From: kaih@khms.westfalen.de (Kai Henningsen)
To: gcc@gcc.gnu.org
Subject: Re: What is acceptable for -ffast-math?
Date: Fri, 03 Aug 2001 12:26:00 -0000 [thread overview]
Message-ID: <8683E2V1w-B@khms.westfalen.de> (raw)
In-Reply-To: <15208.15303.748602.738457@perceval.inria.fr>
gdosreis@sophia.inria.fr (Gabriel Dos_Reis) wrote on 01.08.01 in < 15208.15303.748602.738457@perceval.inria.fr >:
> | <<We're talking here of transformations which we do know able to
> | drastically change the results.
> | >>
> |
> | Words like drastically are not particularly helpful in this discussion,
> | plain "change" would be just fine.
>
> Do you think changing 0.125 to 0.0 is not drastic?
That depends entirely on the context, obviously. If it's a pixel position,
for example, it's completely meaningless.
And anyway you needed to go right to the edge of the data type to do that.
Calculating on the edge (and needing precision) is precisely the situation
where you switch optimization *off*.
Sure, with 64 bit floats, that edge is a lot closer than with larger
types. So?
Some work can't be done with those. So? Some work can't be done with 32
bit floats, either. Or with ints. Nothing new about that.
MfG Kai
next prev parent reply other threads:[~2001-08-03 12:26 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-08-01 10:04 What is acceptable for -ffast-math? (Was: associative law in combine) dewar
2001-08-01 10:28 ` Gabriel Dos_Reis
2001-08-01 10:41 ` What is acceptable for -ffast-math? (Was: associative law incombine) Linus Torvalds
2001-08-01 10:55 ` Gabriel Dos_Reis
2001-08-03 12:26 ` Kai Henningsen [this message]
2001-08-01 10:13 What is acceptable for -ffast-math? (Was: associative law in combine) dewar
2001-08-03 12:26 ` What is acceptable for -ffast-math? Kai Henningsen
2001-08-02 12:07 Jeremy Sanders
2001-08-03 13:49 dewar
2001-08-04 1:56 ` Jeremy Sanders
2001-08-03 15:00 dewar
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