http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51357
Bug #: 51357
Summary: Simple program crash when enabling AVX
Classification: Unclassified
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: critical
Priority: P3
Component: c
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: cdub...@gmail.com
Created attachment 25953
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25953
Preprocessed version
This simple program (I attached the preprocessed version):
#include <stdlib.h>
#include <stdio.h>
void conv(const float* x, const int m,
const float* y, const int n,
float* z)
{
int i, j;
float sum;
for (i = 0; i < m - n + 1; ++i) {
sum = 0.0f;
for (j = 0; j < n - 3; j += 4) {
sum += x[i + j + 0] * y[j + 0];
sum += x[i + j + 1] * y[j + 1];
sum += x[i + j + 2] * y[j + 2];
sum += x[i + j + 3] * y[j + 3];
}
z[i] = sum;
}
}
int main()
{
const int m = 128000;
const int n = 64;
float* x = (float*)malloc(m * sizeof(float));
float* y = (float*)malloc(n * sizeof(float));
float* z = (float*)malloc((m - n + 1) * sizeof(float));
conv(x, m, y, n, z);
printf("%f\n", z[0]);
free(x);
free(y);
free(z);
}
Crash if I compile it with gcc 4.6.2 (and gcc 4.6.1) optimizations turned on
(-O2) and if I enable AVX (-march=corei7-avx).
It works without optimizations (or with only -Os) or without AVX
(-march=corei7).
I use the latest Apple clang assembler (included with XCode 4.2.1).
Here is the output of gcc -v:
MacBook-Pro-2:main charles$ gcc-4.6 -v -save-temps -march=corei7-avx -O2
main.cpp
Using built-in specs.
COLLECT_GCC=gcc-4.6
COLLECT_LTO_WRAPPER=/usr/local/Cellar/gcc/4.6.2/gcc/libexec/gcc/x86_64-apple-darwin11.2.0/4.6.2/lto-wrapper
Target: x86_64-apple-darwin11.2.0
Configured with: ../configure
--enable-languages=c,c++,fortran,java,objc,obj-c++
--prefix=/usr/local/Cellar/gcc/4.6.2/gcc
--datarootdir=/usr/local/Cellar/gcc/4.6.2/share
--bindir=/usr/local/Cellar/gcc/4.6.2/bin --program-suffix=-4.6
--with-gmp=/usr/local/Cellar/gmp/5.0.2 --with-mpfr=/usr/local/Cellar/mpfr/3.1.0
--with-mpc=/usr/local/Cellar/libmpc/0.9 --with-system-zlib
--enable-stage1-checking --enable-plugin --enable-lto --disable-nls
--disable-fully-dynamic-string
Thread model: posix
gcc version 4.6.2 (GCC)
COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.7.2' '-v' '-save-temps'
'-march=corei7-avx' '-O2'
/usr/local/Cellar/gcc/4.6.2/gcc/libexec/gcc/x86_64-apple-darwin11.2.0/4.6.2/cc1plus
-E -quiet -v -D__DYNAMIC__ main.cpp -fPIC -mmacosx-version-min=10.7.2
-march=corei7-avx -O2 -fpch-preprocess -o main.ii
ignoring nonexistent directory
"/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2/../../../../x86_64-apple-darwin11.2.0/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2/../../../../include/c++/4.6.2
/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2/../../../../include/c++/4.6.2/x86_64-apple-darwin11.2.0
/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2/../../../../include/c++/4.6.2/backward
/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2/include
/usr/local/include
/usr/local/Cellar/gcc/4.6.2/gcc/include
/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2/include-fixed
/usr/include
/System/Library/Frameworks
/Library/Frameworks
End of search list.
COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.7.2' '-v' '-save-temps'
'-march=corei7-avx' '-O2'
/usr/local/Cellar/gcc/4.6.2/gcc/libexec/gcc/x86_64-apple-darwin11.2.0/4.6.2/cc1plus
-fpreprocessed main.ii -fPIC -quiet -dumpbase main.cpp
-mmacosx-version-min=10.7.2 -march=corei7-avx -auxbase main -O2 -version -o
main.s
GNU C++ (GCC) version 4.6.2 (x86_64-apple-darwin11.2.0)
compiled by GNU C version 4.6.2, GMP version 5.0.2, MPFR version 3.1.0, MPC
version 0.9
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++ (GCC) version 4.6.2 (x86_64-apple-darwin11.2.0)
compiled by GNU C version 4.6.2, GMP version 5.0.2, MPFR version 3.1.0, MPC
version 0.9
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: b1d97ab7cd7bb3a1ba06b8ac1d280faa
COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.7.2' '-v' '-save-temps'
'-march=corei7-avx' '-O2'
as -arch x86_64 -force_cpusubtype_ALL -o main.o main.s
COMPILER_PATH=/usr/local/Cellar/gcc/4.6.2/gcc/libexec/gcc/x86_64-apple-darwin11.2.0/4.6.2/:/usr/local/Cellar/gcc/4.6.2/gcc/libexec/gcc/x86_64-apple-darwin11.2.0/4.6.2/:/usr/local/Cellar/gcc/4.6.2/gcc/libexec/gcc/x86_64-apple-darwin11.2.0/:/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2/:/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/
LIBRARY_PATH=/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2/:/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2/../../../:/usr/lib/
COLLECT_GCC_OPTIONS='-mmacosx-version-min=10.7.2' '-v' '-save-temps'
'-march=corei7-avx' '-O2'
/usr/local/Cellar/gcc/4.6.2/gcc/libexec/gcc/x86_64-apple-darwin11.2.0/4.6.2/collect2
-dynamic -arch x86_64 -macosx_version_min 10.7.2 -weak_reference_mismatches
non-weak -o a.out -lcrt1.10.5.o
-L/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2
-L/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2/../../..
main.o -no_compact_unwind -lSystem -lgcc_ext.10.5 -lgcc -lSystem -v
collect2 version 4.6.2 (x86_64 Darwin)
/usr/bin/ld -dynamic -arch x86_64 -macosx_version_min 10.7.2
-weak_reference_mismatches non-weak -o a.out -lcrt1.10.5.o
-L/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2
-L/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2/../../..
main.o -no_compact_unwind -lSystem -lgcc_ext.10.5 -lgcc -lSystem -v
@(#)PROGRAM:ld PROJECT:ld64-127.2
Library search paths:
/usr/local/Cellar/gcc/4.6.2/gcc/lib/gcc/x86_64-apple-darwin11.2.0/4.6.2
/usr/local/Cellar/gcc/4.6.2/gcc/lib
/usr/lib
/usr/local/lib
Framework search paths:
/Library/Frameworks/
/System/Library/Frameworks/
It works if I do not unroll the inner loop, I guess because it is not using AVX
in that case.
Versions of the program using SSE or AVX intrinsics crash in the same
conditions.
