[PowerPC] Change default for unaligned FP access for older subtargets
This is a fix for https://bugs.llvm.org/show_bug.cgi?id=40554
Some CPU's trap to the kernel on unaligned floating point access and
there are kernels that do not handle the interrupt. The program then
fails with a SIGBUS according to the PR. This just switches the
default for unaligned access to only allow it on recent server CPUs
that are known to allow this.
Differential revision: https://reviews.llvm.org/D71954
This upstream commit causes a compiler hang when building certain ports
(e.g. security/nss, multimedia/x264) for powerpc64. The hang has been
reported in https://bugs.llvm.org/show_bug.cgi?id=45186, but in the mean
time it is more convenient to revert the commit.
Requested by: jhibbits
MFC after: 6 weeks
X-MFC-With: 358851
6f7003bfdd