https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71335
Bug ID: 71335 Summary: wrong code at -O2 and -O3 in 32-bit and 64-bit modes on x86_64-linux-gnu Product: gcc Version: 6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: chengniansun at gmail dot com Target Milestone: --- $: gcc-trunk -v Using built-in specs. COLLECT_GCC=gcc-trunk COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../gcc-source-trunk/configure --enable-languages=c,c++,lto --prefix=/usr/local/gcc-trunk --disable-bootstrap Thread model: posix gcc version 7.0.0 20160529 (experimental) [trunk revision 236861] (GCC) $: gcc-trunk small.c -O3 -m64 ; timeout -s 9 2 ./a.out Killed $: gcc-trunk small.c -O2 -m64 ; timeout -s 9 2 ./a.out Killed $: gcc-trunk small.c -Os -m64 ; timeout -s 9 2 ./a.out $: cat small.c int a; int main() { int b = 0; while (a < 0 || b) { b = 0; for (; b < 9; b++) ; } return 0; } $: