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Re: PowerPC 64 x 32 bits performance

From: Alan Modra <amodra at bigpond dot net dot au>
To: Edmar Wienskoski <edmar at freescale dot com>
Cc: GCC Development <gcc at gcc dot gnu dot org>
Date: Mon, 7 Mar 2005 16:45:26 +1030
Subject: Re: PowerPC 64 x 32 bits performance
References: <5888D31A-7824-40AD-8113-714F759A1423@apple.com> <4228E84D.6030107@freescale.com>

On Fri, Mar 04, 2005 at 04:59:25PM -0600, Edmar Wienskoski wrote:
> and notice a considerable number of load instructions in the 64 bits one.
> 
> Does anyone have an insight on why this is happening ?

These are most likey 64-bit address constant loads.  On ppc32, a 32-bit
address constant can be calculated in at most 2 instructions.  A 64-bit
address takes up to 5 instructions to calculate in-line, or a TOC memory
load.

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre

Follow-Ups:
- Re: PowerPC 64 x 32 bits performance
  - From: Robert Dewar

References:
- invoke.texi: reference to web page that does not exist
  - From: Devang Patel
- PowerPC 64 x 32 bits performance
  - From: Edmar Wienskoski

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