https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109934
Bug ID: 109934 Summary: Wrong code at -O3 on x86_64-linux-gnu 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: --- For the following code, gcc trunk at -O3 emits wrong code. Compiler explorer: https://godbolt.org/z/3E8xf69rP $ cat a.c int printf(const char *, ...); short a; long b = 3, c; int d(int e) { switch (e) case 111: case 222: case 44: return 0; return e; } int main() { for (; a >= 0; --a) if (d(c + 23) - 23) b = 0; printf("%d\n", (int)b); } $ $ gcc-tk -O0 a.c && ./a.out 3 $ 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-c09471fbc7588db2480f036aa56a2403d3c03ae5/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-c09471fbc7588db2480f036aa56a2403d3c03ae5 Thread model: posix Supported LTO compression algorithms: zlib gcc version 14.0.0 20230521 (experimental) (GCC) $