[AVR] Add a majority of the backend code

[dylanmckay]

Summary

This adds the majority of the AVR backend.

[dylanmckay]

Ping.

[dylanmckay]

Ping.

[dylanmckay]

Ping.

[arsenm]

lib/Target/AVR/AVRFrameLowering.h

9–12

Remove empty comment block

30

Pointless comment

lib/Target/AVR/AVRISelLowering.h

119–123

C++ style comments

lib/Target/AVR/AVRInstrInfo.cpp

38–43

These are not OK

lib/Target/AVR/AVRInstrInfo.h

23

Missing undef?

lib/Target/AVR/AVRSubtarget.h

68

this->?

[dylanmckay]

First round of code review

[dylanmckay]

lib/Target/AVR/AVRInstrInfo.cpp

40–45

That wasn't meant to make it in here, it's gone now.

lib/Target/AVR/AVRInstrInfo.h

25

Nice catch

[dylanmckay]

Back to you Matt

[dylanmckay]

Ping

[arsenm]

LGTM with some style nits, plus the pass setup seems to be adding a couple of passes I don't see being added

lib/Target/AVR/AVRFrameLowering.h

20–22

C++ style comments

lib/Target/AVR/AVRISelLowering.h

40

Why not all caps like the others?

83–84

I think it's best to not duplicate the comments on overrides. The base class header comment is more likely to be kept up to date

lib/Target/AVR/AVRInstrInfo.cpp

70

brace on case lines

391

Question mark?

463

static_cast

lib/Target/AVR/AVRInstrInfo.h

30–34

C++ comments

lib/Target/AVR/AVRRegisterInfo.cpp

58–70

Some comments about why these registers are reserved might be helpful

172

Fallthrough

lib/Target/AVR/AVRRegisterInfo.h

24–26

C++ comments. Repeat for everywhere else

lib/Target/AVR/AVRSubtarget.cpp

38

Do these actually initialize to 0? I don't think I've seen empty parens like this before

lib/Target/AVR/AVRSubtarget.h

39

Extra lne

49

return on new line like the others here

lib/Target/AVR/AVRTargetMachine.cpp

30

This is only one place, so you can just move the literal there

33

static, Get->get

36

No return after else

97

Don't see this

104

I don't see this file?

lib/Target/AVR/MCTargetDesc/AVRMCTargetDesc.h

24–26

Alphabetize

[dylanmckay]

lib/Target/AVR/AVRRegisterInfo.cpp

58–70

Agree

[dylanmckay]

Second round of Matt's code review

[dylanmckay]

Thanks for the review Matt :)

lib/Target/AVR/AVRFrameLowering.h

+//===-- AVRFrameLowering.h - Define frame lowering for AVR ------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_AVR_FRAME_LOWERING_H
+#define LLVM_AVR_FRAME_LOWERING_H
+
+#include "AVRConfig.h"
+
+#include "llvm/Target/TargetFrameLowering.h"
+
+namespace llvm {
+
+/**
+ * Utilities for creating function call frames.
+ */
+class AVRFrameLowering : public TargetFrameLowering {
+public:
+  explicit AVRFrameLowering();
+
+public: // TargetFrameLowering
+  void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
+  void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
+  bool hasFP(const MachineFunction &MF) const override;
+  bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
+                                 MachineBasicBlock::iterator MI,
+                                 const std::vector<CalleeSavedInfo> &CSI,
+                                 const TargetRegisterInfo *TRI) const override;
+  bool
+  restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
+                              MachineBasicBlock::iterator MI,
+                              const std::vector<CalleeSavedInfo> &CSI,
+                              const TargetRegisterInfo *TRI) const override;
+  bool hasReservedCallFrame(const MachineFunction &MF) const override;
+  bool canSimplifyCallFramePseudos(const MachineFunction &MF) const override;
+  void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
+                            RegScavenger *RS = nullptr) const override;
+  void
+  eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
+                                MachineBasicBlock::iterator MI) const override;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_AVR_FRAME_LOWERING_H

lib/Target/AVR/AVRISelLowering.h

+//===-- AVRISelLowering.h - AVR DAG Lowering Interface ----------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the interfaces that AVR uses to lower LLVM code into a
+// selection DAG.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_AVR_ISEL_LOWERING_H
+#define LLVM_AVR_ISEL_LOWERING_H
+
+#include "AVRConfig.h"
+
+#include "llvm/Target/TargetLowering.h"
+
+namespace llvm {
+
+namespace AVRISD {
+
+/// AVR Specific DAG Nodes
+enum NodeType {
+  /// Start the numbering where the builtin ops leave off.
+  FIRST_NUMBER = ISD::BUILTIN_OP_END,
+  /// Return from subroutine.
+  RET_FLAG,
+  /// Return from ISR.
+  RETI_FLAG,
+  /// Represents an abstract call instruction,
+  /// which includes a bunch of information.
+  CALL,
+  /// A wrapper node for TargetConstantPool,
+  /// TargetExternalSymbol, and TargetGlobalAddress.
+  Wrapper,
+  LSL,     ///< Logical shift left.
+  LSR,     ///< Logical shift right.
+  ASR,     ///< Arithmetic shift right.
+  ROR,     ///< Bit rotate right.
+  ROL,     ///< Bit rotate left.
+  LSLLOOP, ///< A loop of single logical shift left instructions.
+  LSRLOOP, ///< A loop of single logical shift right instructions.
+  ASRLOOP, ///< A loop of single arithmetic shift right instructions.
+  /// AVR conditional branches. Operand 0 is the chain operand, operand 1
+  /// is the block to branch if condition is true, operand 2 is the
+  /// condition code, and operand 3 is the flag operand produced by a CMP
+  /// or TEST instruction.
+  BRCOND,
+  /// Compare instruction.
+  CMP,
+  /// Compare with carry instruction.
+  CMPC,
+  /// Test for zero or minus instruction.
+  TST,
+  /// Operand 0 and operand 1 are selection variable, operand 2
+  /// is condition code and operand 3 is flag operand.
+  SELECT_CC
+};
+
+} // end of namespace AVRISD
+
+class AVRTargetMachine;
+
+/**
+ * Performs target lowering for the AVR.
+ */
+class AVRTargetLowering : public TargetLowering {
+public:
+  explicit AVRTargetLowering(AVRTargetMachine &TM);
+
+public:
+  MVT getScalarShiftAmountTy(const DataLayout &, EVT LHSTy) const override {
+    return MVT::i8;
+  }
+  const char *getTargetNodeName(unsigned Opcode) const override;
+
+  /*!
+   * Provide custom lowering hooks for some operations.
+   */
+  SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const override;
+
+  /*!
+   * Replace the results of node with an illegal result
+   * type with new values built out of custom code.
+   */
+  void ReplaceNodeResults(SDNode *N, SmallVectorImpl<SDValue> &Results,
+                          SelectionDAG &DAG) const override;
+
+  /*!
+   * Returns true if the addressing mode represented
+   * by AM is legal for this target, for a load/store
+   * of the specified type.
+   */
+  bool isLegalAddressingMode(const DataLayout &DL, const AddrMode &AM, Type *Ty,
+                             unsigned AS) const override;
+
+  /*!
+   * Returns true by value, base pointer and
+   * offset pointer and addressing mode by reference if the node's address
+   * can be legally represented as pre-indexed load / store address.
+   */
+  bool getPreIndexedAddressParts(SDNode *N, SDValue &Base, SDValue &Offset,
+                                 ISD::MemIndexedMode &AM,
+                                 SelectionDAG &DAG) const override;
+
+  /*!
+   * Returns true by value, base pointer and
+   * offset pointer and addressing mode by reference if this node can be
+   * combined with a load / store to form a post-indexed load / store.
+   */
+  bool getPostIndexedAddressParts(SDNode *N, SDNode *Op, SDValue &Base,
+                                  SDValue &Offset, ISD::MemIndexedMode &AM,
+                                  SelectionDAG &DAG) const override;
+
+  /*!
+   * Return true if folding a constant offset
+   * with the given GlobalAddress is legal.  It is frequently not legal in
+   * PIC relocation models.
+   */
+  bool isOffsetFoldingLegal(const GlobalAddressSDNode *GA) const override;
+
+  MachineBasicBlock *
+  EmitInstrWithCustomInserter(MachineInstr *MI,
+                              MachineBasicBlock *MBB) const override;
+
+  /// Inline Asm support.
+  /// Implementation of TargetLowering hooks.
+  ConstraintType getConstraintType(StringRef Constraint) const override;
+
+  ConstraintWeight
+  getSingleConstraintMatchWeight(AsmOperandInfo &info,
+                                 const char *constraint) const override;
+
+  std::pair<unsigned, const TargetRegisterClass *>
+  getRegForInlineAsmConstraint(const TargetRegisterInfo *TRI,
+                               StringRef Constraint, MVT VT) const override;
+
+  unsigned getInlineAsmMemConstraint(StringRef ConstraintCode) const override;
+
+  void LowerAsmOperandForConstraint(SDValue Op, std::string &Constraint,
+                                    std::vector<SDValue> &Ops,
+                                    SelectionDAG &DAG) const override;
+
+private:
+  SDValue getAVRCmp(SDValue LHS, SDValue RHS, ISD::CondCode CC, SDValue &AVRcc,
+                    SelectionDAG &DAG, SDLoc dl) const;
+  SDValue LowerShifts(SDValue Op, SelectionDAG &DAG) const;
+  SDValue LowerDivRem(SDValue Op, SelectionDAG &DAG) const;
+  SDValue LowerGlobalAddress(SDValue Op, SelectionDAG &DAG) const;
+  SDValue LowerBlockAddress(SDValue Op, SelectionDAG &DAG) const;
+  SDValue LowerBR_CC(SDValue Op, SelectionDAG &DAG) const;
+  SDValue LowerINLINEASM(SDValue Op, SelectionDAG &DAG) const;
+  SDValue LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const;
+  SDValue LowerSETCC(SDValue Op, SelectionDAG &DAG) const;
+  SDValue LowerVASTART(SDValue Op, SelectionDAG &DAG) const;
+
+  SDValue LowerReturn(SDValue Chain, CallingConv::ID CallConv, bool isVarArg,
+                      const SmallVectorImpl<ISD::OutputArg> &Outs,
+                      const SmallVectorImpl<SDValue> &OutVals, SDLoc dl,
+                      SelectionDAG &DAG) const override;
+  SDValue LowerFormalArguments(SDValue Chain, CallingConv::ID CallConv,
+                               bool isVarArg,
+                               const SmallVectorImpl<ISD::InputArg> &Ins,
+                               SDLoc dl, SelectionDAG &DAG,
+                               SmallVectorImpl<SDValue> &InVals) const override;
+  SDValue LowerCall(TargetLowering::CallLoweringInfo &CLI,
+                    SmallVectorImpl<SDValue> &InVals) const override;
+  SDValue LowerCallResult(SDValue Chain, SDValue InFlag,
+                          CallingConv::ID CallConv, bool isVarArg,
+                          const SmallVectorImpl<ISD::InputArg> &Ins, SDLoc dl,
+                          SelectionDAG &DAG,
+                          SmallVectorImpl<SDValue> &InVals) const;
+
+private: // custom inserters
+  MachineBasicBlock *insertShift(MachineInstr *MI, MachineBasicBlock *BB) const;
+  MachineBasicBlock *insertMul(MachineInstr *MI, MachineBasicBlock *BB) const;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_AVR_ISEL_LOWERING_H

lib/Target/AVR/AVRInstrInfo.h

+//===-- AVRInstrInfo.h - AVR Instruction Information ------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the AVR implementation of the TargetInstrInfo class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_AVR_INSTR_INFO_H
+#define LLVM_AVR_INSTR_INFO_H
+
+#include "llvm/Target/TargetInstrInfo.h"
+
+#include "AVRRegisterInfo.h"
+
+#define GET_INSTRINFO_HEADER
+#include "AVRGenInstrInfo.inc"
+
+namespace llvm {
+
+namespace AVRCC {
+
+/*!
+ * AVR specific condition codes.
+ * These correspond to `AVR_*_COND` in `AVRInstrInfo.td`.
+ * They must be kept in synch.
+ */
+enum CondCodes {
+  COND_EQ, //!< Equal
+  COND_NE, //!< Not equal
+  COND_GE, //!< Greater than or equal
+  COND_LT, //!< Less than
+  COND_SH, //!< Unsigned same or higher
+  COND_LO, //!< Unsigned lower
+  COND_MI, //!< Minus
+  COND_PL, //!< Plus
+  COND_INVALID
+};
+
+} // end of namespace AVRCC
+
+namespace AVRII {
+
+/// Specifies a target operand flag.
+enum TOF {
+  MO_NO_FLAG,
+
+  /// On a symbol operand, this represents the lo part.
+  MO_LO = (1 << 1),
+
+  /// On a symbol operand, this represents the hi part.
+  MO_HI = (1 << 2),
+
+  /// On a symbol operand, this represents it has to be negated.
+  MO_NEG = (1 << 3)
+};
+
+} // end of namespace AVRII
+
+/**
+ * Utilities related to the AVR instruction set.
+ */
+class AVRInstrInfo : public AVRGenInstrInfo {
+public:
+  explicit AVRInstrInfo();
+  /*!
+   * TargetInstrInfo is a superset of MRegister info.
+   * As such, whenever a client has an instance of instruction info, it should
+   * always be able to get register info as well (through this method).
+   */
+  const AVRRegisterInfo &getRegisterInfo() const { return RI; }
+  const MCInstrDesc &getBrCond(AVRCC::CondCodes CC) const;
+  AVRCC::CondCodes getCondFromBranchOpc(unsigned Opc) const;
+  AVRCC::CondCodes getOppositeCondition(AVRCC::CondCodes CC) const;
+  unsigned GetInstSizeInBytes(const MachineInstr *MI) const;
+
+  void copyPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
+                   DebugLoc DL, unsigned DestReg, unsigned SrcReg,
+                   bool KillSrc) const override;
+  void storeRegToStackSlot(MachineBasicBlock &MBB,
+                           MachineBasicBlock::iterator MI, unsigned SrcReg,
+                           bool isKill, int FrameIndex,
+                           const TargetRegisterClass *RC,
+                           const TargetRegisterInfo *TRI) const override;
+  void loadRegFromStackSlot(MachineBasicBlock &MBB,
+                            MachineBasicBlock::iterator MI, unsigned DestReg,
+                            int FrameIndex, const TargetRegisterClass *RC,
+                            const TargetRegisterInfo *TRI) const override;
+  unsigned isLoadFromStackSlot(const MachineInstr *MI,
+                               int &FrameIndex) const override;
+  unsigned isStoreToStackSlot(const MachineInstr *MI,
+                              int &FrameIndex) const override;
+
+  // Branch analysis.
+  bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
+                     MachineBasicBlock *&FBB,
+                     SmallVectorImpl<MachineOperand> &Cond,
+                     bool AllowModify = false) const override;
+  unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
+                        MachineBasicBlock *FBB, ArrayRef<MachineOperand> Cond,
+                        DebugLoc DL) const override;
+  unsigned RemoveBranch(MachineBasicBlock &MBB) const override;
+  bool
+  ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const override;
+
+private:
+  const AVRRegisterInfo RI;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_AVR_INSTR_INFO_H

lib/Target/AVR/AVRInstrInfo.cpp

+//===-- AVRInstrInfo.cpp - AVR Instruction Information --------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the AVR implementation of the TargetInstrInfo class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AVRInstrInfo.h"
+
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/CodeGen/MachineConstantPool.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineMemOperand.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Function.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/TargetRegistry.h"
+
+#include "AVR.h"
+#include "AVRMachineFunctionInfo.h"
+#include "AVRTargetMachine.h"
+#include "MCTargetDesc/AVRMCTargetDesc.h"
+
+#define GET_INSTRINFO_CTOR_DTOR
+#include "AVRGenInstrInfo.inc"
+
+namespace llvm {
+
+// External variable defined inside the register allocator to indicate if
+// we should reserve REG_Y if it is going to be used as the frame pointer.
+extern bool RA_ReserveREG_Y;
+// External variable defined inside the register allocator to indicate if
+// the register allocator is executing code inside the spiller.
+extern bool RA_InSpillerCode;
+
+AVRInstrInfo::AVRInstrInfo()
+    : AVRGenInstrInfo(AVR::ADJCALLSTACKDOWN, AVR::ADJCALLSTACKUP), RI() {}
+
+void AVRInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
+                               MachineBasicBlock::iterator MI, DebugLoc DL,
+                               unsigned DestReg, unsigned SrcReg,
+                               bool KillSrc) const {
+  unsigned Opc;
+
+  if (AVR::GPR8RegClass.contains(DestReg, SrcReg)) {
+    Opc = AVR::MOVRdRr;
+  } else if (AVR::DREGSRegClass.contains(DestReg, SrcReg)) {
+    Opc = AVR::MOVWRdRr;
+  } else if (SrcReg == AVR::SP && AVR::DREGSRegClass.contains(DestReg)) {
+    Opc = AVR::SPREAD;
+  } else if (DestReg == AVR::SP && AVR::DREGSRegClass.contains(SrcReg)) {
+    Opc = AVR::SPWRITE;
+  } else {
+    llvm_unreachable("Impossible reg-to-reg copy");
+  }
+
+  BuildMI(MBB, MI, DL, get(Opc), DestReg)
+      .addReg(SrcReg, getKillRegState(KillSrc));
+}
+
+unsigned AVRInstrInfo::isLoadFromStackSlot(const MachineInstr *MI,
+                                           int &FrameIndex) const {
+  switch (MI->getOpcode()) {
+  case AVR::LDDRdPtrQ:
+  case AVR::LDDWRdYQ: //:FIXME: remove this once PR13375 gets fixed
+    // case AVR::LDDWRdPtrQ:
+    {
+      if ((MI->getOperand(1).isFI()) && (MI->getOperand(2).isImm()) &&
+          (MI->getOperand(2).getImm() == 0)) {
+        FrameIndex = MI->getOperand(1).getIndex();
+        return MI->getOperand(0).getReg();
+      }
+      break;
+    }
+  default:
+    break;
+  }
+
+  return 0;
+}
+
+unsigned AVRInstrInfo::isStoreToStackSlot(const MachineInstr *MI,
+                                          int &FrameIndex) const {
+  switch (MI->getOpcode()) {
+  case AVR::STDPtrQRr:
+  case AVR::STDWPtrQRr: {
+    if ((MI->getOperand(0).isFI()) && (MI->getOperand(1).isImm()) &&
+        (MI->getOperand(1).getImm() == 0)) {
+      FrameIndex = MI->getOperand(0).getIndex();
+      return MI->getOperand(2).getReg();
+    }
+    break;
+  }
+  default:
+    break;
+  }
+
+  return 0;
+}
+
+void AVRInstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
+                                       MachineBasicBlock::iterator MI,
+                                       unsigned SrcReg, bool isKill,
+                                       int FrameIndex,
+                                       const TargetRegisterClass *RC,
+                                       const TargetRegisterInfo *TRI) const {
+  MachineFunction &MF = *MBB.getParent();
+  AVRMachineFunctionInfo *AFI = MF.getInfo<AVRMachineFunctionInfo>();
+
+  if (RA_InSpillerCode && !AFI->getHasSpills()) {
+    AFI->setHasSpills(true);
+    RA_ReserveREG_Y = true;
+  }
+
+  DebugLoc DL;
+  if (MI != MBB.end()) {
+    DL = MI->getDebugLoc();
+  }
+
+  const MachineFrameInfo &MFI = *MF.getFrameInfo();
+
+  MachineMemOperand *MMO = MF.getMachineMemOperand(
+      MachinePointerInfo::getFixedStack(MF, FrameIndex),
+      MachineMemOperand::MOStore, MFI.getObjectSize(FrameIndex),
+      MFI.getObjectAlignment(FrameIndex));
+
+  unsigned Opcode = 0;
+  if (RC->hasType(MVT::i8)) {
+    Opcode = AVR::STDPtrQRr;
+  } else if (RC->hasType(MVT::i16)) {
+    Opcode = AVR::STDWPtrQRr;
+  } else {
+    llvm_unreachable("Cannot store this register into a stack slot!");
+  }
+
+  BuildMI(MBB, MI, DL, get(Opcode))
+      .addFrameIndex(FrameIndex)
+      .addImm(0)
+      .addReg(SrcReg, getKillRegState(isKill))
+      .addMemOperand(MMO);
+}
+
+void AVRInstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
+                                        MachineBasicBlock::iterator MI,
+                                        unsigned DestReg, int FrameIndex,
+                                        const TargetRegisterClass *RC,
+                                        const TargetRegisterInfo *TRI) const {
+  DebugLoc DL;
+  if (MI != MBB.end()) {
+    DL = MI->getDebugLoc();
+  }
+
+  MachineFunction &MF = *MBB.getParent();
+  const MachineFrameInfo &MFI = *MF.getFrameInfo();
+
+  MachineMemOperand *MMO = MF.getMachineMemOperand(
+      MachinePointerInfo::getFixedStack(MF, FrameIndex),
+      MachineMemOperand::MOLoad, MFI.getObjectSize(FrameIndex),
+      MFI.getObjectAlignment(FrameIndex));
+
+  unsigned Opcode = 0;
+  if (RC->hasType(MVT::i8)) {
+    Opcode = AVR::LDDRdPtrQ;
+  } else if (RC->hasType(MVT::i16)) {
+    // Opcode = AVR::LDDWRdPtrQ;
+    //:FIXME: remove this once PR13375 gets fixed
+    Opcode = AVR::LDDWRdYQ;
+  } else {
+    llvm_unreachable("Cannot load this register from a stack slot!");
+  }
+
+  BuildMI(MBB, MI, DL, get(Opcode), DestReg)
+      .addFrameIndex(FrameIndex)
+      .addImm(0)
+      .addMemOperand(MMO);
+}
+
+const MCInstrDesc &AVRInstrInfo::getBrCond(AVRCC::CondCodes CC) const {
+  switch (CC) {
+  default:
+    llvm_unreachable("Unknown condition code!");
+  case AVRCC::COND_EQ:
+    return get(AVR::BREQk);
+  case AVRCC::COND_NE:
+    return get(AVR::BRNEk);
+  case AVRCC::COND_GE:
+    return get(AVR::BRGEk);
+  case AVRCC::COND_LT:
+    return get(AVR::BRLTk);
+  case AVRCC::COND_SH:
+    return get(AVR::BRSHk);
+  case AVRCC::COND_LO:
+    return get(AVR::BRLOk);
+  case AVRCC::COND_MI:
+    return get(AVR::BRMIk);
+  case AVRCC::COND_PL:
+    return get(AVR::BRPLk);
+  }
+}
+
+AVRCC::CondCodes AVRInstrInfo::getCondFromBranchOpc(unsigned Opc) const {
+  switch (Opc) {
+  default:
+    return AVRCC::COND_INVALID;
+  case AVR::BREQk:
+    return AVRCC::COND_EQ;
+  case AVR::BRNEk:
+    return AVRCC::COND_NE;
+  case AVR::BRSHk:
+    return AVRCC::COND_SH;
+  case AVR::BRLOk:
+    return AVRCC::COND_LO;
+  case AVR::BRMIk:
+    return AVRCC::COND_MI;
+  case AVR::BRPLk:
+    return AVRCC::COND_PL;
+  case AVR::BRGEk:
+    return AVRCC::COND_GE;
+  case AVR::BRLTk:
+    return AVRCC::COND_LT;
+  }
+}
+
+AVRCC::CondCodes AVRInstrInfo::getOppositeCondition(AVRCC::CondCodes CC) const {
+  switch (CC) {
+  default:
+    llvm_unreachable("Invalid condition!");
+  case AVRCC::COND_EQ:
+    return AVRCC::COND_NE;
+  case AVRCC::COND_NE:
+    return AVRCC::COND_EQ;
+  case AVRCC::COND_SH:
+    return AVRCC::COND_LO;
+  case AVRCC::COND_LO:
+    return AVRCC::COND_SH;
+  case AVRCC::COND_GE:
+    return AVRCC::COND_LT;
+  case AVRCC::COND_LT:
+    return AVRCC::COND_GE;
+  case AVRCC::COND_MI:
+    return AVRCC::COND_PL;
+  case AVRCC::COND_PL:
+    return AVRCC::COND_MI;
+  }
+}
+
+bool AVRInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
+                                 MachineBasicBlock *&TBB,
+                                 MachineBasicBlock *&FBB,
+                                 SmallVectorImpl<MachineOperand> &Cond,
+                                 bool AllowModify) const {
+  // Start from the bottom of the block and work up, examining the
+  // terminator instructions.
+  MachineBasicBlock::iterator I = MBB.end();
+  MachineBasicBlock::iterator UnCondBrIter = MBB.end();
+
+  while (I != MBB.begin()) {
+    --I;
+    if (I->isDebugValue()) {
+      continue;
+    }
+
+    // Working from the bottom, when we see a non-terminator
+    // instruction, we're done.
+    if (!isUnpredicatedTerminator(*I)) {
+      break;
+    }
+
+    // A terminator that isn't a branch can't easily be handled
+    // by this analysis.
+    if (!I->getDesc().isBranch()) {
+      return true;
+    }
+
+    // Handle unconditional branches.
+    //:TODO: add here jmp
+    if (I->getOpcode() == AVR::RJMPk) {
+      UnCondBrIter = I;
+
+      if (!AllowModify) {
+        TBB = I->getOperand(0).getMBB();
+        continue;
+      }
+
+      // If the block has any instructions after a JMP, delete them.
+      while (std::next(I) != MBB.end()) {
+        std::next(I)->eraseFromParent();
+      }
+
+      Cond.clear();
+      FBB = 0;
+
+      // Delete the JMP if it's equivalent to a fall-through.
+      if (MBB.isLayoutSuccessor(I->getOperand(0).getMBB())) {
+        TBB = 0;
+        I->eraseFromParent();
+        I = MBB.end();
+        UnCondBrIter = MBB.end();
+        continue;
+      }
+
+      // TBB is used to indicate the unconditinal destination.
+      TBB = I->getOperand(0).getMBB();
+      continue;
+    }
+
+    // Handle conditional branches.
+    AVRCC::CondCodes BranchCode = getCondFromBranchOpc(I->getOpcode());
+    if (BranchCode == AVRCC::COND_INVALID) {
+      return true; // Can't handle indirect branch.
+    }
+
+    // Working from the bottom, handle the first conditional branch.
+    if (Cond.empty()) {
+      MachineBasicBlock *TargetBB = I->getOperand(0).getMBB();
+      if (AllowModify && UnCondBrIter != MBB.end() &&
+          MBB.isLayoutSuccessor(TargetBB)) {
+        // If we can modify the code and it ends in something like:
+        //
+        //     jCC L1
+        //     jmp L2
+        //   L1:
+        //     ...
+        //   L2:
+        //
+        // Then we can change this to:
+        //
+        //     jnCC L2
+        //   L1:
+        //     ...
+        //   L2:
+        //
+        // Which is a bit more efficient.
+        // We conditionally jump to the fall-through block.
+        BranchCode = getOppositeCondition(BranchCode);
+        unsigned JNCC = getBrCond(BranchCode).getOpcode();
+        MachineBasicBlock::iterator OldInst = I;
+
+        BuildMI(MBB, UnCondBrIter, MBB.findDebugLoc(I), get(JNCC))
+            .addMBB(UnCondBrIter->getOperand(0).getMBB());
+        BuildMI(MBB, UnCondBrIter, MBB.findDebugLoc(I), get(AVR::RJMPk))
+            .addMBB(TargetBB);
+
+        OldInst->eraseFromParent();
+        UnCondBrIter->eraseFromParent();
+
+        // Restart the analysis.
+        UnCondBrIter = MBB.end();
+        I = MBB.end();
+        continue;
+      }
+
+      FBB = TBB;
+      TBB = I->getOperand(0).getMBB();
+      Cond.push_back(MachineOperand::CreateImm(BranchCode));
+      continue;
+    }
+
+    // Handle subsequent conditional branches. Only handle the case where all
+    // conditional branches branch to the same destination.
+    assert(Cond.size() == 1);
+    assert(TBB);
+
+    // Only handle the case where all conditional branches branch to
+    // the same destination.
+    if (TBB != I->getOperand(0).getMBB()) {
+      return true;
+    }
+
+    AVRCC::CondCodes OldBranchCode = (AVRCC::CondCodes)Cond[0].getImm();
+    // If the conditions are the same, we can leave them alone.
+    if (OldBranchCode == BranchCode) {
+      continue;
+    }
+
+    return true;
+  }
+
+  return false;
+}
+
+unsigned AVRInstrInfo::InsertBranch(MachineBasicBlock &MBB,
+                                    MachineBasicBlock *TBB,
+                                    MachineBasicBlock *FBB,
+                                    ArrayRef<MachineOperand> Cond,
+                                    DebugLoc DL) const {
+  // Shouldn't be a fall through.
+  assert(TBB && "InsertBranch must not be told to insert a fallthrough");
+  assert((Cond.size() == 1 || Cond.size() == 0) &&
+         "AVR branch conditions have one component!");
+
+  if (Cond.empty()) {
+    // Unconditional branch?
+    assert(!FBB && "Unconditional branch with multiple successors!");
+    BuildMI(&MBB, DL, get(AVR::RJMPk)).addMBB(TBB);
+    return 1;
+  }
+
+  // Conditional branch.
+  unsigned Count = 0;
+  AVRCC::CondCodes CC = (AVRCC::CondCodes)Cond[0].getImm();
+  BuildMI(&MBB, DL, getBrCond(CC)).addMBB(TBB);
+  ++Count;
+
+  if (FBB) {
+    // Two-way Conditional branch. Insert the second branch.
+    BuildMI(&MBB, DL, get(AVR::RJMPk)).addMBB(FBB);
+    ++Count;
+  }
+
+  return Count;
+}
+
+unsigned AVRInstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
+  MachineBasicBlock::iterator I = MBB.end();
+  unsigned Count = 0;
+
+  while (I != MBB.begin()) {
+    --I;
+    if (I->isDebugValue()) {
+      continue;
+    }
+    //:TODO: add here the missing jmp instructions once they are implemented
+    // like jmp, {e}ijmp, and other cond branches, ...
+    if (I->getOpcode() != AVR::RJMPk &&
+        getCondFromBranchOpc(I->getOpcode()) == AVRCC::COND_INVALID) {
+      break;
+    }
+
+    // Remove the branch.
+    I->eraseFromParent();
+    I = MBB.end();
+    ++Count;
+  }
+
+  return Count;
+}
+
+bool AVRInstrInfo::ReverseBranchCondition(
+    SmallVectorImpl<MachineOperand> &Cond) const {
+  assert(Cond.size() == 1 && "Invalid AVR branch condition!");
+
+  AVRCC::CondCodes CC = static_cast<AVRCC::CondCodes>(Cond[0].getImm());
+  Cond[0].setImm(getOppositeCondition(CC));
+
+  return false;
+}
+
+unsigned AVRInstrInfo::GetInstSizeInBytes(const MachineInstr *MI) const {
+  unsigned Opcode = MI->getOpcode();
+
+  switch (Opcode) {
+  // A regular instruction
+  default: {
+    const MCInstrDesc &Desc = get(Opcode);
+    return Desc.getSize();
+  }
+  case TargetOpcode::EH_LABEL:
+  case TargetOpcode::IMPLICIT_DEF:
+  case TargetOpcode::KILL:
+  case TargetOpcode::DBG_VALUE:
+    return 0;
+  case TargetOpcode::INLINEASM: {
+    const MachineFunction *MF = MI->getParent()->getParent();
+    const AVRTargetMachine &TM = (const AVRTargetMachine &)MF->getTarget();
+    const TargetInstrInfo &TII = *TM.getSubtargetImpl()->getInstrInfo();
+    return TII.getInlineAsmLength(MI->getOperand(0).getSymbolName(),
+                                  *TM.getMCAsmInfo());
+  }
+  }
+}
+
+} // end of namespace llvm

lib/Target/AVR/AVRRegisterInfo.h

+//===-- AVRRegisterInfo.h - AVR Register Information Impl -------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the AVR implementation of the TargetRegisterInfo class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_AVR_REGISTER_INFO_H
+#define LLVM_AVR_REGISTER_INFO_H
+
+#include "llvm/Target/TargetRegisterInfo.h"
+
+#define GET_REGINFO_HEADER
+#include "AVRGenRegisterInfo.inc"
+
+namespace llvm {
+/**
+ * Utilities relating to AVR registers.
+ */
+class AVRRegisterInfo : public AVRGenRegisterInfo {
+public:
+  AVRRegisterInfo();
+
+public:
+  const uint16_t *
+  getCalleeSavedRegs(const MachineFunction *MF = 0) const override;
+  const uint32_t *getCallPreservedMask(const MachineFunction &MF,
+                                       CallingConv::ID CC) const override;
+  BitVector getReservedRegs(const MachineFunction &MF) const override;
+
+  const TargetRegisterClass *
+  getLargestLegalSuperClass(const TargetRegisterClass *RC,
+                            const MachineFunction &MF) const override;
+
+  /// Stack Frame Processing Methods
+  void eliminateFrameIndex(MachineBasicBlock::iterator MI, int SPAdj,
+                           unsigned FIOperandNum,
+                           RegScavenger *RS = NULL) const override;
+
+  /// Debug information queries.
+  unsigned getFrameRegister(const MachineFunction &MF) const override;
+
+  /// Returns a TargetRegisterClass used for pointer values.
+  const TargetRegisterClass *
+  getPointerRegClass(const MachineFunction &MF,
+                     unsigned Kind = 0) const override;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_AVR_REGISTER_INFO_H

lib/Target/AVR/AVRRegisterInfo.cpp

+//===-- AVRRegisterInfo.cpp - AVR Register Information --------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the AVR implementation of the TargetRegisterInfo class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AVRRegisterInfo.h"
+
+#include "llvm/ADT/BitVector.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/IR/Function.h"
+#include "llvm/Target/TargetFrameLowering.h"
+
+#include "AVR.h"
+#include "AVRInstrInfo.h"
+#include "AVRTargetMachine.h"
+#include "MCTargetDesc/AVRMCTargetDesc.h"
+
+#define GET_REGINFO_TARGET_DESC
+#include "AVRGenRegisterInfo.inc"
+
+namespace llvm {
+
+AVRRegisterInfo::AVRRegisterInfo() : AVRGenRegisterInfo(0) {}
+
+const uint16_t *
+AVRRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
+  CallingConv::ID CC = MF->getFunction()->getCallingConv();
+
+  return ((CC == CallingConv::AVR_INTR || CC == CallingConv::AVR_SIGNAL)
+              ? CSR_Interrupts_SaveList
+              : CSR_Normal_SaveList);
+}
+
+const uint32_t *
+AVRRegisterInfo::getCallPreservedMask(const MachineFunction &MF,
+                                      CallingConv::ID CC) const {
+  return ((CC == CallingConv::AVR_INTR || CC == CallingConv::AVR_SIGNAL)
+              ? CSR_Interrupts_RegMask
+              : CSR_Normal_RegMask);
+}
+
+BitVector AVRRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
+  BitVector Reserved(getNumRegs());
+  const AVRTargetMachine &TM = (const AVRTargetMachine &)MF.getTarget();
+  const TargetFrameLowering *TFI = TM.getSubtargetImpl()->getFrameLowering();
+
+  Reserved.set(AVR::R0);
+  Reserved.set(AVR::R1);
+  Reserved.set(AVR::R1R0);
+
+  Reserved.set(AVR::SPL);
+  Reserved.set(AVR::SPH);
+  Reserved.set(AVR::SP);
+
+  if (TFI->hasFP(MF)) {
+    Reserved.set(AVR::R28);
+    Reserved.set(AVR::R29);
+    Reserved.set(AVR::R29R28);
+  }
+
+  return Reserved;
+}
+
+const TargetRegisterClass *
+AVRRegisterInfo::getLargestLegalSuperClass(const TargetRegisterClass *RC,
+                                           const MachineFunction &MF) const {
+  if (RC->hasType(MVT::i16)) {
+    return &AVR::DREGSRegClass;
+  }
+
+  if (RC->hasType(MVT::i8)) {
+    return &AVR::GPR8RegClass;
+  }
+
+  llvm_unreachable("Invalid register size");
+}
+
+/// Fold a frame offset shared between two add instructions into a single one.
+static void foldFrameOffset(MachineInstr &MI, int &Offset, unsigned DstReg) {
+  int Opcode = MI.getOpcode();
+
+  // Don't bother trying if the next instruction is not an add or a sub.
+  if ((Opcode != AVR::SUBIWRdK) && (Opcode != AVR::ADIWRdK)) {
+    return;
+  }
+
+  // Check that DstReg matches with next instruction, otherwise the instruction
+  // is not related to stack address manipulation.
+  if (DstReg != MI.getOperand(0).getReg()) {
+    return;
+  }
+
+  // Add the offset in the next instruction to our offset.
+  switch (Opcode) {
+  case AVR::SUBIWRdK:
+    Offset += -MI.getOperand(2).getImm();
+    break;
+  case AVR::ADIWRdK:
+    Offset += MI.getOperand(2).getImm();
+    break;
+  }
+
+  // Finally remove the instruction.
+  MI.eraseFromParent();
+}
+
+void AVRRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
+                                          int SPAdj, unsigned FIOperandNum,
+                                          RegScavenger *RS) const {
+  assert(SPAdj == 0 && "Unexpected SPAdj value");
+
+  MachineInstr &MI = *II;
+  DebugLoc dl = MI.getDebugLoc();
+  MachineBasicBlock &MBB = *MI.getParent();
+  const MachineFunction &MF = *MBB.getParent();
+  const AVRTargetMachine &TM = (const AVRTargetMachine &)MF.getTarget();
+  const TargetInstrInfo &TII = *TM.getSubtargetImpl()->getInstrInfo();
+  const MachineFrameInfo *MFI = MF.getFrameInfo();
+  const TargetFrameLowering *TFI = TM.getSubtargetImpl()->getFrameLowering();
+  int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
+  int Offset = MFI->getObjectOffset(FrameIndex);
+
+  // Add one to the offset because SP points to an empty slot.
+  Offset += MFI->getStackSize() - TFI->getOffsetOfLocalArea() + 1;
+  // Fold incoming offset.
+  Offset += MI.getOperand(FIOperandNum + 1).getImm();
+
+  // This is actually "load effective address" of the stack slot
+  // instruction. We have only two-address instructions, thus we need to
+  // expand it into move + add.
+  if (MI.getOpcode() == AVR::FRMIDX) {
+    MI.setDesc(TII.get(AVR::MOVWRdRr));
+    MI.getOperand(FIOperandNum).ChangeToRegister(AVR::R29R28, false);
+
+    assert(Offset > 0 && "Invalid offset");
+
+    // We need to materialize the offset via an add instruction.
+    unsigned Opcode;
+    unsigned DstReg = MI.getOperand(0).getReg();
+    assert(DstReg != AVR::R29R28 && "Dest reg cannot be the frame pointer");
+
+    // Generally, to load a frame address two add instructions are emitted that
+    // could get folded into a single one:
+    //  movw    r31:r30, r29:r28
+    //  adiw    r31:r30, 29
+    //  adiw    r31:r30, 16
+    // to:
+    //  movw    r31:r30, r29:r28
+    //  adiw    r31:r30, 45
+    foldFrameOffset(*std::next(II), Offset, DstReg);
+
+    // Select the best opcode based on DstReg and the offset size.
+    switch (DstReg) {
+    case AVR::R25R24:
+    case AVR::R27R26:
+    case AVR::R31R30: {
+      if (isUInt<6>(Offset)) {
+        Opcode = AVR::ADIWRdK;
+        break;
+      }
+      // Fallthru
+    }
+    default: {
+      // This opcode will get expanded into a pair of subi/sbci.
+      Opcode = AVR::SUBIWRdK;
+      Offset = -Offset;
+      break;
+    }
+    }
+
+    MachineInstr *New = BuildMI(MBB, std::next(II), dl, TII.get(Opcode), DstReg)
+                            .addReg(DstReg, RegState::Kill)
+                            .addImm(Offset);
+    New->getOperand(3).setIsDead();
+
+    return;
+  }
+
+  // If the offset is too big we have to adjust and restore the frame pointer
+  // to materialize a valid load/store with displacement.
+  //:TODO: consider using only one adiw/sbiw chain for more than one frame index
+  if (Offset >= 63) {
+    unsigned AddOpc = AVR::ADIWRdK, SubOpc = AVR::SBIWRdK;
+    int AddOffset = Offset - 63 + 1;
+
+    // For huge offsets where adiw/sbiw cannot be used use a pair of subi/sbci.
+    if ((Offset - 63 + 1) > 63) {
+      AddOpc = AVR::SUBIWRdK;
+      SubOpc = AVR::SUBIWRdK;
+      AddOffset = -AddOffset;
+    }
+
+    // It is possible that the spiller places this frame instruction in between
+    // a compare and branch, invalidating the contents of SREG set by the
+    // compare instruction because of the add/sub pairs. Conservatively save and
+    // restore SREG before and after each add/sub pair.
+    BuildMI(MBB, II, dl, TII.get(AVR::INRdA), AVR::R0).addImm(0x3f);
+
+    MachineInstr *New = BuildMI(MBB, II, dl, TII.get(AddOpc), AVR::R29R28)
+                            .addReg(AVR::R29R28, RegState::Kill)
+                            .addImm(AddOffset);
+    New->getOperand(3).setIsDead();
+
+    // Restore SREG.
+    BuildMI(MBB, std::next(II), dl, TII.get(AVR::OUTARr))
+        .addImm(0x3f)
+        .addReg(AVR::R0, RegState::Kill);
+
+    // No need to set SREG as dead here otherwise if the next instruction is a
+    // cond branch it will be using a dead register.
+    New = BuildMI(MBB, std::next(II), dl, TII.get(SubOpc), AVR::R29R28)
+              .addReg(AVR::R29R28, RegState::Kill)
+              .addImm(Offset - 63 + 1);
+
+    Offset = 62;
+  }
+
+  MI.getOperand(FIOperandNum).ChangeToRegister(AVR::R29R28, false);
+  assert(isUInt<6>(Offset) && "Offset is out of range");
+  MI.getOperand(FIOperandNum + 1).ChangeToImmediate(Offset);
+}
+
+unsigned AVRRegisterInfo::getFrameRegister(const MachineFunction &MF) const {
+  const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
+  if (TFI->hasFP(MF)) {
+    // The Y pointer register
+    return AVR::R28;
+  }
+
+  return AVR::SP;
+}
+
+const TargetRegisterClass *
+AVRRegisterInfo::getPointerRegClass(const MachineFunction &MF,
+                                    unsigned Kind) const {
+  // FIXME: Currently we're using avr-gcc as reference, so we restrict
+  // ptrs to Y and Z regs. Though avr-gcc has buggy implementation
+  // of memory constraint, so we can fix it and bit avr-gcc here ;-)
+  return &AVR::PTRDISPREGSRegClass;
+}
+
+} // end of namespace llvm

lib/Target/AVR/AVRSubtarget.h

+//===-- AVRSubtarget.h - Define Subtarget for the AVR -----------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the AVR specific subclass of TargetSubtargetInfo.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_AVR_SUBTARGET_H
+#define LLVM_AVR_SUBTARGET_H
+
+#include "AVRConfig.h"
+
+#include "llvm/Target/TargetSubtargetInfo.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/Target/TargetMachine.h"
+
+#include "AVRFrameLowering.h"
+#include "AVRISelLowering.h"
+#include "AVRInstrInfo.h"
+#include "AVRSelectionDAGInfo.h"
+
+#define GET_SUBTARGETINFO_HEADER
+#include "AVRGenSubtargetInfo.inc"
+
+namespace llvm {
+
+/**
+ * A specific AVR target MCU.
+ */
+class AVRSubtarget : public AVRGenSubtargetInfo {
+
+public:
+  //! Creates an AVR subtarget.
+  //! \param TT  The target triple.
+  //! \param CPU The CPU to target.
+  //! \param FS  The feature string.
+  //! \param TM  The target machine.
+  AVRSubtarget(const Triple &TT, const std::string &CPU, const std::string &FS,
+               AVRTargetMachine &TM);
+
+  const AVRInstrInfo *getInstrInfo() const override { return &InstrInfo; }
+  const TargetFrameLowering *getFrameLowering() const override {
+    return &FrameLowering;
+  }
+  const AVRTargetLowering *getTargetLowering() const override {
+    return &TLInfo;
+  }
+  const AVRSelectionDAGInfo *getSelectionDAGInfo() const override {
+    return &TSInfo;
+  }
+  const AVRRegisterInfo *getRegisterInfo() const override {
+    return &InstrInfo.getRegisterInfo();
+  }
+
+  /// Parses a subtarget feature string, setting appropriate options.
+  /// \note Definition of function is auto generated by `tblgen`.
+  void ParseSubtargetFeatures(StringRef CPU, StringRef FS);
+
+  // Subtarget feature getters.
+  // See AVR.td for details.
+  bool hasSRAM() const { return this->m_hasSRAM; }
+  bool hasJMPCALL() const { return this->m_hasJMPCALL; }
+  bool hasIJMPCALL() const { return this->m_hasIJMPCALL; }
+  bool hasEIJMPCALL() const { return this->m_hasEIJMPCALL; }
+  bool hasADDSUBIW() const { return this->m_hasADDSUBIW; }
+  bool hasSmallStack() const { return m_hasSmallStack; }
+  bool hasMOVW() const { return this->m_hasMOVW; }
+  bool hasLPM() const { return this->m_hasLPM; }
+  bool hasLPMX() const { return this->m_hasLPMX; }
+  bool hasELPM() const { return this->m_hasELPM; }
+  bool hasELPMX() const { return this->m_hasELPMX; }
+  bool hasSPM() const { return this->m_hasSPM; }
+  bool hasSPMX() const { return this->m_hasSPMX; }
+  bool hasDES() const { return this->m_hasDES; }
+  bool supportsRMW() const { return this->m_supportsRMW; }
+  bool supportsMultiplication() const { return this->m_supportsMultiplication; }
+  bool hasBREAK() const { return this->m_hasBREAK; }
+  bool hasTinyEncoding() const { return this->m_hasTinyEncoding; }
+
+  /// Gets the ELF architecture for the e_flags field
+  /// of an ELF object file.
+  unsigned getELFArch() const {
+    assert(ELFArch != 0 &&
+           "every device must have an associate ELF architecture");
+    return this->ELFArch;
+  }
+
+private:
+  AVRInstrInfo InstrInfo;
+  AVRFrameLowering FrameLowering;
+  AVRTargetLowering TLInfo;
+  AVRSelectionDAGInfo TSInfo;
+
+  // Subtarget feature settings
+  // See AVR.td for details.
+  bool m_hasSRAM;
+  bool m_hasJMPCALL;
+  bool m_hasIJMPCALL;
+  bool m_hasEIJMPCALL;
+  bool m_hasADDSUBIW;
+  bool m_hasSmallStack;
+  bool m_hasMOVW;
+  bool m_hasLPM;
+  bool m_hasLPMX;
+  bool m_hasELPM;
+  bool m_hasELPMX;
+  bool m_hasSPM;
+  bool m_hasSPMX;
+  bool m_hasDES;
+  bool m_supportsRMW;
+  bool m_supportsMultiplication;
+  bool m_hasBREAK;
+  bool m_hasTinyEncoding;
+
+  /// The ELF e_flags architecture.
+  unsigned ELFArch;
+
+  // Dummy member, used by FeatureSet's. We cannot have a SubtargetFeature with
+  // no variable, so we instead bind pseudo features to this variable.
+  bool m_FeatureSetDummy;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_AVR_SUBTARGET_H

lib/Target/AVR/AVRSubtarget.cpp

+//===-- AVRSubtarget.cpp - AVR Subtarget Information ----------------------===//
+//
+//                     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 AVR specific subclass of TargetSubtargetInfo.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AVRSubtarget.h"
+
+#include "llvm/Support/ELF.h"
+#include "llvm/Support/TargetRegistry.h"
+
+#include "AVR.h"
+#include "AVRTargetMachine.h"
+#include "MCTargetDesc/AVRMCTargetDesc.h"
+
+#define DEBUG_TYPE "avr-subtarget"
+
+#define GET_SUBTARGETINFO_TARGET_DESC
+#define GET_SUBTARGETINFO_CTOR
+#include "AVRGenSubtargetInfo.inc"
+
+namespace llvm {
+
+AVRSubtarget::AVRSubtarget(const Triple &TT, const std::string &CPU,
+                           const std::string &FS, AVRTargetMachine &TM)
+    : AVRGenSubtargetInfo(TT, CPU, FS), InstrInfo(), FrameLowering(),
+      TLInfo(TM), TSInfo(),
+
+      // Subtarget features
+      m_hasSRAM(), m_hasJMPCALL(), m_hasIJMPCALL(), m_hasEIJMPCALL(),
+      m_hasADDSUBIW(), m_hasSmallStack(), m_hasMOVW(), m_hasLPM(), m_hasLPMX(),
+      m_hasELPM(), m_hasELPMX(), m_hasSPM(), m_hasSPMX(), m_hasDES(),
+      m_supportsRMW(), m_supportsMultiplication(), m_hasBREAK(),
+      m_hasTinyEncoding(), ELFArch(), m_FeatureSetDummy() {
+  // Parse features string.
+  ParseSubtargetFeatures(CPU, FS);
+}
+
+} // end of namespace llvm

lib/Target/AVR/AVRTargetMachine.h

+//===-- AVRTargetMachine.h - Define TargetMachine for AVR -------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the AVR specific subclass of TargetMachine.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_AVR_TARGET_MACHINE_H
+#define LLVM_AVR_TARGET_MACHINE_H
+
+#include "AVRConfig.h"
+
+#include "llvm/IR/DataLayout.h"
+#include "llvm/Target/TargetMachine.h"
+
+#include "AVRFrameLowering.h"
+#include "AVRISelLowering.h"
+#include "AVRInstrInfo.h"
+#include "AVRSelectionDAGInfo.h"
+#include "AVRSubtarget.h"
+
+namespace llvm {
+
+/**
+ * A generic AVR implementation.
+ */
+class AVRTargetMachine : public LLVMTargetMachine {
+public:
+  AVRTargetMachine(const Target &T, const Triple &TT, StringRef CPU,
+                   StringRef FS, const TargetOptions &Options, Reloc::Model RM,
+                   CodeModel::Model CM, CodeGenOpt::Level OL);
+
+  const AVRSubtarget *getSubtargetImpl() const;
+  const AVRSubtarget *getSubtargetImpl(const Function &) const override;
+
+  TargetLoweringObjectFile *getObjFileLowering() const override {
+    return this->TLOF.get();
+  }
+
+  // Pass Pipeline Configuration.
+  TargetPassConfig *createPassConfig(PassManagerBase &PM) override;
+
+private:
+  std::unique_ptr<TargetLoweringObjectFile> TLOF;
+  AVRSubtarget SubTarget;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_AVR_TARGET_MACHINE_H

lib/Target/AVR/AVRTargetMachine.cpp

+//===-- AVRTargetMachine.cpp - Define TargetMachine for AVR ---------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the AVR specific subclass of TargetMachine.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AVRTargetMachine.h"
+
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/LegacyPassManager.h"
+#include "llvm/Support/TargetRegistry.h"
+
+#include "AVRTargetObjectFile.h"
+#include "AVR.h"
+#include "MCTargetDesc/AVRMCTargetDesc.h"
+
+namespace llvm {
+
+// The default CPU to choose if an empty string is passed.
+namespace {
+const char *DefaultCPU = "avr2";
+
+/// Processes a CPU name.
+StringRef GetTargetCPU(StringRef CPU) {
+  if (CPU.empty() || CPU == "generic") {
+    return DefaultCPU;
+  } else {
+    return CPU;
+  }
+}
+}
+
+AVRTargetMachine::AVRTargetMachine(const Target &T, const Triple &TT,
+                                   StringRef CPU, StringRef FS,
+                                   const TargetOptions &Options,
+                                   Reloc::Model RM, CodeModel::Model CM,
+                                   CodeGenOpt::Level OL)
+    : LLVMTargetMachine(
+          T, "e-p:16:8:8-i8:8:8-i16:8:8-i32:8:8-i64:8:8-f32:8:8-f64:8:8-n8", TT,
+          GetTargetCPU(CPU), FS, Options, RM, CM, OL),
+      SubTarget(TT, GetTargetCPU(CPU), FS, *this) {
+  this->TLOF = make_unique<AVRTargetObjectFile>();
+  initAsmInfo();
+}
+
+namespace {
+/// AVR Code Generator Pass Configuration Options.
+class AVRPassConfig : public TargetPassConfig {
+public:
+  AVRPassConfig(AVRTargetMachine *TM, PassManagerBase &PM)
+      : TargetPassConfig(TM, PM) {}
+
+  AVRTargetMachine &getAVRTargetMachine() const {
+    return getTM<AVRTargetMachine>();
+  }
+
+  bool addInstSelector() override;
+  void addPreSched2() override;
+  void addPreRegAlloc() override;
+  void addPreEmitPass() override;
+};
+} // namespace
+
+TargetPassConfig *AVRTargetMachine::createPassConfig(PassManagerBase &PM) {
+  return new AVRPassConfig(this, PM);
+}
 
 extern "C" void LLVMInitializeAVRTarget() {
+  // Register the target.
+  RegisterTargetMachine<AVRTargetMachine> X(TheAVRTarget);
+}
+
+const AVRSubtarget *AVRTargetMachine::getSubtargetImpl() const {
+  return &SubTarget;
+}
 
+const AVRSubtarget *AVRTargetMachine::getSubtargetImpl(const Function &) const {
+  return &SubTarget;
 }
+
+//===----------------------------------------------------------------------===//
+// Pass Pipeline Configuration
+//===----------------------------------------------------------------------===//
+
+bool AVRPassConfig::addInstSelector() {
+  // Install an instruction selector.
+  addPass(createAVRISelDag(getAVRTargetMachine(), getOptLevel()));
+  // Create the frame analyzer pass used by the PEI pass.
+  addPass(createAVRFrameAnalyzerPass());
+
+  return false;
+}
+
+void AVRPassConfig::addPreRegAlloc() {
+  // Create the dynalloc SP save/restore pass to handle variable sized allocas.
+  addPass(createAVRDynAllocaSRPass());
+}
+
+void AVRPassConfig::addPreSched2() { addPass(createAVRExpandPseudoPass()); }
+
+void AVRPassConfig::addPreEmitPass() {
+  // Must run branch selection immediately preceding the asm printer.
+  addPass(createAVRBranchSelectionPass());
+}
+
+} // end of namespace llvm

lib/Target/AVR/CMakeLists.txt

 set(LLVM_TARGET_DEFINITIONS AVR.td)
 
 tablegen(LLVM AVRGenRegisterInfo.inc -gen-register-info)
 tablegen(LLVM AVRGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM AVRGenCallingConv.inc -gen-callingconv)
+tablegen(LLVM AVRGenSubtargetInfo.inc -gen-subtarget)
 add_public_tablegen_target(AVRCommonTableGen)
 
 add_llvm_target(AVRCodeGen
     AVRTargetMachine.cpp
     AVRTargetObjectFile.cpp
+    AVRSubtarget.cpp
+    AVRInstrInfo.cpp
+    AVRRegisterInfo.cpp
   )
 
 add_dependencies(LLVMAVRCodeGen intrinsics_gen)
 
 add_subdirectory(TargetInfo)
 

lib/Target/AVR/MCTargetDesc/AVRMCTargetDesc.h

+//===-- AVRMCTargetDesc.h - AVR Target Descriptions -------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides AVR specific target descriptions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_AVR_MCTARGET_DESC_H
+#define LLVM_AVR_MCTARGET_DESC_H
+
+#include "AVRConfig.h"
+
+#include "llvm/Support/DataTypes.h"
+
+namespace llvm {
+
+class MCCodeEmitter;
+class MCAsmBackend;
+class MCRegisterInfo;
+class MCObjectWriter;
+class MCInstrInfo;
+class MCContext;
+class StringRef;
+class Target;
+class Triple;
+class raw_pwrite_stream;
+
+extern Target TheAVRTarget;
+
+/**
+ * Creates a machine code emitter for AVR.
+ */
+MCCodeEmitter *createAVRMCCodeEmitter(const MCInstrInfo &MCII,
+                                      const MCRegisterInfo &MRI,
+                                      MCContext &Ctx);
+
+/**
+ * Creates an assembly backend for AVR.
+ */
+MCAsmBackend *createAVRAsmBackend(const Target &T, const MCRegisterInfo &MRI,
+                                  const Triple &TT, StringRef CPU);
+
+/**
+ * Creates an ELF object writer for AVR.
+ */
+MCObjectWriter *createAVRELFObjectWriter(raw_pwrite_stream &OS, uint8_t OSABI);
+
+} // end namespace llvm
+
+#define GET_REGINFO_ENUM
+#include "AVRGenRegisterInfo.inc"
+
+#define GET_INSTRINFO_ENUM
+#include "AVRGenInstrInfo.inc"
+
+#define GET_SUBTARGETINFO_ENUM
+#include "AVRGenSubtargetInfo.inc"
+
+#endif // LLVM_AVR_MCTARGET_DESC_H