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      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(raw_ostream &OS, StringRef Indent) 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       OS << Indent << '#' << Frame++ << ' ';
    423       cast<StackFrameContext>(LCtx)->getDecl()->print(OS, PP);
    424       OS << '\n';
    425       break;
    426     case Scope:
    427       OS << Indent << "    (scope)\n";
    428       break;
    429     case Block:
    430       OS << Indent << "    (block context: "
    431                    << cast<BlockInvocationContext>(LCtx)->getContextData()
    432                    << ")\n";
    433       break;
    434     }
    435   }
    436 }
    437 
    438 void LocationContext::dumpStack() const {
    439   dumpStack(llvm::errs());
    440 }
    441 
    442 //===----------------------------------------------------------------------===//
    443 // Lazily generated map to query the external variables referenced by a Block.
    444 //===----------------------------------------------------------------------===//
    445 
    446 namespace {
    447 class FindBlockDeclRefExprsVals : public StmtVisitor<FindBlockDeclRefExprsVals>{
    448   BumpVector<const VarDecl*> &BEVals;
    449   BumpVectorContext &BC;
    450   llvm::SmallPtrSet<const VarDecl*, 4> Visited;
    451   llvm::SmallPtrSet<const DeclContext*, 4> IgnoredContexts;
    452 public:
    453   FindBlockDeclRefExprsVals(BumpVector<const VarDecl*> &bevals,
    454                             BumpVectorContext &bc)
    455   : BEVals(bevals), BC(bc) {}
    456 
    457   bool IsTrackedDecl(const VarDecl *VD) {
    458     const DeclContext *DC = VD->getDeclContext();
    459     return IgnoredContexts.count(DC) == 0;
    460   }
    461 
    462   void VisitStmt(Stmt *S) {
    463     for (Stmt::child_range I = S->children(); I; ++I)
    464       if (Stmt *child = *I)
    465         Visit(child);
    466   }
    467 
    468   void VisitDeclRefExpr(DeclRefExpr *DR) {
    469     // Non-local variables are also directly modified.
    470     if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
    471       if (!VD->hasLocalStorage()) {
    472         if (Visited.insert(VD))
    473           BEVals.push_back(VD, BC);
    474       }
    475     }
    476   }
    477 
    478   void VisitBlockExpr(BlockExpr *BR) {
    479     // Blocks containing blocks can transitively capture more variables.
    480     IgnoredContexts.insert(BR->getBlockDecl());
    481     Visit(BR->getBlockDecl()->getBody());
    482   }
    483 
    484   void VisitPseudoObjectExpr(PseudoObjectExpr *PE) {
    485     for (PseudoObjectExpr::semantics_iterator it = PE->semantics_begin(),
    486          et = PE->semantics_end(); it != et; ++it) {
    487       Expr *Semantic = *it;
    488       if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(Semantic))
    489         Semantic = OVE->getSourceExpr();
    490       Visit(Semantic);
    491     }
    492   }
    493 };
    494 } // end anonymous namespace
    495 
    496 typedef BumpVector<const VarDecl*> DeclVec;
    497 
    498 static DeclVec* LazyInitializeReferencedDecls(const BlockDecl *BD,
    499                                               void *&Vec,
    500                                               llvm::BumpPtrAllocator &A) {
    501   if (Vec)
    502     return (DeclVec*) Vec;
    503 
    504   BumpVectorContext BC(A);
    505   DeclVec *BV = (DeclVec*) A.Allocate<DeclVec>();
    506   new (BV) DeclVec(BC, 10);
    507 
    508   // Go through the capture list.
    509   for (BlockDecl::capture_const_iterator CI = BD->capture_begin(),
    510        CE = BD->capture_end(); CI != CE; ++CI) {
    511     BV->push_back(CI->getVariable(), BC);
    512   }
    513 
    514   // Find the referenced global/static variables.
    515   FindBlockDeclRefExprsVals F(*BV, BC);
    516   F.Visit(BD->getBody());
    517 
    518   Vec = BV;
    519   return BV;
    520 }
    521 
    522 std::pair<AnalysisDeclContext::referenced_decls_iterator,
    523           AnalysisDeclContext::referenced_decls_iterator>
    524 AnalysisDeclContext::getReferencedBlockVars(const BlockDecl *BD) {
    525   if (!ReferencedBlockVars)
    526     ReferencedBlockVars = new llvm::DenseMap<const BlockDecl*,void*>();
    527 
    528   DeclVec *V = LazyInitializeReferencedDecls(BD, (*ReferencedBlockVars)[BD], A);
    529   return std::make_pair(V->begin(), V->end());
    530 }
    531 
    532 ManagedAnalysis *&AnalysisDeclContext::getAnalysisImpl(const void *tag) {
    533   if (!ManagedAnalyses)
    534     ManagedAnalyses = new ManagedAnalysisMap();
    535   ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
    536   return (*M)[tag];
    537 }
    538 
    539 //===----------------------------------------------------------------------===//
    540 // Cleanup.
    541 //===----------------------------------------------------------------------===//
    542 
    543 ManagedAnalysis::~ManagedAnalysis() {}
    544 
    545 AnalysisDeclContext::~AnalysisDeclContext() {
    546   delete forcedBlkExprs;
    547   delete ReferencedBlockVars;
    548   // Release the managed analyses.
    549   if (ManagedAnalyses) {
    550     ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
    551     for (ManagedAnalysisMap::iterator I = M->begin(), E = M->end(); I!=E; ++I)
    552       delete I->second;
    553     delete M;
    554   }
    555 }
    556 
    557 AnalysisDeclContextManager::~AnalysisDeclContextManager() {
    558   for (ContextMap::iterator I = Contexts.begin(), E = Contexts.end(); I!=E; ++I)
    559     delete I->second;
    560 }
    561 
    562 LocationContext::~LocationContext() {}
    563 
    564 LocationContextManager::~LocationContextManager() {
    565   clear();
    566 }
    567 
    568 void LocationContextManager::clear() {
    569   for (llvm::FoldingSet<LocationContext>::iterator I = Contexts.begin(),
    570        E = Contexts.end(); I != E; ) {
    571     LocationContext *LC = &*I;
    572     ++I;
    573     delete LC;
    574   }
    575 
    576   Contexts.clear();
    577 }
    578 
    579