Re: Update libquadmath fmaq from glibc, fix nanq issues

[Jakub Jelinek <jakub@redhat.com>]

On Wed, Nov 07, 2018 at 12:29:21AM +0000, Joseph Myers wrote:
> This patch extends update-quadmath.py to update fmaq from glibc.
> 
> The issue in that function was that quadmath-imp.h had a struct in a
> union with mant_high and mant_low fields (up to 64-bit) whereas glibc
> has mantissa0, mantissa1, mantissa2 and mantissa3 (up to 32-bit).  The
> patch changes those fields to be the same as in glibc, moving printf /
> strtod code that also uses those fields back to closer to the glibc
> form.  This allows fmaq to be updated automatically from glibc (which
> brings in at least one bug fix from glibc from 2015).
> 
> nanq was also using the mant_high field name, and had other issues: it
> only partly initialized the union from which a value was returned, and
> setting mant_high to 1 meant a signaling NaN would be returned rather
> than a quiet NaN.  This patch fixes those issues as part of updating
> it to use the changed interfaces (but does not fix the issue of not
> using the argument).
> 
> Bootstrapped with no regressions on x86_64-pc-linux-gnu.

Don't know about the dropping of HAVE_FENV_H/USE_FENV_H stuff, don't we
support libquadmath on targets that don't have fenv.h?
In other sources, like e.g. expq.c, the USE_FENV_H guards are still kept.

	Jakub