xref: /freebsd/contrib/llvm-project/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp (revision ec0ea6efa1ad229d75c394c1a9b9cac33af2b1d3) 
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   // Use ExternalWeak so that if all sections are discarded due to section
332   // garbage collection, the linker will not report undefined symbol errors.
333   // Windows defines the start/stop symbols in compiler-rt so no need for
334   // ExternalWeak.
335   GlobalValue::LinkageTypes Linkage = TargetTriple.isOSBinFormatCOFF()
336                                           ? GlobalVariable::ExternalLinkage
337                                           : GlobalVariable::ExternalWeakLinkage;
338   GlobalVariable *SecStart =
339       new GlobalVariable(M, Ty, false, Linkage, nullptr,
340                          getSectionStart(Section));
341   SecStart->setVisibility(GlobalValue::HiddenVisibility);
342   GlobalVariable *SecEnd =
343       new GlobalVariable(M, Ty, false, Linkage, nullptr,
344                          getSectionEnd(Section));
345   SecEnd->setVisibility(GlobalValue::HiddenVisibility);
346   IRBuilder<> IRB(M.getContext());
347   if (!TargetTriple.isOSBinFormatCOFF())
348     return std::make_pair(SecStart, SecEnd);
349 
350   // Account for the fact that on windows-msvc __start_* symbols actually
351   // point to a uint64_t before the start of the array.
352   auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy);
353   auto GEP = IRB.CreateGEP(Int8Ty, SecStartI8Ptr,
354                            ConstantInt::get(IntptrTy, sizeof(uint64_t)));
355   return std::make_pair(IRB.CreatePointerCast(GEP, PointerType::getUnqual(Ty)),
356                         SecEnd);
357 }
358 
359 Function *ModuleSanitizerCoverage::CreateInitCallsForSections(
360     Module &M, const char *CtorName, const char *InitFunctionName, Type *Ty,
361     const char *Section) {
362   auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
363   auto SecStart = SecStartEnd.first;
364   auto SecEnd = SecStartEnd.second;
365   Function *CtorFunc;
366   Type *PtrTy = PointerType::getUnqual(Ty);
367   std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
368       M, CtorName, InitFunctionName, {PtrTy, PtrTy}, {SecStart, SecEnd});
369   assert(CtorFunc->getName() == CtorName);
370 
371   if (TargetTriple.supportsCOMDAT()) {
372     // Use comdat to dedup CtorFunc.
373     CtorFunc->setComdat(M.getOrInsertComdat(CtorName));
374     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
375   } else {
376     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
377   }
378 
379   if (TargetTriple.isOSBinFormatCOFF()) {
380     // In COFF files, if the contructors are set as COMDAT (they are because
381     // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
382     // functions and data) is used, the constructors get stripped. To prevent
383     // this, give the constructors weak ODR linkage and ensure the linker knows
384     // to include the sancov constructor. This way the linker can deduplicate
385     // the constructors but always leave one copy.
386     CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
387   }
388   return CtorFunc;
389 }
390 
391 bool ModuleSanitizerCoverage::instrumentModule(
392     Module &M, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
393   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
394     return false;
395   if (Allowlist &&
396       !Allowlist->inSection("coverage", "src", M.getSourceFileName()))
397     return false;
398   if (Blocklist &&
399       Blocklist->inSection("coverage", "src", M.getSourceFileName()))
400     return false;
401   C = &(M.getContext());
402   DL = &M.getDataLayout();
403   CurModule = &M;
404   CurModuleUniqueId = getUniqueModuleId(CurModule);
405   TargetTriple = Triple(M.getTargetTriple());
406   FunctionGuardArray = nullptr;
407   Function8bitCounterArray = nullptr;
408   FunctionBoolArray = nullptr;
409   FunctionPCsArray = nullptr;
410   IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
411   IntptrPtrTy = PointerType::getUnqual(IntptrTy);
412   Type *VoidTy = Type::getVoidTy(*C);
413   IRBuilder<> IRB(*C);
414   Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
415   Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
416   Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
417   Int1PtrTy = PointerType::getUnqual(IRB.getInt1Ty());
418   Int64Ty = IRB.getInt64Ty();
419   Int32Ty = IRB.getInt32Ty();
420   Int16Ty = IRB.getInt16Ty();
421   Int8Ty = IRB.getInt8Ty();
422   Int1Ty = IRB.getInt1Ty();
423 
424   SanCovTracePCIndir =
425       M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy);
426   // Make sure smaller parameters are zero-extended to i64 if required by the
427   // target ABI.
428   AttributeList SanCovTraceCmpZeroExtAL;
429   SanCovTraceCmpZeroExtAL =
430       SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt);
431   SanCovTraceCmpZeroExtAL =
432       SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt);
433 
434   SanCovTraceCmpFunction[0] =
435       M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy,
436                             IRB.getInt8Ty(), IRB.getInt8Ty());
437   SanCovTraceCmpFunction[1] =
438       M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy,
439                             IRB.getInt16Ty(), IRB.getInt16Ty());
440   SanCovTraceCmpFunction[2] =
441       M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy,
442                             IRB.getInt32Ty(), IRB.getInt32Ty());
443   SanCovTraceCmpFunction[3] =
444       M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty);
445 
446   SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction(
447       SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty);
448   SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction(
449       SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty);
450   SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction(
451       SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty);
452   SanCovTraceConstCmpFunction[3] =
453       M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty);
454 
455   {
456     AttributeList AL;
457     AL = AL.addParamAttribute(*C, 0, Attribute::ZExt);
458     SanCovTraceDivFunction[0] =
459         M.getOrInsertFunction(SanCovTraceDiv4, AL, VoidTy, IRB.getInt32Ty());
460   }
461   SanCovTraceDivFunction[1] =
462       M.getOrInsertFunction(SanCovTraceDiv8, VoidTy, Int64Ty);
463   SanCovTraceGepFunction =
464       M.getOrInsertFunction(SanCovTraceGep, VoidTy, IntptrTy);
465   SanCovTraceSwitchFunction =
466       M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy);
467 
468   Constant *SanCovLowestStackConstant =
469       M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
470   SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant);
471   if (!SanCovLowestStack || SanCovLowestStack->getValueType() != IntptrTy) {
472     C->emitError(StringRef("'") + SanCovLowestStackName +
473                  "' should not be declared by the user");
474     return true;
475   }
476   SanCovLowestStack->setThreadLocalMode(
477       GlobalValue::ThreadLocalMode::InitialExecTLSModel);
478   if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
479     SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
480 
481   SanCovTracePC = M.getOrInsertFunction(SanCovTracePCName, VoidTy);
482   SanCovTracePCGuard =
483       M.getOrInsertFunction(SanCovTracePCGuardName, VoidTy, Int32PtrTy);
484 
485   for (auto &F : M)
486     instrumentFunction(F, DTCallback, PDTCallback);
487 
488   Function *Ctor = nullptr;
489 
490   if (FunctionGuardArray)
491     Ctor = CreateInitCallsForSections(M, SanCovModuleCtorTracePcGuardName,
492                                       SanCovTracePCGuardInitName, Int32Ty,
493                                       SanCovGuardsSectionName);
494   if (Function8bitCounterArray)
495     Ctor = CreateInitCallsForSections(M, SanCovModuleCtor8bitCountersName,
496                                       SanCov8bitCountersInitName, Int8Ty,
497                                       SanCovCountersSectionName);
498   if (FunctionBoolArray) {
499     Ctor = CreateInitCallsForSections(M, SanCovModuleCtorBoolFlagName,
500                                       SanCovBoolFlagInitName, Int1Ty,
501                                       SanCovBoolFlagSectionName);
502   }
503   if (Ctor && Options.PCTable) {
504     auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrTy);
505     FunctionCallee InitFunction = declareSanitizerInitFunction(
506         M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy});
507     IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
508     IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
509   }
510   appendToUsed(M, GlobalsToAppendToUsed);
511   appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
512   return true;
513 }
514 
515 // True if block has successors and it dominates all of them.
516 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
517   if (succ_empty(BB))
518     return false;
519 
520   return llvm::all_of(successors(BB), [&](const BasicBlock *SUCC) {
521     return DT->dominates(BB, SUCC);
522   });
523 }
524 
525 // True if block has predecessors and it postdominates all of them.
526 static bool isFullPostDominator(const BasicBlock *BB,
527                                 const PostDominatorTree *PDT) {
528   if (pred_empty(BB))
529     return false;
530 
531   return llvm::all_of(predecessors(BB), [&](const BasicBlock *PRED) {
532     return PDT->dominates(BB, PRED);
533   });
534 }
535 
536 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
537                                   const DominatorTree *DT,
538                                   const PostDominatorTree *PDT,
539                                   const SanitizerCoverageOptions &Options) {
540   // Don't insert coverage for blocks containing nothing but unreachable: we
541   // will never call __sanitizer_cov() for them, so counting them in
542   // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
543   // percentage. Also, unreachable instructions frequently have no debug
544   // locations.
545   if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime()))
546     return false;
547 
548   // Don't insert coverage into blocks without a valid insertion point
549   // (catchswitch blocks).
550   if (BB->getFirstInsertionPt() == BB->end())
551     return false;
552 
553   if (Options.NoPrune || &F.getEntryBlock() == BB)
554     return true;
555 
556   if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
557       &F.getEntryBlock() != BB)
558     return false;
559 
560   // Do not instrument full dominators, or full post-dominators with multiple
561   // predecessors.
562   return !isFullDominator(BB, DT)
563     && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
564 }
565 
566 
567 // Returns true iff From->To is a backedge.
568 // A twist here is that we treat From->To as a backedge if
569 //   * To dominates From or
570 //   * To->UniqueSuccessor dominates From
571 static bool IsBackEdge(BasicBlock *From, BasicBlock *To,
572                        const DominatorTree *DT) {
573   if (DT->dominates(To, From))
574     return true;
575   if (auto Next = To->getUniqueSuccessor())
576     if (DT->dominates(Next, From))
577       return true;
578   return false;
579 }
580 
581 // Prunes uninteresting Cmp instrumentation:
582 //   * CMP instructions that feed into loop backedge branch.
583 //
584 // Note that Cmp pruning is controlled by the same flag as the
585 // BB pruning.
586 static bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree *DT,
587                              const SanitizerCoverageOptions &Options) {
588   if (!Options.NoPrune)
589     if (CMP->hasOneUse())
590       if (auto BR = dyn_cast<BranchInst>(CMP->user_back()))
591         for (BasicBlock *B : BR->successors())
592           if (IsBackEdge(BR->getParent(), B, DT))
593             return false;
594   return true;
595 }
596 
597 void ModuleSanitizerCoverage::instrumentFunction(
598     Function &F, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
599   if (F.empty())
600     return;
601   if (F.getName().find(".module_ctor") != std::string::npos)
602     return; // Should not instrument sanitizer init functions.
603   if (F.getName().startswith("__sanitizer_"))
604     return; // Don't instrument __sanitizer_* callbacks.
605   // Don't touch available_externally functions, their actual body is elewhere.
606   if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
607     return;
608   // Don't instrument MSVC CRT configuration helpers. They may run before normal
609   // initialization.
610   if (F.getName() == "__local_stdio_printf_options" ||
611       F.getName() == "__local_stdio_scanf_options")
612     return;
613   if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
614     return;
615   // Don't instrument functions using SEH for now. Splitting basic blocks like
616   // we do for coverage breaks WinEHPrepare.
617   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
618   if (F.hasPersonalityFn() &&
619       isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
620     return;
621   if (Allowlist && !Allowlist->inSection("coverage", "fun", F.getName()))
622     return;
623   if (Blocklist && Blocklist->inSection("coverage", "fun", F.getName()))
624     return;
625   if (F.hasFnAttribute(Attribute::NoSanitizeCoverage))
626     return;
627   if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
628     SplitAllCriticalEdges(F, CriticalEdgeSplittingOptions().setIgnoreUnreachableDests());
629   SmallVector<Instruction *, 8> IndirCalls;
630   SmallVector<BasicBlock *, 16> BlocksToInstrument;
631   SmallVector<Instruction *, 8> CmpTraceTargets;
632   SmallVector<Instruction *, 8> SwitchTraceTargets;
633   SmallVector<BinaryOperator *, 8> DivTraceTargets;
634   SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
635 
636   const DominatorTree *DT = DTCallback(F);
637   const PostDominatorTree *PDT = PDTCallback(F);
638   bool IsLeafFunc = true;
639 
640   for (auto &BB : F) {
641     if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
642       BlocksToInstrument.push_back(&BB);
643     for (auto &Inst : BB) {
644       if (Options.IndirectCalls) {
645         CallBase *CB = dyn_cast<CallBase>(&Inst);
646         if (CB && !CB->getCalledFunction())
647           IndirCalls.push_back(&Inst);
648       }
649       if (Options.TraceCmp) {
650         if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst))
651           if (IsInterestingCmp(CMP, DT, Options))
652             CmpTraceTargets.push_back(&Inst);
653         if (isa<SwitchInst>(&Inst))
654           SwitchTraceTargets.push_back(&Inst);
655       }
656       if (Options.TraceDiv)
657         if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
658           if (BO->getOpcode() == Instruction::SDiv ||
659               BO->getOpcode() == Instruction::UDiv)
660             DivTraceTargets.push_back(BO);
661       if (Options.TraceGep)
662         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
663           GepTraceTargets.push_back(GEP);
664       if (Options.StackDepth)
665         if (isa<InvokeInst>(Inst) ||
666             (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
667           IsLeafFunc = false;
668     }
669   }
670 
671   InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
672   InjectCoverageForIndirectCalls(F, IndirCalls);
673   InjectTraceForCmp(F, CmpTraceTargets);
674   InjectTraceForSwitch(F, SwitchTraceTargets);
675   InjectTraceForDiv(F, DivTraceTargets);
676   InjectTraceForGep(F, GepTraceTargets);
677 }
678 
679 GlobalVariable *ModuleSanitizerCoverage::CreateFunctionLocalArrayInSection(
680     size_t NumElements, Function &F, Type *Ty, const char *Section) {
681   ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
682   auto Array = new GlobalVariable(
683       *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
684       Constant::getNullValue(ArrayTy), "__sancov_gen_");
685 
686   if (TargetTriple.supportsCOMDAT() &&
687       (TargetTriple.isOSBinFormatELF() || !F.isInterposable()))
688     if (auto Comdat = getOrCreateFunctionComdat(F, TargetTriple))
689       Array->setComdat(Comdat);
690   Array->setSection(getSectionName(Section));
691   Array->setAlignment(Align(DL->getTypeStoreSize(Ty).getFixedSize()));
692 
693   // sancov_pcs parallels the other metadata section(s). Optimizers (e.g.
694   // GlobalOpt/ConstantMerge) may not discard sancov_pcs and the other
695   // section(s) as a unit, so we conservatively retain all unconditionally in
696   // the compiler.
697   //
698   // With comdat (COFF/ELF), the linker can guarantee the associated sections
699   // will be retained or discarded as a unit, so llvm.compiler.used is
700   // sufficient. Otherwise, conservatively make all of them retained by the
701   // linker.
702   if (Array->hasComdat())
703     GlobalsToAppendToCompilerUsed.push_back(Array);
704   else
705     GlobalsToAppendToUsed.push_back(Array);
706 
707   return Array;
708 }
709 
710 GlobalVariable *
711 ModuleSanitizerCoverage::CreatePCArray(Function &F,
712                                        ArrayRef<BasicBlock *> AllBlocks) {
713   size_t N = AllBlocks.size();
714   assert(N);
715   SmallVector<Constant *, 32> PCs;
716   IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
717   for (size_t i = 0; i < N; i++) {
718     if (&F.getEntryBlock() == AllBlocks[i]) {
719       PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
720       PCs.push_back((Constant *)IRB.CreateIntToPtr(
721           ConstantInt::get(IntptrTy, 1), IntptrPtrTy));
722     } else {
723       PCs.push_back((Constant *)IRB.CreatePointerCast(
724           BlockAddress::get(AllBlocks[i]), IntptrPtrTy));
725       PCs.push_back((Constant *)IRB.CreateIntToPtr(
726           ConstantInt::get(IntptrTy, 0), IntptrPtrTy));
727     }
728   }
729   auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy,
730                                                     SanCovPCsSectionName);
731   PCArray->setInitializer(
732       ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs));
733   PCArray->setConstant(true);
734 
735   return PCArray;
736 }
737 
738 void ModuleSanitizerCoverage::CreateFunctionLocalArrays(
739     Function &F, ArrayRef<BasicBlock *> AllBlocks) {
740   if (Options.TracePCGuard)
741     FunctionGuardArray = CreateFunctionLocalArrayInSection(
742         AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
743 
744   if (Options.Inline8bitCounters)
745     Function8bitCounterArray = CreateFunctionLocalArrayInSection(
746         AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
747   if (Options.InlineBoolFlag)
748     FunctionBoolArray = CreateFunctionLocalArrayInSection(
749         AllBlocks.size(), F, Int1Ty, SanCovBoolFlagSectionName);
750 
751   if (Options.PCTable)
752     FunctionPCsArray = CreatePCArray(F, AllBlocks);
753 }
754 
755 bool ModuleSanitizerCoverage::InjectCoverage(Function &F,
756                                              ArrayRef<BasicBlock *> AllBlocks,
757                                              bool IsLeafFunc) {
758   if (AllBlocks.empty()) return false;
759   CreateFunctionLocalArrays(F, AllBlocks);
760   for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
761     InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
762   return true;
763 }
764 
765 // On every indirect call we call a run-time function
766 // __sanitizer_cov_indir_call* with two parameters:
767 //   - callee address,
768 //   - global cache array that contains CacheSize pointers (zero-initialized).
769 //     The cache is used to speed up recording the caller-callee pairs.
770 // The address of the caller is passed implicitly via caller PC.
771 // CacheSize is encoded in the name of the run-time function.
772 void ModuleSanitizerCoverage::InjectCoverageForIndirectCalls(
773     Function &F, ArrayRef<Instruction *> IndirCalls) {
774   if (IndirCalls.empty())
775     return;
776   assert(Options.TracePC || Options.TracePCGuard ||
777          Options.Inline8bitCounters || Options.InlineBoolFlag);
778   for (auto I : IndirCalls) {
779     IRBuilder<> IRB(I);
780     CallBase &CB = cast<CallBase>(*I);
781     Value *Callee = CB.getCalledOperand();
782     if (isa<InlineAsm>(Callee))
783       continue;
784     IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
785   }
786 }
787 
788 // For every switch statement we insert a call:
789 // __sanitizer_cov_trace_switch(CondValue,
790 //      {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
791 
792 void ModuleSanitizerCoverage::InjectTraceForSwitch(
793     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
794   for (auto I : SwitchTraceTargets) {
795     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
796       IRBuilder<> IRB(I);
797       SmallVector<Constant *, 16> Initializers;
798       Value *Cond = SI->getCondition();
799       if (Cond->getType()->getScalarSizeInBits() >
800           Int64Ty->getScalarSizeInBits())
801         continue;
802       Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
803       Initializers.push_back(
804           ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
805       if (Cond->getType()->getScalarSizeInBits() <
806           Int64Ty->getScalarSizeInBits())
807         Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
808       for (auto It : SI->cases()) {
809         Constant *C = It.getCaseValue();
810         if (C->getType()->getScalarSizeInBits() <
811             Int64Ty->getScalarSizeInBits())
812           C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
813         Initializers.push_back(C);
814       }
815       llvm::sort(drop_begin(Initializers, 2),
816                  [](const Constant *A, const Constant *B) {
817                    return cast<ConstantInt>(A)->getLimitedValue() <
818                           cast<ConstantInt>(B)->getLimitedValue();
819                  });
820       ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
821       GlobalVariable *GV = new GlobalVariable(
822           *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
823           ConstantArray::get(ArrayOfInt64Ty, Initializers),
824           "__sancov_gen_cov_switch_values");
825       IRB.CreateCall(SanCovTraceSwitchFunction,
826                      {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
827     }
828   }
829 }
830 
831 void ModuleSanitizerCoverage::InjectTraceForDiv(
832     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
833   for (auto BO : DivTraceTargets) {
834     IRBuilder<> IRB(BO);
835     Value *A1 = BO->getOperand(1);
836     if (isa<ConstantInt>(A1)) continue;
837     if (!A1->getType()->isIntegerTy())
838       continue;
839     uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
840     int CallbackIdx = TypeSize == 32 ? 0 :
841         TypeSize == 64 ? 1 : -1;
842     if (CallbackIdx < 0) continue;
843     auto Ty = Type::getIntNTy(*C, TypeSize);
844     IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
845                    {IRB.CreateIntCast(A1, Ty, true)});
846   }
847 }
848 
849 void ModuleSanitizerCoverage::InjectTraceForGep(
850     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
851   for (auto GEP : GepTraceTargets) {
852     IRBuilder<> IRB(GEP);
853     for (Use &Idx : GEP->indices())
854       if (!isa<ConstantInt>(Idx) && Idx->getType()->isIntegerTy())
855         IRB.CreateCall(SanCovTraceGepFunction,
856                        {IRB.CreateIntCast(Idx, IntptrTy, true)});
857   }
858 }
859 
860 void ModuleSanitizerCoverage::InjectTraceForCmp(
861     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
862   for (auto I : CmpTraceTargets) {
863     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
864       IRBuilder<> IRB(ICMP);
865       Value *A0 = ICMP->getOperand(0);
866       Value *A1 = ICMP->getOperand(1);
867       if (!A0->getType()->isIntegerTy())
868         continue;
869       uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
870       int CallbackIdx = TypeSize == 8 ? 0 :
871                         TypeSize == 16 ? 1 :
872                         TypeSize == 32 ? 2 :
873                         TypeSize == 64 ? 3 : -1;
874       if (CallbackIdx < 0) continue;
875       // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
876       auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
877       bool FirstIsConst = isa<ConstantInt>(A0);
878       bool SecondIsConst = isa<ConstantInt>(A1);
879       // If both are const, then we don't need such a comparison.
880       if (FirstIsConst && SecondIsConst) continue;
881       // If only one is const, then make it the first callback argument.
882       if (FirstIsConst || SecondIsConst) {
883         CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
884         if (SecondIsConst)
885           std::swap(A0, A1);
886       }
887 
888       auto Ty = Type::getIntNTy(*C, TypeSize);
889       IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
890               IRB.CreateIntCast(A1, Ty, true)});
891     }
892   }
893 }
894 
895 void ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
896                                                     size_t Idx,
897                                                     bool IsLeafFunc) {
898   BasicBlock::iterator IP = BB.getFirstInsertionPt();
899   bool IsEntryBB = &BB == &F.getEntryBlock();
900   DebugLoc EntryLoc;
901   if (IsEntryBB) {
902     if (auto SP = F.getSubprogram())
903       EntryLoc = DILocation::get(SP->getContext(), SP->getScopeLine(), 0, SP);
904     // Keep static allocas and llvm.localescape calls in the entry block.  Even
905     // if we aren't splitting the block, it's nice for allocas to be before
906     // calls.
907     IP = PrepareToSplitEntryBlock(BB, IP);
908   } else {
909     EntryLoc = IP->getDebugLoc();
910     if (!EntryLoc)
911       if (auto *SP = F.getSubprogram())
912         EntryLoc = DILocation::get(SP->getContext(), 0, 0, SP);
913   }
914 
915   IRBuilder<> IRB(&*IP);
916   IRB.SetCurrentDebugLocation(EntryLoc);
917   if (Options.TracePC) {
918     IRB.CreateCall(SanCovTracePC)
919         ->setCannotMerge(); // gets the PC using GET_CALLER_PC.
920   }
921   if (Options.TracePCGuard) {
922     auto GuardPtr = IRB.CreateIntToPtr(
923         IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
924                       ConstantInt::get(IntptrTy, Idx * 4)),
925         Int32PtrTy);
926     IRB.CreateCall(SanCovTracePCGuard, GuardPtr)->setCannotMerge();
927   }
928   if (Options.Inline8bitCounters) {
929     auto CounterPtr = IRB.CreateGEP(
930         Function8bitCounterArray->getValueType(), Function8bitCounterArray,
931         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
932     auto Load = IRB.CreateLoad(Int8Ty, CounterPtr);
933     auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
934     auto Store = IRB.CreateStore(Inc, CounterPtr);
935     SetNoSanitizeMetadata(Load);
936     SetNoSanitizeMetadata(Store);
937   }
938   if (Options.InlineBoolFlag) {
939     auto FlagPtr = IRB.CreateGEP(
940         FunctionBoolArray->getValueType(), FunctionBoolArray,
941         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
942     auto Load = IRB.CreateLoad(Int1Ty, FlagPtr);
943     auto ThenTerm =
944         SplitBlockAndInsertIfThen(IRB.CreateIsNull(Load), &*IP, false);
945     IRBuilder<> ThenIRB(ThenTerm);
946     auto Store = ThenIRB.CreateStore(ConstantInt::getTrue(Int1Ty), FlagPtr);
947     SetNoSanitizeMetadata(Load);
948     SetNoSanitizeMetadata(Store);
949   }
950   if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
951     // Check stack depth.  If it's the deepest so far, record it.
952     Module *M = F.getParent();
953     Function *GetFrameAddr = Intrinsic::getDeclaration(
954         M, Intrinsic::frameaddress,
955         IRB.getInt8PtrTy(M->getDataLayout().getAllocaAddrSpace()));
956     auto FrameAddrPtr =
957         IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
958     auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
959     auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack);
960     auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
961     auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false);
962     IRBuilder<> ThenIRB(ThenTerm);
963     auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
964     SetNoSanitizeMetadata(LowestStack);
965     SetNoSanitizeMetadata(Store);
966   }
967 }
968 
969 std::string
970 ModuleSanitizerCoverage::getSectionName(const std::string &Section) const {
971   if (TargetTriple.isOSBinFormatCOFF()) {
972     if (Section == SanCovCountersSectionName)
973       return ".SCOV$CM";
974     if (Section == SanCovBoolFlagSectionName)
975       return ".SCOV$BM";
976     if (Section == SanCovPCsSectionName)
977       return ".SCOVP$M";
978     return ".SCOV$GM"; // For SanCovGuardsSectionName.
979   }
980   if (TargetTriple.isOSBinFormatMachO())
981     return "__DATA,__" + Section;
982   return "__" + Section;
983 }
984 
985 std::string
986 ModuleSanitizerCoverage::getSectionStart(const std::string &Section) const {
987   if (TargetTriple.isOSBinFormatMachO())
988     return "\1section$start$__DATA$__" + Section;
989   return "__start___" + Section;
990 }
991 
992 std::string
993 ModuleSanitizerCoverage::getSectionEnd(const std::string &Section) const {
994   if (TargetTriple.isOSBinFormatMachO())
995     return "\1section$end$__DATA$__" + Section;
996   return "__stop___" + Section;
997 }
998 
999 char ModuleSanitizerCoverageLegacyPass::ID = 0;
1000 INITIALIZE_PASS_BEGIN(ModuleSanitizerCoverageLegacyPass, "sancov",
1001                       "Pass for instrumenting coverage on functions", false,
1002                       false)
1003 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
1004 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
1005 INITIALIZE_PASS_END(ModuleSanitizerCoverageLegacyPass, "sancov",
1006                     "Pass for instrumenting coverage on functions", false,
1007                     false)
1008 ModulePass *llvm::createModuleSanitizerCoverageLegacyPassPass(
1009     const SanitizerCoverageOptions &Options,
1010     const std::vector<std::string> &AllowlistFiles,
1011     const std::vector<std::string> &BlocklistFiles) {
1012   return new ModuleSanitizerCoverageLegacyPass(Options, AllowlistFiles,
1013                                                BlocklistFiles);
1014 }
1015