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.
