http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52943
Bug #: 52943 Summary: likely wrong code bug Classification: Unclassified Product: gcc Version: 4.8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassig...@gcc.gnu.org ReportedBy: reg...@cs.utah.edu CC: cheny...@cs.utah.edu [regehr@dyson r23]$ current-gcc -O2 small.c ; ./a.out 0 [regehr@dyson r23]$ current-gcc -O3 small.c ; ./a.out 1 [regehr@dyson r23]$ cat small.c int printf (const char *, ...); int a[] = { 0, 0, 0, 6 }; int b; int main () { for (;;) { b = 3; for (; b; b -= 1) a[b] = a[3] > 1; break; } printf ("%d\n", a[1]); return 0; } [regehr@dyson r23]$ current-gcc -v Using built-in specs. COLLECT_GCC=current-gcc COLLECT_LTO_WRAPPER=/uusoc/exports/scratch/regehr/z/compiler-install/gcc-r186359-install/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.8.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ../configure --with-libelf=/usr/local --enable-lto --prefix=/home/regehr/z/compiler-install/gcc-r186359-install --program-prefix=r186359- --enable-languages=c,c++ Thread model: posix gcc version 4.8.0 20120411 (experimental) (GCC)