This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]
Other format:	[Raw text]

Re: PATCH:[darwin] fix load of a misaligned double word

From: Bradley Lucier <lucier at math dot purdue dot edu>
To: Andrew Pinski <pinskia at physics dot uc dot edu>
Cc: Bradley Lucier <lucier at math dot purdue dot edu>, gcc-patches at gcc dot gnu dot org, fjahanian at apple dot com, dje at watson dot ibm dot com
Date: Mon, 22 Dec 2003 19:39:00 -0500
Subject: Re: PATCH:[darwin] fix load of a misaligned double word
References: <2CCD8331-34DE-11D8-B318-000A958F150A@math.purdue.edu> <C3C1F18B-34DF-11D8-BB55-000393A6D2F2@physics.uc.edu>

On Dec 22, 2003, at 7:34 PM, Andrew Pinski 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.

At the risk of exposing too much of my ignorance here, how can the assembler tell whether 3(r4) is not aligned on any 4-byte, 8-byte, etc., boundary? It depends on what is in r4, doesn't it?

Brad

Follow-Ups:
- Re: PATCH:[darwin] fix load of a misaligned double word
  - From: Andrew Pinski

References:
- Re: PATCH:[darwin] fix load of a misaligned double word
  - From: Bradley Lucier
- Re: PATCH:[darwin] fix load of a misaligned double word
  - From: Andrew Pinski

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]