[AVR] Add MOVW disassembly

Author: tomtor

llvm/lib/Target/AVR/Disassembler/AVRDisassembler.cpp

@@ -328,6 +328,22 @@ static DecodeStatus decodeCondBranch(MCInst &Inst, unsigned Insn,
   return MCDisassembler::Success;
 }
 
+static DecodeStatus decodeMoveWord(MCInst &Inst, unsigned Insn,
+                                   uint64_t Address,
+                                   const MCDisassembler *Decoder) {
+  // Get the registers
+  unsigned RegValD = GPRDecoderTable[2 * ((Insn >> 4) & 0xf)];
+  unsigned RegValR = GPRDecoderTable[2 * (Insn & 0xf)];
+
+  if ((Insn & 0xff00) == 0x0100) {
+    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) {
@@ -502,6 +518,11 @@ 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 load/store instruction. ST/LD need a specified
     // DecoderMethod, as they already have a specified PostEncoderMethod.
     Result = decodeLoadStore(Instr, Insn, Address, this);