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Re: [PATCH] Perform constant folding of math builtins
- From: "Joseph S. Myers" <jsm28 at cam dot ac dot uk>
- To: "Kaveh R. Ghazi" <ghazi at caip dot rutgers dot edu>
- Cc: <aaronl at vitelus dot com>, <roger at eyesopen dot com>, <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 26 Aug 2002 17:50:00 +0100 (BST)
- Subject: Re: [PATCH] Perform constant folding of math builtins
On Mon, 26 Aug 2002, Kaveh R. Ghazi wrote:
> > The second is that
> > these values need to be calculated in the precision required for the
> > target, so shouldn't use the host functions anyway.
>
> Why not? Aren't we talking about "unsafe" math opts?
Folding for arbitrary constant arguments isn't unsafe if we have
last-bit-accurate emulation for the target precision operations.
(Provided that once we have the C99 floating point pragmas they are
honoured - meaning disabling the folding except for exact cases when
#pragma STDC FENV_ACCESS ON is in effect.)
--
Joseph S. Myers
jsm28@cam.ac.uk