https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115152
Bug ID: 115152 Summary: wrong code at -O3 with "-fno-tree-fre -fno-tree-dominator-opts -fno-tree-loop-im" on x86_64-linux-gnu Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: zhendong.su at inf dot ethz.ch Target Milestone: --- This appears to be a regression from 12.*, and affects 13.* and later. Compiler Explorer: https://godbolt.org/z/cvM1TYd7h [598] % gcctk -v Using built-in specs. COLLECT_GCC=gcctk COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/15.0.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../gcc-trunk/configure --disable-bootstrap --enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk --enable-sanitizers --enable-languages=c,c++ --disable-werror --enable-multilib Thread model: posix Supported LTO compression algorithms: zlib gcc version 15.0.0 20240516 (experimental) (GCC) [599] % [599] % gcctk -O3 small.c; ./a.out [600] % [600] % gcctk -O3 -fno-tree-fre -fno-tree-dominator-opts -fno-tree-loop-im small.c [601] % ./a.out Aborted [602] % [602] % cat small.c int a, b, c, d; char e[1] = {1}; int main() { for (a = 0; a < 3; a++) for (b = 0; b < 2; b++) c = e[0] = e[0] ^ d; if (!c) __builtin_abort(); return 0; }