BPFSelectionDAGInfo.cpp

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//===-- BPFSelectionDAGInfo.cpp - BPF SelectionDAG Info -------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements the BPFSelectionDAGInfo class.
//
//===----------------------------------------------------------------------===//
 
#include "BPFTargetMachine.h"
#include "llvm/CodeGen/SelectionDAG.h"
using namespace llvm;
 
#define DEBUG_TYPE "bpf-selectiondag-info"
 
SDValue BPFSelectionDAGInfo::EmitTargetCodeForMemcpy(
    SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Dst, SDValue Src,
    SDValue Size, Align Alignment, bool isVolatile, bool AlwaysInline,
    MachinePointerInfo DstPtrInfo, MachinePointerInfo SrcPtrInfo) const {
  // Requires the copy size to be a constant.
  ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
  if (!ConstantSize)
    return SDValue();
 
  unsigned CopyLen = ConstantSize->getZExtValue();
  unsigned StoresNumEstimate = alignTo(CopyLen, Alignment) >> Log2(Alignment);
  // Impose the same copy length limit as MaxStoresPerMemcpy.
  if (StoresNumEstimate > getCommonMaxStoresPerMemFunc())
    return SDValue();
 
  SDVTList VTs = DAG.getVTList(MVT::Other, MVT::Glue);
 
  Dst = DAG.getNode(BPFISD::MEMCPY, dl, VTs, Chain, Dst, Src,
                    DAG.getConstant(CopyLen, dl, MVT::i64),
                    DAG.getConstant(Alignment.value(), dl, MVT::i64));
 
  return Dst.getValue(0);
}