lib/Transforms/Instrumentation/SanitizerCoverage.cpp

   1 //===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===//
   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 // Coverage instrumentation done on LLVM IR level, works with Sanitizers.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/Transforms/Instrumentation/SanitizerCoverage.h"
  14 #include "llvm/ADT/ArrayRef.h"
  15 #include "llvm/ADT/SmallVector.h"
  16 #include "llvm/Analysis/EHPersonalities.h"
  17 #include "llvm/Analysis/PostDominators.h"
  18 #include "llvm/IR/CFG.h"
  19 #include "llvm/IR/CallSite.h"
  20 #include "llvm/IR/Constant.h"
  21 #include "llvm/IR/DataLayout.h"
  22 #include "llvm/IR/DebugInfo.h"
  23 #include "llvm/IR/Dominators.h"
  24 #include "llvm/IR/Function.h"
  25 #include "llvm/IR/GlobalVariable.h"
  26 #include "llvm/IR/IRBuilder.h"
  27 #include "llvm/IR/InlineAsm.h"
  28 #include "llvm/IR/IntrinsicInst.h"
  29 #include "llvm/IR/Intrinsics.h"
  30 #include "llvm/IR/LLVMContext.h"
  31 #include "llvm/IR/MDBuilder.h"
  32 #include "llvm/IR/Mangler.h"
  33 #include "llvm/IR/Module.h"
  34 #include "llvm/IR/Type.h"
  35 #include "llvm/Support/CommandLine.h"
  36 #include "llvm/Support/Debug.h"
  37 #include "llvm/Support/raw_ostream.h"
  38 #include "llvm/Transforms/Instrumentation.h"
  39 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
  40 #include "llvm/Transforms/Utils/ModuleUtils.h"
  41
  42 using namespace llvm;
  43
  44 #define DEBUG_TYPE "sancov"
  45
  46 static const char *const SanCovTracePCIndirName =
  47     "__sanitizer_cov_trace_pc_indir";
  48 static const char *const SanCovTracePCName = "__sanitizer_cov_trace_pc";
  49 static const char *const SanCovTraceCmp1 = "__sanitizer_cov_trace_cmp1";
  50 static const char *const SanCovTraceCmp2 = "__sanitizer_cov_trace_cmp2";
  51 static const char *const SanCovTraceCmp4 = "__sanitizer_cov_trace_cmp4";
  52 static const char *const SanCovTraceCmp8 = "__sanitizer_cov_trace_cmp8";
  53 static const char *const SanCovTraceConstCmp1 =
  54     "__sanitizer_cov_trace_const_cmp1";
  55 static const char *const SanCovTraceConstCmp2 =
  56     "__sanitizer_cov_trace_const_cmp2";
  57 static const char *const SanCovTraceConstCmp4 =
  58     "__sanitizer_cov_trace_const_cmp4";
  59 static const char *const SanCovTraceConstCmp8 =
  60     "__sanitizer_cov_trace_const_cmp8";
  61 static const char *const SanCovTraceDiv4 = "__sanitizer_cov_trace_div4";
  62 static const char *const SanCovTraceDiv8 = "__sanitizer_cov_trace_div8";
  63 static const char *const SanCovTraceGep = "__sanitizer_cov_trace_gep";
  64 static const char *const SanCovTraceSwitchName = "__sanitizer_cov_trace_switch";
  65 static const char *const SanCovModuleCtorTracePcGuardName =
  66     "sancov.module_ctor_trace_pc_guard";
  67 static const char *const SanCovModuleCtor8bitCountersName =
  68     "sancov.module_ctor_8bit_counters";
  69 static const uint64_t SanCtorAndDtorPriority = 2;
  70
  71 static const char *const SanCovTracePCGuardName =
  72     "__sanitizer_cov_trace_pc_guard";
  73 static const char *const SanCovTracePCGuardInitName =
  74     "__sanitizer_cov_trace_pc_guard_init";
  75 static const char *const SanCov8bitCountersInitName =
  76     "__sanitizer_cov_8bit_counters_init";
  77 static const char *const SanCovPCsInitName = "__sanitizer_cov_pcs_init";
  78
  79 static const char *const SanCovGuardsSectionName = "sancov_guards";
  80 static const char *const SanCovCountersSectionName = "sancov_cntrs";
  81 static const char *const SanCovPCsSectionName = "sancov_pcs";
  82
  83 static const char *const SanCovLowestStackName = "__sancov_lowest_stack";
  84
  85 static cl::opt<int> ClCoverageLevel(
  86     "sanitizer-coverage-level",
  87     cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
  88              "3: all blocks and critical edges"),
  89     cl::Hidden, cl::init(0));
  90
  91 static cl::opt<bool> ClTracePC("sanitizer-coverage-trace-pc",
  92                                cl::desc("Experimental pc tracing"), cl::Hidden,
  93                                cl::init(false));
  94
  95 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard",
  96                                     cl::desc("pc tracing with a guard"),
  97                                     cl::Hidden, cl::init(false));
  98
  99 // If true, we create a global variable that contains PCs of all instrumented
 100 // BBs, put this global into a named section, and pass this section's bounds
 101 // to __sanitizer_cov_pcs_init.
 102 // This way the coverage instrumentation does not need to acquire the PCs
 103 // at run-time. Works with trace-pc-guard and inline-8bit-counters.
 104 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table",
 105                                      cl::desc("create a static PC table"),
 106                                      cl::Hidden, cl::init(false));
 107
 108 static cl::opt<bool>
 109     ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters",
 110                          cl::desc("increments 8-bit counter for every edge"),
 111                          cl::Hidden, cl::init(false));
 112
 113 static cl::opt<bool>
 114     ClCMPTracing("sanitizer-coverage-trace-compares",
 115                  cl::desc("Tracing of CMP and similar instructions"),
 116                  cl::Hidden, cl::init(false));
 117
 118 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs",
 119                                   cl::desc("Tracing of DIV instructions"),
 120                                   cl::Hidden, cl::init(false));
 121
 122 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps",
 123                                   cl::desc("Tracing of GEP instructions"),
 124                                   cl::Hidden, cl::init(false));
 125
 126 static cl::opt<bool>
 127     ClPruneBlocks("sanitizer-coverage-prune-blocks",
 128                   cl::desc("Reduce the number of instrumented blocks"),
 129                   cl::Hidden, cl::init(true));
 130
 131 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth",
 132                                   cl::desc("max stack depth tracing"),
 133                                   cl::Hidden, cl::init(false));
 134
 135 namespace {
 136
 137 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
 138   SanitizerCoverageOptions Res;
 139   switch (LegacyCoverageLevel) {
 140   case 0:
 141     Res.CoverageType = SanitizerCoverageOptions::SCK_None;
 142     break;
 143   case 1:
 144     Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
 145     break;
 146   case 2:
 147     Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
 148     break;
 149   case 3:
 150     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
 151     break;
 152   case 4:
 153     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
 154     Res.IndirectCalls = true;
 155     break;
 156   }
 157   return Res;
 158 }
 159
 160 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
 161   // Sets CoverageType and IndirectCalls.
 162   SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
 163   Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
 164   Options.IndirectCalls |= CLOpts.IndirectCalls;
 165   Options.TraceCmp |= ClCMPTracing;
 166   Options.TraceDiv |= ClDIVTracing;
 167   Options.TraceGep |= ClGEPTracing;
 168   Options.TracePC |= ClTracePC;
 169   Options.TracePCGuard |= ClTracePCGuard;
 170   Options.Inline8bitCounters |= ClInline8bitCounters;
 171   Options.PCTable |= ClCreatePCTable;
 172   Options.NoPrune |= !ClPruneBlocks;
 173   Options.StackDepth |= ClStackDepth;
 174   if (!Options.TracePCGuard && !Options.TracePC &&
 175       !Options.Inline8bitCounters && !Options.StackDepth)
 176     Options.TracePCGuard = true; // TracePCGuard is default.
 177   return Options;
 178 }
 179
 180 using DomTreeCallback = function_ref<const DominatorTree *(Function &F)>;
 181 using PostDomTreeCallback =
 182     function_ref<const PostDominatorTree *(Function &F)>;
 183
 184 class ModuleSanitizerCoverage {
 185 public:
 186   ModuleSanitizerCoverage(
 187       const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
 188       : Options(OverrideFromCL(Options)) {}
 189   bool instrumentModule(Module &M, DomTreeCallback DTCallback,
 190                         PostDomTreeCallback PDTCallback);
 191
 192 private:
 193   void instrumentFunction(Function &F, DomTreeCallback DTCallback,
 194                           PostDomTreeCallback PDTCallback);
 195   void InjectCoverageForIndirectCalls(Function &F,
 196                                       ArrayRef<Instruction *> IndirCalls);
 197   void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
 198   void InjectTraceForDiv(Function &F,
 199                          ArrayRef<BinaryOperator *> DivTraceTargets);
 200   void InjectTraceForGep(Function &F,
 201                          ArrayRef<GetElementPtrInst *> GepTraceTargets);
 202   void InjectTraceForSwitch(Function &F,
 203                             ArrayRef<Instruction *> SwitchTraceTargets);
 204   bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
 205                       bool IsLeafFunc = true);
 206   GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
 207                                                     Function &F, Type *Ty,
 208                                                     const char *Section);
 209   GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
 210   void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
 211   void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
 212                              bool IsLeafFunc = true);
 213   Function *CreateInitCallsForSections(Module &M, const char *CtorName,
 214                                        const char *InitFunctionName, Type *Ty,
 215                                        const char *Section);
 216   std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section,
 217                                                 Type *Ty);
 218
 219   void SetNoSanitizeMetadata(Instruction *I) {
 220     I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
 221                    MDNode::get(*C, None));
 222   }
 223
 224   std::string getSectionName(const std::string &Section) const;
 225   std::string getSectionStart(const std::string &Section) const;
 226   std::string getSectionEnd(const std::string &Section) const;
 227   FunctionCallee SanCovTracePCIndir;
 228   FunctionCallee SanCovTracePC, SanCovTracePCGuard;
 229   FunctionCallee SanCovTraceCmpFunction[4];
 230   FunctionCallee SanCovTraceConstCmpFunction[4];
 231   FunctionCallee SanCovTraceDivFunction[2];
 232   FunctionCallee SanCovTraceGepFunction;
 233   FunctionCallee SanCovTraceSwitchFunction;
 234   GlobalVariable *SanCovLowestStack;
 235   InlineAsm *EmptyAsm;
 236   Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy,
 237       *Int16Ty, *Int8Ty, *Int8PtrTy;
 238   Module *CurModule;
 239   std::string CurModuleUniqueId;
 240   Triple TargetTriple;
 241   LLVMContext *C;
 242   const DataLayout *DL;
 243
 244   GlobalVariable *FunctionGuardArray;  // for trace-pc-guard.
 245   GlobalVariable *Function8bitCounterArray;  // for inline-8bit-counters.
 246   GlobalVariable *FunctionPCsArray;  // for pc-table.
 247   SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
 248   SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
 249
 250   SanitizerCoverageOptions Options;
 251 };
 252
 253 class ModuleSanitizerCoverageLegacyPass : public ModulePass {
 254 public:
 255   ModuleSanitizerCoverageLegacyPass(
 256       const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
 257       : ModulePass(ID), Options(Options) {
 258     initializeModuleSanitizerCoverageLegacyPassPass(
 259         *PassRegistry::getPassRegistry());
 260   }
 261   bool runOnModule(Module &M) override {
 262     ModuleSanitizerCoverage ModuleSancov(Options);
 263     auto DTCallback = [this](Function &F) -> const DominatorTree * {
 264       return &this->getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
 265     };
 266     auto PDTCallback = [this](Function &F) -> const PostDominatorTree * {
 267       return &this->getAnalysis<PostDominatorTreeWrapperPass>(F)
 268                   .getPostDomTree();
 269     };
 270     return ModuleSancov.instrumentModule(M, DTCallback, PDTCallback);
 271   }
 272
 273   static char ID; // Pass identification, replacement for typeid
 274   StringRef getPassName() const override { return "ModuleSanitizerCoverage"; }
 275
 276   void getAnalysisUsage(AnalysisUsage &AU) const override {
 277     AU.addRequired<DominatorTreeWrapperPass>();
 278     AU.addRequired<PostDominatorTreeWrapperPass>();
 279   }
 280
 281 private:
 282   SanitizerCoverageOptions Options;
 283 };
 284
 285 } // namespace
 286
 287 PreservedAnalyses ModuleSanitizerCoveragePass::run(Module &M,
 288                                                    ModuleAnalysisManager &MAM) {
 289   ModuleSanitizerCoverage ModuleSancov(Options);
 290   auto &FAM = MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
 291   auto DTCallback = [&FAM](Function &F) -> const DominatorTree * {
 292     return &FAM.getResult<DominatorTreeAnalysis>(F);
 293   };
 294   auto PDTCallback = [&FAM](Function &F) -> const PostDominatorTree * {
 295     return &FAM.getResult<PostDominatorTreeAnalysis>(F);
 296   };
 297   if (ModuleSancov.instrumentModule(M, DTCallback, PDTCallback))
 298     return PreservedAnalyses::none();
 299   return PreservedAnalyses::all();
 300 }
 301
 302 std::pair<Value *, Value *>
 303 ModuleSanitizerCoverage::CreateSecStartEnd(Module &M, const char *Section,
 304                                            Type *Ty) {
 305   GlobalVariable *SecStart =
 306       new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr,
 307                          getSectionStart(Section));
 308   SecStart->setVisibility(GlobalValue::HiddenVisibility);
 309   GlobalVariable *SecEnd =
 310       new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage,
 311                          nullptr, getSectionEnd(Section));
 312   SecEnd->setVisibility(GlobalValue::HiddenVisibility);
 313   IRBuilder<> IRB(M.getContext());
 314   Value *SecEndPtr = IRB.CreatePointerCast(SecEnd, Ty);
 315   if (!TargetTriple.isOSBinFormatCOFF())
 316     return std::make_pair(IRB.CreatePointerCast(SecStart, Ty), SecEndPtr);
 317
 318   // Account for the fact that on windows-msvc __start_* symbols actually
 319   // point to a uint64_t before the start of the array.
 320   auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy);
 321   auto GEP = IRB.CreateGEP(Int8Ty, SecStartI8Ptr,
 322                            ConstantInt::get(IntptrTy, sizeof(uint64_t)));
 323   return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEndPtr);
 324 }
 325
 326 Function *ModuleSanitizerCoverage::CreateInitCallsForSections(
 327     Module &M, const char *CtorName, const char *InitFunctionName, Type *Ty,
 328     const char *Section) {
 329   auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
 330   auto SecStart = SecStartEnd.first;
 331   auto SecEnd = SecStartEnd.second;
 332   Function *CtorFunc;
 333   std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
 334       M, CtorName, InitFunctionName, {Ty, Ty}, {SecStart, SecEnd});
 335   assert(CtorFunc->getName() == CtorName);
 336
 337   if (TargetTriple.supportsCOMDAT()) {
 338     // Use comdat to dedup CtorFunc.
 339     CtorFunc->setComdat(M.getOrInsertComdat(CtorName));
 340     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
 341   } else {
 342     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
 343   }
 344
 345   if (TargetTriple.isOSBinFormatCOFF()) {
 346     // In COFF files, if the contructors are set as COMDAT (they are because
 347     // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
 348     // functions and data) is used, the constructors get stripped. To prevent
 349     // this, give the constructors weak ODR linkage and ensure the linker knows
 350     // to include the sancov constructor. This way the linker can deduplicate
 351     // the constructors but always leave one copy.
 352     CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
 353     appendToUsed(M, CtorFunc);
 354   }
 355   return CtorFunc;
 356 }
 357
 358 bool ModuleSanitizerCoverage::instrumentModule(
 359     Module &M, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
 360   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
 361     return false;
 362   C = &(M.getContext());
 363   DL = &M.getDataLayout();
 364   CurModule = &M;
 365   CurModuleUniqueId = getUniqueModuleId(CurModule);
 366   TargetTriple = Triple(M.getTargetTriple());
 367   FunctionGuardArray = nullptr;
 368   Function8bitCounterArray = nullptr;
 369   FunctionPCsArray = nullptr;
 370   IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
 371   IntptrPtrTy = PointerType::getUnqual(IntptrTy);
 372   Type *VoidTy = Type::getVoidTy(*C);
 373   IRBuilder<> IRB(*C);
 374   Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
 375   Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
 376   Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
 377   Int64Ty = IRB.getInt64Ty();
 378   Int32Ty = IRB.getInt32Ty();
 379   Int16Ty = IRB.getInt16Ty();
 380   Int8Ty = IRB.getInt8Ty();
 381
 382   SanCovTracePCIndir =
 383       M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy);
 384   // Make sure smaller parameters are zero-extended to i64 as required by the
 385   // x86_64 ABI.
 386   AttributeList SanCovTraceCmpZeroExtAL;
 387   if (TargetTriple.getArch() == Triple::x86_64) {
 388     SanCovTraceCmpZeroExtAL =
 389         SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt);
 390     SanCovTraceCmpZeroExtAL =
 391         SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt);
 392   }
 393
 394   SanCovTraceCmpFunction[0] =
 395       M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy,
 396                             IRB.getInt8Ty(), IRB.getInt8Ty());
 397   SanCovTraceCmpFunction[1] =
 398       M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy,
 399                             IRB.getInt16Ty(), IRB.getInt16Ty());
 400   SanCovTraceCmpFunction[2] =
 401       M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy,
 402                             IRB.getInt32Ty(), IRB.getInt32Ty());
 403   SanCovTraceCmpFunction[3] =
 404       M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty);
 405
 406   SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction(
 407       SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty);
 408   SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction(
 409       SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty);
 410   SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction(
 411       SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty);
 412   SanCovTraceConstCmpFunction[3] =
 413       M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty);
 414
 415   {
 416     AttributeList AL;
 417     if (TargetTriple.getArch() == Triple::x86_64)
 418       AL = AL.addParamAttribute(*C, 0, Attribute::ZExt);
 419     SanCovTraceDivFunction[0] =
 420         M.getOrInsertFunction(SanCovTraceDiv4, AL, VoidTy, IRB.getInt32Ty());
 421   }
 422   SanCovTraceDivFunction[1] =
 423       M.getOrInsertFunction(SanCovTraceDiv8, VoidTy, Int64Ty);
 424   SanCovTraceGepFunction =
 425       M.getOrInsertFunction(SanCovTraceGep, VoidTy, IntptrTy);
 426   SanCovTraceSwitchFunction =
 427       M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy);
 428
 429   Constant *SanCovLowestStackConstant =
 430       M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
 431   SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant);
 432   if (!SanCovLowestStack) {
 433     C->emitError(StringRef("'") + SanCovLowestStackName +
 434                  "' should not be declared by the user");
 435     return true;
 436   }
 437   SanCovLowestStack->setThreadLocalMode(
 438       GlobalValue::ThreadLocalMode::InitialExecTLSModel);
 439   if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
 440     SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
 441
 442   // We insert an empty inline asm after cov callbacks to avoid callback merge.
 443   EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
 444                             StringRef(""), StringRef(""),
 445                             /*hasSideEffects=*/true);
 446
 447   SanCovTracePC = M.getOrInsertFunction(SanCovTracePCName, VoidTy);
 448   SanCovTracePCGuard =
 449       M.getOrInsertFunction(SanCovTracePCGuardName, VoidTy, Int32PtrTy);
 450
 451   for (auto &F : M)
 452     instrumentFunction(F, DTCallback, PDTCallback);
 453
 454   Function *Ctor = nullptr;
 455
 456   if (FunctionGuardArray)
 457     Ctor = CreateInitCallsForSections(M, SanCovModuleCtorTracePcGuardName,
 458                                       SanCovTracePCGuardInitName, Int32PtrTy,
 459                                       SanCovGuardsSectionName);
 460   if (Function8bitCounterArray)
 461     Ctor = CreateInitCallsForSections(M, SanCovModuleCtor8bitCountersName,
 462                                       SanCov8bitCountersInitName, Int8PtrTy,
 463                                       SanCovCountersSectionName);
 464   if (Ctor && Options.PCTable) {
 465     auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy);
 466     FunctionCallee InitFunction = declareSanitizerInitFunction(
 467         M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy});
 468     IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
 469     IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
 470   }
 471   // We don't reference these arrays directly in any of our runtime functions,
 472   // so we need to prevent them from being dead stripped.
 473   if (TargetTriple.isOSBinFormatMachO())
 474     appendToUsed(M, GlobalsToAppendToUsed);
 475   appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
 476   return true;
 477 }
 478
 479 // True if block has successors and it dominates all of them.
 480 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
 481   if (succ_begin(BB) == succ_end(BB))
 482     return false;
 483
 484   for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
 485     if (!DT->dominates(BB, SUCC))
 486       return false;
 487   }
 488
 489   return true;
 490 }
 491
 492 // True if block has predecessors and it postdominates all of them.
 493 static bool isFullPostDominator(const BasicBlock *BB,
 494                                 const PostDominatorTree *PDT) {
 495   if (pred_begin(BB) == pred_end(BB))
 496     return false;
 497
 498   for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
 499     if (!PDT->dominates(BB, PRED))
 500       return false;
 501   }
 502
 503   return true;
 504 }
 505
 506 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
 507                                   const DominatorTree *DT,
 508                                   const PostDominatorTree *PDT,
 509                                   const SanitizerCoverageOptions &Options) {
 510   // Don't insert coverage for blocks containing nothing but unreachable: we
 511   // will never call __sanitizer_cov() for them, so counting them in
 512   // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
 513   // percentage. Also, unreachable instructions frequently have no debug
 514   // locations.
 515   if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime()))
 516     return false;
 517
 518   // Don't insert coverage into blocks without a valid insertion point
 519   // (catchswitch blocks).
 520   if (BB->getFirstInsertionPt() == BB->end())
 521     return false;
 522
 523   if (Options.NoPrune || &F.getEntryBlock() == BB)
 524     return true;
 525
 526   if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
 527       &F.getEntryBlock() != BB)
 528     return false;
 529
 530   // Do not instrument full dominators, or full post-dominators with multiple
 531   // predecessors.
 532   return !isFullDominator(BB, DT)
 533     && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
 534 }
 535
 536
 537 // Returns true iff From->To is a backedge.
 538 // A twist here is that we treat From->To as a backedge if
 539 //   * To dominates From or
 540 //   * To->UniqueSuccessor dominates From
 541 static bool IsBackEdge(BasicBlock *From, BasicBlock *To,
 542                        const DominatorTree *DT) {
 543   if (DT->dominates(To, From))
 544     return true;
 545   if (auto Next = To->getUniqueSuccessor())
 546     if (DT->dominates(Next, From))
 547       return true;
 548   return false;
 549 }
 550
 551 // Prunes uninteresting Cmp instrumentation:
 552 //   * CMP instructions that feed into loop backedge branch.
 553 //
 554 // Note that Cmp pruning is controlled by the same flag as the
 555 // BB pruning.
 556 static bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree *DT,
 557                              const SanitizerCoverageOptions &Options) {
 558   if (!Options.NoPrune)
 559     if (CMP->hasOneUse())
 560       if (auto BR = dyn_cast<BranchInst>(CMP->user_back()))
 561         for (BasicBlock *B : BR->successors())
 562           if (IsBackEdge(BR->getParent(), B, DT))
 563             return false;
 564   return true;
 565 }
 566
 567 void ModuleSanitizerCoverage::instrumentFunction(
 568     Function &F, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
 569   if (F.empty())
 570     return;
 571   if (F.getName().find(".module_ctor") != std::string::npos)
 572     return; // Should not instrument sanitizer init functions.
 573   if (F.getName().startswith("__sanitizer_"))
 574     return; // Don't instrument __sanitizer_* callbacks.
 575   // Don't touch available_externally functions, their actual body is elewhere.
 576   if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
 577     return;
 578   // Don't instrument MSVC CRT configuration helpers. They may run before normal
 579   // initialization.
 580   if (F.getName() == "__local_stdio_printf_options" ||
 581       F.getName() == "__local_stdio_scanf_options")
 582     return;
 583   if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
 584     return;
 585   // Don't instrument functions using SEH for now. Splitting basic blocks like
 586   // we do for coverage breaks WinEHPrepare.
 587   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
 588   if (F.hasPersonalityFn() &&
 589       isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
 590     return;
 591   if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
 592     SplitAllCriticalEdges(F, CriticalEdgeSplittingOptions().setIgnoreUnreachableDests());
 593   SmallVector<Instruction *, 8> IndirCalls;
 594   SmallVector<BasicBlock *, 16> BlocksToInstrument;
 595   SmallVector<Instruction *, 8> CmpTraceTargets;
 596   SmallVector<Instruction *, 8> SwitchTraceTargets;
 597   SmallVector<BinaryOperator *, 8> DivTraceTargets;
 598   SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
 599
 600   const DominatorTree *DT = DTCallback(F);
 601   const PostDominatorTree *PDT = PDTCallback(F);
 602   bool IsLeafFunc = true;
 603
 604   for (auto &BB : F) {
 605     if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
 606       BlocksToInstrument.push_back(&BB);
 607     for (auto &Inst : BB) {
 608       if (Options.IndirectCalls) {
 609         CallSite CS(&Inst);
 610         if (CS && !CS.getCalledFunction())
 611           IndirCalls.push_back(&Inst);
 612       }
 613       if (Options.TraceCmp) {
 614         if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst))
 615           if (IsInterestingCmp(CMP, DT, Options))
 616             CmpTraceTargets.push_back(&Inst);
 617         if (isa<SwitchInst>(&Inst))
 618           SwitchTraceTargets.push_back(&Inst);
 619       }
 620       if (Options.TraceDiv)
 621         if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
 622           if (BO->getOpcode() == Instruction::SDiv ||
 623               BO->getOpcode() == Instruction::UDiv)
 624             DivTraceTargets.push_back(BO);
 625       if (Options.TraceGep)
 626         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
 627           GepTraceTargets.push_back(GEP);
 628       if (Options.StackDepth)
 629         if (isa<InvokeInst>(Inst) ||
 630             (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
 631           IsLeafFunc = false;
 632     }
 633   }
 634
 635   InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
 636   InjectCoverageForIndirectCalls(F, IndirCalls);
 637   InjectTraceForCmp(F, CmpTraceTargets);
 638   InjectTraceForSwitch(F, SwitchTraceTargets);
 639   InjectTraceForDiv(F, DivTraceTargets);
 640   InjectTraceForGep(F, GepTraceTargets);
 641 }
 642
 643 GlobalVariable *ModuleSanitizerCoverage::CreateFunctionLocalArrayInSection(
 644     size_t NumElements, Function &F, Type *Ty, const char *Section) {
 645   ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
 646   auto Array = new GlobalVariable(
 647       *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
 648       Constant::getNullValue(ArrayTy), "__sancov_gen_");
 649
 650   if (TargetTriple.supportsCOMDAT() && !F.isInterposable())
 651     if (auto Comdat =
 652             GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId))
 653       Array->setComdat(Comdat);
 654   Array->setSection(getSectionName(Section));
 655   Array->setAlignment(Ty->isPointerTy() ? DL->getPointerSize()
 656                                         : Ty->getPrimitiveSizeInBits() / 8);
 657   GlobalsToAppendToUsed.push_back(Array);
 658   GlobalsToAppendToCompilerUsed.push_back(Array);
 659   MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
 660   Array->addMetadata(LLVMContext::MD_associated, *MD);
 661
 662   return Array;
 663 }
 664
 665 GlobalVariable *
 666 ModuleSanitizerCoverage::CreatePCArray(Function &F,
 667                                        ArrayRef<BasicBlock *> AllBlocks) {
 668   size_t N = AllBlocks.size();
 669   assert(N);
 670   SmallVector<Constant *, 32> PCs;
 671   IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
 672   for (size_t i = 0; i < N; i++) {
 673     if (&F.getEntryBlock() == AllBlocks[i]) {
 674       PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
 675       PCs.push_back((Constant *)IRB.CreateIntToPtr(
 676           ConstantInt::get(IntptrTy, 1), IntptrPtrTy));
 677     } else {
 678       PCs.push_back((Constant *)IRB.CreatePointerCast(
 679           BlockAddress::get(AllBlocks[i]), IntptrPtrTy));
 680       PCs.push_back((Constant *)IRB.CreateIntToPtr(
 681           ConstantInt::get(IntptrTy, 0), IntptrPtrTy));
 682     }
 683   }
 684   auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy,
 685                                                     SanCovPCsSectionName);
 686   PCArray->setInitializer(
 687       ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs));
 688   PCArray->setConstant(true);
 689
 690   return PCArray;
 691 }
 692
 693 void ModuleSanitizerCoverage::CreateFunctionLocalArrays(
 694     Function &F, ArrayRef<BasicBlock *> AllBlocks) {
 695   if (Options.TracePCGuard)
 696     FunctionGuardArray = CreateFunctionLocalArrayInSection(
 697         AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
 698
 699   if (Options.Inline8bitCounters)
 700     Function8bitCounterArray = CreateFunctionLocalArrayInSection(
 701         AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
 702
 703   if (Options.PCTable)
 704     FunctionPCsArray = CreatePCArray(F, AllBlocks);
 705 }
 706
 707 bool ModuleSanitizerCoverage::InjectCoverage(Function &F,
 708                                              ArrayRef<BasicBlock *> AllBlocks,
 709                                              bool IsLeafFunc) {
 710   if (AllBlocks.empty()) return false;
 711   CreateFunctionLocalArrays(F, AllBlocks);
 712   for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
 713     InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
 714   return true;
 715 }
 716
 717 // On every indirect call we call a run-time function
 718 // __sanitizer_cov_indir_call* with two parameters:
 719 //   - callee address,
 720 //   - global cache array that contains CacheSize pointers (zero-initialized).
 721 //     The cache is used to speed up recording the caller-callee pairs.
 722 // The address of the caller is passed implicitly via caller PC.
 723 // CacheSize is encoded in the name of the run-time function.
 724 void ModuleSanitizerCoverage::InjectCoverageForIndirectCalls(
 725     Function &F, ArrayRef<Instruction *> IndirCalls) {
 726   if (IndirCalls.empty())
 727     return;
 728   assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters);
 729   for (auto I : IndirCalls) {
 730     IRBuilder<> IRB(I);
 731     CallSite CS(I);
 732     Value *Callee = CS.getCalledValue();
 733     if (isa<InlineAsm>(Callee))
 734       continue;
 735     IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
 736   }
 737 }
 738
 739 // For every switch statement we insert a call:
 740 // __sanitizer_cov_trace_switch(CondValue,
 741 //      {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
 742
 743 void ModuleSanitizerCoverage::InjectTraceForSwitch(
 744     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
 745   for (auto I : SwitchTraceTargets) {
 746     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
 747       IRBuilder<> IRB(I);
 748       SmallVector<Constant *, 16> Initializers;
 749       Value *Cond = SI->getCondition();
 750       if (Cond->getType()->getScalarSizeInBits() >
 751           Int64Ty->getScalarSizeInBits())
 752         continue;
 753       Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
 754       Initializers.push_back(
 755           ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
 756       if (Cond->getType()->getScalarSizeInBits() <
 757           Int64Ty->getScalarSizeInBits())
 758         Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
 759       for (auto It : SI->cases()) {
 760         Constant *C = It.getCaseValue();
 761         if (C->getType()->getScalarSizeInBits() <
 762             Int64Ty->getScalarSizeInBits())
 763           C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
 764         Initializers.push_back(C);
 765       }
 766       llvm::sort(Initializers.begin() + 2, Initializers.end(),
 767                  [](const Constant *A, const Constant *B) {
 768                    return cast<ConstantInt>(A)->getLimitedValue() <
 769                           cast<ConstantInt>(B)->getLimitedValue();
 770                  });
 771       ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
 772       GlobalVariable *GV = new GlobalVariable(
 773           *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
 774           ConstantArray::get(ArrayOfInt64Ty, Initializers),
 775           "__sancov_gen_cov_switch_values");
 776       IRB.CreateCall(SanCovTraceSwitchFunction,
 777                      {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
 778     }
 779   }
 780 }
 781
 782 void ModuleSanitizerCoverage::InjectTraceForDiv(
 783     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
 784   for (auto BO : DivTraceTargets) {
 785     IRBuilder<> IRB(BO);
 786     Value *A1 = BO->getOperand(1);
 787     if (isa<ConstantInt>(A1)) continue;
 788     if (!A1->getType()->isIntegerTy())
 789       continue;
 790     uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
 791     int CallbackIdx = TypeSize == 32 ? 0 :
 792         TypeSize == 64 ? 1 : -1;
 793     if (CallbackIdx < 0) continue;
 794     auto Ty = Type::getIntNTy(*C, TypeSize);
 795     IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
 796                    {IRB.CreateIntCast(A1, Ty, true)});
 797   }
 798 }
 799
 800 void ModuleSanitizerCoverage::InjectTraceForGep(
 801     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
 802   for (auto GEP : GepTraceTargets) {
 803     IRBuilder<> IRB(GEP);
 804     for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
 805       if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy())
 806         IRB.CreateCall(SanCovTraceGepFunction,
 807                        {IRB.CreateIntCast(*I, IntptrTy, true)});
 808   }
 809 }
 810
 811 void ModuleSanitizerCoverage::InjectTraceForCmp(
 812     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
 813   for (auto I : CmpTraceTargets) {
 814     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
 815       IRBuilder<> IRB(ICMP);
 816       Value *A0 = ICMP->getOperand(0);
 817       Value *A1 = ICMP->getOperand(1);
 818       if (!A0->getType()->isIntegerTy())
 819         continue;
 820       uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
 821       int CallbackIdx = TypeSize == 8 ? 0 :
 822                         TypeSize == 16 ? 1 :
 823                         TypeSize == 32 ? 2 :
 824                         TypeSize == 64 ? 3 : -1;
 825       if (CallbackIdx < 0) continue;
 826       // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
 827       auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
 828       bool FirstIsConst = isa<ConstantInt>(A0);
 829       bool SecondIsConst = isa<ConstantInt>(A1);
 830       // If both are const, then we don't need such a comparison.
 831       if (FirstIsConst && SecondIsConst) continue;
 832       // If only one is const, then make it the first callback argument.
 833       if (FirstIsConst || SecondIsConst) {
 834         CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
 835         if (SecondIsConst)
 836           std::swap(A0, A1);
 837       }
 838
 839       auto Ty = Type::getIntNTy(*C, TypeSize);
 840       IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
 841               IRB.CreateIntCast(A1, Ty, true)});
 842     }
 843   }
 844 }
 845
 846 void ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
 847                                                     size_t Idx,
 848                                                     bool IsLeafFunc) {
 849   BasicBlock::iterator IP = BB.getFirstInsertionPt();
 850   bool IsEntryBB = &BB == &F.getEntryBlock();
 851   DebugLoc EntryLoc;
 852   if (IsEntryBB) {
 853     if (auto SP = F.getSubprogram())
 854       EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
 855     // Keep static allocas and llvm.localescape calls in the entry block.  Even
 856     // if we aren't splitting the block, it's nice for allocas to be before
 857     // calls.
 858     IP = PrepareToSplitEntryBlock(BB, IP);
 859   } else {
 860     EntryLoc = IP->getDebugLoc();
 861   }
 862
 863   IRBuilder<> IRB(&*IP);
 864   IRB.SetCurrentDebugLocation(EntryLoc);
 865   if (Options.TracePC) {
 866     IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
 867     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
 868   }
 869   if (Options.TracePCGuard) {
 870     auto GuardPtr = IRB.CreateIntToPtr(
 871         IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
 872                       ConstantInt::get(IntptrTy, Idx * 4)),
 873         Int32PtrTy);
 874     IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
 875     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
 876   }
 877   if (Options.Inline8bitCounters) {
 878     auto CounterPtr = IRB.CreateGEP(
 879         Function8bitCounterArray->getValueType(), Function8bitCounterArray,
 880         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
 881     auto Load = IRB.CreateLoad(Int8Ty, CounterPtr);
 882     auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
 883     auto Store = IRB.CreateStore(Inc, CounterPtr);
 884     SetNoSanitizeMetadata(Load);
 885     SetNoSanitizeMetadata(Store);
 886   }
 887   if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
 888     // Check stack depth.  If it's the deepest so far, record it.
 889     Module *M = F.getParent();
 890     Function *GetFrameAddr = Intrinsic::getDeclaration(
 891         M, Intrinsic::frameaddress,
 892         IRB.getInt8PtrTy(M->getDataLayout().getAllocaAddrSpace()));
 893     auto FrameAddrPtr =
 894         IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
 895     auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
 896     auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack);
 897     auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
 898     auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false);
 899     IRBuilder<> ThenIRB(ThenTerm);
 900     auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
 901     SetNoSanitizeMetadata(LowestStack);
 902     SetNoSanitizeMetadata(Store);
 903   }
 904 }
 905
 906 std::string
 907 ModuleSanitizerCoverage::getSectionName(const std::string &Section) const {
 908   if (TargetTriple.isOSBinFormatCOFF()) {
 909     if (Section == SanCovCountersSectionName)
 910       return ".SCOV$CM";
 911     if (Section == SanCovPCsSectionName)
 912       return ".SCOVP$M";
 913     return ".SCOV$GM"; // For SanCovGuardsSectionName.
 914   }
 915   if (TargetTriple.isOSBinFormatMachO())
 916     return "__DATA,__" + Section;
 917   return "__" + Section;
 918 }
 919
 920 std::string
 921 ModuleSanitizerCoverage::getSectionStart(const std::string &Section) const {
 922   if (TargetTriple.isOSBinFormatMachO())
 923     return "\1section$start$__DATA$__" + Section;
 924   return "__start___" + Section;
 925 }
 926
 927 std::string
 928 ModuleSanitizerCoverage::getSectionEnd(const std::string &Section) const {
 929   if (TargetTriple.isOSBinFormatMachO())
 930     return "\1section$end$__DATA$__" + Section;
 931   return "__stop___" + Section;
 932 }
 933
 934 char ModuleSanitizerCoverageLegacyPass::ID = 0;
 935 INITIALIZE_PASS_BEGIN(ModuleSanitizerCoverageLegacyPass, "sancov",
 936                       "Pass for instrumenting coverage on functions", false,
 937                       false)
 938 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 939 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
 940 INITIALIZE_PASS_END(ModuleSanitizerCoverageLegacyPass, "sancov",
 941                     "Pass for instrumenting coverage on functions", false,
 942                     false)
 943 ModulePass *llvm::createModuleSanitizerCoverageLegacyPassPass(
 944     const SanitizerCoverageOptions &Options) {
 945   return new ModuleSanitizerCoverageLegacyPass(Options);
 946 }