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//==- llvm/CodeGen/SelectionDAGTargetInfo.h - SelectionDAG Info --*- C++ -*-==//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file declares the SelectionDAGTargetInfo class, which targets can
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// subclass to parameterize the SelectionDAG lowering and instruction
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// selection process.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_SELECTIONDAGTARGETINFO_H
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#define LLVM_CODEGEN_SELECTIONDAGTARGETINFO_H
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#include "llvm/CodeGen/MachineMemOperand.h"
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#include "llvm/CodeGen/SelectionDAGNodes.h"
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#include "llvm/Support/CodeGen.h"
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#include <utility>
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namespace llvm {
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class SelectionDAG;
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//===----------------------------------------------------------------------===//
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/// Targets can subclass this to parameterize the
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/// SelectionDAG lowering and instruction selection process.
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///
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class SelectionDAGTargetInfo {
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public:
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  explicit SelectionDAGTargetInfo() = default;
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  SelectionDAGTargetInfo(const SelectionDAGTargetInfo &) = delete;
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  SelectionDAGTargetInfo &operator=(const SelectionDAGTargetInfo &) = delete;
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  virtual ~SelectionDAGTargetInfo();
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  /// Emit target-specific code that performs a memcpy.
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  /// This can be used by targets to provide code sequences for cases
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  /// that don't fit the target's parameters for simple loads/stores and can be
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  /// more efficient than using a library call. This function can return a null
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  /// SDValue if the target declines to use custom code and a different
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  /// lowering strategy should be used.
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  ///
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  /// If AlwaysInline is true, the size is constant and the target should not
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  /// emit any calls and is strongly encouraged to attempt to emit inline code
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  /// even if it is beyond the usual threshold because this intrinsic is being
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  /// expanded in a place where calls are not feasible (e.g. within the prologue
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  /// for another call). If the target chooses to decline an AlwaysInline
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  /// request here, legalize will resort to using simple loads and stores.
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  virtual SDValue EmitTargetCodeForMemcpy(SelectionDAG &DAG, const SDLoc &dl,
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                                          SDValue Chain, SDValue Op1,
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                                          SDValue Op2, SDValue Op3,
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                                          Align Alignment, bool isVolatile,
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                                          bool AlwaysInline,
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                                          MachinePointerInfo DstPtrInfo,
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                                          MachinePointerInfo SrcPtrInfo) const {
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    return SDValue();
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  }
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  /// Emit target-specific code that performs a memmove.
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  /// This can be used by targets to provide code sequences for cases
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  /// that don't fit the target's parameters for simple loads/stores and can be
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  /// more efficient than using a library call. This function can return a null
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  /// SDValue if the target declines to use custom code and a different
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  /// lowering strategy should be used.
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  virtual SDValue EmitTargetCodeForMemmove(
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      SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Op1,
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      SDValue Op2, SDValue Op3, Align Alignment, bool isVolatile,
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      MachinePointerInfo DstPtrInfo, MachinePointerInfo SrcPtrInfo) const {
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    return SDValue();
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  }
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  /// Emit target-specific code that performs a memset.
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  /// This can be used by targets to provide code sequences for cases
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  /// that don't fit the target's parameters for simple stores and can be more
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  /// efficient than using a library call. This function can return a null
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  /// SDValue if the target declines to use custom code and a different
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  /// lowering strategy should be used. Note that if AlwaysInline is true the
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  /// function has to return a valid SDValue.
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  virtual SDValue EmitTargetCodeForMemset(SelectionDAG &DAG, const SDLoc &dl,
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                                          SDValue Chain, SDValue Op1,
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                                          SDValue Op2, SDValue Op3,
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                                          Align Alignment, bool isVolatile,
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                                          bool AlwaysInline,
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                                          MachinePointerInfo DstPtrInfo) const {
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    return SDValue();
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  }
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  /// Emit target-specific code that performs a memcmp/bcmp, in cases where that is
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  /// faster than a libcall. The first returned SDValue is the result of the
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  /// memcmp and the second is the chain. Both SDValues can be null if a normal
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  /// libcall should be used.
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  virtual std::pair<SDValue, SDValue>
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  EmitTargetCodeForMemcmp(SelectionDAG &DAG, const SDLoc &dl, SDValue Chain,
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                          SDValue Op1, SDValue Op2, SDValue Op3,
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                          MachinePointerInfo Op1PtrInfo,
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                          MachinePointerInfo Op2PtrInfo) const {
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    return std::make_pair(SDValue(), SDValue());
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  }
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  /// Emit target-specific code that performs a memchr, in cases where that is
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  /// faster than a libcall. The first returned SDValue is the result of the
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  /// memchr and the second is the chain. Both SDValues can be null if a normal
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  /// libcall should be used.
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  virtual std::pair<SDValue, SDValue>
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  EmitTargetCodeForMemchr(SelectionDAG &DAG, const SDLoc &dl, SDValue Chain,
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                          SDValue Src, SDValue Char, SDValue Length,
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                          MachinePointerInfo SrcPtrInfo) const {
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    return std::make_pair(SDValue(), SDValue());
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  }
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  /// Emit target-specific code that performs a strcpy or stpcpy, in cases
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  /// where that is faster than a libcall.
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  /// The first returned SDValue is the result of the copy (the start
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  /// of the destination string for strcpy, a pointer to the null terminator
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  /// for stpcpy) and the second is the chain.  Both SDValues can be null
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  /// if a normal libcall should be used.
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  virtual std::pair<SDValue, SDValue>
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  EmitTargetCodeForStrcpy(SelectionDAG &DAG, const SDLoc &DL, SDValue Chain,
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                          SDValue Dest, SDValue Src,
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                          MachinePointerInfo DestPtrInfo,
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                          MachinePointerInfo SrcPtrInfo, bool isStpcpy) const {
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    return std::make_pair(SDValue(), SDValue());
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  }
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  /// Emit target-specific code that performs a strcmp, in cases where that is
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  /// faster than a libcall.
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  /// The first returned SDValue is the result of the strcmp and the second is
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  /// the chain. Both SDValues can be null if a normal libcall should be used.
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  virtual std::pair<SDValue, SDValue>
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  EmitTargetCodeForStrcmp(SelectionDAG &DAG, const SDLoc &dl, SDValue Chain,
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                          SDValue Op1, SDValue Op2,
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                          MachinePointerInfo Op1PtrInfo,
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                          MachinePointerInfo Op2PtrInfo) const {
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    return std::make_pair(SDValue(), SDValue());
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  }
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  virtual std::pair<SDValue, SDValue>
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  EmitTargetCodeForStrlen(SelectionDAG &DAG, const SDLoc &DL, SDValue Chain,
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                          SDValue Src, MachinePointerInfo SrcPtrInfo) const {
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    return std::make_pair(SDValue(), SDValue());
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  }
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  virtual std::pair<SDValue, SDValue>
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  EmitTargetCodeForStrnlen(SelectionDAG &DAG, const SDLoc &DL, SDValue Chain,
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                           SDValue Src, SDValue MaxLength,
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                           MachinePointerInfo SrcPtrInfo) const {
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    return std::make_pair(SDValue(), SDValue());
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  }
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  virtual SDValue EmitTargetCodeForSetTag(SelectionDAG &DAG, const SDLoc &dl,
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                                          SDValue Chain, SDValue Addr,
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                                          SDValue Size,
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                                          MachinePointerInfo DstPtrInfo,
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                                          bool ZeroData) const {
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    return SDValue();
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  }
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  // Return true if the DAG Combiner should disable generic combines.
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  virtual bool disableGenericCombines(CodeGenOpt::Level OptLevel) const {
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    return false;
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  }
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};
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} // end namespace llvm
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#endif // LLVM_CODEGEN_SELECTIONDAGTARGETINFO_H