https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71887
Bug ID: 71887 Summary: wrong code (SIGFPE) at -O1 and above on x86_64-linux-gnu (in both 32-bit and 64-bit modes) Product: gcc Version: 7.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: rtl-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 -O1 and above 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 20160714 (experimental) [trunk revision 238331] (GCC) $ $ gcc-trunk -O0 small.c; ./a.out $ gcc-6.1 -O1 small.c; ./a.out $ $ gcc-trunk -O1 small.c $ ./a.out Floating point exception (core dumped) $ ------------------------------------ char a; int b; int main () { unsigned char c = a, d = a; b = d == 0 ? c : c % d; return 0; }