text: //==-- 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 DataLayout;
  class TargetMachine;
  
  //===----------------------------------------------------------------------===//
  /// TargetSelectionDAGInfo - Targets can subclass this to parameterize the
  /// SelectionDAG lowering and instruction selection process.
  ///
  class TargetSelectionDAGInfo {
    TargetSelectionDAGInfo(const TargetSelectionDAGInfo &) LLVM_DELETED_FUNCTION;
    void operator=(const TargetSelectionDAGInfo &) LLVM_DELETED_FUNCTION;
  
    const DataLayout *DL;
  
  protected:
    const DataLayout *getDataLayout() const { return DL; }
  
  public:
    explicit TargetSelectionDAGInfo(const DataLayout *DL);
    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, SDLoc dl,
                            SDValue Chain,
                            SDValue Op1, SDValue Op2,
                            SDValue Op3, unsigned Align, bool isVolatile,
                            bool AlwaysInline,
                            MachinePointerInfo DstPtrInfo,
                            MachinePointerInfo SrcPtrInfo) 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, SDLoc dl,
                             SDValue Chain,
                             SDValue Op1, SDValue Op2,
                             SDValue Op3, unsigned Align, bool isVolatile,
                             MachinePointerInfo DstPtrInfo,
                             MachinePointerInfo SrcPtrInfo) 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, SDLoc dl,
                            SDValue Chain,
                            SDValue Op1, SDValue Op2,
                            SDValue Op3, unsigned Align, bool isVolatile,
                            MachinePointerInfo DstPtrInfo) const {
      return SDValue();
    }
  
    /// EmitTargetCodeForMemcmp - Emit target-specific code that performs a
    /// memcmp, in cases where that is faster than a libcall.  The first
    /// returned SDValue is the result of the memcmp and the second is
    /// the chain.  Both SDValues can be null if a normal libcall should
    /// be used.
    virtual std::pair<SDValue, SDValue>
    EmitTargetCodeForMemcmp(SelectionDAG &DAG, SDLoc dl,
                            SDValue Chain,
                            SDValue Op1, SDValue Op2,
                            SDValue Op3, MachinePointerInfo Op1PtrInfo,
                            MachinePointerInfo Op2PtrInfo) const {
      return std::make_pair(SDValue(), SDValue());
    }
  
    /// EmitTargetCodeForMemchr - Emit target-specific code that performs a
    /// memchr, in cases where that is faster than a libcall.  The first
    /// returned SDValue is the result of the memchr and the second is
    /// the chain.  Both SDValues can be null if a normal libcall should
    /// be used.
    virtual std::pair<SDValue, SDValue>
    EmitTargetCodeForMemchr(SelectionDAG &DAG, SDLoc dl, SDValue Chain,
                            SDValue Src, SDValue Char, SDValue Length,
                            MachinePointerInfo SrcPtrInfo) const {
      return std::make_pair(SDValue(), SDValue());
    }
  
    /// EmitTargetCodeForStrcpy - Emit target-specific code that performs a
    /// strcpy or stpcpy, in cases where that is faster than a libcall.
    /// The first returned SDValue is the result of the copy (the start
    /// of the destination string for strcpy, a pointer to the null terminator
    /// for stpcpy) and the second is the chain.  Both SDValues can be null
    /// if a normal libcall should be used.
    virtual std::pair<SDValue, SDValue>
    EmitTargetCodeForStrcpy(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
                            SDValue Dest, SDValue Src,
                            MachinePointerInfo DestPtrInfo,
                            MachinePointerInfo SrcPtrInfo,
                            bool isStpcpy) const {
      return std::make_pair(SDValue(), SDValue());
    }
  
    /// EmitTargetCodeForStrcmp - Emit target-specific code that performs a
    /// strcmp, in cases where that is faster than a libcall.  The first
    /// returned SDValue is the result of the strcmp and the second is
    /// the chain.  Both SDValues can be null if a normal libcall should
    /// be used.
    virtual std::pair<SDValue, SDValue>
    EmitTargetCodeForStrcmp(SelectionDAG &DAG, SDLoc dl,
                            SDValue Chain,
                            SDValue Op1, SDValue Op2,
                            MachinePointerInfo Op1PtrInfo,
                            MachinePointerInfo Op2PtrInfo) const {
      return std::make_pair(SDValue(), SDValue());
    }
  
    virtual std::pair<SDValue, SDValue>
    EmitTargetCodeForStrlen(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
                            SDValue Src, MachinePointerInfo SrcPtrInfo) const {
      return std::make_pair(SDValue(), SDValue());
    }
  
    virtual std::pair<SDValue, SDValue>
    EmitTargetCodeForStrnlen(SelectionDAG &DAG, SDLoc DL, SDValue Chain,
                             SDValue Src, SDValue MaxLength,
                             MachinePointerInfo SrcPtrInfo) const {
      return std::make_pair(SDValue(), SDValue());
    }
  };
  
  } // end llvm namespace
  
  #endif
  