[AArch64] - Return address signing dwarf support

Functions that have signed return addresses need additional dwarf support:
- After signing the LR, and before authenticating it, the LR register is in a
  state the is unusable by a debugger or unwinder
- To account for this a new directive, .cfi_negate_ra_state, is added
- This directive says the signed state of the LR register has now changed,
  i.e. unsigned -> signed or signed -> unsigned
- This directive has the same CFA code as the SPARC directive GNU_window_save
  (0x2d), adding a macro to account for multiply defined codes
- This patch matches the gcc implementation of this support:
  https://patchwork.ozlabs.org/patch/800271/

Differential Revision: https://reviews.llvm.org/D50136

llvm-svn: 343089

1 files changed, 19 insertions, 1 deletions

diff --git a/llvm/lib/BinaryFormat/Dwarf.cpp b/llvm/lib/BinaryFormat/Dwarf.cpp
index 5984de73ae6..46b95275395 100644
--- a/llvm/lib/BinaryFormat/Dwarf.cpp
+++ b/llvm/lib/BinaryFormat/Dwarf.cpp
@@ -13,6 +13,7 @@
 
 #include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/Triple.h"
 #include "llvm/Support/ErrorHandling.h"
 
 using namespace llvm;
@@ -455,14 +456,31 @@ StringRef llvm::dwarf::RangeListEncodingString(unsigned Encoding) {
   }
 }
 
-StringRef llvm::dwarf::CallFrameString(unsigned Encoding) {
+StringRef llvm::dwarf::CallFrameString(unsigned Encoding,
+    Triple::ArchType Arch) {
+#define SELECT_AARCH64 (Arch == llvm::Triple::aarch64_be || Arch == llvm::Triple::aarch64)
+#define SELECT_MIPS64 Arch == llvm::Triple::mips64
+#define SELECT_SPARC64 Arch == llvm::Triple::sparcv9
+#define SELECT_X86 (Arch == llvm::Triple::x86 || Arch == llvm::Triple::x86_64)
+#define HANDLE_DW_CFA(ID, NAME)
+#define HANDLE_DW_CFA_PRED(ID, NAME, PRED) \
+  if (ID == Encoding && PRED) \
+    return "DW_CFA_" #NAME;
+#include "llvm/BinaryFormat/Dwarf.def"
+
   switch (Encoding) {
   default:
     return StringRef();
+#define HANDLE_DW_CFA_PRED(ID, NAME, PRED)
 #define HANDLE_DW_CFA(ID, NAME)                                                \
   case DW_CFA_##NAME:                                                          \
     return "DW_CFA_" #NAME;
 #include "llvm/BinaryFormat/Dwarf.def"
+
+#undef SELECT_X86
+#undef SELECT_SPARC64
+#undef SELECT_MIPS64
+#undef SELECT_AARCH64
   }
 }