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