1 //===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Coverage instrumentation that works with AddressSanitizer
11 // and potentially with other Sanitizers.
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):
17 // __sanitizer_cov(&Guard);
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).
22 // With SCK_Edge we also split critical edges this effectively
23 // instrumenting all edges.
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.
29 //===----------------------------------------------------------------------===//
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"
57 #define DEBUG_TYPE "sancov"
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 SanCovIndirCallName = "__sanitizer_cov_indir_call16";
63 static const char *const SanCovTracePCIndirName =
64 "__sanitizer_cov_trace_pc_indir";
65 static const char *const SanCovTraceEnterName =
66 "__sanitizer_cov_trace_func_enter";
67 static const char *const SanCovTraceBBName =
68 "__sanitizer_cov_trace_basic_block";
69 static const char *const SanCovTracePCName = "__sanitizer_cov_trace_pc";
70 static const char *const SanCovTraceCmp1 = "__sanitizer_cov_trace_cmp1";
71 static const char *const SanCovTraceCmp2 = "__sanitizer_cov_trace_cmp2";
72 static const char *const SanCovTraceCmp4 = "__sanitizer_cov_trace_cmp4";
73 static const char *const SanCovTraceCmp8 = "__sanitizer_cov_trace_cmp8";
74 static const char *const SanCovTraceDiv4 = "__sanitizer_cov_trace_div4";
75 static const char *const SanCovTraceDiv8 = "__sanitizer_cov_trace_div8";
76 static const char *const SanCovTraceGep = "__sanitizer_cov_trace_gep";
77 static const char *const SanCovTraceSwitchName = "__sanitizer_cov_trace_switch";
78 static const char *const SanCovModuleCtorName = "sancov.module_ctor";
79 static const uint64_t SanCtorAndDtorPriority = 2;
81 static const char *const SanCovTracePCGuardSection = "__sancov_guards";
82 static const char *const SanCovTracePCGuardName =
83 "__sanitizer_cov_trace_pc_guard";
84 static const char *const SanCovTracePCGuardInitName =
85 "__sanitizer_cov_trace_pc_guard_init";
87 static cl::opt<int> ClCoverageLevel(
88 "sanitizer-coverage-level",
89 cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
90 "3: all blocks and critical edges, "
91 "4: above plus indirect calls"),
92 cl::Hidden, cl::init(0));
94 static cl::opt<unsigned> ClCoverageBlockThreshold(
95 "sanitizer-coverage-block-threshold",
96 cl::desc("Use a callback with a guard check inside it if there are"
97 " more than this number of blocks."),
98 cl::Hidden, cl::init(500));
101 ClExperimentalTracing("sanitizer-coverage-experimental-tracing",
102 cl::desc("Experimental basic-block tracing: insert "
103 "callbacks at every basic block"),
104 cl::Hidden, cl::init(false));
106 static cl::opt<bool> ClExperimentalTracePC("sanitizer-coverage-trace-pc",
107 cl::desc("Experimental pc tracing"),
108 cl::Hidden, cl::init(false));
110 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard",
111 cl::desc("pc tracing with a guard"),
112 cl::Hidden, cl::init(false));
115 ClCMPTracing("sanitizer-coverage-trace-compares",
116 cl::desc("Tracing of CMP and similar instructions"),
117 cl::Hidden, cl::init(false));
119 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs",
120 cl::desc("Tracing of DIV instructions"),
121 cl::Hidden, cl::init(false));
123 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps",
124 cl::desc("Tracing of GEP instructions"),
125 cl::Hidden, cl::init(false));
128 ClPruneBlocks("sanitizer-coverage-prune-blocks",
129 cl::desc("Reduce the number of instrumented blocks"),
130 cl::Hidden, cl::init(true));
132 // Experimental 8-bit counters used as an additional search heuristic during
133 // coverage-guided fuzzing.
134 // The counters are not thread-friendly:
135 // - contention on these counters may cause significant slowdown;
136 // - the counter updates are racy and the results may be inaccurate.
137 // They are also inaccurate due to 8-bit integer overflow.
138 static cl::opt<bool> ClUse8bitCounters("sanitizer-coverage-8bit-counters",
139 cl::desc("Experimental 8-bit counters"),
140 cl::Hidden, cl::init(false));
144 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
145 SanitizerCoverageOptions Res;
146 switch (LegacyCoverageLevel) {
148 Res.CoverageType = SanitizerCoverageOptions::SCK_None;
151 Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
154 Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
157 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
160 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
161 Res.IndirectCalls = true;
167 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
168 // Sets CoverageType and IndirectCalls.
169 SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
170 Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
171 Options.IndirectCalls |= CLOpts.IndirectCalls;
172 Options.TraceBB |= ClExperimentalTracing;
173 Options.TraceCmp |= ClCMPTracing;
174 Options.TraceDiv |= ClDIVTracing;
175 Options.TraceGep |= ClGEPTracing;
176 Options.Use8bitCounters |= ClUse8bitCounters;
177 Options.TracePC |= ClExperimentalTracePC;
178 Options.TracePCGuard |= ClTracePCGuard;
182 class SanitizerCoverageModule : public ModulePass {
184 SanitizerCoverageModule(
185 const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
186 : ModulePass(ID), Options(OverrideFromCL(Options)) {
187 initializeSanitizerCoverageModulePass(*PassRegistry::getPassRegistry());
189 bool runOnModule(Module &M) override;
190 bool runOnFunction(Function &F);
191 static char ID; // Pass identification, replacement for typeid
192 StringRef getPassName() const override { return "SanitizerCoverageModule"; }
194 void getAnalysisUsage(AnalysisUsage &AU) const override {
195 AU.addRequired<DominatorTreeWrapperPass>();
196 AU.addRequired<PostDominatorTreeWrapperPass>();
200 void InjectCoverageForIndirectCalls(Function &F,
201 ArrayRef<Instruction *> IndirCalls);
202 void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
203 void InjectTraceForDiv(Function &F,
204 ArrayRef<BinaryOperator *> DivTraceTargets);
205 void InjectTraceForGep(Function &F,
206 ArrayRef<GetElementPtrInst *> GepTraceTargets);
207 void InjectTraceForSwitch(Function &F,
208 ArrayRef<Instruction *> SwitchTraceTargets);
209 bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks);
210 void CreateFunctionGuardArray(size_t NumGuards, Function &F);
211 void SetNoSanitizeMetadata(Instruction *I);
212 void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
214 unsigned NumberOfInstrumentedBlocks() {
215 return SanCovFunction->getNumUses() +
216 SanCovWithCheckFunction->getNumUses() + SanCovTraceBB->getNumUses() +
217 SanCovTraceEnter->getNumUses();
219 Function *SanCovFunction;
220 Function *SanCovWithCheckFunction;
221 Function *SanCovIndirCallFunction, *SanCovTracePCIndir;
222 Function *SanCovTraceEnter, *SanCovTraceBB, *SanCovTracePC, *SanCovTracePCGuard;
223 Function *SanCovTraceCmpFunction[4];
224 Function *SanCovTraceDivFunction[2];
225 Function *SanCovTraceGepFunction;
226 Function *SanCovTraceSwitchFunction;
228 Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy;
231 const DataLayout *DL;
233 GlobalVariable *GuardArray;
234 GlobalVariable *FunctionGuardArray; // for trace-pc-guard.
235 GlobalVariable *EightBitCounterArray;
236 bool HasSancovGuardsSection;
238 SanitizerCoverageOptions Options;
243 bool SanitizerCoverageModule::runOnModule(Module &M) {
244 if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
246 C = &(M.getContext());
247 DL = &M.getDataLayout();
249 HasSancovGuardsSection = false;
250 IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
251 IntptrPtrTy = PointerType::getUnqual(IntptrTy);
252 Type *VoidTy = Type::getVoidTy(*C);
254 Type *Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
255 Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
256 Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
257 Int64Ty = IRB.getInt64Ty();
258 Int32Ty = IRB.getInt32Ty();
260 SanCovFunction = checkSanitizerInterfaceFunction(
261 M.getOrInsertFunction(SanCovName, VoidTy, Int32PtrTy, nullptr));
262 SanCovWithCheckFunction = checkSanitizerInterfaceFunction(
263 M.getOrInsertFunction(SanCovWithCheckName, VoidTy, Int32PtrTy, nullptr));
264 SanCovTracePCIndir = checkSanitizerInterfaceFunction(
265 M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy, nullptr));
266 SanCovIndirCallFunction =
267 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
268 SanCovIndirCallName, VoidTy, IntptrTy, IntptrTy, nullptr));
269 SanCovTraceCmpFunction[0] =
270 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
271 SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty(), nullptr));
272 SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction(
273 M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(),
274 IRB.getInt16Ty(), nullptr));
275 SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction(
276 M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(),
277 IRB.getInt32Ty(), nullptr));
278 SanCovTraceCmpFunction[3] =
279 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
280 SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty, nullptr));
282 SanCovTraceDivFunction[0] =
283 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
284 SanCovTraceDiv4, VoidTy, IRB.getInt32Ty(), nullptr));
285 SanCovTraceDivFunction[1] =
286 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
287 SanCovTraceDiv8, VoidTy, Int64Ty, nullptr));
288 SanCovTraceGepFunction =
289 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
290 SanCovTraceGep, VoidTy, IntptrTy, nullptr));
291 SanCovTraceSwitchFunction =
292 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
293 SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy, nullptr));
295 // We insert an empty inline asm after cov callbacks to avoid callback merge.
296 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
297 StringRef(""), StringRef(""),
298 /*hasSideEffects=*/true);
300 SanCovTracePC = checkSanitizerInterfaceFunction(
301 M.getOrInsertFunction(SanCovTracePCName, VoidTy, nullptr));
302 SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
303 SanCovTracePCGuardName, VoidTy, Int32PtrTy, nullptr));
304 SanCovTraceEnter = checkSanitizerInterfaceFunction(
305 M.getOrInsertFunction(SanCovTraceEnterName, VoidTy, Int32PtrTy, nullptr));
306 SanCovTraceBB = checkSanitizerInterfaceFunction(
307 M.getOrInsertFunction(SanCovTraceBBName, VoidTy, Int32PtrTy, nullptr));
309 // At this point we create a dummy array of guards because we don't
310 // know how many elements we will need.
311 Type *Int32Ty = IRB.getInt32Ty();
312 Type *Int8Ty = IRB.getInt8Ty();
314 if (!Options.TracePCGuard)
316 new GlobalVariable(M, Int32Ty, false, GlobalValue::ExternalLinkage,
317 nullptr, "__sancov_gen_cov_tmp");
318 if (Options.Use8bitCounters)
319 EightBitCounterArray =
320 new GlobalVariable(M, Int8Ty, false, GlobalVariable::ExternalLinkage,
321 nullptr, "__sancov_gen_cov_tmp");
326 auto N = NumberOfInstrumentedBlocks();
328 GlobalVariable *RealGuardArray = nullptr;
329 if (!Options.TracePCGuard) {
330 // Now we know how many elements we need. Create an array of guards
331 // with one extra element at the beginning for the size.
332 Type *Int32ArrayNTy = ArrayType::get(Int32Ty, N + 1);
333 RealGuardArray = new GlobalVariable(
334 M, Int32ArrayNTy, false, GlobalValue::PrivateLinkage,
335 Constant::getNullValue(Int32ArrayNTy), "__sancov_gen_cov");
337 // Replace the dummy array with the real one.
338 GuardArray->replaceAllUsesWith(
339 IRB.CreatePointerCast(RealGuardArray, Int32PtrTy));
340 GuardArray->eraseFromParent();
343 GlobalVariable *RealEightBitCounterArray;
344 if (Options.Use8bitCounters) {
345 // Make sure the array is 16-aligned.
346 static const int CounterAlignment = 16;
347 Type *Int8ArrayNTy = ArrayType::get(Int8Ty, alignTo(N, CounterAlignment));
348 RealEightBitCounterArray = new GlobalVariable(
349 M, Int8ArrayNTy, false, GlobalValue::PrivateLinkage,
350 Constant::getNullValue(Int8ArrayNTy), "__sancov_gen_cov_counter");
351 RealEightBitCounterArray->setAlignment(CounterAlignment);
352 EightBitCounterArray->replaceAllUsesWith(
353 IRB.CreatePointerCast(RealEightBitCounterArray, Int8PtrTy));
354 EightBitCounterArray->eraseFromParent();
357 // Create variable for module (compilation unit) name
358 Constant *ModNameStrConst =
359 ConstantDataArray::getString(M.getContext(), M.getName(), true);
360 GlobalVariable *ModuleName = new GlobalVariable(
361 M, ModNameStrConst->getType(), true, GlobalValue::PrivateLinkage,
362 ModNameStrConst, "__sancov_gen_modname");
363 if (Options.TracePCGuard) {
364 if (HasSancovGuardsSection) {
366 std::string SectionName(SanCovTracePCGuardSection);
367 GlobalVariable *Bounds[2];
368 const char *Prefix[2] = {"__start_", "__stop_"};
369 for (int i = 0; i < 2; i++) {
370 Bounds[i] = new GlobalVariable(M, Int32PtrTy, false,
371 GlobalVariable::ExternalLinkage, nullptr,
372 Prefix[i] + SectionName);
373 Bounds[i]->setVisibility(GlobalValue::HiddenVisibility);
375 std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
376 M, SanCovModuleCtorName, SanCovTracePCGuardInitName,
377 {Int32PtrTy, Int32PtrTy},
378 {IRB.CreatePointerCast(Bounds[0], Int32PtrTy),
379 IRB.CreatePointerCast(Bounds[1], Int32PtrTy)});
381 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
383 } else if (!Options.TracePC) {
385 std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
386 M, SanCovModuleCtorName, SanCovModuleInitName,
387 {Int32PtrTy, IntptrTy, Int8PtrTy, Int8PtrTy},
388 {IRB.CreatePointerCast(RealGuardArray, Int32PtrTy),
389 ConstantInt::get(IntptrTy, N),
390 Options.Use8bitCounters
391 ? IRB.CreatePointerCast(RealEightBitCounterArray, Int8PtrTy)
392 : Constant::getNullValue(Int8PtrTy),
393 IRB.CreatePointerCast(ModuleName, Int8PtrTy)});
395 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
401 // True if block has successors and it dominates all of them.
402 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
403 if (succ_begin(BB) == succ_end(BB))
406 for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
407 if (!DT->dominates(BB, SUCC))
414 // True if block has predecessors and it postdominates all of them.
415 static bool isFullPostDominator(const BasicBlock *BB,
416 const PostDominatorTree *PDT) {
417 if (pred_begin(BB) == pred_end(BB))
420 for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
421 if (!PDT->dominates(BB, PRED))
428 static bool shouldInstrumentBlock(const Function& F, const BasicBlock *BB, const DominatorTree *DT,
429 const PostDominatorTree *PDT) {
430 // Don't insert coverage for unreachable blocks: we will never call
431 // __sanitizer_cov() for them, so counting them in
432 // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
433 // percentage. Also, unreachable instructions frequently have no debug
435 if (isa<UnreachableInst>(BB->getTerminator()))
438 if (!ClPruneBlocks || &F.getEntryBlock() == BB)
441 return !(isFullDominator(BB, DT) || isFullPostDominator(BB, PDT));
444 bool SanitizerCoverageModule::runOnFunction(Function &F) {
447 if (F.getName().find(".module_ctor") != std::string::npos)
448 return false; // Should not instrument sanitizer init functions.
449 if (F.getName().startswith("__sanitizer_"))
450 return false; // Don't instrument __sanitizer_* callbacks.
451 // Don't instrument MSVC CRT configuration helpers. They may run before normal
453 if (F.getName() == "__local_stdio_printf_options" ||
454 F.getName() == "__local_stdio_scanf_options")
456 // Don't instrument functions using SEH for now. Splitting basic blocks like
457 // we do for coverage breaks WinEHPrepare.
458 // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
459 if (F.hasPersonalityFn() &&
460 isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
462 if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
463 SplitAllCriticalEdges(F);
464 SmallVector<Instruction *, 8> IndirCalls;
465 SmallVector<BasicBlock *, 16> BlocksToInstrument;
466 SmallVector<Instruction *, 8> CmpTraceTargets;
467 SmallVector<Instruction *, 8> SwitchTraceTargets;
468 SmallVector<BinaryOperator *, 8> DivTraceTargets;
469 SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
471 const DominatorTree *DT =
472 &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
473 const PostDominatorTree *PDT =
474 &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree();
477 if (shouldInstrumentBlock(F, &BB, DT, PDT))
478 BlocksToInstrument.push_back(&BB);
479 for (auto &Inst : BB) {
480 if (Options.IndirectCalls) {
482 if (CS && !CS.getCalledFunction())
483 IndirCalls.push_back(&Inst);
485 if (Options.TraceCmp) {
486 if (isa<ICmpInst>(&Inst))
487 CmpTraceTargets.push_back(&Inst);
488 if (isa<SwitchInst>(&Inst))
489 SwitchTraceTargets.push_back(&Inst);
491 if (Options.TraceDiv)
492 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
493 if (BO->getOpcode() == Instruction::SDiv ||
494 BO->getOpcode() == Instruction::UDiv)
495 DivTraceTargets.push_back(BO);
496 if (Options.TraceGep)
497 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
498 GepTraceTargets.push_back(GEP);
502 InjectCoverage(F, BlocksToInstrument);
503 InjectCoverageForIndirectCalls(F, IndirCalls);
504 InjectTraceForCmp(F, CmpTraceTargets);
505 InjectTraceForSwitch(F, SwitchTraceTargets);
506 InjectTraceForDiv(F, DivTraceTargets);
507 InjectTraceForGep(F, GepTraceTargets);
510 void SanitizerCoverageModule::CreateFunctionGuardArray(size_t NumGuards,
512 if (!Options.TracePCGuard) return;
513 HasSancovGuardsSection = true;
514 ArrayType *ArrayOfInt32Ty = ArrayType::get(Int32Ty, NumGuards);
515 FunctionGuardArray = new GlobalVariable(
516 *CurModule, ArrayOfInt32Ty, false, GlobalVariable::PrivateLinkage,
517 Constant::getNullValue(ArrayOfInt32Ty), "__sancov_gen_");
518 if (auto Comdat = F.getComdat())
519 FunctionGuardArray->setComdat(Comdat);
520 FunctionGuardArray->setSection(SanCovTracePCGuardSection);
523 bool SanitizerCoverageModule::InjectCoverage(Function &F,
524 ArrayRef<BasicBlock *> AllBlocks) {
525 if (AllBlocks.empty()) return false;
526 switch (Options.CoverageType) {
527 case SanitizerCoverageOptions::SCK_None:
529 case SanitizerCoverageOptions::SCK_Function:
530 CreateFunctionGuardArray(1, F);
531 InjectCoverageAtBlock(F, F.getEntryBlock(), 0, false);
534 bool UseCalls = ClCoverageBlockThreshold < AllBlocks.size();
535 CreateFunctionGuardArray(AllBlocks.size(), F);
536 for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
537 InjectCoverageAtBlock(F, *AllBlocks[i], i, UseCalls);
543 // On every indirect call we call a run-time function
544 // __sanitizer_cov_indir_call* with two parameters:
546 // - global cache array that contains CacheSize pointers (zero-initialized).
547 // The cache is used to speed up recording the caller-callee pairs.
548 // The address of the caller is passed implicitly via caller PC.
549 // CacheSize is encoded in the name of the run-time function.
550 void SanitizerCoverageModule::InjectCoverageForIndirectCalls(
551 Function &F, ArrayRef<Instruction *> IndirCalls) {
552 if (IndirCalls.empty())
554 const int CacheSize = 16;
555 const int CacheAlignment = 64; // Align for better performance.
556 Type *Ty = ArrayType::get(IntptrTy, CacheSize);
557 for (auto I : IndirCalls) {
560 Value *Callee = CS.getCalledValue();
561 if (isa<InlineAsm>(Callee))
563 GlobalVariable *CalleeCache = new GlobalVariable(
564 *F.getParent(), Ty, false, GlobalValue::PrivateLinkage,
565 Constant::getNullValue(Ty), "__sancov_gen_callee_cache");
566 CalleeCache->setAlignment(CacheAlignment);
567 if (Options.TracePC || Options.TracePCGuard)
568 IRB.CreateCall(SanCovTracePCIndir,
569 IRB.CreatePointerCast(Callee, IntptrTy));
571 IRB.CreateCall(SanCovIndirCallFunction,
572 {IRB.CreatePointerCast(Callee, IntptrTy),
573 IRB.CreatePointerCast(CalleeCache, IntptrTy)});
577 // For every switch statement we insert a call:
578 // __sanitizer_cov_trace_switch(CondValue,
579 // {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
581 void SanitizerCoverageModule::InjectTraceForSwitch(
582 Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
583 for (auto I : SwitchTraceTargets) {
584 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
586 SmallVector<Constant *, 16> Initializers;
587 Value *Cond = SI->getCondition();
588 if (Cond->getType()->getScalarSizeInBits() >
589 Int64Ty->getScalarSizeInBits())
591 Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
592 Initializers.push_back(
593 ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
594 if (Cond->getType()->getScalarSizeInBits() <
595 Int64Ty->getScalarSizeInBits())
596 Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
597 for (auto It : SI->cases()) {
598 Constant *C = It.getCaseValue();
599 if (C->getType()->getScalarSizeInBits() <
600 Int64Ty->getScalarSizeInBits())
601 C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
602 Initializers.push_back(C);
604 std::sort(Initializers.begin() + 2, Initializers.end(),
605 [](const Constant *A, const Constant *B) {
606 return cast<ConstantInt>(A)->getLimitedValue() <
607 cast<ConstantInt>(B)->getLimitedValue();
609 ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
610 GlobalVariable *GV = new GlobalVariable(
611 *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
612 ConstantArray::get(ArrayOfInt64Ty, Initializers),
613 "__sancov_gen_cov_switch_values");
614 IRB.CreateCall(SanCovTraceSwitchFunction,
615 {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
620 void SanitizerCoverageModule::InjectTraceForDiv(
621 Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
622 for (auto BO : DivTraceTargets) {
624 Value *A1 = BO->getOperand(1);
625 if (isa<ConstantInt>(A1)) continue;
626 if (!A1->getType()->isIntegerTy())
628 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
629 int CallbackIdx = TypeSize == 32 ? 0 :
630 TypeSize == 64 ? 1 : -1;
631 if (CallbackIdx < 0) continue;
632 auto Ty = Type::getIntNTy(*C, TypeSize);
633 IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
634 {IRB.CreateIntCast(A1, Ty, true)});
638 void SanitizerCoverageModule::InjectTraceForGep(
639 Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
640 for (auto GEP : GepTraceTargets) {
641 IRBuilder<> IRB(GEP);
642 for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
643 if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy())
644 IRB.CreateCall(SanCovTraceGepFunction,
645 {IRB.CreateIntCast(*I, IntptrTy, true)});
649 void SanitizerCoverageModule::InjectTraceForCmp(
650 Function &, ArrayRef<Instruction *> CmpTraceTargets) {
651 for (auto I : CmpTraceTargets) {
652 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
653 IRBuilder<> IRB(ICMP);
654 Value *A0 = ICMP->getOperand(0);
655 Value *A1 = ICMP->getOperand(1);
656 if (!A0->getType()->isIntegerTy())
658 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
659 int CallbackIdx = TypeSize == 8 ? 0 :
662 TypeSize == 64 ? 3 : -1;
663 if (CallbackIdx < 0) continue;
664 // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
665 auto Ty = Type::getIntNTy(*C, TypeSize);
667 SanCovTraceCmpFunction[CallbackIdx],
668 {IRB.CreateIntCast(A0, Ty, true), IRB.CreateIntCast(A1, Ty, true)});
673 void SanitizerCoverageModule::SetNoSanitizeMetadata(Instruction *I) {
674 I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
675 MDNode::get(*C, None));
678 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
679 size_t Idx, bool UseCalls) {
680 BasicBlock::iterator IP = BB.getFirstInsertionPt();
681 bool IsEntryBB = &BB == &F.getEntryBlock();
684 if (auto SP = F.getSubprogram())
685 EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
686 // Keep static allocas and llvm.localescape calls in the entry block. Even
687 // if we aren't splitting the block, it's nice for allocas to be before
689 IP = PrepareToSplitEntryBlock(BB, IP);
691 EntryLoc = IP->getDebugLoc();
694 IRBuilder<> IRB(&*IP);
695 IRB.SetCurrentDebugLocation(EntryLoc);
696 if (Options.TracePC) {
697 IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
698 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
699 } else if (Options.TracePCGuard) {
700 auto GuardPtr = IRB.CreateIntToPtr(
701 IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
702 ConstantInt::get(IntptrTy, Idx * 4)),
705 auto GuardLoad = IRB.CreateLoad(GuardPtr);
706 GuardLoad->setAtomic(AtomicOrdering::Monotonic);
707 GuardLoad->setAlignment(8);
708 SetNoSanitizeMetadata(GuardLoad); // Don't instrument with e.g. asan.
709 auto Cmp = IRB.CreateICmpNE(
710 GuardLoad, Constant::getNullValue(GuardLoad->getType()));
711 auto Ins = SplitBlockAndInsertIfThen(
712 Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
713 IRB.SetInsertPoint(Ins);
714 IRB.SetCurrentDebugLocation(EntryLoc);
716 IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
717 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
719 Value *GuardP = IRB.CreateAdd(
720 IRB.CreatePointerCast(GuardArray, IntptrTy),
721 ConstantInt::get(IntptrTy, (1 + NumberOfInstrumentedBlocks()) * 4));
722 GuardP = IRB.CreateIntToPtr(GuardP, Int32PtrTy);
723 if (Options.TraceBB) {
724 IRB.CreateCall(IsEntryBB ? SanCovTraceEnter : SanCovTraceBB, GuardP);
725 } else if (UseCalls) {
726 IRB.CreateCall(SanCovWithCheckFunction, GuardP);
728 LoadInst *Load = IRB.CreateLoad(GuardP);
729 Load->setAtomic(AtomicOrdering::Monotonic);
730 Load->setAlignment(4);
731 SetNoSanitizeMetadata(Load);
733 IRB.CreateICmpSGE(Constant::getNullValue(Load->getType()), Load);
734 Instruction *Ins = SplitBlockAndInsertIfThen(
735 Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
736 IRB.SetInsertPoint(Ins);
737 IRB.SetCurrentDebugLocation(EntryLoc);
738 // __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
739 IRB.CreateCall(SanCovFunction, GuardP);
740 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
744 if (Options.Use8bitCounters) {
745 IRB.SetInsertPoint(&*IP);
746 Value *P = IRB.CreateAdd(
747 IRB.CreatePointerCast(EightBitCounterArray, IntptrTy),
748 ConstantInt::get(IntptrTy, NumberOfInstrumentedBlocks() - 1));
749 P = IRB.CreateIntToPtr(P, IRB.getInt8PtrTy());
750 LoadInst *LI = IRB.CreateLoad(P);
751 Value *Inc = IRB.CreateAdd(LI, ConstantInt::get(IRB.getInt8Ty(), 1));
752 StoreInst *SI = IRB.CreateStore(Inc, P);
753 SetNoSanitizeMetadata(LI);
754 SetNoSanitizeMetadata(SI);
758 char SanitizerCoverageModule::ID = 0;
759 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov",
760 "SanitizerCoverage: TODO."
763 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
764 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
765 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov",
766 "SanitizerCoverage: TODO."
769 ModulePass *llvm::createSanitizerCoverageModulePass(
770 const SanitizerCoverageOptions &Options) {
771 return new SanitizerCoverageModule(Options);