[PAC][clang] Define PointerAuthQualifier and PointerAuthenticationMode (#84384)

This brings declarations of `PointerAuthQualifier` class and
`PointerAuthenticationMode` enum and related functions required for
PAuth support in lldb (see #84387) from downstream Apple's code. See
#84387 for tests as well.

Co-authored-by: Ahmed Bougacha <[email protected]>
Co-authored-by: John McCall <[email protected]>

---------

Co-authored-by: John McCall <[email protected]>
Co-authored-by: Ahmed Bougacha <[email protected]>

Author: 3 people

clang-tools-extra/clang-tidy/bugprone/EasilySwappableParametersCheck.cpp

@@ -967,7 +967,8 @@ approximateStandardConversionSequence(const TheCheck &Check, QualType From,
   // Get out the qualifiers of the original type. This will always be
   // re-applied to the WorkType to ensure it is the same qualification as the
   // original From was.
-  auto QualifiersToApply = From.split().Quals.getAsOpaqueValue();
+  auto FastQualifiersToApply = static_cast<unsigned>(
+      From.split().Quals.getAsOpaqueValue() & Qualifiers::FastMask);
 
   // LValue->RValue is irrelevant for the check, because it is a thing to be
   // done at a call site, and will be performed if need be performed.
@@ -993,7 +994,7 @@ approximateStandardConversionSequence(const TheCheck &Check, QualType From,
     // "const double -> double".
     LLVM_DEBUG(llvm::dbgs()
                << "--- approximateStdConv. Conversion between numerics.\n");
-    WorkType = QualType{ToBuiltin, QualifiersToApply};
+    WorkType = QualType{ToBuiltin, FastQualifiersToApply};
   }
 
   const auto *FromEnum = WorkType->getAs<EnumType>();
@@ -1002,7 +1003,7 @@ approximateStandardConversionSequence(const TheCheck &Check, QualType From,
     // Unscoped enumerations (or enumerations in C) convert to numerics.
     LLVM_DEBUG(llvm::dbgs()
                << "--- approximateStdConv. Unscoped enum to numeric.\n");
-    WorkType = QualType{ToBuiltin, QualifiersToApply};
+    WorkType = QualType{ToBuiltin, FastQualifiersToApply};
   } else if (FromNumeric && ToEnum && ToEnum->isUnscopedEnumerationType()) {
     // Numeric types convert to enumerations only in C.
     if (Ctx.getLangOpts().CPlusPlus) {
@@ -1013,7 +1014,7 @@ approximateStandardConversionSequence(const TheCheck &Check, QualType From,
 
     LLVM_DEBUG(llvm::dbgs()
                << "--- approximateStdConv. Numeric to unscoped enum.\n");
-    WorkType = QualType{ToEnum, QualifiersToApply};
+    WorkType = QualType{ToEnum, FastQualifiersToApply};
   }
 
   // Check for pointer conversions.
@@ -1022,14 +1023,14 @@ approximateStandardConversionSequence(const TheCheck &Check, QualType From,
   if (FromPtr && ToPtr) {
     if (ToPtr->isVoidPointerType()) {
       LLVM_DEBUG(llvm::dbgs() << "--- approximateStdConv. To void pointer.\n");
-      WorkType = QualType{ToPtr, QualifiersToApply};
+      WorkType = QualType{ToPtr, FastQualifiersToApply};
     }
 
     const auto *FromRecordPtr = FromPtr->getPointeeCXXRecordDecl();
     const auto *ToRecordPtr = ToPtr->getPointeeCXXRecordDecl();
     if (isDerivedToBase(FromRecordPtr, ToRecordPtr)) {
       LLVM_DEBUG(llvm::dbgs() << "--- approximateStdConv. Derived* to Base*\n");
-      WorkType = QualType{ToPtr, QualifiersToApply};
+      WorkType = QualType{ToPtr, FastQualifiersToApply};
     }
   }
 
@@ -1039,7 +1040,7 @@ approximateStandardConversionSequence(const TheCheck &Check, QualType From,
   const auto *ToRecord = To->getAsCXXRecordDecl();
   if (isDerivedToBase(FromRecord, ToRecord)) {
     LLVM_DEBUG(llvm::dbgs() << "--- approximateStdConv. Derived To Base.\n");
-    WorkType = QualType{ToRecord->getTypeForDecl(), QualifiersToApply};
+    WorkType = QualType{ToRecord->getTypeForDecl(), FastQualifiersToApply};
   }
 
   if (Ctx.getLangOpts().CPlusPlus17 && FromPtr && ToPtr) {
@@ -1054,7 +1055,7 @@ approximateStandardConversionSequence(const TheCheck &Check, QualType From,
         !ToFunctionPtr->hasNoexceptExceptionSpec()) {
       LLVM_DEBUG(llvm::dbgs() << "--- approximateStdConv. noexcept function "
                                  "pointer to non-noexcept.\n");
-      WorkType = QualType{ToPtr, QualifiersToApply};
+      WorkType = QualType{ToPtr, FastQualifiersToApply};
     }
   }
 

clang/include/clang/AST/ASTContext.h

@@ -2197,6 +2197,16 @@ class ASTContext : public RefCountedBase<ASTContext> {
     return getQualifiedType(type.getUnqualifiedType(), Qs);
   }
 
+  /// \brief Return a type with the given __ptrauth qualifier.
+  QualType getPointerAuthType(QualType Ty, PointerAuthQualifier PointerAuth) {
+    assert(!Ty.getPointerAuth());
+    assert(PointerAuth);
+
+    Qualifiers Qs;
+    Qs.setPointerAuth(PointerAuth);
+    return getQualifiedType(Ty, Qs);
+  }
+
   unsigned char getFixedPointScale(QualType Ty) const;
   unsigned char getFixedPointIBits(QualType Ty) const;
   llvm::FixedPointSemantics getFixedPointSemantics(QualType Ty) const;

clang/include/clang/AST/AbstractBasicReader.h

@@ -213,9 +213,9 @@ class DataStreamBasicReader : public BasicReaderBase<Impl> {
   }
 
   Qualifiers readQualifiers() {
-    static_assert(sizeof(Qualifiers().getAsOpaqueValue()) <= sizeof(uint32_t),
+    static_assert(sizeof(Qualifiers().getAsOpaqueValue()) <= sizeof(uint64_t),
                   "update this if the value size changes");
-    uint32_t value = asImpl().readUInt32();
+    uint64_t value = asImpl().readUInt64();
     return Qualifiers::fromOpaqueValue(value);
   }
 

clang/include/clang/AST/AbstractBasicWriter.h

@@ -196,9 +196,9 @@ class DataStreamBasicWriter : public BasicWriterBase<Impl> {
   }
 
   void writeQualifiers(Qualifiers value) {
-    static_assert(sizeof(value.getAsOpaqueValue()) <= sizeof(uint32_t),
+    static_assert(sizeof(value.getAsOpaqueValue()) <= sizeof(uint64_t),
                   "update this if the value size changes");
-    asImpl().writeUInt32(value.getAsOpaqueValue());
+    asImpl().writeUInt64(value.getAsOpaqueValue());
   }
 
   void writeExceptionSpecInfo(