|  | //===-- X86SelectionDAGInfo.cpp - X86 SelectionDAG Info -------------------===// | 
|  | // | 
|  | //                     The LLVM Compiler Infrastructure | 
|  | // | 
|  | // This file is distributed under the University of Illinois Open Source | 
|  | // License. See LICENSE.TXT for details. | 
|  | // | 
|  | //===----------------------------------------------------------------------===// | 
|  | // | 
|  | // This file implements the X86SelectionDAGInfo class. | 
|  | // | 
|  | //===----------------------------------------------------------------------===// | 
|  |  | 
|  | #include "X86InstrInfo.h" | 
|  | #include "X86ISelLowering.h" | 
|  | #include "X86RegisterInfo.h" | 
|  | #include "X86Subtarget.h" | 
|  | #include "X86SelectionDAGInfo.h" | 
|  | #include "llvm/CodeGen/SelectionDAG.h" | 
|  | #include "llvm/IR/DerivedTypes.h" | 
|  | #include "llvm/Target/TargetLowering.h" | 
|  |  | 
|  | using namespace llvm; | 
|  |  | 
|  | #define DEBUG_TYPE "x86-selectiondag-info" | 
|  |  | 
|  | bool X86SelectionDAGInfo::isBaseRegConflictPossible( | 
|  | SelectionDAG &DAG, ArrayRef<MCPhysReg> ClobberSet) const { | 
|  | // We cannot use TRI->hasBasePointer() until *after* we select all basic | 
|  | // blocks.  Legalization may introduce new stack temporaries with large | 
|  | // alignment requirements.  Fall back to generic code if there are any | 
|  | // dynamic stack adjustments (hopefully rare) and the base pointer would | 
|  | // conflict if we had to use it. | 
|  | MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo(); | 
|  | if (!MFI->hasVarSizedObjects() && !MFI->hasOpaqueSPAdjustment()) | 
|  | return false; | 
|  |  | 
|  | const X86RegisterInfo *TRI = static_cast<const X86RegisterInfo *>( | 
|  | DAG.getSubtarget().getRegisterInfo()); | 
|  | unsigned BaseReg = TRI->getBaseRegister(); | 
|  | for (unsigned R : ClobberSet) | 
|  | if (BaseReg == R) | 
|  | return true; | 
|  | return false; | 
|  | } | 
|  |  | 
|  | SDValue X86SelectionDAGInfo::EmitTargetCodeForMemset( | 
|  | SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Dst, SDValue Src, | 
|  | SDValue Size, unsigned Align, bool isVolatile, | 
|  | MachinePointerInfo DstPtrInfo) const { | 
|  | ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size); | 
|  | const X86Subtarget &Subtarget = | 
|  | DAG.getMachineFunction().getSubtarget<X86Subtarget>(); | 
|  |  | 
|  | #ifndef NDEBUG | 
|  | // If the base register might conflict with our physical registers, bail out. | 
|  | const MCPhysReg ClobberSet[] = {X86::RCX, X86::RAX, X86::RDI, | 
|  | X86::ECX, X86::EAX, X86::EDI}; | 
|  | assert(!isBaseRegConflictPossible(DAG, ClobberSet)); | 
|  | #endif | 
|  |  | 
|  | // If to a segment-relative address space, use the default lowering. | 
|  | if (DstPtrInfo.getAddrSpace() >= 256) | 
|  | return SDValue(); | 
|  |  | 
|  | // If not DWORD aligned or size is more than the threshold, call the library. | 
|  | // The libc version is likely to be faster for these cases. It can use the | 
|  | // address value and run time information about the CPU. | 
|  | if ((Align & 3) != 0 || !ConstantSize || | 
|  | ConstantSize->getZExtValue() > Subtarget.getMaxInlineSizeThreshold()) { | 
|  | // Check to see if there is a specialized entry-point for memory zeroing. | 
|  | ConstantSDNode *V = dyn_cast<ConstantSDNode>(Src); | 
|  |  | 
|  | if (const char *bzeroEntry = V && | 
|  | V->isNullValue() ? Subtarget.getBZeroEntry() : nullptr) { | 
|  | const TargetLowering &TLI = DAG.getTargetLoweringInfo(); | 
|  | EVT IntPtr = TLI.getPointerTy(DAG.getDataLayout()); | 
|  | Type *IntPtrTy = DAG.getDataLayout().getIntPtrType(*DAG.getContext()); | 
|  | TargetLowering::ArgListTy Args; | 
|  | TargetLowering::ArgListEntry Entry; | 
|  | Entry.Node = Dst; | 
|  | Entry.Ty = IntPtrTy; | 
|  | Args.push_back(Entry); | 
|  | Entry.Node = Size; | 
|  | Args.push_back(Entry); | 
|  |  | 
|  | TargetLowering::CallLoweringInfo CLI(DAG); | 
|  | CLI.setDebugLoc(dl).setChain(Chain) | 
|  | .setCallee(CallingConv::C, Type::getVoidTy(*DAG.getContext()), | 
|  | DAG.getExternalSymbol(bzeroEntry, IntPtr), std::move(Args)) | 
|  | .setDiscardResult(); | 
|  |  | 
|  | std::pair<SDValue,SDValue> CallResult = TLI.LowerCallTo(CLI); | 
|  | return CallResult.second; | 
|  | } | 
|  |  | 
|  | // Otherwise have the target-independent code call memset. | 
|  | return SDValue(); | 
|  | } | 
|  |  | 
|  | uint64_t SizeVal = ConstantSize->getZExtValue(); | 
|  | SDValue InFlag; | 
|  | EVT AVT; | 
|  | SDValue Count; | 
|  | ConstantSDNode *ValC = dyn_cast<ConstantSDNode>(Src); | 
|  | unsigned BytesLeft = 0; | 
|  | bool TwoRepStos = false; | 
|  | if (ValC) { | 
|  | unsigned ValReg; | 
|  | uint64_t Val = ValC->getZExtValue() & 255; | 
|  |  | 
|  | // If the value is a constant, then we can potentially use larger sets. | 
|  | switch (Align & 3) { | 
|  | case 2:   // WORD aligned | 
|  | AVT = MVT::i16; | 
|  | ValReg = X86::AX; | 
|  | Val = (Val << 8) | Val; | 
|  | break; | 
|  | case 0:  // DWORD aligned | 
|  | AVT = MVT::i32; | 
|  | ValReg = X86::EAX; | 
|  | Val = (Val << 8)  | Val; | 
|  | Val = (Val << 16) | Val; | 
|  | if (Subtarget.is64Bit() && ((Align & 0x7) == 0)) {  // QWORD aligned | 
|  | AVT = MVT::i64; | 
|  | ValReg = X86::RAX; | 
|  | Val = (Val << 32) | Val; | 
|  | } | 
|  | break; | 
|  | default:  // Byte aligned | 
|  | AVT = MVT::i8; | 
|  | ValReg = X86::AL; | 
|  | Count = DAG.getIntPtrConstant(SizeVal, dl); | 
|  | break; | 
|  | } | 
|  |  | 
|  | if (AVT.bitsGT(MVT::i8)) { | 
|  | unsigned UBytes = AVT.getSizeInBits() / 8; | 
|  | Count = DAG.getIntPtrConstant(SizeVal / UBytes, dl); | 
|  | BytesLeft = SizeVal % UBytes; | 
|  | } | 
|  |  | 
|  | Chain = DAG.getCopyToReg(Chain, dl, ValReg, DAG.getConstant(Val, dl, AVT), | 
|  | InFlag); | 
|  | InFlag = Chain.getValue(1); | 
|  | } else { | 
|  | AVT = MVT::i8; | 
|  | Count  = DAG.getIntPtrConstant(SizeVal, dl); | 
|  | Chain  = DAG.getCopyToReg(Chain, dl, X86::AL, Src, InFlag); | 
|  | InFlag = Chain.getValue(1); | 
|  | } | 
|  |  | 
|  | Chain = DAG.getCopyToReg(Chain, dl, Subtarget.is64Bit() ? X86::RCX : X86::ECX, | 
|  | Count, InFlag); | 
|  | InFlag = Chain.getValue(1); | 
|  | Chain = DAG.getCopyToReg(Chain, dl, Subtarget.is64Bit() ? X86::RDI : X86::EDI, | 
|  | Dst, InFlag); | 
|  | InFlag = Chain.getValue(1); | 
|  |  | 
|  | SDVTList Tys = DAG.getVTList(MVT::Other, MVT::Glue); | 
|  | SDValue Ops[] = { Chain, DAG.getValueType(AVT), InFlag }; | 
|  | Chain = DAG.getNode(X86ISD::REP_STOS, dl, Tys, Ops); | 
|  |  | 
|  | if (TwoRepStos) { | 
|  | InFlag = Chain.getValue(1); | 
|  | Count  = Size; | 
|  | EVT CVT = Count.getValueType(); | 
|  | SDValue Left = DAG.getNode(ISD::AND, dl, CVT, Count, | 
|  | DAG.getConstant((AVT == MVT::i64) ? 7 : 3, dl, | 
|  | CVT)); | 
|  | Chain = DAG.getCopyToReg(Chain, dl, (CVT == MVT::i64) ? X86::RCX : X86::ECX, | 
|  | Left, InFlag); | 
|  | InFlag = Chain.getValue(1); | 
|  | Tys = DAG.getVTList(MVT::Other, MVT::Glue); | 
|  | SDValue Ops[] = { Chain, DAG.getValueType(MVT::i8), InFlag }; | 
|  | Chain = DAG.getNode(X86ISD::REP_STOS, dl, Tys, Ops); | 
|  | } else if (BytesLeft) { | 
|  | // Handle the last 1 - 7 bytes. | 
|  | unsigned Offset = SizeVal - BytesLeft; | 
|  | EVT AddrVT = Dst.getValueType(); | 
|  | EVT SizeVT = Size.getValueType(); | 
|  |  | 
|  | Chain = DAG.getMemset(Chain, dl, | 
|  | DAG.getNode(ISD::ADD, dl, AddrVT, Dst, | 
|  | DAG.getConstant(Offset, dl, AddrVT)), | 
|  | Src, | 
|  | DAG.getConstant(BytesLeft, dl, SizeVT), | 
|  | Align, isVolatile, false, | 
|  | DstPtrInfo.getWithOffset(Offset)); | 
|  | } | 
|  |  | 
|  | // TODO: Use a Tokenfactor, as in memcpy, instead of a single chain. | 
|  | return Chain; | 
|  | } | 
|  |  | 
|  | SDValue X86SelectionDAGInfo::EmitTargetCodeForMemcpy( | 
|  | SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Dst, SDValue Src, | 
|  | SDValue Size, unsigned Align, bool isVolatile, bool AlwaysInline, | 
|  | MachinePointerInfo DstPtrInfo, MachinePointerInfo SrcPtrInfo) const { | 
|  | // This requires the copy size to be a constant, preferably | 
|  | // within a subtarget-specific limit. | 
|  | ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size); | 
|  | const X86Subtarget &Subtarget = | 
|  | DAG.getMachineFunction().getSubtarget<X86Subtarget>(); | 
|  | if (!ConstantSize) | 
|  | return SDValue(); | 
|  | uint64_t SizeVal = ConstantSize->getZExtValue(); | 
|  | if (!AlwaysInline && SizeVal > Subtarget.getMaxInlineSizeThreshold()) | 
|  | return SDValue(); | 
|  |  | 
|  | /// If not DWORD aligned, it is more efficient to call the library.  However | 
|  | /// if calling the library is not allowed (AlwaysInline), then soldier on as | 
|  | /// the code generated here is better than the long load-store sequence we | 
|  | /// would otherwise get. | 
|  | if (!AlwaysInline && (Align & 3) != 0) | 
|  | return SDValue(); | 
|  |  | 
|  | // If to a segment-relative address space, use the default lowering. | 
|  | if (DstPtrInfo.getAddrSpace() >= 256 || | 
|  | SrcPtrInfo.getAddrSpace() >= 256) | 
|  | return SDValue(); | 
|  |  | 
|  | // If the base register might conflict with our physical registers, bail out. | 
|  | const MCPhysReg ClobberSet[] = {X86::RCX, X86::RSI, X86::RDI, | 
|  | X86::ECX, X86::ESI, X86::EDI}; | 
|  | if (isBaseRegConflictPossible(DAG, ClobberSet)) | 
|  | return SDValue(); | 
|  |  | 
|  | MVT AVT; | 
|  | if (Align & 1) | 
|  | AVT = MVT::i8; | 
|  | else if (Align & 2) | 
|  | AVT = MVT::i16; | 
|  | else if (Align & 4) | 
|  | // DWORD aligned | 
|  | AVT = MVT::i32; | 
|  | else | 
|  | // QWORD aligned | 
|  | AVT = Subtarget.is64Bit() ? MVT::i64 : MVT::i32; | 
|  |  | 
|  | unsigned UBytes = AVT.getSizeInBits() / 8; | 
|  | unsigned CountVal = SizeVal / UBytes; | 
|  | SDValue Count = DAG.getIntPtrConstant(CountVal, dl); | 
|  | unsigned BytesLeft = SizeVal % UBytes; | 
|  |  | 
|  | SDValue InFlag; | 
|  | Chain = DAG.getCopyToReg(Chain, dl, Subtarget.is64Bit() ? X86::RCX : X86::ECX, | 
|  | Count, InFlag); | 
|  | InFlag = Chain.getValue(1); | 
|  | Chain = DAG.getCopyToReg(Chain, dl, Subtarget.is64Bit() ? X86::RDI : X86::EDI, | 
|  | Dst, InFlag); | 
|  | InFlag = Chain.getValue(1); | 
|  | Chain = DAG.getCopyToReg(Chain, dl, Subtarget.is64Bit() ? X86::RSI : X86::ESI, | 
|  | Src, InFlag); | 
|  | InFlag = Chain.getValue(1); | 
|  |  | 
|  | SDVTList Tys = DAG.getVTList(MVT::Other, MVT::Glue); | 
|  | SDValue Ops[] = { Chain, DAG.getValueType(AVT), InFlag }; | 
|  | SDValue RepMovs = DAG.getNode(X86ISD::REP_MOVS, dl, Tys, Ops); | 
|  |  | 
|  | SmallVector<SDValue, 4> Results; | 
|  | Results.push_back(RepMovs); | 
|  | if (BytesLeft) { | 
|  | // Handle the last 1 - 7 bytes. | 
|  | unsigned Offset = SizeVal - BytesLeft; | 
|  | EVT DstVT = Dst.getValueType(); | 
|  | EVT SrcVT = Src.getValueType(); | 
|  | EVT SizeVT = Size.getValueType(); | 
|  | Results.push_back(DAG.getMemcpy(Chain, dl, | 
|  | DAG.getNode(ISD::ADD, dl, DstVT, Dst, | 
|  | DAG.getConstant(Offset, dl, | 
|  | DstVT)), | 
|  | DAG.getNode(ISD::ADD, dl, SrcVT, Src, | 
|  | DAG.getConstant(Offset, dl, | 
|  | SrcVT)), | 
|  | DAG.getConstant(BytesLeft, dl, SizeVT), | 
|  | Align, isVolatile, AlwaysInline, false, | 
|  | DstPtrInfo.getWithOffset(Offset), | 
|  | SrcPtrInfo.getWithOffset(Offset))); | 
|  | } | 
|  |  | 
|  | return DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Results); | 
|  | } |