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Re: [PATCH] Recognize sqrt(1.0/x) as rsqrt.d on MIPS4

From: Eric Christopher <echristo at redhat dot com>
To: Richard Sandiford <rsandifo at redhat dot com>
Cc: Roger Sayle <roger at eyesopen dot com>, gcc-patches at gcc dot gnu dot org
Date: Tue, 10 Aug 2004 10:44:17 -0700
Subject: Re: [PATCH] Recognize sqrt(1.0/x) as rsqrt.d on MIPS4
References: <Pine.LNX.4.44.0408100839500.16913-100000@www.eyesopen.com> <878ycn9bdf.fsf@redhat.com>

> I'm just uneasy at seeing more uses of flag_unsafe_math_optimizations
> creeping into the back-end.  I'd much rather the middle-end say what was
> fair game and what wasn't, in the hope of presenting a more consistent,
> cross-platform interface[*].  Perhaps we could have a rsqrt rtx code and
> optab, and have the middle-end check whether that is available.

This is a good idea. And the target specific patterns can be removed
then, but IMO there's no reason not to have the patterns until such time
though. It's not like it's a gross hack or anything :)

-eric

-- 
Eric Christopher <echristo@redhat.com>

References:
- Re: [PATCH] Recognize sqrt(1.0/x) as rsqrt.d on MIPS4
  - From: Roger Sayle
- Re: [PATCH] Recognize sqrt(1.0/x) as rsqrt.d on MIPS4
  - From: Richard Sandiford

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