https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109778
Bug ID: 109778 Summary: Wrong code at -O3 on x86_64-linux-gnu since GCC-12.2 Product: gcc Version: 14.0 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 trunk at -O3 emits wrong code. This seems to be a bug since gcc-12.2 Compiler explorer: https://godbolt.org/z/E5aqnMK6Y $ cat a.c int printf(const char *, ...); int a, b, c, d; int *e = &c; unsigned f(unsigned char g) { g = 1 | g << 1; g = g >> 4 | g << 4; return g; } void h(unsigned g) { *e = 8 > f(g + 86) - 86; } int main() { d = a && b; h(d + 4); printf("%d\n", c); } $ $ gcc-tk -O0 a.c && ./a.out 1 $ gcc-tk -O3 a.c && ./a.out 0 $ $ gcc-tk -v Using built-in specs. COLLECT_GCC=gcc-tk COLLECT_LTO_WRAPPER=/zdata/shaoli/compilers/ccbuilder-compilers/gcc-b7fe38c14e5f1bc32950c7b2ffc8537c7c381af4/libexec/gcc/x86_64-pc-linux-gnu/14.0.0/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-b7fe38c14e5f1bc32950c7b2ffc8537c7c381af4 Thread model: posix Supported LTO compression algorithms: zlib gcc version 14.0.0 20230506 (experimental) (GCC) $