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[Bug tree-optimization/23335] out of ssa does coalesce some variables
- From: "pinskia at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 11 Aug 2005 18:23:38 -0000
- Subject: [Bug tree-optimization/23335] out of ssa does coalesce some variables
- References: <20050811175402.23335.dann@godzilla.ics.uci.edu>
- Reply-to: gcc-bugzilla at gcc dot gnu dot 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