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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/SaveAndRestore.h"
     32 #include "llvm/Support/raw_ostream.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(nullptr),
     45     builtCFG(false),
     46     builtCompleteCFG(false),
     47     ReferencedBlockVars(nullptr),
     48     ManagedAnalyses(nullptr)
     49 {
     50   cfgBuildOptions.forcedBlkExprs = &forcedBlkExprs;
     51 }
     52 
     53 AnalysisDeclContext::AnalysisDeclContext(AnalysisDeclContextManager *Mgr,
     54                                          const Decl *d)
     55 : Manager(Mgr),
     56   D(d),
     57   forcedBlkExprs(nullptr),
     58   builtCFG(false),
     59   builtCompleteCFG(false),
     60   ReferencedBlockVars(nullptr),
     61   ManagedAnalyses(nullptr)
     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                                                        bool addCXXNewAllocator)
     73   : SynthesizeBodies(synthesizeBodies)
     74 {
     75   cfgBuildOptions.PruneTriviallyFalseEdges = !useUnoptimizedCFG;
     76   cfgBuildOptions.AddImplicitDtors = addImplicitDtors;
     77   cfgBuildOptions.AddInitializers = addInitializers;
     78   cfgBuildOptions.AddTemporaryDtors = addTemporaryDtors;
     79   cfgBuildOptions.AddStaticInitBranches = addStaticInitBranch;
     80   cfgBuildOptions.AddCXXNewAllocator = addCXXNewAllocator;
     81 }
     82 
     83 void AnalysisDeclContextManager::clear() {
     84   llvm::DeleteContainerSeconds(Contexts);
     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       Body = getBodyFarm(getASTContext()).getBody(FD);
     98       if (Body)
     99         IsAutosynthesized = true;
    100     }
    101     return Body;
    102   }
    103   else if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {
    104     Stmt *Body = MD->getBody();
    105     if (!Body && Manager && Manager->synthesizeBodies()) {
    106       Body = getBodyFarm(getASTContext()).getBody(MD);
    107       if (Body)
    108         IsAutosynthesized = true;
    109     }
    110     return Body;
    111   } else if (const BlockDecl *BD = dyn_cast<BlockDecl>(D))
    112     return BD->getBody();
    113   else if (const FunctionTemplateDecl *FunTmpl
    114            = dyn_cast_or_null<FunctionTemplateDecl>(D))
    115     return FunTmpl->getTemplatedDecl()->getBody();
    116 
    117   llvm_unreachable("unknown code decl");
    118 }
    119 
    120 Stmt *AnalysisDeclContext::getBody() const {
    121   bool Tmp;
    122   return getBody(Tmp);
    123 }
    124 
    125 bool AnalysisDeclContext::isBodyAutosynthesized() const {
    126   bool Tmp;
    127   getBody(Tmp);
    128   return Tmp;
    129 }
    130 
    131 const ImplicitParamDecl *AnalysisDeclContext::getSelfDecl() const {
    132   if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D))
    133     return MD->getSelfDecl();
    134   if (const BlockDecl *BD = dyn_cast<BlockDecl>(D)) {
    135     // See if 'self' was captured by the block.
    136     for (const auto &I : BD->captures()) {
    137       const VarDecl *VD = I.getVariable();
    138       if (VD->getName() == "self")
    139         return dyn_cast<ImplicitParamDecl>(VD);
    140     }
    141   }
    142 
    143   return nullptr;
    144 }
    145 
    146 void AnalysisDeclContext::registerForcedBlockExpression(const Stmt *stmt) {
    147   if (!forcedBlkExprs)
    148     forcedBlkExprs = new CFG::BuildOptions::ForcedBlkExprs();
    149   // Default construct an entry for 'stmt'.
    150   if (const Expr *e = dyn_cast<Expr>(stmt))
    151     stmt = e->IgnoreParens();
    152   (void) (*forcedBlkExprs)[stmt];
    153 }
    154 
    155 const CFGBlock *
    156 AnalysisDeclContext::getBlockForRegisteredExpression(const Stmt *stmt) {
    157   assert(forcedBlkExprs);
    158   if (const Expr *e = dyn_cast<Expr>(stmt))
    159     stmt = e->IgnoreParens();
    160   CFG::BuildOptions::ForcedBlkExprs::const_iterator itr =
    161     forcedBlkExprs->find(stmt);
    162   assert(itr != forcedBlkExprs->end());
    163   return itr->second;
    164 }
    165 
    166 /// Add each synthetic statement in the CFG to the parent map, using the
    167 /// source statement's parent.
    168 static void addParentsForSyntheticStmts(const CFG *TheCFG, ParentMap &PM) {
    169   if (!TheCFG)
    170     return;
    171 
    172   for (CFG::synthetic_stmt_iterator I = TheCFG->synthetic_stmt_begin(),
    173                                     E = TheCFG->synthetic_stmt_end();
    174        I != E; ++I) {
    175     PM.setParent(I->first, PM.getParent(I->second));
    176   }
    177 }
    178 
    179 CFG *AnalysisDeclContext::getCFG() {
    180   if (!cfgBuildOptions.PruneTriviallyFalseEdges)
    181     return getUnoptimizedCFG();
    182 
    183   if (!builtCFG) {
    184     cfg.reset(CFG::buildCFG(D, getBody(),
    185                             &D->getASTContext(), cfgBuildOptions));
    186     // Even when the cfg is not successfully built, we don't
    187     // want to try building it again.
    188     builtCFG = true;
    189 
    190     if (PM)
    191       addParentsForSyntheticStmts(cfg.get(), *PM);
    192 
    193     // The Observer should only observe one build of the CFG.
    194     getCFGBuildOptions().Observer = nullptr;
    195   }
    196   return cfg.get();
    197 }
    198 
    199 CFG *AnalysisDeclContext::getUnoptimizedCFG() {
    200   if (!builtCompleteCFG) {
    201     SaveAndRestore<bool> NotPrune(cfgBuildOptions.PruneTriviallyFalseEdges,
    202                                   false);
    203     completeCFG.reset(CFG::buildCFG(D, getBody(), &D->getASTContext(),
    204                                     cfgBuildOptions));
    205     // Even when the cfg is not successfully built, we don't
    206     // want to try building it again.
    207     builtCompleteCFG = true;
    208 
    209     if (PM)
    210       addParentsForSyntheticStmts(completeCFG.get(), *PM);
    211 
    212     // The Observer should only observe one build of the CFG.
    213     getCFGBuildOptions().Observer = nullptr;
    214   }
    215   return completeCFG.get();
    216 }
    217 
    218 CFGStmtMap *AnalysisDeclContext::getCFGStmtMap() {
    219   if (cfgStmtMap)
    220     return cfgStmtMap.get();
    221 
    222   if (CFG *c = getCFG()) {
    223     cfgStmtMap.reset(CFGStmtMap::Build(c, &getParentMap()));
    224     return cfgStmtMap.get();
    225   }
    226 
    227   return nullptr;
    228 }
    229 
    230 CFGReverseBlockReachabilityAnalysis *AnalysisDeclContext::getCFGReachablityAnalysis() {
    231   if (CFA)
    232     return CFA.get();
    233 
    234   if (CFG *c = getCFG()) {
    235     CFA.reset(new CFGReverseBlockReachabilityAnalysis(*c));
    236     return CFA.get();
    237   }
    238 
    239   return nullptr;
    240 }
    241 
    242 void AnalysisDeclContext::dumpCFG(bool ShowColors) {
    243     getCFG()->dump(getASTContext().getLangOpts(), ShowColors);
    244 }
    245 
    246 ParentMap &AnalysisDeclContext::getParentMap() {
    247   if (!PM) {
    248     PM.reset(new ParentMap(getBody()));
    249     if (const CXXConstructorDecl *C = dyn_cast<CXXConstructorDecl>(getDecl())) {
    250       for (const auto *I : C->inits()) {
    251         PM->addStmt(I->getInit());
    252       }
    253     }
    254     if (builtCFG)
    255       addParentsForSyntheticStmts(getCFG(), *PM);
    256     if (builtCompleteCFG)
    257       addParentsForSyntheticStmts(getUnoptimizedCFG(), *PM);
    258   }
    259   return *PM;
    260 }
    261 
    262 PseudoConstantAnalysis *AnalysisDeclContext::getPseudoConstantAnalysis() {
    263   if (!PCA)
    264     PCA.reset(new PseudoConstantAnalysis(getBody()));
    265   return PCA.get();
    266 }
    267 
    268 AnalysisDeclContext *AnalysisDeclContextManager::getContext(const Decl *D) {
    269   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
    270     // Calling 'hasBody' replaces 'FD' in place with the FunctionDecl
    271     // that has the body.
    272     FD->hasBody(FD);
    273     D = FD;
    274   }
    275 
    276   AnalysisDeclContext *&AC = Contexts[D];
    277   if (!AC)
    278     AC = new AnalysisDeclContext(this, D, cfgBuildOptions);
    279   return AC;
    280 }
    281 
    282 const StackFrameContext *
    283 AnalysisDeclContext::getStackFrame(LocationContext const *Parent, const Stmt *S,
    284                                const CFGBlock *Blk, unsigned Idx) {
    285   return getLocationContextManager().getStackFrame(this, Parent, S, Blk, Idx);
    286 }
    287 
    288 const BlockInvocationContext *
    289 AnalysisDeclContext::getBlockInvocationContext(const LocationContext *parent,
    290                                                const clang::BlockDecl *BD,
    291                                                const void *ContextData) {
    292   return getLocationContextManager().getBlockInvocationContext(this, parent,
    293                                                                BD, ContextData);
    294 }
    295 
    296 LocationContextManager & AnalysisDeclContext::getLocationContextManager() {
    297   assert(Manager &&
    298          "Cannot create LocationContexts without an AnalysisDeclContextManager!");
    299   return Manager->getLocationContextManager();
    300 }
    301 
    302 //===----------------------------------------------------------------------===//
    303 // FoldingSet profiling.
    304 //===----------------------------------------------------------------------===//
    305 
    306 void LocationContext::ProfileCommon(llvm::FoldingSetNodeID &ID,
    307                                     ContextKind ck,
    308                                     AnalysisDeclContext *ctx,
    309                                     const LocationContext *parent,
    310                                     const void *data) {
    311   ID.AddInteger(ck);
    312   ID.AddPointer(ctx);
    313   ID.AddPointer(parent);
    314   ID.AddPointer(data);
    315 }
    316 
    317 void StackFrameContext::Profile(llvm::FoldingSetNodeID &ID) {
    318   Profile(ID, getAnalysisDeclContext(), getParent(), CallSite, Block, Index);
    319 }
    320 
    321 void ScopeContext::Profile(llvm::FoldingSetNodeID &ID) {
    322   Profile(ID, getAnalysisDeclContext(), getParent(), Enter);
    323 }
    324 
    325 void BlockInvocationContext::Profile(llvm::FoldingSetNodeID &ID) {
    326   Profile(ID, getAnalysisDeclContext(), getParent(), BD, ContextData);
    327 }
    328 
    329 //===----------------------------------------------------------------------===//
    330 // LocationContext creation.
    331 //===----------------------------------------------------------------------===//
    332 
    333 template <typename LOC, typename DATA>
    334 const LOC*
    335 LocationContextManager::getLocationContext(AnalysisDeclContext *ctx,
    336                                            const LocationContext *parent,
    337                                            const DATA *d) {
    338   llvm::FoldingSetNodeID ID;
    339   LOC::Profile(ID, ctx, parent, d);
    340   void *InsertPos;
    341 
    342   LOC *L = cast_or_null<LOC>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
    343 
    344   if (!L) {
    345     L = new LOC(ctx, parent, d);
    346     Contexts.InsertNode(L, InsertPos);
    347   }
    348   return L;
    349 }
    350 
    351 const StackFrameContext*
    352 LocationContextManager::getStackFrame(AnalysisDeclContext *ctx,
    353                                       const LocationContext *parent,
    354                                       const Stmt *s,
    355                                       const CFGBlock *blk, unsigned idx) {
    356   llvm::FoldingSetNodeID ID;
    357   StackFrameContext::Profile(ID, ctx, parent, s, blk, idx);
    358   void *InsertPos;
    359   StackFrameContext *L =
    360    cast_or_null<StackFrameContext>(Contexts.FindNodeOrInsertPos(ID, InsertPos));
    361   if (!L) {
    362     L = new StackFrameContext(ctx, parent, s, blk, idx);
    363     Contexts.InsertNode(L, InsertPos);
    364   }
    365   return L;
    366 }
    367 
    368 const ScopeContext *
    369 LocationContextManager::getScope(AnalysisDeclContext *ctx,
    370                                  const LocationContext *parent,
    371                                  const Stmt *s) {
    372   return getLocationContext<ScopeContext, Stmt>(ctx, parent, s);
    373 }
    374 
    375 const BlockInvocationContext *
    376 LocationContextManager::getBlockInvocationContext(AnalysisDeclContext *ctx,
    377                                                   const LocationContext *parent,
    378                                                   const BlockDecl *BD,
    379                                                   const void *ContextData) {
    380   llvm::FoldingSetNodeID ID;
    381   BlockInvocationContext::Profile(ID, ctx, parent, BD, ContextData);
    382   void *InsertPos;
    383   BlockInvocationContext *L =
    384     cast_or_null<BlockInvocationContext>(Contexts.FindNodeOrInsertPos(ID,
    385                                                                     InsertPos));
    386   if (!L) {
    387     L = new BlockInvocationContext(ctx, parent, BD, ContextData);
    388     Contexts.InsertNode(L, InsertPos);
    389   }
    390   return L;
    391 }
    392 
    393 //===----------------------------------------------------------------------===//
    394 // LocationContext methods.
    395 //===----------------------------------------------------------------------===//
    396 
    397 const StackFrameContext *LocationContext::getCurrentStackFrame() const {
    398   const LocationContext *LC = this;
    399   while (LC) {
    400     if (const StackFrameContext *SFC = dyn_cast<StackFrameContext>(LC))
    401       return SFC;
    402     LC = LC->getParent();
    403   }
    404   return nullptr;
    405 }
    406 
    407 bool LocationContext::inTopFrame() const {
    408   return getCurrentStackFrame()->inTopFrame();
    409 }
    410 
    411 bool LocationContext::isParentOf(const LocationContext *LC) const {
    412   do {
    413     const LocationContext *Parent = LC->getParent();
    414     if (Parent == this)
    415       return true;
    416     else
    417       LC = Parent;
    418   } while (LC);
    419 
    420   return false;
    421 }
    422 
    423 void LocationContext::dumpStack(raw_ostream &OS, StringRef Indent) const {
    424   ASTContext &Ctx = getAnalysisDeclContext()->getASTContext();
    425   PrintingPolicy PP(Ctx.getLangOpts());
    426   PP.TerseOutput = 1;
    427 
    428   unsigned Frame = 0;
    429   for (const LocationContext *LCtx = this; LCtx; LCtx = LCtx->getParent()) {
    430     switch (LCtx->getKind()) {
    431     case StackFrame:
    432       OS << Indent << '#' << Frame++ << ' ';
    433       cast<StackFrameContext>(LCtx)->getDecl()->print(OS, PP);
    434       OS << '\n';
    435       break;
    436     case Scope:
    437       OS << Indent << "    (scope)\n";
    438       break;
    439     case Block:
    440       OS << Indent << "    (block context: "
    441                    << cast<BlockInvocationContext>(LCtx)->getContextData()
    442                    << ")\n";
    443       break;
    444     }
    445   }
    446 }
    447 
    448 LLVM_DUMP_METHOD void LocationContext::dumpStack() const {
    449   dumpStack(llvm::errs());
    450 }
    451 
    452 //===----------------------------------------------------------------------===//
    453 // Lazily generated map to query the external variables referenced by a Block.
    454 //===----------------------------------------------------------------------===//
    455 
    456 namespace {
    457 class FindBlockDeclRefExprsVals : public StmtVisitor<FindBlockDeclRefExprsVals>{
    458   BumpVector<const VarDecl*> &BEVals;
    459   BumpVectorContext &BC;
    460   llvm::SmallPtrSet<const VarDecl*, 4> Visited;
    461   llvm::SmallPtrSet<const DeclContext*, 4> IgnoredContexts;
    462 public:
    463   FindBlockDeclRefExprsVals(BumpVector<const VarDecl*> &bevals,
    464                             BumpVectorContext &bc)
    465   : BEVals(bevals), BC(bc) {}
    466 
    467   void VisitStmt(Stmt *S) {
    468     for (Stmt::child_range I = S->children(); I; ++I)
    469       if (Stmt *child = *I)
    470         Visit(child);
    471   }
    472 
    473   void VisitDeclRefExpr(DeclRefExpr *DR) {
    474     // Non-local variables are also directly modified.
    475     if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
    476       if (!VD->hasLocalStorage()) {
    477         if (Visited.insert(VD))
    478           BEVals.push_back(VD, BC);
    479       }
    480     }
    481   }
    482 
    483   void VisitBlockExpr(BlockExpr *BR) {
    484     // Blocks containing blocks can transitively capture more variables.
    485     IgnoredContexts.insert(BR->getBlockDecl());
    486     Visit(BR->getBlockDecl()->getBody());
    487   }
    488 
    489   void VisitPseudoObjectExpr(PseudoObjectExpr *PE) {
    490     for (PseudoObjectExpr::semantics_iterator it = PE->semantics_begin(),
    491          et = PE->semantics_end(); it != et; ++it) {
    492       Expr *Semantic = *it;
    493       if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(Semantic))
    494         Semantic = OVE->getSourceExpr();
    495       Visit(Semantic);
    496     }
    497   }
    498 };
    499 } // end anonymous namespace
    500 
    501 typedef BumpVector<const VarDecl*> DeclVec;
    502 
    503 static DeclVec* LazyInitializeReferencedDecls(const BlockDecl *BD,
    504                                               void *&Vec,
    505                                               llvm::BumpPtrAllocator &A) {
    506   if (Vec)
    507     return (DeclVec*) Vec;
    508 
    509   BumpVectorContext BC(A);
    510   DeclVec *BV = (DeclVec*) A.Allocate<DeclVec>();
    511   new (BV) DeclVec(BC, 10);
    512 
    513   // Go through the capture list.
    514   for (const auto &CI : BD->captures()) {
    515     BV->push_back(CI.getVariable(), BC);
    516   }
    517 
    518   // Find the referenced global/static variables.
    519   FindBlockDeclRefExprsVals F(*BV, BC);
    520   F.Visit(BD->getBody());
    521 
    522   Vec = BV;
    523   return BV;
    524 }
    525 
    526 std::pair<AnalysisDeclContext::referenced_decls_iterator,
    527           AnalysisDeclContext::referenced_decls_iterator>
    528 AnalysisDeclContext::getReferencedBlockVars(const BlockDecl *BD) {
    529   if (!ReferencedBlockVars)
    530     ReferencedBlockVars = new llvm::DenseMap<const BlockDecl*,void*>();
    531 
    532   DeclVec *V = LazyInitializeReferencedDecls(BD, (*ReferencedBlockVars)[BD], A);
    533   return std::make_pair(V->begin(), V->end());
    534 }
    535 
    536 ManagedAnalysis *&AnalysisDeclContext::getAnalysisImpl(const void *tag) {
    537   if (!ManagedAnalyses)
    538     ManagedAnalyses = new ManagedAnalysisMap();
    539   ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
    540   return (*M)[tag];
    541 }
    542 
    543 //===----------------------------------------------------------------------===//
    544 // Cleanup.
    545 //===----------------------------------------------------------------------===//
    546 
    547 ManagedAnalysis::~ManagedAnalysis() {}
    548 
    549 AnalysisDeclContext::~AnalysisDeclContext() {
    550   delete forcedBlkExprs;
    551   delete ReferencedBlockVars;
    552   // Release the managed analyses.
    553   if (ManagedAnalyses) {
    554     ManagedAnalysisMap *M = (ManagedAnalysisMap*) ManagedAnalyses;
    555     llvm::DeleteContainerSeconds(*M);
    556     delete M;
    557   }
    558 }
    559 
    560 AnalysisDeclContextManager::~AnalysisDeclContextManager() {
    561   llvm::DeleteContainerSeconds(Contexts);
    562 }
    563 
    564 LocationContext::~LocationContext() {}
    565 
    566 LocationContextManager::~LocationContextManager() {
    567   clear();
    568 }
    569 
    570 void LocationContextManager::clear() {
    571   for (llvm::FoldingSet<LocationContext>::iterator I = Contexts.begin(),
    572        E = Contexts.end(); I != E; ) {
    573     LocationContext *LC = &*I;
    574     ++I;
    575     delete LC;
    576   }
    577 
    578   Contexts.clear();
    579 }
    580 
    581