This method emits nodes for passing byval arguments in registers and stack.
This has the same functionality as existing functions PassByValArg64 and
WriteByValArg which will be deleted later.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166843 91177308-0d34-0410-b5e6-96231b3b80d8