[clang] [clang] Fix PointerAuth semantics of cpp_trivially_relocatable (PR #143969)

[Corentin Jabot via cfe-commits]

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@@ -629,25 +629,46 @@ class ASTContext : public RefCountedBase<ASTContext> {
   void setRelocationInfoForCXXRecord(const CXXRecordDecl *,
                                      CXXRecordDeclRelocationInfo);
 
-  /// Examines a given type, and returns whether the T itself
+  /// Examines a given type, and returns whether the type itself
   /// is address discriminated, or any transitively embedded types
   /// contain data that is address discriminated. This includes
   /// implicitly authenticated values like vtable pointers, as well as
   /// explicitly qualified fields.
-  bool containsAddressDiscriminatedPointerAuth(QualType T);
-  // A simple helper function to short circuit pointer auth checks.
+  bool containsAddressDiscriminatedPointerAuth(QualType T) {
+    if (!isPointerAuthenticationAvailable())
+      return false;
+    return findPointerAuthContent(T) != PointerAuthContent::None;
+  }
 
-  bool isPointerAuthenticationAvailable() const {
-    return LangOpts.PointerAuthCalls || LangOpts.PointerAuthIntrinsics ||
-           LangOpts.PointerAuthVTPtrAddressDiscrimination;
+  /// Examines a given type, and returns whether the type itself
+  /// or any data it transitively contains has a pointer authentication
+  /// schema that is not safely relocatable. e.g. any data or fields
+  /// with address discrimination other than any otherwise similar
+  /// vtable pointers.
+  bool containsNonRelocatablePointerAuth(QualType T) {
+    if (!isPointerAuthenticationAvailable())
+      return false;
+    return findPointerAuthContent(T) == PointerAuthContent::AddressDiscriminatedData;
   }
 
 private:
   llvm::DenseMap<const CXXRecordDecl *, CXXRecordDeclRelocationInfo>
       RelocatableClasses;
 
   // FIXME: store in RecordDeclBitfields in future?
-  llvm::DenseMap<const RecordDecl *, bool>
+  enum class PointerAuthContent : uint8_t {
+    None,
+    AddressDiscriminatedVTable,
+    AddressDiscriminatedData
+  };
+
+  // A simple helper function to short circuit pointer auth checks.
+  bool isPointerAuthenticationAvailable() const {
+    return LangOpts.PointerAuthCalls || LangOpts.PointerAuthIntrinsics ||
+           LangOpts.PointerAuthVTPtrAddressDiscrimination;
+  }
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cor3ntin wrote:

2 questions; Why do we have 3 options, and why do we care about anything but `PointerAuthVTPtrAddressDiscrimination`here?

https://github.com/llvm/llvm-project/pull/143969