From: Jan Hubicka <jh@suse.cz>
To: Geoff Keating <geoffk@geoffk.org>
Cc: Jan Hubicka <jh@suse.cz>, gcc-patches@gcc.gnu.org
Subject: Re: Simplify floating point conversions
Date: Wed, 06 Nov 2002 01:09:00 -0000 [thread overview]
Message-ID: <20021106090904.GB22059@kam.mff.cuni.cz> (raw)
In-Reply-To: <jm4ravommn.fsf@desire.geoffk.org>
> Jan Hubicka <jh@suse.cz> writes:
>
> > Hi,
> > this patch makes us to simplify some of the floating point operations to
> > narrower mode when conversions are present. This include
> > +,-,/,*,abs,neg,sqrt/sin/cos/exp.
> > I believe it is IEEE safe, but some expert would be welcome.
>
> It's not safe, except for 'abs' and 'neg'. For example,
> (float)sqrt(2.0 * FLT_MAX) != sqrtf(2.0 * FLT_MAX).
> I think it would be OK for -ffast-math, though.
I am doing only (float)sqrt((double)float)
that commonly results from C code that uses floats but calls math
functions. I can add fast-math code for weaker checks later, but first
I would like to know whether this transformation is valid.
I will add the comments :) I usually write the automatically and
ididn't noticed there are none..
Honza
>
> --
> - Geoffrey Keating <geoffk@geoffk.org>
prev parent reply other threads:[~2002-11-06 9:09 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-11-05 9:14 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
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 [this message]
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