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Re: [PATCH] PR 16373: -fomit-frame-pointer when optimizing on x86
- From: Roger Sayle <roger at eyesopen dot com>
- To: Andi Kleen <ak at muc dot de>
- Cc: gcc at gcc dot gnu dot org
- Date: Sun, 11 Jul 2004 22:02:40 -0600 (MDT)
- Subject: Re: [PATCH] PR 16373: -fomit-frame-pointer when optimizing on x86
On Mon, 12 Jul 2004, Andi Kleen wrote:
> Roger Sayle <roger@eyesopen.com> writes:
>
> > On Sun, 11 Jul 2004, Joseph S. Myers wrote:
> >> Performance statistics (compile time, run time and code size)? After all,
> >> the point of this change is presumably that it improves performance.
> >
> > Do you have any doubt at all that this patch won't improve run-time,
> > reduce code size and speed up a bootstrapped compiler? :>
>
> It won't reduce code size - ebp references are smaller than esp
> references. This means if the function does more than four or five
> local variable references it will be bigger.
>
> But it will be likely faster.
Please see the following posting that presents the experimental results
showing the overall code size reduction on GCC's CSiBE benchmarks:
http://gcc.gnu.org/ml/gcc-patches/2004-07/msg01181.html
Roger
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