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Re: [PATCH] PR 16373: -fomit-frame-pointer when optimizing on x86


On Sun, Jul 11, 2004 at 05:06:02PM -0600, Roger Sayle wrote:
> 
> I was orginally just going to ask whether there were any remaining
> hold-ups to enabling -fomit-frame-pointer by default when optimizing
> on IA-32.  More pro-actively, I thought I'd propose the following patch
> and see what people think.  The x86_64 targets in i386.c already do
> this by default, and with the variable tracking changes, gcc 3.5 will
> already require users to use a recent gdb 6.x for debugging.
> 
> 
> The following patch has been tested on i686-pc-linux-gnu with a full
> "make bootstrap", all default languages, and regression tested with a
> top-level "make -k check" with no new failures.  I'll admit that I've
> never run the gdb testsuite, but I'd hope that by now any regressions
> there would be considered problems with gdb :)
> 
> Ok for mainline?

Just search the archives for -fomit-frame-pointer i386.
This patch came up several times even this year.

I don't think we can turn -fomit-frame-pointer by default on unless
we also -fasynchronous-unwind-tables, because otherwise things like
glibc's backtrace(3) has zero chance of ever working.
Java heavily relies on this function, but several other programs as
well.  x86-64 which enables -fomit-frame-pointer by default
enables async unwind tables at the same time.

	Jakub


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