From: Jan Hubicka <jh@suse.cz>
To: Gabriel Dos Reis <gdr@integrable-solutions.net>
Cc: Jan Hubicka <jh@suse.cz>, Richard Henderson <rth@redhat.com>,
gcc-patches@gcc.gnu.org, aj@suse.de
Subject: Re: Simplify floating point conversions II
Date: Wed, 06 Nov 2002 13:36:00 -0000 [thread overview]
Message-ID: <20021106213652.GF1316@atrey.karlin.mff.cuni.cz> (raw)
In-Reply-To: <m365va2xfl.fsf@soliton.integrable-solutions.net>
> Jan Hubicka <jh@suse.cz> writes:
>
> | > On Wed, Nov 06, 2002 at 06:54:41PM +0100, Jan Hubicka wrote:
> | > > + For fast math it would be safe probably to convert (float)sqrt(x)
> | > > + into sqrt((float)x), but in strict mode the argument can overflow. */
> | >
> | > I don't believe this to be true.
> |
> | What you don't believe?
>
> Likew RTH, I, skeptical that your assertion is right.
>
> | That in ffast-math we can do the transformation?
>
> Do we really need to do that transformation? That is is there any
> real evidence that it brings any real benefit?
> I would be reluctant to include it even in -funsafe-math.
I am not implementing that transformation, so I am not sure.
Doing the cases I do right now and I believe to be safe brings quite
considerable amount of matches in standard C 3d graphics code that does
a lot of float and some casts to double coming from implicit C stuff.
Honza
>
> -- Gaby
next prev parent reply other threads:[~2002-11-06 21:36 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-11-05 9:14 Simplify floating point conversions Jan Hubicka
2002-11-05 9:38 ` Richard Henderson
2002-11-05 9:42 ` Jan Hubicka
2002-11-06 1:23 ` Simplify floating point conversions II Jan Hubicka
2002-11-06 3:08 ` Michael Matz
2002-11-06 4:36 ` Jan Hubicka
2002-11-06 9:54 ` Jan Hubicka
2002-11-06 10:09 ` Richard Henderson
2002-11-06 13:11 ` Jan Hubicka
2002-11-06 13:19 ` Jan Hubicka
2002-11-06 13:35 ` Gabriel Dos Reis
2002-11-06 13:36 ` Jan Hubicka [this message]
2002-11-06 14:06 ` Gabriel Dos Reis
2002-11-06 14:29 ` Converting floor to rint Jan Hubicka
2002-11-06 14:47 ` Richard Henderson
2002-11-06 14:53 ` Jan Hubicka
2002-11-06 14:55 ` Gabriel Dos Reis
2002-11-07 1:21 ` Jan Hubicka
2002-11-07 1:32 ` Jakub Jelinek
2002-11-07 1:33 ` Gabriel Dos Reis
2002-11-07 1:44 ` Jan Hubicka
2002-11-07 1:52 ` Jakub Jelinek
2002-11-07 1:54 ` Jan Hubicka
2002-11-07 2:04 ` Jan Hubicka
2002-11-07 4:47 ` Gabriel Dos Reis
2002-11-07 4:56 ` Jan Hubicka
2002-11-07 5:14 ` Andreas Schwab
2002-11-07 5:27 ` Gabriel Dos Reis
2002-11-07 5:31 ` Jan Hubicka
2002-11-07 5:35 ` Andreas Schwab
2002-11-07 5:22 ` Gabriel Dos Reis
2002-11-07 5:43 ` Andreas Schwab
2002-11-07 6:23 ` Gabriel Dos Reis
2002-11-07 7:01 ` Jan Hubicka
2002-11-07 7:18 ` Gabriel Dos Reis
2002-11-06 13:48 ` Simplify floating point conversions III Jan Hubicka
2002-11-06 14:55 ` Richard Henderson
2002-11-07 2:54 ` Simplify floating point conversions IV Jan Hubicka
2002-11-18 15:01 ` Richard Henderson
2002-11-05 11:14 ` Simplify floating point conversions Geoff Keating
2002-11-06 1:09 ` Jan Hubicka
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