https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71438
Bug ID: 71438 Summary: wrong code at -O3 on x86_64-linux-gnu (by tree vectorizer) 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 testcase on x86_64-linux at -O3 in both 32-bit and 64-bit modes. This appears to be a tree vectorizer bug as it goes away with -fno-tree-vectorize. 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 20160606 (experimental) [trunk revision 237117] (GCC) $ $ gcc-trunk -O2 small.c; ./a.out $ gcc-6.1 -O3 small.c; ./a.out $ $ gcc-trunk -O3 small.c; ./a.out Aborted (core dumped) $ $ gcc-trunk -O3 -fno-tree-vectorize small.c; ./a.out $ ----------------------------------- int a, b, c, d; int main () { int e = d = 3; for (; d >= 0; d--) { c = e; e = a ^ (a && b) && 1; } if (c != 0) __builtin_abort (); return 0; }