xref: /llvm-project/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp (revision 6fedc18c9c25568c5aba6c0a7aaf5d2406bc84eb)
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/GlobalsModRef.h"
17 #include "llvm/Analysis/PostDominators.h"
18 #include "llvm/IR/Constant.h"
19 #include "llvm/IR/DataLayout.h"
20 #include "llvm/IR/Dominators.h"
21 #include "llvm/IR/EHPersonalities.h"
22 #include "llvm/IR/Function.h"
23 #include "llvm/IR/GlobalVariable.h"
24 #include "llvm/IR/IRBuilder.h"
25 #include "llvm/IR/IntrinsicInst.h"
26 #include "llvm/IR/Intrinsics.h"
27 #include "llvm/IR/LLVMContext.h"
28 #include "llvm/IR/MDBuilder.h"
29 #include "llvm/IR/Module.h"
30 #include "llvm/IR/Type.h"
31 #include "llvm/Support/CommandLine.h"
32 #include "llvm/Support/SpecialCaseList.h"
33 #include "llvm/Support/VirtualFileSystem.h"
34 #include "llvm/TargetParser/Triple.h"
35 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
36 #include "llvm/Transforms/Utils/ModuleUtils.h"
37 
38 using namespace llvm;
39 
40 #define DEBUG_TYPE "sancov"
41 
42 const char SanCovTracePCIndirName[] = "__sanitizer_cov_trace_pc_indir";
43 const char SanCovTracePCName[] = "__sanitizer_cov_trace_pc";
44 const char SanCovTraceCmp1[] = "__sanitizer_cov_trace_cmp1";
45 const char SanCovTraceCmp2[] = "__sanitizer_cov_trace_cmp2";
46 const char SanCovTraceCmp4[] = "__sanitizer_cov_trace_cmp4";
47 const char SanCovTraceCmp8[] = "__sanitizer_cov_trace_cmp8";
48 const char SanCovTraceConstCmp1[] = "__sanitizer_cov_trace_const_cmp1";
49 const char SanCovTraceConstCmp2[] = "__sanitizer_cov_trace_const_cmp2";
50 const char SanCovTraceConstCmp4[] = "__sanitizer_cov_trace_const_cmp4";
51 const char SanCovTraceConstCmp8[] = "__sanitizer_cov_trace_const_cmp8";
52 const char SanCovLoad1[] = "__sanitizer_cov_load1";
53 const char SanCovLoad2[] = "__sanitizer_cov_load2";
54 const char SanCovLoad4[] = "__sanitizer_cov_load4";
55 const char SanCovLoad8[] = "__sanitizer_cov_load8";
56 const char SanCovLoad16[] = "__sanitizer_cov_load16";
57 const char SanCovStore1[] = "__sanitizer_cov_store1";
58 const char SanCovStore2[] = "__sanitizer_cov_store2";
59 const char SanCovStore4[] = "__sanitizer_cov_store4";
60 const char SanCovStore8[] = "__sanitizer_cov_store8";
61 const char SanCovStore16[] = "__sanitizer_cov_store16";
62 const char SanCovTraceDiv4[] = "__sanitizer_cov_trace_div4";
63 const char SanCovTraceDiv8[] = "__sanitizer_cov_trace_div8";
64 const char SanCovTraceGep[] = "__sanitizer_cov_trace_gep";
65 const char SanCovTraceSwitchName[] = "__sanitizer_cov_trace_switch";
66 const char SanCovModuleCtorTracePcGuardName[] =
67     "sancov.module_ctor_trace_pc_guard";
68 const char SanCovModuleCtor8bitCountersName[] =
69     "sancov.module_ctor_8bit_counters";
70 const char SanCovModuleCtorBoolFlagName[] = "sancov.module_ctor_bool_flag";
71 static const uint64_t SanCtorAndDtorPriority = 2;
72 
73 const char SanCovTracePCGuardName[] = "__sanitizer_cov_trace_pc_guard";
74 const char SanCovTracePCGuardInitName[] = "__sanitizer_cov_trace_pc_guard_init";
75 const char SanCov8bitCountersInitName[] = "__sanitizer_cov_8bit_counters_init";
76 const char SanCovBoolFlagInitName[] = "__sanitizer_cov_bool_flag_init";
77 const char SanCovPCsInitName[] = "__sanitizer_cov_pcs_init";
78 const char SanCovCFsInitName[] = "__sanitizer_cov_cfs_init";
79 
80 const char SanCovGuardsSectionName[] = "sancov_guards";
81 const char SanCovCountersSectionName[] = "sancov_cntrs";
82 const char SanCovBoolFlagSectionName[] = "sancov_bools";
83 const char SanCovPCsSectionName[] = "sancov_pcs";
84 const char SanCovCFsSectionName[] = "sancov_cfs";
85 
86 const char SanCovLowestStackName[] = "__sancov_lowest_stack";
87 
88 static cl::opt<int> ClCoverageLevel(
89     "sanitizer-coverage-level",
90     cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
91              "3: all blocks and critical edges"),
92     cl::Hidden);
93 
94 static cl::opt<bool> ClTracePC("sanitizer-coverage-trace-pc",
95                                cl::desc("Experimental pc tracing"), cl::Hidden);
96 
97 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard",
98                                     cl::desc("pc tracing with a guard"),
99                                     cl::Hidden);
100 
101 // If true, we create a global variable that contains PCs of all instrumented
102 // BBs, put this global into a named section, and pass this section's bounds
103 // to __sanitizer_cov_pcs_init.
104 // This way the coverage instrumentation does not need to acquire the PCs
105 // at run-time. Works with trace-pc-guard, inline-8bit-counters, and
106 // inline-bool-flag.
107 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table",
108                                      cl::desc("create a static PC table"),
109                                      cl::Hidden);
110 
111 static cl::opt<bool>
112     ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters",
113                          cl::desc("increments 8-bit counter for every edge"),
114                          cl::Hidden);
115 
116 static cl::opt<bool>
117     ClInlineBoolFlag("sanitizer-coverage-inline-bool-flag",
118                      cl::desc("sets a boolean flag for every edge"),
119                      cl::Hidden);
120 
121 static cl::opt<bool>
122     ClCMPTracing("sanitizer-coverage-trace-compares",
123                  cl::desc("Tracing of CMP and similar instructions"),
124                  cl::Hidden);
125 
126 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs",
127                                   cl::desc("Tracing of DIV instructions"),
128                                   cl::Hidden);
129 
130 static cl::opt<bool> ClLoadTracing("sanitizer-coverage-trace-loads",
131                                    cl::desc("Tracing of load instructions"),
132                                    cl::Hidden);
133 
134 static cl::opt<bool> ClStoreTracing("sanitizer-coverage-trace-stores",
135                                     cl::desc("Tracing of store instructions"),
136                                     cl::Hidden);
137 
138 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps",
139                                   cl::desc("Tracing of GEP instructions"),
140                                   cl::Hidden);
141 
142 static cl::opt<bool>
143     ClPruneBlocks("sanitizer-coverage-prune-blocks",
144                   cl::desc("Reduce the number of instrumented blocks"),
145                   cl::Hidden, cl::init(true));
146 
147 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth",
148                                   cl::desc("max stack depth tracing"),
149                                   cl::Hidden);
150 
151 static cl::opt<bool>
152     ClCollectCF("sanitizer-coverage-control-flow",
153                 cl::desc("collect control flow for each function"), cl::Hidden);
154 
155 namespace {
156 
157 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
158   SanitizerCoverageOptions Res;
159   switch (LegacyCoverageLevel) {
160   case 0:
161     Res.CoverageType = SanitizerCoverageOptions::SCK_None;
162     break;
163   case 1:
164     Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
165     break;
166   case 2:
167     Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
168     break;
169   case 3:
170     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
171     break;
172   case 4:
173     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
174     Res.IndirectCalls = true;
175     break;
176   }
177   return Res;
178 }
179 
180 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
181   // Sets CoverageType and IndirectCalls.
182   SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
183   Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
184   Options.IndirectCalls |= CLOpts.IndirectCalls;
185   Options.TraceCmp |= ClCMPTracing;
186   Options.TraceDiv |= ClDIVTracing;
187   Options.TraceGep |= ClGEPTracing;
188   Options.TracePC |= ClTracePC;
189   Options.TracePCGuard |= ClTracePCGuard;
190   Options.Inline8bitCounters |= ClInline8bitCounters;
191   Options.InlineBoolFlag |= ClInlineBoolFlag;
192   Options.PCTable |= ClCreatePCTable;
193   Options.NoPrune |= !ClPruneBlocks;
194   Options.StackDepth |= ClStackDepth;
195   Options.TraceLoads |= ClLoadTracing;
196   Options.TraceStores |= ClStoreTracing;
197   if (!Options.TracePCGuard && !Options.TracePC &&
198       !Options.Inline8bitCounters && !Options.StackDepth &&
199       !Options.InlineBoolFlag && !Options.TraceLoads && !Options.TraceStores)
200     Options.TracePCGuard = true; // TracePCGuard is default.
201   Options.CollectControlFlow |= ClCollectCF;
202   return Options;
203 }
204 
205 class ModuleSanitizerCoverage {
206 public:
207   using DomTreeCallback = function_ref<const DominatorTree &(Function &F)>;
208   using PostDomTreeCallback =
209       function_ref<const PostDominatorTree &(Function &F)>;
210 
211   ModuleSanitizerCoverage(Module &M, DomTreeCallback DTCallback,
212                           PostDomTreeCallback PDTCallback,
213                           const SanitizerCoverageOptions &Options,
214                           const SpecialCaseList *Allowlist,
215                           const SpecialCaseList *Blocklist)
216       : M(M), DTCallback(DTCallback), PDTCallback(PDTCallback),
217         Options(Options), Allowlist(Allowlist), Blocklist(Blocklist) {}
218 
219   bool instrumentModule();
220 
221 private:
222   void createFunctionControlFlow(Function &F);
223   void instrumentFunction(Function &F);
224   void InjectCoverageForIndirectCalls(Function &F,
225                                       ArrayRef<Instruction *> IndirCalls);
226   void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
227   void InjectTraceForDiv(Function &F,
228                          ArrayRef<BinaryOperator *> DivTraceTargets);
229   void InjectTraceForGep(Function &F,
230                          ArrayRef<GetElementPtrInst *> GepTraceTargets);
231   void InjectTraceForLoadsAndStores(Function &F, ArrayRef<LoadInst *> Loads,
232                                     ArrayRef<StoreInst *> Stores);
233   void InjectTraceForSwitch(Function &F,
234                             ArrayRef<Instruction *> SwitchTraceTargets);
235   bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
236                       bool IsLeafFunc = true);
237   GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
238                                                     Function &F, Type *Ty,
239                                                     const char *Section);
240   GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
241   void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
242   void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
243                              bool IsLeafFunc = true);
244   Function *CreateInitCallsForSections(Module &M, const char *CtorName,
245                                        const char *InitFunctionName, Type *Ty,
246                                        const char *Section);
247   std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section,
248                                                 Type *Ty);
249 
250   std::string getSectionName(const std::string &Section) const;
251   std::string getSectionStart(const std::string &Section) const;
252   std::string getSectionEnd(const std::string &Section) const;
253 
254   Module &M;
255   DomTreeCallback DTCallback;
256   PostDomTreeCallback PDTCallback;
257 
258   FunctionCallee SanCovTracePCIndir;
259   FunctionCallee SanCovTracePC, SanCovTracePCGuard;
260   std::array<FunctionCallee, 4> SanCovTraceCmpFunction;
261   std::array<FunctionCallee, 4> SanCovTraceConstCmpFunction;
262   std::array<FunctionCallee, 5> SanCovLoadFunction;
263   std::array<FunctionCallee, 5> SanCovStoreFunction;
264   std::array<FunctionCallee, 2> SanCovTraceDivFunction;
265   FunctionCallee SanCovTraceGepFunction;
266   FunctionCallee SanCovTraceSwitchFunction;
267   GlobalVariable *SanCovLowestStack;
268   Type *PtrTy, *IntptrTy, *Int64Ty, *Int32Ty, *Int16Ty, *Int8Ty, *Int1Ty;
269   Module *CurModule;
270   std::string CurModuleUniqueId;
271   Triple TargetTriple;
272   LLVMContext *C;
273   const DataLayout *DL;
274 
275   GlobalVariable *FunctionGuardArray;  // for trace-pc-guard.
276   GlobalVariable *Function8bitCounterArray;  // for inline-8bit-counters.
277   GlobalVariable *FunctionBoolArray;         // for inline-bool-flag.
278   GlobalVariable *FunctionPCsArray;  // for pc-table.
279   GlobalVariable *FunctionCFsArray;  // for control flow table
280   SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
281   SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
282 
283   SanitizerCoverageOptions Options;
284 
285   const SpecialCaseList *Allowlist;
286   const SpecialCaseList *Blocklist;
287 };
288 } // namespace
289 
290 PreservedAnalyses SanitizerCoveragePass::run(Module &M,
291                                              ModuleAnalysisManager &MAM) {
292   auto &FAM = MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
293   auto DTCallback = [&FAM](Function &F) -> const DominatorTree & {
294     return FAM.getResult<DominatorTreeAnalysis>(F);
295   };
296   auto PDTCallback = [&FAM](Function &F) -> const PostDominatorTree & {
297     return FAM.getResult<PostDominatorTreeAnalysis>(F);
298   };
299   ModuleSanitizerCoverage ModuleSancov(M, DTCallback, PDTCallback,
300                                        OverrideFromCL(Options), Allowlist.get(),
301                                        Blocklist.get());
302   if (!ModuleSancov.instrumentModule())
303     return PreservedAnalyses::all();
304 
305   PreservedAnalyses PA = PreservedAnalyses::none();
306   // GlobalsAA is considered stateless and does not get invalidated unless
307   // explicitly invalidated; PreservedAnalyses::none() is not enough. Sanitizers
308   // make changes that require GlobalsAA to be invalidated.
309   PA.abandon<GlobalsAA>();
310   return PA;
311 }
312 
313 std::pair<Value *, Value *>
314 ModuleSanitizerCoverage::CreateSecStartEnd(Module &M, const char *Section,
315                                            Type *Ty) {
316   // Use ExternalWeak so that if all sections are discarded due to section
317   // garbage collection, the linker will not report undefined symbol errors.
318   // Windows defines the start/stop symbols in compiler-rt so no need for
319   // ExternalWeak.
320   GlobalValue::LinkageTypes Linkage = TargetTriple.isOSBinFormatCOFF()
321                                           ? GlobalVariable::ExternalLinkage
322                                           : GlobalVariable::ExternalWeakLinkage;
323   GlobalVariable *SecStart =
324       new GlobalVariable(M, Ty, false, Linkage, nullptr,
325                          getSectionStart(Section));
326   SecStart->setVisibility(GlobalValue::HiddenVisibility);
327   GlobalVariable *SecEnd =
328       new GlobalVariable(M, Ty, false, Linkage, nullptr,
329                          getSectionEnd(Section));
330   SecEnd->setVisibility(GlobalValue::HiddenVisibility);
331   IRBuilder<> IRB(M.getContext());
332   if (!TargetTriple.isOSBinFormatCOFF())
333     return std::make_pair(SecStart, SecEnd);
334 
335   // Account for the fact that on windows-msvc __start_* symbols actually
336   // point to a uint64_t before the start of the array.
337   auto GEP =
338       IRB.CreatePtrAdd(SecStart, ConstantInt::get(IntptrTy, sizeof(uint64_t)));
339   return std::make_pair(GEP, SecEnd);
340 }
341 
342 Function *ModuleSanitizerCoverage::CreateInitCallsForSections(
343     Module &M, const char *CtorName, const char *InitFunctionName, Type *Ty,
344     const char *Section) {
345   auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
346   auto SecStart = SecStartEnd.first;
347   auto SecEnd = SecStartEnd.second;
348   Function *CtorFunc;
349   std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
350       M, CtorName, InitFunctionName, {PtrTy, PtrTy}, {SecStart, SecEnd});
351   assert(CtorFunc->getName() == CtorName);
352 
353   if (TargetTriple.supportsCOMDAT()) {
354     // Use comdat to dedup CtorFunc.
355     CtorFunc->setComdat(M.getOrInsertComdat(CtorName));
356     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
357   } else {
358     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
359   }
360 
361   if (TargetTriple.isOSBinFormatCOFF()) {
362     // In COFF files, if the contructors are set as COMDAT (they are because
363     // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
364     // functions and data) is used, the constructors get stripped. To prevent
365     // this, give the constructors weak ODR linkage and ensure the linker knows
366     // to include the sancov constructor. This way the linker can deduplicate
367     // the constructors but always leave one copy.
368     CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
369   }
370   return CtorFunc;
371 }
372 
373 bool ModuleSanitizerCoverage::instrumentModule() {
374   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
375     return false;
376   if (Allowlist &&
377       !Allowlist->inSection("coverage", "src", M.getSourceFileName()))
378     return false;
379   if (Blocklist &&
380       Blocklist->inSection("coverage", "src", M.getSourceFileName()))
381     return false;
382   C = &(M.getContext());
383   DL = &M.getDataLayout();
384   CurModule = &M;
385   CurModuleUniqueId = getUniqueModuleId(CurModule);
386   TargetTriple = Triple(M.getTargetTriple());
387   FunctionGuardArray = nullptr;
388   Function8bitCounterArray = nullptr;
389   FunctionBoolArray = nullptr;
390   FunctionPCsArray = nullptr;
391   FunctionCFsArray = nullptr;
392   IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
393   PtrTy = PointerType::getUnqual(*C);
394   Type *VoidTy = Type::getVoidTy(*C);
395   IRBuilder<> IRB(*C);
396   Int64Ty = IRB.getInt64Ty();
397   Int32Ty = IRB.getInt32Ty();
398   Int16Ty = IRB.getInt16Ty();
399   Int8Ty = IRB.getInt8Ty();
400   Int1Ty = IRB.getInt1Ty();
401 
402   SanCovTracePCIndir =
403       M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy);
404   // Make sure smaller parameters are zero-extended to i64 if required by the
405   // target ABI.
406   AttributeList SanCovTraceCmpZeroExtAL;
407   SanCovTraceCmpZeroExtAL =
408       SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt);
409   SanCovTraceCmpZeroExtAL =
410       SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt);
411 
412   SanCovTraceCmpFunction[0] =
413       M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy,
414                             IRB.getInt8Ty(), IRB.getInt8Ty());
415   SanCovTraceCmpFunction[1] =
416       M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy,
417                             IRB.getInt16Ty(), IRB.getInt16Ty());
418   SanCovTraceCmpFunction[2] =
419       M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy,
420                             IRB.getInt32Ty(), IRB.getInt32Ty());
421   SanCovTraceCmpFunction[3] =
422       M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty);
423 
424   SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction(
425       SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty);
426   SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction(
427       SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty);
428   SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction(
429       SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty);
430   SanCovTraceConstCmpFunction[3] =
431       M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty);
432 
433   // Loads.
434   SanCovLoadFunction[0] = M.getOrInsertFunction(SanCovLoad1, VoidTy, PtrTy);
435   SanCovLoadFunction[1] =
436       M.getOrInsertFunction(SanCovLoad2, VoidTy, PtrTy);
437   SanCovLoadFunction[2] =
438       M.getOrInsertFunction(SanCovLoad4, VoidTy, PtrTy);
439   SanCovLoadFunction[3] =
440       M.getOrInsertFunction(SanCovLoad8, VoidTy, PtrTy);
441   SanCovLoadFunction[4] =
442       M.getOrInsertFunction(SanCovLoad16, VoidTy, PtrTy);
443   // Stores.
444   SanCovStoreFunction[0] =
445       M.getOrInsertFunction(SanCovStore1, VoidTy, PtrTy);
446   SanCovStoreFunction[1] =
447       M.getOrInsertFunction(SanCovStore2, VoidTy, PtrTy);
448   SanCovStoreFunction[2] =
449       M.getOrInsertFunction(SanCovStore4, VoidTy, PtrTy);
450   SanCovStoreFunction[3] =
451       M.getOrInsertFunction(SanCovStore8, VoidTy, PtrTy);
452   SanCovStoreFunction[4] =
453       M.getOrInsertFunction(SanCovStore16, VoidTy, PtrTy);
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, PtrTy);
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, PtrTy);
484 
485   for (auto &F : M)
486     instrumentFunction(F);
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, {PtrTy, PtrTy});
507     IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
508     IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
509   }
510 
511   if (Ctor && Options.CollectControlFlow) {
512     auto SecStartEnd = CreateSecStartEnd(M, SanCovCFsSectionName, IntptrTy);
513     FunctionCallee InitFunction = declareSanitizerInitFunction(
514         M, SanCovCFsInitName, {PtrTy, PtrTy});
515     IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
516     IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
517   }
518 
519   appendToUsed(M, GlobalsToAppendToUsed);
520   appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
521   return true;
522 }
523 
524 // True if block has successors and it dominates all of them.
525 static bool isFullDominator(const BasicBlock *BB, const DominatorTree &DT) {
526   if (succ_empty(BB))
527     return false;
528 
529   return llvm::all_of(successors(BB), [&](const BasicBlock *SUCC) {
530     return DT.dominates(BB, SUCC);
531   });
532 }
533 
534 // True if block has predecessors and it postdominates all of them.
535 static bool isFullPostDominator(const BasicBlock *BB,
536                                 const PostDominatorTree &PDT) {
537   if (pred_empty(BB))
538     return false;
539 
540   return llvm::all_of(predecessors(BB), [&](const BasicBlock *PRED) {
541     return PDT.dominates(BB, PRED);
542   });
543 }
544 
545 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
546                                   const DominatorTree &DT,
547                                   const PostDominatorTree &PDT,
548                                   const SanitizerCoverageOptions &Options) {
549   // Don't insert coverage for blocks containing nothing but unreachable: we
550   // will never call __sanitizer_cov() for them, so counting them in
551   // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
552   // percentage. Also, unreachable instructions frequently have no debug
553   // locations.
554   if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime()))
555     return false;
556 
557   // Don't insert coverage into blocks without a valid insertion point
558   // (catchswitch blocks).
559   if (BB->getFirstInsertionPt() == BB->end())
560     return false;
561 
562   if (Options.NoPrune || &F.getEntryBlock() == BB)
563     return true;
564 
565   if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
566       &F.getEntryBlock() != BB)
567     return false;
568 
569   // Do not instrument full dominators, or full post-dominators with multiple
570   // predecessors.
571   return !isFullDominator(BB, DT)
572     && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
573 }
574 
575 // Returns true iff From->To is a backedge.
576 // A twist here is that we treat From->To as a backedge if
577 //   * To dominates From or
578 //   * To->UniqueSuccessor dominates From
579 static bool IsBackEdge(BasicBlock *From, BasicBlock *To,
580                        const DominatorTree &DT) {
581   if (DT.dominates(To, From))
582     return true;
583   if (auto Next = To->getUniqueSuccessor())
584     if (DT.dominates(Next, From))
585       return true;
586   return false;
587 }
588 
589 // Prunes uninteresting Cmp instrumentation:
590 //   * CMP instructions that feed into loop backedge branch.
591 //
592 // Note that Cmp pruning is controlled by the same flag as the
593 // BB pruning.
594 static bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree &DT,
595                              const SanitizerCoverageOptions &Options) {
596   if (!Options.NoPrune)
597     if (CMP->hasOneUse())
598       if (auto BR = dyn_cast<BranchInst>(CMP->user_back()))
599         for (BasicBlock *B : BR->successors())
600           if (IsBackEdge(BR->getParent(), B, DT))
601             return false;
602   return true;
603 }
604 
605 void ModuleSanitizerCoverage::instrumentFunction(Function &F) {
606   if (F.empty())
607     return;
608   if (F.getName().contains(".module_ctor"))
609     return; // Should not instrument sanitizer init functions.
610   if (F.getName().starts_with("__sanitizer_"))
611     return; // Don't instrument __sanitizer_* callbacks.
612   // Don't touch available_externally functions, their actual body is elewhere.
613   if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
614     return;
615   // Don't instrument MSVC CRT configuration helpers. They may run before normal
616   // initialization.
617   if (F.getName() == "__local_stdio_printf_options" ||
618       F.getName() == "__local_stdio_scanf_options")
619     return;
620   if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
621     return;
622   // Don't instrument functions using SEH for now. Splitting basic blocks like
623   // we do for coverage breaks WinEHPrepare.
624   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
625   if (F.hasPersonalityFn() &&
626       isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
627     return;
628   if (Allowlist && !Allowlist->inSection("coverage", "fun", F.getName()))
629     return;
630   if (Blocklist && Blocklist->inSection("coverage", "fun", F.getName()))
631     return;
632   if (F.hasFnAttribute(Attribute::NoSanitizeCoverage))
633     return;
634   if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge) {
635     SplitAllCriticalEdges(
636         F, CriticalEdgeSplittingOptions().setIgnoreUnreachableDests());
637   }
638   SmallVector<Instruction *, 8> IndirCalls;
639   SmallVector<BasicBlock *, 16> BlocksToInstrument;
640   SmallVector<Instruction *, 8> CmpTraceTargets;
641   SmallVector<Instruction *, 8> SwitchTraceTargets;
642   SmallVector<BinaryOperator *, 8> DivTraceTargets;
643   SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
644   SmallVector<LoadInst *, 8> Loads;
645   SmallVector<StoreInst *, 8> Stores;
646 
647   const DominatorTree &DT = DTCallback(F);
648   const PostDominatorTree &PDT = PDTCallback(F);
649   bool IsLeafFunc = true;
650 
651   for (auto &BB : F) {
652     if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
653       BlocksToInstrument.push_back(&BB);
654     for (auto &Inst : BB) {
655       if (Options.IndirectCalls) {
656         CallBase *CB = dyn_cast<CallBase>(&Inst);
657         if (CB && CB->isIndirectCall())
658           IndirCalls.push_back(&Inst);
659       }
660       if (Options.TraceCmp) {
661         if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst))
662           if (IsInterestingCmp(CMP, DT, Options))
663             CmpTraceTargets.push_back(&Inst);
664         if (isa<SwitchInst>(&Inst))
665           SwitchTraceTargets.push_back(&Inst);
666       }
667       if (Options.TraceDiv)
668         if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
669           if (BO->getOpcode() == Instruction::SDiv ||
670               BO->getOpcode() == Instruction::UDiv)
671             DivTraceTargets.push_back(BO);
672       if (Options.TraceGep)
673         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
674           GepTraceTargets.push_back(GEP);
675       if (Options.TraceLoads)
676         if (LoadInst *LI = dyn_cast<LoadInst>(&Inst))
677           Loads.push_back(LI);
678       if (Options.TraceStores)
679         if (StoreInst *SI = dyn_cast<StoreInst>(&Inst))
680           Stores.push_back(SI);
681       if (Options.StackDepth)
682         if (isa<InvokeInst>(Inst) ||
683             (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
684           IsLeafFunc = false;
685     }
686   }
687 
688   if (Options.CollectControlFlow)
689     createFunctionControlFlow(F);
690 
691   InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
692   InjectCoverageForIndirectCalls(F, IndirCalls);
693   InjectTraceForCmp(F, CmpTraceTargets);
694   InjectTraceForSwitch(F, SwitchTraceTargets);
695   InjectTraceForDiv(F, DivTraceTargets);
696   InjectTraceForGep(F, GepTraceTargets);
697   InjectTraceForLoadsAndStores(F, Loads, Stores);
698 }
699 
700 GlobalVariable *ModuleSanitizerCoverage::CreateFunctionLocalArrayInSection(
701     size_t NumElements, Function &F, Type *Ty, const char *Section) {
702   ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
703   auto Array = new GlobalVariable(
704       *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
705       Constant::getNullValue(ArrayTy), "__sancov_gen_");
706 
707   if (TargetTriple.supportsCOMDAT() &&
708       (TargetTriple.isOSBinFormatELF() || !F.isInterposable()))
709     if (auto Comdat = getOrCreateFunctionComdat(F, TargetTriple))
710       Array->setComdat(Comdat);
711   Array->setSection(getSectionName(Section));
712   Array->setAlignment(Align(DL->getTypeStoreSize(Ty).getFixedValue()));
713 
714   // sancov_pcs parallels the other metadata section(s). Optimizers (e.g.
715   // GlobalOpt/ConstantMerge) may not discard sancov_pcs and the other
716   // section(s) as a unit, so we conservatively retain all unconditionally in
717   // the compiler.
718   //
719   // With comdat (COFF/ELF), the linker can guarantee the associated sections
720   // will be retained or discarded as a unit, so llvm.compiler.used is
721   // sufficient. Otherwise, conservatively make all of them retained by the
722   // linker.
723   if (Array->hasComdat())
724     GlobalsToAppendToCompilerUsed.push_back(Array);
725   else
726     GlobalsToAppendToUsed.push_back(Array);
727 
728   return Array;
729 }
730 
731 GlobalVariable *
732 ModuleSanitizerCoverage::CreatePCArray(Function &F,
733                                        ArrayRef<BasicBlock *> AllBlocks) {
734   size_t N = AllBlocks.size();
735   assert(N);
736   SmallVector<Constant *, 32> PCs;
737   IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
738   for (size_t i = 0; i < N; i++) {
739     if (&F.getEntryBlock() == AllBlocks[i]) {
740       PCs.push_back((Constant *)IRB.CreatePointerCast(&F, PtrTy));
741       PCs.push_back((Constant *)IRB.CreateIntToPtr(
742           ConstantInt::get(IntptrTy, 1), PtrTy));
743     } else {
744       PCs.push_back((Constant *)IRB.CreatePointerCast(
745           BlockAddress::get(AllBlocks[i]), PtrTy));
746       PCs.push_back(Constant::getNullValue(PtrTy));
747     }
748   }
749   auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, PtrTy,
750                                                     SanCovPCsSectionName);
751   PCArray->setInitializer(
752       ConstantArray::get(ArrayType::get(PtrTy, N * 2), PCs));
753   PCArray->setConstant(true);
754 
755   return PCArray;
756 }
757 
758 void ModuleSanitizerCoverage::CreateFunctionLocalArrays(
759     Function &F, ArrayRef<BasicBlock *> AllBlocks) {
760   if (Options.TracePCGuard)
761     FunctionGuardArray = CreateFunctionLocalArrayInSection(
762         AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
763 
764   if (Options.Inline8bitCounters)
765     Function8bitCounterArray = CreateFunctionLocalArrayInSection(
766         AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
767   if (Options.InlineBoolFlag)
768     FunctionBoolArray = CreateFunctionLocalArrayInSection(
769         AllBlocks.size(), F, Int1Ty, SanCovBoolFlagSectionName);
770 
771   if (Options.PCTable)
772     FunctionPCsArray = CreatePCArray(F, AllBlocks);
773 }
774 
775 bool ModuleSanitizerCoverage::InjectCoverage(Function &F,
776                                              ArrayRef<BasicBlock *> AllBlocks,
777                                              bool IsLeafFunc) {
778   if (AllBlocks.empty()) return false;
779   CreateFunctionLocalArrays(F, AllBlocks);
780   for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
781     InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
782   return true;
783 }
784 
785 // On every indirect call we call a run-time function
786 // __sanitizer_cov_indir_call* with two parameters:
787 //   - callee address,
788 //   - global cache array that contains CacheSize pointers (zero-initialized).
789 //     The cache is used to speed up recording the caller-callee pairs.
790 // The address of the caller is passed implicitly via caller PC.
791 // CacheSize is encoded in the name of the run-time function.
792 void ModuleSanitizerCoverage::InjectCoverageForIndirectCalls(
793     Function &F, ArrayRef<Instruction *> IndirCalls) {
794   if (IndirCalls.empty())
795     return;
796   assert(Options.TracePC || Options.TracePCGuard ||
797          Options.Inline8bitCounters || Options.InlineBoolFlag);
798   for (auto *I : IndirCalls) {
799     InstrumentationIRBuilder IRB(I);
800     CallBase &CB = cast<CallBase>(*I);
801     Value *Callee = CB.getCalledOperand();
802     if (isa<InlineAsm>(Callee))
803       continue;
804     IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
805   }
806 }
807 
808 // For every switch statement we insert a call:
809 // __sanitizer_cov_trace_switch(CondValue,
810 //      {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
811 
812 void ModuleSanitizerCoverage::InjectTraceForSwitch(
813     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
814   for (auto *I : SwitchTraceTargets) {
815     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
816       InstrumentationIRBuilder IRB(I);
817       SmallVector<Constant *, 16> Initializers;
818       Value *Cond = SI->getCondition();
819       if (Cond->getType()->getScalarSizeInBits() >
820           Int64Ty->getScalarSizeInBits())
821         continue;
822       Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
823       Initializers.push_back(
824           ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
825       if (Cond->getType()->getScalarSizeInBits() <
826           Int64Ty->getScalarSizeInBits())
827         Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
828       for (auto It : SI->cases()) {
829         ConstantInt *C = It.getCaseValue();
830         if (C->getType()->getScalarSizeInBits() < 64)
831           C = ConstantInt::get(C->getContext(), C->getValue().zext(64));
832         Initializers.push_back(C);
833       }
834       llvm::sort(drop_begin(Initializers, 2),
835                  [](const Constant *A, const Constant *B) {
836                    return cast<ConstantInt>(A)->getLimitedValue() <
837                           cast<ConstantInt>(B)->getLimitedValue();
838                  });
839       ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
840       GlobalVariable *GV = new GlobalVariable(
841           *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
842           ConstantArray::get(ArrayOfInt64Ty, Initializers),
843           "__sancov_gen_cov_switch_values");
844       IRB.CreateCall(SanCovTraceSwitchFunction, {Cond, GV});
845     }
846   }
847 }
848 
849 void ModuleSanitizerCoverage::InjectTraceForDiv(
850     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
851   for (auto *BO : DivTraceTargets) {
852     InstrumentationIRBuilder IRB(BO);
853     Value *A1 = BO->getOperand(1);
854     if (isa<ConstantInt>(A1)) continue;
855     if (!A1->getType()->isIntegerTy())
856       continue;
857     uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
858     int CallbackIdx = TypeSize == 32 ? 0 :
859         TypeSize == 64 ? 1 : -1;
860     if (CallbackIdx < 0) continue;
861     auto Ty = Type::getIntNTy(*C, TypeSize);
862     IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
863                    {IRB.CreateIntCast(A1, Ty, true)});
864   }
865 }
866 
867 void ModuleSanitizerCoverage::InjectTraceForGep(
868     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
869   for (auto *GEP : GepTraceTargets) {
870     InstrumentationIRBuilder IRB(GEP);
871     for (Use &Idx : GEP->indices())
872       if (!isa<ConstantInt>(Idx) && Idx->getType()->isIntegerTy())
873         IRB.CreateCall(SanCovTraceGepFunction,
874                        {IRB.CreateIntCast(Idx, IntptrTy, true)});
875   }
876 }
877 
878 void ModuleSanitizerCoverage::InjectTraceForLoadsAndStores(
879     Function &, ArrayRef<LoadInst *> Loads, ArrayRef<StoreInst *> Stores) {
880   auto CallbackIdx = [&](Type *ElementTy) -> int {
881     uint64_t TypeSize = DL->getTypeStoreSizeInBits(ElementTy);
882     return TypeSize == 8     ? 0
883            : TypeSize == 16  ? 1
884            : TypeSize == 32  ? 2
885            : TypeSize == 64  ? 3
886            : TypeSize == 128 ? 4
887                              : -1;
888   };
889   for (auto *LI : Loads) {
890     InstrumentationIRBuilder IRB(LI);
891     auto Ptr = LI->getPointerOperand();
892     int Idx = CallbackIdx(LI->getType());
893     if (Idx < 0)
894       continue;
895     IRB.CreateCall(SanCovLoadFunction[Idx], Ptr);
896   }
897   for (auto *SI : Stores) {
898     InstrumentationIRBuilder IRB(SI);
899     auto Ptr = SI->getPointerOperand();
900     int Idx = CallbackIdx(SI->getValueOperand()->getType());
901     if (Idx < 0)
902       continue;
903     IRB.CreateCall(SanCovStoreFunction[Idx], Ptr);
904   }
905 }
906 
907 void ModuleSanitizerCoverage::InjectTraceForCmp(
908     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
909   for (auto *I : CmpTraceTargets) {
910     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
911       InstrumentationIRBuilder IRB(ICMP);
912       Value *A0 = ICMP->getOperand(0);
913       Value *A1 = ICMP->getOperand(1);
914       if (!A0->getType()->isIntegerTy())
915         continue;
916       uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
917       int CallbackIdx = TypeSize == 8 ? 0 :
918                         TypeSize == 16 ? 1 :
919                         TypeSize == 32 ? 2 :
920                         TypeSize == 64 ? 3 : -1;
921       if (CallbackIdx < 0) continue;
922       // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
923       auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
924       bool FirstIsConst = isa<ConstantInt>(A0);
925       bool SecondIsConst = isa<ConstantInt>(A1);
926       // If both are const, then we don't need such a comparison.
927       if (FirstIsConst && SecondIsConst) continue;
928       // If only one is const, then make it the first callback argument.
929       if (FirstIsConst || SecondIsConst) {
930         CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
931         if (SecondIsConst)
932           std::swap(A0, A1);
933       }
934 
935       auto Ty = Type::getIntNTy(*C, TypeSize);
936       IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
937               IRB.CreateIntCast(A1, Ty, true)});
938     }
939   }
940 }
941 
942 void ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
943                                                     size_t Idx,
944                                                     bool IsLeafFunc) {
945   BasicBlock::iterator IP = BB.getFirstInsertionPt();
946   bool IsEntryBB = &BB == &F.getEntryBlock();
947   DebugLoc EntryLoc;
948   if (IsEntryBB) {
949     if (auto SP = F.getSubprogram())
950       EntryLoc = DILocation::get(SP->getContext(), SP->getScopeLine(), 0, SP);
951     // Keep static allocas and llvm.localescape calls in the entry block.  Even
952     // if we aren't splitting the block, it's nice for allocas to be before
953     // calls.
954     IP = PrepareToSplitEntryBlock(BB, IP);
955   }
956 
957   InstrumentationIRBuilder IRB(&*IP);
958   if (EntryLoc)
959     IRB.SetCurrentDebugLocation(EntryLoc);
960   if (Options.TracePC) {
961     IRB.CreateCall(SanCovTracePC)
962         ->setCannotMerge(); // gets the PC using GET_CALLER_PC.
963   }
964   if (Options.TracePCGuard) {
965     auto GuardPtr = IRB.CreateIntToPtr(
966         IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
967                       ConstantInt::get(IntptrTy, Idx * 4)),
968         PtrTy);
969     IRB.CreateCall(SanCovTracePCGuard, GuardPtr)->setCannotMerge();
970   }
971   if (Options.Inline8bitCounters) {
972     auto CounterPtr = IRB.CreateGEP(
973         Function8bitCounterArray->getValueType(), Function8bitCounterArray,
974         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
975     auto Load = IRB.CreateLoad(Int8Ty, CounterPtr);
976     auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
977     auto Store = IRB.CreateStore(Inc, CounterPtr);
978     Load->setNoSanitizeMetadata();
979     Store->setNoSanitizeMetadata();
980   }
981   if (Options.InlineBoolFlag) {
982     auto FlagPtr = IRB.CreateGEP(
983         FunctionBoolArray->getValueType(), FunctionBoolArray,
984         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
985     auto Load = IRB.CreateLoad(Int1Ty, FlagPtr);
986     auto ThenTerm = SplitBlockAndInsertIfThen(
987         IRB.CreateIsNull(Load), &*IP, false,
988         MDBuilder(IRB.getContext()).createUnlikelyBranchWeights());
989     IRBuilder<> ThenIRB(ThenTerm);
990     auto Store = ThenIRB.CreateStore(ConstantInt::getTrue(Int1Ty), FlagPtr);
991     Load->setNoSanitizeMetadata();
992     Store->setNoSanitizeMetadata();
993   }
994   if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
995     // Check stack depth.  If it's the deepest so far, record it.
996     Module *M = F.getParent();
997     Function *GetFrameAddr = Intrinsic::getDeclaration(
998         M, Intrinsic::frameaddress,
999         IRB.getPtrTy(M->getDataLayout().getAllocaAddrSpace()));
1000     auto FrameAddrPtr =
1001         IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
1002     auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
1003     auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack);
1004     auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
1005     auto ThenTerm = SplitBlockAndInsertIfThen(
1006         IsStackLower, &*IP, false,
1007         MDBuilder(IRB.getContext()).createUnlikelyBranchWeights());
1008     IRBuilder<> ThenIRB(ThenTerm);
1009     auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
1010     LowestStack->setNoSanitizeMetadata();
1011     Store->setNoSanitizeMetadata();
1012   }
1013 }
1014 
1015 std::string
1016 ModuleSanitizerCoverage::getSectionName(const std::string &Section) const {
1017   if (TargetTriple.isOSBinFormatCOFF()) {
1018     if (Section == SanCovCountersSectionName)
1019       return ".SCOV$CM";
1020     if (Section == SanCovBoolFlagSectionName)
1021       return ".SCOV$BM";
1022     if (Section == SanCovPCsSectionName)
1023       return ".SCOVP$M";
1024     return ".SCOV$GM"; // For SanCovGuardsSectionName.
1025   }
1026   if (TargetTriple.isOSBinFormatMachO())
1027     return "__DATA,__" + Section;
1028   return "__" + Section;
1029 }
1030 
1031 std::string
1032 ModuleSanitizerCoverage::getSectionStart(const std::string &Section) const {
1033   if (TargetTriple.isOSBinFormatMachO())
1034     return "\1section$start$__DATA$__" + Section;
1035   return "__start___" + Section;
1036 }
1037 
1038 std::string
1039 ModuleSanitizerCoverage::getSectionEnd(const std::string &Section) const {
1040   if (TargetTriple.isOSBinFormatMachO())
1041     return "\1section$end$__DATA$__" + Section;
1042   return "__stop___" + Section;
1043 }
1044 
1045 void ModuleSanitizerCoverage::createFunctionControlFlow(Function &F) {
1046   SmallVector<Constant *, 32> CFs;
1047   IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
1048 
1049   for (auto &BB : F) {
1050     // blockaddress can not be used on function's entry block.
1051     if (&BB == &F.getEntryBlock())
1052       CFs.push_back((Constant *)IRB.CreatePointerCast(&F, PtrTy));
1053     else
1054       CFs.push_back((Constant *)IRB.CreatePointerCast(BlockAddress::get(&BB),
1055                                                       PtrTy));
1056 
1057     for (auto SuccBB : successors(&BB)) {
1058       assert(SuccBB != &F.getEntryBlock());
1059       CFs.push_back((Constant *)IRB.CreatePointerCast(BlockAddress::get(SuccBB),
1060                                                       PtrTy));
1061     }
1062 
1063     CFs.push_back((Constant *)Constant::getNullValue(PtrTy));
1064 
1065     for (auto &Inst : BB) {
1066       if (CallBase *CB = dyn_cast<CallBase>(&Inst)) {
1067         if (CB->isIndirectCall()) {
1068           // TODO(navidem): handle indirect calls, for now mark its existence.
1069           CFs.push_back((Constant *)IRB.CreateIntToPtr(
1070               ConstantInt::get(IntptrTy, -1), PtrTy));
1071         } else {
1072           auto CalledF = CB->getCalledFunction();
1073           if (CalledF && !CalledF->isIntrinsic())
1074             CFs.push_back(
1075                 (Constant *)IRB.CreatePointerCast(CalledF, PtrTy));
1076         }
1077       }
1078     }
1079 
1080     CFs.push_back((Constant *)Constant::getNullValue(PtrTy));
1081   }
1082 
1083   FunctionCFsArray = CreateFunctionLocalArrayInSection(
1084       CFs.size(), F, PtrTy, SanCovCFsSectionName);
1085   FunctionCFsArray->setInitializer(
1086       ConstantArray::get(ArrayType::get(PtrTy, CFs.size()), CFs));
1087   FunctionCFsArray->setConstant(true);
1088 }
1089