1//===-- BPFSelectionDAGInfo.cpp - BPF SelectionDAG Info -------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the BPFSelectionDAGInfo class.
10//
11//===----------------------------------------------------------------------===//
12
13#include "BPFTargetMachine.h"
14#include "llvm/CodeGen/SelectionDAG.h"
15#include "llvm/IR/DerivedTypes.h"
16using namespace llvm;
17
18#define DEBUG_TYPE "bpf-selectiondag-info"
19
20SDValue BPFSelectionDAGInfo::EmitTargetCodeForMemcpy(
21    SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Dst, SDValue Src,
22    SDValue Size, Align Alignment, bool isVolatile, bool AlwaysInline,
23    MachinePointerInfo DstPtrInfo, MachinePointerInfo SrcPtrInfo) const {
24  // Requires the copy size to be a constant.
25  ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
26  if (!ConstantSize)
27    return SDValue();
28
29  unsigned CopyLen = ConstantSize->getZExtValue();
30  unsigned StoresNumEstimate = alignTo(CopyLen, Alignment) >> Log2(Alignment);
31  // Impose the same copy length limit as MaxStoresPerMemcpy.
32  if (StoresNumEstimate > getCommonMaxStoresPerMemFunc())
33    return SDValue();
34
35  SDVTList VTs = DAG.getVTList(MVT::Other, MVT::Glue);
36
37  Dst = DAG.getNode(BPFISD::MEMCPY, dl, VTs, Chain, Dst, Src,
38                    DAG.getConstant(CopyLen, dl, MVT::i64),
39                    DAG.getConstant(Alignment.value(), dl, MVT::i64));
40
41  return Dst.getValue(0);
42}
43