[TableGen] Make ParseOperandName method const (NFC)

Also change its name to start with a lowercase letter and update
the doxygen comment to conform to the coding standard.

Author: s-barannikov

llvm/utils/TableGen/Common/CodeGenInstruction.cpp

@@ -227,7 +227,7 @@ CGIOperandList::findSubOperandAlias(StringRef Name) const {
 }
 
 std::pair<unsigned, unsigned>
-CGIOperandList::ParseOperandName(StringRef Op, bool AllowWholeOp) {
+CGIOperandList::parseOperandName(StringRef Op, bool AllowWholeOp) const {
   if (!Op.starts_with("$"))
     PrintFatalError(TheDef->getLoc(),
                     TheDef->getName() + ": Illegal operand name: '" + Op + "'");
@@ -307,7 +307,7 @@ static void ParseConstraint(StringRef CStr, CGIOperandList &Ops,
                       "Illegal format for @earlyclobber constraint in '" +
                           Rec->getName() + "': '" + CStr + "'");
     Name = Name.substr(wpos);
-    std::pair<unsigned, unsigned> Op = Ops.ParseOperandName(Name, false);
+    std::pair<unsigned, unsigned> Op = Ops.parseOperandName(Name, false);
 
     // Build the string for the operand
     if (!Ops[Op.first].Constraints[Op.second].isNone())
@@ -335,15 +335,15 @@ static void ParseConstraint(StringRef CStr, CGIOperandList &Ops,
                     "Illegal format for tied-to constraint in '" +
                         Rec->getName() + "': '" + CStr + "'");
   StringRef LHSOpName = CStr.substr(start, wpos - start);
-  std::pair<unsigned, unsigned> LHSOp = Ops.ParseOperandName(LHSOpName, false);
+  std::pair<unsigned, unsigned> LHSOp = Ops.parseOperandName(LHSOpName, false);
 
   wpos = CStr.find_first_not_of(" \t", pos + 1);
   if (wpos == StringRef::npos)
     PrintFatalError(Rec->getLoc(),
                     "Illegal format for tied-to constraint: '" + CStr + "'");
 
   StringRef RHSOpName = CStr.substr(wpos);
-  std::pair<unsigned, unsigned> RHSOp = Ops.ParseOperandName(RHSOpName, false);
+  std::pair<unsigned, unsigned> RHSOp = Ops.parseOperandName(RHSOpName, false);
 
   // Sort the operands into order, which should put the output one
   // first. But keep the original order, for use in diagnostics.
@@ -414,7 +414,7 @@ void CGIOperandList::ProcessDisableEncoding(StringRef DisableEncoding) {
       break;
 
     // Figure out which operand this is.
-    std::pair<unsigned, unsigned> Op = ParseOperandName(OpName, false);
+    std::pair<unsigned, unsigned> Op = parseOperandName(OpName, false);
 
     // Mark the operand as not-to-be encoded.
     OperandList[Op.first].DoNotEncode[Op.second] = true;

llvm/utils/TableGen/Common/CodeGenInstruction.h

@@ -183,12 +183,12 @@ class CGIOperandList {
   std::optional<std::pair<unsigned, unsigned>>
   findSubOperandAlias(StringRef Name) const;
 
-  /// ParseOperandName - Parse an operand name like "$foo" or "$foo.bar",
+  /// Parses an operand name like "$foo" or "$foo.bar",
   /// where $foo is a whole operand and $foo.bar refers to a suboperand.
   /// This aborts if the name is invalid.  If AllowWholeOp is true, references
   /// to operands with suboperands are allowed, otherwise not.
-  std::pair<unsigned, unsigned> ParseOperandName(StringRef Op,
-                                                 bool AllowWholeOp = true);
+  std::pair<unsigned, unsigned>
+  parseOperandName(StringRef Op, bool AllowWholeOp = true) const;
 
   /// getFlattenedOperandNumber - Flatten a operand/suboperand pair into a
   /// flat machineinstr operand #.

llvm/utils/TableGen/Common/VarLenCodeEmitterGen.cpp

@@ -447,7 +447,7 @@ VarLenCodeEmitterGen::getInstructionCases(const Record *R,
 std::string VarLenCodeEmitterGen::getInstructionCaseForEncoding(
     const Record *R, AltEncodingTy Mode, const VarLenInst &VLI,
     const CodeGenTarget &Target, int Indent) {
-  CodeGenInstruction &CGI = Target.getInstruction(R);
+  const CodeGenInstruction &CGI = Target.getInstruction(R);
 
   std::string Case;
   raw_string_ostream SS(Case);
@@ -474,7 +474,7 @@ std::string VarLenCodeEmitterGen::getInstructionCaseForEncoding(
         LoBit = static_cast<unsigned>(cast<IntInit>(DV->getArg(2))->getValue());
       }
 
-      auto OpIdx = CGI.Operands.ParseOperandName(OperandName);
+      auto OpIdx = CGI.Operands.parseOperandName(OperandName);
       unsigned FlatOpIdx = CGI.Operands.getFlattenedOperandNumber(OpIdx);
       StringRef CustomEncoder =
           CGI.Operands[OpIdx.first].EncoderMethodNames[OpIdx.second];

llvm/utils/TableGen/DecoderEmitter.cpp

@@ -1885,9 +1885,7 @@ static void parseVarLenInstOperand(const Record &Def,
     }
 
     if (!OpName.empty()) {
-      auto OpSubOpPair =
-          const_cast<CodeGenInstruction &>(CGI).Operands.ParseOperandName(
-              OpName);
+      auto OpSubOpPair = CGI.Operands.parseOperandName(OpName);
       unsigned OpIdx = CGI.Operands.getFlattenedOperandNumber(OpSubOpPair);
       Operands[OpIdx].addField(CurrBitPos, EncodingSegment.BitWidth, Offset);
       if (!EncodingSegment.CustomDecoder.empty())