ARM: support interrupt attribute

This function-attribute modifies the callee-saved register list and function
epilogue (specifically the return instruction) so that a routine is suitable
for use as an interrupt-handler of the specified type without disrupting
user-mode applications.

rdar://problem/14207019

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191766 91177308-0d34-0410-b5e6-96231b3b80d8
[SystemZ] Extend pseudo conditional 8- and 16-bit stores to high words

As the comment says, we always want to use STOC for 32-bit stores.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191767 91177308-0d34-0410-b5e6-96231b3b80d8