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
22using namespace clang;
23using namespace sema;
24
25void FunctionScopeInfo::Clear() {
26  HasBranchProtectedScope = false;
27  HasBranchIntoScope = false;
28  HasIndirectGoto = false;
29  HasDroppedStmt = false;
30  ObjCShouldCallSuper = false;
31  ObjCIsDesignatedInit = false;
32  ObjCWarnForNoDesignatedInitChain = false;
33  ObjCIsSecondaryInit = false;
34  ObjCWarnForNoInitDelegation = false;
35
36  SwitchStack.clear();
37  Returns.clear();
38  ErrorTrap.reset();
39  PossiblyUnreachableDiags.clear();
40  WeakObjectUses.clear();
41}
42
43static const NamedDecl *getBestPropertyDecl(const ObjCPropertyRefExpr *PropE) {
44  if (PropE->isExplicitProperty())
45    return PropE->getExplicitProperty();
46
47  return PropE->getImplicitPropertyGetter();
48}
49
50FunctionScopeInfo::WeakObjectProfileTy::BaseInfoTy
51FunctionScopeInfo::WeakObjectProfileTy::getBaseInfo(const Expr *E) {
52  E = E->IgnoreParenCasts();
53
54  const NamedDecl *D = nullptr;
55  bool IsExact = false;
56
57  switch (E->getStmtClass()) {
58  case Stmt::DeclRefExprClass:
59    D = cast<DeclRefExpr>(E)->getDecl();
60    IsExact = isa<VarDecl>(D);
61    break;
62  case Stmt::MemberExprClass: {
63    const MemberExpr *ME = cast<MemberExpr>(E);
64    D = ME->getMemberDecl();
65    IsExact = isa<CXXThisExpr>(ME->getBase()->IgnoreParenImpCasts());
66    break;
67  }
68  case Stmt::ObjCIvarRefExprClass: {
69    const ObjCIvarRefExpr *IE = cast<ObjCIvarRefExpr>(E);
70    D = IE->getDecl();
71    IsExact = IE->getBase()->isObjCSelfExpr();
72    break;
73  }
74  case Stmt::PseudoObjectExprClass: {
75    const PseudoObjectExpr *POE = cast<PseudoObjectExpr>(E);
76    const ObjCPropertyRefExpr *BaseProp =
77      dyn_cast<ObjCPropertyRefExpr>(POE->getSyntacticForm());
78    if (BaseProp) {
79      D = getBestPropertyDecl(BaseProp);
80
81      const Expr *DoubleBase = BaseProp->getBase();
82      if (const OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(DoubleBase))
83        DoubleBase = OVE->getSourceExpr();
84
85      IsExact = DoubleBase->isObjCSelfExpr();
86    }
87    break;
88  }
89  default:
90    break;
91  }
92
93  return BaseInfoTy(D, IsExact);
94}
95
96FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
97                                          const ObjCPropertyRefExpr *PropE)
98    : Base(nullptr, true), Property(getBestPropertyDecl(PropE)) {
99
100  if (PropE->isObjectReceiver()) {
101    const OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(PropE->getBase());
102    const Expr *E = OVE->getSourceExpr();
103    Base = getBaseInfo(E);
104  } else if (PropE->isClassReceiver()) {
105    Base.setPointer(PropE->getClassReceiver());
106  } else {
107    assert(PropE->isSuperReceiver());
108  }
109}
110
111FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(const Expr *BaseE,
112                                                const ObjCPropertyDecl *Prop)
113    : Base(nullptr, true), Property(Prop) {
114  if (BaseE)
115    Base = getBaseInfo(BaseE);
116  // else, this is a message accessing a property on super.
117}
118
119FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
120                                                      const DeclRefExpr *DRE)
121  : Base(nullptr, true), Property(DRE->getDecl()) {
122  assert(isa<VarDecl>(Property));
123}
124
125FunctionScopeInfo::WeakObjectProfileTy::WeakObjectProfileTy(
126                                                  const ObjCIvarRefExpr *IvarE)
127  : Base(getBaseInfo(IvarE->getBase())), Property(IvarE->getDecl()) {
128}
129
130void FunctionScopeInfo::recordUseOfWeak(const ObjCMessageExpr *Msg,
131                                        const ObjCPropertyDecl *Prop) {
132  assert(Msg && Prop);
133  WeakUseVector &Uses =
134    WeakObjectUses[WeakObjectProfileTy(Msg->getInstanceReceiver(), Prop)];
135  Uses.push_back(WeakUseTy(Msg, Msg->getNumArgs() == 0));
136}
137
138void FunctionScopeInfo::markSafeWeakUse(const Expr *E) {
139  E = E->IgnoreParenCasts();
140
141  if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
142    markSafeWeakUse(POE->getSyntacticForm());
143    return;
144  }
145
146  if (const ConditionalOperator *Cond = dyn_cast<ConditionalOperator>(E)) {
147    markSafeWeakUse(Cond->getTrueExpr());
148    markSafeWeakUse(Cond->getFalseExpr());
149    return;
150  }
151
152  if (const BinaryConditionalOperator *Cond =
153        dyn_cast<BinaryConditionalOperator>(E)) {
154    markSafeWeakUse(Cond->getCommon());
155    markSafeWeakUse(Cond->getFalseExpr());
156    return;
157  }
158
159  // Has this weak object been seen before?
160  FunctionScopeInfo::WeakObjectUseMap::iterator Uses;
161  if (const ObjCPropertyRefExpr *RefExpr = dyn_cast<ObjCPropertyRefExpr>(E)) {
162    if (isa<OpaqueValueExpr>(RefExpr->getBase()))
163     Uses = WeakObjectUses.find(WeakObjectProfileTy(RefExpr));
164    else {
165      markSafeWeakUse(RefExpr->getBase());
166      return;
167    }
168  }
169  else if (const ObjCIvarRefExpr *IvarE = dyn_cast<ObjCIvarRefExpr>(E))
170    Uses = WeakObjectUses.find(WeakObjectProfileTy(IvarE));
171  else if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
172    Uses = WeakObjectUses.find(WeakObjectProfileTy(DRE));
173  else if (const ObjCMessageExpr *MsgE = dyn_cast<ObjCMessageExpr>(E)) {
174    Uses = WeakObjectUses.end();
175    if (const ObjCMethodDecl *MD = MsgE->getMethodDecl()) {
176      if (const ObjCPropertyDecl *Prop = MD->findPropertyDecl()) {
177        Uses =
178          WeakObjectUses.find(WeakObjectProfileTy(MsgE->getInstanceReceiver(),
179                                                  Prop));
180      }
181    }
182  }
183  else
184    return;
185
186  if (Uses == WeakObjectUses.end())
187    return;
188
189  // Has there been a read from the object using this Expr?
190  FunctionScopeInfo::WeakUseVector::reverse_iterator ThisUse =
191    std::find(Uses->second.rbegin(), Uses->second.rend(), WeakUseTy(E, true));
192  if (ThisUse == Uses->second.rend())
193    return;
194
195  ThisUse->markSafe();
196}
197
198void LambdaScopeInfo::getPotentialVariableCapture(unsigned Idx, VarDecl *&VD,
199                                                  Expr *&E) const {
200  assert(Idx < getNumPotentialVariableCaptures() &&
201         "Index of potential capture must be within 0 to less than the "
202         "number of captures!");
203  E = PotentiallyCapturingExprs[Idx];
204  if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
205    VD = dyn_cast<VarDecl>(DRE->getFoundDecl());
206  else if (MemberExpr *ME = dyn_cast<MemberExpr>(E))
207    VD = dyn_cast<VarDecl>(ME->getMemberDecl());
208  else
209    llvm_unreachable("Only DeclRefExprs or MemberExprs should be added for "
210    "potential captures");
211  assert(VD);
212}
213
214FunctionScopeInfo::~FunctionScopeInfo() { }
215BlockScopeInfo::~BlockScopeInfo() { }
216LambdaScopeInfo::~LambdaScopeInfo() { }
217CapturedRegionScopeInfo::~CapturedRegionScopeInfo() { }
218