[Bug rtl-optimization/47270] [4.6/4.7/4.8 Regression] GCC produces unnecessary code on -O2 and -O3 levels

[steven at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47270

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-03-05
     Ever Confirmed|0                           |1

--- Comment #4 from Steven Bosscher <steven at gcc dot gnu.org> 2013-03-05 23:28:58 UTC ---
(In reply to comment #1)
> and RTL optimizations aren't able to undo that.  I doubt anything can
> be done about this easily.

Perhaps tree-ssa-uncprop should handle this.

FWIW, I've always thought that constant propagation into PHI arguments
was a mistake...