https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71403
Bug ID: 71403 Summary: wrong code (segfault) 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: --- The current gcc trunk miscompiles the following code on x86_64-linux-gnu at -O3 in both 32-bit and 64-bit modes. This is a regression from 6.1.x. $ 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 20160603 (experimental) [trunk revision 237059] (GCC) $ $ gcc-trunk -O2 small.c; ./a.out $ gcc-6.1 -O3 small.c; ./a.out $ $ gcc-trunk -O3 small.c $ ./a.out Segmentation fault (core dumped) $ ------------------------------------- char a, c; short b; int main () { unsigned d = 0; int e = 1; for (a = 0; a < 2; a++) { if (e) c--; for (; d < 2; d++) for (b = 0; b; b++) ; e = 0; } return 0; }