[DebugInfo] Teach LLVM and LLDB about ptrauth in DWARF

Teach libDebugInfo (llvm-dwarfdump) and lldb about DWARF tags and
attributes for pointer authentication. These values have been emitted by
Apple clang for several releases. Although upstream LLVM doesn't emit
these values yet, we hope to upstream that part sometime soon.

Differential revision: https://reviews.llvm.org/D130215

Author: JDevlieghere

lldb/source/Plugins/SymbolFile/DWARF/DWARFDIE.cpp

@@ -320,6 +320,18 @@ void DWARFDIE::AppendTypeName(Stream &s) const {
   case DW_TAG_volatile_type:
     s.PutCString("volatile ");
     break;
+  case DW_TAG_LLVM_ptrauth_type: {
+    unsigned key = GetAttributeValueAsUnsigned(DW_AT_LLVM_ptrauth_key, 0);
+    bool isAddressDiscriminated = GetAttributeValueAsUnsigned(
+        DW_AT_LLVM_ptrauth_address_discriminated, 0);
+    unsigned extraDiscriminator =
+        GetAttributeValueAsUnsigned(DW_AT_LLVM_ptrauth_extra_discriminator, 0);
+    bool isaPointer =
+        GetAttributeValueAsUnsigned(DW_AT_LLVM_ptrauth_isa_pointer, 0);
+    s.Printf("__ptrauth(%d, %d, 0x0%x, %d)", key, isAddressDiscriminated,
+             extraDiscriminator, isaPointer);
+    break;
+  }
   default:
     return;
   }

llvm/include/llvm/BinaryFormat/Dwarf.def

@@ -241,6 +241,9 @@ HANDLE_DW_TAG(0x420c, SUN_f90_interface, 0, SUN, DW_KIND_NONE)
 HANDLE_DW_TAG(0x420d, SUN_fortran_vax_structure, 0, SUN, DW_KIND_NONE)
 HANDLE_DW_TAG(0x42ff, SUN_hi, 0, SUN, DW_KIND_NONE)
 
+// LLVM
+HANDLE_DW_TAG(0x4300, LLVM_ptrauth_type, 0, LLVM, DW_KIND_NONE)
+
 // DSP-C/Starcore __circ, _rev
 HANDLE_DW_TAG(0x5101, ALTIUM_circ_type, 0, ALTIUM, DW_KIND_NONE)
 HANDLE_DW_TAG(0x5102, ALTIUM_mwa_circ_type, 0, ALTIUM, DW_KIND_NONE)
@@ -597,8 +600,12 @@ HANDLE_DW_AT(0x3e00, LLVM_include_path, 0, LLVM)
 HANDLE_DW_AT(0x3e01, LLVM_config_macros, 0, LLVM)
 HANDLE_DW_AT(0x3e02, LLVM_sysroot, 0, LLVM)
 HANDLE_DW_AT(0x3e03, LLVM_tag_offset, 0, LLVM)
-// The missing numbers here are reserved for ptrauth support.
+HANDLE_DW_AT(0x3e04, LLVM_ptrauth_key, 0, LLVM)
+HANDLE_DW_AT(0x3e05, LLVM_ptrauth_address_discriminated, 0, LLVM)
+HANDLE_DW_AT(0x3e06, LLVM_ptrauth_extra_discriminator, 0, LLVM)
 HANDLE_DW_AT(0x3e07, LLVM_apinotes, 0, APPLE)
+HANDLE_DW_AT(0x3e08, LLVM_ptrauth_isa_pointer, 0, LLVM)
+HANDLE_DW_AT(0x3e09, LLVM_ptrauth_authenticates_null_values, 0, LLVM)
 
 // Apple extensions.
 

llvm/lib/DebugInfo/DWARF/DWARFTypePrinter.cpp

@@ -143,6 +143,9 @@ DWARFTypePrinter::appendUnqualifiedNameBefore(DWARFDie D,
     Word = false;
     break;
   }
+  case DW_TAG_LLVM_ptrauth_type:
+    appendQualifiedNameBefore(Inner());
+    break;
   case DW_TAG_const_type:
   case DW_TAG_volatile_type:
     appendConstVolatileQualifierBefore(D);
@@ -237,6 +240,35 @@ void DWARFTypePrinter::appendUnqualifiedNameAfter(
                                /*SkipFirstParamIfArtificial=*/D.getTag() ==
                                    DW_TAG_ptr_to_member_type);
     break;
+  }
+  case DW_TAG_LLVM_ptrauth_type: {
+    auto getValOrNull = [&](dwarf::Attribute Attr) -> uint64_t {
+      if (auto Form = D.find(Attr))
+        return *Form->getAsUnsignedConstant();
+      return 0;
+    };
+    SmallVector<const char *, 2> optionsVec;
+    if (getValOrNull(DW_AT_LLVM_ptrauth_isa_pointer))
+      optionsVec.push_back("isa-pointer");
+    if (getValOrNull(DW_AT_LLVM_ptrauth_authenticates_null_values))
+      optionsVec.push_back("authenticates-null-values");
+    std::string options;
+    for (auto option : optionsVec) {
+      if (options.size())
+        options += ",";
+      options += option;
+    }
+    if (options.size())
+      options = ", \"" + options + "\"";
+    std::string PtrauthString;
+    llvm::raw_string_ostream PtrauthStream(PtrauthString);
+    PtrauthStream
+        << "__ptrauth(" << getValOrNull(DW_AT_LLVM_ptrauth_key) << ", "
+        << getValOrNull(DW_AT_LLVM_ptrauth_address_discriminated) << ", 0x0"
+        << utohexstr(getValOrNull(DW_AT_LLVM_ptrauth_extra_discriminator), true)
+        << options << ")";
+    OS << PtrauthStream.str();
+    break;
   }
     /*
   case DW_TAG_structure_type: