[ARM64] [Windows] Exception handling support in frame lowering

Emit pseudo instructions indicating unwind codes corresponding to each
instruction inside the prologue/epilogue.  These are used by the MCLayer to
populate the .xdata section.

Differential Revision: https://reviews.llvm.org/D50288


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345701 91177308-0d34-0410-b5e6-96231b3b80d8
17 files changed