forked from OSchip/llvm-project
1137 lines
43 KiB
C++
1137 lines
43 KiB
C++
//===-- LoopConvert/LoopActions.cpp - C++11 For loop migration ------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// \brief This file defines matchers and callbacks for use in migrating C++
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/// for loops.
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///
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//===----------------------------------------------------------------------===//
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#include "LoopActions.h"
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#include "LoopMatchers.h"
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#include "VariableNaming.h"
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#include "clang/Lex/Lexer.h"
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using namespace clang::ast_matchers;
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using namespace clang::tooling;
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using namespace clang;
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/// \brief The information needed to describe a valid convertible usage
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/// of an array index or iterator.
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struct Usage {
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const Expr *E;
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bool IsArrow;
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SourceRange Range;
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explicit Usage(const Expr *E)
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: E(E), IsArrow(false), Range(E->getSourceRange()) { }
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Usage(const Expr *E, bool IsArrow, SourceRange Range)
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: E(E), IsArrow(IsArrow), Range(Range) { }
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};
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/// \brief A class to encapsulate lowering of the tool's confidence level.
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///
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/// Confidence is a quantity opposite in meaning to Risk. Since clang-modernize
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/// uses risk, this class reverses the meaning for the legacy loop convert
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/// code.
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class Confidence {
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public:
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/// \brief Initialize confidence level.
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explicit Confidence(RiskLevel Level) :
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CurrentLevel(Level) {}
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/// \brief Lower the internal confidence level to Level, but do not raise it.
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void lowerTo(RiskLevel Level) {
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CurrentLevel = std::max(Level, CurrentLevel);
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}
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/// \brief Return the internal confidence level.
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RiskLevel getRiskLevel() const { return CurrentLevel; }
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private:
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RiskLevel CurrentLevel;
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};
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/// \brief Discover usages of expressions consisting of index or iterator
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/// access.
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///
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/// Given an index variable, recursively crawls a for loop to discover if the
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/// index variable is used in a way consistent with range-based for loop access.
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class ForLoopIndexUseVisitor
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: public RecursiveASTVisitor<ForLoopIndexUseVisitor> {
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public:
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ForLoopIndexUseVisitor(ASTContext *Context, const VarDecl *IndexVar,
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const VarDecl *EndVar, const Expr *ContainerExpr,
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const Expr *ArrayBoundExpr,
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bool ContainerNeedsDereference) :
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Context(Context), IndexVar(IndexVar), EndVar(EndVar),
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ContainerExpr(ContainerExpr), ArrayBoundExpr(ArrayBoundExpr),
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ContainerNeedsDereference(ContainerNeedsDereference),
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OnlyUsedAsIndex(true), AliasDecl(NULL), ConfidenceLevel(RL_Safe),
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NextStmtParent(NULL), CurrStmtParent(NULL), ReplaceWithAliasUse(false),
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AliasFromForInit(false) {
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if (ContainerExpr) {
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addComponent(ContainerExpr);
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llvm::FoldingSetNodeID ID;
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const Expr *E = ContainerExpr->IgnoreParenImpCasts();
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E->Profile(ID, *Context, true);
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}
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}
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/// \brief Finds all uses of IndexVar in Body, placing all usages in Usages,
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/// and returns true if IndexVar was only used in a way consistent with a
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/// range-based for loop.
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///
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/// The general strategy is to reject any DeclRefExprs referencing IndexVar,
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/// with the exception of certain acceptable patterns.
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/// For arrays, the DeclRefExpr for IndexVar must appear as the index of an
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/// ArraySubscriptExpression. Iterator-based loops may dereference
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/// IndexVar or call methods through operator-> (builtin or overloaded).
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/// Array-like containers may use IndexVar as a parameter to the at() member
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/// function and in overloaded operator[].
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bool findAndVerifyUsages(const Stmt *Body) {
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TraverseStmt(const_cast<Stmt *>(Body));
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return OnlyUsedAsIndex && ContainerExpr;
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}
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/// \brief Add a set of components that we should consider relevant to the
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/// container.
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void addComponents(const ComponentVector &Components) {
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// FIXME: add sort(on ID)+unique to avoid extra work.
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for (ComponentVector::const_iterator I = Components.begin(),
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E = Components.end(); I != E; ++I)
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addComponent(*I);
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}
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/// \brief Accessor for Usages.
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const UsageResult &getUsages() const { return Usages; }
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/// \brief Get the container indexed by IndexVar, if any.
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const Expr *getContainerIndexed() const {
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return ContainerExpr;
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}
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/// \brief Returns the statement declaring the variable created as an alias
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/// for the loop element, if any.
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const DeclStmt *getAliasDecl() const { return AliasDecl; }
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/// \brief Accessor for ConfidenceLevel.
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RiskLevel getRiskLevel() const {
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return ConfidenceLevel.getRiskLevel();
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}
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/// \brief Indicates if the alias declaration was in a place where it cannot
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/// simply be removed but rather replaced with a use of the alias variable.
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/// For example, variables declared in the condition of an if, switch, or for
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/// stmt.
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bool aliasUseRequired() const { return ReplaceWithAliasUse; }
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/// \brief Indicates if the alias declaration came from the init clause of a
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/// nested for loop. SourceRanges provided by Clang for DeclStmts in this
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/// case need to be adjusted.
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bool aliasFromForInit() const { return AliasFromForInit; }
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private:
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/// Typedef used in CRTP functions.
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typedef RecursiveASTVisitor<ForLoopIndexUseVisitor> VisitorBase;
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friend class RecursiveASTVisitor<ForLoopIndexUseVisitor>;
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/// Overriden methods for RecursiveASTVisitor's traversal.
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bool TraverseArraySubscriptExpr(ArraySubscriptExpr *E);
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bool TraverseCXXMemberCallExpr(CXXMemberCallExpr *MemberCall);
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bool TraverseCXXOperatorCallExpr(CXXOperatorCallExpr *OpCall);
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bool TraverseMemberExpr(MemberExpr *Member);
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bool TraverseUnaryDeref(UnaryOperator *Uop);
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bool VisitDeclRefExpr(DeclRefExpr *E);
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bool VisitDeclStmt(DeclStmt *S);
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bool TraverseStmt(Stmt *S);
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/// \brief Add an expression to the list of expressions on which the container
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/// expression depends.
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void addComponent(const Expr *E) {
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llvm::FoldingSetNodeID ID;
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const Expr *Node = E->IgnoreParenImpCasts();
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Node->Profile(ID, *Context, true);
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DependentExprs.push_back(std::make_pair(Node, ID));
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}
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// Input member variables:
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ASTContext *Context;
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/// The index variable's VarDecl.
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const VarDecl *IndexVar;
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/// The loop's 'end' variable, which cannot be mentioned at all.
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const VarDecl *EndVar;
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/// The Expr which refers to the container.
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const Expr *ContainerExpr;
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/// The Expr which refers to the terminating condition for array-based loops.
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const Expr *ArrayBoundExpr;
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bool ContainerNeedsDereference;
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// Output member variables:
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/// A container which holds all usages of IndexVar as the index of
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/// ArraySubscriptExpressions.
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UsageResult Usages;
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bool OnlyUsedAsIndex;
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/// The DeclStmt for an alias to the container element.
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const DeclStmt *AliasDecl;
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Confidence ConfidenceLevel;
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/// \brief A list of expressions on which ContainerExpr depends.
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///
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/// If any of these expressions are encountered outside of an acceptable usage
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/// of the loop element, lower our confidence level.
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llvm::SmallVector<
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std::pair<const Expr *, llvm::FoldingSetNodeID>, 16> DependentExprs;
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/// The parent-in-waiting. Will become the real parent once we traverse down
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/// one level in the AST.
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const Stmt *NextStmtParent;
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/// The actual parent of a node when Visit*() calls are made. Only the
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/// parentage of DeclStmt's to possible iteration/selection statements is of
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/// importance.
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const Stmt *CurrStmtParent;
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/// \see aliasUseRequired().
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bool ReplaceWithAliasUse;
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/// \see aliasFromForInit().
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bool AliasFromForInit;
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};
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/// \brief Obtain the original source code text from a SourceRange.
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static StringRef getStringFromRange(SourceManager &SourceMgr,
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const LangOptions &LangOpts,
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SourceRange Range) {
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if (SourceMgr.getFileID(Range.getBegin()) !=
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SourceMgr.getFileID(Range.getEnd()))
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return NULL;
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CharSourceRange SourceChars(Range, true);
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return Lexer::getSourceText(SourceChars, SourceMgr, LangOpts);
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}
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/// \brief Returns the DeclRefExpr represented by E, or NULL if there isn't one.
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static const DeclRefExpr *getDeclRef(const Expr *E) {
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return dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts());
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}
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/// \brief If the given expression is actually a DeclRefExpr, find and return
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/// the underlying VarDecl; otherwise, return NULL.
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static const VarDecl *getReferencedVariable(const Expr *E) {
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if (const DeclRefExpr *DRE = getDeclRef(E))
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return dyn_cast<VarDecl>(DRE->getDecl());
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return NULL;
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}
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/// \brief Returns true when the given expression is a member expression
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/// whose base is `this` (implicitly or not).
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static bool isDirectMemberExpr(const Expr *E) {
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if (const MemberExpr *Member = dyn_cast<MemberExpr>(E->IgnoreParenImpCasts()))
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return isa<CXXThisExpr>(Member->getBase()->IgnoreParenImpCasts());
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return false;
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}
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/// \brief Returns true when two ValueDecls are the same variable.
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static bool areSameVariable(const ValueDecl *First, const ValueDecl *Second) {
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return First && Second &&
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First->getCanonicalDecl() == Second->getCanonicalDecl();
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}
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/// \brief Determines if an expression is a declaration reference to a
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/// particular variable.
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static bool exprReferencesVariable(const ValueDecl *Target, const Expr *E) {
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if (!Target || !E)
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return false;
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const DeclRefExpr *Decl = getDeclRef(E);
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return Decl && areSameVariable(Target, Decl->getDecl());
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}
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/// \brief Returns true when two Exprs are equivalent.
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static bool areSameExpr(ASTContext *Context, const Expr *First,
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const Expr *Second) {
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if (!First || !Second)
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return false;
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llvm::FoldingSetNodeID FirstID, SecondID;
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First->Profile(FirstID, *Context, true);
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Second->Profile(SecondID, *Context, true);
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return FirstID == SecondID;
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}
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/// \brief Look through conversion/copy constructors to find the explicit
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/// initialization expression, returning it is found.
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///
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/// The main idea is that given
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/// vector<int> v;
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/// we consider either of these initializations
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/// vector<int>::iterator it = v.begin();
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/// vector<int>::iterator it(v.begin());
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/// and retrieve `v.begin()` as the expression used to initialize `it` but do
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/// not include
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/// vector<int>::iterator it;
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/// vector<int>::iterator it(v.begin(), 0); // if this constructor existed
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/// as being initialized from `v.begin()`
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static const Expr *digThroughConstructors(const Expr *E) {
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if (!E)
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return NULL;
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E = E->IgnoreParenImpCasts();
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if (const CXXConstructExpr *ConstructExpr = dyn_cast<CXXConstructExpr>(E)) {
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// The initial constructor must take exactly one parameter, but base class
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// and deferred constructors can take more.
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if (ConstructExpr->getNumArgs() != 1 ||
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ConstructExpr->getConstructionKind() != CXXConstructExpr::CK_Complete)
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return NULL;
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E = ConstructExpr->getArg(0);
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if (const MaterializeTemporaryExpr *Temp =
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dyn_cast<MaterializeTemporaryExpr>(E))
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E = Temp->GetTemporaryExpr();
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return digThroughConstructors(E);
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}
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return E;
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}
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/// \brief If the expression is a dereference or call to operator*(), return the
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/// operand. Otherwise, return NULL.
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static const Expr *getDereferenceOperand(const Expr *E) {
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if (const UnaryOperator *Uop = dyn_cast<UnaryOperator>(E))
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return Uop->getOpcode() == UO_Deref ? Uop->getSubExpr() : NULL;
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if (const CXXOperatorCallExpr *OpCall = dyn_cast<CXXOperatorCallExpr>(E))
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return OpCall->getOperator() == OO_Star && OpCall->getNumArgs() == 1 ?
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OpCall->getArg(0) : NULL;
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return NULL;
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}
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/// \brief Returns true when the Container contains an Expr equivalent to E.
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template<typename ContainerT>
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static bool containsExpr(ASTContext *Context, const ContainerT *Container,
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const Expr *E) {
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llvm::FoldingSetNodeID ID;
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E->Profile(ID, *Context, true);
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for (typename ContainerT::const_iterator I = Container->begin(),
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End = Container->end(); I != End; ++I)
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if (ID == I->second)
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return true;
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return false;
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}
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/// \brief Returns true when the index expression is a declaration reference to
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/// IndexVar.
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///
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/// If the index variable is `index`, this function returns true on
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/// arrayExpression[index];
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/// containerExpression[index];
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/// but not
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/// containerExpression[notIndex];
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static bool isIndexInSubscriptExpr(const Expr *IndexExpr,
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const VarDecl *IndexVar) {
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const DeclRefExpr *Idx = getDeclRef(IndexExpr);
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return Idx && Idx->getType()->isIntegerType()
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&& areSameVariable(IndexVar, Idx->getDecl());
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}
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/// \brief Returns true when the index expression is a declaration reference to
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/// IndexVar, Obj is the same expression as SourceExpr after all parens and
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/// implicit casts are stripped off.
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///
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/// If PermitDeref is true, IndexExpression may
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/// be a dereference (overloaded or builtin operator*).
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///
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/// This function is intended for array-like containers, as it makes sure that
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/// both the container and the index match.
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/// If the loop has index variable `index` and iterates over `container`, then
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/// isIndexInSubscriptExpr returns true for
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/// \code
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/// container[index]
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/// container.at(index)
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/// container->at(index)
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/// \endcode
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/// but not for
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/// \code
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/// container[notIndex]
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/// notContainer[index]
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/// \endcode
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/// If PermitDeref is true, then isIndexInSubscriptExpr additionally returns
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/// true on these expressions:
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/// \code
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/// (*container)[index]
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/// (*container).at(index)
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/// \endcode
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static bool isIndexInSubscriptExpr(ASTContext *Context, const Expr *IndexExpr,
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const VarDecl *IndexVar, const Expr *Obj,
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const Expr *SourceExpr, bool PermitDeref) {
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if (!SourceExpr || !Obj || !isIndexInSubscriptExpr(IndexExpr, IndexVar))
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return false;
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if (areSameExpr(Context, SourceExpr->IgnoreParenImpCasts(),
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Obj->IgnoreParenImpCasts()))
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return true;
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if (const Expr *InnerObj = getDereferenceOperand(Obj->IgnoreParenImpCasts()))
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if (PermitDeref && areSameExpr(Context, SourceExpr->IgnoreParenImpCasts(),
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InnerObj->IgnoreParenImpCasts()))
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return true;
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return false;
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}
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/// \brief Returns true when Opcall is a call a one-parameter dereference of
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/// IndexVar.
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///
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/// For example, if the index variable is `index`, returns true for
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/// *index
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/// but not
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/// index
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/// *notIndex
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static bool isDereferenceOfOpCall(const CXXOperatorCallExpr *OpCall,
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const VarDecl *IndexVar) {
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return OpCall->getOperator() == OO_Star && OpCall->getNumArgs() == 1 &&
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exprReferencesVariable(IndexVar, OpCall->getArg(0));
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}
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/// \brief Returns true when Uop is a dereference of IndexVar.
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///
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/// For example, if the index variable is `index`, returns true for
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/// *index
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/// but not
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/// index
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/// *notIndex
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static bool isDereferenceOfUop(const UnaryOperator *Uop,
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const VarDecl *IndexVar) {
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return Uop->getOpcode() == UO_Deref &&
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exprReferencesVariable(IndexVar, Uop->getSubExpr());
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}
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/// \brief Determines whether the given Decl defines a variable initialized to
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/// the loop object.
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///
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/// This is intended to find cases such as
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/// \code
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/// for (int i = 0; i < arraySize(arr); ++i) {
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/// T t = arr[i];
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/// // use t, do not use i
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/// }
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/// \endcode
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/// and
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/// \code
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/// for (iterator i = container.begin(), e = container.end(); i != e; ++i) {
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/// T t = *i;
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/// // use t, do not use i
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/// }
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/// \endcode
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static bool isAliasDecl(const Decl *TheDecl, const VarDecl *IndexVar) {
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const VarDecl *VDecl = dyn_cast<VarDecl>(TheDecl);
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if (!VDecl)
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return false;
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if (!VDecl->hasInit())
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return false;
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const Expr *Init =
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digThroughConstructors(VDecl->getInit()->IgnoreParenImpCasts());
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if (!Init)
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return false;
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switch (Init->getStmtClass()) {
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case Stmt::ArraySubscriptExprClass: {
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const ArraySubscriptExpr *E = cast<ArraySubscriptExpr>(Init);
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// We don't really care which array is used here. We check to make sure
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// it was the correct one later, since the AST will traverse it next.
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return isIndexInSubscriptExpr(E->getIdx(), IndexVar);
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}
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case Stmt::UnaryOperatorClass:
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return isDereferenceOfUop(cast<UnaryOperator>(Init), IndexVar);
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case Stmt::CXXOperatorCallExprClass: {
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const CXXOperatorCallExpr *OpCall = cast<CXXOperatorCallExpr>(Init);
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if (OpCall->getOperator() == OO_Star)
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return isDereferenceOfOpCall(OpCall, IndexVar);
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break;
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}
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default:
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break;
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}
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return false;
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}
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/// \brief Determines whether the bound of a for loop condition expression is
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/// the same as the statically computable size of ArrayType.
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///
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/// Given
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/// \code
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/// const int N = 5;
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/// int arr[N];
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/// \endcode
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/// This is intended to permit
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/// \code
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/// for (int i = 0; i < N; ++i) { /* use arr[i] */ }
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/// for (int i = 0; i < arraysize(arr); ++i) { /* use arr[i] */ }
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/// \endcode
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static bool arrayMatchesBoundExpr(ASTContext *Context,
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const QualType &ArrayType,
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const Expr *ConditionExpr) {
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if (!ConditionExpr || ConditionExpr->isValueDependent())
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return false;
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const ConstantArrayType *ConstType =
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Context->getAsConstantArrayType(ArrayType);
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if (!ConstType)
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return false;
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llvm::APSInt ConditionSize;
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if (!ConditionExpr->isIntegerConstantExpr(ConditionSize, *Context))
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return false;
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llvm::APSInt ArraySize(ConstType->getSize());
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return llvm::APSInt::isSameValue(ConditionSize, ArraySize);
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}
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/// \brief If the unary operator is a dereference of IndexVar, include it
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/// as a valid usage and prune the traversal.
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///
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/// For example, if container.begin() and container.end() both return pointers
|
|
/// to int, this makes sure that the initialization for `k` is not counted as an
|
|
/// unconvertible use of the iterator `i`.
|
|
/// \code
|
|
/// for (int *i = container.begin(), *e = container.end(); i != e; ++i) {
|
|
/// int k = *i + 2;
|
|
/// }
|
|
/// \endcode
|
|
bool ForLoopIndexUseVisitor::TraverseUnaryDeref(UnaryOperator *Uop) {
|
|
// If we dereference an iterator that's actually a pointer, count the
|
|
// occurrence.
|
|
if (isDereferenceOfUop(Uop, IndexVar)) {
|
|
Usages.push_back(Usage(Uop));
|
|
return true;
|
|
}
|
|
|
|
return VisitorBase::TraverseUnaryOperator(Uop);
|
|
}
|
|
|
|
/// \brief If the member expression is operator-> (overloaded or not) on
|
|
/// IndexVar, include it as a valid usage and prune the traversal.
|
|
///
|
|
/// For example, given
|
|
/// \code
|
|
/// struct Foo { int bar(); int x; };
|
|
/// vector<Foo> v;
|
|
/// \endcode
|
|
/// the following uses will be considered convertible:
|
|
/// \code
|
|
/// for (vector<Foo>::iterator i = v.begin(), e = v.end(); i != e; ++i) {
|
|
/// int b = i->bar();
|
|
/// int k = i->x + 1;
|
|
/// }
|
|
/// \endcode
|
|
/// though
|
|
/// \code
|
|
/// for (vector<Foo>::iterator i = v.begin(), e = v.end(); i != e; ++i) {
|
|
/// int k = i.insert(1);
|
|
/// }
|
|
/// for (vector<Foo>::iterator i = v.begin(), e = v.end(); i != e; ++i) {
|
|
/// int b = e->bar();
|
|
/// }
|
|
/// \endcode
|
|
/// will not.
|
|
bool ForLoopIndexUseVisitor::TraverseMemberExpr(MemberExpr *Member) {
|
|
const Expr *Base = Member->getBase();
|
|
const DeclRefExpr *Obj = getDeclRef(Base);
|
|
const Expr *ResultExpr = Member;
|
|
QualType ExprType;
|
|
if (const CXXOperatorCallExpr *Call =
|
|
dyn_cast<CXXOperatorCallExpr>(Base->IgnoreParenImpCasts())) {
|
|
// If operator->() is a MemberExpr containing a CXXOperatorCallExpr, then
|
|
// the MemberExpr does not have the expression we want. We therefore catch
|
|
// that instance here.
|
|
// For example, if vector<Foo>::iterator defines operator->(), then the
|
|
// example `i->bar()` at the top of this function is a CXXMemberCallExpr
|
|
// referring to `i->` as the member function called. We want just `i`, so
|
|
// we take the argument to operator->() as the base object.
|
|
if(Call->getOperator() == OO_Arrow) {
|
|
assert(Call->getNumArgs() == 1 &&
|
|
"Operator-> takes more than one argument");
|
|
Obj = getDeclRef(Call->getArg(0));
|
|
ResultExpr = Obj;
|
|
ExprType = Call->getCallReturnType();
|
|
}
|
|
}
|
|
|
|
if (Member->isArrow() && Obj && exprReferencesVariable(IndexVar, Obj)) {
|
|
if (ExprType.isNull())
|
|
ExprType = Obj->getType();
|
|
|
|
assert(ExprType->isPointerType() && "Operator-> returned non-pointer type");
|
|
// FIXME: This works around not having the location of the arrow operator.
|
|
// Consider adding OperatorLoc to MemberExpr?
|
|
SourceLocation ArrowLoc =
|
|
Lexer::getLocForEndOfToken(Base->getExprLoc(), 0,
|
|
Context->getSourceManager(),
|
|
Context->getLangOpts());
|
|
// If something complicated is happening (i.e. the next token isn't an
|
|
// arrow), give up on making this work.
|
|
if (!ArrowLoc.isInvalid()) {
|
|
Usages.push_back(Usage(ResultExpr, /*IsArrow=*/true,
|
|
SourceRange(Base->getExprLoc(), ArrowLoc)));
|
|
return true;
|
|
}
|
|
}
|
|
return TraverseStmt(Member->getBase());
|
|
}
|
|
|
|
/// \brief If a member function call is the at() accessor on the container with
|
|
/// IndexVar as the single argument, include it as a valid usage and prune
|
|
/// the traversal.
|
|
///
|
|
/// Member calls on other objects will not be permitted.
|
|
/// Calls on the iterator object are not permitted, unless done through
|
|
/// operator->(). The one exception is allowing vector::at() for pseudoarrays.
|
|
bool ForLoopIndexUseVisitor::TraverseCXXMemberCallExpr(
|
|
CXXMemberCallExpr *MemberCall) {
|
|
MemberExpr *Member =
|
|
dyn_cast<MemberExpr>(MemberCall->getCallee()->IgnoreParenImpCasts());
|
|
if (!Member)
|
|
return VisitorBase::TraverseCXXMemberCallExpr(MemberCall);
|
|
// We specifically allow an accessor named "at" to let STL in, though
|
|
// this is restricted to pseudo-arrays by requiring a single, integer
|
|
// argument.
|
|
const IdentifierInfo *Ident = Member->getMemberDecl()->getIdentifier();
|
|
if (Ident && Ident->isStr("at") && MemberCall->getNumArgs() == 1) {
|
|
if (isIndexInSubscriptExpr(Context, MemberCall->getArg(0), IndexVar,
|
|
Member->getBase(), ContainerExpr,
|
|
ContainerNeedsDereference)) {
|
|
Usages.push_back(Usage(MemberCall));
|
|
return true;
|
|
}
|
|
}
|
|
|
|
if (containsExpr(Context, &DependentExprs, Member->getBase()))
|
|
ConfidenceLevel.lowerTo(RL_Risky);
|
|
|
|
return VisitorBase::TraverseCXXMemberCallExpr(MemberCall);
|
|
}
|
|
|
|
/// \brief If an overloaded operator call is a dereference of IndexVar or
|
|
/// a subscript of a the container with IndexVar as the single argument,
|
|
/// include it as a valid usage and prune the traversal.
|
|
///
|
|
/// For example, given
|
|
/// \code
|
|
/// struct Foo { int bar(); int x; };
|
|
/// vector<Foo> v;
|
|
/// void f(Foo);
|
|
/// \endcode
|
|
/// the following uses will be considered convertible:
|
|
/// \code
|
|
/// for (vector<Foo>::iterator i = v.begin(), e = v.end(); i != e; ++i) {
|
|
/// f(*i);
|
|
/// }
|
|
/// for (int i = 0; i < v.size(); ++i) {
|
|
/// int i = v[i] + 1;
|
|
/// }
|
|
/// \endcode
|
|
bool ForLoopIndexUseVisitor::TraverseCXXOperatorCallExpr(
|
|
CXXOperatorCallExpr *OpCall) {
|
|
switch (OpCall->getOperator()) {
|
|
case OO_Star:
|
|
if (isDereferenceOfOpCall(OpCall, IndexVar)) {
|
|
Usages.push_back(Usage(OpCall));
|
|
return true;
|
|
}
|
|
break;
|
|
|
|
case OO_Subscript:
|
|
if (OpCall->getNumArgs() != 2)
|
|
break;
|
|
if (isIndexInSubscriptExpr(Context, OpCall->getArg(1), IndexVar,
|
|
OpCall->getArg(0), ContainerExpr,
|
|
ContainerNeedsDereference)) {
|
|
Usages.push_back(Usage(OpCall));
|
|
return true;
|
|
}
|
|
break;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
return VisitorBase::TraverseCXXOperatorCallExpr(OpCall);
|
|
}
|
|
|
|
/// \brief If we encounter an array with IndexVar as the index of an
|
|
/// ArraySubsriptExpression, note it as a consistent usage and prune the
|
|
/// AST traversal.
|
|
///
|
|
/// For example, given
|
|
/// \code
|
|
/// const int N = 5;
|
|
/// int arr[N];
|
|
/// \endcode
|
|
/// This is intended to permit
|
|
/// \code
|
|
/// for (int i = 0; i < N; ++i) { /* use arr[i] */ }
|
|
/// \endcode
|
|
/// but not
|
|
/// \code
|
|
/// for (int i = 0; i < N; ++i) { /* use notArr[i] */ }
|
|
/// \endcode
|
|
/// and further checking needs to be done later to ensure that exactly one array
|
|
/// is referenced.
|
|
bool ForLoopIndexUseVisitor::TraverseArraySubscriptExpr(
|
|
ArraySubscriptExpr *E) {
|
|
Expr *Arr = E->getBase();
|
|
if (!isIndexInSubscriptExpr(E->getIdx(), IndexVar))
|
|
return VisitorBase::TraverseArraySubscriptExpr(E);
|
|
|
|
if ((ContainerExpr && !areSameExpr(Context, Arr->IgnoreParenImpCasts(),
|
|
ContainerExpr->IgnoreParenImpCasts()))
|
|
|| !arrayMatchesBoundExpr(Context, Arr->IgnoreImpCasts()->getType(),
|
|
ArrayBoundExpr)) {
|
|
// If we have already discovered the array being indexed and this isn't it
|
|
// or this array doesn't match, mark this loop as unconvertible.
|
|
OnlyUsedAsIndex = false;
|
|
return VisitorBase::TraverseArraySubscriptExpr(E);
|
|
}
|
|
|
|
if (!ContainerExpr)
|
|
ContainerExpr = Arr;
|
|
|
|
Usages.push_back(Usage(E));
|
|
return true;
|
|
}
|
|
|
|
/// \brief If we encounter a reference to IndexVar in an unpruned branch of the
|
|
/// traversal, mark this loop as unconvertible.
|
|
///
|
|
/// This implements the whitelist for convertible loops: any usages of IndexVar
|
|
/// not explicitly considered convertible by this traversal will be caught by
|
|
/// this function.
|
|
///
|
|
/// Additionally, if the container expression is more complex than just a
|
|
/// DeclRefExpr, and some part of it is appears elsewhere in the loop, lower
|
|
/// our confidence in the transformation.
|
|
///
|
|
/// For example, these are not permitted:
|
|
/// \code
|
|
/// for (int i = 0; i < N; ++i) { printf("arr[%d] = %d", i, arr[i]); }
|
|
/// for (vector<int>::iterator i = container.begin(), e = container.end();
|
|
/// i != e; ++i)
|
|
/// i.insert(0);
|
|
/// for (vector<int>::iterator i = container.begin(), e = container.end();
|
|
/// i != e; ++i)
|
|
/// i.insert(0);
|
|
/// for (vector<int>::iterator i = container.begin(), e = container.end();
|
|
/// i != e; ++i)
|
|
/// if (i + 1 != e)
|
|
/// printf("%d", *i);
|
|
/// \endcode
|
|
///
|
|
/// And these will raise the risk level:
|
|
/// \code
|
|
/// int arr[10][20];
|
|
/// int l = 5;
|
|
/// for (int j = 0; j < 20; ++j)
|
|
/// int k = arr[l][j] + l; // using l outside arr[l] is considered risky
|
|
/// for (int i = 0; i < obj.getVector().size(); ++i)
|
|
/// obj.foo(10); // using `obj` is considered risky
|
|
/// \endcode
|
|
bool ForLoopIndexUseVisitor::VisitDeclRefExpr(DeclRefExpr *E) {
|
|
const ValueDecl *TheDecl = E->getDecl();
|
|
if (areSameVariable(IndexVar, TheDecl) || areSameVariable(EndVar, TheDecl))
|
|
OnlyUsedAsIndex = false;
|
|
if (containsExpr(Context, &DependentExprs, E))
|
|
ConfidenceLevel.lowerTo(RL_Risky);
|
|
return true;
|
|
}
|
|
|
|
/// \brief If we find that another variable is created just to refer to the loop
|
|
/// element, note it for reuse as the loop variable.
|
|
///
|
|
/// See the comments for isAliasDecl.
|
|
bool ForLoopIndexUseVisitor::VisitDeclStmt(DeclStmt *S) {
|
|
if (!AliasDecl && S->isSingleDecl() &&
|
|
isAliasDecl(S->getSingleDecl(), IndexVar)) {
|
|
AliasDecl = S;
|
|
if (CurrStmtParent) {
|
|
if (isa<IfStmt>(CurrStmtParent) ||
|
|
isa<WhileStmt>(CurrStmtParent) ||
|
|
isa<SwitchStmt>(CurrStmtParent))
|
|
ReplaceWithAliasUse = true;
|
|
else if (isa<ForStmt>(CurrStmtParent)) {
|
|
if (cast<ForStmt>(CurrStmtParent)->getConditionVariableDeclStmt() == S)
|
|
ReplaceWithAliasUse = true;
|
|
else
|
|
// It's assumed S came the for loop's init clause.
|
|
AliasFromForInit = true;
|
|
}
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool ForLoopIndexUseVisitor::TraverseStmt(Stmt *S) {
|
|
// All this pointer swapping is a mechanism for tracking immediate parentage
|
|
// of Stmts.
|
|
const Stmt *OldNextParent = NextStmtParent;
|
|
CurrStmtParent = NextStmtParent;
|
|
NextStmtParent = S;
|
|
bool Result = VisitorBase::TraverseStmt(S);
|
|
NextStmtParent = OldNextParent;
|
|
return Result;
|
|
}
|
|
|
|
//// \brief Apply the source transformations necessary to migrate the loop!
|
|
void LoopFixer::doConversion(ASTContext *Context,
|
|
const VarDecl *IndexVar,
|
|
const VarDecl *MaybeContainer,
|
|
StringRef ContainerString,
|
|
const UsageResult &Usages,
|
|
const DeclStmt *AliasDecl,
|
|
bool AliasUseRequired,
|
|
bool AliasFromForInit,
|
|
const ForStmt *TheLoop,
|
|
bool ContainerNeedsDereference,
|
|
bool DerefByValue,
|
|
bool DerefByConstRef) {
|
|
std::string VarName;
|
|
bool VarNameFromAlias = Usages.size() == 1 && AliasDecl;
|
|
bool AliasVarIsRef = false;
|
|
|
|
if (VarNameFromAlias) {
|
|
const VarDecl *AliasVar = cast<VarDecl>(AliasDecl->getSingleDecl());
|
|
VarName = AliasVar->getName().str();
|
|
AliasVarIsRef = AliasVar->getType()->isReferenceType();
|
|
|
|
// We keep along the entire DeclStmt to keep the correct range here.
|
|
const SourceRange &ReplaceRange = AliasDecl->getSourceRange();
|
|
|
|
std::string ReplacementText;
|
|
if (AliasUseRequired)
|
|
ReplacementText = VarName;
|
|
else if (AliasFromForInit)
|
|
// FIXME: Clang includes the location of the ';' but only for DeclStmt's
|
|
// in a for loop's init clause. Need to put this ';' back while removing
|
|
// the declaration of the alias variable. This is probably a bug.
|
|
ReplacementText = ";";
|
|
|
|
Owner.addReplacementForCurrentTU(Replacement(
|
|
Context->getSourceManager(),
|
|
CharSourceRange::getTokenRange(ReplaceRange), ReplacementText));
|
|
// No further replacements are made to the loop, since the iterator or index
|
|
// was used exactly once - in the initialization of AliasVar.
|
|
} else {
|
|
VariableNamer Namer(&TUInfo.getGeneratedDecls(),
|
|
&TUInfo.getParentFinder().getStmtToParentStmtMap(),
|
|
TheLoop, IndexVar, MaybeContainer, Context);
|
|
VarName = Namer.createIndexName();
|
|
// First, replace all usages of the array subscript expression with our new
|
|
// variable.
|
|
for (UsageResult::const_iterator I = Usages.begin(), E = Usages.end();
|
|
I != E; ++I) {
|
|
std::string ReplaceText = I->IsArrow ? VarName + "." : VarName;
|
|
TUInfo.getReplacedVars().insert(std::make_pair(TheLoop, IndexVar));
|
|
Owner.addReplacementForCurrentTU(
|
|
Replacement(Context->getSourceManager(),
|
|
CharSourceRange::getTokenRange(I->Range), ReplaceText));
|
|
}
|
|
}
|
|
|
|
// Now, we need to construct the new range expresion.
|
|
SourceRange ParenRange(TheLoop->getLParenLoc(), TheLoop->getRParenLoc());
|
|
|
|
QualType AutoRefType = Context->getAutoDeductType();
|
|
|
|
// If the new variable name is from the aliased variable, then the reference
|
|
// type for the new variable should only be used if the aliased variable was
|
|
// declared as a reference.
|
|
if (!VarNameFromAlias || AliasVarIsRef) {
|
|
// If an iterator's operator*() returns a 'T&' we can bind that to 'auto&'.
|
|
// If operator*() returns 'T' we can bind that to 'auto&&' which will deduce
|
|
// to 'T&&'.
|
|
if (DerefByValue)
|
|
AutoRefType = Context->getRValueReferenceType(AutoRefType);
|
|
else {
|
|
if (DerefByConstRef)
|
|
AutoRefType = Context->getConstType(AutoRefType);
|
|
AutoRefType = Context->getLValueReferenceType(AutoRefType);
|
|
}
|
|
}
|
|
|
|
std::string MaybeDereference = ContainerNeedsDereference ? "*" : "";
|
|
std::string TypeString = AutoRefType.getAsString();
|
|
std::string Range = ("(" + TypeString + " " + VarName + " : "
|
|
+ MaybeDereference + ContainerString + ")").str();
|
|
Owner.addReplacementForCurrentTU(
|
|
Replacement(Context->getSourceManager(),
|
|
CharSourceRange::getTokenRange(ParenRange), Range));
|
|
TUInfo.getGeneratedDecls().insert(make_pair(TheLoop, VarName));
|
|
}
|
|
|
|
/// \brief Determine whether Init appears to be an initializing an iterator.
|
|
///
|
|
/// If it is, returns the object whose begin() or end() method is called, and
|
|
/// the output parameter isArrow is set to indicate whether the initialization
|
|
/// is called via . or ->.
|
|
static const Expr *getContainerFromBeginEndCall(const Expr *Init, bool IsBegin,
|
|
bool *IsArrow) {
|
|
// FIXME: Maybe allow declaration/initialization outside of the for loop?
|
|
const CXXMemberCallExpr *TheCall =
|
|
dyn_cast_or_null<CXXMemberCallExpr>(digThroughConstructors(Init));
|
|
if (!TheCall || TheCall->getNumArgs() != 0)
|
|
return NULL;
|
|
|
|
const MemberExpr *Member = dyn_cast<MemberExpr>(TheCall->getCallee());
|
|
if (!Member)
|
|
return NULL;
|
|
const std::string Name = Member->getMemberDecl()->getName();
|
|
const std::string TargetName = IsBegin ? "begin" : "end";
|
|
if (Name != TargetName)
|
|
return NULL;
|
|
|
|
const Expr *SourceExpr = Member->getBase();
|
|
if (!SourceExpr)
|
|
return NULL;
|
|
|
|
*IsArrow = Member->isArrow();
|
|
return SourceExpr;
|
|
}
|
|
|
|
/// \brief Determines the container whose begin() and end() functions are called
|
|
/// for an iterator-based loop.
|
|
///
|
|
/// BeginExpr must be a member call to a function named "begin()", and EndExpr
|
|
/// must be a member .
|
|
static const Expr *findContainer(ASTContext *Context, const Expr *BeginExpr,
|
|
const Expr *EndExpr,
|
|
bool *ContainerNeedsDereference) {
|
|
// Now that we know the loop variable and test expression, make sure they are
|
|
// valid.
|
|
bool BeginIsArrow = false;
|
|
bool EndIsArrow = false;
|
|
const Expr *BeginContainerExpr =
|
|
getContainerFromBeginEndCall(BeginExpr, /*IsBegin=*/true, &BeginIsArrow);
|
|
if (!BeginContainerExpr)
|
|
return NULL;
|
|
|
|
const Expr *EndContainerExpr =
|
|
getContainerFromBeginEndCall(EndExpr, /*IsBegin=*/false, &EndIsArrow);
|
|
// Disallow loops that try evil things like this (note the dot and arrow):
|
|
// for (IteratorType It = Obj.begin(), E = Obj->end(); It != E; ++It) { }
|
|
if (!EndContainerExpr || BeginIsArrow != EndIsArrow ||
|
|
!areSameExpr(Context, EndContainerExpr, BeginContainerExpr))
|
|
return NULL;
|
|
|
|
*ContainerNeedsDereference = BeginIsArrow;
|
|
return BeginContainerExpr;
|
|
}
|
|
|
|
StringRef LoopFixer::checkDeferralsAndRejections(ASTContext *Context,
|
|
const Expr *ContainerExpr,
|
|
Confidence ConfidenceLevel,
|
|
const ForStmt *TheLoop) {
|
|
// If we already modified the range of this for loop, don't do any further
|
|
// updates on this iteration.
|
|
// FIXME: Once Replacements can detect conflicting edits, replace this
|
|
// implementation and rely on conflicting edit detection instead.
|
|
if (TUInfo.getReplacedVars().count(TheLoop)) {
|
|
++*DeferredChanges;
|
|
return "";
|
|
}
|
|
|
|
TUInfo.getParentFinder().gatherAncestors(Context->getTranslationUnitDecl());
|
|
// Ensure that we do not try to move an expression dependent on a local
|
|
// variable declared inside the loop outside of it!
|
|
DependencyFinderASTVisitor DependencyFinder(
|
|
&TUInfo.getParentFinder().getStmtToParentStmtMap(),
|
|
&TUInfo.getParentFinder().getDeclToParentStmtMap(),
|
|
&TUInfo.getReplacedVars(), TheLoop);
|
|
|
|
// Not all of these are actually deferred changes.
|
|
// FIXME: Determine when the external dependency isn't an expression converted
|
|
// by another loop.
|
|
if (DependencyFinder.dependsOnInsideVariable(ContainerExpr)) {
|
|
++*DeferredChanges;
|
|
return "";
|
|
}
|
|
if (ConfidenceLevel.getRiskLevel() > MaxRisk) {
|
|
++*RejectedChanges;
|
|
return "";
|
|
}
|
|
|
|
StringRef ContainerString;
|
|
if (isa<CXXThisExpr>(ContainerExpr->IgnoreParenImpCasts())) {
|
|
ContainerString = "this";
|
|
} else {
|
|
ContainerString = getStringFromRange(Context->getSourceManager(),
|
|
Context->getLangOpts(),
|
|
ContainerExpr->getSourceRange());
|
|
}
|
|
|
|
// In case someone is using an evil macro, reject this change.
|
|
if (ContainerString.empty())
|
|
++*RejectedChanges;
|
|
return ContainerString;
|
|
}
|
|
|
|
/// \brief Given that we have verified that the loop's header appears to be
|
|
/// convertible, run the complete analysis on the loop to determine if the
|
|
/// loop's body is convertible.
|
|
void LoopFixer::findAndVerifyUsages(ASTContext *Context,
|
|
const VarDecl *LoopVar,
|
|
const VarDecl *EndVar,
|
|
const Expr *ContainerExpr,
|
|
const Expr *BoundExpr,
|
|
bool ContainerNeedsDereference,
|
|
bool DerefByValue,
|
|
bool DerefByConstRef,
|
|
const ForStmt *TheLoop,
|
|
Confidence ConfidenceLevel) {
|
|
ForLoopIndexUseVisitor Finder(Context, LoopVar, EndVar, ContainerExpr,
|
|
BoundExpr, ContainerNeedsDereference);
|
|
if (ContainerExpr) {
|
|
ComponentFinderASTVisitor ComponentFinder;
|
|
ComponentFinder.findExprComponents(ContainerExpr->IgnoreParenImpCasts());
|
|
Finder.addComponents(ComponentFinder.getComponents());
|
|
}
|
|
|
|
if (!Finder.findAndVerifyUsages(TheLoop->getBody()))
|
|
return;
|
|
|
|
ConfidenceLevel.lowerTo(Finder.getRiskLevel());
|
|
if (FixerKind == LFK_Array) {
|
|
// The array being indexed by IndexVar was discovered during traversal.
|
|
ContainerExpr = Finder.getContainerIndexed()->IgnoreParenImpCasts();
|
|
// Very few loops are over expressions that generate arrays rather than
|
|
// array variables. Consider loops over arrays that aren't just represented
|
|
// by a variable to be risky conversions.
|
|
if (!getReferencedVariable(ContainerExpr) &&
|
|
!isDirectMemberExpr(ContainerExpr))
|
|
ConfidenceLevel.lowerTo(RL_Risky);
|
|
}
|
|
|
|
std::string ContainerString =
|
|
checkDeferralsAndRejections(Context, ContainerExpr,
|
|
ConfidenceLevel, TheLoop);
|
|
if (ContainerString.empty())
|
|
return;
|
|
|
|
doConversion(Context, LoopVar, getReferencedVariable(ContainerExpr),
|
|
ContainerString, Finder.getUsages(), Finder.getAliasDecl(),
|
|
Finder.aliasUseRequired(), Finder.aliasFromForInit(), TheLoop,
|
|
ContainerNeedsDereference, DerefByValue, DerefByConstRef);
|
|
++*AcceptedChanges;
|
|
}
|
|
|
|
/// \brief The LoopFixer callback, which determines if loops discovered by the
|
|
/// matchers are convertible, printing information about the loops if so.
|
|
void LoopFixer::run(const MatchFinder::MatchResult &Result) {
|
|
const BoundNodes &Nodes = Result.Nodes;
|
|
Confidence ConfidenceLevel(RL_Safe);
|
|
ASTContext *Context = Result.Context;
|
|
const ForStmt *TheLoop = Nodes.getStmtAs<ForStmt>(LoopName);
|
|
|
|
if (!Owner.isFileModifiable(Context->getSourceManager(),TheLoop->getForLoc()))
|
|
return;
|
|
|
|
// Check that we have exactly one index variable and at most one end variable.
|
|
const VarDecl *LoopVar = Nodes.getDeclAs<VarDecl>(IncrementVarName);
|
|
const VarDecl *CondVar = Nodes.getDeclAs<VarDecl>(ConditionVarName);
|
|
const VarDecl *InitVar = Nodes.getDeclAs<VarDecl>(InitVarName);
|
|
if (!areSameVariable(LoopVar, CondVar) || !areSameVariable(LoopVar, InitVar))
|
|
return;
|
|
const VarDecl *EndVar = Nodes.getDeclAs<VarDecl>(EndVarName);
|
|
const VarDecl *ConditionEndVar =
|
|
Nodes.getDeclAs<VarDecl>(ConditionEndVarName);
|
|
if (EndVar && !areSameVariable(EndVar, ConditionEndVar))
|
|
return;
|
|
|
|
// If the end comparison isn't a variable, we can try to work with the
|
|
// expression the loop variable is being tested against instead.
|
|
const CXXMemberCallExpr *EndCall =
|
|
Nodes.getStmtAs<CXXMemberCallExpr>(EndCallName);
|
|
const Expr *BoundExpr = Nodes.getStmtAs<Expr>(ConditionBoundName);
|
|
// If the loop calls end()/size() after each iteration, lower our confidence
|
|
// level.
|
|
if (FixerKind != LFK_Array && !EndVar)
|
|
ConfidenceLevel.lowerTo(RL_Reasonable);
|
|
|
|
const Expr *ContainerExpr = NULL;
|
|
bool DerefByValue = false;
|
|
bool DerefByConstRef = false;
|
|
bool ContainerNeedsDereference = false;
|
|
// FIXME: Try to put most of this logic inside a matcher. Currently, matchers
|
|
// don't allow the right-recursive checks in digThroughConstructors.
|
|
if (FixerKind == LFK_Iterator) {
|
|
ContainerExpr = findContainer(Context, LoopVar->getInit(),
|
|
EndVar ? EndVar->getInit() : EndCall,
|
|
&ContainerNeedsDereference);
|
|
|
|
QualType InitVarType = InitVar->getType();
|
|
QualType CanonicalInitVarType = InitVarType.getCanonicalType();
|
|
|
|
const CXXMemberCallExpr *BeginCall =
|
|
Nodes.getNodeAs<CXXMemberCallExpr>(BeginCallName);
|
|
assert(BeginCall != 0 && "Bad Callback. No begin call expression.");
|
|
QualType CanonicalBeginType =
|
|
BeginCall->getMethodDecl()->getResultType().getCanonicalType();
|
|
|
|
if (CanonicalBeginType->isPointerType() &&
|
|
CanonicalInitVarType->isPointerType()) {
|
|
QualType BeginPointeeType = CanonicalBeginType->getPointeeType();
|
|
QualType InitPointeeType = CanonicalInitVarType->getPointeeType();
|
|
// If the initializer and the variable are both pointers check if the
|
|
// un-qualified pointee types match otherwise we don't use auto.
|
|
if (!Context->hasSameUnqualifiedType(InitPointeeType, BeginPointeeType))
|
|
return;
|
|
} else {
|
|
// Check for qualified types to avoid conversions from non-const to const
|
|
// iterator types.
|
|
if (!Context->hasSameType(CanonicalInitVarType, CanonicalBeginType))
|
|
return;
|
|
}
|
|
|
|
DerefByValue = Nodes.getNodeAs<QualType>(DerefByValueResultName) != 0;
|
|
if (!DerefByValue) {
|
|
if (const QualType *DerefType =
|
|
Nodes.getNodeAs<QualType>(DerefByRefResultName)) {
|
|
// A node will only be bound with DerefByRefResultName if we're dealing
|
|
// with a user-defined iterator type. Test the const qualification of
|
|
// the reference type.
|
|
DerefByConstRef = (*DerefType)->getAs<ReferenceType>()->getPointeeType()
|
|
.isConstQualified();
|
|
} else {
|
|
// By nature of the matcher this case is triggered only for built-in
|
|
// iterator types (i.e. pointers).
|
|
assert(isa<PointerType>(CanonicalInitVarType) &&
|
|
"Non-class iterator type is not a pointer type");
|
|
QualType InitPointeeType = CanonicalInitVarType->getPointeeType();
|
|
QualType BeginPointeeType = CanonicalBeginType->getPointeeType();
|
|
// If the initializer and variable have both the same type just use auto
|
|
// otherwise we test for const qualification of the pointed-at type.
|
|
if (!Context->hasSameType(InitPointeeType, BeginPointeeType))
|
|
DerefByConstRef = InitPointeeType.isConstQualified();
|
|
}
|
|
} else {
|
|
// If the dereference operator returns by value then test for the
|
|
// canonical const qualification of the init variable type.
|
|
DerefByConstRef = CanonicalInitVarType.isConstQualified();
|
|
}
|
|
} else if (FixerKind == LFK_PseudoArray) {
|
|
if (!EndCall)
|
|
return;
|
|
ContainerExpr = EndCall->getImplicitObjectArgument();
|
|
const MemberExpr *Member = dyn_cast<MemberExpr>(EndCall->getCallee());
|
|
if (!Member)
|
|
return;
|
|
ContainerNeedsDereference = Member->isArrow();
|
|
}
|
|
// We must know the container or an array length bound.
|
|
if (!ContainerExpr && !BoundExpr)
|
|
return;
|
|
|
|
findAndVerifyUsages(Context, LoopVar, EndVar, ContainerExpr, BoundExpr,
|
|
ContainerNeedsDereference, DerefByValue, DerefByConstRef,
|
|
TheLoop, ConfidenceLevel);
|
|
}
|