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Re: PATCH:[darwin] fix load of a misaligned double word
- From: Dale Johannesen <dalej at apple dot com>
- To: fj <fjahanian at apple dot com>
- Cc: Bradley Lucier <lucier at math dot purdue dot edu>, gcc-patches at gcc dot gnu dot org, Dale Johannesen <dalej at apple dot com>, dje at watson dot ibm dot com, Andrew Pinski <pinskia at physics dot uc dot edu>
- Date: Mon, 22 Dec 2003 17:37:28 -0800
- Subject: Re: PATCH:[darwin] fix load of a misaligned double word
- References: <2B7C4B0B-34E7-11D8-9FD0-003065D642C2@apple.com>
On Dec 22, 2003, at 5:27 PM, fj wrote:
This patch is fix the load/stores of double words (ld/std
instructions).
The PPC ISA defines them as being always using 4 byte aligned offsets.
So the patch was to fix the output of the right asm but it looks like
a side effect is that it the load and stores of doubles (lfd/stfd),
the offset
also get aligned which causes this performance problem.
Yes, we do this for both DImode and DFmode. It causes an extra 'addi'
for DFmode.
If this is not necessary we can take it out for DFmode. But this was
reviewed by
David and I would like him to comment on it first,
That is a pretty big performance hit on some code.