llvm-mirror/include/llvm/Target/TargetSelectionDAGInfo.h

//==-- llvm/Target/TargetSelectionDAGInfo.h - SelectionDAG Info --*- C++ -*-==//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the TargetSelectionDAGInfo class, which targets can
// subclass to parameterize the SelectionDAG lowering and instruction
// selection process.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_TARGET_TARGETSELECTIONDAGINFO_H
#define LLVM_TARGET_TARGETSELECTIONDAGINFO_H

#include "llvm/CodeGen/SelectionDAGNodes.h"

namespace llvm {

class TargetData;
class TargetMachine;

//===----------------------------------------------------------------------===//
/// TargetSelectionDAGInfo - Targets can subclass this to parameterize the
/// SelectionDAG lowering and instruction selection process.
///
class TargetSelectionDAGInfo {
  TargetSelectionDAGInfo(const TargetSelectionDAGInfo &); // DO NOT IMPLEMENT
  void operator=(const TargetSelectionDAGInfo &);         // DO NOT IMPLEMENT

  const TargetData *TD;

protected:
  const TargetData *getTargetData() const { return TD; }

public:
  explicit TargetSelectionDAGInfo(const TargetMachine &TM);
  virtual ~TargetSelectionDAGInfo();

  /// EmitTargetCodeForMemcpy - Emit target-specific code that performs a
  /// memcpy. This can be used by targets to provide code sequences for cases
  /// that don't fit the target's parameters for simple loads/stores and can be
  /// more efficient than using a library call. This function can return a null
  /// SDValue if the target declines to use custom code and a different
  /// lowering strategy should be used.
  /// 
  /// If AlwaysInline is true, the size is constant and the target should not
  /// emit any calls and is strongly encouraged to attempt to emit inline code
  /// even if it is beyond the usual threshold because this intrinsic is being
  /// expanded in a place where calls are not feasible (e.g. within the prologue
  /// for another call). If the target chooses to decline an AlwaysInline
  /// request here, legalize will resort to using simple loads and stores.
  virtual SDValue
  EmitTargetCodeForMemcpy(SelectionDAG &DAG, DebugLoc dl,
                          SDValue Chain,
                          SDValue Op1, SDValue Op2,
                          SDValue Op3, unsigned Align, bool isVolatile,
                          bool AlwaysInline,
                          const Value *DstSV, uint64_t DstOff,
                          const Value *SrcSV, uint64_t SrcOff) const {
    return SDValue();
  }

  /// EmitTargetCodeForMemmove - Emit target-specific code that performs a
  /// memmove. This can be used by targets to provide code sequences for cases
  /// that don't fit the target's parameters for simple loads/stores and can be
  /// more efficient than using a library call. This function can return a null
  /// SDValue if the target declines to use custom code and a different
  /// lowering strategy should be used.
  virtual SDValue
  EmitTargetCodeForMemmove(SelectionDAG &DAG, DebugLoc dl,
                           SDValue Chain,
                           SDValue Op1, SDValue Op2,
                           SDValue Op3, unsigned Align, bool isVolatile,
                           const Value *DstSV, uint64_t DstOff,
                           const Value *SrcSV, uint64_t SrcOff) const {
    return SDValue();
  }

  /// EmitTargetCodeForMemset - Emit target-specific code that performs a
  /// memset. This can be used by targets to provide code sequences for cases
  /// that don't fit the target's parameters for simple stores and can be more
  /// efficient than using a library call. This function can return a null
  /// SDValue if the target declines to use custom code and a different
  /// lowering strategy should be used.
  virtual SDValue
  EmitTargetCodeForMemset(SelectionDAG &DAG, DebugLoc dl,
                          SDValue Chain,
                          SDValue Op1, SDValue Op2,
                          SDValue Op3, unsigned Align, bool isVolatile,
                          const Value *DstSV, uint64_t DstOff) const {
    return SDValue();
  }
};

} // end llvm namespace

#endif