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Re: fabs() intrinsic totally broken in P4, as of 2002-02-11

From: Richard Henderson <rth at redhat dot com>
To: Jan Hubicka <jh at suse dot cz>
Cc: Tom Womack <tom at womack dot net>, gcc at gcc dot gnu dot org
Date: Sun, 17 Feb 2002 11:29:10 -0800
Subject: Re: fabs() intrinsic totally broken in P4, as of 2002-02-11
References: <001a01c1b6ff$f03e1240$5637f380@maths.nottingham.ac.uk> <20020217163523.GE8455@atrey.karlin.mff.cuni.cz>

On Sun, Feb 17, 2002 at 05:35:23PM +0100, Jan Hubicka wrote:
> The drawback is that we can't represent the constant as FP value as it would
> get promptly normalized,

Err, would it?  ~(-0.0) is a NaN.  Oh, I see, real.c is somewhat
insistent about producing canonical QNaNs.  That's irritating.

> Do you see any way out?

Using unspecs to hide the pieces of the constant generation.
Ugly, but...

r~

References:
- fabs() intrinsic totally broken in P4, as of 2002-02-11
  - From: Tom Womack
- Re: fabs() intrinsic totally broken in P4, as of 2002-02-11
  - From: Jan Hubicka

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