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Re: [Bug tree-optimization/37312] -Os significantly faster than -O2 on test case
- From: Andrew Thomas Pinski <pinskia at gmail dot com>
- To: "gcc-bugzilla at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- Cc: "gcc-bugs at gcc dot gnu dot org" <gcc-bugs at gcc dot gnu dot org>
- Date: Mon, 1 Sep 2008 13:40:01 -0700
- Subject: Re: [Bug tree-optimization/37312] -Os significantly faster than -O2 on test case
- References: <bug-37312-7834@http.gcc.gnu.org/bugzilla/> <20080901143614.26759.qmail@sourceware.org>
This is mostly because of extra register moves that IRA some times
introduces. There is another bug about Inline-asm and the return
register.
Sent from my iPhone
On Sep 1, 2008, at 7:36, "rguenth at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org
> wrote:
------- Comment #4 from rguenth at gcc dot gnu dot org 2008-09-01
14:36 -------
Well, now -Os -funroll-all-loops doesn't do any unrolling anymore
while it did
before. With -O2 you get what you ask for - unrolled loops.
-funroll-all-loops isn't really a flag to be used in general.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37312