[AMDGPU][AsmParser][NFC] Immediate operand classes to derive from custom operands.

[kosarev]

Summary

Removes unnecessary duplication in TableGen definitions.

Part of https://github.com/llvm/llvm-project/issues/62629.

[dp]

LGTM.

llvm/lib/Target/AMDGPU/AMDGPUInstructions.td

 def NoFP64Denormals : Predicate<"!MF->getInfo<SIMachineFunctionInfo>()->getMode().allFP64FP16Denormals()">;
 def UnsafeFPMath : Predicate<"TM.Options.UnsafeFPMath">;
 }
 
 def FMA : Predicate<"Subtarget->hasFMA()">;
 
 def InstFlag : OperandWithDefaultOps <i32, (ops (i32 0))>;
 
-class ImmOperandClass<string name, bit optional> : AsmOperandClass {
+class CustomOperandClass<string name, bit optional> : AsmOperandClass {
   let Name = name;
   let PredicateMethod = "is"#name;
-  let ParserMethod = "";
+  let ParserMethod = "parse"#name;
   let RenderMethod = "addImmOperands";
   let IsOptional = optional;
   let DefaultMethod = "default"#name;
 }
 
+class CustomOperandProps<bit optional = 0, string name = NAME,
+    AsmOperandClass opClass = CustomOperandClass<name, optional>> {
+  string PrintMethod = "print"#name;
+  AsmOperandClass ParserMatchClass = opClass;
+  string OperandType = "OPERAND_IMMEDIATE";
+}
+
+class CustomOperand<ValueType type, bit optional = 0, string name = NAME,
+    AsmOperandClass opClass = CustomOperandClass<name, optional>>
+  : Operand<type>, CustomOperandProps<optional, name, opClass>;
+
+class ImmOperandClass<string name, bit optional>
+    : CustomOperandClass<name, optional> {
+  let ParserMethod = "";
+}
+
 class ImmOperand<ValueType type, string name, bit optional = 0,
-                 string printer = "print"#name> : Operand<type> {
-  let ParserMatchClass = ImmOperandClass<name, optional>;
+                 string printer = "print"#name>
+    : CustomOperand<type, optional, name, ImmOperandClass<name, optional>> {
   let PrintMethod = printer;
-  let OperandType = "OPERAND_IMMEDIATE";
 }
 
 def s16imm : ImmOperand<i16, "S16Imm", 0, "printU16ImmOperand">;
 def u16imm : ImmOperand<i16, "U16Imm", 0, "printU16ImmOperand">;
 
 //===--------------------------------------------------------------------===//
 // Custom Operands
 //===--------------------------------------------------------------------===//

llvm/lib/Target/AMDGPU/SIInstrInfo.td

 def SDWAVopcDst : BoolRC {
   let OperandNamespace = "AMDGPU";
   let OperandType = "OPERAND_SDWA_VOPC_DST";
   let EncoderMethod = "getSDWAVopcDstEncoding";
   let DecoderMethod = "decodeSDWAVopcDst";
   let PrintMethod = "printVOPDst";
 }
 
-class CustomOperandClass<string CName, bit Optional> : AsmOperandClass {
-  let Name = CName;
-  let PredicateMethod = "is"#CName;
-  let ParserMethod = "parse"#CName;
-  let RenderMethod = "addImmOperands";
-  let IsOptional = Optional;
-  let DefaultMethod = "default"#CName;
-}
-
-class CustomOperandProps<bit Optional = 0, string Name = NAME,
-    AsmOperandClass Class = CustomOperandClass<Name, Optional>> {
-  string PrintMethod = "print"#Name;
-  AsmOperandClass ParserMatchClass = Class;
-  string OperandType = "OPERAND_IMMEDIATE";
-}
-
-class CustomOperand<ValueType Type, bit Optional = 0, string Name = NAME,
-    AsmOperandClass Class = CustomOperandClass<Name, Optional>>
-  : Operand<Type>, CustomOperandProps<Optional, Name, Class>;
-
 class NamedIntOperandClass<string Prefix, string Name, string ConvertMethod>
     : CustomOperandClass<Name, 1> {
   string ImmTy = "AMDGPUOperand::ImmTy"#Name;
   let ParserMethod =
     "[this](OperandVector &Operands) -> OperandMatchResultTy { "#
     "return parseIntWithPrefix(\""#Prefix#"\", Operands, "#ImmTy#", "#
     ConvertMethod#"); }";
 }