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Re: O flags
- From: Robert Mijakovic <mijakovi at in dot tum dot de>
- To: Segher Boessenkool <segher at kernel dot crashing dot org>
- Cc: gcc-help at gcc dot gnu dot org
- Date: Mon, 25 May 2015 07:52:24 +0200
- Subject: Re: O flags
- Authentication-results: sourceware.org; auth=none
- References: <55621552 dot 4080504 at in dot tum dot de> <20150524184622 dot GC21930 at gate dot crashing dot org>
Hi Segher,
Thank you for your answer. I have overlooked it while I have checked the
documentation.
I have expected to see something like that as optimizations are usually
applied in multiple
passes and there are dependencies between them. On the other hand, I
have expected to
see a way to specify multiple passes and all optimizations to be exposed
to users.
Best regards,
Robert
On 24.05.2015 20:46, Segher Boessenkool wrote:
On Sun, May 24, 2015 at 08:15:46PM +0200, Robert Mijakovic wrote:
I took optimizations enabled by O[1..3] and tried to enable them all at
once without calling
O flag levels. I have found out that improvements I got by using all
flags used by the
particular O flag level are not even close to what I would get by
explicitly using O flag levels.
That is a frequently asked question:
http://gcc.gnu.org/wiki/FAQ#optimization-options
Segher
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