From: Jan Hubicka <jh@suse.cz>
To: Richard Henderson <rth@redhat.com>, Jan Hubicka <jh@suse.cz>,
gcc-patches@gcc.gnu.org, aj@suse.de
Subject: Re: Simplify floating point conversions
Date: Tue, 05 Nov 2002 09:42:00 -0000 [thread overview]
Message-ID: <20021105174231.GZ14655@kam.mff.cuni.cz> (raw)
In-Reply-To: <20021105173800.GD20534@redhat.com>
> On Tue, Nov 05, 2002 at 06:14:00PM +0100, Jan Hubicka wrote:
> > 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.
>
> You should have commented this. It should not take someone 5
Oops...
> minutes to even figure out what's going on here. To be sure, it's
>
> (float)sqrtl(x) -> sqrtf((float)x)
It does just (float)sqrt((float)x)->sqrtf(x)
This is common in C code when you call sqrt on float value.
Honza
>
> correct? Well, clearly this fails for X = 2**(127 * 2), since
> X is not representable as a float, but its square root is. It
> would not be hard to identify similar problems with every other
> operation on your list except for ABS/NEG.
>
>
> r~
next prev parent reply other threads:[~2002-11-05 17:42 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 [this message]
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
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