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Re: [PATCH][PPC] Remove unnecessary local variable mptwo

From: Richard Henderson <rth at twiddle dot net>
To: Carlos O'Donell <carlos at systemhalted dot org>
Cc: Siddhesh Poyarekar <siddhesh at redhat dot com>, libc-alpha at sourceware dot org, rsa at us dot ibm dot com
Date: Thu, 10 Jan 2013 09:14:17 -0800
Subject: Re: [PATCH][PPC] Remove unnecessary local variable mptwo
References: <20130109114033.GC2692@spoyarek.pnq.redhat.com> <50EEE333.7080304@systemhalted.org>

On 01/10/2013 07:50 AM, Carlos O'Donell wrote:

On 01/09/2013 06:40 AM, Siddhesh Poyarekar wrote:

Hi,

Attached patch removes the local variable mptwo from the __inv
function so that it uses the global static definition instead.  No
regressions resulting from this patch.  OK to commit?

Siddhesh

	* sysdeps/powerpc/powerpc32/power4/fpu/mpa.c (__inv): Remove
	local variable MPTWO.
	* sysdeps/powerpc/powerpc64/power4/fpu/mpa.c (__inv): Likewise.

How does this impact the generated code?

How does that impact mpatan's performance?

It's an initialized non-static local variable that has to be constructed on every invocation of __inv. Replacing that with a reference to a hidden global variable has got to be an improvement.

r~

Follow-Ups:
- Re: [PATCH][PPC] Remove unnecessary local variable mptwo
  - From: Siddhesh Poyarekar

References:
- [PATCH][PPC] Remove unnecessary local variable mptwo
  - From: Siddhesh Poyarekar
- Re: [PATCH][PPC] Remove unnecessary local variable mptwo
  - From: Carlos O'Donell

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