https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111916
Bug ID: 111916 Summary: wrong code at -O1 and above on x86_64-linux-gnu (the generated code hangs) 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 recent regression. Compiler Explorer: https://godbolt.org/z/aEEKbdY6E [563] % 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/14.0.0/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 14.0.0 20231022 (experimental) (GCC) [564] % [564] % gcctk -O0 small.c; ./a.out [565] % [565] % gcctk -O1 small.c [566] % timeout -s 9 5 ./a.out Killed [567] % [567] % cat small.c #pragma pack(1) struct A { int b : 4; int c : 11; int d : 2; int e : 5; } f; int main() { struct A g = {1, 1, 1, 1}; while (!g.b) f = g; return 0; }