xref: /llvm-project/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp (revision 018472c34ab877b96787d4317b95b2aa3aaafef0) 
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   Options.NoPrune |= !ClPruneBlocks;
155   return Options;
156 }
157 
158 class SanitizerCoverageModule : public ModulePass {
159 public:
160   SanitizerCoverageModule(
161       const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
162       : ModulePass(ID), Options(OverrideFromCL(Options)) {
163     initializeSanitizerCoverageModulePass(*PassRegistry::getPassRegistry());
164   }
165   bool runOnModule(Module &M) override;
166   bool runOnFunction(Function &F);
167   static char ID; // Pass identification, replacement for typeid
168   StringRef getPassName() const override { return "SanitizerCoverageModule"; }
169 
170   void getAnalysisUsage(AnalysisUsage &AU) const override {
171     AU.addRequired<DominatorTreeWrapperPass>();
172     AU.addRequired<PostDominatorTreeWrapperPass>();
173   }
174 
175 private:
176   void InjectCoverageForIndirectCalls(Function &F,
177                                       ArrayRef<Instruction *> IndirCalls);
178   void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
179   void InjectTraceForDiv(Function &F,
180                          ArrayRef<BinaryOperator *> DivTraceTargets);
181   void InjectTraceForGep(Function &F,
182                          ArrayRef<GetElementPtrInst *> GepTraceTargets);
183   void InjectTraceForSwitch(Function &F,
184                             ArrayRef<Instruction *> SwitchTraceTargets);
185   bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks);
186   void CreateFunctionGuardArray(size_t NumGuards, Function &F);
187   void SetNoSanitizeMetadata(Instruction *I);
188   void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
189                              bool UseCalls);
190   unsigned NumberOfInstrumentedBlocks() {
191     return SanCovFunction->getNumUses() +
192            SanCovWithCheckFunction->getNumUses();
193   }
194   StringRef getSanCovTracePCGuardSection() const;
195   StringRef getSanCovTracePCGuardSectionStart() const;
196   StringRef getSanCovTracePCGuardSectionEnd() const;
197   Function *SanCovFunction;
198   Function *SanCovWithCheckFunction;
199   Function *SanCovTracePCIndir;
200   Function *SanCovTracePC, *SanCovTracePCGuard;
201   Function *SanCovTraceCmpFunction[4];
202   Function *SanCovTraceDivFunction[2];
203   Function *SanCovTraceGepFunction;
204   Function *SanCovTraceSwitchFunction;
205   InlineAsm *EmptyAsm;
206   Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy;
207   Module *CurModule;
208   Triple TargetTriple;
209   LLVMContext *C;
210   const DataLayout *DL;
211 
212   GlobalVariable *GuardArray;
213   GlobalVariable *FunctionGuardArray;  // for trace-pc-guard.
214   bool HasSancovGuardsSection;
215 
216   SanitizerCoverageOptions Options;
217 };
218 
219 } // namespace
220 
221 bool SanitizerCoverageModule::runOnModule(Module &M) {
222   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
223     return false;
224   C = &(M.getContext());
225   DL = &M.getDataLayout();
226   CurModule = &M;
227   TargetTriple = Triple(M.getTargetTriple());
228   HasSancovGuardsSection = false;
229   IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
230   IntptrPtrTy = PointerType::getUnqual(IntptrTy);
231   Type *VoidTy = Type::getVoidTy(*C);
232   IRBuilder<> IRB(*C);
233   Type *Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
234   Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
235   Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
236   Int64Ty = IRB.getInt64Ty();
237   Int32Ty = IRB.getInt32Ty();
238 
239   SanCovFunction = checkSanitizerInterfaceFunction(
240       M.getOrInsertFunction(SanCovName, VoidTy, Int32PtrTy));
241   SanCovWithCheckFunction = checkSanitizerInterfaceFunction(
242       M.getOrInsertFunction(SanCovWithCheckName, VoidTy, Int32PtrTy));
243   SanCovTracePCIndir = checkSanitizerInterfaceFunction(
244       M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy));
245   SanCovTraceCmpFunction[0] =
246       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
247           SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty()));
248   SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction(
249       M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(),
250                             IRB.getInt16Ty()));
251   SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction(
252       M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(),
253                             IRB.getInt32Ty()));
254   SanCovTraceCmpFunction[3] =
255       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
256           SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty));
257 
258   SanCovTraceDivFunction[0] =
259       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
260           SanCovTraceDiv4, VoidTy, IRB.getInt32Ty()));
261   SanCovTraceDivFunction[1] =
262       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
263           SanCovTraceDiv8, VoidTy, Int64Ty));
264   SanCovTraceGepFunction =
265       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
266           SanCovTraceGep, VoidTy, IntptrTy));
267   SanCovTraceSwitchFunction =
268       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
269           SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy));
270 
271   // We insert an empty inline asm after cov callbacks to avoid callback merge.
272   EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
273                             StringRef(""), StringRef(""),
274                             /*hasSideEffects=*/true);
275 
276   SanCovTracePC = checkSanitizerInterfaceFunction(
277       M.getOrInsertFunction(SanCovTracePCName, VoidTy));
278   SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
279       SanCovTracePCGuardName, VoidTy, Int32PtrTy));
280 
281   // At this point we create a dummy array of guards because we don't
282   // know how many elements we will need.
283   Type *Int32Ty = IRB.getInt32Ty();
284 
285   if (!Options.TracePCGuard)
286     GuardArray =
287         new GlobalVariable(M, Int32Ty, false, GlobalValue::ExternalLinkage,
288                            nullptr, "__sancov_gen_cov_tmp");
289 
290   for (auto &F : M)
291     runOnFunction(F);
292 
293   auto N = NumberOfInstrumentedBlocks();
294 
295   GlobalVariable *RealGuardArray = nullptr;
296   if (!Options.TracePCGuard) {
297     // Now we know how many elements we need. Create an array of guards
298     // with one extra element at the beginning for the size.
299     Type *Int32ArrayNTy = ArrayType::get(Int32Ty, N + 1);
300     RealGuardArray = new GlobalVariable(
301         M, Int32ArrayNTy, false, GlobalValue::PrivateLinkage,
302         Constant::getNullValue(Int32ArrayNTy), "__sancov_gen_cov");
303 
304     // Replace the dummy array with the real one.
305     GuardArray->replaceAllUsesWith(
306         IRB.CreatePointerCast(RealGuardArray, Int32PtrTy));
307     GuardArray->eraseFromParent();
308   }
309 
310   // Create variable for module (compilation unit) name
311   Constant *ModNameStrConst =
312       ConstantDataArray::getString(M.getContext(), M.getName(), true);
313   GlobalVariable *ModuleName = new GlobalVariable(
314       M, ModNameStrConst->getType(), true, GlobalValue::PrivateLinkage,
315       ModNameStrConst, "__sancov_gen_modname");
316   if (Options.TracePCGuard) {
317     if (HasSancovGuardsSection) {
318       Function *CtorFunc;
319       GlobalVariable *SecStart = new GlobalVariable(
320           M, Int32PtrTy, false, GlobalVariable::ExternalLinkage, nullptr,
321           getSanCovTracePCGuardSectionStart());
322       SecStart->setVisibility(GlobalValue::HiddenVisibility);
323       GlobalVariable *SecEnd = new GlobalVariable(
324           M, Int32PtrTy, false, GlobalVariable::ExternalLinkage, nullptr,
325           getSanCovTracePCGuardSectionEnd());
326       SecEnd->setVisibility(GlobalValue::HiddenVisibility);
327 
328       std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
329           M, SanCovModuleCtorName, SanCovTracePCGuardInitName,
330           {Int32PtrTy, Int32PtrTy},
331           {IRB.CreatePointerCast(SecStart, Int32PtrTy),
332             IRB.CreatePointerCast(SecEnd, Int32PtrTy)});
333 
334       if (TargetTriple.supportsCOMDAT()) {
335         // Use comdat to dedup CtorFunc.
336         CtorFunc->setComdat(M.getOrInsertComdat(SanCovModuleCtorName));
337         appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
338       } else {
339         appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
340       }
341     }
342   } else if (!Options.TracePC) {
343     Function *CtorFunc;
344     std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
345         M, SanCovModuleCtorName, SanCovModuleInitName,
346         {Int32PtrTy, IntptrTy, Int8PtrTy, Int8PtrTy},
347         {IRB.CreatePointerCast(RealGuardArray, Int32PtrTy),
348          ConstantInt::get(IntptrTy, N), Constant::getNullValue(Int8PtrTy),
349          IRB.CreatePointerCast(ModuleName, Int8PtrTy)});
350 
351     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
352   }
353 
354   return true;
355 }
356 
357 // True if block has successors and it dominates all of them.
358 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
359   if (succ_begin(BB) == succ_end(BB))
360     return false;
361 
362   for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
363     if (!DT->dominates(BB, SUCC))
364       return false;
365   }
366 
367   return true;
368 }
369 
370 // True if block has predecessors and it postdominates all of them.
371 static bool isFullPostDominator(const BasicBlock *BB,
372                                 const PostDominatorTree *PDT) {
373   if (pred_begin(BB) == pred_end(BB))
374     return false;
375 
376   for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
377     if (!PDT->dominates(BB, PRED))
378       return false;
379   }
380 
381   return true;
382 }
383 
384 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
385                                   const DominatorTree *DT,
386                                   const PostDominatorTree *PDT,
387                                   const SanitizerCoverageOptions &Options) {
388   // Don't insert coverage for unreachable blocks: we will never call
389   // __sanitizer_cov() for them, so counting them in
390   // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
391   // percentage. Also, unreachable instructions frequently have no debug
392   // locations.
393   if (isa<UnreachableInst>(BB->getTerminator()))
394     return false;
395 
396   // Don't insert coverage into blocks without a valid insertion point
397   // (catchswitch blocks).
398   if (BB->getFirstInsertionPt() == BB->end())
399     return false;
400 
401   if (Options.NoPrune || &F.getEntryBlock() == BB)
402     return true;
403 
404   return !(isFullDominator(BB, DT) || isFullPostDominator(BB, PDT));
405 }
406 
407 bool SanitizerCoverageModule::runOnFunction(Function &F) {
408   if (F.empty())
409     return false;
410   if (F.getName().find(".module_ctor") != std::string::npos)
411     return false; // Should not instrument sanitizer init functions.
412   if (F.getName().startswith("__sanitizer_"))
413     return false;  // Don't instrument __sanitizer_* callbacks.
414   // Don't instrument MSVC CRT configuration helpers. They may run before normal
415   // initialization.
416   if (F.getName() == "__local_stdio_printf_options" ||
417       F.getName() == "__local_stdio_scanf_options")
418     return false;
419   // Don't instrument functions using SEH for now. Splitting basic blocks like
420   // we do for coverage breaks WinEHPrepare.
421   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
422   if (F.hasPersonalityFn() &&
423       isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
424     return false;
425   if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
426     SplitAllCriticalEdges(F);
427   SmallVector<Instruction *, 8> IndirCalls;
428   SmallVector<BasicBlock *, 16> BlocksToInstrument;
429   SmallVector<Instruction *, 8> CmpTraceTargets;
430   SmallVector<Instruction *, 8> SwitchTraceTargets;
431   SmallVector<BinaryOperator *, 8> DivTraceTargets;
432   SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
433 
434   const DominatorTree *DT =
435       &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
436   const PostDominatorTree *PDT =
437       &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree();
438 
439   for (auto &BB : F) {
440     if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
441       BlocksToInstrument.push_back(&BB);
442     for (auto &Inst : BB) {
443       if (Options.IndirectCalls) {
444         CallSite CS(&Inst);
445         if (CS && !CS.getCalledFunction())
446           IndirCalls.push_back(&Inst);
447       }
448       if (Options.TraceCmp) {
449         if (isa<ICmpInst>(&Inst))
450           CmpTraceTargets.push_back(&Inst);
451         if (isa<SwitchInst>(&Inst))
452           SwitchTraceTargets.push_back(&Inst);
453       }
454       if (Options.TraceDiv)
455         if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
456           if (BO->getOpcode() == Instruction::SDiv ||
457               BO->getOpcode() == Instruction::UDiv)
458             DivTraceTargets.push_back(BO);
459       if (Options.TraceGep)
460         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
461           GepTraceTargets.push_back(GEP);
462    }
463   }
464 
465   InjectCoverage(F, BlocksToInstrument);
466   InjectCoverageForIndirectCalls(F, IndirCalls);
467   InjectTraceForCmp(F, CmpTraceTargets);
468   InjectTraceForSwitch(F, SwitchTraceTargets);
469   InjectTraceForDiv(F, DivTraceTargets);
470   InjectTraceForGep(F, GepTraceTargets);
471   return true;
472 }
473 void SanitizerCoverageModule::CreateFunctionGuardArray(size_t NumGuards,
474                                                        Function &F) {
475   if (!Options.TracePCGuard) return;
476   HasSancovGuardsSection = true;
477   ArrayType *ArrayOfInt32Ty = ArrayType::get(Int32Ty, NumGuards);
478   FunctionGuardArray = new GlobalVariable(
479       *CurModule, ArrayOfInt32Ty, false, GlobalVariable::PrivateLinkage,
480       Constant::getNullValue(ArrayOfInt32Ty), "__sancov_gen_");
481   if (auto Comdat = F.getComdat())
482     FunctionGuardArray->setComdat(Comdat);
483   FunctionGuardArray->setSection(getSanCovTracePCGuardSection());
484 }
485 
486 bool SanitizerCoverageModule::InjectCoverage(Function &F,
487                                              ArrayRef<BasicBlock *> AllBlocks) {
488   if (AllBlocks.empty()) return false;
489   switch (Options.CoverageType) {
490   case SanitizerCoverageOptions::SCK_None:
491     return false;
492   case SanitizerCoverageOptions::SCK_Function:
493     CreateFunctionGuardArray(1, F);
494     InjectCoverageAtBlock(F, F.getEntryBlock(), 0, false);
495     return true;
496   default: {
497     bool UseCalls = ClCoverageBlockThreshold < AllBlocks.size();
498     CreateFunctionGuardArray(AllBlocks.size(), F);
499     for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
500       InjectCoverageAtBlock(F, *AllBlocks[i], i, UseCalls);
501     return true;
502   }
503   }
504 }
505 
506 // On every indirect call we call a run-time function
507 // __sanitizer_cov_indir_call* with two parameters:
508 //   - callee address,
509 //   - global cache array that contains CacheSize pointers (zero-initialized).
510 //     The cache is used to speed up recording the caller-callee pairs.
511 // The address of the caller is passed implicitly via caller PC.
512 // CacheSize is encoded in the name of the run-time function.
513 void SanitizerCoverageModule::InjectCoverageForIndirectCalls(
514     Function &F, ArrayRef<Instruction *> IndirCalls) {
515   if (IndirCalls.empty())
516     return;
517   if (!Options.TracePC && !Options.TracePCGuard)
518     return;
519   for (auto I : IndirCalls) {
520     IRBuilder<> IRB(I);
521     CallSite CS(I);
522     Value *Callee = CS.getCalledValue();
523     if (isa<InlineAsm>(Callee))
524       continue;
525     IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
526   }
527 }
528 
529 // For every switch statement we insert a call:
530 // __sanitizer_cov_trace_switch(CondValue,
531 //      {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
532 
533 void SanitizerCoverageModule::InjectTraceForSwitch(
534     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
535   for (auto I : SwitchTraceTargets) {
536     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
537       IRBuilder<> IRB(I);
538       SmallVector<Constant *, 16> Initializers;
539       Value *Cond = SI->getCondition();
540       if (Cond->getType()->getScalarSizeInBits() >
541           Int64Ty->getScalarSizeInBits())
542         continue;
543       Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
544       Initializers.push_back(
545           ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
546       if (Cond->getType()->getScalarSizeInBits() <
547           Int64Ty->getScalarSizeInBits())
548         Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
549       for (auto It : SI->cases()) {
550         Constant *C = It.getCaseValue();
551         if (C->getType()->getScalarSizeInBits() <
552             Int64Ty->getScalarSizeInBits())
553           C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
554         Initializers.push_back(C);
555       }
556       std::sort(Initializers.begin() + 2, Initializers.end(),
557                 [](const Constant *A, const Constant *B) {
558                   return cast<ConstantInt>(A)->getLimitedValue() <
559                          cast<ConstantInt>(B)->getLimitedValue();
560                 });
561       ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
562       GlobalVariable *GV = new GlobalVariable(
563           *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
564           ConstantArray::get(ArrayOfInt64Ty, Initializers),
565           "__sancov_gen_cov_switch_values");
566       IRB.CreateCall(SanCovTraceSwitchFunction,
567                      {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
568     }
569   }
570 }
571 
572 void SanitizerCoverageModule::InjectTraceForDiv(
573     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
574   for (auto BO : DivTraceTargets) {
575     IRBuilder<> IRB(BO);
576     Value *A1 = BO->getOperand(1);
577     if (isa<ConstantInt>(A1)) continue;
578     if (!A1->getType()->isIntegerTy())
579       continue;
580     uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
581     int CallbackIdx = TypeSize == 32 ? 0 :
582         TypeSize == 64 ? 1 : -1;
583     if (CallbackIdx < 0) continue;
584     auto Ty = Type::getIntNTy(*C, TypeSize);
585     IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
586                    {IRB.CreateIntCast(A1, Ty, true)});
587   }
588 }
589 
590 void SanitizerCoverageModule::InjectTraceForGep(
591     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
592   for (auto GEP : GepTraceTargets) {
593     IRBuilder<> IRB(GEP);
594     for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
595       if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy())
596         IRB.CreateCall(SanCovTraceGepFunction,
597                        {IRB.CreateIntCast(*I, IntptrTy, true)});
598   }
599 }
600 
601 void SanitizerCoverageModule::InjectTraceForCmp(
602     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
603   for (auto I : CmpTraceTargets) {
604     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
605       IRBuilder<> IRB(ICMP);
606       Value *A0 = ICMP->getOperand(0);
607       Value *A1 = ICMP->getOperand(1);
608       if (!A0->getType()->isIntegerTy())
609         continue;
610       uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
611       int CallbackIdx = TypeSize == 8 ? 0 :
612                         TypeSize == 16 ? 1 :
613                         TypeSize == 32 ? 2 :
614                         TypeSize == 64 ? 3 : -1;
615       if (CallbackIdx < 0) continue;
616       // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
617       auto Ty = Type::getIntNTy(*C, TypeSize);
618       IRB.CreateCall(
619           SanCovTraceCmpFunction[CallbackIdx],
620           {IRB.CreateIntCast(A0, Ty, true), IRB.CreateIntCast(A1, Ty, true)});
621     }
622   }
623 }
624 
625 void SanitizerCoverageModule::SetNoSanitizeMetadata(Instruction *I) {
626   I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
627                  MDNode::get(*C, None));
628 }
629 
630 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
631                                                     size_t Idx, bool UseCalls) {
632   BasicBlock::iterator IP = BB.getFirstInsertionPt();
633   bool IsEntryBB = &BB == &F.getEntryBlock();
634   DebugLoc EntryLoc;
635   if (IsEntryBB) {
636     if (auto SP = F.getSubprogram())
637       EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
638     // Keep static allocas and llvm.localescape calls in the entry block.  Even
639     // if we aren't splitting the block, it's nice for allocas to be before
640     // calls.
641     IP = PrepareToSplitEntryBlock(BB, IP);
642   } else {
643     EntryLoc = IP->getDebugLoc();
644   }
645 
646   IRBuilder<> IRB(&*IP);
647   IRB.SetCurrentDebugLocation(EntryLoc);
648   if (Options.TracePC) {
649     IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
650     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
651   } else if (Options.TracePCGuard) {
652     auto GuardPtr = IRB.CreateIntToPtr(
653         IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
654                       ConstantInt::get(IntptrTy, Idx * 4)),
655         Int32PtrTy);
656     if (!UseCalls) {
657       auto GuardLoad = IRB.CreateLoad(GuardPtr);
658       GuardLoad->setAtomic(AtomicOrdering::Monotonic);
659       GuardLoad->setAlignment(8);
660       SetNoSanitizeMetadata(GuardLoad);  // Don't instrument with e.g. asan.
661       auto Cmp = IRB.CreateICmpNE(
662           GuardLoad, Constant::getNullValue(GuardLoad->getType()));
663       auto Ins = SplitBlockAndInsertIfThen(
664           Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
665       IRB.SetInsertPoint(Ins);
666       IRB.SetCurrentDebugLocation(EntryLoc);
667     }
668     IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
669     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
670   } else {
671     Value *GuardP = IRB.CreateAdd(
672         IRB.CreatePointerCast(GuardArray, IntptrTy),
673         ConstantInt::get(IntptrTy, (1 + NumberOfInstrumentedBlocks()) * 4));
674     GuardP = IRB.CreateIntToPtr(GuardP, Int32PtrTy);
675     if (UseCalls) {
676       IRB.CreateCall(SanCovWithCheckFunction, GuardP);
677     } else {
678       LoadInst *Load = IRB.CreateLoad(GuardP);
679       Load->setAtomic(AtomicOrdering::Monotonic);
680       Load->setAlignment(4);
681       SetNoSanitizeMetadata(Load);
682       Value *Cmp =
683           IRB.CreateICmpSGE(Constant::getNullValue(Load->getType()), Load);
684       Instruction *Ins = SplitBlockAndInsertIfThen(
685           Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
686       IRB.SetInsertPoint(Ins);
687       IRB.SetCurrentDebugLocation(EntryLoc);
688       // __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
689       IRB.CreateCall(SanCovFunction, GuardP);
690       IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
691     }
692   }
693 }
694 
695 StringRef SanitizerCoverageModule::getSanCovTracePCGuardSection() const {
696   if (TargetTriple.getObjectFormat() == Triple::COFF)
697     return ".SCOV$M";
698   if (TargetTriple.isOSBinFormatMachO())
699     return "__DATA,__sancov_guards";
700   return "__sancov_guards";
701 }
702 
703 StringRef SanitizerCoverageModule::getSanCovTracePCGuardSectionStart() const {
704   if (TargetTriple.isOSBinFormatMachO())
705     return "\1section$start$__DATA$__sancov_guards";
706   return "__start___sancov_guards";
707 }
708 
709 StringRef SanitizerCoverageModule::getSanCovTracePCGuardSectionEnd() const {
710   if (TargetTriple.isOSBinFormatMachO())
711     return "\1section$end$__DATA$__sancov_guards";
712   return "__stop___sancov_guards";
713 }
714 
715 
716 char SanitizerCoverageModule::ID = 0;
717 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov",
718                       "SanitizerCoverage: TODO."
719                       "ModulePass",
720                       false, false)
721 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
722 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
723 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov",
724                     "SanitizerCoverage: TODO."
725                     "ModulePass",
726                     false, false)
727 ModulePass *llvm::createSanitizerCoverageModulePass(
728     const SanitizerCoverageOptions &Options) {
729   return new SanitizerCoverageModule(Options);
730 }
731