http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60452
Bug ID: 60452 Summary: wrong code at -O1 and above on x86_64-linux-gnu (affecting trunk and 4.8.x) Product: gcc Version: 4.9.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: su at cs dot ucdavis.edu The current gcc trunk and 4.8.x mis-compile the following code on x86_64-linux at -O1 in both 32-bit and 64-bit modes. This is a regression from 4.7.x. $ gcc-trunk -v Using built-in specs. COLLECT_GCC=gcc-trunk COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ../gcc-trunk/configure --prefix=/usr/local/gcc-trunk --enable-languages=c,c++ --disable-werror --enable-multilib Thread model: posix gcc version 4.9.0 20140306 (experimental) [trunk revision 208366] (GCC) $ $ gcc-trunk -O0 small.c; a.out $ gcc-trunk -O2 small.c; a.out $ gcc-4.7.3 -O1 small.c; a.out $ $ gcc-trunk -O1 small.c; a.out Segmentation fault (core dumped) $ gcc-4.8.2 -O1 small.c; a.out Segmentation fault (core dumped) $ ------------------------------- int a, c, d; short b; void fn1 (int p) { } int fn2 () { return 0; } int main () { int e[2] = { 0, 0 }; for (; b < 1; b++) { for (; c;) if (e[0]) break; fn1 (e[b]); for (; c; c++) e[0] = 0; d = fn2 (); if (b == (d | 2837)) a = e[b]; } return 0; }