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 addLifetime,
71                                                        bool synthesizeBodies,
72                                                        bool addStaticInitBranch,
73                                                        bool addCXXNewAllocator,
74                                                        CodeInjector *injector)
75   : Injector(injector), SynthesizeBodies(synthesizeBodies)
76 {
77   cfgBuildOptions.PruneTriviallyFalseEdges = !useUnoptimizedCFG;
78   cfgBuildOptions.AddImplicitDtors = addImplicitDtors;
79   cfgBuildOptions.AddInitializers = addInitializers;
80   cfgBuildOptions.AddTemporaryDtors = addTemporaryDtors;
81   cfgBuildOptions.AddLifetime = addLifetime;
82   cfgBuildOptions.AddStaticInitBranches = addStaticInitBranch;
83   cfgBuildOptions.AddCXXNewAllocator = addCXXNewAllocator;
84 }
85 
86 void AnalysisDeclContextManager::clear() { Contexts.clear(); }
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 (auto *CoroBody = dyn_cast_or_null<CoroutineBodyStmt>(Body))
98       Body = CoroBody->getBody();
99     if (Manager && Manager->synthesizeBodies()) {
100       Stmt *SynthesizedBody =
101           getBodyFarm(getASTContext(), Manager->Injector.get()).getBody(FD);
102       if (SynthesizedBody) {
103         Body = SynthesizedBody;
104         IsAutosynthesized = true;
105       }
106     }
107     return Body;
108   }
109   else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
110     Stmt *Body = MD->getBody();
111     if (Manager && Manager->synthesizeBodies()) {
112       Stmt *SynthesizedBody =
113           getBodyFarm(getASTContext(), Manager->Injector.get()).getBody(MD);
114       if (SynthesizedBody) {
115         Body = SynthesizedBody;
116         IsAutosynthesized = true;
117       }
118     }
119     return Body;
120   } else if (const BlockDecl *BD = dyn_cast<BlockDecl>(D))
121     return BD->getBody();
122   else if (const FunctionTemplateDecl *FunTmpl
123            = dyn_cast_or_null<FunctionTemplateDecl>(D))
124     return FunTmpl->getTemplatedDecl()->getBody();
125 
126   llvm_unreachable("unknown code decl");
127 }
128 
129 Stmt *AnalysisDeclContext::getBody() const {
130   bool Tmp;
131   return getBody(Tmp);
132 }
133 
134 bool AnalysisDeclContext::isBodyAutosynthesized() const {
135   bool Tmp;
136   getBody(Tmp);
137   return Tmp;
138 }
139 
140 bool AnalysisDeclContext::isBodyAutosynthesizedFromModelFile() const {
141   bool Tmp;
142   Stmt *Body = getBody(Tmp);
143   return Tmp && Body->getLocStart().isValid();
144 }
145 
146 /// Returns true if \param VD is an Objective-C implicit 'self' parameter.
147 static bool isSelfDecl(const VarDecl *VD) {
148   return isa<ImplicitParamDecl>(VD) && VD->getName() == "self";
149 }
150 
151 const ImplicitParamDecl *AnalysisDeclContext::getSelfDecl() const {
152   if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D))
153     return MD->getSelfDecl();
154   if (const BlockDecl *BD = dyn_cast<BlockDecl>(D)) {
155     // See if 'self' was captured by the block.
156     for (const auto &I : BD->captures()) {
157       const VarDecl *VD = I.getVariable();
158       if (isSelfDecl(VD))
159         return dyn_cast<ImplicitParamDecl>(VD);
160     }
161   }
162 
163   auto *CXXMethod = dyn_cast<CXXMethodDecl>(D);
164   if (!CXXMethod)
165     return nullptr;
166 
167   const CXXRecordDecl *parent = CXXMethod->getParent();
168   if (!parent->isLambda())
169     return nullptr;
170 
171   for (const LambdaCapture &LC : parent->captures()) {
172     if (!LC.capturesVariable())
173       continue;
174 
175     VarDecl *VD = LC.getCapturedVar();
176     if (isSelfDecl(VD))
177       return dyn_cast<ImplicitParamDecl>(VD);
178   }
179 
180   return nullptr;
181 }
182 
183 void AnalysisDeclContext::registerForcedBlockExpression(const Stmt *stmt) {
184   if (!forcedBlkExprs)
185     forcedBlkExprs = new CFG::BuildOptions::ForcedBlkExprs();
186   // Default construct an entry for 'stmt'.
187   if (const Expr *e = dyn_cast<Expr>(stmt))
188     stmt = e->IgnoreParens();
189   (void) (*forcedBlkExprs)[stmt];
190 }
191 
192 const CFGBlock *
193 AnalysisDeclContext::getBlockForRegisteredExpression(const Stmt *stmt) {
194   assert(forcedBlkExprs);
195   if (const Expr *e = dyn_cast<Expr>(stmt))
196     stmt = e->IgnoreParens();
197   CFG::BuildOptions::ForcedBlkExprs::const_iterator itr =
198     forcedBlkExprs->find(stmt);
199   assert(itr != forcedBlkExprs->end());
200   return itr->second;
201 }
202 
203 /// Add each synthetic statement in the CFG to the parent map, using the
204 /// source statement's parent.
205 static void addParentsForSyntheticStmts(const CFG *TheCFG, ParentMap &PM) {
206   if (!TheCFG)
207     return;
208 
209   for (CFG::synthetic_stmt_iterator I = TheCFG->synthetic_stmt_begin(),
210                                     E = TheCFG->synthetic_stmt_end();
211        I != E; ++I) {
212     PM.setParent(I->first, PM.getParent(I->second));
213   }
214 }
215 
216 CFG *AnalysisDeclContext::getCFG() {
217   if (!cfgBuildOptions.PruneTriviallyFalseEdges)
218     return getUnoptimizedCFG();
219 
220   if (!builtCFG) {
221     cfg = CFG::buildCFG(D, getBody(), &D->getASTContext(), cfgBuildOptions);
222     // Even when the cfg is not successfully built, we don't
223     // want to try building it again.
224     builtCFG = true;
225 
226     if (PM)
227       addParentsForSyntheticStmts(cfg.get(), *PM);
228 
229     // The Observer should only observe one build of the CFG.
230     getCFGBuildOptions().Observer = nullptr;
231   }
232   return cfg.get();
233 }
234 
235 CFG *AnalysisDeclContext::getUnoptimizedCFG() {
236   if (!builtCompleteCFG) {
237     SaveAndRestore<bool> NotPrune(cfgBuildOptions.PruneTriviallyFalseEdges,
238                                   false);
239     completeCFG =
240         CFG::buildCFG(D, getBody(), &D->getASTContext(), cfgBuildOptions);
241     // Even when the cfg is not successfully built, we don't
242     // want to try building it again.
243     builtCompleteCFG = true;
244 
245     if (PM)
246       addParentsForSyntheticStmts(completeCFG.get(), *PM);
247 
248     // The Observer should only observe one build of the CFG.
249     getCFGBuildOptions().Observer = nullptr;
250   }
251   return completeCFG.get();
252 }
253 
254 CFGStmtMap *AnalysisDeclContext::getCFGStmtMap() {
255   if (cfgStmtMap)
256     return cfgStmtMap.get();
257 
258   if (CFG *c = getCFG()) {
259     cfgStmtMap.reset(CFGStmtMap::Build(c, &getParentMap()));
260     return cfgStmtMap.get();
261   }
262 
263   return nullptr;
264 }
265 
266 CFGReverseBlockReachabilityAnalysis *AnalysisDeclContext::getCFGReachablityAnalysis() {
267   if (CFA)
268     return CFA.get();
269 
270   if (CFG *c = getCFG()) {
271     CFA.reset(new CFGReverseBlockReachabilityAnalysis(*c));
272     return CFA.get();
273   }
274 
275   return nullptr;
276 }
277 
278 void AnalysisDeclContext::dumpCFG(bool ShowColors) {
279     getCFG()->dump(getASTContext().getLangOpts(), ShowColors);
280 }
281 
282 ParentMap &AnalysisDeclContext::getParentMap() {
283   if (!PM) {
284     PM.reset(new ParentMap(getBody()));
285     if (const CXXConstructorDecl *C = dyn_cast<CXXConstructorDecl>(getDecl())) {
286       for (const auto *I : C->inits()) {
287         PM->addStmt(I->getInit());
288       }
289     }
290     if (builtCFG)
291       addParentsForSyntheticStmts(getCFG(), *PM);
292     if (builtCompleteCFG)
293       addParentsForSyntheticStmts(getUnoptimizedCFG(), *PM);
294   }
295   return *PM;
296 }
297 
298 PseudoConstantAnalysis *AnalysisDeclContext::getPseudoConstantAnalysis() {
299   if (!PCA)
300     PCA.reset(new PseudoConstantAnalysis(getBody()));
301   return PCA.get();
302 }
303 
304 AnalysisDeclContext *AnalysisDeclContextManager::getContext(const Decl *D) {
305   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
306     // Calling 'hasBody' replaces 'FD' in place with the FunctionDecl
307     // that has the body.
308     FD->hasBody(FD);
309     D = FD;
310   }
311 
312   std::unique_ptr<AnalysisDeclContext> &AC = Contexts[D];
313   if (!AC)
314     AC = llvm::make_unique<AnalysisDeclContext>(this, D, cfgBuildOptions);
315   return AC.get();
316 }
317 
318 const StackFrameContext *
319 AnalysisDeclContext::getStackFrame(LocationContext const *Parent, const Stmt *S,
320                                const CFGBlock *Blk, unsigned Idx) {
321   return getLocationContextManager().getStackFrame(this, Parent, S, Blk, Idx);
322 }
323 
324 const BlockInvocationContext *
325 AnalysisDeclContext::getBlockInvocationContext(const LocationContext *parent,
326                                                const clang::BlockDecl *BD,
327                                                const void *ContextData) {
328   return getLocationContextManager().getBlockInvocationContext(this, parent,
329                                                                BD, ContextData);
330 }
331 
332 bool AnalysisDeclContext::isInStdNamespace(const Decl *D) {
333   const DeclContext *DC = D->getDeclContext()->getEnclosingNamespaceContext();
334   const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC);
335   if (!ND)
336     return false;
337 
338   while (const DeclContext *Parent = ND->getParent()) {
339     if (!isa<NamespaceDecl>(Parent))
340       break;
341     ND = cast<NamespaceDecl>(Parent);
342   }
343 
344   return ND->isStdNamespace();
345 }
346 
347 LocationContextManager & AnalysisDeclContext::getLocationContextManager() {
348   assert(Manager &&
349          "Cannot create LocationContexts without an AnalysisDeclContextManager!");
350   return Manager->getLocationContextManager();
351 }
352 
353 //===----------------------------------------------------------------------===//
354 // FoldingSet profiling.
355 //===----------------------------------------------------------------------===//
356 
357 void LocationContext::ProfileCommon(llvm::FoldingSetNodeID &ID,
358                                     ContextKind ck,
359                                     AnalysisDeclContext *ctx,
360                                     const LocationContext *parent,
361                                     const void *data) {
362   ID.AddInteger(ck);
363   ID.AddPointer(ctx);
364   ID.AddPointer(parent);
365   ID.AddPointer(data);
366 }
367 
368 void StackFrameContext::Profile(llvm::FoldingSetNodeID &ID) {
369   Profile(ID, getAnalysisDeclContext(), getParent(), CallSite, Block, Index);
370 }
371 
372 void ScopeContext::Profile(llvm::FoldingSetNodeID &ID) {
373   Profile(ID, getAnalysisDeclContext(), getParent(), Enter);
374 }
375 
376 void BlockInvocationContext::Profile(llvm::FoldingSetNodeID &ID) {
377   Profile(ID, getAnalysisDeclContext(), getParent(), BD, ContextData);
378 }
379 
380 //===----------------------------------------------------------------------===//
381 // LocationContext creation.
382 //===----------------------------------------------------------------------===//
383 
384 template <typename LOC, typename DATA>
385 const LOC*
386 LocationContextManager::getLocationContext(AnalysisDeclContext *ctx,
387                                            const LocationContext *parent,
388                                            const DATA *d) {
389   llvm::FoldingSetNodeID ID;
390   LOC::Profile(ID, ctx, parent, d);
391   void *InsertPos;
392 
393   LOC *L = cast_or_null<LOC>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
394 
395   if (!L) {
396     L = new LOC(ctx, parent, d);
397     Contexts.InsertNode(L, InsertPos);
398   }
399   return L;
400 }
401 
402 const StackFrameContext*
403 LocationContextManager::getStackFrame(AnalysisDeclContext *ctx,
404                                       const LocationContext *parent,
405                                       const Stmt *s,
406                                       const CFGBlock *blk, unsigned idx) {
407   llvm::FoldingSetNodeID ID;
408   StackFrameContext::Profile(ID, ctx, parent, s, blk, idx);
409   void *InsertPos;
410   StackFrameContext *L =
411    cast_or_null<StackFrameContext>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
412   if (!L) {
413     L = new StackFrameContext(ctx, parent, s, blk, idx);
414     Contexts.InsertNode(L, InsertPos);
415   }
416   return L;
417 }
418 
419 const ScopeContext *
420 LocationContextManager::getScope(AnalysisDeclContext *ctx,
421                                  const LocationContext *parent,
422                                  const Stmt *s) {
423   return getLocationContext<ScopeContext, Stmt>(ctx, parent, s);
424 }
425 
426 const BlockInvocationContext *
427 LocationContextManager::getBlockInvocationContext(AnalysisDeclContext *ctx,
428                                                   const LocationContext *parent,
429                                                   const BlockDecl *BD,
430                                                   const void *ContextData) {
431   llvm::FoldingSetNodeID ID;
432   BlockInvocationContext::Profile(ID, ctx, parent, BD, ContextData);
433   void *InsertPos;
434   BlockInvocationContext *L =
435     cast_or_null<BlockInvocationContext>(Contexts.FindNodeOrInsertPos(ID,
436                                                                     InsertPos));
437   if (!L) {
438     L = new BlockInvocationContext(ctx, parent, BD, ContextData);
439     Contexts.InsertNode(L, InsertPos);
440   }
441   return L;
442 }
443 
444 //===----------------------------------------------------------------------===//
445 // LocationContext methods.
446 //===----------------------------------------------------------------------===//
447 
448 const StackFrameContext *LocationContext::getCurrentStackFrame() const {
449   const LocationContext *LC = this;
450   while (LC) {
451     if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LC))
452       return SFC;
453     LC = LC->getParent();
454   }
455   return nullptr;
456 }
457 
458 bool LocationContext::inTopFrame() const {
459   return getCurrentStackFrame()->inTopFrame();
460 }
461 
462 bool LocationContext::isParentOf(const LocationContext *LC) const {
463   do {
464     const LocationContext *Parent = LC->getParent();
465     if (Parent == this)
466       return true;
467     else
468       LC = Parent;
469   } while (LC);
470 
471   return false;
472 }
473 
474 void LocationContext::dumpStack(raw_ostream &OS, StringRef Indent) const {
475   ASTContext &Ctx = getAnalysisDeclContext()->getASTContext();
476   PrintingPolicy PP(Ctx.getLangOpts());
477   PP.TerseOutput = 1;
478 
479   unsigned Frame = 0;
480   for (const LocationContext *LCtx = this; LCtx; LCtx = LCtx->getParent()) {
481     switch (LCtx->getKind()) {
482     case StackFrame:
483       OS << Indent << '#' << Frame++ << ' ';
484       cast<StackFrameContext>(LCtx)->getDecl()->print(OS, PP);
485       OS << '\n';
486       break;
487     case Scope:
488       OS << Indent << "    (scope)\n";
489       break;
490     case Block:
491       OS << Indent << "    (block context: "
492                    << cast<BlockInvocationContext>(LCtx)->getContextData()
493                    << ")\n";
494       break;
495     }
496   }
497 }
498 
499 LLVM_DUMP_METHOD void LocationContext::dumpStack() const {
500   dumpStack(llvm::errs());
501 }
502 
503 //===----------------------------------------------------------------------===//
504 // Lazily generated map to query the external variables referenced by a Block.
505 //===----------------------------------------------------------------------===//
506 
507 namespace {
508 class FindBlockDeclRefExprsVals : public StmtVisitor<FindBlockDeclRefExprsVals>{
509   BumpVector<const VarDecl*> &BEVals;
510   BumpVectorContext &BC;
511   llvm::SmallPtrSet<const VarDecl*, 4> Visited;
512   llvm::SmallPtrSet<const DeclContext*, 4> IgnoredContexts;
513 public:
514   FindBlockDeclRefExprsVals(BumpVector<const VarDecl*> &bevals,
515                             BumpVectorContext &bc)
516   : BEVals(bevals), BC(bc) {}
517 
518   void VisitStmt(Stmt *S) {
519     for (Stmt *Child : S->children())
520       if (Child)
521         Visit(Child);
522   }
523 
524   void VisitDeclRefExpr(DeclRefExpr *DR) {
525     // Non-local variables are also directly modified.
526     if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
527       if (!VD->hasLocalStorage()) {
528         if (Visited.insert(VD).second)
529           BEVals.push_back(VD, BC);
530       }
531     }
532   }
533 
534   void VisitBlockExpr(BlockExpr *BR) {
535     // Blocks containing blocks can transitively capture more variables.
536     IgnoredContexts.insert(BR->getBlockDecl());
537     Visit(BR->getBlockDecl()->getBody());
538   }
539 
540   void VisitPseudoObjectExpr(PseudoObjectExpr *PE) {
541     for (PseudoObjectExpr::semantics_iterator it = PE->semantics_begin(),
542          et = PE->semantics_end(); it != et; ++it) {
543       Expr *Semantic = *it;
544       if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(Semantic))
545         Semantic = OVE->getSourceExpr();
546       Visit(Semantic);
547     }
548   }
549 };
550 } // end anonymous namespace
551 
552 typedef BumpVector<const VarDecl*> DeclVec;
553 
554 static DeclVec* LazyInitializeReferencedDecls(const BlockDecl *BD,
555                                               void *&Vec,
556                                               llvm::BumpPtrAllocator &A) {
557   if (Vec)
558     return (DeclVec*) Vec;
559 
560   BumpVectorContext BC(A);
561   DeclVec *BV = (DeclVec*) A.Allocate<DeclVec>();
562   new (BV) DeclVec(BC, 10);
563 
564   // Go through the capture list.
565   for (const auto &CI : BD->captures()) {
566     BV->push_back(CI.getVariable(), BC);
567   }
568 
569   // Find the referenced global/static variables.
570   FindBlockDeclRefExprsVals F(*BV, BC);
571   F.Visit(BD->getBody());
572 
573   Vec = BV;
574   return BV;
575 }
576 
577 llvm::iterator_range<AnalysisDeclContext::referenced_decls_iterator>
578 AnalysisDeclContext::getReferencedBlockVars(const BlockDecl *BD) {
579   if (!ReferencedBlockVars)
580     ReferencedBlockVars = new llvm::DenseMap<const BlockDecl*,void*>();
581 
582   const DeclVec *V =
583       LazyInitializeReferencedDecls(BD, (*ReferencedBlockVars)[BD], A);
584   return llvm::make_range(V->begin(), V->end());
585 }
586 
587 ManagedAnalysis *&AnalysisDeclContext::getAnalysisImpl(const void *tag) {
588   if (!ManagedAnalyses)
589     ManagedAnalyses = new ManagedAnalysisMap();
590   ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
591   return (*M)[tag];
592 }
593 
594 //===----------------------------------------------------------------------===//
595 // Cleanup.
596 //===----------------------------------------------------------------------===//
597 
598 ManagedAnalysis::~ManagedAnalysis() {}
599 
600 AnalysisDeclContext::~AnalysisDeclContext() {
601   delete forcedBlkExprs;
602   delete ReferencedBlockVars;
603   // Release the managed analyses.
604   if (ManagedAnalyses) {
605     ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
606     llvm::DeleteContainerSeconds(*M);
607     delete M;
608   }
609 }
610 
611 AnalysisDeclContextManager::~AnalysisDeclContextManager() {}
612 
613 LocationContext::~LocationContext() {}
614 
615 LocationContextManager::~LocationContextManager() {
616   clear();
617 }
618 
619 void LocationContextManager::clear() {
620   for (llvm::FoldingSet<LocationContext>::iterator I = Contexts.begin(),
621        E = Contexts.end(); I != E; ) {
622     LocationContext *LC = &*I;
623     ++I;
624     delete LC;
625   }
626 
627   Contexts.clear();
628 }
629 
630