From: "Lawrence Rust" <lvr AT nospam DOT softsystem DOT co DOT uk>
Newsgroups: comp.os.msdos.djgpp
References: <zdZ19.3130$6j5 DOT 101432 AT newsfep2-win DOT server DOT ntli DOT net> <3d48a1d8$0$1421$272ea4a1 AT news DOT execpc DOT com>
Subject: Re: Prolog
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Date: Thu, 1 Aug 2002 10:23:15 +0100
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To: djgpp AT delorie DOT com
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"Chris Giese" <NoEmailAds AT execpc DOT com> wrote...
> "Lawrence Rust" <lvr AT nospam DOT softsystem DOT co DOT uk> wrote:
>
> >Is it possible to suppress the prolog and epilog code emitted by gcc in
an
> >extern function just consisting of asm statements?  E.g in:
> >
> >extern void foo( void)
> >{
> >  __asm__ __volatile ( "...");
> >}
> >
> >Even in an optimised (-O3) build the compiler emits:
> >
> > pushl %ebp
> > movl %esp,%ebp
> > ...
> > movl %ebp,%esp
> > popl %ebp
> > ret
>
> Maybe "gcc -fomit-frame-pointer ..." ?

Thanks, that suppresses the prolog for all functions in a file but I was
hoping that there might be a way to suppress it from within the source file,
either using an __attribute__() declaration or by a #pragma or something.

The problem is that the source is part of a library that will be compiled by
others and I can't guarantee that the final makefile will specify
'-fomit-frame-pointer'.  The function modifies the sp register so it's
important that the calling stack frame format is known.

Alternatively is there a way of determining a compile time if
'-fomit-frame-pointer' is on or off?

TIA

-- Lawrence Rust