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diff --git a/contrib/libs/llvm16/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/contrib/libs/llvm16/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
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+//===- DataFlowSanitizer.cpp - dynamic data flow analysis -----------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file
+/// This file is a part of DataFlowSanitizer, a generalised dynamic data flow
+/// analysis.
+///
+/// Unlike other Sanitizer tools, this tool is not designed to detect a specific
+/// class of bugs on its own.  Instead, it provides a generic dynamic data flow
+/// analysis framework to be used by clients to help detect application-specific
+/// issues within their own code.
+///
+/// The analysis is based on automatic propagation of data flow labels (also
+/// known as taint labels) through a program as it performs computation.
+///
+/// Argument and return value labels are passed through TLS variables
+/// __dfsan_arg_tls and __dfsan_retval_tls.
+///
+/// Each byte of application memory is backed by a shadow memory byte. The
+/// shadow byte can represent up to 8 labels. On Linux/x86_64, memory is then
+/// laid out as follows:
+///
+/// +--------------------+ 0x800000000000 (top of memory)
+/// |    application 3   |
+/// +--------------------+ 0x700000000000
+/// |      invalid       |
+/// +--------------------+ 0x610000000000
+/// |      origin 1      |
+/// +--------------------+ 0x600000000000
+/// |    application 2   |
+/// +--------------------+ 0x510000000000
+/// |      shadow 1      |
+/// +--------------------+ 0x500000000000
+/// |      invalid       |
+/// +--------------------+ 0x400000000000
+/// |      origin 3      |
+/// +--------------------+ 0x300000000000
+/// |      shadow 3      |
+/// +--------------------+ 0x200000000000
+/// |      origin 2      |
+/// +--------------------+ 0x110000000000
+/// |      invalid       |
+/// +--------------------+ 0x100000000000
+/// |      shadow 2      |
+/// +--------------------+ 0x010000000000
+/// |    application 1   |
+/// +--------------------+ 0x000000000000
+///
+/// MEM_TO_SHADOW(mem) = mem ^ 0x500000000000
+/// SHADOW_TO_ORIGIN(shadow) = shadow + 0x100000000000
+///
+/// For more information, please refer to the design document:
+/// http://clang.llvm.org/docs/DataFlowSanitizerDesign.html
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Instrumentation/DataFlowSanitizer.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/StringSet.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/ADT/iterator.h"
+#include "llvm/Analysis/GlobalsModRef.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/Argument.h"
+#include "llvm/IR/Attributes.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Constant.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/GlobalAlias.h"
+#include "llvm/IR/GlobalValue.h"
+#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/InstVisitor.h"
+#include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/MDBuilder.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/IR/Type.h"
+#include "llvm/IR/User.h"
+#include "llvm/IR/Value.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Alignment.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/SpecialCaseList.h"
+#include "llvm/Support/VirtualFileSystem.h"
+#include "llvm/Transforms/Instrumentation.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <set>
+#include <string>
+#include <utility>
+#include <vector>
+
+using namespace llvm;
+
+// This must be consistent with ShadowWidthBits.
+static const Align ShadowTLSAlignment = Align(2);
+
+static const Align MinOriginAlignment = Align(4);
+
+// The size of TLS variables. These constants must be kept in sync with the ones
+// in dfsan.cpp.
+static const unsigned ArgTLSSize = 800;
+static const unsigned RetvalTLSSize = 800;
+
+// The -dfsan-preserve-alignment flag controls whether this pass assumes that
+// alignment requirements provided by the input IR are correct.  For example,
+// if the input IR contains a load with alignment 8, this flag will cause
+// the shadow load to have alignment 16.  This flag is disabled by default as
+// we have unfortunately encountered too much code (including Clang itself;
+// see PR14291) which performs misaligned access.
+static cl::opt<bool> ClPreserveAlignment(
+    "dfsan-preserve-alignment",
+    cl::desc("respect alignment requirements provided by input IR"), cl::Hidden,
+    cl::init(false));
+
+// The ABI list files control 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 for uninstrumented functions are
+// "functional" and "discard", which are described below under
+// DataFlowSanitizer::WrapperKind.
+// Functions will often be labelled with both "uninstrumented" and one of
+// "functional" or "discard". This will leave the function unchanged by this
+// pass, and create a wrapper function that will call the original.
+//
+// Instrumented functions can also be annotated as "force_zero_labels", which
+// will make all shadow and return values set zero labels.
+// Functions should never be labelled with both "force_zero_labels" and
+// "uninstrumented" or any of the unistrumented wrapper kinds.
+static cl::list<std::string> ClABIListFiles(
+    "dfsan-abilist",
+    cl::desc("File listing native ABI functions and how the pass treats them"),
+    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));
+
+// Controls whether the pass propagates labels of offsets in GEP instructions.
+static cl::opt<bool> ClCombineOffsetLabelsOnGEP(
+    "dfsan-combine-offset-labels-on-gep",
+    cl::desc(
+        "Combine the label of the offset with the label of the pointer when "
+        "doing pointer arithmetic."),
+    cl::Hidden, cl::init(true));
+
+static cl::list<std::string> ClCombineTaintLookupTables(
+    "dfsan-combine-taint-lookup-table",
+    cl::desc(
+        "When dfsan-combine-offset-labels-on-gep and/or "
+        "dfsan-combine-pointer-labels-on-load are false, this flag can "
+        "be used to re-enable combining offset and/or pointer taint when "
+        "loading specific constant global variables (i.e. lookup tables)."),
+    cl::Hidden);
+
+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);
+
+// Experimental feature that inserts callbacks for certain data events.
+// Currently callbacks are only inserted for loads, stores, memory transfers
+// (i.e. memcpy and memmove), and comparisons.
+//
+// If this flag is set to true, the user must provide definitions for the
+// following callback functions:
+//   void __dfsan_load_callback(dfsan_label Label, void* addr);
+//   void __dfsan_store_callback(dfsan_label Label, void* addr);
+//   void __dfsan_mem_transfer_callback(dfsan_label *Start, size_t Len);
+//   void __dfsan_cmp_callback(dfsan_label CombinedLabel);
+static cl::opt<bool> ClEventCallbacks(
+    "dfsan-event-callbacks",
+    cl::desc("Insert calls to __dfsan_*_callback functions on data events."),
+    cl::Hidden, cl::init(false));
+
+// Experimental feature that inserts callbacks for conditionals, including:
+// conditional branch, switch, select.
+// This must be true for dfsan_set_conditional_callback() to have effect.
+static cl::opt<bool> ClConditionalCallbacks(
+    "dfsan-conditional-callbacks",
+    cl::desc("Insert calls to callback functions on conditionals."), cl::Hidden,
+    cl::init(false));
+
+// Experimental feature that inserts callbacks for data reaching a function,
+// either via function arguments and loads.
+// This must be true for dfsan_set_reaches_function_callback() to have effect.
+static cl::opt<bool> ClReachesFunctionCallbacks(
+    "dfsan-reaches-function-callbacks",
+    cl::desc("Insert calls to callback functions on data reaching a function."),
+    cl::Hidden, cl::init(false));
+
+// Controls whether the pass tracks the control flow of select instructions.
+static cl::opt<bool> ClTrackSelectControlFlow(
+    "dfsan-track-select-control-flow",
+    cl::desc("Propagate labels from condition values of select instructions "
+             "to results."),
+    cl::Hidden, cl::init(true));
+
+// TODO: This default value follows MSan. DFSan may use a different value.
+static cl::opt<int> ClInstrumentWithCallThreshold(
+    "dfsan-instrument-with-call-threshold",
+    cl::desc("If the function being instrumented requires more than "
+             "this number of origin stores, use callbacks instead of "
+             "inline checks (-1 means never use callbacks)."),
+    cl::Hidden, cl::init(3500));
+
+// Controls how to track origins.
+// * 0: do not track origins.
+// * 1: track origins at memory store operations.
+// * 2: track origins at memory load and store operations.
+//      TODO: track callsites.
+static cl::opt<int> ClTrackOrigins("dfsan-track-origins",
+                                   cl::desc("Track origins of labels"),
+                                   cl::Hidden, cl::init(0));
+
+static cl::opt<bool> ClIgnorePersonalityRoutine(
+    "dfsan-ignore-personality-routine",
+    cl::desc("If a personality routine is marked uninstrumented from the ABI "
+             "list, do not create a wrapper for it."),
+    cl::Hidden, cl::init(false));
+
+static StringRef getGlobalTypeString(const GlobalValue &G) {
+  // Types of GlobalVariables are always pointer types.
+  Type *GType = G.getValueType();
+  // For now we support excluding struct types only.
+  if (StructType *SGType = dyn_cast<StructType>(GType)) {
+    if (!SGType->isLiteral())
+      return SGType->getName();
+  }
+  return "<unknown type>";
+}
+
+namespace {
+
+// Memory map parameters used in application-to-shadow address calculation.
+// Offset = (Addr & ~AndMask) ^ XorMask
+// Shadow = ShadowBase + Offset
+// Origin = (OriginBase + Offset) & ~3ULL
+struct MemoryMapParams {
+  uint64_t AndMask;
+  uint64_t XorMask;
+  uint64_t ShadowBase;
+  uint64_t OriginBase;
+};
+
+} // end anonymous namespace
+
+// NOLINTBEGIN(readability-identifier-naming)
+// aarch64 Linux
+const MemoryMapParams Linux_AArch64_MemoryMapParams = {
+    0,               // AndMask (not used)
+    0x0B00000000000, // XorMask
+    0,               // ShadowBase (not used)
+    0x0200000000000, // OriginBase
+};
+
+// x86_64 Linux
+const MemoryMapParams Linux_X86_64_MemoryMapParams = {
+    0,              // AndMask (not used)
+    0x500000000000, // XorMask
+    0,              // ShadowBase (not used)
+    0x100000000000, // OriginBase
+};
+// NOLINTEND(readability-identifier-naming)
+
+namespace {
+
+class DFSanABIList {
+  std::unique_ptr<SpecialCaseList> SCL;
+
+public:
+  DFSanABIList() = default;
+
+  void set(std::unique_ptr<SpecialCaseList> List) { SCL = std::move(List); }
+
+  /// Returns whether either this function or its source file are listed in the
+  /// given category.
+  bool isIn(const Function &F, StringRef Category) const {
+    return isIn(*F.getParent(), Category) ||
+           SCL->inSection("dataflow", "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, StringRef Category) const {
+    if (isIn(*GA.getParent(), Category))
+      return true;
+
+    if (isa<FunctionType>(GA.getValueType()))
+      return SCL->inSection("dataflow", "fun", GA.getName(), Category);
+
+    return SCL->inSection("dataflow", "global", GA.getName(), Category) ||
+           SCL->inSection("dataflow", "type", getGlobalTypeString(GA),
+                          Category);
+  }
+
+  /// Returns whether this module is listed in the given category.
+  bool isIn(const Module &M, StringRef Category) const {
+    return SCL->inSection("dataflow", "src", M.getModuleIdentifier(), Category);
+  }
+};
+
+/// TransformedFunction is used to express the result of transforming one
+/// function type into another.  This struct is immutable.  It holds metadata
+/// useful for updating calls of the old function to the new type.
+struct TransformedFunction {
+  TransformedFunction(FunctionType *OriginalType, FunctionType *TransformedType,
+                      std::vector<unsigned> ArgumentIndexMapping)
+      : OriginalType(OriginalType), TransformedType(TransformedType),
+        ArgumentIndexMapping(ArgumentIndexMapping) {}
+
+  // Disallow copies.
+  TransformedFunction(const TransformedFunction &) = delete;
+  TransformedFunction &operator=(const TransformedFunction &) = delete;
+
+  // Allow moves.
+  TransformedFunction(TransformedFunction &&) = default;
+  TransformedFunction &operator=(TransformedFunction &&) = default;
+
+  /// Type of the function before the transformation.
+  FunctionType *OriginalType;
+
+  /// Type of the function after the transformation.
+  FunctionType *TransformedType;
+
+  /// Transforming a function may change the position of arguments.  This
+  /// member records the mapping from each argument's old position to its new
+  /// position.  Argument positions are zero-indexed.  If the transformation
+  /// from F to F' made the first argument of F into the third argument of F',
+  /// then ArgumentIndexMapping[0] will equal 2.
+  std::vector<unsigned> ArgumentIndexMapping;
+};
+
+/// Given function attributes from a call site for the original function,
+/// return function attributes appropriate for a call to the transformed
+/// function.
+AttributeList
+transformFunctionAttributes(const TransformedFunction &TransformedFunction,
+                            LLVMContext &Ctx, AttributeList CallSiteAttrs) {
+
+  // Construct a vector of AttributeSet for each function argument.
+  std::vector<llvm::AttributeSet> ArgumentAttributes(
+      TransformedFunction.TransformedType->getNumParams());
+
+  // Copy attributes from the parameter of the original function to the
+  // transformed version.  'ArgumentIndexMapping' holds the mapping from
+  // old argument position to new.
+  for (unsigned I = 0, IE = TransformedFunction.ArgumentIndexMapping.size();
+       I < IE; ++I) {
+    unsigned TransformedIndex = TransformedFunction.ArgumentIndexMapping[I];
+    ArgumentAttributes[TransformedIndex] = CallSiteAttrs.getParamAttrs(I);
+  }
+
+  // Copy annotations on varargs arguments.
+  for (unsigned I = TransformedFunction.OriginalType->getNumParams(),
+                IE = CallSiteAttrs.getNumAttrSets();
+       I < IE; ++I) {
+    ArgumentAttributes.push_back(CallSiteAttrs.getParamAttrs(I));
+  }
+
+  return AttributeList::get(Ctx, CallSiteAttrs.getFnAttrs(),
+                            CallSiteAttrs.getRetAttrs(),
+                            llvm::ArrayRef(ArgumentAttributes));
+}
+
+class DataFlowSanitizer {
+  friend struct DFSanFunction;
+  friend class DFSanVisitor;
+
+  enum { ShadowWidthBits = 8, ShadowWidthBytes = ShadowWidthBits / 8 };
+
+  enum { OriginWidthBits = 32, OriginWidthBytes = OriginWidthBits / 8 };
+
+  /// 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. 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
+  };
+
+  Module *Mod;
+  LLVMContext *Ctx;
+  Type *Int8Ptr;
+  IntegerType *OriginTy;
+  PointerType *OriginPtrTy;
+  ConstantInt *ZeroOrigin;
+  /// The shadow type for all primitive types and vector types.
+  IntegerType *PrimitiveShadowTy;
+  PointerType *PrimitiveShadowPtrTy;
+  IntegerType *IntptrTy;
+  ConstantInt *ZeroPrimitiveShadow;
+  Constant *ArgTLS;
+  ArrayType *ArgOriginTLSTy;
+  Constant *ArgOriginTLS;
+  Constant *RetvalTLS;
+  Constant *RetvalOriginTLS;
+  FunctionType *DFSanUnionLoadFnTy;
+  FunctionType *DFSanLoadLabelAndOriginFnTy;
+  FunctionType *DFSanUnimplementedFnTy;
+  FunctionType *DFSanWrapperExternWeakNullFnTy;
+  FunctionType *DFSanSetLabelFnTy;
+  FunctionType *DFSanNonzeroLabelFnTy;
+  FunctionType *DFSanVarargWrapperFnTy;
+  FunctionType *DFSanConditionalCallbackFnTy;
+  FunctionType *DFSanConditionalCallbackOriginFnTy;
+  FunctionType *DFSanReachesFunctionCallbackFnTy;
+  FunctionType *DFSanReachesFunctionCallbackOriginFnTy;
+  FunctionType *DFSanCmpCallbackFnTy;
+  FunctionType *DFSanLoadStoreCallbackFnTy;
+  FunctionType *DFSanMemTransferCallbackFnTy;
+  FunctionType *DFSanChainOriginFnTy;
+  FunctionType *DFSanChainOriginIfTaintedFnTy;
+  FunctionType *DFSanMemOriginTransferFnTy;
+  FunctionType *DFSanMemShadowOriginTransferFnTy;
+  FunctionType *DFSanMemShadowOriginConditionalExchangeFnTy;
+  FunctionType *DFSanMaybeStoreOriginFnTy;
+  FunctionCallee DFSanUnionLoadFn;
+  FunctionCallee DFSanLoadLabelAndOriginFn;
+  FunctionCallee DFSanUnimplementedFn;
+  FunctionCallee DFSanWrapperExternWeakNullFn;
+  FunctionCallee DFSanSetLabelFn;
+  FunctionCallee DFSanNonzeroLabelFn;
+  FunctionCallee DFSanVarargWrapperFn;
+  FunctionCallee DFSanLoadCallbackFn;
+  FunctionCallee DFSanStoreCallbackFn;
+  FunctionCallee DFSanMemTransferCallbackFn;
+  FunctionCallee DFSanConditionalCallbackFn;
+  FunctionCallee DFSanConditionalCallbackOriginFn;
+  FunctionCallee DFSanReachesFunctionCallbackFn;
+  FunctionCallee DFSanReachesFunctionCallbackOriginFn;
+  FunctionCallee DFSanCmpCallbackFn;
+  FunctionCallee DFSanChainOriginFn;
+  FunctionCallee DFSanChainOriginIfTaintedFn;
+  FunctionCallee DFSanMemOriginTransferFn;
+  FunctionCallee DFSanMemShadowOriginTransferFn;
+  FunctionCallee DFSanMemShadowOriginConditionalExchangeFn;
+  FunctionCallee DFSanMaybeStoreOriginFn;
+  SmallPtrSet<Value *, 16> DFSanRuntimeFunctions;
+  MDNode *ColdCallWeights;
+  MDNode *OriginStoreWeights;
+  DFSanABIList ABIList;
+  DenseMap<Value *, Function *> UnwrappedFnMap;
+  AttributeMask ReadOnlyNoneAttrs;
+  StringSet<> CombineTaintLookupTableNames;
+
+  /// Memory map parameters used in calculation mapping application addresses
+  /// to shadow addresses and origin addresses.
+  const MemoryMapParams *MapParams;
+
+  Value *getShadowOffset(Value *Addr, IRBuilder<> &IRB);
+  Value *getShadowAddress(Value *Addr, Instruction *Pos);
+  Value *getShadowAddress(Value *Addr, Instruction *Pos, Value *ShadowOffset);
+  std::pair<Value *, Value *>
+  getShadowOriginAddress(Value *Addr, Align InstAlignment, Instruction *Pos);
+  bool isInstrumented(const Function *F);
+  bool isInstrumented(const GlobalAlias *GA);
+  bool isForceZeroLabels(const Function *F);
+  TransformedFunction getCustomFunctionType(FunctionType *T);
+  WrapperKind getWrapperKind(Function *F);
+  void addGlobalNameSuffix(GlobalValue *GV);
+  void buildExternWeakCheckIfNeeded(IRBuilder<> &IRB, Function *F);
+  Function *buildWrapperFunction(Function *F, StringRef NewFName,
+                                 GlobalValue::LinkageTypes NewFLink,
+                                 FunctionType *NewFT);
+  void initializeCallbackFunctions(Module &M);
+  void initializeRuntimeFunctions(Module &M);
+  bool initializeModule(Module &M);
+
+  /// Advances \p OriginAddr to point to the next 32-bit origin and then loads
+  /// from it. Returns the origin's loaded value.
+  Value *loadNextOrigin(Instruction *Pos, Align OriginAlign,
+                        Value **OriginAddr);
+
+  /// Returns whether the given load byte size is amenable to inlined
+  /// optimization patterns.
+  bool hasLoadSizeForFastPath(uint64_t Size);
+
+  /// Returns whether the pass tracks origins. Supports only TLS ABI mode.
+  bool shouldTrackOrigins();
+
+  /// Returns a zero constant with the shadow type of OrigTy.
+  ///
+  /// getZeroShadow({T1,T2,...}) = {getZeroShadow(T1),getZeroShadow(T2,...}
+  /// getZeroShadow([n x T]) = [n x getZeroShadow(T)]
+  /// getZeroShadow(other type) = i16(0)
+  Constant *getZeroShadow(Type *OrigTy);
+  /// Returns a zero constant with the shadow type of V's type.
+  Constant *getZeroShadow(Value *V);
+
+  /// Checks if V is a zero shadow.
+  bool isZeroShadow(Value *V);
+
+  /// Returns the shadow type of OrigTy.
+  ///
+  /// getShadowTy({T1,T2,...}) = {getShadowTy(T1),getShadowTy(T2),...}
+  /// getShadowTy([n x T]) = [n x getShadowTy(T)]
+  /// getShadowTy(other type) = i16
+  Type *getShadowTy(Type *OrigTy);
+  /// Returns the shadow type of of V's type.
+  Type *getShadowTy(Value *V);
+
+  const uint64_t NumOfElementsInArgOrgTLS = ArgTLSSize / OriginWidthBytes;
+
+public:
+  DataFlowSanitizer(const std::vector<std::string> &ABIListFiles);
+
+  bool runImpl(Module &M,
+               llvm::function_ref<TargetLibraryInfo &(Function &)> GetTLI);
+};
+
+struct DFSanFunction {
+  DataFlowSanitizer &DFS;
+  Function *F;
+  DominatorTree DT;
+  bool IsNativeABI;
+  bool IsForceZeroLabels;
+  TargetLibraryInfo &TLI;
+  AllocaInst *LabelReturnAlloca = nullptr;
+  AllocaInst *OriginReturnAlloca = nullptr;
+  DenseMap<Value *, Value *> ValShadowMap;
+  DenseMap<Value *, Value *> ValOriginMap;
+  DenseMap<AllocaInst *, AllocaInst *> AllocaShadowMap;
+  DenseMap<AllocaInst *, AllocaInst *> AllocaOriginMap;
+
+  struct PHIFixupElement {
+    PHINode *Phi;
+    PHINode *ShadowPhi;
+    PHINode *OriginPhi;
+  };
+  std::vector<PHIFixupElement> PHIFixups;
+
+  DenseSet<Instruction *> SkipInsts;
+  std::vector<Value *> NonZeroChecks;
+
+  struct CachedShadow {
+    BasicBlock *Block; // The block where Shadow is defined.
+    Value *Shadow;
+  };
+  /// Maps a value to its latest shadow value in terms of domination tree.
+  DenseMap<std::pair<Value *, Value *>, CachedShadow> CachedShadows;
+  /// Maps a value to its latest collapsed shadow value it was converted to in
+  /// terms of domination tree. When ClDebugNonzeroLabels is on, this cache is
+  /// used at a post process where CFG blocks are split. So it does not cache
+  /// BasicBlock like CachedShadows, but uses domination between values.
+  DenseMap<Value *, Value *> CachedCollapsedShadows;
+  DenseMap<Value *, std::set<Value *>> ShadowElements;
+
+  DFSanFunction(DataFlowSanitizer &DFS, Function *F, bool IsNativeABI,
+                bool IsForceZeroLabels, TargetLibraryInfo &TLI)
+      : DFS(DFS), F(F), IsNativeABI(IsNativeABI),
+        IsForceZeroLabels(IsForceZeroLabels), TLI(TLI) {
+    DT.recalculate(*F);
+  }
+
+  /// Computes the shadow address for a given function argument.
+  ///
+  /// Shadow = ArgTLS+ArgOffset.
+  Value *getArgTLS(Type *T, unsigned ArgOffset, IRBuilder<> &IRB);
+
+  /// Computes the shadow address for a return value.
+  Value *getRetvalTLS(Type *T, IRBuilder<> &IRB);
+
+  /// Computes the origin address for a given function argument.
+  ///
+  /// Origin = ArgOriginTLS[ArgNo].
+  Value *getArgOriginTLS(unsigned ArgNo, IRBuilder<> &IRB);
+
+  /// Computes the origin address for a return value.
+  Value *getRetvalOriginTLS();
+
+  Value *getOrigin(Value *V);
+  void setOrigin(Instruction *I, Value *Origin);
+  /// Generates IR to compute the origin of the last operand with a taint label.
+  Value *combineOperandOrigins(Instruction *Inst);
+  /// Before the instruction Pos, generates IR to compute the last origin with a
+  /// taint label. Labels and origins are from vectors Shadows and Origins
+  /// correspondingly. The generated IR is like
+  ///   Sn-1 != Zero ? On-1: ... S2 != Zero ? O2: S1 != Zero ? O1: O0
+  /// When Zero is nullptr, it uses ZeroPrimitiveShadow. Otherwise it can be
+  /// zeros with other bitwidths.
+  Value *combineOrigins(const std::vector<Value *> &Shadows,
+                        const std::vector<Value *> &Origins, Instruction *Pos,
+                        ConstantInt *Zero = nullptr);
+
+  Value *getShadow(Value *V);
+  void setShadow(Instruction *I, Value *Shadow);
+  /// Generates IR to compute the union of the two given shadows, inserting it
+  /// before Pos. The combined value is with primitive type.
+  Value *combineShadows(Value *V1, Value *V2, Instruction *Pos);
+  /// Combines the shadow values of V1 and V2, then converts the combined value
+  /// with primitive type into a shadow value with the original type T.
+  Value *combineShadowsThenConvert(Type *T, Value *V1, Value *V2,
+                                   Instruction *Pos);
+  Value *combineOperandShadows(Instruction *Inst);
+
+  /// Generates IR to load shadow and origin corresponding to bytes [\p
+  /// Addr, \p Addr + \p Size), where addr has alignment \p
+  /// InstAlignment, and take the union of each of those shadows. The returned
+  /// shadow always has primitive type.
+  ///
+  /// When tracking loads is enabled, the returned origin is a chain at the
+  /// current stack if the returned shadow is tainted.
+  std::pair<Value *, Value *> loadShadowOrigin(Value *Addr, uint64_t Size,
+                                               Align InstAlignment,
+                                               Instruction *Pos);
+
+  void storePrimitiveShadowOrigin(Value *Addr, uint64_t Size,
+                                  Align InstAlignment, Value *PrimitiveShadow,
+                                  Value *Origin, Instruction *Pos);
+  /// Applies PrimitiveShadow to all primitive subtypes of T, returning
+  /// the expanded shadow value.
+  ///
+  /// EFP({T1,T2, ...}, PS) = {EFP(T1,PS),EFP(T2,PS),...}
+  /// EFP([n x T], PS) = [n x EFP(T,PS)]
+  /// EFP(other types, PS) = PS
+  Value *expandFromPrimitiveShadow(Type *T, Value *PrimitiveShadow,
+                                   Instruction *Pos);
+  /// Collapses Shadow into a single primitive shadow value, unioning all
+  /// primitive shadow values in the process. Returns the final primitive
+  /// shadow value.
+  ///
+  /// CTP({V1,V2, ...}) = UNION(CFP(V1,PS),CFP(V2,PS),...)
+  /// CTP([V1,V2,...]) = UNION(CFP(V1,PS),CFP(V2,PS),...)
+  /// CTP(other types, PS) = PS
+  Value *collapseToPrimitiveShadow(Value *Shadow, Instruction *Pos);
+
+  void storeZeroPrimitiveShadow(Value *Addr, uint64_t Size, Align ShadowAlign,
+                                Instruction *Pos);
+
+  Align getShadowAlign(Align InstAlignment);
+
+  // If ClConditionalCallbacks is enabled, insert a callback after a given
+  // branch instruction using the given conditional expression.
+  void addConditionalCallbacksIfEnabled(Instruction &I, Value *Condition);
+
+  // If ClReachesFunctionCallbacks is enabled, insert a callback for each
+  // argument and load instruction.
+  void addReachesFunctionCallbacksIfEnabled(IRBuilder<> &IRB, Instruction &I,
+                                            Value *Data);
+
+  bool isLookupTableConstant(Value *P);
+
+private:
+  /// Collapses the shadow with aggregate type into a single primitive shadow
+  /// value.
+  template <class AggregateType>
+  Value *collapseAggregateShadow(AggregateType *AT, Value *Shadow,
+                                 IRBuilder<> &IRB);
+
+  Value *collapseToPrimitiveShadow(Value *Shadow, IRBuilder<> &IRB);
+
+  /// Returns the shadow value of an argument A.
+  Value *getShadowForTLSArgument(Argument *A);
+
+  /// The fast path of loading shadows.
+  std::pair<Value *, Value *>
+  loadShadowFast(Value *ShadowAddr, Value *OriginAddr, uint64_t Size,
+                 Align ShadowAlign, Align OriginAlign, Value *FirstOrigin,
+                 Instruction *Pos);
+
+  Align getOriginAlign(Align InstAlignment);
+
+  /// Because 4 contiguous bytes share one 4-byte origin, the most accurate load
+  /// is __dfsan_load_label_and_origin. This function returns the union of all
+  /// labels and the origin of the first taint label. However this is an
+  /// additional call with many instructions. To ensure common cases are fast,
+  /// checks if it is possible to load labels and origins without using the
+  /// callback function.
+  ///
+  /// When enabling tracking load instructions, we always use
+  /// __dfsan_load_label_and_origin to reduce code size.
+  bool useCallbackLoadLabelAndOrigin(uint64_t Size, Align InstAlignment);
+
+  /// Returns a chain at the current stack with previous origin V.
+  Value *updateOrigin(Value *V, IRBuilder<> &IRB);
+
+  /// Returns a chain at the current stack with previous origin V if Shadow is
+  /// tainted.
+  Value *updateOriginIfTainted(Value *Shadow, Value *Origin, IRBuilder<> &IRB);
+
+  /// Creates an Intptr = Origin | Origin << 32 if Intptr's size is 64. Returns
+  /// Origin otherwise.
+  Value *originToIntptr(IRBuilder<> &IRB, Value *Origin);
+
+  /// Stores Origin into the address range [StoreOriginAddr, StoreOriginAddr +
+  /// Size).
+  void paintOrigin(IRBuilder<> &IRB, Value *Origin, Value *StoreOriginAddr,
+                   uint64_t StoreOriginSize, Align Alignment);
+
+  /// Stores Origin in terms of its Shadow value.
+  /// * Do not write origins for zero shadows because we do not trace origins
+  ///   for untainted sinks.
+  /// * Use __dfsan_maybe_store_origin if there are too many origin store
+  ///   instrumentations.
+  void storeOrigin(Instruction *Pos, Value *Addr, uint64_t Size, Value *Shadow,
+                   Value *Origin, Value *StoreOriginAddr, Align InstAlignment);
+
+  /// Convert a scalar value to an i1 by comparing with 0.
+  Value *convertToBool(Value *V, IRBuilder<> &IRB, const Twine &Name = "");
+
+  bool shouldInstrumentWithCall();
+
+  /// Generates IR to load shadow and origin corresponding to bytes [\p
+  /// Addr, \p Addr + \p Size), where addr has alignment \p
+  /// InstAlignment, and take the union of each of those shadows. The returned
+  /// shadow always has primitive type.
+  std::pair<Value *, Value *>
+  loadShadowOriginSansLoadTracking(Value *Addr, uint64_t Size,
+                                   Align InstAlignment, Instruction *Pos);
+  int NumOriginStores = 0;
+};
+
+class DFSanVisitor : public InstVisitor<DFSanVisitor> {
+public:
+  DFSanFunction &DFSF;
+
+  DFSanVisitor(DFSanFunction &DFSF) : DFSF(DFSF) {}
+
+  const DataLayout &getDataLayout() const {
+    return DFSF.F->getParent()->getDataLayout();
+  }
+
+  // Combines shadow values and origins for all of I's operands.
+  void visitInstOperands(Instruction &I);
+
+  void visitUnaryOperator(UnaryOperator &UO);
+  void visitBinaryOperator(BinaryOperator &BO);
+  void visitBitCastInst(BitCastInst &BCI);
+  void visitCastInst(CastInst &CI);
+  void visitCmpInst(CmpInst &CI);
+  void visitLandingPadInst(LandingPadInst &LPI);
+  void visitGetElementPtrInst(GetElementPtrInst &GEPI);
+  void visitLoadInst(LoadInst &LI);
+  void visitStoreInst(StoreInst &SI);
+  void visitAtomicRMWInst(AtomicRMWInst &I);
+  void visitAtomicCmpXchgInst(AtomicCmpXchgInst &I);
+  void visitReturnInst(ReturnInst &RI);
+  void visitLibAtomicLoad(CallBase &CB);
+  void visitLibAtomicStore(CallBase &CB);
+  void visitLibAtomicExchange(CallBase &CB);
+  void visitLibAtomicCompareExchange(CallBase &CB);
+  void visitCallBase(CallBase &CB);
+  void visitPHINode(PHINode &PN);
+  void visitExtractElementInst(ExtractElementInst &I);
+  void visitInsertElementInst(InsertElementInst &I);
+  void visitShuffleVectorInst(ShuffleVectorInst &I);
+  void visitExtractValueInst(ExtractValueInst &I);
+  void visitInsertValueInst(InsertValueInst &I);
+  void visitAllocaInst(AllocaInst &I);
+  void visitSelectInst(SelectInst &I);
+  void visitMemSetInst(MemSetInst &I);
+  void visitMemTransferInst(MemTransferInst &I);
+  void visitBranchInst(BranchInst &BR);
+  void visitSwitchInst(SwitchInst &SW);
+
+private:
+  void visitCASOrRMW(Align InstAlignment, Instruction &I);
+
+  // Returns false when this is an invoke of a custom function.
+  bool visitWrappedCallBase(Function &F, CallBase &CB);
+
+  // Combines origins for all of I's operands.
+  void visitInstOperandOrigins(Instruction &I);
+
+  void addShadowArguments(Function &F, CallBase &CB, std::vector<Value *> &Args,
+                          IRBuilder<> &IRB);
+
+  void addOriginArguments(Function &F, CallBase &CB, std::vector<Value *> &Args,
+                          IRBuilder<> &IRB);
+
+  Value *makeAddAcquireOrderingTable(IRBuilder<> &IRB);
+  Value *makeAddReleaseOrderingTable(IRBuilder<> &IRB);
+};
+
+bool LibAtomicFunction(const Function &F) {
+  // This is a bit of a hack because TargetLibraryInfo is a function pass.
+  // The DFSan pass would need to be refactored to be function pass oriented
+  // (like MSan is) in order to fit together nicely with TargetLibraryInfo.
+  // We need this check to prevent them from being instrumented, or wrapped.
+  // Match on name and number of arguments.
+  if (!F.hasName() || F.isVarArg())
+    return false;
+  switch (F.arg_size()) {
+  case 4:
+    return F.getName() == "__atomic_load" || F.getName() == "__atomic_store";
+  case 5:
+    return F.getName() == "__atomic_exchange";
+  case 6:
+    return F.getName() == "__atomic_compare_exchange";
+  default:
+    return false;
+  }
+}
+
+} // end anonymous namespace
+
+DataFlowSanitizer::DataFlowSanitizer(
+    const std::vector<std::string> &ABIListFiles) {
+  std::vector<std::string> AllABIListFiles(std::move(ABIListFiles));
+  llvm::append_range(AllABIListFiles, ClABIListFiles);
+  // FIXME: should we propagate vfs::FileSystem to this constructor?
+  ABIList.set(
+      SpecialCaseList::createOrDie(AllABIListFiles, *vfs::getRealFileSystem()));
+
+  for (StringRef v : ClCombineTaintLookupTables)
+    CombineTaintLookupTableNames.insert(v);
+}
+
+TransformedFunction DataFlowSanitizer::getCustomFunctionType(FunctionType *T) {
+  SmallVector<Type *, 4> ArgTypes;
+
+  // Some parameters of the custom function being constructed are
+  // parameters of T.  Record the mapping from parameters of T to
+  // parameters of the custom function, so that parameter attributes
+  // at call sites can be updated.
+  std::vector<unsigned> ArgumentIndexMapping;
+  for (unsigned I = 0, E = T->getNumParams(); I != E; ++I) {
+    Type *ParamType = T->getParamType(I);
+    ArgumentIndexMapping.push_back(ArgTypes.size());
+    ArgTypes.push_back(ParamType);
+  }
+  for (unsigned I = 0, E = T->getNumParams(); I != E; ++I)
+    ArgTypes.push_back(PrimitiveShadowTy);
+  if (T->isVarArg())
+    ArgTypes.push_back(PrimitiveShadowPtrTy);
+  Type *RetType = T->getReturnType();
+  if (!RetType->isVoidTy())
+    ArgTypes.push_back(PrimitiveShadowPtrTy);
+
+  if (shouldTrackOrigins()) {
+    for (unsigned I = 0, E = T->getNumParams(); I != E; ++I)
+      ArgTypes.push_back(OriginTy);
+    if (T->isVarArg())
+      ArgTypes.push_back(OriginPtrTy);
+    if (!RetType->isVoidTy())
+      ArgTypes.push_back(OriginPtrTy);
+  }
+
+  return TransformedFunction(
+      T, FunctionType::get(T->getReturnType(), ArgTypes, T->isVarArg()),
+      ArgumentIndexMapping);
+}
+
+bool DataFlowSanitizer::isZeroShadow(Value *V) {
+  Type *T = V->getType();
+  if (!isa<ArrayType>(T) && !isa<StructType>(T)) {
+    if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
+      return CI->isZero();
+    return false;
+  }
+
+  return isa<ConstantAggregateZero>(V);
+}
+
+bool DataFlowSanitizer::hasLoadSizeForFastPath(uint64_t Size) {
+  uint64_t ShadowSize = Size * ShadowWidthBytes;
+  return ShadowSize % 8 == 0 || ShadowSize == 4;
+}
+
+bool DataFlowSanitizer::shouldTrackOrigins() {
+  static const bool ShouldTrackOrigins = ClTrackOrigins;
+  return ShouldTrackOrigins;
+}
+
+Constant *DataFlowSanitizer::getZeroShadow(Type *OrigTy) {
+  if (!isa<ArrayType>(OrigTy) && !isa<StructType>(OrigTy))
+    return ZeroPrimitiveShadow;
+  Type *ShadowTy = getShadowTy(OrigTy);
+  return ConstantAggregateZero::get(ShadowTy);
+}
+
+Constant *DataFlowSanitizer::getZeroShadow(Value *V) {
+  return getZeroShadow(V->getType());
+}
+
+static Value *expandFromPrimitiveShadowRecursive(
+    Value *Shadow, SmallVector<unsigned, 4> &Indices, Type *SubShadowTy,
+    Value *PrimitiveShadow, IRBuilder<> &IRB) {
+  if (!isa<ArrayType>(SubShadowTy) && !isa<StructType>(SubShadowTy))
+    return IRB.CreateInsertValue(Shadow, PrimitiveShadow, Indices);
+
+  if (ArrayType *AT = dyn_cast<ArrayType>(SubShadowTy)) {
+    for (unsigned Idx = 0; Idx < AT->getNumElements(); Idx++) {
+      Indices.push_back(Idx);
+      Shadow = expandFromPrimitiveShadowRecursive(
+          Shadow, Indices, AT->getElementType(), PrimitiveShadow, IRB);
+      Indices.pop_back();
+    }
+    return Shadow;
+  }
+
+  if (StructType *ST = dyn_cast<StructType>(SubShadowTy)) {
+    for (unsigned Idx = 0; Idx < ST->getNumElements(); Idx++) {
+      Indices.push_back(Idx);
+      Shadow = expandFromPrimitiveShadowRecursive(
+          Shadow, Indices, ST->getElementType(Idx), PrimitiveShadow, IRB);
+      Indices.pop_back();
+    }
+    return Shadow;
+  }
+  llvm_unreachable("Unexpected shadow type");
+}
+
+bool DFSanFunction::shouldInstrumentWithCall() {
+  return ClInstrumentWithCallThreshold >= 0 &&
+         NumOriginStores >= ClInstrumentWithCallThreshold;
+}
+
+Value *DFSanFunction::expandFromPrimitiveShadow(Type *T, Value *PrimitiveShadow,
+                                                Instruction *Pos) {
+  Type *ShadowTy = DFS.getShadowTy(T);
+
+  if (!isa<ArrayType>(ShadowTy) && !isa<StructType>(ShadowTy))
+    return PrimitiveShadow;
+
+  if (DFS.isZeroShadow(PrimitiveShadow))
+    return DFS.getZeroShadow(ShadowTy);
+
+  IRBuilder<> IRB(Pos);
+  SmallVector<unsigned, 4> Indices;
+  Value *Shadow = UndefValue::get(ShadowTy);
+  Shadow = expandFromPrimitiveShadowRecursive(Shadow, Indices, ShadowTy,
+                                              PrimitiveShadow, IRB);
+
+  // Caches the primitive shadow value that built the shadow value.
+  CachedCollapsedShadows[Shadow] = PrimitiveShadow;
+  return Shadow;
+}
+
+template <class AggregateType>
+Value *DFSanFunction::collapseAggregateShadow(AggregateType *AT, Value *Shadow,
+                                              IRBuilder<> &IRB) {
+  if (!AT->getNumElements())
+    return DFS.ZeroPrimitiveShadow;
+
+  Value *FirstItem = IRB.CreateExtractValue(Shadow, 0);
+  Value *Aggregator = collapseToPrimitiveShadow(FirstItem, IRB);
+
+  for (unsigned Idx = 1; Idx < AT->getNumElements(); Idx++) {
+    Value *ShadowItem = IRB.CreateExtractValue(Shadow, Idx);
+    Value *ShadowInner = collapseToPrimitiveShadow(ShadowItem, IRB);
+    Aggregator = IRB.CreateOr(Aggregator, ShadowInner);
+  }
+  return Aggregator;
+}
+
+Value *DFSanFunction::collapseToPrimitiveShadow(Value *Shadow,
+                                                IRBuilder<> &IRB) {
+  Type *ShadowTy = Shadow->getType();
+  if (!isa<ArrayType>(ShadowTy) && !isa<StructType>(ShadowTy))
+    return Shadow;
+  if (ArrayType *AT = dyn_cast<ArrayType>(ShadowTy))
+    return collapseAggregateShadow<>(AT, Shadow, IRB);
+  if (StructType *ST = dyn_cast<StructType>(ShadowTy))
+    return collapseAggregateShadow<>(ST, Shadow, IRB);
+  llvm_unreachable("Unexpected shadow type");
+}
+
+Value *DFSanFunction::collapseToPrimitiveShadow(Value *Shadow,
+                                                Instruction *Pos) {
+  Type *ShadowTy = Shadow->getType();
+  if (!isa<ArrayType>(ShadowTy) && !isa<StructType>(ShadowTy))
+    return Shadow;
+
+  // Checks if the cached collapsed shadow value dominates Pos.
+  Value *&CS = CachedCollapsedShadows[Shadow];
+  if (CS && DT.dominates(CS, Pos))
+    return CS;
+
+  IRBuilder<> IRB(Pos);
+  Value *PrimitiveShadow = collapseToPrimitiveShadow(Shadow, IRB);
+  // Caches the converted primitive shadow value.
+  CS = PrimitiveShadow;
+  return PrimitiveShadow;
+}
+
+void DFSanFunction::addConditionalCallbacksIfEnabled(Instruction &I,
+                                                     Value *Condition) {
+  if (!ClConditionalCallbacks) {
+    return;
+  }
+  IRBuilder<> IRB(&I);
+  Value *CondShadow = getShadow(Condition);
+  CallInst *CI;
+  if (DFS.shouldTrackOrigins()) {
+    Value *CondOrigin = getOrigin(Condition);
+    CI = IRB.CreateCall(DFS.DFSanConditionalCallbackOriginFn,
+                        {CondShadow, CondOrigin});
+  } else {
+    CI = IRB.CreateCall(DFS.DFSanConditionalCallbackFn, {CondShadow});
+  }
+  CI->addParamAttr(0, Attribute::ZExt);
+}
+
+void DFSanFunction::addReachesFunctionCallbacksIfEnabled(IRBuilder<> &IRB,
+                                                         Instruction &I,
+                                                         Value *Data) {
+  if (!ClReachesFunctionCallbacks) {
+    return;
+  }
+  const DebugLoc &dbgloc = I.getDebugLoc();
+  Value *DataShadow = collapseToPrimitiveShadow(getShadow(Data), IRB);
+  ConstantInt *CILine;
+  llvm::Value *FilePathPtr;
+
+  if (dbgloc.get() == nullptr) {
+    CILine = llvm::ConstantInt::get(I.getContext(), llvm::APInt(32, 0));
+    FilePathPtr = IRB.CreateGlobalStringPtr(
+        I.getFunction()->getParent()->getSourceFileName());
+  } else {
+    CILine = llvm::ConstantInt::get(I.getContext(),
+                                    llvm::APInt(32, dbgloc.getLine()));
+    FilePathPtr =
+        IRB.CreateGlobalStringPtr(dbgloc->getFilename());
+  }
+
+  llvm::Value *FunctionNamePtr =
+      IRB.CreateGlobalStringPtr(I.getFunction()->getName());
+
+  CallInst *CB;
+  std::vector<Value *> args;
+
+  if (DFS.shouldTrackOrigins()) {
+    Value *DataOrigin = getOrigin(Data);
+    args = { DataShadow, DataOrigin, FilePathPtr, CILine, FunctionNamePtr };
+    CB = IRB.CreateCall(DFS.DFSanReachesFunctionCallbackOriginFn, args);
+  } else {
+    args = { DataShadow, FilePathPtr, CILine, FunctionNamePtr };
+    CB = IRB.CreateCall(DFS.DFSanReachesFunctionCallbackFn, args);
+  }
+  CB->addParamAttr(0, Attribute::ZExt);
+  CB->setDebugLoc(dbgloc);
+}
+
+Type *DataFlowSanitizer::getShadowTy(Type *OrigTy) {
+  if (!OrigTy->isSized())
+    return PrimitiveShadowTy;
+  if (isa<IntegerType>(OrigTy))
+    return PrimitiveShadowTy;
+  if (isa<VectorType>(OrigTy))
+    return PrimitiveShadowTy;
+  if (ArrayType *AT = dyn_cast<ArrayType>(OrigTy))
+    return ArrayType::get(getShadowTy(AT->getElementType()),
+                          AT->getNumElements());
+  if (StructType *ST = dyn_cast<StructType>(OrigTy)) {
+    SmallVector<Type *, 4> Elements;
+    for (unsigned I = 0, N = ST->getNumElements(); I < N; ++I)
+      Elements.push_back(getShadowTy(ST->getElementType(I)));
+    return StructType::get(*Ctx, Elements);
+  }
+  return PrimitiveShadowTy;
+}
+
+Type *DataFlowSanitizer::getShadowTy(Value *V) {
+  return getShadowTy(V->getType());
+}
+
+bool DataFlowSanitizer::initializeModule(Module &M) {
+  Triple TargetTriple(M.getTargetTriple());
+  const DataLayout &DL = M.getDataLayout();
+
+  if (TargetTriple.getOS() != Triple::Linux)
+    report_fatal_error("unsupported operating system");
+  switch (TargetTriple.getArch()) {
+  case Triple::aarch64:
+    MapParams = &Linux_AArch64_MemoryMapParams;
+    break;
+  case Triple::x86_64:
+    MapParams = &Linux_X86_64_MemoryMapParams;
+    break;
+  default:
+    report_fatal_error("unsupported architecture");
+  }
+
+  Mod = &M;
+  Ctx = &M.getContext();
+  Int8Ptr = Type::getInt8PtrTy(*Ctx);
+  OriginTy = IntegerType::get(*Ctx, OriginWidthBits);
+  OriginPtrTy = PointerType::getUnqual(OriginTy);
+  PrimitiveShadowTy = IntegerType::get(*Ctx, ShadowWidthBits);
+  PrimitiveShadowPtrTy = PointerType::getUnqual(PrimitiveShadowTy);
+  IntptrTy = DL.getIntPtrType(*Ctx);
+  ZeroPrimitiveShadow = ConstantInt::getSigned(PrimitiveShadowTy, 0);
+  ZeroOrigin = ConstantInt::getSigned(OriginTy, 0);
+
+  Type *DFSanUnionLoadArgs[2] = {PrimitiveShadowPtrTy, IntptrTy};
+  DFSanUnionLoadFnTy = FunctionType::get(PrimitiveShadowTy, DFSanUnionLoadArgs,
+                                         /*isVarArg=*/false);
+  Type *DFSanLoadLabelAndOriginArgs[2] = {Int8Ptr, IntptrTy};
+  DFSanLoadLabelAndOriginFnTy =
+      FunctionType::get(IntegerType::get(*Ctx, 64), DFSanLoadLabelAndOriginArgs,
+                        /*isVarArg=*/false);
+  DFSanUnimplementedFnTy = FunctionType::get(
+      Type::getVoidTy(*Ctx), Type::getInt8PtrTy(*Ctx), /*isVarArg=*/false);
+  Type *DFSanWrapperExternWeakNullArgs[2] = {Int8Ptr, Int8Ptr};
+  DFSanWrapperExternWeakNullFnTy =
+      FunctionType::get(Type::getVoidTy(*Ctx), DFSanWrapperExternWeakNullArgs,
+                        /*isVarArg=*/false);
+  Type *DFSanSetLabelArgs[4] = {PrimitiveShadowTy, OriginTy,
+                                Type::getInt8PtrTy(*Ctx), IntptrTy};
+  DFSanSetLabelFnTy = FunctionType::get(Type::getVoidTy(*Ctx),
+                                        DFSanSetLabelArgs, /*isVarArg=*/false);
+  DFSanNonzeroLabelFnTy = FunctionType::get(Type::getVoidTy(*Ctx), std::nullopt,
+                                            /*isVarArg=*/false);
+  DFSanVarargWrapperFnTy = FunctionType::get(
+      Type::getVoidTy(*Ctx), Type::getInt8PtrTy(*Ctx), /*isVarArg=*/false);
+  DFSanConditionalCallbackFnTy =
+      FunctionType::get(Type::getVoidTy(*Ctx), PrimitiveShadowTy,
+                        /*isVarArg=*/false);
+  Type *DFSanConditionalCallbackOriginArgs[2] = {PrimitiveShadowTy, OriginTy};
+  DFSanConditionalCallbackOriginFnTy = FunctionType::get(
+      Type::getVoidTy(*Ctx), DFSanConditionalCallbackOriginArgs,
+      /*isVarArg=*/false);
+  Type *DFSanReachesFunctionCallbackArgs[4] = {PrimitiveShadowTy, Int8Ptr,
+                                               OriginTy, Int8Ptr};
+  DFSanReachesFunctionCallbackFnTy =
+      FunctionType::get(Type::getVoidTy(*Ctx), DFSanReachesFunctionCallbackArgs,
+                        /*isVarArg=*/false);
+  Type *DFSanReachesFunctionCallbackOriginArgs[5] = {
+      PrimitiveShadowTy, OriginTy, Int8Ptr, OriginTy, Int8Ptr};
+  DFSanReachesFunctionCallbackOriginFnTy = FunctionType::get(
+      Type::getVoidTy(*Ctx), DFSanReachesFunctionCallbackOriginArgs,
+      /*isVarArg=*/false);
+  DFSanCmpCallbackFnTy =
+      FunctionType::get(Type::getVoidTy(*Ctx), PrimitiveShadowTy,
+                        /*isVarArg=*/false);
+  DFSanChainOriginFnTy =
+      FunctionType::get(OriginTy, OriginTy, /*isVarArg=*/false);
+  Type *DFSanChainOriginIfTaintedArgs[2] = {PrimitiveShadowTy, OriginTy};
+  DFSanChainOriginIfTaintedFnTy = FunctionType::get(
+      OriginTy, DFSanChainOriginIfTaintedArgs, /*isVarArg=*/false);
+  Type *DFSanMaybeStoreOriginArgs[4] = {IntegerType::get(*Ctx, ShadowWidthBits),
+                                        Int8Ptr, IntptrTy, OriginTy};
+  DFSanMaybeStoreOriginFnTy = FunctionType::get(
+      Type::getVoidTy(*Ctx), DFSanMaybeStoreOriginArgs, /*isVarArg=*/false);
+  Type *DFSanMemOriginTransferArgs[3] = {Int8Ptr, Int8Ptr, IntptrTy};
+  DFSanMemOriginTransferFnTy = FunctionType::get(
+      Type::getVoidTy(*Ctx), DFSanMemOriginTransferArgs, /*isVarArg=*/false);
+  Type *DFSanMemShadowOriginTransferArgs[3] = {Int8Ptr, Int8Ptr, IntptrTy};
+  DFSanMemShadowOriginTransferFnTy =
+      FunctionType::get(Type::getVoidTy(*Ctx), DFSanMemShadowOriginTransferArgs,
+                        /*isVarArg=*/false);
+  Type *DFSanMemShadowOriginConditionalExchangeArgs[5] = {
+      IntegerType::get(*Ctx, 8), Int8Ptr, Int8Ptr, Int8Ptr, IntptrTy};
+  DFSanMemShadowOriginConditionalExchangeFnTy = FunctionType::get(
+      Type::getVoidTy(*Ctx), DFSanMemShadowOriginConditionalExchangeArgs,
+      /*isVarArg=*/false);
+  Type *DFSanLoadStoreCallbackArgs[2] = {PrimitiveShadowTy, Int8Ptr};
+  DFSanLoadStoreCallbackFnTy =
+      FunctionType::get(Type::getVoidTy(*Ctx), DFSanLoadStoreCallbackArgs,
+                        /*isVarArg=*/false);
+  Type *DFSanMemTransferCallbackArgs[2] = {PrimitiveShadowPtrTy, IntptrTy};
+  DFSanMemTransferCallbackFnTy =
+      FunctionType::get(Type::getVoidTy(*Ctx), DFSanMemTransferCallbackArgs,
+                        /*isVarArg=*/false);
+
+  ColdCallWeights = MDBuilder(*Ctx).createBranchWeights(1, 1000);
+  OriginStoreWeights = MDBuilder(*Ctx).createBranchWeights(1, 1000);
+  return true;
+}
+
+bool DataFlowSanitizer::isInstrumented(const Function *F) {
+  return !ABIList.isIn(*F, "uninstrumented");
+}
+
+bool DataFlowSanitizer::isInstrumented(const GlobalAlias *GA) {
+  return !ABIList.isIn(*GA, "uninstrumented");
+}
+
+bool DataFlowSanitizer::isForceZeroLabels(const Function *F) {
+  return ABIList.isIn(*F, "force_zero_labels");
+}
+
+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::addGlobalNameSuffix(GlobalValue *GV) {
+  std::string GVName = std::string(GV->getName()), Suffix = ".dfsan";
+  GV->setName(GVName + Suffix);
+
+  // 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 " + GVName + Suffix + ",");
+    Pos = Asm.find("@");
+
+    if (Pos == std::string::npos)
+      report_fatal_error(Twine("unsupported .symver: ", Asm));
+
+    Asm.replace(Pos, 1, Suffix + "@");
+    GV->getParent()->setModuleInlineAsm(Asm);
+  }
+}
+
+void DataFlowSanitizer::buildExternWeakCheckIfNeeded(IRBuilder<> &IRB,
+                                                     Function *F) {
+  // If the function we are wrapping was ExternWeak, it may be null.
+  // The original code before calling this wrapper may have checked for null,
+  // but replacing with a known-to-not-be-null wrapper can break this check.
+  // When replacing uses of the extern weak function with the wrapper we try
+  // to avoid replacing uses in conditionals, but this is not perfect.
+  // In the case where we fail, and accidentally optimize out a null check
+  // for a extern weak function, add a check here to help identify the issue.
+  if (GlobalValue::isExternalWeakLinkage(F->getLinkage())) {
+    std::vector<Value *> Args;
+    Args.push_back(IRB.CreatePointerCast(F, IRB.getInt8PtrTy()));
+    Args.push_back(IRB.CreateGlobalStringPtr(F->getName()));
+    IRB.CreateCall(DFSanWrapperExternWeakNullFn, Args);
+  }
+}
+
+Function *
+DataFlowSanitizer::buildWrapperFunction(Function *F, StringRef NewFName,
+                                        GlobalValue::LinkageTypes NewFLink,
+                                        FunctionType *NewFT) {
+  FunctionType *FT = F->getFunctionType();
+  Function *NewF = Function::Create(NewFT, NewFLink, F->getAddressSpace(),
+                                    NewFName, F->getParent());
+  NewF->copyAttributesFrom(F);
+  NewF->removeRetAttrs(
+      AttributeFuncs::typeIncompatible(NewFT->getReturnType()));
+
+  BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", NewF);
+  if (F->isVarArg()) {
+    NewF->removeFnAttr("split-stack");
+    CallInst::Create(DFSanVarargWrapperFn,
+                     IRBuilder<>(BB).CreateGlobalStringPtr(F->getName()), "",
+                     BB);
+    new UnreachableInst(*Ctx, BB);
+  } else {
+    auto ArgIt = pointer_iterator<Argument *>(NewF->arg_begin());
+    std::vector<Value *> Args(ArgIt, ArgIt + FT->getNumParams());
+
+    CallInst *CI = CallInst::Create(F, Args, "", BB);
+    if (FT->getReturnType()->isVoidTy())
+      ReturnInst::Create(*Ctx, BB);
+    else
+      ReturnInst::Create(*Ctx, CI, BB);
+  }
+
+  return NewF;
+}
+
+// Initialize DataFlowSanitizer runtime functions and declare them in the module
+void DataFlowSanitizer::initializeRuntimeFunctions(Module &M) {
+  LLVMContext &C = M.getContext();
+  {
+    AttributeList AL;
+    AL = AL.addFnAttribute(C, Attribute::NoUnwind);
+    AL = AL.addFnAttribute(
+        C, Attribute::getWithMemoryEffects(C, MemoryEffects::readOnly()));
+    AL = AL.addRetAttribute(C, Attribute::ZExt);
+    DFSanUnionLoadFn =
+        Mod->getOrInsertFunction("__dfsan_union_load", DFSanUnionLoadFnTy, AL);
+  }
+  {
+    AttributeList AL;
+    AL = AL.addFnAttribute(C, Attribute::NoUnwind);
+    AL = AL.addFnAttribute(
+        C, Attribute::getWithMemoryEffects(C, MemoryEffects::readOnly()));
+    AL = AL.addRetAttribute(C, Attribute::ZExt);
+    DFSanLoadLabelAndOriginFn = Mod->getOrInsertFunction(
+        "__dfsan_load_label_and_origin", DFSanLoadLabelAndOriginFnTy, AL);
+  }
+  DFSanUnimplementedFn =
+      Mod->getOrInsertFunction("__dfsan_unimplemented", DFSanUnimplementedFnTy);
+  DFSanWrapperExternWeakNullFn = Mod->getOrInsertFunction(
+      "__dfsan_wrapper_extern_weak_null", DFSanWrapperExternWeakNullFnTy);
+  {
+    AttributeList AL;
+    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
+    AL = AL.addParamAttribute(M.getContext(), 1, Attribute::ZExt);
+    DFSanSetLabelFn =
+        Mod->getOrInsertFunction("__dfsan_set_label", DFSanSetLabelFnTy, AL);
+  }
+  DFSanNonzeroLabelFn =
+      Mod->getOrInsertFunction("__dfsan_nonzero_label", DFSanNonzeroLabelFnTy);
+  DFSanVarargWrapperFn = Mod->getOrInsertFunction("__dfsan_vararg_wrapper",
+                                                  DFSanVarargWrapperFnTy);
+  {
+    AttributeList AL;
+    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
+    AL = AL.addRetAttribute(M.getContext(), Attribute::ZExt);
+    DFSanChainOriginFn = Mod->getOrInsertFunction("__dfsan_chain_origin",
+                                                  DFSanChainOriginFnTy, AL);
+  }
+  {
+    AttributeList AL;
+    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
+    AL = AL.addParamAttribute(M.getContext(), 1, Attribute::ZExt);
+    AL = AL.addRetAttribute(M.getContext(), Attribute::ZExt);
+    DFSanChainOriginIfTaintedFn = Mod->getOrInsertFunction(
+        "__dfsan_chain_origin_if_tainted", DFSanChainOriginIfTaintedFnTy, AL);
+  }
+  DFSanMemOriginTransferFn = Mod->getOrInsertFunction(
+      "__dfsan_mem_origin_transfer", DFSanMemOriginTransferFnTy);
+
+  DFSanMemShadowOriginTransferFn = Mod->getOrInsertFunction(
+      "__dfsan_mem_shadow_origin_transfer", DFSanMemShadowOriginTransferFnTy);
+
+  DFSanMemShadowOriginConditionalExchangeFn =
+      Mod->getOrInsertFunction("__dfsan_mem_shadow_origin_conditional_exchange",
+                               DFSanMemShadowOriginConditionalExchangeFnTy);
+
+  {
+    AttributeList AL;
+    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
+    AL = AL.addParamAttribute(M.getContext(), 3, Attribute::ZExt);
+    DFSanMaybeStoreOriginFn = Mod->getOrInsertFunction(
+        "__dfsan_maybe_store_origin", DFSanMaybeStoreOriginFnTy, AL);
+  }
+
+  DFSanRuntimeFunctions.insert(
+      DFSanUnionLoadFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanLoadLabelAndOriginFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanUnimplementedFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanWrapperExternWeakNullFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanSetLabelFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanNonzeroLabelFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanVarargWrapperFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanLoadCallbackFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanStoreCallbackFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanMemTransferCallbackFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanConditionalCallbackFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanConditionalCallbackOriginFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanReachesFunctionCallbackFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanReachesFunctionCallbackOriginFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanCmpCallbackFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanChainOriginFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanChainOriginIfTaintedFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanMemOriginTransferFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanMemShadowOriginTransferFn.getCallee()->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanMemShadowOriginConditionalExchangeFn.getCallee()
+          ->stripPointerCasts());
+  DFSanRuntimeFunctions.insert(
+      DFSanMaybeStoreOriginFn.getCallee()->stripPointerCasts());
+}
+
+// Initializes event callback functions and declare them in the module
+void DataFlowSanitizer::initializeCallbackFunctions(Module &M) {
+  {
+    AttributeList AL;
+    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
+    DFSanLoadCallbackFn = Mod->getOrInsertFunction(
+        "__dfsan_load_callback", DFSanLoadStoreCallbackFnTy, AL);
+  }
+  {
+    AttributeList AL;
+    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
+    DFSanStoreCallbackFn = Mod->getOrInsertFunction(
+        "__dfsan_store_callback", DFSanLoadStoreCallbackFnTy, AL);
+  }
+  DFSanMemTransferCallbackFn = Mod->getOrInsertFunction(
+      "__dfsan_mem_transfer_callback", DFSanMemTransferCallbackFnTy);
+  {
+    AttributeList AL;
+    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
+    DFSanCmpCallbackFn = Mod->getOrInsertFunction("__dfsan_cmp_callback",
+                                                  DFSanCmpCallbackFnTy, AL);
+  }
+  {
+    AttributeList AL;
+    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
+    DFSanConditionalCallbackFn = Mod->getOrInsertFunction(
+        "__dfsan_conditional_callback", DFSanConditionalCallbackFnTy, AL);
+  }
+  {
+    AttributeList AL;
+    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
+    DFSanConditionalCallbackOriginFn =
+        Mod->getOrInsertFunction("__dfsan_conditional_callback_origin",
+                                 DFSanConditionalCallbackOriginFnTy, AL);
+  }
+  {
+    AttributeList AL;
+    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
+    DFSanReachesFunctionCallbackFn =
+        Mod->getOrInsertFunction("__dfsan_reaches_function_callback",
+                                 DFSanReachesFunctionCallbackFnTy, AL);
+  }
+  {
+    AttributeList AL;
+    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
+    DFSanReachesFunctionCallbackOriginFn =
+        Mod->getOrInsertFunction("__dfsan_reaches_function_callback_origin",
+                                 DFSanReachesFunctionCallbackOriginFnTy, AL);
+  }
+}
+
+bool DataFlowSanitizer::runImpl(
+    Module &M, llvm::function_ref<TargetLibraryInfo &(Function &)> GetTLI) {
+  initializeModule(M);
+
+  if (ABIList.isIn(M, "skip"))
+    return false;
+
+  const unsigned InitialGlobalSize = M.global_size();
+  const unsigned InitialModuleSize = M.size();
+
+  bool Changed = false;
+
+  auto GetOrInsertGlobal = [this, &Changed](StringRef Name,
+                                            Type *Ty) -> Constant * {
+    Constant *C = Mod->getOrInsertGlobal(Name, Ty);
+    if (GlobalVariable *G = dyn_cast<GlobalVariable>(C)) {
+      Changed |= G->getThreadLocalMode() != GlobalVariable::InitialExecTLSModel;
+      G->setThreadLocalMode(GlobalVariable::InitialExecTLSModel);
+    }
+    return C;
+  };
+
+  // These globals must be kept in sync with the ones in dfsan.cpp.
+  ArgTLS =
+      GetOrInsertGlobal("__dfsan_arg_tls",
+                        ArrayType::get(Type::getInt64Ty(*Ctx), ArgTLSSize / 8));
+  RetvalTLS = GetOrInsertGlobal(
+      "__dfsan_retval_tls",
+      ArrayType::get(Type::getInt64Ty(*Ctx), RetvalTLSSize / 8));
+  ArgOriginTLSTy = ArrayType::get(OriginTy, NumOfElementsInArgOrgTLS);
+  ArgOriginTLS = GetOrInsertGlobal("__dfsan_arg_origin_tls", ArgOriginTLSTy);
+  RetvalOriginTLS = GetOrInsertGlobal("__dfsan_retval_origin_tls", OriginTy);
+
+  (void)Mod->getOrInsertGlobal("__dfsan_track_origins", OriginTy, [&] {
+    Changed = true;
+    return new GlobalVariable(
+        M, OriginTy, true, GlobalValue::WeakODRLinkage,
+        ConstantInt::getSigned(OriginTy,
+                               shouldTrackOrigins() ? ClTrackOrigins : 0),
+        "__dfsan_track_origins");
+  });
+
+  initializeCallbackFunctions(M);
+  initializeRuntimeFunctions(M);
+
+  std::vector<Function *> FnsToInstrument;
+  SmallPtrSet<Function *, 2> FnsWithNativeABI;
+  SmallPtrSet<Function *, 2> FnsWithForceZeroLabel;
+  SmallPtrSet<Constant *, 1> PersonalityFns;
+  for (Function &F : M)
+    if (!F.isIntrinsic() && !DFSanRuntimeFunctions.contains(&F) &&
+        !LibAtomicFunction(F)) {
+      FnsToInstrument.push_back(&F);
+      if (F.hasPersonalityFn())
+        PersonalityFns.insert(F.getPersonalityFn()->stripPointerCasts());
+    }
+
+  if (ClIgnorePersonalityRoutine) {
+    for (auto *C : PersonalityFns) {
+      assert(isa<Function>(C) && "Personality routine is not a function!");
+      Function *F = cast<Function>(C);
+      if (!isInstrumented(F))
+        llvm::erase_value(FnsToInstrument, F);
+    }
+  }
+
+  // Give function aliases prefixes when necessary, and build wrappers where the
+  // instrumentedness is inconsistent.
+  for (GlobalAlias &GA : llvm::make_early_inc_range(M.aliases())) {
+    // Don't stop on weak.  We assume people aren't playing games with the
+    // instrumentedness of overridden weak aliases.
+    auto *F = dyn_cast<Function>(GA.getAliaseeObject());
+    if (!F)
+      continue;
+
+    bool GAInst = isInstrumented(&GA), FInst = isInstrumented(F);
+    if (GAInst && FInst) {
+      addGlobalNameSuffix(&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);
+    }
+  }
+
+  // TODO: This could be more precise.
+  ReadOnlyNoneAttrs.addAttribute(Attribute::Memory);
+
+  // 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 FI = FnsToInstrument.begin(),
+                                         FE = FnsToInstrument.end();
+       FI != FE; ++FI) {
+    Function &F = **FI;
+    FunctionType *FT = F.getFunctionType();
+
+    bool IsZeroArgsVoidRet = (FT->getNumParams() == 0 && !FT->isVarArg() &&
+                              FT->getReturnType()->isVoidTy());
+
+    if (isInstrumented(&F)) {
+      if (isForceZeroLabels(&F))
+        FnsWithForceZeroLabel.insert(&F);
+
+      // Instrumented functions get a '.dfsan' suffix.  This allows us to more
+      // easily identify cases of mismatching ABIs. This naming scheme is
+      // mangling-compatible (see Itanium ABI), using a vendor-specific suffix.
+      addGlobalNameSuffix(&F);
+    } 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.
+
+      // If the function being wrapped has local linkage, then preserve the
+      // function's linkage in the wrapper function.
+      GlobalValue::LinkageTypes WrapperLinkage =
+          F.hasLocalLinkage() ? F.getLinkage()
+                              : GlobalValue::LinkOnceODRLinkage;
+
+      Function *NewF = buildWrapperFunction(
+          &F,
+          (shouldTrackOrigins() ? std::string("dfso$") : std::string("dfsw$")) +
+              std::string(F.getName()),
+          WrapperLinkage, FT);
+      NewF->removeFnAttrs(ReadOnlyNoneAttrs);
+
+      Value *WrappedFnCst =
+          ConstantExpr::getBitCast(NewF, PointerType::getUnqual(FT));
+
+      // Extern weak functions can sometimes be null at execution time.
+      // Code will sometimes check if an extern weak function is null.
+      // This could look something like:
+      //   declare extern_weak i8 @my_func(i8)
+      //   br i1 icmp ne (i8 (i8)* @my_func, i8 (i8)* null), label %use_my_func,
+      //   label %avoid_my_func
+      // The @"dfsw$my_func" wrapper is never null, so if we replace this use
+      // in the comparison, the icmp will simplify to false and we have
+      // accidentally optimized away a null check that is necessary.
+      // This can lead to a crash when the null extern_weak my_func is called.
+      //
+      // To prevent (the most common pattern of) this problem,
+      // do not replace uses in comparisons with the wrapper.
+      // We definitely want to replace uses in call instructions.
+      // Other uses (e.g. store the function address somewhere) might be
+      // called or compared or both - this case may not be handled correctly.
+      // We will default to replacing with wrapper in cases we are unsure.
+      auto IsNotCmpUse = [](Use &U) -> bool {
+        User *Usr = U.getUser();
+        if (ConstantExpr *CE = dyn_cast<ConstantExpr>(Usr)) {
+          // This is the most common case for icmp ne null
+          if (CE->getOpcode() == Instruction::ICmp) {
+            return false;
+          }
+        }
+        if (Instruction *I = dyn_cast<Instruction>(Usr)) {
+          if (I->getOpcode() == Instruction::ICmp) {
+            return false;
+          }
+        }
+        return true;
+      };
+      F.replaceUsesWithIf(WrappedFnCst, IsNotCmpUse);
+
+      UnwrappedFnMap[WrappedFnCst] = &F;
+      *FI = 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 = FI - FnsToInstrument.begin(),
+               Count = FE - FnsToInstrument.begin();
+        FnsToInstrument.push_back(&F);
+        FI = FnsToInstrument.begin() + N;
+        FE = FnsToInstrument.begin() + Count;
+      }
+      // Hopefully, nobody will try to indirectly call a vararg
+      // function... yet.
+    } else if (FT->isVarArg()) {
+      UnwrappedFnMap[&F] = &F;
+      *FI = nullptr;
+    }
+  }
+
+  for (Function *F : FnsToInstrument) {
+    if (!F || F->isDeclaration())
+      continue;
+
+    removeUnreachableBlocks(*F);
+
+    DFSanFunction DFSF(*this, F, FnsWithNativeABI.count(F),
+                       FnsWithForceZeroLabel.count(F), GetTLI(*F));
+
+    if (ClReachesFunctionCallbacks) {
+      // Add callback for arguments reaching this function.
+      for (auto &FArg : F->args()) {
+        Instruction *Next = &F->getEntryBlock().front();
+        Value *FArgShadow = DFSF.getShadow(&FArg);
+        if (isZeroShadow(FArgShadow))
+          continue;
+        if (Instruction *FArgShadowInst = dyn_cast<Instruction>(FArgShadow)) {
+          Next = FArgShadowInst->getNextNode();
+        }
+        if (shouldTrackOrigins()) {
+          if (Instruction *Origin =
+                  dyn_cast<Instruction>(DFSF.getOrigin(&FArg))) {
+            // Ensure IRB insertion point is after loads for shadow and origin.
+            Instruction *OriginNext = Origin->getNextNode();
+            if (Next->comesBefore(OriginNext)) {
+              Next = OriginNext;
+            }
+          }
+        }
+        IRBuilder<> IRB(Next);
+        DFSF.addReachesFunctionCallbacksIfEnabled(IRB, *Next, &FArg);
+      }
+    }
+
+    // DFSanVisitor may create new basic blocks, which confuses df_iterator.
+    // Build a copy of the list before iterating over it.
+    SmallVector<BasicBlock *, 4> BBList(depth_first(&F->getEntryBlock()));
+
+    for (BasicBlock *BB : BBList) {
+      Instruction *Inst = &BB->front();
+      while (true) {
+        // DFSanVisitor may split the current basic block, changing the current
+        // instruction's next pointer and moving the next instruction to the
+        // tail block from which we should continue.
+        Instruction *Next = Inst->getNextNode();
+        // DFSanVisitor may delete Inst, so keep track of whether it was a
+        // terminator.
+        bool IsTerminator = Inst->isTerminator();
+        if (!DFSF.SkipInsts.count(Inst))
+          DFSanVisitor(DFSF).visit(Inst);
+        if (IsTerminator)
+          break;
+        Inst = Next;
+      }
+    }
+
+    // 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 (DFSanFunction::PHIFixupElement &P : DFSF.PHIFixups) {
+      for (unsigned Val = 0, N = P.Phi->getNumIncomingValues(); Val != N;
+           ++Val) {
+        P.ShadowPhi->setIncomingValue(
+            Val, DFSF.getShadow(P.Phi->getIncomingValue(Val)));
+        if (P.OriginPhi)
+          P.OriginPhi->setIncomingValue(
+              Val, DFSF.getOrigin(P.Phi->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 (Value *V : DFSF.NonZeroChecks) {
+        Instruction *Pos;
+        if (Instruction *I = dyn_cast<Instruction>(V))
+          Pos = I->getNextNode();
+        else
+          Pos = &DFSF.F->getEntryBlock().front();
+        while (isa<PHINode>(Pos) || isa<AllocaInst>(Pos))
+          Pos = Pos->getNextNode();
+        IRBuilder<> IRB(Pos);
+        Value *PrimitiveShadow = DFSF.collapseToPrimitiveShadow(V, Pos);
+        Value *Ne =
+            IRB.CreateICmpNE(PrimitiveShadow, DFSF.DFS.ZeroPrimitiveShadow);
+        BranchInst *BI = cast<BranchInst>(SplitBlockAndInsertIfThen(
+            Ne, Pos, /*Unreachable=*/false, ColdCallWeights));
+        IRBuilder<> ThenIRB(BI);
+        ThenIRB.CreateCall(DFSF.DFS.DFSanNonzeroLabelFn, {});
+      }
+    }
+  }
+
+  return Changed || !FnsToInstrument.empty() ||
+         M.global_size() != InitialGlobalSize || M.size() != InitialModuleSize;
+}
+
+Value *DFSanFunction::getArgTLS(Type *T, unsigned ArgOffset, IRBuilder<> &IRB) {
+  Value *Base = IRB.CreatePointerCast(DFS.ArgTLS, DFS.IntptrTy);
+  if (ArgOffset)
+    Base = IRB.CreateAdd(Base, ConstantInt::get(DFS.IntptrTy, ArgOffset));
+  return IRB.CreateIntToPtr(Base, PointerType::get(DFS.getShadowTy(T), 0),
+                            "_dfsarg");
+}
+
+Value *DFSanFunction::getRetvalTLS(Type *T, IRBuilder<> &IRB) {
+  return IRB.CreatePointerCast(
+      DFS.RetvalTLS, PointerType::get(DFS.getShadowTy(T), 0), "_dfsret");
+}
+
+Value *DFSanFunction::getRetvalOriginTLS() { return DFS.RetvalOriginTLS; }
+
+Value *DFSanFunction::getArgOriginTLS(unsigned ArgNo, IRBuilder<> &IRB) {
+  return IRB.CreateConstGEP2_64(DFS.ArgOriginTLSTy, DFS.ArgOriginTLS, 0, ArgNo,
+                                "_dfsarg_o");
+}
+
+Value *DFSanFunction::getOrigin(Value *V) {
+  assert(DFS.shouldTrackOrigins());
+  if (!isa<Argument>(V) && !isa<Instruction>(V))
+    return DFS.ZeroOrigin;
+  Value *&Origin = ValOriginMap[V];
+  if (!Origin) {
+    if (Argument *A = dyn_cast<Argument>(V)) {
+      if (IsNativeABI)
+        return DFS.ZeroOrigin;
+      if (A->getArgNo() < DFS.NumOfElementsInArgOrgTLS) {
+        Instruction *ArgOriginTLSPos = &*F->getEntryBlock().begin();
+        IRBuilder<> IRB(ArgOriginTLSPos);
+        Value *ArgOriginPtr = getArgOriginTLS(A->getArgNo(), IRB);
+        Origin = IRB.CreateLoad(DFS.OriginTy, ArgOriginPtr);
+      } else {
+        // Overflow
+        Origin = DFS.ZeroOrigin;
+      }
+    } else {
+      Origin = DFS.ZeroOrigin;
+    }
+  }
+  return Origin;
+}
+
+void DFSanFunction::setOrigin(Instruction *I, Value *Origin) {
+  if (!DFS.shouldTrackOrigins())
+    return;
+  assert(!ValOriginMap.count(I));
+  assert(Origin->getType() == DFS.OriginTy);
+  ValOriginMap[I] = Origin;
+}
+
+Value *DFSanFunction::getShadowForTLSArgument(Argument *A) {
+  unsigned ArgOffset = 0;
+  const DataLayout &DL = F->getParent()->getDataLayout();
+  for (auto &FArg : F->args()) {
+    if (!FArg.getType()->isSized()) {
+      if (A == &FArg)
+        break;
+      continue;
+    }
+
+    unsigned Size = DL.getTypeAllocSize(DFS.getShadowTy(&FArg));
+    if (A != &FArg) {
+      ArgOffset += alignTo(Size, ShadowTLSAlignment);
+      if (ArgOffset > ArgTLSSize)
+        break; // ArgTLS overflows, uses a zero shadow.
+      continue;
+    }
+
+    if (ArgOffset + Size > ArgTLSSize)
+      break; // ArgTLS overflows, uses a zero shadow.
+
+    Instruction *ArgTLSPos = &*F->getEntryBlock().begin();
+    IRBuilder<> IRB(ArgTLSPos);
+    Value *ArgShadowPtr = getArgTLS(FArg.getType(), ArgOffset, IRB);
+    return IRB.CreateAlignedLoad(DFS.getShadowTy(&FArg), ArgShadowPtr,
+                                 ShadowTLSAlignment);
+  }
+
+  return DFS.getZeroShadow(A);
+}
+
+Value *DFSanFunction::getShadow(Value *V) {
+  if (!isa<Argument>(V) && !isa<Instruction>(V))
+    return DFS.getZeroShadow(V);
+  if (IsForceZeroLabels)
+    return DFS.getZeroShadow(V);
+  Value *&Shadow = ValShadowMap[V];
+  if (!Shadow) {
+    if (Argument *A = dyn_cast<Argument>(V)) {
+      if (IsNativeABI)
+        return DFS.getZeroShadow(V);
+      Shadow = getShadowForTLSArgument(A);
+      NonZeroChecks.push_back(Shadow);
+    } else {
+      Shadow = DFS.getZeroShadow(V);
+    }
+  }
+  return Shadow;
+}
+
+void DFSanFunction::setShadow(Instruction *I, Value *Shadow) {
+  assert(!ValShadowMap.count(I));
+  ValShadowMap[I] = Shadow;
+}
+
+/// Compute the integer shadow offset that corresponds to a given
+/// application address.
+///
+/// Offset = (Addr & ~AndMask) ^ XorMask
+Value *DataFlowSanitizer::getShadowOffset(Value *Addr, IRBuilder<> &IRB) {
+  assert(Addr != RetvalTLS && "Reinstrumenting?");
+  Value *OffsetLong = IRB.CreatePointerCast(Addr, IntptrTy);
+
+  uint64_t AndMask = MapParams->AndMask;
+  if (AndMask)
+    OffsetLong =
+        IRB.CreateAnd(OffsetLong, ConstantInt::get(IntptrTy, ~AndMask));
+
+  uint64_t XorMask = MapParams->XorMask;
+  if (XorMask)
+    OffsetLong = IRB.CreateXor(OffsetLong, ConstantInt::get(IntptrTy, XorMask));
+  return OffsetLong;
+}
+
+std::pair<Value *, Value *>
+DataFlowSanitizer::getShadowOriginAddress(Value *Addr, Align InstAlignment,
+                                          Instruction *Pos) {
+  // Returns ((Addr & shadow_mask) + origin_base - shadow_base) & ~4UL
+  IRBuilder<> IRB(Pos);
+  Value *ShadowOffset = getShadowOffset(Addr, IRB);
+  Value *ShadowLong = ShadowOffset;
+  uint64_t ShadowBase = MapParams->ShadowBase;
+  if (ShadowBase != 0) {
+    ShadowLong =
+        IRB.CreateAdd(ShadowLong, ConstantInt::get(IntptrTy, ShadowBase));
+  }
+  IntegerType *ShadowTy = IntegerType::get(*Ctx, ShadowWidthBits);
+  Value *ShadowPtr =
+      IRB.CreateIntToPtr(ShadowLong, PointerType::get(ShadowTy, 0));
+  Value *OriginPtr = nullptr;
+  if (shouldTrackOrigins()) {
+    Value *OriginLong = ShadowOffset;
+    uint64_t OriginBase = MapParams->OriginBase;
+    if (OriginBase != 0)
+      OriginLong =
+          IRB.CreateAdd(OriginLong, ConstantInt::get(IntptrTy, OriginBase));
+    const Align Alignment = llvm::assumeAligned(InstAlignment.value());
+    // When alignment is >= 4, Addr must be aligned to 4, otherwise it is UB.
+    // So Mask is unnecessary.
+    if (Alignment < MinOriginAlignment) {
+      uint64_t Mask = MinOriginAlignment.value() - 1;
+      OriginLong = IRB.CreateAnd(OriginLong, ConstantInt::get(IntptrTy, ~Mask));
+    }
+    OriginPtr = IRB.CreateIntToPtr(OriginLong, OriginPtrTy);
+  }
+  return std::make_pair(ShadowPtr, OriginPtr);
+}
+
+Value *DataFlowSanitizer::getShadowAddress(Value *Addr, Instruction *Pos,
+                                           Value *ShadowOffset) {
+  IRBuilder<> IRB(Pos);
+  return IRB.CreateIntToPtr(ShadowOffset, PrimitiveShadowPtrTy);
+}
+
+Value *DataFlowSanitizer::getShadowAddress(Value *Addr, Instruction *Pos) {
+  IRBuilder<> IRB(Pos);
+  Value *ShadowOffset = getShadowOffset(Addr, IRB);
+  return getShadowAddress(Addr, Pos, ShadowOffset);
+}
+
+Value *DFSanFunction::combineShadowsThenConvert(Type *T, Value *V1, Value *V2,
+                                                Instruction *Pos) {
+  Value *PrimitiveValue = combineShadows(V1, V2, Pos);
+  return expandFromPrimitiveShadow(T, PrimitiveValue, Pos);
+}
+
+// Generates IR to compute the union of the two given shadows, inserting it
+// before Pos. The combined value is with primitive type.
+Value *DFSanFunction::combineShadows(Value *V1, Value *V2, Instruction *Pos) {
+  if (DFS.isZeroShadow(V1))
+    return collapseToPrimitiveShadow(V2, Pos);
+  if (DFS.isZeroShadow(V2))
+    return collapseToPrimitiveShadow(V1, Pos);
+  if (V1 == V2)
+    return collapseToPrimitiveShadow(V1, Pos);
+
+  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 collapseToPrimitiveShadow(V1, Pos);
+    }
+    if (std::includes(V2Elems->second.begin(), V2Elems->second.end(),
+                      V1Elems->second.begin(), V1Elems->second.end())) {
+      return collapseToPrimitiveShadow(V2, Pos);
+    }
+  } else if (V1Elems != ShadowElements.end()) {
+    if (V1Elems->second.count(V2))
+      return collapseToPrimitiveShadow(V1, Pos);
+  } else if (V2Elems != ShadowElements.end()) {
+    if (V2Elems->second.count(V1))
+      return collapseToPrimitiveShadow(V2, Pos);
+  }
+
+  auto Key = std::make_pair(V1, V2);
+  if (V1 > V2)
+    std::swap(Key.first, Key.second);
+  CachedShadow &CCS = CachedShadows[Key];
+  if (CCS.Block && DT.dominates(CCS.Block, Pos->getParent()))
+    return CCS.Shadow;
+
+  // Converts inputs shadows to shadows with primitive types.
+  Value *PV1 = collapseToPrimitiveShadow(V1, Pos);
+  Value *PV2 = collapseToPrimitiveShadow(V2, Pos);
+
+  IRBuilder<> IRB(Pos);
+  CCS.Block = Pos->getParent();
+  CCS.Shadow = IRB.CreateOr(PV1, PV2);
+
+  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 {
+    UnionElems.insert(V2);
+  }
+  ShadowElements[CCS.Shadow] = std::move(UnionElems);
+
+  return CCS.Shadow;
+}
+
+// A convenience function which folds the shadows of each of the operands
+// of the provided instruction Inst, inserting the IR before Inst.  Returns
+// the computed union Value.
+Value *DFSanFunction::combineOperandShadows(Instruction *Inst) {
+  if (Inst->getNumOperands() == 0)
+    return DFS.getZeroShadow(Inst);
+
+  Value *Shadow = getShadow(Inst->getOperand(0));
+  for (unsigned I = 1, N = Inst->getNumOperands(); I < N; ++I)
+    Shadow = combineShadows(Shadow, getShadow(Inst->getOperand(I)), Inst);
+
+  return expandFromPrimitiveShadow(Inst->getType(), Shadow, Inst);
+}
+
+void DFSanVisitor::visitInstOperands(Instruction &I) {
+  Value *CombinedShadow = DFSF.combineOperandShadows(&I);
+  DFSF.setShadow(&I, CombinedShadow);
+  visitInstOperandOrigins(I);
+}
+
+Value *DFSanFunction::combineOrigins(const std::vector<Value *> &Shadows,
+                                     const std::vector<Value *> &Origins,
+                                     Instruction *Pos, ConstantInt *Zero) {
+  assert(Shadows.size() == Origins.size());
+  size_t Size = Origins.size();
+  if (Size == 0)
+    return DFS.ZeroOrigin;
+  Value *Origin = nullptr;
+  if (!Zero)
+    Zero = DFS.ZeroPrimitiveShadow;
+  for (size_t I = 0; I != Size; ++I) {
+    Value *OpOrigin = Origins[I];
+    Constant *ConstOpOrigin = dyn_cast<Constant>(OpOrigin);
+    if (ConstOpOrigin && ConstOpOrigin->isNullValue())
+      continue;
+    if (!Origin) {
+      Origin = OpOrigin;
+      continue;
+    }
+    Value *OpShadow = Shadows[I];
+    Value *PrimitiveShadow = collapseToPrimitiveShadow(OpShadow, Pos);
+    IRBuilder<> IRB(Pos);
+    Value *Cond = IRB.CreateICmpNE(PrimitiveShadow, Zero);
+    Origin = IRB.CreateSelect(Cond, OpOrigin, Origin);
+  }
+  return Origin ? Origin : DFS.ZeroOrigin;
+}
+
+Value *DFSanFunction::combineOperandOrigins(Instruction *Inst) {
+  size_t Size = Inst->getNumOperands();
+  std::vector<Value *> Shadows(Size);
+  std::vector<Value *> Origins(Size);
+  for (unsigned I = 0; I != Size; ++I) {
+    Shadows[I] = getShadow(Inst->getOperand(I));
+    Origins[I] = getOrigin(Inst->getOperand(I));
+  }
+  return combineOrigins(Shadows, Origins, Inst);
+}
+
+void DFSanVisitor::visitInstOperandOrigins(Instruction &I) {
+  if (!DFSF.DFS.shouldTrackOrigins())
+    return;
+  Value *CombinedOrigin = DFSF.combineOperandOrigins(&I);
+  DFSF.setOrigin(&I, CombinedOrigin);
+}
+
+Align DFSanFunction::getShadowAlign(Align InstAlignment) {
+  const Align Alignment = ClPreserveAlignment ? InstAlignment : Align(1);
+  return Align(Alignment.value() * DFS.ShadowWidthBytes);
+}
+
+Align DFSanFunction::getOriginAlign(Align InstAlignment) {
+  const Align Alignment = llvm::assumeAligned(InstAlignment.value());
+  return Align(std::max(MinOriginAlignment, Alignment));
+}
+
+bool DFSanFunction::isLookupTableConstant(Value *P) {
+  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(P->stripPointerCasts()))
+    if (GV->isConstant() && GV->hasName())
+      return DFS.CombineTaintLookupTableNames.count(GV->getName());
+
+  return false;
+}
+
+bool DFSanFunction::useCallbackLoadLabelAndOrigin(uint64_t Size,
+                                                  Align InstAlignment) {
+  // When enabling tracking load instructions, we always use
+  // __dfsan_load_label_and_origin to reduce code size.
+  if (ClTrackOrigins == 2)
+    return true;
+
+  assert(Size != 0);
+  // * if Size == 1, it is sufficient to load its origin aligned at 4.
+  // * if Size == 2, we assume most cases Addr % 2 == 0, so it is sufficient to
+  //   load its origin aligned at 4. If not, although origins may be lost, it
+  //   should not happen very often.
+  // * if align >= 4, Addr must be aligned to 4, otherwise it is UB. When
+  //   Size % 4 == 0, it is more efficient to load origins without callbacks.
+  // * Otherwise we use __dfsan_load_label_and_origin.
+  // This should ensure that common cases run efficiently.
+  if (Size <= 2)
+    return false;
+
+  const Align Alignment = llvm::assumeAligned(InstAlignment.value());
+  return Alignment < MinOriginAlignment || !DFS.hasLoadSizeForFastPath(Size);
+}
+
+Value *DataFlowSanitizer::loadNextOrigin(Instruction *Pos, Align OriginAlign,
+                                         Value **OriginAddr) {
+  IRBuilder<> IRB(Pos);
+  *OriginAddr =
+      IRB.CreateGEP(OriginTy, *OriginAddr, ConstantInt::get(IntptrTy, 1));
+  return IRB.CreateAlignedLoad(OriginTy, *OriginAddr, OriginAlign);
+}
+
+std::pair<Value *, Value *> DFSanFunction::loadShadowFast(
+    Value *ShadowAddr, Value *OriginAddr, uint64_t Size, Align ShadowAlign,
+    Align OriginAlign, Value *FirstOrigin, Instruction *Pos) {
+  const bool ShouldTrackOrigins = DFS.shouldTrackOrigins();
+  const uint64_t ShadowSize = Size * DFS.ShadowWidthBytes;
+
+  assert(Size >= 4 && "Not large enough load size for fast path!");
+
+  // Used for origin tracking.
+  std::vector<Value *> Shadows;
+  std::vector<Value *> Origins;
+
+  // Load instructions in LLVM can have arbitrary byte sizes (e.g., 3, 12, 20)
+  // but this function is only used in a subset of cases that make it possible
+  // to optimize the instrumentation.
+  //
+  // Specifically, when the shadow size in bytes (i.e., loaded bytes x shadow
+  // per byte) is either:
+  // - a multiple of 8  (common)
+  // - equal to 4       (only for load32)
+  //
+  // For the second case, we can fit the wide shadow in a 32-bit integer. In all
+  // other cases, we use a 64-bit integer to hold the wide shadow.
+  Type *WideShadowTy =
+      ShadowSize == 4 ? Type::getInt32Ty(*DFS.Ctx) : Type::getInt64Ty(*DFS.Ctx);
+
+  IRBuilder<> IRB(Pos);
+  Value *WideAddr = IRB.CreateBitCast(ShadowAddr, WideShadowTy->getPointerTo());
+  Value *CombinedWideShadow =
+      IRB.CreateAlignedLoad(WideShadowTy, WideAddr, ShadowAlign);
+
+  unsigned WideShadowBitWidth = WideShadowTy->getIntegerBitWidth();
+  const uint64_t BytesPerWideShadow = WideShadowBitWidth / DFS.ShadowWidthBits;
+
+  auto AppendWideShadowAndOrigin = [&](Value *WideShadow, Value *Origin) {
+    if (BytesPerWideShadow > 4) {
+      assert(BytesPerWideShadow == 8);
+      // The wide shadow relates to two origin pointers: one for the first four
+      // application bytes, and one for the latest four. We use a left shift to
+      // get just the shadow bytes that correspond to the first origin pointer,
+      // and then the entire shadow for the second origin pointer (which will be
+      // chosen by combineOrigins() iff the least-significant half of the wide
+      // shadow was empty but the other half was not).
+      Value *WideShadowLo = IRB.CreateShl(
+          WideShadow, ConstantInt::get(WideShadowTy, WideShadowBitWidth / 2));
+      Shadows.push_back(WideShadow);
+      Origins.push_back(DFS.loadNextOrigin(Pos, OriginAlign, &OriginAddr));
+
+      Shadows.push_back(WideShadowLo);
+      Origins.push_back(Origin);
+    } else {
+      Shadows.push_back(WideShadow);
+      Origins.push_back(Origin);
+    }
+  };
+
+  if (ShouldTrackOrigins)
+    AppendWideShadowAndOrigin(CombinedWideShadow, FirstOrigin);
+
+  // First OR all the WideShadows (i.e., 64bit or 32bit shadow chunks) linearly;
+  // then OR individual shadows within the combined WideShadow by binary ORing.
+  // This is fewer instructions than ORing shadows individually, since it
+  // needs logN shift/or instructions (N being the bytes of the combined wide
+  // shadow).
+  for (uint64_t ByteOfs = BytesPerWideShadow; ByteOfs < Size;
+       ByteOfs += BytesPerWideShadow) {
+    WideAddr = IRB.CreateGEP(WideShadowTy, WideAddr,
+                             ConstantInt::get(DFS.IntptrTy, 1));
+    Value *NextWideShadow =
+        IRB.CreateAlignedLoad(WideShadowTy, WideAddr, ShadowAlign);
+    CombinedWideShadow = IRB.CreateOr(CombinedWideShadow, NextWideShadow);
+    if (ShouldTrackOrigins) {
+      Value *NextOrigin = DFS.loadNextOrigin(Pos, OriginAlign, &OriginAddr);
+      AppendWideShadowAndOrigin(NextWideShadow, NextOrigin);
+    }
+  }
+  for (unsigned Width = WideShadowBitWidth / 2; Width >= DFS.ShadowWidthBits;
+       Width >>= 1) {
+    Value *ShrShadow = IRB.CreateLShr(CombinedWideShadow, Width);
+    CombinedWideShadow = IRB.CreateOr(CombinedWideShadow, ShrShadow);
+  }
+  return {IRB.CreateTrunc(CombinedWideShadow, DFS.PrimitiveShadowTy),
+          ShouldTrackOrigins
+              ? combineOrigins(Shadows, Origins, Pos,
+                               ConstantInt::getSigned(IRB.getInt64Ty(), 0))
+              : DFS.ZeroOrigin};
+}
+
+std::pair<Value *, Value *> DFSanFunction::loadShadowOriginSansLoadTracking(
+    Value *Addr, uint64_t Size, Align InstAlignment, Instruction *Pos) {
+  const bool ShouldTrackOrigins = DFS.shouldTrackOrigins();
+
+  // Non-escaped loads.
+  if (AllocaInst *AI = dyn_cast<AllocaInst>(Addr)) {
+    const auto SI = AllocaShadowMap.find(AI);
+    if (SI != AllocaShadowMap.end()) {
+      IRBuilder<> IRB(Pos);
+      Value *ShadowLI = IRB.CreateLoad(DFS.PrimitiveShadowTy, SI->second);
+      const auto OI = AllocaOriginMap.find(AI);
+      assert(!ShouldTrackOrigins || OI != AllocaOriginMap.end());
+      return {ShadowLI, ShouldTrackOrigins
+                            ? IRB.CreateLoad(DFS.OriginTy, OI->second)
+                            : nullptr};
+    }
+  }
+
+  // Load from constant addresses.
+  SmallVector<const Value *, 2> Objs;
+  getUnderlyingObjects(Addr, Objs);
+  bool AllConstants = true;
+  for (const Value *Obj : Objs) {
+    if (isa<Function>(Obj) || isa<BlockAddress>(Obj))
+      continue;
+    if (isa<GlobalVariable>(Obj) && cast<GlobalVariable>(Obj)->isConstant())
+      continue;
+
+    AllConstants = false;
+    break;
+  }
+  if (AllConstants)
+    return {DFS.ZeroPrimitiveShadow,
+            ShouldTrackOrigins ? DFS.ZeroOrigin : nullptr};
+
+  if (Size == 0)
+    return {DFS.ZeroPrimitiveShadow,
+            ShouldTrackOrigins ? DFS.ZeroOrigin : nullptr};
+
+  // Use callback to load if this is not an optimizable case for origin
+  // tracking.
+  if (ShouldTrackOrigins &&
+      useCallbackLoadLabelAndOrigin(Size, InstAlignment)) {
+    IRBuilder<> IRB(Pos);
+    CallInst *Call =
+        IRB.CreateCall(DFS.DFSanLoadLabelAndOriginFn,
+                       {IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
+                        ConstantInt::get(DFS.IntptrTy, Size)});
+    Call->addRetAttr(Attribute::ZExt);
+    return {IRB.CreateTrunc(IRB.CreateLShr(Call, DFS.OriginWidthBits),
+                            DFS.PrimitiveShadowTy),
+            IRB.CreateTrunc(Call, DFS.OriginTy)};
+  }
+
+  // Other cases that support loading shadows or origins in a fast way.
+  Value *ShadowAddr, *OriginAddr;
+  std::tie(ShadowAddr, OriginAddr) =
+      DFS.getShadowOriginAddress(Addr, InstAlignment, Pos);
+
+  const Align ShadowAlign = getShadowAlign(InstAlignment);
+  const Align OriginAlign = getOriginAlign(InstAlignment);
+  Value *Origin = nullptr;
+  if (ShouldTrackOrigins) {
+    IRBuilder<> IRB(Pos);
+    Origin = IRB.CreateAlignedLoad(DFS.OriginTy, OriginAddr, OriginAlign);
+  }
+
+  // When the byte size is small enough, we can load the shadow directly with
+  // just a few instructions.
+  switch (Size) {
+  case 1: {
+    LoadInst *LI = new LoadInst(DFS.PrimitiveShadowTy, ShadowAddr, "", Pos);
+    LI->setAlignment(ShadowAlign);
+    return {LI, Origin};
+  }
+  case 2: {
+    IRBuilder<> IRB(Pos);
+    Value *ShadowAddr1 = IRB.CreateGEP(DFS.PrimitiveShadowTy, ShadowAddr,
+                                       ConstantInt::get(DFS.IntptrTy, 1));
+    Value *Load =
+        IRB.CreateAlignedLoad(DFS.PrimitiveShadowTy, ShadowAddr, ShadowAlign);
+    Value *Load1 =
+        IRB.CreateAlignedLoad(DFS.PrimitiveShadowTy, ShadowAddr1, ShadowAlign);
+    return {combineShadows(Load, Load1, Pos), Origin};
+  }
+  }
+  bool HasSizeForFastPath = DFS.hasLoadSizeForFastPath(Size);
+
+  if (HasSizeForFastPath)
+    return loadShadowFast(ShadowAddr, OriginAddr, Size, ShadowAlign,
+                          OriginAlign, Origin, Pos);
+
+  IRBuilder<> IRB(Pos);
+  CallInst *FallbackCall = IRB.CreateCall(
+      DFS.DFSanUnionLoadFn, {ShadowAddr, ConstantInt::get(DFS.IntptrTy, Size)});
+  FallbackCall->addRetAttr(Attribute::ZExt);
+  return {FallbackCall, Origin};
+}
+
+std::pair<Value *, Value *> DFSanFunction::loadShadowOrigin(Value *Addr,
+                                                            uint64_t Size,
+                                                            Align InstAlignment,
+                                                            Instruction *Pos) {
+  Value *PrimitiveShadow, *Origin;
+  std::tie(PrimitiveShadow, Origin) =
+      loadShadowOriginSansLoadTracking(Addr, Size, InstAlignment, Pos);
+  if (DFS.shouldTrackOrigins()) {
+    if (ClTrackOrigins == 2) {
+      IRBuilder<> IRB(Pos);
+      auto *ConstantShadow = dyn_cast<Constant>(PrimitiveShadow);
+      if (!ConstantShadow || !ConstantShadow->isZeroValue())
+        Origin = updateOriginIfTainted(PrimitiveShadow, Origin, IRB);
+    }
+  }
+  return {PrimitiveShadow, Origin};
+}
+
+static AtomicOrdering addAcquireOrdering(AtomicOrdering AO) {
+  switch (AO) {
+  case AtomicOrdering::NotAtomic:
+    return AtomicOrdering::NotAtomic;
+  case AtomicOrdering::Unordered:
+  case AtomicOrdering::Monotonic:
+  case AtomicOrdering::Acquire:
+    return AtomicOrdering::Acquire;
+  case AtomicOrdering::Release:
+  case AtomicOrdering::AcquireRelease:
+    return AtomicOrdering::AcquireRelease;
+  case AtomicOrdering::SequentiallyConsistent:
+    return AtomicOrdering::SequentiallyConsistent;
+  }
+  llvm_unreachable("Unknown ordering");
+}
+
+Value *StripPointerGEPsAndCasts(Value *V) {
+  if (!V->getType()->isPointerTy())
+    return V;
+
+  // DFSan pass should be running on valid IR, but we'll
+  // keep a seen set to ensure there are no issues.
+  SmallPtrSet<const Value *, 4> Visited;
+  Visited.insert(V);
+  do {
+    if (auto *GEP = dyn_cast<GEPOperator>(V)) {
+      V = GEP->getPointerOperand();
+    } else if (Operator::getOpcode(V) == Instruction::BitCast) {
+      V = cast<Operator>(V)->getOperand(0);
+      if (!V->getType()->isPointerTy())
+        return V;
+    } else if (isa<GlobalAlias>(V)) {
+      V = cast<GlobalAlias>(V)->getAliasee();
+    }
+  } while (Visited.insert(V).second);
+
+  return V;
+}
+
+void DFSanVisitor::visitLoadInst(LoadInst &LI) {
+  auto &DL = LI.getModule()->getDataLayout();
+  uint64_t Size = DL.getTypeStoreSize(LI.getType());
+  if (Size == 0) {
+    DFSF.setShadow(&LI, DFSF.DFS.getZeroShadow(&LI));
+    DFSF.setOrigin(&LI, DFSF.DFS.ZeroOrigin);
+    return;
+  }
+
+  // When an application load is atomic, increase atomic ordering between
+  // atomic application loads and stores to ensure happen-before order; load
+  // shadow data after application data; store zero shadow data before
+  // application data. This ensure shadow loads return either labels of the
+  // initial application data or zeros.
+  if (LI.isAtomic())
+    LI.setOrdering(addAcquireOrdering(LI.getOrdering()));
+
+  Instruction *AfterLi = LI.getNextNode();
+  Instruction *Pos = LI.isAtomic() ? LI.getNextNode() : &LI;
+  std::vector<Value *> Shadows;
+  std::vector<Value *> Origins;
+  Value *PrimitiveShadow, *Origin;
+  std::tie(PrimitiveShadow, Origin) =
+      DFSF.loadShadowOrigin(LI.getPointerOperand(), Size, LI.getAlign(), Pos);
+  const bool ShouldTrackOrigins = DFSF.DFS.shouldTrackOrigins();
+  if (ShouldTrackOrigins) {
+    Shadows.push_back(PrimitiveShadow);
+    Origins.push_back(Origin);
+  }
+  if (ClCombinePointerLabelsOnLoad ||
+      DFSF.isLookupTableConstant(
+          StripPointerGEPsAndCasts(LI.getPointerOperand()))) {
+    Value *PtrShadow = DFSF.getShadow(LI.getPointerOperand());
+    PrimitiveShadow = DFSF.combineShadows(PrimitiveShadow, PtrShadow, Pos);
+    if (ShouldTrackOrigins) {
+      Shadows.push_back(PtrShadow);
+      Origins.push_back(DFSF.getOrigin(LI.getPointerOperand()));
+    }
+  }
+  if (!DFSF.DFS.isZeroShadow(PrimitiveShadow))
+    DFSF.NonZeroChecks.push_back(PrimitiveShadow);
+
+  Value *Shadow =
+      DFSF.expandFromPrimitiveShadow(LI.getType(), PrimitiveShadow, Pos);
+  DFSF.setShadow(&LI, Shadow);
+
+  if (ShouldTrackOrigins) {
+    DFSF.setOrigin(&LI, DFSF.combineOrigins(Shadows, Origins, Pos));
+  }
+
+  if (ClEventCallbacks) {
+    IRBuilder<> IRB(Pos);
+    Value *Addr8 = IRB.CreateBitCast(LI.getPointerOperand(), DFSF.DFS.Int8Ptr);
+    CallInst *CI =
+        IRB.CreateCall(DFSF.DFS.DFSanLoadCallbackFn, {PrimitiveShadow, Addr8});
+    CI->addParamAttr(0, Attribute::ZExt);
+  }
+
+  IRBuilder<> IRB(AfterLi);
+  DFSF.addReachesFunctionCallbacksIfEnabled(IRB, LI, &LI);
+}
+
+Value *DFSanFunction::updateOriginIfTainted(Value *Shadow, Value *Origin,
+                                            IRBuilder<> &IRB) {
+  assert(DFS.shouldTrackOrigins());
+  return IRB.CreateCall(DFS.DFSanChainOriginIfTaintedFn, {Shadow, Origin});
+}
+
+Value *DFSanFunction::updateOrigin(Value *V, IRBuilder<> &IRB) {
+  if (!DFS.shouldTrackOrigins())
+    return V;
+  return IRB.CreateCall(DFS.DFSanChainOriginFn, V);
+}
+
+Value *DFSanFunction::originToIntptr(IRBuilder<> &IRB, Value *Origin) {
+  const unsigned OriginSize = DataFlowSanitizer::OriginWidthBytes;
+  const DataLayout &DL = F->getParent()->getDataLayout();
+  unsigned IntptrSize = DL.getTypeStoreSize(DFS.IntptrTy);
+  if (IntptrSize == OriginSize)
+    return Origin;
+  assert(IntptrSize == OriginSize * 2);
+  Origin = IRB.CreateIntCast(Origin, DFS.IntptrTy, /* isSigned */ false);
+  return IRB.CreateOr(Origin, IRB.CreateShl(Origin, OriginSize * 8));
+}
+
+void DFSanFunction::paintOrigin(IRBuilder<> &IRB, Value *Origin,
+                                Value *StoreOriginAddr,
+                                uint64_t StoreOriginSize, Align Alignment) {
+  const unsigned OriginSize = DataFlowSanitizer::OriginWidthBytes;
+  const DataLayout &DL = F->getParent()->getDataLayout();
+  const Align IntptrAlignment = DL.getABITypeAlign(DFS.IntptrTy);
+  unsigned IntptrSize = DL.getTypeStoreSize(DFS.IntptrTy);
+  assert(IntptrAlignment >= MinOriginAlignment);
+  assert(IntptrSize >= OriginSize);
+
+  unsigned Ofs = 0;
+  Align CurrentAlignment = Alignment;
+  if (Alignment >= IntptrAlignment && IntptrSize > OriginSize) {
+    Value *IntptrOrigin = originToIntptr(IRB, Origin);
+    Value *IntptrStoreOriginPtr = IRB.CreatePointerCast(
+        StoreOriginAddr, PointerType::get(DFS.IntptrTy, 0));
+    for (unsigned I = 0; I < StoreOriginSize / IntptrSize; ++I) {
+      Value *Ptr =
+          I ? IRB.CreateConstGEP1_32(DFS.IntptrTy, IntptrStoreOriginPtr, I)
+            : IntptrStoreOriginPtr;
+      IRB.CreateAlignedStore(IntptrOrigin, Ptr, CurrentAlignment);
+      Ofs += IntptrSize / OriginSize;
+      CurrentAlignment = IntptrAlignment;
+    }
+  }
+
+  for (unsigned I = Ofs; I < (StoreOriginSize + OriginSize - 1) / OriginSize;
+       ++I) {
+    Value *GEP = I ? IRB.CreateConstGEP1_32(DFS.OriginTy, StoreOriginAddr, I)
+                   : StoreOriginAddr;
+    IRB.CreateAlignedStore(Origin, GEP, CurrentAlignment);
+    CurrentAlignment = MinOriginAlignment;
+  }
+}
+
+Value *DFSanFunction::convertToBool(Value *V, IRBuilder<> &IRB,
+                                    const Twine &Name) {
+  Type *VTy = V->getType();
+  assert(VTy->isIntegerTy());
+  if (VTy->getIntegerBitWidth() == 1)
+    // Just converting a bool to a bool, so do nothing.
+    return V;
+  return IRB.CreateICmpNE(V, ConstantInt::get(VTy, 0), Name);
+}
+
+void DFSanFunction::storeOrigin(Instruction *Pos, Value *Addr, uint64_t Size,
+                                Value *Shadow, Value *Origin,
+                                Value *StoreOriginAddr, Align InstAlignment) {
+  // Do not write origins for zero shadows because we do not trace origins for
+  // untainted sinks.
+  const Align OriginAlignment = getOriginAlign(InstAlignment);
+  Value *CollapsedShadow = collapseToPrimitiveShadow(Shadow, Pos);
+  IRBuilder<> IRB(Pos);
+  if (auto *ConstantShadow = dyn_cast<Constant>(CollapsedShadow)) {
+    if (!ConstantShadow->isZeroValue())
+      paintOrigin(IRB, updateOrigin(Origin, IRB), StoreOriginAddr, Size,
+                  OriginAlignment);
+    return;
+  }
+
+  if (shouldInstrumentWithCall()) {
+    IRB.CreateCall(DFS.DFSanMaybeStoreOriginFn,
+                   {CollapsedShadow,
+                    IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
+                    ConstantInt::get(DFS.IntptrTy, Size), Origin});
+  } else {
+    Value *Cmp = convertToBool(CollapsedShadow, IRB, "_dfscmp");
+    Instruction *CheckTerm = SplitBlockAndInsertIfThen(
+        Cmp, &*IRB.GetInsertPoint(), false, DFS.OriginStoreWeights, &DT);
+    IRBuilder<> IRBNew(CheckTerm);
+    paintOrigin(IRBNew, updateOrigin(Origin, IRBNew), StoreOriginAddr, Size,
+                OriginAlignment);
+    ++NumOriginStores;
+  }
+}
+
+void DFSanFunction::storeZeroPrimitiveShadow(Value *Addr, uint64_t Size,
+                                             Align ShadowAlign,
+                                             Instruction *Pos) {
+  IRBuilder<> IRB(Pos);
+  IntegerType *ShadowTy =
+      IntegerType::get(*DFS.Ctx, Size * DFS.ShadowWidthBits);
+  Value *ExtZeroShadow = ConstantInt::get(ShadowTy, 0);
+  Value *ShadowAddr = DFS.getShadowAddress(Addr, Pos);
+  Value *ExtShadowAddr =
+      IRB.CreateBitCast(ShadowAddr, PointerType::getUnqual(ShadowTy));
+  IRB.CreateAlignedStore(ExtZeroShadow, ExtShadowAddr, ShadowAlign);
+  // Do not write origins for 0 shadows because we do not trace origins for
+  // untainted sinks.
+}
+
+void DFSanFunction::storePrimitiveShadowOrigin(Value *Addr, uint64_t Size,
+                                               Align InstAlignment,
+                                               Value *PrimitiveShadow,
+                                               Value *Origin,
+                                               Instruction *Pos) {
+  const bool ShouldTrackOrigins = DFS.shouldTrackOrigins() && Origin;
+
+  if (AllocaInst *AI = dyn_cast<AllocaInst>(Addr)) {
+    const auto SI = AllocaShadowMap.find(AI);
+    if (SI != AllocaShadowMap.end()) {
+      IRBuilder<> IRB(Pos);
+      IRB.CreateStore(PrimitiveShadow, SI->second);
+
+      // Do not write origins for 0 shadows because we do not trace origins for
+      // untainted sinks.
+      if (ShouldTrackOrigins && !DFS.isZeroShadow(PrimitiveShadow)) {
+        const auto OI = AllocaOriginMap.find(AI);
+        assert(OI != AllocaOriginMap.end() && Origin);
+        IRB.CreateStore(Origin, OI->second);
+      }
+      return;
+    }
+  }
+
+  const Align ShadowAlign = getShadowAlign(InstAlignment);
+  if (DFS.isZeroShadow(PrimitiveShadow)) {
+    storeZeroPrimitiveShadow(Addr, Size, ShadowAlign, Pos);
+    return;
+  }
+
+  IRBuilder<> IRB(Pos);
+  Value *ShadowAddr, *OriginAddr;
+  std::tie(ShadowAddr, OriginAddr) =
+      DFS.getShadowOriginAddress(Addr, InstAlignment, Pos);
+
+  const unsigned ShadowVecSize = 8;
+  assert(ShadowVecSize * DFS.ShadowWidthBits <= 128 &&
+         "Shadow vector is too large!");
+
+  uint64_t Offset = 0;
+  uint64_t LeftSize = Size;
+  if (LeftSize >= ShadowVecSize) {
+    auto *ShadowVecTy =
+        FixedVectorType::get(DFS.PrimitiveShadowTy, ShadowVecSize);
+    Value *ShadowVec = PoisonValue::get(ShadowVecTy);
+    for (unsigned I = 0; I != ShadowVecSize; ++I) {
+      ShadowVec = IRB.CreateInsertElement(
+          ShadowVec, PrimitiveShadow,
+          ConstantInt::get(Type::getInt32Ty(*DFS.Ctx), I));
+    }
+    Value *ShadowVecAddr =
+        IRB.CreateBitCast(ShadowAddr, PointerType::getUnqual(ShadowVecTy));
+    do {
+      Value *CurShadowVecAddr =
+          IRB.CreateConstGEP1_32(ShadowVecTy, ShadowVecAddr, Offset);
+      IRB.CreateAlignedStore(ShadowVec, CurShadowVecAddr, ShadowAlign);
+      LeftSize -= ShadowVecSize;
+      ++Offset;
+    } while (LeftSize >= ShadowVecSize);
+    Offset *= ShadowVecSize;
+  }
+  while (LeftSize > 0) {
+    Value *CurShadowAddr =
+        IRB.CreateConstGEP1_32(DFS.PrimitiveShadowTy, ShadowAddr, Offset);
+    IRB.CreateAlignedStore(PrimitiveShadow, CurShadowAddr, ShadowAlign);
+    --LeftSize;
+    ++Offset;
+  }
+
+  if (ShouldTrackOrigins) {
+    storeOrigin(Pos, Addr, Size, PrimitiveShadow, Origin, OriginAddr,
+                InstAlignment);
+  }
+}
+
+static AtomicOrdering addReleaseOrdering(AtomicOrdering AO) {
+  switch (AO) {
+  case AtomicOrdering::NotAtomic:
+    return AtomicOrdering::NotAtomic;
+  case AtomicOrdering::Unordered:
+  case AtomicOrdering::Monotonic:
+  case AtomicOrdering::Release:
+    return AtomicOrdering::Release;
+  case AtomicOrdering::Acquire:
+  case AtomicOrdering::AcquireRelease:
+    return AtomicOrdering::AcquireRelease;
+  case AtomicOrdering::SequentiallyConsistent:
+    return AtomicOrdering::SequentiallyConsistent;
+  }
+  llvm_unreachable("Unknown ordering");
+}
+
+void DFSanVisitor::visitStoreInst(StoreInst &SI) {
+  auto &DL = SI.getModule()->getDataLayout();
+  Value *Val = SI.getValueOperand();
+  uint64_t Size = DL.getTypeStoreSize(Val->getType());
+  if (Size == 0)
+    return;
+
+  // When an application store is atomic, increase atomic ordering between
+  // atomic application loads and stores to ensure happen-before order; load
+  // shadow data after application data; store zero shadow data before
+  // application data. This ensure shadow loads return either labels of the
+  // initial application data or zeros.
+  if (SI.isAtomic())
+    SI.setOrdering(addReleaseOrdering(SI.getOrdering()));
+
+  const bool ShouldTrackOrigins =
+      DFSF.DFS.shouldTrackOrigins() && !SI.isAtomic();
+  std::vector<Value *> Shadows;
+  std::vector<Value *> Origins;
+
+  Value *Shadow =
+      SI.isAtomic() ? DFSF.DFS.getZeroShadow(Val) : DFSF.getShadow(Val);
+
+  if (ShouldTrackOrigins) {
+    Shadows.push_back(Shadow);
+    Origins.push_back(DFSF.getOrigin(Val));
+  }
+
+  Value *PrimitiveShadow;
+  if (ClCombinePointerLabelsOnStore) {
+    Value *PtrShadow = DFSF.getShadow(SI.getPointerOperand());
+    if (ShouldTrackOrigins) {
+      Shadows.push_back(PtrShadow);
+      Origins.push_back(DFSF.getOrigin(SI.getPointerOperand()));
+    }
+    PrimitiveShadow = DFSF.combineShadows(Shadow, PtrShadow, &SI);
+  } else {
+    PrimitiveShadow = DFSF.collapseToPrimitiveShadow(Shadow, &SI);
+  }
+  Value *Origin = nullptr;
+  if (ShouldTrackOrigins)
+    Origin = DFSF.combineOrigins(Shadows, Origins, &SI);
+  DFSF.storePrimitiveShadowOrigin(SI.getPointerOperand(), Size, SI.getAlign(),
+                                  PrimitiveShadow, Origin, &SI);
+  if (ClEventCallbacks) {
+    IRBuilder<> IRB(&SI);
+    Value *Addr8 = IRB.CreateBitCast(SI.getPointerOperand(), DFSF.DFS.Int8Ptr);
+    CallInst *CI =
+        IRB.CreateCall(DFSF.DFS.DFSanStoreCallbackFn, {PrimitiveShadow, Addr8});
+    CI->addParamAttr(0, Attribute::ZExt);
+  }
+}
+
+void DFSanVisitor::visitCASOrRMW(Align InstAlignment, Instruction &I) {
+  assert(isa<AtomicRMWInst>(I) || isa<AtomicCmpXchgInst>(I));
+
+  Value *Val = I.getOperand(1);
+  const auto &DL = I.getModule()->getDataLayout();
+  uint64_t Size = DL.getTypeStoreSize(Val->getType());
+  if (Size == 0)
+    return;
+
+  // Conservatively set data at stored addresses and return with zero shadow to
+  // prevent shadow data races.
+  IRBuilder<> IRB(&I);
+  Value *Addr = I.getOperand(0);
+  const Align ShadowAlign = DFSF.getShadowAlign(InstAlignment);
+  DFSF.storeZeroPrimitiveShadow(Addr, Size, ShadowAlign, &I);
+  DFSF.setShadow(&I, DFSF.DFS.getZeroShadow(&I));
+  DFSF.setOrigin(&I, DFSF.DFS.ZeroOrigin);
+}
+
+void DFSanVisitor::visitAtomicRMWInst(AtomicRMWInst &I) {
+  visitCASOrRMW(I.getAlign(), I);
+  // TODO: The ordering change follows MSan. It is possible not to change
+  // ordering because we always set and use 0 shadows.
+  I.setOrdering(addReleaseOrdering(I.getOrdering()));
+}
+
+void DFSanVisitor::visitAtomicCmpXchgInst(AtomicCmpXchgInst &I) {
+  visitCASOrRMW(I.getAlign(), I);
+  // TODO: The ordering change follows MSan. It is possible not to change
+  // ordering because we always set and use 0 shadows.
+  I.setSuccessOrdering(addReleaseOrdering(I.getSuccessOrdering()));
+}
+
+void DFSanVisitor::visitUnaryOperator(UnaryOperator &UO) {
+  visitInstOperands(UO);
+}
+
+void DFSanVisitor::visitBinaryOperator(BinaryOperator &BO) {
+  visitInstOperands(BO);
+}
+
+void DFSanVisitor::visitBitCastInst(BitCastInst &BCI) {
+  // Special case: if this is the bitcast (there is exactly 1 allowed) between
+  // a musttail call and a ret, don't instrument. New instructions are not
+  // allowed after a musttail call.
+  if (auto *CI = dyn_cast<CallInst>(BCI.getOperand(0)))
+    if (CI->isMustTailCall())
+      return;
+  visitInstOperands(BCI);
+}
+
+void DFSanVisitor::visitCastInst(CastInst &CI) { visitInstOperands(CI); }
+
+void DFSanVisitor::visitCmpInst(CmpInst &CI) {
+  visitInstOperands(CI);
+  if (ClEventCallbacks) {
+    IRBuilder<> IRB(&CI);
+    Value *CombinedShadow = DFSF.getShadow(&CI);
+    CallInst *CallI =
+        IRB.CreateCall(DFSF.DFS.DFSanCmpCallbackFn, CombinedShadow);
+    CallI->addParamAttr(0, Attribute::ZExt);
+  }
+}
+
+void DFSanVisitor::visitLandingPadInst(LandingPadInst &LPI) {
+  // We do not need to track data through LandingPadInst.
+  //
+  // For the C++ exceptions, if a value is thrown, this value will be stored
+  // in a memory location provided by __cxa_allocate_exception(...) (on the
+  // throw side) or  __cxa_begin_catch(...) (on the catch side).
+  // This memory will have a shadow, so with the loads and stores we will be
+  // able to propagate labels on data thrown through exceptions, without any
+  // special handling of the LandingPadInst.
+  //
+  // The second element in the pair result of the LandingPadInst is a
+  // register value, but it is for a type ID and should never be tainted.
+  DFSF.setShadow(&LPI, DFSF.DFS.getZeroShadow(&LPI));
+  DFSF.setOrigin(&LPI, DFSF.DFS.ZeroOrigin);
+}
+
+void DFSanVisitor::visitGetElementPtrInst(GetElementPtrInst &GEPI) {
+  if (ClCombineOffsetLabelsOnGEP ||
+      DFSF.isLookupTableConstant(
+          StripPointerGEPsAndCasts(GEPI.getPointerOperand()))) {
+    visitInstOperands(GEPI);
+    return;
+  }
+
+  // Only propagate shadow/origin of base pointer value but ignore those of
+  // offset operands.
+  Value *BasePointer = GEPI.getPointerOperand();
+  DFSF.setShadow(&GEPI, DFSF.getShadow(BasePointer));
+  if (DFSF.DFS.shouldTrackOrigins())
+    DFSF.setOrigin(&GEPI, DFSF.getOrigin(BasePointer));
+}
+
+void DFSanVisitor::visitExtractElementInst(ExtractElementInst &I) {
+  visitInstOperands(I);
+}
+
+void DFSanVisitor::visitInsertElementInst(InsertElementInst &I) {
+  visitInstOperands(I);
+}
+
+void DFSanVisitor::visitShuffleVectorInst(ShuffleVectorInst &I) {
+  visitInstOperands(I);
+}
+
+void DFSanVisitor::visitExtractValueInst(ExtractValueInst &I) {
+  IRBuilder<> IRB(&I);
+  Value *Agg = I.getAggregateOperand();
+  Value *AggShadow = DFSF.getShadow(Agg);
+  Value *ResShadow = IRB.CreateExtractValue(AggShadow, I.getIndices());
+  DFSF.setShadow(&I, ResShadow);
+  visitInstOperandOrigins(I);
+}
+
+void DFSanVisitor::visitInsertValueInst(InsertValueInst &I) {
+  IRBuilder<> IRB(&I);
+  Value *AggShadow = DFSF.getShadow(I.getAggregateOperand());
+  Value *InsShadow = DFSF.getShadow(I.getInsertedValueOperand());
+  Value *Res = IRB.CreateInsertValue(AggShadow, InsShadow, I.getIndices());
+  DFSF.setShadow(&I, Res);
+  visitInstOperandOrigins(I);
+}
+
+void DFSanVisitor::visitAllocaInst(AllocaInst &I) {
+  bool AllLoadsStores = true;
+  for (User *U : I.users()) {
+    if (isa<LoadInst>(U))
+      continue;
+
+    if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
+      if (SI->getPointerOperand() == &I)
+        continue;
+    }
+
+    AllLoadsStores = false;
+    break;
+  }
+  if (AllLoadsStores) {
+    IRBuilder<> IRB(&I);
+    DFSF.AllocaShadowMap[&I] = IRB.CreateAlloca(DFSF.DFS.PrimitiveShadowTy);
+    if (DFSF.DFS.shouldTrackOrigins()) {
+      DFSF.AllocaOriginMap[&I] =
+          IRB.CreateAlloca(DFSF.DFS.OriginTy, nullptr, "_dfsa");
+    }
+  }
+  DFSF.setShadow(&I, DFSF.DFS.ZeroPrimitiveShadow);
+  DFSF.setOrigin(&I, DFSF.DFS.ZeroOrigin);
+}
+
+void DFSanVisitor::visitSelectInst(SelectInst &I) {
+  Value *CondShadow = DFSF.getShadow(I.getCondition());
+  Value *TrueShadow = DFSF.getShadow(I.getTrueValue());
+  Value *FalseShadow = DFSF.getShadow(I.getFalseValue());
+  Value *ShadowSel = nullptr;
+  const bool ShouldTrackOrigins = DFSF.DFS.shouldTrackOrigins();
+  std::vector<Value *> Shadows;
+  std::vector<Value *> Origins;
+  Value *TrueOrigin =
+      ShouldTrackOrigins ? DFSF.getOrigin(I.getTrueValue()) : nullptr;
+  Value *FalseOrigin =
+      ShouldTrackOrigins ? DFSF.getOrigin(I.getFalseValue()) : nullptr;
+
+  DFSF.addConditionalCallbacksIfEnabled(I, I.getCondition());
+
+  if (isa<VectorType>(I.getCondition()->getType())) {
+    ShadowSel = DFSF.combineShadowsThenConvert(I.getType(), TrueShadow,
+                                               FalseShadow, &I);
+    if (ShouldTrackOrigins) {
+      Shadows.push_back(TrueShadow);
+      Shadows.push_back(FalseShadow);
+      Origins.push_back(TrueOrigin);
+      Origins.push_back(FalseOrigin);
+    }
+  } else {
+    if (TrueShadow == FalseShadow) {
+      ShadowSel = TrueShadow;
+      if (ShouldTrackOrigins) {
+        Shadows.push_back(TrueShadow);
+        Origins.push_back(TrueOrigin);
+      }
+    } else {
+      ShadowSel =
+          SelectInst::Create(I.getCondition(), TrueShadow, FalseShadow, "", &I);
+      if (ShouldTrackOrigins) {
+        Shadows.push_back(ShadowSel);
+        Origins.push_back(SelectInst::Create(I.getCondition(), TrueOrigin,
+                                             FalseOrigin, "", &I));
+      }
+    }
+  }
+  DFSF.setShadow(&I, ClTrackSelectControlFlow
+                         ? DFSF.combineShadowsThenConvert(
+                               I.getType(), CondShadow, ShadowSel, &I)
+                         : ShadowSel);
+  if (ShouldTrackOrigins) {
+    if (ClTrackSelectControlFlow) {
+      Shadows.push_back(CondShadow);
+      Origins.push_back(DFSF.getOrigin(I.getCondition()));
+    }
+    DFSF.setOrigin(&I, DFSF.combineOrigins(Shadows, Origins, &I));
+  }
+}
+
+void DFSanVisitor::visitMemSetInst(MemSetInst &I) {
+  IRBuilder<> IRB(&I);
+  Value *ValShadow = DFSF.getShadow(I.getValue());
+  Value *ValOrigin = DFSF.DFS.shouldTrackOrigins()
+                         ? DFSF.getOrigin(I.getValue())
+                         : DFSF.DFS.ZeroOrigin;
+  IRB.CreateCall(
+      DFSF.DFS.DFSanSetLabelFn,
+      {ValShadow, ValOrigin,
+       IRB.CreateBitCast(I.getDest(), Type::getInt8PtrTy(*DFSF.DFS.Ctx)),
+       IRB.CreateZExtOrTrunc(I.getLength(), DFSF.DFS.IntptrTy)});
+}
+
+void DFSanVisitor::visitMemTransferInst(MemTransferInst &I) {
+  IRBuilder<> IRB(&I);
+
+  // CopyOrMoveOrigin transfers origins by refering to their shadows. So we
+  // need to move origins before moving shadows.
+  if (DFSF.DFS.shouldTrackOrigins()) {
+    IRB.CreateCall(
+        DFSF.DFS.DFSanMemOriginTransferFn,
+        {IRB.CreatePointerCast(I.getArgOperand(0), IRB.getInt8PtrTy()),
+         IRB.CreatePointerCast(I.getArgOperand(1), IRB.getInt8PtrTy()),
+         IRB.CreateIntCast(I.getArgOperand(2), DFSF.DFS.IntptrTy, false)});
+  }
+
+  Value *RawDestShadow = DFSF.DFS.getShadowAddress(I.getDest(), &I);
+  Value *SrcShadow = DFSF.DFS.getShadowAddress(I.getSource(), &I);
+  Value *LenShadow =
+      IRB.CreateMul(I.getLength(), ConstantInt::get(I.getLength()->getType(),
+                                                    DFSF.DFS.ShadowWidthBytes));
+  Type *Int8Ptr = Type::getInt8PtrTy(*DFSF.DFS.Ctx);
+  Value *DestShadow = IRB.CreateBitCast(RawDestShadow, Int8Ptr);
+  SrcShadow = IRB.CreateBitCast(SrcShadow, Int8Ptr);
+  auto *MTI = cast<MemTransferInst>(
+      IRB.CreateCall(I.getFunctionType(), I.getCalledOperand(),
+                     {DestShadow, SrcShadow, LenShadow, I.getVolatileCst()}));
+  MTI->setDestAlignment(DFSF.getShadowAlign(I.getDestAlign().valueOrOne()));
+  MTI->setSourceAlignment(DFSF.getShadowAlign(I.getSourceAlign().valueOrOne()));
+  if (ClEventCallbacks) {
+    IRB.CreateCall(DFSF.DFS.DFSanMemTransferCallbackFn,
+                   {RawDestShadow,
+                    IRB.CreateZExtOrTrunc(I.getLength(), DFSF.DFS.IntptrTy)});
+  }
+}
+
+void DFSanVisitor::visitBranchInst(BranchInst &BR) {
+  if (!BR.isConditional())
+    return;
+
+  DFSF.addConditionalCallbacksIfEnabled(BR, BR.getCondition());
+}
+
+void DFSanVisitor::visitSwitchInst(SwitchInst &SW) {
+  DFSF.addConditionalCallbacksIfEnabled(SW, SW.getCondition());
+}
+
+static bool isAMustTailRetVal(Value *RetVal) {
+  // Tail call may have a bitcast between return.
+  if (auto *I = dyn_cast<BitCastInst>(RetVal)) {
+    RetVal = I->getOperand(0);
+  }
+  if (auto *I = dyn_cast<CallInst>(RetVal)) {
+    return I->isMustTailCall();
+  }
+  return false;
+}
+
+void DFSanVisitor::visitReturnInst(ReturnInst &RI) {
+  if (!DFSF.IsNativeABI && RI.getReturnValue()) {
+    // Don't emit the instrumentation for musttail call returns.
+    if (isAMustTailRetVal(RI.getReturnValue()))
+      return;
+
+    Value *S = DFSF.getShadow(RI.getReturnValue());
+    IRBuilder<> IRB(&RI);
+    Type *RT = DFSF.F->getFunctionType()->getReturnType();
+    unsigned Size = getDataLayout().getTypeAllocSize(DFSF.DFS.getShadowTy(RT));
+    if (Size <= RetvalTLSSize) {
+      // If the size overflows, stores nothing. At callsite, oversized return
+      // shadows are set to zero.
+      IRB.CreateAlignedStore(S, DFSF.getRetvalTLS(RT, IRB), ShadowTLSAlignment);
+    }
+    if (DFSF.DFS.shouldTrackOrigins()) {
+      Value *O = DFSF.getOrigin(RI.getReturnValue());
+      IRB.CreateStore(O, DFSF.getRetvalOriginTLS());
+    }
+  }
+}
+
+void DFSanVisitor::addShadowArguments(Function &F, CallBase &CB,
+                                      std::vector<Value *> &Args,
+                                      IRBuilder<> &IRB) {
+  FunctionType *FT = F.getFunctionType();
+
+  auto *I = CB.arg_begin();
+
+  // Adds non-variable argument shadows.
+  for (unsigned N = FT->getNumParams(); N != 0; ++I, --N)
+    Args.push_back(DFSF.collapseToPrimitiveShadow(DFSF.getShadow(*I), &CB));
+
+  // Adds variable argument shadows.
+  if (FT->isVarArg()) {
+    auto *LabelVATy = ArrayType::get(DFSF.DFS.PrimitiveShadowTy,
+                                     CB.arg_size() - FT->getNumParams());
+    auto *LabelVAAlloca =
+        new AllocaInst(LabelVATy, getDataLayout().getAllocaAddrSpace(),
+                       "labelva", &DFSF.F->getEntryBlock().front());
+
+    for (unsigned N = 0; I != CB.arg_end(); ++I, ++N) {
+      auto *LabelVAPtr = IRB.CreateStructGEP(LabelVATy, LabelVAAlloca, N);
+      IRB.CreateStore(DFSF.collapseToPrimitiveShadow(DFSF.getShadow(*I), &CB),
+                      LabelVAPtr);
+    }
+
+    Args.push_back(IRB.CreateStructGEP(LabelVATy, LabelVAAlloca, 0));
+  }
+
+  // Adds the return value shadow.
+  if (!FT->getReturnType()->isVoidTy()) {
+    if (!DFSF.LabelReturnAlloca) {
+      DFSF.LabelReturnAlloca = new AllocaInst(
+          DFSF.DFS.PrimitiveShadowTy, getDataLayout().getAllocaAddrSpace(),
+          "labelreturn", &DFSF.F->getEntryBlock().front());
+    }
+    Args.push_back(DFSF.LabelReturnAlloca);
+  }
+}
+
+void DFSanVisitor::addOriginArguments(Function &F, CallBase &CB,
+                                      std::vector<Value *> &Args,
+                                      IRBuilder<> &IRB) {
+  FunctionType *FT = F.getFunctionType();
+
+  auto *I = CB.arg_begin();
+
+  // Add non-variable argument origins.
+  for (unsigned N = FT->getNumParams(); N != 0; ++I, --N)
+    Args.push_back(DFSF.getOrigin(*I));
+
+  // Add variable argument origins.
+  if (FT->isVarArg()) {
+    auto *OriginVATy =
+        ArrayType::get(DFSF.DFS.OriginTy, CB.arg_size() - FT->getNumParams());
+    auto *OriginVAAlloca =
+        new AllocaInst(OriginVATy, getDataLayout().getAllocaAddrSpace(),
+                       "originva", &DFSF.F->getEntryBlock().front());
+
+    for (unsigned N = 0; I != CB.arg_end(); ++I, ++N) {
+      auto *OriginVAPtr = IRB.CreateStructGEP(OriginVATy, OriginVAAlloca, N);
+      IRB.CreateStore(DFSF.getOrigin(*I), OriginVAPtr);
+    }
+
+    Args.push_back(IRB.CreateStructGEP(OriginVATy, OriginVAAlloca, 0));
+  }
+
+  // Add the return value origin.
+  if (!FT->getReturnType()->isVoidTy()) {
+    if (!DFSF.OriginReturnAlloca) {
+      DFSF.OriginReturnAlloca = new AllocaInst(
+          DFSF.DFS.OriginTy, getDataLayout().getAllocaAddrSpace(),
+          "originreturn", &DFSF.F->getEntryBlock().front());
+    }
+    Args.push_back(DFSF.OriginReturnAlloca);
+  }
+}
+
+bool DFSanVisitor::visitWrappedCallBase(Function &F, CallBase &CB) {
+  IRBuilder<> IRB(&CB);
+  switch (DFSF.DFS.getWrapperKind(&F)) {
+  case DataFlowSanitizer::WK_Warning:
+    CB.setCalledFunction(&F);
+    IRB.CreateCall(DFSF.DFS.DFSanUnimplementedFn,
+                   IRB.CreateGlobalStringPtr(F.getName()));
+    DFSF.DFS.buildExternWeakCheckIfNeeded(IRB, &F);
+    DFSF.setShadow(&CB, DFSF.DFS.getZeroShadow(&CB));
+    DFSF.setOrigin(&CB, DFSF.DFS.ZeroOrigin);
+    return true;
+  case DataFlowSanitizer::WK_Discard:
+    CB.setCalledFunction(&F);
+    DFSF.DFS.buildExternWeakCheckIfNeeded(IRB, &F);
+    DFSF.setShadow(&CB, DFSF.DFS.getZeroShadow(&CB));
+    DFSF.setOrigin(&CB, DFSF.DFS.ZeroOrigin);
+    return true;
+  case DataFlowSanitizer::WK_Functional:
+    CB.setCalledFunction(&F);
+    DFSF.DFS.buildExternWeakCheckIfNeeded(IRB, &F);
+    visitInstOperands(CB);
+    return true;
+  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.
+    CallInst *CI = dyn_cast<CallInst>(&CB);
+    if (!CI)
+      return false;
+
+    const bool ShouldTrackOrigins = DFSF.DFS.shouldTrackOrigins();
+    FunctionType *FT = F.getFunctionType();
+    TransformedFunction CustomFn = DFSF.DFS.getCustomFunctionType(FT);
+    std::string CustomFName = ShouldTrackOrigins ? "__dfso_" : "__dfsw_";
+    CustomFName += F.getName();
+    FunctionCallee CustomF = DFSF.DFS.Mod->getOrInsertFunction(
+        CustomFName, CustomFn.TransformedType);
+    if (Function *CustomFn = dyn_cast<Function>(CustomF.getCallee())) {
+      CustomFn->copyAttributesFrom(&F);
+
+      // Custom functions returning non-void will write to the return label.
+      if (!FT->getReturnType()->isVoidTy()) {
+        CustomFn->removeFnAttrs(DFSF.DFS.ReadOnlyNoneAttrs);
+      }
+    }
+
+    std::vector<Value *> Args;
+
+    // Adds non-variable arguments.
+    auto *I = CB.arg_begin();
+    for (unsigned N = FT->getNumParams(); N != 0; ++I, --N) {
+      Args.push_back(*I);
+    }
+
+    // Adds shadow arguments.
+    const unsigned ShadowArgStart = Args.size();
+    addShadowArguments(F, CB, Args, IRB);
+
+    // Adds origin arguments.
+    const unsigned OriginArgStart = Args.size();
+    if (ShouldTrackOrigins)
+      addOriginArguments(F, CB, Args, IRB);
+
+    // Adds variable arguments.
+    append_range(Args, drop_begin(CB.args(), FT->getNumParams()));
+
+    CallInst *CustomCI = IRB.CreateCall(CustomF, Args);
+    CustomCI->setCallingConv(CI->getCallingConv());
+    CustomCI->setAttributes(transformFunctionAttributes(
+        CustomFn, CI->getContext(), CI->getAttributes()));
+
+    // Update the parameter attributes of the custom call instruction to
+    // zero extend the shadow parameters. This is required for targets
+    // which consider PrimitiveShadowTy an illegal type.
+    for (unsigned N = 0; N < FT->getNumParams(); N++) {
+      const unsigned ArgNo = ShadowArgStart + N;
+      if (CustomCI->getArgOperand(ArgNo)->getType() ==
+          DFSF.DFS.PrimitiveShadowTy)
+        CustomCI->addParamAttr(ArgNo, Attribute::ZExt);
+      if (ShouldTrackOrigins) {
+        const unsigned OriginArgNo = OriginArgStart + N;
+        if (CustomCI->getArgOperand(OriginArgNo)->getType() ==
+            DFSF.DFS.OriginTy)
+          CustomCI->addParamAttr(OriginArgNo, Attribute::ZExt);
+      }
+    }
+
+    // Loads the return value shadow and origin.
+    if (!FT->getReturnType()->isVoidTy()) {
+      LoadInst *LabelLoad =
+          IRB.CreateLoad(DFSF.DFS.PrimitiveShadowTy, DFSF.LabelReturnAlloca);
+      DFSF.setShadow(CustomCI, DFSF.expandFromPrimitiveShadow(
+                                   FT->getReturnType(), LabelLoad, &CB));
+      if (ShouldTrackOrigins) {
+        LoadInst *OriginLoad =
+            IRB.CreateLoad(DFSF.DFS.OriginTy, DFSF.OriginReturnAlloca);
+        DFSF.setOrigin(CustomCI, OriginLoad);
+      }
+    }
+
+    CI->replaceAllUsesWith(CustomCI);
+    CI->eraseFromParent();
+    return true;
+  }
+  return false;
+}
+
+Value *DFSanVisitor::makeAddAcquireOrderingTable(IRBuilder<> &IRB) {
+  constexpr int NumOrderings = (int)AtomicOrderingCABI::seq_cst + 1;
+  uint32_t OrderingTable[NumOrderings] = {};
+
+  OrderingTable[(int)AtomicOrderingCABI::relaxed] =
+      OrderingTable[(int)AtomicOrderingCABI::acquire] =
+          OrderingTable[(int)AtomicOrderingCABI::consume] =
+              (int)AtomicOrderingCABI::acquire;
+  OrderingTable[(int)AtomicOrderingCABI::release] =
+      OrderingTable[(int)AtomicOrderingCABI::acq_rel] =
+          (int)AtomicOrderingCABI::acq_rel;
+  OrderingTable[(int)AtomicOrderingCABI::seq_cst] =
+      (int)AtomicOrderingCABI::seq_cst;
+
+  return ConstantDataVector::get(IRB.getContext(),
+                                 ArrayRef(OrderingTable, NumOrderings));
+}
+
+void DFSanVisitor::visitLibAtomicLoad(CallBase &CB) {
+  // Since we use getNextNode here, we can't have CB terminate the BB.
+  assert(isa<CallInst>(CB));
+
+  IRBuilder<> IRB(&CB);
+  Value *Size = CB.getArgOperand(0);
+  Value *SrcPtr = CB.getArgOperand(1);
+  Value *DstPtr = CB.getArgOperand(2);
+  Value *Ordering = CB.getArgOperand(3);
+  // Convert the call to have at least Acquire ordering to make sure
+  // the shadow operations aren't reordered before it.
+  Value *NewOrdering =
+      IRB.CreateExtractElement(makeAddAcquireOrderingTable(IRB), Ordering);
+  CB.setArgOperand(3, NewOrdering);
+
+  IRBuilder<> NextIRB(CB.getNextNode());
+  NextIRB.SetCurrentDebugLocation(CB.getDebugLoc());
+
+  // TODO: Support ClCombinePointerLabelsOnLoad
+  // TODO: Support ClEventCallbacks
+
+  NextIRB.CreateCall(DFSF.DFS.DFSanMemShadowOriginTransferFn,
+                     {NextIRB.CreatePointerCast(DstPtr, NextIRB.getInt8PtrTy()),
+                      NextIRB.CreatePointerCast(SrcPtr, NextIRB.getInt8PtrTy()),
+                      NextIRB.CreateIntCast(Size, DFSF.DFS.IntptrTy, false)});
+}
+
+Value *DFSanVisitor::makeAddReleaseOrderingTable(IRBuilder<> &IRB) {
+  constexpr int NumOrderings = (int)AtomicOrderingCABI::seq_cst + 1;
+  uint32_t OrderingTable[NumOrderings] = {};
+
+  OrderingTable[(int)AtomicOrderingCABI::relaxed] =
+      OrderingTable[(int)AtomicOrderingCABI::release] =
+          (int)AtomicOrderingCABI::release;
+  OrderingTable[(int)AtomicOrderingCABI::consume] =
+      OrderingTable[(int)AtomicOrderingCABI::acquire] =
+          OrderingTable[(int)AtomicOrderingCABI::acq_rel] =
+              (int)AtomicOrderingCABI::acq_rel;
+  OrderingTable[(int)AtomicOrderingCABI::seq_cst] =
+      (int)AtomicOrderingCABI::seq_cst;
+
+  return ConstantDataVector::get(IRB.getContext(),
+                                 ArrayRef(OrderingTable, NumOrderings));
+}
+
+void DFSanVisitor::visitLibAtomicStore(CallBase &CB) {
+  IRBuilder<> IRB(&CB);
+  Value *Size = CB.getArgOperand(0);
+  Value *SrcPtr = CB.getArgOperand(1);
+  Value *DstPtr = CB.getArgOperand(2);
+  Value *Ordering = CB.getArgOperand(3);
+  // Convert the call to have at least Release ordering to make sure
+  // the shadow operations aren't reordered after it.
+  Value *NewOrdering =
+      IRB.CreateExtractElement(makeAddReleaseOrderingTable(IRB), Ordering);
+  CB.setArgOperand(3, NewOrdering);
+
+  // TODO: Support ClCombinePointerLabelsOnStore
+  // TODO: Support ClEventCallbacks
+
+  IRB.CreateCall(DFSF.DFS.DFSanMemShadowOriginTransferFn,
+                 {IRB.CreatePointerCast(DstPtr, IRB.getInt8PtrTy()),
+                  IRB.CreatePointerCast(SrcPtr, IRB.getInt8PtrTy()),
+                  IRB.CreateIntCast(Size, DFSF.DFS.IntptrTy, false)});
+}
+
+void DFSanVisitor::visitLibAtomicExchange(CallBase &CB) {
+  // void __atomic_exchange(size_t size, void *ptr, void *val, void *ret, int
+  // ordering)
+  IRBuilder<> IRB(&CB);
+  Value *Size = CB.getArgOperand(0);
+  Value *TargetPtr = CB.getArgOperand(1);
+  Value *SrcPtr = CB.getArgOperand(2);
+  Value *DstPtr = CB.getArgOperand(3);
+
+  // This operation is not atomic for the shadow and origin memory.
+  // This could result in DFSan false positives or false negatives.
+  // For now we will assume these operations are rare, and
+  // the additional complexity to address this is not warrented.
+
+  // Current Target to Dest
+  IRB.CreateCall(DFSF.DFS.DFSanMemShadowOriginTransferFn,
+                 {IRB.CreatePointerCast(DstPtr, IRB.getInt8PtrTy()),
+                  IRB.CreatePointerCast(TargetPtr, IRB.getInt8PtrTy()),
+                  IRB.CreateIntCast(Size, DFSF.DFS.IntptrTy, false)});
+
+  // Current Src to Target (overriding)
+  IRB.CreateCall(DFSF.DFS.DFSanMemShadowOriginTransferFn,
+                 {IRB.CreatePointerCast(TargetPtr, IRB.getInt8PtrTy()),
+                  IRB.CreatePointerCast(SrcPtr, IRB.getInt8PtrTy()),
+                  IRB.CreateIntCast(Size, DFSF.DFS.IntptrTy, false)});
+}
+
+void DFSanVisitor::visitLibAtomicCompareExchange(CallBase &CB) {
+  // bool __atomic_compare_exchange(size_t size, void *ptr, void *expected, void
+  // *desired, int success_order, int failure_order)
+  Value *Size = CB.getArgOperand(0);
+  Value *TargetPtr = CB.getArgOperand(1);
+  Value *ExpectedPtr = CB.getArgOperand(2);
+  Value *DesiredPtr = CB.getArgOperand(3);
+
+  // This operation is not atomic for the shadow and origin memory.
+  // This could result in DFSan false positives or false negatives.
+  // For now we will assume these operations are rare, and
+  // the additional complexity to address this is not warrented.
+
+  IRBuilder<> NextIRB(CB.getNextNode());
+  NextIRB.SetCurrentDebugLocation(CB.getDebugLoc());
+
+  DFSF.setShadow(&CB, DFSF.DFS.getZeroShadow(&CB));
+
+  // If original call returned true, copy Desired to Target.
+  // If original call returned false, copy Target to Expected.
+  NextIRB.CreateCall(
+      DFSF.DFS.DFSanMemShadowOriginConditionalExchangeFn,
+      {NextIRB.CreateIntCast(&CB, NextIRB.getInt8Ty(), false),
+       NextIRB.CreatePointerCast(TargetPtr, NextIRB.getInt8PtrTy()),
+       NextIRB.CreatePointerCast(ExpectedPtr, NextIRB.getInt8PtrTy()),
+       NextIRB.CreatePointerCast(DesiredPtr, NextIRB.getInt8PtrTy()),
+       NextIRB.CreateIntCast(Size, DFSF.DFS.IntptrTy, false)});
+}
+
+void DFSanVisitor::visitCallBase(CallBase &CB) {
+  Function *F = CB.getCalledFunction();
+  if ((F && F->isIntrinsic()) || CB.isInlineAsm()) {
+    visitInstOperands(CB);
+    return;
+  }
+
+  // Calls to this function are synthesized in wrappers, and we shouldn't
+  // instrument them.
+  if (F == DFSF.DFS.DFSanVarargWrapperFn.getCallee()->stripPointerCasts())
+    return;
+
+  LibFunc LF;
+  if (DFSF.TLI.getLibFunc(CB, LF)) {
+    // libatomic.a functions need to have special handling because there isn't
+    // a good way to intercept them or compile the library with
+    // instrumentation.
+    switch (LF) {
+    case LibFunc_atomic_load:
+      if (!isa<CallInst>(CB)) {
+        llvm::errs() << "DFSAN -- cannot instrument invoke of libatomic load. "
+                        "Ignoring!\n";
+        break;
+      }
+      visitLibAtomicLoad(CB);
+      return;
+    case LibFunc_atomic_store:
+      visitLibAtomicStore(CB);
+      return;
+    default:
+      break;
+    }
+  }
+
+  // TODO: These are not supported by TLI? They are not in the enum.
+  if (F && F->hasName() && !F->isVarArg()) {
+    if (F->getName() == "__atomic_exchange") {
+      visitLibAtomicExchange(CB);
+      return;
+    }
+    if (F->getName() == "__atomic_compare_exchange") {
+      visitLibAtomicCompareExchange(CB);
+      return;
+    }
+  }
+
+  DenseMap<Value *, Function *>::iterator UnwrappedFnIt =
+      DFSF.DFS.UnwrappedFnMap.find(CB.getCalledOperand());
+  if (UnwrappedFnIt != DFSF.DFS.UnwrappedFnMap.end())
+    if (visitWrappedCallBase(*UnwrappedFnIt->second, CB))
+      return;
+
+  IRBuilder<> IRB(&CB);
+
+  const bool ShouldTrackOrigins = DFSF.DFS.shouldTrackOrigins();
+  FunctionType *FT = CB.getFunctionType();
+  const DataLayout &DL = getDataLayout();
+
+  // Stores argument shadows.
+  unsigned ArgOffset = 0;
+  for (unsigned I = 0, N = FT->getNumParams(); I != N; ++I) {
+    if (ShouldTrackOrigins) {
+      // Ignore overflowed origins
+      Value *ArgShadow = DFSF.getShadow(CB.getArgOperand(I));
+      if (I < DFSF.DFS.NumOfElementsInArgOrgTLS &&
+          !DFSF.DFS.isZeroShadow(ArgShadow))
+        IRB.CreateStore(DFSF.getOrigin(CB.getArgOperand(I)),
+                        DFSF.getArgOriginTLS(I, IRB));
+    }
+
+    unsigned Size =
+        DL.getTypeAllocSize(DFSF.DFS.getShadowTy(FT->getParamType(I)));
+    // Stop storing if arguments' size overflows. Inside a function, arguments
+    // after overflow have zero shadow values.
+    if (ArgOffset + Size > ArgTLSSize)
+      break;
+    IRB.CreateAlignedStore(DFSF.getShadow(CB.getArgOperand(I)),
+                           DFSF.getArgTLS(FT->getParamType(I), ArgOffset, IRB),
+                           ShadowTLSAlignment);
+    ArgOffset += alignTo(Size, ShadowTLSAlignment);
+  }
+
+  Instruction *Next = nullptr;
+  if (!CB.getType()->isVoidTy()) {
+    if (InvokeInst *II = dyn_cast<InvokeInst>(&CB)) {
+      if (II->getNormalDest()->getSinglePredecessor()) {
+        Next = &II->getNormalDest()->front();
+      } else {
+        BasicBlock *NewBB =
+            SplitEdge(II->getParent(), II->getNormalDest(), &DFSF.DT);
+        Next = &NewBB->front();
+      }
+    } else {
+      assert(CB.getIterator() != CB.getParent()->end());
+      Next = CB.getNextNode();
+    }
+
+    // Don't emit the epilogue for musttail call returns.
+    if (isa<CallInst>(CB) && cast<CallInst>(CB).isMustTailCall())
+      return;
+
+    // Loads the return value shadow.
+    IRBuilder<> NextIRB(Next);
+    unsigned Size = DL.getTypeAllocSize(DFSF.DFS.getShadowTy(&CB));
+    if (Size > RetvalTLSSize) {
+      // Set overflowed return shadow to be zero.
+      DFSF.setShadow(&CB, DFSF.DFS.getZeroShadow(&CB));
+    } else {
+      LoadInst *LI = NextIRB.CreateAlignedLoad(
+          DFSF.DFS.getShadowTy(&CB), DFSF.getRetvalTLS(CB.getType(), NextIRB),
+          ShadowTLSAlignment, "_dfsret");
+      DFSF.SkipInsts.insert(LI);
+      DFSF.setShadow(&CB, LI);
+      DFSF.NonZeroChecks.push_back(LI);
+    }
+
+    if (ShouldTrackOrigins) {
+      LoadInst *LI = NextIRB.CreateLoad(DFSF.DFS.OriginTy,
+                                        DFSF.getRetvalOriginTLS(), "_dfsret_o");
+      DFSF.SkipInsts.insert(LI);
+      DFSF.setOrigin(&CB, LI);
+    }
+
+    DFSF.addReachesFunctionCallbacksIfEnabled(NextIRB, CB, &CB);
+  }
+}
+
+void DFSanVisitor::visitPHINode(PHINode &PN) {
+  Type *ShadowTy = DFSF.DFS.getShadowTy(&PN);
+  PHINode *ShadowPN =
+      PHINode::Create(ShadowTy, PN.getNumIncomingValues(), "", &PN);
+
+  // Give the shadow phi node valid predecessors to fool SplitEdge into working.
+  Value *UndefShadow = UndefValue::get(ShadowTy);
+  for (BasicBlock *BB : PN.blocks())
+    ShadowPN->addIncoming(UndefShadow, BB);
+
+  DFSF.setShadow(&PN, ShadowPN);
+
+  PHINode *OriginPN = nullptr;
+  if (DFSF.DFS.shouldTrackOrigins()) {
+    OriginPN =
+        PHINode::Create(DFSF.DFS.OriginTy, PN.getNumIncomingValues(), "", &PN);
+    Value *UndefOrigin = UndefValue::get(DFSF.DFS.OriginTy);
+    for (BasicBlock *BB : PN.blocks())
+      OriginPN->addIncoming(UndefOrigin, BB);
+    DFSF.setOrigin(&PN, OriginPN);
+  }
+
+  DFSF.PHIFixups.push_back({&PN, ShadowPN, OriginPN});
+}
+
+PreservedAnalyses DataFlowSanitizerPass::run(Module &M,
+                                             ModuleAnalysisManager &AM) {
+  auto GetTLI = [&](Function &F) -> TargetLibraryInfo & {
+    auto &FAM =
+        AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
+    return FAM.getResult<TargetLibraryAnalysis>(F);
+  };
+  if (!DataFlowSanitizer(ABIListFiles).runImpl(M, GetTLI))
+    return PreservedAnalyses::all();
+
+  PreservedAnalyses PA = PreservedAnalyses::none();
+  // GlobalsAA is considered stateless and does not get invalidated unless
+  // explicitly invalidated; PreservedAnalyses::none() is not enough. Sanitizers
+  // make changes that require GlobalsAA to be invalidated.
+  PA.abandon<GlobalsAA>();
+  return PA;
+}