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Re: Use MPFR for real.c decimal-string-to-binary conversions (PR 21718)
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Cc: Richard Biener <richard dot guenther at gmail dot com>
- Date: Wed, 20 Nov 2013 21:09:17 +0000
- Subject: Re: Use MPFR for real.c decimal-string-to-binary conversions (PR 21718)
- Authentication-results: sourceware.org; auth=none
- References: <Pine dot LNX dot 4 dot 64 dot 1311192136190 dot 8742 at digraph dot polyomino dot org dot uk> <CAFiYyc09cVvrDoTy0n9f6wBbFrtXB1s5be3EFCTeCwxGeJ8BpA at mail dot gmail dot com> <Pine dot LNX dot 4 dot 64 dot 1311201816531 dot 28804 at digraph dot polyomino dot org dot uk> <alpine dot DEB dot 2 dot 10 dot 1311202102541 dot 11848 at stedding dot saclay dot inria dot fr>
On Wed, 20 Nov 2013, Marc Glisse wrote:
> On Wed, 20 Nov 2013, Joseph S. Myers wrote:
>
> > This patch removes real_sqrt. (I rather hope that in general little
> > if any floating-point constant folding is happening on RTL - it
> > doesn't seem like the sort of thing for which RTL expansion should be
> > expected to introduce new folding opportunities, and if it does I'd
> > tend to think that indicates a deficiency in the GIMPLE optimizers.)
> >
> > Bootstrapped with no regressions on x86_64-unknown-linux-gnu. OK to
> > commit?
> >
> > 2013-11-20 Joseph Myers <joseph@codesourcery.com>
> >
> > * real.c (real_sqrt): Remove function.
> > * real.h (real_sqrt): Remove prototype.
> > * simplify-rtx.c (simplify_const_unary_operation): Do not fold
> > SQRT using real_sqrt.
>
> I think you can close PR 55950 with that one.
Thanks for the reference - if you have a case where this code is active
(other than where -fno- options are used to disable GIMPLE constant
propagation etc. artificially, although I couldn't find a suitable
testcase even with such options), could you file a PR in Bugzilla for the
missing GIMPLE optimization that results in this only getting optimized
(or not, after this patch) at the RTL level?
--
Joseph S. Myers
joseph@codesourcery.com