1 //===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // Coverage instrumentation done on LLVM IR level, works with Sanitizers.
11 //===----------------------------------------------------------------------===//
13 #include "llvm/Transforms/Instrumentation/SanitizerCoverage.h"
14 #include "llvm/ADT/ArrayRef.h"
15 #include "llvm/ADT/SmallVector.h"
16 #include "llvm/Analysis/EHPersonalities.h"
17 #include "llvm/Analysis/PostDominators.h"
18 #include "llvm/IR/CFG.h"
19 #include "llvm/IR/CallSite.h"
20 #include "llvm/IR/Constant.h"
21 #include "llvm/IR/DataLayout.h"
22 #include "llvm/IR/DebugInfo.h"
23 #include "llvm/IR/Dominators.h"
24 #include "llvm/IR/Function.h"
25 #include "llvm/IR/GlobalVariable.h"
26 #include "llvm/IR/IRBuilder.h"
27 #include "llvm/IR/InlineAsm.h"
28 #include "llvm/IR/IntrinsicInst.h"
29 #include "llvm/IR/Intrinsics.h"
30 #include "llvm/IR/LLVMContext.h"
31 #include "llvm/IR/MDBuilder.h"
32 #include "llvm/IR/Mangler.h"
33 #include "llvm/IR/Module.h"
34 #include "llvm/IR/Type.h"
35 #include "llvm/InitializePasses.h"
36 #include "llvm/Support/CommandLine.h"
37 #include "llvm/Support/Debug.h"
38 #include "llvm/Support/raw_ostream.h"
39 #include "llvm/Transforms/Instrumentation.h"
40 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
41 #include "llvm/Transforms/Utils/ModuleUtils.h"
45 #define DEBUG_TYPE "sancov"
47 static const char *const SanCovTracePCIndirName =
48 "__sanitizer_cov_trace_pc_indir";
49 static const char *const SanCovTracePCName = "__sanitizer_cov_trace_pc";
50 static const char *const SanCovTraceCmp1 = "__sanitizer_cov_trace_cmp1";
51 static const char *const SanCovTraceCmp2 = "__sanitizer_cov_trace_cmp2";
52 static const char *const SanCovTraceCmp4 = "__sanitizer_cov_trace_cmp4";
53 static const char *const SanCovTraceCmp8 = "__sanitizer_cov_trace_cmp8";
54 static const char *const SanCovTraceConstCmp1 =
55 "__sanitizer_cov_trace_const_cmp1";
56 static const char *const SanCovTraceConstCmp2 =
57 "__sanitizer_cov_trace_const_cmp2";
58 static const char *const SanCovTraceConstCmp4 =
59 "__sanitizer_cov_trace_const_cmp4";
60 static const char *const SanCovTraceConstCmp8 =
61 "__sanitizer_cov_trace_const_cmp8";
62 static const char *const SanCovTraceDiv4 = "__sanitizer_cov_trace_div4";
63 static const char *const SanCovTraceDiv8 = "__sanitizer_cov_trace_div8";
64 static const char *const SanCovTraceGep = "__sanitizer_cov_trace_gep";
65 static const char *const SanCovTraceSwitchName = "__sanitizer_cov_trace_switch";
66 static const char *const SanCovModuleCtorTracePcGuardName =
67 "sancov.module_ctor_trace_pc_guard";
68 static const char *const SanCovModuleCtor8bitCountersName =
69 "sancov.module_ctor_8bit_counters";
70 static const uint64_t SanCtorAndDtorPriority = 2;
72 static const char *const SanCovTracePCGuardName =
73 "__sanitizer_cov_trace_pc_guard";
74 static const char *const SanCovTracePCGuardInitName =
75 "__sanitizer_cov_trace_pc_guard_init";
76 static const char *const SanCov8bitCountersInitName =
77 "__sanitizer_cov_8bit_counters_init";
78 static const char *const SanCovPCsInitName = "__sanitizer_cov_pcs_init";
80 static const char *const SanCovGuardsSectionName = "sancov_guards";
81 static const char *const SanCovCountersSectionName = "sancov_cntrs";
82 static const char *const SanCovPCsSectionName = "sancov_pcs";
84 static const char *const SanCovLowestStackName = "__sancov_lowest_stack";
86 static cl::opt<int> ClCoverageLevel(
87 "sanitizer-coverage-level",
88 cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
89 "3: all blocks and critical edges"),
90 cl::Hidden, cl::init(0));
92 static cl::opt<bool> ClTracePC("sanitizer-coverage-trace-pc",
93 cl::desc("Experimental pc tracing"), cl::Hidden,
96 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard",
97 cl::desc("pc tracing with a guard"),
98 cl::Hidden, cl::init(false));
100 // If true, we create a global variable that contains PCs of all instrumented
101 // BBs, put this global into a named section, and pass this section's bounds
102 // to __sanitizer_cov_pcs_init.
103 // This way the coverage instrumentation does not need to acquire the PCs
104 // at run-time. Works with trace-pc-guard and inline-8bit-counters.
105 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table",
106 cl::desc("create a static PC table"),
107 cl::Hidden, cl::init(false));
110 ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters",
111 cl::desc("increments 8-bit counter for every edge"),
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 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth",
133 cl::desc("max stack depth tracing"),
134 cl::Hidden, cl::init(false));
138 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
139 SanitizerCoverageOptions Res;
140 switch (LegacyCoverageLevel) {
142 Res.CoverageType = SanitizerCoverageOptions::SCK_None;
145 Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
148 Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
151 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
154 Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
155 Res.IndirectCalls = true;
161 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
162 // Sets CoverageType and IndirectCalls.
163 SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
164 Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
165 Options.IndirectCalls |= CLOpts.IndirectCalls;
166 Options.TraceCmp |= ClCMPTracing;
167 Options.TraceDiv |= ClDIVTracing;
168 Options.TraceGep |= ClGEPTracing;
169 Options.TracePC |= ClTracePC;
170 Options.TracePCGuard |= ClTracePCGuard;
171 Options.Inline8bitCounters |= ClInline8bitCounters;
172 Options.PCTable |= ClCreatePCTable;
173 Options.NoPrune |= !ClPruneBlocks;
174 Options.StackDepth |= ClStackDepth;
175 if (!Options.TracePCGuard && !Options.TracePC &&
176 !Options.Inline8bitCounters && !Options.StackDepth)
177 Options.TracePCGuard = true; // TracePCGuard is default.
181 using DomTreeCallback = function_ref<const DominatorTree *(Function &F)>;
182 using PostDomTreeCallback =
183 function_ref<const PostDominatorTree *(Function &F)>;
185 class ModuleSanitizerCoverage {
187 ModuleSanitizerCoverage(
188 const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
189 : Options(OverrideFromCL(Options)) {}
190 bool instrumentModule(Module &M, DomTreeCallback DTCallback,
191 PostDomTreeCallback PDTCallback);
194 void instrumentFunction(Function &F, DomTreeCallback DTCallback,
195 PostDomTreeCallback PDTCallback);
196 void InjectCoverageForIndirectCalls(Function &F,
197 ArrayRef<Instruction *> IndirCalls);
198 void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
199 void InjectTraceForDiv(Function &F,
200 ArrayRef<BinaryOperator *> DivTraceTargets);
201 void InjectTraceForGep(Function &F,
202 ArrayRef<GetElementPtrInst *> GepTraceTargets);
203 void InjectTraceForSwitch(Function &F,
204 ArrayRef<Instruction *> SwitchTraceTargets);
205 bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
206 bool IsLeafFunc = true);
207 GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
208 Function &F, Type *Ty,
209 const char *Section);
210 GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
211 void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
212 void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
213 bool IsLeafFunc = true);
214 Function *CreateInitCallsForSections(Module &M, const char *CtorName,
215 const char *InitFunctionName, Type *Ty,
216 const char *Section);
217 std::pair<Value *, Value *> CreateSecStartEnd(Module &M, const char *Section,
220 void SetNoSanitizeMetadata(Instruction *I) {
221 I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
222 MDNode::get(*C, None));
225 std::string getSectionName(const std::string &Section) const;
226 std::string getSectionStart(const std::string &Section) const;
227 std::string getSectionEnd(const std::string &Section) const;
228 FunctionCallee SanCovTracePCIndir;
229 FunctionCallee SanCovTracePC, SanCovTracePCGuard;
230 FunctionCallee SanCovTraceCmpFunction[4];
231 FunctionCallee SanCovTraceConstCmpFunction[4];
232 FunctionCallee SanCovTraceDivFunction[2];
233 FunctionCallee SanCovTraceGepFunction;
234 FunctionCallee SanCovTraceSwitchFunction;
235 GlobalVariable *SanCovLowestStack;
237 Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy,
238 *Int16Ty, *Int8Ty, *Int8PtrTy;
240 std::string CurModuleUniqueId;
243 const DataLayout *DL;
245 GlobalVariable *FunctionGuardArray; // for trace-pc-guard.
246 GlobalVariable *Function8bitCounterArray; // for inline-8bit-counters.
247 GlobalVariable *FunctionPCsArray; // for pc-table.
248 SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
249 SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
251 SanitizerCoverageOptions Options;
254 class ModuleSanitizerCoverageLegacyPass : public ModulePass {
256 ModuleSanitizerCoverageLegacyPass(
257 const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
258 : ModulePass(ID), Options(Options) {
259 initializeModuleSanitizerCoverageLegacyPassPass(
260 *PassRegistry::getPassRegistry());
262 bool runOnModule(Module &M) override {
263 ModuleSanitizerCoverage ModuleSancov(Options);
264 auto DTCallback = [this](Function &F) -> const DominatorTree * {
265 return &this->getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
267 auto PDTCallback = [this](Function &F) -> const PostDominatorTree * {
268 return &this->getAnalysis<PostDominatorTreeWrapperPass>(F)
271 return ModuleSancov.instrumentModule(M, DTCallback, PDTCallback);
274 static char ID; // Pass identification, replacement for typeid
275 StringRef getPassName() const override { return "ModuleSanitizerCoverage"; }
277 void getAnalysisUsage(AnalysisUsage &AU) const override {
278 AU.addRequired<DominatorTreeWrapperPass>();
279 AU.addRequired<PostDominatorTreeWrapperPass>();
283 SanitizerCoverageOptions Options;
288 PreservedAnalyses ModuleSanitizerCoveragePass::run(Module &M,
289 ModuleAnalysisManager &MAM) {
290 ModuleSanitizerCoverage ModuleSancov(Options);
291 auto &FAM = MAM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
292 auto DTCallback = [&FAM](Function &F) -> const DominatorTree * {
293 return &FAM.getResult<DominatorTreeAnalysis>(F);
295 auto PDTCallback = [&FAM](Function &F) -> const PostDominatorTree * {
296 return &FAM.getResult<PostDominatorTreeAnalysis>(F);
298 if (ModuleSancov.instrumentModule(M, DTCallback, PDTCallback))
299 return PreservedAnalyses::none();
300 return PreservedAnalyses::all();
303 std::pair<Value *, Value *>
304 ModuleSanitizerCoverage::CreateSecStartEnd(Module &M, const char *Section,
306 GlobalVariable *SecStart =
307 new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr,
308 getSectionStart(Section));
309 SecStart->setVisibility(GlobalValue::HiddenVisibility);
310 GlobalVariable *SecEnd =
311 new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage,
312 nullptr, getSectionEnd(Section));
313 SecEnd->setVisibility(GlobalValue::HiddenVisibility);
314 IRBuilder<> IRB(M.getContext());
315 Value *SecEndPtr = IRB.CreatePointerCast(SecEnd, Ty);
316 if (!TargetTriple.isOSBinFormatCOFF())
317 return std::make_pair(IRB.CreatePointerCast(SecStart, Ty), SecEndPtr);
319 // Account for the fact that on windows-msvc __start_* symbols actually
320 // point to a uint64_t before the start of the array.
321 auto SecStartI8Ptr = IRB.CreatePointerCast(SecStart, Int8PtrTy);
322 auto GEP = IRB.CreateGEP(Int8Ty, SecStartI8Ptr,
323 ConstantInt::get(IntptrTy, sizeof(uint64_t)));
324 return std::make_pair(IRB.CreatePointerCast(GEP, Ty), SecEndPtr);
327 Function *ModuleSanitizerCoverage::CreateInitCallsForSections(
328 Module &M, const char *CtorName, const char *InitFunctionName, Type *Ty,
329 const char *Section) {
330 auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
331 auto SecStart = SecStartEnd.first;
332 auto SecEnd = SecStartEnd.second;
334 std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
335 M, CtorName, InitFunctionName, {Ty, Ty}, {SecStart, SecEnd});
336 assert(CtorFunc->getName() == CtorName);
338 if (TargetTriple.supportsCOMDAT()) {
339 // Use comdat to dedup CtorFunc.
340 CtorFunc->setComdat(M.getOrInsertComdat(CtorName));
341 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
343 appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
346 if (TargetTriple.isOSBinFormatCOFF()) {
347 // In COFF files, if the contructors are set as COMDAT (they are because
348 // COFF supports COMDAT) and the linker flag /OPT:REF (strip unreferenced
349 // functions and data) is used, the constructors get stripped. To prevent
350 // this, give the constructors weak ODR linkage and ensure the linker knows
351 // to include the sancov constructor. This way the linker can deduplicate
352 // the constructors but always leave one copy.
353 CtorFunc->setLinkage(GlobalValue::WeakODRLinkage);
354 appendToUsed(M, CtorFunc);
359 bool ModuleSanitizerCoverage::instrumentModule(
360 Module &M, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
361 if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
363 C = &(M.getContext());
364 DL = &M.getDataLayout();
366 CurModuleUniqueId = getUniqueModuleId(CurModule);
367 TargetTriple = Triple(M.getTargetTriple());
368 FunctionGuardArray = nullptr;
369 Function8bitCounterArray = nullptr;
370 FunctionPCsArray = nullptr;
371 IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
372 IntptrPtrTy = PointerType::getUnqual(IntptrTy);
373 Type *VoidTy = Type::getVoidTy(*C);
375 Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
376 Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
377 Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
378 Int64Ty = IRB.getInt64Ty();
379 Int32Ty = IRB.getInt32Ty();
380 Int16Ty = IRB.getInt16Ty();
381 Int8Ty = IRB.getInt8Ty();
384 M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy);
385 // Make sure smaller parameters are zero-extended to i64 as required by the
387 AttributeList SanCovTraceCmpZeroExtAL;
388 if (TargetTriple.getArch() == Triple::x86_64) {
389 SanCovTraceCmpZeroExtAL =
390 SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 0, Attribute::ZExt);
391 SanCovTraceCmpZeroExtAL =
392 SanCovTraceCmpZeroExtAL.addParamAttribute(*C, 1, Attribute::ZExt);
395 SanCovTraceCmpFunction[0] =
396 M.getOrInsertFunction(SanCovTraceCmp1, SanCovTraceCmpZeroExtAL, VoidTy,
397 IRB.getInt8Ty(), IRB.getInt8Ty());
398 SanCovTraceCmpFunction[1] =
399 M.getOrInsertFunction(SanCovTraceCmp2, SanCovTraceCmpZeroExtAL, VoidTy,
400 IRB.getInt16Ty(), IRB.getInt16Ty());
401 SanCovTraceCmpFunction[2] =
402 M.getOrInsertFunction(SanCovTraceCmp4, SanCovTraceCmpZeroExtAL, VoidTy,
403 IRB.getInt32Ty(), IRB.getInt32Ty());
404 SanCovTraceCmpFunction[3] =
405 M.getOrInsertFunction(SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty);
407 SanCovTraceConstCmpFunction[0] = M.getOrInsertFunction(
408 SanCovTraceConstCmp1, SanCovTraceCmpZeroExtAL, VoidTy, Int8Ty, Int8Ty);
409 SanCovTraceConstCmpFunction[1] = M.getOrInsertFunction(
410 SanCovTraceConstCmp2, SanCovTraceCmpZeroExtAL, VoidTy, Int16Ty, Int16Ty);
411 SanCovTraceConstCmpFunction[2] = M.getOrInsertFunction(
412 SanCovTraceConstCmp4, SanCovTraceCmpZeroExtAL, VoidTy, Int32Ty, Int32Ty);
413 SanCovTraceConstCmpFunction[3] =
414 M.getOrInsertFunction(SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty);
418 if (TargetTriple.getArch() == Triple::x86_64)
419 AL = AL.addParamAttribute(*C, 0, Attribute::ZExt);
420 SanCovTraceDivFunction[0] =
421 M.getOrInsertFunction(SanCovTraceDiv4, AL, VoidTy, IRB.getInt32Ty());
423 SanCovTraceDivFunction[1] =
424 M.getOrInsertFunction(SanCovTraceDiv8, VoidTy, Int64Ty);
425 SanCovTraceGepFunction =
426 M.getOrInsertFunction(SanCovTraceGep, VoidTy, IntptrTy);
427 SanCovTraceSwitchFunction =
428 M.getOrInsertFunction(SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy);
430 Constant *SanCovLowestStackConstant =
431 M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
432 SanCovLowestStack = dyn_cast<GlobalVariable>(SanCovLowestStackConstant);
433 if (!SanCovLowestStack) {
434 C->emitError(StringRef("'") + SanCovLowestStackName +
435 "' should not be declared by the user");
438 SanCovLowestStack->setThreadLocalMode(
439 GlobalValue::ThreadLocalMode::InitialExecTLSModel);
440 if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
441 SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
443 // We insert an empty inline asm after cov callbacks to avoid callback merge.
444 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
445 StringRef(""), StringRef(""),
446 /*hasSideEffects=*/true);
448 SanCovTracePC = M.getOrInsertFunction(SanCovTracePCName, VoidTy);
450 M.getOrInsertFunction(SanCovTracePCGuardName, VoidTy, Int32PtrTy);
453 instrumentFunction(F, DTCallback, PDTCallback);
455 Function *Ctor = nullptr;
457 if (FunctionGuardArray)
458 Ctor = CreateInitCallsForSections(M, SanCovModuleCtorTracePcGuardName,
459 SanCovTracePCGuardInitName, Int32PtrTy,
460 SanCovGuardsSectionName);
461 if (Function8bitCounterArray)
462 Ctor = CreateInitCallsForSections(M, SanCovModuleCtor8bitCountersName,
463 SanCov8bitCountersInitName, Int8PtrTy,
464 SanCovCountersSectionName);
465 if (Ctor && Options.PCTable) {
466 auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy);
467 FunctionCallee InitFunction = declareSanitizerInitFunction(
468 M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy});
469 IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
470 IRBCtor.CreateCall(InitFunction, {SecStartEnd.first, SecStartEnd.second});
472 // We don't reference these arrays directly in any of our runtime functions,
473 // so we need to prevent them from being dead stripped.
474 if (TargetTriple.isOSBinFormatMachO())
475 appendToUsed(M, GlobalsToAppendToUsed);
476 appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
480 // True if block has successors and it dominates all of them.
481 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
482 if (succ_begin(BB) == succ_end(BB))
485 for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
486 if (!DT->dominates(BB, SUCC))
493 // True if block has predecessors and it postdominates all of them.
494 static bool isFullPostDominator(const BasicBlock *BB,
495 const PostDominatorTree *PDT) {
496 if (pred_begin(BB) == pred_end(BB))
499 for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
500 if (!PDT->dominates(BB, PRED))
507 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
508 const DominatorTree *DT,
509 const PostDominatorTree *PDT,
510 const SanitizerCoverageOptions &Options) {
511 // Don't insert coverage for blocks containing nothing but unreachable: we
512 // will never call __sanitizer_cov() for them, so counting them in
513 // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
514 // percentage. Also, unreachable instructions frequently have no debug
516 if (isa<UnreachableInst>(BB->getFirstNonPHIOrDbgOrLifetime()))
519 // Don't insert coverage into blocks without a valid insertion point
520 // (catchswitch blocks).
521 if (BB->getFirstInsertionPt() == BB->end())
524 if (Options.NoPrune || &F.getEntryBlock() == BB)
527 if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
528 &F.getEntryBlock() != BB)
531 // Do not instrument full dominators, or full post-dominators with multiple
533 return !isFullDominator(BB, DT)
534 && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
538 // Returns true iff From->To is a backedge.
539 // A twist here is that we treat From->To as a backedge if
540 // * To dominates From or
541 // * To->UniqueSuccessor dominates From
542 static bool IsBackEdge(BasicBlock *From, BasicBlock *To,
543 const DominatorTree *DT) {
544 if (DT->dominates(To, From))
546 if (auto Next = To->getUniqueSuccessor())
547 if (DT->dominates(Next, From))
552 // Prunes uninteresting Cmp instrumentation:
553 // * CMP instructions that feed into loop backedge branch.
555 // Note that Cmp pruning is controlled by the same flag as the
557 static bool IsInterestingCmp(ICmpInst *CMP, const DominatorTree *DT,
558 const SanitizerCoverageOptions &Options) {
559 if (!Options.NoPrune)
560 if (CMP->hasOneUse())
561 if (auto BR = dyn_cast<BranchInst>(CMP->user_back()))
562 for (BasicBlock *B : BR->successors())
563 if (IsBackEdge(BR->getParent(), B, DT))
568 void ModuleSanitizerCoverage::instrumentFunction(
569 Function &F, DomTreeCallback DTCallback, PostDomTreeCallback PDTCallback) {
572 if (F.getName().find(".module_ctor") != std::string::npos)
573 return; // Should not instrument sanitizer init functions.
574 if (F.getName().startswith("__sanitizer_"))
575 return; // Don't instrument __sanitizer_* callbacks.
576 // Don't touch available_externally functions, their actual body is elewhere.
577 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
579 // Don't instrument MSVC CRT configuration helpers. They may run before normal
581 if (F.getName() == "__local_stdio_printf_options" ||
582 F.getName() == "__local_stdio_scanf_options")
584 if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
586 // Don't instrument functions using SEH for now. Splitting basic blocks like
587 // we do for coverage breaks WinEHPrepare.
588 // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
589 if (F.hasPersonalityFn() &&
590 isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
592 if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
593 SplitAllCriticalEdges(F, CriticalEdgeSplittingOptions().setIgnoreUnreachableDests());
594 SmallVector<Instruction *, 8> IndirCalls;
595 SmallVector<BasicBlock *, 16> BlocksToInstrument;
596 SmallVector<Instruction *, 8> CmpTraceTargets;
597 SmallVector<Instruction *, 8> SwitchTraceTargets;
598 SmallVector<BinaryOperator *, 8> DivTraceTargets;
599 SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
601 const DominatorTree *DT = DTCallback(F);
602 const PostDominatorTree *PDT = PDTCallback(F);
603 bool IsLeafFunc = true;
606 if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
607 BlocksToInstrument.push_back(&BB);
608 for (auto &Inst : BB) {
609 if (Options.IndirectCalls) {
611 if (CS && !CS.getCalledFunction())
612 IndirCalls.push_back(&Inst);
614 if (Options.TraceCmp) {
615 if (ICmpInst *CMP = dyn_cast<ICmpInst>(&Inst))
616 if (IsInterestingCmp(CMP, DT, Options))
617 CmpTraceTargets.push_back(&Inst);
618 if (isa<SwitchInst>(&Inst))
619 SwitchTraceTargets.push_back(&Inst);
621 if (Options.TraceDiv)
622 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
623 if (BO->getOpcode() == Instruction::SDiv ||
624 BO->getOpcode() == Instruction::UDiv)
625 DivTraceTargets.push_back(BO);
626 if (Options.TraceGep)
627 if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
628 GepTraceTargets.push_back(GEP);
629 if (Options.StackDepth)
630 if (isa<InvokeInst>(Inst) ||
631 (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
636 InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
637 InjectCoverageForIndirectCalls(F, IndirCalls);
638 InjectTraceForCmp(F, CmpTraceTargets);
639 InjectTraceForSwitch(F, SwitchTraceTargets);
640 InjectTraceForDiv(F, DivTraceTargets);
641 InjectTraceForGep(F, GepTraceTargets);
644 GlobalVariable *ModuleSanitizerCoverage::CreateFunctionLocalArrayInSection(
645 size_t NumElements, Function &F, Type *Ty, const char *Section) {
646 ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
647 auto Array = new GlobalVariable(
648 *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
649 Constant::getNullValue(ArrayTy), "__sancov_gen_");
651 if (TargetTriple.supportsCOMDAT() && !F.isInterposable())
653 GetOrCreateFunctionComdat(F, TargetTriple, CurModuleUniqueId))
654 Array->setComdat(Comdat);
655 Array->setSection(getSectionName(Section));
656 Array->setAlignment(Align(Ty->isPointerTy()
657 ? DL->getPointerSize()
658 : Ty->getPrimitiveSizeInBits() / 8));
659 GlobalsToAppendToUsed.push_back(Array);
660 GlobalsToAppendToCompilerUsed.push_back(Array);
661 MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
662 Array->addMetadata(LLVMContext::MD_associated, *MD);
668 ModuleSanitizerCoverage::CreatePCArray(Function &F,
669 ArrayRef<BasicBlock *> AllBlocks) {
670 size_t N = AllBlocks.size();
672 SmallVector<Constant *, 32> PCs;
673 IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
674 for (size_t i = 0; i < N; i++) {
675 if (&F.getEntryBlock() == AllBlocks[i]) {
676 PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
677 PCs.push_back((Constant *)IRB.CreateIntToPtr(
678 ConstantInt::get(IntptrTy, 1), IntptrPtrTy));
680 PCs.push_back((Constant *)IRB.CreatePointerCast(
681 BlockAddress::get(AllBlocks[i]), IntptrPtrTy));
682 PCs.push_back((Constant *)IRB.CreateIntToPtr(
683 ConstantInt::get(IntptrTy, 0), IntptrPtrTy));
686 auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy,
687 SanCovPCsSectionName);
688 PCArray->setInitializer(
689 ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs));
690 PCArray->setConstant(true);
695 void ModuleSanitizerCoverage::CreateFunctionLocalArrays(
696 Function &F, ArrayRef<BasicBlock *> AllBlocks) {
697 if (Options.TracePCGuard)
698 FunctionGuardArray = CreateFunctionLocalArrayInSection(
699 AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
701 if (Options.Inline8bitCounters)
702 Function8bitCounterArray = CreateFunctionLocalArrayInSection(
703 AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
706 FunctionPCsArray = CreatePCArray(F, AllBlocks);
709 bool ModuleSanitizerCoverage::InjectCoverage(Function &F,
710 ArrayRef<BasicBlock *> AllBlocks,
712 if (AllBlocks.empty()) return false;
713 CreateFunctionLocalArrays(F, AllBlocks);
714 for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
715 InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
719 // On every indirect call we call a run-time function
720 // __sanitizer_cov_indir_call* with two parameters:
722 // - global cache array that contains CacheSize pointers (zero-initialized).
723 // The cache is used to speed up recording the caller-callee pairs.
724 // The address of the caller is passed implicitly via caller PC.
725 // CacheSize is encoded in the name of the run-time function.
726 void ModuleSanitizerCoverage::InjectCoverageForIndirectCalls(
727 Function &F, ArrayRef<Instruction *> IndirCalls) {
728 if (IndirCalls.empty())
730 assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters);
731 for (auto I : IndirCalls) {
734 Value *Callee = CS.getCalledValue();
735 if (isa<InlineAsm>(Callee))
737 IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
741 // For every switch statement we insert a call:
742 // __sanitizer_cov_trace_switch(CondValue,
743 // {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
745 void ModuleSanitizerCoverage::InjectTraceForSwitch(
746 Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
747 for (auto I : SwitchTraceTargets) {
748 if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
750 SmallVector<Constant *, 16> Initializers;
751 Value *Cond = SI->getCondition();
752 if (Cond->getType()->getScalarSizeInBits() >
753 Int64Ty->getScalarSizeInBits())
755 Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
756 Initializers.push_back(
757 ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
758 if (Cond->getType()->getScalarSizeInBits() <
759 Int64Ty->getScalarSizeInBits())
760 Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
761 for (auto It : SI->cases()) {
762 Constant *C = It.getCaseValue();
763 if (C->getType()->getScalarSizeInBits() <
764 Int64Ty->getScalarSizeInBits())
765 C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
766 Initializers.push_back(C);
768 llvm::sort(Initializers.begin() + 2, Initializers.end(),
769 [](const Constant *A, const Constant *B) {
770 return cast<ConstantInt>(A)->getLimitedValue() <
771 cast<ConstantInt>(B)->getLimitedValue();
773 ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
774 GlobalVariable *GV = new GlobalVariable(
775 *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
776 ConstantArray::get(ArrayOfInt64Ty, Initializers),
777 "__sancov_gen_cov_switch_values");
778 IRB.CreateCall(SanCovTraceSwitchFunction,
779 {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
784 void ModuleSanitizerCoverage::InjectTraceForDiv(
785 Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
786 for (auto BO : DivTraceTargets) {
788 Value *A1 = BO->getOperand(1);
789 if (isa<ConstantInt>(A1)) continue;
790 if (!A1->getType()->isIntegerTy())
792 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
793 int CallbackIdx = TypeSize == 32 ? 0 :
794 TypeSize == 64 ? 1 : -1;
795 if (CallbackIdx < 0) continue;
796 auto Ty = Type::getIntNTy(*C, TypeSize);
797 IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
798 {IRB.CreateIntCast(A1, Ty, true)});
802 void ModuleSanitizerCoverage::InjectTraceForGep(
803 Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
804 for (auto GEP : GepTraceTargets) {
805 IRBuilder<> IRB(GEP);
806 for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
807 if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy())
808 IRB.CreateCall(SanCovTraceGepFunction,
809 {IRB.CreateIntCast(*I, IntptrTy, true)});
813 void ModuleSanitizerCoverage::InjectTraceForCmp(
814 Function &, ArrayRef<Instruction *> CmpTraceTargets) {
815 for (auto I : CmpTraceTargets) {
816 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
817 IRBuilder<> IRB(ICMP);
818 Value *A0 = ICMP->getOperand(0);
819 Value *A1 = ICMP->getOperand(1);
820 if (!A0->getType()->isIntegerTy())
822 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
823 int CallbackIdx = TypeSize == 8 ? 0 :
826 TypeSize == 64 ? 3 : -1;
827 if (CallbackIdx < 0) continue;
828 // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
829 auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
830 bool FirstIsConst = isa<ConstantInt>(A0);
831 bool SecondIsConst = isa<ConstantInt>(A1);
832 // If both are const, then we don't need such a comparison.
833 if (FirstIsConst && SecondIsConst) continue;
834 // If only one is const, then make it the first callback argument.
835 if (FirstIsConst || SecondIsConst) {
836 CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
841 auto Ty = Type::getIntNTy(*C, TypeSize);
842 IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
843 IRB.CreateIntCast(A1, Ty, true)});
848 void ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
851 BasicBlock::iterator IP = BB.getFirstInsertionPt();
852 bool IsEntryBB = &BB == &F.getEntryBlock();
855 if (auto SP = F.getSubprogram())
856 EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
857 // Keep static allocas and llvm.localescape calls in the entry block. Even
858 // if we aren't splitting the block, it's nice for allocas to be before
860 IP = PrepareToSplitEntryBlock(BB, IP);
862 EntryLoc = IP->getDebugLoc();
865 IRBuilder<> IRB(&*IP);
866 IRB.SetCurrentDebugLocation(EntryLoc);
867 if (Options.TracePC) {
868 IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
869 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
871 if (Options.TracePCGuard) {
872 auto GuardPtr = IRB.CreateIntToPtr(
873 IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
874 ConstantInt::get(IntptrTy, Idx * 4)),
876 IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
877 IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
879 if (Options.Inline8bitCounters) {
880 auto CounterPtr = IRB.CreateGEP(
881 Function8bitCounterArray->getValueType(), Function8bitCounterArray,
882 {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
883 auto Load = IRB.CreateLoad(Int8Ty, CounterPtr);
884 auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
885 auto Store = IRB.CreateStore(Inc, CounterPtr);
886 SetNoSanitizeMetadata(Load);
887 SetNoSanitizeMetadata(Store);
889 if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
890 // Check stack depth. If it's the deepest so far, record it.
891 Module *M = F.getParent();
892 Function *GetFrameAddr = Intrinsic::getDeclaration(
893 M, Intrinsic::frameaddress,
894 IRB.getInt8PtrTy(M->getDataLayout().getAllocaAddrSpace()));
896 IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
897 auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
898 auto LowestStack = IRB.CreateLoad(IntptrTy, SanCovLowestStack);
899 auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
900 auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false);
901 IRBuilder<> ThenIRB(ThenTerm);
902 auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
903 SetNoSanitizeMetadata(LowestStack);
904 SetNoSanitizeMetadata(Store);
909 ModuleSanitizerCoverage::getSectionName(const std::string &Section) const {
910 if (TargetTriple.isOSBinFormatCOFF()) {
911 if (Section == SanCovCountersSectionName)
913 if (Section == SanCovPCsSectionName)
915 return ".SCOV$GM"; // For SanCovGuardsSectionName.
917 if (TargetTriple.isOSBinFormatMachO())
918 return "__DATA,__" + Section;
919 return "__" + Section;
923 ModuleSanitizerCoverage::getSectionStart(const std::string &Section) const {
924 if (TargetTriple.isOSBinFormatMachO())
925 return "\1section$start$__DATA$__" + Section;
926 return "__start___" + Section;
930 ModuleSanitizerCoverage::getSectionEnd(const std::string &Section) const {
931 if (TargetTriple.isOSBinFormatMachO())
932 return "\1section$end$__DATA$__" + Section;
933 return "__stop___" + Section;
936 char ModuleSanitizerCoverageLegacyPass::ID = 0;
937 INITIALIZE_PASS_BEGIN(ModuleSanitizerCoverageLegacyPass, "sancov",
938 "Pass for instrumenting coverage on functions", false,
940 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
941 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
942 INITIALIZE_PASS_END(ModuleSanitizerCoverageLegacyPass, "sancov",
943 "Pass for instrumenting coverage on functions", false,
945 ModulePass *llvm::createModuleSanitizerCoverageLegacyPassPass(
946 const SanitizerCoverageOptions &Options) {
947 return new ModuleSanitizerCoverageLegacyPass(Options);