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Re: -Os for Darwin why?

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From:
Kay Roepke
Date:
February 18, 2003 05:58
Subject:
Re: -Os for Darwin why?
Message ID:
0DED1273-4349-11D7-BF21-00039355EB2E@dolphin-services.de

On Tuesday, February 18, 2003, at 06:46  AM, schwern@pobox.com wrote:

> On Mon, Feb 17, 2003 at 08:06:48PM -0800, Wilfredo Sánchez wrote:
>>    ProjectBuilder now defaults to -Os.
>>
>>    I bet you can find something on Tech Info Library, and the option 
>> is
>> documented in gcc(1).
>>
>>    I'm not sure we need to document every option in the hints file, 
>> but
>> OK.
>
> I understand what the option does, the man page explains that, I just
> didn't understand why it was being used to compile perl by default.
> Your reason for using it is valid, I just want to make sure Future
> Generations know why too.
>
> I still don't understand why its only used for Darwin 6.x and up and 
> not
> 5.x and down.  Could you explain?

This seems to be an issue with the gcc2.95 used in Darwin 5.x with 
respect to size optimizing.
Namely the release notes for gcc3 claim much improved -Os optimizing 
which is almost (but not quite) the same as
-O2.
The rationale is that swapping is way more expensive than CPU cycles, 
and therefore size matters! (Don't believe the hype ;-))
So I guess the -Os is more or less broken in the Apple gcc2.95.x 
release and thus not used.

Regards,

Kay

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