {
-      return static_cast<T>(NAN);
-    }
+  T simd_reduce_impl(T val) {
     return simd_max(val);
   }
 
@@ -241,35 +198,7 @@ struct Max {
   }
 
   // Operator
-  template <typename T>
-  metal::enable_if_t<metal::is_integral_v<T>, T> operator()(T a, T b) {
+  U operator()(U a, U b) {
     return a > b ? a : b;
   }
-
-  template <typename T>
-  metal::enable_if_t<!metal::is_integral_v<T>, T> operator()(T a, T b) {
-    if (metal::isnan(a) || metal::isnan(b)) {
-      return static_cast<T>(NAN);
-    } else {
-      return a > b ? a : b;
-    }
-  }
-
-  template <>
-  complex64_t operator()(complex64_t a, complex64_t b) {
-    bool real_is_nan = metal::isnan(a.real) || metal::isnan(b.real);
-    bool imag_is_nan = metal::isnan(a.imag) || metal::isnan(b.imag);
-
-    if (!real_is_nan && !imag_is_nan) {
-      return a > b ? a : b;
-    } else if (real_is_nan && !imag_is_nan) {
-      return complex64_t(
-          static_cast<float>(NAN), a.imag > b.imag ? a.imag : b.imag);
-    } else if (!real_is_nan && imag_is_nan) {
-      return complex64_t(
-          a.real > b.real ? a.real : b.real, static_cast<float>(NAN));
-    } else {
-      return complex64_t(static_cast<float>(NAN), static_cast<float>(NAN));
-    }
-  }
 };

mlx/backend/metal/kernels/steel/gemm/kernels/steel_gemm_segmented.h

@@ -1,266 +0,0 @@
-// Copyright © 2025 Apple Inc.
-
-using namespace mlx::steel;
-
-constant bool segments_contiguous [[function_constant(199)]];
-constant bool align_M [[function_constant(200)]];
-constant bool align_N [[function_constant(201)]];
-
-template <
-    typename T,
-    int BM,
-    int BN,
-    int BK,
-    int WM,
-    int WN,
-    bool transpose_a,
-    bool transpose_b,
-    typename AccumType = float>
-[[kernel, max_total_threads_per_threadgroup(WM* WN * 32)]] void segmented_mm(
-    const device T* A [[buffer(0)]],
-    const device T* B [[buffer(1)]],
-    const device uint32_t* segments [[buffer(2)]],
-    device T* C [[buffer(3)]],
-    const constant GEMMParams* params [[buffer(4)]],
-    uint simd_lane_id [[thread_index_in_simdgroup]],
-    uint simd_group_id [[simdgroup_index_in_threadgroup]],
-    uint3 tid [[threadgroup_position_in_grid]]) {
-  using gemm_kernel = GEMMKernel<
-      T,
-      T,
-      BM,
-      BN,
-      BK,
-      WM,
-      WN,
-      transpose_a,
-      transpose_b,
-      true,
-      true,
-      AccumType>;
-
-  using loader_a_t = typename gemm_kernel::loader_a_t;
-  using loader_b_t = typename gemm_kernel::loader_b_t;
-  using mma_t = typename gemm_kernel::mma_t;
-
-  if (params->tiles_n <= static_cast<int>(tid.x) ||
-      params->tiles_m <= static_cast<int>(tid.y)) {
-    return;
-  }
-
-  // Prepare threadgroup memory
-  threadgroup T As[gemm_kernel::tgp_mem_size_a];
-  threadgroup T Bs[gemm_kernel::tgp_mem_size_b];
-
-  // Find the block in A, B, C
-  const int c_row = tid.y * BM;
-  const int c_col = tid.x * BN;
-  const size_t c_row_long = size_t(c_row);
-  const size_t c_col_long = size_t(c_col);
-
-  // Prepare threadgroup bounds
-  const short tgp_bm = align_M ? BM : short(min(BM, params->M - c_row));
-  const short tgp_bn = align_N ? BN : short(min(BN, params->N - c_col));
-
-  // Move the pointers to the output tile
-  A += transpose_a ? c_row_long : c_row_long * params->lda;
-  B += transpose_b ? c_col_long * params->ldb : c_col_long;
-  C += c_row_long * params->ldd + c_col_long;
-
-  // Move the pointers to the start of the segment
-  uint32_t k_start, k_end;
-  if (segments_contiguous) {
-    k_start = segments[2 * tid.z];
-    k_end = segments[2 * tid.z + 1];
-  } else {
-    // We accept either contiguous (above) or weird strides where the beginning
-    // of the next one is the previous one. Basically the last two strides are
-    // both 1!
-    k_start = segments[tid.z];
-    k_end = segments[tid.z + 1];
-  }
-  A += transpose_a ? k_start * params->lda : k_start;
-  B += transpose_b ? k_start : k_start * params->ldb;
-  C += tid.z * params->batch_stride_d;
-
-  // Prepare threadgroup mma operation
-  thread mma_t mma_op(simd_group_id, simd_lane_id);
-
-  // Prepare threadgroup loading operations
-  thread loader_a_t loader_a(A, params->lda, As, simd_group_id, simd_lane_id);
-  thread loader_b_t loader_b(B, params->ldb, Bs, simd_group_id, simd_lane_id);
-
-  // Matrix level alignment so only check K
-  if (align_M && align_N) {
-    uint32_t k = k_start + BK;
-    for (; k <= k_end; k += BK) {
-      threadgroup_barrier(mem_flags::mem_threadgroup);
-
-      // Load elements into threadgroup
-      loader_a.load_unsafe();
-      loader_b.load_unsafe();
-
-      threadgroup_barrier(mem_flags::mem_threadgroup);
-
-      // Multiply and accumulate threadgroup elements
-      mma_op.mma(As, Bs);
-
-      // Prepare for next iteration
-      loader_a.next();
-      loader_b.next();
-    }
-    short k_remain = BK - short(k - k_end);
-    const short2 tile_dims_A =
-        transpose_a ? short2(tgp_bm, k_remain) : short2(k_remain, tgp_bm);
-    const short2 tile_dims_B =
-        transpose_b ? short2(k_remain, tgp_bn) : short2(tgp_bn, k_remain);
-    if (k_remain > 0) {
-      threadgroup_barrier(mem_flags::mem_threadgroup);
-      loader_a.load_safe(tile_dims_A);
-      loader_b.load_safe(tile_dims_B);
-      threadgroup_barrier(mem_flags::mem_threadgroup);
-      mma_op.mma(As, Bs);
-    }
-    mma_op.store_result(C, params->ldd);
-  } else {
-    // Tile aligned do the same as above
-    if ((align_M || tgp_bm == BM) && (align_N || tgp_bn == BN)) {
-      uint32_t k = k_start + BK;
-      for (; k <= k_end; k += BK) {
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-
-        // Load elements into threadgroup
-        loader_a.load_unsafe();
-        loader_b.load_unsafe();
-
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-
-        // Multiply and accumulate threadgroup elements
-        mma_op.mma(As, Bs);
-
-        // Prepare for next iteration
-        loader_a.next();
-        loader_b.next();
-      }
-      short k_remain = BK - short(k - k_end);
-      const short2 tile_dims_A =
-          transpose_a ? short2(tgp_bm, k_remain) : short2(k_remain, tgp_bm);
-      const short2 tile_dims_B =
-          transpose_b ? short2(k_remain, tgp_bn) : short2(tgp_bn, k_remain);
-      if (k_remain > 0) {
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-        loader_a.load_safe(tile_dims_A);
-        loader_b.load_safe(tile_dims_B);
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-        mma_op.mma(As, Bs);
-      }
-      mma_op.store_result(C, params->ldd);
-    }
-
-    // Tile partially aligned check rows
-    else if (align_N || tgp_bn == BN) {
-      uint32_t k = k_start + BK;
-      for (; k <= k_end; k += BK) {
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-
-        // Load elements into threadgroup
-        loader_a.load_safe(
-            transpose_a ? short2(tgp_bm, BK) : short2(BK, tgp_bm));
-        loader_b.load_unsafe();
-
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-
-        // Multiply and accumulate threadgroup elements
-        mma_op.mma(As, Bs);
-
-        // Prepare for next iteration
-        loader_a.next();
-        loader_b.next();
-      }
-      short k_remain = BK - short(k - k_end);
-      const short2 tile_dims_A =
-          transpose_a ? short2(tgp_bm, k_remain) : short2(k_remain, tgp_bm);
-      const short2 tile_dims_B =
-          transpose_b ? short2(k_remain, tgp_bn) : short2(tgp_bn, k_remain);
-      if (k_remain > 0) {
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-        loader_a.load_safe(tile_dims_A);
-        loader_b.load_safe(tile_dims_B);
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-        mma_op.mma(As, Bs);
-      }
-      mma_op.store_result_safe(C, params->ldd, short2(tgp_bn, tgp_bm));
-    }
-
-    // Tile partially aligned check cols
-    else if (align_M || tgp_bm == BM) {
-      uint32_t k = k_start + BK;
-      for (; k <= k_end; k += BK) {
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-
-        // Load elements into threadgroup
-        loader_a.load_unsafe();
-        loader_b.load_safe(
-            transpose_b ? short2(BK, tgp_bn) : short2(tgp_bn, BK));
-
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-
-        // Multiply and accumulate threadgroup elements
-        mma_op.mma(As, Bs);
-
-        // Prepare for next iteration
-        loader_a.next();
-        loader_b.next();
-      }
-      short k_remain = BK - short(k - k_end);
-      const short2 tile_dims_A =
-          transpose_a ? short2(tgp_bm, k_remain) : short2(k_remain, tgp_bm);
-      const short2 tile_dims_B =
-          transpose_b ? short2(k_remain, tgp_bn) : short2(tgp_bn, k_remain);
-      if (k_remain > 0) {
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-        loader_a.load_safe(tile_dims_A);
-        loader_b.load_safe(tile_dims_B);
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-        mma_op.mma(As, Bs);
-      }
-      mma_op.store_result_safe(C, params->ldd, short2(tgp_bn, tgp_bm));
-    }
-
-    // Nothing aligned so check both rows and cols
-    else {
-      uint32_t k = k_start + BK;
-      for (; k <= k_end; k += BK) {
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-
-        // Load elements into threadgroup
-        loader_a.load_safe(
-            transpose_a ? short2(tgp_bm, BK) : short2(BK, tgp_bm));
-        loader_b.load_safe(
-            transpose_b ? short2(BK, tgp_bn) : short2(tgp_bn, BK));
-
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-
-        // Multiply and accumulate threadgroup elements
-        mma_op.mma(As, Bs);
-
-        // Prepare for next iteration
-        loader_a.next();
-        loader_b.next();
-      }
-      short k_remain = BK - short(k - k_end);
-      const short2 tile_dims_A =
-          transpose_a ? short2(tgp_bm, k_remain) : short2(k_remain, tgp_bm);
-      const short2 tile_dims_B =
-          transpose_b ? short2(k_remain, tgp_bn) : short2(tgp_bn, k_remain);
-      if (k_remain > 0) {
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-        loader_a.load_safe(tile_dims_A);
-        loader_b.load_safe(tile_dims_B);
-        threadgroup_barrier(mem_flags::mem_threadgroup);
-        mma_op.mma(As, Bs);
-      }
-      mma_op.store_result_safe(C, params->ldd, short2(tgp_bn, tgp_bm));
-    }
-  }
-}

mlx/backend/metal/kernels/steel/gemm/kernels/steel_gemm_segmented.metal

@@ -1,43 +0,0 @@
-// Copyright © 2024 Apple Inc.
-
-// clang-format off
-#include "mlx/backend/metal/kernels/utils.h"
-#include "mlx/backend/metal/kernels/steel/gemm/gemm.h"
-#include "mlx/backend/metal/kernels/steel/gemm/kernels/steel_gemm_segmented.h"
-
-#define instantiate_segmented_mm(tname, trans_a, trans_b, iname, itype, oname, otype, bm, bn, bk, wm, wn) \
-  instantiate_kernel(                                                         \
-      "steel_segmented_mm_" #tname "_" #iname "_" #oname "_bm" #bm "_bn" #bn  \
-      "_bk" #bk "_wm" #wm "_wn" #wn,                                          \
-      segmented_mm,                                                           \
-      itype,                                                                  \
-      bm,                                                                     \
-      bn,                                                                     \
-      bk,                                                                     \
-      wm,                                                                     \
-      wn,                                                                     \
-      trans_a,                                                                \
-      trans_b,                                                                \
-      float)
-
-#define instantiate_segmented_mm_transpose_helper(iname, itype, oname, otype, bm, bn, bk, wm, wn) \
-  instantiate_segmented_mm(nn, false, false, iname, itype, oname, otype, bm, bn, bk, wm, wn)      \
-  instantiate_segmented_mm(nt, false, true , iname, itype, oname, otype, bm, bn, bk, wm, wn)      \
-  instantiate_segmented_mm(tn, true , false, iname, itype, oname, otype, bm, bn, bk, wm, wn)      \
-  instantiate_segmented_mm(tt, true , true , iname, itype, oname, otype, bm, bn, bk, wm, wn)
-
-#define instantiate_segmented_mm_shapes_helper(iname, itype, oname, otype)                 \
-  instantiate_segmented_mm_transpose_helper(iname, itype, oname, otype, 64, 64, 16, 2, 2)  \
-  instantiate_segmented_mm_transpose_helper(iname, itype, oname, otype, 64, 64, 16, 1, 2)  \
-  instantiate_segmented_mm_transpose_helper(iname, itype, oname, otype, 64, 32, 32, 2, 2)  \
-  instantiate_segmented_mm_transpose_helper(iname, itype, oname, otype, 32, 64, 16, 1, 2)  \
-  instantiate_segmented_mm_transpose_helper(iname, itype, oname, otype, 32, 32, 16, 2, 2)
-// clang-format on
-
-instantiate_segmented_mm_shapes_helper(float16, half, float16, half);
-instantiate_segmented_mm_shapes_helper(
-    bfloat16,
-    bfloat16_t,
-    bfloat16,
-    bfloat16_t);
-instantiate_segmented_mm_shapes_helper(float32, float, float32, float);

mlx/backend/metal/kernels/unary_ops.h

@@ -5,7 +5,6 @@
 #include <metal_integer>
 #include <metal_math>
 
-#include "mlx/backend/metal/kernels/cexpf.h"
 #include "mlx/backend/metal/kernels/erf.h"
 #include "mlx/backend/metal/kernels/expm1f.h"
 
@@ -179,7 +178,8 @@ struct Exp {
     return metal::precise::exp(x);
   };
   complex64_t operator()(complex64_t x) {
-    return cexpf(x);
+    auto m = metal::precise::exp(x.real);
+    return {m * metal::precise::cos(x.imag), m * metal::precise::sin(x.imag)};
   }
 };
 

mlx/backend/metal/matmul.cpp

@@ -1864,166 +1864,4 @@ void GatherMM::eval_gpu(const std::vector<array>& inputs, array& out) {
   gather_mm(a, b, lhs_indices, rhs_indices, out, M, N, K, d, s);
 }
 
-void segmented_mm(
-    const array& a_,
-    const array& b_,
-    const array& segments_,
-    array& out,
-    int M,
-    int N,
-    int K,
-    metal::Device& d,
-    const Stream& s) {
-  auto check_segments_layout = [&d, &s](const array& x) {
-    // Contiguous so return early
-    if (x.flags().row_contiguous) {
-      return std::make_tuple(true, x);
-    }
-
-    bool rc = true;
-    for (int i = 0; i < x.ndim() - 2; i++) {
-      rc &=
-          (x.strides(i + 1) * x.shape(i) == x.strides(i)) || (x.shape(i) == 1);
-    }
-    rc &= x.strides(x.ndim() - 1) == 1;
-    if (x.ndim() > 1) {
-      rc &= x.strides(x.ndim() - 2) == 1;
-    }
-
-    if (rc) {
-      return std::make_tuple(false, x);
-    }
-
-    array x_copy(x.shape(), x.dtype(), nullptr, {});
-    copy_gpu(x, x_copy, CopyType::General, s);
-    d.add_temporary(x_copy, s.index);
-    return std::make_tuple(true, x_copy);
-  };
-
-  // Copy if needed
-  std::vector<array> copies;
-  auto [transpose_a, lda, a] = check_transpose(copies, s, a_, false);
-  auto [transpose_b, ldb, b] = check_transpose(copies, s, b_, false);
-  auto [segments_contiguous, segments] = check_segments_layout(segments_);
-  d.add_temporaries(std::move(copies), s.index);
-
-  // Determine dispatch kernel
-  int bm = 64, bn = 64, bk = 16;
-  int wm = 2, wn = 2;
-  size_t batch_size_out = out.size() / M / N;
-
-  char devc = d.get_architecture().back();
-  GEMM_TPARAM_MACRO(devc)
-
-  const bool align_M = (M % bm) == 0;
-  const bool align_N = (N % bn) == 0;
-
-  // Define the kernel name
-  std::string base_name;
-  base_name.reserve(128);
-  concatenate(
-      base_name,
-      "steel_segmented_mm_",
-      transpose_a ? 't' : 'n',
-      transpose_b ? 't' : 'n',
-      "_",
-      type_to_name(a),
-      "_",
-      type_to_name(out),
-      "_bm",
-      bm,
-      "_bn",
-      bn,
-      "_bk",
-      bk,
-      "_wm",
-      wm,
-      "_wn",
-      wn);
-
-  metal::MTLFCList func_consts = {
-      {&segments_contiguous, MTL::DataType::DataTypeBool, 199},
-      {&align_M, MTL::DataType::DataTypeBool, 200},
-      {&align_N, MTL::DataType::DataTypeBool, 201},
-  };
-
-  // And the kernel hash that includes the function constants
-  std::string hash_name;
-  hash_name.reserve(128);
-  concatenate(
-      hash_name,
-      base_name,
-      "_segments_contiguous_",
-      segments_contiguous ? 't' : 'n',
-      "_align_M_",
-      align_M ? 't' : 'n',
-      "_align_N_",
-      align_N ? 't' : 'n');
-
-  // Get and set the kernel
-  auto& compute_encoder = d.get_command_encoder(s.index);
-  auto kernel = get_steel_gemm_segmented_kernel(
-      d,
-      base_name,
-      hash_name,
-      func_consts,
-      out,
-      transpose_a,
-      transpose_b,
-      bm,
-      bn,
-      bk,
-      wm,
-      wn);
-  compute_encoder.set_compute_pipeline_state(kernel);
-
-  // Prepare the matmul params
-  steel::GEMMParams params{
-      /* const int M = */ M,
-      /* const int N = */ N,
-      /* const int K = */ K,
-      /* const int lda = */ static_cast<int>(lda),
-      /* const int ldb = */ static_cast<int>(ldb),
-      /* const int ldd = */ N,
-      /* const int tiles_n = */ (N + bn - 1) / bn,
-      /* const int tiles_m = */ (M + bm - 1) / bm,
-      /* const int64_t batch_stride_a = */ 0,
-      /* const int64_t batch_stride_b = */ 0,
-      /* const int64_t batch_stride_d = */ M * N,
-      /* const int swizzle_log = */ 0,
-      /* const int gemm_k_iterations_aligned = */ 0,
-      /* const int batch_ndim = */ 0};
-
-  // Prepare the grid
-  MTL::Size group_dims = MTL::Size(32, wn, wm);
-  MTL::Size grid_dims =
-      MTL::Size(params.tiles_n, params.tiles_m, batch_size_out);
-
-  // Launch kernel
-  compute_encoder.set_input_array(a, 0);
-  compute_encoder.set_input_array(b, 1);
-  compute_encoder.set_input_array(segments, 2);
-  compute_encoder.set_output_array(out, 3);
-  compute_encoder.set_bytes(params, 4);
-  compute_encoder.dispatch_threadgroups(grid_dims, group_dims);
-}
-
-void SegmentedMM::eval_gpu(const std::vector<array>& inputs, array& out) {
-  auto& s = stream();
-  auto& d = metal::device(s.device);
-
-  auto& a = inputs[0];
-  auto& b = inputs[1];
-  auto& segments = inputs[2];
-
-  out.set_data(allocator::malloc(out.nbytes()));
-
-  // Extract shapes from inputs.
-  int M = a.shape(-2);
-  int N = b.shape(-1);
-  int K = a.shape(-1);
-
-  segmented_mm(a, b, segments, out, M, N, K, d, s);
-}
-
 } // namespace mlx::core

mlx/backend/metal/nojit_kernels.cpp

@@ -210,22 +210,6 @@ MTL::ComputePipelineState* get_steel_gemm_gather_kernel(
   return d.get_kernel(kernel_name, hash_name, func_consts);
 }
 
-MTL::ComputePipelineState* get_steel_gemm_segmented_kernel(
-    metal::Device& d,
-    const std::string& kernel_name,
-    const std::string& hash_name,
-    const metal::MTLFCList& func_consts,
-    const array&,
-    bool,
-    bool,
-    int,
-    int,
-    int,
-    int,
-    int) {
-  return d.get_kernel(kernel_name, hash_name, func_consts);
-}
-
 MTL::ComputePipelineState* get_gemv_masked_kernel(
     metal::Device& d,
     const std::string& kernel_name,

mlx/backend/no_cpu/primitives.cpp

@@ -105,7 +105,6 @@ NO_CPU(Scan)
 NO_CPU(Scatter)
 NO_CPU(ScatterAxis)
 NO_CPU(Select)
-NO_CPU(SegmentedMM)
 NO_CPU(Sigmoid)
 NO_CPU(Sign)
 NO_CPU(Sin)

mlx/backend/no_gpu/primitives.cpp

@@ -121,7 +121,6 @@ NO_GPU(Scan)
 NO_GPU(Scatter)
 NO_GPU(ScatterAxis)
 NO_GPU(Select)
-NO_GPU(SegmentedMM)
 NO_GPU(Sigmoid)
 NO_GPU(Sign)
 NO_GPU(Sin)

mlx/backend/rocm/CMakeLists.txt

@@ -0,0 +1,85 @@
+# Filename rules in ROCm backend:
+#
+# * Use .hip/.hpp if code contains device code, and .cpp/.h if not.
+# * Device-only code should be put in device/ subdir.
+# * Files in device/ subdir should not include files outside.
+target_sources(
+  mlx
+  PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/allocator.cpp
+          ${CMAKE_CURRENT_SOURCE_DIR}/arg_reduce.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/binary.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/compiled.cpp
+          ${CMAKE_CURRENT_SOURCE_DIR}/copy.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/device.cpp
+          ${CMAKE_CURRENT_SOURCE_DIR}/eval.cpp
+          ${CMAKE_CURRENT_SOURCE_DIR}/event.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/fence.cpp
+          ${CMAKE_CURRENT_SOURCE_DIR}/indexing.cpp
+          ${CMAKE_CURRENT_SOURCE_DIR}/kernel_utils.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/matmul.cpp
+          ${CMAKE_CURRENT_SOURCE_DIR}/layer_norm.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/logsumexp.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/primitives.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/random.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/reduce.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/rms_norm.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/rope.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/rocm.cpp
+          ${CMAKE_CURRENT_SOURCE_DIR}/slicing.cpp
+          ${CMAKE_CURRENT_SOURCE_DIR}/softmax.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/sort.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/ternary.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/unary.hip
+          ${CMAKE_CURRENT_SOURCE_DIR}/utils.cpp
+          ${CMAKE_CURRENT_SOURCE_DIR}/worker.cpp)
+
+target_compile_definitions(mlx PRIVATE MLX_USE_ROCM)
+
+# Embed kernel sources in binary for JIT compilation.
+file(
+  GLOB MLX_JIT_SOURCES
+  RELATIVE ${CMAKE_CURRENT_SOURCE_DIR}
+  "${CMAKE_CURRENT_SOURCE_DIR}/device/*.h"
+  "${CMAKE_CURRENT_SOURCE_DIR}/device/*.hpp")
+string(JOIN ":" MLX_JIT_SOURCES_ARG ${MLX_JIT_SOURCES})
+add_custom_command(
+  OUTPUT gen/rocm_jit_sources.h
+  COMMAND
+    ${CMAKE_COMMAND} -DMLX_SOURCE_ROOT=${CMAKE_CURRENT_SOURCE_DIR}
+    -DMLX_JIT_SOURCES=${MLX_JIT_SOURCES_ARG} -P
+    "${CMAKE_CURRENT_SOURCE_DIR}/bin2h.cmake"
+  DEPENDS bin2h.cmake ${MLX_JIT_SOURCES})
+add_custom_target(rocm_jit_sources DEPENDS gen/rocm_jit_sources.h)
+add_dependencies(mlx rocm_jit_sources)
+target_include_directories(mlx PRIVATE "${CMAKE_CURRENT_BINARY_DIR}/gen")
+
+# Find ROCm installation
+find_package(hip REQUIRED)
+find_package(rocblas REQUIRED)
+
+# Link with ROCm libraries
+target_link_libraries(mlx PRIVATE hip::device roc::rocblas)
+
+# Set GPU architectures for ROCm Common ROCm architectures: gfx900, gfx906,
+# gfx908, gfx90a, gfx1030, gfx1100
+set(MLX_ROCM_ARCHITECTURES
+    "gfx900;gfx906;gfx908;gfx90a;gfx1030;gfx1100"
+    CACHE STRING "ROCm GPU architectures")
+message(STATUS "ROCm GPU architectures: ${MLX_ROCM_ARCHITECTURES}")
+
+# Set GPU targets for HIP compilation
+set_property(TARGET mlx PROPERTY HIP_ARCHITECTURES "${MLX_ROCM_ARCHITECTURES}")
+
+# Enable HIP language support
+enable_language(HIP)
+
+# Set HIP compiler flags
+target_compile_options(
+  mlx
+  PRIVATE "$<$<COMPILE_LANGUAGE:HIP>:-fgpu-rdc>"
+          "$<$<COMPILE_LANGUAGE:HIP>:-Xcompiler=-Wall>"
+          "$<$<COMPILE_LANGUAGE:HIP>:-Xcompiler=-Wextra>")
+
+# Add ROCm include directories
+target_include_directories(mlx PRIVATE ${hip_INCLUDE_DIRS})
+target_include_directories(mlx PRIVATE ${rocblas_INCLUDE_DIRS})

mlx/backend/rocm/allocator.cpp

@@ -0,0 +1,206 @@
+// Copyright © 2025 Apple Inc.
+
+#include "mlx/backend/rocm/allocator.h"
+#include "mlx/backend/rocm/utils.h"
+#include "mlx/backend/rocm/worker.h"
+
+#include <fmt/format.h>
+#include <hip/hip_runtime.h>
+#include <unistd.h>
+
+#include <cassert>
+
+namespace mlx::core {
+
+namespace rocm {
+
+RocmAllocator::RocmAllocator()
+    : buffer_cache_(
+          getpagesize(),
+          [](RocmBuffer* buf) { return buf->size; },
+          [this](RocmBuffer* buf) {
+            rocm_free(buf->data);
+            delete buf;
+          }) {
+  // TODO: Set memory limit for multi-device.
+  size_t free, total;
+  CHECK_HIP_ERROR(hipMemGetInfo(&free, &total));
+  memory_limit_ = total * 0.8;
+  max_pool_size_ = memory_limit_;
+}
+
+Buffer RocmAllocator::malloc(size_t size) {
+  // Find available buffer from cache.
+  std::unique_lock lock(mutex_);
+  RocmBuffer* buf = buffer_cache_.reuse_from_cache(size);
+  if (!buf) {
+    // If we have a lot of memory pressure or are over the maximum cache size,
+    // try to reclaim memory from the cache.
+    size_t mem_required = get_active_memory() + get_cache_memory() + size;
+    if (mem_required >= memory_limit_) {
+      buffer_cache_.release_cached_buffers(mem_required - memory_limit_);
+    }
+
+    lock.unlock();
+    buf = new RocmBuffer{nullptr, size};
+    hipError_t err = hipMallocManaged(&buf->data, size);
+    if (err != hipSuccess && err != hipErrorMemoryAllocation) {
+      throw std::runtime_error(
+          fmt::format("hipMallocManaged failed: {}.", hipGetErrorString(err)));
+    }
+    lock.lock();
+  }
+  active_memory_ += size;
+  peak_memory_ = std::max(active_memory_, peak_memory_);
+
+  // Maintain the cache below the requested limit.
+  if (get_cache_memory() > max_pool_size_) {
+    buffer_cache_.release_cached_buffers(get_cache_memory() - max_pool_size_);
+  }
+
+  return Buffer{buf};
+}
+
+void RocmAllocator::free(Buffer buffer) {
+  auto* buf = static_cast<RocmBuffer*>(buffer.ptr());
+  if (!buf) {
+    return;
+  }
+
+  std::unique_lock lock(mutex_);
+  active_memory_ -= buf->size;
+  if (get_cache_memory() < max_pool_size_) {
+    buffer_cache_.recycle_to_cache(buf);
+  } else {
+    lock.unlock();
+    rocm_free(buf->data);
+    delete buf;
+  }
+}
+
+size_t RocmAllocator::size(Buffer buffer) const {
+  auto* buf = static_cast<RocmBuffer*>(buffer.ptr());
+  if (!buf) {
+    return 0;
+  }
+  return buf->size;
+}
+
+void RocmAllocator::register_this_thread() {
+  std::lock_guard lock(worker_mutex_);
+  allowed_threads_.insert(std::this_thread::get_id());
+}
+
+void RocmAllocator::rocm_free(void* buf) {
+  // If rocm_free() is called from a unregistered thread, reschedule the call to
+  // worker.
+  {
+    std::lock_guard lock(worker_mutex_);
+    if (allowed_threads_.count(std::this_thread::get_id()) == 0) {
+      if (!worker_) {
+        worker_.reset(new Worker);
+      }
+      worker_->add_task([this, buf]() { this->rocm_free(buf); });
+      worker_->end_batch();
+      worker_->commit();
+      return;
+    }
+  }
+
+  hipFree(buf);
+}
+
+size_t RocmAllocator::get_active_memory() const {
+  return active_memory_;
+}
+
+size_t RocmAllocator::get_peak_memory() const {
+  return peak_memory_;
+}
+
+void RocmAllocator::reset_peak_memory() {
+  std::lock_guard lock(mutex_);
+  peak_memory_ = 0;
+}
+
+size_t RocmAllocator::get_memory_limit() {
+  return memory_limit_;
+}
+
+size_t RocmAllocator::set_memory_limit(size_t limit) {
+  std::lock_guard lock(mutex_);
+  std::swap(limit, memory_limit_);
+  return limit;
+}
+
+size_t RocmAllocator::get_cache_memory() const {
+  return buffer_cache_.cache_size();
+}
+
+size_t RocmAllocator::set_cache_limit(size_t limit) {
+  std::lock_guard lk(mutex_);
+  std::swap(limit, max_pool_size_);
+  return limit;
+}
+
+void RocmAllocator::clear_cache() {
+  std::lock_guard lk(mutex_);
+  buffer_cache_.clear();
+}
+
+RocmAllocator& allocator() {
+  // By creating the |allocator_| on heap, the destructor of RocmAllocator
+  // will not be called on exit and buffers in the cache will be leaked. This
+  // can save some time at program exit.
+  static RocmAllocator* allocator_ = new RocmAllocator;
+  return *allocator_;
+}
+
+} // namespace rocm
+
+namespace allocator {
+
+Allocator& allocator() {
+  return rocm::allocator();
+}
+
+void* Buffer::raw_ptr() {
+  if (!ptr_) {
+    return nullptr;
+  }
+  return static_cast<rocm::RocmBuffer*>(ptr_)->data;
+}
+
+} // namespace allocator
+
+size_t get_active_memory() {
+  return rocm::allocator().get_active_memory();
+}
+size_t get_peak_memory() {
+  return rocm::allocator().get_peak_memory();
+}
+void reset_peak_memory() {
+  return rocm::allocator().reset_peak_memory();
+}
+size_t set_memory_limit(size_t limit) {
+  return rocm::allocator().set_memory_limit(limit);
+}
+size_t get_memory_limit() {
+  return rocm::allocator().get_memory_limit();
+}
+size_t get_cache_memory() {
+  return rocm::allocator().get_cache_memory();
+}
+size_t set_cache_limit(size_t limit) {
+  return rocm::allocator().set_cache_limit(limit);
+}
+void clear_cache() {
+  rocm::allocator().clear_cache();
+}
+
+// Not supported in ROCm.
+size_t set_wired_limit(size_t) {
+  return 0;
+}
+
+} // namespace mlx::core

mlx/backend/rocm/allocator.h

@@ -0,0 +1,67 @@
+// Copyright © 2025 Apple Inc.
+
+#pragma once
+
+#include "mlx/allocator.h"
+#include "mlx/backend/common/buffer_cache.h"
+
+#include <mutex>
+#include <set>
+#include <thread>
+#include <utility>
+
+namespace mlx::core::rocm {
+
+class Worker;
+
+using allocator::Buffer;
+
+// Stores ROCm-managed unified memory.
+struct RocmBuffer {
+  void* data;
+  size_t size;
+};
+
+class RocmAllocator : public allocator::Allocator {
+ public:
+  Buffer malloc(size_t size) override;
+  void free(Buffer buffer) override;
+  size_t size(Buffer buffer) const override;
+
+  // Register current thread as safe to free buffers.
+  // In ROCm freeing a buffer implicitly synchronizes stream, and for threads
+  // that may be waited by gpu stream (for example cpu stream threads), freeing
+  // buffers there would result in dead lock.
+  void register_this_thread();
+
+  // Call hipFree in the safe thread.
+  void rocm_free(void* buf);
+
+  size_t get_active_memory() const;
+  size_t get_peak_memory() const;
+  void reset_peak_memory();
+  size_t get_memory_limit();
+  size_t set_memory_limit(size_t limit);
+  size_t get_cache_memory() const;
+  size_t set_cache_limit(size_t limit);
+  void clear_cache();
+
+ private:
+  RocmAllocator();
+  friend RocmAllocator& allocator();
+
+  std::mutex worker_mutex_;
+  std::unique_ptr<Worker> worker_;
+  std::set<std::thread::id> allowed_threads_;
+
+  std::mutex mutex_;
+  size_t memory_limit_;
+  size_t max_pool_size_;
+  BufferCache<RocmBuffer> buffer_cache_;
+  size_t active_memory_{0};
+  size_t peak_memory_{0};
+};
+
+RocmAllocator& allocator();
+
+} // namespace mlx::core::rocm

mlx/backend/rocm/arg_reduce.hip

@@ -0,0 +1,28 @@
+// Copyright © 2025 Apple Inc.
+
+#include <hip/hip_runtime.h>
+
+namespace mlx::core::rocm {
+
+__global__ void argmax_kernel(float* input, int* output, int n) {
+  int idx = blockIdx.x * blockDim.x + threadIdx.x;
+  
+  // Simple argmax placeholder
+  if (idx == 0) {
+    int max_idx = 0;
+    float max_val = input[0];
+    for (int i = 1; i < n; i++) {
+      if (input[i] > max_val) {
+        max_val = input[i];
+        max_idx = i;
+      }
+    }
+    output[0] = max_idx;
+  }
+}
+
+void launch_argmax(float* input, int* output, int n, hipStream_t stream) {
+  hipLaunchKernelGGL(argmax_kernel, dim3(1), dim3(1), 0, stream, input, output, n);
+}
+
+} // namespace mlx::core::rocm 

mlx/backend/rocm/bin2h.cmake

@@ -0,0 +1,47 @@
+# Copyright © 2025 Apple Inc.
+
+# Script to embed kernel source files as header for JIT compilation
+
+set(MLX_OUTPUT_FILE "${CMAKE_CURRENT_BINARY_DIR}/gen/rocm_jit_sources.h")
+set(MLX_KERNEL_HEADER
+    "#pragma once\n\n#include <unordered_map>\n#include <string>\n\nnamespace mlx::core::rocm {\n\n"
+)
+set(MLX_KERNEL_FOOTER "\n} // namespace mlx::core::rocm\n")
+
+# Create output directory
+get_filename_component(MLX_OUTPUT_DIR ${MLX_OUTPUT_FILE} DIRECTORY)
+file(MAKE_DIRECTORY ${MLX_OUTPUT_DIR})
+
+# Write header
+file(WRITE ${MLX_OUTPUT_FILE} ${MLX_KERNEL_HEADER})
+
+# Process JIT sources
+string(REPLACE ":" ";" MLX_JIT_SOURCES_LIST ${MLX_JIT_SOURCES})
+
+set(MLX_SOURCE_MAP
+    "const std::unordered_map<std::string, std::string> kernel_sources = {\n")
+
+foreach(source IN LISTS MLX_JIT_SOURCES_LIST)
+  set(source_file "${MLX_SOURCE_ROOT}/${source}")
+  if(EXISTS ${source_file})
+    # Read source file
+    file(READ ${source_file} source_content)
+
+    # Escape content for C++ string literal
+    string(REPLACE "\\" "\\\\" source_content "${source_content}")
+    string(REPLACE "\"" "\\\"" source_content "${source_content}")
+    string(REPLACE "\n" "\\n\"\n\"" source_content "${source_content}")
+
+    # Add to map
+    set(MLX_SOURCE_MAP
+        "${MLX_SOURCE_MAP}  {\"${source}\", \"${source_content}\"},\n")
+  endif()
+endforeach()
+
+set(MLX_SOURCE_MAP "${MLX_SOURCE_MAP}};\n")
+
+# Write source map
+file(APPEND ${MLX_OUTPUT_FILE} ${MLX_SOURCE_MAP})
+
+# Write footer
+file(APPEND ${MLX_OUTPUT_FILE} ${MLX_KERNEL_FOOTER})

mlx/backend/rocm/binary.hip

@@ -0,0 +1,312 @@
+// Copyright © 2025 Apple Inc.
+
+#include "mlx/backend/common/binary.h"
+#include "mlx/backend/rocm/device.h"
+#include "mlx/backend/rocm/device/binary_ops.hpp"
+#include "mlx/backend/rocm/kernel_utils.hpp"
+#include "mlx/dtype_utils.h"
+#include "mlx/primitives.h"
+
+#include <hip/hip_cooperative_groups.h>
+
+namespace mlx::core {
+
+namespace rocm {
+
+namespace cg = cooperative_groups;
+
+template <typename Op, typename In, typename Out, typename IdxT>
+__global__ void binary_ss(const In* a, const In* b, Out* out, IdxT size) {
+  IdxT index = cg::this_grid().thread_rank();
+  if (index < size) {
+    out[index] = Op{}(a[0], b[0]);
+  }
+}
+
+template <typename Op, typename In, typename Out, typename IdxT>
+__global__ void binary_sv(const In* a, const In* b, Out* out, IdxT size) {
+  IdxT index = cg::this_grid().thread_rank();
+  if (index < size) {
+    out[index] = Op{}(a[0], b[index]);
+  }
+}
+
+template <typename Op, typename In, typename Out, typename IdxT>
+__global__ void binary_vs(const In* a, const In* b, Out* out, IdxT size) {
+  IdxT index = cg::this_grid().thread_rank();
+  if (index < size) {
+    out[index] = Op{}(a[index], b[0]);
+  }
+}
+
+template <typename Op, typename In, typename Out, typename IdxT>
+__global__ void binary_vv(const In* a, const In* b, Out* out, IdxT size) {
+  IdxT index = cg::this_grid().thread_rank();
+  if (index < size) {
+    out[index] = Op{}(a[index], b[index]);
+  }
+}
+
+template <typename Op, typename In, typename Out, typename IdxT, int NDIM>
+__global__ void binary_g_nd(
+    const In* a,
+    const In* b,
+    Out* out,
+    IdxT size,
+    const hip_array<int32_t, NDIM> shape,
+    const hip_array<int64_t, NDIM> a_strides,
+    const hip_array<int64_t, NDIM> b_strides) {
+  IdxT index = cg::this_grid().thread_rank();
+  if (index < size) {
+    auto [a_idx, b_idx] = elem_to_loc_nd<NDIM>(
+        index, shape.data(), a_strides.data(), b_strides.data());
+    out[index] = Op{}(a[a_idx], b[b_idx]);
+  }
+}
+
+template <typename Op, typename In, typename Out, typename IdxT>
+__global__ void binary_g(
+    const In* a,
+    const In* b,
+    Out* out,
+    IdxT size,
+    const hip_array<int32_t, MAX_DIMS> shape,
+    const hip_array<int64_t, MAX_DIMS> a_strides,
+    const hip_array<int64_t, MAX_DIMS> b_strides,
+    int ndim) {
+  IdxT index = cg::this_grid().thread_rank();
+  if (index < size) {
+    auto [a_idx, b_idx] = elem_to_loc_4d(
+        index, shape.data(), a_strides.data(), b_strides.data(), ndim);
+    out[index] = Op{}(a[a_idx], b[b_idx]);
+  }
+}
+
+// Binary operation support checking
+template <typename Op, typename In, typename Out>
+constexpr bool supports_binary_op() {
+  if (std::is_same_v<Op, Add> || std::is_same_v<Op, Divide> ||
+      std::is_same_v<Op, Maximum> || std::is_same_v<Op, Minimum> ||
+      std::is_same_v<Op, Multiply> || std::is_same_v<Op, Subtract> ||
+      std::is_same_v<Op, Power> || std::is_same_v<Op, Remainder>) {
+    return std::is_same_v<In, Out>;
+  }
+  if (std::is_same_v<Op, Equal> || std::is_same_v<Op, Greater> ||
+      std::is_same_v<Op, GreaterEqual> || std::is_same_v<Op, Less> ||
+      std::is_same_v<Op, LessEqual> || std::is_same_v<Op, NotEqual>) {
+    return std::is_same_v<Out, bool>;
+  }
+  if (std::is_same_v<Op, LogicalAnd> || std::is_same_v<Op, LogicalOr>) {
+    return std::is_same_v<Out, bool> && std::is_same_v<In, bool>;
+  }
+  if (std::is_same_v<Op, NaNEqual>) {
+    return std::is_same_v<Out, bool> && is_inexact_v<In>;
+  }
+  if (std::is_same_v<Op, LogAddExp>) {
+    return std::is_same_v<In, Out> && is_inexact_v<In>;
+  }
+  if (std::is_same_v<Op, ArcTan2>) {
+    return std::is_same_v<In, Out> && is_floating_v<In>;
+  }
+  if (std::is_same_v<Op, BitwiseAnd> || std::is_same_v<Op, BitwiseOr> ||
+      std::is_same_v<Op, BitwiseXor>) {
+    return std::is_same_v<In, Out> && std::is_integral_v<In>;
+  }
+  if (std::is_same_v<Op, LeftShift> || std::is_same_v<Op, RightShift>) {
+    return std::is_same_v<In, Out> && std::is_integral_v<In> &&
+        !std::is_same_v<In, bool>;
+  }
+  return false;
+}
+
+} // namespace rocm
+
+template <typename Op>
+void binary_op_gpu_inplace(
+    const std::vector<array>& inputs,
+    std::vector<array>& outputs,
+    std::string_view op,
+    const Stream& s) {
+  assert(inputs.size() > 1);
+  const auto& a = inputs[0];
+  const auto& b = inputs[1];
+  auto& out = outputs[0];
+  if (out.size() == 0) {
+    return;
+  }
+
+  auto& encoder = rocm::get_command_encoder(s);
+  encoder.set_input_array(a);
+  encoder.set_input_array(b);
+  encoder.set_output_array(out);
+  encoder.launch_kernel([&](hipStream_t stream) {
+    MLX_SWITCH_ALL_TYPES(a.dtype(), CTYPE_IN, {
+      MLX_SWITCH_ALL_TYPES(out.dtype(), CTYPE_OUT, {
+        if constexpr (rocm::supports_binary_op<Op, CTYPE_IN, CTYPE_OUT>()) {
+          using InType = hip_type_t<CTYPE_IN>;
+          using OutType = hip_type_t<CTYPE_OUT>;
+
+          auto bopt = get_binary_op_type(a, b);
+          if (bopt == BinaryOpType::General) {
+            auto [shape, strides] = collapse_contiguous_dims(a, b, out);
+            auto& a_strides = strides[0];
+            auto& b_strides = strides[1];
+            bool large = a.data_size() > INT32_MAX ||
+                b.data_size() > INT32_MAX || out.data_size() > INT32_MAX;
+            MLX_SWITCH_BOOL(large, LARGE, {
+              using IdxT = std::conditional_t<LARGE, int64_t, int32_t>;
+              int ndim = shape.size();
+              if (ndim <= 3) {
+                MLX_SWITCH_1_2_3(ndim, NDIM, {
+                  auto kernel =
+                      &rocm::binary_g_nd<Op, InType, OutType, IdxT, NDIM>;
+                  auto [num_blocks, block_dims] =
+                      get_launch_args(kernel, out, large);
+                  hipLaunchKernelGGL(kernel, num_blocks, block_dims, 0, stream,
+                      a.data<InType>(),
+                      b.data<InType>(),
+                      out.data<OutType>(),
+                      out.size(),
+                      make_hip_array<NDIM>(shape),
+                      make_hip_array<NDIM>(a_strides),
+                      make_hip_array<NDIM>(b_strides));
+                });
+              } else {
+                auto kernel = rocm::binary_g<Op, InType, OutType, IdxT>;
+                auto [num_blocks, block_dims] =
+                    get_launch_args(kernel, out, large);
+                hipLaunchKernelGGL(kernel, num_blocks, block_dims, 0, stream,
+                    a.data<InType>(),
+                    b.data<InType>(),
+                    out.data<OutType>(),
+                    out.size(),
+                    make_hip_array(shape),
+                    make_hip_array(a_strides),
+                    make_hip_array(b_strides),
+                    ndim);
+              }
+            });
+          } else {
+            MLX_SWITCH_BOOL(out.data_size() > UINT32_MAX, LARGE, {
+              using IdxT = std::conditional_t<LARGE, int64_t, uint32_t>;
+              auto kernel = rocm::binary_ss<Op, InType, OutType, IdxT>;
+              if (bopt == BinaryOpType::ScalarVector) {
+                kernel = rocm::binary_sv<Op, InType, OutType, IdxT>;
+              } else if (bopt == BinaryOpType::VectorScalar) {
+                kernel = rocm::binary_vs<Op, InType, OutType, IdxT>;
+              } else if (bopt == BinaryOpType::VectorVector) {
+                kernel = rocm::binary_vv<Op, InType, OutType, IdxT>;
+              }
+              auto [num_blocks, block_dims] = get_launch_args(
+                  kernel, out.data_size(), out.shape(), out.strides(), LARGE);
+              hipLaunchKernelGGL(kernel, num_blocks, block_dims, 0, stream,
+                  a.data<InType>(),
+                  b.data<InType>(),
+                  out.data<OutType>(),
+                  out.data_size());
+            });
+          }
+        } else {
+          throw std::runtime_error(fmt::format(
+              "Can not do binary op {} on inputs of {} with result of {}.",
+              op,
+              dtype_to_string(a.dtype()),
+              dtype_to_string(out.dtype())));
+        }
+      });
+    });
+  });
+}
+
+template <typename Op>
+void binary_op_gpu(
+    const std::vector<array>& inputs,
+    std::vector<array>& outputs,
+    std::string_view op,
+    const Stream& s) {
+  auto& a = inputs[0];
+  auto& b = inputs[1];
+  auto bopt = get_binary_op_type(a, b);
+  set_binary_op_output_data(a, b, outputs[0], bopt);
+  set_binary_op_output_data(a, b, outputs[1], bopt);
+  binary_op_gpu_inplace<Op>(inputs, outputs, op, s);
+}
+
+template <typename Op>
+void binary_op_gpu(
+    const std::vector<array>& inputs,
+    array& out,
+    std::string_view op,
+    const Stream& s) {
+  auto& a = inputs[0];
+  auto& b = inputs[1];
+  auto bopt = get_binary_op_type(a, b);
+  set_binary_op_output_data(a, b, out, bopt);
+  std::vector<array> outputs{out};
+  binary_op_gpu_inplace<Op>(inputs, outputs, op, s);
+}
+
+#define BINARY_GPU(func)                                                 \
+  void func::eval_gpu(const std::vector<array>& inputs, array& out) {    \
+    auto& s = out.primitive().stream();                                  \
+    binary_op_gpu<rocm::func>(inputs, out, get_primitive_string(this), s); \
+  }
+
+#define BINARY_GPU_MULTI(func)                                               \
+  void func::eval_gpu(                                                       \
+      const std::vector<array>& inputs, std::vector<array>& outputs) {       \
+    auto& s = outputs[0].primitive().stream();                               \
+    binary_op_gpu<rocm::func>(inputs, outputs, get_primitive_string(this), s); \
+  }
+
+BINARY_GPU(Add)
+BINARY_GPU(ArcTan2)
+BINARY_GPU(Divide)
+BINARY_GPU(Remainder)
+BINARY_GPU(Greater)
+BINARY_GPU(GreaterEqual)
+BINARY_GPU(Less)
+BINARY_GPU(LessEqual)
+BINARY_GPU(LogicalAnd)
+BINARY_GPU(LogicalOr)
+BINARY_GPU(LogAddExp)
+BINARY_GPU(Maximum)
+BINARY_GPU(Minimum)
+BINARY_GPU(Multiply)
+BINARY_GPU(NotEqual)
+BINARY_GPU(Power)
+BINARY_GPU(Subtract)
+
+void Equal::eval_gpu(const std::vector<array>& inputs, array& out) {
+  auto& s = out.primitive().stream();
+  auto op = get_primitive_string(this);
+  if (equal_nan_) {
+    binary_op_gpu<rocm::NaNEqual>(inputs, out, op, s);
+  } else {
+    binary_op_gpu<rocm::Equal>(inputs, out, op, s);
+  }
+}
+
+void BitwiseBinary::eval_gpu(const std::vector<array>& inputs, array& out) {
+  auto& s = out.primitive().stream();
+  auto op = get_primitive_string(this);
+  switch (op_) {
+    case BitwiseBinary::And:
+      binary_op_gpu<rocm::BitwiseAnd>(inputs, out, op, s);
+      break;
+    case BitwiseBinary::Or:
+      binary_op_gpu<rocm::BitwiseOr>(inputs, out, op, s);
+      break;
+    case BitwiseBinary::Xor:
+      binary_op_gpu<rocm::BitwiseXor>(inputs, out, op, s);
+      break;
+    case BitwiseBinary::LeftShift:
+      binary_op_gpu<rocm::LeftShift>(inputs, out, op, s);
+      break;
+    case BitwiseBinary::RightShift:
+      binary_op_gpu<rocm::RightShift>(inputs, out, op, s);
+      break;
+  }
+}
+
+} // namespace mlx::core 

mlx/backend/rocm/compiled.cpp

@@ -0,0 +1,9 @@
+// Copyright © 2025 Apple Inc.
+
+namespace mlx::core::rocm {
+
+void compile() {
+  // Placeholder for ROCm compilation
+}
+
+} // namespace mlx::core::rocm

mlx/backend/rocm/copy.hip

@@ -0,0 +1,20 @@
+// Copyright © 2025 Apple Inc.
+
+#include <hip/hip_runtime.h>
+
+namespace mlx::core::rocm {
+
+__global__ void copy_kernel(float* src, float* dst, int n) {
+  int idx = blockIdx.x * blockDim.x + threadIdx.x;
+  if (idx < n) {
+    dst[idx] = src[idx];
+  }
+}
+
+void launch_copy(float* src, float* dst, int n, hipStream_t stream) {
+  int threads = 256;
+  int blocks = (n + threads - 1) / threads;
+  hipLaunchKernelGGL(copy_kernel, dim3(blocks), dim3(threads), 0, stream, src, dst, n);
+}
+
+} // namespace mlx::core::rocm 

mlx/backend/rocm/copy/copy.hpp

@@ -0,0 +1,60 @@
+// Copyright © 2025 Apple Inc.
+
+#pragma once
+
+#include <hip/hip_runtime.h>
+#include <cstddef>
+
+namespace mlx::core::rocm {
+
+// Copy function declarations
+void copy_contiguous(
+    const void* src,
+    void* dst,
+    size_t size,
+    hipStream_t stream);
+
+void copy_general(
+    const void* src,
+    void* dst,
+    const int* src_shape,
+    const size_t* src_strides,
+    const int* dst_shape,
+    const size_t* dst_strides,
+    int ndim,
+    size_t size,
+    size_t dtype_size,
+    hipStream_t stream);
+
+void copy_general_dynamic(
+    const void* src,
+    void* dst,
+    const int* src_shape,
+    const size_t* src_strides,
+    const int* dst_shape,
+    const size_t* dst_strides,
+    int ndim,
+    size_t size,
+    size_t dtype_size,
+    hipStream_t stream);
+
+void copy_general_input(
+    const void* src,
+    void* dst,
+    const int* src_shape,
+    const size_t* src_strides,
+    const int* dst_shape,
+    const size_t* dst_strides,
+    int ndim,
+    size_t size,
+    size_t dtype_size,
+    hipStream_t stream);
+
+// Utility functions for element location calculation
+__device__ size_t
+elem_to_loc(size_t elem, const int* shape, const size_t* strides, int ndim);
+
+__device__ size_t
+loc_to_elem(size_t loc, const int* shape, const size_t* strides, int ndim);
+
+} // namespace mlx::core::rocm

mlx/backend/rocm/copy/copy_contiguous.hip

@@ -0,0 +1,38 @@
+// Copyright © 2025 Apple Inc.
+
+#include "mlx/backend/rocm/copy/copy.hpp"
+#include "mlx/backend/rocm/kernel_utils.hpp"
+
+#include <hip/hip_runtime.h>
+
+namespace mlx::core::rocm {
+
+__global__ void copy_contiguous_kernel(
+    const char* src,
+    char* dst,
+    size_t size) {
+  size_t tid = blockIdx.x * blockDim.x + threadIdx.x;
+  if (tid < size) {
+    dst[tid] = src[tid];
+  }
+}
+
+void copy_contiguous(
+    const void* src,
+    void* dst,
+    size_t size,
+    hipStream_t stream) {
+  if (size == 0) {
+    return;
+  }
+
+  const int threads_per_block = 256;
+  const int blocks = (size + threads_per_block - 1) / threads_per_block;
+
+  copy_contiguous_kernel<<<blocks, threads_per_block, 0, stream>>>(
+      static_cast<const char*>(src),
+      static_cast<char*>(dst),
+      size);
+}
+
+} // namespace mlx::core::rocm 

mlx/backend/rocm/device.cpp

@@ -0,0 +1,130 @@
+// Copyright © 2025 Apple Inc.
+
+#include "mlx/backend/rocm/device.h"
+#include "mlx/backend/metal/metal.h"
+#include "mlx/backend/rocm/worker.h"
+
+#include <fmt/format.h>
+
+namespace mlx::core {
+
+namespace rocm {
+
+DeviceStream::DeviceStream(Device& device) : device_(device), stream_(device) {}
+
+void DeviceStream::synchronize() {
+  CHECK_HIP_ERROR(hipStreamSynchronize(stream_));
+}
+
+hipStream_t DeviceStream::schedule_hip_stream() {
+  // TODO: Return a stream that maximizes parallelism.
+  return stream_;
+}
+
+hipStream_t DeviceStream::last_hip_stream() {
+  return stream_;
+}
+
+CommandEncoder& DeviceStream::get_encoder() {
+  if (!encoder_) {
+    encoder_ = std::make_unique<CommandEncoder>(*this);
+  }
+  return *encoder_;
+}
+
+Device::Device(int device) : device_(device) {
+  CHECK_HIP_ERROR(hipDeviceGetAttribute(
+      &compute_capability_major_,
+      hipDeviceAttributeComputeCapabilityMajor,
+      device_));
+  CHECK_HIP_ERROR(hipDeviceGetAttribute(
+      &compute_capability_minor_,
+      hipDeviceAttributeComputeCapabilityMinor,
+      device_));
+
+  // Validate device requirements
+  int attr = 0;
+  CHECK_HIP_ERROR(hipDeviceGetAttribute(
+      &attr, hipDeviceAttributeConcurrentManagedAccess, device_));
+  if (attr != 1) {
+    // ROCm unified memory might not be available on all devices
+    // This is a warning rather than an error for ROCm
+    // TODO: Add proper ROCm unified memory checking
+  }
+
+  // Create rocBLAS handle
+  make_current();
+  CHECK_HIP_ERROR(
+      static_cast<hipError_t>(rocblas_create_handle(&rocblas_handle_)));
+}
+
+Device::~Device() {
+  if (rocblas_handle_) {
+    rocblas_destroy_handle(rocblas_handle_);
+  }
+}
+
+void Device::make_current() {
+  // Cache current device to reduce HIP API calls
+  static int current = 0;
+  if (current != device_) {
+    CHECK_HIP_ERROR(hipSetDevice(device_));
+    current = device_;
+  }
+}
+
+DeviceStream& Device::get_stream(Stream s) {
+  auto it = streams_.find(s.index);
+  if (it == streams_.end()) {
+    it = streams_.try_emplace(s.index, *this).first;
+  }
+  return it->second;
+}
+
+CommandEncoder::CommandEncoder(DeviceStream& s)
+    : device_(s.device()), stream_(s) {}
+
+void CommandEncoder::add_completed_handler(std::function<void()> task) {
+  worker_.add_task(std::move(task));
+}
+
+void CommandEncoder::end_encoding() {
+  if (!temporaries_.empty()) {
+    add_completed_handler([temporaries = std::move(temporaries_)]() {});
+  }
+
+  // There is no kernel running, run completion handlers immediately.
+  if (!has_gpu_work_) {
+    worker_.consume_in_this_thread();
+    return;
+  }
+  has_gpu_work_ = false;
+
+  // Commit tasks
+  commit();
+}
+
+void CommandEncoder::commit() {
+  worker_.commit(stream_.last_hip_stream());
+}
+
+Device& device(mlx::core::Device device) {
+  static std::unordered_map<int, Device> devices;
+  auto it = devices.find(device.index);
+  if (it == devices.end()) {
+    it = devices.try_emplace(device.index, device.index).first;
+  }
+  return it->second;
+}
+
+DeviceStream& get_stream(Stream s) {
+  return device(s.device).get_stream(s);
+}
+
+CommandEncoder& get_command_encoder(Stream s) {
+  return get_stream(s).get_encoder();
+}
+
+} // namespace rocm
+
+} // namespace mlx::core

mlx/backend/rocm/device.h

@@ -0,0 +1,146 @@
+// Copyright © 2025 Apple Inc.
+
+#pragma once
+
+#include "mlx/array.h"
+#include "mlx/backend/rocm/utils.h"
+#include "mlx/backend/rocm/worker.h"
+#include "mlx/stream.h"
+
+#include <hip/hip_runtime.h>
+#include <rocblas/rocblas.h>
+
+#include <unordered_map>
+
+namespace mlx::core {
+
+namespace rocm {
+
+class Device;
+class CommandEncoder;
+
+class DeviceStream {
+ public:
+  explicit DeviceStream(Device& device);
+
+  DeviceStream(const DeviceStream&) = delete;
+  DeviceStream& operator=(const DeviceStream&) = delete;
+
+  // Wait until kernels in the stream complete.
+  void synchronize();
+
+  // Return a HIP stream for launching kernels.
+  hipStream_t schedule_hip_stream();
+
+  // Return the last HIP stream used.
+  hipStream_t last_hip_stream();
+
+  CommandEncoder& get_encoder();
+
+  Device& device() {
+    return device_;
+  }
+
+ private:
+  Device& device_;
+  HipStream stream_;
+  std::unique_ptr<CommandEncoder> encoder_;
+};
+
+class Device {
+ public:
+  explicit Device(int device);
+  ~Device();
+
+  Device(const Device&) = delete;
+  Device& operator=(const Device&) = delete;
+
+  // Make this device the current HIP device, required by some HIP calls.
+  void make_current();
+
+  DeviceStream& get_stream(Stream s);
+
+  int hip_device() const {
+    return device_;
+  }
+  int compute_capability_major() const {
+    return compute_capability_major_;
+  }
+  int compute_capability_minor() const {
+    return compute_capability_minor_;
+  }
+  rocblas_handle rocblas_handle() const {
+    return rocblas_handle_;
+  }
+
+ private:
+  int device_;
+  int compute_capability_major_;
+  int compute_capability_minor_;
+  rocblas_handle rocblas_handle_;
+  std::unordered_map<int, DeviceStream> streams_;
+};
+
+class CommandEncoder {
+ public:
+  explicit CommandEncoder(DeviceStream& stream);
+
+  CommandEncoder(const CommandEncoder&) = delete;
+  CommandEncoder& operator=(const CommandEncoder&) = delete;
+
+  void set_input_array(const array& arr) {}
+  void set_output_array(const array& arr) {}
+
+  void add_temporary(const array& arr) {
+    temporaries_.push_back(arr.data_shared_ptr());
+  }
+
+  void add_completed_handler(std::function<void()> task);
+  void end_encoding();
+  void commit();
+
+  // Schedule a HIP stream for |fun| to launch kernels, and check error
+  // afterwards.
+  template <typename F>
+  void launch_kernel(F&& fun) {
+    launch_kernel(stream_.schedule_hip_stream(), std::forward<F>(fun));
+  }
+
+  template <typename F>
+  void launch_kernel(hipStream_t stream, F&& fun) {
+    device_.make_current();
+    fun(stream);
+    check_hip_error("kernel launch", hipGetLastError());
+    has_gpu_work_ = true;
+  }
+
+  Device& device() {
+    return device_;
+  }
+
+  DeviceStream& stream() {
+    return stream_;
+  }
+
+  bool has_gpu_work() const {
+    return has_gpu_work_;
+  }
+
+ private:
+  Device& device_;
+  DeviceStream& stream_;
+  Worker worker_;
+  bool has_gpu_work_{false};
+  std::vector<std::shared_ptr<array::Data>> temporaries_;
+};
+
+Device& device(mlx::core::Device device);
+DeviceStream& get_stream(Stream s);
+CommandEncoder& get_command_encoder(Stream s);
+
+// Utility function to check HIP errors
+void check_hip_error(const char* msg, hipError_t error);
+
+} // namespace rocm
+
+} // namespace mlx::core

mlx/backend/rocm/device/arange.hpp

@@ -0,0 +1,17 @@
+// Copyright © 2025 Apple Inc.
+
+#pragma once
+
+#include <hip/hip_runtime.h>
+
+namespace mlx::core::rocm {
+
+template <typename T>
+__global__ void arange_kernel(T* out, T start, T step, size_t size) {
+  size_t tid = blockIdx.x * blockDim.x + threadIdx.x;
+  if (tid < size) {
+    out[tid] = start + static_cast<T>(tid) * step;
+  }
+}
+
+} // namespace mlx::core::rocm

mlx/backend/rocm/device/atomic_ops.hpp

@@ -0,0 +1,36 @@
+// Copyright © 2025 Apple Inc.
+
+#pragma once
+
+#include <hip/hip_runtime.h>
+
+namespace mlx::core::rocm {
+
+// Atomic operations for HIP
+__device__ inline float atomicAddFloat(float* address, float val) {
+  return atomicAdd(address, val);
+}
+
+__device__ inline double atomicAddDouble(double* address, double val) {
+  return atomicAdd(address, val);
+}
+
+__device__ inline int atomicAddInt(int* address, int val) {
+  return atomicAdd(address, val);
+}
+
+__device__ inline unsigned int atomicAddUInt(
+    unsigned int* address,
+    unsigned int val) {
+  return atomicAdd(address, val);
+}
+
+__device__ inline float atomicMaxFloat(float* address, float val) {
+  return atomicMax(address, val);
+}
+
+__device__ inline float atomicMinFloat(float* address, float val) {
+  return atomicMin(address, val);
+}
+
+} // namespace mlx::core::rocm

mlx/backend/rocm/device/binary_ops.hpp

@@ -0,0 +1,217 @@
+// Copyright © 2025 Apple Inc.
+
+#pragma once
+
+#include <hip/hip_bfloat16.h>
+#include <hip/hip_fp16.h>
+#include <hip/hip_runtime.h>
+#include <hipcomplex.h>
+
+namespace mlx::core::rocm {
+
+// Arithmetic operations
+struct Add {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return a + b;
+  }
+};
+
+struct Subtract {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return a - b;
+  }
+};
+
+struct Multiply {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return a * b;
+  }
+};
+
+struct Divide {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return a / b;
+  }
+};
+
+struct Power {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return powf(a, b);
+  }
+
+  __device__ double operator()(double a, double b) {
+    return pow(a, b);
+  }
+};
+
+struct Remainder {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return fmodf(a, b);
+  }
+
+  __device__ double operator()(double a, double b) {
+    return fmod(a, b);
+  }
+};
+
+// Comparison operations
+struct Equal {
+  template <typename T>
+  __device__ bool operator()(T a, T b) {
+    return a == b;
+  }
+};
+
+struct NotEqual {
+  template <typename T>
+  __device__ bool operator()(T a, T b) {
+    return a != b;
+  }
+};
+
+struct Greater {
+  template <typename T>
+  __device__ bool operator()(T a, T b) {
+    return a > b;
+  }
+};
+
+struct GreaterEqual {
+  template <typename T>
+  __device__ bool operator()(T a, T b) {
+    return a >= b;
+  }
+};
+
+struct Less {
+  template <typename T>
+  __device__ bool operator()(T a, T b) {
+    return a < b;
+  }
+};
+
+struct LessEqual {
+  template <typename T>
+  __device__ bool operator()(T a, T b) {
+    return a <= b;
+  }
+};
+
+struct NaNEqual {
+  template <typename T>
+  __device__ bool operator()(T a, T b) {
+    return (isnan(a) && isnan(b)) || (a == b);
+  }
+};
+
+// Logic operations
+struct LogicalAnd {
+  __device__ bool operator()(bool a, bool b) {
+    return a && b;
+  }
+};
+
+struct LogicalOr {
+  __device__ bool operator()(bool a, bool b) {
+    return a || b;
+  }
+};
+
+// Math operations
+struct Maximum {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return fmaxf(a, b);
+  }
+
+  __device__ double operator()(double a, double b) {
+    return fmax(a, b);
+  }
+};
+
+struct Minimum {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return fminf(a, b);
+  }
+
+  __device__ double operator()(double a, double b) {
+    return fmin(a, b);
+  }
+};
+
+struct LogAddExp {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    T max_val = fmaxf(a, b);
+    T min_val = fminf(a, b);
+    if (isinf(max_val)) {
+      return max_val;
+    }
+    return max_val + log1pf(expf(min_val - max_val));
+  }
+
+  __device__ double operator()(double a, double b) {
+    double max_val = fmax(a, b);
+    double min_val = fmin(a, b);
+    if (isinf(max_val)) {
+      return max_val;
+    }
+    return max_val + log1p(exp(min_val - max_val));
+  }
+};
+
+struct ArcTan2 {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return atan2f(a, b);
+  }
+
+  __device__ double operator()(double a, double b) {
+    return atan2(a, b);
+  }
+};
+
+// Bitwise operations
+struct BitwiseAnd {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return a & b;
+  }
+};
+
+struct BitwiseOr {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return a | b;
+  }
+};
+
+struct BitwiseXor {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return a ^ b;
+  }
+};
+
+struct LeftShift {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return a << b;
+  }
+};
+
+struct RightShift {
+  template <typename T>
+  __device__ T operator()(T a, T b) {
+    return a >> b;
+  }
+};
+
+} // namespace mlx::core::rocm

mlx/backend/rocm/device/cast_op.hpp

@@ -0,0 +1,21 @@
+// Copyright © 2025 Apple Inc.
+
+#pragma once
+
+#include <hip/hip_runtime.h>
+
+namespace mlx::core::rocm {
+
+template <typename To, typename From>
+struct CastOp {
+  __device__ To operator()(From x) const {
+    return static_cast<To>(x);
+  }
+};
+
+template <typename To, typename From>
+__device__ inline To cast_op(From x) {
+  return static_cast<To>(x);
+}
+
+} // namespace mlx::core::rocm

mlx/backend/rocm/device/config.h

@@ -0,0 +1,14 @@
+// Copyright © 2025 Apple Inc.
+
+#pragma once
+
+// ROCm/HIP specific configuration
+#define ROCM_MAX_THREADS_PER_BLOCK 1024
+#define ROCM_WARP_SIZE 64
+#define ROCM_MAX_BLOCKS_PER_GRID 65535
+
+namespace mlx::core::rocm {
+constexpr int kMaxThreadsPerBlock = ROCM_MAX_THREADS_PER_BLOCK;
+constexpr int kWarpSize = ROCM_WARP_SIZE;
+constexpr int kMaxBlocksPerGrid = ROCM_MAX_BLOCKS_PER_GRID;
+} // namespace mlx::core::rocm

mlx/backend/rocm/device/fp16_math.hpp

@@ -0,0 +1,87 @@
+// Copyright © 2025 Apple Inc.
+
+#pragma once
+
+#include <hip/hip_fp16.h>
+#include <hip/hip_runtime.h>
+
+namespace mlx::core::rocm {
+
+// HIP/ROCm equivalents of CUDA half precision math functions
+inline __device__ __half2 h2sin(__half2 x) {
+  return __half2{hsin(x.x), hsin(x.y)};
+}
+
+inline __device__ __half2 h2cos(__half2 x) {
+  return __half2{hcos(x.x), hcos(x.y)};
+}
+
+inline __device__ __half2 h2exp(__half2 x) {
+  return __half2{hexp(x.x), hexp(x.y)};
+}
+
+inline __device__ __half2 h2log(__half2 x) {
+  return __half2{hlog(x.x), hlog(x.y)};
+}
+
+inline __device__ __half2 h2sqrt(__half2 x) {
+  return __half2{hsqrt(x.x), hsqrt(x.y)};
+}
+
+inline __device__ __half2 h2rsqrt(__half2 x) {
+  return __half2{hrsqrt(x.x), hrsqrt(x.y)};
+}
+
+inline __device__ __half2 h2ceil(__half2 x) {
+  return __half2{hceil(x.x), hceil(x.y)};
+}
+
+inline __device__ __half2 h2floor(__half2 x) {
+  return __half2{hfloor(x.x), hfloor(x.y)};
+}
+
+inline __device__ __half2 h2rint(__half2 x) {
+  return __half2{hrint(x.x), hrint(x.y)};
+}
+
+inline __device__ __half2 h2trunc(__half2 x) {
+  return __half2{htrunc(x.x), htrunc(x.y)};
+}
+
+// Additional math functions for half precision
+inline __device__ __half habs(__half x) {
+  return __half{fabsf(__half2float(x))};
+}
+
+inline __device__ __half2 h2abs(__half2 x) {
+  return __half2{habs(x.x), habs(x.y)};
+}
+
+inline __device__ __half hneg(__half x) {
+  return __half{-__half2float(x)};
+}
+
+inline __device__ __half2 h2neg(__half2 x) {
+  return __half2{hneg(x.x), hneg(x.y)};
+}
+
+// BFloat16 support functions
+#ifdef __HIP_BFLOAT16__
+inline __device__ __hip_bfloat16 habs(__hip_bfloat16 x) {
+  return __hip_bfloat16{fabsf(__bfloat162float(x))};
+}
+
+inline __device__ __hip_bfloat162 h2abs(__hip_bfloat162 x) {
+  return __hip_bfloat162{habs(x.x), habs(x.y)};
+}
+
+inline __device__ __hip_bfloat16 hneg(__hip_bfloat16 x) {
+  return __hip_bfloat16{-__bfloat162float(x)};
+}
+
+inline __device__ __hip_bfloat162 h2neg(__hip_bfloat162 x) {
+  return __hip_bfloat162{hneg(x.x), hneg(x.y)};
+}
+#endif
+
+} // namespace mlx::core::rocm