Take: struct a { union { int a; int b; }; union { int c; int d; }; };
int f(struct a *c) { int d = c->a; c->c = 1; return c->a + d; } --- CUT --- There should only be one load from c->a but currently there is two -- Summary: Union in structs are not well optimized Product: gcc Version: 4.4.0 Status: UNCONFIRMED Keywords: missed-optimization Severity: normal Priority: P3 Component: tree-optimization AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: pinskia at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38207