clang-tools  15.0.0git
ExprSequence.cpp
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1 //===---------- ExprSequence.cpp - clang-tidy -----------------------------===//
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 #include "ExprSequence.h"
10 #include "clang/AST/ParentMapContext.h"
11 
12 namespace clang {
13 namespace tidy {
14 namespace utils {
15 
16 // Returns the Stmt nodes that are parents of 'S', skipping any potential
17 // intermediate non-Stmt nodes.
18 //
19 // In almost all cases, this function returns a single parent or no parents at
20 // all.
21 //
22 // The case that a Stmt has multiple parents is rare but does actually occur in
23 // the parts of the AST that we're interested in. Specifically, InitListExpr
24 // nodes cause ASTContext::getParent() to return multiple parents for certain
25 // nodes in their subtree because RecursiveASTVisitor visits both the syntactic
26 // and semantic forms of InitListExpr, and the parent-child relationships are
27 // different between the two forms.
28 static SmallVector<const Stmt *, 1> getParentStmts(const Stmt *S,
29  ASTContext *Context) {
30  SmallVector<const Stmt *, 1> Result;
31 
32  TraversalKindScope RAII(*Context, TK_AsIs);
33  DynTypedNodeList Parents = Context->getParents(*S);
34 
35  SmallVector<DynTypedNode, 1> NodesToProcess(Parents.begin(), Parents.end());
36 
37  while (!NodesToProcess.empty()) {
38  DynTypedNode Node = NodesToProcess.back();
39  NodesToProcess.pop_back();
40 
41  if (const auto *S = Node.get<Stmt>()) {
42  Result.push_back(S);
43  } else {
44  Parents = Context->getParents(Node);
45  NodesToProcess.append(Parents.begin(), Parents.end());
46  }
47  }
48 
49  return Result;
50 }
51 
52 namespace {
53 bool isDescendantOrEqual(const Stmt *Descendant, const Stmt *Ancestor,
54  ASTContext *Context) {
55  if (Descendant == Ancestor)
56  return true;
57  for (const Stmt *Parent : getParentStmts(Descendant, Context)) {
58  if (isDescendantOrEqual(Parent, Ancestor, Context))
59  return true;
60  }
61 
62  return false;
63 }
64 } // namespace
65 
66 ExprSequence::ExprSequence(const CFG *TheCFG, const Stmt *Root,
67  ASTContext *TheContext)
68  : Context(TheContext), Root(Root) {
69  for (const auto &SyntheticStmt : TheCFG->synthetic_stmts()) {
70  SyntheticStmtSourceMap[SyntheticStmt.first] = SyntheticStmt.second;
71  }
72 }
73 
74 bool ExprSequence::inSequence(const Stmt *Before, const Stmt *After) const {
75  Before = resolveSyntheticStmt(Before);
76  After = resolveSyntheticStmt(After);
77 
78  // If 'After' is in the subtree of the siblings that follow 'Before' in the
79  // chain of successors, we know that 'After' is sequenced after 'Before'.
80  for (const Stmt *Successor = getSequenceSuccessor(Before); Successor;
81  Successor = getSequenceSuccessor(Successor)) {
82  if (isDescendantOrEqual(After, Successor, Context))
83  return true;
84  }
85 
86  // If 'After' is a parent of 'Before' or is sequenced after one of these
87  // parents, we know that it is sequenced after 'Before'.
88  for (const Stmt *Parent : getParentStmts(Before, Context)) {
89  if (Parent == After || inSequence(Parent, After))
90  return true;
91  }
92 
93  return false;
94 }
95 
96 bool ExprSequence::potentiallyAfter(const Stmt *After,
97  const Stmt *Before) const {
98  return !inSequence(After, Before);
99 }
100 
101 const Stmt *ExprSequence::getSequenceSuccessor(const Stmt *S) const {
102  for (const Stmt *Parent : getParentStmts(S, Context)) {
103  // If a statement has multiple parents, make sure we're using the parent
104  // that lies within the sub-tree under Root.
105  if (!isDescendantOrEqual(Parent, Root, Context))
106  continue;
107 
108  if (const auto *BO = dyn_cast<BinaryOperator>(Parent)) {
109  // Comma operator: Right-hand side is sequenced after the left-hand side.
110  if (BO->getLHS() == S && BO->getOpcode() == BO_Comma)
111  return BO->getRHS();
112  } else if (const auto *InitList = dyn_cast<InitListExpr>(Parent)) {
113  // Initializer list: Each initializer clause is sequenced after the
114  // clauses that precede it.
115  for (unsigned I = 1; I < InitList->getNumInits(); ++I) {
116  if (InitList->getInit(I - 1) == S)
117  return InitList->getInit(I);
118  }
119  } else if (const auto *Compound = dyn_cast<CompoundStmt>(Parent)) {
120  // Compound statement: Each sub-statement is sequenced after the
121  // statements that precede it.
122  const Stmt *Previous = nullptr;
123  for (const auto *Child : Compound->body()) {
124  if (Previous == S)
125  return Child;
126  Previous = Child;
127  }
128  } else if (const auto *TheDeclStmt = dyn_cast<DeclStmt>(Parent)) {
129  // Declaration: Every initializer expression is sequenced after the
130  // initializer expressions that precede it.
131  const Expr *PreviousInit = nullptr;
132  for (const Decl *TheDecl : TheDeclStmt->decls()) {
133  if (const auto *TheVarDecl = dyn_cast<VarDecl>(TheDecl)) {
134  if (const Expr *Init = TheVarDecl->getInit()) {
135  if (PreviousInit == S)
136  return Init;
137  PreviousInit = Init;
138  }
139  }
140  }
141  } else if (const auto *ForRange = dyn_cast<CXXForRangeStmt>(Parent)) {
142  // Range-based for: Loop variable declaration is sequenced before the
143  // body. (We need this rule because these get placed in the same
144  // CFGBlock.)
145  if (S == ForRange->getLoopVarStmt())
146  return ForRange->getBody();
147  } else if (const auto *TheIfStmt = dyn_cast<IfStmt>(Parent)) {
148  // If statement:
149  // - Sequence init statement before variable declaration, if present;
150  // before condition evaluation, otherwise.
151  // - Sequence variable declaration (along with the expression used to
152  // initialize it) before the evaluation of the condition.
153  if (S == TheIfStmt->getInit()) {
154  if (TheIfStmt->getConditionVariableDeclStmt() != nullptr)
155  return TheIfStmt->getConditionVariableDeclStmt();
156  return TheIfStmt->getCond();
157  }
158  if (S == TheIfStmt->getConditionVariableDeclStmt())
159  return TheIfStmt->getCond();
160  } else if (const auto *TheSwitchStmt = dyn_cast<SwitchStmt>(Parent)) {
161  // Ditto for switch statements.
162  if (S == TheSwitchStmt->getInit()) {
163  if (TheSwitchStmt->getConditionVariableDeclStmt() != nullptr)
164  return TheSwitchStmt->getConditionVariableDeclStmt();
165  return TheSwitchStmt->getCond();
166  }
167  if (S == TheSwitchStmt->getConditionVariableDeclStmt())
168  return TheSwitchStmt->getCond();
169  } else if (const auto *TheWhileStmt = dyn_cast<WhileStmt>(Parent)) {
170  // While statement: Sequence variable declaration (along with the
171  // expression used to initialize it) before the evaluation of the
172  // condition.
173  if (S == TheWhileStmt->getConditionVariableDeclStmt())
174  return TheWhileStmt->getCond();
175  }
176  }
177 
178  return nullptr;
179 }
180 
181 const Stmt *ExprSequence::resolveSyntheticStmt(const Stmt *S) const {
182  if (SyntheticStmtSourceMap.count(S))
183  return SyntheticStmtSourceMap.lookup(S);
184  return S;
185 }
186 
187 StmtToBlockMap::StmtToBlockMap(const CFG *TheCFG, ASTContext *TheContext)
188  : Context(TheContext) {
189  for (const auto *B : *TheCFG) {
190  for (const auto &Elem : *B) {
191  if (Optional<CFGStmt> S = Elem.getAs<CFGStmt>())
192  Map[S->getStmt()] = B;
193  }
194  }
195 }
196 
197 const CFGBlock *StmtToBlockMap::blockContainingStmt(const Stmt *S) const {
198  while (!Map.count(S)) {
199  SmallVector<const Stmt *, 1> Parents = getParentStmts(S, Context);
200  if (Parents.empty())
201  return nullptr;
202  S = Parents[0];
203  }
204 
205  return Map.lookup(S);
206 }
207 
208 } // namespace utils
209 } // namespace tidy
210 } // namespace clang
TheDecl
const Decl * TheDecl
Definition: ExtractFunction.cpp:501
Root
ASTNode Root
Definition: DumpAST.cpp:332
clang::tidy::utils::ExprSequence::potentiallyAfter
bool potentiallyAfter(const Stmt *After, const Stmt *Before) const
Returns whether After can potentially be evaluated after Before.
Definition: ExprSequence.cpp:96
clang::tidy::utils::StmtToBlockMap::blockContainingStmt
const CFGBlock * blockContainingStmt(const Stmt *S) const
Returns the block that S is contained in.
Definition: ExprSequence.cpp:197
clang::tidy::utils::StmtToBlockMap::StmtToBlockMap
StmtToBlockMap(const CFG *TheCFG, ASTContext *TheContext)
Initializes the map for the given CFG.
Definition: ExprSequence.cpp:187
clang::tidy::utils::ExprSequence::inSequence
bool inSequence(const Stmt *Before, const Stmt *After) const
Returns whether Before is sequenced before After.
Definition: ExprSequence.cpp:74
Decl
const FunctionDecl * Decl
Definition: AvoidBindCheck.cpp:100
clang::tidy::utils::ExprSequence::ExprSequence
ExprSequence(const CFG *TheCFG, const Stmt *Root, ASTContext *TheContext)
Initializes this ExprSequence with sequence information for the given CFG.
Definition: ExprSequence.cpp:66
Parent
const Node * Parent
Definition: ExtractFunction.cpp:157
ExprSequence.h
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
ns1::ns2::B
@ B
Definition: CategoricalFeature.h:3
clang::tidy::utils::getParentStmts
static SmallVector< const Stmt *, 1 > getParentStmts(const Stmt *S, ASTContext *Context)
Definition: ExprSequence.cpp:28