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1 //== AnalysisContext.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 AnalysisContext, a class that manages the analysis context
11 // data for path sensitive analysis.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "clang/AST/Decl.h"
16 #include "clang/AST/DeclObjC.h"
17 #include "clang/AST/DeclTemplate.h"
18 #include "clang/AST/ParentMap.h"
19 #include "clang/AST/StmtVisitor.h"
20 #include "clang/Analysis/Analyses/LiveVariables.h"
21 #include "clang/Analysis/Analyses/PseudoConstantAnalysis.h"
22 #include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
23 #include "clang/Analysis/AnalysisContext.h"
24 #include "clang/Analysis/CFG.h"
25 #include "clang/Analysis/CFGStmtMap.h"
26 #include "clang/Analysis/Support/BumpVector.h"
27 #include "llvm/ADT/SmallSet.h"
28 #include "llvm/Support/ErrorHandling.h"
29 
30 using namespace clang;
31 
AnalysisContext(const Decl * d,idx::TranslationUnit * tu,bool useUnoptimizedCFG,bool addehedges,bool addImplicitDtors,bool addInitializers)32 AnalysisContext::AnalysisContext(const Decl *d,
33                                  idx::TranslationUnit *tu,
34                                  bool useUnoptimizedCFG,
35                                  bool addehedges,
36                                  bool addImplicitDtors,
37                                  bool addInitializers)
38   : D(d), TU(tu),
39     forcedBlkExprs(0),
40     builtCFG(false), builtCompleteCFG(false),
41     useUnoptimizedCFG(useUnoptimizedCFG),
42     ReferencedBlockVars(0)
43 {
44   cfgBuildOptions.forcedBlkExprs = &forcedBlkExprs;
45   cfgBuildOptions.AddEHEdges = addehedges;
46   cfgBuildOptions.AddImplicitDtors = addImplicitDtors;
47   cfgBuildOptions.AddInitializers = addInitializers;
48 }
49 
clear()50 void AnalysisContextManager::clear() {
51   for (ContextMap::iterator I = Contexts.begin(), E = Contexts.end(); I!=E; ++I)
52     delete I->second;
53   Contexts.clear();
54 }
55 
getBody()56 Stmt *AnalysisContext::getBody() {
57   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
58     return FD->getBody();
59   else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D))
60     return MD->getBody();
61   else if (const BlockDecl *BD = dyn_cast<BlockDecl>(D))
62     return BD->getBody();
63   else if (const FunctionTemplateDecl *FunTmpl
64            = dyn_cast_or_null<FunctionTemplateDecl>(D))
65     return FunTmpl->getTemplatedDecl()->getBody();
66 
67   llvm_unreachable("unknown code decl");
68 }
69 
getSelfDecl() const70 const ImplicitParamDecl *AnalysisContext::getSelfDecl() const {
71   if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D))
72     return MD->getSelfDecl();
73 
74   return NULL;
75 }
76 
registerForcedBlockExpression(const Stmt * stmt)77 void AnalysisContext::registerForcedBlockExpression(const Stmt *stmt) {
78   if (!forcedBlkExprs)
79     forcedBlkExprs = new CFG::BuildOptions::ForcedBlkExprs();
80   // Default construct an entry for 'stmt'.
81   if (const Expr *e = dyn_cast<Expr>(stmt))
82     stmt = e->IgnoreParens();
83   (void) (*forcedBlkExprs)[stmt];
84 }
85 
86 const CFGBlock *
getBlockForRegisteredExpression(const Stmt * stmt)87 AnalysisContext::getBlockForRegisteredExpression(const Stmt *stmt) {
88   assert(forcedBlkExprs);
89   if (const Expr *e = dyn_cast<Expr>(stmt))
90     stmt = e->IgnoreParens();
91   CFG::BuildOptions::ForcedBlkExprs::const_iterator itr =
92     forcedBlkExprs->find(stmt);
93   assert(itr != forcedBlkExprs->end());
94   return itr->second;
95 }
96 
getCFG()97 CFG *AnalysisContext::getCFG() {
98   if (useUnoptimizedCFG)
99     return getUnoptimizedCFG();
100 
101   if (!builtCFG) {
102     cfg.reset(CFG::buildCFG(D, getBody(),
103                             &D->getASTContext(), cfgBuildOptions));
104     // Even when the cfg is not successfully built, we don't
105     // want to try building it again.
106     builtCFG = true;
107   }
108   return cfg.get();
109 }
110 
getUnoptimizedCFG()111 CFG *AnalysisContext::getUnoptimizedCFG() {
112   if (!builtCompleteCFG) {
113     CFG::BuildOptions B = cfgBuildOptions;
114     B.PruneTriviallyFalseEdges = false;
115     completeCFG.reset(CFG::buildCFG(D, getBody(), &D->getASTContext(), B));
116     // Even when the cfg is not successfully built, we don't
117     // want to try building it again.
118     builtCompleteCFG = true;
119   }
120   return completeCFG.get();
121 }
122 
getCFGStmtMap()123 CFGStmtMap *AnalysisContext::getCFGStmtMap() {
124   if (cfgStmtMap)
125     return cfgStmtMap.get();
126 
127   if (CFG *c = getCFG()) {
128     cfgStmtMap.reset(CFGStmtMap::Build(c, &getParentMap()));
129     return cfgStmtMap.get();
130   }
131 
132   return 0;
133 }
134 
getCFGReachablityAnalysis()135 CFGReverseBlockReachabilityAnalysis *AnalysisContext::getCFGReachablityAnalysis() {
136   if (CFA)
137     return CFA.get();
138 
139   if (CFG *c = getCFG()) {
140     CFA.reset(new CFGReverseBlockReachabilityAnalysis(*c));
141     return CFA.get();
142   }
143 
144   return 0;
145 }
146 
dumpCFG()147 void AnalysisContext::dumpCFG() {
148     getCFG()->dump(getASTContext().getLangOptions());
149 }
150 
getParentMap()151 ParentMap &AnalysisContext::getParentMap() {
152   if (!PM)
153     PM.reset(new ParentMap(getBody()));
154   return *PM;
155 }
156 
getPseudoConstantAnalysis()157 PseudoConstantAnalysis *AnalysisContext::getPseudoConstantAnalysis() {
158   if (!PCA)
159     PCA.reset(new PseudoConstantAnalysis(getBody()));
160   return PCA.get();
161 }
162 
getLiveVariables()163 LiveVariables *AnalysisContext::getLiveVariables() {
164   if (!liveness) {
165     if (CFG *c = getCFG()) {
166       liveness.reset(new LiveVariables(*this));
167       liveness->runOnCFG(*c);
168       liveness->runOnAllBlocks(*c, 0, true);
169     }
170   }
171 
172   return liveness.get();
173 }
174 
getRelaxedLiveVariables()175 LiveVariables *AnalysisContext::getRelaxedLiveVariables() {
176   if (!relaxedLiveness)
177     if (CFG *c = getCFG()) {
178       relaxedLiveness.reset(new LiveVariables(*this, false));
179       relaxedLiveness->runOnCFG(*c);
180       relaxedLiveness->runOnAllBlocks(*c, 0, true);
181     }
182 
183   return relaxedLiveness.get();
184 }
185 
getContext(const Decl * D,idx::TranslationUnit * TU)186 AnalysisContext *AnalysisContextManager::getContext(const Decl *D,
187                                                     idx::TranslationUnit *TU) {
188   AnalysisContext *&AC = Contexts[D];
189   if (!AC)
190     AC = new AnalysisContext(D, TU, UseUnoptimizedCFG, false,
191         AddImplicitDtors, AddInitializers);
192 
193   return AC;
194 }
195 
196 //===----------------------------------------------------------------------===//
197 // FoldingSet profiling.
198 //===----------------------------------------------------------------------===//
199 
ProfileCommon(llvm::FoldingSetNodeID & ID,ContextKind ck,AnalysisContext * ctx,const LocationContext * parent,const void * data)200 void LocationContext::ProfileCommon(llvm::FoldingSetNodeID &ID,
201                                     ContextKind ck,
202                                     AnalysisContext *ctx,
203                                     const LocationContext *parent,
204                                     const void* data) {
205   ID.AddInteger(ck);
206   ID.AddPointer(ctx);
207   ID.AddPointer(parent);
208   ID.AddPointer(data);
209 }
210 
Profile(llvm::FoldingSetNodeID & ID)211 void StackFrameContext::Profile(llvm::FoldingSetNodeID &ID) {
212   Profile(ID, getAnalysisContext(), getParent(), CallSite, Block, Index);
213 }
214 
Profile(llvm::FoldingSetNodeID & ID)215 void ScopeContext::Profile(llvm::FoldingSetNodeID &ID) {
216   Profile(ID, getAnalysisContext(), getParent(), Enter);
217 }
218 
Profile(llvm::FoldingSetNodeID & ID)219 void BlockInvocationContext::Profile(llvm::FoldingSetNodeID &ID) {
220   Profile(ID, getAnalysisContext(), getParent(), BD);
221 }
222 
223 //===----------------------------------------------------------------------===//
224 // LocationContext creation.
225 //===----------------------------------------------------------------------===//
226 
227 template <typename LOC, typename DATA>
228 const LOC*
getLocationContext(AnalysisContext * ctx,const LocationContext * parent,const DATA * d)229 LocationContextManager::getLocationContext(AnalysisContext *ctx,
230                                            const LocationContext *parent,
231                                            const DATA *d) {
232   llvm::FoldingSetNodeID ID;
233   LOC::Profile(ID, ctx, parent, d);
234   void *InsertPos;
235 
236   LOC *L = cast_or_null<LOC>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
237 
238   if (!L) {
239     L = new LOC(ctx, parent, d);
240     Contexts.InsertNode(L, InsertPos);
241   }
242   return L;
243 }
244 
245 const StackFrameContext*
getStackFrame(AnalysisContext * ctx,const LocationContext * parent,const Stmt * s,const CFGBlock * blk,unsigned idx)246 LocationContextManager::getStackFrame(AnalysisContext *ctx,
247                                       const LocationContext *parent,
248                                       const Stmt *s,
249                                       const CFGBlock *blk, unsigned idx) {
250   llvm::FoldingSetNodeID ID;
251   StackFrameContext::Profile(ID, ctx, parent, s, blk, idx);
252   void *InsertPos;
253   StackFrameContext *L =
254    cast_or_null<StackFrameContext>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
255   if (!L) {
256     L = new StackFrameContext(ctx, parent, s, blk, idx);
257     Contexts.InsertNode(L, InsertPos);
258   }
259   return L;
260 }
261 
262 const ScopeContext *
getScope(AnalysisContext * ctx,const LocationContext * parent,const Stmt * s)263 LocationContextManager::getScope(AnalysisContext *ctx,
264                                  const LocationContext *parent,
265                                  const Stmt *s) {
266   return getLocationContext<ScopeContext, Stmt>(ctx, parent, s);
267 }
268 
269 //===----------------------------------------------------------------------===//
270 // LocationContext methods.
271 //===----------------------------------------------------------------------===//
272 
getCurrentStackFrame() const273 const StackFrameContext *LocationContext::getCurrentStackFrame() const {
274   const LocationContext *LC = this;
275   while (LC) {
276     if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LC))
277       return SFC;
278     LC = LC->getParent();
279   }
280   return NULL;
281 }
282 
283 const StackFrameContext *
getStackFrameForDeclContext(const DeclContext * DC) const284 LocationContext::getStackFrameForDeclContext(const DeclContext *DC) const {
285   const LocationContext *LC = this;
286   while (LC) {
287     if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LC)) {
288       if (cast<DeclContext>(SFC->getDecl()) == DC)
289         return SFC;
290     }
291     LC = LC->getParent();
292   }
293   return NULL;
294 }
295 
isParentOf(const LocationContext * LC) const296 bool LocationContext::isParentOf(const LocationContext *LC) const {
297   do {
298     const LocationContext *Parent = LC->getParent();
299     if (Parent == this)
300       return true;
301     else
302       LC = Parent;
303   } while (LC);
304 
305   return false;
306 }
307 
308 //===----------------------------------------------------------------------===//
309 // Lazily generated map to query the external variables referenced by a Block.
310 //===----------------------------------------------------------------------===//
311 
312 namespace {
313 class FindBlockDeclRefExprsVals : public StmtVisitor<FindBlockDeclRefExprsVals>{
314   BumpVector<const VarDecl*> &BEVals;
315   BumpVectorContext &BC;
316   llvm::DenseMap<const VarDecl*, unsigned> Visited;
317   llvm::SmallSet<const DeclContext*, 4> IgnoredContexts;
318 public:
FindBlockDeclRefExprsVals(BumpVector<const VarDecl * > & bevals,BumpVectorContext & bc)319   FindBlockDeclRefExprsVals(BumpVector<const VarDecl*> &bevals,
320                             BumpVectorContext &bc)
321   : BEVals(bevals), BC(bc) {}
322 
IsTrackedDecl(const VarDecl * VD)323   bool IsTrackedDecl(const VarDecl *VD) {
324     const DeclContext *DC = VD->getDeclContext();
325     return IgnoredContexts.count(DC) == 0;
326   }
327 
VisitStmt(Stmt * S)328   void VisitStmt(Stmt *S) {
329     for (Stmt::child_range I = S->children(); I; ++I)
330       if (Stmt *child = *I)
331         Visit(child);
332   }
333 
VisitDeclRefExpr(const DeclRefExpr * DR)334   void VisitDeclRefExpr(const DeclRefExpr *DR) {
335     // Non-local variables are also directly modified.
336     if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl()))
337       if (!VD->hasLocalStorage()) {
338         unsigned &flag = Visited[VD];
339         if (!flag) {
340           flag = 1;
341           BEVals.push_back(VD, BC);
342         }
343       }
344   }
345 
VisitBlockDeclRefExpr(BlockDeclRefExpr * DR)346   void VisitBlockDeclRefExpr(BlockDeclRefExpr *DR) {
347     if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
348       unsigned &flag = Visited[VD];
349       if (!flag) {
350         flag = 1;
351         if (IsTrackedDecl(VD))
352           BEVals.push_back(VD, BC);
353       }
354     }
355   }
356 
VisitBlockExpr(BlockExpr * BR)357   void VisitBlockExpr(BlockExpr *BR) {
358     // Blocks containing blocks can transitively capture more variables.
359     IgnoredContexts.insert(BR->getBlockDecl());
360     Visit(BR->getBlockDecl()->getBody());
361   }
362 };
363 } // end anonymous namespace
364 
365 typedef BumpVector<const VarDecl*> DeclVec;
366 
LazyInitializeReferencedDecls(const BlockDecl * BD,void * & Vec,llvm::BumpPtrAllocator & A)367 static DeclVec* LazyInitializeReferencedDecls(const BlockDecl *BD,
368                                               void *&Vec,
369                                               llvm::BumpPtrAllocator &A) {
370   if (Vec)
371     return (DeclVec*) Vec;
372 
373   BumpVectorContext BC(A);
374   DeclVec *BV = (DeclVec*) A.Allocate<DeclVec>();
375   new (BV) DeclVec(BC, 10);
376 
377   // Find the referenced variables.
378   FindBlockDeclRefExprsVals F(*BV, BC);
379   F.Visit(BD->getBody());
380 
381   Vec = BV;
382   return BV;
383 }
384 
385 std::pair<AnalysisContext::referenced_decls_iterator,
386           AnalysisContext::referenced_decls_iterator>
getReferencedBlockVars(const BlockDecl * BD)387 AnalysisContext::getReferencedBlockVars(const BlockDecl *BD) {
388   if (!ReferencedBlockVars)
389     ReferencedBlockVars = new llvm::DenseMap<const BlockDecl*,void*>();
390 
391   DeclVec *V = LazyInitializeReferencedDecls(BD, (*ReferencedBlockVars)[BD], A);
392   return std::make_pair(V->begin(), V->end());
393 }
394 
395 //===----------------------------------------------------------------------===//
396 // Cleanup.
397 //===----------------------------------------------------------------------===//
398 
~AnalysisContext()399 AnalysisContext::~AnalysisContext() {
400   delete forcedBlkExprs;
401   delete ReferencedBlockVars;
402 }
403 
~AnalysisContextManager()404 AnalysisContextManager::~AnalysisContextManager() {
405   for (ContextMap::iterator I = Contexts.begin(), E = Contexts.end(); I!=E; ++I)
406     delete I->second;
407 }
408 
~LocationContext()409 LocationContext::~LocationContext() {}
410 
~LocationContextManager()411 LocationContextManager::~LocationContextManager() {
412   clear();
413 }
414 
clear()415 void LocationContextManager::clear() {
416   for (llvm::FoldingSet<LocationContext>::iterator I = Contexts.begin(),
417        E = Contexts.end(); I != E; ) {
418     LocationContext *LC = &*I;
419     ++I;
420     delete LC;
421   }
422 
423   Contexts.clear();
424 }
425 
426