[turbofan][arm64] Use immediates instead of MiscField for stack operations.

src/compiler/arm64/code-generator-arm64.cc

Index: src/compiler/arm64/code-generator-arm64.cc
diff --git a/src/compiler/arm64/code-generator-arm64.cc b/src/compiler/arm64/code-generator-arm64.cc
index 34ec3821f7ba1605d0865c5a52414df7848dc993..1008ddcecbdcb916cefde6c79e1ce963d8a2345d 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -610,24 +610,16 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       // Pseudo instruction turned into cbz/cbnz in AssembleArchBranch.
       break;
     case kArm64Claim: {
-      int words = MiscField::decode(instr->opcode());
-      __ Claim(words);
+      __ Claim(i.InputInt32(0));
       break;
     }
     case kArm64Poke: {
-      int slot = MiscField::decode(instr->opcode());
-      Operand operand(slot * kPointerSize);
+      Operand operand(i.InputInt32(1) * kPointerSize);
       __ Poke(i.InputRegister(0), operand);
       break;
     }
-    case kArm64PokePairZero: {
-      // TODO(dcarney): test slot offset and register order.
-      int slot = MiscField::decode(instr->opcode()) - 1;
-      __ PokePair(i.InputRegister(0), xzr, slot * kPointerSize);
-      break;
-    }
     case kArm64PokePair: {
-      int slot = MiscField::decode(instr->opcode()) - 1;
+      int slot = i.InputInt32(2) - 1;
       __ PokePair(i.InputRegister(1), i.InputRegister(0), slot * kPointerSize);
       break;
     }