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Re: soft-fp: Add FP_DENORM_ZERO
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: Carlos O'Donell <carlos at redhat dot com>
- Cc: <libc-alpha at sourceware dot org>
- Date: Thu, 9 Oct 2014 00:57:48 +0000
- Subject: Re: soft-fp: Add FP_DENORM_ZERO
- Authentication-results: sourceware.org; auth=none
- References: <Pine dot LNX dot 4 dot 64 dot 1409191817180 dot 11496 at digraph dot polyomino dot org dot uk> <5435D91B dot 90603 at redhat dot com>
On Wed, 8 Oct 2014, Carlos O'Donell wrote:
> > diff --git a/soft-fp/soft-fp.h b/soft-fp/soft-fp.h
> > index 86bc7fa..05fcca0 100644
> > --- a/soft-fp/soft-fp.h
> > +++ b/soft-fp/soft-fp.h
> > @@ -161,6 +161,11 @@
> > # define FP_HANDLE_EXCEPTIONS do {} while (0)
> > #endif
> >
> > +/* Whether to flush subnormal inputs to zero with the same sign. */
> > +#ifndef FP_DENORM_ZERO
> > +# define FP_DENORM_ZERO 0
> > +#endif
>
> OK, but...
>
> For the record this is an instance of the "centralized defaults" pattern
> which we try to avoid in glibc. What if the target accidentally defines:
I am unconvinced this can readily be avoided in the soft-fp code without a
lot of duplication of common definitions in different sfp-machine.h files
(of which there are a lot, when you consider those in libgcc and the Linux
kernel as well as glibc).
--
Joseph S. Myers
joseph@codesourcery.com