lib/Target/BPF/BPFSelectionDAGInfo.cpp

   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 }