调度SIMD指令+ SIMDPP + qmake [英] Dispatching SIMD instructions + SIMDPP + qmake

问题描述

我正在开发一个使用SIMD指令集的QT小部件.我已经编译了3个版本:SSE3，AVX和AVX2(simdpp允许通过单个#define在它们之间进行切换).

I'm developing a QT widget that makes use of SIMD instruction sets. I've compiled 3 versions: SSE3, AVX, and AVX2(simdpp allows to switch between them by a single #define).

现在，我想要的是让窗口小部件根据最佳支持的指令集在这些实现之间自动切换. simdpp随附的指南利用了一些makefile魔术:

Now, what I want is for my widget to switch automatically between these implementations, according to best supported instruction set. Guide that is provided with simdpp makes use of some makefile magic:

CXXFLAGS=""

test: main.o test_sse2.o test_sse3.o test_sse4_1.o test_null.o
    g++ $^ -o test

main.o: main.cc
    g++ main.cc $(CXXFLAGS) -c -o main.o

test_null.o: test.cc
    g++ test.cc -c $(CXXFLAGS) -DSIMDPP_EMIT_DISPATCHER \
        -DSIMDPP_DISPATCH_ARCH1=SIMDPP_ARCH_X86_SSE2 \
        -DSIMDPP_DISPATCH_ARCH2=SIMDPP_ARCH_X86_SSE3 \
        -DSIMDPP_DISPATCH_ARCH3=SIMDPP_ARCH_X86_SSE4_1 -o test_null.o

test_sse2.o: test.cc
    g++ test.cc -c $(CXXFLAGS) -DSIMDPP_ARCH_X86_SSE2 -msse2 -o test_sse2.o

test_sse3.o: test.cc
    g++ test.cc -c $(CXXFLAGS) -DSIMDPP_ARCH_X86_SSE3 -msse3 -o test_sse3.o

test_sse4_1.o: test.cc
    g++ test.cc -c $(CXXFLAGS) -DSIMDPP_ARCH_X86_SSE4_1 -msse4.1 -o test_sse4_1.o

此处是该指南的链接: http://p12tic.github.io/libsimdpp/v2.0~rc2/libsimdpp/arch/dispatch.html

Here is a link to the guide: http://p12tic.github.io/libsimdpp/v2.0~rc2/libsimdpp/arch/dispatch.html

我不知道如何使用qmake来实现这种行为.有什么想法吗?

I have no idea how to implement such behavior with qmake. Any ideas?

首先想到的是使用分派的代码创建一个共享库，并将其链接到项目.在这里，我再次陷入困境. App是跨平台的，这意味着它必须同时使用GCC和MSVC(准确地说是vc120)进行编译，这迫使Windows中使用nmake，我确实尝试过，但这就像我一生中最糟糕的经历

First that comes to mind is to create a shared library with dispatched code, and link it to the project. Here I'm stuck again. App is cross-platform, which means it has to compile with both GCC and MSVC(vc120, to be exact), which forces using nmake in Windows, and I tried, really, but it was like the worst experience in my whole programmer life.

世界各地的程序员，在此先感谢您！

Thanks in advance, programmers of the world!

推荐答案

如果太晚了，抱歉.希望我仍然可以提供帮助.

sorry if this is a bit late. Hope I can still help.

您需要考虑两个方面:编译时间和运行时间.

You need to consider 2 areas: Compile time and run time.

编译时-需要创建代码来支持不同的功能. 运行时-需要创建代码来确定可以运行的功能.

Compile time - need to create code to support different features. Run time - need to create code to decide which features you can run.

您想要做的是创建一个调度程序...

What you are wanting to do is create a dispatcher...

FuncImpl.h:

FuncImpl.h:

#pragma once
void execAvx2();
void execAvx();
void execSse();
void execDefault();

FuncImpl.cpp:

FuncImpl.cpp:

// Compile this file once for each variant with different compiler settings.
#if defined(__AVX2__)
void execAvx2()
{
 // AVX2 impl
...
}

#elif defined (__AVX__)

void execAvx()
{
// AVX impl
...
}

#elif defined (__SSE4_2__)

void execSse()
{
 // Sse impl
...
}

#else

void execDefault()
{
 // Vanilla impl
...
}

#endif

DispatchFunc.cpp

DispatchFunc.cpp

#include "FuncImpl.h"

// Decide at runtime which code to run
void dispatchFunc()
{
     if(CheckCpuAvx2Flag())
     {
         execAvx2();
     } 
     else if(CheckCpuAvxFlag())
     {
         execAvx();
     }
     else if(CheckCpuSseFlags())
     {
         execSse();
     }
     else
     {
         execDefault();
     }
}

您可以做的是创建一组QMAKE_EXTRA_COMPILERS.

What you can do is create a set of QMAKE_EXTRA_COMPILERS.

SampleCompiler.pri(对每个变体执行此操作):

SampleCompiler.pri (Do this for each variant):

MyCompiler.name = MyCompiler         # Name
MyCompiler.input = MY_SOURCES        # Symbol of the source list to compile
MyCompiler.dependency_type = TYPE_C
MyCompiler.variable_out = OBJECTS
# EXTRA_CXXFLAGS = -mavx / -mavx2 / -msse4.2
# _var = creates FileName_var.o => replace with own variant (_sse, etc)  
MyCompiler.output = ${QMAKE_VAR_OBJECTS_DIR}${QMAKE_FILE_IN_BASE}_var$${first(QMAKE_EXT_OBJ)}
MyCompiler.commands = $${QMAKE_CXX} $(CXXFLAGS) $${EXTRA_CXXFLAGS} $(INCPATH) -c ${QMAKE_FILE_IN} -o${QMAKE_FILE_OUT}
QMAKE_EXTRA_COMPILERS += MyCompiler   # Add my compiler

MyProject.pro

MyProject.pro

...
include(SseCompiler.pri)
include(AvxCompiler.pri)
include(Avx2Compiler.pri)
..

# Normal sources
# Will create FuncImpl.o and DispatchFunc.o
SOURCES += FuncImpl.cpp \
           DispatchFunc.cpp

# Give the other compilers their sources
# Will create FuncImpl_avx2.o FuncImpl_avx.o FuncImpl_sse.o
AVX2_SOURCES += FuncImpl.cpp
AVX_SOURCES += FuncImpl.cpp
SSE_SOURCES += FuncImpl.cpp

# Link all objects
...

您现在所需要的就是调用dispatchFunc()！

All you need now is to call dispatchFunc()!

检查cpu标志是您的另一项练习: cpuid

Checking cpu flags is another exercise for you: cpuid

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