mlx/mlx/backend/metal/kernels/rope.metal
2024-03-22 17:28:26 -07:00

71 lines
2.6 KiB
Metal

// Copyright © 2023-2024 Apple Inc.
#include <metal_math>
#include "mlx/backend/metal/kernels/bf16.h"
#include "mlx/backend/metal/kernels/utils.h"
template <typename T, bool traditional>
[[kernel]] void rope(
const device T *in [[buffer(0)]],
device T * out [[buffer(1)]],
constant const size_t strides[3],
constant const size_t out_strides[3],
constant const int& offset,
constant const float& base,
constant const float& scale,
uint3 pos [[thread_position_in_grid]],
uint3 grid [[threads_per_grid]]) {
// Compute the input and output indices
uint in_index_1, in_index_2;
uint out_index_1, out_index_2;
if (traditional) {
out_index_1 = 2 * pos.x * out_strides[2] + pos.y * out_strides[1] + pos.z * out_strides[0];
out_index_2 = out_index_1 + 1;
in_index_1 = 2 * pos.x * strides[2] + pos.y * strides[1] + pos.z * strides[0];
in_index_2 = in_index_1 + strides[2];
} else {
out_index_1 = pos.x * out_strides[2] + pos.y * out_strides[1] + pos.z * out_strides[0];
out_index_2 = out_index_1 + grid.x * out_strides[2];
in_index_1 = pos.x * strides[2] + pos.y * strides[1] + pos.z * strides[0];
in_index_2 = in_index_1 + grid.x * strides[2];
}
// Figure out L and d.
float L = scale * static_cast<float>(pos.y + offset);
float d = static_cast<float>(pos.x) / static_cast<float>(grid.x);
// Compute costheta, sintheta
float theta = L * metal::exp2(-d * base);
float costheta = metal::fast::cos(theta);
float sintheta = metal::fast::sin(theta);
// Read and write the output
float x1 = static_cast<float>(in[in_index_1]);
float x2 = static_cast<float>(in[in_index_2]);
float rx1 = x1 * costheta - x2 * sintheta;
float rx2 = x1 * sintheta + x2 * costheta;
out[out_index_1] = static_cast<T>(rx1);
out[out_index_2] = static_cast<T>(rx2);
}
#define instantiate_rope(name, type, traditional) \
template [[host_name("rope_" #name)]] \
[[kernel]] void rope<type, traditional>( \
const device type* in [[buffer(0)]], \
device type* out [[buffer(1)]], \
constant const size_t strides[3], \
constant const size_t out_strides[3], \
constant const int& offset, \
constant const float& base, \
constant const float& scale, \
uint3 pos [[thread_position_in_grid]], \
uint3 grid [[threads_per_grid]]);
instantiate_rope(traditional_float16, half, true)
instantiate_rope(traditional_bfloat16, bfloat16_t, true)
instantiate_rope(traditional_float32, float, true)
instantiate_rope(float16, half, false)
instantiate_rope(bfloat16, bfloat16_t, false)
instantiate_rope(float32, float, false)