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Re: [PATCH] Don't do double divide in powf.

From: Jim Wilson <jimw at sifive dot com>
To: newlib at sourceware dot org
Date: Tue, 12 Dec 2017 10:14:16 -0800
Subject: Re: [PATCH] Don't do double divide in powf.
Authentication-results: sourceware.org; auth=none
Newsgroups: gmane.comp.lib.newlib
References: <20171212034521.8556-1-jimw@sifive.com> <20171212130454.GD9113@calimero.vinschen.de>

On 12/12/2017 05:04 AM, Corinna Vinschen wrote:

On Dec 11 19:45, Jim Wilson wrote:

-		        exc.retval = 0.0/0.0;	/* X/Open allow NaN */
+		        exc.retval = nan("");	/* X/Open allow NaN */


As far as I can see, that still pulls in an unnecessary function call,
nan().

What about using NAN?  That's basically __builtin_nanf("") and usually
resolves without function call on any platform.

I don't see any place in the math dir that currently uses NAN like this,but there are multiple places calling nan(""), so I did it that way. Idon't care which way it is done. But it looks like Craig Howland has alegitimate objection, so I will try float 0.0/0.0 divide instead.

Jim

References:
- [PATCH] Don't do double divide in powf.
  - From: Jim Wilson
- Re: [PATCH] Don't do double divide in powf.
  - From: Corinna Vinschen

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