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/AnalysisContext.h"
16 #include "BodyFarm.h"
17 #include "clang/AST/ASTContext.h"
18 #include "clang/AST/Decl.h"
19 #include "clang/AST/DeclObjC.h"
20 #include "clang/AST/DeclTemplate.h"
21 #include "clang/AST/ParentMap.h"
22 #include "clang/AST/StmtVisitor.h"
23 #include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
24 #include "clang/Analysis/Analyses/LiveVariables.h"
25 #include "clang/Analysis/Analyses/PseudoConstantAnalysis.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(bool useUnoptimizedCFG,
67                                                        bool addImplicitDtors,
68                                                        bool addInitializers,
69                                                        bool addTemporaryDtors,
70                                                        bool synthesizeBodies,
71                                                        bool addStaticInitBranch,
72                                                        bool addCXXNewAllocator,
73                                                        CodeInjector *injector)
74   : Injector(injector), SynthesizeBodies(synthesizeBodies)
75 {
76   cfgBuildOptions.PruneTriviallyFalseEdges = !useUnoptimizedCFG;
77   cfgBuildOptions.AddImplicitDtors = addImplicitDtors;
78   cfgBuildOptions.AddInitializers = addInitializers;
79   cfgBuildOptions.AddTemporaryDtors = addTemporaryDtors;
80   cfgBuildOptions.AddStaticInitBranches = addStaticInitBranch;
81   cfgBuildOptions.AddCXXNewAllocator = addCXXNewAllocator;
82 }
83 
84 void AnalysisDeclContextManager::clear() { Contexts.clear(); }
85 
86 static BodyFarm &getBodyFarm(ASTContext &C, CodeInjector *injector = nullptr) {
87   static BodyFarm *BF = new BodyFarm(C, injector);
88   return *BF;
89 }
90 
91 Stmt *AnalysisDeclContext::getBody(bool &IsAutosynthesized) const {
92   IsAutosynthesized = false;
93   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
94     Stmt *Body = FD->getBody();
95     if (Manager && Manager->synthesizeBodies()) {
96       Stmt *SynthesizedBody =
97           getBodyFarm(getASTContext(), Manager->Injector.get()).getBody(FD);
98       if (SynthesizedBody) {
99         Body = SynthesizedBody;
100         IsAutosynthesized = true;
101       }
102     }
103     return Body;
104   }
105   else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
106     Stmt *Body = MD->getBody();
107     if (Manager && Manager->synthesizeBodies()) {
108       Stmt *SynthesizedBody =
109           getBodyFarm(getASTContext(), Manager->Injector.get()).getBody(MD);
110       if (SynthesizedBody) {
111         Body = SynthesizedBody;
112         IsAutosynthesized = true;
113       }
114     }
115     return Body;
116   } else if (const BlockDecl *BD = dyn_cast<BlockDecl>(D))
117     return BD->getBody();
118   else if (const FunctionTemplateDecl *FunTmpl
119            = dyn_cast_or_null<FunctionTemplateDecl>(D))
120     return FunTmpl->getTemplatedDecl()->getBody();
121 
122   llvm_unreachable("unknown code decl");
123 }
124 
125 Stmt *AnalysisDeclContext::getBody() const {
126   bool Tmp;
127   return getBody(Tmp);
128 }
129 
130 bool AnalysisDeclContext::isBodyAutosynthesized() const {
131   bool Tmp;
132   getBody(Tmp);
133   return Tmp;
134 }
135 
136 bool AnalysisDeclContext::isBodyAutosynthesizedFromModelFile() const {
137   bool Tmp;
138   Stmt *Body = getBody(Tmp);
139   return Tmp && Body->getLocStart().isValid();
140 }
141 
142 /// Returns true if \param VD is an Objective-C implicit 'self' parameter.
143 static bool isSelfDecl(const VarDecl *VD) {
144   return isa<ImplicitParamDecl>(VD) && VD->getName() == "self";
145 }
146 
147 const ImplicitParamDecl *AnalysisDeclContext::getSelfDecl() const {
148   if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D))
149     return MD->getSelfDecl();
150   if (const BlockDecl *BD = dyn_cast<BlockDecl>(D)) {
151     // See if 'self' was captured by the block.
152     for (const auto &I : BD->captures()) {
153       const VarDecl *VD = I.getVariable();
154       if (isSelfDecl(VD))
155         return dyn_cast<ImplicitParamDecl>(VD);
156     }
157   }
158 
159   auto *CXXMethod = dyn_cast<CXXMethodDecl>(D);
160   if (!CXXMethod)
161     return nullptr;
162 
163   const CXXRecordDecl *parent = CXXMethod->getParent();
164   if (!parent->isLambda())
165     return nullptr;
166 
167   for (const LambdaCapture &LC : parent->captures()) {
168     if (!LC.capturesVariable())
169       continue;
170 
171     VarDecl *VD = LC.getCapturedVar();
172     if (isSelfDecl(VD))
173       return dyn_cast<ImplicitParamDecl>(VD);
174   }
175 
176   return nullptr;
177 }
178 
179 void AnalysisDeclContext::registerForcedBlockExpression(const Stmt *stmt) {
180   if (!forcedBlkExprs)
181     forcedBlkExprs = new CFG::BuildOptions::ForcedBlkExprs();
182   // Default construct an entry for 'stmt'.
183   if (const Expr *e = dyn_cast<Expr>(stmt))
184     stmt = e->IgnoreParens();
185   (void) (*forcedBlkExprs)[stmt];
186 }
187 
188 const CFGBlock *
189 AnalysisDeclContext::getBlockForRegisteredExpression(const Stmt *stmt) {
190   assert(forcedBlkExprs);
191   if (const Expr *e = dyn_cast<Expr>(stmt))
192     stmt = e->IgnoreParens();
193   CFG::BuildOptions::ForcedBlkExprs::const_iterator itr =
194     forcedBlkExprs->find(stmt);
195   assert(itr != forcedBlkExprs->end());
196   return itr->second;
197 }
198 
199 /// Add each synthetic statement in the CFG to the parent map, using the
200 /// source statement's parent.
201 static void addParentsForSyntheticStmts(const CFG *TheCFG, ParentMap &PM) {
202   if (!TheCFG)
203     return;
204 
205   for (CFG::synthetic_stmt_iterator I = TheCFG->synthetic_stmt_begin(),
206                                     E = TheCFG->synthetic_stmt_end();
207        I != E; ++I) {
208     PM.setParent(I->first, PM.getParent(I->second));
209   }
210 }
211 
212 CFG *AnalysisDeclContext::getCFG() {
213   if (!cfgBuildOptions.PruneTriviallyFalseEdges)
214     return getUnoptimizedCFG();
215 
216   if (!builtCFG) {
217     cfg = CFG::buildCFG(D, getBody(), &D->getASTContext(), cfgBuildOptions);
218     // Even when the cfg is not successfully built, we don't
219     // want to try building it again.
220     builtCFG = true;
221 
222     if (PM)
223       addParentsForSyntheticStmts(cfg.get(), *PM);
224 
225     // The Observer should only observe one build of the CFG.
226     getCFGBuildOptions().Observer = nullptr;
227   }
228   return cfg.get();
229 }
230 
231 CFG *AnalysisDeclContext::getUnoptimizedCFG() {
232   if (!builtCompleteCFG) {
233     SaveAndRestore<bool> NotPrune(cfgBuildOptions.PruneTriviallyFalseEdges,
234                                   false);
235     completeCFG =
236         CFG::buildCFG(D, getBody(), &D->getASTContext(), cfgBuildOptions);
237     // Even when the cfg is not successfully built, we don't
238     // want to try building it again.
239     builtCompleteCFG = true;
240 
241     if (PM)
242       addParentsForSyntheticStmts(completeCFG.get(), *PM);
243 
244     // The Observer should only observe one build of the CFG.
245     getCFGBuildOptions().Observer = nullptr;
246   }
247   return completeCFG.get();
248 }
249 
250 CFGStmtMap *AnalysisDeclContext::getCFGStmtMap() {
251   if (cfgStmtMap)
252     return cfgStmtMap.get();
253 
254   if (CFG *c = getCFG()) {
255     cfgStmtMap.reset(CFGStmtMap::Build(c, &getParentMap()));
256     return cfgStmtMap.get();
257   }
258 
259   return nullptr;
260 }
261 
262 CFGReverseBlockReachabilityAnalysis *AnalysisDeclContext::getCFGReachablityAnalysis() {
263   if (CFA)
264     return CFA.get();
265 
266   if (CFG *c = getCFG()) {
267     CFA.reset(new CFGReverseBlockReachabilityAnalysis(*c));
268     return CFA.get();
269   }
270 
271   return nullptr;
272 }
273 
274 void AnalysisDeclContext::dumpCFG(bool ShowColors) {
275     getCFG()->dump(getASTContext().getLangOpts(), ShowColors);
276 }
277 
278 ParentMap &AnalysisDeclContext::getParentMap() {
279   if (!PM) {
280     PM.reset(new ParentMap(getBody()));
281     if (const CXXConstructorDecl *C = dyn_cast<CXXConstructorDecl>(getDecl())) {
282       for (const auto *I : C->inits()) {
283         PM->addStmt(I->getInit());
284       }
285     }
286     if (builtCFG)
287       addParentsForSyntheticStmts(getCFG(), *PM);
288     if (builtCompleteCFG)
289       addParentsForSyntheticStmts(getUnoptimizedCFG(), *PM);
290   }
291   return *PM;
292 }
293 
294 PseudoConstantAnalysis *AnalysisDeclContext::getPseudoConstantAnalysis() {
295   if (!PCA)
296     PCA.reset(new PseudoConstantAnalysis(getBody()));
297   return PCA.get();
298 }
299 
300 AnalysisDeclContext *AnalysisDeclContextManager::getContext(const Decl *D) {
301   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
302     // Calling 'hasBody' replaces 'FD' in place with the FunctionDecl
303     // that has the body.
304     FD->hasBody(FD);
305     D = FD;
306   }
307 
308   std::unique_ptr<AnalysisDeclContext> &AC = Contexts[D];
309   if (!AC)
310     AC = llvm::make_unique<AnalysisDeclContext>(this, D, cfgBuildOptions);
311   return AC.get();
312 }
313 
314 const StackFrameContext *
315 AnalysisDeclContext::getStackFrame(LocationContext const *Parent, const Stmt *S,
316                                const CFGBlock *Blk, unsigned Idx) {
317   return getLocationContextManager().getStackFrame(this, Parent, S, Blk, Idx);
318 }
319 
320 const BlockInvocationContext *
321 AnalysisDeclContext::getBlockInvocationContext(const LocationContext *parent,
322                                                const clang::BlockDecl *BD,
323                                                const void *ContextData) {
324   return getLocationContextManager().getBlockInvocationContext(this, parent,
325                                                                BD, ContextData);
326 }
327 
328 bool AnalysisDeclContext::isInStdNamespace(const Decl *D) {
329   const DeclContext *DC = D->getDeclContext()->getEnclosingNamespaceContext();
330   const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC);
331   if (!ND)
332     return false;
333 
334   while (const DeclContext *Parent = ND->getParent()) {
335     if (!isa<NamespaceDecl>(Parent))
336       break;
337     ND = cast<NamespaceDecl>(Parent);
338   }
339 
340   return ND->isStdNamespace();
341 }
342 
343 LocationContextManager & AnalysisDeclContext::getLocationContextManager() {
344   assert(Manager &&
345          "Cannot create LocationContexts without an AnalysisDeclContextManager!");
346   return Manager->getLocationContextManager();
347 }
348 
349 //===----------------------------------------------------------------------===//
350 // FoldingSet profiling.
351 //===----------------------------------------------------------------------===//
352 
353 void LocationContext::ProfileCommon(llvm::FoldingSetNodeID &ID,
354                                     ContextKind ck,
355                                     AnalysisDeclContext *ctx,
356                                     const LocationContext *parent,
357                                     const void *data) {
358   ID.AddInteger(ck);
359   ID.AddPointer(ctx);
360   ID.AddPointer(parent);
361   ID.AddPointer(data);
362 }
363 
364 void StackFrameContext::Profile(llvm::FoldingSetNodeID &ID) {
365   Profile(ID, getAnalysisDeclContext(), getParent(), CallSite, Block, Index);
366 }
367 
368 void ScopeContext::Profile(llvm::FoldingSetNodeID &ID) {
369   Profile(ID, getAnalysisDeclContext(), getParent(), Enter);
370 }
371 
372 void BlockInvocationContext::Profile(llvm::FoldingSetNodeID &ID) {
373   Profile(ID, getAnalysisDeclContext(), getParent(), BD, ContextData);
374 }
375 
376 //===----------------------------------------------------------------------===//
377 // LocationContext creation.
378 //===----------------------------------------------------------------------===//
379 
380 template <typename LOC, typename DATA>
381 const LOC*
382 LocationContextManager::getLocationContext(AnalysisDeclContext *ctx,
383                                            const LocationContext *parent,
384                                            const DATA *d) {
385   llvm::FoldingSetNodeID ID;
386   LOC::Profile(ID, ctx, parent, d);
387   void *InsertPos;
388 
389   LOC *L = cast_or_null<LOC>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
390 
391   if (!L) {
392     L = new LOC(ctx, parent, d);
393     Contexts.InsertNode(L, InsertPos);
394   }
395   return L;
396 }
397 
398 const StackFrameContext*
399 LocationContextManager::getStackFrame(AnalysisDeclContext *ctx,
400                                       const LocationContext *parent,
401                                       const Stmt *s,
402                                       const CFGBlock *blk, unsigned idx) {
403   llvm::FoldingSetNodeID ID;
404   StackFrameContext::Profile(ID, ctx, parent, s, blk, idx);
405   void *InsertPos;
406   StackFrameContext *L =
407    cast_or_null<StackFrameContext>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
408   if (!L) {
409     L = new StackFrameContext(ctx, parent, s, blk, idx);
410     Contexts.InsertNode(L, InsertPos);
411   }
412   return L;
413 }
414 
415 const ScopeContext *
416 LocationContextManager::getScope(AnalysisDeclContext *ctx,
417                                  const LocationContext *parent,
418                                  const Stmt *s) {
419   return getLocationContext<ScopeContext, Stmt>(ctx, parent, s);
420 }
421 
422 const BlockInvocationContext *
423 LocationContextManager::getBlockInvocationContext(AnalysisDeclContext *ctx,
424                                                   const LocationContext *parent,
425                                                   const BlockDecl *BD,
426                                                   const void *ContextData) {
427   llvm::FoldingSetNodeID ID;
428   BlockInvocationContext::Profile(ID, ctx, parent, BD, ContextData);
429   void *InsertPos;
430   BlockInvocationContext *L =
431     cast_or_null<BlockInvocationContext>(Contexts.FindNodeOrInsertPos(ID,
432                                                                     InsertPos));
433   if (!L) {
434     L = new BlockInvocationContext(ctx, parent, BD, ContextData);
435     Contexts.InsertNode(L, InsertPos);
436   }
437   return L;
438 }
439 
440 //===----------------------------------------------------------------------===//
441 // LocationContext methods.
442 //===----------------------------------------------------------------------===//
443 
444 const StackFrameContext *LocationContext::getCurrentStackFrame() const {
445   const LocationContext *LC = this;
446   while (LC) {
447     if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LC))
448       return SFC;
449     LC = LC->getParent();
450   }
451   return nullptr;
452 }
453 
454 bool LocationContext::inTopFrame() const {
455   return getCurrentStackFrame()->inTopFrame();
456 }
457 
458 bool LocationContext::isParentOf(const LocationContext *LC) const {
459   do {
460     const LocationContext *Parent = LC->getParent();
461     if (Parent == this)
462       return true;
463     else
464       LC = Parent;
465   } while (LC);
466 
467   return false;
468 }
469 
470 void LocationContext::dumpStack(raw_ostream &OS, StringRef Indent) const {
471   ASTContext &Ctx = getAnalysisDeclContext()->getASTContext();
472   PrintingPolicy PP(Ctx.getLangOpts());
473   PP.TerseOutput = 1;
474 
475   unsigned Frame = 0;
476   for (const LocationContext *LCtx = this; LCtx; LCtx = LCtx->getParent()) {
477     switch (LCtx->getKind()) {
478     case StackFrame:
479       OS << Indent << '#' << Frame++ << ' ';
480       cast<StackFrameContext>(LCtx)->getDecl()->print(OS, PP);
481       OS << '\n';
482       break;
483     case Scope:
484       OS << Indent << "    (scope)\n";
485       break;
486     case Block:
487       OS << Indent << "    (block context: "
488                    << cast<BlockInvocationContext>(LCtx)->getContextData()
489                    << ")\n";
490       break;
491     }
492   }
493 }
494 
495 LLVM_DUMP_METHOD void LocationContext::dumpStack() const {
496   dumpStack(llvm::errs());
497 }
498 
499 //===----------------------------------------------------------------------===//
500 // Lazily generated map to query the external variables referenced by a Block.
501 //===----------------------------------------------------------------------===//
502 
503 namespace {
504 class FindBlockDeclRefExprsVals : public StmtVisitor<FindBlockDeclRefExprsVals>{
505   BumpVector<const VarDecl*> &BEVals;
506   BumpVectorContext &BC;
507   llvm::SmallPtrSet<const VarDecl*, 4> Visited;
508   llvm::SmallPtrSet<const DeclContext*, 4> IgnoredContexts;
509 public:
510   FindBlockDeclRefExprsVals(BumpVector<const VarDecl*> &bevals,
511                             BumpVectorContext &bc)
512   : BEVals(bevals), BC(bc) {}
513 
514   void VisitStmt(Stmt *S) {
515     for (Stmt *Child : S->children())
516       if (Child)
517         Visit(Child);
518   }
519 
520   void VisitDeclRefExpr(DeclRefExpr *DR) {
521     // Non-local variables are also directly modified.
522     if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
523       if (!VD->hasLocalStorage()) {
524         if (Visited.insert(VD).second)
525           BEVals.push_back(VD, BC);
526       }
527     }
528   }
529 
530   void VisitBlockExpr(BlockExpr *BR) {
531     // Blocks containing blocks can transitively capture more variables.
532     IgnoredContexts.insert(BR->getBlockDecl());
533     Visit(BR->getBlockDecl()->getBody());
534   }
535 
536   void VisitPseudoObjectExpr(PseudoObjectExpr *PE) {
537     for (PseudoObjectExpr::semantics_iterator it = PE->semantics_begin(),
538          et = PE->semantics_end(); it != et; ++it) {
539       Expr *Semantic = *it;
540       if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(Semantic))
541         Semantic = OVE->getSourceExpr();
542       Visit(Semantic);
543     }
544   }
545 };
546 } // end anonymous namespace
547 
548 typedef BumpVector<const VarDecl*> DeclVec;
549 
550 static DeclVec* LazyInitializeReferencedDecls(const BlockDecl *BD,
551                                               void *&Vec,
552                                               llvm::BumpPtrAllocator &A) {
553   if (Vec)
554     return (DeclVec*) Vec;
555 
556   BumpVectorContext BC(A);
557   DeclVec *BV = (DeclVec*) A.Allocate<DeclVec>();
558   new (BV) DeclVec(BC, 10);
559 
560   // Go through the capture list.
561   for (const auto &CI : BD->captures()) {
562     BV->push_back(CI.getVariable(), BC);
563   }
564 
565   // Find the referenced global/static variables.
566   FindBlockDeclRefExprsVals F(*BV, BC);
567   F.Visit(BD->getBody());
568 
569   Vec = BV;
570   return BV;
571 }
572 
573 llvm::iterator_range<AnalysisDeclContext::referenced_decls_iterator>
574 AnalysisDeclContext::getReferencedBlockVars(const BlockDecl *BD) {
575   if (!ReferencedBlockVars)
576     ReferencedBlockVars = new llvm::DenseMap<const BlockDecl*,void*>();
577 
578   const DeclVec *V =
579       LazyInitializeReferencedDecls(BD, (*ReferencedBlockVars)[BD], A);
580   return llvm::make_range(V->begin(), V->end());
581 }
582 
583 ManagedAnalysis *&AnalysisDeclContext::getAnalysisImpl(const void *tag) {
584   if (!ManagedAnalyses)
585     ManagedAnalyses = new ManagedAnalysisMap();
586   ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
587   return (*M)[tag];
588 }
589 
590 //===----------------------------------------------------------------------===//
591 // Cleanup.
592 //===----------------------------------------------------------------------===//
593 
594 ManagedAnalysis::~ManagedAnalysis() {}
595 
596 AnalysisDeclContext::~AnalysisDeclContext() {
597   delete forcedBlkExprs;
598   delete ReferencedBlockVars;
599   // Release the managed analyses.
600   if (ManagedAnalyses) {
601     ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
602     llvm::DeleteContainerSeconds(*M);
603     delete M;
604   }
605 }
606 
607 AnalysisDeclContextManager::~AnalysisDeclContextManager() {}
608 
609 LocationContext::~LocationContext() {}
610 
611 LocationContextManager::~LocationContextManager() {
612   clear();
613 }
614 
615 void LocationContextManager::clear() {
616   for (llvm::FoldingSet<LocationContext>::iterator I = Contexts.begin(),
617        E = Contexts.end(); I != E; ) {
618     LocationContext *LC = &*I;
619     ++I;
620     delete LC;
621   }
622 
623   Contexts.clear();
624 }
625 
626