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Re: -fprefetch-loop-arrays and hardware prefetch

From: "Praveen Raghavan" <praveenr at gmail dot com>
To: "Zuxy Meng" <zuxy dot meng at gmail dot com>
Cc: gcc-help at gcc dot gnu dot org
Date: Fri, 27 Apr 2007 10:47:49 +0200
Subject: Re: -fprefetch-loop-arrays and hardware prefetch
References: <f0scid$8s5$1@sea.gmane.org>
Reply-to: praveenr at gmail dot com

Hi Zuxy,

There is a check made to see if the hardware supports prefetch if so
then the -fprefetch-loop-arrays flags is ignored. In many other
architectures this is still quite useful.
But currently I think the prefetch flag is always set to 0 in "loop.c".

Regards,
Praveen

On 4/27/07, Zuxy Meng <zuxy.meng@gmail.com> wrote:

Hi,

Modern x86/x86-64 CPUs support hardware prefetch if memory loads are in a
regular pattern, and software prefetch is recommended only when memory
access pattern is hard to determine by hardware. Does that
mean -fprefetch-loop-arrays is unnecessary on such CPUs?

--
Zuxy

References:
- -fprefetch-loop-arrays and hardware prefetch
  - From: Zuxy Meng

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