https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67689
Bug ID: 67689 Summary: wrong code at -O1, -O2 and -O3 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: su at cs dot ucdavis.edu Target Milestone: --- The current gcc trunk miscompiles the following code on x86_64-linux-gnu at -O1, -O2 and -O3 in both 32-bit and 64-bit modes. This is a regression from 5.2.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/6.0.0/lto-wrapper Target: x86_64-pc-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 6.0.0 20150922 (experimental) [trunk revision 228013] (GCC) $ $ gcc-trunk -O0 small.c; ./a.out $ gcc-5.2 -O1 small.c; ./a.out $ $ gcc-trunk -O1 small.c $ ./a.out Aborted $ ---------------------------------- int a, b, c = 1, d, e; void fn1 () { e = c >> b ? c : c << 1; for (b = 0; b < 1; b++) d = a ? 0 : e ^ 1; d = 0; } int main () { fn1 (); if (e != 1) __builtin_abort (); return 0; }