//===-- AVRRegisterInfo.td - AVR Register defs -------------*- tablegen -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

//===----------------------------------------------------------------------===//
//  Declarations that describe the AVR register file
//===----------------------------------------------------------------------===//

// 8-bit General purpose register definition.
class AVRReg<bits<16> num,
             string name,
             list<Register> subregs = [],
             list<string> altNames = []>
  : RegisterWithSubRegs<name, subregs>
{
  field bits<16> Num = num;

  let HWEncoding = num;
  let Namespace = "AVR";
  let SubRegs = subregs;
  let AltNames = altNames;
}

// Subregister indices.
let Namespace = "AVR" in
{
  def sub_lo : SubRegIndex<8>;
  def sub_hi : SubRegIndex<8, 8>;
}

let Namespace = "AVR" in {
  def ptr : RegAltNameIndex;
}


//===----------------------------------------------------------------------===//
//  8-bit general purpose registers
//===----------------------------------------------------------------------===//

def R0  : AVRReg<0,  "r0">,  DwarfRegNum<[0]>;
def R1  : AVRReg<1,  "r1">,  DwarfRegNum<[1]>;
def R2  : AVRReg<2,  "r2">,  DwarfRegNum<[2]>;
def R3  : AVRReg<3,  "r3">,  DwarfRegNum<[3]>;
def R4  : AVRReg<4,  "r4">,  DwarfRegNum<[4]>;
def R5  : AVRReg<5,  "r5">,  DwarfRegNum<[5]>;
def R6  : AVRReg<6,  "r6">,  DwarfRegNum<[6]>;
def R7  : AVRReg<7,  "r7">,  DwarfRegNum<[7]>;
def R8  : AVRReg<8,  "r8">,  DwarfRegNum<[8]>;
def R9  : AVRReg<9,  "r9">,  DwarfRegNum<[9]>;
def R10 : AVRReg<10, "r10">, DwarfRegNum<[10]>;
def R11 : AVRReg<11, "r11">, DwarfRegNum<[11]>;
def R12 : AVRReg<12, "r12">, DwarfRegNum<[12]>;
def R13 : AVRReg<13, "r13">, DwarfRegNum<[13]>;
def R14 : AVRReg<14, "r14">, DwarfRegNum<[14]>;
def R15 : AVRReg<15, "r15">, DwarfRegNum<[15]>;
def R16 : AVRReg<16, "r16">, DwarfRegNum<[16]>;
def R17 : AVRReg<17, "r17">, DwarfRegNum<[17]>;
def R18 : AVRReg<18, "r18">, DwarfRegNum<[18]>;
def R19 : AVRReg<19, "r19">, DwarfRegNum<[19]>;
def R20 : AVRReg<20, "r20">, DwarfRegNum<[20]>;
def R21 : AVRReg<21, "r21">, DwarfRegNum<[21]>;
def R22 : AVRReg<22, "r22">, DwarfRegNum<[22]>;
def R23 : AVRReg<23, "r23">, DwarfRegNum<[23]>;
def R24 : AVRReg<24, "r24">, DwarfRegNum<[24]>;
def R25 : AVRReg<25, "r25">, DwarfRegNum<[25]>;
def R26 : AVRReg<26, "r26">, DwarfRegNum<[26]>;
def R27 : AVRReg<27, "r27">, DwarfRegNum<[27]>;
def R28 : AVRReg<28, "r28">, DwarfRegNum<[28]>;
def R29 : AVRReg<29, "r29">, DwarfRegNum<[29]>;
def R30 : AVRReg<30, "r30">, DwarfRegNum<[30]>;
def R31 : AVRReg<31, "r31">, DwarfRegNum<[31]>;
def SPL : AVRReg<32, "SPL">, DwarfRegNum<[32]>;
def SPH : AVRReg<33, "SPH">, DwarfRegNum<[33]>;

let SubRegIndices = [sub_lo, sub_hi],
CoveredBySubRegs = 1 in
{
  // 16 bit GPR pairs.
  def SP     : AVRReg<32, "SP",      [SPL, SPH]>, DwarfRegNum<[32]>;

  // The pointer registers (X,Y,Z) are a special case because they
  // are printed as a `high:low` pair when a DREG is expected,
  // but printed using `X`, `Y`, `Z` when a pointer register is expected.
  let RegAltNameIndices = [ptr] in {
      def R31R30 : AVRReg<30, "r31:r30", [R30, R31], ["Z"]>, DwarfRegNum<[30]>;
      def R29R28 : AVRReg<28, "r29:r28", [R28, R29], ["Y"]>, DwarfRegNum<[28]>;
      def R27R26 : AVRReg<26, "r27:r26", [R26, R27], ["X"]>, DwarfRegNum<[26]>;
  }
  def R25R24 : AVRReg<24, "r25:r24", [R24, R25]>, DwarfRegNum<[24]>;
  def R23R22 : AVRReg<22, "r23:r22", [R22, R23]>, DwarfRegNum<[22]>;
  def R21R20 : AVRReg<20, "r21:r20", [R20, R21]>, DwarfRegNum<[20]>;
  def R19R18 : AVRReg<18, "r19:r18", [R18, R19]>, DwarfRegNum<[18]>;
  def R17R16 : AVRReg<16, "r17:r16", [R16, R17]>, DwarfRegNum<[16]>;
  def R15R14 : AVRReg<14, "r15:r14", [R14, R15]>, DwarfRegNum<[14]>;
  def R13R12 : AVRReg<12, "r13:r12", [R12, R13]>, DwarfRegNum<[12]>;
  def R11R10 : AVRReg<10, "r11:r10", [R10, R11]>, DwarfRegNum<[10]>;
  def R9R8   : AVRReg<8,  "r9:r8",   [R8, R9]>,   DwarfRegNum<[8]>;
  def R7R6   : AVRReg<6,  "r7:r6",   [R6, R7]>,   DwarfRegNum<[6]>;
  def R5R4   : AVRReg<4,  "r5:r4",   [R4, R5]>,   DwarfRegNum<[4]>;
  def R3R2   : AVRReg<2,  "r3:r2",   [R2, R3]>,   DwarfRegNum<[2]>;
  def R1R0   : AVRReg<0,  "r1:r0",   [R0, R1]>,   DwarfRegNum<[0]>;
}

//===----------------------------------------------------------------------===//
// Register Classes
//===----------------------------------------------------------------------===//

// Main 8-bit register class.
def GPR8 : RegisterClass<"AVR", [i8], 8,
  (
    // Return value and argument registers.
    add R24, R25, R18, R19, R20, R21, R22, R23,
    // Scratch registers.
    R30, R31, R26, R27,
    // Callee saved registers.
    R28, R29, R17, R16, R15, R14, R13, R12, R11, R10,
    R9, R8, R7, R6, R5, R4, R3, R2, R0, R1
  )>;

// Simple lower registers r0..r15
def GPR8lo : RegisterClass<"AVR", [i8], 8,
  (
    add R15, R14, R13, R12, R11, R10, R9, R8, R7, R6, R5, R4, R3, R2, R0, R1
  )>;

// 8-bit register class for instructions which take immediates.
def LD8 : RegisterClass<"AVR", [i8], 8,
  (
    // Return value and arguments.
    add R24, R25, R18, R19, R20, R21, R22, R23,
    // Scratch registers.
    R30, R31, R26, R27,
    // Callee saved registers.
    R28, R29, R17, R16
  )>;

// Simple lower registers r16..r23
def LD8lo : RegisterClass<"AVR", [i8], 8,
  (
    add R23, R22, R21, R20, R19, R18, R17, R16
  )>;

// Main 16-bit pair register class.
def DREGS : RegisterClass<"AVR", [i16], 8,
  (
    // Return value and arguments.
    add R25R24, R19R18, R21R20, R23R22,
    // Scratch registers.
    R31R30, R27R26,
    // Callee saved registers.
    R29R28, R17R16, R15R14, R13R12, R11R10,
    R9R8, R7R6, R5R4, R3R2, R1R0
  )>;

// The 16-bit DREGS register class, excluding the Z pointer register.
//
// This is used by instructions which cause high pointer register
// contention which leads to an assertion in the register allocator.
//
// There is no technical reason why instructions that use this class
// cannot use Z; it's simply a workaround a regalloc bug.
//
// More information can be found in PR39553.
def DREGS_WITHOUT_YZ_WORKAROUND : RegisterClass<"AVR", [i16], 8,
  (
    // Return value and arguments.
    add R25R24, R19R18, R21R20, R23R22,
    // Scratch registers.
    R27R26,
    // Callee saved registers.
    R17R16, R15R14, R13R12, R11R10,
    R9R8, R7R6, R5R4, R3R2, R1R0
  )>;

// 16-bit register class for immediate instructions.
def DLDREGS : RegisterClass<"AVR", [i16], 8,
  (
    // Return value and arguments.
    add R25R24, R19R18, R21R20, R23R22,
    // Scratch registers.
    R31R30, R27R26,
    // Callee saved registers.
    R29R28, R17R16
  )>;

// 16-bit register class for the adiw/sbiw instructions.
def IWREGS : RegisterClass<"AVR", [i16], 8,
  (
    // Return value and arguments.
    add R25R24,
    // Scratch registers.
    R31R30, R27R26,
    // Callee saved registers.
    R29R28
  )>;

// 16-bit register class for the ld and st instructions.
// AKA X,Y, and Z
def PTRREGS : RegisterClass<"AVR", [i16], 8,
  (
    add R27R26, // X
        R29R28, // Y
        R31R30  // Z
  ), ptr>;

// 16-bit register class for the ldd and std instructions.
// AKA Y and Z.
def PTRDISPREGS : RegisterClass<"AVR", [i16], 8,
  (
    add R31R30, R29R28
  ), ptr>;

// We have a bunch of instructions with an explicit Z register argument. We
// model this using a register class containing only the Z register.
def ZREG : RegisterClass<"AVR", [i16], 8, (add R31R30)>;

// Register class used for the stack read pseudo instruction.
def GPRSP: RegisterClass<"AVR", [i16], 8, (add SP)>;

// Status register.
def SREG : AVRReg<14, "FLAGS">, DwarfRegNum<[88]>;
def CCR : RegisterClass<"AVR", [i8], 8, (add SREG)>
{
  let CopyCost = -1;      // Don't allow copying of status registers
}