1 //== AnalysisDeclContext.cpp - Analysis context for Path Sens analysis -*- C++ -*-//
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 // This file defines AnalysisDeclContext, a class that manages the analysis context
11 // data for path sensitive analysis.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/Analysis/AnalysisDeclContext.h"
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/Decl.h"
18 #include "clang/AST/DeclObjC.h"
19 #include "clang/AST/DeclTemplate.h"
20 #include "clang/AST/ParentMap.h"
21 #include "clang/AST/StmtVisitor.h"
22 #include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
23 #include "clang/Analysis/Analyses/LiveVariables.h"
24 #include "clang/Analysis/Analyses/PseudoConstantAnalysis.h"
25 #include "clang/Analysis/BodyFarm.h"
26 #include "clang/Analysis/CFG.h"
27 #include "clang/Analysis/CFGStmtMap.h"
28 #include "clang/Analysis/Support/BumpVector.h"
29 #include "llvm/ADT/SmallPtrSet.h"
30 #include "llvm/Support/ErrorHandling.h"
31 #include "llvm/Support/SaveAndRestore.h"
32 #include "llvm/Support/raw_ostream.h"
33 
34 using namespace clang;
35 
36 typedef llvm::DenseMap<const void *, ManagedAnalysis *> ManagedAnalysisMap;
37 
38 AnalysisDeclContext::AnalysisDeclContext(AnalysisDeclContextManager *Mgr,
39                                          const Decl *d,
40                                          const CFG::BuildOptions &buildOptions)
41   : Manager(Mgr),
42     D(d),
43     cfgBuildOptions(buildOptions),
44     forcedBlkExprs(nullptr),
45     builtCFG(false),
46     builtCompleteCFG(false),
47     ReferencedBlockVars(nullptr),
48     ManagedAnalyses(nullptr)
49 {
50   cfgBuildOptions.forcedBlkExprs = &forcedBlkExprs;
51 }
52 
53 AnalysisDeclContext::AnalysisDeclContext(AnalysisDeclContextManager *Mgr,
54                                          const Decl *d)
55 : Manager(Mgr),
56   D(d),
57   forcedBlkExprs(nullptr),
58   builtCFG(false),
59   builtCompleteCFG(false),
60   ReferencedBlockVars(nullptr),
61   ManagedAnalyses(nullptr)
62 {
63   cfgBuildOptions.forcedBlkExprs = &forcedBlkExprs;
64 }
65 
66 AnalysisDeclContextManager::AnalysisDeclContextManager(
67     ASTContext &ASTCtx, bool useUnoptimizedCFG, bool addImplicitDtors,
68     bool addInitializers, bool addTemporaryDtors, bool addLifetime,
69     bool addLoopExit, bool synthesizeBodies, bool addStaticInitBranch,
70     bool addCXXNewAllocator, CodeInjector *injector)
71     : Injector(injector), FunctionBodyFarm(ASTCtx, injector),
72       SynthesizeBodies(synthesizeBodies) {
73   cfgBuildOptions.PruneTriviallyFalseEdges = !useUnoptimizedCFG;
74   cfgBuildOptions.AddImplicitDtors = addImplicitDtors;
75   cfgBuildOptions.AddInitializers = addInitializers;
76   cfgBuildOptions.AddTemporaryDtors = addTemporaryDtors;
77   cfgBuildOptions.AddLifetime = addLifetime;
78   cfgBuildOptions.AddLoopExit = addLoopExit;
79   cfgBuildOptions.AddStaticInitBranches = addStaticInitBranch;
80   cfgBuildOptions.AddCXXNewAllocator = addCXXNewAllocator;
81 }
82 
83 void AnalysisDeclContextManager::clear() { Contexts.clear(); }
84 
85 Stmt *AnalysisDeclContext::getBody(bool &IsAutosynthesized) const {
86   IsAutosynthesized = false;
87   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
88     Stmt *Body = FD->getBody();
89     if (auto *CoroBody = dyn_cast_or_null<CoroutineBodyStmt>(Body))
90       Body = CoroBody->getBody();
91     if (Manager && Manager->synthesizeBodies()) {
92       Stmt *SynthesizedBody = Manager->getBodyFarm().getBody(FD);
93       if (SynthesizedBody) {
94         Body = SynthesizedBody;
95         IsAutosynthesized = true;
96       }
97     }
98     return Body;
99   }
100   else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
101     Stmt *Body = MD->getBody();
102     if (Manager && Manager->synthesizeBodies()) {
103       Stmt *SynthesizedBody = Manager->getBodyFarm().getBody(MD);
104       if (SynthesizedBody) {
105         Body = SynthesizedBody;
106         IsAutosynthesized = true;
107       }
108     }
109     return Body;
110   } else if (const BlockDecl *BD = dyn_cast<BlockDecl>(D))
111     return BD->getBody();
112   else if (const FunctionTemplateDecl *FunTmpl
113            = dyn_cast_or_null<FunctionTemplateDecl>(D))
114     return FunTmpl->getTemplatedDecl()->getBody();
115 
116   llvm_unreachable("unknown code decl");
117 }
118 
119 Stmt *AnalysisDeclContext::getBody() const {
120   bool Tmp;
121   return getBody(Tmp);
122 }
123 
124 bool AnalysisDeclContext::isBodyAutosynthesized() const {
125   bool Tmp;
126   getBody(Tmp);
127   return Tmp;
128 }
129 
130 bool AnalysisDeclContext::isBodyAutosynthesizedFromModelFile() const {
131   bool Tmp;
132   Stmt *Body = getBody(Tmp);
133   return Tmp && Body->getLocStart().isValid();
134 }
135 
136 /// Returns true if \param VD is an Objective-C implicit 'self' parameter.
137 static bool isSelfDecl(const VarDecl *VD) {
138   return isa<ImplicitParamDecl>(VD) && VD->getName() == "self";
139 }
140 
141 const ImplicitParamDecl *AnalysisDeclContext::getSelfDecl() const {
142   if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D))
143     return MD->getSelfDecl();
144   if (const BlockDecl *BD = dyn_cast<BlockDecl>(D)) {
145     // See if 'self' was captured by the block.
146     for (const auto &I : BD->captures()) {
147       const VarDecl *VD = I.getVariable();
148       if (isSelfDecl(VD))
149         return dyn_cast<ImplicitParamDecl>(VD);
150     }
151   }
152 
153   auto *CXXMethod = dyn_cast<CXXMethodDecl>(D);
154   if (!CXXMethod)
155     return nullptr;
156 
157   const CXXRecordDecl *parent = CXXMethod->getParent();
158   if (!parent->isLambda())
159     return nullptr;
160 
161   for (const LambdaCapture &LC : parent->captures()) {
162     if (!LC.capturesVariable())
163       continue;
164 
165     VarDecl *VD = LC.getCapturedVar();
166     if (isSelfDecl(VD))
167       return dyn_cast<ImplicitParamDecl>(VD);
168   }
169 
170   return nullptr;
171 }
172 
173 void AnalysisDeclContext::registerForcedBlockExpression(const Stmt *stmt) {
174   if (!forcedBlkExprs)
175     forcedBlkExprs = new CFG::BuildOptions::ForcedBlkExprs();
176   // Default construct an entry for 'stmt'.
177   if (const Expr *e = dyn_cast<Expr>(stmt))
178     stmt = e->IgnoreParens();
179   (void) (*forcedBlkExprs)[stmt];
180 }
181 
182 const CFGBlock *
183 AnalysisDeclContext::getBlockForRegisteredExpression(const Stmt *stmt) {
184   assert(forcedBlkExprs);
185   if (const Expr *e = dyn_cast<Expr>(stmt))
186     stmt = e->IgnoreParens();
187   CFG::BuildOptions::ForcedBlkExprs::const_iterator itr =
188     forcedBlkExprs->find(stmt);
189   assert(itr != forcedBlkExprs->end());
190   return itr->second;
191 }
192 
193 /// Add each synthetic statement in the CFG to the parent map, using the
194 /// source statement's parent.
195 static void addParentsForSyntheticStmts(const CFG *TheCFG, ParentMap &PM) {
196   if (!TheCFG)
197     return;
198 
199   for (CFG::synthetic_stmt_iterator I = TheCFG->synthetic_stmt_begin(),
200                                     E = TheCFG->synthetic_stmt_end();
201        I != E; ++I) {
202     PM.setParent(I->first, PM.getParent(I->second));
203   }
204 }
205 
206 CFG *AnalysisDeclContext::getCFG() {
207   if (!cfgBuildOptions.PruneTriviallyFalseEdges)
208     return getUnoptimizedCFG();
209 
210   if (!builtCFG) {
211     cfg = CFG::buildCFG(D, getBody(), &D->getASTContext(), cfgBuildOptions);
212     // Even when the cfg is not successfully built, we don't
213     // want to try building it again.
214     builtCFG = true;
215 
216     if (PM)
217       addParentsForSyntheticStmts(cfg.get(), *PM);
218 
219     // The Observer should only observe one build of the CFG.
220     getCFGBuildOptions().Observer = nullptr;
221   }
222   return cfg.get();
223 }
224 
225 CFG *AnalysisDeclContext::getUnoptimizedCFG() {
226   if (!builtCompleteCFG) {
227     SaveAndRestore<bool> NotPrune(cfgBuildOptions.PruneTriviallyFalseEdges,
228                                   false);
229     completeCFG =
230         CFG::buildCFG(D, getBody(), &D->getASTContext(), cfgBuildOptions);
231     // Even when the cfg is not successfully built, we don't
232     // want to try building it again.
233     builtCompleteCFG = true;
234 
235     if (PM)
236       addParentsForSyntheticStmts(completeCFG.get(), *PM);
237 
238     // The Observer should only observe one build of the CFG.
239     getCFGBuildOptions().Observer = nullptr;
240   }
241   return completeCFG.get();
242 }
243 
244 CFGStmtMap *AnalysisDeclContext::getCFGStmtMap() {
245   if (cfgStmtMap)
246     return cfgStmtMap.get();
247 
248   if (CFG *c = getCFG()) {
249     cfgStmtMap.reset(CFGStmtMap::Build(c, &getParentMap()));
250     return cfgStmtMap.get();
251   }
252 
253   return nullptr;
254 }
255 
256 CFGReverseBlockReachabilityAnalysis *AnalysisDeclContext::getCFGReachablityAnalysis() {
257   if (CFA)
258     return CFA.get();
259 
260   if (CFG *c = getCFG()) {
261     CFA.reset(new CFGReverseBlockReachabilityAnalysis(*c));
262     return CFA.get();
263   }
264 
265   return nullptr;
266 }
267 
268 void AnalysisDeclContext::dumpCFG(bool ShowColors) {
269     getCFG()->dump(getASTContext().getLangOpts(), ShowColors);
270 }
271 
272 ParentMap &AnalysisDeclContext::getParentMap() {
273   if (!PM) {
274     PM.reset(new ParentMap(getBody()));
275     if (const CXXConstructorDecl *C = dyn_cast<CXXConstructorDecl>(getDecl())) {
276       for (const auto *I : C->inits()) {
277         PM->addStmt(I->getInit());
278       }
279     }
280     if (builtCFG)
281       addParentsForSyntheticStmts(getCFG(), *PM);
282     if (builtCompleteCFG)
283       addParentsForSyntheticStmts(getUnoptimizedCFG(), *PM);
284   }
285   return *PM;
286 }
287 
288 PseudoConstantAnalysis *AnalysisDeclContext::getPseudoConstantAnalysis() {
289   if (!PCA)
290     PCA.reset(new PseudoConstantAnalysis(getBody()));
291   return PCA.get();
292 }
293 
294 AnalysisDeclContext *AnalysisDeclContextManager::getContext(const Decl *D) {
295   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
296     // Calling 'hasBody' replaces 'FD' in place with the FunctionDecl
297     // that has the body.
298     FD->hasBody(FD);
299     D = FD;
300   }
301 
302   std::unique_ptr<AnalysisDeclContext> &AC = Contexts[D];
303   if (!AC)
304     AC = llvm::make_unique<AnalysisDeclContext>(this, D, cfgBuildOptions);
305   return AC.get();
306 }
307 
308 BodyFarm &AnalysisDeclContextManager::getBodyFarm() { return FunctionBodyFarm; }
309 
310 const StackFrameContext *
311 AnalysisDeclContext::getStackFrame(LocationContext const *Parent, const Stmt *S,
312                                const CFGBlock *Blk, unsigned Idx) {
313   return getLocationContextManager().getStackFrame(this, Parent, S, Blk, Idx);
314 }
315 
316 const BlockInvocationContext *
317 AnalysisDeclContext::getBlockInvocationContext(const LocationContext *parent,
318                                                const clang::BlockDecl *BD,
319                                                const void *ContextData) {
320   return getLocationContextManager().getBlockInvocationContext(this, parent,
321                                                                BD, ContextData);
322 }
323 
324 bool AnalysisDeclContext::isInStdNamespace(const Decl *D) {
325   const DeclContext *DC = D->getDeclContext()->getEnclosingNamespaceContext();
326   const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC);
327   if (!ND)
328     return false;
329 
330   while (const DeclContext *Parent = ND->getParent()) {
331     if (!isa<NamespaceDecl>(Parent))
332       break;
333     ND = cast<NamespaceDecl>(Parent);
334   }
335 
336   return ND->isStdNamespace();
337 }
338 
339 LocationContextManager & AnalysisDeclContext::getLocationContextManager() {
340   assert(Manager &&
341          "Cannot create LocationContexts without an AnalysisDeclContextManager!");
342   return Manager->getLocationContextManager();
343 }
344 
345 //===----------------------------------------------------------------------===//
346 // FoldingSet profiling.
347 //===----------------------------------------------------------------------===//
348 
349 void LocationContext::ProfileCommon(llvm::FoldingSetNodeID &ID,
350                                     ContextKind ck,
351                                     AnalysisDeclContext *ctx,
352                                     const LocationContext *parent,
353                                     const void *data) {
354   ID.AddInteger(ck);
355   ID.AddPointer(ctx);
356   ID.AddPointer(parent);
357   ID.AddPointer(data);
358 }
359 
360 void StackFrameContext::Profile(llvm::FoldingSetNodeID &ID) {
361   Profile(ID, getAnalysisDeclContext(), getParent(), CallSite, Block, Index);
362 }
363 
364 void ScopeContext::Profile(llvm::FoldingSetNodeID &ID) {
365   Profile(ID, getAnalysisDeclContext(), getParent(), Enter);
366 }
367 
368 void BlockInvocationContext::Profile(llvm::FoldingSetNodeID &ID) {
369   Profile(ID, getAnalysisDeclContext(), getParent(), BD, ContextData);
370 }
371 
372 //===----------------------------------------------------------------------===//
373 // LocationContext creation.
374 //===----------------------------------------------------------------------===//
375 
376 template <typename LOC, typename DATA>
377 const LOC*
378 LocationContextManager::getLocationContext(AnalysisDeclContext *ctx,
379                                            const LocationContext *parent,
380                                            const DATA *d) {
381   llvm::FoldingSetNodeID ID;
382   LOC::Profile(ID, ctx, parent, d);
383   void *InsertPos;
384 
385   LOC *L = cast_or_null<LOC>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
386 
387   if (!L) {
388     L = new LOC(ctx, parent, d);
389     Contexts.InsertNode(L, InsertPos);
390   }
391   return L;
392 }
393 
394 const StackFrameContext*
395 LocationContextManager::getStackFrame(AnalysisDeclContext *ctx,
396                                       const LocationContext *parent,
397                                       const Stmt *s,
398                                       const CFGBlock *blk, unsigned idx) {
399   llvm::FoldingSetNodeID ID;
400   StackFrameContext::Profile(ID, ctx, parent, s, blk, idx);
401   void *InsertPos;
402   StackFrameContext *L =
403    cast_or_null<StackFrameContext>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
404   if (!L) {
405     L = new StackFrameContext(ctx, parent, s, blk, idx);
406     Contexts.InsertNode(L, InsertPos);
407   }
408   return L;
409 }
410 
411 const ScopeContext *
412 LocationContextManager::getScope(AnalysisDeclContext *ctx,
413                                  const LocationContext *parent,
414                                  const Stmt *s) {
415   return getLocationContext<ScopeContext, Stmt>(ctx, parent, s);
416 }
417 
418 const BlockInvocationContext *
419 LocationContextManager::getBlockInvocationContext(AnalysisDeclContext *ctx,
420                                                   const LocationContext *parent,
421                                                   const BlockDecl *BD,
422                                                   const void *ContextData) {
423   llvm::FoldingSetNodeID ID;
424   BlockInvocationContext::Profile(ID, ctx, parent, BD, ContextData);
425   void *InsertPos;
426   BlockInvocationContext *L =
427     cast_or_null<BlockInvocationContext>(Contexts.FindNodeOrInsertPos(ID,
428                                                                     InsertPos));
429   if (!L) {
430     L = new BlockInvocationContext(ctx, parent, BD, ContextData);
431     Contexts.InsertNode(L, InsertPos);
432   }
433   return L;
434 }
435 
436 //===----------------------------------------------------------------------===//
437 // LocationContext methods.
438 //===----------------------------------------------------------------------===//
439 
440 const StackFrameContext *LocationContext::getCurrentStackFrame() const {
441   const LocationContext *LC = this;
442   while (LC) {
443     if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LC))
444       return SFC;
445     LC = LC->getParent();
446   }
447   return nullptr;
448 }
449 
450 bool LocationContext::inTopFrame() const {
451   return getCurrentStackFrame()->inTopFrame();
452 }
453 
454 bool LocationContext::isParentOf(const LocationContext *LC) const {
455   do {
456     const LocationContext *Parent = LC->getParent();
457     if (Parent == this)
458       return true;
459     else
460       LC = Parent;
461   } while (LC);
462 
463   return false;
464 }
465 
466 void LocationContext::dumpStack(raw_ostream &OS, StringRef Indent) const {
467   ASTContext &Ctx = getAnalysisDeclContext()->getASTContext();
468   PrintingPolicy PP(Ctx.getLangOpts());
469   PP.TerseOutput = 1;
470 
471   unsigned Frame = 0;
472   for (const LocationContext *LCtx = this; LCtx; LCtx = LCtx->getParent()) {
473     switch (LCtx->getKind()) {
474     case StackFrame:
475       OS << Indent << '#' << Frame++ << ' ';
476       cast<StackFrameContext>(LCtx)->getDecl()->print(OS, PP);
477       OS << '\n';
478       break;
479     case Scope:
480       OS << Indent << "    (scope)\n";
481       break;
482     case Block:
483       OS << Indent << "    (block context: "
484                    << cast<BlockInvocationContext>(LCtx)->getContextData()
485                    << ")\n";
486       break;
487     }
488   }
489 }
490 
491 LLVM_DUMP_METHOD void LocationContext::dumpStack() const {
492   dumpStack(llvm::errs());
493 }
494 
495 //===----------------------------------------------------------------------===//
496 // Lazily generated map to query the external variables referenced by a Block.
497 //===----------------------------------------------------------------------===//
498 
499 namespace {
500 class FindBlockDeclRefExprsVals : public StmtVisitor<FindBlockDeclRefExprsVals>{
501   BumpVector<const VarDecl*> &BEVals;
502   BumpVectorContext &BC;
503   llvm::SmallPtrSet<const VarDecl*, 4> Visited;
504   llvm::SmallPtrSet<const DeclContext*, 4> IgnoredContexts;
505 public:
506   FindBlockDeclRefExprsVals(BumpVector<const VarDecl*> &bevals,
507                             BumpVectorContext &bc)
508   : BEVals(bevals), BC(bc) {}
509 
510   void VisitStmt(Stmt *S) {
511     for (Stmt *Child : S->children())
512       if (Child)
513         Visit(Child);
514   }
515 
516   void VisitDeclRefExpr(DeclRefExpr *DR) {
517     // Non-local variables are also directly modified.
518     if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
519       if (!VD->hasLocalStorage()) {
520         if (Visited.insert(VD).second)
521           BEVals.push_back(VD, BC);
522       }
523     }
524   }
525 
526   void VisitBlockExpr(BlockExpr *BR) {
527     // Blocks containing blocks can transitively capture more variables.
528     IgnoredContexts.insert(BR->getBlockDecl());
529     Visit(BR->getBlockDecl()->getBody());
530   }
531 
532   void VisitPseudoObjectExpr(PseudoObjectExpr *PE) {
533     for (PseudoObjectExpr::semantics_iterator it = PE->semantics_begin(),
534          et = PE->semantics_end(); it != et; ++it) {
535       Expr *Semantic = *it;
536       if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(Semantic))
537         Semantic = OVE->getSourceExpr();
538       Visit(Semantic);
539     }
540   }
541 };
542 } // end anonymous namespace
543 
544 typedef BumpVector<const VarDecl*> DeclVec;
545 
546 static DeclVec* LazyInitializeReferencedDecls(const BlockDecl *BD,
547                                               void *&Vec,
548                                               llvm::BumpPtrAllocator &A) {
549   if (Vec)
550     return (DeclVec*) Vec;
551 
552   BumpVectorContext BC(A);
553   DeclVec *BV = (DeclVec*) A.Allocate<DeclVec>();
554   new (BV) DeclVec(BC, 10);
555 
556   // Go through the capture list.
557   for (const auto &CI : BD->captures()) {
558     BV->push_back(CI.getVariable(), BC);
559   }
560 
561   // Find the referenced global/static variables.
562   FindBlockDeclRefExprsVals F(*BV, BC);
563   F.Visit(BD->getBody());
564 
565   Vec = BV;
566   return BV;
567 }
568 
569 llvm::iterator_range<AnalysisDeclContext::referenced_decls_iterator>
570 AnalysisDeclContext::getReferencedBlockVars(const BlockDecl *BD) {
571   if (!ReferencedBlockVars)
572     ReferencedBlockVars = new llvm::DenseMap<const BlockDecl*,void*>();
573 
574   const DeclVec *V =
575       LazyInitializeReferencedDecls(BD, (*ReferencedBlockVars)[BD], A);
576   return llvm::make_range(V->begin(), V->end());
577 }
578 
579 ManagedAnalysis *&AnalysisDeclContext::getAnalysisImpl(const void *tag) {
580   if (!ManagedAnalyses)
581     ManagedAnalyses = new ManagedAnalysisMap();
582   ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
583   return (*M)[tag];
584 }
585 
586 //===----------------------------------------------------------------------===//
587 // Cleanup.
588 //===----------------------------------------------------------------------===//
589 
590 ManagedAnalysis::~ManagedAnalysis() {}
591 
592 AnalysisDeclContext::~AnalysisDeclContext() {
593   delete forcedBlkExprs;
594   delete ReferencedBlockVars;
595   // Release the managed analyses.
596   if (ManagedAnalyses) {
597     ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
598     llvm::DeleteContainerSeconds(*M);
599     delete M;
600   }
601 }
602 
603 LocationContext::~LocationContext() {}
604 
605 LocationContextManager::~LocationContextManager() {
606   clear();
607 }
608 
609 void LocationContextManager::clear() {
610   for (llvm::FoldingSet<LocationContext>::iterator I = Contexts.begin(),
611        E = Contexts.end(); I != E; ) {
612     LocationContext *LC = &*I;
613     ++I;
614     delete LC;
615   }
616 
617   Contexts.clear();
618 }
619 
620