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/Constant.h"
20 #include "llvm/IR/DataLayout.h"
21 #include "llvm/IR/DebugInfo.h"
22 #include "llvm/IR/Dominators.h"
23 #include "llvm/IR/Function.h"
24 #include "llvm/IR/GlobalVariable.h"
25 #include "llvm/IR/IRBuilder.h"
26 #include "llvm/IR/InlineAsm.h"
27 #include "llvm/IR/IntrinsicInst.h"
28 #include "llvm/IR/Intrinsics.h"
29 #include "llvm/IR/LLVMContext.h"
30 #include "llvm/IR/MDBuilder.h"
31 #include "llvm/IR/Mangler.h"
32 #include "llvm/IR/Module.h"
33 #include "llvm/IR/Type.h"
34 #include "llvm/InitializePasses.h"
35 #include "llvm/Support/CommandLine.h"
36 #include "llvm/Support/Debug.h"
37 #include "llvm/Support/SpecialCaseList.h"
38 #include "llvm/Support/VirtualFileSystem.h"
39 #include "llvm/Support/raw_ostream.h"
40 #include "llvm/Transforms/Instrumentation.h"
41 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
42 #include "llvm/Transforms/Utils/ModuleUtils.h"
43 
44 using namespace llvm;
45 
46 #define DEBUG_TYPE "sancov"
47 
48 const char SanCovTracePCIndirName[] = "__sanitizer_cov_trace_pc_indir";
49 const char SanCovTracePCName[] = "__sanitizer_cov_trace_pc";
50 const char SanCovTraceCmp1[] = "__sanitizer_cov_trace_cmp1";
51 const char SanCovTraceCmp2[] = "__sanitizer_cov_trace_cmp2";
52 const char SanCovTraceCmp4[] = "__sanitizer_cov_trace_cmp4";
53 const char SanCovTraceCmp8[] = "__sanitizer_cov_trace_cmp8";
54 const char SanCovTraceConstCmp1[] = "__sanitizer_cov_trace_const_cmp1";
55 const char SanCovTraceConstCmp2[] = "__sanitizer_cov_trace_const_cmp2";
56 const char SanCovTraceConstCmp4[] = "__sanitizer_cov_trace_const_cmp4";
57 const char SanCovTraceConstCmp8[] = "__sanitizer_cov_trace_const_cmp8";
58 const char SanCovTraceDiv4[] = "__sanitizer_cov_trace_div4";
59 const char SanCovTraceDiv8[] = "__sanitizer_cov_trace_div8";
60 const char SanCovTraceGep[] = "__sanitizer_cov_trace_gep";
61 const char SanCovTraceSwitchName[] = "__sanitizer_cov_trace_switch";
62 const char SanCovModuleCtorTracePcGuardName[] =
63     "sancov.module_ctor_trace_pc_guard";
64 const char SanCovModuleCtor8bitCountersName[] =
65     "sancov.module_ctor_8bit_counters";
66 const char SanCovModuleCtorBoolFlagName[] = "sancov.module_ctor_bool_flag";
67 static const uint64_t SanCtorAndDtorPriority = 2;
68 
69 const char SanCovTracePCGuardName[] = "__sanitizer_cov_trace_pc_guard";
70 const char SanCovTracePCGuardInitName[] = "__sanitizer_cov_trace_pc_guard_init";
71 const char SanCov8bitCountersInitName[] = "__sanitizer_cov_8bit_counters_init";
72 const char SanCovBoolFlagInitName[] = "__sanitizer_cov_bool_flag_init";
73 const char SanCovPCsInitName[] = "__sanitizer_cov_pcs_init";
74 
75 const char SanCovGuardsSectionName[] = "sancov_guards";
76 const char SanCovCountersSectionName[] = "sancov_cntrs";
77 const char SanCovBoolFlagSectionName[] = "sancov_bools";
78 const char SanCovPCsSectionName[] = "sancov_pcs";
79 
80 const char 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, inline-8bit-counters, and
101 // inline-bool-flag.
102 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table",
103                                      cl::desc("create a static PC table"),
104                                      cl::Hidden, cl::init(false));
105 
106 static cl::opt<bool>
107     ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters",
108                          cl::desc("increments 8-bit counter for every edge"),
109                          cl::Hidden, cl::init(false));
110 
111 static cl::opt<bool>
112     ClInlineBoolFlag("sanitizer-coverage-inline-bool-flag",
113                      cl::desc("sets a boolean flag for every edge"), cl::Hidden,
114                      cl::init(false));
115 
116 static cl::opt<bool>
117     ClCMPTracing("sanitizer-coverage-trace-compares",
118                  cl::desc("Tracing of CMP and similar instructions"),
119                  cl::Hidden, cl::init(false));
120 
121 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs",
122                                   cl::desc("Tracing of DIV instructions"),
123                                   cl::Hidden, cl::init(false));
124 
125 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps",
126                                   cl::desc("Tracing of GEP instructions"),
127                                   cl::Hidden, cl::init(false));
128 
129 static cl::opt<bool>
130     ClPruneBlocks("sanitizer-coverage-prune-blocks",
131                   cl::desc("Reduce the number of instrumented blocks"),
132                   cl::Hidden, cl::init(true));
133 
134 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth",
135                                   cl::desc("max stack depth tracing"),
136                                   cl::Hidden, cl::init(false));
137 
138 namespace {
139 
140 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
141   SanitizerCoverageOptions Res;
142   switch (LegacyCoverageLevel) {
143   case 0:
144     Res.CoverageType = SanitizerCoverageOptions::SCK_None;
145     break;
146   case 1:
147     Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
148     break;
149   case 2:
150     Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
151     break;
152   case 3:
153     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
154     break;
155   case 4:
156     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
157     Res.IndirectCalls = true;
158     break;
159   }
160   return Res;
161 }
162 
163 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
164   // Sets CoverageType and IndirectCalls.
165   SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
166   Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
167   Options.IndirectCalls |= CLOpts.IndirectCalls;
168   Options.TraceCmp |= ClCMPTracing;
169   Options.TraceDiv |= ClDIVTracing;
170   Options.TraceGep |= ClGEPTracing;
171   Options.TracePC |= ClTracePC;
172   Options.TracePCGuard |= ClTracePCGuard;
173   Options.Inline8bitCounters |= ClInline8bitCounters;
174   Options.InlineBoolFlag |= ClInlineBoolFlag;
175   Options.PCTable |= ClCreatePCTable;
176   Options.NoPrune |= !ClPruneBlocks;
177   Options.StackDepth |= ClStackDepth;
178   if (!Options.TracePCGuard && !Options.TracePC &&
179       !Options.Inline8bitCounters && !Options.StackDepth &&
180       !Options.InlineBoolFlag)
181     Options.TracePCGuard = true; // TracePCGuard is default.
182   return Options;
183 }
184 
185 using DomTreeCallback = function_ref<const DominatorTree *(Function &F)>;
186 using PostDomTreeCallback =
187     function_ref<const PostDominatorTree *(Function &F)>;
188 
189 class ModuleSanitizerCoverage {
190 public:
191   ModuleSanitizerCoverage(
192       const SanitizerCoverageOptions &Options = SanitizerCoverageOptions(),
193       const SpecialCaseList *Allowlist = nullptr,
194       const SpecialCaseList *Blocklist = nullptr)
195       : Options(OverrideFromCL(Options)), Allowlist(Allowlist),
196         Blocklist(Blocklist) {}
197   bool instrumentModule(Module &M, DomTreeCallback DTCallback,
198                         PostDomTreeCallback PDTCallback);
199 
200 private:
201   void instrumentFunction(Function &F, DomTreeCallback DTCallback,
202                           PostDomTreeCallback PDTCallback);
203   void InjectCoverageForIndirectCalls(Function &F,
204                                       ArrayRef<Instruction *> IndirCalls);
205   void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
206   void InjectTraceForDiv(Function &F,
207                          ArrayRef<BinaryOperator *> DivTraceTargets);
208   void InjectTraceForGep(Function &F,
209                          ArrayRef<GetElementPtrInst *> GepTraceTargets);
210   void InjectTraceForSwitch(Function &F,
211                             ArrayRef<Instruction *> SwitchTraceTargets);
212   bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
213                       bool IsLeafFunc = true);
214   GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
215                                                     Function &F, Type *Ty,
216                                                     const char *Section);
217   GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
218   void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
219   void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
220                              bool IsLeafFunc = true);
221   Function *CreateInitCallsForSections(Module &M, const char *CtorName,
222                                        const char *InitFunctionName, Type *Ty,
223                                        const char *Section);
224   std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section,
225                                                 Type *Ty);
226 
227   void SetNoSanitizeMetadata(Instruction *I) {
228     I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
229                    MDNode::get(*C, None));
230   }
231 
232   std::string getSectionName(const std::string &Section) const;
233   std::string getSectionStart(const std::string &Section) const;
234   std::string getSectionEnd(const std::string &Section) const;
235   FunctionCallee SanCovTracePCIndir;
236   FunctionCallee SanCovTracePC, SanCovTracePCGuard;
237   FunctionCallee SanCovTraceCmpFunction[4];
238   FunctionCallee SanCovTraceConstCmpFunction[4];
239   FunctionCallee SanCovTraceDivFunction[2];
240   FunctionCallee SanCovTraceGepFunction;
241   FunctionCallee SanCovTraceSwitchFunction;
242   GlobalVariable *SanCovLowestStack;
243   Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy,
244       *Int16Ty, *Int8Ty, *Int8PtrTy, *Int1Ty, *Int1PtrTy;
245   Module *CurModule;
246   std::string CurModuleUniqueId;
247   Triple TargetTriple;
248   LLVMContext *C;
249   const DataLayout *DL;
250 
251   GlobalVariable *FunctionGuardArray;  // for trace-pc-guard.
252   GlobalVariable *Function8bitCounterArray;  // for inline-8bit-counters.
253   GlobalVariable *FunctionBoolArray;         // for inline-bool-flag.
254   GlobalVariable *FunctionPCsArray;  // for pc-table.
255   SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
256   SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
257 
258   SanitizerCoverageOptions Options;
259 
260   const SpecialCaseList *Allowlist;
261   const SpecialCaseList *Blocklist;
262 };
263 
264 class ModuleSanitizerCoverageLegacyPass : public ModulePass {
265 public:
266   ModuleSanitizerCoverageLegacyPass(
267       const SanitizerCoverageOptions &Options = SanitizerCoverageOptions(),
268       const std::vector<std::string> &AllowlistFiles =
269           std::vector<std::string>(),
270       const std::vector<std::string> &BlocklistFiles =
271           std::vector<std::string>())
272       : ModulePass(ID), Options(Options) {
273     if (AllowlistFiles.size() > 0)
274       Allowlist = SpecialCaseList::createOrDie(AllowlistFiles,
275                                                *vfs::getRealFileSystem());
276     if (BlocklistFiles.size() > 0)
277       Blocklist = SpecialCaseList::createOrDie(BlocklistFiles,
278                                                *vfs::getRealFileSystem());
279     initializeModuleSanitizerCoverageLegacyPassPass(
280         *PassRegistry::getPassRegistry());
281   }
282   bool runOnModule(Module &M) override {
283     ModuleSanitizerCoverage ModuleSancov(Options, Allowlist.get(),
284                                          Blocklist.get());
285     auto DTCallback = [this](Function &F) -> const DominatorTree * {
286       return &this->getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
287     };
288     auto PDTCallback = [this](Function &F) -> const PostDominatorTree * {
289       return &this->getAnalysis<PostDominatorTreeWrapperPass>(F)
290                   .getPostDomTree();
291     };
292     return ModuleSancov.instrumentModule(M, DTCallback, PDTCallback);
293   }
294 
295   static char ID; // Pass identification, replacement for typeid
296   StringRef getPassName() const override { return "ModuleSanitizerCoverage"; }
297 
298   void getAnalysisUsage(AnalysisUsage &AU) const override {
299     AU.addRequired<DominatorTreeWrapperPass>();
300     AU.addRequired<PostDominatorTreeWrapperPass>();
301   }
302 
303 private:
304   SanitizerCoverageOptions Options;
305 
306   std::unique_ptr<SpecialCaseList> Allowlist;
307   std::unique_ptr<SpecialCaseList> Blocklist;
308 };
309 
310 } // namespace
311 
312 PreservedAnalyses ModuleSanitizerCoveragePass::run(Module &M,
313                                                    ModuleAnalysisManager &MAM) {
314   ModuleSanitizerCoverage ModuleSancov(Options, Allowlist.get(),
315                                        Blocklist.get());
316   auto &FAM = MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
317   auto DTCallback = [&FAM](Function &F) -> const DominatorTree * {
318     return &FAM.getResult<DominatorTreeAnalysis>(F);
319   };
320   auto PDTCallback = [&FAM](Function &F) -> const PostDominatorTree * {
321     return &FAM.getResult<PostDominatorTreeAnalysis>(F);
322   };
323   if (ModuleSancov.instrumentModule(M, DTCallback, PDTCallback))
324     return PreservedAnalyses::none();
325   return PreservedAnalyses::all();
326 }
327 
328 std::pair<Value *, Value *>
329 ModuleSanitizerCoverage::CreateSecStartEnd(Module &M, const char *Section,
330                                            Type *Ty) {
331   GlobalVariable *SecStart = new GlobalVariable(
332       M, Ty->getPointerElementType(), false, GlobalVariable::ExternalLinkage,
333       nullptr, getSectionStart(Section));
334   SecStart->setVisibility(GlobalValue::HiddenVisibility);
335   GlobalVariable *SecEnd = new GlobalVariable(
336       M, Ty->getPointerElementType(), false, GlobalVariable::ExternalLinkage,
337       nullptr, getSectionEnd(Section));
338   SecEnd->setVisibility(GlobalValue::HiddenVisibility);
339   IRBuilder<> IRB(M.getContext());
340   if (!TargetTriple.isOSBinFormatCOFF())
341     return std::make_pair(SecStart, SecEnd);
342 
343   // Account for the fact that on windows-msvc __start_* symbols actually
344   // point to a uint64_t before the start of the array.
345   auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy);
346   auto GEP = IRB.CreateGEP(Int8Ty, SecStartI8Ptr,
347                            ConstantInt::get(IntptrTy, sizeof(uint64_t)));
348   return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEnd);
349 }
350 
351 Function *ModuleSanitizerCoverage::CreateInitCallsForSections(
352     Module &M, const char *CtorName, const char *InitFunctionName, Type *Ty,
353     const char *Section) {
354   auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
355   auto SecStart = SecStartEnd.first;
356   auto SecEnd = SecStartEnd.second;
357   Function *CtorFunc;
358   std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
359       M, CtorName, InitFunctionName, {Ty, Ty}, {SecStart, SecEnd});
360   assert(CtorFunc->getName() == CtorName);
361 
362   if (TargetTriple.supportsCOMDAT()) {
363     // Use comdat to dedup CtorFunc.
364     CtorFunc->setComdat(M.getOrInsertComdat(CtorName));
365     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
366   } else {
367     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
368   }
369 
370   if (TargetTriple.isOSBinFormatCOFF()) {
371     // In COFF files, if the contructors are set as COMDAT (they are because
372     // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
373     // functions and data) is used, the constructors get stripped. To prevent
374     // this, give the constructors weak ODR linkage and ensure the linker knows
375     // to include the sancov constructor. This way the linker can deduplicate
376     // the constructors but always leave one copy.
377     CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
378     appendToUsed(M, CtorFunc);
379   }
380   return CtorFunc;
381 }
382 
383 bool ModuleSanitizerCoverage::instrumentModule(
384     Module &M, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
385   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
386     return false;
387   if (Allowlist &&
388       !Allowlist->inSection("coverage", "src", M.getSourceFileName()))
389     return false;
390   if (Blocklist &&
391       Blocklist->inSection("coverage", "src", M.getSourceFileName()))
392     return false;
393   C = &(M.getContext());
394   DL = &M.getDataLayout();
395   CurModule = &M;
396   CurModuleUniqueId = getUniqueModuleId(CurModule);
397   TargetTriple = Triple(M.getTargetTriple());
398   FunctionGuardArray = nullptr;
399   Function8bitCounterArray = nullptr;
400   FunctionBoolArray = nullptr;
401   FunctionPCsArray = nullptr;
402   IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
403   IntptrPtrTy = PointerType::getUnqual(IntptrTy);
404   Type *VoidTy = Type::getVoidTy(*C);
405   IRBuilder<> IRB(*C);
406   Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
407   Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
408   Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
409   Int1PtrTy = PointerType::getUnqual(IRB.getInt1Ty());
410   Int64Ty = IRB.getInt64Ty();
411   Int32Ty = IRB.getInt32Ty();
412   Int16Ty = IRB.getInt16Ty();
413   Int8Ty = IRB.getInt8Ty();
414   Int1Ty = IRB.getInt1Ty();
415 
416   SanCovTracePCIndir =
417       M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy);
418   // Make sure smaller parameters are zero-extended to i64 if required by the
419   // target ABI.
420   AttributeList SanCovTraceCmpZeroExtAL;
421   SanCovTraceCmpZeroExtAL =
422       SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt);
423   SanCovTraceCmpZeroExtAL =
424       SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt);
425 
426   SanCovTraceCmpFunction[0] =
427       M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy,
428                             IRB.getInt8Ty(), IRB.getInt8Ty());
429   SanCovTraceCmpFunction[1] =
430       M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy,
431                             IRB.getInt16Ty(), IRB.getInt16Ty());
432   SanCovTraceCmpFunction[2] =
433       M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy,
434                             IRB.getInt32Ty(), IRB.getInt32Ty());
435   SanCovTraceCmpFunction[3] =
436       M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty);
437 
438   SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction(
439       SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty);
440   SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction(
441       SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty);
442   SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction(
443       SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty);
444   SanCovTraceConstCmpFunction[3] =
445       M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty);
446 
447   {
448     AttributeList AL;
449     AL = AL.addParamAttribute(*C, 0, Attribute::ZExt);
450     SanCovTraceDivFunction[0] =
451         M.getOrInsertFunction(SanCovTraceDiv4, AL, VoidTy, IRB.getInt32Ty());
452   }
453   SanCovTraceDivFunction[1] =
454       M.getOrInsertFunction(SanCovTraceDiv8, VoidTy, Int64Ty);
455   SanCovTraceGepFunction =
456       M.getOrInsertFunction(SanCovTraceGep, VoidTy, IntptrTy);
457   SanCovTraceSwitchFunction =
458       M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy);
459 
460   Constant *SanCovLowestStackConstant =
461       M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
462   SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant);
463   if (!SanCovLowestStack) {
464     C->emitError(StringRef("'") + SanCovLowestStackName +
465                  "' should not be declared by the user");
466     return true;
467   }
468   SanCovLowestStack->setThreadLocalMode(
469       GlobalValue::ThreadLocalMode::InitialExecTLSModel);
470   if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
471     SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
472 
473   SanCovTracePC = M.getOrInsertFunction(SanCovTracePCName, VoidTy);
474   SanCovTracePCGuard =
475       M.getOrInsertFunction(SanCovTracePCGuardName, VoidTy, Int32PtrTy);
476 
477   for (auto &F : M)
478     instrumentFunction(F, DTCallback, PDTCallback);
479 
480   Function *Ctor = nullptr;
481 
482   if (FunctionGuardArray)
483     Ctor = CreateInitCallsForSections(M, SanCovModuleCtorTracePcGuardName,
484                                       SanCovTracePCGuardInitName, Int32PtrTy,
485                                       SanCovGuardsSectionName);
486   if (Function8bitCounterArray)
487     Ctor = CreateInitCallsForSections(M, SanCovModuleCtor8bitCountersName,
488                                       SanCov8bitCountersInitName, Int8PtrTy,
489                                       SanCovCountersSectionName);
490   if (FunctionBoolArray) {
491     Ctor = CreateInitCallsForSections(M, SanCovModuleCtorBoolFlagName,
492                                       SanCovBoolFlagInitName, Int1PtrTy,
493                                       SanCovBoolFlagSectionName);
494   }
495   if (Ctor && Options.PCTable) {
496     auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy);
497     FunctionCallee InitFunction = declareSanitizerInitFunction(
498         M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy});
499     IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
500     IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
501   }
502   // We don't reference these arrays directly in any of our runtime functions,
503   // so we need to prevent them from being dead stripped.
504   if (TargetTriple.isOSBinFormatMachO())
505     appendToUsed(M, GlobalsToAppendToUsed);
506   appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
507   return true;
508 }
509 
510 // True if block has successors and it dominates all of them.
511 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
512   if (succ_empty(BB))
513     return false;
514 
515   return llvm::all_of(successors(BB), [&](const BasicBlock *SUCC) {
516     return DT->dominates(BB, SUCC);
517   });
518 }
519 
520 // True if block has predecessors and it postdominates all of them.
521 static bool isFullPostDominator(const BasicBlock *BB,
522                                 const PostDominatorTree *PDT) {
523   if (pred_empty(BB))
524     return false;
525 
526   return llvm::all_of(predecessors(BB), [&](const BasicBlock *PRED) {
527     return PDT->dominates(BB, PRED);
528   });
529 }
530 
531 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
532                                   const DominatorTree *DT,
533                                   const PostDominatorTree *PDT,
534                                   const SanitizerCoverageOptions &Options) {
535   // Don't insert coverage for blocks containing nothing but unreachable: we
536   // will never call __sanitizer_cov() for them, so counting them in
537   // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
538   // percentage. Also, unreachable instructions frequently have no debug
539   // locations.
540   if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime()))
541     return false;
542 
543   // Don't insert coverage into blocks without a valid insertion point
544   // (catchswitch blocks).
545   if (BB->getFirstInsertionPt() == BB->end())
546     return false;
547 
548   if (Options.NoPrune || &F.getEntryBlock() == BB)
549     return true;
550 
551   if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
552       &F.getEntryBlock() != BB)
553     return false;
554 
555   // Do not instrument full dominators, or full post-dominators with multiple
556   // predecessors.
557   return !isFullDominator(BB, DT)
558     && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
559 }
560 
561 
562 // Returns true iff From->To is a backedge.
563 // A twist here is that we treat From->To as a backedge if
564 //   * To dominates From or
565 //   * To->UniqueSuccessor dominates From
566 static bool IsBackEdge(BasicBlock *From, BasicBlock *To,
567                        const DominatorTree *DT) {
568   if (DT->dominates(To, From))
569     return true;
570   if (auto Next = To->getUniqueSuccessor())
571     if (DT->dominates(Next, From))
572       return true;
573   return false;
574 }
575 
576 // Prunes uninteresting Cmp instrumentation:
577 //   * CMP instructions that feed into loop backedge branch.
578 //
579 // Note that Cmp pruning is controlled by the same flag as the
580 // BB pruning.
581 static bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree *DT,
582                              const SanitizerCoverageOptions &Options) {
583   if (!Options.NoPrune)
584     if (CMP->hasOneUse())
585       if (auto BR = dyn_cast<BranchInst>(CMP->user_back()))
586         for (BasicBlock *B : BR->successors())
587           if (IsBackEdge(BR->getParent(), B, DT))
588             return false;
589   return true;
590 }
591 
592 void ModuleSanitizerCoverage::instrumentFunction(
593     Function &F, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
594   if (F.empty())
595     return;
596   if (F.getName().find(".module_ctor") != std::string::npos)
597     return; // Should not instrument sanitizer init functions.
598   if (F.getName().startswith("__sanitizer_"))
599     return; // Don't instrument __sanitizer_* callbacks.
600   // Don't touch available_externally functions, their actual body is elewhere.
601   if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
602     return;
603   // Don't instrument MSVC CRT configuration helpers. They may run before normal
604   // initialization.
605   if (F.getName() == "__local_stdio_printf_options" ||
606       F.getName() == "__local_stdio_scanf_options")
607     return;
608   if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
609     return;
610   // Don't instrument functions using SEH for now. Splitting basic blocks like
611   // we do for coverage breaks WinEHPrepare.
612   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
613   if (F.hasPersonalityFn() &&
614       isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
615     return;
616   if (Allowlist && !Allowlist->inSection("coverage", "fun", F.getName()))
617     return;
618   if (Blocklist && Blocklist->inSection("coverage", "fun", F.getName()))
619     return;
620   if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
621     SplitAllCriticalEdges(F, CriticalEdgeSplittingOptions().setIgnoreUnreachableDests());
622   SmallVector<Instruction *, 8> IndirCalls;
623   SmallVector<BasicBlock *, 16> BlocksToInstrument;
624   SmallVector<Instruction *, 8> CmpTraceTargets;
625   SmallVector<Instruction *, 8> SwitchTraceTargets;
626   SmallVector<BinaryOperator *, 8> DivTraceTargets;
627   SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
628 
629   const DominatorTree *DT = DTCallback(F);
630   const PostDominatorTree *PDT = PDTCallback(F);
631   bool IsLeafFunc = true;
632 
633   for (auto &BB : F) {
634     if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
635       BlocksToInstrument.push_back(&BB);
636     for (auto &Inst : BB) {
637       if (Options.IndirectCalls) {
638         CallBase *CB = dyn_cast<CallBase>(&Inst);
639         if (CB && !CB->getCalledFunction())
640           IndirCalls.push_back(&Inst);
641       }
642       if (Options.TraceCmp) {
643         if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst))
644           if (IsInterestingCmp(CMP, DT, Options))
645             CmpTraceTargets.push_back(&Inst);
646         if (isa<SwitchInst>(&Inst))
647           SwitchTraceTargets.push_back(&Inst);
648       }
649       if (Options.TraceDiv)
650         if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
651           if (BO->getOpcode() == Instruction::SDiv ||
652               BO->getOpcode() == Instruction::UDiv)
653             DivTraceTargets.push_back(BO);
654       if (Options.TraceGep)
655         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
656           GepTraceTargets.push_back(GEP);
657       if (Options.StackDepth)
658         if (isa<InvokeInst>(Inst) ||
659             (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
660           IsLeafFunc = false;
661     }
662   }
663 
664   InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
665   InjectCoverageForIndirectCalls(F, IndirCalls);
666   InjectTraceForCmp(F, CmpTraceTargets);
667   InjectTraceForSwitch(F, SwitchTraceTargets);
668   InjectTraceForDiv(F, DivTraceTargets);
669   InjectTraceForGep(F, GepTraceTargets);
670 }
671 
672 GlobalVariable *ModuleSanitizerCoverage::CreateFunctionLocalArrayInSection(
673     size_t NumElements, Function &F, Type *Ty, const char *Section) {
674   ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
675   auto Array = new GlobalVariable(
676       *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
677       Constant::getNullValue(ArrayTy), "__sancov_gen_");
678 
679   if (TargetTriple.supportsCOMDAT() && !F.isInterposable())
680     if (auto Comdat =
681             GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId))
682       Array->setComdat(Comdat);
683   Array->setSection(getSectionName(Section));
684   Array->setAlignment(Align(DL->getTypeStoreSize(Ty).getFixedSize()));
685   GlobalsToAppendToUsed.push_back(Array);
686   GlobalsToAppendToCompilerUsed.push_back(Array);
687   MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
688   Array->addMetadata(LLVMContext::MD_associated, *MD);
689 
690   return Array;
691 }
692 
693 GlobalVariable *
694 ModuleSanitizerCoverage::CreatePCArray(Function &F,
695                                        ArrayRef<BasicBlock *> AllBlocks) {
696   size_t N = AllBlocks.size();
697   assert(N);
698   SmallVector<Constant *, 32> PCs;
699   IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
700   for (size_t i = 0; i < N; i++) {
701     if (&F.getEntryBlock() == AllBlocks[i]) {
702       PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
703       PCs.push_back((Constant *)IRB.CreateIntToPtr(
704           ConstantInt::get(IntptrTy, 1), IntptrPtrTy));
705     } else {
706       PCs.push_back((Constant *)IRB.CreatePointerCast(
707           BlockAddress::get(AllBlocks[i]), IntptrPtrTy));
708       PCs.push_back((Constant *)IRB.CreateIntToPtr(
709           ConstantInt::get(IntptrTy, 0), IntptrPtrTy));
710     }
711   }
712   auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy,
713                                                     SanCovPCsSectionName);
714   PCArray->setInitializer(
715       ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs));
716   PCArray->setConstant(true);
717 
718   return PCArray;
719 }
720 
721 void ModuleSanitizerCoverage::CreateFunctionLocalArrays(
722     Function &F, ArrayRef<BasicBlock *> AllBlocks) {
723   if (Options.TracePCGuard)
724     FunctionGuardArray = CreateFunctionLocalArrayInSection(
725         AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
726 
727   if (Options.Inline8bitCounters)
728     Function8bitCounterArray = CreateFunctionLocalArrayInSection(
729         AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
730   if (Options.InlineBoolFlag)
731     FunctionBoolArray = CreateFunctionLocalArrayInSection(
732         AllBlocks.size(), F, Int1Ty, SanCovBoolFlagSectionName);
733 
734   if (Options.PCTable)
735     FunctionPCsArray = CreatePCArray(F, AllBlocks);
736 }
737 
738 bool ModuleSanitizerCoverage::InjectCoverage(Function &F,
739                                              ArrayRef<BasicBlock *> AllBlocks,
740                                              bool IsLeafFunc) {
741   if (AllBlocks.empty()) return false;
742   CreateFunctionLocalArrays(F, AllBlocks);
743   for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
744     InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
745   return true;
746 }
747 
748 // On every indirect call we call a run-time function
749 // __sanitizer_cov_indir_call* with two parameters:
750 //   - callee address,
751 //   - global cache array that contains CacheSize pointers (zero-initialized).
752 //     The cache is used to speed up recording the caller-callee pairs.
753 // The address of the caller is passed implicitly via caller PC.
754 // CacheSize is encoded in the name of the run-time function.
755 void ModuleSanitizerCoverage::InjectCoverageForIndirectCalls(
756     Function &F, ArrayRef<Instruction *> IndirCalls) {
757   if (IndirCalls.empty())
758     return;
759   assert(Options.TracePC || Options.TracePCGuard ||
760          Options.Inline8bitCounters || Options.InlineBoolFlag);
761   for (auto I : IndirCalls) {
762     IRBuilder<> IRB(I);
763     CallBase &CB = cast<CallBase>(*I);
764     Value *Callee = CB.getCalledOperand();
765     if (isa<InlineAsm>(Callee))
766       continue;
767     IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
768   }
769 }
770 
771 // For every switch statement we insert a call:
772 // __sanitizer_cov_trace_switch(CondValue,
773 //      {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
774 
775 void ModuleSanitizerCoverage::InjectTraceForSwitch(
776     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
777   for (auto I : SwitchTraceTargets) {
778     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
779       IRBuilder<> IRB(I);
780       SmallVector<Constant *, 16> Initializers;
781       Value *Cond = SI->getCondition();
782       if (Cond->getType()->getScalarSizeInBits() >
783           Int64Ty->getScalarSizeInBits())
784         continue;
785       Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
786       Initializers.push_back(
787           ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
788       if (Cond->getType()->getScalarSizeInBits() <
789           Int64Ty->getScalarSizeInBits())
790         Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
791       for (auto It : SI->cases()) {
792         Constant *C = It.getCaseValue();
793         if (C->getType()->getScalarSizeInBits() <
794             Int64Ty->getScalarSizeInBits())
795           C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
796         Initializers.push_back(C);
797       }
798       llvm::sort(drop_begin(Initializers, 2),
799                  [](const Constant *A, const Constant *B) {
800                    return cast<ConstantInt>(A)->getLimitedValue() <
801                           cast<ConstantInt>(B)->getLimitedValue();
802                  });
803       ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
804       GlobalVariable *GV = new GlobalVariable(
805           *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
806           ConstantArray::get(ArrayOfInt64Ty, Initializers),
807           "__sancov_gen_cov_switch_values");
808       IRB.CreateCall(SanCovTraceSwitchFunction,
809                      {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
810     }
811   }
812 }
813 
814 void ModuleSanitizerCoverage::InjectTraceForDiv(
815     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
816   for (auto BO : DivTraceTargets) {
817     IRBuilder<> IRB(BO);
818     Value *A1 = BO->getOperand(1);
819     if (isa<ConstantInt>(A1)) continue;
820     if (!A1->getType()->isIntegerTy())
821       continue;
822     uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
823     int CallbackIdx = TypeSize == 32 ? 0 :
824         TypeSize == 64 ? 1 : -1;
825     if (CallbackIdx < 0) continue;
826     auto Ty = Type::getIntNTy(*C, TypeSize);
827     IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
828                    {IRB.CreateIntCast(A1, Ty, true)});
829   }
830 }
831 
832 void ModuleSanitizerCoverage::InjectTraceForGep(
833     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
834   for (auto GEP : GepTraceTargets) {
835     IRBuilder<> IRB(GEP);
836     for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
837       if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy())
838         IRB.CreateCall(SanCovTraceGepFunction,
839                        {IRB.CreateIntCast(*I, IntptrTy, true)});
840   }
841 }
842 
843 void ModuleSanitizerCoverage::InjectTraceForCmp(
844     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
845   for (auto I : CmpTraceTargets) {
846     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
847       IRBuilder<> IRB(ICMP);
848       Value *A0 = ICMP->getOperand(0);
849       Value *A1 = ICMP->getOperand(1);
850       if (!A0->getType()->isIntegerTy())
851         continue;
852       uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
853       int CallbackIdx = TypeSize == 8 ? 0 :
854                         TypeSize == 16 ? 1 :
855                         TypeSize == 32 ? 2 :
856                         TypeSize == 64 ? 3 : -1;
857       if (CallbackIdx < 0) continue;
858       // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
859       auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
860       bool FirstIsConst = isa<ConstantInt>(A0);
861       bool SecondIsConst = isa<ConstantInt>(A1);
862       // If both are const, then we don't need such a comparison.
863       if (FirstIsConst && SecondIsConst) continue;
864       // If only one is const, then make it the first callback argument.
865       if (FirstIsConst || SecondIsConst) {
866         CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
867         if (SecondIsConst)
868           std::swap(A0, A1);
869       }
870 
871       auto Ty = Type::getIntNTy(*C, TypeSize);
872       IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
873               IRB.CreateIntCast(A1, Ty, true)});
874     }
875   }
876 }
877 
878 void ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
879                                                     size_t Idx,
880                                                     bool IsLeafFunc) {
881   BasicBlock::iterator IP = BB.getFirstInsertionPt();
882   bool IsEntryBB = &BB == &F.getEntryBlock();
883   DebugLoc EntryLoc;
884   if (IsEntryBB) {
885     if (auto SP = F.getSubprogram())
886       EntryLoc = DILocation::get(SP->getContext(), SP->getScopeLine(), 0, SP);
887     // Keep static allocas and llvm.localescape calls in the entry block.  Even
888     // if we aren't splitting the block, it's nice for allocas to be before
889     // calls.
890     IP = PrepareToSplitEntryBlock(BB, IP);
891   } else {
892     EntryLoc = IP->getDebugLoc();
893   }
894 
895   IRBuilder<> IRB(&*IP);
896   IRB.SetCurrentDebugLocation(EntryLoc);
897   if (Options.TracePC) {
898     IRB.CreateCall(SanCovTracePC)
899         ->setCannotMerge(); // gets the PC using GET_CALLER_PC.
900   }
901   if (Options.TracePCGuard) {
902     auto GuardPtr = IRB.CreateIntToPtr(
903         IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
904                       ConstantInt::get(IntptrTy, Idx * 4)),
905         Int32PtrTy);
906     IRB.CreateCall(SanCovTracePCGuard, GuardPtr)->setCannotMerge();
907   }
908   if (Options.Inline8bitCounters) {
909     auto CounterPtr = IRB.CreateGEP(
910         Function8bitCounterArray->getValueType(), Function8bitCounterArray,
911         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
912     auto Load = IRB.CreateLoad(Int8Ty, CounterPtr);
913     auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
914     auto Store = IRB.CreateStore(Inc, CounterPtr);
915     SetNoSanitizeMetadata(Load);
916     SetNoSanitizeMetadata(Store);
917   }
918   if (Options.InlineBoolFlag) {
919     auto FlagPtr = IRB.CreateGEP(
920         FunctionBoolArray->getValueType(), FunctionBoolArray,
921         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
922     auto Load = IRB.CreateLoad(Int1Ty, FlagPtr);
923     auto ThenTerm =
924         SplitBlockAndInsertIfThen(IRB.CreateIsNull(Load), &*IP, false);
925     IRBuilder<> ThenIRB(ThenTerm);
926     auto Store = ThenIRB.CreateStore(ConstantInt::getTrue(Int1Ty), FlagPtr);
927     SetNoSanitizeMetadata(Load);
928     SetNoSanitizeMetadata(Store);
929   }
930   if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
931     // Check stack depth.  If it's the deepest so far, record it.
932     Module *M = F.getParent();
933     Function *GetFrameAddr = Intrinsic::getDeclaration(
934         M, Intrinsic::frameaddress,
935         IRB.getInt8PtrTy(M->getDataLayout().getAllocaAddrSpace()));
936     auto FrameAddrPtr =
937         IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
938     auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
939     auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack);
940     auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
941     auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false);
942     IRBuilder<> ThenIRB(ThenTerm);
943     auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
944     SetNoSanitizeMetadata(LowestStack);
945     SetNoSanitizeMetadata(Store);
946   }
947 }
948 
949 std::string
950 ModuleSanitizerCoverage::getSectionName(const std::string &Section) const {
951   if (TargetTriple.isOSBinFormatCOFF()) {
952     if (Section == SanCovCountersSectionName)
953       return ".SCOV$CM";
954     if (Section == SanCovBoolFlagSectionName)
955       return ".SCOV$BM";
956     if (Section == SanCovPCsSectionName)
957       return ".SCOVP$M";
958     return ".SCOV$GM"; // For SanCovGuardsSectionName.
959   }
960   if (TargetTriple.isOSBinFormatMachO())
961     return "__DATA,__" + Section;
962   return "__" + Section;
963 }
964 
965 std::string
966 ModuleSanitizerCoverage::getSectionStart(const std::string &Section) const {
967   if (TargetTriple.isOSBinFormatMachO())
968     return "\1section$start$__DATA$__" + Section;
969   return "__start___" + Section;
970 }
971 
972 std::string
973 ModuleSanitizerCoverage::getSectionEnd(const std::string &Section) const {
974   if (TargetTriple.isOSBinFormatMachO())
975     return "\1section$end$__DATA$__" + Section;
976   return "__stop___" + Section;
977 }
978 
979 char ModuleSanitizerCoverageLegacyPass::ID = 0;
980 INITIALIZE_PASS_BEGIN(ModuleSanitizerCoverageLegacyPass, "sancov",
981                       "Pass for instrumenting coverage on functions", false,
982                       false)
983 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
984 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
985 INITIALIZE_PASS_END(ModuleSanitizerCoverageLegacyPass, "sancov",
986                     "Pass for instrumenting coverage on functions", false,
987                     false)
988 ModulePass *llvm::createModuleSanitizerCoverageLegacyPassPass(
989     const SanitizerCoverageOptions &Options,
990     const std::vector<std::string> &AllowlistFiles,
991     const std::vector<std::string> &BlocklistFiles) {
992   return new ModuleSanitizerCoverageLegacyPass(Options, AllowlistFiles,
993                                                BlocklistFiles);
994 }
995