https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101885
Bug ID: 101885 Summary: wrong code at -O3 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: qrzhang at gatech dot edu Target Milestone: --- It appears a regression in gcc-10. gcc-9 works fine. $ gcc-trunk -v gcc version 12.0.0 20210812 (experimental) [master revision 01f8a8b48e5:0eb7800d242:04b4f3152593f85b05974528d1607619dd77d702] (GCC) $ gcc-trunk abc.c ; ./a.out 0 $ gcc-trunk -O3 abc.c ; ./a.out 3 $ cat abc.c int a = 3, c; short b = 5, d, f; volatile short e; int main() { f = 29; for (; f != 33; f++) { int g = a; if (b) if (a) { a = b = 0; for (; b <= 8; b++) ; } e; e; c = 0; for (; c != 14; ++c) e; } b = d; printf("", 8); printf("%d\n", a); }