xref: /llvm-project/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp (revision cf311cfc20a363ba1ee1a8115ab307d6745a6b73) 
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 done on LLVM IR level, works with Sanitizers.
11 //
12 //===----------------------------------------------------------------------===//
13 
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/Module.h"
33 #include "llvm/IR/Type.h"
34 #include "llvm/Support/CommandLine.h"
35 #include "llvm/Support/Debug.h"
36 #include "llvm/Support/raw_ostream.h"
37 #include "llvm/Transforms/Instrumentation.h"
38 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
39 #include "llvm/Transforms/Utils/ModuleUtils.h"
40 
41 using namespace llvm;
42 
43 #define DEBUG_TYPE "sancov"
44 
45 static const char *const SanCovTracePCIndirName =
46     "__sanitizer_cov_trace_pc_indir";
47 static const char *const SanCovTracePCName = "__sanitizer_cov_trace_pc";
48 static const char *const SanCovTraceCmp1 = "__sanitizer_cov_trace_cmp1";
49 static const char *const SanCovTraceCmp2 = "__sanitizer_cov_trace_cmp2";
50 static const char *const SanCovTraceCmp4 = "__sanitizer_cov_trace_cmp4";
51 static const char *const SanCovTraceCmp8 = "__sanitizer_cov_trace_cmp8";
52 static const char *const SanCovTraceConstCmp1 =
53     "__sanitizer_cov_trace_const_cmp1";
54 static const char *const SanCovTraceConstCmp2 =
55     "__sanitizer_cov_trace_const_cmp2";
56 static const char *const SanCovTraceConstCmp4 =
57     "__sanitizer_cov_trace_const_cmp4";
58 static const char *const SanCovTraceConstCmp8 =
59     "__sanitizer_cov_trace_const_cmp8";
60 static const char *const SanCovTraceDiv4 = "__sanitizer_cov_trace_div4";
61 static const char *const SanCovTraceDiv8 = "__sanitizer_cov_trace_div8";
62 static const char *const SanCovTraceGep = "__sanitizer_cov_trace_gep";
63 static const char *const SanCovTraceSwitchName = "__sanitizer_cov_trace_switch";
64 static const char *const SanCovModuleCtorName = "sancov.module_ctor";
65 static const uint64_t SanCtorAndDtorPriority = 2;
66 
67 static const char *const SanCovTracePCGuardName =
68     "__sanitizer_cov_trace_pc_guard";
69 static const char *const SanCovTracePCGuardInitName =
70     "__sanitizer_cov_trace_pc_guard_init";
71 static const char *const SanCov8bitCountersInitName =
72     "__sanitizer_cov_8bit_counters_init";
73 static const char *const SanCovPCsInitName = "__sanitizer_cov_pcs_init";
74 
75 static const char *const SanCovGuardsSectionName = "sancov_guards";
76 static const char *const SanCovCountersSectionName = "sancov_cntrs";
77 static const char *const SanCovPCsSectionName = "sancov_pcs";
78 
79 static const char *const SanCovLowestStackName = "__sancov_lowest_stack";
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<bool> ClTracePC("sanitizer-coverage-trace-pc",
88                                cl::desc("Experimental pc tracing"), cl::Hidden,
89                                cl::init(false));
90 
91 static cl::opt<bool> ClTracePCGuard("sanitizer-coverage-trace-pc-guard",
92                                     cl::desc("pc tracing with a guard"),
93                                     cl::Hidden, cl::init(false));
94 
95 // If true, we create a global variable that contains PCs of all instrumented
96 // BBs, put this global into a named section, and pass this section's bounds
97 // to __sanitizer_cov_pcs_init.
98 // This way the coverage instrumentation does not need to acquire the PCs
99 // at run-time. Works with trace-pc-guard and inline-8bit-counters.
100 static cl::opt<bool> ClCreatePCTable("sanitizer-coverage-pc-table",
101                                      cl::desc("create a static PC table"),
102                                      cl::Hidden, cl::init(false));
103 
104 static cl::opt<bool>
105     ClInline8bitCounters("sanitizer-coverage-inline-8bit-counters",
106                          cl::desc("increments 8-bit counter for every edge"),
107                          cl::Hidden, cl::init(false));
108 
109 static cl::opt<bool>
110     ClCMPTracing("sanitizer-coverage-trace-compares",
111                  cl::desc("Tracing of CMP and similar instructions"),
112                  cl::Hidden, cl::init(false));
113 
114 static cl::opt<bool> ClDIVTracing("sanitizer-coverage-trace-divs",
115                                   cl::desc("Tracing of DIV instructions"),
116                                   cl::Hidden, cl::init(false));
117 
118 static cl::opt<bool> ClGEPTracing("sanitizer-coverage-trace-geps",
119                                   cl::desc("Tracing of GEP instructions"),
120                                   cl::Hidden, cl::init(false));
121 
122 static cl::opt<bool>
123     ClPruneBlocks("sanitizer-coverage-prune-blocks",
124                   cl::desc("Reduce the number of instrumented blocks"),
125                   cl::Hidden, cl::init(true));
126 
127 static cl::opt<bool> ClStackDepth("sanitizer-coverage-stack-depth",
128                                   cl::desc("max stack depth tracing"),
129                                   cl::Hidden, cl::init(false));
130 
131 namespace {
132 
133 SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
134   SanitizerCoverageOptions Res;
135   switch (LegacyCoverageLevel) {
136   case 0:
137     Res.CoverageType = SanitizerCoverageOptions::SCK_None;
138     break;
139   case 1:
140     Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
141     break;
142   case 2:
143     Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
144     break;
145   case 3:
146     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
147     break;
148   case 4:
149     Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
150     Res.IndirectCalls = true;
151     break;
152   }
153   return Res;
154 }
155 
156 SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
157   // Sets CoverageType and IndirectCalls.
158   SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
159   Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
160   Options.IndirectCalls |= CLOpts.IndirectCalls;
161   Options.TraceCmp |= ClCMPTracing;
162   Options.TraceDiv |= ClDIVTracing;
163   Options.TraceGep |= ClGEPTracing;
164   Options.TracePC |= ClTracePC;
165   Options.TracePCGuard |= ClTracePCGuard;
166   Options.Inline8bitCounters |= ClInline8bitCounters;
167   Options.PCTable |= ClCreatePCTable;
168   Options.NoPrune |= !ClPruneBlocks;
169   Options.StackDepth |= ClStackDepth;
170   if (!Options.TracePCGuard && !Options.TracePC &&
171       !Options.Inline8bitCounters && !Options.StackDepth)
172     Options.TracePCGuard = true; // TracePCGuard is default.
173   return Options;
174 }
175 
176 class SanitizerCoverageModule : public ModulePass {
177 public:
178   SanitizerCoverageModule(
179       const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
180       : ModulePass(ID), Options(OverrideFromCL(Options)) {
181     initializeSanitizerCoverageModulePass(*PassRegistry::getPassRegistry());
182   }
183   bool runOnModule(Module &M) override;
184   bool runOnFunction(Function &F);
185   static char ID; // Pass identification, replacement for typeid
186   StringRef getPassName() const override { return "SanitizerCoverageModule"; }
187 
188   void getAnalysisUsage(AnalysisUsage &AU) const override {
189     AU.addRequired<DominatorTreeWrapperPass>();
190     AU.addRequired<PostDominatorTreeWrapperPass>();
191   }
192 
193 private:
194   void InjectCoverageForIndirectCalls(Function &F,
195                                       ArrayRef<Instruction *> IndirCalls);
196   void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
197   void InjectTraceForDiv(Function &F,
198                          ArrayRef<BinaryOperator *> DivTraceTargets);
199   void InjectTraceForGep(Function &F,
200                          ArrayRef<GetElementPtrInst *> GepTraceTargets);
201   void InjectTraceForSwitch(Function &F,
202                             ArrayRef<Instruction *> SwitchTraceTargets);
203   bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks,
204                       bool IsLeafFunc = true);
205   GlobalVariable *CreateFunctionLocalArrayInSection(size_t NumElements,
206                                                     Function &F, Type *Ty,
207                                                     const char *Section);
208   GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
209   void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
210   void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
211                              bool IsLeafFunc = true);
212   Function *CreateInitCallsForSections(Module &M, const char *InitFunctionName,
213                                        Type *Ty, const char *Section);
214   std::pair<GlobalVariable *, GlobalVariable *>
215   CreateSecStartEnd(Module &M, const char *Section, Type *Ty);
216 
217   void SetNoSanitizeMetadata(Instruction *I) {
218     I->setMetadata(I->getModule()->getMDKindID("nosanitize"),
219                    MDNode::get(*C, None));
220   }
221 
222   std::string getSectionName(const std::string &Section) const;
223   std::string getSectionStart(const std::string &Section) const;
224   std::string getSectionEnd(const std::string &Section) const;
225   Function *SanCovTracePCIndir;
226   Function *SanCovTracePC, *SanCovTracePCGuard;
227   Function *SanCovTraceCmpFunction[4];
228   Function *SanCovTraceConstCmpFunction[4];
229   Function *SanCovTraceDivFunction[2];
230   Function *SanCovTraceGepFunction;
231   Function *SanCovTraceSwitchFunction;
232   GlobalVariable *SanCovLowestStack;
233   InlineAsm *EmptyAsm;
234   Type *IntptrTy, *IntptrPtrTy, *Int64Ty, *Int64PtrTy, *Int32Ty, *Int32PtrTy,
235       *Int16Ty, *Int8Ty, *Int8PtrTy;
236   Module *CurModule;
237   Triple TargetTriple;
238   LLVMContext *C;
239   const DataLayout *DL;
240 
241   GlobalVariable *FunctionGuardArray;  // for trace-pc-guard.
242   GlobalVariable *Function8bitCounterArray;  // for inline-8bit-counters.
243   GlobalVariable *FunctionPCsArray;  // for pc-table.
244   SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
245   SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
246 
247   SanitizerCoverageOptions Options;
248 };
249 
250 } // namespace
251 
252 std::pair<GlobalVariable *, GlobalVariable *>
253 SanitizerCoverageModule::CreateSecStartEnd(Module &M, const char *Section,
254                                            Type *Ty) {
255   GlobalVariable *SecStart =
256       new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage, nullptr,
257                          getSectionStart(Section));
258   SecStart->setVisibility(GlobalValue::HiddenVisibility);
259   GlobalVariable *SecEnd =
260       new GlobalVariable(M, Ty, false, GlobalVariable::ExternalLinkage,
261                          nullptr, getSectionEnd(Section));
262   SecEnd->setVisibility(GlobalValue::HiddenVisibility);
263 
264   return std::make_pair(SecStart, SecEnd);
265 }
266 
267 
268 Function *SanitizerCoverageModule::CreateInitCallsForSections(
269     Module &M, const char *InitFunctionName, Type *Ty,
270     const char *Section) {
271   IRBuilder<> IRB(M.getContext());
272   auto SecStartEnd = CreateSecStartEnd(M, Section, Ty);
273   auto SecStart = SecStartEnd.first;
274   auto SecEnd = SecStartEnd.second;
275   Function *CtorFunc;
276   std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
277       M, SanCovModuleCtorName, InitFunctionName, {Ty, Ty},
278       {IRB.CreatePointerCast(SecStart, Ty), IRB.CreatePointerCast(SecEnd, Ty)});
279 
280   if (TargetTriple.supportsCOMDAT()) {
281     // Use comdat to dedup CtorFunc.
282     CtorFunc->setComdat(M.getOrInsertComdat(SanCovModuleCtorName));
283     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority, CtorFunc);
284   } else {
285     appendToGlobalCtors(M, CtorFunc, SanCtorAndDtorPriority);
286   }
287   return CtorFunc;
288 }
289 
290 bool SanitizerCoverageModule::runOnModule(Module &M) {
291   if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
292     return false;
293   C = &(M.getContext());
294   DL = &M.getDataLayout();
295   CurModule = &M;
296   TargetTriple = Triple(M.getTargetTriple());
297   FunctionGuardArray = nullptr;
298   Function8bitCounterArray = nullptr;
299   FunctionPCsArray = nullptr;
300   IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
301   IntptrPtrTy = PointerType::getUnqual(IntptrTy);
302   Type *VoidTy = Type::getVoidTy(*C);
303   IRBuilder<> IRB(*C);
304   Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
305   Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
306   Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
307   Int64Ty = IRB.getInt64Ty();
308   Int32Ty = IRB.getInt32Ty();
309   Int16Ty = IRB.getInt16Ty();
310   Int8Ty = IRB.getInt8Ty();
311 
312   SanCovTracePCIndir = checkSanitizerInterfaceFunction(
313       M.getOrInsertFunction(SanCovTracePCIndirName, VoidTy, IntptrTy));
314   SanCovTraceCmpFunction[0] =
315       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
316           SanCovTraceCmp1, VoidTy, IRB.getInt8Ty(), IRB.getInt8Ty()));
317   SanCovTraceCmpFunction[1] = checkSanitizerInterfaceFunction(
318       M.getOrInsertFunction(SanCovTraceCmp2, VoidTy, IRB.getInt16Ty(),
319                             IRB.getInt16Ty()));
320   SanCovTraceCmpFunction[2] = checkSanitizerInterfaceFunction(
321       M.getOrInsertFunction(SanCovTraceCmp4, VoidTy, IRB.getInt32Ty(),
322                             IRB.getInt32Ty()));
323   SanCovTraceCmpFunction[3] =
324       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
325           SanCovTraceCmp8, VoidTy, Int64Ty, Int64Ty));
326 
327   SanCovTraceConstCmpFunction[0] =
328       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
329           SanCovTraceConstCmp1, VoidTy, Int8Ty, Int8Ty));
330   SanCovTraceConstCmpFunction[1] =
331       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
332           SanCovTraceConstCmp2, VoidTy, Int16Ty, Int16Ty));
333   SanCovTraceConstCmpFunction[2] =
334       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
335           SanCovTraceConstCmp4, VoidTy, Int32Ty, Int32Ty));
336   SanCovTraceConstCmpFunction[3] =
337       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
338           SanCovTraceConstCmp8, VoidTy, Int64Ty, Int64Ty));
339 
340   SanCovTraceDivFunction[0] =
341       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
342           SanCovTraceDiv4, VoidTy, IRB.getInt32Ty()));
343   SanCovTraceDivFunction[1] =
344       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
345           SanCovTraceDiv8, VoidTy, Int64Ty));
346   SanCovTraceGepFunction =
347       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
348           SanCovTraceGep, VoidTy, IntptrTy));
349   SanCovTraceSwitchFunction =
350       checkSanitizerInterfaceFunction(M.getOrInsertFunction(
351           SanCovTraceSwitchName, VoidTy, Int64Ty, Int64PtrTy));
352 
353   Constant *SanCovLowestStackConstant =
354       M.getOrInsertGlobal(SanCovLowestStackName, IntptrTy);
355   SanCovLowestStack = cast<GlobalVariable>(SanCovLowestStackConstant);
356   SanCovLowestStack->setThreadLocalMode(
357       GlobalValue::ThreadLocalMode::InitialExecTLSModel);
358   if (Options.StackDepth && !SanCovLowestStack->isDeclaration())
359     SanCovLowestStack->setInitializer(Constant::getAllOnesValue(IntptrTy));
360 
361   // Make sure smaller parameters are zero-extended to i64 as required by the
362   // x86_64 ABI.
363   if (TargetTriple.getArch() == Triple::x86_64) {
364     for (int i = 0; i < 3; i++) {
365       SanCovTraceCmpFunction[i]->addParamAttr(0, Attribute::ZExt);
366       SanCovTraceCmpFunction[i]->addParamAttr(1, Attribute::ZExt);
367       SanCovTraceConstCmpFunction[i]->addParamAttr(0, Attribute::ZExt);
368       SanCovTraceConstCmpFunction[i]->addParamAttr(1, Attribute::ZExt);
369     }
370     SanCovTraceDivFunction[0]->addParamAttr(0, Attribute::ZExt);
371   }
372 
373 
374   // We insert an empty inline asm after cov callbacks to avoid callback merge.
375   EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
376                             StringRef(""), StringRef(""),
377                             /*hasSideEffects=*/true);
378 
379   SanCovTracePC = checkSanitizerInterfaceFunction(
380       M.getOrInsertFunction(SanCovTracePCName, VoidTy));
381   SanCovTracePCGuard = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
382       SanCovTracePCGuardName, VoidTy, Int32PtrTy));
383 
384   for (auto &F : M)
385     runOnFunction(F);
386 
387   Function *Ctor = nullptr;
388 
389   if (FunctionGuardArray)
390     Ctor = CreateInitCallsForSections(M, SanCovTracePCGuardInitName, Int32PtrTy,
391                                       SanCovGuardsSectionName);
392   if (Function8bitCounterArray)
393     Ctor = CreateInitCallsForSections(M, SanCov8bitCountersInitName, Int8PtrTy,
394                                       SanCovCountersSectionName);
395   if (Ctor && Options.PCTable) {
396     auto SecStartEnd = CreateSecStartEnd(M, SanCovPCsSectionName, IntptrPtrTy);
397     Function *InitFunction = declareSanitizerInitFunction(
398         M, SanCovPCsInitName, {IntptrPtrTy, IntptrPtrTy});
399     IRBuilder<> IRBCtor(Ctor->getEntryBlock().getTerminator());
400     IRBCtor.CreateCall(InitFunction,
401                        {IRB.CreatePointerCast(SecStartEnd.first, IntptrPtrTy),
402                         IRB.CreatePointerCast(SecStartEnd.second, IntptrPtrTy)});
403   }
404   // We don't reference these arrays directly in any of our runtime functions,
405   // so we need to prevent them from being dead stripped.
406   if (TargetTriple.isOSBinFormatMachO())
407     appendToUsed(M, GlobalsToAppendToUsed);
408   appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
409   return true;
410 }
411 
412 // True if block has successors and it dominates all of them.
413 static bool isFullDominator(const BasicBlock *BB, const DominatorTree *DT) {
414   if (succ_begin(BB) == succ_end(BB))
415     return false;
416 
417   for (const BasicBlock *SUCC : make_range(succ_begin(BB), succ_end(BB))) {
418     if (!DT->dominates(BB, SUCC))
419       return false;
420   }
421 
422   return true;
423 }
424 
425 // True if block has predecessors and it postdominates all of them.
426 static bool isFullPostDominator(const BasicBlock *BB,
427                                 const PostDominatorTree *PDT) {
428   if (pred_begin(BB) == pred_end(BB))
429     return false;
430 
431   for (const BasicBlock *PRED : make_range(pred_begin(BB), pred_end(BB))) {
432     if (!PDT->dominates(BB, PRED))
433       return false;
434   }
435 
436   return true;
437 }
438 
439 static bool shouldInstrumentBlock(const Function &F, const BasicBlock *BB,
440                                   const DominatorTree *DT,
441                                   const PostDominatorTree *PDT,
442                                   const SanitizerCoverageOptions &Options) {
443   // Don't insert coverage for unreachable blocks: we will never call
444   // __sanitizer_cov() for them, so counting them in
445   // NumberOfInstrumentedBlocks() might complicate calculation of code coverage
446   // percentage. Also, unreachable instructions frequently have no debug
447   // locations.
448   if (isa<UnreachableInst>(BB->getTerminator()))
449     return false;
450 
451   // Don't insert coverage into blocks without a valid insertion point
452   // (catchswitch blocks).
453   if (BB->getFirstInsertionPt() == BB->end())
454     return false;
455 
456   if (Options.NoPrune || &F.getEntryBlock() == BB)
457     return true;
458 
459   if (Options.CoverageType == SanitizerCoverageOptions::SCK_Function &&
460       &F.getEntryBlock() != BB)
461     return false;
462 
463   // Do not instrument full dominators, or full post-dominators with multiple
464   // predecessors.
465   return !isFullDominator(BB, DT)
466     && !(isFullPostDominator(BB, PDT) && !BB->getSinglePredecessor());
467 }
468 
469 bool SanitizerCoverageModule::runOnFunction(Function &F) {
470   if (F.empty())
471     return false;
472   if (F.getName().find(".module_ctor") != std::string::npos)
473     return false; // Should not instrument sanitizer init functions.
474   if (F.getName().startswith("__sanitizer_"))
475     return false;  // Don't instrument __sanitizer_* callbacks.
476   // Don't touch available_externally functions, their actual body is elewhere.
477   if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
478     return false;
479   // Don't instrument MSVC CRT configuration helpers. They may run before normal
480   // initialization.
481   if (F.getName() == "__local_stdio_printf_options" ||
482       F.getName() == "__local_stdio_scanf_options")
483     return false;
484   if (isa<UnreachableInst>(F.getEntryBlock().getTerminator()))
485     return false;
486   // Don't instrument functions using SEH for now. Splitting basic blocks like
487   // we do for coverage breaks WinEHPrepare.
488   // FIXME: Remove this when SEH no longer uses landingpad pattern matching.
489   if (F.hasPersonalityFn() &&
490       isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
491     return false;
492   if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
493     SplitAllCriticalEdges(F);
494   SmallVector<Instruction *, 8> IndirCalls;
495   SmallVector<BasicBlock *, 16> BlocksToInstrument;
496   SmallVector<Instruction *, 8> CmpTraceTargets;
497   SmallVector<Instruction *, 8> SwitchTraceTargets;
498   SmallVector<BinaryOperator *, 8> DivTraceTargets;
499   SmallVector<GetElementPtrInst *, 8> GepTraceTargets;
500 
501   const DominatorTree *DT =
502       &getAnalysis<DominatorTreeWrapperPass>(F).getDomTree();
503   const PostDominatorTree *PDT =
504       &getAnalysis<PostDominatorTreeWrapperPass>(F).getPostDomTree();
505   bool IsLeafFunc = true;
506 
507   for (auto &BB : F) {
508     if (shouldInstrumentBlock(F, &BB, DT, PDT, Options))
509       BlocksToInstrument.push_back(&BB);
510     for (auto &Inst : BB) {
511       if (Options.IndirectCalls) {
512         CallSite CS(&Inst);
513         if (CS && !CS.getCalledFunction())
514           IndirCalls.push_back(&Inst);
515       }
516       if (Options.TraceCmp) {
517         if (isa<ICmpInst>(&Inst))
518           CmpTraceTargets.push_back(&Inst);
519         if (isa<SwitchInst>(&Inst))
520           SwitchTraceTargets.push_back(&Inst);
521       }
522       if (Options.TraceDiv)
523         if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&Inst))
524           if (BO->getOpcode() == Instruction::SDiv ||
525               BO->getOpcode() == Instruction::UDiv)
526             DivTraceTargets.push_back(BO);
527       if (Options.TraceGep)
528         if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&Inst))
529           GepTraceTargets.push_back(GEP);
530       if (Options.StackDepth)
531         if (isa<InvokeInst>(Inst) ||
532             (isa<CallInst>(Inst) && !isa<IntrinsicInst>(Inst)))
533           IsLeafFunc = false;
534     }
535   }
536 
537   InjectCoverage(F, BlocksToInstrument, IsLeafFunc);
538   InjectCoverageForIndirectCalls(F, IndirCalls);
539   InjectTraceForCmp(F, CmpTraceTargets);
540   InjectTraceForSwitch(F, SwitchTraceTargets);
541   InjectTraceForDiv(F, DivTraceTargets);
542   InjectTraceForGep(F, GepTraceTargets);
543   return true;
544 }
545 
546 GlobalVariable *SanitizerCoverageModule::CreateFunctionLocalArrayInSection(
547     size_t NumElements, Function &F, Type *Ty, const char *Section) {
548   ArrayType *ArrayTy = ArrayType::get(Ty, NumElements);
549   auto Array = new GlobalVariable(
550       *CurModule, ArrayTy, false, GlobalVariable::PrivateLinkage,
551       Constant::getNullValue(ArrayTy), "__sancov_gen_");
552   if (auto Comdat = F.getComdat())
553     Array->setComdat(Comdat);
554   Array->setSection(getSectionName(Section));
555   Array->setAlignment(Ty->isPointerTy() ? DL->getPointerSize()
556                                         : Ty->getPrimitiveSizeInBits() / 8);
557   return Array;
558 }
559 
560 GlobalVariable *
561 SanitizerCoverageModule::CreatePCArray(Function &F,
562                                        ArrayRef<BasicBlock *> AllBlocks) {
563   size_t N = AllBlocks.size();
564   assert(N);
565   SmallVector<Constant *, 32> PCs;
566   IRBuilder<> IRB(&*F.getEntryBlock().getFirstInsertionPt());
567   for (size_t i = 0; i < N; i++) {
568     if (&F.getEntryBlock() == AllBlocks[i]) {
569       PCs.push_back((Constant *)IRB.CreatePointerCast(&F, IntptrPtrTy));
570       PCs.push_back((Constant *)IRB.CreateIntToPtr(
571           ConstantInt::get(IntptrTy, 1), IntptrPtrTy));
572     } else {
573       PCs.push_back((Constant *)IRB.CreatePointerCast(
574           BlockAddress::get(AllBlocks[i]), IntptrPtrTy));
575       PCs.push_back((Constant *)IRB.CreateIntToPtr(
576           ConstantInt::get(IntptrTy, 0), IntptrPtrTy));
577     }
578   }
579   auto *PCArray = CreateFunctionLocalArrayInSection(N * 2, F, IntptrPtrTy,
580                                                     SanCovPCsSectionName);
581   PCArray->setInitializer(
582       ConstantArray::get(ArrayType::get(IntptrPtrTy, N * 2), PCs));
583   PCArray->setConstant(true);
584 
585   return PCArray;
586 }
587 
588 void SanitizerCoverageModule::CreateFunctionLocalArrays(
589     Function &F, ArrayRef<BasicBlock *> AllBlocks) {
590   if (Options.TracePCGuard) {
591     FunctionGuardArray = CreateFunctionLocalArrayInSection(
592         AllBlocks.size(), F, Int32Ty, SanCovGuardsSectionName);
593     GlobalsToAppendToUsed.push_back(FunctionGuardArray);
594     GlobalsToAppendToCompilerUsed.push_back(FunctionGuardArray);
595     MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
596     FunctionGuardArray->addMetadata(LLVMContext::MD_associated, *MD);
597   }
598   if (Options.Inline8bitCounters) {
599     Function8bitCounterArray = CreateFunctionLocalArrayInSection(
600         AllBlocks.size(), F, Int8Ty, SanCovCountersSectionName);
601     GlobalsToAppendToCompilerUsed.push_back(Function8bitCounterArray);
602     MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
603     Function8bitCounterArray->addMetadata(LLVMContext::MD_associated, *MD);
604   }
605   if (Options.PCTable) {
606     FunctionPCsArray = CreatePCArray(F, AllBlocks);
607     GlobalsToAppendToCompilerUsed.push_back(FunctionPCsArray);
608     MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
609     FunctionPCsArray->addMetadata(LLVMContext::MD_associated, *MD);
610   }
611 }
612 
613 bool SanitizerCoverageModule::InjectCoverage(Function &F,
614                                              ArrayRef<BasicBlock *> AllBlocks,
615                                              bool IsLeafFunc) {
616   if (AllBlocks.empty()) return false;
617   CreateFunctionLocalArrays(F, AllBlocks);
618   for (size_t i = 0, N = AllBlocks.size(); i < N; i++)
619     InjectCoverageAtBlock(F, *AllBlocks[i], i, IsLeafFunc);
620   return true;
621 }
622 
623 // On every indirect call we call a run-time function
624 // __sanitizer_cov_indir_call* with two parameters:
625 //   - callee address,
626 //   - global cache array that contains CacheSize pointers (zero-initialized).
627 //     The cache is used to speed up recording the caller-callee pairs.
628 // The address of the caller is passed implicitly via caller PC.
629 // CacheSize is encoded in the name of the run-time function.
630 void SanitizerCoverageModule::InjectCoverageForIndirectCalls(
631     Function &F, ArrayRef<Instruction *> IndirCalls) {
632   if (IndirCalls.empty())
633     return;
634   assert(Options.TracePC || Options.TracePCGuard || Options.Inline8bitCounters);
635   for (auto I : IndirCalls) {
636     IRBuilder<> IRB(I);
637     CallSite CS(I);
638     Value *Callee = CS.getCalledValue();
639     if (isa<InlineAsm>(Callee))
640       continue;
641     IRB.CreateCall(SanCovTracePCIndir, IRB.CreatePointerCast(Callee, IntptrTy));
642   }
643 }
644 
645 // For every switch statement we insert a call:
646 // __sanitizer_cov_trace_switch(CondValue,
647 //      {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
648 
649 void SanitizerCoverageModule::InjectTraceForSwitch(
650     Function &, ArrayRef<Instruction *> SwitchTraceTargets) {
651   for (auto I : SwitchTraceTargets) {
652     if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
653       IRBuilder<> IRB(I);
654       SmallVector<Constant *, 16> Initializers;
655       Value *Cond = SI->getCondition();
656       if (Cond->getType()->getScalarSizeInBits() >
657           Int64Ty->getScalarSizeInBits())
658         continue;
659       Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
660       Initializers.push_back(
661           ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
662       if (Cond->getType()->getScalarSizeInBits() <
663           Int64Ty->getScalarSizeInBits())
664         Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
665       for (auto It : SI->cases()) {
666         Constant *C = It.getCaseValue();
667         if (C->getType()->getScalarSizeInBits() <
668             Int64Ty->getScalarSizeInBits())
669           C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
670         Initializers.push_back(C);
671       }
672       llvm::sort(Initializers.begin() + 2, Initializers.end(),
673                  [](const Constant *A, const Constant *B) {
674                    return cast<ConstantInt>(A)->getLimitedValue() <
675                           cast<ConstantInt>(B)->getLimitedValue();
676                  });
677       ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
678       GlobalVariable *GV = new GlobalVariable(
679           *CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
680           ConstantArray::get(ArrayOfInt64Ty, Initializers),
681           "__sancov_gen_cov_switch_values");
682       IRB.CreateCall(SanCovTraceSwitchFunction,
683                      {Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
684     }
685   }
686 }
687 
688 void SanitizerCoverageModule::InjectTraceForDiv(
689     Function &, ArrayRef<BinaryOperator *> DivTraceTargets) {
690   for (auto BO : DivTraceTargets) {
691     IRBuilder<> IRB(BO);
692     Value *A1 = BO->getOperand(1);
693     if (isa<ConstantInt>(A1)) continue;
694     if (!A1->getType()->isIntegerTy())
695       continue;
696     uint64_t TypeSize = DL->getTypeStoreSizeInBits(A1->getType());
697     int CallbackIdx = TypeSize == 32 ? 0 :
698         TypeSize == 64 ? 1 : -1;
699     if (CallbackIdx < 0) continue;
700     auto Ty = Type::getIntNTy(*C, TypeSize);
701     IRB.CreateCall(SanCovTraceDivFunction[CallbackIdx],
702                    {IRB.CreateIntCast(A1, Ty, true)});
703   }
704 }
705 
706 void SanitizerCoverageModule::InjectTraceForGep(
707     Function &, ArrayRef<GetElementPtrInst *> GepTraceTargets) {
708   for (auto GEP : GepTraceTargets) {
709     IRBuilder<> IRB(GEP);
710     for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
711       if (!isa<ConstantInt>(*I) && (*I)->getType()->isIntegerTy())
712         IRB.CreateCall(SanCovTraceGepFunction,
713                        {IRB.CreateIntCast(*I, IntptrTy, true)});
714   }
715 }
716 
717 void SanitizerCoverageModule::InjectTraceForCmp(
718     Function &, ArrayRef<Instruction *> CmpTraceTargets) {
719   for (auto I : CmpTraceTargets) {
720     if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
721       IRBuilder<> IRB(ICMP);
722       Value *A0 = ICMP->getOperand(0);
723       Value *A1 = ICMP->getOperand(1);
724       if (!A0->getType()->isIntegerTy())
725         continue;
726       uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
727       int CallbackIdx = TypeSize == 8 ? 0 :
728                         TypeSize == 16 ? 1 :
729                         TypeSize == 32 ? 2 :
730                         TypeSize == 64 ? 3 : -1;
731       if (CallbackIdx < 0) continue;
732       // __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
733       auto CallbackFunc = SanCovTraceCmpFunction[CallbackIdx];
734       bool FirstIsConst = isa<ConstantInt>(A0);
735       bool SecondIsConst = isa<ConstantInt>(A1);
736       // If both are const, then we don't need such a comparison.
737       if (FirstIsConst && SecondIsConst) continue;
738       // If only one is const, then make it the first callback argument.
739       if (FirstIsConst || SecondIsConst) {
740         CallbackFunc = SanCovTraceConstCmpFunction[CallbackIdx];
741         if (SecondIsConst)
742           std::swap(A0, A1);
743       }
744 
745       auto Ty = Type::getIntNTy(*C, TypeSize);
746       IRB.CreateCall(CallbackFunc, {IRB.CreateIntCast(A0, Ty, true),
747               IRB.CreateIntCast(A1, Ty, true)});
748     }
749   }
750 }
751 
752 void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
753                                                     size_t Idx,
754                                                     bool IsLeafFunc) {
755   BasicBlock::iterator IP = BB.getFirstInsertionPt();
756   bool IsEntryBB = &BB == &F.getEntryBlock();
757   DebugLoc EntryLoc;
758   if (IsEntryBB) {
759     if (auto SP = F.getSubprogram())
760       EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
761     // Keep static allocas and llvm.localescape calls in the entry block.  Even
762     // if we aren't splitting the block, it's nice for allocas to be before
763     // calls.
764     IP = PrepareToSplitEntryBlock(BB, IP);
765   } else {
766     EntryLoc = IP->getDebugLoc();
767   }
768 
769   IRBuilder<> IRB(&*IP);
770   IRB.SetCurrentDebugLocation(EntryLoc);
771   if (Options.TracePC) {
772     IRB.CreateCall(SanCovTracePC); // gets the PC using GET_CALLER_PC.
773     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
774   }
775   if (Options.TracePCGuard) {
776     auto GuardPtr = IRB.CreateIntToPtr(
777         IRB.CreateAdd(IRB.CreatePointerCast(FunctionGuardArray, IntptrTy),
778                       ConstantInt::get(IntptrTy, Idx * 4)),
779         Int32PtrTy);
780     IRB.CreateCall(SanCovTracePCGuard, GuardPtr);
781     IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
782   }
783   if (Options.Inline8bitCounters) {
784     auto CounterPtr = IRB.CreateGEP(
785         Function8bitCounterArray,
786         {ConstantInt::get(IntptrTy, 0), ConstantInt::get(IntptrTy, Idx)});
787     auto Load = IRB.CreateLoad(CounterPtr);
788     auto Inc = IRB.CreateAdd(Load, ConstantInt::get(Int8Ty, 1));
789     auto Store = IRB.CreateStore(Inc, CounterPtr);
790     SetNoSanitizeMetadata(Load);
791     SetNoSanitizeMetadata(Store);
792   }
793   if (Options.StackDepth && IsEntryBB && !IsLeafFunc) {
794     // Check stack depth.  If it's the deepest so far, record it.
795     Function *GetFrameAddr =
796         Intrinsic::getDeclaration(F.getParent(), Intrinsic::frameaddress);
797     auto FrameAddrPtr =
798         IRB.CreateCall(GetFrameAddr, {Constant::getNullValue(Int32Ty)});
799     auto FrameAddrInt = IRB.CreatePtrToInt(FrameAddrPtr, IntptrTy);
800     auto LowestStack = IRB.CreateLoad(SanCovLowestStack);
801     auto IsStackLower = IRB.CreateICmpULT(FrameAddrInt, LowestStack);
802     auto ThenTerm = SplitBlockAndInsertIfThen(IsStackLower, &*IP, false);
803     IRBuilder<> ThenIRB(ThenTerm);
804     auto Store = ThenIRB.CreateStore(FrameAddrInt, SanCovLowestStack);
805     SetNoSanitizeMetadata(LowestStack);
806     SetNoSanitizeMetadata(Store);
807   }
808 }
809 
810 std::string
811 SanitizerCoverageModule::getSectionName(const std::string &Section) const {
812   if (TargetTriple.getObjectFormat() == Triple::COFF)
813     return ".SCOV$M";
814   if (TargetTriple.isOSBinFormatMachO())
815     return "__DATA,__" + Section;
816   return "__" + Section;
817 }
818 
819 std::string
820 SanitizerCoverageModule::getSectionStart(const std::string &Section) const {
821   if (TargetTriple.isOSBinFormatMachO())
822     return "\1section$start$__DATA$__" + Section;
823   return "__start___" + Section;
824 }
825 
826 std::string
827 SanitizerCoverageModule::getSectionEnd(const std::string &Section) const {
828   if (TargetTriple.isOSBinFormatMachO())
829     return "\1section$end$__DATA$__" + Section;
830   return "__stop___" + Section;
831 }
832 
833 
834 char SanitizerCoverageModule::ID = 0;
835 INITIALIZE_PASS_BEGIN(SanitizerCoverageModule, "sancov",
836                       "SanitizerCoverage: TODO."
837                       "ModulePass",
838                       false, false)
839 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
840 INITIALIZE_PASS_DEPENDENCY(PostDominatorTreeWrapperPass)
841 INITIALIZE_PASS_END(SanitizerCoverageModule, "sancov",
842                     "SanitizerCoverage: TODO."
843                     "ModulePass",
844                     false, false)
845 ModulePass *llvm::createSanitizerCoverageModulePass(
846     const SanitizerCoverageOptions &Options) {
847   return new SanitizerCoverageModule(Options);
848 }
849