Gentoo Archives: gentoo-embedded

From: Tuurlijk <ldx@××××××××.org>
To: gentoo-embedded@l.g.o
Subject: Re: [gentoo-embedded] x86 SBC Gentoo Embedded HotTo version 0.08
Date: Thu, 22 Sep 2005 07:19:08
In Reply to: Re: [gentoo-embedded] x86 SBC Gentoo Embedded HotTo version 0.08 by Natanael Copa
Op 21-sep-05 om 17:44 heeft Natanael Copa het volgende geschreven:
> > From the gcc man page: > -O also turns on -fomit-frame-pointer on machines where doing so > does not interfere with debugging. > > If I have undestood this correctly, -fomit-frame-pointer does interfere > with debugging on x86 so -O does not turn it on. > > In other words: On x86 -Os does not turn on -fomit-frame-pointer. > > Correct me if I'm wrong.
On closer inspection, this appears to be correct indeed. I was misled by: -fomit-frame-pointer Don't keep the frame pointer in a register for functions that don't need one. This avoids the instructions to save, set up and restore frame pointers; it also makes an extra register available in many functions. It also makes debugging impossible on some machines. On some machines, such as the VAX, this flag has no effect, because the standard calling sequence automatically handles the frame pointer and nothing is saved by pretending it doesn't exist. The machine-description macro "FRAME_POINTER_REQUIRED" controls whether a target machine supports this flag. Enabled at levels -O, -O2, -O3, -Os.


Subject Author
Re: [gentoo-embedded] x86 SBC Gentoo Embedded HotTo version 0.08 Natanael Copa <mlists@××××××.org>