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/************************* dispatch_example.cpp ****************************
| Author: Agner Fog
| Date created: 2012-05-30
* Last modified: 2016-04-26
* Version: 1.22
| Project: vector classes
| Description:
| Example of CPU dispatching.
|
| # Example of compiling this with GCC compiler:
| # Compile dispatch_example.cpp five times for different instruction sets:
| g++ -O3 -msse2 -c dispatch_example.cpp -od2.o
| g++ -O3 -msse4.1 -c dispatch_example.cpp -od5.o
| g++ -O3 -mavx -c dispatch_example.cpp -od7.o
| g++ -O3 -mavx2 -c dispatch_example.cpp -od8.o
| g++ -O3 -mavx512f -c dispatch_example.cpp -od9.o
| g++ -O3 -msse2 -otest instrset_detect.cpp d2.o d5.o d7.o d8.o d9.o
| ./test
|
| (c) Copyright 2012-2016 GNU General Public License http://www.gnu.org/licenses
\*****************************************************************************/
#include <stdio.h>
#define MAX_VECTOR_SIZE 512
#include "vectorclass.h"
#ifdef VCL_NAMESPACE
namespace VCL_NAMESPACE {
#endif
// define function type (change this to fit your purpose. Should not contain vector types)
typedef float MyFuncType(float*);
// function prototypes for each version
MyFuncType myfunc, myfunc_SSE2, myfunc_SSE41, myfunc_AVX, myfunc_AVX2, myfunc_AVX512, myfunc_dispatch;
// Define function name depending on which instruction set we compile for
#if INSTRSET == 2 // SSE2
#define FUNCNAME myfunc_SSE2
#elif INSTRSET == 5 // SSE4.1
#define FUNCNAME myfunc_SSE41
#elif INSTRSET == 7 // AVX
#define FUNCNAME myfunc_AVX
#elif INSTRSET == 8 // AVX2
#define FUNCNAME myfunc_AVX2
#elif INSTRSET == 9 // AVX512
#define FUNCNAME myfunc_AVX512
#endif
// specific version of the function. Compile once for each version
float FUNCNAME (float * f) {
Vec16f a; // vector of 16 floats
a.load(f); // load array into vector
return horizontal_add(a); // return sum of 16 elements
}
#if INSTRSET == 2
// make dispatcher in only the lowest of the compiled versions
// Function pointer initially points to the dispatcher.
// After first call it points to the selected version
MyFuncType * myfunc_pointer = &myfunc_dispatch; // function pointer
// Dispatcher
float myfunc_dispatch(float * f) {
int iset = instrset_detect(); // Detect supported instruction set
if (iset >= 9) myfunc_pointer = &myfunc_AVX512; // AVX512 version
else if (iset >= 8) myfunc_pointer = &myfunc_AVX2; // AVX2 version
else if (iset >= 7) myfunc_pointer = &myfunc_AVX; // AVX version
else if (iset >= 5) myfunc_pointer = &myfunc_SSE41; // SSE4.1 version
else if (iset >= 2) myfunc_pointer = &myfunc_SSE2; // SSE2 version
else {
// Error: lowest instruction set not supported (put your own error message here:)
fprintf(stderr, "\nError: Instruction set SSE2 not supported on this computer");
return 0.f;
}
// continue in dispatched version
return (*myfunc_pointer)(f);
}
// Entry to dispatched function call
inline float myfunc(float * f) {
return (*myfunc_pointer)(f); // go to dispatched version
}
// Example: main calls myfunc
int main(int argc, char* argv[])
{
float a[16]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16}; // array of 16 floats
float sum = myfunc(a); // call function with dispatching
printf("\nsum = %8.3f \n", sum); // print result
return 0;
}
#endif // INSTRSET == 2
#ifdef VCL_NAMESPACE
}
#endif
|
