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      1 //===--- ScopeInfo.cpp - Information about a semantic context -------------===//
      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 implements FunctionScopeInfo and its subclasses, which contain
     11 // information about a single function, block, lambda, or method body.
     12 //
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "clang/Sema/ScopeInfo.h"
     16 #include "clang/AST/Decl.h"
     17 #include "clang/AST/DeclObjC.h"
     18 #include "clang/AST/Expr.h"
     19 #include "clang/AST/ExprCXX.h"
     20 #include "clang/AST/ExprObjC.h"
     21 
     22 using namespace clang;
     23 using namespace sema;
     24 
     25 void FunctionScopeInfo::Clear() {
     26   HasBranchProtectedScope = false;
     27   HasBranchIntoScope = false;
     28   HasIndirectGoto = false;
     29 
     30   SwitchStack.clear();
     31   Returns.clear();
     32   ErrorTrap.reset();
     33   PossiblyUnreachableDiags.clear();
     34   WeakObjectUses.clear();
     35 }
     36 
     37 static const NamedDecl *getBestPropertyDecl(const ObjCPropertyRefExpr *PropE) {
     38   if (PropE->isExplicitProperty())
     39     return PropE->getExplicitProperty();
     40 
     41   return PropE->getImplicitPropertyGetter();
     42 }
     43 
     44 FunctionScopeInfo::WeakObjectProfileTy::BaseInfoTy
     45 FunctionScopeInfo::WeakObjectProfileTy::getBaseInfo(const Expr *E) {
     46   E = E->IgnoreParenCasts();
     47 
     48   const NamedDecl *D = 0;
     49   bool IsExact = false;
     50 
     51   switch (E->getStmtClass()) {
     52   case Stmt::DeclRefExprClass:
     53     D = cast<DeclRefExpr>(E)->getDecl();
     54     IsExact = isa<VarDecl>(D);
     55     break;
     56   case Stmt::MemberExprClass: {
     57     const MemberExpr *ME = cast<MemberExpr>(E);
     58     D = ME->getMemberDecl();
     59     IsExact = isa<CXXThisExpr>(ME->getBase()->IgnoreParenImpCasts());
     60     break;
     61   }
     62   case Stmt::ObjCIvarRefExprClass: {
     63     const ObjCIvarRefExpr *IE = cast<ObjCIvarRefExpr>(E);
     64     D = IE->getDecl();
     65     IsExact = IE->getBase()->isObjCSelfExpr();
     66     break;
     67   }
     68   case Stmt::PseudoObjectExprClass: {
     69     const PseudoObjectExpr *POE = cast<PseudoObjectExpr>(E);
     70     const ObjCPropertyRefExpr *BaseProp =
     71       dyn_cast<ObjCPropertyRefExpr>(POE->getSyntacticForm());
     72     if (BaseProp) {
     73       D = getBestPropertyDecl(BaseProp);
     74 
     75       const Expr *DoubleBase = BaseProp->getBase();
     76       if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(DoubleBase))
     77         DoubleBase = OVE->getSourceExpr();
     78 
     79       IsExact = DoubleBase->isObjCSelfExpr();
     80     }
     81     break;
     82   }
     83   default:
     84     break;
     85   }
     86 
     87   return BaseInfoTy(D, IsExact);
     88 }
     89 
     90 
     91 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
     92                                           const ObjCPropertyRefExpr *PropE)
     93     : Base(0, true), Property(getBestPropertyDecl(PropE)) {
     94 
     95   if (PropE->isObjectReceiver()) {
     96     const OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(PropE->getBase());
     97     const Expr *E = OVE->getSourceExpr();
     98     Base = getBaseInfo(E);
     99   } else if (PropE->isClassReceiver()) {
    100     Base.setPointer(PropE->getClassReceiver());
    101   } else {
    102     assert(PropE->isSuperReceiver());
    103   }
    104 }
    105 
    106 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(const Expr *BaseE,
    107                                                 const ObjCPropertyDecl *Prop)
    108     : Base(0, true), Property(Prop) {
    109   if (BaseE)
    110     Base = getBaseInfo(BaseE);
    111   // else, this is a message accessing a property on super.
    112 }
    113 
    114 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
    115                                                       const DeclRefExpr *DRE)
    116   : Base(0, true), Property(DRE->getDecl()) {
    117   assert(isa<VarDecl>(Property));
    118 }
    119 
    120 FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
    121                                                   const ObjCIvarRefExpr *IvarE)
    122   : Base(getBaseInfo(IvarE->getBase())), Property(IvarE->getDecl()) {
    123 }
    124 
    125 void FunctionScopeInfo::recordUseOfWeak(const ObjCMessageExpr *Msg,
    126                                         const ObjCPropertyDecl *Prop) {
    127   assert(Msg && Prop);
    128   WeakUseVector &Uses =
    129     WeakObjectUses[WeakObjectProfileTy(Msg->getInstanceReceiver(), Prop)];
    130   Uses.push_back(WeakUseTy(Msg, Msg->getNumArgs() == 0));
    131 }
    132 
    133 void FunctionScopeInfo::markSafeWeakUse(const Expr *E) {
    134   E = E->IgnoreParenCasts();
    135 
    136   if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
    137     markSafeWeakUse(POE->getSyntacticForm());
    138     return;
    139   }
    140 
    141   if (const ConditionalOperator *Cond = dyn_cast<ConditionalOperator>(E)) {
    142     markSafeWeakUse(Cond->getTrueExpr());
    143     markSafeWeakUse(Cond->getFalseExpr());
    144     return;
    145   }
    146 
    147   if (const BinaryConditionalOperator *Cond =
    148         dyn_cast<BinaryConditionalOperator>(E)) {
    149     markSafeWeakUse(Cond->getCommon());
    150     markSafeWeakUse(Cond->getFalseExpr());
    151     return;
    152   }
    153 
    154   // Has this weak object been seen before?
    155   FunctionScopeInfo::WeakObjectUseMap::iterator Uses;
    156   if (const ObjCPropertyRefExpr *RefExpr = dyn_cast<ObjCPropertyRefExpr>(E))
    157     Uses = WeakObjectUses.find(WeakObjectProfileTy(RefExpr));
    158   else if (const ObjCIvarRefExpr *IvarE = dyn_cast<ObjCIvarRefExpr>(E))
    159     Uses = WeakObjectUses.find(WeakObjectProfileTy(IvarE));
    160   else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
    161     Uses = WeakObjectUses.find(WeakObjectProfileTy(DRE));
    162   else if (const ObjCMessageExpr *MsgE = dyn_cast<ObjCMessageExpr>(E)) {
    163     Uses = WeakObjectUses.end();
    164     if (const ObjCMethodDecl *MD = MsgE->getMethodDecl()) {
    165       if (const ObjCPropertyDecl *Prop = MD->findPropertyDecl()) {
    166         Uses =
    167           WeakObjectUses.find(WeakObjectProfileTy(MsgE->getInstanceReceiver(),
    168                                                   Prop));
    169       }
    170     }
    171   }
    172   else
    173     return;
    174 
    175   if (Uses == WeakObjectUses.end())
    176     return;
    177 
    178   // Has there been a read from the object using this Expr?
    179   FunctionScopeInfo::WeakUseVector::reverse_iterator ThisUse =
    180     std::find(Uses->second.rbegin(), Uses->second.rend(), WeakUseTy(E, true));
    181   if (ThisUse == Uses->second.rend())
    182     return;
    183 
    184   ThisUse->markSafe();
    185 }
    186 
    187 FunctionScopeInfo::~FunctionScopeInfo() { }
    188 BlockScopeInfo::~BlockScopeInfo() { }
    189 LambdaScopeInfo::~LambdaScopeInfo() { }
    190 CapturedRegionScopeInfo::~CapturedRegionScopeInfo() { }
    191