[Bug tree-optimization/23335] out of ssa does coalesce some variables

["pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-08-11 18:23 -------
What is happening is that out of SSA is doing almost no coalescing at all, it only coalesces SSA_NAME 
which have the same decl.

To me, it looks like copyrename is missing an opportunity to rename a SSANAME:
  # D.15690_3 = PHI <0(3), mult_41(12), D.15690_13(14), 0(0), mult_55(11), mult_28(13)>;


well it turns out this might be harder to do than orginally I had thought as one of the arguments to the 
PHI is does not have a SSA_NAME whos decl is mult.

This problem is understood but hard to get right.

I will try to get a small example for this issue, note this is also an issue in 4.0.0 too.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |minor
            Summary|out of ssa does not delete  |out of ssa does coalesce
                   |single def single use       |some variables
                   |variable                    |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23335