Make max_align_t respect _Float128 [version 2]

[Bernd Edlinger]

On 09/07/16 22:04, Joseph Myers wrote:
> On Wed, 7 Sep 2016, Bernd Edlinger wrote:
>
>> interesting.  I just tried the test case from PR 77330 with _Decimal128.
>> result: _Decimal128 did *not* trap with gcc4.8.4, but it does trap with
>> gcc-7.0.0.
>
> I checked with GCC 4.3; __alignof__ (_Decimal128) was 16 back then.
> Whether particular code happens to make use of that alignment requirement
> is inherently unpredictable.
>

Oh, now I see...

Alignof(_Decimal128) was 16, but gcc4.8 did not enable -msse, and
that must have changed.  When I use gcc -m32 -msse the test case
starts to fail with gcc-4.8.4.

With gcc-7.0.0 -m32 -mno-sse fixes the test case but the alignment is
still 16, as you already said.

Apparently the different -msse default setting made the situation worse.
I think that will not run on a pentium4 any more.


Bernd.