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 bool canInstrumentWithSancov(const Function &F) {
 181   if (F.empty())
 182     return false;
 183   if (F.getName().find(".module_ctor") != std::string::npos)
 184     return false; // Should not instrument sanitizer init functions.
 185   if (F.getName().startswith("__sanitizer_"))
 186     return false; // Don't instrument __sanitizer_* callbacks.
 187   // Don't touch available_externally functions, their actual body is elewhere.
 188   if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
 189     return false;
 190   // Don't instrument MSVC CRT configuration helpers. They may run before normal
 191   // initialization.
 192   if (F.getName() == "__local_stdio_printf_options" ||
 193       F.getName() == "__local_stdio_scanf_options")
 194     return false;
 195   if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
 196     return false;
 197   // Don't instrument functions using SEH for now. Splitting basic blocks like
 198   // we do for coverage breaks WinEHPrepare.
 199   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
 200   if (F.hasPersonalityFn() &&
 201       isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
 202     return false;
 203   return true;
 204 }
 205
 206 std::string getSectionStartImpl(const Triple &TargetTriple,
 207                                 const std::string &Section) {
 208   if (TargetTriple.isOSBinFormatMachO())
 209     return "\1section$start$__DATA$__" + Section;
 210   return "__start___" + Section;
 211 }
 212
 213 std::string getSectionEndImpl(const Triple &TargetTriple,
 214                               const std::string &Section) {
 215   if (TargetTriple.isOSBinFormatMachO())
 216     return "\1section$end$__DATA$__" + Section;
 217   return "__stop___" + Section;
 218 }
 219
 220 /// This is a class for instrumenting the module to add calls to initializing
 221 /// the trace PC guards and 8bit counter globals. This should only be done
 222 /// though if there is at least one function that can be instrumented with
 223 /// Sancov.
 224 class ModuleSanitizerCoverage {
 225 public:
 226   ModuleSanitizerCoverage(const SanitizerCoverageOptions &Options)
 227       : Options(OverrideFromCL(Options)) {}
 228
 229   bool instrumentModule(Module &M) {
 230     if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
 231       return false;
 232
 233     Function *Ctor = nullptr;
 234     LLVMContext *C = &(M.getContext());
 235     const DataLayout *DL = &M.getDataLayout();
 236     TargetTriple = Triple(M.getTargetTriple());
 237     IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
 238     Type *IntptrPtrTy = PointerType::getUnqual(IntptrTy);
 239     IRBuilder<> IRB(*C);
 240     Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
 241     Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
 242     Int8Ty = IRB.getInt8Ty();
 243
 244     // Check that the __sancov_lowest_stack marker does not already exist.
 245     Constant *SanCovLowestStackConstant =
 246         M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
 247     GlobalVariable *SanCovLowestStack =
 248         dyn_cast<GlobalVariable>(SanCovLowestStackConstant);
 249     if (!SanCovLowestStack) {
 250       C->emitError(StringRef("'") + SanCovLowestStackName +
 251                    "' should not be declared by the user");
 252       return true;
 253     }
 254
 255     // We want to emit guard init calls if the module contains a function that
 256     // we can instrument with SanitizerCoverage. We ignore any functions that
 257     // were inserted by SanitizerCoverage and get the result from the analysis
 258     // that checks for a valid function that the analysis may have run over.
 259     if (!llvm::any_of(
 260             M, [](const Function &F) { return canInstrumentWithSancov(F); }))
 261       return false;
 262
 263     // Emit the init calls.
 264     if (Options.TracePCGuard)
 265       Ctor = CreateInitCallsForSections(M, SanCovModuleCtorTracePcGuardName,
 266                                         SanCovTracePCGuardInitName, Int32PtrTy,
 267                                         SanCovGuardsSectionName);
 268     if (Options.Inline8bitCounters)
 269       Ctor = CreateInitCallsForSections(M, SanCovModuleCtor8bitCountersName,
 270                                         SanCov8bitCountersInitName, Int8PtrTy,
 271                                         SanCovCountersSectionName);
 272     if (Ctor && Options.PCTable) {
 273       auto SecStartEnd =
 274           CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy);
 275       FunctionCallee InitFunction = declareSanitizerInitFunction(
 276           M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy});
 277       IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
 278       IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
 279     }
 280     return Ctor;
 281   }
 282
 283 private:
 284   Function *CreateInitCallsForSections(Module &M, const char *CtorName,
 285                                        const char *InitFunctionName, Type *Ty,
 286                                        const char *Section);
 287   std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section,
 288                                                 Type *Ty);
 289   std::string getSectionStart(const std::string &Section) const {
 290     return getSectionStartImpl(TargetTriple, Section);
 291   }
 292   std::string getSectionEnd(const std::string &Section) const {
 293     return getSectionEndImpl(TargetTriple, Section);
 294   }
 295
 296   SanitizerCoverageOptions Options;
 297   Triple TargetTriple;
 298   Type *IntptrTy, *Int8PtrTy, *Int8Ty;
 299 };
 300
 301 class ModuleSanitizerCoverageLegacyPass : public ModulePass {
 302 public:
 303   static char ID;
 304
 305   ModuleSanitizerCoverageLegacyPass(
 306       SanitizerCoverageOptions Options = SanitizerCoverageOptions())
 307       : ModulePass(ID), Options(Options) {
 308     initializeModuleSanitizerCoverageLegacyPassPass(
 309         *PassRegistry::getPassRegistry());
 310   }
 311
 312   bool runOnModule(Module &M) override {
 313     ModuleSanitizerCoverage ModuleSancov(Options);
 314     return ModuleSancov.instrumentModule(M);
 315   };
 316
 317   StringRef getPassName() const override {
 318     return "ModuleSanitizerCoverageLegacyPass";
 319   }
 320
 321 private:
 322   SanitizerCoverageOptions Options;
 323 };
 324
 325 char ModuleSanitizerCoverageLegacyPass::ID = 0;
 326
 327 class SanitizerCoverage {
 328 public:
 329   SanitizerCoverage(Function &F, const SanitizerCoverageOptions &Options)
 330       : CurModule(F.getParent()), Options(OverrideFromCL(Options)) {
 331     initializeModule(*F.getParent());
 332   }
 333
 334   ~SanitizerCoverage() { finalizeModule(*CurModule); }
 335
 336   bool instrumentFunction(Function &F, const DominatorTree *DT,
 337                           const PostDominatorTree *PDT);
 338
 339 private:
 340   void initializeModule(Module &M);
 341   void finalizeModule(Module &M);
 342   void InjectCoverageForIndirectCalls(Function &F,
 343                                       ArrayRef<Instruction *> IndirCalls);
 344   void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
 345   void InjectTraceForDiv(Function &F,
 346                          ArrayRef<BinaryOperator *> DivTraceTargets);
 347   void InjectTraceForGep(Function &F,
 348                          ArrayRef<GetElementPtrInst *> GepTraceTargets);
 349   void InjectTraceForSwitch(Function &F,
 350                             ArrayRef<Instruction *> SwitchTraceTargets);
 351   bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
 352                       bool IsLeafFunc = true);
 353   GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
 354                                                     Function &F, Type *Ty,
 355                                                     const char *Section);
 356   GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
 357   void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
 358   void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
 359                              bool IsLeafFunc = true);
 360
 361   void SetNoSanitizeMetadata(Instruction *I) {
 362     I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
 363                    MDNode::get(*C, None));
 364   }
 365
 366   std::string getSectionName(const std::string &Section) const;
 367   std::string getSectionStart(const std::string &Section) const;
 368   std::string getSectionEnd(const std::string &Section) const;
 369   FunctionCallee SanCovTracePCIndir;
 370   FunctionCallee SanCovTracePC, SanCovTracePCGuard;
 371   FunctionCallee SanCovTraceCmpFunction[4];
 372   FunctionCallee SanCovTraceConstCmpFunction[4];
 373   FunctionCallee SanCovTraceDivFunction[2];
 374   FunctionCallee SanCovTraceGepFunction;
 375   FunctionCallee SanCovTraceSwitchFunction;
 376   GlobalVariable *SanCovLowestStack;
 377   InlineAsm *EmptyAsm;
 378   Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy,
 379       *Int16Ty, *Int8Ty, *Int8PtrTy;
 380   Module *CurModule;
 381   std::string CurModuleUniqueId;
 382   Triple TargetTriple;
 383   LLVMContext *C;
 384   const DataLayout *DL;
 385
 386   GlobalVariable *FunctionGuardArray;  // for trace-pc-guard.
 387   GlobalVariable *Function8bitCounterArray;  // for inline-8bit-counters.
 388   GlobalVariable *FunctionPCsArray;  // for pc-table.
 389   SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
 390   SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
 391
 392   SanitizerCoverageOptions Options;
 393 };
 394
 395 class SanitizerCoverageLegacyPass : public FunctionPass {
 396 public:
 397   static char ID; // Pass identification, replacement for typeid
 398
 399   SanitizerCoverageLegacyPass(
 400       SanitizerCoverageOptions Options = SanitizerCoverageOptions())
 401       : FunctionPass(ID), Options(Options) {
 402     initializeSanitizerCoverageLegacyPassPass(*PassRegistry::getPassRegistry());
 403   }
 404
 405   bool runOnFunction(Function &F) override {
 406     const DominatorTree *DT =
 407         &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
 408     const PostDominatorTree *PDT =
 409         &getAnalysis<PostDominatorTreeWrapperPass>().getPostDomTree();
 410     SanitizerCoverage Sancov(F, Options);
 411     return Sancov.instrumentFunction(F, DT, PDT);
 412   }
 413
 414   StringRef getPassName() const override {
 415     return "SanitizerCoverageLegacyPass";
 416   }
 417
 418   void getAnalysisUsage(AnalysisUsage &AU) const override {
 419     // Make the module sancov pass required by this pass so that it runs when
 420     // -sancov is passed.
 421     AU.addRequired<ModuleSanitizerCoverageLegacyPass>();
 422     AU.addRequired<DominatorTreeWrapperPass>();
 423     AU.addRequired<PostDominatorTreeWrapperPass>();
 424   }
 425
 426 private:
 427   SanitizerCoverageOptions Options;
 428 };
 429
 430 } // namespace
 431
 432 PreservedAnalyses SanitizerCoveragePass::run(Function &F,
 433                                              FunctionAnalysisManager &AM) {
 434   const DominatorTree *DT = &AM.getResult<DominatorTreeAnalysis>(F);
 435   const PostDominatorTree *PDT = &AM.getResult<PostDominatorTreeAnalysis>(F);
 436   SanitizerCoverage Sancov(F, Options);
 437   if (Sancov.instrumentFunction(F, DT, PDT))
 438     return PreservedAnalyses::none();
 439   return PreservedAnalyses::all();
 440 }
 441
 442 PreservedAnalyses ModuleSanitizerCoveragePass::run(Module &M,
 443                                                    ModuleAnalysisManager &AM) {
 444   ModuleSanitizerCoverage ModuleSancov(Options);
 445   if (ModuleSancov.instrumentModule(M))
 446     return PreservedAnalyses::none();
 447   return PreservedAnalyses::all();
 448 }
 449
 450 std::pair<Value *, Value *>
 451 ModuleSanitizerCoverage::CreateSecStartEnd(Module &M, const char *Section,
 452                                            Type *Ty) {
 453   GlobalVariable *SecStart =
 454       new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr,
 455                          getSectionStart(Section));
 456   SecStart->setVisibility(GlobalValue::HiddenVisibility);
 457   GlobalVariable *SecEnd =
 458       new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage,
 459                          nullptr, getSectionEnd(Section));
 460   SecEnd->setVisibility(GlobalValue::HiddenVisibility);
 461
 462   IRBuilder<> IRB(M.getContext());
 463   Value *SecEndPtr = IRB.CreatePointerCast(SecEnd, Ty);
 464   if (!TargetTriple.isOSBinFormatCOFF())
 465     return std::make_pair(IRB.CreatePointerCast(SecStart, Ty), SecEndPtr);
 466
 467   // Account for the fact that on windows-msvc __start_* symbols actually
 468   // point to a uint64_t before the start of the array.
 469   auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy);
 470   auto GEP = IRB.CreateGEP(Int8Ty, SecStartI8Ptr,
 471                            ConstantInt::get(IntptrTy, sizeof(uint64_t)));
 472   return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEndPtr);
 473 }
 474
 475 Function *ModuleSanitizerCoverage::CreateInitCallsForSections(
 476     Module &M, const char *CtorName, const char *InitFunctionName, Type *Ty,
 477     const char *Section) {
 478   auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
 479   auto SecStart = SecStartEnd.first;
 480   auto SecEnd = SecStartEnd.second;
 481   Function *CtorFunc;
 482   std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
 483       M, CtorName, InitFunctionName, {Ty, Ty}, {SecStart, SecEnd});
 484   assert(CtorFunc->getName() == CtorName);
 485
 486   if (TargetTriple.supportsCOMDAT()) {
 487     // Use comdat to dedup CtorFunc.
 488     CtorFunc->setComdat(M.getOrInsertComdat(CtorName));
 489     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
 490   } else {
 491     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
 492   }
 493
 494   if (TargetTriple.isOSBinFormatCOFF()) {
 495     // In COFF files, if the contructors are set as COMDAT (they are because
 496     // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
 497     // functions and data) is used, the constructors get stripped. To prevent
 498     // this, give the constructors weak ODR linkage and ensure the linker knows
 499     // to include the sancov constructor. This way the linker can deduplicate
 500     // the constructors but always leave one copy.
 501     CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
 502     appendToUsed(M, CtorFunc);
 503   }
 504   return CtorFunc;
 505 }
 506
 507 void SanitizerCoverage::initializeModule(Module &M) {
 508   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
 509     return;
 510   C = &(M.getContext());
 511   DL = &M.getDataLayout();
 512   CurModuleUniqueId = getUniqueModuleId(CurModule);
 513   TargetTriple = Triple(M.getTargetTriple());
 514   FunctionGuardArray = nullptr;
 515   Function8bitCounterArray = nullptr;
 516   FunctionPCsArray = nullptr;
 517   IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
 518   IntptrPtrTy = PointerType::getUnqual(IntptrTy);
 519   Type *VoidTy = Type::getVoidTy(*C);
 520   IRBuilder<> IRB(*C);
 521   Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
 522   Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
 523   Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
 524   Int64Ty = IRB.getInt64Ty();
 525   Int32Ty = IRB.getInt32Ty();
 526   Int16Ty = IRB.getInt16Ty();
 527   Int8Ty = IRB.getInt8Ty();
 528
 529   SanCovTracePCIndir =
 530       M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy);
 531   // Make sure smaller parameters are zero-extended to i64 as required by the
 532   // x86_64 ABI.
 533   AttributeList SanCovTraceCmpZeroExtAL;
 534   if (TargetTriple.getArch() == Triple::x86_64) {
 535     SanCovTraceCmpZeroExtAL =
 536         SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt);
 537     SanCovTraceCmpZeroExtAL =
 538         SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt);
 539   }
 540
 541   SanCovTraceCmpFunction[0] =
 542       M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy,
 543                             IRB.getInt8Ty(), IRB.getInt8Ty());
 544   SanCovTraceCmpFunction[1] =
 545       M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy,
 546                             IRB.getInt16Ty(), IRB.getInt16Ty());
 547   SanCovTraceCmpFunction[2] =
 548       M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy,
 549                             IRB.getInt32Ty(), IRB.getInt32Ty());
 550   SanCovTraceCmpFunction[3] =
 551       M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty);
 552
 553   SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction(
 554       SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty);
 555   SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction(
 556       SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty);
 557   SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction(
 558       SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty);
 559   SanCovTraceConstCmpFunction[3] =
 560       M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty);
 561
 562   {
 563     AttributeList AL;
 564     if (TargetTriple.getArch() == Triple::x86_64)
 565       AL = AL.addParamAttribute(*C, 0, Attribute::ZExt);
 566     SanCovTraceDivFunction[0] =
 567         M.getOrInsertFunction(SanCovTraceDiv4, AL, VoidTy, IRB.getInt32Ty());
 568   }
 569   SanCovTraceDivFunction[1] =
 570       M.getOrInsertFunction(SanCovTraceDiv8, VoidTy, Int64Ty);
 571   SanCovTraceGepFunction =
 572       M.getOrInsertFunction(SanCovTraceGep, VoidTy, IntptrTy);
 573   SanCovTraceSwitchFunction =
 574       M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy);
 575
 576   Constant *SanCovLowestStackConstant =
 577       M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
 578   SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant);
 579   SanCovLowestStack->setThreadLocalMode(
 580       GlobalValue::ThreadLocalMode::InitialExecTLSModel);
 581   if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
 582     SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
 583
 584   // We insert an empty inline asm after cov callbacks to avoid callback merge.
 585   EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
 586                             StringRef(""), StringRef(""),
 587                             /*hasSideEffects=*/true);
 588
 589   SanCovTracePC = M.getOrInsertFunction(SanCovTracePCName, VoidTy);
 590   SanCovTracePCGuard =
 591       M.getOrInsertFunction(SanCovTracePCGuardName, VoidTy, Int32PtrTy);
 592 }
 593
 594 void SanitizerCoverage::finalizeModule(Module &M) {
 595   // We don't reference these arrays directly in any of our runtime functions,
 596   // so we need to prevent them from being dead stripped.
 597   if (TargetTriple.isOSBinFormatMachO())
 598     appendToUsed(M, GlobalsToAppendToUsed);
 599   appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
 600 }
 601
 602 // True if block has successors and it dominates all of them.
 603 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
 604   if (succ_begin(BB) == succ_end(BB))
 605     return false;
 606
 607   for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
 608     if (!DT->dominates(BB, SUCC))
 609       return false;
 610   }
 611
 612   return true;
 613 }
 614
 615 // True if block has predecessors and it postdominates all of them.
 616 static bool isFullPostDominator(const BasicBlock *BB,
 617                                 const PostDominatorTree *PDT) {
 618   if (pred_begin(BB) == pred_end(BB))
 619     return false;
 620
 621   for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
 622     if (!PDT->dominates(BB, PRED))
 623       return false;
 624   }
 625
 626   return true;
 627 }
 628
 629 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
 630                                   const DominatorTree *DT,
 631                                   const PostDominatorTree *PDT,
 632                                   const SanitizerCoverageOptions &Options) {
 633   // Don't insert coverage for blocks containing nothing but unreachable: we
 634   // will never call __sanitizer_cov() for them, so counting them in
 635   // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
 636   // percentage. Also, unreachable instructions frequently have no debug
 637   // locations.
 638   if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime()))
 639     return false;
 640
 641   // Don't insert coverage into blocks without a valid insertion point
 642   // (catchswitch blocks).
 643   if (BB->getFirstInsertionPt() == BB->end())
 644     return false;
 645
 646   if (Options.NoPrune || &F.getEntryBlock() == BB)
 647     return true;
 648
 649   if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
 650       &F.getEntryBlock() != BB)
 651     return false;
 652
 653   // Do not instrument full dominators, or full post-dominators with multiple
 654   // predecessors.
 655   return !isFullDominator(BB, DT)
 656     && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
 657 }
 658
 659
 660 // Returns true iff From->To is a backedge.
 661 // A twist here is that we treat From->To as a backedge if
 662 //   * To dominates From or
 663 //   * To->UniqueSuccessor dominates From
 664 static bool IsBackEdge(BasicBlock *From, BasicBlock *To,
 665                        const DominatorTree *DT) {
 666   if (DT->dominates(To, From))
 667     return true;
 668   if (auto Next = To->getUniqueSuccessor())
 669     if (DT->dominates(Next, From))
 670       return true;
 671   return false;
 672 }
 673
 674 // Prunes uninteresting Cmp instrumentation:
 675 //   * CMP instructions that feed into loop backedge branch.
 676 //
 677 // Note that Cmp pruning is controlled by the same flag as the
 678 // BB pruning.
 679 static bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree *DT,
 680                              const SanitizerCoverageOptions &Options) {
 681   if (!Options.NoPrune)
 682     if (CMP->hasOneUse())
 683       if (auto BR = dyn_cast<BranchInst>(CMP->user_back()))
 684         for (BasicBlock *B : BR->successors())
 685           if (IsBackEdge(BR->getParent(), B, DT))
 686             return false;
 687   return true;
 688 }
 689
 690 bool SanitizerCoverage::instrumentFunction(Function &F, const DominatorTree *DT,
 691                                            const PostDominatorTree *PDT) {
 692   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
 693     return false;
 694   if (!canInstrumentWithSancov(F))
 695     return false;
 696   if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
 697     SplitAllCriticalEdges(F, CriticalEdgeSplittingOptions().setIgnoreUnreachableDests());
 698   SmallVector<Instruction *, 8> IndirCalls;
 699   SmallVector<BasicBlock *, 16> BlocksToInstrument;
 700   SmallVector<Instruction *, 8> CmpTraceTargets;
 701   SmallVector<Instruction *, 8> SwitchTraceTargets;
 702   SmallVector<BinaryOperator *, 8> DivTraceTargets;
 703   SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
 704
 705   bool IsLeafFunc = true;
 706
 707   for (auto &BB : F) {
 708     if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
 709       BlocksToInstrument.push_back(&BB);
 710     for (auto &Inst : BB) {
 711       if (Options.IndirectCalls) {
 712         CallSite CS(&Inst);
 713         if (CS && !CS.getCalledFunction())
 714           IndirCalls.push_back(&Inst);
 715       }
 716       if (Options.TraceCmp) {
 717         if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst))
 718           if (IsInterestingCmp(CMP, DT, Options))
 719             CmpTraceTargets.push_back(&Inst);
 720         if (isa<SwitchInst>(&Inst))
 721           SwitchTraceTargets.push_back(&Inst);
 722       }
 723       if (Options.TraceDiv)
 724         if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
 725           if (BO->getOpcode() == Instruction::SDiv ||
 726               BO->getOpcode() == Instruction::UDiv)
 727             DivTraceTargets.push_back(BO);
 728       if (Options.TraceGep)
 729         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
 730           GepTraceTargets.push_back(GEP);
 731       if (Options.StackDepth)
 732         if (isa<InvokeInst>(Inst) ||
 733             (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
 734           IsLeafFunc = false;
 735     }
 736   }
 737
 738   InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
 739   InjectCoverageForIndirectCalls(F, IndirCalls);
 740   InjectTraceForCmp(F, CmpTraceTargets);
 741   InjectTraceForSwitch(F, SwitchTraceTargets);
 742   InjectTraceForDiv(F, DivTraceTargets);
 743   InjectTraceForGep(F, GepTraceTargets);
 744   return true;
 745 }
 746
 747 GlobalVariable *SanitizerCoverage::CreateFunctionLocalArrayInSection(
 748     size_t NumElements, Function &F, Type *Ty, const char *Section) {
 749   ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
 750   auto Array = new GlobalVariable(
 751       *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
 752       Constant::getNullValue(ArrayTy), "__sancov_gen_");
 753
 754   if (TargetTriple.supportsCOMDAT() && !F.isInterposable())
 755     if (auto Comdat =
 756             GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId))
 757       Array->setComdat(Comdat);
 758   Array->setSection(getSectionName(Section));
 759   Array->setAlignment(Ty->isPointerTy() ? DL->getPointerSize()
 760                                         : Ty->getPrimitiveSizeInBits() / 8);
 761   GlobalsToAppendToUsed.push_back(Array);
 762   GlobalsToAppendToCompilerUsed.push_back(Array);
 763   MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
 764   Array->addMetadata(LLVMContext::MD_associated, *MD);
 765
 766   return Array;
 767 }
 768
 769 GlobalVariable *
 770 SanitizerCoverage::CreatePCArray(Function &F,
 771                                  ArrayRef<BasicBlock *> AllBlocks) {
 772   size_t N = AllBlocks.size();
 773   assert(N);
 774   SmallVector<Constant *, 32> PCs;
 775   IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
 776   for (size_t i = 0; i < N; i++) {
 777     if (&F.getEntryBlock() == AllBlocks[i]) {
 778       PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
 779       PCs.push_back((Constant *)IRB.CreateIntToPtr(
 780           ConstantInt::get(IntptrTy, 1), IntptrPtrTy));
 781     } else {
 782       PCs.push_back((Constant *)IRB.CreatePointerCast(
 783           BlockAddress::get(AllBlocks[i]), IntptrPtrTy));
 784       PCs.push_back((Constant *)IRB.CreateIntToPtr(
 785           ConstantInt::get(IntptrTy, 0), IntptrPtrTy));
 786     }
 787   }
 788   auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy,
 789                                                     SanCovPCsSectionName);
 790   PCArray->setInitializer(
 791       ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs));
 792   PCArray->setConstant(true);
 793
 794   return PCArray;
 795 }
 796
 797 void SanitizerCoverage::CreateFunctionLocalArrays(
 798     Function &F, ArrayRef<BasicBlock *> AllBlocks) {
 799   if (Options.TracePCGuard)
 800     FunctionGuardArray = CreateFunctionLocalArrayInSection(
 801         AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
 802
 803   if (Options.Inline8bitCounters)
 804     Function8bitCounterArray = CreateFunctionLocalArrayInSection(
 805         AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
 806
 807   if (Options.PCTable)
 808     FunctionPCsArray = CreatePCArray(F, AllBlocks);
 809 }
 810
 811 bool SanitizerCoverage::InjectCoverage(Function &F,
 812                                        ArrayRef<BasicBlock *> AllBlocks,
 813                                        bool IsLeafFunc) {
 814   if (AllBlocks.empty()) return false;
 815   CreateFunctionLocalArrays(F, AllBlocks);
 816   for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
 817     InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
 818   return true;
 819 }
 820
 821 // On every indirect call we call a run-time function
 822 // __sanitizer_cov_indir_call* with two parameters:
 823 //   - callee address,
 824 //   - global cache array that contains CacheSize pointers (zero-initialized).
 825 //     The cache is used to speed up recording the caller-callee pairs.
 826 // The address of the caller is passed implicitly via caller PC.
 827 // CacheSize is encoded in the name of the run-time function.
 828 void SanitizerCoverage::InjectCoverageForIndirectCalls(
 829     Function &F, ArrayRef<Instruction *> IndirCalls) {
 830   if (IndirCalls.empty())
 831     return;
 832   assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters);
 833   for (auto I : IndirCalls) {
 834     IRBuilder<> IRB(I);
 835     CallSite CS(I);
 836     Value *Callee = CS.getCalledValue();
 837     if (isa<InlineAsm>(Callee))
 838       continue;
 839     IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
 840   }
 841 }
 842
 843 // For every switch statement we insert a call:
 844 // __sanitizer_cov_trace_switch(CondValue,
 845 //      {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
 846
 847 void SanitizerCoverage::InjectTraceForSwitch(
 848     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
 849   for (auto I : SwitchTraceTargets) {
 850     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
 851       IRBuilder<> IRB(I);
 852       SmallVector<Constant *, 16> Initializers;
 853       Value *Cond = SI->getCondition();
 854       if (Cond->getType()->getScalarSizeInBits() >
 855           Int64Ty->getScalarSizeInBits())
 856         continue;
 857       Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
 858       Initializers.push_back(
 859           ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
 860       if (Cond->getType()->getScalarSizeInBits() <
 861           Int64Ty->getScalarSizeInBits())
 862         Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
 863       for (auto It : SI->cases()) {
 864         Constant *C = It.getCaseValue();
 865         if (C->getType()->getScalarSizeInBits() <
 866             Int64Ty->getScalarSizeInBits())
 867           C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
 868         Initializers.push_back(C);
 869       }
 870       llvm::sort(Initializers.begin() + 2, Initializers.end(),
 871                  [](const Constant *A, const Constant *B) {
 872                    return cast<ConstantInt>(A)->getLimitedValue() <
 873                           cast<ConstantInt>(B)->getLimitedValue();
 874                  });
 875       ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
 876       GlobalVariable *GV = new GlobalVariable(
 877           *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
 878           ConstantArray::get(ArrayOfInt64Ty, Initializers),
 879           "__sancov_gen_cov_switch_values");
 880       IRB.CreateCall(SanCovTraceSwitchFunction,
 881                      {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
 882     }
 883   }
 884 }
 885
 886 void SanitizerCoverage::InjectTraceForDiv(
 887     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
 888   for (auto BO : DivTraceTargets) {
 889     IRBuilder<> IRB(BO);
 890     Value *A1 = BO->getOperand(1);
 891     if (isa<ConstantInt>(A1)) continue;
 892     if (!A1->getType()->isIntegerTy())
 893       continue;
 894     uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
 895     int CallbackIdx = TypeSize == 32 ? 0 :
 896         TypeSize == 64 ? 1 : -1;
 897     if (CallbackIdx < 0) continue;
 898     auto Ty = Type::getIntNTy(*C, TypeSize);
 899     IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
 900                    {IRB.CreateIntCast(A1, Ty, true)});
 901   }
 902 }
 903
 904 void SanitizerCoverage::InjectTraceForGep(
 905     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
 906   for (auto GEP : GepTraceTargets) {
 907     IRBuilder<> IRB(GEP);
 908     for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
 909       if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy())
 910         IRB.CreateCall(SanCovTraceGepFunction,
 911                        {IRB.CreateIntCast(*I, IntptrTy, true)});
 912   }
 913 }
 914
 915 void SanitizerCoverage::InjectTraceForCmp(
 916     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
 917   for (auto I : CmpTraceTargets) {
 918     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
 919       IRBuilder<> IRB(ICMP);
 920       Value *A0 = ICMP->getOperand(0);
 921       Value *A1 = ICMP->getOperand(1);
 922       if (!A0->getType()->isIntegerTy())
 923         continue;
 924       uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
 925       int CallbackIdx = TypeSize == 8 ? 0 :
 926                         TypeSize == 16 ? 1 :
 927                         TypeSize == 32 ? 2 :
 928                         TypeSize == 64 ? 3 : -1;
 929       if (CallbackIdx < 0) continue;
 930       // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
 931       auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
 932       bool FirstIsConst = isa<ConstantInt>(A0);
 933       bool SecondIsConst = isa<ConstantInt>(A1);
 934       // If both are const, then we don't need such a comparison.
 935       if (FirstIsConst && SecondIsConst) continue;
 936       // If only one is const, then make it the first callback argument.
 937       if (FirstIsConst || SecondIsConst) {
 938         CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
 939         if (SecondIsConst)
 940           std::swap(A0, A1);
 941       }
 942
 943       auto Ty = Type::getIntNTy(*C, TypeSize);
 944       IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
 945               IRB.CreateIntCast(A1, Ty, true)});
 946     }
 947   }
 948 }
 949
 950 void SanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
 951                                               size_t Idx, bool IsLeafFunc) {
 952   BasicBlock::iterator IP = BB.getFirstInsertionPt();
 953   bool IsEntryBB = &BB == &F.getEntryBlock();
 954   DebugLoc EntryLoc;
 955   if (IsEntryBB) {
 956     if (auto SP = F.getSubprogram())
 957       EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
 958     // Keep static allocas and llvm.localescape calls in the entry block.  Even
 959     // if we aren't splitting the block, it's nice for allocas to be before
 960     // calls.
 961     IP = PrepareToSplitEntryBlock(BB, IP);
 962   } else {
 963     EntryLoc = IP->getDebugLoc();
 964   }
 965
 966   IRBuilder<> IRB(&*IP);
 967   IRB.SetCurrentDebugLocation(EntryLoc);
 968   if (Options.TracePC) {
 969     IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
 970     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
 971   }
 972   if (Options.TracePCGuard) {
 973     auto GuardPtr = IRB.CreateIntToPtr(
 974         IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
 975                       ConstantInt::get(IntptrTy, Idx * 4)),
 976         Int32PtrTy);
 977     IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
 978     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
 979   }
 980   if (Options.Inline8bitCounters) {
 981     auto CounterPtr = IRB.CreateGEP(
 982         Function8bitCounterArray->getValueType(), Function8bitCounterArray,
 983         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
 984     auto Load = IRB.CreateLoad(Int8Ty, CounterPtr);
 985     auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
 986     auto Store = IRB.CreateStore(Inc, CounterPtr);
 987     SetNoSanitizeMetadata(Load);
 988     SetNoSanitizeMetadata(Store);
 989   }
 990   if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
 991     // Check stack depth.  If it's the deepest so far, record it.
 992     Module *M = F.getParent();
 993     Function *GetFrameAddr = Intrinsic::getDeclaration(
 994         M, Intrinsic::frameaddress,
 995         IRB.getInt8PtrTy(M->getDataLayout().getAllocaAddrSpace()));
 996     auto FrameAddrPtr =
 997         IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
 998     auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
 999     auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack);
1000     auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
1001     auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false);
1002     IRBuilder<> ThenIRB(ThenTerm);
1003     auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
1004     SetNoSanitizeMetadata(LowestStack);
1005     SetNoSanitizeMetadata(Store);
1006   }
1007 }
1008
1009 std::string
1010 SanitizerCoverage::getSectionName(const std::string &Section) const {
1011   if (TargetTriple.isOSBinFormatCOFF()) {
1012     if (Section == SanCovCountersSectionName)
1013       return ".SCOV$CM";
1014     if (Section == SanCovPCsSectionName)
1015       return ".SCOVP$M";
1016     return ".SCOV$GM"; // For SanCovGuardsSectionName.
1017   }
1018   if (TargetTriple.isOSBinFormatMachO())
1019     return "__DATA,__" + Section;
1020   return "__" + Section;
1021 }
1022
1023 std::string
1024 SanitizerCoverage::getSectionStart(const std::string &Section) const {
1025   return getSectionStartImpl(TargetTriple, Section);
1026 }
1027
1028 std::string SanitizerCoverage::getSectionEnd(const std::string &Section) const {
1029   return getSectionEndImpl(TargetTriple, Section);
1030 }
1031
1032 INITIALIZE_PASS(ModuleSanitizerCoverageLegacyPass, "module-sancov",
1033                 "Pass for inserting sancov top-level initialization calls",
1034                 false, false)
1035
1036 char SanitizerCoverageLegacyPass::ID = 0;
1037 INITIALIZE_PASS_BEGIN(SanitizerCoverageLegacyPass, "sancov",
1038                       "Pass for instrumenting coverage on functions", false,
1039                       false)
1040 INITIALIZE_PASS_DEPENDENCY(ModuleSanitizerCoverageLegacyPass)
1041 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
1042 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
1043 INITIALIZE_PASS_END(SanitizerCoverageLegacyPass, "sancov",
1044                     "Pass for instrumenting coverage on functions", false,
1045                     false)
1046 FunctionPass *llvm::createSanitizerCoverageLegacyPassPass(
1047     const SanitizerCoverageOptions &Options) {
1048   return new SanitizerCoverageLegacyPass(Options);
1049 }
1050 ModulePass *llvm::createModuleSanitizerCoverageLegacyPassPass(
1051     const SanitizerCoverageOptions &Options) {
1052   return new ModuleSanitizerCoverageLegacyPass(Options);
1053 }