Re: MacIntel apps behaves weirdly when compiled with -02 not -01 - Almost solved(auto-vectorization issue)
Re: MacIntel apps behaves weirdly when compiled with -02 not -01 - Almost solved(auto-vectorization issue)
- Subject: Re: MacIntel apps behaves weirdly when compiled with -02 not -01 - Almost solved(auto-vectorization issue)
- From: Eric Albert <email@hidden>
- Date: Fri, 13 Jan 2006 09:16:52 -0800
On Jan 13, 2006, at 3:39 AM, Olivier Tristan wrote:
I've figured what the problem is, it's the auto vectorization feature
of gcc 4.
When optimization are below -02 , it's not used.
If I disable the auto vectorization, my code works fine again even in
-03.
I didn't use it on standard mac as I compile with gcc3 to support
10.2.8.
I really doubt that a I have a bug in my code which is only triggered
with this flag enabled, but still possible however.
Is there a know issue with xcode 2.2/macintel and auto-vectorization ?
The issue Arvan mentions is known and not yet fixed. I'm a little
surprised that -ftree-vectorize is on by default at -O2, since the man
page doesn't mention that. Can you confirm that and, if it's true,
file a bug report?
By the way, we recommend using -Os rather than -O2 or -O3. I'd suggest
trying that instead.
-Eric
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