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Re: [PATCH] PPC assembly implementation of SHA1

From
BHBenjamin Herrenschmidt <benh@kernel.crashing.org>
Date
Apr 24, 2005, 02:49 UTC
Message-ID
<1114310968.5444.24.camel@gaston>
In-Reply-To
<20050423124246.30071.qmail@science.horizon.com>
On Sat, 2005-04-23 at 12:42 +0000, linux@horizon.com wrote:
Show 5 quoted lines
> - You don't need to decrement %r1 before saving registers.
>   The PPC calling convention defines a "red zone" below the
>   current stack pointer that is guaranteed never to be touched
>   by signal handlers or the like.  This is specifically for
>   leaf procedure optimization, and is at least 224 bytes.
On ELF ppc32 ABI ? Hrm... the SysV ABI document says

"The only permitted references with negative offsets from the stack pointer are those described here for establishing a stack frame."

I know MacOS had a red zone, but do we ?
> - Is that many stw/lwz instructions faster than stmw/lmw?
>   The latter is at least more cahce-friendly.
More cache friendly ? Hrm.. I wouldn't be sure. Also, I remember readind
a while ago that those store/load multiple instructions aren't that
recommended. They aren't very good on some CPU models. I would expect
the bus/cache bandwidth to be the limiting factor here anyway, and as
you point out below, the they don't deal with unaligned access very well
in all cases.
Previous: linux@horizon.comNext: Paul Mackerras
Message 3 of 17 in “Re: [PATCH] PPC assembly implementation of SHA1”
  1. linux@horizon.comApr 23, 2005
  2. linux@horizon.comApr 23, 2005
  3. Benjamin HerrenschmidtApr 24, 2005
  4. Paul MackerrasApr 24, 2005
  5. Wayne ScottApr 24, 2005
  6. linux@horizon.comApr 24, 2005
  7. Revised PPC assembly implementationlinux@horizon.com, Apr 25, 2005
  8. Paul MackerrasApr 25, 2005
  9. linux@horizon.comApr 25, 2005
  10. Paul MackerrasApr 25, 2005
  11. David S. MillerApr 25, 2005
  12. Paul MackerrasApr 26, 2005
  13. linux@horizon.comApr 27, 2005
  14. Paul MackerrasApr 27, 2005
  15. linux@horizon.comApr 27, 2005
  16. linux@horizon.comApr 26, 2005
  17. linux@horizon.comApr 26, 2005

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