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 visitBinaryOperator(BinaryOperator &BO);
 441   void visitCastInst(CastInst &CI);
 442   void visitCmpInst(CmpInst &CI);
 443   void visitGetElementPtrInst(GetElementPtrInst &GEPI);
 444   void visitLoadInst(LoadInst &LI);
 445   void visitStoreInst(StoreInst &SI);
 446   void visitReturnInst(ReturnInst &RI);
 447   void visitCallSite(CallSite CS);
 448   void visitPHINode(PHINode &PN);
 449   void visitExtractElementInst(ExtractElementInst &I);
 450   void visitInsertElementInst(InsertElementInst &I);
 451   void visitShuffleVectorInst(ShuffleVectorInst &I);
 452   void visitExtractValueInst(ExtractValueInst &I);
 453   void visitInsertValueInst(InsertValueInst &I);
 454   void visitAllocaInst(AllocaInst &I);
 455   void visitSelectInst(SelectInst &I);
 456   void visitMemSetInst(MemSetInst &I);
 457   void visitMemTransferInst(MemTransferInst &I);
 458 };
 459
 460 } // end anonymous namespace
 461
 462 char DataFlowSanitizer::ID;
 463
 464 INITIALIZE_PASS(DataFlowSanitizer, "dfsan",
 465                 "DataFlowSanitizer: dynamic data flow analysis.", false, false)
 466
 467 ModulePass *
 468 llvm::createDataFlowSanitizerPass(const std::vector<std::string> &ABIListFiles,
 469                                   void *(*getArgTLS)(),
 470                                   void *(*getRetValTLS)()) {
 471   return new DataFlowSanitizer(ABIListFiles, getArgTLS, getRetValTLS);
 472 }
 473
 474 DataFlowSanitizer::DataFlowSanitizer(
 475     const std::vector<std::string> &ABIListFiles, void *(*getArgTLS)(),
 476     void *(*getRetValTLS)())
 477     : ModulePass(ID), GetArgTLSPtr(getArgTLS), GetRetvalTLSPtr(getRetValTLS) {
 478   std::vector<std::string> AllABIListFiles(std::move(ABIListFiles));
 479   AllABIListFiles.insert(AllABIListFiles.end(), ClABIListFiles.begin(),
 480                          ClABIListFiles.end());
 481   ABIList.set(SpecialCaseList::createOrDie(AllABIListFiles));
 482 }
 483
 484 FunctionType *DataFlowSanitizer::getArgsFunctionType(FunctionType *T) {
 485   SmallVector<Type *, 4> ArgTypes(T->param_begin(), T->param_end());
 486   ArgTypes.append(T->getNumParams(), ShadowTy);
 487   if (T->isVarArg())
 488     ArgTypes.push_back(ShadowPtrTy);
 489   Type *RetType = T->getReturnType();
 490   if (!RetType->isVoidTy())
 491     RetType = StructType::get(RetType, ShadowTy);
 492   return FunctionType::get(RetType, ArgTypes, T->isVarArg());
 493 }
 494
 495 FunctionType *DataFlowSanitizer::getTrampolineFunctionType(FunctionType *T) {
 496   assert(!T->isVarArg());
 497   SmallVector<Type *, 4> ArgTypes;
 498   ArgTypes.push_back(T->getPointerTo());
 499   ArgTypes.append(T->param_begin(), T->param_end());
 500   ArgTypes.append(T->getNumParams(), ShadowTy);
 501   Type *RetType = T->getReturnType();
 502   if (!RetType->isVoidTy())
 503     ArgTypes.push_back(ShadowPtrTy);
 504   return FunctionType::get(T->getReturnType(), ArgTypes, false);
 505 }
 506
 507 TransformedFunction DataFlowSanitizer::getCustomFunctionType(FunctionType *T) {
 508   SmallVector<Type *, 4> ArgTypes;
 509
 510   // Some parameters of the custom function being constructed are
 511   // parameters of T.  Record the mapping from parameters of T to
 512   // parameters of the custom function, so that parameter attributes
 513   // at call sites can be updated.
 514   std::vector<unsigned> ArgumentIndexMapping;
 515   for (unsigned i = 0, ie = T->getNumParams(); i != ie; ++i) {
 516     Type* param_type = T->getParamType(i);
 517     FunctionType *FT;
 518     if (isa<PointerType>(param_type) && (FT = dyn_cast<FunctionType>(
 519             cast<PointerType>(param_type)->getElementType()))) {
 520       ArgumentIndexMapping.push_back(ArgTypes.size());
 521       ArgTypes.push_back(getTrampolineFunctionType(FT)->getPointerTo());
 522       ArgTypes.push_back(Type::getInt8PtrTy(*Ctx));
 523     } else {
 524       ArgumentIndexMapping.push_back(ArgTypes.size());
 525       ArgTypes.push_back(param_type);
 526     }
 527   }
 528   for (unsigned i = 0, e = T->getNumParams(); i != e; ++i)
 529     ArgTypes.push_back(ShadowTy);
 530   if (T->isVarArg())
 531     ArgTypes.push_back(ShadowPtrTy);
 532   Type *RetType = T->getReturnType();
 533   if (!RetType->isVoidTy())
 534     ArgTypes.push_back(ShadowPtrTy);
 535   return TransformedFunction(
 536       T, FunctionType::get(T->getReturnType(), ArgTypes, T->isVarArg()),
 537       ArgumentIndexMapping);
 538 }
 539
 540 bool DataFlowSanitizer::doInitialization(Module &M) {
 541   Triple TargetTriple(M.getTargetTriple());
 542   bool IsX86_64 = TargetTriple.getArch() == Triple::x86_64;
 543   bool IsMIPS64 = TargetTriple.isMIPS64();
 544   bool IsAArch64 = TargetTriple.getArch() == Triple::aarch64 ||
 545                    TargetTriple.getArch() == Triple::aarch64_be;
 546
 547   const DataLayout &DL = M.getDataLayout();
 548
 549   Mod = &M;
 550   Ctx = &M.getContext();
 551   ShadowTy = IntegerType::get(*Ctx, ShadowWidth);
 552   ShadowPtrTy = PointerType::getUnqual(ShadowTy);
 553   IntptrTy = DL.getIntPtrType(*Ctx);
 554   ZeroShadow = ConstantInt::getSigned(ShadowTy, 0);
 555   ShadowPtrMul = ConstantInt::getSigned(IntptrTy, ShadowWidth / 8);
 556   if (IsX86_64)
 557     ShadowPtrMask = ConstantInt::getSigned(IntptrTy, ~0x700000000000LL);
 558   else if (IsMIPS64)
 559     ShadowPtrMask = ConstantInt::getSigned(IntptrTy, ~0xF000000000LL);
 560   // AArch64 supports multiple VMAs and the shadow mask is set at runtime.
 561   else if (IsAArch64)
 562     DFSanRuntimeShadowMask = true;
 563   else
 564     report_fatal_error("unsupported triple");
 565
 566   Type *DFSanUnionArgs[2] = { ShadowTy, ShadowTy };
 567   DFSanUnionFnTy =
 568       FunctionType::get(ShadowTy, DFSanUnionArgs, /*isVarArg=*/ false);
 569   Type *DFSanUnionLoadArgs[2] = { ShadowPtrTy, IntptrTy };
 570   DFSanUnionLoadFnTy =
 571       FunctionType::get(ShadowTy, DFSanUnionLoadArgs, /*isVarArg=*/ false);
 572   DFSanUnimplementedFnTy = FunctionType::get(
 573       Type::getVoidTy(*Ctx), Type::getInt8PtrTy(*Ctx), /*isVarArg=*/false);
 574   Type *DFSanSetLabelArgs[3] = { ShadowTy, Type::getInt8PtrTy(*Ctx), IntptrTy };
 575   DFSanSetLabelFnTy = FunctionType::get(Type::getVoidTy(*Ctx),
 576                                         DFSanSetLabelArgs, /*isVarArg=*/false);
 577   DFSanNonzeroLabelFnTy = FunctionType::get(
 578       Type::getVoidTy(*Ctx), None, /*isVarArg=*/false);
 579   DFSanVarargWrapperFnTy = FunctionType::get(
 580       Type::getVoidTy(*Ctx), Type::getInt8PtrTy(*Ctx), /*isVarArg=*/false);
 581
 582   if (GetArgTLSPtr) {
 583     Type *ArgTLSTy = ArrayType::get(ShadowTy, 64);
 584     ArgTLS = nullptr;
 585     GetArgTLSTy = FunctionType::get(PointerType::getUnqual(ArgTLSTy), false);
 586     GetArgTLS = ConstantExpr::getIntToPtr(
 587         ConstantInt::get(IntptrTy, uintptr_t(GetArgTLSPtr)),
 588         PointerType::getUnqual(GetArgTLSTy));
 589   }
 590   if (GetRetvalTLSPtr) {
 591     RetvalTLS = nullptr;
 592     GetRetvalTLSTy = FunctionType::get(PointerType::getUnqual(ShadowTy), false);
 593     GetRetvalTLS = ConstantExpr::getIntToPtr(
 594         ConstantInt::get(IntptrTy, uintptr_t(GetRetvalTLSPtr)),
 595         PointerType::getUnqual(GetRetvalTLSTy));
 596   }
 597
 598   ColdCallWeights = MDBuilder(*Ctx).createBranchWeights(1, 1000);
 599   return true;
 600 }
 601
 602 bool DataFlowSanitizer::isInstrumented(const Function *F) {
 603   return !ABIList.isIn(*F, "uninstrumented");
 604 }
 605
 606 bool DataFlowSanitizer::isInstrumented(const GlobalAlias *GA) {
 607   return !ABIList.isIn(*GA, "uninstrumented");
 608 }
 609
 610 DataFlowSanitizer::InstrumentedABI DataFlowSanitizer::getInstrumentedABI() {
 611   return ClArgsABI ? IA_Args : IA_TLS;
 612 }
 613
 614 DataFlowSanitizer::WrapperKind DataFlowSanitizer::getWrapperKind(Function *F) {
 615   if (ABIList.isIn(*F, "functional"))
 616     return WK_Functional;
 617   if (ABIList.isIn(*F, "discard"))
 618     return WK_Discard;
 619   if (ABIList.isIn(*F, "custom"))
 620     return WK_Custom;
 621
 622   return WK_Warning;
 623 }
 624
 625 void DataFlowSanitizer::addGlobalNamePrefix(GlobalValue *GV) {
 626   std::string GVName = GV->getName(), Prefix = "dfs$";
 627   GV->setName(Prefix + GVName);
 628
 629   // Try to change the name of the function in module inline asm.  We only do
 630   // this for specific asm directives, currently only ".symver", to try to avoid
 631   // corrupting asm which happens to contain the symbol name as a substring.
 632   // Note that the substitution for .symver assumes that the versioned symbol
 633   // also has an instrumented name.
 634   std::string Asm = GV->getParent()->getModuleInlineAsm();
 635   std::string SearchStr = ".symver " + GVName + ",";
 636   size_t Pos = Asm.find(SearchStr);
 637   if (Pos != std::string::npos) {
 638     Asm.replace(Pos, SearchStr.size(),
 639                 ".symver " + Prefix + GVName + "," + Prefix);
 640     GV->getParent()->setModuleInlineAsm(Asm);
 641   }
 642 }
 643
 644 Function *
 645 DataFlowSanitizer::buildWrapperFunction(Function *F, StringRef NewFName,
 646                                         GlobalValue::LinkageTypes NewFLink,
 647                                         FunctionType *NewFT) {
 648   FunctionType *FT = F->getFunctionType();
 649   Function *NewF = Function::Create(NewFT, NewFLink, F->getAddressSpace(),
 650                                     NewFName, F->getParent());
 651   NewF->copyAttributesFrom(F);
 652   NewF->removeAttributes(
 653       AttributeList::ReturnIndex,
 654       AttributeFuncs::typeIncompatible(NewFT->getReturnType()));
 655
 656   BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", NewF);
 657   if (F->isVarArg()) {
 658     NewF->removeAttributes(AttributeList::FunctionIndex,
 659                            AttrBuilder().addAttribute("split-stack"));
 660     CallInst::Create(DFSanVarargWrapperFn,
 661                      IRBuilder<>(BB).CreateGlobalStringPtr(F->getName()), "",
 662                      BB);
 663     new UnreachableInst(*Ctx, BB);
 664   } else {
 665     std::vector<Value *> Args;
 666     unsigned n = FT->getNumParams();
 667     for (Function::arg_iterator ai = NewF->arg_begin(); n != 0; ++ai, --n)
 668       Args.push_back(&*ai);
 669     CallInst *CI = CallInst::Create(F, Args, "", BB);
 670     if (FT->getReturnType()->isVoidTy())
 671       ReturnInst::Create(*Ctx, BB);
 672     else
 673       ReturnInst::Create(*Ctx, CI, BB);
 674   }
 675
 676   return NewF;
 677 }
 678
 679 Constant *DataFlowSanitizer::getOrBuildTrampolineFunction(FunctionType *FT,
 680                                                           StringRef FName) {
 681   FunctionType *FTT = getTrampolineFunctionType(FT);
 682   FunctionCallee C = Mod->getOrInsertFunction(FName, FTT);
 683   Function *F = dyn_cast<Function>(C.getCallee());
 684   if (F && F->isDeclaration()) {
 685     F->setLinkage(GlobalValue::LinkOnceODRLinkage);
 686     BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", F);
 687     std::vector<Value *> Args;
 688     Function::arg_iterator AI = F->arg_begin(); ++AI;
 689     for (unsigned N = FT->getNumParams(); N != 0; ++AI, --N)
 690       Args.push_back(&*AI);
 691     CallInst *CI = CallInst::Create(FT, &*F->arg_begin(), Args, "", BB);
 692     ReturnInst *RI;
 693     if (FT->getReturnType()->isVoidTy())
 694       RI = ReturnInst::Create(*Ctx, BB);
 695     else
 696       RI = ReturnInst::Create(*Ctx, CI, BB);
 697
 698     DFSanFunction DFSF(*this, F, /*IsNativeABI=*/true);
 699     Function::arg_iterator ValAI = F->arg_begin(), ShadowAI = AI; ++ValAI;
 700     for (unsigned N = FT->getNumParams(); N != 0; ++ValAI, ++ShadowAI, --N)
 701       DFSF.ValShadowMap[&*ValAI] = &*ShadowAI;
 702     DFSanVisitor(DFSF).visitCallInst(*CI);
 703     if (!FT->getReturnType()->isVoidTy())
 704       new StoreInst(DFSF.getShadow(RI->getReturnValue()),
 705                     &*std::prev(F->arg_end()), RI);
 706   }
 707
 708   return cast<Constant>(C.getCallee());
 709 }
 710
 711 bool DataFlowSanitizer::runOnModule(Module &M) {
 712   if (ABIList.isIn(M, "skip"))
 713     return false;
 714
 715   if (!GetArgTLSPtr) {
 716     Type *ArgTLSTy = ArrayType::get(ShadowTy, 64);
 717     ArgTLS = Mod->getOrInsertGlobal("__dfsan_arg_tls", ArgTLSTy);
 718     if (GlobalVariable *G = dyn_cast<GlobalVariable>(ArgTLS))
 719       G->setThreadLocalMode(GlobalVariable::InitialExecTLSModel);
 720   }
 721   if (!GetRetvalTLSPtr) {
 722     RetvalTLS = Mod->getOrInsertGlobal("__dfsan_retval_tls", ShadowTy);
 723     if (GlobalVariable *G = dyn_cast<GlobalVariable>(RetvalTLS))
 724       G->setThreadLocalMode(GlobalVariable::InitialExecTLSModel);
 725   }
 726
 727   ExternalShadowMask =
 728       Mod->getOrInsertGlobal(kDFSanExternShadowPtrMask, IntptrTy);
 729
 730   {
 731     AttributeList AL;
 732     AL = AL.addAttribute(M.getContext(), AttributeList::FunctionIndex,
 733                          Attribute::NoUnwind);
 734     AL = AL.addAttribute(M.getContext(), AttributeList::FunctionIndex,
 735                          Attribute::ReadNone);
 736     AL = AL.addAttribute(M.getContext(), AttributeList::ReturnIndex,
 737                          Attribute::ZExt);
 738     AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
 739     AL = AL.addParamAttribute(M.getContext(), 1, Attribute::ZExt);
 740     DFSanUnionFn =
 741         Mod->getOrInsertFunction("__dfsan_union", DFSanUnionFnTy, AL);
 742   }
 743
 744   {
 745     AttributeList AL;
 746     AL = AL.addAttribute(M.getContext(), AttributeList::FunctionIndex,
 747                          Attribute::NoUnwind);
 748     AL = AL.addAttribute(M.getContext(), AttributeList::FunctionIndex,
 749                          Attribute::ReadNone);
 750     AL = AL.addAttribute(M.getContext(), AttributeList::ReturnIndex,
 751                          Attribute::ZExt);
 752     AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
 753     AL = AL.addParamAttribute(M.getContext(), 1, Attribute::ZExt);
 754     DFSanCheckedUnionFn =
 755         Mod->getOrInsertFunction("dfsan_union", DFSanUnionFnTy, AL);
 756   }
 757   {
 758     AttributeList AL;
 759     AL = AL.addAttribute(M.getContext(), AttributeList::FunctionIndex,
 760                          Attribute::NoUnwind);
 761     AL = AL.addAttribute(M.getContext(), AttributeList::FunctionIndex,
 762                          Attribute::ReadOnly);
 763     AL = AL.addAttribute(M.getContext(), AttributeList::ReturnIndex,
 764                          Attribute::ZExt);
 765     DFSanUnionLoadFn =
 766         Mod->getOrInsertFunction("__dfsan_union_load", DFSanUnionLoadFnTy, AL);
 767   }
 768   DFSanUnimplementedFn =
 769       Mod->getOrInsertFunction("__dfsan_unimplemented", DFSanUnimplementedFnTy);
 770   {
 771     AttributeList AL;
 772     AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
 773     DFSanSetLabelFn =
 774         Mod->getOrInsertFunction("__dfsan_set_label", DFSanSetLabelFnTy, AL);
 775   }
 776   DFSanNonzeroLabelFn =
 777       Mod->getOrInsertFunction("__dfsan_nonzero_label", DFSanNonzeroLabelFnTy);
 778   DFSanVarargWrapperFn = Mod->getOrInsertFunction("__dfsan_vararg_wrapper",
 779                                                   DFSanVarargWrapperFnTy);
 780
 781   std::vector<Function *> FnsToInstrument;
 782   SmallPtrSet<Function *, 2> FnsWithNativeABI;
 783   for (Function &i : M) {
 784     if (!i.isIntrinsic() &&
 785         &i != DFSanUnionFn.getCallee()->stripPointerCasts() &&
 786         &i != DFSanCheckedUnionFn.getCallee()->stripPointerCasts() &&
 787         &i != DFSanUnionLoadFn.getCallee()->stripPointerCasts() &&
 788         &i != DFSanUnimplementedFn.getCallee()->stripPointerCasts() &&
 789         &i != DFSanSetLabelFn.getCallee()->stripPointerCasts() &&
 790         &i != DFSanNonzeroLabelFn.getCallee()->stripPointerCasts() &&
 791         &i != DFSanVarargWrapperFn.getCallee()->stripPointerCasts())
 792       FnsToInstrument.push_back(&i);
 793   }
 794
 795   // Give function aliases prefixes when necessary, and build wrappers where the
 796   // instrumentedness is inconsistent.
 797   for (Module::alias_iterator i = M.alias_begin(), e = M.alias_end(); i != e;) {
 798     GlobalAlias *GA = &*i;
 799     ++i;
 800     // Don't stop on weak.  We assume people aren't playing games with the
 801     // instrumentedness of overridden weak aliases.
 802     if (auto F = dyn_cast<Function>(GA->getBaseObject())) {
 803       bool GAInst = isInstrumented(GA), FInst = isInstrumented(F);
 804       if (GAInst && FInst) {
 805         addGlobalNamePrefix(GA);
 806       } else if (GAInst != FInst) {
 807         // Non-instrumented alias of an instrumented function, or vice versa.
 808         // Replace the alias with a native-ABI wrapper of the aliasee.  The pass
 809         // below will take care of instrumenting it.
 810         Function *NewF =
 811             buildWrapperFunction(F, "", GA->getLinkage(), F->getFunctionType());
 812         GA->replaceAllUsesWith(ConstantExpr::getBitCast(NewF, GA->getType()));
 813         NewF->takeName(GA);
 814         GA->eraseFromParent();
 815         FnsToInstrument.push_back(NewF);
 816       }
 817     }
 818   }
 819
 820   ReadOnlyNoneAttrs.addAttribute(Attribute::ReadOnly)
 821       .addAttribute(Attribute::ReadNone);
 822
 823   // First, change the ABI of every function in the module.  ABI-listed
 824   // functions keep their original ABI and get a wrapper function.
 825   for (std::vector<Function *>::iterator i = FnsToInstrument.begin(),
 826                                          e = FnsToInstrument.end();
 827        i != e; ++i) {
 828     Function &F = **i;
 829     FunctionType *FT = F.getFunctionType();
 830
 831     bool IsZeroArgsVoidRet = (FT->getNumParams() == 0 && !FT->isVarArg() &&
 832                               FT->getReturnType()->isVoidTy());
 833
 834     if (isInstrumented(&F)) {
 835       // Instrumented functions get a 'dfs$' prefix.  This allows us to more
 836       // easily identify cases of mismatching ABIs.
 837       if (getInstrumentedABI() == IA_Args && !IsZeroArgsVoidRet) {
 838         FunctionType *NewFT = getArgsFunctionType(FT);
 839         Function *NewF = Function::Create(NewFT, F.getLinkage(),
 840                                           F.getAddressSpace(), "", &M);
 841         NewF->copyAttributesFrom(&F);
 842         NewF->removeAttributes(
 843             AttributeList::ReturnIndex,
 844             AttributeFuncs::typeIncompatible(NewFT->getReturnType()));
 845         for (Function::arg_iterator FArg = F.arg_begin(),
 846                                     NewFArg = NewF->arg_begin(),
 847                                     FArgEnd = F.arg_end();
 848              FArg != FArgEnd; ++FArg, ++NewFArg) {
 849           FArg->replaceAllUsesWith(&*NewFArg);
 850         }
 851         NewF->getBasicBlockList().splice(NewF->begin(), F.getBasicBlockList());
 852
 853         for (Function::user_iterator UI = F.user_begin(), UE = F.user_end();
 854              UI != UE;) {
 855           BlockAddress *BA = dyn_cast<BlockAddress>(*UI);
 856           ++UI;
 857           if (BA) {
 858             BA->replaceAllUsesWith(
 859                 BlockAddress::get(NewF, BA->getBasicBlock()));
 860             delete BA;
 861           }
 862         }
 863         F.replaceAllUsesWith(
 864             ConstantExpr::getBitCast(NewF, PointerType::getUnqual(FT)));
 865         NewF->takeName(&F);
 866         F.eraseFromParent();
 867         *i = NewF;
 868         addGlobalNamePrefix(NewF);
 869       } else {
 870         addGlobalNamePrefix(&F);
 871       }
 872     } else if (!IsZeroArgsVoidRet || getWrapperKind(&F) == WK_Custom) {
 873       // Build a wrapper function for F.  The wrapper simply calls F, and is
 874       // added to FnsToInstrument so that any instrumentation according to its
 875       // WrapperKind is done in the second pass below.
 876       FunctionType *NewFT = getInstrumentedABI() == IA_Args
 877                                 ? getArgsFunctionType(FT)
 878                                 : FT;
 879
 880       // If the function being wrapped has local linkage, then preserve the
 881       // function's linkage in the wrapper function.
 882       GlobalValue::LinkageTypes wrapperLinkage =
 883           F.hasLocalLinkage()
 884               ? F.getLinkage()
 885               : GlobalValue::LinkOnceODRLinkage;
 886
 887       Function *NewF = buildWrapperFunction(
 888           &F, std::string("dfsw$") + std::string(F.getName()),
 889           wrapperLinkage, NewFT);
 890       if (getInstrumentedABI() == IA_TLS)
 891         NewF->removeAttributes(AttributeList::FunctionIndex, ReadOnlyNoneAttrs);
 892
 893       Value *WrappedFnCst =
 894           ConstantExpr::getBitCast(NewF, PointerType::getUnqual(FT));
 895       F.replaceAllUsesWith(WrappedFnCst);
 896
 897       UnwrappedFnMap[WrappedFnCst] = &F;
 898       *i = NewF;
 899
 900       if (!F.isDeclaration()) {
 901         // This function is probably defining an interposition of an
 902         // uninstrumented function and hence needs to keep the original ABI.
 903         // But any functions it may call need to use the instrumented ABI, so
 904         // we instrument it in a mode which preserves the original ABI.
 905         FnsWithNativeABI.insert(&F);
 906
 907         // This code needs to rebuild the iterators, as they may be invalidated
 908         // by the push_back, taking care that the new range does not include
 909         // any functions added by this code.
 910         size_t N = i - FnsToInstrument.begin(),
 911                Count = e - FnsToInstrument.begin();
 912         FnsToInstrument.push_back(&F);
 913         i = FnsToInstrument.begin() + N;
 914         e = FnsToInstrument.begin() + Count;
 915       }
 916                // Hopefully, nobody will try to indirectly call a vararg
 917                // function... yet.
 918     } else if (FT->isVarArg()) {
 919       UnwrappedFnMap[&F] = &F;
 920       *i = nullptr;
 921     }
 922   }
 923
 924   for (Function *i : FnsToInstrument) {
 925     if (!i || i->isDeclaration())
 926       continue;
 927
 928     removeUnreachableBlocks(*i);
 929
 930     DFSanFunction DFSF(*this, i, FnsWithNativeABI.count(i));
 931
 932     // DFSanVisitor may create new basic blocks, which confuses df_iterator.
 933     // Build a copy of the list before iterating over it.
 934     SmallVector<BasicBlock *, 4> BBList(depth_first(&i->getEntryBlock()));
 935
 936     for (BasicBlock *i : BBList) {
 937       Instruction *Inst = &i->front();
 938       while (true) {
 939         // DFSanVisitor may split the current basic block, changing the current
 940         // instruction's next pointer and moving the next instruction to the
 941         // tail block from which we should continue.
 942         Instruction *Next = Inst->getNextNode();
 943         // DFSanVisitor may delete Inst, so keep track of whether it was a
 944         // terminator.
 945         bool IsTerminator = Inst->isTerminator();
 946         if (!DFSF.SkipInsts.count(Inst))
 947           DFSanVisitor(DFSF).visit(Inst);
 948         if (IsTerminator)
 949           break;
 950         Inst = Next;
 951       }
 952     }
 953
 954     // We will not necessarily be able to compute the shadow for every phi node
 955     // until we have visited every block.  Therefore, the code that handles phi
 956     // nodes adds them to the PHIFixups list so that they can be properly
 957     // handled here.
 958     for (std::vector<std::pair<PHINode *, PHINode *>>::iterator
 959              i = DFSF.PHIFixups.begin(),
 960              e = DFSF.PHIFixups.end();
 961          i != e; ++i) {
 962       for (unsigned val = 0, n = i->first->getNumIncomingValues(); val != n;
 963            ++val) {
 964         i->second->setIncomingValue(
 965             val, DFSF.getShadow(i->first->getIncomingValue(val)));
 966       }
 967     }
 968
 969     // -dfsan-debug-nonzero-labels will split the CFG in all kinds of crazy
 970     // places (i.e. instructions in basic blocks we haven't even begun visiting
 971     // yet).  To make our life easier, do this work in a pass after the main
 972     // instrumentation.
 973     if (ClDebugNonzeroLabels) {
 974       for (Value *V : DFSF.NonZeroChecks) {
 975         Instruction *Pos;
 976         if (Instruction *I = dyn_cast<Instruction>(V))
 977           Pos = I->getNextNode();
 978         else
 979           Pos = &DFSF.F->getEntryBlock().front();
 980         while (isa<PHINode>(Pos) || isa<AllocaInst>(Pos))
 981           Pos = Pos->getNextNode();
 982         IRBuilder<> IRB(Pos);
 983         Value *Ne = IRB.CreateICmpNE(V, DFSF.DFS.ZeroShadow);
 984         BranchInst *BI = cast<BranchInst>(SplitBlockAndInsertIfThen(
 985             Ne, Pos, /*Unreachable=*/false, ColdCallWeights));
 986         IRBuilder<> ThenIRB(BI);
 987         ThenIRB.CreateCall(DFSF.DFS.DFSanNonzeroLabelFn, {});
 988       }
 989     }
 990   }
 991
 992   return false;
 993 }
 994
 995 Value *DFSanFunction::getArgTLSPtr() {
 996   if (ArgTLSPtr)
 997     return ArgTLSPtr;
 998   if (DFS.ArgTLS)
 999     return ArgTLSPtr = DFS.ArgTLS;
1000
1001   IRBuilder<> IRB(&F->getEntryBlock().front());
1002   return ArgTLSPtr = IRB.CreateCall(DFS.GetArgTLSTy, DFS.GetArgTLS, {});
1003 }
1004
1005 Value *DFSanFunction::getRetvalTLS() {
1006   if (RetvalTLSPtr)
1007     return RetvalTLSPtr;
1008   if (DFS.RetvalTLS)
1009     return RetvalTLSPtr = DFS.RetvalTLS;
1010
1011   IRBuilder<> IRB(&F->getEntryBlock().front());
1012   return RetvalTLSPtr =
1013              IRB.CreateCall(DFS.GetRetvalTLSTy, DFS.GetRetvalTLS, {});
1014 }
1015
1016 Value *DFSanFunction::getArgTLS(unsigned Idx, Instruction *Pos) {
1017   IRBuilder<> IRB(Pos);
1018   return IRB.CreateConstGEP2_64(ArrayType::get(DFS.ShadowTy, 64),
1019                                 getArgTLSPtr(), 0, Idx);
1020 }
1021
1022 Value *DFSanFunction::getShadow(Value *V) {
1023   if (!isa<Argument>(V) && !isa<Instruction>(V))
1024     return DFS.ZeroShadow;
1025   Value *&Shadow = ValShadowMap[V];
1026   if (!Shadow) {
1027     if (Argument *A = dyn_cast<Argument>(V)) {
1028       if (IsNativeABI)
1029         return DFS.ZeroShadow;
1030       switch (IA) {
1031       case DataFlowSanitizer::IA_TLS: {
1032         Value *ArgTLSPtr = getArgTLSPtr();
1033         Instruction *ArgTLSPos =
1034             DFS.ArgTLS ? &*F->getEntryBlock().begin()
1035                        : cast<Instruction>(ArgTLSPtr)->getNextNode();
1036         IRBuilder<> IRB(ArgTLSPos);
1037         Shadow =
1038             IRB.CreateLoad(DFS.ShadowTy, getArgTLS(A->getArgNo(), ArgTLSPos));
1039         break;
1040       }
1041       case DataFlowSanitizer::IA_Args: {
1042         unsigned ArgIdx = A->getArgNo() + F->arg_size() / 2;
1043         Function::arg_iterator i = F->arg_begin();
1044         while (ArgIdx--)
1045           ++i;
1046         Shadow = &*i;
1047         assert(Shadow->getType() == DFS.ShadowTy);
1048         break;
1049       }
1050       }
1051       NonZeroChecks.push_back(Shadow);
1052     } else {
1053       Shadow = DFS.ZeroShadow;
1054     }
1055   }
1056   return Shadow;
1057 }
1058
1059 void DFSanFunction::setShadow(Instruction *I, Value *Shadow) {
1060   assert(!ValShadowMap.count(I));
1061   assert(Shadow->getType() == DFS.ShadowTy);
1062   ValShadowMap[I] = Shadow;
1063 }
1064
1065 Value *DataFlowSanitizer::getShadowAddress(Value *Addr, Instruction *Pos) {
1066   assert(Addr != RetvalTLS && "Reinstrumenting?");
1067   IRBuilder<> IRB(Pos);
1068   Value *ShadowPtrMaskValue;
1069   if (DFSanRuntimeShadowMask)
1070     ShadowPtrMaskValue = IRB.CreateLoad(IntptrTy, ExternalShadowMask);
1071   else
1072     ShadowPtrMaskValue = ShadowPtrMask;
1073   return IRB.CreateIntToPtr(
1074       IRB.CreateMul(
1075           IRB.CreateAnd(IRB.CreatePtrToInt(Addr, IntptrTy),
1076                         IRB.CreatePtrToInt(ShadowPtrMaskValue, IntptrTy)),
1077           ShadowPtrMul),
1078       ShadowPtrTy);
1079 }
1080
1081 // Generates IR to compute the union of the two given shadows, inserting it
1082 // before Pos.  Returns the computed union Value.
1083 Value *DFSanFunction::combineShadows(Value *V1, Value *V2, Instruction *Pos) {
1084   if (V1 == DFS.ZeroShadow)
1085     return V2;
1086   if (V2 == DFS.ZeroShadow)
1087     return V1;
1088   if (V1 == V2)
1089     return V1;
1090
1091   auto V1Elems = ShadowElements.find(V1);
1092   auto V2Elems = ShadowElements.find(V2);
1093   if (V1Elems != ShadowElements.end() && V2Elems != ShadowElements.end()) {
1094     if (std::includes(V1Elems->second.begin(), V1Elems->second.end(),
1095                       V2Elems->second.begin(), V2Elems->second.end())) {
1096       return V1;
1097     } else if (std::includes(V2Elems->second.begin(), V2Elems->second.end(),
1098                              V1Elems->second.begin(), V1Elems->second.end())) {
1099       return V2;
1100     }
1101   } else if (V1Elems != ShadowElements.end()) {
1102     if (V1Elems->second.count(V2))
1103       return V1;
1104   } else if (V2Elems != ShadowElements.end()) {
1105     if (V2Elems->second.count(V1))
1106       return V2;
1107   }
1108
1109   auto Key = std::make_pair(V1, V2);
1110   if (V1 > V2)
1111     std::swap(Key.first, Key.second);
1112   CachedCombinedShadow &CCS = CachedCombinedShadows[Key];
1113   if (CCS.Block && DT.dominates(CCS.Block, Pos->getParent()))
1114     return CCS.Shadow;
1115
1116   IRBuilder<> IRB(Pos);
1117   if (AvoidNewBlocks) {
1118     CallInst *Call = IRB.CreateCall(DFS.DFSanCheckedUnionFn, {V1, V2});
1119     Call->addAttribute(AttributeList::ReturnIndex, Attribute::ZExt);
1120     Call->addParamAttr(0, Attribute::ZExt);
1121     Call->addParamAttr(1, Attribute::ZExt);
1122
1123     CCS.Block = Pos->getParent();
1124     CCS.Shadow = Call;
1125   } else {
1126     BasicBlock *Head = Pos->getParent();
1127     Value *Ne = IRB.CreateICmpNE(V1, V2);
1128     BranchInst *BI = cast<BranchInst>(SplitBlockAndInsertIfThen(
1129         Ne, Pos, /*Unreachable=*/false, DFS.ColdCallWeights, &DT));
1130     IRBuilder<> ThenIRB(BI);
1131     CallInst *Call = ThenIRB.CreateCall(DFS.DFSanUnionFn, {V1, V2});
1132     Call->addAttribute(AttributeList::ReturnIndex, Attribute::ZExt);
1133     Call->addParamAttr(0, Attribute::ZExt);
1134     Call->addParamAttr(1, Attribute::ZExt);
1135
1136     BasicBlock *Tail = BI->getSuccessor(0);
1137     PHINode *Phi = PHINode::Create(DFS.ShadowTy, 2, "", &Tail->front());
1138     Phi->addIncoming(Call, Call->getParent());
1139     Phi->addIncoming(V1, Head);
1140
1141     CCS.Block = Tail;
1142     CCS.Shadow = Phi;
1143   }
1144
1145   std::set<Value *> UnionElems;
1146   if (V1Elems != ShadowElements.end()) {
1147     UnionElems = V1Elems->second;
1148   } else {
1149     UnionElems.insert(V1);
1150   }
1151   if (V2Elems != ShadowElements.end()) {
1152     UnionElems.insert(V2Elems->second.begin(), V2Elems->second.end());
1153   } else {
1154     UnionElems.insert(V2);
1155   }
1156   ShadowElements[CCS.Shadow] = std::move(UnionElems);
1157
1158   return CCS.Shadow;
1159 }
1160
1161 // A convenience function which folds the shadows of each of the operands
1162 // of the provided instruction Inst, inserting the IR before Inst.  Returns
1163 // the computed union Value.
1164 Value *DFSanFunction::combineOperandShadows(Instruction *Inst) {
1165   if (Inst->getNumOperands() == 0)
1166     return DFS.ZeroShadow;
1167
1168   Value *Shadow = getShadow(Inst->getOperand(0));
1169   for (unsigned i = 1, n = Inst->getNumOperands(); i != n; ++i) {
1170     Shadow = combineShadows(Shadow, getShadow(Inst->getOperand(i)), Inst);
1171   }
1172   return Shadow;
1173 }
1174
1175 void DFSanVisitor::visitOperandShadowInst(Instruction &I) {
1176   Value *CombinedShadow = DFSF.combineOperandShadows(&I);
1177   DFSF.setShadow(&I, CombinedShadow);
1178 }
1179
1180 // Generates IR to load shadow corresponding to bytes [Addr, Addr+Size), where
1181 // Addr has alignment Align, and take the union of each of those shadows.
1182 Value *DFSanFunction::loadShadow(Value *Addr, uint64_t Size, uint64_t Align,
1183                                  Instruction *Pos) {
1184   if (AllocaInst *AI = dyn_cast<AllocaInst>(Addr)) {
1185     const auto i = AllocaShadowMap.find(AI);
1186     if (i != AllocaShadowMap.end()) {
1187       IRBuilder<> IRB(Pos);
1188       return IRB.CreateLoad(DFS.ShadowTy, i->second);
1189     }
1190   }
1191
1192   uint64_t ShadowAlign = Align * DFS.ShadowWidth / 8;
1193   SmallVector<Value *, 2> Objs;
1194   GetUnderlyingObjects(Addr, Objs, Pos->getModule()->getDataLayout());
1195   bool AllConstants = true;
1196   for (Value *Obj : Objs) {
1197     if (isa<Function>(Obj) || isa<BlockAddress>(Obj))
1198       continue;
1199     if (isa<GlobalVariable>(Obj) && cast<GlobalVariable>(Obj)->isConstant())
1200       continue;
1201
1202     AllConstants = false;
1203     break;
1204   }
1205   if (AllConstants)
1206     return DFS.ZeroShadow;
1207
1208   Value *ShadowAddr = DFS.getShadowAddress(Addr, Pos);
1209   switch (Size) {
1210   case 0:
1211     return DFS.ZeroShadow;
1212   case 1: {
1213     LoadInst *LI = new LoadInst(DFS.ShadowTy, ShadowAddr, "", Pos);
1214     LI->setAlignment(ShadowAlign);
1215     return LI;
1216   }
1217   case 2: {
1218     IRBuilder<> IRB(Pos);
1219     Value *ShadowAddr1 = IRB.CreateGEP(DFS.ShadowTy, ShadowAddr,
1220                                        ConstantInt::get(DFS.IntptrTy, 1));
1221     return combineShadows(
1222         IRB.CreateAlignedLoad(DFS.ShadowTy, ShadowAddr, ShadowAlign),
1223         IRB.CreateAlignedLoad(DFS.ShadowTy, ShadowAddr1, ShadowAlign), Pos);
1224   }
1225   }
1226   if (!AvoidNewBlocks && Size % (64 / DFS.ShadowWidth) == 0) {
1227     // Fast path for the common case where each byte has identical shadow: load
1228     // shadow 64 bits at a time, fall out to a __dfsan_union_load call if any
1229     // shadow is non-equal.
1230     BasicBlock *FallbackBB = BasicBlock::Create(*DFS.Ctx, "", F);
1231     IRBuilder<> FallbackIRB(FallbackBB);
1232     CallInst *FallbackCall = FallbackIRB.CreateCall(
1233         DFS.DFSanUnionLoadFn,
1234         {ShadowAddr, ConstantInt::get(DFS.IntptrTy, Size)});
1235     FallbackCall->addAttribute(AttributeList::ReturnIndex, Attribute::ZExt);
1236
1237     // Compare each of the shadows stored in the loaded 64 bits to each other,
1238     // by computing (WideShadow rotl ShadowWidth) == WideShadow.
1239     IRBuilder<> IRB(Pos);
1240     Value *WideAddr =
1241         IRB.CreateBitCast(ShadowAddr, Type::getInt64PtrTy(*DFS.Ctx));
1242     Value *WideShadow =
1243         IRB.CreateAlignedLoad(IRB.getInt64Ty(), WideAddr, ShadowAlign);
1244     Value *TruncShadow = IRB.CreateTrunc(WideShadow, DFS.ShadowTy);
1245     Value *ShlShadow = IRB.CreateShl(WideShadow, DFS.ShadowWidth);
1246     Value *ShrShadow = IRB.CreateLShr(WideShadow, 64 - DFS.ShadowWidth);
1247     Value *RotShadow = IRB.CreateOr(ShlShadow, ShrShadow);
1248     Value *ShadowsEq = IRB.CreateICmpEQ(WideShadow, RotShadow);
1249
1250     BasicBlock *Head = Pos->getParent();
1251     BasicBlock *Tail = Head->splitBasicBlock(Pos->getIterator());
1252
1253     if (DomTreeNode *OldNode = DT.getNode(Head)) {
1254       std::vector<DomTreeNode *> Children(OldNode->begin(), OldNode->end());
1255
1256       DomTreeNode *NewNode = DT.addNewBlock(Tail, Head);
1257       for (auto Child : Children)
1258         DT.changeImmediateDominator(Child, NewNode);
1259     }
1260
1261     // In the following code LastBr will refer to the previous basic block's
1262     // conditional branch instruction, whose true successor is fixed up to point
1263     // to the next block during the loop below or to the tail after the final
1264     // iteration.
1265     BranchInst *LastBr = BranchInst::Create(FallbackBB, FallbackBB, ShadowsEq);
1266     ReplaceInstWithInst(Head->getTerminator(), LastBr);
1267     DT.addNewBlock(FallbackBB, Head);
1268
1269     for (uint64_t Ofs = 64 / DFS.ShadowWidth; Ofs != Size;
1270          Ofs += 64 / DFS.ShadowWidth) {
1271       BasicBlock *NextBB = BasicBlock::Create(*DFS.Ctx, "", F);
1272       DT.addNewBlock(NextBB, LastBr->getParent());
1273       IRBuilder<> NextIRB(NextBB);
1274       WideAddr = NextIRB.CreateGEP(Type::getInt64Ty(*DFS.Ctx), WideAddr,
1275                                    ConstantInt::get(DFS.IntptrTy, 1));
1276       Value *NextWideShadow = NextIRB.CreateAlignedLoad(NextIRB.getInt64Ty(),
1277                                                         WideAddr, ShadowAlign);
1278       ShadowsEq = NextIRB.CreateICmpEQ(WideShadow, NextWideShadow);
1279       LastBr->setSuccessor(0, NextBB);
1280       LastBr = NextIRB.CreateCondBr(ShadowsEq, FallbackBB, FallbackBB);
1281     }
1282
1283     LastBr->setSuccessor(0, Tail);
1284     FallbackIRB.CreateBr(Tail);
1285     PHINode *Shadow = PHINode::Create(DFS.ShadowTy, 2, "", &Tail->front());
1286     Shadow->addIncoming(FallbackCall, FallbackBB);
1287     Shadow->addIncoming(TruncShadow, LastBr->getParent());
1288     return Shadow;
1289   }
1290
1291   IRBuilder<> IRB(Pos);
1292   CallInst *FallbackCall = IRB.CreateCall(
1293       DFS.DFSanUnionLoadFn, {ShadowAddr, ConstantInt::get(DFS.IntptrTy, Size)});
1294   FallbackCall->addAttribute(AttributeList::ReturnIndex, Attribute::ZExt);
1295   return FallbackCall;
1296 }
1297
1298 void DFSanVisitor::visitLoadInst(LoadInst &LI) {
1299   auto &DL = LI.getModule()->getDataLayout();
1300   uint64_t Size = DL.getTypeStoreSize(LI.getType());
1301   if (Size == 0) {
1302     DFSF.setShadow(&LI, DFSF.DFS.ZeroShadow);
1303     return;
1304   }
1305
1306   uint64_t Align;
1307   if (ClPreserveAlignment) {
1308     Align = LI.getAlignment();
1309     if (Align == 0)
1310       Align = DL.getABITypeAlignment(LI.getType());
1311   } else {
1312     Align = 1;
1313   }
1314   IRBuilder<> IRB(&LI);
1315   Value *Shadow = DFSF.loadShadow(LI.getPointerOperand(), Size, Align, &LI);
1316   if (ClCombinePointerLabelsOnLoad) {
1317     Value *PtrShadow = DFSF.getShadow(LI.getPointerOperand());
1318     Shadow = DFSF.combineShadows(Shadow, PtrShadow, &LI);
1319   }
1320   if (Shadow != DFSF.DFS.ZeroShadow)
1321     DFSF.NonZeroChecks.push_back(Shadow);
1322
1323   DFSF.setShadow(&LI, Shadow);
1324 }
1325
1326 void DFSanFunction::storeShadow(Value *Addr, uint64_t Size, uint64_t Align,
1327                                 Value *Shadow, Instruction *Pos) {
1328   if (AllocaInst *AI = dyn_cast<AllocaInst>(Addr)) {
1329     const auto i = AllocaShadowMap.find(AI);
1330     if (i != AllocaShadowMap.end()) {
1331       IRBuilder<> IRB(Pos);
1332       IRB.CreateStore(Shadow, i->second);
1333       return;
1334     }
1335   }
1336
1337   uint64_t ShadowAlign = Align * DFS.ShadowWidth / 8;
1338   IRBuilder<> IRB(Pos);
1339   Value *ShadowAddr = DFS.getShadowAddress(Addr, Pos);
1340   if (Shadow == DFS.ZeroShadow) {
1341     IntegerType *ShadowTy = IntegerType::get(*DFS.Ctx, Size * DFS.ShadowWidth);
1342     Value *ExtZeroShadow = ConstantInt::get(ShadowTy, 0);
1343     Value *ExtShadowAddr =
1344         IRB.CreateBitCast(ShadowAddr, PointerType::getUnqual(ShadowTy));
1345     IRB.CreateAlignedStore(ExtZeroShadow, ExtShadowAddr, ShadowAlign);
1346     return;
1347   }
1348
1349   const unsigned ShadowVecSize = 128 / DFS.ShadowWidth;
1350   uint64_t Offset = 0;
1351   if (Size >= ShadowVecSize) {
1352     VectorType *ShadowVecTy = VectorType::get(DFS.ShadowTy, ShadowVecSize);
1353     Value *ShadowVec = UndefValue::get(ShadowVecTy);
1354     for (unsigned i = 0; i != ShadowVecSize; ++i) {
1355       ShadowVec = IRB.CreateInsertElement(
1356           ShadowVec, Shadow, ConstantInt::get(Type::getInt32Ty(*DFS.Ctx), i));
1357     }
1358     Value *ShadowVecAddr =
1359         IRB.CreateBitCast(ShadowAddr, PointerType::getUnqual(ShadowVecTy));
1360     do {
1361       Value *CurShadowVecAddr =
1362           IRB.CreateConstGEP1_32(ShadowVecTy, ShadowVecAddr, Offset);
1363       IRB.CreateAlignedStore(ShadowVec, CurShadowVecAddr, ShadowAlign);
1364       Size -= ShadowVecSize;
1365       ++Offset;
1366     } while (Size >= ShadowVecSize);
1367     Offset *= ShadowVecSize;
1368   }
1369   while (Size > 0) {
1370     Value *CurShadowAddr =
1371         IRB.CreateConstGEP1_32(DFS.ShadowTy, ShadowAddr, Offset);
1372     IRB.CreateAlignedStore(Shadow, CurShadowAddr, ShadowAlign);
1373     --Size;
1374     ++Offset;
1375   }
1376 }
1377
1378 void DFSanVisitor::visitStoreInst(StoreInst &SI) {
1379   auto &DL = SI.getModule()->getDataLayout();
1380   uint64_t Size = DL.getTypeStoreSize(SI.getValueOperand()->getType());
1381   if (Size == 0)
1382     return;
1383
1384   uint64_t Align;
1385   if (ClPreserveAlignment) {
1386     Align = SI.getAlignment();
1387     if (Align == 0)
1388       Align = DL.getABITypeAlignment(SI.getValueOperand()->getType());
1389   } else {
1390     Align = 1;
1391   }
1392
1393   Value* Shadow = DFSF.getShadow(SI.getValueOperand());
1394   if (ClCombinePointerLabelsOnStore) {
1395     Value *PtrShadow = DFSF.getShadow(SI.getPointerOperand());
1396     Shadow = DFSF.combineShadows(Shadow, PtrShadow, &SI);
1397   }
1398   DFSF.storeShadow(SI.getPointerOperand(), Size, Align, Shadow, &SI);
1399 }
1400
1401 void DFSanVisitor::visitBinaryOperator(BinaryOperator &BO) {
1402   visitOperandShadowInst(BO);
1403 }
1404
1405 void DFSanVisitor::visitCastInst(CastInst &CI) { visitOperandShadowInst(CI); }
1406
1407 void DFSanVisitor::visitCmpInst(CmpInst &CI) { visitOperandShadowInst(CI); }
1408
1409 void DFSanVisitor::visitGetElementPtrInst(GetElementPtrInst &GEPI) {
1410   visitOperandShadowInst(GEPI);
1411 }
1412
1413 void DFSanVisitor::visitExtractElementInst(ExtractElementInst &I) {
1414   visitOperandShadowInst(I);
1415 }
1416
1417 void DFSanVisitor::visitInsertElementInst(InsertElementInst &I) {
1418   visitOperandShadowInst(I);
1419 }
1420
1421 void DFSanVisitor::visitShuffleVectorInst(ShuffleVectorInst &I) {
1422   visitOperandShadowInst(I);
1423 }
1424
1425 void DFSanVisitor::visitExtractValueInst(ExtractValueInst &I) {
1426   visitOperandShadowInst(I);
1427 }
1428
1429 void DFSanVisitor::visitInsertValueInst(InsertValueInst &I) {
1430   visitOperandShadowInst(I);
1431 }
1432
1433 void DFSanVisitor::visitAllocaInst(AllocaInst &I) {
1434   bool AllLoadsStores = true;
1435   for (User *U : I.users()) {
1436     if (isa<LoadInst>(U))
1437       continue;
1438
1439     if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
1440       if (SI->getPointerOperand() == &I)
1441         continue;
1442     }
1443
1444     AllLoadsStores = false;
1445     break;
1446   }
1447   if (AllLoadsStores) {
1448     IRBuilder<> IRB(&I);
1449     DFSF.AllocaShadowMap[&I] = IRB.CreateAlloca(DFSF.DFS.ShadowTy);
1450   }
1451   DFSF.setShadow(&I, DFSF.DFS.ZeroShadow);
1452 }
1453
1454 void DFSanVisitor::visitSelectInst(SelectInst &I) {
1455   Value *CondShadow = DFSF.getShadow(I.getCondition());
1456   Value *TrueShadow = DFSF.getShadow(I.getTrueValue());
1457   Value *FalseShadow = DFSF.getShadow(I.getFalseValue());
1458
1459   if (isa<VectorType>(I.getCondition()->getType())) {
1460     DFSF.setShadow(
1461         &I,
1462         DFSF.combineShadows(
1463             CondShadow, DFSF.combineShadows(TrueShadow, FalseShadow, &I), &I));
1464   } else {
1465     Value *ShadowSel;
1466     if (TrueShadow == FalseShadow) {
1467       ShadowSel = TrueShadow;
1468     } else {
1469       ShadowSel =
1470           SelectInst::Create(I.getCondition(), TrueShadow, FalseShadow, "", &I);
1471     }
1472     DFSF.setShadow(&I, DFSF.combineShadows(CondShadow, ShadowSel, &I));
1473   }
1474 }
1475
1476 void DFSanVisitor::visitMemSetInst(MemSetInst &I) {
1477   IRBuilder<> IRB(&I);
1478   Value *ValShadow = DFSF.getShadow(I.getValue());
1479   IRB.CreateCall(DFSF.DFS.DFSanSetLabelFn,
1480                  {ValShadow, IRB.CreateBitCast(I.getDest(), Type::getInt8PtrTy(
1481                                                                 *DFSF.DFS.Ctx)),
1482                   IRB.CreateZExtOrTrunc(I.getLength(), DFSF.DFS.IntptrTy)});
1483 }
1484
1485 void DFSanVisitor::visitMemTransferInst(MemTransferInst &I) {
1486   IRBuilder<> IRB(&I);
1487   Value *DestShadow = DFSF.DFS.getShadowAddress(I.getDest(), &I);
1488   Value *SrcShadow = DFSF.DFS.getShadowAddress(I.getSource(), &I);
1489   Value *LenShadow = IRB.CreateMul(
1490       I.getLength(),
1491       ConstantInt::get(I.getLength()->getType(), DFSF.DFS.ShadowWidth / 8));
1492   Type *Int8Ptr = Type::getInt8PtrTy(*DFSF.DFS.Ctx);
1493   DestShadow = IRB.CreateBitCast(DestShadow, Int8Ptr);
1494   SrcShadow = IRB.CreateBitCast(SrcShadow, Int8Ptr);
1495   auto *MTI = cast<MemTransferInst>(
1496       IRB.CreateCall(I.getFunctionType(), I.getCalledValue(),
1497                      {DestShadow, SrcShadow, LenShadow, I.getVolatileCst()}));
1498   if (ClPreserveAlignment) {
1499     MTI->setDestAlignment(I.getDestAlignment() * (DFSF.DFS.ShadowWidth / 8));
1500     MTI->setSourceAlignment(I.getSourceAlignment() * (DFSF.DFS.ShadowWidth / 8));
1501   } else {
1502     MTI->setDestAlignment(DFSF.DFS.ShadowWidth / 8);
1503     MTI->setSourceAlignment(DFSF.DFS.ShadowWidth / 8);
1504   }
1505 }
1506
1507 void DFSanVisitor::visitReturnInst(ReturnInst &RI) {
1508   if (!DFSF.IsNativeABI && RI.getReturnValue()) {
1509     switch (DFSF.IA) {
1510     case DataFlowSanitizer::IA_TLS: {
1511       Value *S = DFSF.getShadow(RI.getReturnValue());
1512       IRBuilder<> IRB(&RI);
1513       IRB.CreateStore(S, DFSF.getRetvalTLS());
1514       break;
1515     }
1516     case DataFlowSanitizer::IA_Args: {
1517       IRBuilder<> IRB(&RI);
1518       Type *RT = DFSF.F->getFunctionType()->getReturnType();
1519       Value *InsVal =
1520           IRB.CreateInsertValue(UndefValue::get(RT), RI.getReturnValue(), 0);
1521       Value *InsShadow =
1522           IRB.CreateInsertValue(InsVal, DFSF.getShadow(RI.getReturnValue()), 1);
1523       RI.setOperand(0, InsShadow);
1524       break;
1525     }
1526     }
1527   }
1528 }
1529
1530 void DFSanVisitor::visitCallSite(CallSite CS) {
1531   Function *F = CS.getCalledFunction();
1532   if ((F && F->isIntrinsic()) || isa<InlineAsm>(CS.getCalledValue())) {
1533     visitOperandShadowInst(*CS.getInstruction());
1534     return;
1535   }
1536
1537   // Calls to this function are synthesized in wrappers, and we shouldn't
1538   // instrument them.
1539   if (F == DFSF.DFS.DFSanVarargWrapperFn.getCallee()->stripPointerCasts())
1540     return;
1541
1542   IRBuilder<> IRB(CS.getInstruction());
1543
1544   DenseMap<Value *, Function *>::iterator i =
1545       DFSF.DFS.UnwrappedFnMap.find(CS.getCalledValue());
1546   if (i != DFSF.DFS.UnwrappedFnMap.end()) {
1547     Function *F = i->second;
1548     switch (DFSF.DFS.getWrapperKind(F)) {
1549     case DataFlowSanitizer::WK_Warning:
1550       CS.setCalledFunction(F);
1551       IRB.CreateCall(DFSF.DFS.DFSanUnimplementedFn,
1552                      IRB.CreateGlobalStringPtr(F->getName()));
1553       DFSF.setShadow(CS.getInstruction(), DFSF.DFS.ZeroShadow);
1554       return;
1555     case DataFlowSanitizer::WK_Discard:
1556       CS.setCalledFunction(F);
1557       DFSF.setShadow(CS.getInstruction(), DFSF.DFS.ZeroShadow);
1558       return;
1559     case DataFlowSanitizer::WK_Functional:
1560       CS.setCalledFunction(F);
1561       visitOperandShadowInst(*CS.getInstruction());
1562       return;
1563     case DataFlowSanitizer::WK_Custom:
1564       // Don't try to handle invokes of custom functions, it's too complicated.
1565       // Instead, invoke the dfsw$ wrapper, which will in turn call the __dfsw_
1566       // wrapper.
1567       if (CallInst *CI = dyn_cast<CallInst>(CS.getInstruction())) {
1568         FunctionType *FT = F->getFunctionType();
1569         TransformedFunction CustomFn = DFSF.DFS.getCustomFunctionType(FT);
1570         std::string CustomFName = "__dfsw_";
1571         CustomFName += F->getName();
1572         FunctionCallee CustomF = DFSF.DFS.Mod->getOrInsertFunction(
1573             CustomFName, CustomFn.TransformedType);
1574         if (Function *CustomFn = dyn_cast<Function>(CustomF.getCallee())) {
1575           CustomFn->copyAttributesFrom(F);
1576
1577           // Custom functions returning non-void will write to the return label.
1578           if (!FT->getReturnType()->isVoidTy()) {
1579             CustomFn->removeAttributes(AttributeList::FunctionIndex,
1580                                        DFSF.DFS.ReadOnlyNoneAttrs);
1581           }
1582         }
1583
1584         std::vector<Value *> Args;
1585
1586         CallSite::arg_iterator i = CS.arg_begin();
1587         for (unsigned n = FT->getNumParams(); n != 0; ++i, --n) {
1588           Type *T = (*i)->getType();
1589           FunctionType *ParamFT;
1590           if (isa<PointerType>(T) &&
1591               (ParamFT = dyn_cast<FunctionType>(
1592                    cast<PointerType>(T)->getElementType()))) {
1593             std::string TName = "dfst";
1594             TName += utostr(FT->getNumParams() - n);
1595             TName += "$";
1596             TName += F->getName();
1597             Constant *T = DFSF.DFS.getOrBuildTrampolineFunction(ParamFT, TName);
1598             Args.push_back(T);
1599             Args.push_back(
1600                 IRB.CreateBitCast(*i, Type::getInt8PtrTy(*DFSF.DFS.Ctx)));
1601           } else {
1602             Args.push_back(*i);
1603           }
1604         }
1605
1606         i = CS.arg_begin();
1607         const unsigned ShadowArgStart = Args.size();
1608         for (unsigned n = FT->getNumParams(); n != 0; ++i, --n)
1609           Args.push_back(DFSF.getShadow(*i));
1610
1611         if (FT->isVarArg()) {
1612           auto *LabelVATy = ArrayType::get(DFSF.DFS.ShadowTy,
1613                                            CS.arg_size() - FT->getNumParams());
1614           auto *LabelVAAlloca = new AllocaInst(
1615               LabelVATy, getDataLayout().getAllocaAddrSpace(),
1616               "labelva", &DFSF.F->getEntryBlock().front());
1617
1618           for (unsigned n = 0; i != CS.arg_end(); ++i, ++n) {
1619             auto LabelVAPtr = IRB.CreateStructGEP(LabelVATy, LabelVAAlloca, n);
1620             IRB.CreateStore(DFSF.getShadow(*i), LabelVAPtr);
1621           }
1622
1623           Args.push_back(IRB.CreateStructGEP(LabelVATy, LabelVAAlloca, 0));
1624         }
1625
1626         if (!FT->getReturnType()->isVoidTy()) {
1627           if (!DFSF.LabelReturnAlloca) {
1628             DFSF.LabelReturnAlloca =
1629               new AllocaInst(DFSF.DFS.ShadowTy,
1630                              getDataLayout().getAllocaAddrSpace(),
1631                              "labelreturn", &DFSF.F->getEntryBlock().front());
1632           }
1633           Args.push_back(DFSF.LabelReturnAlloca);
1634         }
1635
1636         for (i = CS.arg_begin() + FT->getNumParams(); i != CS.arg_end(); ++i)
1637           Args.push_back(*i);
1638
1639         CallInst *CustomCI = IRB.CreateCall(CustomF, Args);
1640         CustomCI->setCallingConv(CI->getCallingConv());
1641         CustomCI->setAttributes(TransformFunctionAttributes(CustomFn,
1642             CI->getContext(), CI->getAttributes()));
1643
1644         // Update the parameter attributes of the custom call instruction to
1645         // zero extend the shadow parameters. This is required for targets
1646         // which consider ShadowTy an illegal type.
1647         for (unsigned n = 0; n < FT->getNumParams(); n++) {
1648           const unsigned ArgNo = ShadowArgStart + n;
1649           if (CustomCI->getArgOperand(ArgNo)->getType() == DFSF.DFS.ShadowTy)
1650             CustomCI->addParamAttr(ArgNo, Attribute::ZExt);
1651         }
1652
1653         if (!FT->getReturnType()->isVoidTy()) {
1654           LoadInst *LabelLoad =
1655               IRB.CreateLoad(DFSF.DFS.ShadowTy, DFSF.LabelReturnAlloca);
1656           DFSF.setShadow(CustomCI, LabelLoad);
1657         }
1658
1659         CI->replaceAllUsesWith(CustomCI);
1660         CI->eraseFromParent();
1661         return;
1662       }
1663       break;
1664     }
1665   }
1666
1667   FunctionType *FT = cast<FunctionType>(
1668       CS.getCalledValue()->getType()->getPointerElementType());
1669   if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_TLS) {
1670     for (unsigned i = 0, n = FT->getNumParams(); i != n; ++i) {
1671       IRB.CreateStore(DFSF.getShadow(CS.getArgument(i)),
1672                       DFSF.getArgTLS(i, CS.getInstruction()));
1673     }
1674   }
1675
1676   Instruction *Next = nullptr;
1677   if (!CS.getType()->isVoidTy()) {
1678     if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
1679       if (II->getNormalDest()->getSinglePredecessor()) {
1680         Next = &II->getNormalDest()->front();
1681       } else {
1682         BasicBlock *NewBB =
1683             SplitEdge(II->getParent(), II->getNormalDest(), &DFSF.DT);
1684         Next = &NewBB->front();
1685       }
1686     } else {
1687       assert(CS->getIterator() != CS->getParent()->end());
1688       Next = CS->getNextNode();
1689     }
1690
1691     if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_TLS) {
1692       IRBuilder<> NextIRB(Next);
1693       LoadInst *LI = NextIRB.CreateLoad(DFSF.DFS.ShadowTy, DFSF.getRetvalTLS());
1694       DFSF.SkipInsts.insert(LI);
1695       DFSF.setShadow(CS.getInstruction(), LI);
1696       DFSF.NonZeroChecks.push_back(LI);
1697     }
1698   }
1699
1700   // Do all instrumentation for IA_Args down here to defer tampering with the
1701   // CFG in a way that SplitEdge may be able to detect.
1702   if (DFSF.DFS.getInstrumentedABI() == DataFlowSanitizer::IA_Args) {
1703     FunctionType *NewFT = DFSF.DFS.getArgsFunctionType(FT);
1704     Value *Func =
1705         IRB.CreateBitCast(CS.getCalledValue(), PointerType::getUnqual(NewFT));
1706     std::vector<Value *> Args;
1707
1708     CallSite::arg_iterator i = CS.arg_begin(), e = CS.arg_end();
1709     for (unsigned n = FT->getNumParams(); n != 0; ++i, --n)
1710       Args.push_back(*i);
1711
1712     i = CS.arg_begin();
1713     for (unsigned n = FT->getNumParams(); n != 0; ++i, --n)
1714       Args.push_back(DFSF.getShadow(*i));
1715
1716     if (FT->isVarArg()) {
1717       unsigned VarArgSize = CS.arg_size() - FT->getNumParams();
1718       ArrayType *VarArgArrayTy = ArrayType::get(DFSF.DFS.ShadowTy, VarArgSize);
1719       AllocaInst *VarArgShadow =
1720         new AllocaInst(VarArgArrayTy, getDataLayout().getAllocaAddrSpace(),
1721                        "", &DFSF.F->getEntryBlock().front());
1722       Args.push_back(IRB.CreateConstGEP2_32(VarArgArrayTy, VarArgShadow, 0, 0));
1723       for (unsigned n = 0; i != e; ++i, ++n) {
1724         IRB.CreateStore(
1725             DFSF.getShadow(*i),
1726             IRB.CreateConstGEP2_32(VarArgArrayTy, VarArgShadow, 0, n));
1727         Args.push_back(*i);
1728       }
1729     }
1730
1731     CallSite NewCS;
1732     if (InvokeInst *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
1733       NewCS = IRB.CreateInvoke(NewFT, Func, II->getNormalDest(),
1734                                II->getUnwindDest(), Args);
1735     } else {
1736       NewCS = IRB.CreateCall(NewFT, Func, Args);
1737     }
1738     NewCS.setCallingConv(CS.getCallingConv());
1739     NewCS.setAttributes(CS.getAttributes().removeAttributes(
1740         *DFSF.DFS.Ctx, AttributeList::ReturnIndex,
1741         AttributeFuncs::typeIncompatible(NewCS.getInstruction()->getType())));
1742
1743     if (Next) {
1744       ExtractValueInst *ExVal =
1745           ExtractValueInst::Create(NewCS.getInstruction(), 0, "", Next);
1746       DFSF.SkipInsts.insert(ExVal);
1747       ExtractValueInst *ExShadow =
1748           ExtractValueInst::Create(NewCS.getInstruction(), 1, "", Next);
1749       DFSF.SkipInsts.insert(ExShadow);
1750       DFSF.setShadow(ExVal, ExShadow);
1751       DFSF.NonZeroChecks.push_back(ExShadow);
1752
1753       CS.getInstruction()->replaceAllUsesWith(ExVal);
1754     }
1755
1756     CS.getInstruction()->eraseFromParent();
1757   }
1758 }
1759
1760 void DFSanVisitor::visitPHINode(PHINode &PN) {
1761   PHINode *ShadowPN =
1762       PHINode::Create(DFSF.DFS.ShadowTy, PN.getNumIncomingValues(), "", &PN);
1763
1764   // Give the shadow phi node valid predecessors to fool SplitEdge into working.
1765   Value *UndefShadow = UndefValue::get(DFSF.DFS.ShadowTy);
1766   for (PHINode::block_iterator i = PN.block_begin(), e = PN.block_end(); i != e;
1767        ++i) {
1768     ShadowPN->addIncoming(UndefShadow, *i);
1769   }
1770
1771   DFSF.PHIFixups.push_back(std::make_pair(&PN, ShadowPN));
1772   DFSF.setShadow(&PN, ShadowPN);
1773 }