https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107257
Bug ID: 107257 Summary: Wrong code at -O2 on x86_64-linux-gnu Product: gcc Version: 13.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: shaohua.li at inf dot ethz.ch Target Milestone: --- % gcc-tk -v Using built-in specs. COLLECT_GCC=gcc-tk COLLECT_LTO_WRAPPER=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-9f0d4adabe2035886a1aa8d2ca990a90de000613/libexec/gcc/x86_64-pc-linux-gnu/13.0.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: ../configure --disable-multilib --disable-bootstrap --enable-languages=c,c++ --prefix=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-9f0d4adabe2035886a1aa8d2ca990a90de000613 Thread model: posix Supported LTO compression algorithms: zlib gcc version 13.0.0 20221013 (experimental) (GCC) % % gcc-tk -w -O0 a.c && ./a.out 2 % gcc-tk -w -O2 a.c && ./a.out 0 % % cat a.c l; m; static signed char n(); s() { n(); } signed char n(u) { for (; u <= 2; u++) { l = 2; for (; l ; l--) { m = 2; for (; m; m--) if (u) break; } } } main() { s(2); printf("%d\n", m); } % Compiler explorer: https://godbolt.org/z/z5Mhxaz9E