Re: Unomitted frame pointers

["Sam Lauber" <sam124 at operamail dot com>]

Then why does -fomit-frame-pointer work on x86 at all? Then that option to omit a frame pointer shall be omitted ;). At least on x86. As for ABI, I simply don't understand this kind of stuff, because there is not enough information and documentation, and I don't have the time to check out the GCC source tree every time I want to look at something. And I _still_ don't recall any warning. I ran strings on GCC, and the only thing I saw was in the builtin specs saying "-pg and -fomit-frame-pointer are incompatible". You must be using 4.0 or 3.3. Why does it have to dynamically align the frame pointer? And _I'm_ not using an old 8086, I've got a Pentium III! I find your comment a bit insulting. And what's the valid reason this time?

Samuel Lauber

----- Original Message -----
From: "Eric Botcazou" <ebotcazou@libertysurf.fr>
To: "Sam Lauber" <sam124@operamail.com>
Subject: Re: Unomitted frame pointers
Date: Sat, 11 Dec 2004 09:08:31 +0100

> 
> > What messages?
> 
> I already posted the same advice once.
> 
> >  I HAD to call my function main, because it was main.
> 
> You don't understand.  Don't do your experiment on a function called 'main',
> it is very special in C.  The bottom line is that it must dynamically align
> the stack pointer on x86 because of an antiquated ABI, thus preventing
> -fomit-frame-pointer to be effective.
> 
> And keep in mind that GCC has been working on x86 for more than 15 years, so
> it can't do as dumb things as you think it does.  There is almost always a
> valid reason.
> 
> --
> Eric Botcazou

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