1 //===-- BPFSelectionDAGInfo.cpp - BPF SelectionDAG Info -------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the BPFSelectionDAGInfo class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "BPFTargetMachine.h"
15 #include "llvm/CodeGen/SelectionDAG.h"
16 #include "llvm/IR/DerivedTypes.h"
17 using namespace llvm;
18 
19 #define DEBUG_TYPE "bpf-selectiondag-info"
20 
21 SDValue BPFSelectionDAGInfo::EmitTargetCodeForMemcpy(
22     SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Dst, SDValue Src,
23     SDValue Size, unsigned Align, bool isVolatile, bool AlwaysInline,
24     MachinePointerInfo DstPtrInfo, MachinePointerInfo SrcPtrInfo) const {
25   // Requires the copy size to be a constant.
26   ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
27   if (!ConstantSize)
28     return SDValue();
29 
30   unsigned CopyLen = ConstantSize->getZExtValue();
31   unsigned StoresNumEstimate = alignTo(CopyLen, Align) >> Log2_32(Align);
32   // Impose the same copy length limit as MaxStoresPerMemcpy.
33   if (StoresNumEstimate > getCommonMaxStoresPerMemFunc())
34     return SDValue();
35 
36   SDVTList VTs = DAG.getVTList(MVT::Other, MVT::Glue);
37 
38   Dst = DAG.getNode(BPFISD::MEMCPY, dl, VTs, Chain, Dst, Src,
39                     DAG.getConstant(CopyLen, dl, MVT::i64),
40                     DAG.getConstant(Align, dl, MVT::i64));
41 
42   return Dst.getValue(0);
43 }
44