X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=blobdiff_plain;f=lib%2FTransforms%2FInstrumentation%2FDataFlowSanitizer.cpp;h=35057cdd47e9783c70f482ad95e5c49cc9025b28;hp=af227d27d9208e33113675c3094c7734317842d0;hb=110748bbb4a290e10e3d8246edd717bcfe3ca380;hpb=a90d91fd1add17b3c6af09a845ede940595098e9

diff --git a/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
index af227d27d92..35057cdd47e 100644
--- a/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -48,20 +48,25 @@
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/DenseSet.h"
 #include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Analysis/ValueTracking.h"
-#include "llvm/IR/InlineAsm.h"
+#include "llvm/IR/Dominators.h"
 #include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/InlineAsm.h"
+#include "llvm/IR/InstVisitor.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/MDBuilder.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Value.h"
-#include "llvm/InstVisitor.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/SpecialCaseList.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Transforms/Utils/SpecialCaseList.h"
+#include <algorithm>
 #include <iterator>
+#include <set>
+#include <utility>
 
 using namespace llvm;
 
@@ -76,24 +81,94 @@ static cl::opt<bool> ClPreserveAlignment(
     cl::desc("respect alignment requirements provided by input IR"), cl::Hidden,
     cl::init(false));
 
-// The greylist file controls how shadow parameters are passed.
-// The program acts as though every function in the greylist is passed
-// parameters with zero shadow and that its return value also has zero shadow.
-// This avoids the use of TLS or extra function parameters to pass shadow state
-// and essentially makes the function conform to the "native" (i.e. unsanitized)
-// ABI.
-static cl::opt<std::string> ClGreylistFile(
-    "dfsan-greylist",
-    cl::desc("File containing the list of functions with a native ABI"),
+// The ABI list file controls how shadow parameters are passed.  The pass treats
+// every function labelled "uninstrumented" in the ABI list file as conforming
+// to the "native" (i.e. unsanitized) ABI.  Unless the ABI list contains
+// additional annotations for those functions, a call to one of those functions
+// will produce a warning message, as the labelling behaviour of the function is
+// unknown.  The other supported annotations are "functional" and "discard",
+// which are described below under DataFlowSanitizer::WrapperKind.
+static cl::opt<std::string> ClABIListFile(
+    "dfsan-abilist",
+    cl::desc("File listing native ABI functions and how the pass treats them"),
     cl::Hidden);
 
+// Controls whether the pass uses IA_Args or IA_TLS as the ABI for instrumented
+// functions (see DataFlowSanitizer::InstrumentedABI below).
 static cl::opt<bool> ClArgsABI(
     "dfsan-args-abi",
     cl::desc("Use the argument ABI rather than the TLS ABI"),
     cl::Hidden);
 
+// Controls whether the pass includes or ignores the labels of pointers in load
+// instructions.
+static cl::opt<bool> ClCombinePointerLabelsOnLoad(
+    "dfsan-combine-pointer-labels-on-load",
+    cl::desc("Combine the label of the pointer with the label of the data when "
+             "loading from memory."),
+    cl::Hidden, cl::init(true));
+
+// Controls whether the pass includes or ignores the labels of pointers in
+// stores instructions.
+static cl::opt<bool> ClCombinePointerLabelsOnStore(
+    "dfsan-combine-pointer-labels-on-store",
+    cl::desc("Combine the label of the pointer with the label of the data when "
+             "storing in memory."),
+    cl::Hidden, cl::init(false));
+
+static cl::opt<bool> ClDebugNonzeroLabels(
+    "dfsan-debug-nonzero-labels",
+    cl::desc("Insert calls to __dfsan_nonzero_label on observing a parameter, "
+             "load or return with a nonzero label"),
+    cl::Hidden);
+
 namespace {
 
+StringRef GetGlobalTypeString(const GlobalValue &G) {
+  // Types of GlobalVariables are always pointer types.
+  Type *GType = G.getType()->getElementType();
+  // For now we support blacklisting struct types only.
+  if (StructType *SGType = dyn_cast<StructType>(GType)) {
+    if (!SGType->isLiteral())
+      return SGType->getName();
+  }
+  return "<unknown type>";
+}
+
+class DFSanABIList {
+  std::unique_ptr<SpecialCaseList> SCL;
+
+ public:
+  DFSanABIList(SpecialCaseList *SCL) : SCL(SCL) {}
+
+  /// Returns whether either this function or its source file are listed in the
+  /// given category.
+  bool isIn(const Function &F, const StringRef Category) const {
+    return isIn(*F.getParent(), Category) ||
+           SCL->inSection("fun", F.getName(), Category);
+  }
+
+  /// Returns whether this global alias is listed in the given category.
+  ///
+  /// If GA aliases a function, the alias's name is matched as a function name
+  /// would be.  Similarly, aliases of globals are matched like globals.
+  bool isIn(const GlobalAlias &GA, const StringRef Category) const {
+    if (isIn(*GA.getParent(), Category))
+      return true;
+
+    if (isa<FunctionType>(GA.getType()->getElementType()))
+      return SCL->inSection("fun", GA.getName(), Category);
+
+    return SCL->inSection("global", GA.getName(), Category) ||
+           SCL->inSection("type", GetGlobalTypeString(GA), Category);
+  }
+
+  /// Returns whether this module is listed in the given category.
+  bool isIn(const Module &M, const StringRef Category) const {
+    return SCL->inSection("src", M.getModuleIdentifier(), Category);
+  }
+};
+
 class DataFlowSanitizer : public ModulePass {
   friend struct DFSanFunction;
   friend class DFSanVisitor;
@@ -102,14 +177,43 @@ class DataFlowSanitizer : public ModulePass {
     ShadowWidth = 16
   };
 
+  /// Which ABI should be used for instrumented functions?
   enum InstrumentedABI {
-    IA_None,
-    IA_MemOnly,
+    /// Argument and return value labels are passed through additional
+    /// arguments and by modifying the return type.
     IA_Args,
+
+    /// Argument and return value labels are passed through TLS variables
+    /// __dfsan_arg_tls and __dfsan_retval_tls.
     IA_TLS
   };
 
-  DataLayout *DL;
+  /// How should calls to uninstrumented functions be handled?
+  enum WrapperKind {
+    /// This function is present in an uninstrumented form but we don't know
+    /// how it should be handled.  Print a warning and call the function anyway.
+    /// Don't label the return value.
+    WK_Warning,
+
+    /// This function does not write to (user-accessible) memory, and its return
+    /// value is unlabelled.
+    WK_Discard,
+
+    /// This function does not write to (user-accessible) memory, and the label
+    /// of its return value is the union of the label of its arguments.
+    WK_Functional,
+
+    /// Instead of calling the function, a custom wrapper __dfsw_F is called,
+    /// where F is the name of the function.  This function may wrap the
+    /// original function or provide its own implementation.  This is similar to
+    /// the IA_Args ABI, except that IA_Args uses a struct return type to
+    /// pass the return value shadow in a register, while WK_Custom uses an
+    /// extra pointer argument to return the shadow.  This allows the wrapped
+    /// form of the function type to be expressed in C.
+    WK_Custom
+  };
+
+  const DataLayout *DL;
   Module *Mod;
   LLVMContext *Ctx;
   IntegerType *ShadowTy;
@@ -126,44 +230,77 @@ class DataFlowSanitizer : public ModulePass {
   Constant *GetRetvalTLS;
   FunctionType *DFSanUnionFnTy;
   FunctionType *DFSanUnionLoadFnTy;
+  FunctionType *DFSanUnimplementedFnTy;
+  FunctionType *DFSanSetLabelFnTy;
+  FunctionType *DFSanNonzeroLabelFnTy;
   Constant *DFSanUnionFn;
   Constant *DFSanUnionLoadFn;
+  Constant *DFSanUnimplementedFn;
+  Constant *DFSanSetLabelFn;
+  Constant *DFSanNonzeroLabelFn;
   MDNode *ColdCallWeights;
-  OwningPtr<SpecialCaseList> Greylist;
+  DFSanABIList ABIList;
   DenseMap<Value *, Function *> UnwrappedFnMap;
+  AttributeSet ReadOnlyNoneAttrs;
 
   Value *getShadowAddress(Value *Addr, Instruction *Pos);
-  Value *combineShadows(Value *V1, Value *V2, Instruction *Pos);
-  FunctionType *getInstrumentedFunctionType(FunctionType *T);
-  InstrumentedABI getInstrumentedABI(Function *F);
-  InstrumentedABI getDefaultInstrumentedABI();
-
-public:
-  DataFlowSanitizer(void *(*getArgTLS)() = 0, void *(*getRetValTLS)() = 0);
+  bool isInstrumented(const Function *F);
+  bool isInstrumented(const GlobalAlias *GA);
+  FunctionType *getArgsFunctionType(FunctionType *T);
+  FunctionType *getTrampolineFunctionType(FunctionType *T);
+  FunctionType *getCustomFunctionType(FunctionType *T);
+  InstrumentedABI getInstrumentedABI();
+  WrapperKind getWrapperKind(Function *F);
+  void addGlobalNamePrefix(GlobalValue *GV);
+  Function *buildWrapperFunction(Function *F, StringRef NewFName,
+                                 GlobalValue::LinkageTypes NewFLink,
+                                 FunctionType *NewFT);
+  Constant *getOrBuildTrampolineFunction(FunctionType *FT, StringRef FName);
+
+ public:
+  DataFlowSanitizer(StringRef ABIListFile = StringRef(),
+                    void *(*getArgTLS)() = nullptr,
+                    void *(*getRetValTLS)() = nullptr);
   static char ID;
-  bool doInitialization(Module &M);
-  bool runOnModule(Module &M);
+  bool doInitialization(Module &M) override;
+  bool runOnModule(Module &M) override;
 };
 
 struct DFSanFunction {
   DataFlowSanitizer &DFS;
   Function *F;
+  DominatorTree DT;
   DataFlowSanitizer::InstrumentedABI IA;
+  bool IsNativeABI;
   Value *ArgTLSPtr;
   Value *RetvalTLSPtr;
+  AllocaInst *LabelReturnAlloca;
   DenseMap<Value *, Value *> ValShadowMap;
   DenseMap<AllocaInst *, AllocaInst *> AllocaShadowMap;
   std::vector<std::pair<PHINode *, PHINode *> > PHIFixups;
   DenseSet<Instruction *> SkipInsts;
+  DenseSet<Value *> NonZeroChecks;
 
-  DFSanFunction(DataFlowSanitizer &DFS, Function *F)
-      : DFS(DFS), F(F), IA(DFS.getInstrumentedABI(F)), ArgTLSPtr(0),
-        RetvalTLSPtr(0) {}
+  struct CachedCombinedShadow {
+    BasicBlock *Block;
+    Value *Shadow;
+  };
+  DenseMap<std::pair<Value *, Value *>, CachedCombinedShadow>
+      CachedCombinedShadows;
+  DenseMap<Value *, std::set<Value *>> ShadowElements;
+
+  DFSanFunction(DataFlowSanitizer &DFS, Function *F, bool IsNativeABI)
+      : DFS(DFS), F(F), IA(DFS.getInstrumentedABI()),
+        IsNativeABI(IsNativeABI), ArgTLSPtr(nullptr), RetvalTLSPtr(nullptr),
+        LabelReturnAlloca(nullptr) {
+    DT.recalculate(*F);
+  }
   Value *getArgTLSPtr();
   Value *getArgTLS(unsigned Index, Instruction *Pos);
   Value *getRetvalTLS();
   Value *getShadow(Value *V);
   void setShadow(Instruction *I, Value *Shadow);
+  Value *combineShadows(Value *V1, Value *V2, Instruction *Pos);
   Value *combineOperandShadows(Instruction *Inst);
   Value *loadShadow(Value *ShadowAddr, uint64_t Size, uint64_t Align,
                     Instruction *Pos);
@@ -172,7 +309,7 @@ struct DFSanFunction {
 };
 
 class DFSanVisitor : public InstVisitor<DFSanVisitor> {
-public:
+ public:
   DFSanFunction &DFSF;
   DFSanVisitor(DFSanFunction &DFSF) : DFSF(DFSF) {}
 
@@ -194,6 +331,7 @@ public:
   void visitInsertValueInst(InsertValueInst &I);
   void visitAllocaInst(AllocaInst &I);
   void visitSelectInst(SelectInst &I);
+  void visitMemSetInst(MemSetInst &I);
   void visitMemTransferInst(MemTransferInst &I);
 };
 
@@ -203,17 +341,21 @@ char DataFlowSanitizer::ID;
 INITIALIZE_PASS(DataFlowSanitizer, "dfsan",
                 "DataFlowSanitizer: dynamic data flow analysis.", false, false)
 
-ModulePass *llvm::createDataFlowSanitizerPass(void *(*getArgTLS)(),
+ModulePass *llvm::createDataFlowSanitizerPass(StringRef ABIListFile,
+                                              void *(*getArgTLS)(),
                                               void *(*getRetValTLS)()) {
-  return new DataFlowSanitizer(getArgTLS, getRetValTLS);
+  return new DataFlowSanitizer(ABIListFile, getArgTLS, getRetValTLS);
 }
 
-DataFlowSanitizer::DataFlowSanitizer(void *(*getArgTLS)(),
+DataFlowSanitizer::DataFlowSanitizer(StringRef ABIListFile,
+                                     void *(*getArgTLS)(),
                                      void *(*getRetValTLS)())
     : ModulePass(ID), GetArgTLSPtr(getArgTLS), GetRetvalTLSPtr(getRetValTLS),
-      Greylist(SpecialCaseList::createOrDie(ClGreylistFile)) {}
+      ABIList(SpecialCaseList::createOrDie(ABIListFile.empty() ? ClABIListFile
+                                                               : ABIListFile)) {
+}
 
-FunctionType *DataFlowSanitizer::getInstrumentedFunctionType(FunctionType *T) {
+FunctionType *DataFlowSanitizer::getArgsFunctionType(FunctionType *T) {
   llvm::SmallVector<Type *, 4> ArgTypes;
   std::copy(T->param_begin(), T->param_end(), std::back_inserter(ArgTypes));
   for (unsigned i = 0, e = T->getNumParams(); i != e; ++i)
@@ -222,14 +364,50 @@ FunctionType *DataFlowSanitizer::getInstrumentedFunctionType(FunctionType *T) {
     ArgTypes.push_back(ShadowPtrTy);
   Type *RetType = T->getReturnType();
   if (!RetType->isVoidTy())
-    RetType = StructType::get(RetType, ShadowTy, (Type *)0);
+    RetType = StructType::get(RetType, ShadowTy, (Type *)nullptr);
   return FunctionType::get(RetType, ArgTypes, T->isVarArg());
 }
 
+FunctionType *DataFlowSanitizer::getTrampolineFunctionType(FunctionType *T) {
+  assert(!T->isVarArg());
+  llvm::SmallVector<Type *, 4> ArgTypes;
+  ArgTypes.push_back(T->getPointerTo());
+  std::copy(T->param_begin(), T->param_end(), std::back_inserter(ArgTypes));
+  for (unsigned i = 0, e = T->getNumParams(); i != e; ++i)
+    ArgTypes.push_back(ShadowTy);
+  Type *RetType = T->getReturnType();
+  if (!RetType->isVoidTy())
+    ArgTypes.push_back(ShadowPtrTy);
+  return FunctionType::get(T->getReturnType(), ArgTypes, false);
+}
+
+FunctionType *DataFlowSanitizer::getCustomFunctionType(FunctionType *T) {
+  assert(!T->isVarArg());
+  llvm::SmallVector<Type *, 4> ArgTypes;
+  for (FunctionType::param_iterator i = T->param_begin(), e = T->param_end();
+       i != e; ++i) {
+    FunctionType *FT;
+    if (isa<PointerType>(*i) && (FT = dyn_cast<FunctionType>(cast<PointerType>(
+                                     *i)->getElementType()))) {
+      ArgTypes.push_back(getTrampolineFunctionType(FT)->getPointerTo());
+      ArgTypes.push_back(Type::getInt8PtrTy(*Ctx));
+    } else {
+      ArgTypes.push_back(*i);
+    }
+  }
+  for (unsigned i = 0, e = T->getNumParams(); i != e; ++i)
+    ArgTypes.push_back(ShadowTy);
+  Type *RetType = T->getReturnType();
+  if (!RetType->isVoidTy())
+    ArgTypes.push_back(ShadowPtrTy);
+  return FunctionType::get(T->getReturnType(), ArgTypes, false);
+}
+
 bool DataFlowSanitizer::doInitialization(Module &M) {
-  DL = getAnalysisIfAvailable<DataLayout>();
-  if (!DL)
-    return false;
+  DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
+  if (!DLP)
+    report_fatal_error("data layout missing");
+  DL = &DLP->getDataLayout();
 
   Mod = &M;
   Ctx = &M.getContext();
@@ -246,44 +424,145 @@ bool DataFlowSanitizer::doInitialization(Module &M) {
   Type *DFSanUnionLoadArgs[2] = { ShadowPtrTy, IntptrTy };
   DFSanUnionLoadFnTy =
       FunctionType::get(ShadowTy, DFSanUnionLoadArgs, /*isVarArg=*/ false);
+  DFSanUnimplementedFnTy = FunctionType::get(
+      Type::getVoidTy(*Ctx), Type::getInt8PtrTy(*Ctx), /*isVarArg=*/false);
+  Type *DFSanSetLabelArgs[3] = { ShadowTy, Type::getInt8PtrTy(*Ctx), IntptrTy };
+  DFSanSetLabelFnTy = FunctionType::get(Type::getVoidTy(*Ctx),
+                                        DFSanSetLabelArgs, /*isVarArg=*/false);
+  DFSanNonzeroLabelFnTy = FunctionType::get(
+      Type::getVoidTy(*Ctx), ArrayRef<Type *>(), /*isVarArg=*/false);
 
   if (GetArgTLSPtr) {
     Type *ArgTLSTy = ArrayType::get(ShadowTy, 64);
-    ArgTLS = 0;
+    ArgTLS = nullptr;
     GetArgTLS = ConstantExpr::getIntToPtr(
         ConstantInt::get(IntptrTy, uintptr_t(GetArgTLSPtr)),
         PointerType::getUnqual(
-            FunctionType::get(PointerType::getUnqual(ArgTLSTy), (Type *)0)));
+            FunctionType::get(PointerType::getUnqual(ArgTLSTy),
+                              (Type *)nullptr)));
   }
   if (GetRetvalTLSPtr) {
-    RetvalTLS = 0;
+    RetvalTLS = nullptr;
     GetRetvalTLS = ConstantExpr::getIntToPtr(
         ConstantInt::get(IntptrTy, uintptr_t(GetRetvalTLSPtr)),
         PointerType::getUnqual(
-            FunctionType::get(PointerType::getUnqual(ShadowTy), (Type *)0)));
+            FunctionType::get(PointerType::getUnqual(ShadowTy),
+                              (Type *)nullptr)));
   }
 
   ColdCallWeights = MDBuilder(*Ctx).createBranchWeights(1, 1000);
   return true;
 }
 
-DataFlowSanitizer::InstrumentedABI
-DataFlowSanitizer::getInstrumentedABI(Function *F) {
-  if (Greylist->isIn(*F))
-    return IA_MemOnly;
-  else
-    return getDefaultInstrumentedABI();
+bool DataFlowSanitizer::isInstrumented(const Function *F) {
+  return !ABIList.isIn(*F, "uninstrumented");
 }
 
-DataFlowSanitizer::InstrumentedABI
-DataFlowSanitizer::getDefaultInstrumentedABI() {
+bool DataFlowSanitizer::isInstrumented(const GlobalAlias *GA) {
+  return !ABIList.isIn(*GA, "uninstrumented");
+}
+
+DataFlowSanitizer::InstrumentedABI DataFlowSanitizer::getInstrumentedABI() {
   return ClArgsABI ? IA_Args : IA_TLS;
 }
 
+DataFlowSanitizer::WrapperKind DataFlowSanitizer::getWrapperKind(Function *F) {
+  if (ABIList.isIn(*F, "functional"))
+    return WK_Functional;
+  if (ABIList.isIn(*F, "discard"))
+    return WK_Discard;
+  if (ABIList.isIn(*F, "custom"))
+    return WK_Custom;
+
+  return WK_Warning;
+}
+
+void DataFlowSanitizer::addGlobalNamePrefix(GlobalValue *GV) {
+  std::string GVName = GV->getName(), Prefix = "dfs$";
+  GV->setName(Prefix + GVName);
+
+  // Try to change the name of the function in module inline asm.  We only do
+  // this for specific asm directives, currently only ".symver", to try to avoid
+  // corrupting asm which happens to contain the symbol name as a substring.
+  // Note that the substitution for .symver assumes that the versioned symbol
+  // also has an instrumented name.
+  std::string Asm = GV->getParent()->getModuleInlineAsm();
+  std::string SearchStr = ".symver " + GVName + ",";
+  size_t Pos = Asm.find(SearchStr);
+  if (Pos != std::string::npos) {
+    Asm.replace(Pos, SearchStr.size(),
+                ".symver " + Prefix + GVName + "," + Prefix);
+    GV->getParent()->setModuleInlineAsm(Asm);
+  }
+}
+
+Function *
+DataFlowSanitizer::buildWrapperFunction(Function *F, StringRef NewFName,
+                                        GlobalValue::LinkageTypes NewFLink,
+                                        FunctionType *NewFT) {
+  FunctionType *FT = F->getFunctionType();
+  Function *NewF = Function::Create(NewFT, NewFLink, NewFName,
+                                    F->getParent());
+  NewF->copyAttributesFrom(F);
+  NewF->removeAttributes(
+      AttributeSet::ReturnIndex,
+      AttributeFuncs::typeIncompatible(NewFT->getReturnType(),
+                                       AttributeSet::ReturnIndex));
+
+  BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", NewF);
+  std::vector<Value *> Args;
+  unsigned n = FT->getNumParams();
+  for (Function::arg_iterator ai = NewF->arg_begin(); n != 0; ++ai, --n)
+    Args.push_back(&*ai);
+  CallInst *CI = CallInst::Create(F, Args, "", BB);
+  if (FT->getReturnType()->isVoidTy())
+    ReturnInst::Create(*Ctx, BB);
+  else
+    ReturnInst::Create(*Ctx, CI, BB);
+
+  return NewF;
+}
+
+Constant *DataFlowSanitizer::getOrBuildTrampolineFunction(FunctionType *FT,
+                                                          StringRef FName) {
+  FunctionType *FTT = getTrampolineFunctionType(FT);
+  Constant *C = Mod->getOrInsertFunction(FName, FTT);
+  Function *F = dyn_cast<Function>(C);
+  if (F && F->isDeclaration()) {
+    F->setLinkage(GlobalValue::LinkOnceODRLinkage);
+    BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", F);
+    std::vector<Value *> Args;
+    Function::arg_iterator AI = F->arg_begin(); ++AI;
+    for (unsigned N = FT->getNumParams(); N != 0; ++AI, --N)
+      Args.push_back(&*AI);
+    CallInst *CI =
+        CallInst::Create(&F->getArgumentList().front(), Args, "", BB);
+    ReturnInst *RI;
+    if (FT->getReturnType()->isVoidTy())
+      RI = ReturnInst::Create(*Ctx, BB);
+    else
+      RI = ReturnInst::Create(*Ctx, CI, BB);
+
+    DFSanFunction DFSF(*this, F, /*IsNativeABI=*/true);
+    Function::arg_iterator ValAI = F->arg_begin(), ShadowAI = AI; ++ValAI;
+    for (unsigned N = FT->getNumParams(); N != 0; ++ValAI, ++ShadowAI, --N)
+      DFSF.ValShadowMap[ValAI] = ShadowAI;
+    DFSanVisitor(DFSF).visitCallInst(*CI);
+    if (!FT->getReturnType()->isVoidTy())
+      new StoreInst(DFSF.getShadow(RI->getReturnValue()),
+                    &F->getArgumentList().back(), RI);
+  }
+
+  return C;
+}
+
 bool DataFlowSanitizer::runOnModule(Module &M) {
   if (!DL)
     return false;
 
+  if (ABIList.isIn(M, "skip"))
+    return false;
+
   if (!GetArgTLSPtr) {
     Type *ArgTLSTy = ArrayType::get(ShadowTy, 64);
     ArgTLS = Mod->getOrInsertGlobal("__dfsan_arg_tls", ArgTLSTy);
@@ -306,35 +585,82 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
   DFSanUnionLoadFn =
       Mod->getOrInsertFunction("__dfsan_union_load", DFSanUnionLoadFnTy);
   if (Function *F = dyn_cast<Function>(DFSanUnionLoadFn)) {
+    F->addAttribute(AttributeSet::FunctionIndex, Attribute::ReadOnly);
     F->addAttribute(AttributeSet::ReturnIndex, Attribute::ZExt);
   }
+  DFSanUnimplementedFn =
+      Mod->getOrInsertFunction("__dfsan_unimplemented", DFSanUnimplementedFnTy);
+  DFSanSetLabelFn =
+      Mod->getOrInsertFunction("__dfsan_set_label", DFSanSetLabelFnTy);
+  if (Function *F = dyn_cast<Function>(DFSanSetLabelFn)) {
+    F->addAttribute(1, Attribute::ZExt);
+  }
+  DFSanNonzeroLabelFn =
+      Mod->getOrInsertFunction("__dfsan_nonzero_label", DFSanNonzeroLabelFnTy);
 
   std::vector<Function *> FnsToInstrument;
+  llvm::SmallPtrSet<Function *, 2> FnsWithNativeABI;
   for (Module::iterator i = M.begin(), e = M.end(); i != e; ++i) {
-    if (!i->isIntrinsic() && i != DFSanUnionFn && i != DFSanUnionLoadFn)
+    if (!i->isIntrinsic() &&
+        i != DFSanUnionFn &&
+        i != DFSanUnionLoadFn &&
+        i != DFSanUnimplementedFn &&
+        i != DFSanSetLabelFn &&
+        i != DFSanNonzeroLabelFn)
       FnsToInstrument.push_back(&*i);
   }
 
-  // First, change the ABI of every function in the module.  Greylisted
+  // Give function aliases prefixes when necessary, and build wrappers where the
+  // instrumentedness is inconsistent.
+  for (Module::alias_iterator i = M.alias_begin(), e = M.alias_end(); i != e;) {
+    GlobalAlias *GA = &*i;
+    ++i;
+    // Don't stop on weak.  We assume people aren't playing games with the
+    // instrumentedness of overridden weak aliases.
+    if (auto F = dyn_cast<Function>(GA->getBaseObject())) {
+      bool GAInst = isInstrumented(GA), FInst = isInstrumented(F);
+      if (GAInst && FInst) {
+        addGlobalNamePrefix(GA);
+      } else if (GAInst != FInst) {
+        // Non-instrumented alias of an instrumented function, or vice versa.
+        // Replace the alias with a native-ABI wrapper of the aliasee.  The pass
+        // below will take care of instrumenting it.
+        Function *NewF =
+            buildWrapperFunction(F, "", GA->getLinkage(), F->getFunctionType());
+        GA->replaceAllUsesWith(ConstantExpr::getBitCast(NewF, GA->getType()));
+        NewF->takeName(GA);
+        GA->eraseFromParent();
+        FnsToInstrument.push_back(NewF);
+      }
+    }
+  }
+
+  AttrBuilder B;
+  B.addAttribute(Attribute::ReadOnly).addAttribute(Attribute::ReadNone);
+  ReadOnlyNoneAttrs = AttributeSet::get(*Ctx, AttributeSet::FunctionIndex, B);
+
+  // First, change the ABI of every function in the module.  ABI-listed
   // functions keep their original ABI and get a wrapper function.
   for (std::vector<Function *>::iterator i = FnsToInstrument.begin(),
                                          e = FnsToInstrument.end();
        i != e; ++i) {
     Function &F = **i;
-
     FunctionType *FT = F.getFunctionType();
-    FunctionType *NewFT = getInstrumentedFunctionType(FT);
-    // If the function types are the same (i.e. void()), we don't need to do
-    // anything here.
-    if (FT != NewFT) {
-      switch (getInstrumentedABI(&F)) {
-      case IA_Args: {
+
+    bool IsZeroArgsVoidRet = (FT->getNumParams() == 0 && !FT->isVarArg() &&
+                              FT->getReturnType()->isVoidTy());
+
+    if (isInstrumented(&F)) {
+      // Instrumented functions get a 'dfs$' prefix.  This allows us to more
+      // easily identify cases of mismatching ABIs.
+      if (getInstrumentedABI() == IA_Args && !IsZeroArgsVoidRet) {
+        FunctionType *NewFT = getArgsFunctionType(FT);
         Function *NewF = Function::Create(NewFT, F.getLinkage(), "", &M);
-        NewF->setCallingConv(F.getCallingConv());
-        NewF->setAttributes(F.getAttributes().removeAttributes(
-            *Ctx, AttributeSet::ReturnIndex,
+        NewF->copyAttributesFrom(&F);
+        NewF->removeAttributes(
+            AttributeSet::ReturnIndex,
             AttributeFuncs::typeIncompatible(NewFT->getReturnType(),
-                                             AttributeSet::ReturnIndex)));
+                                             AttributeSet::ReturnIndex));
         for (Function::arg_iterator FArg = F.arg_begin(),
                                     NewFArg = NewF->arg_begin(),
                                     FArgEnd = F.arg_end();
@@ -343,10 +669,10 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
         }
         NewF->getBasicBlockList().splice(NewF->begin(), F.getBasicBlockList());
 
-        for (Function::use_iterator ui = F.use_begin(), ue = F.use_end();
-             ui != ue;) {
-          BlockAddress *BA = dyn_cast<BlockAddress>(ui.getUse().getUser());
-          ++ui;
+        for (Function::user_iterator UI = F.user_begin(), UE = F.user_end();
+             UI != UE;) {
+          BlockAddress *BA = dyn_cast<BlockAddress>(*UI);
+          ++UI;
           if (BA) {
             BA->replaceAllUsesWith(
                 BlockAddress::get(NewF, BA->getBasicBlock()));
@@ -358,41 +684,49 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
         NewF->takeName(&F);
         F.eraseFromParent();
         *i = NewF;
-        break;
-      }
-      case IA_MemOnly: {
-        assert(!FT->isVarArg() && "varargs not handled here yet");
-        assert(getDefaultInstrumentedABI() == IA_Args);
-        Function *NewF =
-            Function::Create(NewFT, GlobalValue::LinkOnceODRLinkage,
-                             std::string("dfsw$") + F.getName(), &M);
-        NewF->setCallingConv(F.getCallingConv());
-        NewF->setAttributes(F.getAttributes());
-
-        BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", NewF);
-        std::vector<Value *> Args;
-        unsigned n = FT->getNumParams();
-        for (Function::arg_iterator i = NewF->arg_begin(); n != 0; ++i, --n)
-          Args.push_back(&*i);
-        CallInst *CI = CallInst::Create(&F, Args, "", BB);
-        if (FT->getReturnType()->isVoidTy())
-          ReturnInst::Create(*Ctx, BB);
-        else {
-          Value *InsVal = InsertValueInst::Create(
-              UndefValue::get(NewFT->getReturnType()), CI, 0, "", BB);
-          Value *InsShadow =
-              InsertValueInst::Create(InsVal, ZeroShadow, 1, "", BB);
-          ReturnInst::Create(*Ctx, InsShadow, BB);
-        }
-
-        Value *WrappedFnCst =
-            ConstantExpr::getBitCast(NewF, PointerType::getUnqual(FT));
-        F.replaceAllUsesWith(WrappedFnCst);
-        UnwrappedFnMap[WrappedFnCst] = &F;
-        break;
+        addGlobalNamePrefix(NewF);
+      } else {
+        addGlobalNamePrefix(&F);
       }
-      default:
-        break;
+               // Hopefully, nobody will try to indirectly call a vararg
+               // function... yet.
+    } else if (FT->isVarArg()) {
+      UnwrappedFnMap[&F] = &F;
+      *i = nullptr;
+    } else if (!IsZeroArgsVoidRet || getWrapperKind(&F) == WK_Custom) {
+      // Build a wrapper function for F.  The wrapper simply calls F, and is
+      // added to FnsToInstrument so that any instrumentation according to its
+      // WrapperKind is done in the second pass below.
+      FunctionType *NewFT = getInstrumentedABI() == IA_Args
+                                ? getArgsFunctionType(FT)
+                                : FT;
+      Function *NewF = buildWrapperFunction(
+          &F, std::string("dfsw$") + std::string(F.getName()),
+          GlobalValue::LinkOnceODRLinkage, NewFT);
+      if (getInstrumentedABI() == IA_TLS)
+        NewF->removeAttributes(AttributeSet::FunctionIndex, ReadOnlyNoneAttrs);
+
+      Value *WrappedFnCst =
+          ConstantExpr::getBitCast(NewF, PointerType::getUnqual(FT));
+      F.replaceAllUsesWith(WrappedFnCst);
+      UnwrappedFnMap[WrappedFnCst] = &F;
+      *i = NewF;
+
+      if (!F.isDeclaration()) {
+        // This function is probably defining an interposition of an
+        // uninstrumented function and hence needs to keep the original ABI.
+        // But any functions it may call need to use the instrumented ABI, so
+        // we instrument it in a mode which preserves the original ABI.
+        FnsWithNativeABI.insert(&F);
+
+        // This code needs to rebuild the iterators, as they may be invalidated
+        // by the push_back, taking care that the new range does not include
+        // any functions added by this code.
+        size_t N = i - FnsToInstrument.begin(),
+               Count = e - FnsToInstrument.begin();
+        FnsToInstrument.push_back(&F);
+        i = FnsToInstrument.begin() + N;
+        e = FnsToInstrument.begin() + Count;
       }
     }
   }
@@ -400,18 +734,17 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
   for (std::vector<Function *>::iterator i = FnsToInstrument.begin(),
                                          e = FnsToInstrument.end();
        i != e; ++i) {
-    if ((*i)->isDeclaration())
+    if (!*i || (*i)->isDeclaration())
       continue;
 
     removeUnreachableBlocks(**i);
 
-    DFSanFunction DFSF(*this, *i);
+    DFSanFunction DFSF(*this, *i, FnsWithNativeABI.count(*i));
 
     // DFSanVisitor may create new basic blocks, which confuses df_iterator.
     // Build a copy of the list before iterating over it.
-    llvm::SmallVector<BasicBlock *, 4> BBList;
-    std::copy(df_begin(&(*i)->getEntryBlock()), df_end(&(*i)->getEntryBlock()),
-              std::back_inserter(BBList));
+    llvm::SmallVector<BasicBlock *, 4> BBList(
+        depth_first(&(*i)->getEntryBlock()));
 
     for (llvm::SmallVector<BasicBlock *, 4>::iterator i = BBList.begin(),
                                                       e = BBList.end();
@@ -433,6 +766,10 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
       }
     }
 
+    // We will not necessarily be able to compute the shadow for every phi node
+    // until we have visited every block.  Therefore, the code that handles phi
+    // nodes adds them to the PHIFixups list so that they can be properly
+    // handled here.
     for (std::vector<std::pair<PHINode *, PHINode *> >::iterator
              i = DFSF.PHIFixups.begin(),
              e = DFSF.PHIFixups.end();
@@ -443,6 +780,30 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
             val, DFSF.getShadow(i->first->getIncomingValue(val)));
       }
     }
+
+    // -dfsan-debug-nonzero-labels will split the CFG in all kinds of crazy
+    // places (i.e. instructions in basic blocks we haven't even begun visiting
+    // yet).  To make our life easier, do this work in a pass after the main
+    // instrumentation.
+    if (ClDebugNonzeroLabels) {
+      for (DenseSet<Value *>::iterator i = DFSF.NonZeroChecks.begin(),
+                                       e = DFSF.NonZeroChecks.end();
+           i != e; ++i) {
+        Instruction *Pos;
+        if (Instruction *I = dyn_cast<Instruction>(*i))
+          Pos = I->getNextNode();
+        else
+          Pos = DFSF.F->getEntryBlock().begin();
+        while (isa<PHINode>(Pos) || isa<AllocaInst>(Pos))
+          Pos = Pos->getNextNode();
+        IRBuilder<> IRB(Pos);
+        Value *Ne = IRB.CreateICmpNE(*i, DFSF.DFS.ZeroShadow);
+        BranchInst *BI = cast<BranchInst>(SplitBlockAndInsertIfThen(
+            Ne, Pos, /*Unreachable=*/false, ColdCallWeights));
+        IRBuilder<> ThenIRB(BI);
+        ThenIRB.CreateCall(DFSF.DFS.DFSanNonzeroLabelFn);
+      }
+    }
   }
 
   return false;
@@ -479,6 +840,8 @@ Value *DFSanFunction::getShadow(Value *V) {
   Value *&Shadow = ValShadowMap[V];
   if (!Shadow) {
     if (Argument *A = dyn_cast<Argument>(V)) {
+      if (IsNativeABI)
+        return DFS.ZeroShadow;
       switch (IA) {
       case DataFlowSanitizer::IA_TLS: {
         Value *ArgTLSPtr = getArgTLSPtr();
@@ -495,12 +858,11 @@ Value *DFSanFunction::getShadow(Value *V) {
         while (ArgIdx--)
           ++i;
         Shadow = i;
+        assert(Shadow->getType() == DFS.ShadowTy);
         break;
       }
-      default:
-        Shadow = DFS.ZeroShadow;
-        break;
       }
+      NonZeroChecks.insert(Shadow);
     } else {
       Shadow = DFS.ZeroShadow;
     }
@@ -526,37 +888,72 @@ Value *DataFlowSanitizer::getShadowAddress(Value *Addr, Instruction *Pos) {
 
 // Generates IR to compute the union of the two given shadows, inserting it
 // before Pos.  Returns the computed union Value.
-Value *DataFlowSanitizer::combineShadows(Value *V1, Value *V2,
-                                         Instruction *Pos) {
-  if (V1 == ZeroShadow)
+Value *DFSanFunction::combineShadows(Value *V1, Value *V2, Instruction *Pos) {
+  if (V1 == DFS.ZeroShadow)
     return V2;
-  if (V2 == ZeroShadow)
+  if (V2 == DFS.ZeroShadow)
     return V1;
   if (V1 == V2)
     return V1;
+
+  auto V1Elems = ShadowElements.find(V1);
+  auto V2Elems = ShadowElements.find(V2);
+  if (V1Elems != ShadowElements.end() && V2Elems != ShadowElements.end()) {
+    if (std::includes(V1Elems->second.begin(), V1Elems->second.end(),
+                      V2Elems->second.begin(), V2Elems->second.end())) {
+      return V1;
+    } else if (std::includes(V2Elems->second.begin(), V2Elems->second.end(),
+                             V1Elems->second.begin(), V1Elems->second.end())) {
+      return V2;
+    }
+  } else if (V1Elems != ShadowElements.end()) {
+    if (V1Elems->second.count(V2))
+      return V1;
+  } else if (V2Elems != ShadowElements.end()) {
+    if (V2Elems->second.count(V1))
+      return V2;
+  }
+
+  auto Key = std::make_pair(V1, V2);
+  if (V1 > V2)
+    std::swap(Key.first, Key.second);
+  CachedCombinedShadow &CCS = CachedCombinedShadows[Key];
+  if (CCS.Block && DT.dominates(CCS.Block, Pos->getParent()))
+    return CCS.Shadow;
+
   IRBuilder<> IRB(Pos);
   BasicBlock *Head = Pos->getParent();
   Value *Ne = IRB.CreateICmpNE(V1, V2);
-  Instruction *NeInst = dyn_cast<Instruction>(Ne);
-  if (NeInst) {
-    BranchInst *BI = cast<BranchInst>(SplitBlockAndInsertIfThen(
-        NeInst, /*Unreachable=*/ false, ColdCallWeights));
-    IRBuilder<> ThenIRB(BI);
-    CallInst *Call = ThenIRB.CreateCall2(DFSanUnionFn, V1, V2);
-    Call->addAttribute(AttributeSet::ReturnIndex, Attribute::ZExt);
-    Call->addAttribute(1, Attribute::ZExt);
-    Call->addAttribute(2, Attribute::ZExt);
-
-    BasicBlock *Tail = BI->getSuccessor(0);
-    PHINode *Phi = PHINode::Create(ShadowTy, 2, "", Tail->begin());
-    Phi->addIncoming(Call, Call->getParent());
-    Phi->addIncoming(ZeroShadow, Head);
-    Pos = Phi;
-    return Phi;
+  BranchInst *BI = cast<BranchInst>(SplitBlockAndInsertIfThen(
+      Ne, Pos, /*Unreachable=*/false, DFS.ColdCallWeights, &DT));
+  IRBuilder<> ThenIRB(BI);
+  CallInst *Call = ThenIRB.CreateCall2(DFS.DFSanUnionFn, V1, V2);
+  Call->addAttribute(AttributeSet::ReturnIndex, Attribute::ZExt);
+  Call->addAttribute(1, Attribute::ZExt);
+  Call->addAttribute(2, Attribute::ZExt);
+
+  BasicBlock *Tail = BI->getSuccessor(0);
+  PHINode *Phi = PHINode::Create(DFS.ShadowTy, 2, "", Tail->begin());
+  Phi->addIncoming(Call, Call->getParent());
+  Phi->addIncoming(V1, Head);
+
+  CCS.Block = Tail;
+  CCS.Shadow = Phi;
+
+  std::set<Value *> UnionElems;
+  if (V1Elems != ShadowElements.end()) {
+    UnionElems = V1Elems->second;
+  } else {
+    UnionElems.insert(V1);
+  }
+  if (V2Elems != ShadowElements.end()) {
+    UnionElems.insert(V2Elems->second.begin(), V2Elems->second.end());
   } else {
-    assert(0 && "todo");
-    return 0;
+    UnionElems.insert(V2);
   }
+  ShadowElements[Phi] = std::move(UnionElems);
+
+  return Phi;
 }
 
 // A convenience function which folds the shadows of each of the operands
@@ -568,7 +965,7 @@ Value *DFSanFunction::combineOperandShadows(Instruction *Inst) {
 
   Value *Shadow = getShadow(Inst->getOperand(0));
   for (unsigned i = 1, n = Inst->getNumOperands(); i != n; ++i) {
-    Shadow = DFS.combineShadows(Shadow, getShadow(Inst->getOperand(i)), Inst);
+    Shadow = combineShadows(Shadow, getShadow(Inst->getOperand(i)), Inst);
   }
   return Shadow;
 }
@@ -621,9 +1018,8 @@ Value *DFSanFunction::loadShadow(Value *Addr, uint64_t Size, uint64_t Align,
     IRBuilder<> IRB(Pos);
     Value *ShadowAddr1 =
         IRB.CreateGEP(ShadowAddr, ConstantInt::get(DFS.IntptrTy, 1));
-    return DFS.combineShadows(IRB.CreateAlignedLoad(ShadowAddr, ShadowAlign),
-                              IRB.CreateAlignedLoad(ShadowAddr1, ShadowAlign),
-                              Pos);
+    return combineShadows(IRB.CreateAlignedLoad(ShadowAddr, ShadowAlign),
+                          IRB.CreateAlignedLoad(ShadowAddr1, ShadowAlign), Pos);
   }
   }
   if (Size % (64 / DFS.ShadowWidth) == 0) {
@@ -650,16 +1046,27 @@ Value *DFSanFunction::loadShadow(Value *Addr, uint64_t Size, uint64_t Align,
 
     BasicBlock *Head = Pos->getParent();
     BasicBlock *Tail = Head->splitBasicBlock(Pos);
+
+    if (DomTreeNode *OldNode = DT.getNode(Head)) {
+      std::vector<DomTreeNode *> Children(OldNode->begin(), OldNode->end());
+
+      DomTreeNode *NewNode = DT.addNewBlock(Tail, Head);
+      for (auto Child : Children)
+        DT.changeImmediateDominator(Child, NewNode);
+    }
+
     // In the following code LastBr will refer to the previous basic block's
     // conditional branch instruction, whose true successor is fixed up to point
     // to the next block during the loop below or to the tail after the final
     // iteration.
     BranchInst *LastBr = BranchInst::Create(FallbackBB, FallbackBB, ShadowsEq);
     ReplaceInstWithInst(Head->getTerminator(), LastBr);
+    DT.addNewBlock(FallbackBB, Head);
 
     for (uint64_t Ofs = 64 / DFS.ShadowWidth; Ofs != Size;
          Ofs += 64 / DFS.ShadowWidth) {
       BasicBlock *NextBB = BasicBlock::Create(*DFS.Ctx, "", F);
+      DT.addNewBlock(NextBB, LastBr->getParent());
       IRBuilder<> NextIRB(NextBB);
       WideAddr = NextIRB.CreateGEP(WideAddr, ConstantInt::get(DFS.IntptrTy, 1));
       Value *NextWideShadow = NextIRB.CreateAlignedLoad(WideAddr, ShadowAlign);
@@ -694,10 +1101,15 @@ void DFSanVisitor::visitLoadInst(LoadInst &LI) {
     Align = 1;
   }
   IRBuilder<> IRB(&LI);
-  Value *LoadedShadow =
-      DFSF.loadShadow(LI.getPointerOperand(), Size, Align, &LI);
-  Value *PtrShadow = DFSF.getShadow(LI.getPointerOperand());
-  DFSF.setShadow(&LI, DFSF.DFS.combineShadows(LoadedShadow, PtrShadow, &LI));
+  Value *Shadow = DFSF.loadShadow(LI.getPointerOperand(), Size, Align, &LI);
+  if (ClCombinePointerLabelsOnLoad) {
+    Value *PtrShadow = DFSF.getShadow(LI.getPointerOperand());
+    Shadow = DFSF.combineShadows(Shadow, PtrShadow, &LI);
+  }
+  if (Shadow != DFSF.DFS.ZeroShadow)
+    DFSF.NonZeroChecks.insert(Shadow);
+
+  DFSF.setShadow(&LI, Shadow);
 }
 
 void DFSanFunction::storeShadow(Value *Addr, uint64_t Size, uint64_t Align,
@@ -762,8 +1174,13 @@ void DFSanVisitor::visitStoreInst(StoreInst &SI) {
   } else {
     Align = 1;
   }
-  DFSF.storeShadow(SI.getPointerOperand(), Size, Align,
-                   DFSF.getShadow(SI.getValueOperand()), &SI);
+
+  Value* Shadow = DFSF.getShadow(SI.getValueOperand());
+  if (ClCombinePointerLabelsOnStore) {
+    Value *PtrShadow = DFSF.getShadow(SI.getPointerOperand());
+    Shadow = DFSF.combineShadows(Shadow, PtrShadow, &SI);
+  }
+  DFSF.storeShadow(SI.getPointerOperand(), Size, Align, Shadow, &SI);
 }
 
 void DFSanVisitor::visitBinaryOperator(BinaryOperator &BO) {
@@ -800,12 +1217,11 @@ void DFSanVisitor::visitInsertValueInst(InsertValueInst &I) {
 
 void DFSanVisitor::visitAllocaInst(AllocaInst &I) {
   bool AllLoadsStores = true;
-  for (Instruction::use_iterator i = I.use_begin(), e = I.use_end(); i != e;
-       ++i) {
-    if (isa<LoadInst>(*i))
+  for (User *U : I.users()) {
+    if (isa<LoadInst>(U))
       continue;
 
-    if (StoreInst *SI = dyn_cast<StoreInst>(*i)) {
+    if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
       if (SI->getPointerOperand() == &I)
         continue;
     }
@@ -827,9 +1243,9 @@ void DFSanVisitor::visitSelectInst(SelectInst &I) {
 
   if (isa<VectorType>(I.getCondition()->getType())) {
     DFSF.setShadow(
-        &I, DFSF.DFS.combineShadows(
-                CondShadow,
-                DFSF.DFS.combineShadows(TrueShadow, FalseShadow, &I), &I));
+        &I,
+        DFSF.combineShadows(
+            CondShadow, DFSF.combineShadows(TrueShadow, FalseShadow, &I), &I));
   } else {
     Value *ShadowSel;
     if (TrueShadow == FalseShadow) {
@@ -838,10 +1254,19 @@ void DFSanVisitor::visitSelectInst(SelectInst &I) {
       ShadowSel =
           SelectInst::Create(I.getCondition(), TrueShadow, FalseShadow, "", &I);
     }
-    DFSF.setShadow(&I, DFSF.DFS.combineShadows(CondShadow, ShadowSel, &I));
+    DFSF.setShadow(&I, DFSF.combineShadows(CondShadow, ShadowSel, &I));
   }
 }
 
+void DFSanVisitor::visitMemSetInst(MemSetInst &I) {
+  IRBuilder<> IRB(&I);
+  Value *ValShadow = DFSF.getShadow(I.getValue());
+  IRB.CreateCall3(
+      DFSF.DFS.DFSanSetLabelFn, ValShadow,
+      IRB.CreateBitCast(I.getDest(), Type::getInt8PtrTy(*DFSF.DFS.Ctx)),
+      IRB.CreateZExtOrTrunc(I.getLength(), DFSF.DFS.IntptrTy));
+}
+
 void DFSanVisitor::visitMemTransferInst(MemTransferInst &I) {
   IRBuilder<> IRB(&I);
   Value *DestShadow = DFSF.DFS.getShadowAddress(I.getDest(), &I);
@@ -866,7 +1291,7 @@ void DFSanVisitor::visitMemTransferInst(MemTransferInst &I) {
 }
 
 void DFSanVisitor::visitReturnInst(ReturnInst &RI) {
-  if (RI.getReturnValue()) {
+  if (!DFSF.IsNativeABI && RI.getReturnValue()) {
     switch (DFSF.IA) {
     case DataFlowSanitizer::IA_TLS: {
       Value *S = DFSF.getShadow(RI.getReturnValue());
@@ -884,8 +1309,6 @@ void DFSanVisitor::visitReturnInst(ReturnInst &RI) {
       RI.setOperand(0, InsShadow);
       break;
     }
-    default:
-      break;
     }
   }
 }
@@ -897,26 +1320,114 @@ void DFSanVisitor::visitCallSite(CallSite CS) {
     return;
   }
 
+  IRBuilder<> IRB(CS.getInstruction());
+
   DenseMap<Value *, Function *>::iterator i =
       DFSF.DFS.UnwrappedFnMap.find(CS.getCalledValue());
   if (i != DFSF.DFS.UnwrappedFnMap.end()) {
-    CS.setCalledFunction(i->second);
-    DFSF.setShadow(CS.getInstruction(), DFSF.DFS.ZeroShadow);
-    return;
-  }
+    Function *F = i->second;
+    switch (DFSF.DFS.getWrapperKind(F)) {
+    case DataFlowSanitizer::WK_Warning: {
+      CS.setCalledFunction(F);
+      IRB.CreateCall(DFSF.DFS.DFSanUnimplementedFn,
+                     IRB.CreateGlobalStringPtr(F->getName()));
+      DFSF.setShadow(CS.getInstruction(), DFSF.DFS.ZeroShadow);
+      return;
+    }
+    case DataFlowSanitizer::WK_Discard: {
+      CS.setCalledFunction(F);
+      DFSF.setShadow(CS.getInstruction(), DFSF.DFS.ZeroShadow);
+      return;
+    }
+    case DataFlowSanitizer::WK_Functional: {
+      CS.setCalledFunction(F);
+      visitOperandShadowInst(*CS.getInstruction());
+      return;
+    }
+    case DataFlowSanitizer::WK_Custom: {
+      // Don't try to handle invokes of custom functions, it's too complicated.
+      // Instead, invoke the dfsw$ wrapper, which will in turn call the __dfsw_
+      // wrapper.
+      if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction())) {
+        FunctionType *FT = F->getFunctionType();
+        FunctionType *CustomFT = DFSF.DFS.getCustomFunctionType(FT);
+        std::string CustomFName = "__dfsw_";
+        CustomFName += F->getName();
+        Constant *CustomF =
+            DFSF.DFS.Mod->getOrInsertFunction(CustomFName, CustomFT);
+        if (Function *CustomFn = dyn_cast<Function>(CustomF)) {
+          CustomFn->copyAttributesFrom(F);
+
+          // Custom functions returning non-void will write to the return label.
+          if (!FT->getReturnType()->isVoidTy()) {
+            CustomFn->removeAttributes(AttributeSet::FunctionIndex,
+                                       DFSF.DFS.ReadOnlyNoneAttrs);
+          }
+        }
 
-  IRBuilder<> IRB(CS.getInstruction());
+        std::vector<Value *> Args;
+
+        CallSite::arg_iterator i = CS.arg_begin();
+        for (unsigned n = FT->getNumParams(); n != 0; ++i, --n) {
+          Type *T = (*i)->getType();
+          FunctionType *ParamFT;
+          if (isa<PointerType>(T) &&
+              (ParamFT = dyn_cast<FunctionType>(
+                   cast<PointerType>(T)->getElementType()))) {
+            std::string TName = "dfst";
+            TName += utostr(FT->getNumParams() - n);
+            TName += "$";
+            TName += F->getName();
+            Constant *T = DFSF.DFS.getOrBuildTrampolineFunction(ParamFT, TName);
+            Args.push_back(T);
+            Args.push_back(
+                IRB.CreateBitCast(*i, Type::getInt8PtrTy(*DFSF.DFS.Ctx)));
+          } else {
+            Args.push_back(*i);
+          }
+        }
+
+        i = CS.arg_begin();
+        for (unsigned n = FT->getNumParams(); n != 0; ++i, --n)
+          Args.push_back(DFSF.getShadow(*i));
+
+        if (!FT->getReturnType()->isVoidTy()) {
+          if (!DFSF.LabelReturnAlloca) {
+            DFSF.LabelReturnAlloca =
+                new AllocaInst(DFSF.DFS.ShadowTy, "labelreturn",
+                               DFSF.F->getEntryBlock().begin());
+          }
+          Args.push_back(DFSF.LabelReturnAlloca);
+        }
+
+        CallInst *CustomCI = IRB.CreateCall(CustomF, Args);
+        CustomCI->setCallingConv(CI->getCallingConv());
+        CustomCI->setAttributes(CI->getAttributes());
+
+        if (!FT->getReturnType()->isVoidTy()) {
+          LoadInst *LabelLoad = IRB.CreateLoad(DFSF.LabelReturnAlloca);
+          DFSF.setShadow(CustomCI, LabelLoad);
+        }
+
+        CI->replaceAllUsesWith(CustomCI);
+        CI->eraseFromParent();
+        return;
+      }
+      break;
+    }
+    }
+  }
 
   FunctionType *FT = cast<FunctionType>(
       CS.getCalledValue()->getType()->getPointerElementType());
-  if (DFSF.DFS.getDefaultInstrumentedABI() == DataFlowSanitizer::IA_TLS) {
+  if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_TLS) {
     for (unsigned i = 0, n = FT->getNumParams(); i != n; ++i) {
       IRB.CreateStore(DFSF.getShadow(CS.getArgument(i)),
                       DFSF.getArgTLS(i, CS.getInstruction()));
     }
   }
 
-  Instruction *Next = 0;
+  Instruction *Next = nullptr;
   if (!CS.getType()->isVoidTy()) {
     if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
       if (II->getNormalDest()->getSinglePredecessor()) {
@@ -930,18 +1441,19 @@ void DFSanVisitor::visitCallSite(CallSite CS) {
       Next = CS->getNextNode();
     }
 
-    if (DFSF.DFS.getDefaultInstrumentedABI() == DataFlowSanitizer::IA_TLS) {
+    if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_TLS) {
       IRBuilder<> NextIRB(Next);
       LoadInst *LI = NextIRB.CreateLoad(DFSF.getRetvalTLS());
       DFSF.SkipInsts.insert(LI);
       DFSF.setShadow(CS.getInstruction(), LI);
+      DFSF.NonZeroChecks.insert(LI);
     }
   }
 
   // Do all instrumentation for IA_Args down here to defer tampering with the
   // CFG in a way that SplitEdge may be able to detect.
-  if (DFSF.DFS.getDefaultInstrumentedABI() == DataFlowSanitizer::IA_Args) {
-    FunctionType *NewFT = DFSF.DFS.getInstrumentedFunctionType(FT);
+  if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_Args) {
+    FunctionType *NewFT = DFSF.DFS.getArgsFunctionType(FT);
     Value *Func =
         IRB.CreateBitCast(CS.getCalledValue(), PointerType::getUnqual(NewFT));
     std::vector<Value *> Args;
@@ -988,6 +1500,7 @@ void DFSanVisitor::visitCallSite(CallSite CS) {
           ExtractValueInst::Create(NewCS.getInstruction(), 1, "", Next);
       DFSF.SkipInsts.insert(ExShadow);
       DFSF.setShadow(ExVal, ExShadow);
+      DFSF.NonZeroChecks.insert(ExShadow);
 
       CS.getInstruction()->replaceAllUsesWith(ExVal);
     }