forked from OSchip/llvm-project
125 lines
5.1 KiB
C++
125 lines
5.1 KiB
C++
//===------------- ExprSequence.h - clang-tidy ----------------------------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_EXPRSEQUENCE_H
|
|
#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_EXPRSEQUENCE_H
|
|
|
|
#include "clang/Analysis/CFG.h"
|
|
#include "clang/Lex/Lexer.h"
|
|
#include "llvm/ADT/DenseMap.h"
|
|
#include "llvm/ADT/SmallPtrSet.h"
|
|
#include "llvm/ADT/SmallVector.h"
|
|
|
|
#include "../ClangTidy.h"
|
|
|
|
namespace clang {
|
|
namespace tidy {
|
|
namespace utils {
|
|
|
|
/// Provides information about the evaluation order of (sub-)expressions within
|
|
/// a `CFGBlock`.
|
|
///
|
|
/// While a `CFGBlock` does contain individual `CFGElement`s for some
|
|
/// sub-expressions, the order in which those `CFGElement`s appear reflects
|
|
/// only one possible order in which the sub-expressions may be evaluated.
|
|
/// However, we want to warn if any of the potential evaluation orders can lead
|
|
/// to a use-after-move, not just the one contained in the `CFGBlock`.
|
|
///
|
|
/// This class implements only a simplified version of the C++ sequencing
|
|
/// rules. The main limitation is that we do not distinguish between value
|
|
/// computation and side effect -- see the "Implementation" section for more
|
|
/// details.
|
|
///
|
|
/// Note: `SequenceChecker` from SemaChecking.cpp does a similar job (and much
|
|
/// more thoroughly), but using it would require
|
|
/// - Pulling `SequenceChecker` out into a header file (i.e. making it part of
|
|
/// the API),
|
|
/// - Removing the dependency of `SequenceChecker` on `Sema`, and
|
|
/// - (Probably) modifying `SequenceChecker` to make it suitable to be used in
|
|
/// this context.
|
|
/// For the moment, it seems preferable to re-implement our own version of
|
|
/// sequence checking that is special-cased to what we need here.
|
|
///
|
|
/// Implementation
|
|
/// --------------
|
|
///
|
|
/// `ExprSequence` uses two types of sequencing edges between nodes in the AST:
|
|
///
|
|
/// - Every `Stmt` is assumed to be sequenced after its children. This is
|
|
/// overly optimistic because the standard only states that value computations
|
|
/// of operands are sequenced before the value computation of the operator,
|
|
/// making no guarantees about side effects (in general).
|
|
///
|
|
/// For our purposes, this rule is sufficient, however, because this check is
|
|
/// interested in operations on objects, which are generally performed through
|
|
/// function calls (whether explicit and implicit). Function calls guarantee
|
|
/// that the value computations and side effects for all function arguments
|
|
/// are sequenced before the execution of the function.
|
|
///
|
|
/// - In addition, some `Stmt`s are known to be sequenced before or after
|
|
/// their siblings. For example, the `Stmt`s that make up a `CompoundStmt`are
|
|
/// all sequenced relative to each other. The function
|
|
/// `getSequenceSuccessor()` implements these sequencing rules.
|
|
class ExprSequence {
|
|
public:
|
|
/// Initializes this `ExprSequence` with sequence information for the given
|
|
/// `CFG`.
|
|
ExprSequence(const CFG *TheCFG, ASTContext *TheContext);
|
|
|
|
/// Returns whether \p Before is sequenced before \p After.
|
|
bool inSequence(const Stmt *Before, const Stmt *After) const;
|
|
|
|
/// Returns whether \p After can potentially be evaluated after \p Before.
|
|
/// This is exactly equivalent to `!inSequence(After, Before)` but makes some
|
|
/// conditions read more naturally.
|
|
bool potentiallyAfter(const Stmt *After, const Stmt *Before) const;
|
|
|
|
private:
|
|
// Returns the sibling of \p S (if any) that is directly sequenced after \p S,
|
|
// or nullptr if no such sibling exists. For example, if \p S is the child of
|
|
// a `CompoundStmt`, this would return the Stmt that directly follows \p S in
|
|
// the `CompoundStmt`.
|
|
//
|
|
// As the sequencing of many constructs that change control flow is already
|
|
// encoded in the `CFG`, this function only implements the sequencing rules
|
|
// for those constructs where sequencing cannot be inferred from the `CFG`.
|
|
const Stmt *getSequenceSuccessor(const Stmt *S) const;
|
|
|
|
const Stmt *resolveSyntheticStmt(const Stmt *S) const;
|
|
|
|
ASTContext *Context;
|
|
|
|
llvm::DenseMap<const Stmt *, const Stmt *> SyntheticStmtSourceMap;
|
|
};
|
|
|
|
/// Maps `Stmt`s to the `CFGBlock` that contains them. Some `Stmt`s may be
|
|
/// contained in more than one `CFGBlock`; in this case, they are mapped to the
|
|
/// innermost block (i.e. the one that is furthest from the root of the tree).
|
|
class StmtToBlockMap {
|
|
public:
|
|
/// Initializes the map for the given `CFG`.
|
|
StmtToBlockMap(const CFG *TheCFG, ASTContext *TheContext);
|
|
|
|
/// Returns the block that \p S is contained in. Some `Stmt`s may be contained
|
|
/// in more than one `CFGBlock`; in this case, this function returns the
|
|
/// innermost block (i.e. the one that is furthest from the root of the tree).
|
|
const CFGBlock *blockContainingStmt(const Stmt *S) const;
|
|
|
|
private:
|
|
ASTContext *Context;
|
|
|
|
llvm::DenseMap<const Stmt *, const CFGBlock *> Map;
|
|
};
|
|
|
|
} // namespace utils
|
|
} // namespace tidy
|
|
} // namespace clang
|
|
|
|
#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_EXPRSEQUENCE_H
|