From: Gabriel Dos Reis <gdr@integrable-solutions.net>
To: Jan Hubicka <jh@suse.cz>
Cc: Andreas Schwab <schwab@suse.de>, gcc-patches@gcc.gnu.org
Subject: Re: Converting floor to rint
Date: Thu, 07 Nov 2002 07:18:00 -0000 [thread overview]
Message-ID: <m3isz9tnjj.fsf@soliton.integrable-solutions.net> (raw)
In-Reply-To: Jan Hubicka's message of "Thu, 7 Nov 2002 16:00:55 +0100"
Jan Hubicka <jh@suse.cz> writes:
[...]
| > F.7.1 Environment management
| >
| > [#1] IEC 60559 requires that floating-point operations
| > implicitly raise floating-point exception status flags, and
| > that rounding control modes can be set explicitly to affect
| > result values of floating-point operations. When the state
| > for the FENV_ACCESS pragma (defined in <fenv.h>) is ``on'',
| > these changes to the floating-point state are treated as
| > *side effects* which respect sequence points.304)
| >
| > (my emphasis)
|
| So one can not consider rint as "attribute((const))" function and we can
| not do that in strict mode.
That is exact.
| >
| > | Otherwise, if
| > | __STDC_IEC_559__ is not defined, then no requirements on the exceptions
| > | are stated for rint, since 7.12.9.4 does not have a "shall".
| Can I detect somehow the cases when __STDC_IEC_559__ is not defined?
Also one would need to access thye value of FENV_ACCESS. That is all
that I loosenely called "propriate FE exception machinary".
| This seems to be done by glibc in all cases, even with -ffast-math.
| Perhaps I can do the rint folding only with -ffast-math that would be
| enought for majority of 3D software that is about the only case where we
| get some oppurtunities for speedup from this transformations?
I won't oppose to having it in -funsafe-math.
-- Gaby
next prev parent reply other threads:[~2002-11-07 15:18 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
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 [this message]
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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