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/AST/ASTContext.h"
16 #include "clang/AST/Decl.h"
17 #include "clang/AST/DeclObjC.h"
18 #include "clang/AST/DeclTemplate.h"
19 #include "clang/AST/ParentMap.h"
20 #include "clang/AST/StmtVisitor.h"
21 #include "clang/Analysis/Analyses/LiveVariables.h"
22 #include "clang/Analysis/Analyses/PseudoConstantAnalysis.h"
23 #include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
24 #include "clang/Analysis/AnalysisContext.h"
25 #include "clang/Analysis/CFG.h"
26 #include "clang/Analysis/CFGStmtMap.h"
27 #include "clang/Analysis/Support/BumpVector.h"
28 #include "llvm/Support/SaveAndRestore.h"
29 #include "llvm/ADT/SmallPtrSet.h"
30 #include "llvm/Support/ErrorHandling.h"
31 
32 using namespace clang;
33 
34 typedef llvm::DenseMap<const void *, ManagedAnalysis *> ManagedAnalysisMap;
35 
36 AnalysisDeclContext::AnalysisDeclContext(AnalysisDeclContextManager *Mgr,
37                                  const Decl *d,
38                                  const CFG::BuildOptions &buildOptions)
39   : Manager(Mgr),
40     D(d),
41     cfgBuildOptions(buildOptions),
42     forcedBlkExprs(0),
43     builtCFG(false),
44     builtCompleteCFG(false),
45     ReferencedBlockVars(0),
46     ManagedAnalyses(0)
47 {
48   cfgBuildOptions.forcedBlkExprs = &forcedBlkExprs;
49 }
50 
51 AnalysisDeclContext::AnalysisDeclContext(AnalysisDeclContextManager *Mgr,
52                                  const Decl *d)
53 : Manager(Mgr),
54   D(d),
55   forcedBlkExprs(0),
56   builtCFG(false),
57   builtCompleteCFG(false),
58   ReferencedBlockVars(0),
59   ManagedAnalyses(0)
60 {
61   cfgBuildOptions.forcedBlkExprs = &forcedBlkExprs;
62 }
63 
64 AnalysisDeclContextManager::AnalysisDeclContextManager(bool useUnoptimizedCFG,
65                                                bool addImplicitDtors,
66                                                bool addInitializers) {
67   cfgBuildOptions.PruneTriviallyFalseEdges = !useUnoptimizedCFG;
68   cfgBuildOptions.AddImplicitDtors = addImplicitDtors;
69   cfgBuildOptions.AddInitializers = addInitializers;
70 }
71 
72 void AnalysisDeclContextManager::clear() {
73   for (ContextMap::iterator I = Contexts.begin(), E = Contexts.end(); I!=E; ++I)
74     delete I->second;
75   Contexts.clear();
76 }
77 
78 Stmt *AnalysisDeclContext::getBody() const {
79   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
80     return FD->getBody();
81   else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D))
82     return MD->getBody();
83   else if (const BlockDecl *BD = dyn_cast<BlockDecl>(D))
84     return BD->getBody();
85   else if (const FunctionTemplateDecl *FunTmpl
86            = dyn_cast_or_null<FunctionTemplateDecl>(D))
87     return FunTmpl->getTemplatedDecl()->getBody();
88 
89   llvm_unreachable("unknown code decl");
90 }
91 
92 const ImplicitParamDecl *AnalysisDeclContext::getSelfDecl() const {
93   if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D))
94     return MD->getSelfDecl();
95   if (const BlockDecl *BD = dyn_cast<BlockDecl>(D)) {
96     // See if 'self' was captured by the block.
97     for (BlockDecl::capture_const_iterator it = BD->capture_begin(),
98          et = BD->capture_end(); it != et; ++it) {
99       const VarDecl *VD = it->getVariable();
100       if (VD->getName() == "self")
101         return dyn_cast<ImplicitParamDecl>(VD);
102     }
103   }
104 
105   return NULL;
106 }
107 
108 void AnalysisDeclContext::registerForcedBlockExpression(const Stmt *stmt) {
109   if (!forcedBlkExprs)
110     forcedBlkExprs = new CFG::BuildOptions::ForcedBlkExprs();
111   // Default construct an entry for 'stmt'.
112   if (const Expr *e = dyn_cast<Expr>(stmt))
113     stmt = e->IgnoreParens();
114   (void) (*forcedBlkExprs)[stmt];
115 }
116 
117 const CFGBlock *
118 AnalysisDeclContext::getBlockForRegisteredExpression(const Stmt *stmt) {
119   assert(forcedBlkExprs);
120   if (const Expr *e = dyn_cast<Expr>(stmt))
121     stmt = e->IgnoreParens();
122   CFG::BuildOptions::ForcedBlkExprs::const_iterator itr =
123     forcedBlkExprs->find(stmt);
124   assert(itr != forcedBlkExprs->end());
125   return itr->second;
126 }
127 
128 CFG *AnalysisDeclContext::getCFG() {
129   if (!cfgBuildOptions.PruneTriviallyFalseEdges)
130     return getUnoptimizedCFG();
131 
132   if (!builtCFG) {
133     cfg.reset(CFG::buildCFG(D, getBody(),
134                             &D->getASTContext(), cfgBuildOptions));
135     // Even when the cfg is not successfully built, we don't
136     // want to try building it again.
137     builtCFG = true;
138   }
139   return cfg.get();
140 }
141 
142 CFG *AnalysisDeclContext::getUnoptimizedCFG() {
143   if (!builtCompleteCFG) {
144     SaveAndRestore<bool> NotPrune(cfgBuildOptions.PruneTriviallyFalseEdges,
145                                   false);
146     completeCFG.reset(CFG::buildCFG(D, getBody(), &D->getASTContext(),
147                                     cfgBuildOptions));
148     // Even when the cfg is not successfully built, we don't
149     // want to try building it again.
150     builtCompleteCFG = true;
151   }
152   return completeCFG.get();
153 }
154 
155 CFGStmtMap *AnalysisDeclContext::getCFGStmtMap() {
156   if (cfgStmtMap)
157     return cfgStmtMap.get();
158 
159   if (CFG *c = getCFG()) {
160     cfgStmtMap.reset(CFGStmtMap::Build(c, &getParentMap()));
161     return cfgStmtMap.get();
162   }
163 
164   return 0;
165 }
166 
167 CFGReverseBlockReachabilityAnalysis *AnalysisDeclContext::getCFGReachablityAnalysis() {
168   if (CFA)
169     return CFA.get();
170 
171   if (CFG *c = getCFG()) {
172     CFA.reset(new CFGReverseBlockReachabilityAnalysis(*c));
173     return CFA.get();
174   }
175 
176   return 0;
177 }
178 
179 void AnalysisDeclContext::dumpCFG(bool ShowColors) {
180     getCFG()->dump(getASTContext().getLangOpts(), ShowColors);
181 }
182 
183 ParentMap &AnalysisDeclContext::getParentMap() {
184   if (!PM)
185     PM.reset(new ParentMap(getBody()));
186   return *PM;
187 }
188 
189 PseudoConstantAnalysis *AnalysisDeclContext::getPseudoConstantAnalysis() {
190   if (!PCA)
191     PCA.reset(new PseudoConstantAnalysis(getBody()));
192   return PCA.get();
193 }
194 
195 AnalysisDeclContext *AnalysisDeclContextManager::getContext(const Decl *D) {
196   AnalysisDeclContext *&AC = Contexts[D];
197   if (!AC)
198     AC = new AnalysisDeclContext(this, D, cfgBuildOptions);
199   return AC;
200 }
201 
202 const StackFrameContext *
203 AnalysisDeclContext::getStackFrame(LocationContext const *Parent, const Stmt *S,
204                                const CFGBlock *Blk, unsigned Idx) {
205   return getLocationContextManager().getStackFrame(this, Parent, S, Blk, Idx);
206 }
207 
208 const BlockInvocationContext *
209 AnalysisDeclContext::getBlockInvocationContext(const LocationContext *parent,
210                                                const clang::BlockDecl *BD,
211                                                const void *ContextData) {
212   return getLocationContextManager().getBlockInvocationContext(this, parent,
213                                                                BD, ContextData);
214 }
215 
216 LocationContextManager & AnalysisDeclContext::getLocationContextManager() {
217   assert(Manager &&
218          "Cannot create LocationContexts without an AnalysisDeclContextManager!");
219   return Manager->getLocationContextManager();
220 }
221 
222 //===----------------------------------------------------------------------===//
223 // FoldingSet profiling.
224 //===----------------------------------------------------------------------===//
225 
226 void LocationContext::ProfileCommon(llvm::FoldingSetNodeID &ID,
227                                     ContextKind ck,
228                                     AnalysisDeclContext *ctx,
229                                     const LocationContext *parent,
230                                     const void *data) {
231   ID.AddInteger(ck);
232   ID.AddPointer(ctx);
233   ID.AddPointer(parent);
234   ID.AddPointer(data);
235 }
236 
237 void StackFrameContext::Profile(llvm::FoldingSetNodeID &ID) {
238   Profile(ID, getAnalysisDeclContext(), getParent(), CallSite, Block, Index);
239 }
240 
241 void ScopeContext::Profile(llvm::FoldingSetNodeID &ID) {
242   Profile(ID, getAnalysisDeclContext(), getParent(), Enter);
243 }
244 
245 void BlockInvocationContext::Profile(llvm::FoldingSetNodeID &ID) {
246   Profile(ID, getAnalysisDeclContext(), getParent(), BD, ContextData);
247 }
248 
249 //===----------------------------------------------------------------------===//
250 // LocationContext creation.
251 //===----------------------------------------------------------------------===//
252 
253 template <typename LOC, typename DATA>
254 const LOC*
255 LocationContextManager::getLocationContext(AnalysisDeclContext *ctx,
256                                            const LocationContext *parent,
257                                            const DATA *d) {
258   llvm::FoldingSetNodeID ID;
259   LOC::Profile(ID, ctx, parent, d);
260   void *InsertPos;
261 
262   LOC *L = cast_or_null<LOC>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
263 
264   if (!L) {
265     L = new LOC(ctx, parent, d);
266     Contexts.InsertNode(L, InsertPos);
267   }
268   return L;
269 }
270 
271 const StackFrameContext*
272 LocationContextManager::getStackFrame(AnalysisDeclContext *ctx,
273                                       const LocationContext *parent,
274                                       const Stmt *s,
275                                       const CFGBlock *blk, unsigned idx) {
276   llvm::FoldingSetNodeID ID;
277   StackFrameContext::Profile(ID, ctx, parent, s, blk, idx);
278   void *InsertPos;
279   StackFrameContext *L =
280    cast_or_null<StackFrameContext>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
281   if (!L) {
282     L = new StackFrameContext(ctx, parent, s, blk, idx);
283     Contexts.InsertNode(L, InsertPos);
284   }
285   return L;
286 }
287 
288 const ScopeContext *
289 LocationContextManager::getScope(AnalysisDeclContext *ctx,
290                                  const LocationContext *parent,
291                                  const Stmt *s) {
292   return getLocationContext<ScopeContext, Stmt>(ctx, parent, s);
293 }
294 
295 const BlockInvocationContext *
296 LocationContextManager::getBlockInvocationContext(AnalysisDeclContext *ctx,
297                                                   const LocationContext *parent,
298                                                   const BlockDecl *BD,
299                                                   const void *ContextData) {
300   llvm::FoldingSetNodeID ID;
301   BlockInvocationContext::Profile(ID, ctx, parent, BD, ContextData);
302   void *InsertPos;
303   BlockInvocationContext *L =
304     cast_or_null<BlockInvocationContext>(Contexts.FindNodeOrInsertPos(ID,
305                                                                     InsertPos));
306   if (!L) {
307     L = new BlockInvocationContext(ctx, parent, BD, ContextData);
308     Contexts.InsertNode(L, InsertPos);
309   }
310   return L;
311 }
312 
313 //===----------------------------------------------------------------------===//
314 // LocationContext methods.
315 //===----------------------------------------------------------------------===//
316 
317 const StackFrameContext *LocationContext::getCurrentStackFrame() const {
318   const LocationContext *LC = this;
319   while (LC) {
320     if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LC))
321       return SFC;
322     LC = LC->getParent();
323   }
324   return NULL;
325 }
326 
327 bool LocationContext::isParentOf(const LocationContext *LC) const {
328   do {
329     const LocationContext *Parent = LC->getParent();
330     if (Parent == this)
331       return true;
332     else
333       LC = Parent;
334   } while (LC);
335 
336   return false;
337 }
338 
339 //===----------------------------------------------------------------------===//
340 // Lazily generated map to query the external variables referenced by a Block.
341 //===----------------------------------------------------------------------===//
342 
343 namespace {
344 class FindBlockDeclRefExprsVals : public StmtVisitor<FindBlockDeclRefExprsVals>{
345   BumpVector<const VarDecl*> &BEVals;
346   BumpVectorContext &BC;
347   llvm::SmallPtrSet<const VarDecl*, 4> Visited;
348   llvm::SmallPtrSet<const DeclContext*, 4> IgnoredContexts;
349 public:
350   FindBlockDeclRefExprsVals(BumpVector<const VarDecl*> &bevals,
351                             BumpVectorContext &bc)
352   : BEVals(bevals), BC(bc) {}
353 
354   bool IsTrackedDecl(const VarDecl *VD) {
355     const DeclContext *DC = VD->getDeclContext();
356     return IgnoredContexts.count(DC) == 0;
357   }
358 
359   void VisitStmt(Stmt *S) {
360     for (Stmt::child_range I = S->children(); I; ++I)
361       if (Stmt *child = *I)
362         Visit(child);
363   }
364 
365   void VisitDeclRefExpr(DeclRefExpr *DR) {
366     // Non-local variables are also directly modified.
367     if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
368       if (!VD->hasLocalStorage()) {
369         if (Visited.insert(VD))
370           BEVals.push_back(VD, BC);
371       } else if (DR->refersToEnclosingLocal()) {
372         if (Visited.insert(VD) && IsTrackedDecl(VD))
373           BEVals.push_back(VD, BC);
374       }
375     }
376   }
377 
378   void VisitBlockExpr(BlockExpr *BR) {
379     // Blocks containing blocks can transitively capture more variables.
380     IgnoredContexts.insert(BR->getBlockDecl());
381     Visit(BR->getBlockDecl()->getBody());
382   }
383 
384   void VisitPseudoObjectExpr(PseudoObjectExpr *PE) {
385     for (PseudoObjectExpr::semantics_iterator it = PE->semantics_begin(),
386          et = PE->semantics_end(); it != et; ++it) {
387       Expr *Semantic = *it;
388       if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(Semantic))
389         Semantic = OVE->getSourceExpr();
390       Visit(Semantic);
391     }
392   }
393 };
394 } // end anonymous namespace
395 
396 typedef BumpVector<const VarDecl*> DeclVec;
397 
398 static DeclVec* LazyInitializeReferencedDecls(const BlockDecl *BD,
399                                               void *&Vec,
400                                               llvm::BumpPtrAllocator &A) {
401   if (Vec)
402     return (DeclVec*) Vec;
403 
404   BumpVectorContext BC(A);
405   DeclVec *BV = (DeclVec*) A.Allocate<DeclVec>();
406   new (BV) DeclVec(BC, 10);
407 
408   // Find the referenced variables.
409   FindBlockDeclRefExprsVals F(*BV, BC);
410   F.Visit(BD->getBody());
411 
412   Vec = BV;
413   return BV;
414 }
415 
416 std::pair<AnalysisDeclContext::referenced_decls_iterator,
417           AnalysisDeclContext::referenced_decls_iterator>
418 AnalysisDeclContext::getReferencedBlockVars(const BlockDecl *BD) {
419   if (!ReferencedBlockVars)
420     ReferencedBlockVars = new llvm::DenseMap<const BlockDecl*,void*>();
421 
422   DeclVec *V = LazyInitializeReferencedDecls(BD, (*ReferencedBlockVars)[BD], A);
423   return std::make_pair(V->begin(), V->end());
424 }
425 
426 ManagedAnalysis *&AnalysisDeclContext::getAnalysisImpl(const void *tag) {
427   if (!ManagedAnalyses)
428     ManagedAnalyses = new ManagedAnalysisMap();
429   ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
430   return (*M)[tag];
431 }
432 
433 //===----------------------------------------------------------------------===//
434 // Cleanup.
435 //===----------------------------------------------------------------------===//
436 
437 ManagedAnalysis::~ManagedAnalysis() {}
438 
439 AnalysisDeclContext::~AnalysisDeclContext() {
440   delete forcedBlkExprs;
441   delete ReferencedBlockVars;
442   // Release the managed analyses.
443   if (ManagedAnalyses) {
444     ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
445     for (ManagedAnalysisMap::iterator I = M->begin(), E = M->end(); I!=E; ++I)
446       delete I->second;
447     delete M;
448   }
449 }
450 
451 AnalysisDeclContextManager::~AnalysisDeclContextManager() {
452   for (ContextMap::iterator I = Contexts.begin(), E = Contexts.end(); I!=E; ++I)
453     delete I->second;
454 }
455 
456 LocationContext::~LocationContext() {}
457 
458 LocationContextManager::~LocationContextManager() {
459   clear();
460 }
461 
462 void LocationContextManager::clear() {
463   for (llvm::FoldingSet<LocationContext>::iterator I = Contexts.begin(),
464        E = Contexts.end(); I != E; ) {
465     LocationContext *LC = &*I;
466     ++I;
467     delete LC;
468   }
469 
470   Contexts.clear();
471 }
472 
473