contrib/llvm-project/llvm/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/InitializePasses.h"
  36 #include "llvm/Support/CommandLine.h"
  37 #include "llvm/Support/Debug.h"
  38 #include "llvm/Support/raw_ostream.h"
  39 #include "llvm/Transforms/Instrumentation.h"
  40 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
  41 #include "llvm/Transforms/Utils/ModuleUtils.h"
  42
  43 using namespace llvm;
  44
  45 #define DEBUG_TYPE "sancov"
  46
  47 static const char *const SanCovTracePCIndirName =
  48     "__sanitizer_cov_trace_pc_indir";
  49 static const char *const SanCovTracePCName = "__sanitizer_cov_trace_pc";
  50 static const char *const SanCovTraceCmp1 = "__sanitizer_cov_trace_cmp1";
  51 static const char *const SanCovTraceCmp2 = "__sanitizer_cov_trace_cmp2";
  52 static const char *const SanCovTraceCmp4 = "__sanitizer_cov_trace_cmp4";
  53 static const char *const SanCovTraceCmp8 = "__sanitizer_cov_trace_cmp8";
  54 static const char *const SanCovTraceConstCmp1 =
  55     "__sanitizer_cov_trace_const_cmp1";
  56 static const char *const SanCovTraceConstCmp2 =
  57     "__sanitizer_cov_trace_const_cmp2";
  58 static const char *const SanCovTraceConstCmp4 =
  59     "__sanitizer_cov_trace_const_cmp4";
  60 static const char *const SanCovTraceConstCmp8 =
  61     "__sanitizer_cov_trace_const_cmp8";
  62 static const char *const SanCovTraceDiv4 = "__sanitizer_cov_trace_div4";
  63 static const char *const SanCovTraceDiv8 = "__sanitizer_cov_trace_div8";
  64 static const char *const SanCovTraceGep = "__sanitizer_cov_trace_gep";
  65 static const char *const SanCovTraceSwitchName = "__sanitizer_cov_trace_switch";
  66 static const char *const SanCovModuleCtorTracePcGuardName =
  67     "sancov.module_ctor_trace_pc_guard";
  68 static const char *const SanCovModuleCtor8bitCountersName =
  69     "sancov.module_ctor_8bit_counters";
  70 static const uint64_t SanCtorAndDtorPriority = 2;
  71
  72 static const char *const SanCovTracePCGuardName =
  73     "__sanitizer_cov_trace_pc_guard";
  74 static const char *const SanCovTracePCGuardInitName =
  75     "__sanitizer_cov_trace_pc_guard_init";
  76 static const char *const SanCov8bitCountersInitName =
  77     "__sanitizer_cov_8bit_counters_init";
  78 static const char *const SanCovPCsInitName = "__sanitizer_cov_pcs_init";
  79
  80 static const char *const SanCovGuardsSectionName = "sancov_guards";
  81 static const char *const SanCovCountersSectionName = "sancov_cntrs";
  82 static const char *const SanCovPCsSectionName = "sancov_pcs";
  83
  84 static const char *const SanCovLowestStackName = "__sancov_lowest_stack";
  85
  86 static cl::opt<int> ClCoverageLevel(
  87     "sanitizer-coverage-level",
  88     cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
  89              "3: all blocks and critical edges"),
  90     cl::Hidden, cl::init(0));
  91
  92 static cl::opt<bool> ClTracePC("sanitizer-coverage-trace-pc",
  93                                cl::desc("Experimental pc tracing"), cl::Hidden,
  94                                cl::init(false));
  95
  96 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard",
  97                                     cl::desc("pc tracing with a guard"),
  98                                     cl::Hidden, cl::init(false));
  99
 100 // If true, we create a global variable that contains PCs of all instrumented
 101 // BBs, put this global into a named section, and pass this section's bounds
 102 // to __sanitizer_cov_pcs_init.
 103 // This way the coverage instrumentation does not need to acquire the PCs
 104 // at run-time. Works with trace-pc-guard and inline-8bit-counters.
 105 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table",
 106                                      cl::desc("create a static PC table"),
 107                                      cl::Hidden, cl::init(false));
 108
 109 static cl::opt<bool>
 110     ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters",
 111                          cl::desc("increments 8-bit counter for every edge"),
 112                          cl::Hidden, cl::init(false));
 113
 114 static cl::opt<bool>
 115     ClCMPTracing("sanitizer-coverage-trace-compares",
 116                  cl::desc("Tracing of CMP and similar instructions"),
 117                  cl::Hidden, cl::init(false));
 118
 119 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs",
 120                                   cl::desc("Tracing of DIV instructions"),
 121                                   cl::Hidden, cl::init(false));
 122
 123 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps",
 124                                   cl::desc("Tracing of GEP instructions"),
 125                                   cl::Hidden, cl::init(false));
 126
 127 static cl::opt<bool>
 128     ClPruneBlocks("sanitizer-coverage-prune-blocks",
 129                   cl::desc("Reduce the number of instrumented blocks"),
 130                   cl::Hidden, cl::init(true));
 131
 132 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth",
 133                                   cl::desc("max stack depth tracing"),
 134                                   cl::Hidden, cl::init(false));
 135
 136 namespace {
 137
 138 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
 139   SanitizerCoverageOptions Res;
 140   switch (LegacyCoverageLevel) {
 141   case 0:
 142     Res.CoverageType = SanitizerCoverageOptions::SCK_None;
 143     break;
 144   case 1:
 145     Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
 146     break;
 147   case 2:
 148     Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
 149     break;
 150   case 3:
 151     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
 152     break;
 153   case 4:
 154     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
 155     Res.IndirectCalls = true;
 156     break;
 157   }
 158   return Res;
 159 }
 160
 161 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
 162   // Sets CoverageType and IndirectCalls.
 163   SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
 164   Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
 165   Options.IndirectCalls |= CLOpts.IndirectCalls;
 166   Options.TraceCmp |= ClCMPTracing;
 167   Options.TraceDiv |= ClDIVTracing;
 168   Options.TraceGep |= ClGEPTracing;
 169   Options.TracePC |= ClTracePC;
 170   Options.TracePCGuard |= ClTracePCGuard;
 171   Options.Inline8bitCounters |= ClInline8bitCounters;
 172   Options.PCTable |= ClCreatePCTable;
 173   Options.NoPrune |= !ClPruneBlocks;
 174   Options.StackDepth |= ClStackDepth;
 175   if (!Options.TracePCGuard && !Options.TracePC &&
 176       !Options.Inline8bitCounters && !Options.StackDepth)
 177     Options.TracePCGuard = true; // TracePCGuard is default.
 178   return Options;
 179 }
 180
 181 using DomTreeCallback = function_ref<const DominatorTree *(Function &F)>;
 182 using PostDomTreeCallback =
 183     function_ref<const PostDominatorTree *(Function &F)>;
 184
 185 class ModuleSanitizerCoverage {
 186 public:
 187   ModuleSanitizerCoverage(
 188       const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
 189       : Options(OverrideFromCL(Options)) {}
 190   bool instrumentModule(Module &M, DomTreeCallback DTCallback,
 191                         PostDomTreeCallback PDTCallback);
 192
 193 private:
 194   void instrumentFunction(Function &F, DomTreeCallback DTCallback,
 195                           PostDomTreeCallback PDTCallback);
 196   void InjectCoverageForIndirectCalls(Function &F,
 197                                       ArrayRef<Instruction *> IndirCalls);
 198   void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
 199   void InjectTraceForDiv(Function &F,
 200                          ArrayRef<BinaryOperator *> DivTraceTargets);
 201   void InjectTraceForGep(Function &F,
 202                          ArrayRef<GetElementPtrInst *> GepTraceTargets);
 203   void InjectTraceForSwitch(Function &F,
 204                             ArrayRef<Instruction *> SwitchTraceTargets);
 205   bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
 206                       bool IsLeafFunc = true);
 207   GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
 208                                                     Function &F, Type *Ty,
 209                                                     const char *Section);
 210   GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
 211   void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
 212   void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
 213                              bool IsLeafFunc = true);
 214   Function *CreateInitCallsForSections(Module &M, const char *CtorName,
 215                                        const char *InitFunctionName, Type *Ty,
 216                                        const char *Section);
 217   std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section,
 218                                                 Type *Ty);
 219
 220   void SetNoSanitizeMetadata(Instruction *I) {
 221     I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
 222                    MDNode::get(*C, None));
 223   }
 224
 225   std::string getSectionName(const std::string &Section) const;
 226   std::string getSectionStart(const std::string &Section) const;
 227   std::string getSectionEnd(const std::string &Section) const;
 228   FunctionCallee SanCovTracePCIndir;
 229   FunctionCallee SanCovTracePC, SanCovTracePCGuard;
 230   FunctionCallee SanCovTraceCmpFunction[4];
 231   FunctionCallee SanCovTraceConstCmpFunction[4];
 232   FunctionCallee SanCovTraceDivFunction[2];
 233   FunctionCallee SanCovTraceGepFunction;
 234   FunctionCallee SanCovTraceSwitchFunction;
 235   GlobalVariable *SanCovLowestStack;
 236   InlineAsm *EmptyAsm;
 237   Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy,
 238       *Int16Ty, *Int8Ty, *Int8PtrTy;
 239   Module *CurModule;
 240   std::string CurModuleUniqueId;
 241   Triple TargetTriple;
 242   LLVMContext *C;
 243   const DataLayout *DL;
 244
 245   GlobalVariable *FunctionGuardArray;  // for trace-pc-guard.
 246   GlobalVariable *Function8bitCounterArray;  // for inline-8bit-counters.
 247   GlobalVariable *FunctionPCsArray;  // for pc-table.
 248   SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
 249   SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
 250
 251   SanitizerCoverageOptions Options;
 252 };
 253
 254 class ModuleSanitizerCoverageLegacyPass : public ModulePass {
 255 public:
 256   ModuleSanitizerCoverageLegacyPass(
 257       const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
 258       : ModulePass(ID), Options(Options) {
 259     initializeModuleSanitizerCoverageLegacyPassPass(
 260         *PassRegistry::getPassRegistry());
 261   }
 262   bool runOnModule(Module &M) override {
 263     ModuleSanitizerCoverage ModuleSancov(Options);
 264     auto DTCallback = [this](Function &F) -> const DominatorTree * {
 265       return &this->getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
 266     };
 267     auto PDTCallback = [this](Function &F) -> const PostDominatorTree * {
 268       return &this->getAnalysis<PostDominatorTreeWrapperPass>(F)
 269                   .getPostDomTree();
 270     };
 271     return ModuleSancov.instrumentModule(M, DTCallback, PDTCallback);
 272   }
 273
 274   static char ID; // Pass identification, replacement for typeid
 275   StringRef getPassName() const override { return "ModuleSanitizerCoverage"; }
 276
 277   void getAnalysisUsage(AnalysisUsage &AU) const override {
 278     AU.addRequired<DominatorTreeWrapperPass>();
 279     AU.addRequired<PostDominatorTreeWrapperPass>();
 280   }
 281
 282 private:
 283   SanitizerCoverageOptions Options;
 284 };
 285
 286 } // namespace
 287
 288 PreservedAnalyses ModuleSanitizerCoveragePass::run(Module &M,
 289                                                    ModuleAnalysisManager &MAM) {
 290   ModuleSanitizerCoverage ModuleSancov(Options);
 291   auto &FAM = MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
 292   auto DTCallback = [&FAM](Function &F) -> const DominatorTree * {
 293     return &FAM.getResult<DominatorTreeAnalysis>(F);
 294   };
 295   auto PDTCallback = [&FAM](Function &F) -> const PostDominatorTree * {
 296     return &FAM.getResult<PostDominatorTreeAnalysis>(F);
 297   };
 298   if (ModuleSancov.instrumentModule(M, DTCallback, PDTCallback))
 299     return PreservedAnalyses::none();
 300   return PreservedAnalyses::all();
 301 }
 302
 303 std::pair<Value *, Value *>
 304 ModuleSanitizerCoverage::CreateSecStartEnd(Module &M, const char *Section,
 305                                            Type *Ty) {
 306   GlobalVariable *SecStart =
 307       new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr,
 308                          getSectionStart(Section));
 309   SecStart->setVisibility(GlobalValue::HiddenVisibility);
 310   GlobalVariable *SecEnd =
 311       new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage,
 312                          nullptr, getSectionEnd(Section));
 313   SecEnd->setVisibility(GlobalValue::HiddenVisibility);
 314   IRBuilder<> IRB(M.getContext());
 315   Value *SecEndPtr = IRB.CreatePointerCast(SecEnd, Ty);
 316   if (!TargetTriple.isOSBinFormatCOFF())
 317     return std::make_pair(IRB.CreatePointerCast(SecStart, Ty), SecEndPtr);
 318
 319   // Account for the fact that on windows-msvc __start_* symbols actually
 320   // point to a uint64_t before the start of the array.
 321   auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy);
 322   auto GEP = IRB.CreateGEP(Int8Ty, SecStartI8Ptr,
 323                            ConstantInt::get(IntptrTy, sizeof(uint64_t)));
 324   return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEndPtr);
 325 }
 326
 327 Function *ModuleSanitizerCoverage::CreateInitCallsForSections(
 328     Module &M, const char *CtorName, const char *InitFunctionName, Type *Ty,
 329     const char *Section) {
 330   auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
 331   auto SecStart = SecStartEnd.first;
 332   auto SecEnd = SecStartEnd.second;
 333   Function *CtorFunc;
 334   std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
 335       M, CtorName, InitFunctionName, {Ty, Ty}, {SecStart, SecEnd});
 336   assert(CtorFunc->getName() == CtorName);
 337
 338   if (TargetTriple.supportsCOMDAT()) {
 339     // Use comdat to dedup CtorFunc.
 340     CtorFunc->setComdat(M.getOrInsertComdat(CtorName));
 341     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
 342   } else {
 343     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
 344   }
 345
 346   if (TargetTriple.isOSBinFormatCOFF()) {
 347     // In COFF files, if the contructors are set as COMDAT (they are because
 348     // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
 349     // functions and data) is used, the constructors get stripped. To prevent
 350     // this, give the constructors weak ODR linkage and ensure the linker knows
 351     // to include the sancov constructor. This way the linker can deduplicate
 352     // the constructors but always leave one copy.
 353     CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
 354     appendToUsed(M, CtorFunc);
 355   }
 356   return CtorFunc;
 357 }
 358
 359 bool ModuleSanitizerCoverage::instrumentModule(
 360     Module &M, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
 361   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
 362     return false;
 363   C = &(M.getContext());
 364   DL = &M.getDataLayout();
 365   CurModule = &M;
 366   CurModuleUniqueId = getUniqueModuleId(CurModule);
 367   TargetTriple = Triple(M.getTargetTriple());
 368   FunctionGuardArray = nullptr;
 369   Function8bitCounterArray = nullptr;
 370   FunctionPCsArray = nullptr;
 371   IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
 372   IntptrPtrTy = PointerType::getUnqual(IntptrTy);
 373   Type *VoidTy = Type::getVoidTy(*C);
 374   IRBuilder<> IRB(*C);
 375   Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
 376   Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
 377   Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
 378   Int64Ty = IRB.getInt64Ty();
 379   Int32Ty = IRB.getInt32Ty();
 380   Int16Ty = IRB.getInt16Ty();
 381   Int8Ty = IRB.getInt8Ty();
 382
 383   SanCovTracePCIndir =
 384       M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy);
 385   // Make sure smaller parameters are zero-extended to i64 as required by the
 386   // x86_64 ABI.
 387   AttributeList SanCovTraceCmpZeroExtAL;
 388   if (TargetTriple.getArch() == Triple::x86_64) {
 389     SanCovTraceCmpZeroExtAL =
 390         SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt);
 391     SanCovTraceCmpZeroExtAL =
 392         SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt);
 393   }
 394
 395   SanCovTraceCmpFunction[0] =
 396       M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy,
 397                             IRB.getInt8Ty(), IRB.getInt8Ty());
 398   SanCovTraceCmpFunction[1] =
 399       M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy,
 400                             IRB.getInt16Ty(), IRB.getInt16Ty());
 401   SanCovTraceCmpFunction[2] =
 402       M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy,
 403                             IRB.getInt32Ty(), IRB.getInt32Ty());
 404   SanCovTraceCmpFunction[3] =
 405       M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty);
 406
 407   SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction(
 408       SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty);
 409   SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction(
 410       SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty);
 411   SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction(
 412       SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty);
 413   SanCovTraceConstCmpFunction[3] =
 414       M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty);
 415
 416   {
 417     AttributeList AL;
 418     if (TargetTriple.getArch() == Triple::x86_64)
 419       AL = AL.addParamAttribute(*C, 0, Attribute::ZExt);
 420     SanCovTraceDivFunction[0] =
 421         M.getOrInsertFunction(SanCovTraceDiv4, AL, VoidTy, IRB.getInt32Ty());
 422   }
 423   SanCovTraceDivFunction[1] =
 424       M.getOrInsertFunction(SanCovTraceDiv8, VoidTy, Int64Ty);
 425   SanCovTraceGepFunction =
 426       M.getOrInsertFunction(SanCovTraceGep, VoidTy, IntptrTy);
 427   SanCovTraceSwitchFunction =
 428       M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy);
 429
 430   Constant *SanCovLowestStackConstant =
 431       M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
 432   SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant);
 433   if (!SanCovLowestStack) {
 434     C->emitError(StringRef("'") + SanCovLowestStackName +
 435                  "' should not be declared by the user");
 436     return true;
 437   }
 438   SanCovLowestStack->setThreadLocalMode(
 439       GlobalValue::ThreadLocalMode::InitialExecTLSModel);
 440   if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
 441     SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
 442
 443   // We insert an empty inline asm after cov callbacks to avoid callback merge.
 444   EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
 445                             StringRef(""), StringRef(""),
 446                             /*hasSideEffects=*/true);
 447
 448   SanCovTracePC = M.getOrInsertFunction(SanCovTracePCName, VoidTy);
 449   SanCovTracePCGuard =
 450       M.getOrInsertFunction(SanCovTracePCGuardName, VoidTy, Int32PtrTy);
 451
 452   for (auto &F : M)
 453     instrumentFunction(F, DTCallback, PDTCallback);
 454
 455   Function *Ctor = nullptr;
 456
 457   if (FunctionGuardArray)
 458     Ctor = CreateInitCallsForSections(M, SanCovModuleCtorTracePcGuardName,
 459                                       SanCovTracePCGuardInitName, Int32PtrTy,
 460                                       SanCovGuardsSectionName);
 461   if (Function8bitCounterArray)
 462     Ctor = CreateInitCallsForSections(M, SanCovModuleCtor8bitCountersName,
 463                                       SanCov8bitCountersInitName, Int8PtrTy,
 464                                       SanCovCountersSectionName);
 465   if (Ctor && Options.PCTable) {
 466     auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy);
 467     FunctionCallee InitFunction = declareSanitizerInitFunction(
 468         M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy});
 469     IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
 470     IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
 471   }
 472   // We don't reference these arrays directly in any of our runtime functions,
 473   // so we need to prevent them from being dead stripped.
 474   if (TargetTriple.isOSBinFormatMachO())
 475     appendToUsed(M, GlobalsToAppendToUsed);
 476   appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
 477   return true;
 478 }
 479
 480 // True if block has successors and it dominates all of them.
 481 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
 482   if (succ_begin(BB) == succ_end(BB))
 483     return false;
 484
 485   for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
 486     if (!DT->dominates(BB, SUCC))
 487       return false;
 488   }
 489
 490   return true;
 491 }
 492
 493 // True if block has predecessors and it postdominates all of them.
 494 static bool isFullPostDominator(const BasicBlock *BB,
 495                                 const PostDominatorTree *PDT) {
 496   if (pred_begin(BB) == pred_end(BB))
 497     return false;
 498
 499   for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
 500     if (!PDT->dominates(BB, PRED))
 501       return false;
 502   }
 503
 504   return true;
 505 }
 506
 507 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
 508                                   const DominatorTree *DT,
 509                                   const PostDominatorTree *PDT,
 510                                   const SanitizerCoverageOptions &Options) {
 511   // Don't insert coverage for blocks containing nothing but unreachable: we
 512   // will never call __sanitizer_cov() for them, so counting them in
 513   // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
 514   // percentage. Also, unreachable instructions frequently have no debug
 515   // locations.
 516   if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime()))
 517     return false;
 518
 519   // Don't insert coverage into blocks without a valid insertion point
 520   // (catchswitch blocks).
 521   if (BB->getFirstInsertionPt() == BB->end())
 522     return false;
 523
 524   if (Options.NoPrune || &F.getEntryBlock() == BB)
 525     return true;
 526
 527   if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
 528       &F.getEntryBlock() != BB)
 529     return false;
 530
 531   // Do not instrument full dominators, or full post-dominators with multiple
 532   // predecessors.
 533   return !isFullDominator(BB, DT)
 534     && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
 535 }
 536
 537
 538 // Returns true iff From->To is a backedge.
 539 // A twist here is that we treat From->To as a backedge if
 540 //   * To dominates From or
 541 //   * To->UniqueSuccessor dominates From
 542 static bool IsBackEdge(BasicBlock *From, BasicBlock *To,
 543                        const DominatorTree *DT) {
 544   if (DT->dominates(To, From))
 545     return true;
 546   if (auto Next = To->getUniqueSuccessor())
 547     if (DT->dominates(Next, From))
 548       return true;
 549   return false;
 550 }
 551
 552 // Prunes uninteresting Cmp instrumentation:
 553 //   * CMP instructions that feed into loop backedge branch.
 554 //
 555 // Note that Cmp pruning is controlled by the same flag as the
 556 // BB pruning.
 557 static bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree *DT,
 558                              const SanitizerCoverageOptions &Options) {
 559   if (!Options.NoPrune)
 560     if (CMP->hasOneUse())
 561       if (auto BR = dyn_cast<BranchInst>(CMP->user_back()))
 562         for (BasicBlock *B : BR->successors())
 563           if (IsBackEdge(BR->getParent(), B, DT))
 564             return false;
 565   return true;
 566 }
 567
 568 void ModuleSanitizerCoverage::instrumentFunction(
 569     Function &F, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
 570   if (F.empty())
 571     return;
 572   if (F.getName().find(".module_ctor") != std::string::npos)
 573     return; // Should not instrument sanitizer init functions.
 574   if (F.getName().startswith("__sanitizer_"))
 575     return; // Don't instrument __sanitizer_* callbacks.
 576   // Don't touch available_externally functions, their actual body is elewhere.
 577   if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
 578     return;
 579   // Don't instrument MSVC CRT configuration helpers. They may run before normal
 580   // initialization.
 581   if (F.getName() == "__local_stdio_printf_options" ||
 582       F.getName() == "__local_stdio_scanf_options")
 583     return;
 584   if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
 585     return;
 586   // Don't instrument functions using SEH for now. Splitting basic blocks like
 587   // we do for coverage breaks WinEHPrepare.
 588   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
 589   if (F.hasPersonalityFn() &&
 590       isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
 591     return;
 592   if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
 593     SplitAllCriticalEdges(F, CriticalEdgeSplittingOptions().setIgnoreUnreachableDests());
 594   SmallVector<Instruction *, 8> IndirCalls;
 595   SmallVector<BasicBlock *, 16> BlocksToInstrument;
 596   SmallVector<Instruction *, 8> CmpTraceTargets;
 597   SmallVector<Instruction *, 8> SwitchTraceTargets;
 598   SmallVector<BinaryOperator *, 8> DivTraceTargets;
 599   SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
 600
 601   const DominatorTree *DT = DTCallback(F);
 602   const PostDominatorTree *PDT = PDTCallback(F);
 603   bool IsLeafFunc = true;
 604
 605   for (auto &BB : F) {
 606     if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
 607       BlocksToInstrument.push_back(&BB);
 608     for (auto &Inst : BB) {
 609       if (Options.IndirectCalls) {
 610         CallSite CS(&Inst);
 611         if (CS && !CS.getCalledFunction())
 612           IndirCalls.push_back(&Inst);
 613       }
 614       if (Options.TraceCmp) {
 615         if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst))
 616           if (IsInterestingCmp(CMP, DT, Options))
 617             CmpTraceTargets.push_back(&Inst);
 618         if (isa<SwitchInst>(&Inst))
 619           SwitchTraceTargets.push_back(&Inst);
 620       }
 621       if (Options.TraceDiv)
 622         if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
 623           if (BO->getOpcode() == Instruction::SDiv ||
 624               BO->getOpcode() == Instruction::UDiv)
 625             DivTraceTargets.push_back(BO);
 626       if (Options.TraceGep)
 627         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
 628           GepTraceTargets.push_back(GEP);
 629       if (Options.StackDepth)
 630         if (isa<InvokeInst>(Inst) ||
 631             (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
 632           IsLeafFunc = false;
 633     }
 634   }
 635
 636   InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
 637   InjectCoverageForIndirectCalls(F, IndirCalls);
 638   InjectTraceForCmp(F, CmpTraceTargets);
 639   InjectTraceForSwitch(F, SwitchTraceTargets);
 640   InjectTraceForDiv(F, DivTraceTargets);
 641   InjectTraceForGep(F, GepTraceTargets);
 642 }
 643
 644 GlobalVariable *ModuleSanitizerCoverage::CreateFunctionLocalArrayInSection(
 645     size_t NumElements, Function &F, Type *Ty, const char *Section) {
 646   ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
 647   auto Array = new GlobalVariable(
 648       *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
 649       Constant::getNullValue(ArrayTy), "__sancov_gen_");
 650
 651   if (TargetTriple.supportsCOMDAT() && !F.isInterposable())
 652     if (auto Comdat =
 653             GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId))
 654       Array->setComdat(Comdat);
 655   Array->setSection(getSectionName(Section));
 656   Array->setAlignment(Align(Ty->isPointerTy()
 657                                 ? DL->getPointerSize()
 658                                 : Ty->getPrimitiveSizeInBits() / 8));
 659   GlobalsToAppendToUsed.push_back(Array);
 660   GlobalsToAppendToCompilerUsed.push_back(Array);
 661   MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
 662   Array->addMetadata(LLVMContext::MD_associated, *MD);
 663
 664   return Array;
 665 }
 666
 667 GlobalVariable *
 668 ModuleSanitizerCoverage::CreatePCArray(Function &F,
 669                                        ArrayRef<BasicBlock *> AllBlocks) {
 670   size_t N = AllBlocks.size();
 671   assert(N);
 672   SmallVector<Constant *, 32> PCs;
 673   IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
 674   for (size_t i = 0; i < N; i++) {
 675     if (&F.getEntryBlock() == AllBlocks[i]) {
 676       PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
 677       PCs.push_back((Constant *)IRB.CreateIntToPtr(
 678           ConstantInt::get(IntptrTy, 1), IntptrPtrTy));
 679     } else {
 680       PCs.push_back((Constant *)IRB.CreatePointerCast(
 681           BlockAddress::get(AllBlocks[i]), IntptrPtrTy));
 682       PCs.push_back((Constant *)IRB.CreateIntToPtr(
 683           ConstantInt::get(IntptrTy, 0), IntptrPtrTy));
 684     }
 685   }
 686   auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy,
 687                                                     SanCovPCsSectionName);
 688   PCArray->setInitializer(
 689       ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs));
 690   PCArray->setConstant(true);
 691
 692   return PCArray;
 693 }
 694
 695 void ModuleSanitizerCoverage::CreateFunctionLocalArrays(
 696     Function &F, ArrayRef<BasicBlock *> AllBlocks) {
 697   if (Options.TracePCGuard)
 698     FunctionGuardArray = CreateFunctionLocalArrayInSection(
 699         AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
 700
 701   if (Options.Inline8bitCounters)
 702     Function8bitCounterArray = CreateFunctionLocalArrayInSection(
 703         AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
 704
 705   if (Options.PCTable)
 706     FunctionPCsArray = CreatePCArray(F, AllBlocks);
 707 }
 708
 709 bool ModuleSanitizerCoverage::InjectCoverage(Function &F,
 710                                              ArrayRef<BasicBlock *> AllBlocks,
 711                                              bool IsLeafFunc) {
 712   if (AllBlocks.empty()) return false;
 713   CreateFunctionLocalArrays(F, AllBlocks);
 714   for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
 715     InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
 716   return true;
 717 }
 718
 719 // On every indirect call we call a run-time function
 720 // __sanitizer_cov_indir_call* with two parameters:
 721 //   - callee address,
 722 //   - global cache array that contains CacheSize pointers (zero-initialized).
 723 //     The cache is used to speed up recording the caller-callee pairs.
 724 // The address of the caller is passed implicitly via caller PC.
 725 // CacheSize is encoded in the name of the run-time function.
 726 void ModuleSanitizerCoverage::InjectCoverageForIndirectCalls(
 727     Function &F, ArrayRef<Instruction *> IndirCalls) {
 728   if (IndirCalls.empty())
 729     return;
 730   assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters);
 731   for (auto I : IndirCalls) {
 732     IRBuilder<> IRB(I);
 733     CallSite CS(I);
 734     Value *Callee = CS.getCalledValue();
 735     if (isa<InlineAsm>(Callee))
 736       continue;
 737     IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
 738   }
 739 }
 740
 741 // For every switch statement we insert a call:
 742 // __sanitizer_cov_trace_switch(CondValue,
 743 //      {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
 744
 745 void ModuleSanitizerCoverage::InjectTraceForSwitch(
 746     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
 747   for (auto I : SwitchTraceTargets) {
 748     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
 749       IRBuilder<> IRB(I);
 750       SmallVector<Constant *, 16> Initializers;
 751       Value *Cond = SI->getCondition();
 752       if (Cond->getType()->getScalarSizeInBits() >
 753           Int64Ty->getScalarSizeInBits())
 754         continue;
 755       Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
 756       Initializers.push_back(
 757           ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
 758       if (Cond->getType()->getScalarSizeInBits() <
 759           Int64Ty->getScalarSizeInBits())
 760         Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
 761       for (auto It : SI->cases()) {
 762         Constant *C = It.getCaseValue();
 763         if (C->getType()->getScalarSizeInBits() <
 764             Int64Ty->getScalarSizeInBits())
 765           C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
 766         Initializers.push_back(C);
 767       }
 768       llvm::sort(Initializers.begin() + 2, Initializers.end(),
 769                  [](const Constant *A, const Constant *B) {
 770                    return cast<ConstantInt>(A)->getLimitedValue() <
 771                           cast<ConstantInt>(B)->getLimitedValue();
 772                  });
 773       ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
 774       GlobalVariable *GV = new GlobalVariable(
 775           *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
 776           ConstantArray::get(ArrayOfInt64Ty, Initializers),
 777           "__sancov_gen_cov_switch_values");
 778       IRB.CreateCall(SanCovTraceSwitchFunction,
 779                      {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
 780     }
 781   }
 782 }
 783
 784 void ModuleSanitizerCoverage::InjectTraceForDiv(
 785     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
 786   for (auto BO : DivTraceTargets) {
 787     IRBuilder<> IRB(BO);
 788     Value *A1 = BO->getOperand(1);
 789     if (isa<ConstantInt>(A1)) continue;
 790     if (!A1->getType()->isIntegerTy())
 791       continue;
 792     uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
 793     int CallbackIdx = TypeSize == 32 ? 0 :
 794         TypeSize == 64 ? 1 : -1;
 795     if (CallbackIdx < 0) continue;
 796     auto Ty = Type::getIntNTy(*C, TypeSize);
 797     IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
 798                    {IRB.CreateIntCast(A1, Ty, true)});
 799   }
 800 }
 801
 802 void ModuleSanitizerCoverage::InjectTraceForGep(
 803     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
 804   for (auto GEP : GepTraceTargets) {
 805     IRBuilder<> IRB(GEP);
 806     for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
 807       if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy())
 808         IRB.CreateCall(SanCovTraceGepFunction,
 809                        {IRB.CreateIntCast(*I, IntptrTy, true)});
 810   }
 811 }
 812
 813 void ModuleSanitizerCoverage::InjectTraceForCmp(
 814     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
 815   for (auto I : CmpTraceTargets) {
 816     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
 817       IRBuilder<> IRB(ICMP);
 818       Value *A0 = ICMP->getOperand(0);
 819       Value *A1 = ICMP->getOperand(1);
 820       if (!A0->getType()->isIntegerTy())
 821         continue;
 822       uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
 823       int CallbackIdx = TypeSize == 8 ? 0 :
 824                         TypeSize == 16 ? 1 :
 825                         TypeSize == 32 ? 2 :
 826                         TypeSize == 64 ? 3 : -1;
 827       if (CallbackIdx < 0) continue;
 828       // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
 829       auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
 830       bool FirstIsConst = isa<ConstantInt>(A0);
 831       bool SecondIsConst = isa<ConstantInt>(A1);
 832       // If both are const, then we don't need such a comparison.
 833       if (FirstIsConst && SecondIsConst) continue;
 834       // If only one is const, then make it the first callback argument.
 835       if (FirstIsConst || SecondIsConst) {
 836         CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
 837         if (SecondIsConst)
 838           std::swap(A0, A1);
 839       }
 840
 841       auto Ty = Type::getIntNTy(*C, TypeSize);
 842       IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
 843               IRB.CreateIntCast(A1, Ty, true)});
 844     }
 845   }
 846 }
 847
 848 void ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
 849                                                     size_t Idx,
 850                                                     bool IsLeafFunc) {
 851   BasicBlock::iterator IP = BB.getFirstInsertionPt();
 852   bool IsEntryBB = &BB == &F.getEntryBlock();
 853   DebugLoc EntryLoc;
 854   if (IsEntryBB) {
 855     if (auto SP = F.getSubprogram())
 856       EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
 857     // Keep static allocas and llvm.localescape calls in the entry block.  Even
 858     // if we aren't splitting the block, it's nice for allocas to be before
 859     // calls.
 860     IP = PrepareToSplitEntryBlock(BB, IP);
 861   } else {
 862     EntryLoc = IP->getDebugLoc();
 863   }
 864
 865   IRBuilder<> IRB(&*IP);
 866   IRB.SetCurrentDebugLocation(EntryLoc);
 867   if (Options.TracePC) {
 868     IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
 869     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
 870   }
 871   if (Options.TracePCGuard) {
 872     auto GuardPtr = IRB.CreateIntToPtr(
 873         IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
 874                       ConstantInt::get(IntptrTy, Idx * 4)),
 875         Int32PtrTy);
 876     IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
 877     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
 878   }
 879   if (Options.Inline8bitCounters) {
 880     auto CounterPtr = IRB.CreateGEP(
 881         Function8bitCounterArray->getValueType(), Function8bitCounterArray,
 882         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
 883     auto Load = IRB.CreateLoad(Int8Ty, CounterPtr);
 884     auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
 885     auto Store = IRB.CreateStore(Inc, CounterPtr);
 886     SetNoSanitizeMetadata(Load);
 887     SetNoSanitizeMetadata(Store);
 888   }
 889   if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
 890     // Check stack depth.  If it's the deepest so far, record it.
 891     Module *M = F.getParent();
 892     Function *GetFrameAddr = Intrinsic::getDeclaration(
 893         M, Intrinsic::frameaddress,
 894         IRB.getInt8PtrTy(M->getDataLayout().getAllocaAddrSpace()));
 895     auto FrameAddrPtr =
 896         IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
 897     auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
 898     auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack);
 899     auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
 900     auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false);
 901     IRBuilder<> ThenIRB(ThenTerm);
 902     auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
 903     SetNoSanitizeMetadata(LowestStack);
 904     SetNoSanitizeMetadata(Store);
 905   }
 906 }
 907
 908 std::string
 909 ModuleSanitizerCoverage::getSectionName(const std::string &Section) const {
 910   if (TargetTriple.isOSBinFormatCOFF()) {
 911     if (Section == SanCovCountersSectionName)
 912       return ".SCOV$CM";
 913     if (Section == SanCovPCsSectionName)
 914       return ".SCOVP$M";
 915     return ".SCOV$GM"; // For SanCovGuardsSectionName.
 916   }
 917   if (TargetTriple.isOSBinFormatMachO())
 918     return "__DATA,__" + Section;
 919   return "__" + Section;
 920 }
 921
 922 std::string
 923 ModuleSanitizerCoverage::getSectionStart(const std::string &Section) const {
 924   if (TargetTriple.isOSBinFormatMachO())
 925     return "\1section$start$__DATA$__" + Section;
 926   return "__start___" + Section;
 927 }
 928
 929 std::string
 930 ModuleSanitizerCoverage::getSectionEnd(const std::string &Section) const {
 931   if (TargetTriple.isOSBinFormatMachO())
 932     return "\1section$end$__DATA$__" + Section;
 933   return "__stop___" + Section;
 934 }
 935
 936 char ModuleSanitizerCoverageLegacyPass::ID = 0;
 937 INITIALIZE_PASS_BEGIN(ModuleSanitizerCoverageLegacyPass, "sancov",
 938                       "Pass for instrumenting coverage on functions", false,
 939                       false)
 940 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 941 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
 942 INITIALIZE_PASS_END(ModuleSanitizerCoverageLegacyPass, "sancov",
 943                     "Pass for instrumenting coverage on functions", false,
 944                     false)
 945 ModulePass *llvm::createModuleSanitizerCoverageLegacyPassPass(
 946     const SanitizerCoverageOptions &Options) {
 947   return new ModuleSanitizerCoverageLegacyPass(Options);
 948 }