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 CFG *AnalysisDeclContext::getCFG() {
161   if (!cfgBuildOptions.PruneTriviallyFalseEdges)
162     return getUnoptimizedCFG();
163 
164   if (!builtCFG) {
165     cfg.reset(CFG::buildCFG(D, getBody(),
166                             &D->getASTContext(), cfgBuildOptions));
167     // Even when the cfg is not successfully built, we don't
168     // want to try building it again.
169     builtCFG = true;
170   }
171   return cfg.get();
172 }
173 
174 CFG *AnalysisDeclContext::getUnoptimizedCFG() {
175   if (!builtCompleteCFG) {
176     SaveAndRestore<bool> NotPrune(cfgBuildOptions.PruneTriviallyFalseEdges,
177                                   false);
178     completeCFG.reset(CFG::buildCFG(D, getBody(), &D->getASTContext(),
179                                     cfgBuildOptions));
180     // Even when the cfg is not successfully built, we don't
181     // want to try building it again.
182     builtCompleteCFG = true;
183   }
184   return completeCFG.get();
185 }
186 
187 CFGStmtMap *AnalysisDeclContext::getCFGStmtMap() {
188   if (cfgStmtMap)
189     return cfgStmtMap.get();
190 
191   if (CFG *c = getCFG()) {
192     cfgStmtMap.reset(CFGStmtMap::Build(c, &getParentMap()));
193     return cfgStmtMap.get();
194   }
195 
196   return 0;
197 }
198 
199 CFGReverseBlockReachabilityAnalysis *AnalysisDeclContext::getCFGReachablityAnalysis() {
200   if (CFA)
201     return CFA.get();
202 
203   if (CFG *c = getCFG()) {
204     CFA.reset(new CFGReverseBlockReachabilityAnalysis(*c));
205     return CFA.get();
206   }
207 
208   return 0;
209 }
210 
211 void AnalysisDeclContext::dumpCFG(bool ShowColors) {
212     getCFG()->dump(getASTContext().getLangOpts(), ShowColors);
213 }
214 
215 ParentMap &AnalysisDeclContext::getParentMap() {
216   if (!PM) {
217     PM.reset(new ParentMap(getBody()));
218     if (const CXXConstructorDecl *C = dyn_cast<CXXConstructorDecl>(getDecl())) {
219       for (CXXConstructorDecl::init_const_iterator I = C->init_begin(),
220                                                    E = C->init_end();
221            I != E; ++I) {
222         PM->addStmt((*I)->getInit());
223       }
224     }
225   }
226   return *PM;
227 }
228 
229 PseudoConstantAnalysis *AnalysisDeclContext::getPseudoConstantAnalysis() {
230   if (!PCA)
231     PCA.reset(new PseudoConstantAnalysis(getBody()));
232   return PCA.get();
233 }
234 
235 AnalysisDeclContext *AnalysisDeclContextManager::getContext(const Decl *D) {
236   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
237     // Calling 'hasBody' replaces 'FD' in place with the FunctionDecl
238     // that has the body.
239     FD->hasBody(FD);
240     D = FD;
241   }
242 
243   AnalysisDeclContext *&AC = Contexts[D];
244   if (!AC)
245     AC = new AnalysisDeclContext(this, D, cfgBuildOptions);
246   return AC;
247 }
248 
249 const StackFrameContext *
250 AnalysisDeclContext::getStackFrame(LocationContext const *Parent, const Stmt *S,
251                                const CFGBlock *Blk, unsigned Idx) {
252   return getLocationContextManager().getStackFrame(this, Parent, S, Blk, Idx);
253 }
254 
255 const BlockInvocationContext *
256 AnalysisDeclContext::getBlockInvocationContext(const LocationContext *parent,
257                                                const clang::BlockDecl *BD,
258                                                const void *ContextData) {
259   return getLocationContextManager().getBlockInvocationContext(this, parent,
260                                                                BD, ContextData);
261 }
262 
263 LocationContextManager & AnalysisDeclContext::getLocationContextManager() {
264   assert(Manager &&
265          "Cannot create LocationContexts without an AnalysisDeclContextManager!");
266   return Manager->getLocationContextManager();
267 }
268 
269 //===----------------------------------------------------------------------===//
270 // FoldingSet profiling.
271 //===----------------------------------------------------------------------===//
272 
273 void LocationContext::ProfileCommon(llvm::FoldingSetNodeID &ID,
274                                     ContextKind ck,
275                                     AnalysisDeclContext *ctx,
276                                     const LocationContext *parent,
277                                     const void *data) {
278   ID.AddInteger(ck);
279   ID.AddPointer(ctx);
280   ID.AddPointer(parent);
281   ID.AddPointer(data);
282 }
283 
284 void StackFrameContext::Profile(llvm::FoldingSetNodeID &ID) {
285   Profile(ID, getAnalysisDeclContext(), getParent(), CallSite, Block, Index);
286 }
287 
288 void ScopeContext::Profile(llvm::FoldingSetNodeID &ID) {
289   Profile(ID, getAnalysisDeclContext(), getParent(), Enter);
290 }
291 
292 void BlockInvocationContext::Profile(llvm::FoldingSetNodeID &ID) {
293   Profile(ID, getAnalysisDeclContext(), getParent(), BD, ContextData);
294 }
295 
296 //===----------------------------------------------------------------------===//
297 // LocationContext creation.
298 //===----------------------------------------------------------------------===//
299 
300 template <typename LOC, typename DATA>
301 const LOC*
302 LocationContextManager::getLocationContext(AnalysisDeclContext *ctx,
303                                            const LocationContext *parent,
304                                            const DATA *d) {
305   llvm::FoldingSetNodeID ID;
306   LOC::Profile(ID, ctx, parent, d);
307   void *InsertPos;
308 
309   LOC *L = cast_or_null<LOC>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
310 
311   if (!L) {
312     L = new LOC(ctx, parent, d);
313     Contexts.InsertNode(L, InsertPos);
314   }
315   return L;
316 }
317 
318 const StackFrameContext*
319 LocationContextManager::getStackFrame(AnalysisDeclContext *ctx,
320                                       const LocationContext *parent,
321                                       const Stmt *s,
322                                       const CFGBlock *blk, unsigned idx) {
323   llvm::FoldingSetNodeID ID;
324   StackFrameContext::Profile(ID, ctx, parent, s, blk, idx);
325   void *InsertPos;
326   StackFrameContext *L =
327    cast_or_null<StackFrameContext>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
328   if (!L) {
329     L = new StackFrameContext(ctx, parent, s, blk, idx);
330     Contexts.InsertNode(L, InsertPos);
331   }
332   return L;
333 }
334 
335 const ScopeContext *
336 LocationContextManager::getScope(AnalysisDeclContext *ctx,
337                                  const LocationContext *parent,
338                                  const Stmt *s) {
339   return getLocationContext<ScopeContext, Stmt>(ctx, parent, s);
340 }
341 
342 const BlockInvocationContext *
343 LocationContextManager::getBlockInvocationContext(AnalysisDeclContext *ctx,
344                                                   const LocationContext *parent,
345                                                   const BlockDecl *BD,
346                                                   const void *ContextData) {
347   llvm::FoldingSetNodeID ID;
348   BlockInvocationContext::Profile(ID, ctx, parent, BD, ContextData);
349   void *InsertPos;
350   BlockInvocationContext *L =
351     cast_or_null<BlockInvocationContext>(Contexts.FindNodeOrInsertPos(ID,
352                                                                     InsertPos));
353   if (!L) {
354     L = new BlockInvocationContext(ctx, parent, BD, ContextData);
355     Contexts.InsertNode(L, InsertPos);
356   }
357   return L;
358 }
359 
360 //===----------------------------------------------------------------------===//
361 // LocationContext methods.
362 //===----------------------------------------------------------------------===//
363 
364 const StackFrameContext *LocationContext::getCurrentStackFrame() const {
365   const LocationContext *LC = this;
366   while (LC) {
367     if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LC))
368       return SFC;
369     LC = LC->getParent();
370   }
371   return NULL;
372 }
373 
374 bool LocationContext::inTopFrame() const {
375   return getCurrentStackFrame()->inTopFrame();
376 }
377 
378 bool LocationContext::isParentOf(const LocationContext *LC) const {
379   do {
380     const LocationContext *Parent = LC->getParent();
381     if (Parent == this)
382       return true;
383     else
384       LC = Parent;
385   } while (LC);
386 
387   return false;
388 }
389 
390 void LocationContext::dumpStack() const {
391   ASTContext &Ctx = getAnalysisDeclContext()->getASTContext();
392   PrintingPolicy PP(Ctx.getLangOpts());
393   PP.TerseOutput = 1;
394 
395   unsigned Frame = 0;
396   for (const LocationContext *LCtx = this; LCtx; LCtx = LCtx->getParent()) {
397     switch (LCtx->getKind()) {
398     case StackFrame:
399       llvm::errs() << '#' << Frame++ << ' ';
400       cast<StackFrameContext>(LCtx)->getDecl()->print(llvm::errs(), PP);
401       llvm::errs() << '\n';
402       break;
403     case Scope:
404       llvm::errs() << "    (scope)\n";
405       break;
406     case Block:
407       llvm::errs() << "    (block context: "
408                    << cast<BlockInvocationContext>(LCtx)->getContextData()
409                    << ")\n";
410       break;
411     }
412   }
413 }
414 
415 //===----------------------------------------------------------------------===//
416 // Lazily generated map to query the external variables referenced by a Block.
417 //===----------------------------------------------------------------------===//
418 
419 namespace {
420 class FindBlockDeclRefExprsVals : public StmtVisitor<FindBlockDeclRefExprsVals>{
421   BumpVector<const VarDecl*> &BEVals;
422   BumpVectorContext &BC;
423   llvm::SmallPtrSet<const VarDecl*, 4> Visited;
424   llvm::SmallPtrSet<const DeclContext*, 4> IgnoredContexts;
425 public:
426   FindBlockDeclRefExprsVals(BumpVector<const VarDecl*> &bevals,
427                             BumpVectorContext &bc)
428   : BEVals(bevals), BC(bc) {}
429 
430   bool IsTrackedDecl(const VarDecl *VD) {
431     const DeclContext *DC = VD->getDeclContext();
432     return IgnoredContexts.count(DC) == 0;
433   }
434 
435   void VisitStmt(Stmt *S) {
436     for (Stmt::child_range I = S->children(); I; ++I)
437       if (Stmt *child = *I)
438         Visit(child);
439   }
440 
441   void VisitDeclRefExpr(DeclRefExpr *DR) {
442     // Non-local variables are also directly modified.
443     if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
444       if (!VD->hasLocalStorage()) {
445         if (Visited.insert(VD))
446           BEVals.push_back(VD, BC);
447       }
448     }
449   }
450 
451   void VisitBlockExpr(BlockExpr *BR) {
452     // Blocks containing blocks can transitively capture more variables.
453     IgnoredContexts.insert(BR->getBlockDecl());
454     Visit(BR->getBlockDecl()->getBody());
455   }
456 
457   void VisitPseudoObjectExpr(PseudoObjectExpr *PE) {
458     for (PseudoObjectExpr::semantics_iterator it = PE->semantics_begin(),
459          et = PE->semantics_end(); it != et; ++it) {
460       Expr *Semantic = *it;
461       if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(Semantic))
462         Semantic = OVE->getSourceExpr();
463       Visit(Semantic);
464     }
465   }
466 };
467 } // end anonymous namespace
468 
469 typedef BumpVector<const VarDecl*> DeclVec;
470 
471 static DeclVec* LazyInitializeReferencedDecls(const BlockDecl *BD,
472                                               void *&Vec,
473                                               llvm::BumpPtrAllocator &A) {
474   if (Vec)
475     return (DeclVec*) Vec;
476 
477   BumpVectorContext BC(A);
478   DeclVec *BV = (DeclVec*) A.Allocate<DeclVec>();
479   new (BV) DeclVec(BC, 10);
480 
481   // Go through the capture list.
482   for (BlockDecl::capture_const_iterator CI = BD->capture_begin(),
483        CE = BD->capture_end(); CI != CE; ++CI) {
484     BV->push_back(CI->getVariable(), BC);
485   }
486 
487   // Find the referenced global/static variables.
488   FindBlockDeclRefExprsVals F(*BV, BC);
489   F.Visit(BD->getBody());
490 
491   Vec = BV;
492   return BV;
493 }
494 
495 std::pair<AnalysisDeclContext::referenced_decls_iterator,
496           AnalysisDeclContext::referenced_decls_iterator>
497 AnalysisDeclContext::getReferencedBlockVars(const BlockDecl *BD) {
498   if (!ReferencedBlockVars)
499     ReferencedBlockVars = new llvm::DenseMap<const BlockDecl*,void*>();
500 
501   DeclVec *V = LazyInitializeReferencedDecls(BD, (*ReferencedBlockVars)[BD], A);
502   return std::make_pair(V->begin(), V->end());
503 }
504 
505 ManagedAnalysis *&AnalysisDeclContext::getAnalysisImpl(const void *tag) {
506   if (!ManagedAnalyses)
507     ManagedAnalyses = new ManagedAnalysisMap();
508   ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
509   return (*M)[tag];
510 }
511 
512 //===----------------------------------------------------------------------===//
513 // Cleanup.
514 //===----------------------------------------------------------------------===//
515 
516 ManagedAnalysis::~ManagedAnalysis() {}
517 
518 AnalysisDeclContext::~AnalysisDeclContext() {
519   delete forcedBlkExprs;
520   delete ReferencedBlockVars;
521   // Release the managed analyses.
522   if (ManagedAnalyses) {
523     ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
524     for (ManagedAnalysisMap::iterator I = M->begin(), E = M->end(); I!=E; ++I)
525       delete I->second;
526     delete M;
527   }
528 }
529 
530 AnalysisDeclContextManager::~AnalysisDeclContextManager() {
531   for (ContextMap::iterator I = Contexts.begin(), E = Contexts.end(); I!=E; ++I)
532     delete I->second;
533 }
534 
535 LocationContext::~LocationContext() {}
536 
537 LocationContextManager::~LocationContextManager() {
538   clear();
539 }
540 
541 void LocationContextManager::clear() {
542   for (llvm::FoldingSet<LocationContext>::iterator I = Contexts.begin(),
543        E = Contexts.end(); I != E; ) {
544     LocationContext *LC = &*I;
545     ++I;
546     delete LC;
547   }
548 
549   Contexts.clear();
550 }
551 
552