- Support emitting .cfi_undefined in CodeGen
- Emit register names in assembly for .cfi_undefined, .cfi_register, and
.cfi_return_column
[AMDGPU] Implement wave64 DWARF register mapping
Implement the DWARF register mapping described in
llvm/docs/AMDGPUUsage.rst
This is currently limited to wave64 VGPRs/AGPRs.
This also includes some minor changes in AMDGPUInstPrinter and
AMDGPUMCTargetDesc to make generating CFI assembly text and ELF sections
possible to ease testing, although complete CFI support is not yet
implemented.