Subversion Repositories QNX 8.QNX8 LLVM/Clang compiler suite

//===- CodeGen/MachineConstantPool.h - Abstract Constant Pool ---*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

/// @file

/// This file declares the MachineConstantPool class which is an abstract

/// constant pool to keep track of constants referenced by a function.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CODEGEN_MACHINECONSTANTPOOL_H

#define LLVM_CODEGEN_MACHINECONSTANTPOOL_H

#include "llvm/ADT/DenseSet.h"

#include "llvm/MC/SectionKind.h"

#include "llvm/Support/Alignment.h"

#include <climits>

#include <vector>

namespace llvm {

class Constant;

class DataLayout;

class FoldingSetNodeID;

class MachineConstantPool;

class raw_ostream;

class Type;

/// Abstract base class for all machine specific constantpool value subclasses.

///

class MachineConstantPoolValue {

  virtual void anchor();

  Type *Ty;

public:

  explicit MachineConstantPoolValue(Type *ty) : Ty(ty) {}

  virtual ~MachineConstantPoolValue() = default;

  Type *getType() const { return Ty; }

  virtual unsigned getSizeInBytes(const DataLayout &DL) const;

  virtual int getExistingMachineCPValue(MachineConstantPool *CP,

                                        Align Alignment) = 0;

  virtual void addSelectionDAGCSEId(FoldingSetNodeID &ID) = 0;

  /// print - Implement operator<<

  virtual void print(raw_ostream &O) const = 0;

};

inline raw_ostream &operator<<(raw_ostream &OS,

                               const MachineConstantPoolValue &V) {

  V.print(OS);

  return OS;

}

/// This class is a data container for one entry in a MachineConstantPool.

/// It contains a pointer to the value and an offset from the start of

/// the constant pool.

/// An entry in a MachineConstantPool

class MachineConstantPoolEntry {

public:

  /// The constant itself.

  union {

    const Constant *ConstVal;

    MachineConstantPoolValue *MachineCPVal;

  } Val;

  /// The required alignment for this entry.

  Align Alignment;

  bool IsMachineConstantPoolEntry;

  MachineConstantPoolEntry(const Constant *V, Align A)

      : Alignment(A), IsMachineConstantPoolEntry(false) {

    Val.ConstVal = V;

  }

  MachineConstantPoolEntry(MachineConstantPoolValue *V, Align A)

      : Alignment(A), IsMachineConstantPoolEntry(true) {

    Val.MachineCPVal = V;

  }

  /// isMachineConstantPoolEntry - Return true if the MachineConstantPoolEntry

  /// is indeed a target specific constantpool entry, not a wrapper over a

  /// Constant.

  bool isMachineConstantPoolEntry() const { return IsMachineConstantPoolEntry; }

  Align getAlign() const { return Alignment; }

  unsigned getSizeInBytes(const DataLayout &DL) const;

  /// This method classifies the entry according to whether or not it may

  /// generate a relocation entry.  This must be conservative, so if it might

  /// codegen to a relocatable entry, it should say so.

  bool needsRelocation() const;

  SectionKind getSectionKind(const DataLayout *DL) const;

};

/// The MachineConstantPool class keeps track of constants referenced by a

/// function which must be spilled to memory.  This is used for constants which

/// are unable to be used directly as operands to instructions, which typically

/// include floating point and large integer constants.

///

/// Instructions reference the address of these constant pool constants through

/// the use of MO_ConstantPoolIndex values.  When emitting assembly or machine

/// code, these virtual address references are converted to refer to the

/// address of the function constant pool values.

/// The machine constant pool.

class MachineConstantPool {

  Align PoolAlignment; ///< The alignment for the pool.

  std::vector<MachineConstantPoolEntry> Constants; ///< The pool of constants.

  /// MachineConstantPoolValues that use an existing MachineConstantPoolEntry.

  DenseSet<MachineConstantPoolValue*> MachineCPVsSharingEntries;

  const DataLayout &DL;

  const DataLayout &getDataLayout() const { return DL; }

public:

  /// The only constructor.

  explicit MachineConstantPool(const DataLayout &DL)

      : PoolAlignment(1), DL(DL) {}

  ~MachineConstantPool();

  /// Return the alignment required by the whole constant pool, of which the

  /// first element must be aligned.

  Align getConstantPoolAlign() const { return PoolAlignment; }

  /// getConstantPoolIndex - Create a new entry in the constant pool or return

  /// an existing one.  User must specify the minimum required alignment for

  /// the object.

  unsigned getConstantPoolIndex(const Constant *C, Align Alignment);

  unsigned getConstantPoolIndex(MachineConstantPoolValue *V, Align Alignment);

  /// isEmpty - Return true if this constant pool contains no constants.

  bool isEmpty() const { return Constants.empty(); }

  const std::vector<MachineConstantPoolEntry> &getConstants() const {

    return Constants;

  }

  /// print - Used by the MachineFunction printer to print information about

  /// constant pool objects.  Implemented in MachineFunction.cpp

  void print(raw_ostream &OS) const;

  /// dump - Call print(cerr) to be called from the debugger.

  void dump() const;

};

} // end namespace llvm

#endif // LLVM_CODEGEN_MACHINECONSTANTPOOL_H