[AArch64] - Return address signing dwarf support

- Reapply changes intially introduced in r343089
- The archtecture info is no longer loaded whenever a DWARFContext is created
- The runtimes libraries (santiziers) make use of the dwarf context classes but
  do not intialise the target info
- The architecture of the object can be obtained without loading the target info
- Adding a method to the dwarf context to get this information and multiplex the
  string printing later on

Differential Revision: https://reviews.llvm.org/D55774

llvm-svn: 349472

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp
index 66dfe7b7fa4..9791fb5724b 100644
--- a/llvm/lib/MC/MCDwarf.cpp
+++ b/llvm/lib/MC/MCDwarf.cpp
@@ -1332,6 +1332,10 @@ void FrameEmitterImpl::EmitCFIInstruction(const MCCFIInstruction &Instr) {
     Streamer.EmitIntValue(dwarf::DW_CFA_GNU_window_save, 1);
     return;
 
+  case MCCFIInstruction::OpNegateRAState:
+    Streamer.EmitIntValue(dwarf::DW_CFA_AARCH64_negate_ra_state, 1);
+    return;
+
   case MCCFIInstruction::OpUndefined: {
     unsigned Reg = Instr.getRegister();
     Streamer.EmitIntValue(dwarf::DW_CFA_undefined, 1);