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Re: [patch] expmed.c: Fix PR 23971 - slow synth_mult.
- From: Falk Hueffner <falk at debian dot org>
- To: Kazu Hirata <kazu at codesourcery dot com>
- Cc: gcc-patches at gcc dot gnu dot org, roger at eyesopen dot com
- Date: Wed, 21 Sep 2005 17:53:11 +0200
- Subject: Re: [patch] expmed.c: Fix PR 23971 - slow synth_mult.
- References: <200509211319.j8LDJRWp013164@sparrowhawk.codesourcery.com>
Kazu Hirata <kazu@codesourcery.com> writes:
> Here is the timing in seconds with the cross compiler to
> alpha-linux-gnu from x86_64-pc-linux-gnu.
>
> original patched diff(%)
> 6.939 0.686 -90.114 (wow!)
Actually, 0.6 seconds for one line of source still seems quite
excessive... While this patch certainly seems like a good idea, I'm
wondering whether we shouldn't just additionally put an upper limit to
the number of instructions generated, since it seems unlikely that
expanding a multiply to more than say 12 insns is really such a great
idea.
--
Falk