[clang] Add support for __ptrauth being applied to integer types

This adds support for the __ptrauth qualifier to be applied to
pointer sized integer types.

Author: ojhunt

clang/docs/PointerAuthentication.rst

@@ -284,13 +284,14 @@ __ptrauth Qualifier
 ^^^^^^^^^^^^^^^^^^^
 
 ``__ptrauth(key, address, discriminator)`` is an extended type
-qualifier which causes so-qualified objects to hold pointers signed using the
-specified schema rather than the default schema for such types.
+qualifier which causes so-qualified objects to hold pointers or pointer sized
+integers signed using the specified schema rather than the default schema for
+such types.
 
 In the current implementation in Clang, the qualified type must be a C pointer
-type, either to a function or to an object.  It currently cannot be an
-Objective-C pointer type, a C++ reference type, or a block pointer type; these
-restrictions may be lifted in the future.
+type, either to a function or to an object, or a pointer sized integer.  It
+currently cannot be an Objective-C pointer type, a C++ reference type, or a
+block pointer type; these restrictions may be lifted in the future.
 
 The qualifier's operands are as follows:
 

clang/include/clang/AST/Type.h

@@ -2560,7 +2560,9 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase {
   bool isFunctionProtoType() const { return getAs<FunctionProtoType>(); }
   bool isPointerType() const;
   bool isPointerOrReferenceType() const;
-  bool isSignableType() const;
+  bool isSignableType(const ASTContext &Ctx) const;
+  bool isSignablePointerType() const;
+  bool isSignableIntegerType(const ASTContext &Ctx) const;
   bool isAnyPointerType() const;   // Any C pointer or ObjC object pointer
   bool isCountAttributedType() const;
   bool isBlockPointerType() const;
@@ -8222,7 +8224,13 @@ inline bool Type::isAnyPointerType() const {
   return isPointerType() || isObjCObjectPointerType();
 }
 
-inline bool Type::isSignableType() const { return isPointerType(); }
+inline bool Type::isSignableType(const ASTContext &Ctx) const {
+  return isSignablePointerType() || isSignableIntegerType(Ctx);
+}
+
+inline bool Type::isSignablePointerType() const {
+  return isPointerType() || isObjCClassType() || isObjCQualifiedClassType();
+}
 
 inline bool Type::isBlockPointerType() const {
   return isa<BlockPointerType>(CanonicalType);

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -1031,10 +1031,12 @@ def err_ptrauth_qualifier_invalid : Error<
   "%select{return type|parameter type|property}1 may not be qualified with '__ptrauth'; type is %0">;
 def err_ptrauth_qualifier_cast : Error<
   "cannot cast to '__ptrauth'-qualified type %0">;
-def err_ptrauth_qualifier_nonpointer : Error<
-  "'__ptrauth' qualifier only applies to pointer types; %0 is invalid">;
-def err_ptrauth_qualifier_redundant : Error<
-  "type %0 is already %1-qualified">;
+def err_ptrauth_qualifier_invalid_target
+    : Error<"'__ptrauth' qualifier only applies to pointer or pointer sized "
+            "integer"
+            " types; %0 is invalid">;
+def err_ptrauth_qualifier_redundant
+    : Error<"type %0 is already __ptrauth-qualified">;
 def err_ptrauth_arg_not_ice : Error<
   "argument to '__ptrauth' must be an integer constant expression">;
 def err_ptrauth_address_discrimination_invalid : Error<

clang/lib/AST/ASTContext.cpp

@@ -2943,6 +2943,9 @@ bool ASTContext::hasUniqueObjectRepresentations(
 
   // All integrals and enums are unique.
   if (Ty->isIntegralOrEnumerationType()) {
+    // Address discriminated integer types are not unique.
+    if (Ty.hasAddressDiscriminatedPointerAuth())
+      return false;
     // Except _BitInt types that have padding bits.
     if (const auto *BIT = Ty->getAs<BitIntType>())
       return getTypeSize(BIT) == BIT->getNumBits();

clang/lib/AST/Type.cpp

@@ -5062,6 +5062,12 @@ AttributedType::stripOuterNullability(QualType &T) {
   return std::nullopt;
 }
 
+bool Type::isSignableIntegerType(const ASTContext &Ctx) const {
+  if (!isIntegralType(Ctx) || isEnumeralType())
+    return false;
+  return Ctx.getTypeSize(this) == Ctx.getTypeSize(Ctx.VoidPtrTy);
+}
+
 bool Type::isBlockCompatibleObjCPointerType(ASTContext &ctx) const {
   const auto *objcPtr = getAs<ObjCObjectPointerType>();
   if (!objcPtr)

clang/lib/CodeGen/CGExprConstant.cpp

@@ -2444,6 +2444,10 @@ ConstantEmitter::tryEmitPrivate(const APValue &Value, QualType DestType,
                                  EnablePtrAuthFunctionTypeDiscrimination)
         .tryEmit();
   case APValue::Int:
+    if (PointerAuthQualifier PointerAuth = DestType.getPointerAuth();
+        PointerAuth &&
+        (PointerAuth.authenticatesNullValues() || Value.getInt() != 0))
+      return nullptr;
     return llvm::ConstantInt::get(CGM.getLLVMContext(), Value.getInt());
   case APValue::FixedPoint:
     return llvm::ConstantInt::get(CGM.getLLVMContext(),

clang/lib/CodeGen/CGExprScalar.cpp

@@ -2300,7 +2300,7 @@ static bool isLValueKnownNonNull(CodeGenFunction &CGF, const Expr *E) {
 }
 
 bool CodeGenFunction::isPointerKnownNonNull(const Expr *E) {
-  assert(E->getType()->isSignableType());
+  assert(E->getType()->isSignableType(getContext()));
 
   E = E->IgnoreParens();
 

clang/lib/CodeGen/CGPointerAuth.cpp

@@ -175,7 +175,7 @@ CGPointerAuthInfo CodeGenModule::getPointerAuthInfoForPointeeType(QualType T) {
 /// pointer type.
 static CGPointerAuthInfo getPointerAuthInfoForType(CodeGenModule &CGM,
                                                    QualType PointerType) {
-  assert(PointerType->isSignableType());
+  assert(PointerType->isSignableType(CGM.getContext()));
 
   // Block pointers are currently not signed.
   if (PointerType->isBlockPointerType())
@@ -209,7 +209,7 @@ emitLoadOfOrigPointerRValue(CodeGenFunction &CGF, const LValue &LV,
 /// needlessly resigning the pointer.
 std::pair<llvm::Value *, CGPointerAuthInfo>
 CodeGenFunction::EmitOrigPointerRValue(const Expr *E) {
-  assert(E->getType()->isSignableType());
+  assert(E->getType()->isSignableType(getContext()));
 
   E = E->IgnoreParens();
   if (const auto *Load = dyn_cast<ImplicitCastExpr>(E)) {
@@ -291,7 +291,10 @@ static bool equalAuthPolicies(const CGPointerAuthInfo &Left,
   if (Left.isSigned() != Right.isSigned())
     return false;
   return Left.getKey() == Right.getKey() &&
-         Left.getAuthenticationMode() == Right.getAuthenticationMode();
+         Left.getAuthenticationMode() == Right.getAuthenticationMode() &&
+         Left.isIsaPointer() == Right.isIsaPointer() &&
+         Left.authenticatesNullValues() == Right.authenticatesNullValues() &&
+         Left.getDiscriminator() == Right.getDiscriminator();
 }
 
 // Return the discriminator or return zero if the discriminator is null.
@@ -642,10 +645,10 @@ llvm::Value *CodeGenFunction::authPointerToPointerCast(llvm::Value *ResultPtr,
                                                        QualType SourceType,
                                                        QualType DestType) {
   CGPointerAuthInfo CurAuthInfo, NewAuthInfo;
-  if (SourceType->isSignableType())
+  if (SourceType->isSignableType(getContext()))
     CurAuthInfo = getPointerAuthInfoForType(CGM, SourceType);
 
-  if (DestType->isSignableType())
+  if (DestType->isSignableType(getContext()))
     NewAuthInfo = getPointerAuthInfoForType(CGM, DestType);
 
   if (!CurAuthInfo && !NewAuthInfo)
@@ -667,10 +670,10 @@ Address CodeGenFunction::authPointerToPointerCast(Address Ptr,
                                                   QualType SourceType,
                                                   QualType DestType) {
   CGPointerAuthInfo CurAuthInfo, NewAuthInfo;
-  if (SourceType->isSignableType())
+  if (SourceType->isSignableType(getContext()))
     CurAuthInfo = getPointerAuthInfoForType(CGM, SourceType);
 
-  if (DestType->isSignableType())
+  if (DestType->isSignableType(getContext()))
     NewAuthInfo = getPointerAuthInfoForType(CGM, DestType);
 
   if (!CurAuthInfo && !NewAuthInfo)

clang/lib/Sema/SemaDeclCXX.cpp

@@ -10888,7 +10888,7 @@ void Sema::checkIllFormedTrivialABIStruct(CXXRecordDecl &RD) {
       return;
     }
 
-    // Ill-formed if the field is an address-discriminated pointer.
+    // Ill-formed if the field is an address-discriminated value.
     if (FT.hasAddressDiscriminatedPointerAuth()) {
       PrintDiagAndRemoveAttr(6);
       return;

clang/lib/Sema/SemaType.cpp

@@ -8379,15 +8379,14 @@ static void HandlePtrAuthQualifier(ASTContext &Ctx, QualType &T,
     return;
   }
 
-  if (!T->isSignableType() && !T->isDependentType()) {
-    S.Diag(Attr.getLoc(), diag::err_ptrauth_qualifier_nonpointer) << T;
+  if (!T->isSignableType(Ctx) && !T->isDependentType()) {
+    S.Diag(Attr.getLoc(), diag::err_ptrauth_qualifier_invalid_target) << T;
     Attr.setInvalid();
     return;
   }
 
   if (T.getPointerAuth()) {
-    S.Diag(Attr.getLoc(), diag::err_ptrauth_qualifier_redundant)
-        << T << Attr.getAttrName()->getName();
+    S.Diag(Attr.getLoc(), diag::err_ptrauth_qualifier_redundant) << T;
     Attr.setInvalid();
     return;
   }
@@ -8402,7 +8401,8 @@ static void HandlePtrAuthQualifier(ASTContext &Ctx, QualType &T,
          "address discriminator arg should be either 0 or 1");
   PointerAuthQualifier Qual = PointerAuthQualifier::Create(
       Key, IsAddressDiscriminated, ExtraDiscriminator,
-      PointerAuthenticationMode::SignAndAuth, false, false);
+      PointerAuthenticationMode::SignAndAuth, /*IsIsaPointer=*/false,
+      /*AuthenticatesNullValues=*/false);
   T = S.Context.getPointerAuthType(T, Qual);
 }