The following two testcases should produce the same code after forwprop1: struct foo { int i[3]; };
void bar (void) { struct foo Foo; int i; for (i=0; i<3; ++i) { void *p = &Foo.i[i]; int *pi = (int *)p; if (pi != 0) { *pi = 0; } } } --- struct foo { int i[3]; }; void bar (void) { struct foo Foo; int i; for (i=0; i<3; ++i) { void *p = &Foo.i[i]; int *pi = (int *)p; if (p != 0) { *pi = 0; } } } (the difference is testing p != 0 vs. pi != 0) This happens in tramp3d-v4 via placement new: for (i=0; i<3; ++i) new (&a[i]) double; where placement new expands to the "wrong" test sequence. Mine. -- Summary: forwprop does not look through casts Product: gcc Version: 4.3.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: enhancement Priority: P3 Component: tree-optimization AssignedTo: rguenth at gcc dot gnu dot org ReportedBy: rguenth at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31146