https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77605
Bug ID: 77605 Summary: wrong code at -O3 on x86_64-linux-gnu Product: gcc Version: 7.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: su at cs dot ucdavis.edu Target Milestone: --- This seems to affect at least all versions 4.6.x and later. $ 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 20160915 (experimental) [trunk revision 240161] (GCC) $ $ gcc-trunk -O2 small.c; ./a.out $ $ gcc-trunk -O3 small.c $ ./a.out Aborted (core dumped) $ ---------------------------------------- int a, b, c[2][8]; int main () { for (a = 0; a < 8; a++) for (b = 0; b < 2; b++) c[b][a] = c[b][b + 6] ^ 1; if (c[0][7] != 0) __builtin_abort (); return 0; }