https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114552
Bug ID: 114552 Summary: wrong code at -O1 and above 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: --- It is a regression from 12.3, and affects 13.* and the trunk. Compiler Explorer: https://godbolt.org/z/bznEs9bao [656] % 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/14.0.1/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 14.0.1 20240401 (experimental) (GCC) [657] % [657] % gcctk -O0 small.c; ./a.out [658] % [658] % gcctk -O1 small.c [659] % ./a.out Segmentation fault [660] % [660] % cat small.c #pragma pack(1) struct a { short b; int c; }; struct d { struct a b; int e; }; short f, g, h; int i, j, o; const struct d k = {{1,0},0}; short *l = &h, *m = &g, *n = &f; void p() { *n = (o > 0) > o; } void q(struct a n) { j = 0; for (; j < 5; j++) i = *m = *l != 0; p(); } int main() { q(k.b); return 0; }