llvm/lib/Target/XCore/XCoreSelectionDAGInfo.cpp

//===-- XCoreSelectionDAGInfo.cpp - XCore SelectionDAG Info ---------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the XCoreSelectionDAGInfo class.
//
//===----------------------------------------------------------------------===//

#include "XCoreSelectionDAGInfo.h"
#include "XCoreTargetMachine.h"

#define GET_SDNODE_DESC
#include "XCoreGenSDNodeInfo.inc"

using namespace llvm;

#define DEBUG_TYPE "xcore-selectiondag-info"

XCoreSelectionDAGInfo::XCoreSelectionDAGInfo()
    : SelectionDAGGenTargetInfo(XCoreGenSDNodeInfo) {}

SDValue XCoreSelectionDAGInfo::EmitTargetCodeForMemcpy(
    SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Dst, SDValue Src,
    SDValue Size, Align DstAlign, Align SrcAlign, bool isVolatile,
    bool AlwaysInline, MachinePointerInfo DstPtrInfo,
    MachinePointerInfo SrcPtrInfo) const {
  unsigned SizeBitWidth = Size.getValueSizeInBits();
  // Call __memcpy_4 if the src, dst and size are all 4 byte aligned.
  if (!AlwaysInline && SrcAlign >= Align(4) && DstAlign >= Align(4) &&
      DAG.MaskedValueIsZero(Size, APInt(SizeBitWidth, 3))) {
    const TargetLowering &TLI = *DAG.getSubtarget().getTargetLowering();
    TargetLowering::ArgListTy Args;
    Type *ArgTy = DAG.getDataLayout().getIntPtrType(*DAG.getContext());
    Args.emplace_back(Dst, ArgTy);
    Args.emplace_back(Src, ArgTy);
    Args.emplace_back(Size, ArgTy);

    RTLIB::LibcallImpl MemcpyAlign4Impl =
        DAG.getLibcalls().getLibcallImpl(RTLIB::MEMCPY_ALIGN_4);
    if (MemcpyAlign4Impl == RTLIB::Unsupported)
      return SDValue();

    CallingConv::ID CC =
        DAG.getLibcalls().getLibcallImplCallingConv(MemcpyAlign4Impl);

    TargetLowering::CallLoweringInfo CLI(DAG);
    CLI.setDebugLoc(dl)
        .setChain(Chain)
        .setLibCallee(
            CC, Type::getVoidTy(*DAG.getContext()),
            DAG.getExternalSymbol(MemcpyAlign4Impl,
                                  TLI.getPointerTy(DAG.getDataLayout())),
            std::move(Args))
        .setDiscardResult();

    std::pair<SDValue,SDValue> CallResult = TLI.LowerCallTo(CLI);
    return CallResult.second;
  }

  // Otherwise have the target-independent code call memcpy.
  return SDValue();
}