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Re: powerpc & unaligned block moves with fp registers
- To: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- Subject: Re: powerpc & unaligned block moves with fp registers
- From: David Edelsohn <dje at watson dot ibm dot com>
- Date: Thu, 08 Nov 2001 16:11:01 -0500
- cc: gcc at gcc dot gnu dot org
>>>>> Richard Kenner writes:
> On some architectures, unaligned 64-bit loads and stores can cause
> alignment exceptions trapping to the OS to perform the load in pieces.
Richard> I think STRICT_ALIGNMENT should be true on such architectures.
I guess I did not explain this clearly enough. The DImode objects
do not need to be naturally aligned. Following the definition of
STRICT_ALIGNMENT to 0, these instructions will work, just work more
slowly.
We discussed STRICT_ALIGNMENT a few years ago and agreed that
STRICT_ALIGNMENT was not the solution. This is why we expanded
SLOW_UNALIGNED_ACCESS in the first place.
David