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

[Roger Sayle]

On Wed, 14 Jul 2004, Richard Henderson wrote:
> On Wed, Jul 14, 2004 at 07:53:01PM -0600, Roger Sayle wrote:
> > Is this doable?
>
> It would be *possible*, but would be quite a lot of code to get right.

Would it be significantly easier just to treat %ebp as a "real" fixed
register.  Either saved and restored in functions with a frame-pointer,
or completely unused in functions without?  This should limit the changes
to prologue/epilogue generation, and perhaps tweaking register classes.

Less pretty, but safer (i.e. avoids your "a lot of code to get right").


> I'm not sure that it's worth it.

The benchmarking results are compelling.  I'll time some bootstraps to
determine how many minutes it shaves off of a full bootstrap.

Roger
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