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"
16 using namespace llvm;
17
18 #define DEBUG_TYPE "bpf-selectiondag-info"
19
EmitTargetCodeForMemcpy(SelectionDAG & DAG,const SDLoc & dl,SDValue Chain,SDValue Dst,SDValue Src,SDValue Size,Align Alignment,bool isVolatile,bool AlwaysInline,MachinePointerInfo DstPtrInfo,MachinePointerInfo SrcPtrInfo) const20 SDValue 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