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[AVR] Add AVR MOVW/ADIW/SUBIW disassembly #146360

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[AVR] Add AVR MOVW/ADIW/SUBIW disassembly #146360

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fcb60b2
[AVR] Add MOVW disassembly
tomtor Jun 30, 2025
2f48e11
[AVR] Add ADIW disassembly
tomtor Jun 30, 2025
b9eeb0c
[AVR] Add SUBIW disassembly
tomtor Jun 30, 2025
9e26c52
fix formatting
tomtor Jun 30, 2025
f711e7c
refactor
tomtor Jun 30, 2025
ad003f7
Add Patryk suggestion
tomtor Jun 30, 2025
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55 changes: 55 additions & 0 deletions llvm/lib/Target/AVR/Disassembler/AVRDisassembler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -328,6 +328,51 @@ static DecodeStatus decodeCondBranch(MCInst &Inst, unsigned Insn,
return MCDisassembler::Success;
}

static DecodeStatus decodeAddSubWordImm(MCInst &Inst, unsigned Insn,
uint64_t Address,
const MCDisassembler *Decoder) {
if ((Insn & 0xfe00) == 0x9600) {
// Get the register
unsigned RegVal;
switch ((Insn >> 4) & 0x3) {
case 0:
RegVal = AVR::R25R24;
break;
case 1:
RegVal = AVR::R27R26;
break;
case 2:
RegVal = AVR::R29R28;
break;
case 3:
RegVal = AVR::R31R30;
}

Inst.setOpcode((Insn & 0xff00) == 0x9600 ? AVR::ADIWRdK : AVR::SUBIWRdK);
Inst.addOperand(MCOperand::createReg(RegVal));
Inst.addOperand(MCOperand::createReg(RegVal));
unsigned imm = ((Insn & 0x00C0) >> 2) | (Insn & 0xF);
Inst.addOperand(MCOperand::createImm(imm));
return MCDisassembler::Success;
}
return MCDisassembler::Fail;
}

static DecodeStatus decodeMoveWord(MCInst &Inst, unsigned Insn,
uint64_t Address,
const MCDisassembler *Decoder) {
if ((Insn & 0xff00) == 0x0100) {
// Get the registers
unsigned RegValD = GPRDecoderTable[2 * ((Insn >> 4) & 0xf)];
unsigned RegValR = GPRDecoderTable[2 * (Insn & 0xf)];
Inst.setOpcode(AVR::MOVWRdRr);
Inst.addOperand(MCOperand::createReg(RegValD));
Inst.addOperand(MCOperand::createReg(RegValR));
return MCDisassembler::Success;
}
return MCDisassembler::Fail;
}

static DecodeStatus decodeLoadStore(MCInst &Inst, unsigned Insn,
uint64_t Address,
const MCDisassembler *Decoder) {
Expand Down Expand Up @@ -502,6 +547,16 @@ DecodeStatus AVRDisassembler::getInstruction(MCInst &Instr, uint64_t &Size,
if (Result != MCDisassembler::Fail)
return Result;

// Try to decode to a MOVW instruction
Result = decodeMoveWord(Instr, Insn, Address, this);
if (Result != MCDisassembler::Fail)
return Result;

// Try to decode to a ADIW /SBIW instruction
Result = decodeAddSubWordImm(Instr, Insn, Address, this);
if (Result != MCDisassembler::Fail)
return Result;

// Try to decode to a load/store instruction. ST/LD need a specified
// DecoderMethod, as they already have a specified PostEncoderMethod.
Result = decodeLoadStore(Instr, Insn, Address, this);
Expand Down