[UBSan] Add !nosanitize metadata to the code generated by UBSan.

This is used to mark the instructions emitted by Clang to implement
variety of UBSan checks. Generally, we don't want to instrument these
instructions with another sanitizers (like ASan).

Reviewed in http://reviews.llvm.org/D4544

llvm-svn: 213291

5 files changed, 64 insertions, 18 deletions

diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 4bdc87e2d42..4f68b347dbf 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -447,11 +447,12 @@ RValue CodeGenFunction::EmitBuiltinExpr(const FunctionDecl *FD,
     return RValue::get(Builder.CreateCall(F));
   }
   case Builtin::BI__builtin_unreachable: {
-    if (SanOpts->Unreachable)
+    if (SanOpts->Unreachable) {
+      SanitizerScope SanScope(this);
       EmitCheck(Builder.getFalse(), "builtin_unreachable",
                 EmitCheckSourceLocation(E->getExprLoc()),
                 ArrayRef<llvm::Value *>(), CRK_Unrecoverable);
-    else
+    } else
       Builder.CreateUnreachable();
 
     // We do need to preserve an insertion point.
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index a43cf30da73..63731b7b7d0 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -458,6 +458,8 @@ void CodeGenFunction::EmitTypeCheck(TypeCheckKind TCK, SourceLocation Loc,
   if (Address->getType()->getPointerAddressSpace())
     return;
 
+  SanitizerScope SanScope(this);
+
   llvm::Value *Cond = nullptr;
   llvm::BasicBlock *Done = nullptr;
 
@@ -654,6 +656,7 @@ void CodeGenFunction::EmitBoundsCheck(const Expr *E, const Expr *Base,
                                       bool Accessed) {
   assert(SanOpts->ArrayBounds &&
          "should not be called unless adding bounds checks");
+  SanitizerScope SanScope(this);
 
   QualType IndexedType;
   llvm::Value *Bound = getArrayIndexingBound(*this, Base, IndexedType);
@@ -1129,6 +1132,7 @@ llvm::Value *CodeGenFunction::EmitLoadOfScalar(llvm::Value *Addr, bool Volatile,
 
   if ((SanOpts->Bool && hasBooleanRepresentation(Ty)) ||
       (SanOpts->Enum && Ty->getAs<EnumType>())) {
+    SanitizerScope SanScope(this);
     llvm::APInt Min, End;
     if (getRangeForType(*this, Ty, Min, End, true)) {
       --End;
@@ -2183,6 +2187,7 @@ void CodeGenFunction::EmitCheck(llvm::Value *Checked, StringRef CheckName,
                                 ArrayRef<llvm::Value *> DynamicArgs,
                                 CheckRecoverableKind RecoverKind) {
   assert(SanOpts != &SanitizerOptions::Disabled);
+  assert(IsSanitizerScope);
 
   if (CGM.getCodeGenOpts().SanitizeUndefinedTrapOnError) {
     assert (RecoverKind != CRK_AlwaysRecoverable &&
@@ -3231,6 +3236,7 @@ RValue CodeGenFunction::EmitCall(QualType CalleeType, llvm::Value *Callee,
       (!TargetDecl || !isa<FunctionDecl>(TargetDecl))) {
     if (llvm::Constant *PrefixSig =
             CGM.getTargetCodeGenInfo().getUBSanFunctionSignature(CGM)) {
+      SanitizerScope SanScope(this);
       llvm::Constant *FTRTTIConst =
           CGM.GetAddrOfRTTIDescriptor(QualType(FnType, 0), /*ForEH=*/true);
       llvm::Type *PrefixStructTyElems[] = {
diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 86f47872aea..9e0fbcfd184 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -554,6 +554,7 @@ void ScalarExprEmitter::EmitFloatConversionCheck(Value *OrigSrc,
                                                  Value *Src, QualType SrcType,
                                                  QualType DstType,
                                                  llvm::Type *DstTy) {
+  CodeGenFunction::SanitizerScope SanScope(&CGF);
   using llvm::APFloat;
   using llvm::APSInt;
 
@@ -840,6 +841,7 @@ Value *ScalarExprEmitter::EmitNullValue(QualType Ty) {
 /// might actually be a unary increment which has been lowered to a binary
 /// operation). The check passes if \p Check, which is an \c i1, is \c true.
 void ScalarExprEmitter::EmitBinOpCheck(Value *Check, const BinOpInfo &Info) {
+  assert(CGF.IsSanitizerScope);
   StringRef CheckName;
   SmallVector<llvm::Constant *, 4> StaticData;
   SmallVector<llvm::Value *, 2> DynamicData;
@@ -2153,15 +2155,18 @@ void ScalarExprEmitter::EmitUndefinedBehaviorIntegerDivAndRemCheck(
 }
 
 Value *ScalarExprEmitter::EmitDiv(const BinOpInfo &Ops) {
-  if ((CGF.SanOpts->IntegerDivideByZero ||
-       CGF.SanOpts->SignedIntegerOverflow) &&
-      Ops.Ty->isIntegerType()) {
-    llvm::Value *Zero = llvm::Constant::getNullValue(ConvertType(Ops.Ty));
-    EmitUndefinedBehaviorIntegerDivAndRemCheck(Ops, Zero, true);
-  } else if (CGF.SanOpts->FloatDivideByZero &&
-             Ops.Ty->isRealFloatingType()) {
-    llvm::Value *Zero = llvm::Constant::getNullValue(ConvertType(Ops.Ty));
-    EmitBinOpCheck(Builder.CreateFCmpUNE(Ops.RHS, Zero), Ops);
+  {
+    CodeGenFunction::SanitizerScope SanScope(&CGF);
+    if ((CGF.SanOpts->IntegerDivideByZero ||
+         CGF.SanOpts->SignedIntegerOverflow) &&
+        Ops.Ty->isIntegerType()) {
+      llvm::Value *Zero = llvm::Constant::getNullValue(ConvertType(Ops.Ty));
+      EmitUndefinedBehaviorIntegerDivAndRemCheck(Ops, Zero, true);
+    } else if (CGF.SanOpts->FloatDivideByZero &&
+               Ops.Ty->isRealFloatingType()) {
+      llvm::Value *Zero = llvm::Constant::getNullValue(ConvertType(Ops.Ty));
+      EmitBinOpCheck(Builder.CreateFCmpUNE(Ops.RHS, Zero), Ops);
+    }
   }
 
   if (Ops.LHS->getType()->isFPOrFPVectorTy()) {
@@ -2185,6 +2190,7 @@ Value *ScalarExprEmitter::EmitDiv(const BinOpInfo &Ops) {
 Value *ScalarExprEmitter::EmitRem(const BinOpInfo &Ops) {
   // Rem in C can't be a floating point type: C99 6.5.5p2.
   if (CGF.SanOpts->IntegerDivideByZero) {
+    CodeGenFunction::SanitizerScope SanScope(&CGF);
     llvm::Value *Zero = llvm::Constant::getNullValue(ConvertType(Ops.Ty));
 
     if (Ops.Ty->isIntegerType())
@@ -2242,9 +2248,10 @@ Value *ScalarExprEmitter::EmitOverflowCheckedBinOp(const BinOpInfo &Ops) {
   if (handlerName->empty()) {
     // If the signed-integer-overflow sanitizer is enabled, emit a call to its
     // runtime. Otherwise, this is a -ftrapv check, so just emit a trap.
-    if (!isSigned || CGF.SanOpts->SignedIntegerOverflow)
+    if (!isSigned || CGF.SanOpts->SignedIntegerOverflow) {
+      CodeGenFunction::SanitizerScope SanScope(&CGF);
       EmitBinOpCheck(Builder.CreateNot(overflow), Ops);
-    else
+    } else
       CGF.EmitTrapCheck(Builder.CreateNot(overflow));
     return result;
   }
@@ -2596,6 +2603,7 @@ Value *ScalarExprEmitter::EmitShl(const BinOpInfo &Ops) {
 
   if (CGF.SanOpts->Shift && !CGF.getLangOpts().OpenCL &&
       isa<llvm::IntegerType>(Ops.LHS->getType())) {
+    CodeGenFunction::SanitizerScope SanScope(&CGF);
     llvm::Value *WidthMinusOne = GetWidthMinusOneValue(Ops.LHS, RHS);
     llvm::Value *Valid = Builder.CreateICmpULE(RHS, WidthMinusOne);
 
@@ -2647,8 +2655,10 @@ Value *ScalarExprEmitter::EmitShr(const BinOpInfo &Ops) {
     RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, "sh_prom");
 
   if (CGF.SanOpts->Shift && !CGF.getLangOpts().OpenCL &&
-      isa<llvm::IntegerType>(Ops.LHS->getType()))
+      isa<llvm::IntegerType>(Ops.LHS->getType())) {
+    CodeGenFunction::SanitizerScope SanScope(&CGF);
     EmitBinOpCheck(Builder.CreateICmpULE(RHS, GetWidthMinusOneValue(Ops.LHS, RHS)), Ops);
+  }
 
   // OpenCL 6.3j: shift values are effectively % word size of LHS.
   if (CGF.getLangOpts().OpenCL)
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index 0987673bb2b..5ca3a78bb4f 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -36,8 +36,9 @@ using namespace CodeGen;
 CodeGenFunction::CodeGenFunction(CodeGenModule &cgm, bool suppressNewContext)
     : CodeGenTypeCache(cgm), CGM(cgm), Target(cgm.getTarget()),
       Builder(cgm.getModule().getContext(), llvm::ConstantFolder(),
-              CGBuilderInserterTy(this)), CapturedStmtInfo(nullptr),
-      SanOpts(&CGM.getLangOpts().Sanitize), AutoreleaseResult(false), BlockInfo(nullptr),
+              CGBuilderInserterTy(this)),
+      CapturedStmtInfo(nullptr), SanOpts(&CGM.getLangOpts().Sanitize),
+      IsSanitizerScope(false), AutoreleaseResult(false), BlockInfo(nullptr),
       BlockPointer(nullptr), LambdaThisCaptureField(nullptr),
       NormalCleanupDest(nullptr), NextCleanupDestIndex(1),
       FirstBlockInfo(nullptr), EHResumeBlock(nullptr), ExceptionSlot(nullptr),
@@ -843,11 +844,12 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
   //   function call is used by the caller, the behavior is undefined.
   if (getLangOpts().CPlusPlus && !FD->hasImplicitReturnZero() &&
       !FD->getReturnType()->isVoidType() && Builder.GetInsertBlock()) {
-    if (SanOpts->Return)
+    if (SanOpts->Return) {
+      SanitizerScope SanScope(this);
       EmitCheck(Builder.getFalse(), "missing_return",
                 EmitCheckSourceLocation(FD->getLocation()),
                 ArrayRef<llvm::Value *>(), CRK_Unrecoverable);
-    else if (CGM.getCodeGenOpts().OptimizationLevel == 0)
+    } else if (CGM.getCodeGenOpts().OptimizationLevel == 0)
       Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::trap));
     Builder.CreateUnreachable();
     Builder.ClearInsertionPoint();
@@ -1499,6 +1501,7 @@ void CodeGenFunction::EmitVariablyModifiedType(QualType type) {
           //   greater than zero.
           if (SanOpts->VLABound &&
               size->getType()->isSignedIntegerType()) {
+            SanitizerScope SanScope(this);
             llvm::Value *Zero = llvm::Constant::getNullValue(Size->getType());
             llvm::Constant *StaticArgs[] = {
               EmitCheckSourceLocation(size->getLocStart()),
@@ -1637,11 +1640,26 @@ llvm::Value *CodeGenFunction::EmitFieldAnnotations(const FieldDecl *D,
 
 CodeGenFunction::CGCapturedStmtInfo::~CGCapturedStmtInfo() { }
 
+CodeGenFunction::SanitizerScope::SanitizerScope(CodeGenFunction *CGF)
+    : CGF(CGF) {
+  assert(!CGF->IsSanitizerScope);
+  CGF->IsSanitizerScope = true;
+}
+
+CodeGenFunction::SanitizerScope::~SanitizerScope() {
+  CGF->IsSanitizerScope = false;
+}
+
 void CodeGenFunction::InsertHelper(llvm::Instruction *I,
                                    const llvm::Twine &Name,
                                    llvm::BasicBlock *BB,
                                    llvm::BasicBlock::iterator InsertPt) const {
   LoopStack.InsertHelper(I);
+  if (IsSanitizerScope) {
+    I->setMetadata(
+        CGM.getModule().getMDKindID("nosanitize"),
+        llvm::MDNode::get(CGM.getLLVMContext(), ArrayRef<llvm::Value *>()));
+  }
 }
 
 template <bool PreserveNames>
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index d6675f39c7d..f7a91686e39 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -247,6 +247,17 @@ public:
   /// \brief Sanitizer options to use for this function.
   const SanitizerOptions *SanOpts;
 
+  /// \brief True if CodeGen currently emits code implementing sanitizer checks.
+  bool IsSanitizerScope;
+
+  /// \brief RAII object to set/unset CodeGenFunction::IsSanitizerScope.
+  class SanitizerScope {
+    CodeGenFunction *CGF;
+  public:
+    SanitizerScope(CodeGenFunction *CGF);
+    ~SanitizerScope();
+  };
+
   /// In ARC, whether we should autorelease the return value.
   bool AutoreleaseResult;