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Re: [PATCH] Don't unnecessarily align stack in leaf functions if frame size is zero (PR middle-end/47581)
- From: Nathan Froyd <froydnj at codesourcery dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: Uros Bizjak <ubizjak at gmail dot com>, Richard Henderson <rth at redhat dot com>, gcc-patches at gcc dot gnu dot org, "H.J. Lu" <hjl dot tools at gmail dot com>
- Date: Wed, 2 Feb 2011 06:22:01 -0800
- Subject: Re: [PATCH] Don't unnecessarily align stack in leaf functions if frame size is zero (PR middle-end/47581)
- References: <20110202141849.GN30899@tyan-ft48-01.lab.bos.redhat.com>
On Wed, Feb 02, 2011 at 03:18:49PM +0100, Jakub Jelinek wrote:
> i?86 -m32 -O2 for:
> unsigned mulh(unsigned a, unsigned b)
> {
> return ((unsigned long long)a * (unsigned long long)b) >> 32;
> }
> completely unnecessarily subtracts 4 from %esp and adds it back after a few
> insns:
We have had a number of issues in this area; could you please add a
testcase for this so we can catch regressions earlier next time?
-Nathan