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Re: About Regmove !!
- From: Michael Matz <matz at suse dot de>
- To: tm <tm at mail dot kloo dot net>
- Cc: <law at redhat dot com>, <joern dot rennecke at superh dot com>, <gcc at gcc dot gnu dot org>
- Date: Wed, 13 Nov 2002 13:32:24 +0100 (CET)
- Subject: Re: About Regmove !!
Hi,
On Tue, 12 Nov 2002, tm wrote:
> Is there a particular reference you have in mind which covers handling
> addressing inheritance in GCSE?
>
> To me, it seems very awkward to have address inheritance handled by GCSE.
>
> In order to generate efficient address inheritance, the addressing mode of
> an instruction may need to be changed. This implies GCSE will need to
> understand all of the target CPU's addressing modes and allowable
> displacements for each one.
I just want to mention that the current regmove doesn't have any of this
information also, and still is effective enough (at least it seems so from
your words). What's more, it even only reduces the constants under some
fairly narrow constraints (only when both operands have to match in some
insn). So any optimization doing this probably doesn't need to be _that_
much more intelligent than the current regmove as far as target
dependencies are concerned.
Ciao,
Michael.