On Core2 ix86 machine following case (reduced from cpu2000.mcf) runs 50% slower if compiled with trunk -mtune=core2 -O2
unsigned int g_i,g_j; unsigned int g_a=1,g_b; void __attribute__((noinline)) foo() { do { if (g_a & g_i) {g_i++;} else {g_j++;} } while (g_b--); } int main() { int i; for (i=0; i<4; i++) { g_b=0x7fffffff; foo(); } return 0; } -- Summary: Performance regression with -mtune=core2 Product: gcc Version: 4.4.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: rtl-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: Joey dot ye at intel dot com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37571