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