[PATCH], PowerPC long double transition patches, v2

[Michael Meissner <meissner at linux dot ibm dot com>]

I'm going to post long double transition fixes that fix most of the problems
when you switch the long double format as follow-ups to this message.  A few of
the fixes to the tests were previously posted, but I've added some comments.

Here are the remaining failures in the C/C++ tests after these patches are
applied:

    1)	There currently is no converter between Decimal types and IEEE 128-bit
	floating point.  Tulio has said this is on the list, but it is lower in
	priority than the main long double transition code in GLIBC.

    2)	A few of the tests use GLIBC long double support, and will presumably
	work when the GLIBC changes are done.

    3)	Two nan related tests (gcc.dg/torture/float128-nan.c, and
	gcc.target/powerpc/nan128-1.c) fail.  I haven't looked into these yet.

    4)	One test (gcc.target/powerpc/pr70117.c) fails after the long double
	code is converted to use __ibm128.  The failure is in the isnormal
	function.  It generates different code for __ibm128 if long double is
	IEEE 128-bit than it does for long double using IBM extended double.

As before, I would like to install these in the trunk and back port them to GCC
8.2.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797