[llvm] [AVR] Remove some custom decoder functions (NFCI) (PR #156852)

[Ben Shi via llvm-commits]

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@@ -141,18 +106,25 @@ static DecodeStatus decodeCallTarget(MCInst &Inst, unsigned Field,
   return MCDisassembler::Success;
 }
 
-static DecodeStatus decodeFRd(MCInst &Inst, unsigned Insn, uint64_t Address,
-                              const MCDisassembler *Decoder) {
-  unsigned d = fieldFromInstruction(Insn, 4, 5);
-  if (DecodeGPR8RegisterClass(Inst, d, Address, Decoder) ==
-      MCDisassembler::Fail)
-    return MCDisassembler::Fail;
+static DecodeStatus decodeRelCondBrTarget7(MCInst &Inst, unsigned Field,
+                                           uint64_t Address,
+                                           const MCDisassembler *Decoder) {
+  Inst.addOperand(MCOperand::createImm(SignExtend32(Field, 7) << 1));
+  return MCDisassembler::Success;
+}
+
+static DecodeStatus decodeRelCondBrTarget13(MCInst &Inst, unsigned Field,
+                                            uint64_t Address,
+                                            const MCDisassembler *Decoder) {
+  Inst.addOperand(MCOperand::createImm(SignExtend32(Field, 12) << 1));
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benshi001 wrote:

It would be better to commnet `The legal range is [-4096, 4094]`.

https://github.com/llvm/llvm-project/pull/156852