The following code gives wrong result with -O2 and above :
% gcc -O0 -o example example.c && ./example
1
% gcc -O2 -o example example.c && ./example
0
The bug is triggered on i486 platform, with gcc 4.3.2 but not with gcc 4.1.2.
#include <stdio.h>
int main(void) {
volatile int y;
int x;
y = 0x80000000;
x = y;
if (x < 0)
x = -x;
printf("%d\n", x == 0x80000000);
return 0;
}
--
Summary: Optimized code gives wrong result
Product: gcc
Version: 4.3.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: gabriel dot campana at free dot fr
GCC build triplet: i486-linux-gnu
GCC host triplet: i486-linux-gnu
GCC target triplet: i486-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39231
