Update Compute Pipeline Creation API (#581)

* Add option to specialize metal functions on function constants
* Update Compute Pipeline Creation API
* Add options to make libraries from source and stitching
* Update function specialization name options

mlx/backend/metal/device.cpp

@@ -1,4 +1,4 @@
-// Copyright © 2023 Apple Inc.
+// Copyright © 2023-24 Apple Inc.
 
 #include <dlfcn.h>
 #include <cstdlib>
@@ -242,37 +242,127 @@ void Device::register_library(
   }
 }
 
-MTL::ComputePipelineState* Device::get_kernel(
-    const std::string& name,
-    const std::string& lib_name /* = "mlx" */) {
-  auto pool = new_scoped_memory_pool();
-  // Look for cached kernel
-  if (auto it = kernel_map_.find(name); it != kernel_map_.end()) {
-    return it->second;
-  }
-
-  // Prepare new kernel
-
+MTL::Library* Device::get_library_cache_(const std::string& lib_name) {
   // Search for cached metal lib
   MTL::Library* mtl_lib;
-  if (auto it = library_map_.find(name); it != library_map_.end()) {
+  if (auto it = library_map_.find(lib_name); it != library_map_.end()) {
     mtl_lib = it->second;
   } else { // Look for metallib alongside library
     register_library(lib_name);
     mtl_lib = library_map_[lib_name];
   }
 
+  return mtl_lib;
+}
+
+MTL::Library* Device::get_library_(const std::string& source_string) {
+  auto pool = new_scoped_memory_pool();
+
+  auto ns_code =
+      NS::String::string(source_string.c_str(), NS::ASCIIStringEncoding);
+
+  NS::Error* error = nullptr;
+  auto mtl_lib = device_->newLibrary(ns_code, nullptr, &error);
+
+  // Throw error if unable to compile library
+  if (!mtl_lib) {
+    std::ostringstream msg;
+    msg << "[metal::Device] Unable to load build metal library from source"
+        << "\n";
+    if (error) {
+      msg << error->localizedDescription()->utf8String() << "\n";
+    }
+    throw std::runtime_error(msg.str());
+  }
+
+  return mtl_lib;
+}
+
+MTL::Library* Device::get_library_(const MTL::StitchedLibraryDescriptor* desc) {
+  auto pool = new_scoped_memory_pool();
+
+  NS::Error* error = nullptr;
+  auto mtl_lib = device_->newLibrary(desc, &error);
+
+  // Throw error if unable to compile library
+  if (!mtl_lib) {
+    std::ostringstream msg;
+    msg << "[metal::Device] Unable to load build stitched metal library"
+        << "\n";
+    if (error) {
+      msg << error->localizedDescription()->utf8String() << "\n";
+    }
+    throw std::runtime_error(msg.str());
+  }
+
+  return mtl_lib;
+}
+
+MTL::Function* Device::get_function_(
+    const std::string& name,
+    MTL::Library* mtl_lib) {
   // Pull kernel from library
   auto ns_name = NS::String::string(name.c_str(), NS::ASCIIStringEncoding);
   auto mtl_function = mtl_lib->newFunction(ns_name);
 
+  return mtl_function;
+}
+
+MTL::Function* Device::get_function_(
+    const std::string& name,
+    const std::string& specialized_name,
+    const MTLFCList& func_consts,
+    MTL::Library* mtl_lib) {
+  if (func_consts.empty() && (specialized_name == name)) {
+    return get_function_(name, mtl_lib);
+  }
+
+  // Prepare function constants
+  auto mtl_func_consts = MTL::FunctionConstantValues::alloc()->init();
+
+  for (auto [value, type, index] : func_consts) {
+    mtl_func_consts->setConstantValue(value, type, index);
+  }
+
+  // Prepare function desc
+  auto desc = MTL::FunctionDescriptor::functionDescriptor();
+  desc->setName(NS::String::string(name.c_str(), NS::ASCIIStringEncoding));
+  desc->setSpecializedName(
+      NS::String::string(specialized_name.c_str(), NS::ASCIIStringEncoding));
+  desc->setConstantValues(mtl_func_consts);
+
+  // Pull kernel from library
+  NS::Error* error = nullptr;
+  auto mtl_function = mtl_lib->newFunction(desc, &error);
+
+  // Throw error if unable to build metal function
+  if (!mtl_function) {
+    std::ostringstream msg;
+    msg << "[metal::Device] Unable to load function " << name << "\n";
+    if (error) {
+      msg << error->localizedDescription()->utf8String() << "\n";
+    }
+    throw std::runtime_error(msg.str());
+  }
+
+  mtl_func_consts->release();
+  desc->release();
+
+  return mtl_function;
+}
+
+MTL::ComputePipelineState* Device::get_kernel_(
+    const std::string& name,
+    const MTL::Function* mtl_function) {
   // Compile kernel to compute pipeline
   NS::Error* error = nullptr;
   MTL::ComputePipelineState* kernel;
+
   if (mtl_function) {
     kernel = device_->newComputePipelineState(mtl_function, &error);
-    mtl_function->release();
   }
+
+  // Throw error if unable to compile metal function
   if (!mtl_function || !kernel) {
     std::ostringstream msg;
     msg << "[metal::Device] Unable to load kernel " << name << "\n";
@@ -282,11 +372,170 @@ MTL::ComputePipelineState* Device::get_kernel(
     throw std::runtime_error(msg.str());
   }
 
-  // Add kernel to cache
-  kernel_map_.insert({name, kernel});
   return kernel;
 }
 
+MTL::ComputePipelineState* Device::get_kernel_(
+    const std::string& name,
+    const MTL::Function* mtl_function,
+    const MTL::LinkedFunctions* linked_functions) {
+  // Check inputs
+  if (!linked_functions) {
+    return get_kernel_(name, mtl_function);
+  }
+
+  if (!mtl_function) {
+    std::ostringstream msg;
+    msg << "[metal::Device] Unable to load kernel " << name << "\n";
+    throw std::runtime_error(msg.str());
+  }
+
+  // Prepare compute pipeline state descriptor
+  auto desc = MTL::ComputePipelineDescriptor::alloc()->init();
+  desc->setComputeFunction(mtl_function);
+  desc->setLinkedFunctions(linked_functions);
+
+  // Compile kernel to compute pipeline
+  NS::Error* error = nullptr;
+  auto kernel = device_->newComputePipelineState(
+      desc, MTL::PipelineOptionNone, nullptr, &error);
+
+  // Throw error if unable to compile metal function
+  if (!kernel) {
+    std::ostringstream msg;
+    msg << "[metal::Device] Unable to load kernel " << name << "\n";
+    if (error) {
+      msg << error->localizedDescription()->utf8String() << "\n";
+    }
+    throw std::runtime_error(msg.str());
+  }
+
+  return kernel;
+}
+
+MTL::Library* Device::get_library(
+    const std::string& name,
+    const std::string& source,
+    bool cache /* = true */) {
+  if (cache) {
+    if (auto it = library_map_.find(name); it != library_map_.end()) {
+      return it->second;
+    }
+  }
+
+  auto mtl_lib = get_library_(source);
+
+  if (cache) {
+    library_map_.insert({name, mtl_lib});
+  }
+
+  return mtl_lib;
+}
+
+MTL::Library* Device::get_library(
+    const std::string& name,
+    const MTL::StitchedLibraryDescriptor* desc,
+    bool cache /* = true */) {
+  if (cache) {
+    if (auto it = library_map_.find(name); it != library_map_.end()) {
+      return it->second;
+    }
+  }
+
+  auto mtl_lib = get_library_(desc);
+
+  if (cache) {
+    library_map_.insert({name, mtl_lib});
+  }
+
+  return mtl_lib;
+}
+
+MTL::Function* Device::get_function(
+    const std::string& base_name,
+    MTL::Library* mtl_lib,
+    const std::string& specialized_name /* = "" */,
+    const MTLFCList& func_consts /* = {} */) {
+  return get_function_(base_name, specialized_name, func_consts, mtl_lib);
+}
+
+MTL::Function* Device::get_function(
+    const std::string& base_name,
+    const std::string& lib_name /* = "mlx" */,
+    const std::string& specialized_name /*  = "" */,
+    const MTLFCList& func_consts /* = {} */) {
+  // Search for cached metal lib
+  MTL::Library* mtl_lib = get_library_cache_(lib_name);
+
+  return get_function(base_name, mtl_lib, specialized_name, func_consts);
+}
+
+MTL::LinkedFunctions* Device::get_linked_functions_(
+    const std::vector<MTL::Function*>& funcs) {
+  if (funcs.empty()) {
+    return nullptr;
+  }
+
+  auto lfuncs = MTL::LinkedFunctions::linkedFunctions();
+
+  std::vector<NS::Object*> objs(funcs.size());
+  for (int i = 0; i < funcs.size(); i++) {
+    objs[i] = funcs[i];
+  }
+
+  NS::Array* funcs_arr = NS::Array::array(objs.data(), funcs.size());
+
+  lfuncs->setPrivateFunctions(funcs_arr);
+
+  return lfuncs;
+}
+
+MTL::ComputePipelineState* Device::get_kernel(
+    const std::string& base_name,
+    MTL::Library* mtl_lib,
+    const std::string& hash_name /* = "" */,
+    const MTLFCList& func_consts /* = {} */,
+    const std::vector<MTL::Function*>& linked_functions /* = {} */) {
+  auto pool = new_scoped_memory_pool();
+
+  // Look for cached kernel
+  const auto& kname = hash_name.empty() ? base_name : hash_name;
+  if (auto it = kernel_map_.find(kname); it != kernel_map_.end()) {
+    return it->second;
+  }
+
+  // Pull kernel from library
+  auto mtl_function = get_function_(base_name, kname, func_consts, mtl_lib);
+
+  // Compile kernel to compute pipeline
+  auto mtl_linked_funcs = get_linked_functions_(linked_functions);
+  auto kernel = get_kernel_(kname, mtl_function, mtl_linked_funcs);
+  mtl_function->release();
+  mtl_linked_funcs->release();
+
+  // Add kernel to cache
+  kernel_map_.insert({kname, kernel});
+  return kernel;
+}
+
+MTL::ComputePipelineState* Device::get_kernel(
+    const std::string& base_name,
+    const std::string& lib_name /* = "mlx" */,
+    const std::string& hash_name /*  = "" */,
+    const MTLFCList& func_consts /*  = {} */,
+    const std::vector<MTL::Function*>& linked_functions /*  = {} */) {
+  // Look for cached kernel
+  const auto& kname = hash_name.size() == 0 ? base_name : hash_name;
+  if (auto it = kernel_map_.find(kname); it != kernel_map_.end()) {
+    return it->second;
+  }
+
+  // Search for cached metal lib
+  MTL::Library* mtl_lib = get_library_cache_(lib_name);
+
+  return get_kernel(base_name, mtl_lib, kname, func_consts, linked_functions);
+}
+
 Device& device(mlx::core::Device) {
   static Device metal_device;
   return metal_device;

mlx/backend/metal/device.h

@@ -1,4 +1,4 @@
-// Copyright © 2023 Apple Inc.
+// Copyright © 2023-24 Apple Inc.
 
 #pragma once
 
@@ -31,6 +31,9 @@ inline std::string get_colocated_mtllib_path(const std::string& lib_name) {
   return mtllib_path;
 }
 
+using MTLFCList =
+    std::vector<std::tuple<const void*, MTL::DataType, NS::UInteger>>;
+
 class Device {
  public:
   Device();
@@ -59,14 +62,71 @@ class Device {
       const std::function<std::string(const std::string&)>& lib_path_func =
           get_colocated_mtllib_path);
 
-  MTL::ComputePipelineState* get_kernel(
+  MTL::Library* get_library(
       const std::string& name,
-      const std::string& lib_name = "mlx");
+      const std::string& source_string,
+      bool cache = true);
+
+  MTL::Library* get_library(
+      const std::string& name,
+      const MTL::StitchedLibraryDescriptor* desc,
+      bool cache = true);
+
+  MTL::Function* get_function(
+      const std::string& base_name,
+      MTL::Library* mtl_lib,
+      const std::string& specialized_name = "",
+      const MTLFCList& func_consts = {});
+
+  MTL::Function* get_function(
+      const std::string& base_name,
+      const std::string& lib_name = "mlx",
+      const std::string& specialized_name = "",
+      const MTLFCList& func_consts = {});
+
+  MTL::ComputePipelineState* get_kernel(
+      const std::string& base_name,
+      MTL::Library* mtl_lib,
+      const std::string& hash_name = "",
+      const MTLFCList& func_consts = {},
+      const std::vector<MTL::Function*>& linked_functions = {});
+
+  MTL::ComputePipelineState* get_kernel(
+      const std::string& base_name,
+      const std::string& lib_name = "mlx",
+      const std::string& hash_name = "",
+      const MTLFCList& func_consts = {},
+      const std::vector<MTL::Function*>& linked_functions = {});
 
   MTL::ArgumentEncoder* argument_encoder(
       const std::vector<MTL::ArgumentDescriptor*>& arg_descs) const;
 
  private:
+  MTL::Library* get_library_cache_(const std::string& name);
+
+  MTL::Library* get_library_(const std::string& source_string);
+  MTL::Library* get_library_(const MTL::StitchedLibraryDescriptor* desc);
+
+  MTL::Function* get_function_(const std::string& name, MTL::Library* mtl_lib);
+
+  MTL::Function* get_function_(
+      const std::string& name,
+      const std::string& specialized_name,
+      const MTLFCList& func_consts,
+      MTL::Library* mtl_lib);
+
+  MTL::LinkedFunctions* get_linked_functions_(
+      const std::vector<MTL::Function*>& funcs);
+
+  MTL::ComputePipelineState* get_kernel_(
+      const std::string& name,
+      const MTL::Function* mtl_function);
+
+  MTL::ComputePipelineState* get_kernel_(
+      const std::string& name,
+      const MTL::Function* mtl_function,
+      const MTL::LinkedFunctions* linked_functions);
+
   MTL::Device* device_;
   std::unordered_map<int32_t, MTL::CommandQueue*> queue_map_;
   std::unordered_map<int32_t, std::pair<int, MTL::CommandBuffer*>> buffer_map_;