https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102149
Bug ID: 102149 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: --- Seems to be a recent regression. $ gcc-trunk -v gcc version 12.0.0 20210831 (experimental) [master revision 5e57bacf6f3:a82c79a304b:de7a795c321e76826d123c92b99e73e144666b60] (GCC) $ gcc-trunk abc.c ; ./a.out 1 $ gcc-trunk abc.c ; ./a.out 0 $ cat abc.c int a[8]; int *b = &a[6]; char c; int main() { int d = 7; for (; d >= 0; d--) { *b = 1; c = a[d] >> 3; a[d] = c; } printf("%d\n", a[6]); }