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Re: [Patch, MIPS] Enable fp-contract on MIPS and update -mfused-madd
- From: "Maciej W. Rozycki" <macro at linux-mips dot org>
- To: Joseph Myers <joseph at codesourcery dot com>
- Cc: Steve Ellcey <sellcey at imgtec dot com>, Richard Sandiford <rdsandiford at googlemail dot com>, gcc-patches at gcc dot gnu dot org, Catherine Moore <clm at codesourcery dot com>, Matthew Fortune <matthew dot fortune at imgtec dot com>
- Date: Tue, 16 Jun 2015 14:26:40 +0100 (BST)
- Subject: Re: [Patch, MIPS] Enable fp-contract on MIPS and update -mfused-madd
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- References: <4c25620c-546c-40ae-b330-3652fe25f791 at BAMAIL02 dot ba dot imgtec dot org> <alpine dot DEB dot 2 dot 10 dot 1506112002380 dot 15628 at digraph dot polyomino dot org dot uk> <alpine dot LFD dot 2 dot 11 dot 1506152042580 dot 5418 at eddie dot linux-mips dot org> <alpine dot DEB dot 2 dot 10 dot 1506152047390 dot 9772 at digraph dot polyomino dot org dot uk> <alpine dot LFD dot 2 dot 11 dot 1506152215570 dot 5418 at eddie dot linux-mips dot org> <alpine dot DEB dot 2 dot 10 dot 1506152157470 dot 9772 at digraph dot polyomino dot org dot uk> <alpine dot LFD dot 2 dot 11 dot 1506161240330 dot 5418 at eddie dot linux-mips dot org> <alpine dot DEB dot 2 dot 10 dot 1506161215400 dot 4909 at digraph dot polyomino dot org dot uk>
On Tue, 16 Jun 2015, Joseph Myers wrote:
> > Furthermore these checks were deliberately introduced by Richard with his
> > proposal here <http://gcc.gnu.org/ml/gcc-patches/2006-09/msg00682.html>
> > and agreed upon in the discussion even before IEEE Std 754-2008 has been
> > made. Are you suggesting that the arguments used there, that have led to
> > the current arrangement, no longer stand and consequently the HONOR_NANS
> > checks introduced are now best dropped?
>
> Only the checks for abs and neg patterns are necessary, not those for
> fused operations.
And neither for the unfused combined operations we handle for some MIPS
processors that implement them presumably?
In that case I think the HONOR_NANS checks will best be globally removed
first (where applicable of course), with a separate preparatory change.
Maciej