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Re: rs6000 fused multiply-add patch [+ patchlet]
- From: Segher Boessenkool <segher at koffie dot nl>
- To: Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Sun, 12 Jan 2003 02:25:57 +0100
- Subject: Re: rs6000 fused multiply-add patch [+ patchlet]
- References: <10301100218.AA27058@vlsi1.ultra.nyu.edu>
Richard Kenner wrote:
>
> Reducing the amount of rtl isn't the same as improving performance.
>
> No, but unless the MD file has a serious problem, it is *one way* of
> improving performance.
I don't dispute that.
> There's no question that we don't current have a pass which is good at
> finding the simplest form of the RTL. The idea is to move as much of
> combine as possible into simplify-rtx.c.
It's on my todo list (it's in the beginner projects list).
> Then combine is very small and other passes will do what you are
> trying to do.
Part of it, maybe. But certainly not all, unless we run simplify
and combine over and over again until nothing changes anymore.
Segher