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 
20 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