I noticed this while running a profiledbootstrap and looking through simplify-rtx.c. Take the following function: int f(int a) { return a*2-a; }
We don't optimizate a*2-a to just a on the tree level but do in combine, we do. -- Summary: fold does not fold a*2-a to a Product: gcc Version: 4.1.0 Status: UNCONFIRMED Keywords: missed-optimization, TREE Severity: enhancement Priority: P2 Component: middle-end AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: pinskia at gcc dot gnu dot org CC: gcc-bugs at gcc dot gnu dot org OtherBugsDependingO 19986 nThis: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23294