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// !!!! PLEASE READ !!!!
// Minimize (transitively) included headers from _avx*.cc because some of the
// functions defined in the headers compiled with platform dependent compiler
// options can be reused by other translation units generating illegal
// instruction run-time error.
// Common utilities for writing performance kernels and easy dispatching of
// different backends.
/*
The general workflow shall be as follows, say we want to
implement a functionality called void foo(int a, float b).
In foo.h, do:
void foo(int a, float b);
In foo_avx512.cc, do:
void foo__avx512(int a, float b) {
[actual avx512 implementation]
}
In foo_avx2.cc, do:
void foo__avx2(int a, float b) {
[actual avx2 implementation]
}
In foo_avx.cc, do:
void foo__avx(int a, float b) {
[actual avx implementation]
}
In foo.cc, do:
// The base implementation should *always* be provided.
void foo__base(int a, float b) {
[base, possibly slow implementation]
}
decltype(foo__base) foo__avx512;
decltype(foo__base) foo__avx2;
decltype(foo__base) foo__avx;
void foo(int a, float b) {
// You should always order things by their preference, faster
// implementations earlier in the function.
AVX512_DO(foo, a, b);
AVX2_DO(foo, a, b);
AVX_DO(foo, a, b);
BASE_DO(foo, a, b);
}
*/
// Details: this functionality basically covers the cases for both build time
// and run time architecture support.
//
// During build time:
// The build system should provide flags CAFFE2_PERF_WITH_AVX512,
// CAFFE2_PERF_WITH_AVX2, and CAFFE2_PERF_WITH_AVX that corresponds to the
// __AVX512F__, __AVX512DQ__, __AVX512VL__, __AVX2__, and __AVX__ flags the
// compiler provides. Note that we do not use the compiler flags but rely on
// the build system flags, because the common files (like foo.cc above) will
// always be built without __AVX512F__, __AVX512DQ__, __AVX512VL__, __AVX2__
// and __AVX__.
// During run time:
// we use cpuid to identify cpu support and run the proper functions.
#pragma once
#include "caffe2/utils/cpuid.h"
// DO macros: these should be used in your entry function, similar to foo()
// above, that routes implementations based on CPU capability.
#define BASE_DO(funcname, ...) return funcname##__base(__VA_ARGS__);
#ifdef CAFFE2_PERF_WITH_AVX512
#define AVX512_DO(funcname, ...) \
if (GetCpuId().avx512f() && GetCpuId().avx512dq() && \
GetCpuId().avx512vl()) { \
return funcname##__avx512(__VA_ARGS__); \
}
#else // CAFFE2_PERF_WITH_AVX512
#define AVX512_DO(funcname, ...)
#endif // CAFFE2_PERF_WITH_AVX512
#ifdef CAFFE2_PERF_WITH_AVX2
#define AVX2_DO(funcname, ...) \
if (GetCpuId().avx2()) { \
return funcname##__avx2(__VA_ARGS__); \
}
#define AVX2_FMA_DO(funcname, ...) \
if (GetCpuId().avx2() && GetCpuId().fma()) { \
return funcname##__avx2_fma(__VA_ARGS__); \
}
#else // CAFFE2_PERF_WITH_AVX2
#define AVX2_DO(funcname, ...)
#define AVX2_FMA_DO(funcname, ...)
#endif // CAFFE2_PERF_WITH_AVX2
#ifdef CAFFE2_PERF_WITH_AVX
#define AVX_DO(funcname, ...) \
if (GetCpuId().avx()) { \
return funcname##__avx(__VA_ARGS__); \
}
#define AVX_F16C_DO(funcname, ...) \
if (GetCpuId().avx() && GetCpuId().f16c()) { \
return funcname##__avx_f16c(__VA_ARGS__); \
}
#else // CAFFE2_PERF_WITH_AVX
#define AVX_DO(funcname, ...)
#define AVX_F16C_DO(funcname, ...)
#endif // CAFFE2_PERF_WITH_AVX
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