[PAC] Fix address discrimination for type info vtable pointers (llvm#…

…102199)

In llvm#99726, `-fptrauth-type-info-vtable-pointer-discrimination` was
introduced, which is intended to enable type and address discrimination
for type_info vtable pointers. However, some codegen logic for actually
enabling address discrimination was missing. This patch addresses the
issue.

Fixes llvm#101716

clang/lib/CodeGen/ItaniumCXXABI.cpp

@@ -3437,7 +3437,7 @@ class ItaniumRTTIBuilder {
   llvm::Constant *GetAddrOfExternalRTTIDescriptor(QualType Ty);
 
   /// BuildVTablePointer - Build the vtable pointer for the given type.
-  void BuildVTablePointer(const Type *Ty);
+  void BuildVTablePointer(const Type *Ty, llvm::Constant *StorageAddress);
 
   /// BuildSIClassTypeInfo - Build an abi::__si_class_type_info, used for single
   /// inheritance, according to the Itanium C++ ABI, 2.9.5p6b.
@@ -3834,7 +3834,8 @@ static bool CanUseSingleInheritance(const CXXRecordDecl *RD) {
   return true;
 }
 
-void ItaniumRTTIBuilder::BuildVTablePointer(const Type *Ty) {
+void ItaniumRTTIBuilder::BuildVTablePointer(const Type *Ty,
+                                            llvm::Constant *StorageAddress) {
   // abi::__class_type_info.
   static const char * const ClassTypeInfo =
     "_ZTVN10__cxxabiv117__class_type_infoE";
@@ -3981,9 +3982,12 @@ void ItaniumRTTIBuilder::BuildVTablePointer(const Type *Ty) {
                                                           VTable, Two);
   }
 
-  if (auto &Schema = CGM.getCodeGenOpts().PointerAuth.CXXTypeInfoVTablePointer)
-    VTable = CGM.getConstantSignedPointer(VTable, Schema, nullptr, GlobalDecl(),
-                                          QualType(Ty, 0));
+  if (const auto &Schema =
+          CGM.getCodeGenOpts().PointerAuth.CXXTypeInfoVTablePointer)
+    VTable = CGM.getConstantSignedPointer(
+        VTable, Schema,
+        Schema.isAddressDiscriminated() ? StorageAddress : nullptr,
+        GlobalDecl(), QualType(Ty, 0));
 
   Fields.push_back(VTable);
 }
@@ -4099,8 +4103,18 @@ llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(
       llvm::GlobalVariable::LinkageTypes Linkage,
       llvm::GlobalValue::VisibilityTypes Visibility,
       llvm::GlobalValue::DLLStorageClassTypes DLLStorageClass) {
+  SmallString<256> Name;
+  llvm::raw_svector_ostream Out(Name);
+  CGM.getCXXABI().getMangleContext().mangleCXXRTTI(Ty, Out);
+  llvm::Module &M = CGM.getModule();
+  llvm::GlobalVariable *OldGV = M.getNamedGlobal(Name);
+  // int8 is an arbitrary type to be replaced later with replaceInitializer.
+  llvm::GlobalVariable *GV =
+      new llvm::GlobalVariable(M, CGM.Int8Ty, /*isConstant=*/true, Linkage,
+                               /*Initializer=*/nullptr, Name);
+
   // Add the vtable pointer.
-  BuildVTablePointer(cast<Type>(Ty));
+  BuildVTablePointer(cast<Type>(Ty), GV);
 
   // And the name.
   llvm::GlobalVariable *TypeName = GetAddrOfTypeName(Ty, Linkage);
@@ -4218,16 +4232,7 @@ llvm::Constant *ItaniumRTTIBuilder::BuildTypeInfo(
     llvm_unreachable("HLSL doesn't support RTTI");
   }
 
-  llvm::Constant *Init = llvm::ConstantStruct::getAnon(Fields);
-
-  SmallString<256> Name;
-  llvm::raw_svector_ostream Out(Name);
-  CGM.getCXXABI().getMangleContext().mangleCXXRTTI(Ty, Out);
-  llvm::Module &M = CGM.getModule();
-  llvm::GlobalVariable *OldGV = M.getNamedGlobal(Name);
-  llvm::GlobalVariable *GV =
-      new llvm::GlobalVariable(M, Init->getType(),
-                               /*isConstant=*/true, Linkage, Init, Name);
+  GV->replaceInitializer(llvm::ConstantStruct::getAnon(Fields));
 
   // Export the typeinfo in the same circumstances as the vtable is exported.
   auto GVDLLStorageClass = DLLStorageClass;

clang/test/CodeGenCXX/RelativeVTablesABI/child-inheritted-from-parent-in-comdat.cpp

@@ -4,8 +4,8 @@
 // RUN: %clang_cc1 %s -triple=aarch64-unknown-fuchsia -O1 -o - -emit-llvm -fhalf-no-semantic-interposition | FileCheck %s
 
 // The inline function is emitted in each module with the same comdat
-// CHECK: $_ZTS1A = comdat any
 // CHECK: $_ZTI1A = comdat any
+// CHECK: $_ZTS1A = comdat any
 // CHECK: $_ZTI1B.rtti_proxy = comdat any
 
 // The VTable is emitted everywhere used

clang/test/CodeGenCXX/RelativeVTablesABI/inlined-key-function.cpp

@@ -4,8 +4,8 @@
 // RUN: %clang_cc1 %s -triple=aarch64-unknown-fuchsia -O1 -o - -emit-llvm | FileCheck %s
 
 // CHECK: $_ZTV1A = comdat any
-// CHECK: $_ZTS1A = comdat any
 // CHECK: $_ZTI1A = comdat any
+// CHECK: $_ZTS1A = comdat any
 // CHECK: $_ZTI1A.rtti_proxy = comdat any
 
 // The VTable is linkonce_odr and in a comdat here bc it’s key function is inline defined.

clang/test/CodeGenCXX/RelativeVTablesABI/parent-and-child-in-comdats.cpp

@@ -8,12 +8,12 @@
 // CHECK: $_ZN1A3fooEv = comdat any
 // CHECK: $_ZN1B3fooEv = comdat any
 // CHECK: $_ZTV1A = comdat any
-// CHECK: $_ZTS1A = comdat any
 // CHECK: $_ZTI1A = comdat any
+// CHECK: $_ZTS1A = comdat any
 // CHECK: $_ZTI1A.rtti_proxy = comdat any
 // CHECK: $_ZTV1B = comdat any
-// CHECK: $_ZTS1B = comdat any
 // CHECK: $_ZTI1B = comdat any
+// CHECK: $_ZTS1B = comdat any
 // CHECK: $_ZTI1B.rtti_proxy = comdat any
 
 // Both the vtables for A and B are emitted and in their own comdats.

clang/test/CodeGenCXX/RelativeVTablesABI/parent-vtable-in-comdat.cpp

@@ -7,17 +7,17 @@
 // A::foo() has a comdat since it is an inline function
 // CHECK: $_ZN1A3fooEv = comdat any
 // CHECK: $_ZTV1A = comdat any
+// CHECK: $_ZTI1A = comdat any
 // CHECK: $_ZTS1A = comdat any
 
 // The VTable for A has its own comdat section bc it has no key function
-// CHECK: $_ZTI1A = comdat any
 // CHECK: $_ZTI1A.rtti_proxy = comdat any
 
 // The VTable for A is emitted here and in a comdat section since it has no key function, and is used in this module when creating an instance of A.
 // CHECK: @_ZTV1A.local = linkonce_odr hidden unnamed_addr constant { [3 x i32] } { [3 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr @_ZTI1A.rtti_proxy to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @_ZN1A3fooEv to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32)] }, comdat($_ZTV1A), align 4
+// CHECK: @_ZTI1A = linkonce_odr constant { ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i32 8), ptr @_ZTS1A }, comdat, align 8
 // CHECK: @_ZTVN10__cxxabiv117__class_type_infoE = external global [0 x ptr]
 // CHECK: @_ZTS1A = linkonce_odr constant [3 x i8] c"1A\00", comdat, align 1
-// CHECK: @_ZTI1A = linkonce_odr constant { ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i32 8), ptr @_ZTS1A }, comdat, align 8
 // CHECK: @_ZTI1A.rtti_proxy = linkonce_odr hidden unnamed_addr constant ptr @_ZTI1A, comdat
 // CHECK: @_ZTV1A = linkonce_odr unnamed_addr alias { [3 x i32] }, ptr @_ZTV1A.local
 

clang/test/CodeGenCXX/RelativeVTablesABI/simple-vtable-definition.cpp

@@ -9,9 +9,9 @@
 // The vtable definition itself is private so we can take relative references to
 // it. The vtable symbol will be exposed through a public alias.
 // CHECK: @_ZTV1A.local = internal unnamed_addr constant { [3 x i32] } { [3 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr @_ZTI1A.rtti_proxy to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @_ZN1A3fooEv to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32)] }, align 4
+// CHECK: @_ZTI1A ={{.*}} constant { ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i32 8), ptr @_ZTS1A }, align 8
 // CHECK: @_ZTVN10__cxxabiv117__class_type_infoE = external global [0 x ptr]
 // CHECK: @_ZTS1A ={{.*}} constant [3 x i8] c"1A\00", align 1
-// CHECK: @_ZTI1A ={{.*}} constant { ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i32 8), ptr @_ZTS1A }, align 8
 
 // The rtti should be in a comdat
 // CHECK: @_ZTI1A.rtti_proxy = {{.*}}comdat

clang/test/CodeGenCXX/RelativeVTablesABI/type-info.cpp

@@ -5,12 +5,12 @@
 // CHECK: $_ZTI1A.rtti_proxy = comdat any
 // CHECK: $_ZTI1B.rtti_proxy = comdat any
 
+// CHECK: @_ZTI1A ={{.*}} constant { ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i32 8), ptr @_ZTS1A }, align 8
 // CHECK: @_ZTVN10__cxxabiv117__class_type_infoE = external global [0 x ptr]
 // CHECK: @_ZTS1A ={{.*}} constant [3 x i8] c"1A\00", align 1
-// CHECK: @_ZTI1A ={{.*}} constant { ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i32 8), ptr @_ZTS1A }, align 8
+// CHECK: @_ZTI1B ={{.*}} constant { ptr, ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv120__si_class_type_infoE, i32 8), ptr @_ZTS1B, ptr @_ZTI1A }, align 8
 // CHECK: @_ZTVN10__cxxabiv120__si_class_type_infoE = external global [0 x ptr]
 // CHECK: @_ZTS1B ={{.*}} constant [3 x i8] c"1B\00", align 1
-// CHECK: @_ZTI1B ={{.*}} constant { ptr, ptr, ptr } { ptr getelementptr inbounds (i8, ptr @_ZTVN10__cxxabiv120__si_class_type_infoE, i32 8), ptr @_ZTS1B, ptr @_ZTI1A }, align 8
 // CHECK: @_ZTI1A.rtti_proxy = linkonce_odr hidden unnamed_addr constant ptr @_ZTI1A, comdat
 // CHECK: @_ZTI1B.rtti_proxy = linkonce_odr hidden unnamed_addr constant ptr @_ZTI1B, comdat
 

clang/test/CodeGenCXX/armv7k.cpp

@@ -50,17 +50,17 @@ namespace test2 {
 
   struct __attribute__((visibility("hidden"))) B {};
   const std::type_info &b0 = typeid(B);
-  // CHECK-GLOBALS: @_ZTSN5test21BE = linkonce_odr hidden constant
   // CHECK-GLOBALS: @_ZTIN5test21BE = linkonce_odr hidden constant { {{.*}}, ptr @_ZTSN5test21BE }
+  // CHECK-GLOBALS: @_ZTSN5test21BE = linkonce_odr hidden constant
 
   const std::type_info &b1 = typeid(B*);
-  // CHECK-GLOBALS: @_ZTSPN5test21BE = linkonce_odr hidden constant
   // CHECK-GLOBALS: @_ZTIPN5test21BE = linkonce_odr hidden constant { {{.*}}, ptr @_ZTSPN5test21BE, i32 0, ptr @_ZTIN5test21BE
+  // CHECK-GLOBALS: @_ZTSPN5test21BE = linkonce_odr hidden constant
 
   struct C {};
   const std::type_info &c0 = typeid(C);
-  // CHECK-GLOBALS: @_ZTSN5test21CE = linkonce_odr constant [11 x i8] c"N5test21CE\00"
   // CHECK-GLOBALS: @_ZTIN5test21CE = linkonce_odr constant { {{.*}}, ptr @_ZTSN5test21CE }
+  // CHECK-GLOBALS: @_ZTSN5test21CE = linkonce_odr constant [11 x i8] c"N5test21CE\00"
 }
 
 // va_list should be based on "char *" rather than "ptr".

clang/test/CodeGenCXX/dynamic-cast-address-space.cpp

@@ -10,17 +10,17 @@ B fail;
 // CHECK: @_ZTV1B = linkonce_odr unnamed_addr addrspace(1) constant { [3 x ptr addrspace(1)] } { [3 x ptr addrspace(1)] [ptr addrspace(1) null, ptr addrspace(1) @_ZTI1B, ptr addrspace(1) addrspacecast (ptr @_ZN1A1fEv to ptr addrspace(1))] }, comdat, align 8
 // CHECK: @fail = addrspace(1) global { ptr addrspace(1) } { ptr addrspace(1) getelementptr inbounds inrange(-16, 8) ({ [3 x ptr addrspace(1)] }, ptr addrspace(1) @_ZTV1B, i32 0, i32 0, i32 2) }, align 8
 // CHECK: @_ZTI1A = external addrspace(1) constant ptr addrspace(1)
+// CHECK: @_ZTI1B = linkonce_odr addrspace(1) constant { ptr addrspace(1), ptr addrspace(1), ptr addrspace(1) } { ptr addrspace(1) getelementptr inbounds (ptr addrspace(1), ptr addrspace(1) @_ZTVN10__cxxabiv120__si_class_type_infoE, i64 2), ptr addrspace(1) @_ZTS1B, ptr addrspace(1) @_ZTI1A }, comdat, align 8
 // CHECK: @_ZTVN10__cxxabiv120__si_class_type_infoE = external addrspace(1) global [0 x ptr addrspace(1)]
 // CHECK: @_ZTS1B = linkonce_odr addrspace(1) constant [3 x i8] c"1B\00", comdat, align 1
-// CHECK: @_ZTI1B = linkonce_odr addrspace(1) constant { ptr addrspace(1), ptr addrspace(1), ptr addrspace(1) } { ptr addrspace(1) getelementptr inbounds (ptr addrspace(1), ptr addrspace(1) @_ZTVN10__cxxabiv120__si_class_type_infoE, i64 2), ptr addrspace(1) @_ZTS1B, ptr addrspace(1) @_ZTI1A }, comdat, align 8
 // CHECK: @__oclc_ABI_version = weak_odr hidden local_unnamed_addr addrspace(4) constant i32 500
 //.
 // WITH-NONZERO-DEFAULT-AS: @_ZTV1B = linkonce_odr unnamed_addr addrspace(1) constant { [3 x ptr addrspace(1)] } { [3 x ptr addrspace(1)] [ptr addrspace(1) null, ptr addrspace(1) @_ZTI1B, ptr addrspace(1) addrspacecast (ptr addrspace(4) @_ZN1A1fEv to ptr addrspace(1))] }, comdat, align 8
 // WITH-NONZERO-DEFAULT-AS: @fail = addrspace(1) global { ptr addrspace(1) } { ptr addrspace(1) getelementptr inbounds inrange(-16, 8) ({ [3 x ptr addrspace(1)] }, ptr addrspace(1) @_ZTV1B, i32 0, i32 0, i32 2) }, align 8
 // WITH-NONZERO-DEFAULT-AS: @_ZTI1A = external addrspace(1) constant ptr addrspace(1)
+// WITH-NONZERO-DEFAULT-AS: @_ZTI1B = linkonce_odr addrspace(1) constant { ptr addrspace(1), ptr addrspace(1), ptr addrspace(1) } { ptr addrspace(1) getelementptr inbounds (ptr addrspace(1), ptr addrspace(1) @_ZTVN10__cxxabiv120__si_class_type_infoE, i64 2), ptr addrspace(1) @_ZTS1B, ptr addrspace(1) @_ZTI1A }, comdat, align 8
 // WITH-NONZERO-DEFAULT-AS: @_ZTVN10__cxxabiv120__si_class_type_infoE = external addrspace(1) global [0 x ptr addrspace(1)]
 // WITH-NONZERO-DEFAULT-AS: @_ZTS1B = linkonce_odr addrspace(1) constant [3 x i8] c"1B\00", comdat, align 1
-// WITH-NONZERO-DEFAULT-AS: @_ZTI1B = linkonce_odr addrspace(1) constant { ptr addrspace(1), ptr addrspace(1), ptr addrspace(1) } { ptr addrspace(1) getelementptr inbounds (ptr addrspace(1), ptr addrspace(1) @_ZTVN10__cxxabiv120__si_class_type_infoE, i64 2), ptr addrspace(1) @_ZTS1B, ptr addrspace(1) @_ZTI1A }, comdat, align 8
 //.
 // CHECK-LABEL: define dso_local noundef nonnull align 8 dereferenceable(8) ptr @_Z1fP1A(
 // CHECK-SAME: ptr noundef [[A:%.*]]) #[[ATTR0:[0-9]+]] personality ptr @__gxx_personality_v0 {

clang/test/CodeGenCXX/exceptions-no-rtti.cpp

@@ -3,8 +3,8 @@
 // CHECK: @_ZTIN5test11AE = linkonce_odr constant
 // CHECK: @_ZTIN5test11BE = linkonce_odr constant
 // CHECK: @_ZTIN5test11CE = linkonce_odr constant
-// CHECK: @_ZTIN5test11DE = linkonce_odr constant
 // CHECK: @_ZTIPN5test11DE = linkonce_odr constant {{.*}} @_ZTIN5test11DE
+// CHECK: @_ZTIN5test11DE = linkonce_odr constant
 
 // PR6974: this shouldn't crash
 namespace test0 {

clang/test/CodeGenCXX/implicit-record-visibility.cpp

@@ -7,6 +7,6 @@
 // under -fvisibility=hidden the type of function f, due to its va_list (aka
 // __builtin_va_list, aka __va_list_tag (*)[1]) parameter would be hidden:
 
-// CHECK: @_ZTSFvP13__va_list_tagE = linkonce_odr constant
 // CHECK: @_ZTIFvP13__va_list_tagE = linkonce_odr constant
+// CHECK: @_ZTSFvP13__va_list_tagE = linkonce_odr constant
 void f(va_list) { (void)typeid(f); }