xref: /llvm-project/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp (revision c5d3d490340fd32698ef9f29b80e97a4c1e95d11) 
1 //===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Coverage instrumentation that works with AddressSanitizer
11 // and potentially with other Sanitizers.
12 //
13 // We create a Guard variable with the same linkage
14 // as the function and inject this code into the entry block (SCK_Function)
15 // or all blocks (SCK_BB):
16 // if (Guard < 0) {
17 //    __sanitizer_cov(&Guard);
18 // }
19 // The accesses to Guard are atomic. The rest of the logic is
20 // in __sanitizer_cov (it's fine to call it more than once).
21 //
22 // With SCK_Edge we also split critical edges this effectively
23 // instrumenting all edges.
24 //
25 // This coverage implementation provides very limited data:
26 // it only tells if a given function (block) was ever executed. No counters.
27 // But for many use cases this is what we need and the added slowdown small.
28 //
29 //===----------------------------------------------------------------------===//
30 
31 #include "llvm/ADT/ArrayRef.h"
32 #include "llvm/ADT/SmallVector.h"
33 #include "llvm/Analysis/EHPersonalities.h"
34 #include "llvm/Analysis/PostDominators.h"
35 #include "llvm/IR/CFG.h"
36 #include "llvm/IR/CallSite.h"
37 #include "llvm/IR/DataLayout.h"
38 #include "llvm/IR/DebugInfo.h"
39 #include "llvm/IR/Dominators.h"
40 #include "llvm/IR/Function.h"
41 #include "llvm/IR/IRBuilder.h"
42 #include "llvm/IR/InlineAsm.h"
43 #include "llvm/IR/LLVMContext.h"
44 #include "llvm/IR/MDBuilder.h"
45 #include "llvm/IR/Module.h"
46 #include "llvm/IR/Type.h"
47 #include "llvm/Support/CommandLine.h"
48 #include "llvm/Support/Debug.h"
49 #include "llvm/Support/raw_ostream.h"
50 #include "llvm/Transforms/Instrumentation.h"
51 #include "llvm/Transforms/Scalar.h"
52 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
53 #include "llvm/Transforms/Utils/ModuleUtils.h"
54 
55 using namespace llvm;
56 
57 #define DEBUG_TYPE "sancov"
58 
59 static const char *const SanCovModuleInitName = "__sanitizer_cov_module_init";
60 static const char *const SanCovName = "__sanitizer_cov";
61 static const char *const SanCovWithCheckName = "__sanitizer_cov_with_check";
62 static const char *const SanCovTracePCIndirName =
63     "__sanitizer_cov_trace_pc_indir";
64 static const char *const SanCovTracePCName = "__sanitizer_cov_trace_pc";
65 static const char *const SanCovTraceCmp1 = "__sanitizer_cov_trace_cmp1";
66 static const char *const SanCovTraceCmp2 = "__sanitizer_cov_trace_cmp2";
67 static const char *const SanCovTraceCmp4 = "__sanitizer_cov_trace_cmp4";
68 static const char *const SanCovTraceCmp8 = "__sanitizer_cov_trace_cmp8";
69 static const char *const SanCovTraceDiv4 = "__sanitizer_cov_trace_div4";
70 static const char *const SanCovTraceDiv8 = "__sanitizer_cov_trace_div8";
71 static const char *const SanCovTraceGep = "__sanitizer_cov_trace_gep";
72 static const char *const SanCovTraceSwitchName = "__sanitizer_cov_trace_switch";
73 static const char *const SanCovModuleCtorName = "sancov.module_ctor";
74 static const uint64_t SanCtorAndDtorPriority = 2;
75 
76 static const char *const SanCovTracePCGuardName =
77     "__sanitizer_cov_trace_pc_guard";
78 static const char *const SanCovTracePCGuardInitName =
79     "__sanitizer_cov_trace_pc_guard_init";
80 
81 static cl::opt<int> ClCoverageLevel(
82     "sanitizer-coverage-level",
83     cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
84              "3: all blocks and critical edges"),
85     cl::Hidden, cl::init(0));
86 
87 static cl::opt<unsigned> ClCoverageBlockThreshold(
88     "sanitizer-coverage-block-threshold",
89     cl::desc("Use a callback with a guard check inside it if there are"
90              " more than this number of blocks."),
91     cl::Hidden, cl::init(0));
92 
93 static cl::opt<bool> ClExperimentalTracePC("sanitizer-coverage-trace-pc",
94                                            cl::desc("Experimental pc tracing"),
95                                            cl::Hidden, cl::init(false));
96 
97 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard",
98                                     cl::desc("pc tracing with a guard"),
99                                     cl::Hidden, cl::init(false));
100 
101 static cl::opt<bool>
102     ClCMPTracing("sanitizer-coverage-trace-compares",
103                  cl::desc("Tracing of CMP and similar instructions"),
104                  cl::Hidden, cl::init(false));
105 
106 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs",
107                                   cl::desc("Tracing of DIV instructions"),
108                                   cl::Hidden, cl::init(false));
109 
110 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps",
111                                   cl::desc("Tracing of GEP instructions"),
112                                   cl::Hidden, cl::init(false));
113 
114 static cl::opt<bool>
115     ClPruneBlocks("sanitizer-coverage-prune-blocks",
116                   cl::desc("Reduce the number of instrumented blocks"),
117                   cl::Hidden, cl::init(true));
118 
119 namespace {
120 
121 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
122   SanitizerCoverageOptions Res;
123   switch (LegacyCoverageLevel) {
124   case 0:
125     Res.CoverageType = SanitizerCoverageOptions::SCK_None;
126     break;
127   case 1:
128     Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
129     break;
130   case 2:
131     Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
132     break;
133   case 3:
134     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
135     break;
136   case 4:
137     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
138     Res.IndirectCalls = true;
139     break;
140   }
141   return Res;
142 }
143 
144 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
145   // Sets CoverageType and IndirectCalls.
146   SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
147   Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
148   Options.IndirectCalls |= CLOpts.IndirectCalls;
149   Options.TraceCmp |= ClCMPTracing;
150   Options.TraceDiv |= ClDIVTracing;
151   Options.TraceGep |= ClGEPTracing;
152   Options.TracePC |= ClExperimentalTracePC;
153   Options.TracePCGuard |= ClTracePCGuard;
154   return Options;
155 }
156 
157 class SanitizerCoverageModule : public ModulePass {
158 public:
159   SanitizerCoverageModule(
160       const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
161       : ModulePass(ID), Options(OverrideFromCL(Options)) {
162     initializeSanitizerCoverageModulePass(*PassRegistry::getPassRegistry());
163   }
164   bool runOnModule(Module &M) override;
165   bool runOnFunction(Function &F);
166   static char ID; // Pass identification, replacement for typeid
167   StringRef getPassName() const override { return "SanitizerCoverageModule"; }
168 
169   void getAnalysisUsage(AnalysisUsage &AU) const override {
170     AU.addRequired<DominatorTreeWrapperPass>();
171     AU.addRequired<PostDominatorTreeWrapperPass>();
172   }
173 
174 private:
175   void InjectCoverageForIndirectCalls(Function &F,
176                                       ArrayRef<Instruction *> IndirCalls);
177   void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
178   void InjectTraceForDiv(Function &F,
179                          ArrayRef<BinaryOperator *> DivTraceTargets);
180   void InjectTraceForGep(Function &F,
181                          ArrayRef<GetElementPtrInst *> GepTraceTargets);
182   void InjectTraceForSwitch(Function &F,
183                             ArrayRef<Instruction *> SwitchTraceTargets);
184   bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks);
185   void CreateFunctionGuardArray(size_t NumGuards, Function &F);
186   void SetNoSanitizeMetadata(Instruction *I);
187   void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
188                              bool UseCalls);
189   unsigned NumberOfInstrumentedBlocks() {
190     return SanCovFunction->getNumUses() +
191            SanCovWithCheckFunction->getNumUses();
192   }
193   StringRef getSanCovTracePCGuardSection() const;
194   StringRef getSanCovTracePCGuardSectionStart() const;
195   StringRef getSanCovTracePCGuardSectionEnd() const;
196   Function *SanCovFunction;
197   Function *SanCovWithCheckFunction;
198   Function *SanCovTracePCIndir;
199   Function *SanCovTracePC, *SanCovTracePCGuard;
200   Function *SanCovTraceCmpFunction[4];
201   Function *SanCovTraceDivFunction[2];
202   Function *SanCovTraceGepFunction;
203   Function *SanCovTraceSwitchFunction;
204   InlineAsm *EmptyAsm;
205   Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy;
206   Module *CurModule;
207   Triple TargetTriple;
208   LLVMContext *C;
209   const DataLayout *DL;
210 
211   GlobalVariable *GuardArray;
212   GlobalVariable *FunctionGuardArray;  // for trace-pc-guard.
213   bool HasSancovGuardsSection;
214 
215   SanitizerCoverageOptions Options;
216 };
217 
218 } // namespace
219 
220 bool SanitizerCoverageModule::runOnModule(Module &M) {
221   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
222     return false;
223   C = &(M.getContext());
224   DL = &M.getDataLayout();
225   CurModule = &M;
226   TargetTriple = Triple(M.getTargetTriple());
227   HasSancovGuardsSection = false;
228   IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
229   IntptrPtrTy = PointerType::getUnqual(IntptrTy);
230   Type *VoidTy = Type::getVoidTy(*C);
231   IRBuilder<> IRB(*C);
232   Type *Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
233   Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
234   Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
235   Int64Ty = IRB.getInt64Ty();
236   Int32Ty = IRB.getInt32Ty();
237 
238   SanCovFunction = checkSanitizerInterfaceFunction(
239       M.getOrInsertFunction(SanCovName, VoidTy, Int32PtrTy));
240   SanCovWithCheckFunction = checkSanitizerInterfaceFunction(
241       M.getOrInsertFunction(SanCovWithCheckName, VoidTy, Int32PtrTy));
242   SanCovTracePCIndir = checkSanitizerInterfaceFunction(
243       M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy));
244   SanCovTraceCmpFunction[0] =
245       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
246           SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty()));
247   SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction(
248       M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(),
249                             IRB.getInt16Ty()));
250   SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction(
251       M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(),
252                             IRB.getInt32Ty()));
253   SanCovTraceCmpFunction[3] =
254       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
255           SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty));
256 
257   SanCovTraceDivFunction[0] =
258       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
259           SanCovTraceDiv4, VoidTy, IRB.getInt32Ty()));
260   SanCovTraceDivFunction[1] =
261       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
262           SanCovTraceDiv8, VoidTy, Int64Ty));
263   SanCovTraceGepFunction =
264       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
265           SanCovTraceGep, VoidTy, IntptrTy));
266   SanCovTraceSwitchFunction =
267       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
268           SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy));
269 
270   // We insert an empty inline asm after cov callbacks to avoid callback merge.
271   EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
272                             StringRef(""), StringRef(""),
273                             /*hasSideEffects=*/true);
274 
275   SanCovTracePC = checkSanitizerInterfaceFunction(
276       M.getOrInsertFunction(SanCovTracePCName, VoidTy));
277   SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
278       SanCovTracePCGuardName, VoidTy, Int32PtrTy));
279 
280   // At this point we create a dummy array of guards because we don't
281   // know how many elements we will need.
282   Type *Int32Ty = IRB.getInt32Ty();
283 
284   if (!Options.TracePCGuard)
285     GuardArray =
286         new GlobalVariable(M, Int32Ty, false, GlobalValue::ExternalLinkage,
287                            nullptr, "__sancov_gen_cov_tmp");
288 
289   for (auto &F : M)
290     runOnFunction(F);
291 
292   auto N = NumberOfInstrumentedBlocks();
293 
294   GlobalVariable *RealGuardArray = nullptr;
295   if (!Options.TracePCGuard) {
296     // Now we know how many elements we need. Create an array of guards
297     // with one extra element at the beginning for the size.
298     Type *Int32ArrayNTy = ArrayType::get(Int32Ty, N + 1);
299     RealGuardArray = new GlobalVariable(
300         M, Int32ArrayNTy, false, GlobalValue::PrivateLinkage,
301         Constant::getNullValue(Int32ArrayNTy), "__sancov_gen_cov");
302 
303     // Replace the dummy array with the real one.
304     GuardArray->replaceAllUsesWith(
305         IRB.CreatePointerCast(RealGuardArray, Int32PtrTy));
306     GuardArray->eraseFromParent();
307   }
308 
309   // Create variable for module (compilation unit) name
310   Constant *ModNameStrConst =
311       ConstantDataArray::getString(M.getContext(), M.getName(), true);
312   GlobalVariable *ModuleName = new GlobalVariable(
313       M, ModNameStrConst->getType(), true, GlobalValue::PrivateLinkage,
314       ModNameStrConst, "__sancov_gen_modname");
315   if (Options.TracePCGuard) {
316     if (HasSancovGuardsSection) {
317       Function *CtorFunc;
318       GlobalVariable *SecStart = new GlobalVariable(
319           M, Int32PtrTy, false, GlobalVariable::ExternalLinkage, nullptr,
320           getSanCovTracePCGuardSectionStart());
321       SecStart->setVisibility(GlobalValue::HiddenVisibility);
322       GlobalVariable *SecEnd = new GlobalVariable(
323           M, Int32PtrTy, false, GlobalVariable::ExternalLinkage, nullptr,
324           getSanCovTracePCGuardSectionEnd());
325       SecEnd->setVisibility(GlobalValue::HiddenVisibility);
326 
327       std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
328           M, SanCovModuleCtorName, SanCovTracePCGuardInitName,
329           {Int32PtrTy, Int32PtrTy},
330           {IRB.CreatePointerCast(SecStart, Int32PtrTy),
331             IRB.CreatePointerCast(SecEnd, Int32PtrTy)});
332 
333       if (TargetTriple.supportsCOMDAT()) {
334         // Use comdat to dedup CtorFunc.
335         CtorFunc->setComdat(M.getOrInsertComdat(SanCovModuleCtorName));
336         appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
337       } else {
338         appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
339       }
340     }
341   } else if (!Options.TracePC) {
342     Function *CtorFunc;
343     std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
344         M, SanCovModuleCtorName, SanCovModuleInitName,
345         {Int32PtrTy, IntptrTy, Int8PtrTy, Int8PtrTy},
346         {IRB.CreatePointerCast(RealGuardArray, Int32PtrTy),
347          ConstantInt::get(IntptrTy, N), Constant::getNullValue(Int8PtrTy),
348          IRB.CreatePointerCast(ModuleName, Int8PtrTy)});
349 
350     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
351   }
352 
353   return true;
354 }
355 
356 // True if block has successors and it dominates all of them.
357 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
358   if (succ_begin(BB) == succ_end(BB))
359     return false;
360 
361   for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
362     if (!DT->dominates(BB, SUCC))
363       return false;
364   }
365 
366   return true;
367 }
368 
369 // True if block has predecessors and it postdominates all of them.
370 static bool isFullPostDominator(const BasicBlock *BB,
371                                 const PostDominatorTree *PDT) {
372   if (pred_begin(BB) == pred_end(BB))
373     return false;
374 
375   for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
376     if (!PDT->dominates(BB, PRED))
377       return false;
378   }
379 
380   return true;
381 }
382 
383 static bool shouldInstrumentBlock(const Function& F, const BasicBlock *BB, const DominatorTree *DT,
384                                   const PostDominatorTree *PDT) {
385   // Don't insert coverage for unreachable blocks: we will never call
386   // __sanitizer_cov() for them, so counting them in
387   // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
388   // percentage. Also, unreachable instructions frequently have no debug
389   // locations.
390   if (isa<UnreachableInst>(BB->getTerminator()))
391     return false;
392 
393   // Don't insert coverage into blocks without a valid insertion point
394   // (catchswitch blocks).
395   if (BB->getFirstInsertionPt() == BB->end())
396     return false;
397 
398   if (!ClPruneBlocks || &F.getEntryBlock() == BB)
399     return true;
400 
401   return !(isFullDominator(BB, DT) || isFullPostDominator(BB, PDT));
402 }
403 
404 bool SanitizerCoverageModule::runOnFunction(Function &F) {
405   if (F.empty())
406     return false;
407   if (F.getName().find(".module_ctor") != std::string::npos)
408     return false; // Should not instrument sanitizer init functions.
409   if (F.getName().startswith("__sanitizer_"))
410     return false;  // Don't instrument __sanitizer_* callbacks.
411   // Don't instrument MSVC CRT configuration helpers. They may run before normal
412   // initialization.
413   if (F.getName() == "__local_stdio_printf_options" ||
414       F.getName() == "__local_stdio_scanf_options")
415     return false;
416   // Don't instrument functions using SEH for now. Splitting basic blocks like
417   // we do for coverage breaks WinEHPrepare.
418   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
419   if (F.hasPersonalityFn() &&
420       isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
421     return false;
422   if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
423     SplitAllCriticalEdges(F);
424   SmallVector<Instruction *, 8> IndirCalls;
425   SmallVector<BasicBlock *, 16> BlocksToInstrument;
426   SmallVector<Instruction *, 8> CmpTraceTargets;
427   SmallVector<Instruction *, 8> SwitchTraceTargets;
428   SmallVector<BinaryOperator *, 8> DivTraceTargets;
429   SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
430 
431   const DominatorTree *DT =
432       &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
433   const PostDominatorTree *PDT =
434       &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree();
435 
436   for (auto &BB : F) {
437     if (shouldInstrumentBlock(F, &BB, DT, PDT))
438       BlocksToInstrument.push_back(&BB);
439     for (auto &Inst : BB) {
440       if (Options.IndirectCalls) {
441         CallSite CS(&Inst);
442         if (CS && !CS.getCalledFunction())
443           IndirCalls.push_back(&Inst);
444       }
445       if (Options.TraceCmp) {
446         if (isa<ICmpInst>(&Inst))
447           CmpTraceTargets.push_back(&Inst);
448         if (isa<SwitchInst>(&Inst))
449           SwitchTraceTargets.push_back(&Inst);
450       }
451       if (Options.TraceDiv)
452         if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
453           if (BO->getOpcode() == Instruction::SDiv ||
454               BO->getOpcode() == Instruction::UDiv)
455             DivTraceTargets.push_back(BO);
456       if (Options.TraceGep)
457         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
458           GepTraceTargets.push_back(GEP);
459    }
460   }
461 
462   InjectCoverage(F, BlocksToInstrument);
463   InjectCoverageForIndirectCalls(F, IndirCalls);
464   InjectTraceForCmp(F, CmpTraceTargets);
465   InjectTraceForSwitch(F, SwitchTraceTargets);
466   InjectTraceForDiv(F, DivTraceTargets);
467   InjectTraceForGep(F, GepTraceTargets);
468   return true;
469 }
470 void SanitizerCoverageModule::CreateFunctionGuardArray(size_t NumGuards,
471                                                        Function &F) {
472   if (!Options.TracePCGuard) return;
473   HasSancovGuardsSection = true;
474   ArrayType *ArrayOfInt32Ty = ArrayType::get(Int32Ty, NumGuards);
475   FunctionGuardArray = new GlobalVariable(
476       *CurModule, ArrayOfInt32Ty, false, GlobalVariable::PrivateLinkage,
477       Constant::getNullValue(ArrayOfInt32Ty), "__sancov_gen_");
478   if (auto Comdat = F.getComdat())
479     FunctionGuardArray->setComdat(Comdat);
480   FunctionGuardArray->setSection(getSanCovTracePCGuardSection());
481 }
482 
483 bool SanitizerCoverageModule::InjectCoverage(Function &F,
484                                              ArrayRef<BasicBlock *> AllBlocks) {
485   if (AllBlocks.empty()) return false;
486   switch (Options.CoverageType) {
487   case SanitizerCoverageOptions::SCK_None:
488     return false;
489   case SanitizerCoverageOptions::SCK_Function:
490     CreateFunctionGuardArray(1, F);
491     InjectCoverageAtBlock(F, F.getEntryBlock(), 0, false);
492     return true;
493   default: {
494     bool UseCalls = ClCoverageBlockThreshold < AllBlocks.size();
495     CreateFunctionGuardArray(AllBlocks.size(), F);
496     for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
497       InjectCoverageAtBlock(F, *AllBlocks[i], i, UseCalls);
498     return true;
499   }
500   }
501 }
502 
503 // On every indirect call we call a run-time function
504 // __sanitizer_cov_indir_call* with two parameters:
505 //   - callee address,
506 //   - global cache array that contains CacheSize pointers (zero-initialized).
507 //     The cache is used to speed up recording the caller-callee pairs.
508 // The address of the caller is passed implicitly via caller PC.
509 // CacheSize is encoded in the name of the run-time function.
510 void SanitizerCoverageModule::InjectCoverageForIndirectCalls(
511     Function &F, ArrayRef<Instruction *> IndirCalls) {
512   if (IndirCalls.empty())
513     return;
514   if (!Options.TracePC && !Options.TracePCGuard)
515     return;
516   for (auto I : IndirCalls) {
517     IRBuilder<> IRB(I);
518     CallSite CS(I);
519     Value *Callee = CS.getCalledValue();
520     if (isa<InlineAsm>(Callee))
521       continue;
522     IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
523   }
524 }
525 
526 // For every switch statement we insert a call:
527 // __sanitizer_cov_trace_switch(CondValue,
528 //      {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
529 
530 void SanitizerCoverageModule::InjectTraceForSwitch(
531     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
532   for (auto I : SwitchTraceTargets) {
533     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
534       IRBuilder<> IRB(I);
535       SmallVector<Constant *, 16> Initializers;
536       Value *Cond = SI->getCondition();
537       if (Cond->getType()->getScalarSizeInBits() >
538           Int64Ty->getScalarSizeInBits())
539         continue;
540       Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
541       Initializers.push_back(
542           ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
543       if (Cond->getType()->getScalarSizeInBits() <
544           Int64Ty->getScalarSizeInBits())
545         Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
546       for (auto It : SI->cases()) {
547         Constant *C = It.getCaseValue();
548         if (C->getType()->getScalarSizeInBits() <
549             Int64Ty->getScalarSizeInBits())
550           C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
551         Initializers.push_back(C);
552       }
553       std::sort(Initializers.begin() + 2, Initializers.end(),
554                 [](const Constant *A, const Constant *B) {
555                   return cast<ConstantInt>(A)->getLimitedValue() <
556                          cast<ConstantInt>(B)->getLimitedValue();
557                 });
558       ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
559       GlobalVariable *GV = new GlobalVariable(
560           *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
561           ConstantArray::get(ArrayOfInt64Ty, Initializers),
562           "__sancov_gen_cov_switch_values");
563       IRB.CreateCall(SanCovTraceSwitchFunction,
564                      {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
565     }
566   }
567 }
568 
569 void SanitizerCoverageModule::InjectTraceForDiv(
570     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
571   for (auto BO : DivTraceTargets) {
572     IRBuilder<> IRB(BO);
573     Value *A1 = BO->getOperand(1);
574     if (isa<ConstantInt>(A1)) continue;
575     if (!A1->getType()->isIntegerTy())
576       continue;
577     uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
578     int CallbackIdx = TypeSize == 32 ? 0 :
579         TypeSize == 64 ? 1 : -1;
580     if (CallbackIdx < 0) continue;
581     auto Ty = Type::getIntNTy(*C, TypeSize);
582     IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
583                    {IRB.CreateIntCast(A1, Ty, true)});
584   }
585 }
586 
587 void SanitizerCoverageModule::InjectTraceForGep(
588     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
589   for (auto GEP : GepTraceTargets) {
590     IRBuilder<> IRB(GEP);
591     for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
592       if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy())
593         IRB.CreateCall(SanCovTraceGepFunction,
594                        {IRB.CreateIntCast(*I, IntptrTy, true)});
595   }
596 }
597 
598 void SanitizerCoverageModule::InjectTraceForCmp(
599     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
600   for (auto I : CmpTraceTargets) {
601     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
602       IRBuilder<> IRB(ICMP);
603       Value *A0 = ICMP->getOperand(0);
604       Value *A1 = ICMP->getOperand(1);
605       if (!A0->getType()->isIntegerTy())
606         continue;
607       uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
608       int CallbackIdx = TypeSize == 8 ? 0 :
609                         TypeSize == 16 ? 1 :
610                         TypeSize == 32 ? 2 :
611                         TypeSize == 64 ? 3 : -1;
612       if (CallbackIdx < 0) continue;
613       // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
614       auto Ty = Type::getIntNTy(*C, TypeSize);
615       IRB.CreateCall(
616           SanCovTraceCmpFunction[CallbackIdx],
617           {IRB.CreateIntCast(A0, Ty, true), IRB.CreateIntCast(A1, Ty, true)});
618     }
619   }
620 }
621 
622 void SanitizerCoverageModule::SetNoSanitizeMetadata(Instruction *I) {
623   I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
624                  MDNode::get(*C, None));
625 }
626 
627 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
628                                                     size_t Idx, bool UseCalls) {
629   BasicBlock::iterator IP = BB.getFirstInsertionPt();
630   bool IsEntryBB = &BB == &F.getEntryBlock();
631   DebugLoc EntryLoc;
632   if (IsEntryBB) {
633     if (auto SP = F.getSubprogram())
634       EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
635     // Keep static allocas and llvm.localescape calls in the entry block.  Even
636     // if we aren't splitting the block, it's nice for allocas to be before
637     // calls.
638     IP = PrepareToSplitEntryBlock(BB, IP);
639   } else {
640     EntryLoc = IP->getDebugLoc();
641   }
642 
643   IRBuilder<> IRB(&*IP);
644   IRB.SetCurrentDebugLocation(EntryLoc);
645   if (Options.TracePC) {
646     IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
647     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
648   } else if (Options.TracePCGuard) {
649     auto GuardPtr = IRB.CreateIntToPtr(
650         IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
651                       ConstantInt::get(IntptrTy, Idx * 4)),
652         Int32PtrTy);
653     if (!UseCalls) {
654       auto GuardLoad = IRB.CreateLoad(GuardPtr);
655       GuardLoad->setAtomic(AtomicOrdering::Monotonic);
656       GuardLoad->setAlignment(8);
657       SetNoSanitizeMetadata(GuardLoad);  // Don't instrument with e.g. asan.
658       auto Cmp = IRB.CreateICmpNE(
659           GuardLoad, Constant::getNullValue(GuardLoad->getType()));
660       auto Ins = SplitBlockAndInsertIfThen(
661           Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
662       IRB.SetInsertPoint(Ins);
663       IRB.SetCurrentDebugLocation(EntryLoc);
664     }
665     IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
666     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
667   } else {
668     Value *GuardP = IRB.CreateAdd(
669         IRB.CreatePointerCast(GuardArray, IntptrTy),
670         ConstantInt::get(IntptrTy, (1 + NumberOfInstrumentedBlocks()) * 4));
671     GuardP = IRB.CreateIntToPtr(GuardP, Int32PtrTy);
672     if (UseCalls) {
673       IRB.CreateCall(SanCovWithCheckFunction, GuardP);
674     } else {
675       LoadInst *Load = IRB.CreateLoad(GuardP);
676       Load->setAtomic(AtomicOrdering::Monotonic);
677       Load->setAlignment(4);
678       SetNoSanitizeMetadata(Load);
679       Value *Cmp =
680           IRB.CreateICmpSGE(Constant::getNullValue(Load->getType()), Load);
681       Instruction *Ins = SplitBlockAndInsertIfThen(
682           Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
683       IRB.SetInsertPoint(Ins);
684       IRB.SetCurrentDebugLocation(EntryLoc);
685       // __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
686       IRB.CreateCall(SanCovFunction, GuardP);
687       IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
688     }
689   }
690 }
691 
692 StringRef SanitizerCoverageModule::getSanCovTracePCGuardSection() const {
693   if (TargetTriple.getObjectFormat() == Triple::COFF)
694     return ".SCOV$M";
695   if (TargetTriple.isOSBinFormatMachO())
696     return "__DATA,__sancov_guards";
697   return "__sancov_guards";
698 }
699 
700 StringRef SanitizerCoverageModule::getSanCovTracePCGuardSectionStart() const {
701   if (TargetTriple.isOSBinFormatMachO())
702     return "\1section$start$__DATA$__sancov_guards";
703   return "__start___sancov_guards";
704 }
705 
706 StringRef SanitizerCoverageModule::getSanCovTracePCGuardSectionEnd() const {
707   if (TargetTriple.isOSBinFormatMachO())
708     return "\1section$end$__DATA$__sancov_guards";
709   return "__stop___sancov_guards";
710 }
711 
712 
713 char SanitizerCoverageModule::ID = 0;
714 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov",
715                       "SanitizerCoverage: TODO."
716                       "ModulePass",
717                       false, false)
718 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
719 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
720 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov",
721                     "SanitizerCoverage: TODO."
722                     "ModulePass",
723                     false, false)
724 ModulePass *llvm::createSanitizerCoverageModulePass(
725     const SanitizerCoverageOptions &Options) {
726   return new SanitizerCoverageModule(Options);
727 }
728