Partially implement callee-side for arguments and return values.
byval doesn't work properly, and most likely sret or other on-stack
return values most as well.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303308 91177308-0d34-0410-b5e6-96231b3b80d8
Surprisingly, one of the three interference checks in LiveRegMatrix was
using the main live range instead of the apropriate subregister range
resulting in unnecessarily conservative results.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296722 91177308-0d34-0410-b5e6-96231b3b80d8