include/llvm/Analysis/ValueNumbering.h

//===- llvm/Analysis/ValueNumbering.h - Value #'ing Interface ---*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the abstract ValueNumbering interface, which is used as the
// common interface used by all clients of value numbering information, and
// implemented by all value numbering implementations.
//
// Implementations of this interface must implement the various virtual methods,
// which automatically provides functionality for the entire suite of client
// APIs.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ANALYSIS_VALUE_NUMBERING_H
#define LLVM_ANALYSIS_VALUE_NUMBERING_H

#include <vector>
#include "llvm/Pass.h"

namespace llvm {

class Value;
class Instruction;

struct ValueNumbering {
  static char ID; // Class identification, replacement for typeinfo
  virtual ~ValueNumbering();    // We want to be subclassed

  /// getEqualNumberNodes - Return nodes with the same value number as the
  /// specified Value.  This fills in the argument vector with any equal values.
  ///
  virtual void getEqualNumberNodes(Value *V1,
                                   std::vector<Value*> &RetVals) const = 0;

  ///===-------------------------------------------------------------------===//
  /// Interfaces to update value numbering analysis information as the client
  /// changes the program.
  ///

  /// deleteValue - This method should be called whenever an LLVM Value is
  /// deleted from the program, for example when an instruction is found to be
  /// redundant and is eliminated.
  ///
  virtual void deleteValue(Value *V) {}

  /// copyValue - This method should be used whenever a preexisting value in the
  /// program is copied or cloned, introducing a new value.  Note that analysis
  /// implementations should tolerate clients that use this method to introduce
  /// the same value multiple times: if the analysis already knows about a
  /// value, it should ignore the request.
  ///
  virtual void copyValue(Value *From, Value *To) {}

  /// replaceWithNewValue - This method is the obvious combination of the two
  /// above, and it provided as a helper to simplify client code.
  ///
  void replaceWithNewValue(Value *Old, Value *New) {
    copyValue(Old, New);
    deleteValue(Old);
  }
};

} // End llvm namespace

// Force any file including this header to get the implementation as well
FORCE_DEFINING_FILE_TO_BE_LINKED(BasicValueNumbering)

#endif