[Bug testsuite/101002] Some powerpc tests fail with -mlong-double-64

["segher at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101002

--- Comment #9 from Segher Boessenkool <segher at gcc dot gnu.org> ---
(In reply to Peter Bergner from comment #4)
> These die because the struct we're using to check the alignment of uses long
> double as the "big" aligned type.  We could either disable the tests using a
> "dg-require-effective-target longdouble128" or we could use a different more
> aligned type in the struct.  Maybe _Float128 or _Decimal128 or use an
> attribute aligned?   Thoughts?

Maybe just some vector type?  Those have 128-bit alignment even with
-mno-altivec,
right?

> gcc.target/powerpc/pr85657-3.c
> gcc.target/powerpc/signbit-1.c
> pr85657-3.c:38:20: error: unknown type name ‘__ibm128’; did you mean
> ‘__int128’?
> 
> These die because we don't create the type __ibm128 when using
> -mlong-double-64, which seems strange since we do create the __float128 type
> used in the test cases.
> 
> Mike, I assume the __ibm128 type should always be created?

It always should, yes.  Always.  Unconditionally.