http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47831
Ian Bolton <ibolton at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Status|UNCONFIRMED |NEW
Last reconfirmed| |2011.02.22 14:50:03
CC| |ibolton at gcc dot gnu.org
Ever Confirmed|0 |1
Known to fail| |4.6.0
--- Comment #1 from Ian Bolton <ibolton at gcc dot gnu.org> 2011-02-22 14:50:03
UTC ---
Confirmed on r170278 of trunk.
The better sequence that Carrot mentions comes from having if-conversion
disabled (-fno-if-conversion2).
I expect Basic Block Reordering might be able to help out in the case where
if-conversion is enabled, but I think it is still disabled for -Os, as it can
sometimes lead to larger code.
That is a separate issue though. To tackle this properly, the if-conversion
heuristic would need to be enhanced to detect cases where the codesize will
likely increase and pessimise against those cases when using -Os.
