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