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[Bug tree-optimization/37312] -Os significantly faster than -O2 on test case
- From: "andi-gcc at firstfloor dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 1 Sep 2008 14:20:21 -0000
- Subject: [Bug tree-optimization/37312] -Os significantly faster than -O2 on test case
- References: <bug-37312-7834@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #3 from andi-gcc at firstfloor dot org 2008-09-01 14:20 -------
Thanks for the us^whelpful comment. If you can suggest a way to do carry
preserving addition without inline assembler that would be fine, otherwise not.
-Os seems to do something that improves it at least (and that is new in 4.4,
4.3 didn't do that)
I suppose -O2 does something more that makes it then worse again.
I merely filled it because I thought it would be interesting to fix that
something to not pessimize code.
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37312