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[Bug rtl-optimization/50904] [4.7 regression] pessimization when -fno-protect-parens is enabled by -Ofast
- From: "ebotcazou at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 01 Dec 2011 19:53:15 +0000
- Subject: [Bug rtl-optimization/50904] [4.7 regression] pessimization when -fno-protect-parens is enabled by -Ofast
- Auto-submitted: auto-generated
- References: <bug-50904-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50904
Eric Botcazou <ebotcazou at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
CC|ebotcazou at gcc dot |
|gnu.org |
Component|tree-optimization |rtl-optimization
AssignedTo|unassigned at gcc dot |ebotcazou at gcc dot
|gnu.org |gnu.org
--- Comment #19 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-12-01 19:53:15 UTC ---
> lim3 was added as a "hack", now yes, cunroll needs ccp after it (but it's
> there in the form of DOM and VRP). It's a pass ordering issue that we
> cannot ever solve.
OK, but that doesn't explain why LIM isn't able to hoist the loads...
> Please - it seems like a missed optimization there, too.
More of an acknowledged limitation I'd say. And RTL passes aren't supposed to
be enhanced to plug holes in the Tree passes, but let's try anyway.