faiss/gpu/utils/LoadStoreOperators.cuh

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/**
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
#pragma once
#include <faiss/gpu/utils/Float16.cuh>
#ifndef __HALF2_TO_UI
// cuda_fp16.hpp doesn't export this
#define __HALF2_TO_UI(var) *(reinterpret_cast<unsigned int *>(&(var)))
#endif
//
// Templated wrappers to express load/store for different scalar and vector
// types, so kernels can have the same written form but can operate
// over half and float, and on vector types transparently
//
namespace faiss { namespace gpu {
template <typename T>
struct LoadStore {
static inline __device__ T load(void* p) {
return *((T*) p);
}
static inline __device__ void store(void* p, const T& v) {
*((T*) p) = v;
}
};
template <>
struct LoadStore<Half4> {
static inline __device__ Half4 load(void* p) {
Half4 out;
#if CUDA_VERSION >= 9000
asm("ld.global.v2.u32 {%0, %1}, [%2];" :
"=r"(__HALF2_TO_UI(out.a)), "=r"(__HALF2_TO_UI(out.b)) : "l"(p));
#else
asm("ld.global.v2.u32 {%0, %1}, [%2];" :
"=r"(out.a.x), "=r"(out.b.x) : "l"(p));
#endif
return out;
}
static inline __device__ void store(void* p, Half4& v) {
#if CUDA_VERSION >= 9000
asm("st.v2.u32 [%0], {%1, %2};" : : "l"(p),
"r"(__HALF2_TO_UI(v.a)), "r"(__HALF2_TO_UI(v.b)));
#else
asm("st.v2.u32 [%0], {%1, %2};" : : "l"(p), "r"(v.a.x), "r"(v.b.x));
#endif
}
};
template <>
struct LoadStore<Half8> {
static inline __device__ Half8 load(void* p) {
Half8 out;
#if CUDA_VERSION >= 9000
asm("ld.global.v4.u32 {%0, %1, %2, %3}, [%4];" :
"=r"(__HALF2_TO_UI(out.a.a)), "=r"(__HALF2_TO_UI(out.a.b)),
"=r"(__HALF2_TO_UI(out.b.a)), "=r"(__HALF2_TO_UI(out.b.b)) : "l"(p));
#else
asm("ld.global.v4.u32 {%0, %1, %2, %3}, [%4];" :
"=r"(out.a.a.x), "=r"(out.a.b.x),
"=r"(out.b.a.x), "=r"(out.b.b.x) : "l"(p));
#endif
return out;
}
static inline __device__ void store(void* p, Half8& v) {
#if CUDA_VERSION >= 9000
asm("st.v4.u32 [%0], {%1, %2, %3, %4};"
: : "l"(p), "r"(__HALF2_TO_UI(v.a.a)), "r"(__HALF2_TO_UI(v.a.b)),
"r"(__HALF2_TO_UI(v.b.a)), "r"(__HALF2_TO_UI(v.b.b)));
#else
asm("st.v4.u32 [%0], {%1, %2, %3, %4};"
: : "l"(p), "r"(v.a.a.x), "r"(v.a.b.x), "r"(v.b.a.x), "r"(v.b.b.x));
#endif
}
};
} } // namespace