[Dwarf] Support `__ptrauth` qualifier in metadata nodes (#82363)

Emit `__ptrauth`-qualified types as `DIDerivedType` metadata nodes in IR
with tag `DW_TAG_LLVM_ptrauth_type`, baseType referring to the type
which has the qualifier applied, and the following parameters
representing the signing schema:

- `ptrAuthKey` (integer)
- `ptrAuthIsAddressDiscriminated` (boolean)
- `ptrAuthExtraDiscriminator` (integer)
- `ptrAuthIsaPointer` (boolean)
- `ptrAuthAuthenticatesNullValues` (boolean)

Co-authored-by: Ahmed Bougacha <ahmed@bougacha.org>

1 files changed, 21 insertions, 11 deletions

diff --git a/llvm/lib/IR/DebugInfoMetadata.cpp b/llvm/lib/IR/DebugInfoMetadata.cpp
index 28f9665..36c13e7 100644
--- a/llvm/lib/IR/DebugInfoMetadata.cpp
+++ b/llvm/lib/IR/DebugInfoMetadata.cpp
@@ -34,6 +34,10 @@ cl::opt<bool> EnableFSDiscriminator(
     cl::desc("Enable adding flow sensitive discriminators"));
 } // namespace llvm
 
+uint32_t DIType::getAlignInBits() const {
+  return (getTag() == dwarf::DW_TAG_LLVM_ptrauth_type ? 0 : SubclassData32);
+}
+
 const DIExpression::FragmentInfo DebugVariable::DefaultFragment = {
     std::numeric_limits<uint64_t>::max(), std::numeric_limits<uint64_t>::min()};
 
@@ -731,26 +735,32 @@ Constant *DIDerivedType::getDiscriminantValue() const {
   return nullptr;
 }
 
-DIDerivedType *
-DIDerivedType::getImpl(LLVMContext &Context, unsigned Tag, MDString *Name,
-                       Metadata *File, unsigned Line, Metadata *Scope,
-                       Metadata *BaseType, uint64_t SizeInBits,
-                       uint32_t AlignInBits, uint64_t OffsetInBits,
-                       std::optional<unsigned> DWARFAddressSpace, DIFlags Flags,
-                       Metadata *ExtraData, Metadata *Annotations,
-                       StorageType Storage, bool ShouldCreate) {
+DIDerivedType *DIDerivedType::getImpl(
+    LLVMContext &Context, unsigned Tag, MDString *Name, Metadata *File,
+    unsigned Line, Metadata *Scope, Metadata *BaseType, uint64_t SizeInBits,
+    uint32_t AlignInBits, uint64_t OffsetInBits,
+    std::optional<unsigned> DWARFAddressSpace,
+    std::optional<PtrAuthData> PtrAuthData, DIFlags Flags, Metadata *ExtraData,
+    Metadata *Annotations, StorageType Storage, bool ShouldCreate) {
   assert(isCanonical(Name) && "Expected canonical MDString");
   DEFINE_GETIMPL_LOOKUP(DIDerivedType,
                         (Tag, Name, File, Line, Scope, BaseType, SizeInBits,
-                         AlignInBits, OffsetInBits, DWARFAddressSpace, Flags,
-                         ExtraData, Annotations));
+                         AlignInBits, OffsetInBits, DWARFAddressSpace,
+                         PtrAuthData, Flags, ExtraData, Annotations));
   Metadata *Ops[] = {File, Scope, Name, BaseType, ExtraData, Annotations};
   DEFINE_GETIMPL_STORE(DIDerivedType,
                        (Tag, Line, SizeInBits, AlignInBits, OffsetInBits,
-                        DWARFAddressSpace, Flags),
+                        DWARFAddressSpace, PtrAuthData, Flags),
                        Ops);
 }
 
+std::optional<DIDerivedType::PtrAuthData>
+DIDerivedType::getPtrAuthData() const {
+  return getTag() == dwarf::DW_TAG_LLVM_ptrauth_type
+             ? std::optional<PtrAuthData>(PtrAuthData(SubclassData32))
+             : std::nullopt;
+}
+
 DICompositeType *DICompositeType::getImpl(
     LLVMContext &Context, unsigned Tag, MDString *Name, Metadata *File,
     unsigned Line, Metadata *Scope, Metadata *BaseType, uint64_t SizeInBits,