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