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	as it caused miscompilations and assertion failures (PR23768, http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20150601/280380.html). git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239169 91177308-0d34-0410-b5e6-96231b3b80d8
		
			
				
	
	
		
			278 lines
		
	
	
		
			9.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			278 lines
		
	
	
		
			9.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
//===-- ARMSelectionDAGInfo.cpp - ARM SelectionDAG Info -------------------===//
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//
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//                     The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the ARMSelectionDAGInfo class.
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//
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//===----------------------------------------------------------------------===//
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#include "ARMTargetMachine.h"
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#include "llvm/CodeGen/SelectionDAG.h"
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#include "llvm/IR/DerivedTypes.h"
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using namespace llvm;
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#define DEBUG_TYPE "arm-selectiondag-info"
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ARMSelectionDAGInfo::ARMSelectionDAGInfo(const DataLayout &DL)
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    : TargetSelectionDAGInfo(&DL) {}
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ARMSelectionDAGInfo::~ARMSelectionDAGInfo() {
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}
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// Emit, if possible, a specialized version of the given Libcall. Typically this
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// means selecting the appropriately aligned version, but we also convert memset
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// of 0 into memclr.
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SDValue ARMSelectionDAGInfo::
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EmitSpecializedLibcall(SelectionDAG &DAG, SDLoc dl,
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                       SDValue Chain,
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                       SDValue Dst, SDValue Src,
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                       SDValue Size, unsigned Align,
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                       RTLIB::Libcall LC) const {
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  const ARMSubtarget &Subtarget =
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      DAG.getMachineFunction().getSubtarget<ARMSubtarget>();
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  const ARMTargetLowering *TLI = Subtarget.getTargetLowering();
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  // Only use a specialized AEABI function if the default version of this
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  // Libcall is an AEABI function.
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  if (std::strncmp(TLI->getLibcallName(LC), "__aeabi", 7) != 0)
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    return SDValue();
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  // Translate RTLIB::Libcall to AEABILibcall. We only do this in order to be
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  // able to translate memset to memclr and use the value to index the function
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  // name array.
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  enum {
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    AEABI_MEMCPY = 0,
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    AEABI_MEMMOVE,
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    AEABI_MEMSET,
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    AEABI_MEMCLR
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  } AEABILibcall;
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  switch (LC) {
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  case RTLIB::MEMCPY:
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    AEABILibcall = AEABI_MEMCPY;
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    break;
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  case RTLIB::MEMMOVE:
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    AEABILibcall = AEABI_MEMMOVE;
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    break;
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  case RTLIB::MEMSET: 
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    AEABILibcall = AEABI_MEMSET;
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    if (ConstantSDNode *ConstantSrc = dyn_cast<ConstantSDNode>(Src))
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      if (ConstantSrc->getZExtValue() == 0)
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        AEABILibcall = AEABI_MEMCLR;
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    break;
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  default:
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    return SDValue();
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  }
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  // Choose the most-aligned libcall variant that we can
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  enum {
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    ALIGN1 = 0,
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    ALIGN4,
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    ALIGN8
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  } AlignVariant;
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  if ((Align & 7) == 0)
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    AlignVariant = ALIGN8;
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  else if ((Align & 3) == 0)
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    AlignVariant = ALIGN4;
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  else
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    AlignVariant = ALIGN1;
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  TargetLowering::ArgListTy Args;
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  TargetLowering::ArgListEntry Entry;
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  Entry.Ty = TLI->getDataLayout()->getIntPtrType(*DAG.getContext());
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  Entry.Node = Dst;
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  Args.push_back(Entry);
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  if (AEABILibcall == AEABI_MEMCLR) {
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    Entry.Node = Size;
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    Args.push_back(Entry);
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  } else if (AEABILibcall == AEABI_MEMSET) {
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    // Adjust parameters for memset, EABI uses format (ptr, size, value),
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    // GNU library uses (ptr, value, size)
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    // See RTABI section 4.3.4
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    Entry.Node = Size;
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    Args.push_back(Entry);
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    // Extend or truncate the argument to be an i32 value for the call.
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    if (Src.getValueType().bitsGT(MVT::i32))
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      Src = DAG.getNode(ISD::TRUNCATE, dl, MVT::i32, Src);
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    else if (Src.getValueType().bitsLT(MVT::i32))
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      Src = DAG.getNode(ISD::ZERO_EXTEND, dl, MVT::i32, Src);
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    Entry.Node = Src; 
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    Entry.Ty = Type::getInt32Ty(*DAG.getContext());
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    Entry.isSExt = false;
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    Args.push_back(Entry);
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  } else {
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    Entry.Node = Src;
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    Args.push_back(Entry);
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    Entry.Node = Size;
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    Args.push_back(Entry);
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  }
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  char const *FunctionNames[4][3] = {
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    { "__aeabi_memcpy",  "__aeabi_memcpy4",  "__aeabi_memcpy8"  },
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    { "__aeabi_memmove", "__aeabi_memmove4", "__aeabi_memmove8" },
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    { "__aeabi_memset",  "__aeabi_memset4",  "__aeabi_memset8"  },
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    { "__aeabi_memclr",  "__aeabi_memclr4",  "__aeabi_memclr8"  }
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  };
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  TargetLowering::CallLoweringInfo CLI(DAG);
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  CLI.setDebugLoc(dl).setChain(Chain)
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    .setCallee(TLI->getLibcallCallingConv(LC),
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               Type::getVoidTy(*DAG.getContext()),
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               DAG.getExternalSymbol(FunctionNames[AEABILibcall][AlignVariant],
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                                     TLI->getPointerTy()), std::move(Args), 0)
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    .setDiscardResult();
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  std::pair<SDValue,SDValue> CallResult = TLI->LowerCallTo(CLI);
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  return CallResult.second;
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}
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SDValue
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ARMSelectionDAGInfo::EmitTargetCodeForMemcpy(SelectionDAG &DAG, SDLoc dl,
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                                             SDValue Chain,
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                                             SDValue Dst, SDValue Src,
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                                             SDValue Size, unsigned Align,
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                                             bool isVolatile, bool AlwaysInline,
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                                             MachinePointerInfo DstPtrInfo,
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                                          MachinePointerInfo SrcPtrInfo) const {
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  const ARMSubtarget &Subtarget =
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      DAG.getMachineFunction().getSubtarget<ARMSubtarget>();
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  // Do repeated 4-byte loads and stores. To be improved.
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  // This requires 4-byte alignment.
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  if ((Align & 3) != 0)
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    return SDValue();
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  // This requires the copy size to be a constant, preferably
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  // within a subtarget-specific limit.
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  ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
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  if (!ConstantSize)
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    return EmitSpecializedLibcall(DAG, dl, Chain, Dst, Src, Size, Align,
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                                  RTLIB::MEMCPY);
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  uint64_t SizeVal = ConstantSize->getZExtValue();
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  if (!AlwaysInline && SizeVal > Subtarget.getMaxInlineSizeThreshold())
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    return EmitSpecializedLibcall(DAG, dl, Chain, Dst, Src, Size, Align,
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                                  RTLIB::MEMCPY);
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  unsigned BytesLeft = SizeVal & 3;
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  unsigned NumMemOps = SizeVal >> 2;
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  unsigned EmittedNumMemOps = 0;
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  EVT VT = MVT::i32;
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  unsigned VTSize = 4;
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  unsigned i = 0;
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  // Emit a maximum of 4 loads in Thumb1 since we have fewer registers
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  const unsigned MAX_LOADS_IN_LDM = Subtarget.isThumb1Only() ? 4 : 6;
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  SDValue TFOps[6];
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  SDValue Loads[6];
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  uint64_t SrcOff = 0, DstOff = 0;
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  // Emit up to MAX_LOADS_IN_LDM loads, then a TokenFactor barrier, then the
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  // same number of stores.  The loads and stores will get combined into
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  // ldm/stm later on.
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  while (EmittedNumMemOps < NumMemOps) {
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    for (i = 0;
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         i < MAX_LOADS_IN_LDM && EmittedNumMemOps + i < NumMemOps; ++i) {
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      Loads[i] = DAG.getLoad(VT, dl, Chain,
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                             DAG.getNode(ISD::ADD, dl, MVT::i32, Src,
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                                         DAG.getConstant(SrcOff, dl, MVT::i32)),
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                             SrcPtrInfo.getWithOffset(SrcOff), isVolatile,
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                             false, false, 0);
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      TFOps[i] = Loads[i].getValue(1);
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      SrcOff += VTSize;
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    }
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    Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
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                        makeArrayRef(TFOps, i));
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    for (i = 0;
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         i < MAX_LOADS_IN_LDM && EmittedNumMemOps + i < NumMemOps; ++i) {
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      TFOps[i] = DAG.getStore(Chain, dl, Loads[i],
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                              DAG.getNode(ISD::ADD, dl, MVT::i32, Dst,
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                                          DAG.getConstant(DstOff, dl, MVT::i32)),
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                              DstPtrInfo.getWithOffset(DstOff),
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                              isVolatile, false, 0);
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      DstOff += VTSize;
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    }
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    Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
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                        makeArrayRef(TFOps, i));
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    EmittedNumMemOps += i;
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  }
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  if (BytesLeft == 0)
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    return Chain;
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  // Issue loads / stores for the trailing (1 - 3) bytes.
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  unsigned BytesLeftSave = BytesLeft;
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  i = 0;
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  while (BytesLeft) {
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    if (BytesLeft >= 2) {
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      VT = MVT::i16;
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      VTSize = 2;
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    } else {
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      VT = MVT::i8;
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      VTSize = 1;
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    }
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    Loads[i] = DAG.getLoad(VT, dl, Chain,
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                           DAG.getNode(ISD::ADD, dl, MVT::i32, Src,
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                                       DAG.getConstant(SrcOff, dl, MVT::i32)),
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                           SrcPtrInfo.getWithOffset(SrcOff),
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                           false, false, false, 0);
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    TFOps[i] = Loads[i].getValue(1);
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    ++i;
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    SrcOff += VTSize;
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    BytesLeft -= VTSize;
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  }
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  Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
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                      makeArrayRef(TFOps, i));
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  i = 0;
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  BytesLeft = BytesLeftSave;
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  while (BytesLeft) {
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    if (BytesLeft >= 2) {
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      VT = MVT::i16;
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      VTSize = 2;
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    } else {
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      VT = MVT::i8;
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      VTSize = 1;
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    }
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    TFOps[i] = DAG.getStore(Chain, dl, Loads[i],
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                            DAG.getNode(ISD::ADD, dl, MVT::i32, Dst,
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                                        DAG.getConstant(DstOff, dl, MVT::i32)),
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                            DstPtrInfo.getWithOffset(DstOff), false, false, 0);
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    ++i;
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    DstOff += VTSize;
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    BytesLeft -= VTSize;
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  }
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  return DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
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                     makeArrayRef(TFOps, i));
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}
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SDValue ARMSelectionDAGInfo::
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EmitTargetCodeForMemmove(SelectionDAG &DAG, SDLoc dl,
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                         SDValue Chain,
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                         SDValue Dst, SDValue Src,
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                         SDValue Size, unsigned Align,
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                         bool isVolatile,
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                         MachinePointerInfo DstPtrInfo,
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                         MachinePointerInfo SrcPtrInfo) const {
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  return EmitSpecializedLibcall(DAG, dl, Chain, Dst, Src, Size, Align,
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                                RTLIB::MEMMOVE);
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}
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SDValue ARMSelectionDAGInfo::
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EmitTargetCodeForMemset(SelectionDAG &DAG, SDLoc dl,
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                        SDValue Chain, SDValue Dst,
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                        SDValue Src, SDValue Size,
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                        unsigned Align, bool isVolatile,
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                        MachinePointerInfo DstPtrInfo) const {
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  return EmitSpecializedLibcall(DAG, dl, Chain, Dst, Src, Size, Align,
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                                RTLIB::MEMSET);
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}
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