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[Bug target/70542] New: [6 Regression] Wrong code with -O3 -mavx2.
- From: "vsevolod.livinskij at frtk dot ru" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 05 Apr 2016 07:35:15 +0000
- Subject: [Bug target/70542] New: [6 Regression] Wrong code with -O3 -mavx2.
- Auto-submitted: auto-generated
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70542
Bug ID: 70542
Summary: [6 Regression] Wrong code with -O3 -mavx2.
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: vsevolod.livinskij at frtk dot ru
Target Milestone: ---
Created attachment 38187
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38187&action=edit
Reproducer.
Test case produces incorrect result with -O3 -mavx2 (and -march=knl and
-march=skylake-avx512. Everything works fine with gcc version 4.9.4 20160401
(prerelease) (Revision=234686) and gcc version 5.3.1 20160401
(Revision=234686).
Output:
g++ -O2 -mavx2 repr.cpp; ./a.out
1540
> g++ -O3 -mavx2 repr.cpp; ./a.out
1204
GCC version:
> g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/export/users/vlivinsk/gcc-trunk/bin/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /export/users/vlivinsk/gcc-trunk/gcc/configure
--with-arch=corei7 --with-cpu=corei7 --enable-clocale=gnu --with-system-zlib
--enable-shared --with-demangler-in-ld --enable-cloog-backend=isl
--with-fpmath=sse --enable-checking=release --enable-languages=c,c++,lto
--with-gmp=/export/users/vlivinsk/gcc-trunk/gmp-6.1.0/bin
--with-mpfr=/export/users/vlivinsk/gcc-trunk/mpfr-3.1.3/bin
--with-mpc=/export/users/vlivinsk/gcc-trunk/mpc-1.0.3/bin
--prefix=/export/users/vlivinsk/gcc-trunk/bin
Thread model: posix
gcc version 6.0.0 20160404 (experimental) (Revision=234705)
Test:
#include <cstdlib>
int a[520];
short b[482];
short c[480];
int d[963];
short e[320];
int main() {
for (int i = 0; i < 520; ++i)
a[i] = -636544305;
for (int i = 0; i < 386; ++i)
b[i] = -31804;
for (long i = 1; i <= 112; ++i) {
c[i] = b[i] >> ((a[i] & 1587842570) - 1510214139);
if (a[i])
d[i] = i;
e[i] = 7 << ((2312631697 - b[i]) - 2312663500);
}
unsigned long long g = 0;
for (int i = 0; i < 111; ++i) {
g = e[i] + g;
}
if (g != 1540)
abort();
}