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100 lines
3.6 KiB
C++
100 lines
3.6 KiB
C++
/************************* dispatch_example.cpp ****************************
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| Author: Agner Fog
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| Date created: 2012-05-30
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| Last modified: 2014-07-23
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| Version: 1.14
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| Project: vector classes
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| Description:
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| Example of CPU dispatching.
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| # Example of compiling this with GCC compiler:
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| # Compile dispatch_example.cpp five times for different instruction sets:
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| g++ -O3 -msse2 -c dispatch_example.cpp -od2.o
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| g++ -O3 -msse4.1 -c dispatch_example.cpp -od5.o
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| g++ -O3 -mavx -c dispatch_example.cpp -od7.o
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| g++ -O3 -mavx2 -c dispatch_example.cpp -od8.o
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| g++ -O3 -mavx512f -c dispatch_example.cpp -od9.o
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| g++ -O3 -msse2 -otest instrset_detect.cpp d2.o d5.o d7.o d8.o d9.o
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| ./test
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| (c) Copyright 2012 - 2014 GNU General Public License http://www.gnu.org/licenses
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\*****************************************************************************/
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#include <stdio.h>
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#define MAX_VECTOR_SIZE 512
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#include "vectorclass.h"
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// define function type (change this to fit your purpose. Should not contain vector types)
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typedef float MyFuncType(float*);
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// function prototypes for each version
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MyFuncType myfunc, myfunc_SSE2, myfunc_SSE41, myfunc_AVX, myfunc_AVX2, myfunc_AVX512, myfunc_dispatch;
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// Define function name depending on which instruction set we compile for
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#if INSTRSET == 2 // SSE2
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#define FUNCNAME myfunc_SSE2
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#elif INSTRSET == 5 // SSE4.1
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#define FUNCNAME myfunc_SSE41
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#elif INSTRSET == 7 // AVX
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#define FUNCNAME myfunc_AVX
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#elif INSTRSET == 8 // AVX2
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#define FUNCNAME myfunc_AVX2
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#elif INSTRSET == 9 // AVX512
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#define FUNCNAME myfunc_AVX512
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#endif
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// specific version of the function. Compile once for each version
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float FUNCNAME (float * f) {
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Vec16f a; // vector of 16 floats
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a.load(f); // load array into vector
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return horizontal_add(a); // return sum of 16 elements
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}
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#if INSTRSET == 2
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// make dispatcher in only the lowest of the compiled versions
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// Function pointer initially points to the dispatcher.
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// After first call it points to the selected version
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MyFuncType * myfunc_pointer = &myfunc_dispatch; // function pointer
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// Dispatcher
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float myfunc_dispatch(float * f) {
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int iset = instrset_detect(); // Detect supported instruction set
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if (iset >= 9) myfunc_pointer = &myfunc_AVX512; // AVX512 version
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else if (iset >= 8) myfunc_pointer = &myfunc_AVX2; // AVX2 version
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else if (iset >= 7) myfunc_pointer = &myfunc_AVX; // AVX version
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else if (iset >= 5) myfunc_pointer = &myfunc_SSE41; // SSE4.1 version
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else if (iset >= 2) myfunc_pointer = &myfunc_SSE2; // SSE2 version
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else {
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// Error: lowest instruction set not supported (put your own error message here:)
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fprintf(stderr, "\nError: Instruction set SSE2 not supported on this computer");
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return 0.f;
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}
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// continue in dispatched version
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return (*myfunc_pointer)(f);
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}
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// Entry to dispatched function call
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inline float myfunc(float * f) {
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return (*myfunc_pointer)(f); // go to dispatched version
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}
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// Example: main calls myfunc
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int main(int argc, char* argv[])
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{
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float a[16]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16}; // array of 16 floats
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float sum = myfunc(a); // call function with dispatching
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printf("\nsum = %8.3f \n", sum); // print result
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return 0;
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}
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#endif // INSTRSET == 2
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