| //===-- 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 "X86SelectionDAGInfo.h" |
| #include "X86ISelLowering.h" |
| #include "X86InstrInfo.h" |
| #include "X86RegisterInfo.h" |
| #include "X86Subtarget.h" |
| #include "llvm/CodeGen/SelectionDAG.h" |
| #include "llvm/CodeGen/TargetLowering.h" |
| #include "llvm/IR/DerivedTypes.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; |
| } |
| |
| namespace { |
| |
| // Represents a cover of a buffer of Size bytes with Count() blocks of type AVT |
| // (of size UBytes() bytes), as well as how many bytes remain (BytesLeft() is |
| // always smaller than the block size). |
| struct RepMovsRepeats { |
| RepMovsRepeats(uint64_t Size) : Size(Size) {} |
| |
| uint64_t Count() const { return Size / UBytes(); } |
| uint64_t BytesLeft() const { return Size % UBytes(); } |
| uint64_t UBytes() const { return AVT.getSizeInBits() / 8; } |
| |
| const uint64_t Size; |
| MVT AVT = MVT::i8; |
| }; |
| |
| } // namespace |
| |
| SDValue X86SelectionDAGInfo::EmitTargetCodeForMemset( |
| SelectionDAG &DAG, const SDLoc &dl, SDValue Chain, SDValue Dst, SDValue Val, |
| 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 *ValC = dyn_cast<ConstantSDNode>(Val); |
| |
| if (const char *bzeroName = (ValC && ValC->isNullValue()) |
| ? DAG.getTargetLoweringInfo().getLibcallName(RTLIB::BZERO) |
| : 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) |
| .setLibCallee(CallingConv::C, Type::getVoidTy(*DAG.getContext()), |
| DAG.getExternalSymbol(bzeroName, 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>(Val); |
| unsigned BytesLeft = 0; |
| 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, Val, 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 (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)), |
| Val, |
| 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(); |
| RepMovsRepeats Repeats(ConstantSize->getZExtValue()); |
| if (!AlwaysInline && Repeats.Size > 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(); |
| |
| // If the target has enhanced REPMOVSB, then it's at least as fast to use |
| // REP MOVSB instead of REP MOVS{W,D,Q}, and it avoids having to handle |
| // BytesLeft. |
| if (!Subtarget.hasERMSB() && !(Align & 1)) { |
| if (Align & 2) |
| // WORD aligned |
| Repeats.AVT = MVT::i16; |
| else if (Align & 4) |
| // DWORD aligned |
| Repeats.AVT = MVT::i32; |
| else |
| // QWORD aligned |
| Repeats.AVT = Subtarget.is64Bit() ? MVT::i64 : MVT::i32; |
| |
| if (Repeats.BytesLeft() > 0 && |
| DAG.getMachineFunction().getFunction().optForMinSize()) { |
| // When agressively optimizing for size, avoid generating the code to |
| // handle BytesLeft. |
| Repeats.AVT = MVT::i8; |
| } |
| } |
| |
| SDValue InFlag; |
| Chain = DAG.getCopyToReg(Chain, dl, Subtarget.is64Bit() ? X86::RCX : X86::ECX, |
| DAG.getIntPtrConstant(Repeats.Count(), dl), 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(Repeats.AVT), InFlag }; |
| SDValue RepMovs = DAG.getNode(X86ISD::REP_MOVS, dl, Tys, Ops); |
| |
| SmallVector<SDValue, 4> Results; |
| Results.push_back(RepMovs); |
| if (Repeats.BytesLeft()) { |
| // Handle the last 1 - 7 bytes. |
| unsigned Offset = Repeats.Size - Repeats.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(Repeats.BytesLeft(), dl, |
| SizeVT), |
| Align, isVolatile, AlwaysInline, false, |
| DstPtrInfo.getWithOffset(Offset), |
| SrcPtrInfo.getWithOffset(Offset))); |
| } |
| |
| return DAG.getNode(ISD::TokenFactor, dl, MVT::Other, Results); |
| } |