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Re: [PATCH] PR 42327: Add checks for sqrt optab being present before doing pow (x, 0.75) optimization

From: Paolo Bonzini <bonzini at gnu dot org>
To: Michael Meissner <meissner at linux dot vnet dot ibm dot com>, gcc-patches at gcc dot gnu dot org, rguenther at suse dot de, jakub at redhat dot com
Date: Wed, 08 Dec 2010 11:39:32 +0100
Subject: Re: [PATCH] PR 42327: Add checks for sqrt optab being present before doing pow (x, 0.75) optimization
Newsgroups: gmane.comp.gcc.patches
References: <20101207173857.GA14620@hungry-tiger.westford.ibm.com>

On 12/07/2010 06:38 PM, Michael Meissner wrote:

	* builtins.c (expand_builtin_pow_root): Don't optimize pow(x,y)
	where y is 0.25, 1./6., or 0.75 if the target does not have a sqrt
	instruction, but do optimize if y is 0.5 or 1./6. since that

^^^^^

Did you mean 1./3. here?

changes an expensive call into a cheaper one.

Paolo

Follow-Ups:
- Re: [PATCH] PR 42327: Add checks for sqrt optab being present before doing pow (x, 0.75) optimization
  - From: Michael Meissner

References:
- [PATCH] PR 42327: Add checks for sqrt optab being present before doing pow (x, 0.75) optimization
  - From: Michael Meissner

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