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Re: PowerPC 64 x 32 bits performance

From: Robert Dewar <dewar at adacore dot com>
To: Alan Modra <amodra at bigpond dot net dot au>
Cc: Edmar Wienskoski <edmar at freescale dot com>,GCC Development <gcc at gcc dot gnu dot org>
Date: Mon, 07 Mar 2005 06:06:42 -0500
Subject: Re: PowerPC 64 x 32 bits performance
References: <5888D31A-7824-40AD-8113-714F759A1423@apple.com> <4228E84D.6030107@freescale.com> <20050307061526.GU15642@bubble.modra.org>

Alan Modra wrote:

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.


One general principle at work here is that there is no rule that 64-bit
code will be faster than 32-bit code. On the contrary, one generally
expects 32-bit code to be faster in many cases.

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

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