Found this while trying to bootstrap with BOOT_CFLAGS="-O3 -fipa-cp" and it miscompiled libcpp/macro.c at the stage2. Appeared somewhere in between r122374 and r124593:
/* { dg-do run } */ /* { dg-options "-O3 -fipa-cp" } */ int k; void f1 (int a, int b) { if (a) while (b --) k = 1; else if (b != 1) __builtin_abort (); } int main (void) { f1 (1, 1); if (k != 1) __builtin_abort (); return 0; } -- Summary: [4.3 Regression] -fipa-cp miscompilation Product: gcc Version: 4.3.0 Status: UNCONFIRMED Keywords: wrong-code Severity: normal Priority: P3 Component: tree-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: belyshev at depni dot sinp dot msu dot ru http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33434