Hello,
I am unable to see the expected performance gain using vectorizatio on
powerPC using Linux Suse.
I've prepared a simple test and compiled it once with vectorization and once
without the vectorization flags. I'd appriciate if someone could point me as to
what Im doing wrong here.Bellow are the results of the test runs:
time ./TestNoVec 92200 8 89720 1000
real 0m23.549s
time ./TestVec 92200 8 89720 1000
real 0m22.845s
Here is the code:
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
typedef float ARRTYPE;
int main ( int argc, char *argv[] )
{
int m_nSamples = atoi( argv[1] );
int itBegin = atoi( argv[2] );
int itEnd = atoi( argv[3] );
int iSizeMain = atoi( argv[ 4 ] );
ARRTYPE *pSum1 = new ARRTYPE[ 100000 ];
ARRTYPE *pSum = new ARRTYPE[ 100000 ];
for ( int it = 0; it < m_nSamples; it++ )
{
pSum[ it ] = it / itBegin;
pSum1[ it ] = itBegin / ( it + 1 );
}
ARRTYPE *pVec1 = (ARRTYPE*) malloc (sizeof(ARRTYPE) *m_nSamples);
ARRTYPE *pVec2 = (ARRTYPE*) malloc (sizeof(ARRTYPE) *m_nSamples);
for ( int i = 0, j = 0; i < m_nSamples - 5; i++ )
{
for( int it = itBegin; it < itEnd; it++ )
pVec1[ it ] += pSum[ it ] + pSum1[ it ];
}
free( pVec1 );
free( pVec2 );
}
Compilation flag for No vectorization:
gcc -DTIXML_USE_STL -I /home/build/build -I /home/build/build -I. -I
/usr/local/include -I /usr/include -O3 -fomit-frame-pointer -mtune=powerpc
-falign-functions=16 -fprefetch-loop-arrays -fpeel-loops -funswitch-loops
-fPIC -mcpu=powerpc -m64 -fargument-noalias -funroll-loops
-ftree-vectorizer-verbose=7 -fdump-tree-vect-details -c -o Test.o Test.cpp
gcc -lpthread -lz -lm -lstdc++ -DTIXML_USE_STL -I /home/build/build -I
/home/build/build -I. -I /usr/local/include -I /usr/include -O3
-fomit-frame-pointer -mtune=powerpc -falign-functions=16 -fprefetch-loop-arrays
-fpeel-loops -funswitch-loops -fPIC -mcpu=powerpc -m64 -fargument-noalias
-funroll-loops -ftree-vectorizer-verbose=7 -fdump-tree-vect-details
-L/usr/local/lib64 -DTIXML_USE_STL -pthread -L. -L /home/build/build/lib64 -L
/home/build/build/lib64 -L /usr/lib64 -L /lib64 -L /opt/gnome/lib64 -o
TestNoVec Test.o
Compilation of vectorized code:
gcc -DTIXML_USE_STL -I /home/build/build -I /home/build/build -I. -I
/usr/local/include -I /usr/include -O3 -fomit-frame-pointer -mtune=powerpc
-falign-functions=16 -fprefetch-loop-arrays -fpeel-loops -funswitch-loops
-ftree-vectorize -fPIC -mcpu=powerpc -maltivec -mabi=altivec -m64
-fargument-noalias -funroll-loops -ftree-vectorizer-verbose=7
-fdump-tree-vect-details -c -o Test.o Test.cpp
gcc -lpthread -lz -lm -lstdc++ -DTIXML_USE_STL -I /home/build/build -I
/home/build/build -I. -I /usr/local/include -I /usr/include -O3
-fomit-frame-pointer -mtune=powerpc -falign-functions=16 -fprefetch-loop-arrays
-fpeel-loops -funswitch-loops -ftree-vectorize -fPIC -mcpu=powerpc -maltivec
-mabi=altivec -m64 -fargument-noalias -funroll-loops
-ftree-vectorizer-verbose=7 -fdump-tree-vect-details -L/usr/local/lib64
-DTIXML_USE_STL -pthread -L. -L /home/build/build/lib64 -L
/home/build/build/lib64 -L /usr/lib64 -L /lib64 -L /opt/gnome/lib64 -o TestVec
Test.o
--
Summary: Vectorization on power PC
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: eyal at geomage dot com
GCC build triplet: gcc (GCC) 4.3.0 20071124 (experimental)
GCC host triplet: PowerPC
GCC target triplet: PowerPC
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35117
