Re: Problems Building 7.0-Beta3 with -Os

From: Alexander Leidinger <Alexander_at_Leidinger.net>
Date: Thu, 06 Dec 2007 08:43:42 +0100
Quoting Ruslan Ermilov <ru_at_freebsd.org> (from Thu, 6 Dec 2007 10:22:39 +0300):

> On Wed, Dec 05, 2007 at 03:16:28PM -0800, David O'Brien wrote:
>> [...]  -Os is a collection of
>> optimizations that is between -O1 and -O2.  That is -Os includes
>> everything that -O1 does, and -O2 includes everything that -Os does.
>> In otherwords:  -O1 < -Os < -O2   (properly)
>>
> I read it differently.  From the manpage:
>
> : -Os Optimize for size.  -Os enables all -O2 optimizations that do not
> :     typically increase code size.  It also performs further optimiza-
> :     tions designed to reduce code size.
>
> It says that -Os is a subset of -O2 optimizations plus some
> extra optimizations.  Reading further in a manpage, there's
> only one, -mspace.

And after the import of the new gcc in 7, a lot of people noticed,  
that the resulting binaries are larger with -Os than with -O2. This  
doesn't help for the original problem (not being able to compile  
FreeBSD), but gives a hint to prefer -O2 over -Os when the problem is  
found.

Bye,
Alexander.

-- 
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http://www.Leidinger.net    Alexander _at_ Leidinger.net: PGP ID = B0063FE7
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Received on Thu Dec 06 2007 - 06:52:52 UTC

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