1 files changed, 46 insertions, 12 deletions

diff --git a/clang/lib/CodeGen/CGVTables.cpp b/clang/lib/CodeGen/CGVTables.cpp
index cdd40d2a6a2e..a0b5d9e4b096 100644
--- a/clang/lib/CodeGen/CGVTables.cpp
+++ b/clang/lib/CodeGen/CGVTables.cpp
@@ -128,7 +128,7 @@ static void resolveTopLevelMetadata(llvm::Function *Fn,
 
   // Find all llvm.dbg.declare intrinsics and resolve the DILocalVariable nodes
   // they are referencing.
-  for (auto &BB : Fn->getBasicBlockList()) {
+  for (auto &BB : *Fn) {
     for (auto &I : BB) {
       if (auto *DII = dyn_cast<llvm::DbgVariableIntrinsic>(&I)) {
         auto *DILocal = DII->getVariable();
@@ -664,6 +664,12 @@ void CodeGenVTables::addRelativeComponent(ConstantArrayBuilder &builder,
         proxy->setVisibility(llvm::GlobalValue::HiddenVisibility);
         proxy->setComdat(module.getOrInsertComdat(rttiProxyName));
       }
+      // Do not instrument the rtti proxies with hwasan to avoid a duplicate
+      // symbol error. Aliases generated by hwasan will retain the same namebut
+      // the addresses they are set to may have different tags from different
+      // compilation units. We don't run into this without hwasan because the
+      // proxies are in comdat groups, but those aren't propagated to the alias.
+      RemoveHwasanMetadata(proxy);
     }
     target = proxy;
   }
@@ -672,15 +678,23 @@ void CodeGenVTables::addRelativeComponent(ConstantArrayBuilder &builder,
                                       /*position=*/vtableAddressPoint);
 }
 
-bool CodeGenVTables::useRelativeLayout() const {
+static bool UseRelativeLayout(const CodeGenModule &CGM) {
   return CGM.getTarget().getCXXABI().isItaniumFamily() &&
          CGM.getItaniumVTableContext().isRelativeLayout();
 }
 
+bool CodeGenVTables::useRelativeLayout() const {
+  return UseRelativeLayout(CGM);
+}
+
+llvm::Type *CodeGenModule::getVTableComponentType() const {
+  if (UseRelativeLayout(*this))
+    return Int32Ty;
+  return Int8PtrTy;
+}
+
 llvm::Type *CodeGenVTables::getVTableComponentType() const {
-  if (useRelativeLayout())
-    return CGM.Int32Ty;
-  return CGM.Int8PtrTy;
+  return CGM.getVTableComponentType();
 }
 
 static void AddPointerLayoutOffset(const CodeGenModule &CGM,
@@ -895,7 +909,7 @@ llvm::GlobalVariable *CodeGenVTables::GenerateConstructionVTable(
   if (Linkage == llvm::GlobalVariable::AvailableExternallyLinkage)
     Linkage = llvm::GlobalVariable::InternalLinkage;
 
-  unsigned Align = CGM.getDataLayout().getABITypeAlignment(VTType);
+  llvm::Align Align = CGM.getDataLayout().getABITypeAlign(VTType);
 
   // Create the variable that will hold the construction vtable.
   llvm::GlobalVariable *VTable =
@@ -921,12 +935,33 @@ llvm::GlobalVariable *CodeGenVTables::GenerateConstructionVTable(
 
   CGM.EmitVTableTypeMetadata(RD, VTable, *VTLayout.get());
 
-  if (UsingRelativeLayout && !VTable->isDSOLocal())
-    GenerateRelativeVTableAlias(VTable, OutName);
+  if (UsingRelativeLayout) {
+    RemoveHwasanMetadata(VTable);
+    if (!VTable->isDSOLocal())
+      GenerateRelativeVTableAlias(VTable, OutName);
+  }
 
   return VTable;
 }
 
+// Ensure this vtable is not instrumented by hwasan. That is, a global alias is
+// not generated for it. This is mainly used by the relative-vtables ABI where
+// vtables instead contain 32-bit offsets between the vtable and function
+// pointers. Hwasan is disabled for these vtables for now because the tag in a
+// vtable pointer may fail the overflow check when resolving 32-bit PLT
+// relocations. A future alternative for this would be finding which usages of
+// the vtable can continue to use the untagged hwasan value without any loss of
+// value in hwasan.
+void CodeGenVTables::RemoveHwasanMetadata(llvm::GlobalValue *GV) const {
+  if (CGM.getLangOpts().Sanitize.has(SanitizerKind::HWAddress)) {
+    llvm::GlobalValue::SanitizerMetadata Meta;
+    if (GV->hasSanitizerMetadata())
+      Meta = GV->getSanitizerMetadata();
+    Meta.NoHWAddress = true;
+    GV->setSanitizerMetadata(Meta);
+  }
+}
+
 // If the VTable is not dso_local, then we will not be able to indicate that
 // the VTable does not need a relocation and move into rodata. A frequent
 // time this can occur is for classes that should be made public from a DSO
@@ -1254,8 +1289,7 @@ void CodeGenModule::EmitVTableTypeMetadata(const CXXRecordDecl *RD,
   if (!getCodeGenOpts().LTOUnit)
     return;
 
-  CharUnits PointerWidth =
-      Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
+  CharUnits ComponentWidth = GetTargetTypeStoreSize(getVTableComponentType());
 
   typedef std::pair<const CXXRecordDecl *, unsigned> AddressPoint;
   std::vector<AddressPoint> AddressPoints;
@@ -1293,7 +1327,7 @@ void CodeGenModule::EmitVTableTypeMetadata(const CXXRecordDecl *RD,
   ArrayRef<VTableComponent> Comps = VTLayout.vtable_components();
   for (auto AP : AddressPoints) {
     // Create type metadata for the address point.
-    AddVTableTypeMetadata(VTable, PointerWidth * AP.second, AP.first);
+    AddVTableTypeMetadata(VTable, ComponentWidth * AP.second, AP.first);
 
     // The class associated with each address point could also potentially be
     // used for indirect calls via a member function pointer, so we need to
@@ -1306,7 +1340,7 @@ void CodeGenModule::EmitVTableTypeMetadata(const CXXRecordDecl *RD,
           Context.getMemberPointerType(
               Comps[I].getFunctionDecl()->getType(),
               Context.getRecordType(AP.first).getTypePtr()));
-      VTable->addTypeMetadata((PointerWidth * I).getQuantity(), MD);
+      VTable->addTypeMetadata((ComponentWidth * I).getQuantity(), MD);
     }
   }