[cfi] Safe handling of unaddressable vtable pointers (clang).

[eugenis]

Summary

Avoid crashing when printing diagnostics for vtable-related CFI
errors. In diagnostic mode, the frontend does an additional check of
the vtable pointer against the set of all known vtable addresses and
lets the runtime handler know if it is safe to inspect the vtable.

[samsonov]

lib/CodeGen/CGExpr.cpp

2493

This is really ugly. Why are you not passing it down in DynamicArgs? Is it performance penalty you don't want to pay if the check will not succeed? How large will it be?

[eugenis]

lib/CodeGen/CGExpr.cpp

2493

Yes, I want this code to be on the failing side of the check.
This would cost about the same as the check itself, so I suspect it could double the overhead.

[pcc]

lib/CodeGen/CGExpr.cpp

2493

I would just emit the call unconditionally. We don't care too much about the performance in non-trapping mode, and if it becomes a problem in practice we can see if we can have the optimizer move the call into the conditional block (which I suspect it already knows how to do).

lib/CodeGen/CodeGenModule.cpp

4061

This conditional doesn't look right. It should be something like

if (sanitize.has(this) && !sanitizetrap.has(this)) ||
   (sanitize.has(that) && !sanitizetrap.has(that)) ||
...

But that's sufficiently ugly that I wonder if we should just do this unconditionally. It shouldn't make a difference to the generated code either way.

[eugenis]

lib/CodeGen/CGExpr.cpp

2493

I care about performance in non-trapping mode.
Doing this change would not make the code any less ugly. For example, EmitCheck may not use the argument if the check has -fsanitize-trap behaviour, in which case we get an unused llvm.bitset.test call that affects some of the clang tests.

[eugenis]

Moved bitset.text call outside.
LLVM is smart enough to sink it along the cold branch, so performance should not suffer.

[eugenis]

lib/CodeGen/CodeGenModule.cpp

4061

I don't like emitting all these bitset entries if they are not needed.
Fixed.

[samsonov]

lib/CodeGen/CGExpr.cpp

2642

This is almost the same as EmitVTablePtrCheck, but with ZExt? Is the difference intentional/important? Is it possible to extract this logic (getting "all-vtables" metadata and running bitset test) to a function?

lib/CodeGen/CodeGenModule.cpp

4028

Hm, can you write this as a loop?

[eugenis]

lib/CodeGen/CGExpr.cpp

2642

Not important. Zext makes the test a bit simpler.
Extracting these two lines to a function is surely possible, but is it worth it?

[samsonov]

LGTM

lib/CodeGen/CGClass.cpp

2608

Can we rewrite this as if-elseif-else block now?

lib/CodeGen/CGExpr.cpp

2642

Probably not, as long as we have the test coverage.

[eugenis]

lib/CodeGen/CGClass.cpp

2608

even better, with 2 early returns.

[eugenis]

http://llvm.org/viewvc/llvm-project?rev=259716&view=rev

lib/CodeGen/CGClass.cpp

void CodeGenFunction::EmitVTablePtrCheck(const CXXRecordDecl *RD,
 
   llvm::Constant *StaticData[] = {
       llvm::ConstantInt::get(Int8Ty, TCK),
       EmitCheckSourceLocation(Loc),
       EmitCheckTypeDescriptor(QualType(RD->getTypeForDecl(), 0)),
   };
 
   auto TypeId = CGM.CreateCfiIdForTypeMetadata(MD);
   if (CGM.getCodeGenOpts().SanitizeCfiCrossDso && TypeId) {
     EmitCfiSlowPathCheck(M, BitSetTest, TypeId, CastedVTable, StaticData);
-  } else {
-    EmitCheck(std::make_pair(BitSetTest, M), "cfi_check_fail", StaticData,
-              CastedVTable);
+    return;
   }
+
+  if (CGM.getCodeGenOpts().SanitizeTrap.has(M)) {
+    EmitTrapCheck(BitSetTest);
+    return;
+  }
+
+  llvm::Value *AllVtables = llvm::MetadataAsValue::get(
+      CGM.getLLVMContext(),
+      llvm::MDString::get(CGM.getLLVMContext(), "all-vtables"));
+  llvm::Value *ValidVtable =
+      Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::bitset_test),
+                         {CastedVTable, AllVtables});
+  EmitCheck(std::make_pair(BitSetTest, M), "cfi_check_fail", StaticData,
+            {CastedVTable, ValidVtable});
 }
 
 // FIXME: Ideally Expr::IgnoreParenNoopCasts should do this, but it doesn't do
 // quite what we want.
 static const Expr *skipNoOpCastsAndParens(const Expr *E) {
   while (true) {
     if (const ParenExpr *PE = dyn_cast<ParenExpr>(E)) {
       E = PE->getSubExpr();

lib/CodeGen/CGExpr.cpp

#endif
   // Give hint that we very much don't expect to execute the handler
   // Value chosen to match UR_NONTAKEN_WEIGHT, see BranchProbabilityInfo.cpp
   llvm::MDBuilder MDHelper(getLLVMContext());
   llvm::MDNode *Node = MDHelper.createBranchWeights((1U << 20) - 1, 1);
   Branch->setMetadata(llvm::LLVMContext::MD_prof, Node);
   EmitBlock(Handlers);
 
   // Handler functions take an i8* pointing to the (handler-specific) static
   // information block, followed by a sequence of intptr_t arguments
   // representing operand values.
   SmallVector<llvm::Value *, 4> Args;
   SmallVector<llvm::Type *, 4> ArgTypes;
   Args.reserve(DynamicArgs.size() + 1);
   ArgTypes.reserve(DynamicArgs.size() + 1);
 
   // Emit handler arguments and create handler function type.
   if (!StaticArgs.empty()) {
void CodeGenFunction::EmitCfiCheckFail() {
 
   llvm::Value *V = Builder.CreateConstGEP2_32(
       CfiCheckFailDataTy,
       Builder.CreatePointerCast(Data, CfiCheckFailDataTy->getPointerTo(0)), 0,
       0);
   Address CheckKindAddr(V, getIntAlign());
   llvm::Value *CheckKind = Builder.CreateLoad(CheckKindAddr);
 
+  llvm::Value *AllVtables = llvm::MetadataAsValue::get(
+      CGM.getLLVMContext(),
+      llvm::MDString::get(CGM.getLLVMContext(), "all-vtables"));
+  llvm::Value *ValidVtable = Builder.CreateZExt(
+      Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::bitset_test),
+                         {Addr, AllVtables}),
+      IntPtrTy);
+
   const std::pair<int, SanitizerMask> CheckKinds[] = {
       {CFITCK_VCall, SanitizerKind::CFIVCall},
       {CFITCK_NVCall, SanitizerKind::CFINVCall},
       {CFITCK_DerivedCast, SanitizerKind::CFIDerivedCast},
       {CFITCK_UnrelatedCast, SanitizerKind::CFIUnrelatedCast},
       {CFITCK_ICall, SanitizerKind::CFIICall}};
 
   SmallVector<std::pair<llvm::Value *, SanitizerMask>, 5> Checks;
   for (auto CheckKindMaskPair : CheckKinds) {
     int Kind = CheckKindMaskPair.first;
     SanitizerMask Mask = CheckKindMaskPair.second;
     llvm::Value *Cond =
         Builder.CreateICmpNE(CheckKind, llvm::ConstantInt::get(Int8Ty, Kind));
-    EmitCheck(std::make_pair(Cond, Mask), "cfi_check_fail", {}, {Data, Addr});
+    EmitCheck(std::make_pair(Cond, Mask), "cfi_check_fail", {},
+              {Data, Addr, ValidVtable});
   }
 
   FinishFunction();
   // The only reference to this function will be created during LTO link.
   // Make sure it survives until then.
   CGM.addUsedGlobal(F);
 }
 
llvm::Constant *StaticData[] = {
         EmitCheckSourceLocation(E->getLocStart()),
         EmitCheckTypeDescriptor(QualType(FnType, 0)),
     };
     if (CGM.getCodeGenOpts().SanitizeCfiCrossDso && TypeId) {
       EmitCfiSlowPathCheck(SanitizerKind::CFIICall, BitSetTest, TypeId,
                            CastedCallee, StaticData);
     } else {
       EmitCheck(std::make_pair(BitSetTest, SanitizerKind::CFIICall),
-                "cfi_check_fail", StaticData, CastedCallee);
+                "cfi_check_fail", StaticData,
+                {CastedCallee, llvm::UndefValue::get(IntPtrTy)});
     }
   }
 
   CallArgList Args;
   if (Chain)
     Args.add(RValue::get(Builder.CreateBitCast(Chain, CGM.VoidPtrTy)),
              CGM.getContext().VoidPtrTy);
   EmitCallArgs(Args, dyn_cast<FunctionProtoType>(FnType), E->arguments(),

lib/CodeGen/CodeGenModule.h

public:
   /// Create a metadata identifier for the given type. This may either be an
   /// MDString (for external identifiers) or a distinct unnamed MDNode (for
   /// internal identifiers).
   llvm::Metadata *CreateMetadataIdentifierForType(QualType T);
 
   /// Create a bitset entry for the given function and add it to BitsetsMD.
   void CreateFunctionBitSetEntry(const FunctionDecl *FD, llvm::Function *F);
 
+  /// Returns whether this module needs the "all-vtables" bitset.
+  bool NeedAllVtablesBitSet() const;
+
   /// Create a bitset entry for the given vtable and add it to BitsetsMD.
   void CreateVTableBitSetEntry(llvm::NamedMDNode *BitsetsMD,
                                llvm::GlobalVariable *VTable, CharUnits Offset,
                                const CXXRecordDecl *RD);
 
   /// \breif Get the declaration of std::terminate for the platform.
   llvm::Constant *getTerminateFn();
 

lib/CodeGen/CodeGenModule.cpp

llvm::Metadata *CodeGenModule::CreateMetadataIdentifierForType(QualType T) {
   } else {
     InternalId = llvm::MDNode::getDistinct(getLLVMContext(),
                                            llvm::ArrayRef<llvm::Metadata *>());
   }
 
   return InternalId;
 }
 
+/// Returns whether this module needs the "all-vtables" bitset.
+bool CodeGenModule::NeedAllVtablesBitSet() const {
+  // Returns true if at least one of vtable-based CFI checkers is enabled and
+  // is not in the trapping mode.
+  return ((LangOpts.Sanitize.has(SanitizerKind::CFIVCall) &&
+           !CodeGenOpts.SanitizeTrap.has(SanitizerKind::CFIVCall)) ||
+          (LangOpts.Sanitize.has(SanitizerKind::CFINVCall) &&
+           !CodeGenOpts.SanitizeTrap.has(SanitizerKind::CFINVCall)) ||
+          (LangOpts.Sanitize.has(SanitizerKind::CFIDerivedCast) &&
+           !CodeGenOpts.SanitizeTrap.has(SanitizerKind::CFIDerivedCast)) ||
+          (LangOpts.Sanitize.has(SanitizerKind::CFIUnrelatedCast) &&
+           !CodeGenOpts.SanitizeTrap.has(SanitizerKind::CFIUnrelatedCast)));
+}
+
 void CodeGenModule::CreateVTableBitSetEntry(llvm::NamedMDNode *BitsetsMD,
                                             llvm::GlobalVariable *VTable,
                                             CharUnits Offset,
                                             const CXXRecordDecl *RD) {
   llvm::Metadata *MD =
       CreateMetadataIdentifierForType(QualType(RD->getTypeForDecl(), 0));
   llvm::Metadata *BitsetOps[] = {
       MD, llvm::ConstantAsMetadata::get(VTable),
       llvm::ConstantAsMetadata::get(
           llvm::ConstantInt::get(Int64Ty, Offset.getQuantity()))};
   BitsetsMD->addOperand(llvm::MDTuple::get(getLLVMContext(), BitsetOps));
 
   if (CodeGenOpts.SanitizeCfiCrossDso) {
     if (auto TypeId = CreateCfiIdForTypeMetadata(MD)) {
       llvm::Metadata *BitsetOps2[] = {
           llvm::ConstantAsMetadata::get(TypeId),
           llvm::ConstantAsMetadata::get(VTable),
           llvm::ConstantAsMetadata::get(
               llvm::ConstantInt::get(Int64Ty, Offset.getQuantity()))};
       BitsetsMD->addOperand(llvm::MDTuple::get(getLLVMContext(), BitsetOps2));
     }
   }
+
+  if (NeedAllVtablesBitSet()) {
+    llvm::Metadata *MD = llvm::MDString::get(getLLVMContext(), "all-vtables");
+    llvm::Metadata *BitsetOps[] = {
+        MD, llvm::ConstantAsMetadata::get(VTable),
+        llvm::ConstantAsMetadata::get(
+            llvm::ConstantInt::get(Int64Ty, Offset.getQuantity()))};
+    // Avoid adding a node to BitsetsMD twice.
+    if (!llvm::MDTuple::getIfExists(getLLVMContext(), BitsetOps))
+      BitsetsMD->addOperand(llvm::MDTuple::get(getLLVMContext(), BitsetOps));
+  }
 }
 
 // Fills in the supplied string map with the set of target features for the
 // passed in function.
 void CodeGenModule::getFunctionFeatureMap(llvm::StringMap<bool> &FeatureMap,
                                           const FunctionDecl *FD) {
   StringRef TargetCPU = Target.getTargetOpts().CPU;
   if (const auto *TD = FD->getAttr<TargetAttr>()) {

test/CodeGen/cfi-check-fail.c

 // CHECK: [[TRAP]]:
 // CHECK-NEXT:   call void @llvm.trap()
 // CHECK-NEXT:   unreachable
 
 // CHECK: [[CONT0]]:
 // CHECK:   %[[A:.*]] = bitcast i8* %[[DATA]] to { i8, { i8*, i32, i32 }, i8* }*
 // CHECK:   %[[KINDPTR:.*]] = getelementptr {{.*}} %[[A]], i32 0, i32 0
 // CHECK:   %[[KIND:.*]] = load i8, i8* %[[KINDPTR]], align 4
+// CHECK:   %[[VTVALID0:.*]] = call i1 @llvm.bitset.test(i8* %[[ADDR]], metadata !"all-vtables")
+// CHECK:   %[[VTVALID:.*]] = zext i1 %[[VTVALID0]] to i64
 // CHECK:   %[[NOT_0:.*]] = icmp ne i8 %[[KIND]], 0
 // CHECK:   br i1 %[[NOT_0]], label %[[CONT1:.*]], label %[[HANDLE0:.*]], !prof
 
 // CHECK: [[HANDLE0]]:
 // CHECK:   %[[DATA0:.*]] = ptrtoint i8* %[[DATA]] to i64,
 // CHECK:   %[[ADDR0:.*]] = ptrtoint i8* %[[ADDR]] to i64,
-// CHECK:   call void @__ubsan_handle_cfi_check_fail(i64 %[[DATA0]], i64 %[[ADDR0]])
+// CHECK:   call void @__ubsan_handle_cfi_check_fail(i64 %[[DATA0]], i64 %[[ADDR0]], i64 %[[VTVALID]])
 // CHECK:   br label %[[CONT1]]
 
 // CHECK: [[CONT1]]:
 // CHECK:   %[[NOT_1:.*]] = icmp ne i8 %[[KIND]], 1
 // CHECK:   br i1 %[[NOT_1]], label %[[CONT2:.*]], label %[[HANDLE1:.*]], !nosanitize
 
 // CHECK: [[HANDLE1]]:
 // CHECK-NEXT:   call void @llvm.trap()
 // CHECK-NEXT:   unreachable
 
 // CHECK: [[CONT2]]:
 // CHECK:   %[[NOT_2:.*]] = icmp ne i8 %[[KIND]], 2
 // CHECK:   br i1 %[[NOT_2]], label %[[CONT3:.*]], label %[[HANDLE2:.*]], !prof
 
 // CHECK: [[HANDLE2]]:
 // CHECK:   %[[DATA2:.*]] = ptrtoint i8* %[[DATA]] to i64,
 // CHECK:   %[[ADDR2:.*]] = ptrtoint i8* %[[ADDR]] to i64,
-// CHECK:   call void @__ubsan_handle_cfi_check_fail_abort(i64 %[[DATA2]], i64 %[[ADDR2]])
+// CHECK:   call void @__ubsan_handle_cfi_check_fail_abort(i64 %[[DATA2]], i64 %[[ADDR2]], i64 %[[VTVALID]])
 // CHECK:   unreachable
 
 // CHECK: [[CONT3]]:
 // CHECK:   %[[NOT_3:.*]] = icmp ne i8 %[[KIND]], 3
 // CHECK:   br i1 %[[NOT_3]], label %[[CONT4:.*]], label %[[HANDLE3:.*]], !prof
 
 // CHECK: [[HANDLE3]]:
 // CHECK:   %[[DATA3:.*]] = ptrtoint i8* %[[DATA]] to i64,
 // CHECK:   %[[ADDR3:.*]] = ptrtoint i8* %[[ADDR]] to i64,
-// CHECK:   call void @__ubsan_handle_cfi_check_fail(i64 %[[DATA3]], i64 %[[ADDR3]])
+// CHECK:   call void @__ubsan_handle_cfi_check_fail(i64 %[[DATA3]], i64 %[[ADDR3]], i64 %[[VTVALID]])
 // CHECK:   br label %[[CONT4]]
 
 // CHECK: [[CONT4]]:
 // CHECK:   %[[NOT_4:.*]] = icmp ne i8 %[[KIND]], 4
 // CHECK:   br i1 %[[NOT_4]], label %[[CONT5:.*]], label %[[HANDLE4:.*]], !nosanitize
 
 // CHECK: [[HANDLE4]]:
 // CHECK-NEXT:   call void @llvm.trap()
 // CHECK-NEXT:   unreachable
 
 // CHECK: [[CONT5]]:
 // CHECK:   ret void

test/CodeGenCXX/cfi-cast.cpp

-// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-derived-cast -fsanitize-trap=cfi-derived-cast -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-DCAST %s
-// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-unrelated-cast -fsanitize-trap=cfi-unrelated-cast -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-UCAST %s
-// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-unrelated-cast,cfi-cast-strict -fsanitize-trap=cfi-unrelated-cast,cfi-cast-strict -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-UCAST-STRICT %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -std=c++11 -fsanitize=cfi-derived-cast -fsanitize-trap=cfi-derived-cast -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-DCAST %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -std=c++11 -fsanitize=cfi-unrelated-cast -fsanitize-trap=cfi-unrelated-cast -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-UCAST %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -std=c++11 -fsanitize=cfi-unrelated-cast,cfi-cast-strict -fsanitize-trap=cfi-unrelated-cast,cfi-cast-strict -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-UCAST-STRICT %s
 
 // In this test the main thing we are searching for is something like
 // 'metadata !"1B"' where "1B" is the mangled name of the class we are
 // casting to (or maybe its base class in non-strict mode).
 
 struct A {
   virtual void f();
   int i() const;
void abp(A *a) {
   // CHECK-DCAST-NEXT: br i1 [[P]], label %[[CONTBB:[^ ]*]], label %[[TRAPBB:[^ ,]*]]
 
   // CHECK-DCAST: [[TRAPBB]]
   // CHECK-DCAST-NEXT: call void @llvm.trap()
   // CHECK-DCAST-NEXT: unreachable
 
   // CHECK-DCAST: [[CONTBB]]
   // CHECK-DCAST: ret
-  static_cast<B*>(a);
+  (void)static_cast<B*>(a);
 }
 
 // CHECK-DCAST-LABEL: define void @_Z3abrR1A
 void abr(A &a) {
   // CHECK-DCAST: [[P:%[^ ]*]] = call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"_ZTS1B")
   // CHECK-DCAST-NEXT: br i1 [[P]], label %[[CONTBB:[^ ]*]], label %[[TRAPBB:[^ ,]*]]
 
   // CHECK-DCAST: [[TRAPBB]]
   // CHECK-DCAST-NEXT: call void @llvm.trap()
   // CHECK-DCAST-NEXT: unreachable
 
   // CHECK-DCAST: [[CONTBB]]
   // CHECK-DCAST: ret
-  static_cast<B&>(a);
+  (void)static_cast<B&>(a);
 }
 
 // CHECK-DCAST-LABEL: define void @_Z4abrrO1A
 void abrr(A &&a) {
   // CHECK-DCAST: [[P:%[^ ]*]] = call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"_ZTS1B")
   // CHECK-DCAST-NEXT: br i1 [[P]], label %[[CONTBB:[^ ]*]], label %[[TRAPBB:[^ ,]*]]
 
   // CHECK-DCAST: [[TRAPBB]]
   // CHECK-DCAST-NEXT: call void @llvm.trap()
   // CHECK-DCAST-NEXT: unreachable
 
   // CHECK-DCAST: [[CONTBB]]
   // CHECK-DCAST: ret
-  static_cast<B&&>(a);
+  (void)static_cast<B&&>(a);
 }
 
 // CHECK-UCAST-LABEL: define void @_Z3vbpPv
 void vbp(void *p) {
   // CHECK-UCAST: [[P:%[^ ]*]] = call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"_ZTS1B")
   // CHECK-UCAST-NEXT: br i1 [[P]], label %[[CONTBB:[^ ]*]], label %[[TRAPBB:[^ ,]*]]
 
   // CHECK-UCAST: [[TRAPBB]]
   // CHECK-UCAST-NEXT: call void @llvm.trap()
   // CHECK-UCAST-NEXT: unreachable
 
   // CHECK-UCAST: [[CONTBB]]
   // CHECK-UCAST: ret
-  static_cast<B*>(p);
+  (void)static_cast<B*>(p);
 }
 
 // CHECK-UCAST-LABEL: define void @_Z3vbrRc
 void vbr(char &r) {
   // CHECK-UCAST: [[P:%[^ ]*]] = call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"_ZTS1B")
   // CHECK-UCAST-NEXT: br i1 [[P]], label %[[CONTBB:[^ ]*]], label %[[TRAPBB:[^ ,]*]]
 
   // CHECK-UCAST: [[TRAPBB]]
   // CHECK-UCAST-NEXT: call void @llvm.trap()
   // CHECK-UCAST-NEXT: unreachable
 
   // CHECK-UCAST: [[CONTBB]]
   // CHECK-UCAST: ret
-  reinterpret_cast<B&>(r);
+  (void)reinterpret_cast<B&>(r);
 }
 
 // CHECK-UCAST-LABEL: define void @_Z4vbrrOc
 void vbrr(char &&r) {
   // CHECK-UCAST: [[P:%[^ ]*]] = call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"_ZTS1B")
   // CHECK-UCAST-NEXT: br i1 [[P]], label %[[CONTBB:[^ ]*]], label %[[TRAPBB:[^ ,]*]]
 
   // CHECK-UCAST: [[TRAPBB]]
   // CHECK-UCAST-NEXT: call void @llvm.trap()
   // CHECK-UCAST-NEXT: unreachable
 
   // CHECK-UCAST: [[CONTBB]]
   // CHECK-UCAST: ret
-  reinterpret_cast<B&&>(r);
+  (void)reinterpret_cast<B&&>(r);
 }
 
 // CHECK-UCAST-LABEL: define void @_Z3vcpPv
 // CHECK-UCAST-STRICT-LABEL: define void @_Z3vcpPv
 void vcp(void *p) {
   // CHECK-UCAST: call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"_ZTS1A")
   // CHECK-UCAST-STRICT: call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"_ZTS1C")
-  static_cast<C*>(p);
+  (void)static_cast<C*>(p);
 }
 
 // CHECK-UCAST-LABEL: define void @_Z3bcpP1B
 // CHECK-UCAST-STRICT-LABEL: define void @_Z3bcpP1B
 void bcp(B *p) {
   // CHECK-UCAST: call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"_ZTS1A")
   // CHECK-UCAST-STRICT: call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"_ZTS1C")
-  (C *)p;
+  (void)(C *)p;
 }
 
 // CHECK-UCAST-LABEL: define void @_Z8bcp_callP1B
 // CHECK-UCAST-STRICT-LABEL: define void @_Z8bcp_callP1B
 void bcp_call(B *p) {
   // CHECK-UCAST: call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"_ZTS1A")
   // CHECK-UCAST-STRICT: call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"_ZTS1C")
   ((C *)p)->f();

test/CodeGenCXX/cfi-vcall.cpp

-// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-vcall -fsanitize-trap=cfi-vcall -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=ITANIUM --check-prefix=NDIAG %s
-// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-vcall -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=ITANIUM --check-prefix=DIAG --check-prefix=DIAG-ABORT %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-vcall -fsanitize-trap=cfi-vcall -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=ITANIUM --check-prefix=ITANIUM-NDIAG --check-prefix=NDIAG %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-vcall -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=ITANIUM --check-prefix=ITANIUM-DIAG --check-prefix=DIAG --check-prefix=DIAG-ABORT %s
 // RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-vcall -fsanitize-recover=cfi-vcall -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=ITANIUM --check-prefix=DIAG --check-prefix=DIAG-RECOVER %s
 // RUN: %clang_cc1 -triple x86_64-pc-windows-msvc -fsanitize=cfi-vcall -fsanitize-trap=cfi-vcall -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=MS --check-prefix=NDIAG %s
 
 // MS: @[[VTA:[0-9]*]] {{.*}} comdat($"\01??_7A@@6B@")
 // MS: @[[VTB:[0-9]*]] {{.*}} comdat($"\01??_7B@@6B0@@")
 // MS: @[[VTAinB:[0-9]*]] {{.*}} comdat($"\01??_7B@@6BA@@@")
 // MS: @[[VTAinC:[0-9]*]] {{.*}} comdat($"\01??_7C@@6B@")
 // MS: @[[VTBinD:[0-9]*]] {{.*}} comdat($"\01??_7D@?A@@6BB@@@")

 void D::f() {
 }
 
 void D::h() {
 }
 
 // DIAG: @[[SRC:.*]] = private unnamed_addr constant [{{.*}} x i8] c"{{.*}}cfi-vcall.cpp\00", align 1
 // DIAG: @[[TYPE:.*]] = private unnamed_addr constant { i16, i16, [4 x i8] } { i16 -1, i16 0, [4 x i8] c"'A'\00" }
-// DIAG: @[[BADTYPESTATIC:.*]] = private unnamed_addr global { i8, { [{{.*}} x i8]*, i32, i32 }, { i16, i16, [4 x i8] }* } { i8 0, { [{{.*}} x i8]*, i32, i32 } { [{{.*}} x i8]* @[[SRC]], i32 [[@LINE+21]], i32 3 }, { i16, i16, [4 x i8] }* @[[TYPE]] }
+// DIAG: @[[BADTYPESTATIC:.*]] = private unnamed_addr global { i8, { [{{.*}} x i8]*, i32, i32 }, { i16, i16, [4 x i8] }* } { i8 0, { [{{.*}} x i8]*, i32, i32 } { [{{.*}} x i8]* @[[SRC]], i32 [[@LINE+23]], i32 3 }, { i16, i16, [4 x i8] }* @[[TYPE]] }
 
 // ITANIUM: define void @_Z2afP1A
 // MS: define void @"\01?af@@YAXPEAUA@@@Z"
 void af(A *a) {
   // ITANIUM: [[P:%[^ ]*]] = call i1 @llvm.bitset.test(i8* [[VT:%[^ ]*]], metadata !"_ZTS1A")
   // MS: [[P:%[^ ]*]] = call i1 @llvm.bitset.test(i8* [[VT:%[^ ]*]], metadata !"?AUA@@")
+  // DIAG-NEXT: [[VTVALID0:%[^ ]*]] = call i1 @llvm.bitset.test(i8* [[VT]], metadata !"all-vtables")
   // CHECK-NEXT: br i1 [[P]], label %[[CONTBB:[^ ,]*]], label %[[TRAPBB:[^ ,]*]]
   // CHECK-NEXT: {{^$}}
 
   // CHECK: [[TRAPBB]]
   // NDIAG-NEXT: call void @llvm.trap()
   // NDIAG-NEXT: unreachable
   // DIAG-NEXT: [[VTINT:%[^ ]*]] = ptrtoint i8* [[VT]] to i64
-  // DIAG-ABORT-NEXT: call void @__ubsan_handle_cfi_check_fail_abort(i8* getelementptr inbounds ({{.*}} @[[BADTYPESTATIC]], i32 0, i32 0), i64 [[VTINT]])
+  // DIAG-NEXT: [[VTVALID:%[^ ]*]] = zext i1 [[VTVALID0]] to i64
+  // DIAG-ABORT-NEXT: call void @__ubsan_handle_cfi_check_fail_abort(i8* getelementptr inbounds ({{.*}} @[[BADTYPESTATIC]], i32 0, i32 0), i64 [[VTINT]], i64 [[VTVALID]])
   // DIAG-ABORT-NEXT: unreachable
-  // DIAG-RECOVER-NEXT: call void @__ubsan_handle_cfi_check_fail(i8* getelementptr inbounds ({{.*}} @[[BADTYPESTATIC]], i32 0, i32 0), i64 [[VTINT]])
+  // DIAG-RECOVER-NEXT: call void @__ubsan_handle_cfi_check_fail(i8* getelementptr inbounds ({{.*}} @[[BADTYPESTATIC]], i32 0, i32 0), i64 [[VTINT]], i64 [[VTVALID]])
   // DIAG-RECOVER-NEXT: br label %[[CONTBB]]
 
   // CHECK: [[CONTBB]]
   // CHECK: call void %
   a->f();
 }
 
 // ITANIUM: define internal void @_Z3df1PN12_GLOBAL__N_11DE

 void f(D *d) {
   // ITANIUM: {{%[^ ]*}} = call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"_ZTSN5test21DE")
   // MS: {{%[^ ]*}} = call i1 @llvm.bitset.test(i8* {{%[^ ]*}}, metadata !"?AUA@test2@@")
   d->m_fn1();
 }
 
 }
 
-// Check for the expected number of elements (9 or 15 respectively).
-// MS: !llvm.bitsets = !{[[X:[^,]*(,[^,]*){8}]]}
-// ITANIUM: !llvm.bitsets = !{[[X:[^,]*(,[^,]*){14}]]}
+// Check for the expected number of elements (15 or 23 respectively).
+// MS-NDIAG: !llvm.bitsets = !{[[X:[^,]*(,[^,]*){9}]]}
+// MS-DIAG: !llvm.bitsets = !{[[X:[^,]*(,[^,]*){15}]]}
+// ITANIUM-NDIAG: !llvm.bitsets = !{[[X:[^,]*(,[^,]*){14}]]}
+// ITANIUM-DIAG: !llvm.bitsets = !{[[X:[^,]*(,[^,]*){23}]]}
 
 // ITANIUM-DAG: !{!"_ZTS1A", [3 x i8*]* @_ZTV1A, i64 16}
+// ITANIUM-DIAG-DAG: !{!"all-vtables", [3 x i8*]* @_ZTV1A, i64 16}
 // ITANIUM-DAG: !{!"_ZTS1A", [7 x i8*]* @_ZTCN12_GLOBAL__N_11DE0_1B, i64 32}
+// ITANIUM-DIAG-DAG: !{!"all-vtables", [7 x i8*]* @_ZTCN12_GLOBAL__N_11DE0_1B, i64 32}
 // ITANIUM-DAG: !{!"_ZTS1B", [7 x i8*]* @_ZTCN12_GLOBAL__N_11DE0_1B, i64 32}
 // ITANIUM-DAG: !{!"_ZTS1A", [9 x i8*]* @_ZTCN12_GLOBAL__N_11DE8_1C, i64 64}
+// ITANIUM-DIAG-DAG: !{!"all-vtables", [9 x i8*]* @_ZTCN12_GLOBAL__N_11DE8_1C, i64 64}
 // ITANIUM-DAG: !{!"_ZTS1C", [9 x i8*]* @_ZTCN12_GLOBAL__N_11DE8_1C, i64 32}
 // ITANIUM-DAG: !{!"_ZTS1A", [12 x i8*]* @_ZTVN12_GLOBAL__N_11DE, i64 32}
+// ITANIUM-DIAG-DAG: !{!"all-vtables", [12 x i8*]* @_ZTVN12_GLOBAL__N_11DE, i64 32}
 // ITANIUM-DAG: !{!"_ZTS1B", [12 x i8*]* @_ZTVN12_GLOBAL__N_11DE, i64 32}
 // ITANIUM-DAG: !{!"_ZTS1C", [12 x i8*]* @_ZTVN12_GLOBAL__N_11DE, i64 88}
+// ITANIUM-DIAG-DAG: !{!"all-vtables", [12 x i8*]* @_ZTVN12_GLOBAL__N_11DE, i64 88}
 // ITANIUM-DAG: !{![[DTYPE]], [12 x i8*]* @_ZTVN12_GLOBAL__N_11DE, i64 32}
 // ITANIUM-DAG: !{!"_ZTS1A", [7 x i8*]* @_ZTV1B, i64 32}
+// ITANIUM-DIAG-DAG: !{!"all-vtables", [7 x i8*]* @_ZTV1B, i64 32}
 // ITANIUM-DAG: !{!"_ZTS1B", [7 x i8*]* @_ZTV1B, i64 32}
 // ITANIUM-DAG: !{!"_ZTS1A", [5 x i8*]* @_ZTV1C, i64 32}
 // ITANIUM-DAG: !{!"_ZTS1C", [5 x i8*]* @_ZTV1C, i64 32}
 // ITANIUM-DAG: !{!"_ZTS1A", [3 x i8*]* @_ZTVZ3foovE2FA, i64 16}
 // ITANIUM-DAG: !{!{{[0-9]+}}, [3 x i8*]* @_ZTVZ3foovE2FA, i64 16}
 
 // MS-DAG: !{!"?AUA@@", [2 x i8*]* @[[VTA]], i64 8}
+// MS-DIAG-DAG: !{!"all-vtables", [2 x i8*]* @[[VTA]], i64 8}
 // MS-DAG: !{!"?AUB@@", [3 x i8*]* @[[VTB]], i64 8}
+// MS-DIAG-DAG: !{!"all-vtables", [3 x i8*]* @[[VTB]], i64 8}
 // MS-DAG: !{!"?AUA@@", [2 x i8*]* @[[VTAinB]], i64 8}
+// MS-DIAG-DAG: !{!"all-vtables", [2 x i8*]* @[[VTAinB]], i64 8}
 // MS-DAG: !{!"?AUA@@", [2 x i8*]* @[[VTAinC]], i64 8}
+// MS-DIAG-DAG: !{!"all-vtables", [2 x i8*]* @[[VTAinC]], i64 8}
 // MS-DAG: !{!"?AUB@@", [3 x i8*]* @[[VTBinD]], i64 8}
+// MS-DIAG-DAG: !{!"all-vtables", [3 x i8*]* @[[VTBinD]], i64 8}
 // MS-DAG: !{![[DTYPE]], [3 x i8*]* @[[VTBinD]], i64 8}
 // MS-DAG: !{!"?AUA@@", [2 x i8*]* @[[VTAinBinD]], i64 8}
+// MS-DIAG-DAG: !{!"all-vtables", [2 x i8*]* @[[VTAinBinD]], i64 8}
 // MS-DAG: !{!"?AUA@@", [2 x i8*]* @[[VTFA]], i64 8}
+// MS-DIAG-DAG: !{!"all-vtables", [2 x i8*]* @[[VTFA]], i64 8}
 // MS-DAG: !{!{{[0-9]+}}, [2 x i8*]* @[[VTFA]], i64 8}