Re: [PATCH 03/13] jump label v9: x86 support

From: Andi Kleen
Date: Thu Jun 10 2010 - 10:28:32 EST

On Thu, Jun 10, 2010 at 04:12:11PM +0200, Peter Zijlstra wrote:
> On Thu, 2010-06-10 at 15:26 +0200, Andi Kleen wrote:
> > The code generated by -Os is often terrible.
> Is anybody on the gcc side of things looking into curing that?

The problem is that the smallest code is often terrible.
You could often be much better with spending a few more bytes.
But -Os means "smallest"

On the other hand -Os could be likely made smaller
(it often still is not very good), but I fear that would
make things even worse.

We probably would need a -Osmall-but-not-terrible or so,
but that's not there.
> I mean, what's the point of having an -Os if its useless in practise.

I think __hot / __cold but keeping the default at -O2 is a better
approach anyways. Hot paths should be -O2. It just needs some more work.

It already works for __init/__exit at least.

ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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