contrib/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp

   1 //===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // Coverage instrumentation done on LLVM IR level, works with Sanitizers.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  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 SanCovModuleCtorName = "sancov.module_ctor";
  66 static const uint64_t SanCtorAndDtorPriority = 2;
  67
  68 static const char *const SanCovTracePCGuardName =
  69     "__sanitizer_cov_trace_pc_guard";
  70 static const char *const SanCovTracePCGuardInitName =
  71     "__sanitizer_cov_trace_pc_guard_init";
  72 static const char *const SanCov8bitCountersInitName =
  73     "__sanitizer_cov_8bit_counters_init";
  74 static const char *const SanCovPCsInitName = "__sanitizer_cov_pcs_init";
  75
  76 static const char *const SanCovGuardsSectionName = "sancov_guards";
  77 static const char *const SanCovCountersSectionName = "sancov_cntrs";
  78 static const char *const SanCovPCsSectionName = "sancov_pcs";
  79
  80 static const char *const SanCovLowestStackName = "__sancov_lowest_stack";
  81
  82 static cl::opt<int> ClCoverageLevel(
  83     "sanitizer-coverage-level",
  84     cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
  85              "3: all blocks and critical edges"),
  86     cl::Hidden, cl::init(0));
  87
  88 static cl::opt<bool> ClTracePC("sanitizer-coverage-trace-pc",
  89                                cl::desc("Experimental pc tracing"), cl::Hidden,
  90                                cl::init(false));
  91
  92 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard",
  93                                     cl::desc("pc tracing with a guard"),
  94                                     cl::Hidden, cl::init(false));
  95
  96 // If true, we create a global variable that contains PCs of all instrumented
  97 // BBs, put this global into a named section, and pass this section's bounds
  98 // to __sanitizer_cov_pcs_init.
  99 // This way the coverage instrumentation does not need to acquire the PCs
 100 // at run-time. Works with trace-pc-guard and inline-8bit-counters.
 101 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table",
 102                                      cl::desc("create a static PC table"),
 103                                      cl::Hidden, cl::init(false));
 104
 105 static cl::opt<bool>
 106     ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters",
 107                          cl::desc("increments 8-bit counter for every edge"),
 108                          cl::Hidden, cl::init(false));
 109
 110 static cl::opt<bool>
 111     ClCMPTracing("sanitizer-coverage-trace-compares",
 112                  cl::desc("Tracing of CMP and similar instructions"),
 113                  cl::Hidden, cl::init(false));
 114
 115 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs",
 116                                   cl::desc("Tracing of DIV instructions"),
 117                                   cl::Hidden, cl::init(false));
 118
 119 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps",
 120                                   cl::desc("Tracing of GEP instructions"),
 121                                   cl::Hidden, cl::init(false));
 122
 123 static cl::opt<bool>
 124     ClPruneBlocks("sanitizer-coverage-prune-blocks",
 125                   cl::desc("Reduce the number of instrumented blocks"),
 126                   cl::Hidden, cl::init(true));
 127
 128 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth",
 129                                   cl::desc("max stack depth tracing"),
 130                                   cl::Hidden, cl::init(false));
 131
 132 namespace {
 133
 134 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
 135   SanitizerCoverageOptions Res;
 136   switch (LegacyCoverageLevel) {
 137   case 0:
 138     Res.CoverageType = SanitizerCoverageOptions::SCK_None;
 139     break;
 140   case 1:
 141     Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
 142     break;
 143   case 2:
 144     Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
 145     break;
 146   case 3:
 147     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
 148     break;
 149   case 4:
 150     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
 151     Res.IndirectCalls = true;
 152     break;
 153   }
 154   return Res;
 155 }
 156
 157 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
 158   // Sets CoverageType and IndirectCalls.
 159   SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
 160   Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
 161   Options.IndirectCalls |= CLOpts.IndirectCalls;
 162   Options.TraceCmp |= ClCMPTracing;
 163   Options.TraceDiv |= ClDIVTracing;
 164   Options.TraceGep |= ClGEPTracing;
 165   Options.TracePC |= ClTracePC;
 166   Options.TracePCGuard |= ClTracePCGuard;
 167   Options.Inline8bitCounters |= ClInline8bitCounters;
 168   Options.PCTable |= ClCreatePCTable;
 169   Options.NoPrune |= !ClPruneBlocks;
 170   Options.StackDepth |= ClStackDepth;
 171   if (!Options.TracePCGuard && !Options.TracePC &&
 172       !Options.Inline8bitCounters && !Options.StackDepth)
 173     Options.TracePCGuard = true; // TracePCGuard is default.
 174   return Options;
 175 }
 176
 177 class SanitizerCoverageModule : public ModulePass {
 178 public:
 179   SanitizerCoverageModule(
 180       const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
 181       : ModulePass(ID), Options(OverrideFromCL(Options)) {
 182     initializeSanitizerCoverageModulePass(*PassRegistry::getPassRegistry());
 183   }
 184   bool runOnModule(Module &M) override;
 185   bool runOnFunction(Function &F);
 186   static char ID; // Pass identification, replacement for typeid
 187   StringRef getPassName() const override { return "SanitizerCoverageModule"; }
 188
 189   void getAnalysisUsage(AnalysisUsage &AU) const override {
 190     AU.addRequired<DominatorTreeWrapperPass>();
 191     AU.addRequired<PostDominatorTreeWrapperPass>();
 192   }
 193
 194 private:
 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 *InitFunctionName,
 214                                        Type *Ty, const char *Section);
 215   std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section,
 216                                                 Type *Ty);
 217
 218   void SetNoSanitizeMetadata(Instruction *I) {
 219     I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
 220                    MDNode::get(*C, None));
 221   }
 222
 223   std::string getSectionName(const std::string &Section) const;
 224   std::string getSectionStart(const std::string &Section) const;
 225   std::string getSectionEnd(const std::string &Section) const;
 226   Function *SanCovTracePCIndir;
 227   Function *SanCovTracePC, *SanCovTracePCGuard;
 228   Function *SanCovTraceCmpFunction[4];
 229   Function *SanCovTraceConstCmpFunction[4];
 230   Function *SanCovTraceDivFunction[2];
 231   Function *SanCovTraceGepFunction;
 232   Function *SanCovTraceSwitchFunction;
 233   GlobalVariable *SanCovLowestStack;
 234   InlineAsm *EmptyAsm;
 235   Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy,
 236       *Int16Ty, *Int8Ty, *Int8PtrTy;
 237   Module *CurModule;
 238   std::string CurModuleUniqueId;
 239   Triple TargetTriple;
 240   LLVMContext *C;
 241   const DataLayout *DL;
 242
 243   GlobalVariable *FunctionGuardArray;  // for trace-pc-guard.
 244   GlobalVariable *Function8bitCounterArray;  // for inline-8bit-counters.
 245   GlobalVariable *FunctionPCsArray;  // for pc-table.
 246   SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
 247   SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
 248
 249   SanitizerCoverageOptions Options;
 250 };
 251
 252 } // namespace
 253
 254 std::pair<Value *, Value *>
 255 SanitizerCoverageModule::CreateSecStartEnd(Module &M, const char *Section,
 256                                            Type *Ty) {
 257   GlobalVariable *SecStart =
 258       new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr,
 259                          getSectionStart(Section));
 260   SecStart->setVisibility(GlobalValue::HiddenVisibility);
 261   GlobalVariable *SecEnd =
 262       new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage,
 263                          nullptr, getSectionEnd(Section));
 264   SecEnd->setVisibility(GlobalValue::HiddenVisibility);
 265   IRBuilder<> IRB(M.getContext());
 266   Value *SecEndPtr = IRB.CreatePointerCast(SecEnd, Ty);
 267   if (!TargetTriple.isOSBinFormatCOFF())
 268     return std::make_pair(IRB.CreatePointerCast(SecStart, Ty), SecEndPtr);
 269
 270   // Account for the fact that on windows-msvc __start_* symbols actually
 271   // point to a uint64_t before the start of the array.
 272   auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy);
 273   auto GEP = IRB.CreateGEP(SecStartI8Ptr,
 274                            ConstantInt::get(IntptrTy, sizeof(uint64_t)));
 275   return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEndPtr);
 276 }
 277
 278 Function *SanitizerCoverageModule::CreateInitCallsForSections(
 279     Module &M, const char *InitFunctionName, Type *Ty,
 280     const char *Section) {
 281   auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
 282   auto SecStart = SecStartEnd.first;
 283   auto SecEnd = SecStartEnd.second;
 284   Function *CtorFunc;
 285   std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
 286       M, SanCovModuleCtorName, InitFunctionName, {Ty, Ty}, {SecStart, SecEnd});
 287
 288   if (TargetTriple.supportsCOMDAT()) {
 289     // Use comdat to dedup CtorFunc.
 290     CtorFunc->setComdat(M.getOrInsertComdat(SanCovModuleCtorName));
 291     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
 292   } else {
 293     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
 294   }
 295
 296   if (TargetTriple.isOSBinFormatCOFF()) {
 297     // In COFF files, if the contructors are set as COMDAT (they are because
 298     // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
 299     // functions and data) is used, the constructors get stripped. To prevent
 300     // this, give the constructors weak ODR linkage and ensure the linker knows
 301     // to include the sancov constructor. This way the linker can deduplicate
 302     // the constructors but always leave one copy.
 303     CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
 304     appendToUsed(M, CtorFunc);
 305   }
 306   return CtorFunc;
 307 }
 308
 309 bool SanitizerCoverageModule::runOnModule(Module &M) {
 310   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
 311     return false;
 312   C = &(M.getContext());
 313   DL = &M.getDataLayout();
 314   CurModule = &M;
 315   CurModuleUniqueId = getUniqueModuleId(CurModule);
 316   TargetTriple = Triple(M.getTargetTriple());
 317   FunctionGuardArray = nullptr;
 318   Function8bitCounterArray = nullptr;
 319   FunctionPCsArray = nullptr;
 320   IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
 321   IntptrPtrTy = PointerType::getUnqual(IntptrTy);
 322   Type *VoidTy = Type::getVoidTy(*C);
 323   IRBuilder<> IRB(*C);
 324   Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
 325   Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
 326   Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
 327   Int64Ty = IRB.getInt64Ty();
 328   Int32Ty = IRB.getInt32Ty();
 329   Int16Ty = IRB.getInt16Ty();
 330   Int8Ty = IRB.getInt8Ty();
 331
 332   SanCovTracePCIndir = checkSanitizerInterfaceFunction(
 333       M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy));
 334   SanCovTraceCmpFunction[0] =
 335       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 336           SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty()));
 337   SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction(
 338       M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(),
 339                             IRB.getInt16Ty()));
 340   SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction(
 341       M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(),
 342                             IRB.getInt32Ty()));
 343   SanCovTraceCmpFunction[3] =
 344       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 345           SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty));
 346
 347   SanCovTraceConstCmpFunction[0] =
 348       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 349           SanCovTraceConstCmp1, VoidTy, Int8Ty, Int8Ty));
 350   SanCovTraceConstCmpFunction[1] =
 351       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 352           SanCovTraceConstCmp2, VoidTy, Int16Ty, Int16Ty));
 353   SanCovTraceConstCmpFunction[2] =
 354       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 355           SanCovTraceConstCmp4, VoidTy, Int32Ty, Int32Ty));
 356   SanCovTraceConstCmpFunction[3] =
 357       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 358           SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty));
 359
 360   SanCovTraceDivFunction[0] =
 361       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 362           SanCovTraceDiv4, VoidTy, IRB.getInt32Ty()));
 363   SanCovTraceDivFunction[1] =
 364       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 365           SanCovTraceDiv8, VoidTy, Int64Ty));
 366   SanCovTraceGepFunction =
 367       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 368           SanCovTraceGep, VoidTy, IntptrTy));
 369   SanCovTraceSwitchFunction =
 370       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 371           SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy));
 372
 373   Constant *SanCovLowestStackConstant =
 374       M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
 375   SanCovLowestStack = cast<GlobalVariable>(SanCovLowestStackConstant);
 376   SanCovLowestStack->setThreadLocalMode(
 377       GlobalValue::ThreadLocalMode::InitialExecTLSModel);
 378   if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
 379     SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
 380
 381   // Make sure smaller parameters are zero-extended to i64 as required by the
 382   // x86_64 ABI.
 383   if (TargetTriple.getArch() == Triple::x86_64) {
 384     for (int i = 0; i < 3; i++) {
 385       SanCovTraceCmpFunction[i]->addParamAttr(0, Attribute::ZExt);
 386       SanCovTraceCmpFunction[i]->addParamAttr(1, Attribute::ZExt);
 387       SanCovTraceConstCmpFunction[i]->addParamAttr(0, Attribute::ZExt);
 388       SanCovTraceConstCmpFunction[i]->addParamAttr(1, Attribute::ZExt);
 389     }
 390     SanCovTraceDivFunction[0]->addParamAttr(0, Attribute::ZExt);
 391   }
 392
 393
 394   // We insert an empty inline asm after cov callbacks to avoid callback merge.
 395   EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
 396                             StringRef(""), StringRef(""),
 397                             /*hasSideEffects=*/true);
 398
 399   SanCovTracePC = checkSanitizerInterfaceFunction(
 400       M.getOrInsertFunction(SanCovTracePCName, VoidTy));
 401   SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
 402       SanCovTracePCGuardName, VoidTy, Int32PtrTy));
 403
 404   for (auto &F : M)
 405     runOnFunction(F);
 406
 407   Function *Ctor = nullptr;
 408
 409   if (FunctionGuardArray)
 410     Ctor = CreateInitCallsForSections(M, SanCovTracePCGuardInitName, Int32PtrTy,
 411                                       SanCovGuardsSectionName);
 412   if (Function8bitCounterArray)
 413     Ctor = CreateInitCallsForSections(M, SanCov8bitCountersInitName, Int8PtrTy,
 414                                       SanCovCountersSectionName);
 415   if (Ctor && Options.PCTable) {
 416     auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy);
 417     Function *InitFunction = declareSanitizerInitFunction(
 418         M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy});
 419     IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
 420     IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
 421   }
 422   // We don't reference these arrays directly in any of our runtime functions,
 423   // so we need to prevent them from being dead stripped.
 424   if (TargetTriple.isOSBinFormatMachO())
 425     appendToUsed(M, GlobalsToAppendToUsed);
 426   appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
 427   return true;
 428 }
 429
 430 // True if block has successors and it dominates all of them.
 431 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
 432   if (succ_begin(BB) == succ_end(BB))
 433     return false;
 434
 435   for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
 436     if (!DT->dominates(BB, SUCC))
 437       return false;
 438   }
 439
 440   return true;
 441 }
 442
 443 // True if block has predecessors and it postdominates all of them.
 444 static bool isFullPostDominator(const BasicBlock *BB,
 445                                 const PostDominatorTree *PDT) {
 446   if (pred_begin(BB) == pred_end(BB))
 447     return false;
 448
 449   for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
 450     if (!PDT->dominates(BB, PRED))
 451       return false;
 452   }
 453
 454   return true;
 455 }
 456
 457 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
 458                                   const DominatorTree *DT,
 459                                   const PostDominatorTree *PDT,
 460                                   const SanitizerCoverageOptions &Options) {
 461   // Don't insert coverage for unreachable blocks: we will never call
 462   // __sanitizer_cov() for them, so counting them in
 463   // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
 464   // percentage. Also, unreachable instructions frequently have no debug
 465   // locations.
 466   if (isa<UnreachableInst>(BB->getTerminator()))
 467     return false;
 468
 469   // Don't insert coverage into blocks without a valid insertion point
 470   // (catchswitch blocks).
 471   if (BB->getFirstInsertionPt() == BB->end())
 472     return false;
 473
 474   if (Options.NoPrune || &F.getEntryBlock() == BB)
 475     return true;
 476
 477   if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
 478       &F.getEntryBlock() != BB)
 479     return false;
 480
 481   // Do not instrument full dominators, or full post-dominators with multiple
 482   // predecessors.
 483   return !isFullDominator(BB, DT)
 484     && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
 485 }
 486
 487 bool SanitizerCoverageModule::runOnFunction(Function &F) {
 488   if (F.empty())
 489     return false;
 490   if (F.getName().find(".module_ctor") != std::string::npos)
 491     return false; // Should not instrument sanitizer init functions.
 492   if (F.getName().startswith("__sanitizer_"))
 493     return false;  // Don't instrument __sanitizer_* callbacks.
 494   // Don't touch available_externally functions, their actual body is elewhere.
 495   if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
 496     return false;
 497   // Don't instrument MSVC CRT configuration helpers. They may run before normal
 498   // initialization.
 499   if (F.getName() == "__local_stdio_printf_options" ||
 500       F.getName() == "__local_stdio_scanf_options")
 501     return false;
 502   if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
 503     return false;
 504   // Don't instrument functions using SEH for now. Splitting basic blocks like
 505   // we do for coverage breaks WinEHPrepare.
 506   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
 507   if (F.hasPersonalityFn() &&
 508       isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
 509     return false;
 510   if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
 511     SplitAllCriticalEdges(F);
 512   SmallVector<Instruction *, 8> IndirCalls;
 513   SmallVector<BasicBlock *, 16> BlocksToInstrument;
 514   SmallVector<Instruction *, 8> CmpTraceTargets;
 515   SmallVector<Instruction *, 8> SwitchTraceTargets;
 516   SmallVector<BinaryOperator *, 8> DivTraceTargets;
 517   SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
 518
 519   const DominatorTree *DT =
 520       &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
 521   const PostDominatorTree *PDT =
 522       &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree();
 523   bool IsLeafFunc = true;
 524
 525   for (auto &BB : F) {
 526     if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
 527       BlocksToInstrument.push_back(&BB);
 528     for (auto &Inst : BB) {
 529       if (Options.IndirectCalls) {
 530         CallSite CS(&Inst);
 531         if (CS && !CS.getCalledFunction())
 532           IndirCalls.push_back(&Inst);
 533       }
 534       if (Options.TraceCmp) {
 535         if (isa<ICmpInst>(&Inst))
 536           CmpTraceTargets.push_back(&Inst);
 537         if (isa<SwitchInst>(&Inst))
 538           SwitchTraceTargets.push_back(&Inst);
 539       }
 540       if (Options.TraceDiv)
 541         if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
 542           if (BO->getOpcode() == Instruction::SDiv ||
 543               BO->getOpcode() == Instruction::UDiv)
 544             DivTraceTargets.push_back(BO);
 545       if (Options.TraceGep)
 546         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
 547           GepTraceTargets.push_back(GEP);
 548       if (Options.StackDepth)
 549         if (isa<InvokeInst>(Inst) ||
 550             (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
 551           IsLeafFunc = false;
 552     }
 553   }
 554
 555   InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
 556   InjectCoverageForIndirectCalls(F, IndirCalls);
 557   InjectTraceForCmp(F, CmpTraceTargets);
 558   InjectTraceForSwitch(F, SwitchTraceTargets);
 559   InjectTraceForDiv(F, DivTraceTargets);
 560   InjectTraceForGep(F, GepTraceTargets);
 561   return true;
 562 }
 563
 564 GlobalVariable *SanitizerCoverageModule::CreateFunctionLocalArrayInSection(
 565     size_t NumElements, Function &F, Type *Ty, const char *Section) {
 566   ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
 567   auto Array = new GlobalVariable(
 568       *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
 569       Constant::getNullValue(ArrayTy), "__sancov_gen_");
 570
 571   if (TargetTriple.supportsCOMDAT() && !F.isInterposable())
 572     if (auto Comdat =
 573             GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId))
 574       Array->setComdat(Comdat);
 575   Array->setSection(getSectionName(Section));
 576   Array->setAlignment(Ty->isPointerTy() ? DL->getPointerSize()
 577                                         : Ty->getPrimitiveSizeInBits() / 8);
 578   GlobalsToAppendToUsed.push_back(Array);
 579   GlobalsToAppendToCompilerUsed.push_back(Array);
 580   MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
 581   Array->addMetadata(LLVMContext::MD_associated, *MD);
 582
 583   return Array;
 584 }
 585
 586 GlobalVariable *
 587 SanitizerCoverageModule::CreatePCArray(Function &F,
 588                                        ArrayRef<BasicBlock *> AllBlocks) {
 589   size_t N = AllBlocks.size();
 590   assert(N);
 591   SmallVector<Constant *, 32> PCs;
 592   IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
 593   for (size_t i = 0; i < N; i++) {
 594     if (&F.getEntryBlock() == AllBlocks[i]) {
 595       PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
 596       PCs.push_back((Constant *)IRB.CreateIntToPtr(
 597           ConstantInt::get(IntptrTy, 1), IntptrPtrTy));
 598     } else {
 599       PCs.push_back((Constant *)IRB.CreatePointerCast(
 600           BlockAddress::get(AllBlocks[i]), IntptrPtrTy));
 601       PCs.push_back((Constant *)IRB.CreateIntToPtr(
 602           ConstantInt::get(IntptrTy, 0), IntptrPtrTy));
 603     }
 604   }
 605   auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy,
 606                                                     SanCovPCsSectionName);
 607   PCArray->setInitializer(
 608       ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs));
 609   PCArray->setConstant(true);
 610
 611   return PCArray;
 612 }
 613
 614 void SanitizerCoverageModule::CreateFunctionLocalArrays(
 615     Function &F, ArrayRef<BasicBlock *> AllBlocks) {
 616   if (Options.TracePCGuard)
 617     FunctionGuardArray = CreateFunctionLocalArrayInSection(
 618         AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
 619
 620   if (Options.Inline8bitCounters)
 621     Function8bitCounterArray = CreateFunctionLocalArrayInSection(
 622         AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
 623
 624   if (Options.PCTable)
 625     FunctionPCsArray = CreatePCArray(F, AllBlocks);
 626 }
 627
 628 bool SanitizerCoverageModule::InjectCoverage(Function &F,
 629                                              ArrayRef<BasicBlock *> AllBlocks,
 630                                              bool IsLeafFunc) {
 631   if (AllBlocks.empty()) return false;
 632   CreateFunctionLocalArrays(F, AllBlocks);
 633   for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
 634     InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
 635   return true;
 636 }
 637
 638 // On every indirect call we call a run-time function
 639 // __sanitizer_cov_indir_call* with two parameters:
 640 //   - callee address,
 641 //   - global cache array that contains CacheSize pointers (zero-initialized).
 642 //     The cache is used to speed up recording the caller-callee pairs.
 643 // The address of the caller is passed implicitly via caller PC.
 644 // CacheSize is encoded in the name of the run-time function.
 645 void SanitizerCoverageModule::InjectCoverageForIndirectCalls(
 646     Function &F, ArrayRef<Instruction *> IndirCalls) {
 647   if (IndirCalls.empty())
 648     return;
 649   assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters);
 650   for (auto I : IndirCalls) {
 651     IRBuilder<> IRB(I);
 652     CallSite CS(I);
 653     Value *Callee = CS.getCalledValue();
 654     if (isa<InlineAsm>(Callee))
 655       continue;
 656     IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
 657   }
 658 }
 659
 660 // For every switch statement we insert a call:
 661 // __sanitizer_cov_trace_switch(CondValue,
 662 //      {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
 663
 664 void SanitizerCoverageModule::InjectTraceForSwitch(
 665     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
 666   for (auto I : SwitchTraceTargets) {
 667     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
 668       IRBuilder<> IRB(I);
 669       SmallVector<Constant *, 16> Initializers;
 670       Value *Cond = SI->getCondition();
 671       if (Cond->getType()->getScalarSizeInBits() >
 672           Int64Ty->getScalarSizeInBits())
 673         continue;
 674       Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
 675       Initializers.push_back(
 676           ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
 677       if (Cond->getType()->getScalarSizeInBits() <
 678           Int64Ty->getScalarSizeInBits())
 679         Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
 680       for (auto It : SI->cases()) {
 681         Constant *C = It.getCaseValue();
 682         if (C->getType()->getScalarSizeInBits() <
 683             Int64Ty->getScalarSizeInBits())
 684           C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
 685         Initializers.push_back(C);
 686       }
 687       llvm::sort(Initializers.begin() + 2, Initializers.end(),
 688                  [](const Constant *A, const Constant *B) {
 689                    return cast<ConstantInt>(A)->getLimitedValue() <
 690                           cast<ConstantInt>(B)->getLimitedValue();
 691                  });
 692       ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
 693       GlobalVariable *GV = new GlobalVariable(
 694           *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
 695           ConstantArray::get(ArrayOfInt64Ty, Initializers),
 696           "__sancov_gen_cov_switch_values");
 697       IRB.CreateCall(SanCovTraceSwitchFunction,
 698                      {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
 699     }
 700   }
 701 }
 702
 703 void SanitizerCoverageModule::InjectTraceForDiv(
 704     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
 705   for (auto BO : DivTraceTargets) {
 706     IRBuilder<> IRB(BO);
 707     Value *A1 = BO->getOperand(1);
 708     if (isa<ConstantInt>(A1)) continue;
 709     if (!A1->getType()->isIntegerTy())
 710       continue;
 711     uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
 712     int CallbackIdx = TypeSize == 32 ? 0 :
 713         TypeSize == 64 ? 1 : -1;
 714     if (CallbackIdx < 0) continue;
 715     auto Ty = Type::getIntNTy(*C, TypeSize);
 716     IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
 717                    {IRB.CreateIntCast(A1, Ty, true)});
 718   }
 719 }
 720
 721 void SanitizerCoverageModule::InjectTraceForGep(
 722     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
 723   for (auto GEP : GepTraceTargets) {
 724     IRBuilder<> IRB(GEP);
 725     for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
 726       if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy())
 727         IRB.CreateCall(SanCovTraceGepFunction,
 728                        {IRB.CreateIntCast(*I, IntptrTy, true)});
 729   }
 730 }
 731
 732 void SanitizerCoverageModule::InjectTraceForCmp(
 733     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
 734   for (auto I : CmpTraceTargets) {
 735     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
 736       IRBuilder<> IRB(ICMP);
 737       Value *A0 = ICMP->getOperand(0);
 738       Value *A1 = ICMP->getOperand(1);
 739       if (!A0->getType()->isIntegerTy())
 740         continue;
 741       uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
 742       int CallbackIdx = TypeSize == 8 ? 0 :
 743                         TypeSize == 16 ? 1 :
 744                         TypeSize == 32 ? 2 :
 745                         TypeSize == 64 ? 3 : -1;
 746       if (CallbackIdx < 0) continue;
 747       // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
 748       auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
 749       bool FirstIsConst = isa<ConstantInt>(A0);
 750       bool SecondIsConst = isa<ConstantInt>(A1);
 751       // If both are const, then we don't need such a comparison.
 752       if (FirstIsConst && SecondIsConst) continue;
 753       // If only one is const, then make it the first callback argument.
 754       if (FirstIsConst || SecondIsConst) {
 755         CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
 756         if (SecondIsConst)
 757           std::swap(A0, A1);
 758       }
 759
 760       auto Ty = Type::getIntNTy(*C, TypeSize);
 761       IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
 762               IRB.CreateIntCast(A1, Ty, true)});
 763     }
 764   }
 765 }
 766
 767 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
 768                                                     size_t Idx,
 769                                                     bool IsLeafFunc) {
 770   BasicBlock::iterator IP = BB.getFirstInsertionPt();
 771   bool IsEntryBB = &BB == &F.getEntryBlock();
 772   DebugLoc EntryLoc;
 773   if (IsEntryBB) {
 774     if (auto SP = F.getSubprogram())
 775       EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
 776     // Keep static allocas and llvm.localescape calls in the entry block.  Even
 777     // if we aren't splitting the block, it's nice for allocas to be before
 778     // calls.
 779     IP = PrepareToSplitEntryBlock(BB, IP);
 780   } else {
 781     EntryLoc = IP->getDebugLoc();
 782   }
 783
 784   IRBuilder<> IRB(&*IP);
 785   IRB.SetCurrentDebugLocation(EntryLoc);
 786   if (Options.TracePC) {
 787     IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
 788     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
 789   }
 790   if (Options.TracePCGuard) {
 791     auto GuardPtr = IRB.CreateIntToPtr(
 792         IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
 793                       ConstantInt::get(IntptrTy, Idx * 4)),
 794         Int32PtrTy);
 795     IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
 796     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
 797   }
 798   if (Options.Inline8bitCounters) {
 799     auto CounterPtr = IRB.CreateGEP(
 800         Function8bitCounterArray,
 801         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
 802     auto Load = IRB.CreateLoad(CounterPtr);
 803     auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
 804     auto Store = IRB.CreateStore(Inc, CounterPtr);
 805     SetNoSanitizeMetadata(Load);
 806     SetNoSanitizeMetadata(Store);
 807   }
 808   if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
 809     // Check stack depth.  If it's the deepest so far, record it.
 810     Function *GetFrameAddr =
 811         Intrinsic::getDeclaration(F.getParent(), Intrinsic::frameaddress);
 812     auto FrameAddrPtr =
 813         IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
 814     auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
 815     auto LowestStack = IRB.CreateLoad(SanCovLowestStack);
 816     auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
 817     auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false);
 818     IRBuilder<> ThenIRB(ThenTerm);
 819     auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
 820     SetNoSanitizeMetadata(LowestStack);
 821     SetNoSanitizeMetadata(Store);
 822   }
 823 }
 824
 825 std::string
 826 SanitizerCoverageModule::getSectionName(const std::string &Section) const {
 827   if (TargetTriple.isOSBinFormatCOFF()) {
 828     if (Section == SanCovCountersSectionName)
 829       return ".SCOV$CM";
 830     if (Section == SanCovPCsSectionName)
 831       return ".SCOVP$M";
 832     return ".SCOV$GM"; // For SanCovGuardsSectionName.
 833   }
 834   if (TargetTriple.isOSBinFormatMachO())
 835     return "__DATA,__" + Section;
 836   return "__" + Section;
 837 }
 838
 839 std::string
 840 SanitizerCoverageModule::getSectionStart(const std::string &Section) const {
 841   if (TargetTriple.isOSBinFormatMachO())
 842     return "\1section$start$__DATA$__" + Section;
 843   return "__start___" + Section;
 844 }
 845
 846 std::string
 847 SanitizerCoverageModule::getSectionEnd(const std::string &Section) const {
 848   if (TargetTriple.isOSBinFormatMachO())
 849     return "\1section$end$__DATA$__" + Section;
 850   return "__stop___" + Section;
 851 }
 852
 853
 854 char SanitizerCoverageModule::ID = 0;
 855 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov",
 856                       "SanitizerCoverage: TODO."
 857                       "ModulePass",
 858                       false, false)
 859 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 860 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
 861 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov",
 862                     "SanitizerCoverage: TODO."
 863                     "ModulePass",
 864                     false, false)
 865 ModulePass *llvm::createSanitizerCoverageModulePass(
 866     const SanitizerCoverageOptions &Options) {
 867   return new SanitizerCoverageModule(Options);
 868 }