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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: Fri, 02 Dec 2011 21:21:15 +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
--- Comment #35 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-12-02 21:21:15 UTC ---
> One thing I notice (and that's the only difference I can spot at the tree
> level) is that we do not CSE the **2s of
There are many missed hoisting opportunities, with or without the switch.
There are just a few more with the switch, hence the performance regression.