1 files changed, 182 insertions, 0 deletions
diff --git a/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp b/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
new file mode 100644
index 00000000000..02d4a0bdd1f
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/utils/ExprSequence.cpp
@@ -0,0 +1,182 @@
+//===---------- ExprSequence.cpp - clang-tidy -----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ExprSequence.h"
+
+namespace clang {
+namespace tidy {
+namespace utils {
+
+// Returns the Stmt nodes that are parents of 'S', skipping any potential
+// intermediate non-Stmt nodes.
+//
+// In almost all cases, this function returns a single parent or no parents at
+// all.
+//
+// The case that a Stmt has multiple parents is rare but does actually occur in
+// the parts of the AST that we're interested in. Specifically, InitListExpr
+// nodes cause ASTContext::getParent() to return multiple parents for certain
+// nodes in their subtree because RecursiveASTVisitor visits both the syntactic
+// and semantic forms of InitListExpr, and the parent-child relationships are
+// different between the two forms.
+static SmallVector<const Stmt *, 1> getParentStmts(const Stmt *S,
+                                                   ASTContext *Context) {
+  SmallVector<const Stmt *, 1> Result;
+
+  ASTContext::DynTypedNodeList Parents = Context->getParents(*S);
+
+  SmallVector<ast_type_traits::DynTypedNode, 1> NodesToProcess(Parents.begin(),
+                                                               Parents.end());
+
+  while (!NodesToProcess.empty()) {
+    ast_type_traits::DynTypedNode Node = NodesToProcess.back();
+    NodesToProcess.pop_back();
+
+    if (const auto *S = Node.get<Stmt>()) {
+      Result.push_back(S);
+    } else {
+      Parents = Context->getParents(Node);
+      NodesToProcess.append(Parents.begin(), Parents.end());
+    }
+  }
+
+  return Result;
+}
+
+namespace {
+bool isDescendantOrEqual(const Stmt *Descendant, const Stmt *Ancestor,
+                         ASTContext *Context) {
+  if (Descendant == Ancestor)
+    return true;
+  for (const Stmt *Parent : getParentStmts(Descendant, Context)) {
+    if (isDescendantOrEqual(Parent, Ancestor, Context))
+      return true;
+  }
+
+  return false;
+}
+}
+
+ExprSequence::ExprSequence(const CFG *TheCFG, ASTContext *TheContext)
+    : Context(TheContext) {
+  for (const auto &SyntheticStmt : TheCFG->synthetic_stmts()) {
+    SyntheticStmtSourceMap[SyntheticStmt.first] = SyntheticStmt.second;
+  }
+}
+
+bool ExprSequence::inSequence(const Stmt *Before, const Stmt *After) const {
+  Before = resolveSyntheticStmt(Before);
+  After = resolveSyntheticStmt(After);
+
+  // If 'After' is in the subtree of the siblings that follow 'Before' in the
+  // chain of successors, we know that 'After' is sequenced after 'Before'.
+  for (const Stmt *Successor = getSequenceSuccessor(Before); Successor;
+       Successor = getSequenceSuccessor(Successor)) {
+    if (isDescendantOrEqual(After, Successor, Context))
+      return true;
+  }
+
+  // If 'After' is a parent of 'Before' or is sequenced after one of these
+  // parents, we know that it is sequenced after 'Before'.
+  for (const Stmt *Parent : getParentStmts(Before, Context)) {
+    if (Parent == After || inSequence(Parent, After))
+      return true;
+  }
+
+  return false;
+}
+
+bool ExprSequence::potentiallyAfter(const Stmt *After,
+                                    const Stmt *Before) const {
+  return !inSequence(After, Before);
+}
+
+const Stmt *ExprSequence::getSequenceSuccessor(const Stmt *S) const {
+  for (const Stmt *Parent : getParentStmts(S, Context)) {
+    if (const auto *BO = dyn_cast<BinaryOperator>(Parent)) {
+      // Comma operator: Right-hand side is sequenced after the left-hand side.
+      if (BO->getLHS() == S && BO->getOpcode() == BO_Comma)
+        return BO->getRHS();
+    } else if (const auto *InitList = dyn_cast<InitListExpr>(Parent)) {
+      // Initializer list: Each initializer clause is sequenced after the
+      // clauses that precede it.
+      for (unsigned I = 1; I < InitList->getNumInits(); ++I) {
+        if (InitList->getInit(I - 1) == S)
+          return InitList->getInit(I);
+      }
+    } else if (const auto *Compound = dyn_cast<CompoundStmt>(Parent)) {
+      // Compound statement: Each sub-statement is sequenced after the
+      // statements that precede it.
+      const Stmt *Previous = nullptr;
+      for (const auto *Child : Compound->body()) {
+        if (Previous == S)
+          return Child;
+        Previous = Child;
+      }
+    } else if (const auto *TheDeclStmt = dyn_cast<DeclStmt>(Parent)) {
+      // Declaration: Every initializer expression is sequenced after the
+      // initializer expressions that precede it.
+      const Expr *PreviousInit = nullptr;
+      for (const Decl *TheDecl : TheDeclStmt->decls()) {
+        if (const auto *TheVarDecl = dyn_cast<VarDecl>(TheDecl)) {
+          if (const Expr *Init = TheVarDecl->getInit()) {
+            if (PreviousInit == S)
+              return Init;
+            PreviousInit = Init;
+          }
+        }
+      }
+    } else if (const auto *ForRange = dyn_cast<CXXForRangeStmt>(Parent)) {
+      // Range-based for: Loop variable declaration is sequenced before the
+      // body. (We need this rule because these get placed in the same
+      // CFGBlock.)
+      if (S == ForRange->getLoopVarStmt())
+        return ForRange->getBody();
+    } else if (const auto *TheIfStmt = dyn_cast<IfStmt>(Parent)) {
+      // If statement: If a variable is declared inside the condition, the
+      // expression used to initialize the variable is sequenced before the
+      // evaluation of the condition.
+      if (S == TheIfStmt->getConditionVariableDeclStmt())
+        return TheIfStmt->getCond();
+    }
+  }
+
+  return nullptr;
+}
+
+const Stmt *ExprSequence::resolveSyntheticStmt(const Stmt *S) const {
+  if (SyntheticStmtSourceMap.count(S))
+    return SyntheticStmtSourceMap.lookup(S);
+  return S;
+}
+
+StmtToBlockMap::StmtToBlockMap(const CFG *TheCFG, ASTContext *TheContext)
+    : Context(TheContext) {
+  for (const auto *B : *TheCFG) {
+    for (const auto &Elem : *B) {
+      if (Optional<CFGStmt> S = Elem.getAs<CFGStmt>())
+        Map[S->getStmt()] = B;
+    }
+  }
+}
+
+const CFGBlock *StmtToBlockMap::blockContainingStmt(const Stmt *S) const {
+  while (!Map.count(S)) {
+    SmallVector<const Stmt *, 1> Parents = getParentStmts(S, Context);
+    if (Parents.empty())
+      return nullptr;
+    S = Parents[0];
+  }
+
+  return Map.lookup(S);
+}
+
+} // namespace utils
+} // namespace tidy
+} // namespace clang