https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70021
Bug ID: 70021
Summary: Test miscompiled with -O3 option for -march=core-avx2.
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: vsevolod.livinskij at frtk dot ru
Target Milestone: ---
Created attachment 37826
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37826&action=edit
Reproducer.
Test case produces incorrect result with -O3 option for -march=core-avx2.
Everything works fine with other march (-march=corei7-avx and -march=knl). Also
gcc version 4.9.4 (Revision=233763) and gcc version 5.3.1 (Revision=233763)
generate correct code.
Output:
> g++ small.cpp -o out -O3 -std=c++11 -march=core-avx2; ./out
13370567410841507191
> g++ small.cpp -o out -O2 -std=c++11 -march=core-avx2; ./out
16372995556503316667
GCC version:
> g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/gcc-trunk/bin/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../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
--with-pkgversion=Revision=233809 --enable-languages=c,c++,lto
--with-gmp=/gcc-trunk/gmp-6.1.0/bin --with-mpfr=/gcc-trunk/mpfr-3.1.3/bin
--with-mpc=/gcc-trunk/mpc-1.0.3/bin --prefix=/gcc-trunk/bin
Thread model: posix
gcc version 6.0.0 20160229 (experimental) (Revision=233809)
