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Re: powerpc & unaligned block moves with fp registers
- To: Mark Mitchell <mark at codesourcery dot com>
- Subject: Re: powerpc & unaligned block moves with fp registers
- From: David Edelsohn <dje at watson dot ibm dot com>
- Date: Fri, 09 Nov 2001 09:52:29 -0500
- cc: Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>, "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
>>>>> Mark Mitchell writes:
Mark> I would prefer to see GCC just ask the back end "How do you want to
Mark> perform a memory-to-memory copy of thus and such many bits, knowing
Mark> thus and such about the current alignment of the memory?"
And I consider BLKmode move (movstrsi, etc.) the way to do that.
It already provides an alignment and number of bytes. On PowerPC, BLKmove
chooses the most efficient method, including using DImode.
One could call BLKmode move always, but my model was using
SLOW_UNALIGNED_ACCESS to determine when the backend considred things
"complicated" or "non-obvious" that the common code should punt to BLKmode