[AArch64] Remove DecodeAuthLoadWriteback

[samparker]

Summary

The BaseAuthLoad instruction class was incorrectly passing an empty constraint string to its parent, so I have corrected this. This makes the DecodeAuthLoadWriteback function redundant, so I've also removed it.

Thanks to Ahmed for bringing this to my attention!

[ab]

Ah, that explains it. LGTM, thanks!

llvm/trunk/lib/Target/AArch64/AArch64InstrFormats.td

class AuthReturn<bits<3> op, bits<1> M, string asm>
   let Inst{24} = 0;
   let Inst{23-21} = op;
   let Inst{9-0} = 0b1111111111;
 }
 
 let mayLoad = 1 in
 class BaseAuthLoad<bit M, bit W, dag oops, dag iops, string asm,
                    string operands, string cstr, Operand opr>
-  : I<oops, iops, asm, operands, "", []>, Sched<[]> {
+  : I<oops, iops, asm, operands, cstr, []>, Sched<[]> {
   bits<10> offset;
   bits<5> Rn;
   bits<5> Rt;
   let Inst{31-24} = 0b11111000;
   let Inst{23} = M;
   let Inst{22} = offset{9};
   let Inst{21} = 1;
   let Inst{20-12} = offset{8-0};
   let Inst{11} = W;
   let Inst{10} = 1;
   let Inst{9-5} = Rn;
   let Inst{4-0} = Rt;
 }
 
 multiclass AuthLoad<bit M, string asm, Operand opr> {
-  def indexed   : BaseAuthLoad<M, 0, (outs GPR64:$Rt), (ins GPR64sp:$Rn, opr:$offset),
+  def indexed   : BaseAuthLoad<M, 0, (outs GPR64:$Rt),
+                               (ins GPR64sp:$Rn, opr:$offset),
                                asm, "\t$Rt, [$Rn, $offset]", "", opr>;
   def writeback : BaseAuthLoad<M, 1, (outs GPR64sp:$wback, GPR64:$Rt),
                                (ins GPR64sp:$Rn, opr:$offset),
                                asm, "\t$Rt, [$Rn, $offset]!",
-                               "$Rn = $wback,@earlyclobber $wback", opr> {
-    let DecoderMethod = "DecodeAuthLoadWriteback";
-  }
+                               "$Rn = $wback,@earlyclobber $wback", opr>;
 
   def : InstAlias<asm # "\t$Rt, [$Rn]",
                   (!cast<Instruction>(NAME # "indexed") GPR64:$Rt, GPR64sp:$Rn, 0)>;
 }
 
 //---
 // Conditional branch instruction.
 //---

llvm/trunk/lib/Target/AArch64/Disassembler/AArch64Disassembler.cpp

static DecodeStatus DecodeSImm(llvm::MCInst &Inst, uint64_t Imm,
   // Imm is a signed immediate, so sign extend it.
   if (Imm & (1 << (Bits - 1)))
     Imm |= ~((1LL << Bits) - 1);
 
   Inst.addOperand(MCOperand::createImm(Imm));
   return Success;
 }
 
-static DecodeStatus DecodeAuthLoadWriteback(llvm::MCInst &Inst, uint32_t insn,
-                                            uint64_t Address,
-                                            const void *Decoder) {
-  unsigned Rt = fieldFromInstruction(insn, 0, 5);
-  unsigned Rn = fieldFromInstruction(insn, 5, 5);
-  unsigned Imm9 = fieldFromInstruction(insn, 12, 9);
-  unsigned S = fieldFromInstruction(insn, 22, 1);
-
-  unsigned Imm = Imm9 | (S << 9);
-
-  // Address writeback
-  DecodeGPR64spRegisterClass(Inst, Rn, Address, Decoder);
-  // Destination
-  DecodeGPR64RegisterClass(Inst, Rt, Address, Decoder);
-  // Address
-  DecodeGPR64spRegisterClass(Inst, Rn, Address, Decoder);
-  // Offset
-  DecodeSImm<10>(Inst, Imm, Address, Decoder);
-
-  return Success;
-}