xref: /llvm-project/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp (revision 927af63fddb8e34f23b2974f812156767988ec5f) 
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/Constants.h"
20 #include "llvm/IR/DataLayout.h"
21 #include "llvm/IR/Dominators.h"
22 #include "llvm/IR/EHPersonalities.h"
23 #include "llvm/IR/Function.h"
24 #include "llvm/IR/GlobalVariable.h"
25 #include "llvm/IR/IRBuilder.h"
26 #include "llvm/IR/IntrinsicInst.h"
27 #include "llvm/IR/Intrinsics.h"
28 #include "llvm/IR/LLVMContext.h"
29 #include "llvm/IR/MDBuilder.h"
30 #include "llvm/IR/Module.h"
31 #include "llvm/IR/Type.h"
32 #include "llvm/IR/ValueSymbolTable.h"
33 #include "llvm/InitializePasses.h"
34 #include "llvm/Support/CommandLine.h"
35 #include "llvm/Support/SpecialCaseList.h"
36 #include "llvm/Support/VirtualFileSystem.h"
37 #include "llvm/TargetParser/Triple.h"
38 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
39 #include "llvm/Transforms/Utils/ModuleUtils.h"
40 
41 using namespace llvm;
42 
43 #define DEBUG_TYPE "sancov"
44 
45 const char SanCovTracePCIndirName[] = "__sanitizer_cov_trace_pc_indir";
46 const char SanCovTracePCName[] = "__sanitizer_cov_trace_pc";
47 const char SanCovTraceCmp1[] = "__sanitizer_cov_trace_cmp1";
48 const char SanCovTraceCmp2[] = "__sanitizer_cov_trace_cmp2";
49 const char SanCovTraceCmp4[] = "__sanitizer_cov_trace_cmp4";
50 const char SanCovTraceCmp8[] = "__sanitizer_cov_trace_cmp8";
51 const char SanCovTraceConstCmp1[] = "__sanitizer_cov_trace_const_cmp1";
52 const char SanCovTraceConstCmp2[] = "__sanitizer_cov_trace_const_cmp2";
53 const char SanCovTraceConstCmp4[] = "__sanitizer_cov_trace_const_cmp4";
54 const char SanCovTraceConstCmp8[] = "__sanitizer_cov_trace_const_cmp8";
55 const char SanCovLoad1[] = "__sanitizer_cov_load1";
56 const char SanCovLoad2[] = "__sanitizer_cov_load2";
57 const char SanCovLoad4[] = "__sanitizer_cov_load4";
58 const char SanCovLoad8[] = "__sanitizer_cov_load8";
59 const char SanCovLoad16[] = "__sanitizer_cov_load16";
60 const char SanCovStore1[] = "__sanitizer_cov_store1";
61 const char SanCovStore2[] = "__sanitizer_cov_store2";
62 const char SanCovStore4[] = "__sanitizer_cov_store4";
63 const char SanCovStore8[] = "__sanitizer_cov_store8";
64 const char SanCovStore16[] = "__sanitizer_cov_store16";
65 const char SanCovTraceDiv4[] = "__sanitizer_cov_trace_div4";
66 const char SanCovTraceDiv8[] = "__sanitizer_cov_trace_div8";
67 const char SanCovTraceGep[] = "__sanitizer_cov_trace_gep";
68 const char SanCovTraceSwitchName[] = "__sanitizer_cov_trace_switch";
69 const char SanCovModuleCtorTracePcGuardName[] =
70     "sancov.module_ctor_trace_pc_guard";
71 const char SanCovModuleCtor8bitCountersName[] =
72     "sancov.module_ctor_8bit_counters";
73 const char SanCovModuleCtorBoolFlagName[] = "sancov.module_ctor_bool_flag";
74 static const uint64_t SanCtorAndDtorPriority = 2;
75 
76 const char SanCovTracePCGuardName[] = "__sanitizer_cov_trace_pc_guard";
77 const char SanCovTracePCGuardInitName[] = "__sanitizer_cov_trace_pc_guard_init";
78 const char SanCov8bitCountersInitName[] = "__sanitizer_cov_8bit_counters_init";
79 const char SanCovBoolFlagInitName[] = "__sanitizer_cov_bool_flag_init";
80 const char SanCovPCsInitName[] = "__sanitizer_cov_pcs_init";
81 const char SanCovCFsInitName[] = "__sanitizer_cov_cfs_init";
82 
83 const char SanCovGuardsSectionName[] = "sancov_guards";
84 const char SanCovCountersSectionName[] = "sancov_cntrs";
85 const char SanCovBoolFlagSectionName[] = "sancov_bools";
86 const char SanCovPCsSectionName[] = "sancov_pcs";
87 const char SanCovCFsSectionName[] = "sancov_cfs";
88 const char SanCovCallbackGateSectionName[] = "sancov_gate";
89 
90 const char SanCovLowestStackName[] = "__sancov_lowest_stack";
91 const char SanCovCallbackGateName[] = "__sancov_should_track";
92 
93 static cl::opt<int> ClCoverageLevel(
94     "sanitizer-coverage-level",
95     cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
96              "3: all blocks and critical edges"),
97     cl::Hidden);
98 
99 static cl::opt<bool> ClTracePC("sanitizer-coverage-trace-pc",
100                                cl::desc("Experimental pc tracing"), cl::Hidden);
101 
102 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard",
103                                     cl::desc("pc tracing with a guard"),
104                                     cl::Hidden);
105 
106 // If true, we create a global variable that contains PCs of all instrumented
107 // BBs, put this global into a named section, and pass this section's bounds
108 // to __sanitizer_cov_pcs_init.
109 // This way the coverage instrumentation does not need to acquire the PCs
110 // at run-time. Works with trace-pc-guard, inline-8bit-counters, and
111 // inline-bool-flag.
112 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table",
113                                      cl::desc("create a static PC table"),
114                                      cl::Hidden);
115 
116 static cl::opt<bool>
117     ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters",
118                          cl::desc("increments 8-bit counter for every edge"),
119                          cl::Hidden);
120 
121 static cl::opt<bool>
122     ClInlineBoolFlag("sanitizer-coverage-inline-bool-flag",
123                      cl::desc("sets a boolean flag for every edge"),
124                      cl::Hidden);
125 
126 static cl::opt<bool>
127     ClCMPTracing("sanitizer-coverage-trace-compares",
128                  cl::desc("Tracing of CMP and similar instructions"),
129                  cl::Hidden);
130 
131 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs",
132                                   cl::desc("Tracing of DIV instructions"),
133                                   cl::Hidden);
134 
135 static cl::opt<bool> ClLoadTracing("sanitizer-coverage-trace-loads",
136                                    cl::desc("Tracing of load instructions"),
137                                    cl::Hidden);
138 
139 static cl::opt<bool> ClStoreTracing("sanitizer-coverage-trace-stores",
140                                     cl::desc("Tracing of store instructions"),
141                                     cl::Hidden);
142 
143 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps",
144                                   cl::desc("Tracing of GEP instructions"),
145                                   cl::Hidden);
146 
147 static cl::opt<bool>
148     ClPruneBlocks("sanitizer-coverage-prune-blocks",
149                   cl::desc("Reduce the number of instrumented blocks"),
150                   cl::Hidden, cl::init(true));
151 
152 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth",
153                                   cl::desc("max stack depth tracing"),
154                                   cl::Hidden);
155 
156 static cl::opt<bool>
157     ClCollectCF("sanitizer-coverage-control-flow",
158                 cl::desc("collect control flow for each function"), cl::Hidden);
159 
160 static cl::opt<bool> ClGatedCallbacks(
161     "sanitizer-coverage-gated-trace-callbacks",
162     cl::desc("Gate the invocation of the tracing callbacks on a global "
163              "variable. Currently only supported for trace-pc-guard."),
164     cl::Hidden, cl::init(false));
165 
166 namespace {
167 
168 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
169   SanitizerCoverageOptions Res;
170   switch (LegacyCoverageLevel) {
171   case 0:
172     Res.CoverageType = SanitizerCoverageOptions::SCK_None;
173     break;
174   case 1:
175     Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
176     break;
177   case 2:
178     Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
179     break;
180   case 3:
181     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
182     break;
183   case 4:
184     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
185     Res.IndirectCalls = true;
186     break;
187   }
188   return Res;
189 }
190 
191 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
192   // Sets CoverageType and IndirectCalls.
193   SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
194   Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
195   Options.IndirectCalls |= CLOpts.IndirectCalls;
196   Options.TraceCmp |= ClCMPTracing;
197   Options.TraceDiv |= ClDIVTracing;
198   Options.TraceGep |= ClGEPTracing;
199   Options.TracePC |= ClTracePC;
200   Options.TracePCGuard |= ClTracePCGuard;
201   Options.Inline8bitCounters |= ClInline8bitCounters;
202   Options.InlineBoolFlag |= ClInlineBoolFlag;
203   Options.PCTable |= ClCreatePCTable;
204   Options.NoPrune |= !ClPruneBlocks;
205   Options.StackDepth |= ClStackDepth;
206   Options.TraceLoads |= ClLoadTracing;
207   Options.TraceStores |= ClStoreTracing;
208   Options.GatedCallbacks |= ClGatedCallbacks;
209   if (!Options.TracePCGuard && !Options.TracePC &&
210       !Options.Inline8bitCounters && !Options.StackDepth &&
211       !Options.InlineBoolFlag && !Options.TraceLoads && !Options.TraceStores)
212     Options.TracePCGuard = true; // TracePCGuard is default.
213   Options.CollectControlFlow |= ClCollectCF;
214   return Options;
215 }
216 
217 class ModuleSanitizerCoverage {
218 public:
219   using DomTreeCallback = function_ref<const DominatorTree &(Function &F)>;
220   using PostDomTreeCallback =
221       function_ref<const PostDominatorTree &(Function &F)>;
222 
223   ModuleSanitizerCoverage(Module &M, DomTreeCallback DTCallback,
224                           PostDomTreeCallback PDTCallback,
225                           const SanitizerCoverageOptions &Options,
226                           const SpecialCaseList *Allowlist,
227                           const SpecialCaseList *Blocklist)
228       : M(M), DTCallback(DTCallback), PDTCallback(PDTCallback),
229         Options(Options), Allowlist(Allowlist), Blocklist(Blocklist) {}
230 
231   bool instrumentModule();
232 
233 private:
234   void createFunctionControlFlow(Function &F);
235   void instrumentFunction(Function &F);
236   void InjectCoverageForIndirectCalls(Function &F,
237                                       ArrayRef<Instruction *> IndirCalls);
238   void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
239   void InjectTraceForDiv(Function &F,
240                          ArrayRef<BinaryOperator *> DivTraceTargets);
241   void InjectTraceForGep(Function &F,
242                          ArrayRef<GetElementPtrInst *> GepTraceTargets);
243   void InjectTraceForLoadsAndStores(Function &F, ArrayRef<LoadInst *> Loads,
244                                     ArrayRef<StoreInst *> Stores);
245   void InjectTraceForSwitch(Function &F,
246                             ArrayRef<Instruction *> SwitchTraceTargets);
247   bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
248                       bool IsLeafFunc = true);
249   GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
250                                                     Function &F, Type *Ty,
251                                                     const char *Section);
252   GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
253   void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
254   Value *CreateFunctionLocalGateCmp(IRBuilder<> &IRB);
255   void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
256                              Value *&FunctionGateCmp, bool IsLeafFunc = true);
257   Function *CreateInitCallsForSections(Module &M, const char *CtorName,
258                                        const char *InitFunctionName, Type *Ty,
259                                        const char *Section);
260   std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section,
261                                                 Type *Ty);
262 
263   std::string getSectionName(const std::string &Section) const;
264   std::string getSectionStart(const std::string &Section) const;
265   std::string getSectionEnd(const std::string &Section) const;
266 
267   Module &M;
268   DomTreeCallback DTCallback;
269   PostDomTreeCallback PDTCallback;
270 
271   FunctionCallee SanCovTracePCIndir;
272   FunctionCallee SanCovTracePC, SanCovTracePCGuard;
273   std::array<FunctionCallee, 4> SanCovTraceCmpFunction;
274   std::array<FunctionCallee, 4> SanCovTraceConstCmpFunction;
275   std::array<FunctionCallee, 5> SanCovLoadFunction;
276   std::array<FunctionCallee, 5> SanCovStoreFunction;
277   std::array<FunctionCallee, 2> SanCovTraceDivFunction;
278   FunctionCallee SanCovTraceGepFunction;
279   FunctionCallee SanCovTraceSwitchFunction;
280   GlobalVariable *SanCovLowestStack;
281   GlobalVariable *SanCovCallbackGate;
282   Type *PtrTy, *IntptrTy, *Int64Ty, *Int32Ty, *Int16Ty, *Int8Ty, *Int1Ty;
283   Module *CurModule;
284   std::string CurModuleUniqueId;
285   Triple TargetTriple;
286   LLVMContext *C;
287   const DataLayout *DL;
288 
289   GlobalVariable *FunctionGuardArray;  // for trace-pc-guard.
290   GlobalVariable *Function8bitCounterArray;  // for inline-8bit-counters.
291   GlobalVariable *FunctionBoolArray;         // for inline-bool-flag.
292   GlobalVariable *FunctionPCsArray;  // for pc-table.
293   GlobalVariable *FunctionCFsArray;  // for control flow table
294   SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
295   SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
296 
297   SanitizerCoverageOptions Options;
298 
299   const SpecialCaseList *Allowlist;
300   const SpecialCaseList *Blocklist;
301 };
302 } // namespace
303 
304 PreservedAnalyses SanitizerCoveragePass::run(Module &M,
305                                              ModuleAnalysisManager &MAM) {
306   auto &FAM = MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
307   auto DTCallback = [&FAM](Function &F) -> const DominatorTree & {
308     return FAM.getResult<DominatorTreeAnalysis>(F);
309   };
310   auto PDTCallback = [&FAM](Function &F) -> const PostDominatorTree & {
311     return FAM.getResult<PostDominatorTreeAnalysis>(F);
312   };
313   ModuleSanitizerCoverage ModuleSancov(M, DTCallback, PDTCallback,
314                                        OverrideFromCL(Options), Allowlist.get(),
315                                        Blocklist.get());
316   if (!ModuleSancov.instrumentModule())
317     return PreservedAnalyses::all();
318 
319   PreservedAnalyses PA = PreservedAnalyses::none();
320   // GlobalsAA is considered stateless and does not get invalidated unless
321   // explicitly invalidated; PreservedAnalyses::none() is not enough. Sanitizers
322   // make changes that require GlobalsAA to be invalidated.
323   PA.abandon<GlobalsAA>();
324   return PA;
325 }
326 
327 std::pair<Value *, Value *>
328 ModuleSanitizerCoverage::CreateSecStartEnd(Module &M, const char *Section,
329                                            Type *Ty) {
330   // Use ExternalWeak so that if all sections are discarded due to section
331   // garbage collection, the linker will not report undefined symbol errors.
332   // Windows defines the start/stop symbols in compiler-rt so no need for
333   // ExternalWeak.
334   GlobalValue::LinkageTypes Linkage = TargetTriple.isOSBinFormatCOFF()
335                                           ? GlobalVariable::ExternalLinkage
336                                           : GlobalVariable::ExternalWeakLinkage;
337   GlobalVariable *SecStart =
338       new GlobalVariable(M, Ty, false, Linkage, nullptr,
339                          getSectionStart(Section));
340   SecStart->setVisibility(GlobalValue::HiddenVisibility);
341   GlobalVariable *SecEnd =
342       new GlobalVariable(M, Ty, false, Linkage, nullptr,
343                          getSectionEnd(Section));
344   SecEnd->setVisibility(GlobalValue::HiddenVisibility);
345   IRBuilder<> IRB(M.getContext());
346   if (!TargetTriple.isOSBinFormatCOFF())
347     return std::make_pair(SecStart, SecEnd);
348 
349   // Account for the fact that on windows-msvc __start_* symbols actually
350   // point to a uint64_t before the start of the array.
351   auto GEP =
352       IRB.CreatePtrAdd(SecStart, ConstantInt::get(IntptrTy, sizeof(uint64_t)));
353   return std::make_pair(GEP, SecEnd);
354 }
355 
356 Function *ModuleSanitizerCoverage::CreateInitCallsForSections(
357     Module &M, const char *CtorName, const char *InitFunctionName, Type *Ty,
358     const char *Section) {
359   auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
360   auto SecStart = SecStartEnd.first;
361   auto SecEnd = SecStartEnd.second;
362   Function *CtorFunc;
363   std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
364       M, CtorName, InitFunctionName, {PtrTy, PtrTy}, {SecStart, SecEnd});
365   assert(CtorFunc->getName() == CtorName);
366 
367   if (TargetTriple.supportsCOMDAT()) {
368     // Use comdat to dedup CtorFunc.
369     CtorFunc->setComdat(M.getOrInsertComdat(CtorName));
370     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
371   } else {
372     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
373   }
374 
375   if (TargetTriple.isOSBinFormatCOFF()) {
376     // In COFF files, if the contructors are set as COMDAT (they are because
377     // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
378     // functions and data) is used, the constructors get stripped. To prevent
379     // this, give the constructors weak ODR linkage and ensure the linker knows
380     // to include the sancov constructor. This way the linker can deduplicate
381     // the constructors but always leave one copy.
382     CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
383   }
384   return CtorFunc;
385 }
386 
387 bool ModuleSanitizerCoverage::instrumentModule() {
388   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
389     return false;
390   if (Allowlist &&
391       !Allowlist->inSection("coverage", "src", M.getSourceFileName()))
392     return false;
393   if (Blocklist &&
394       Blocklist->inSection("coverage", "src", M.getSourceFileName()))
395     return false;
396   C = &(M.getContext());
397   DL = &M.getDataLayout();
398   CurModule = &M;
399   CurModuleUniqueId = getUniqueModuleId(CurModule);
400   TargetTriple = Triple(M.getTargetTriple());
401   FunctionGuardArray = nullptr;
402   Function8bitCounterArray = nullptr;
403   FunctionBoolArray = nullptr;
404   FunctionPCsArray = nullptr;
405   FunctionCFsArray = nullptr;
406   IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
407   PtrTy = PointerType::getUnqual(*C);
408   Type *VoidTy = Type::getVoidTy(*C);
409   IRBuilder<> IRB(*C);
410   Int64Ty = IRB.getInt64Ty();
411   Int32Ty = IRB.getInt32Ty();
412   Int16Ty = IRB.getInt16Ty();
413   Int8Ty = IRB.getInt8Ty();
414   Int1Ty = IRB.getInt1Ty();
415 
416   SanCovTracePCIndir =
417       M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy);
418   // Make sure smaller parameters are zero-extended to i64 if required by the
419   // target ABI.
420   AttributeList SanCovTraceCmpZeroExtAL;
421   SanCovTraceCmpZeroExtAL =
422       SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt);
423   SanCovTraceCmpZeroExtAL =
424       SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt);
425 
426   SanCovTraceCmpFunction[0] =
427       M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy,
428                             IRB.getInt8Ty(), IRB.getInt8Ty());
429   SanCovTraceCmpFunction[1] =
430       M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy,
431                             IRB.getInt16Ty(), IRB.getInt16Ty());
432   SanCovTraceCmpFunction[2] =
433       M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy,
434                             IRB.getInt32Ty(), IRB.getInt32Ty());
435   SanCovTraceCmpFunction[3] =
436       M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty);
437 
438   SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction(
439       SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty);
440   SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction(
441       SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty);
442   SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction(
443       SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty);
444   SanCovTraceConstCmpFunction[3] =
445       M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty);
446 
447   // Loads.
448   SanCovLoadFunction[0] = M.getOrInsertFunction(SanCovLoad1, VoidTy, PtrTy);
449   SanCovLoadFunction[1] =
450       M.getOrInsertFunction(SanCovLoad2, VoidTy, PtrTy);
451   SanCovLoadFunction[2] =
452       M.getOrInsertFunction(SanCovLoad4, VoidTy, PtrTy);
453   SanCovLoadFunction[3] =
454       M.getOrInsertFunction(SanCovLoad8, VoidTy, PtrTy);
455   SanCovLoadFunction[4] =
456       M.getOrInsertFunction(SanCovLoad16, VoidTy, PtrTy);
457   // Stores.
458   SanCovStoreFunction[0] =
459       M.getOrInsertFunction(SanCovStore1, VoidTy, PtrTy);
460   SanCovStoreFunction[1] =
461       M.getOrInsertFunction(SanCovStore2, VoidTy, PtrTy);
462   SanCovStoreFunction[2] =
463       M.getOrInsertFunction(SanCovStore4, VoidTy, PtrTy);
464   SanCovStoreFunction[3] =
465       M.getOrInsertFunction(SanCovStore8, VoidTy, PtrTy);
466   SanCovStoreFunction[4] =
467       M.getOrInsertFunction(SanCovStore16, VoidTy, PtrTy);
468 
469   {
470     AttributeList AL;
471     AL = AL.addParamAttribute(*C, 0, Attribute::ZExt);
472     SanCovTraceDivFunction[0] =
473         M.getOrInsertFunction(SanCovTraceDiv4, AL, VoidTy, IRB.getInt32Ty());
474   }
475   SanCovTraceDivFunction[1] =
476       M.getOrInsertFunction(SanCovTraceDiv8, VoidTy, Int64Ty);
477   SanCovTraceGepFunction =
478       M.getOrInsertFunction(SanCovTraceGep, VoidTy, IntptrTy);
479   SanCovTraceSwitchFunction =
480       M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, PtrTy);
481 
482   Constant *SanCovLowestStackConstant =
483       M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
484   SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant);
485   if (!SanCovLowestStack || SanCovLowestStack->getValueType() != IntptrTy) {
486     C->emitError(StringRef("'") + SanCovLowestStackName +
487                  "' should not be declared by the user");
488     return true;
489   }
490   SanCovLowestStack->setThreadLocalMode(
491       GlobalValue::ThreadLocalMode::InitialExecTLSModel);
492   if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
493     SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
494 
495   if (Options.GatedCallbacks) {
496     if (!Options.TracePCGuard) {
497       C->emitError(StringRef("'") + ClGatedCallbacks.ArgStr +
498                    "' is only supported with trace-pc-guard");
499       return true;
500     }
501 
502     SanCovCallbackGate = cast<GlobalVariable>(
503         M.getOrInsertGlobal(SanCovCallbackGateName, Int64Ty));
504     SanCovCallbackGate->setSection(
505         getSectionName(SanCovCallbackGateSectionName));
506     SanCovCallbackGate->setInitializer(Constant::getNullValue(Int64Ty));
507     SanCovCallbackGate->setLinkage(GlobalVariable::LinkOnceAnyLinkage);
508     SanCovCallbackGate->setVisibility(GlobalVariable::HiddenVisibility);
509     appendToCompilerUsed(M, SanCovCallbackGate);
510   }
511 
512   SanCovTracePC = M.getOrInsertFunction(SanCovTracePCName, VoidTy);
513   SanCovTracePCGuard =
514       M.getOrInsertFunction(SanCovTracePCGuardName, VoidTy, PtrTy);
515 
516   for (auto &F : M)
517     instrumentFunction(F);
518 
519   Function *Ctor = nullptr;
520 
521   if (FunctionGuardArray)
522     Ctor = CreateInitCallsForSections(M, SanCovModuleCtorTracePcGuardName,
523                                       SanCovTracePCGuardInitName, Int32Ty,
524                                       SanCovGuardsSectionName);
525   if (Function8bitCounterArray)
526     Ctor = CreateInitCallsForSections(M, SanCovModuleCtor8bitCountersName,
527                                       SanCov8bitCountersInitName, Int8Ty,
528                                       SanCovCountersSectionName);
529   if (FunctionBoolArray) {
530     Ctor = CreateInitCallsForSections(M, SanCovModuleCtorBoolFlagName,
531                                       SanCovBoolFlagInitName, Int1Ty,
532                                       SanCovBoolFlagSectionName);
533   }
534   if (Ctor && Options.PCTable) {
535     auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrTy);
536     FunctionCallee InitFunction = declareSanitizerInitFunction(
537         M, SanCovPCsInitName, {PtrTy, PtrTy});
538     IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
539     IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
540   }
541 
542   if (Ctor && Options.CollectControlFlow) {
543     auto SecStartEnd = CreateSecStartEnd(M, SanCovCFsSectionName, IntptrTy);
544     FunctionCallee InitFunction = declareSanitizerInitFunction(
545         M, SanCovCFsInitName, {PtrTy, PtrTy});
546     IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
547     IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
548   }
549 
550   appendToUsed(M, GlobalsToAppendToUsed);
551   appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
552   return true;
553 }
554 
555 // True if block has successors and it dominates all of them.
556 static bool isFullDominator(const BasicBlock *BB, const DominatorTree &DT) {
557   if (succ_empty(BB))
558     return false;
559 
560   return llvm::all_of(successors(BB), [&](const BasicBlock *SUCC) {
561     return DT.dominates(BB, SUCC);
562   });
563 }
564 
565 // True if block has predecessors and it postdominates all of them.
566 static bool isFullPostDominator(const BasicBlock *BB,
567                                 const PostDominatorTree &PDT) {
568   if (pred_empty(BB))
569     return false;
570 
571   return llvm::all_of(predecessors(BB), [&](const BasicBlock *PRED) {
572     return PDT.dominates(BB, PRED);
573   });
574 }
575 
576 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
577                                   const DominatorTree &DT,
578                                   const PostDominatorTree &PDT,
579                                   const SanitizerCoverageOptions &Options) {
580   // Don't insert coverage for blocks containing nothing but unreachable: we
581   // will never call __sanitizer_cov() for them, so counting them in
582   // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
583   // percentage. Also, unreachable instructions frequently have no debug
584   // locations.
585   if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime()))
586     return false;
587 
588   // Don't insert coverage into blocks without a valid insertion point
589   // (catchswitch blocks).
590   if (BB->getFirstInsertionPt() == BB->end())
591     return false;
592 
593   if (Options.NoPrune || &F.getEntryBlock() == BB)
594     return true;
595 
596   if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
597       &F.getEntryBlock() != BB)
598     return false;
599 
600   // Do not instrument full dominators, or full post-dominators with multiple
601   // predecessors.
602   return !isFullDominator(BB, DT)
603     && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
604 }
605 
606 // Returns true iff From->To is a backedge.
607 // A twist here is that we treat From->To as a backedge if
608 //   * To dominates From or
609 //   * To->UniqueSuccessor dominates From
610 static bool IsBackEdge(BasicBlock *From, BasicBlock *To,
611                        const DominatorTree &DT) {
612   if (DT.dominates(To, From))
613     return true;
614   if (auto Next = To->getUniqueSuccessor())
615     if (DT.dominates(Next, From))
616       return true;
617   return false;
618 }
619 
620 // Prunes uninteresting Cmp instrumentation:
621 //   * CMP instructions that feed into loop backedge branch.
622 //
623 // Note that Cmp pruning is controlled by the same flag as the
624 // BB pruning.
625 static bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree &DT,
626                              const SanitizerCoverageOptions &Options) {
627   if (!Options.NoPrune)
628     if (CMP->hasOneUse())
629       if (auto BR = dyn_cast<BranchInst>(CMP->user_back()))
630         for (BasicBlock *B : BR->successors())
631           if (IsBackEdge(BR->getParent(), B, DT))
632             return false;
633   return true;
634 }
635 
636 void ModuleSanitizerCoverage::instrumentFunction(Function &F) {
637   if (F.empty())
638     return;
639   if (F.getName().contains(".module_ctor"))
640     return; // Should not instrument sanitizer init functions.
641   if (F.getName().starts_with("__sanitizer_"))
642     return; // Don't instrument __sanitizer_* callbacks.
643   // Don't touch available_externally functions, their actual body is elewhere.
644   if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
645     return;
646   // Don't instrument MSVC CRT configuration helpers. They may run before normal
647   // initialization.
648   if (F.getName() == "__local_stdio_printf_options" ||
649       F.getName() == "__local_stdio_scanf_options")
650     return;
651   if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
652     return;
653   // Don't instrument functions using SEH for now. Splitting basic blocks like
654   // we do for coverage breaks WinEHPrepare.
655   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
656   if (F.hasPersonalityFn() &&
657       isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
658     return;
659   if (Allowlist && !Allowlist->inSection("coverage", "fun", F.getName()))
660     return;
661   if (Blocklist && Blocklist->inSection("coverage", "fun", F.getName()))
662     return;
663   // Do not apply any instrumentation for naked functions.
664   if (F.hasFnAttribute(Attribute::Naked))
665     return;
666   if (F.hasFnAttribute(Attribute::NoSanitizeCoverage))
667     return;
668   if (F.hasFnAttribute(Attribute::DisableSanitizerInstrumentation))
669     return;
670   if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge) {
671     SplitAllCriticalEdges(
672         F, CriticalEdgeSplittingOptions().setIgnoreUnreachableDests());
673   }
674   SmallVector<Instruction *, 8> IndirCalls;
675   SmallVector<BasicBlock *, 16> BlocksToInstrument;
676   SmallVector<Instruction *, 8> CmpTraceTargets;
677   SmallVector<Instruction *, 8> SwitchTraceTargets;
678   SmallVector<BinaryOperator *, 8> DivTraceTargets;
679   SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
680   SmallVector<LoadInst *, 8> Loads;
681   SmallVector<StoreInst *, 8> Stores;
682 
683   const DominatorTree &DT = DTCallback(F);
684   const PostDominatorTree &PDT = PDTCallback(F);
685   bool IsLeafFunc = true;
686 
687   for (auto &BB : F) {
688     if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
689       BlocksToInstrument.push_back(&BB);
690     for (auto &Inst : BB) {
691       if (Options.IndirectCalls) {
692         CallBase *CB = dyn_cast<CallBase>(&Inst);
693         if (CB && CB->isIndirectCall())
694           IndirCalls.push_back(&Inst);
695       }
696       if (Options.TraceCmp) {
697         if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst))
698           if (IsInterestingCmp(CMP, DT, Options))
699             CmpTraceTargets.push_back(&Inst);
700         if (isa<SwitchInst>(&Inst))
701           SwitchTraceTargets.push_back(&Inst);
702       }
703       if (Options.TraceDiv)
704         if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
705           if (BO->getOpcode() == Instruction::SDiv ||
706               BO->getOpcode() == Instruction::UDiv)
707             DivTraceTargets.push_back(BO);
708       if (Options.TraceGep)
709         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
710           GepTraceTargets.push_back(GEP);
711       if (Options.TraceLoads)
712         if (LoadInst *LI = dyn_cast<LoadInst>(&Inst))
713           Loads.push_back(LI);
714       if (Options.TraceStores)
715         if (StoreInst *SI = dyn_cast<StoreInst>(&Inst))
716           Stores.push_back(SI);
717       if (Options.StackDepth)
718         if (isa<InvokeInst>(Inst) ||
719             (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
720           IsLeafFunc = false;
721     }
722   }
723 
724   if (Options.CollectControlFlow)
725     createFunctionControlFlow(F);
726 
727   InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
728   InjectCoverageForIndirectCalls(F, IndirCalls);
729   InjectTraceForCmp(F, CmpTraceTargets);
730   InjectTraceForSwitch(F, SwitchTraceTargets);
731   InjectTraceForDiv(F, DivTraceTargets);
732   InjectTraceForGep(F, GepTraceTargets);
733   InjectTraceForLoadsAndStores(F, Loads, Stores);
734 }
735 
736 GlobalVariable *ModuleSanitizerCoverage::CreateFunctionLocalArrayInSection(
737     size_t NumElements, Function &F, Type *Ty, const char *Section) {
738   ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
739   auto Array = new GlobalVariable(
740       *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
741       Constant::getNullValue(ArrayTy), "__sancov_gen_");
742 
743   if (TargetTriple.supportsCOMDAT() &&
744       (TargetTriple.isOSBinFormatELF() || !F.isInterposable()))
745     if (auto Comdat = getOrCreateFunctionComdat(F, TargetTriple))
746       Array->setComdat(Comdat);
747   Array->setSection(getSectionName(Section));
748   Array->setAlignment(Align(DL->getTypeStoreSize(Ty).getFixedValue()));
749 
750   // sancov_pcs parallels the other metadata section(s). Optimizers (e.g.
751   // GlobalOpt/ConstantMerge) may not discard sancov_pcs and the other
752   // section(s) as a unit, so we conservatively retain all unconditionally in
753   // the compiler.
754   //
755   // With comdat (COFF/ELF), the linker can guarantee the associated sections
756   // will be retained or discarded as a unit, so llvm.compiler.used is
757   // sufficient. Otherwise, conservatively make all of them retained by the
758   // linker.
759   if (Array->hasComdat())
760     GlobalsToAppendToCompilerUsed.push_back(Array);
761   else
762     GlobalsToAppendToUsed.push_back(Array);
763 
764   return Array;
765 }
766 
767 GlobalVariable *
768 ModuleSanitizerCoverage::CreatePCArray(Function &F,
769                                        ArrayRef<BasicBlock *> AllBlocks) {
770   size_t N = AllBlocks.size();
771   assert(N);
772   SmallVector<Constant *, 32> PCs;
773   IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
774   for (size_t i = 0; i < N; i++) {
775     if (&F.getEntryBlock() == AllBlocks[i]) {
776       PCs.push_back((Constant *)IRB.CreatePointerCast(&F, PtrTy));
777       PCs.push_back((Constant *)IRB.CreateIntToPtr(
778           ConstantInt::get(IntptrTy, 1), PtrTy));
779     } else {
780       PCs.push_back((Constant *)IRB.CreatePointerCast(
781           BlockAddress::get(AllBlocks[i]), PtrTy));
782       PCs.push_back(Constant::getNullValue(PtrTy));
783     }
784   }
785   auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, PtrTy,
786                                                     SanCovPCsSectionName);
787   PCArray->setInitializer(
788       ConstantArray::get(ArrayType::get(PtrTy, N * 2), PCs));
789   PCArray->setConstant(true);
790 
791   return PCArray;
792 }
793 
794 void ModuleSanitizerCoverage::CreateFunctionLocalArrays(
795     Function &F, ArrayRef<BasicBlock *> AllBlocks) {
796   if (Options.TracePCGuard)
797     FunctionGuardArray = CreateFunctionLocalArrayInSection(
798         AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
799 
800   if (Options.Inline8bitCounters)
801     Function8bitCounterArray = CreateFunctionLocalArrayInSection(
802         AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
803   if (Options.InlineBoolFlag)
804     FunctionBoolArray = CreateFunctionLocalArrayInSection(
805         AllBlocks.size(), F, Int1Ty, SanCovBoolFlagSectionName);
806 
807   if (Options.PCTable)
808     FunctionPCsArray = CreatePCArray(F, AllBlocks);
809 }
810 
811 Value *ModuleSanitizerCoverage::CreateFunctionLocalGateCmp(IRBuilder<> &IRB) {
812   auto Load = IRB.CreateLoad(Int64Ty, SanCovCallbackGate);
813   Load->setNoSanitizeMetadata();
814   auto Cmp = IRB.CreateIsNotNull(Load);
815   Cmp->setName("sancov gate cmp");
816   return Cmp;
817 }
818 
819 bool ModuleSanitizerCoverage::InjectCoverage(Function &F,
820                                              ArrayRef<BasicBlock *> AllBlocks,
821                                              bool IsLeafFunc) {
822   if (AllBlocks.empty()) return false;
823   CreateFunctionLocalArrays(F, AllBlocks);
824   Value *FunctionGateCmp = nullptr;
825   for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
826     InjectCoverageAtBlock(F, *AllBlocks[i], i, FunctionGateCmp, IsLeafFunc);
827   return true;
828 }
829 
830 // On every indirect call we call a run-time function
831 // __sanitizer_cov_indir_call* with two parameters:
832 //   - callee address,
833 //   - global cache array that contains CacheSize pointers (zero-initialized).
834 //     The cache is used to speed up recording the caller-callee pairs.
835 // The address of the caller is passed implicitly via caller PC.
836 // CacheSize is encoded in the name of the run-time function.
837 void ModuleSanitizerCoverage::InjectCoverageForIndirectCalls(
838     Function &F, ArrayRef<Instruction *> IndirCalls) {
839   if (IndirCalls.empty())
840     return;
841   assert(Options.TracePC || Options.TracePCGuard ||
842          Options.Inline8bitCounters || Options.InlineBoolFlag);
843   for (auto *I : IndirCalls) {
844     InstrumentationIRBuilder IRB(I);
845     CallBase &CB = cast<CallBase>(*I);
846     Value *Callee = CB.getCalledOperand();
847     if (isa<InlineAsm>(Callee))
848       continue;
849     IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
850   }
851 }
852 
853 // For every switch statement we insert a call:
854 // __sanitizer_cov_trace_switch(CondValue,
855 //      {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
856 
857 void ModuleSanitizerCoverage::InjectTraceForSwitch(
858     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
859   for (auto *I : SwitchTraceTargets) {
860     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
861       InstrumentationIRBuilder IRB(I);
862       SmallVector<Constant *, 16> Initializers;
863       Value *Cond = SI->getCondition();
864       if (Cond->getType()->getScalarSizeInBits() >
865           Int64Ty->getScalarSizeInBits())
866         continue;
867       Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
868       Initializers.push_back(
869           ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
870       if (Cond->getType()->getScalarSizeInBits() <
871           Int64Ty->getScalarSizeInBits())
872         Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
873       for (auto It : SI->cases()) {
874         ConstantInt *C = It.getCaseValue();
875         if (C->getType()->getScalarSizeInBits() < 64)
876           C = ConstantInt::get(C->getContext(), C->getValue().zext(64));
877         Initializers.push_back(C);
878       }
879       llvm::sort(drop_begin(Initializers, 2),
880                  [](const Constant *A, const Constant *B) {
881                    return cast<ConstantInt>(A)->getLimitedValue() <
882                           cast<ConstantInt>(B)->getLimitedValue();
883                  });
884       ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
885       GlobalVariable *GV = new GlobalVariable(
886           *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
887           ConstantArray::get(ArrayOfInt64Ty, Initializers),
888           "__sancov_gen_cov_switch_values");
889       IRB.CreateCall(SanCovTraceSwitchFunction, {Cond, GV});
890     }
891   }
892 }
893 
894 void ModuleSanitizerCoverage::InjectTraceForDiv(
895     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
896   for (auto *BO : DivTraceTargets) {
897     InstrumentationIRBuilder IRB(BO);
898     Value *A1 = BO->getOperand(1);
899     if (isa<ConstantInt>(A1)) continue;
900     if (!A1->getType()->isIntegerTy())
901       continue;
902     uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
903     int CallbackIdx = TypeSize == 32 ? 0 :
904         TypeSize == 64 ? 1 : -1;
905     if (CallbackIdx < 0) continue;
906     auto Ty = Type::getIntNTy(*C, TypeSize);
907     IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
908                    {IRB.CreateIntCast(A1, Ty, true)});
909   }
910 }
911 
912 void ModuleSanitizerCoverage::InjectTraceForGep(
913     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
914   for (auto *GEP : GepTraceTargets) {
915     InstrumentationIRBuilder IRB(GEP);
916     for (Use &Idx : GEP->indices())
917       if (!isa<ConstantInt>(Idx) && Idx->getType()->isIntegerTy())
918         IRB.CreateCall(SanCovTraceGepFunction,
919                        {IRB.CreateIntCast(Idx, IntptrTy, true)});
920   }
921 }
922 
923 void ModuleSanitizerCoverage::InjectTraceForLoadsAndStores(
924     Function &, ArrayRef<LoadInst *> Loads, ArrayRef<StoreInst *> Stores) {
925   auto CallbackIdx = [&](Type *ElementTy) -> int {
926     uint64_t TypeSize = DL->getTypeStoreSizeInBits(ElementTy);
927     return TypeSize == 8     ? 0
928            : TypeSize == 16  ? 1
929            : TypeSize == 32  ? 2
930            : TypeSize == 64  ? 3
931            : TypeSize == 128 ? 4
932                              : -1;
933   };
934   for (auto *LI : Loads) {
935     InstrumentationIRBuilder IRB(LI);
936     auto Ptr = LI->getPointerOperand();
937     int Idx = CallbackIdx(LI->getType());
938     if (Idx < 0)
939       continue;
940     IRB.CreateCall(SanCovLoadFunction[Idx], Ptr);
941   }
942   for (auto *SI : Stores) {
943     InstrumentationIRBuilder IRB(SI);
944     auto Ptr = SI->getPointerOperand();
945     int Idx = CallbackIdx(SI->getValueOperand()->getType());
946     if (Idx < 0)
947       continue;
948     IRB.CreateCall(SanCovStoreFunction[Idx], Ptr);
949   }
950 }
951 
952 void ModuleSanitizerCoverage::InjectTraceForCmp(
953     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
954   for (auto *I : CmpTraceTargets) {
955     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
956       InstrumentationIRBuilder IRB(ICMP);
957       Value *A0 = ICMP->getOperand(0);
958       Value *A1 = ICMP->getOperand(1);
959       if (!A0->getType()->isIntegerTy())
960         continue;
961       uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
962       int CallbackIdx = TypeSize == 8 ? 0 :
963                         TypeSize == 16 ? 1 :
964                         TypeSize == 32 ? 2 :
965                         TypeSize == 64 ? 3 : -1;
966       if (CallbackIdx < 0) continue;
967       // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
968       auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
969       bool FirstIsConst = isa<ConstantInt>(A0);
970       bool SecondIsConst = isa<ConstantInt>(A1);
971       // If both are const, then we don't need such a comparison.
972       if (FirstIsConst && SecondIsConst) continue;
973       // If only one is const, then make it the first callback argument.
974       if (FirstIsConst || SecondIsConst) {
975         CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
976         if (SecondIsConst)
977           std::swap(A0, A1);
978       }
979 
980       auto Ty = Type::getIntNTy(*C, TypeSize);
981       IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
982               IRB.CreateIntCast(A1, Ty, true)});
983     }
984   }
985 }
986 
987 void ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
988                                                     size_t Idx,
989                                                     Value *&FunctionGateCmp,
990                                                     bool IsLeafFunc) {
991   BasicBlock::iterator IP = BB.getFirstInsertionPt();
992   bool IsEntryBB = &BB == &F.getEntryBlock();
993   DebugLoc EntryLoc;
994   if (IsEntryBB) {
995     if (auto SP = F.getSubprogram())
996       EntryLoc = DILocation::get(SP->getContext(), SP->getScopeLine(), 0, SP);
997     // Keep static allocas and llvm.localescape calls in the entry block.  Even
998     // if we aren't splitting the block, it's nice for allocas to be before
999     // calls.
1000     IP = PrepareToSplitEntryBlock(BB, IP);
1001   }
1002 
1003   InstrumentationIRBuilder IRB(&*IP);
1004   if (EntryLoc)
1005     IRB.SetCurrentDebugLocation(EntryLoc);
1006   if (Options.TracePC) {
1007     IRB.CreateCall(SanCovTracePC)
1008         ->setCannotMerge(); // gets the PC using GET_CALLER_PC.
1009   }
1010   if (Options.TracePCGuard) {
1011     auto GuardPtr = IRB.CreateIntToPtr(
1012         IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
1013                       ConstantInt::get(IntptrTy, Idx * 4)),
1014         PtrTy);
1015     if (Options.GatedCallbacks) {
1016       if (!FunctionGateCmp) {
1017         // Create this in the entry block
1018         assert(IsEntryBB);
1019         FunctionGateCmp = CreateFunctionLocalGateCmp(IRB);
1020       }
1021       // Set the branch weights in order to minimize the price paid when the
1022       // gate is turned off, allowing the default enablement of this
1023       // instrumentation with as little of a performance cost as possible
1024       auto Weights = MDBuilder(*C).createBranchWeights(1, 100000);
1025       auto ThenTerm =
1026           SplitBlockAndInsertIfThen(FunctionGateCmp, &*IP, false, Weights);
1027       IRBuilder<> ThenIRB(ThenTerm);
1028       ThenIRB.CreateCall(SanCovTracePCGuard, GuardPtr)->setCannotMerge();
1029     } else {
1030       IRB.CreateCall(SanCovTracePCGuard, GuardPtr)->setCannotMerge();
1031     }
1032   }
1033   if (Options.Inline8bitCounters) {
1034     auto CounterPtr = IRB.CreateGEP(
1035         Function8bitCounterArray->getValueType(), Function8bitCounterArray,
1036         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
1037     auto Load = IRB.CreateLoad(Int8Ty, CounterPtr);
1038     auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
1039     auto Store = IRB.CreateStore(Inc, CounterPtr);
1040     Load->setNoSanitizeMetadata();
1041     Store->setNoSanitizeMetadata();
1042   }
1043   if (Options.InlineBoolFlag) {
1044     auto FlagPtr = IRB.CreateGEP(
1045         FunctionBoolArray->getValueType(), FunctionBoolArray,
1046         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
1047     auto Load = IRB.CreateLoad(Int1Ty, FlagPtr);
1048     auto ThenTerm = SplitBlockAndInsertIfThen(
1049         IRB.CreateIsNull(Load), &*IP, false,
1050         MDBuilder(IRB.getContext()).createUnlikelyBranchWeights());
1051     IRBuilder<> ThenIRB(ThenTerm);
1052     auto Store = ThenIRB.CreateStore(ConstantInt::getTrue(Int1Ty), FlagPtr);
1053     Load->setNoSanitizeMetadata();
1054     Store->setNoSanitizeMetadata();
1055   }
1056   if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
1057     // Check stack depth.  If it's the deepest so far, record it.
1058     Module *M = F.getParent();
1059     Function *GetFrameAddr = Intrinsic::getOrInsertDeclaration(
1060         M, Intrinsic::frameaddress,
1061         IRB.getPtrTy(M->getDataLayout().getAllocaAddrSpace()));
1062     auto FrameAddrPtr =
1063         IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
1064     auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
1065     auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack);
1066     auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
1067     auto ThenTerm = SplitBlockAndInsertIfThen(
1068         IsStackLower, &*IP, false,
1069         MDBuilder(IRB.getContext()).createUnlikelyBranchWeights());
1070     IRBuilder<> ThenIRB(ThenTerm);
1071     auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
1072     LowestStack->setNoSanitizeMetadata();
1073     Store->setNoSanitizeMetadata();
1074   }
1075 }
1076 
1077 std::string
1078 ModuleSanitizerCoverage::getSectionName(const std::string &Section) const {
1079   if (TargetTriple.isOSBinFormatCOFF()) {
1080     if (Section == SanCovCountersSectionName)
1081       return ".SCOV$CM";
1082     if (Section == SanCovBoolFlagSectionName)
1083       return ".SCOV$BM";
1084     if (Section == SanCovPCsSectionName)
1085       return ".SCOVP$M";
1086     return ".SCOV$GM"; // For SanCovGuardsSectionName.
1087   }
1088   if (TargetTriple.isOSBinFormatMachO())
1089     return "__DATA,__" + Section;
1090   return "__" + Section;
1091 }
1092 
1093 std::string
1094 ModuleSanitizerCoverage::getSectionStart(const std::string &Section) const {
1095   if (TargetTriple.isOSBinFormatMachO())
1096     return "\1section$start$__DATA$__" + Section;
1097   return "__start___" + Section;
1098 }
1099 
1100 std::string
1101 ModuleSanitizerCoverage::getSectionEnd(const std::string &Section) const {
1102   if (TargetTriple.isOSBinFormatMachO())
1103     return "\1section$end$__DATA$__" + Section;
1104   return "__stop___" + Section;
1105 }
1106 
1107 void ModuleSanitizerCoverage::createFunctionControlFlow(Function &F) {
1108   SmallVector<Constant *, 32> CFs;
1109   IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
1110 
1111   for (auto &BB : F) {
1112     // blockaddress can not be used on function's entry block.
1113     if (&BB == &F.getEntryBlock())
1114       CFs.push_back((Constant *)IRB.CreatePointerCast(&F, PtrTy));
1115     else
1116       CFs.push_back((Constant *)IRB.CreatePointerCast(BlockAddress::get(&BB),
1117                                                       PtrTy));
1118 
1119     for (auto SuccBB : successors(&BB)) {
1120       assert(SuccBB != &F.getEntryBlock());
1121       CFs.push_back((Constant *)IRB.CreatePointerCast(BlockAddress::get(SuccBB),
1122                                                       PtrTy));
1123     }
1124 
1125     CFs.push_back((Constant *)Constant::getNullValue(PtrTy));
1126 
1127     for (auto &Inst : BB) {
1128       if (CallBase *CB = dyn_cast<CallBase>(&Inst)) {
1129         if (CB->isIndirectCall()) {
1130           // TODO(navidem): handle indirect calls, for now mark its existence.
1131           CFs.push_back((Constant *)IRB.CreateIntToPtr(
1132               ConstantInt::get(IntptrTy, -1), PtrTy));
1133         } else {
1134           auto CalledF = CB->getCalledFunction();
1135           if (CalledF && !CalledF->isIntrinsic())
1136             CFs.push_back(
1137                 (Constant *)IRB.CreatePointerCast(CalledF, PtrTy));
1138         }
1139       }
1140     }
1141 
1142     CFs.push_back((Constant *)Constant::getNullValue(PtrTy));
1143   }
1144 
1145   FunctionCFsArray = CreateFunctionLocalArrayInSection(
1146       CFs.size(), F, PtrTy, SanCovCFsSectionName);
1147   FunctionCFsArray->setInitializer(
1148       ConstantArray::get(ArrayType::get(PtrTy, CFs.size()), CFs));
1149   FunctionCFsArray->setConstant(true);
1150 }
1151