lib/Target/X86/X86SelectionDAGInfo.cpp

   1 //===-- X86SelectionDAGInfo.cpp - X86 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 X86SelectionDAGInfo class.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #define DEBUG_TYPE "x86-selectiondag-info"
  15 #include "X86TargetMachine.h"
  16 #include "llvm/DerivedTypes.h"
  17 #include "llvm/CodeGen/SelectionDAG.h"
  18 using namespace llvm;
  19
  20 X86SelectionDAGInfo::X86SelectionDAGInfo(const X86TargetMachine &TM) :
  21   TargetSelectionDAGInfo(TM),
  22   Subtarget(&TM.getSubtarget<X86Subtarget>()),
  23   TLI(*TM.getTargetLowering()) {
  24 }
  25
  26 X86SelectionDAGInfo::~X86SelectionDAGInfo() {
  27 }
  28
  29 SDValue
  30 X86SelectionDAGInfo::EmitTargetCodeForMemset(SelectionDAG &DAG, DebugLoc dl,
  31                                              SDValue Chain,
  32                                              SDValue Dst, SDValue Src,
  33                                              SDValue Size, unsigned Align,
  34                                              bool isVolatile,
  35                                          MachinePointerInfo DstPtrInfo) const {
  36   ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
  37
  38   // If to a segment-relative address space, use the default lowering.
  39   if (DstPtrInfo.getAddrSpace() >= 256)
  40     return SDValue();
  41
  42   // If not DWORD aligned or size is more than the threshold, call the library.
  43   // The libc version is likely to be faster for these cases. It can use the
  44   // address value and run time information about the CPU.
  45   if ((Align & 3) != 0 ||
  46       !ConstantSize ||
  47       ConstantSize->getZExtValue() >
  48         Subtarget->getMaxInlineSizeThreshold()) {
  49     SDValue InFlag(0, 0);
  50
  51     // Check to see if there is a specialized entry-point for memory zeroing.
  52     ConstantSDNode *V = dyn_cast<ConstantSDNode>(Src);
  53
  54     if (const char *bzeroEntry =  V &&
  55         V->isNullValue() ? Subtarget->getBZeroEntry() : 0) {
  56       EVT IntPtr = TLI.getPointerTy();
  57       const Type *IntPtrTy = getTargetData()->getIntPtrType(*DAG.getContext());
  58       TargetLowering::ArgListTy Args;
  59       TargetLowering::ArgListEntry Entry;
  60       Entry.Node = Dst;
  61       Entry.Ty = IntPtrTy;
  62       Args.push_back(Entry);
  63       Entry.Node = Size;
  64       Args.push_back(Entry);
  65       std::pair<SDValue,SDValue> CallResult =
  66         TLI.LowerCallTo(Chain, Type::getVoidTy(*DAG.getContext()),
  67                         false, false, false, false,
  68                         0, CallingConv::C, false, /*isReturnValueUsed=*/false,
  69                         DAG.getExternalSymbol(bzeroEntry, IntPtr), Args,
  70                         DAG, dl);
  71       return CallResult.second;
  72     }
  73
  74     // Otherwise have the target-independent code call memset.
  75     return SDValue();
  76   }
  77
  78   uint64_t SizeVal = ConstantSize->getZExtValue();
  79   SDValue InFlag(0, 0);
  80   EVT AVT;
  81   SDValue Count;
  82   ConstantSDNode *ValC = dyn_cast<ConstantSDNode>(Src);
  83   unsigned BytesLeft = 0;
  84   bool TwoRepStos = false;
  85   if (ValC) {
  86     unsigned ValReg;
  87     uint64_t Val = ValC->getZExtValue() & 255;
  88
  89     // If the value is a constant, then we can potentially use larger sets.
  90     switch (Align & 3) {
  91     case 2:   // WORD aligned
  92       AVT = MVT::i16;
  93       ValReg = X86::AX;
  94       Val = (Val << 8) | Val;
  95       break;
  96     case 0:  // DWORD aligned
  97       AVT = MVT::i32;
  98       ValReg = X86::EAX;
  99       Val = (Val << 8)  | Val;
 100       Val = (Val << 16) | Val;
 101       if (Subtarget->is64Bit() && ((Align & 0x7) == 0)) {  // QWORD aligned
 102         AVT = MVT::i64;
 103         ValReg = X86::RAX;
 104         Val = (Val << 32) | Val;
 105       }
 106       break;
 107     default:  // Byte aligned
 108       AVT = MVT::i8;
 109       ValReg = X86::AL;
 110       Count = DAG.getIntPtrConstant(SizeVal);
 111       break;
 112     }
 113
 114     if (AVT.bitsGT(MVT::i8)) {
 115       unsigned UBytes = AVT.getSizeInBits() / 8;
 116       Count = DAG.getIntPtrConstant(SizeVal / UBytes);
 117       BytesLeft = SizeVal % UBytes;
 118     }
 119
 120     Chain  = DAG.getCopyToReg(Chain, dl, ValReg, DAG.getConstant(Val, AVT),
 121                               InFlag);
 122     InFlag = Chain.getValue(1);
 123   } else {
 124     AVT = MVT::i8;
 125     Count  = DAG.getIntPtrConstant(SizeVal);
 126     Chain  = DAG.getCopyToReg(Chain, dl, X86::AL, Src, InFlag);
 127     InFlag = Chain.getValue(1);
 128   }
 129
 130   Chain  = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RCX :
 131                                                               X86::ECX,
 132                             Count, InFlag);
 133   InFlag = Chain.getValue(1);
 134   Chain  = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RDI :
 135                                                               X86::EDI,
 136                             Dst, InFlag);
 137   InFlag = Chain.getValue(1);
 138
 139   SDVTList Tys = DAG.getVTList(MVT::Other, MVT::Flag);
 140   SDValue Ops[] = { Chain, DAG.getValueType(AVT), InFlag };
 141   Chain = DAG.getNode(X86ISD::REP_STOS, dl, Tys, Ops, array_lengthof(Ops));
 142
 143   if (TwoRepStos) {
 144     InFlag = Chain.getValue(1);
 145     Count  = Size;
 146     EVT CVT = Count.getValueType();
 147     SDValue Left = DAG.getNode(ISD::AND, dl, CVT, Count,
 148                                DAG.getConstant((AVT == MVT::i64) ? 7 : 3, CVT));
 149     Chain  = DAG.getCopyToReg(Chain, dl, (CVT == MVT::i64) ? X86::RCX :
 150                                                              X86::ECX,
 151                               Left, InFlag);
 152     InFlag = Chain.getValue(1);
 153     Tys = DAG.getVTList(MVT::Other, MVT::Flag);
 154     SDValue Ops[] = { Chain, DAG.getValueType(MVT::i8), InFlag };
 155     Chain = DAG.getNode(X86ISD::REP_STOS, dl, Tys, Ops, array_lengthof(Ops));
 156   } else if (BytesLeft) {
 157     // Handle the last 1 - 7 bytes.
 158     unsigned Offset = SizeVal - BytesLeft;
 159     EVT AddrVT = Dst.getValueType();
 160     EVT SizeVT = Size.getValueType();
 161
 162     Chain = DAG.getMemset(Chain, dl,
 163                           DAG.getNode(ISD::ADD, dl, AddrVT, Dst,
 164                                       DAG.getConstant(Offset, AddrVT)),
 165                           Src,
 166                           DAG.getConstant(BytesLeft, SizeVT),
 167                           Align, isVolatile, DstPtrInfo.getWithOffset(Offset));
 168   }
 169
 170   // TODO: Use a Tokenfactor, as in memcpy, instead of a single chain.
 171   return Chain;
 172 }
 173
 174 SDValue
 175 X86SelectionDAGInfo::EmitTargetCodeForMemcpy(SelectionDAG &DAG, DebugLoc dl,
 176                                         SDValue Chain, SDValue Dst, SDValue Src,
 177                                         SDValue Size, unsigned Align,
 178                                         bool isVolatile, bool AlwaysInline,
 179                                          MachinePointerInfo DstPtrInfo,
 180                                          MachinePointerInfo SrcPtrInfo) const {
 181   // This requires the copy size to be a constant, preferrably
 182   // within a subtarget-specific limit.
 183   ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size);
 184   if (!ConstantSize)
 185     return SDValue();
 186   uint64_t SizeVal = ConstantSize->getZExtValue();
 187   if (!AlwaysInline && SizeVal > Subtarget->getMaxInlineSizeThreshold())
 188     return SDValue();
 189
 190   /// If not DWORD aligned, call the library.
 191   if ((Align & 3) != 0)
 192     return SDValue();
 193
 194   // If to a segment-relative address space, use the default lowering.
 195   if (DstPtrInfo.getAddrSpace() >= 256 ||
 196       SrcPtrInfo.getAddrSpace() >= 256)
 197     return SDValue();
 198
 199   // DWORD aligned
 200   EVT AVT = MVT::i32;
 201   if (Subtarget->is64Bit() && ((Align & 0x7) == 0))  // QWORD aligned
 202     AVT = MVT::i64;
 203
 204   unsigned UBytes = AVT.getSizeInBits() / 8;
 205   unsigned CountVal = SizeVal / UBytes;
 206   SDValue Count = DAG.getIntPtrConstant(CountVal);
 207   unsigned BytesLeft = SizeVal % UBytes;
 208
 209   SDValue InFlag(0, 0);
 210   Chain  = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RCX :
 211                                                               X86::ECX,
 212                             Count, InFlag);
 213   InFlag = Chain.getValue(1);
 214   Chain  = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RDI :
 215                                                               X86::EDI,
 216                             Dst, InFlag);
 217   InFlag = Chain.getValue(1);
 218   Chain  = DAG.getCopyToReg(Chain, dl, Subtarget->is64Bit() ? X86::RSI :
 219                                                               X86::ESI,
 220                             Src, InFlag);
 221   InFlag = Chain.getValue(1);
 222
 223   SDVTList Tys = DAG.getVTList(MVT::Other, MVT::Flag);
 224   SDValue Ops[] = { Chain, DAG.getValueType(AVT), InFlag };
 225   SDValue RepMovs = DAG.getNode(X86ISD::REP_MOVS, dl, Tys, Ops,
 226                                 array_lengthof(Ops));
 227
 228   SmallVector<SDValue, 4> Results;
 229   Results.push_back(RepMovs);
 230   if (BytesLeft) {
 231     // Handle the last 1 - 7 bytes.
 232     unsigned Offset = SizeVal - BytesLeft;
 233     EVT DstVT = Dst.getValueType();
 234     EVT SrcVT = Src.getValueType();
 235     EVT SizeVT = Size.getValueType();
 236     Results.push_back(DAG.getMemcpy(Chain, dl,
 237                                     DAG.getNode(ISD::ADD, dl, DstVT, Dst,
 238                                                 DAG.getConstant(Offset, DstVT)),
 239                                     DAG.getNode(ISD::ADD, dl, SrcVT, Src,
 240                                                 DAG.getConstant(Offset, SrcVT)),
 241                                     DAG.getConstant(BytesLeft, SizeVT),
 242                                     Align, isVolatile, AlwaysInline,
 243                                     DstPtrInfo.getWithOffset(Offset),
 244                                     SrcPtrInfo.getWithOffset(Offset)));
 245   }
 246
 247   return DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
 248                      &Results[0], Results.size());
 249 }