[LLVM][TableGen] Change a few emitters to use const Record pointers (#110112)

Change DirectiveEmitter, Option Emitter, and X86 Emitters to use const
Record pointers.

This is a part of effort to have better const correctness in TableGen
backends:


https://discourse.llvm.org/t/psa-planned-changes-to-tablegen-getallderiveddefinitions-api-potential-downstream-breakages/81089

Author: jurahul

llvm/include/llvm/TableGen/DirectiveEmitter.h

@@ -135,24 +135,24 @@ class Directive : public BaseRecord {
 public:
   Directive(const Record *Def) : BaseRecord(Def) {}
 
-  std::vector<Record *> getAllowedClauses() const {
-    return Def->getValueAsListOfDefs("allowedClauses");
+  std::vector<const Record *> getAllowedClauses() const {
+    return Def->getValueAsListOfConstDefs("allowedClauses");
   }
 
-  std::vector<Record *> getAllowedOnceClauses() const {
-    return Def->getValueAsListOfDefs("allowedOnceClauses");
+  std::vector<const Record *> getAllowedOnceClauses() const {
+    return Def->getValueAsListOfConstDefs("allowedOnceClauses");
   }
 
-  std::vector<Record *> getAllowedExclusiveClauses() const {
-    return Def->getValueAsListOfDefs("allowedExclusiveClauses");
+  std::vector<const Record *> getAllowedExclusiveClauses() const {
+    return Def->getValueAsListOfConstDefs("allowedExclusiveClauses");
   }
 
-  std::vector<Record *> getRequiredClauses() const {
-    return Def->getValueAsListOfDefs("requiredClauses");
+  std::vector<const Record *> getRequiredClauses() const {
+    return Def->getValueAsListOfConstDefs("requiredClauses");
   }
 
-  std::vector<Record *> getLeafConstructs() const {
-    return Def->getValueAsListOfDefs("leafConstructs");
+  std::vector<const Record *> getLeafConstructs() const {
+    return Def->getValueAsListOfConstDefs("leafConstructs");
   }
 
   Record *getAssociation() const { return Def->getValueAsDef("association"); }
@@ -203,8 +203,8 @@ class Clause : public BaseRecord {
     return Def->getValueAsString("enumClauseValue");
   }
 
-  std::vector<Record *> getClauseVals() const {
-    return Def->getValueAsListOfDefs("allowedClauseValues");
+  std::vector<const Record *> getClauseVals() const {
+    return Def->getValueAsListOfConstDefs("allowedClauseValues");
   }
 
   bool isValueOptional() const { return Def->getValueAsBit("isValueOptional"); }

llvm/utils/TableGen/CallingConvEmitter.cpp

@@ -131,9 +131,9 @@ void CallingConvEmitter::EmitAction(const Record *Action, unsigned Indent,
     O << IndentStr << "if (";
 
     if (Action->isSubClassOf("CCIfType")) {
-      ListInit *VTs = Action->getValueAsListInit("VTs");
+      const ListInit *VTs = Action->getValueAsListInit("VTs");
       for (unsigned i = 0, e = VTs->size(); i != e; ++i) {
-        Record *VT = VTs->getElementAsRecord(i);
+        const Record *VT = VTs->getElementAsRecord(i);
         if (i != 0)
           O << " ||\n    " << IndentStr;
         O << "LocVT == " << getEnumName(getValueType(VT));

llvm/utils/TableGen/DirectiveEmitter.cpp

@@ -343,8 +343,9 @@ static void GenerateGetKindClauseVal(const DirectiveLanguage &DirLang,
     if (ClauseVals.size() <= 0)
       continue;
 
-    auto DefaultIt = find_if(
-        ClauseVals, [](Record *CV) { return CV->getValueAsBit("isDefault"); });
+    auto DefaultIt = find_if(ClauseVals, [](const Record *CV) {
+      return CV->getValueAsBit("isDefault");
+    });
 
     if (DefaultIt == ClauseVals.end()) {
       PrintError("At least one val in Clause " + C.getFormattedName() +
@@ -505,7 +506,7 @@ static void EmitLeafTable(const DirectiveLanguage &DirLang, raw_ostream &OS,
   std::vector<LeafList> LeafTable(Directives.size());
   for (auto [Idx, Rec] : enumerate(Directives)) {
     Directive Dir(Rec);
-    std::vector<Record *> Leaves = Dir.getLeafConstructs();
+    std::vector<const Record *> Leaves = Dir.getLeafConstructs();
 
     auto &List = LeafTable[Idx];
     List.resize(MaxLeafCount + 2);
@@ -680,7 +681,7 @@ static void GenerateGetDirectiveAssociation(const DirectiveLanguage &DirLang,
       return AS;
     }
     // Compute the association from leaf constructs.
-    std::vector<Record *> leaves = D.getLeafConstructs();
+    std::vector<const Record *> leaves = D.getLeafConstructs();
     if (leaves.empty()) {
       errs() << D.getName() << '\n';
       PrintFatalError(errorPrefixFor(D) +

llvm/utils/TableGen/OptionParserEmitter.cpp

@@ -471,13 +471,13 @@ static void EmitOptionParser(const RecordKeeper &Records, raw_ostream &OS) {
 
     std::vector<std::pair<std::vector<std::string>, StringRef>>
         HelpTextsForVariants;
-    for (Record *VisibilityHelp :
+    for (const Record *VisibilityHelp :
          R.getValueAsListOfDefs("HelpTextsForVariants")) {
       ArrayRef<Init *> Visibilities =
           VisibilityHelp->getValueAsListInit("Visibilities")->getValues();
 
       std::vector<std::string> VisibilityNames;
-      for (Init *Visibility : Visibilities)
+      for (const Init *Visibility : Visibilities)
         VisibilityNames.push_back(Visibility->getAsUnquotedString());
 
       HelpTextsForVariants.push_back(std::make_pair(

llvm/utils/TableGen/OptionRSTEmitter.cpp

@@ -18,7 +18,6 @@ using namespace llvm;
 /// and emits a RST man page.
 static void EmitOptionRST(const RecordKeeper &Records, raw_ostream &OS) {
   llvm::StringMap<std::vector<const Record *>> OptionsByGroup;
-  std::vector<Record *> OptionsWithoutGroup;
 
   // Get the options.
   std::vector<const Record *> Opts = Records.getAllDerivedDefinitions("Option");

llvm/utils/TableGen/X86FoldTablesEmitter.cpp

@@ -475,7 +475,7 @@ void X86FoldTablesEmitter::addEntryWithFlags(FoldTable &Table,
   StringRef RegInstName = RegRec->getName();
   unsigned DropLen =
       RegInstName.ends_with("rkz") ? 2 : (RegInstName.ends_with("rk") ? 1 : 0);
-  Record *BaseDef =
+  const Record *BaseDef =
       DropLen ? Records.getDef(RegInstName.drop_back(DropLen)) : nullptr;
   bool IsMoveReg =
       BaseDef ? Target.getInstruction(BaseDef).isMoveReg : RegInst->isMoveReg;

llvm/utils/TableGen/X86InstrMappingEmitter.cpp

@@ -215,7 +215,7 @@ void X86InstrMappingEmitter::emitCompressEVEXTable(
     StringRef Name = Rec->getName();
     const CodeGenInstruction *NewInst = nullptr;
     if (ManualMap.find(Name) != ManualMap.end()) {
-      Record *NewRec = Records.getDef(ManualMap.at(Rec->getName()));
+      const Record *NewRec = Records.getDef(ManualMap.at(Rec->getName()));
       assert(NewRec && "Instruction not found!");
       NewInst = &Target.getInstruction(NewRec);
     } else if (Name.ends_with("_EVEX")) {