https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63602
Bug ID: 63602
Summary: Wrong code w/ -O2 -ftree-loop-linear
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: asolokha at gmx dot com
gcc produces wrong code w/ -ftree-loop-linear -O2 (and above) for the following
reduced case:
int sx;
int bn;
int vz = 1;
int *volatile n6 = &bn;
int
main(void)
{
for (int i = 0; i < 3; ++i) {
sx = vz;
vz = bn;
}
return sx;
}
It struck me first w/ gcc-4.10.0-alpha20140810, but today I've reproduced it w/
4.8.3, 4.9.1 and 5-alpha20141019, so I'm not marking it as a regression.
Expected results:
% gcc-5.0_alpha20141019 -O2 -o good 963b8772.c
% ./good
% echo $?
0
Actual results:
% gcc-5.0_alpha20141019 -O2 -ftree-loop-linear -o bad 963b8772.c
% ./bad
% echo $?
1
