This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug tree-optimization/28868] [4.0/4.1/4.2/4.3 Regression] Not eliminating the PHIs which have the same arguments
- From: "sebpop at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 5 Nov 2007 06:13:29 -0000
- Subject: [Bug tree-optimization/28868] [4.0/4.1/4.2/4.3 Regression] Not eliminating the PHIs which have the same arguments
- References: <bug-28868-6528@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #12 from sebpop at gmail dot com 2007-11-05 06:13 -------
Subject: Re: [4.0/4.1/4.2/4.3 Regression] Not elimintating the PHIs which have
the same arguments
> Replacing ssa names with other ssa names willy-nilly is not always a
> win. We eventually ended up with heuristics to not change loop depths
> of ssa names, etc.
>
See also PR23821, where we reach the exact same conclusion:
DOM and VRP are playing the replace SSA_NAMEs game, and
we're losing to this game as the substitution is done randomly...
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28868