mlx/mlx/backend/metal/rope.cpp

90 lines
2.9 KiB
C++

// Copyright © 2023-2024 Apple Inc.
#include "mlx/backend/metal/copy.h"
#include "mlx/backend/metal/utils.h"
#include "mlx/fast_primitives.h"
namespace mlx::core::fast {
void RoPE::eval_gpu(
const std::vector<array>& inputs,
std::vector<array>& outputs) {
assert(inputs.size() == 1);
assert(outputs.size() == 1);
auto& in = inputs[0];
auto& out = outputs[0];
if (in.ndim() < 3) {
throw std::runtime_error("[RoPE] Input must have at least 3 dimensions");
}
auto& s = out.primitive().stream();
auto& d = metal::device(s.device);
size_t strides[3];
size_t out_strides[3];
bool donated = false;
int ndim = in.ndim();
size_t mat_size = in.shape(-2) * in.shape(-1);
if (dims_ < in.shape(-1)) {
donated = true;
auto ctype =
(in.flags().row_contiguous) ? CopyType::Vector : CopyType::General;
copy_gpu(in, out, ctype, s);
strides[0] = mat_size;
strides[1] = out.strides()[ndim - 2];
strides[2] = out.strides()[ndim - 1];
} else if (in.flags().row_contiguous) {
if (in.is_donatable()) {
donated = true;
out.move_shared_buffer(in);
} else {
out.set_data(allocator::malloc_or_wait(out.nbytes()));
}
strides[0] = mat_size;
strides[1] = in.strides()[ndim - 2];
strides[2] = in.strides()[ndim - 1];
} else if (ndim == 3) {
// Handle non-contiguous 3D inputs
out.set_data(allocator::malloc_or_wait(out.nbytes()));
strides[0] = in.strides()[0];
strides[1] = in.strides()[1];
strides[2] = in.strides()[2];
} else {
// Copy non-contiguous > 3D inputs into the output and treat
// input as donated
donated = true;
copy_gpu(in, out, CopyType::General, s);
strides[0] = mat_size;
strides[1] = out.strides()[ndim - 2];
strides[2] = out.strides()[ndim - 1];
}
out_strides[0] = mat_size;
out_strides[1] = out.strides()[ndim - 2];
out_strides[2] = out.strides()[ndim - 1];
std::ostringstream kname;
kname << "rope_" << (forward_ ? "" : "vjp_")
<< (traditional_ ? "traditional_" : "") << type_to_name(in);
auto kernel = d.get_kernel(kname.str());
auto& compute_encoder = d.get_command_encoder(s.index);
float base = std::log2(base_);
compute_encoder->setComputePipelineState(kernel);
compute_encoder.set_input_array(donated ? out : in, 0);
compute_encoder.set_output_array(out, 1);
compute_encoder->setBytes(&strides, 3 * sizeof(size_t), 2);
compute_encoder->setBytes(&out_strides, 3 * sizeof(size_t), 3);
compute_encoder->setBytes(&offset_, sizeof(int), 4);
compute_encoder->setBytes(&base, sizeof(float), 5);
compute_encoder->setBytes(&scale_, sizeof(float), 6);
int dim0 = dims_ / 2;
int dim1 = in.shape(-2);
int dim2 = in.size() / mat_size;
auto group_dims = get_block_dims(dim0, dim1, dim2);
auto grid_dims = MTL::Size(dim0, dim1, dim2);
compute_encoder->dispatchThreads(grid_dims, group_dims);
}
} // namespace mlx::core::fast