1 //===--- ParentMap.cpp - Mappings from Stmts to their Parents ---*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 //  This file defines the ParentMap class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "clang/AST/ParentMap.h"
14 #include "clang/AST/Decl.h"
15 #include "clang/AST/Expr.h"
16 #include "clang/AST/ExprCXX.h"
17 #include "clang/AST/StmtObjC.h"
18 #include "llvm/ADT/DenseMap.h"
19 
20 using namespace clang;
21 
22 typedef llvm::DenseMap<Stmt*, Stmt*> MapTy;
23 
24 enum OpaqueValueMode {
25   OV_Transparent,
26   OV_Opaque
27 };
28 
29 static void BuildParentMap(MapTy& M, Stmt* S,
30                            OpaqueValueMode OVMode = OV_Transparent) {
31   if (!S)
32     return;
33 
34   switch (S->getStmtClass()) {
35   case Stmt::PseudoObjectExprClass: {
36     PseudoObjectExpr *POE = cast<PseudoObjectExpr>(S);
37 
38     if (OVMode == OV_Opaque && M[POE->getSyntacticForm()])
39       break;
40 
41     // If we are rebuilding the map, clear out any existing state.
42     if (M[POE->getSyntacticForm()])
43       for (Stmt *SubStmt : S->children())
44         M[SubStmt] = nullptr;
45 
46     M[POE->getSyntacticForm()] = S;
47     BuildParentMap(M, POE->getSyntacticForm(), OV_Transparent);
48 
49     for (PseudoObjectExpr::semantics_iterator I = POE->semantics_begin(),
50                                               E = POE->semantics_end();
51          I != E; ++I) {
52       M[*I] = S;
53       BuildParentMap(M, *I, OV_Opaque);
54     }
55     break;
56   }
57   case Stmt::BinaryConditionalOperatorClass: {
58     assert(OVMode == OV_Transparent && "Should not appear alongside OVEs");
59     BinaryConditionalOperator *BCO = cast<BinaryConditionalOperator>(S);
60 
61     M[BCO->getCommon()] = S;
62     BuildParentMap(M, BCO->getCommon(), OV_Transparent);
63 
64     M[BCO->getCond()] = S;
65     BuildParentMap(M, BCO->getCond(), OV_Opaque);
66 
67     M[BCO->getTrueExpr()] = S;
68     BuildParentMap(M, BCO->getTrueExpr(), OV_Opaque);
69 
70     M[BCO->getFalseExpr()] = S;
71     BuildParentMap(M, BCO->getFalseExpr(), OV_Transparent);
72 
73     break;
74   }
75   case Stmt::OpaqueValueExprClass: {
76     // FIXME: This isn't correct; it assumes that multiple OpaqueValueExprs
77     // share a single source expression, but in the AST a single
78     // OpaqueValueExpr is shared among multiple parent expressions.
79     // The right thing to do is to give the OpaqueValueExpr its syntactic
80     // parent, then not reassign that when traversing the semantic expressions.
81     OpaqueValueExpr *OVE = cast<OpaqueValueExpr>(S);
82     if (OVMode == OV_Transparent || !M[OVE->getSourceExpr()]) {
83       M[OVE->getSourceExpr()] = S;
84       BuildParentMap(M, OVE->getSourceExpr(), OV_Transparent);
85     }
86     break;
87   }
88   case Stmt::CapturedStmtClass:
89     for (Stmt *SubStmt : S->children()) {
90       if (SubStmt) {
91         M[SubStmt] = S;
92         BuildParentMap(M, SubStmt, OVMode);
93       }
94     }
95     if (Stmt *SubStmt = cast<CapturedStmt>(S)->getCapturedStmt()) {
96       M[SubStmt] = S;
97       BuildParentMap(M, SubStmt, OVMode);
98     }
99     break;
100   default:
101     for (Stmt *SubStmt : S->children()) {
102       if (SubStmt) {
103         M[SubStmt] = S;
104         BuildParentMap(M, SubStmt, OVMode);
105       }
106     }
107     break;
108   }
109 }
110 
111 ParentMap::ParentMap(Stmt *S) : Impl(nullptr) {
112   if (S) {
113     MapTy *M = new MapTy();
114     BuildParentMap(*M, S);
115     Impl = M;
116   }
117 }
118 
119 ParentMap::~ParentMap() {
120   delete (MapTy*) Impl;
121 }
122 
123 void ParentMap::addStmt(Stmt* S) {
124   if (S) {
125     BuildParentMap(*(MapTy*) Impl, S);
126   }
127 }
128 
129 void ParentMap::setParent(const Stmt *S, const Stmt *Parent) {
130   assert(S);
131   assert(Parent);
132   MapTy *M = reinterpret_cast<MapTy *>(Impl);
133   M->insert(std::make_pair(const_cast<Stmt *>(S), const_cast<Stmt *>(Parent)));
134 }
135 
136 Stmt* ParentMap::getParent(Stmt* S) const {
137   MapTy* M = (MapTy*) Impl;
138   return M->lookup(S);
139 }
140 
141 Stmt *ParentMap::getParentIgnoreParens(Stmt *S) const {
142   do { S = getParent(S); } while (S && isa<ParenExpr>(S));
143   return S;
144 }
145 
146 Stmt *ParentMap::getParentIgnoreParenCasts(Stmt *S) const {
147   do {
148     S = getParent(S);
149   }
150   while (S && (isa<ParenExpr>(S) || isa<CastExpr>(S)));
151 
152   return S;
153 }
154 
155 Stmt *ParentMap::getParentIgnoreParenImpCasts(Stmt *S) const {
156   do {
157     S = getParent(S);
158   } while (S && isa<Expr>(S) && cast<Expr>(S)->IgnoreParenImpCasts() != S);
159 
160   return S;
161 }
162 
163 Stmt *ParentMap::getOuterParenParent(Stmt *S) const {
164   Stmt *Paren = nullptr;
165   while (isa<ParenExpr>(S)) {
166     Paren = S;
167     S = getParent(S);
168   };
169   return Paren;
170 }
171 
172 bool ParentMap::isConsumedExpr(Expr* E) const {
173   Stmt *P = getParent(E);
174   Stmt *DirectChild = E;
175 
176   // Ignore parents that don't guarantee consumption.
177   while (P && (isa<ParenExpr>(P) || isa<CastExpr>(P) ||
178                isa<FullExpr>(P))) {
179     DirectChild = P;
180     P = getParent(P);
181   }
182 
183   if (!P)
184     return false;
185 
186   switch (P->getStmtClass()) {
187     default:
188       return isa<Expr>(P);
189     case Stmt::DeclStmtClass:
190       return true;
191     case Stmt::BinaryOperatorClass: {
192       BinaryOperator *BE = cast<BinaryOperator>(P);
193       // If it is a comma, only the right side is consumed.
194       // If it isn't a comma, both sides are consumed.
195       return BE->getOpcode()!=BO_Comma ||DirectChild==BE->getRHS();
196     }
197     case Stmt::ForStmtClass:
198       return DirectChild == cast<ForStmt>(P)->getCond();
199     case Stmt::WhileStmtClass:
200       return DirectChild == cast<WhileStmt>(P)->getCond();
201     case Stmt::DoStmtClass:
202       return DirectChild == cast<DoStmt>(P)->getCond();
203     case Stmt::IfStmtClass:
204       return DirectChild == cast<IfStmt>(P)->getCond();
205     case Stmt::IndirectGotoStmtClass:
206       return DirectChild == cast<IndirectGotoStmt>(P)->getTarget();
207     case Stmt::SwitchStmtClass:
208       return DirectChild == cast<SwitchStmt>(P)->getCond();
209     case Stmt::ObjCForCollectionStmtClass:
210       return DirectChild == cast<ObjCForCollectionStmt>(P)->getCollection();
211     case Stmt::ReturnStmtClass:
212       return true;
213   }
214 }
215 
216