lib/Transforms/Instrumentation/DataFlowSanitizer.cpp

   1 //===- DataFlowSanitizer.cpp - dynamic data flow analysis -----------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 /// \file
  10 /// This file is a part of DataFlowSanitizer, a generalised dynamic data flow
  11 /// analysis.
  12 ///
  13 /// Unlike other Sanitizer tools, this tool is not designed to detect a specific
  14 /// class of bugs on its own.  Instead, it provides a generic dynamic data flow
  15 /// analysis framework to be used by clients to help detect application-specific
  16 /// issues within their own code.
  17 ///
  18 /// The analysis is based on automatic propagation of data flow labels (also
  19 /// known as taint labels) through a program as it performs computation.  Each
  20 /// byte of application memory is backed by two bytes of shadow memory which
  21 /// hold the label.  On Linux/x86_64, memory is laid out as follows:
  22 ///
  23 /// +--------------------+ 0x800000000000 (top of memory)
  24 /// | application memory |
  25 /// +--------------------+ 0x700000008000 (kAppAddr)
  26 /// |                    |
  27 /// |       unused       |
  28 /// |                    |
  29 /// +--------------------+ 0x200200000000 (kUnusedAddr)
  30 /// |    union table     |
  31 /// +--------------------+ 0x200000000000 (kUnionTableAddr)
  32 /// |   shadow memory    |
  33 /// +--------------------+ 0x000000010000 (kShadowAddr)
  34 /// | reserved by kernel |
  35 /// +--------------------+ 0x000000000000
  36 ///
  37 /// To derive a shadow memory address from an application memory address,
  38 /// bits 44-46 are cleared to bring the address into the range
  39 /// [0x000000008000,0x100000000000).  Then the address is shifted left by 1 to
  40 /// account for the double byte representation of shadow labels and move the
  41 /// address into the shadow memory range.  See the function
  42 /// DataFlowSanitizer::getShadowAddress below.
  43 ///
  44 /// For more information, please refer to the design document:
  45 /// http://clang.llvm.org/docs/DataFlowSanitizerDesign.html
  46 //
  47 //===----------------------------------------------------------------------===//
  48
  49 #include "llvm/ADT/DenseMap.h"
  50 #include "llvm/ADT/DenseSet.h"
  51 #include "llvm/ADT/DepthFirstIterator.h"
  52 #include "llvm/ADT/None.h"
  53 #include "llvm/ADT/SmallPtrSet.h"
  54 #include "llvm/ADT/SmallVector.h"
  55 #include "llvm/ADT/StringExtras.h"
  56 #include "llvm/ADT/StringRef.h"
  57 #include "llvm/ADT/Triple.h"
  58 #include "llvm/Transforms/Utils/Local.h"
  59 #include "llvm/Analysis/ValueTracking.h"
  60 #include "llvm/IR/Argument.h"
  61 #include "llvm/IR/Attributes.h"
  62 #include "llvm/IR/BasicBlock.h"
  63 #include "llvm/IR/CallSite.h"
  64 #include "llvm/IR/Constant.h"
  65 #include "llvm/IR/Constants.h"
  66 #include "llvm/IR/DataLayout.h"
  67 #include "llvm/IR/DerivedTypes.h"
  68 #include "llvm/IR/Dominators.h"
  69 #include "llvm/IR/Function.h"
  70 #include "llvm/IR/GlobalAlias.h"
  71 #include "llvm/IR/GlobalValue.h"
  72 #include "llvm/IR/GlobalVariable.h"
  73 #include "llvm/IR/IRBuilder.h"
  74 #include "llvm/IR/InlineAsm.h"
  75 #include "llvm/IR/InstVisitor.h"
  76 #include "llvm/IR/InstrTypes.h"
  77 #include "llvm/IR/Instruction.h"
  78 #include "llvm/IR/Instructions.h"
  79 #include "llvm/IR/IntrinsicInst.h"
  80 #include "llvm/IR/LLVMContext.h"
  81 #include "llvm/IR/MDBuilder.h"
  82 #include "llvm/IR/Module.h"
  83 #include "llvm/IR/Type.h"
  84 #include "llvm/IR/User.h"
  85 #include "llvm/IR/Value.h"
  86 #include "llvm/Pass.h"
  87 #include "llvm/Support/Casting.h"
  88 #include "llvm/Support/CommandLine.h"
  89 #include "llvm/Support/ErrorHandling.h"
  90 #include "llvm/Support/SpecialCaseList.h"
  91 #include "llvm/Transforms/Instrumentation.h"
  92 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
  93 #include <algorithm>
  94 #include <cassert>
  95 #include <cstddef>
  96 #include <cstdint>
  97 #include <iterator>
  98 #include <memory>
  99 #include <set>
 100 #include <string>
 101 #include <utility>
 102 #include <vector>
 103
 104 using namespace llvm;
 105
 106 // External symbol to be used when generating the shadow address for
 107 // architectures with multiple VMAs. Instead of using a constant integer
 108 // the runtime will set the external mask based on the VMA range.
 109 static const char *const kDFSanExternShadowPtrMask = "__dfsan_shadow_ptr_mask";
 110
 111 // The -dfsan-preserve-alignment flag controls whether this pass assumes that
 112 // alignment requirements provided by the input IR are correct.  For example,
 113 // if the input IR contains a load with alignment 8, this flag will cause
 114 // the shadow load to have alignment 16.  This flag is disabled by default as
 115 // we have unfortunately encountered too much code (including Clang itself;
 116 // see PR14291) which performs misaligned access.
 117 static cl::opt<bool> ClPreserveAlignment(
 118     "dfsan-preserve-alignment",
 119     cl::desc("respect alignment requirements provided by input IR"), cl::Hidden,
 120     cl::init(false));
 121
 122 // The ABI list files control how shadow parameters are passed. The pass treats
 123 // every function labelled "uninstrumented" in the ABI list file as conforming
 124 // to the "native" (i.e. unsanitized) ABI.  Unless the ABI list contains
 125 // additional annotations for those functions, a call to one of those functions
 126 // will produce a warning message, as the labelling behaviour of the function is
 127 // unknown.  The other supported annotations are "functional" and "discard",
 128 // which are described below under DataFlowSanitizer::WrapperKind.
 129 static cl::list<std::string> ClABIListFiles(
 130     "dfsan-abilist",
 131     cl::desc("File listing native ABI functions and how the pass treats them"),
 132     cl::Hidden);
 133
 134 // Controls whether the pass uses IA_Args or IA_TLS as the ABI for instrumented
 135 // functions (see DataFlowSanitizer::InstrumentedABI below).
 136 static cl::opt<bool> ClArgsABI(
 137     "dfsan-args-abi",
 138     cl::desc("Use the argument ABI rather than the TLS ABI"),
 139     cl::Hidden);
 140
 141 // Controls whether the pass includes or ignores the labels of pointers in load
 142 // instructions.
 143 static cl::opt<bool> ClCombinePointerLabelsOnLoad(
 144     "dfsan-combine-pointer-labels-on-load",
 145     cl::desc("Combine the label of the pointer with the label of the data when "
 146              "loading from memory."),
 147     cl::Hidden, cl::init(true));
 148
 149 // Controls whether the pass includes or ignores the labels of pointers in
 150 // stores instructions.
 151 static cl::opt<bool> ClCombinePointerLabelsOnStore(
 152     "dfsan-combine-pointer-labels-on-store",
 153     cl::desc("Combine the label of the pointer with the label of the data when "
 154              "storing in memory."),
 155     cl::Hidden, cl::init(false));
 156
 157 static cl::opt<bool> ClDebugNonzeroLabels(
 158     "dfsan-debug-nonzero-labels",
 159     cl::desc("Insert calls to __dfsan_nonzero_label on observing a parameter, "
 160              "load or return with a nonzero label"),
 161     cl::Hidden);
 162
 163 static StringRef GetGlobalTypeString(const GlobalValue &G) {
 164   // Types of GlobalVariables are always pointer types.
 165   Type *GType = G.getValueType();
 166   // For now we support blacklisting struct types only.
 167   if (StructType *SGType = dyn_cast<StructType>(GType)) {
 168     if (!SGType->isLiteral())
 169       return SGType->getName();
 170   }
 171   return "<unknown type>";
 172 }
 173
 174 namespace {
 175
 176 class DFSanABIList {
 177   std::unique_ptr<SpecialCaseList> SCL;
 178
 179  public:
 180   DFSanABIList() = default;
 181
 182   void set(std::unique_ptr<SpecialCaseList> List) { SCL = std::move(List); }
 183
 184   /// Returns whether either this function or its source file are listed in the
 185   /// given category.
 186   bool isIn(const Function &F, StringRef Category) const {
 187     return isIn(*F.getParent(), Category) ||
 188            SCL->inSection("dataflow", "fun", F.getName(), Category);
 189   }
 190
 191   /// Returns whether this global alias is listed in the given category.
 192   ///
 193   /// If GA aliases a function, the alias's name is matched as a function name
 194   /// would be.  Similarly, aliases of globals are matched like globals.
 195   bool isIn(const GlobalAlias &GA, StringRef Category) const {
 196     if (isIn(*GA.getParent(), Category))
 197       return true;
 198
 199     if (isa<FunctionType>(GA.getValueType()))
 200       return SCL->inSection("dataflow", "fun", GA.getName(), Category);
 201
 202     return SCL->inSection("dataflow", "global", GA.getName(), Category) ||
 203            SCL->inSection("dataflow", "type", GetGlobalTypeString(GA),
 204                           Category);
 205   }
 206
 207   /// Returns whether this module is listed in the given category.
 208   bool isIn(const Module &M, StringRef Category) const {
 209     return SCL->inSection("dataflow", "src", M.getModuleIdentifier(), Category);
 210   }
 211 };
 212
 213 /// TransformedFunction is used to express the result of transforming one
 214 /// function type into another.  This struct is immutable.  It holds metadata
 215 /// useful for updating calls of the old function to the new type.
 216 struct TransformedFunction {
 217   TransformedFunction(FunctionType* OriginalType,
 218                       FunctionType* TransformedType,
 219                       std::vector<unsigned> ArgumentIndexMapping)
 220       : OriginalType(OriginalType),
 221         TransformedType(TransformedType),
 222         ArgumentIndexMapping(ArgumentIndexMapping) {}
 223
 224   // Disallow copies.
 225   TransformedFunction(const TransformedFunction&) = delete;
 226   TransformedFunction& operator=(const TransformedFunction&) = delete;
 227
 228   // Allow moves.
 229   TransformedFunction(TransformedFunction&&) = default;
 230   TransformedFunction& operator=(TransformedFunction&&) = default;
 231
 232   /// Type of the function before the transformation.
 233   FunctionType *OriginalType;
 234
 235   /// Type of the function after the transformation.
 236   FunctionType *TransformedType;
 237
 238   /// Transforming a function may change the position of arguments.  This
 239   /// member records the mapping from each argument's old position to its new
 240   /// position.  Argument positions are zero-indexed.  If the transformation
 241   /// from F to F' made the first argument of F into the third argument of F',
 242   /// then ArgumentIndexMapping[0] will equal 2.
 243   std::vector<unsigned> ArgumentIndexMapping;
 244 };
 245
 246 /// Given function attributes from a call site for the original function,
 247 /// return function attributes appropriate for a call to the transformed
 248 /// function.
 249 AttributeList TransformFunctionAttributes(
 250     const TransformedFunction& TransformedFunction,
 251     LLVMContext& Ctx, AttributeList CallSiteAttrs) {
 252
 253   // Construct a vector of AttributeSet for each function argument.
 254   std::vector<llvm::AttributeSet> ArgumentAttributes(
 255       TransformedFunction.TransformedType->getNumParams());
 256
 257   // Copy attributes from the parameter of the original function to the
 258   // transformed version.  'ArgumentIndexMapping' holds the mapping from
 259   // old argument position to new.
 260   for (unsigned i=0, ie = TransformedFunction.ArgumentIndexMapping.size();
 261        i < ie; ++i) {
 262     unsigned TransformedIndex = TransformedFunction.ArgumentIndexMapping[i];
 263     ArgumentAttributes[TransformedIndex] = CallSiteAttrs.getParamAttributes(i);
 264   }
 265
 266   // Copy annotations on varargs arguments.
 267   for (unsigned i = TransformedFunction.OriginalType->getNumParams(),
 268        ie = CallSiteAttrs.getNumAttrSets(); i<ie; ++i) {
 269     ArgumentAttributes.push_back(CallSiteAttrs.getParamAttributes(i));
 270   }
 271
 272   return AttributeList::get(
 273       Ctx,
 274       CallSiteAttrs.getFnAttributes(),
 275       CallSiteAttrs.getRetAttributes(),
 276       llvm::makeArrayRef(ArgumentAttributes));
 277 }
 278
 279 class DataFlowSanitizer : public ModulePass {
 280   friend struct DFSanFunction;
 281   friend class DFSanVisitor;
 282
 283   enum {
 284     ShadowWidth = 16
 285   };
 286
 287   /// Which ABI should be used for instrumented functions?
 288   enum InstrumentedABI {
 289     /// Argument and return value labels are passed through additional
 290     /// arguments and by modifying the return type.
 291     IA_Args,
 292
 293     /// Argument and return value labels are passed through TLS variables
 294     /// __dfsan_arg_tls and __dfsan_retval_tls.
 295     IA_TLS
 296   };
 297
 298   /// How should calls to uninstrumented functions be handled?
 299   enum WrapperKind {
 300     /// This function is present in an uninstrumented form but we don't know
 301     /// how it should be handled.  Print a warning and call the function anyway.
 302     /// Don't label the return value.
 303     WK_Warning,
 304
 305     /// This function does not write to (user-accessible) memory, and its return
 306     /// value is unlabelled.
 307     WK_Discard,
 308
 309     /// This function does not write to (user-accessible) memory, and the label
 310     /// of its return value is the union of the label of its arguments.
 311     WK_Functional,
 312
 313     /// Instead of calling the function, a custom wrapper __dfsw_F is called,
 314     /// where F is the name of the function.  This function may wrap the
 315     /// original function or provide its own implementation.  This is similar to
 316     /// the IA_Args ABI, except that IA_Args uses a struct return type to
 317     /// pass the return value shadow in a register, while WK_Custom uses an
 318     /// extra pointer argument to return the shadow.  This allows the wrapped
 319     /// form of the function type to be expressed in C.
 320     WK_Custom
 321   };
 322
 323   Module *Mod;
 324   LLVMContext *Ctx;
 325   IntegerType *ShadowTy;
 326   PointerType *ShadowPtrTy;
 327   IntegerType *IntptrTy;
 328   ConstantInt *ZeroShadow;
 329   ConstantInt *ShadowPtrMask;
 330   ConstantInt *ShadowPtrMul;
 331   Constant *ArgTLS;
 332   Constant *RetvalTLS;
 333   void *(*GetArgTLSPtr)();
 334   void *(*GetRetvalTLSPtr)();
 335   FunctionType *GetArgTLSTy;
 336   FunctionType *GetRetvalTLSTy;
 337   Constant *GetArgTLS;
 338   Constant *GetRetvalTLS;
 339   Constant *ExternalShadowMask;
 340   FunctionType *DFSanUnionFnTy;
 341   FunctionType *DFSanUnionLoadFnTy;
 342   FunctionType *DFSanUnimplementedFnTy;
 343   FunctionType *DFSanSetLabelFnTy;
 344   FunctionType *DFSanNonzeroLabelFnTy;
 345   FunctionType *DFSanVarargWrapperFnTy;
 346   FunctionCallee DFSanUnionFn;
 347   FunctionCallee DFSanCheckedUnionFn;
 348   FunctionCallee DFSanUnionLoadFn;
 349   FunctionCallee DFSanUnimplementedFn;
 350   FunctionCallee DFSanSetLabelFn;
 351   FunctionCallee DFSanNonzeroLabelFn;
 352   FunctionCallee DFSanVarargWrapperFn;
 353   MDNode *ColdCallWeights;
 354   DFSanABIList ABIList;
 355   DenseMap<Value *, Function *> UnwrappedFnMap;
 356   AttrBuilder ReadOnlyNoneAttrs;
 357   bool DFSanRuntimeShadowMask = false;
 358
 359   Value *getShadowAddress(Value *Addr, Instruction *Pos);
 360   bool isInstrumented(const Function *F);
 361   bool isInstrumented(const GlobalAlias *GA);
 362   FunctionType *getArgsFunctionType(FunctionType *T);
 363   FunctionType *getTrampolineFunctionType(FunctionType *T);
 364   TransformedFunction getCustomFunctionType(FunctionType *T);
 365   InstrumentedABI getInstrumentedABI();
 366   WrapperKind getWrapperKind(Function *F);
 367   void addGlobalNamePrefix(GlobalValue *GV);
 368   Function *buildWrapperFunction(Function *F, StringRef NewFName,
 369                                  GlobalValue::LinkageTypes NewFLink,
 370                                  FunctionType *NewFT);
 371   Constant *getOrBuildTrampolineFunction(FunctionType *FT, StringRef FName);
 372
 373 public:
 374   static char ID;
 375
 376   DataFlowSanitizer(
 377       const std::vector<std::string> &ABIListFiles = std::vector<std::string>(),
 378       void *(*getArgTLS)() = nullptr, void *(*getRetValTLS)() = nullptr);
 379
 380   bool doInitialization(Module &M) override;
 381   bool runOnModule(Module &M) override;
 382 };
 383
 384 struct DFSanFunction {
 385   DataFlowSanitizer &DFS;
 386   Function *F;
 387   DominatorTree DT;
 388   DataFlowSanitizer::InstrumentedABI IA;
 389   bool IsNativeABI;
 390   Value *ArgTLSPtr = nullptr;
 391   Value *RetvalTLSPtr = nullptr;
 392   AllocaInst *LabelReturnAlloca = nullptr;
 393   DenseMap<Value *, Value *> ValShadowMap;
 394   DenseMap<AllocaInst *, AllocaInst *> AllocaShadowMap;
 395   std::vector<std::pair<PHINode *, PHINode *>> PHIFixups;
 396   DenseSet<Instruction *> SkipInsts;
 397   std::vector<Value *> NonZeroChecks;
 398   bool AvoidNewBlocks;
 399
 400   struct CachedCombinedShadow {
 401     BasicBlock *Block;
 402     Value *Shadow;
 403   };
 404   DenseMap<std::pair<Value *, Value *>, CachedCombinedShadow>
 405       CachedCombinedShadows;
 406   DenseMap<Value *, std::set<Value *>> ShadowElements;
 407
 408   DFSanFunction(DataFlowSanitizer &DFS, Function *F, bool IsNativeABI)
 409       : DFS(DFS), F(F), IA(DFS.getInstrumentedABI()), IsNativeABI(IsNativeABI) {
 410     DT.recalculate(*F);
 411     // FIXME: Need to track down the register allocator issue which causes poor
 412     // performance in pathological cases with large numbers of basic blocks.
 413     AvoidNewBlocks = F->size() > 1000;
 414   }
 415
 416   Value *getArgTLSPtr();
 417   Value *getArgTLS(unsigned Index, Instruction *Pos);
 418   Value *getRetvalTLS();
 419   Value *getShadow(Value *V);
 420   void setShadow(Instruction *I, Value *Shadow);
 421   Value *combineShadows(Value *V1, Value *V2, Instruction *Pos);
 422   Value *combineOperandShadows(Instruction *Inst);
 423   Value *loadShadow(Value *ShadowAddr, uint64_t Size, uint64_t Align,
 424                     Instruction *Pos);
 425   void storeShadow(Value *Addr, uint64_t Size, uint64_t Align, Value *Shadow,
 426                    Instruction *Pos);
 427 };
 428
 429 class DFSanVisitor : public InstVisitor<DFSanVisitor> {
 430 public:
 431   DFSanFunction &DFSF;
 432
 433   DFSanVisitor(DFSanFunction &DFSF) : DFSF(DFSF) {}
 434
 435   const DataLayout &getDataLayout() const {
 436     return DFSF.F->getParent()->getDataLayout();
 437   }
 438
 439   void visitOperandShadowInst(Instruction &I);
 440   void visitUnaryOperator(UnaryOperator &UO);
 441   void visitBinaryOperator(BinaryOperator &BO);
 442   void visitCastInst(CastInst &CI);
 443   void visitCmpInst(CmpInst &CI);
 444   void visitGetElementPtrInst(GetElementPtrInst &GEPI);
 445   void visitLoadInst(LoadInst &LI);
 446   void visitStoreInst(StoreInst &SI);
 447   void visitReturnInst(ReturnInst &RI);
 448   void visitCallSite(CallSite CS);
 449   void visitPHINode(PHINode &PN);
 450   void visitExtractElementInst(ExtractElementInst &I);
 451   void visitInsertElementInst(InsertElementInst &I);
 452   void visitShuffleVectorInst(ShuffleVectorInst &I);
 453   void visitExtractValueInst(ExtractValueInst &I);
 454   void visitInsertValueInst(InsertValueInst &I);
 455   void visitAllocaInst(AllocaInst &I);
 456   void visitSelectInst(SelectInst &I);
 457   void visitMemSetInst(MemSetInst &I);
 458   void visitMemTransferInst(MemTransferInst &I);
 459 };
 460
 461 } // end anonymous namespace
 462
 463 char DataFlowSanitizer::ID;
 464
 465 INITIALIZE_PASS(DataFlowSanitizer, "dfsan",
 466                 "DataFlowSanitizer: dynamic data flow analysis.", false, false)
 467
 468 ModulePass *
 469 llvm::createDataFlowSanitizerPass(const std::vector<std::string> &ABIListFiles,
 470                                   void *(*getArgTLS)(),
 471                                   void *(*getRetValTLS)()) {
 472   return new DataFlowSanitizer(ABIListFiles, getArgTLS, getRetValTLS);
 473 }
 474
 475 DataFlowSanitizer::DataFlowSanitizer(
 476     const std::vector<std::string> &ABIListFiles, void *(*getArgTLS)(),
 477     void *(*getRetValTLS)())
 478     : ModulePass(ID), GetArgTLSPtr(getArgTLS), GetRetvalTLSPtr(getRetValTLS) {
 479   std::vector<std::string> AllABIListFiles(std::move(ABIListFiles));
 480   AllABIListFiles.insert(AllABIListFiles.end(), ClABIListFiles.begin(),
 481                          ClABIListFiles.end());
 482   ABIList.set(SpecialCaseList::createOrDie(AllABIListFiles));
 483 }
 484
 485 FunctionType *DataFlowSanitizer::getArgsFunctionType(FunctionType *T) {
 486   SmallVector<Type *, 4> ArgTypes(T->param_begin(), T->param_end());
 487   ArgTypes.append(T->getNumParams(), ShadowTy);
 488   if (T->isVarArg())
 489     ArgTypes.push_back(ShadowPtrTy);
 490   Type *RetType = T->getReturnType();
 491   if (!RetType->isVoidTy())
 492     RetType = StructType::get(RetType, ShadowTy);
 493   return FunctionType::get(RetType, ArgTypes, T->isVarArg());
 494 }
 495
 496 FunctionType *DataFlowSanitizer::getTrampolineFunctionType(FunctionType *T) {
 497   assert(!T->isVarArg());
 498   SmallVector<Type *, 4> ArgTypes;
 499   ArgTypes.push_back(T->getPointerTo());
 500   ArgTypes.append(T->param_begin(), T->param_end());
 501   ArgTypes.append(T->getNumParams(), ShadowTy);
 502   Type *RetType = T->getReturnType();
 503   if (!RetType->isVoidTy())
 504     ArgTypes.push_back(ShadowPtrTy);
 505   return FunctionType::get(T->getReturnType(), ArgTypes, false);
 506 }
 507
 508 TransformedFunction DataFlowSanitizer::getCustomFunctionType(FunctionType *T) {
 509   SmallVector<Type *, 4> ArgTypes;
 510
 511   // Some parameters of the custom function being constructed are
 512   // parameters of T.  Record the mapping from parameters of T to
 513   // parameters of the custom function, so that parameter attributes
 514   // at call sites can be updated.
 515   std::vector<unsigned> ArgumentIndexMapping;
 516   for (unsigned i = 0, ie = T->getNumParams(); i != ie; ++i) {
 517     Type* param_type = T->getParamType(i);
 518     FunctionType *FT;
 519     if (isa<PointerType>(param_type) && (FT = dyn_cast<FunctionType>(
 520             cast<PointerType>(param_type)->getElementType()))) {
 521       ArgumentIndexMapping.push_back(ArgTypes.size());
 522       ArgTypes.push_back(getTrampolineFunctionType(FT)->getPointerTo());
 523       ArgTypes.push_back(Type::getInt8PtrTy(*Ctx));
 524     } else {
 525       ArgumentIndexMapping.push_back(ArgTypes.size());
 526       ArgTypes.push_back(param_type);
 527     }
 528   }
 529   for (unsigned i = 0, e = T->getNumParams(); i != e; ++i)
 530     ArgTypes.push_back(ShadowTy);
 531   if (T->isVarArg())
 532     ArgTypes.push_back(ShadowPtrTy);
 533   Type *RetType = T->getReturnType();
 534   if (!RetType->isVoidTy())
 535     ArgTypes.push_back(ShadowPtrTy);
 536   return TransformedFunction(
 537       T, FunctionType::get(T->getReturnType(), ArgTypes, T->isVarArg()),
 538       ArgumentIndexMapping);
 539 }
 540
 541 bool DataFlowSanitizer::doInitialization(Module &M) {
 542   Triple TargetTriple(M.getTargetTriple());
 543   bool IsX86_64 = TargetTriple.getArch() == Triple::x86_64;
 544   bool IsMIPS64 = TargetTriple.isMIPS64();
 545   bool IsAArch64 = TargetTriple.getArch() == Triple::aarch64 ||
 546                    TargetTriple.getArch() == Triple::aarch64_be;
 547
 548   const DataLayout &DL = M.getDataLayout();
 549
 550   Mod = &M;
 551   Ctx = &M.getContext();
 552   ShadowTy = IntegerType::get(*Ctx, ShadowWidth);
 553   ShadowPtrTy = PointerType::getUnqual(ShadowTy);
 554   IntptrTy = DL.getIntPtrType(*Ctx);
 555   ZeroShadow = ConstantInt::getSigned(ShadowTy, 0);
 556   ShadowPtrMul = ConstantInt::getSigned(IntptrTy, ShadowWidth / 8);
 557   if (IsX86_64)
 558     ShadowPtrMask = ConstantInt::getSigned(IntptrTy, ~0x700000000000LL);
 559   else if (IsMIPS64)
 560     ShadowPtrMask = ConstantInt::getSigned(IntptrTy, ~0xF000000000LL);
 561   // AArch64 supports multiple VMAs and the shadow mask is set at runtime.
 562   else if (IsAArch64)
 563     DFSanRuntimeShadowMask = true;
 564   else
 565     report_fatal_error("unsupported triple");
 566
 567   Type *DFSanUnionArgs[2] = { ShadowTy, ShadowTy };
 568   DFSanUnionFnTy =
 569       FunctionType::get(ShadowTy, DFSanUnionArgs, /*isVarArg=*/ false);
 570   Type *DFSanUnionLoadArgs[2] = { ShadowPtrTy, IntptrTy };
 571   DFSanUnionLoadFnTy =
 572       FunctionType::get(ShadowTy, DFSanUnionLoadArgs, /*isVarArg=*/ false);
 573   DFSanUnimplementedFnTy = FunctionType::get(
 574       Type::getVoidTy(*Ctx), Type::getInt8PtrTy(*Ctx), /*isVarArg=*/false);
 575   Type *DFSanSetLabelArgs[3] = { ShadowTy, Type::getInt8PtrTy(*Ctx), IntptrTy };
 576   DFSanSetLabelFnTy = FunctionType::get(Type::getVoidTy(*Ctx),
 577                                         DFSanSetLabelArgs, /*isVarArg=*/false);
 578   DFSanNonzeroLabelFnTy = FunctionType::get(
 579       Type::getVoidTy(*Ctx), None, /*isVarArg=*/false);
 580   DFSanVarargWrapperFnTy = FunctionType::get(
 581       Type::getVoidTy(*Ctx), Type::getInt8PtrTy(*Ctx), /*isVarArg=*/false);
 582
 583   if (GetArgTLSPtr) {
 584     Type *ArgTLSTy = ArrayType::get(ShadowTy, 64);
 585     ArgTLS = nullptr;
 586     GetArgTLSTy = FunctionType::get(PointerType::getUnqual(ArgTLSTy), false);
 587     GetArgTLS = ConstantExpr::getIntToPtr(
 588         ConstantInt::get(IntptrTy, uintptr_t(GetArgTLSPtr)),
 589         PointerType::getUnqual(GetArgTLSTy));
 590   }
 591   if (GetRetvalTLSPtr) {
 592     RetvalTLS = nullptr;
 593     GetRetvalTLSTy = FunctionType::get(PointerType::getUnqual(ShadowTy), false);
 594     GetRetvalTLS = ConstantExpr::getIntToPtr(
 595         ConstantInt::get(IntptrTy, uintptr_t(GetRetvalTLSPtr)),
 596         PointerType::getUnqual(GetRetvalTLSTy));
 597   }
 598
 599   ColdCallWeights = MDBuilder(*Ctx).createBranchWeights(1, 1000);
 600   return true;
 601 }
 602
 603 bool DataFlowSanitizer::isInstrumented(const Function *F) {
 604   return !ABIList.isIn(*F, "uninstrumented");
 605 }
 606
 607 bool DataFlowSanitizer::isInstrumented(const GlobalAlias *GA) {
 608   return !ABIList.isIn(*GA, "uninstrumented");
 609 }
 610
 611 DataFlowSanitizer::InstrumentedABI DataFlowSanitizer::getInstrumentedABI() {
 612   return ClArgsABI ? IA_Args : IA_TLS;
 613 }
 614
 615 DataFlowSanitizer::WrapperKind DataFlowSanitizer::getWrapperKind(Function *F) {
 616   if (ABIList.isIn(*F, "functional"))
 617     return WK_Functional;
 618   if (ABIList.isIn(*F, "discard"))
 619     return WK_Discard;
 620   if (ABIList.isIn(*F, "custom"))
 621     return WK_Custom;
 622
 623   return WK_Warning;
 624 }
 625
 626 void DataFlowSanitizer::addGlobalNamePrefix(GlobalValue *GV) {
 627   std::string GVName = GV->getName(), Prefix = "dfs$";
 628   GV->setName(Prefix + GVName);
 629
 630   // Try to change the name of the function in module inline asm.  We only do
 631   // this for specific asm directives, currently only ".symver", to try to avoid
 632   // corrupting asm which happens to contain the symbol name as a substring.
 633   // Note that the substitution for .symver assumes that the versioned symbol
 634   // also has an instrumented name.
 635   std::string Asm = GV->getParent()->getModuleInlineAsm();
 636   std::string SearchStr = ".symver " + GVName + ",";
 637   size_t Pos = Asm.find(SearchStr);
 638   if (Pos != std::string::npos) {
 639     Asm.replace(Pos, SearchStr.size(),
 640                 ".symver " + Prefix + GVName + "," + Prefix);
 641     GV->getParent()->setModuleInlineAsm(Asm);
 642   }
 643 }
 644
 645 Function *
 646 DataFlowSanitizer::buildWrapperFunction(Function *F, StringRef NewFName,
 647                                         GlobalValue::LinkageTypes NewFLink,
 648                                         FunctionType *NewFT) {
 649   FunctionType *FT = F->getFunctionType();
 650   Function *NewF = Function::Create(NewFT, NewFLink, F->getAddressSpace(),
 651                                     NewFName, F->getParent());
 652   NewF->copyAttributesFrom(F);
 653   NewF->removeAttributes(
 654       AttributeList::ReturnIndex,
 655       AttributeFuncs::typeIncompatible(NewFT->getReturnType()));
 656
 657   BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", NewF);
 658   if (F->isVarArg()) {
 659     NewF->removeAttributes(AttributeList::FunctionIndex,
 660                            AttrBuilder().addAttribute("split-stack"));
 661     CallInst::Create(DFSanVarargWrapperFn,
 662                      IRBuilder<>(BB).CreateGlobalStringPtr(F->getName()), "",
 663                      BB);
 664     new UnreachableInst(*Ctx, BB);
 665   } else {
 666     std::vector<Value *> Args;
 667     unsigned n = FT->getNumParams();
 668     for (Function::arg_iterator ai = NewF->arg_begin(); n != 0; ++ai, --n)
 669       Args.push_back(&*ai);
 670     CallInst *CI = CallInst::Create(F, Args, "", BB);
 671     if (FT->getReturnType()->isVoidTy())
 672       ReturnInst::Create(*Ctx, BB);
 673     else
 674       ReturnInst::Create(*Ctx, CI, BB);
 675   }
 676
 677   return NewF;
 678 }
 679
 680 Constant *DataFlowSanitizer::getOrBuildTrampolineFunction(FunctionType *FT,
 681                                                           StringRef FName) {
 682   FunctionType *FTT = getTrampolineFunctionType(FT);
 683   FunctionCallee C = Mod->getOrInsertFunction(FName, FTT);
 684   Function *F = dyn_cast<Function>(C.getCallee());
 685   if (F && F->isDeclaration()) {
 686     F->setLinkage(GlobalValue::LinkOnceODRLinkage);
 687     BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", F);
 688     std::vector<Value *> Args;
 689     Function::arg_iterator AI = F->arg_begin(); ++AI;
 690     for (unsigned N = FT->getNumParams(); N != 0; ++AI, --N)
 691       Args.push_back(&*AI);
 692     CallInst *CI = CallInst::Create(FT, &*F->arg_begin(), Args, "", BB);
 693     ReturnInst *RI;
 694     if (FT->getReturnType()->isVoidTy())
 695       RI = ReturnInst::Create(*Ctx, BB);
 696     else
 697       RI = ReturnInst::Create(*Ctx, CI, BB);
 698
 699     DFSanFunction DFSF(*this, F, /*IsNativeABI=*/true);
 700     Function::arg_iterator ValAI = F->arg_begin(), ShadowAI = AI; ++ValAI;
 701     for (unsigned N = FT->getNumParams(); N != 0; ++ValAI, ++ShadowAI, --N)
 702       DFSF.ValShadowMap[&*ValAI] = &*ShadowAI;
 703     DFSanVisitor(DFSF).visitCallInst(*CI);
 704     if (!FT->getReturnType()->isVoidTy())
 705       new StoreInst(DFSF.getShadow(RI->getReturnValue()),
 706                     &*std::prev(F->arg_end()), RI);
 707   }
 708
 709   return cast<Constant>(C.getCallee());
 710 }
 711
 712 bool DataFlowSanitizer::runOnModule(Module &M) {
 713   if (ABIList.isIn(M, "skip"))
 714     return false;
 715
 716   if (!GetArgTLSPtr) {
 717     Type *ArgTLSTy = ArrayType::get(ShadowTy, 64);
 718     ArgTLS = Mod->getOrInsertGlobal("__dfsan_arg_tls", ArgTLSTy);
 719     if (GlobalVariable *G = dyn_cast<GlobalVariable>(ArgTLS))
 720       G->setThreadLocalMode(GlobalVariable::InitialExecTLSModel);
 721   }
 722   if (!GetRetvalTLSPtr) {
 723     RetvalTLS = Mod->getOrInsertGlobal("__dfsan_retval_tls", ShadowTy);
 724     if (GlobalVariable *G = dyn_cast<GlobalVariable>(RetvalTLS))
 725       G->setThreadLocalMode(GlobalVariable::InitialExecTLSModel);
 726   }
 727
 728   ExternalShadowMask =
 729       Mod->getOrInsertGlobal(kDFSanExternShadowPtrMask, IntptrTy);
 730
 731   {
 732     AttributeList AL;
 733     AL = AL.addAttribute(M.getContext(), AttributeList::FunctionIndex,
 734                          Attribute::NoUnwind);
 735     AL = AL.addAttribute(M.getContext(), AttributeList::FunctionIndex,
 736                          Attribute::ReadNone);
 737     AL = AL.addAttribute(M.getContext(), AttributeList::ReturnIndex,
 738                          Attribute::ZExt);
 739     AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
 740     AL = AL.addParamAttribute(M.getContext(), 1, Attribute::ZExt);
 741     DFSanUnionFn =
 742         Mod->getOrInsertFunction("__dfsan_union", DFSanUnionFnTy, AL);
 743   }
 744
 745   {
 746     AttributeList AL;
 747     AL = AL.addAttribute(M.getContext(), AttributeList::FunctionIndex,
 748                          Attribute::NoUnwind);
 749     AL = AL.addAttribute(M.getContext(), AttributeList::FunctionIndex,
 750                          Attribute::ReadNone);
 751     AL = AL.addAttribute(M.getContext(), AttributeList::ReturnIndex,
 752                          Attribute::ZExt);
 753     AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
 754     AL = AL.addParamAttribute(M.getContext(), 1, Attribute::ZExt);
 755     DFSanCheckedUnionFn =
 756         Mod->getOrInsertFunction("dfsan_union", DFSanUnionFnTy, AL);
 757   }
 758   {
 759     AttributeList AL;
 760     AL = AL.addAttribute(M.getContext(), AttributeList::FunctionIndex,
 761                          Attribute::NoUnwind);
 762     AL = AL.addAttribute(M.getContext(), AttributeList::FunctionIndex,
 763                          Attribute::ReadOnly);
 764     AL = AL.addAttribute(M.getContext(), AttributeList::ReturnIndex,
 765                          Attribute::ZExt);
 766     DFSanUnionLoadFn =
 767         Mod->getOrInsertFunction("__dfsan_union_load", DFSanUnionLoadFnTy, AL);
 768   }
 769   DFSanUnimplementedFn =
 770       Mod->getOrInsertFunction("__dfsan_unimplemented", DFSanUnimplementedFnTy);
 771   {
 772     AttributeList AL;
 773     AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
 774     DFSanSetLabelFn =
 775         Mod->getOrInsertFunction("__dfsan_set_label", DFSanSetLabelFnTy, AL);
 776   }
 777   DFSanNonzeroLabelFn =
 778       Mod->getOrInsertFunction("__dfsan_nonzero_label", DFSanNonzeroLabelFnTy);
 779   DFSanVarargWrapperFn = Mod->getOrInsertFunction("__dfsan_vararg_wrapper",
 780                                                   DFSanVarargWrapperFnTy);
 781
 782   std::vector<Function *> FnsToInstrument;
 783   SmallPtrSet<Function *, 2> FnsWithNativeABI;
 784   for (Function &i : M) {
 785     if (!i.isIntrinsic() &&
 786         &i != DFSanUnionFn.getCallee()->stripPointerCasts() &&
 787         &i != DFSanCheckedUnionFn.getCallee()->stripPointerCasts() &&
 788         &i != DFSanUnionLoadFn.getCallee()->stripPointerCasts() &&
 789         &i != DFSanUnimplementedFn.getCallee()->stripPointerCasts() &&
 790         &i != DFSanSetLabelFn.getCallee()->stripPointerCasts() &&
 791         &i != DFSanNonzeroLabelFn.getCallee()->stripPointerCasts() &&
 792         &i != DFSanVarargWrapperFn.getCallee()->stripPointerCasts())
 793       FnsToInstrument.push_back(&i);
 794   }
 795
 796   // Give function aliases prefixes when necessary, and build wrappers where the
 797   // instrumentedness is inconsistent.
 798   for (Module::alias_iterator i = M.alias_begin(), e = M.alias_end(); i != e;) {
 799     GlobalAlias *GA = &*i;
 800     ++i;
 801     // Don't stop on weak.  We assume people aren't playing games with the
 802     // instrumentedness of overridden weak aliases.
 803     if (auto F = dyn_cast<Function>(GA->getBaseObject())) {
 804       bool GAInst = isInstrumented(GA), FInst = isInstrumented(F);
 805       if (GAInst && FInst) {
 806         addGlobalNamePrefix(GA);
 807       } else if (GAInst != FInst) {
 808         // Non-instrumented alias of an instrumented function, or vice versa.
 809         // Replace the alias with a native-ABI wrapper of the aliasee.  The pass
 810         // below will take care of instrumenting it.
 811         Function *NewF =
 812             buildWrapperFunction(F, "", GA->getLinkage(), F->getFunctionType());
 813         GA->replaceAllUsesWith(ConstantExpr::getBitCast(NewF, GA->getType()));
 814         NewF->takeName(GA);
 815         GA->eraseFromParent();
 816         FnsToInstrument.push_back(NewF);
 817       }
 818     }
 819   }
 820
 821   ReadOnlyNoneAttrs.addAttribute(Attribute::ReadOnly)
 822       .addAttribute(Attribute::ReadNone);
 823
 824   // First, change the ABI of every function in the module.  ABI-listed
 825   // functions keep their original ABI and get a wrapper function.
 826   for (std::vector<Function *>::iterator i = FnsToInstrument.begin(),
 827                                          e = FnsToInstrument.end();
 828        i != e; ++i) {
 829     Function &F = **i;
 830     FunctionType *FT = F.getFunctionType();
 831
 832     bool IsZeroArgsVoidRet = (FT->getNumParams() == 0 && !FT->isVarArg() &&
 833                               FT->getReturnType()->isVoidTy());
 834
 835     if (isInstrumented(&F)) {
 836       // Instrumented functions get a 'dfs$' prefix.  This allows us to more
 837       // easily identify cases of mismatching ABIs.
 838       if (getInstrumentedABI() == IA_Args && !IsZeroArgsVoidRet) {
 839         FunctionType *NewFT = getArgsFunctionType(FT);
 840         Function *NewF = Function::Create(NewFT, F.getLinkage(),
 841                                           F.getAddressSpace(), "", &M);
 842         NewF->copyAttributesFrom(&F);
 843         NewF->removeAttributes(
 844             AttributeList::ReturnIndex,
 845             AttributeFuncs::typeIncompatible(NewFT->getReturnType()));
 846         for (Function::arg_iterator FArg = F.arg_begin(),
 847                                     NewFArg = NewF->arg_begin(),
 848                                     FArgEnd = F.arg_end();
 849              FArg != FArgEnd; ++FArg, ++NewFArg) {
 850           FArg->replaceAllUsesWith(&*NewFArg);
 851         }
 852         NewF->getBasicBlockList().splice(NewF->begin(), F.getBasicBlockList());
 853
 854         for (Function::user_iterator UI = F.user_begin(), UE = F.user_end();
 855              UI != UE;) {
 856           BlockAddress *BA = dyn_cast<BlockAddress>(*UI);
 857           ++UI;
 858           if (BA) {
 859             BA->replaceAllUsesWith(
 860                 BlockAddress::get(NewF, BA->getBasicBlock()));
 861             delete BA;
 862           }
 863         }
 864         F.replaceAllUsesWith(
 865             ConstantExpr::getBitCast(NewF, PointerType::getUnqual(FT)));
 866         NewF->takeName(&F);
 867         F.eraseFromParent();
 868         *i = NewF;
 869         addGlobalNamePrefix(NewF);
 870       } else {
 871         addGlobalNamePrefix(&F);
 872       }
 873     } else if (!IsZeroArgsVoidRet || getWrapperKind(&F) == WK_Custom) {
 874       // Build a wrapper function for F.  The wrapper simply calls F, and is
 875       // added to FnsToInstrument so that any instrumentation according to its
 876       // WrapperKind is done in the second pass below.
 877       FunctionType *NewFT = getInstrumentedABI() == IA_Args
 878                                 ? getArgsFunctionType(FT)
 879                                 : FT;
 880
 881       // If the function being wrapped has local linkage, then preserve the
 882       // function's linkage in the wrapper function.
 883       GlobalValue::LinkageTypes wrapperLinkage =
 884           F.hasLocalLinkage()
 885               ? F.getLinkage()
 886               : GlobalValue::LinkOnceODRLinkage;
 887
 888       Function *NewF = buildWrapperFunction(
 889           &F, std::string("dfsw$") + std::string(F.getName()),
 890           wrapperLinkage, NewFT);
 891       if (getInstrumentedABI() == IA_TLS)
 892         NewF->removeAttributes(AttributeList::FunctionIndex, ReadOnlyNoneAttrs);
 893
 894       Value *WrappedFnCst =
 895           ConstantExpr::getBitCast(NewF, PointerType::getUnqual(FT));
 896       F.replaceAllUsesWith(WrappedFnCst);
 897
 898       UnwrappedFnMap[WrappedFnCst] = &F;
 899       *i = NewF;
 900
 901       if (!F.isDeclaration()) {
 902         // This function is probably defining an interposition of an
 903         // uninstrumented function and hence needs to keep the original ABI.
 904         // But any functions it may call need to use the instrumented ABI, so
 905         // we instrument it in a mode which preserves the original ABI.
 906         FnsWithNativeABI.insert(&F);
 907
 908         // This code needs to rebuild the iterators, as they may be invalidated
 909         // by the push_back, taking care that the new range does not include
 910         // any functions added by this code.
 911         size_t N = i - FnsToInstrument.begin(),
 912                Count = e - FnsToInstrument.begin();
 913         FnsToInstrument.push_back(&F);
 914         i = FnsToInstrument.begin() + N;
 915         e = FnsToInstrument.begin() + Count;
 916       }
 917                // Hopefully, nobody will try to indirectly call a vararg
 918                // function... yet.
 919     } else if (FT->isVarArg()) {
 920       UnwrappedFnMap[&F] = &F;
 921       *i = nullptr;
 922     }
 923   }
 924
 925   for (Function *i : FnsToInstrument) {
 926     if (!i || i->isDeclaration())
 927       continue;
 928
 929     removeUnreachableBlocks(*i);
 930
 931     DFSanFunction DFSF(*this, i, FnsWithNativeABI.count(i));
 932
 933     // DFSanVisitor may create new basic blocks, which confuses df_iterator.
 934     // Build a copy of the list before iterating over it.
 935     SmallVector<BasicBlock *, 4> BBList(depth_first(&i->getEntryBlock()));
 936
 937     for (BasicBlock *i : BBList) {
 938       Instruction *Inst = &i->front();
 939       while (true) {
 940         // DFSanVisitor may split the current basic block, changing the current
 941         // instruction's next pointer and moving the next instruction to the
 942         // tail block from which we should continue.
 943         Instruction *Next = Inst->getNextNode();
 944         // DFSanVisitor may delete Inst, so keep track of whether it was a
 945         // terminator.
 946         bool IsTerminator = Inst->isTerminator();
 947         if (!DFSF.SkipInsts.count(Inst))
 948           DFSanVisitor(DFSF).visit(Inst);
 949         if (IsTerminator)
 950           break;
 951         Inst = Next;
 952       }
 953     }
 954
 955     // We will not necessarily be able to compute the shadow for every phi node
 956     // until we have visited every block.  Therefore, the code that handles phi
 957     // nodes adds them to the PHIFixups list so that they can be properly
 958     // handled here.
 959     for (std::vector<std::pair<PHINode *, PHINode *>>::iterator
 960              i = DFSF.PHIFixups.begin(),
 961              e = DFSF.PHIFixups.end();
 962          i != e; ++i) {
 963       for (unsigned val = 0, n = i->first->getNumIncomingValues(); val != n;
 964            ++val) {
 965         i->second->setIncomingValue(
 966             val, DFSF.getShadow(i->first->getIncomingValue(val)));
 967       }
 968     }
 969
 970     // -dfsan-debug-nonzero-labels will split the CFG in all kinds of crazy
 971     // places (i.e. instructions in basic blocks we haven't even begun visiting
 972     // yet).  To make our life easier, do this work in a pass after the main
 973     // instrumentation.
 974     if (ClDebugNonzeroLabels) {
 975       for (Value *V : DFSF.NonZeroChecks) {
 976         Instruction *Pos;
 977         if (Instruction *I = dyn_cast<Instruction>(V))
 978           Pos = I->getNextNode();
 979         else
 980           Pos = &DFSF.F->getEntryBlock().front();
 981         while (isa<PHINode>(Pos) || isa<AllocaInst>(Pos))
 982           Pos = Pos->getNextNode();
 983         IRBuilder<> IRB(Pos);
 984         Value *Ne = IRB.CreateICmpNE(V, DFSF.DFS.ZeroShadow);
 985         BranchInst *BI = cast<BranchInst>(SplitBlockAndInsertIfThen(
 986             Ne, Pos, /*Unreachable=*/false, ColdCallWeights));
 987         IRBuilder<> ThenIRB(BI);
 988         ThenIRB.CreateCall(DFSF.DFS.DFSanNonzeroLabelFn, {});
 989       }
 990     }
 991   }
 992
 993   return false;
 994 }
 995
 996 Value *DFSanFunction::getArgTLSPtr() {
 997   if (ArgTLSPtr)
 998     return ArgTLSPtr;
 999   if (DFS.ArgTLS)
1000     return ArgTLSPtr = DFS.ArgTLS;
1001
1002   IRBuilder<> IRB(&F->getEntryBlock().front());
1003   return ArgTLSPtr = IRB.CreateCall(DFS.GetArgTLSTy, DFS.GetArgTLS, {});
1004 }
1005
1006 Value *DFSanFunction::getRetvalTLS() {
1007   if (RetvalTLSPtr)
1008     return RetvalTLSPtr;
1009   if (DFS.RetvalTLS)
1010     return RetvalTLSPtr = DFS.RetvalTLS;
1011
1012   IRBuilder<> IRB(&F->getEntryBlock().front());
1013   return RetvalTLSPtr =
1014              IRB.CreateCall(DFS.GetRetvalTLSTy, DFS.GetRetvalTLS, {});
1015 }
1016
1017 Value *DFSanFunction::getArgTLS(unsigned Idx, Instruction *Pos) {
1018   IRBuilder<> IRB(Pos);
1019   return IRB.CreateConstGEP2_64(ArrayType::get(DFS.ShadowTy, 64),
1020                                 getArgTLSPtr(), 0, Idx);
1021 }
1022
1023 Value *DFSanFunction::getShadow(Value *V) {
1024   if (!isa<Argument>(V) && !isa<Instruction>(V))
1025     return DFS.ZeroShadow;
1026   Value *&Shadow = ValShadowMap[V];
1027   if (!Shadow) {
1028     if (Argument *A = dyn_cast<Argument>(V)) {
1029       if (IsNativeABI)
1030         return DFS.ZeroShadow;
1031       switch (IA) {
1032       case DataFlowSanitizer::IA_TLS: {
1033         Value *ArgTLSPtr = getArgTLSPtr();
1034         Instruction *ArgTLSPos =
1035             DFS.ArgTLS ? &*F->getEntryBlock().begin()
1036                        : cast<Instruction>(ArgTLSPtr)->getNextNode();
1037         IRBuilder<> IRB(ArgTLSPos);
1038         Shadow =
1039             IRB.CreateLoad(DFS.ShadowTy, getArgTLS(A->getArgNo(), ArgTLSPos));
1040         break;
1041       }
1042       case DataFlowSanitizer::IA_Args: {
1043         unsigned ArgIdx = A->getArgNo() + F->arg_size() / 2;
1044         Function::arg_iterator i = F->arg_begin();
1045         while (ArgIdx--)
1046           ++i;
1047         Shadow = &*i;
1048         assert(Shadow->getType() == DFS.ShadowTy);
1049         break;
1050       }
1051       }
1052       NonZeroChecks.push_back(Shadow);
1053     } else {
1054       Shadow = DFS.ZeroShadow;
1055     }
1056   }
1057   return Shadow;
1058 }
1059
1060 void DFSanFunction::setShadow(Instruction *I, Value *Shadow) {
1061   assert(!ValShadowMap.count(I));
1062   assert(Shadow->getType() == DFS.ShadowTy);
1063   ValShadowMap[I] = Shadow;
1064 }
1065
1066 Value *DataFlowSanitizer::getShadowAddress(Value *Addr, Instruction *Pos) {
1067   assert(Addr != RetvalTLS && "Reinstrumenting?");
1068   IRBuilder<> IRB(Pos);
1069   Value *ShadowPtrMaskValue;
1070   if (DFSanRuntimeShadowMask)
1071     ShadowPtrMaskValue = IRB.CreateLoad(IntptrTy, ExternalShadowMask);
1072   else
1073     ShadowPtrMaskValue = ShadowPtrMask;
1074   return IRB.CreateIntToPtr(
1075       IRB.CreateMul(
1076           IRB.CreateAnd(IRB.CreatePtrToInt(Addr, IntptrTy),
1077                         IRB.CreatePtrToInt(ShadowPtrMaskValue, IntptrTy)),
1078           ShadowPtrMul),
1079       ShadowPtrTy);
1080 }
1081
1082 // Generates IR to compute the union of the two given shadows, inserting it
1083 // before Pos.  Returns the computed union Value.
1084 Value *DFSanFunction::combineShadows(Value *V1, Value *V2, Instruction *Pos) {
1085   if (V1 == DFS.ZeroShadow)
1086     return V2;
1087   if (V2 == DFS.ZeroShadow)
1088     return V1;
1089   if (V1 == V2)
1090     return V1;
1091
1092   auto V1Elems = ShadowElements.find(V1);
1093   auto V2Elems = ShadowElements.find(V2);
1094   if (V1Elems != ShadowElements.end() && V2Elems != ShadowElements.end()) {
1095     if (std::includes(V1Elems->second.begin(), V1Elems->second.end(),
1096                       V2Elems->second.begin(), V2Elems->second.end())) {
1097       return V1;
1098     } else if (std::includes(V2Elems->second.begin(), V2Elems->second.end(),
1099                              V1Elems->second.begin(), V1Elems->second.end())) {
1100       return V2;
1101     }
1102   } else if (V1Elems != ShadowElements.end()) {
1103     if (V1Elems->second.count(V2))
1104       return V1;
1105   } else if (V2Elems != ShadowElements.end()) {
1106     if (V2Elems->second.count(V1))
1107       return V2;
1108   }
1109
1110   auto Key = std::make_pair(V1, V2);
1111   if (V1 > V2)
1112     std::swap(Key.first, Key.second);
1113   CachedCombinedShadow &CCS = CachedCombinedShadows[Key];
1114   if (CCS.Block && DT.dominates(CCS.Block, Pos->getParent()))
1115     return CCS.Shadow;
1116
1117   IRBuilder<> IRB(Pos);
1118   if (AvoidNewBlocks) {
1119     CallInst *Call = IRB.CreateCall(DFS.DFSanCheckedUnionFn, {V1, V2});
1120     Call->addAttribute(AttributeList::ReturnIndex, Attribute::ZExt);
1121     Call->addParamAttr(0, Attribute::ZExt);
1122     Call->addParamAttr(1, Attribute::ZExt);
1123
1124     CCS.Block = Pos->getParent();
1125     CCS.Shadow = Call;
1126   } else {
1127     BasicBlock *Head = Pos->getParent();
1128     Value *Ne = IRB.CreateICmpNE(V1, V2);
1129     BranchInst *BI = cast<BranchInst>(SplitBlockAndInsertIfThen(
1130         Ne, Pos, /*Unreachable=*/false, DFS.ColdCallWeights, &DT));
1131     IRBuilder<> ThenIRB(BI);
1132     CallInst *Call = ThenIRB.CreateCall(DFS.DFSanUnionFn, {V1, V2});
1133     Call->addAttribute(AttributeList::ReturnIndex, Attribute::ZExt);
1134     Call->addParamAttr(0, Attribute::ZExt);
1135     Call->addParamAttr(1, Attribute::ZExt);
1136
1137     BasicBlock *Tail = BI->getSuccessor(0);
1138     PHINode *Phi = PHINode::Create(DFS.ShadowTy, 2, "", &Tail->front());
1139     Phi->addIncoming(Call, Call->getParent());
1140     Phi->addIncoming(V1, Head);
1141
1142     CCS.Block = Tail;
1143     CCS.Shadow = Phi;
1144   }
1145
1146   std::set<Value *> UnionElems;
1147   if (V1Elems != ShadowElements.end()) {
1148     UnionElems = V1Elems->second;
1149   } else {
1150     UnionElems.insert(V1);
1151   }
1152   if (V2Elems != ShadowElements.end()) {
1153     UnionElems.insert(V2Elems->second.begin(), V2Elems->second.end());
1154   } else {
1155     UnionElems.insert(V2);
1156   }
1157   ShadowElements[CCS.Shadow] = std::move(UnionElems);
1158
1159   return CCS.Shadow;
1160 }
1161
1162 // A convenience function which folds the shadows of each of the operands
1163 // of the provided instruction Inst, inserting the IR before Inst.  Returns
1164 // the computed union Value.
1165 Value *DFSanFunction::combineOperandShadows(Instruction *Inst) {
1166   if (Inst->getNumOperands() == 0)
1167     return DFS.ZeroShadow;
1168
1169   Value *Shadow = getShadow(Inst->getOperand(0));
1170   for (unsigned i = 1, n = Inst->getNumOperands(); i != n; ++i) {
1171     Shadow = combineShadows(Shadow, getShadow(Inst->getOperand(i)), Inst);
1172   }
1173   return Shadow;
1174 }
1175
1176 void DFSanVisitor::visitOperandShadowInst(Instruction &I) {
1177   Value *CombinedShadow = DFSF.combineOperandShadows(&I);
1178   DFSF.setShadow(&I, CombinedShadow);
1179 }
1180
1181 // Generates IR to load shadow corresponding to bytes [Addr, Addr+Size), where
1182 // Addr has alignment Align, and take the union of each of those shadows.
1183 Value *DFSanFunction::loadShadow(Value *Addr, uint64_t Size, uint64_t Align,
1184                                  Instruction *Pos) {
1185   if (AllocaInst *AI = dyn_cast<AllocaInst>(Addr)) {
1186     const auto i = AllocaShadowMap.find(AI);
1187     if (i != AllocaShadowMap.end()) {
1188       IRBuilder<> IRB(Pos);
1189       return IRB.CreateLoad(DFS.ShadowTy, i->second);
1190     }
1191   }
1192
1193   uint64_t ShadowAlign = Align * DFS.ShadowWidth / 8;
1194   SmallVector<const Value *, 2> Objs;
1195   GetUnderlyingObjects(Addr, Objs, Pos->getModule()->getDataLayout());
1196   bool AllConstants = true;
1197   for (const Value *Obj : Objs) {
1198     if (isa<Function>(Obj) || isa<BlockAddress>(Obj))
1199       continue;
1200     if (isa<GlobalVariable>(Obj) && cast<GlobalVariable>(Obj)->isConstant())
1201       continue;
1202
1203     AllConstants = false;
1204     break;
1205   }
1206   if (AllConstants)
1207     return DFS.ZeroShadow;
1208
1209   Value *ShadowAddr = DFS.getShadowAddress(Addr, Pos);
1210   switch (Size) {
1211   case 0:
1212     return DFS.ZeroShadow;
1213   case 1: {
1214     LoadInst *LI = new LoadInst(DFS.ShadowTy, ShadowAddr, "", Pos);
1215     LI->setAlignment(MaybeAlign(ShadowAlign));
1216     return LI;
1217   }
1218   case 2: {
1219     IRBuilder<> IRB(Pos);
1220     Value *ShadowAddr1 = IRB.CreateGEP(DFS.ShadowTy, ShadowAddr,
1221                                        ConstantInt::get(DFS.IntptrTy, 1));
1222     return combineShadows(
1223         IRB.CreateAlignedLoad(DFS.ShadowTy, ShadowAddr, ShadowAlign),
1224         IRB.CreateAlignedLoad(DFS.ShadowTy, ShadowAddr1, ShadowAlign), Pos);
1225   }
1226   }
1227   if (!AvoidNewBlocks && Size % (64 / DFS.ShadowWidth) == 0) {
1228     // Fast path for the common case where each byte has identical shadow: load
1229     // shadow 64 bits at a time, fall out to a __dfsan_union_load call if any
1230     // shadow is non-equal.
1231     BasicBlock *FallbackBB = BasicBlock::Create(*DFS.Ctx, "", F);
1232     IRBuilder<> FallbackIRB(FallbackBB);
1233     CallInst *FallbackCall = FallbackIRB.CreateCall(
1234         DFS.DFSanUnionLoadFn,
1235         {ShadowAddr, ConstantInt::get(DFS.IntptrTy, Size)});
1236     FallbackCall->addAttribute(AttributeList::ReturnIndex, Attribute::ZExt);
1237
1238     // Compare each of the shadows stored in the loaded 64 bits to each other,
1239     // by computing (WideShadow rotl ShadowWidth) == WideShadow.
1240     IRBuilder<> IRB(Pos);
1241     Value *WideAddr =
1242         IRB.CreateBitCast(ShadowAddr, Type::getInt64PtrTy(*DFS.Ctx));
1243     Value *WideShadow =
1244         IRB.CreateAlignedLoad(IRB.getInt64Ty(), WideAddr, ShadowAlign);
1245     Value *TruncShadow = IRB.CreateTrunc(WideShadow, DFS.ShadowTy);
1246     Value *ShlShadow = IRB.CreateShl(WideShadow, DFS.ShadowWidth);
1247     Value *ShrShadow = IRB.CreateLShr(WideShadow, 64 - DFS.ShadowWidth);
1248     Value *RotShadow = IRB.CreateOr(ShlShadow, ShrShadow);
1249     Value *ShadowsEq = IRB.CreateICmpEQ(WideShadow, RotShadow);
1250
1251     BasicBlock *Head = Pos->getParent();
1252     BasicBlock *Tail = Head->splitBasicBlock(Pos->getIterator());
1253
1254     if (DomTreeNode *OldNode = DT.getNode(Head)) {
1255       std::vector<DomTreeNode *> Children(OldNode->begin(), OldNode->end());
1256
1257       DomTreeNode *NewNode = DT.addNewBlock(Tail, Head);
1258       for (auto Child : Children)
1259         DT.changeImmediateDominator(Child, NewNode);
1260     }
1261
1262     // In the following code LastBr will refer to the previous basic block's
1263     // conditional branch instruction, whose true successor is fixed up to point
1264     // to the next block during the loop below or to the tail after the final
1265     // iteration.
1266     BranchInst *LastBr = BranchInst::Create(FallbackBB, FallbackBB, ShadowsEq);
1267     ReplaceInstWithInst(Head->getTerminator(), LastBr);
1268     DT.addNewBlock(FallbackBB, Head);
1269
1270     for (uint64_t Ofs = 64 / DFS.ShadowWidth; Ofs != Size;
1271          Ofs += 64 / DFS.ShadowWidth) {
1272       BasicBlock *NextBB = BasicBlock::Create(*DFS.Ctx, "", F);
1273       DT.addNewBlock(NextBB, LastBr->getParent());
1274       IRBuilder<> NextIRB(NextBB);
1275       WideAddr = NextIRB.CreateGEP(Type::getInt64Ty(*DFS.Ctx), WideAddr,
1276                                    ConstantInt::get(DFS.IntptrTy, 1));
1277       Value *NextWideShadow = NextIRB.CreateAlignedLoad(NextIRB.getInt64Ty(),
1278                                                         WideAddr, ShadowAlign);
1279       ShadowsEq = NextIRB.CreateICmpEQ(WideShadow, NextWideShadow);
1280       LastBr->setSuccessor(0, NextBB);
1281       LastBr = NextIRB.CreateCondBr(ShadowsEq, FallbackBB, FallbackBB);
1282     }
1283
1284     LastBr->setSuccessor(0, Tail);
1285     FallbackIRB.CreateBr(Tail);
1286     PHINode *Shadow = PHINode::Create(DFS.ShadowTy, 2, "", &Tail->front());
1287     Shadow->addIncoming(FallbackCall, FallbackBB);
1288     Shadow->addIncoming(TruncShadow, LastBr->getParent());
1289     return Shadow;
1290   }
1291
1292   IRBuilder<> IRB(Pos);
1293   CallInst *FallbackCall = IRB.CreateCall(
1294       DFS.DFSanUnionLoadFn, {ShadowAddr, ConstantInt::get(DFS.IntptrTy, Size)});
1295   FallbackCall->addAttribute(AttributeList::ReturnIndex, Attribute::ZExt);
1296   return FallbackCall;
1297 }
1298
1299 void DFSanVisitor::visitLoadInst(LoadInst &LI) {
1300   auto &DL = LI.getModule()->getDataLayout();
1301   uint64_t Size = DL.getTypeStoreSize(LI.getType());
1302   if (Size == 0) {
1303     DFSF.setShadow(&LI, DFSF.DFS.ZeroShadow);
1304     return;
1305   }
1306
1307   uint64_t Align;
1308   if (ClPreserveAlignment) {
1309     Align = LI.getAlignment();
1310     if (Align == 0)
1311       Align = DL.getABITypeAlignment(LI.getType());
1312   } else {
1313     Align = 1;
1314   }
1315   IRBuilder<> IRB(&LI);
1316   Value *Shadow = DFSF.loadShadow(LI.getPointerOperand(), Size, Align, &LI);
1317   if (ClCombinePointerLabelsOnLoad) {
1318     Value *PtrShadow = DFSF.getShadow(LI.getPointerOperand());
1319     Shadow = DFSF.combineShadows(Shadow, PtrShadow, &LI);
1320   }
1321   if (Shadow != DFSF.DFS.ZeroShadow)
1322     DFSF.NonZeroChecks.push_back(Shadow);
1323
1324   DFSF.setShadow(&LI, Shadow);
1325 }
1326
1327 void DFSanFunction::storeShadow(Value *Addr, uint64_t Size, uint64_t Align,
1328                                 Value *Shadow, Instruction *Pos) {
1329   if (AllocaInst *AI = dyn_cast<AllocaInst>(Addr)) {
1330     const auto i = AllocaShadowMap.find(AI);
1331     if (i != AllocaShadowMap.end()) {
1332       IRBuilder<> IRB(Pos);
1333       IRB.CreateStore(Shadow, i->second);
1334       return;
1335     }
1336   }
1337
1338   uint64_t ShadowAlign = Align * DFS.ShadowWidth / 8;
1339   IRBuilder<> IRB(Pos);
1340   Value *ShadowAddr = DFS.getShadowAddress(Addr, Pos);
1341   if (Shadow == DFS.ZeroShadow) {
1342     IntegerType *ShadowTy = IntegerType::get(*DFS.Ctx, Size * DFS.ShadowWidth);
1343     Value *ExtZeroShadow = ConstantInt::get(ShadowTy, 0);
1344     Value *ExtShadowAddr =
1345         IRB.CreateBitCast(ShadowAddr, PointerType::getUnqual(ShadowTy));
1346     IRB.CreateAlignedStore(ExtZeroShadow, ExtShadowAddr, ShadowAlign);
1347     return;
1348   }
1349
1350   const unsigned ShadowVecSize = 128 / DFS.ShadowWidth;
1351   uint64_t Offset = 0;
1352   if (Size >= ShadowVecSize) {
1353     VectorType *ShadowVecTy = VectorType::get(DFS.ShadowTy, ShadowVecSize);
1354     Value *ShadowVec = UndefValue::get(ShadowVecTy);
1355     for (unsigned i = 0; i != ShadowVecSize; ++i) {
1356       ShadowVec = IRB.CreateInsertElement(
1357           ShadowVec, Shadow, ConstantInt::get(Type::getInt32Ty(*DFS.Ctx), i));
1358     }
1359     Value *ShadowVecAddr =
1360         IRB.CreateBitCast(ShadowAddr, PointerType::getUnqual(ShadowVecTy));
1361     do {
1362       Value *CurShadowVecAddr =
1363           IRB.CreateConstGEP1_32(ShadowVecTy, ShadowVecAddr, Offset);
1364       IRB.CreateAlignedStore(ShadowVec, CurShadowVecAddr, ShadowAlign);
1365       Size -= ShadowVecSize;
1366       ++Offset;
1367     } while (Size >= ShadowVecSize);
1368     Offset *= ShadowVecSize;
1369   }
1370   while (Size > 0) {
1371     Value *CurShadowAddr =
1372         IRB.CreateConstGEP1_32(DFS.ShadowTy, ShadowAddr, Offset);
1373     IRB.CreateAlignedStore(Shadow, CurShadowAddr, ShadowAlign);
1374     --Size;
1375     ++Offset;
1376   }
1377 }
1378
1379 void DFSanVisitor::visitStoreInst(StoreInst &SI) {
1380   auto &DL = SI.getModule()->getDataLayout();
1381   uint64_t Size = DL.getTypeStoreSize(SI.getValueOperand()->getType());
1382   if (Size == 0)
1383     return;
1384
1385   uint64_t Align;
1386   if (ClPreserveAlignment) {
1387     Align = SI.getAlignment();
1388     if (Align == 0)
1389       Align = DL.getABITypeAlignment(SI.getValueOperand()->getType());
1390   } else {
1391     Align = 1;
1392   }
1393
1394   Value* Shadow = DFSF.getShadow(SI.getValueOperand());
1395   if (ClCombinePointerLabelsOnStore) {
1396     Value *PtrShadow = DFSF.getShadow(SI.getPointerOperand());
1397     Shadow = DFSF.combineShadows(Shadow, PtrShadow, &SI);
1398   }
1399   DFSF.storeShadow(SI.getPointerOperand(), Size, Align, Shadow, &SI);
1400 }
1401
1402 void DFSanVisitor::visitUnaryOperator(UnaryOperator &UO) {
1403   visitOperandShadowInst(UO);
1404 }
1405
1406 void DFSanVisitor::visitBinaryOperator(BinaryOperator &BO) {
1407   visitOperandShadowInst(BO);
1408 }
1409
1410 void DFSanVisitor::visitCastInst(CastInst &CI) { visitOperandShadowInst(CI); }
1411
1412 void DFSanVisitor::visitCmpInst(CmpInst &CI) { visitOperandShadowInst(CI); }
1413
1414 void DFSanVisitor::visitGetElementPtrInst(GetElementPtrInst &GEPI) {
1415   visitOperandShadowInst(GEPI);
1416 }
1417
1418 void DFSanVisitor::visitExtractElementInst(ExtractElementInst &I) {
1419   visitOperandShadowInst(I);
1420 }
1421
1422 void DFSanVisitor::visitInsertElementInst(InsertElementInst &I) {
1423   visitOperandShadowInst(I);
1424 }
1425
1426 void DFSanVisitor::visitShuffleVectorInst(ShuffleVectorInst &I) {
1427   visitOperandShadowInst(I);
1428 }
1429
1430 void DFSanVisitor::visitExtractValueInst(ExtractValueInst &I) {
1431   visitOperandShadowInst(I);
1432 }
1433
1434 void DFSanVisitor::visitInsertValueInst(InsertValueInst &I) {
1435   visitOperandShadowInst(I);
1436 }
1437
1438 void DFSanVisitor::visitAllocaInst(AllocaInst &I) {
1439   bool AllLoadsStores = true;
1440   for (User *U : I.users()) {
1441     if (isa<LoadInst>(U))
1442       continue;
1443
1444     if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
1445       if (SI->getPointerOperand() == &I)
1446         continue;
1447     }
1448
1449     AllLoadsStores = false;
1450     break;
1451   }
1452   if (AllLoadsStores) {
1453     IRBuilder<> IRB(&I);
1454     DFSF.AllocaShadowMap[&I] = IRB.CreateAlloca(DFSF.DFS.ShadowTy);
1455   }
1456   DFSF.setShadow(&I, DFSF.DFS.ZeroShadow);
1457 }
1458
1459 void DFSanVisitor::visitSelectInst(SelectInst &I) {
1460   Value *CondShadow = DFSF.getShadow(I.getCondition());
1461   Value *TrueShadow = DFSF.getShadow(I.getTrueValue());
1462   Value *FalseShadow = DFSF.getShadow(I.getFalseValue());
1463
1464   if (isa<VectorType>(I.getCondition()->getType())) {
1465     DFSF.setShadow(
1466         &I,
1467         DFSF.combineShadows(
1468             CondShadow, DFSF.combineShadows(TrueShadow, FalseShadow, &I), &I));
1469   } else {
1470     Value *ShadowSel;
1471     if (TrueShadow == FalseShadow) {
1472       ShadowSel = TrueShadow;
1473     } else {
1474       ShadowSel =
1475           SelectInst::Create(I.getCondition(), TrueShadow, FalseShadow, "", &I);
1476     }
1477     DFSF.setShadow(&I, DFSF.combineShadows(CondShadow, ShadowSel, &I));
1478   }
1479 }
1480
1481 void DFSanVisitor::visitMemSetInst(MemSetInst &I) {
1482   IRBuilder<> IRB(&I);
1483   Value *ValShadow = DFSF.getShadow(I.getValue());
1484   IRB.CreateCall(DFSF.DFS.DFSanSetLabelFn,
1485                  {ValShadow, IRB.CreateBitCast(I.getDest(), Type::getInt8PtrTy(
1486                                                                 *DFSF.DFS.Ctx)),
1487                   IRB.CreateZExtOrTrunc(I.getLength(), DFSF.DFS.IntptrTy)});
1488 }
1489
1490 void DFSanVisitor::visitMemTransferInst(MemTransferInst &I) {
1491   IRBuilder<> IRB(&I);
1492   Value *DestShadow = DFSF.DFS.getShadowAddress(I.getDest(), &I);
1493   Value *SrcShadow = DFSF.DFS.getShadowAddress(I.getSource(), &I);
1494   Value *LenShadow = IRB.CreateMul(
1495       I.getLength(),
1496       ConstantInt::get(I.getLength()->getType(), DFSF.DFS.ShadowWidth / 8));
1497   Type *Int8Ptr = Type::getInt8PtrTy(*DFSF.DFS.Ctx);
1498   DestShadow = IRB.CreateBitCast(DestShadow, Int8Ptr);
1499   SrcShadow = IRB.CreateBitCast(SrcShadow, Int8Ptr);
1500   auto *MTI = cast<MemTransferInst>(
1501       IRB.CreateCall(I.getFunctionType(), I.getCalledValue(),
1502                      {DestShadow, SrcShadow, LenShadow, I.getVolatileCst()}));
1503   if (ClPreserveAlignment) {
1504     MTI->setDestAlignment(I.getDestAlignment() * (DFSF.DFS.ShadowWidth / 8));
1505     MTI->setSourceAlignment(I.getSourceAlignment() * (DFSF.DFS.ShadowWidth / 8));
1506   } else {
1507     MTI->setDestAlignment(DFSF.DFS.ShadowWidth / 8);
1508     MTI->setSourceAlignment(DFSF.DFS.ShadowWidth / 8);
1509   }
1510 }
1511
1512 void DFSanVisitor::visitReturnInst(ReturnInst &RI) {
1513   if (!DFSF.IsNativeABI && RI.getReturnValue()) {
1514     switch (DFSF.IA) {
1515     case DataFlowSanitizer::IA_TLS: {
1516       Value *S = DFSF.getShadow(RI.getReturnValue());
1517       IRBuilder<> IRB(&RI);
1518       IRB.CreateStore(S, DFSF.getRetvalTLS());
1519       break;
1520     }
1521     case DataFlowSanitizer::IA_Args: {
1522       IRBuilder<> IRB(&RI);
1523       Type *RT = DFSF.F->getFunctionType()->getReturnType();
1524       Value *InsVal =
1525           IRB.CreateInsertValue(UndefValue::get(RT), RI.getReturnValue(), 0);
1526       Value *InsShadow =
1527           IRB.CreateInsertValue(InsVal, DFSF.getShadow(RI.getReturnValue()), 1);
1528       RI.setOperand(0, InsShadow);
1529       break;
1530     }
1531     }
1532   }
1533 }
1534
1535 void DFSanVisitor::visitCallSite(CallSite CS) {
1536   Function *F = CS.getCalledFunction();
1537   if ((F && F->isIntrinsic()) || isa<InlineAsm>(CS.getCalledValue())) {
1538     visitOperandShadowInst(*CS.getInstruction());
1539     return;
1540   }
1541
1542   // Calls to this function are synthesized in wrappers, and we shouldn't
1543   // instrument them.
1544   if (F == DFSF.DFS.DFSanVarargWrapperFn.getCallee()->stripPointerCasts())
1545     return;
1546
1547   IRBuilder<> IRB(CS.getInstruction());
1548
1549   DenseMap<Value *, Function *>::iterator i =
1550       DFSF.DFS.UnwrappedFnMap.find(CS.getCalledValue());
1551   if (i != DFSF.DFS.UnwrappedFnMap.end()) {
1552     Function *F = i->second;
1553     switch (DFSF.DFS.getWrapperKind(F)) {
1554     case DataFlowSanitizer::WK_Warning:
1555       CS.setCalledFunction(F);
1556       IRB.CreateCall(DFSF.DFS.DFSanUnimplementedFn,
1557                      IRB.CreateGlobalStringPtr(F->getName()));
1558       DFSF.setShadow(CS.getInstruction(), DFSF.DFS.ZeroShadow);
1559       return;
1560     case DataFlowSanitizer::WK_Discard:
1561       CS.setCalledFunction(F);
1562       DFSF.setShadow(CS.getInstruction(), DFSF.DFS.ZeroShadow);
1563       return;
1564     case DataFlowSanitizer::WK_Functional:
1565       CS.setCalledFunction(F);
1566       visitOperandShadowInst(*CS.getInstruction());
1567       return;
1568     case DataFlowSanitizer::WK_Custom:
1569       // Don't try to handle invokes of custom functions, it's too complicated.
1570       // Instead, invoke the dfsw$ wrapper, which will in turn call the __dfsw_
1571       // wrapper.
1572       if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction())) {
1573         FunctionType *FT = F->getFunctionType();
1574         TransformedFunction CustomFn = DFSF.DFS.getCustomFunctionType(FT);
1575         std::string CustomFName = "__dfsw_";
1576         CustomFName += F->getName();
1577         FunctionCallee CustomF = DFSF.DFS.Mod->getOrInsertFunction(
1578             CustomFName, CustomFn.TransformedType);
1579         if (Function *CustomFn = dyn_cast<Function>(CustomF.getCallee())) {
1580           CustomFn->copyAttributesFrom(F);
1581
1582           // Custom functions returning non-void will write to the return label.
1583           if (!FT->getReturnType()->isVoidTy()) {
1584             CustomFn->removeAttributes(AttributeList::FunctionIndex,
1585                                        DFSF.DFS.ReadOnlyNoneAttrs);
1586           }
1587         }
1588
1589         std::vector<Value *> Args;
1590
1591         CallSite::arg_iterator i = CS.arg_begin();
1592         for (unsigned n = FT->getNumParams(); n != 0; ++i, --n) {
1593           Type *T = (*i)->getType();
1594           FunctionType *ParamFT;
1595           if (isa<PointerType>(T) &&
1596               (ParamFT = dyn_cast<FunctionType>(
1597                    cast<PointerType>(T)->getElementType()))) {
1598             std::string TName = "dfst";
1599             TName += utostr(FT->getNumParams() - n);
1600             TName += "$";
1601             TName += F->getName();
1602             Constant *T = DFSF.DFS.getOrBuildTrampolineFunction(ParamFT, TName);
1603             Args.push_back(T);
1604             Args.push_back(
1605                 IRB.CreateBitCast(*i, Type::getInt8PtrTy(*DFSF.DFS.Ctx)));
1606           } else {
1607             Args.push_back(*i);
1608           }
1609         }
1610
1611         i = CS.arg_begin();
1612         const unsigned ShadowArgStart = Args.size();
1613         for (unsigned n = FT->getNumParams(); n != 0; ++i, --n)
1614           Args.push_back(DFSF.getShadow(*i));
1615
1616         if (FT->isVarArg()) {
1617           auto *LabelVATy = ArrayType::get(DFSF.DFS.ShadowTy,
1618                                            CS.arg_size() - FT->getNumParams());
1619           auto *LabelVAAlloca = new AllocaInst(
1620               LabelVATy, getDataLayout().getAllocaAddrSpace(),
1621               "labelva", &DFSF.F->getEntryBlock().front());
1622
1623           for (unsigned n = 0; i != CS.arg_end(); ++i, ++n) {
1624             auto LabelVAPtr = IRB.CreateStructGEP(LabelVATy, LabelVAAlloca, n);
1625             IRB.CreateStore(DFSF.getShadow(*i), LabelVAPtr);
1626           }
1627
1628           Args.push_back(IRB.CreateStructGEP(LabelVATy, LabelVAAlloca, 0));
1629         }
1630
1631         if (!FT->getReturnType()->isVoidTy()) {
1632           if (!DFSF.LabelReturnAlloca) {
1633             DFSF.LabelReturnAlloca =
1634               new AllocaInst(DFSF.DFS.ShadowTy,
1635                              getDataLayout().getAllocaAddrSpace(),
1636                              "labelreturn", &DFSF.F->getEntryBlock().front());
1637           }
1638           Args.push_back(DFSF.LabelReturnAlloca);
1639         }
1640
1641         for (i = CS.arg_begin() + FT->getNumParams(); i != CS.arg_end(); ++i)
1642           Args.push_back(*i);
1643
1644         CallInst *CustomCI = IRB.CreateCall(CustomF, Args);
1645         CustomCI->setCallingConv(CI->getCallingConv());
1646         CustomCI->setAttributes(TransformFunctionAttributes(CustomFn,
1647             CI->getContext(), CI->getAttributes()));
1648
1649         // Update the parameter attributes of the custom call instruction to
1650         // zero extend the shadow parameters. This is required for targets
1651         // which consider ShadowTy an illegal type.
1652         for (unsigned n = 0; n < FT->getNumParams(); n++) {
1653           const unsigned ArgNo = ShadowArgStart + n;
1654           if (CustomCI->getArgOperand(ArgNo)->getType() == DFSF.DFS.ShadowTy)
1655             CustomCI->addParamAttr(ArgNo, Attribute::ZExt);
1656         }
1657
1658         if (!FT->getReturnType()->isVoidTy()) {
1659           LoadInst *LabelLoad =
1660               IRB.CreateLoad(DFSF.DFS.ShadowTy, DFSF.LabelReturnAlloca);
1661           DFSF.setShadow(CustomCI, LabelLoad);
1662         }
1663
1664         CI->replaceAllUsesWith(CustomCI);
1665         CI->eraseFromParent();
1666         return;
1667       }
1668       break;
1669     }
1670   }
1671
1672   FunctionType *FT = cast<FunctionType>(
1673       CS.getCalledValue()->getType()->getPointerElementType());
1674   if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_TLS) {
1675     for (unsigned i = 0, n = FT->getNumParams(); i != n; ++i) {
1676       IRB.CreateStore(DFSF.getShadow(CS.getArgument(i)),
1677                       DFSF.getArgTLS(i, CS.getInstruction()));
1678     }
1679   }
1680
1681   Instruction *Next = nullptr;
1682   if (!CS.getType()->isVoidTy()) {
1683     if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
1684       if (II->getNormalDest()->getSinglePredecessor()) {
1685         Next = &II->getNormalDest()->front();
1686       } else {
1687         BasicBlock *NewBB =
1688             SplitEdge(II->getParent(), II->getNormalDest(), &DFSF.DT);
1689         Next = &NewBB->front();
1690       }
1691     } else {
1692       assert(CS->getIterator() != CS->getParent()->end());
1693       Next = CS->getNextNode();
1694     }
1695
1696     if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_TLS) {
1697       IRBuilder<> NextIRB(Next);
1698       LoadInst *LI = NextIRB.CreateLoad(DFSF.DFS.ShadowTy, DFSF.getRetvalTLS());
1699       DFSF.SkipInsts.insert(LI);
1700       DFSF.setShadow(CS.getInstruction(), LI);
1701       DFSF.NonZeroChecks.push_back(LI);
1702     }
1703   }
1704
1705   // Do all instrumentation for IA_Args down here to defer tampering with the
1706   // CFG in a way that SplitEdge may be able to detect.
1707   if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_Args) {
1708     FunctionType *NewFT = DFSF.DFS.getArgsFunctionType(FT);
1709     Value *Func =
1710         IRB.CreateBitCast(CS.getCalledValue(), PointerType::getUnqual(NewFT));
1711     std::vector<Value *> Args;
1712
1713     CallSite::arg_iterator i = CS.arg_begin(), e = CS.arg_end();
1714     for (unsigned n = FT->getNumParams(); n != 0; ++i, --n)
1715       Args.push_back(*i);
1716
1717     i = CS.arg_begin();
1718     for (unsigned n = FT->getNumParams(); n != 0; ++i, --n)
1719       Args.push_back(DFSF.getShadow(*i));
1720
1721     if (FT->isVarArg()) {
1722       unsigned VarArgSize = CS.arg_size() - FT->getNumParams();
1723       ArrayType *VarArgArrayTy = ArrayType::get(DFSF.DFS.ShadowTy, VarArgSize);
1724       AllocaInst *VarArgShadow =
1725         new AllocaInst(VarArgArrayTy, getDataLayout().getAllocaAddrSpace(),
1726                        "", &DFSF.F->getEntryBlock().front());
1727       Args.push_back(IRB.CreateConstGEP2_32(VarArgArrayTy, VarArgShadow, 0, 0));
1728       for (unsigned n = 0; i != e; ++i, ++n) {
1729         IRB.CreateStore(
1730             DFSF.getShadow(*i),
1731             IRB.CreateConstGEP2_32(VarArgArrayTy, VarArgShadow, 0, n));
1732         Args.push_back(*i);
1733       }
1734     }
1735
1736     CallSite NewCS;
1737     if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
1738       NewCS = IRB.CreateInvoke(NewFT, Func, II->getNormalDest(),
1739                                II->getUnwindDest(), Args);
1740     } else {
1741       NewCS = IRB.CreateCall(NewFT, Func, Args);
1742     }
1743     NewCS.setCallingConv(CS.getCallingConv());
1744     NewCS.setAttributes(CS.getAttributes().removeAttributes(
1745         *DFSF.DFS.Ctx, AttributeList::ReturnIndex,
1746         AttributeFuncs::typeIncompatible(NewCS.getInstruction()->getType())));
1747
1748     if (Next) {
1749       ExtractValueInst *ExVal =
1750           ExtractValueInst::Create(NewCS.getInstruction(), 0, "", Next);
1751       DFSF.SkipInsts.insert(ExVal);
1752       ExtractValueInst *ExShadow =
1753           ExtractValueInst::Create(NewCS.getInstruction(), 1, "", Next);
1754       DFSF.SkipInsts.insert(ExShadow);
1755       DFSF.setShadow(ExVal, ExShadow);
1756       DFSF.NonZeroChecks.push_back(ExShadow);
1757
1758       CS.getInstruction()->replaceAllUsesWith(ExVal);
1759     }
1760
1761     CS.getInstruction()->eraseFromParent();
1762   }
1763 }
1764
1765 void DFSanVisitor::visitPHINode(PHINode &PN) {
1766   PHINode *ShadowPN =
1767       PHINode::Create(DFSF.DFS.ShadowTy, PN.getNumIncomingValues(), "", &PN);
1768
1769   // Give the shadow phi node valid predecessors to fool SplitEdge into working.
1770   Value *UndefShadow = UndefValue::get(DFSF.DFS.ShadowTy);
1771   for (PHINode::block_iterator i = PN.block_begin(), e = PN.block_end(); i != e;
1772        ++i) {
1773     ShadowPN->addIncoming(UndefShadow, *i);
1774   }
1775
1776   DFSF.PHIFixups.push_back(std::make_pair(&PN, ShadowPN));
1777   DFSF.setShadow(&PN, ShadowPN);
1778 }