[LLVM][TableGen] Change X86FoldTablesEmitter to use const RecordKeeper (#109070)

Change X86FoldTablesEmitter to use const RecordKeeper.

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/utils/TableGen/X86FoldTablesEmitter.cpp

@@ -63,8 +63,8 @@ static bool isExplicitUnalign(const CodeGenInstruction *Inst) {
 }
 
 class X86FoldTablesEmitter {
-  RecordKeeper &Records;
-  CodeGenTarget Target;
+  const RecordKeeper &Records;
+  const CodeGenTarget Target;
 
   // Represents an entry in the folding table
   class X86FoldTableEntry {
@@ -196,7 +196,7 @@ class X86FoldTablesEmitter {
   FoldTable BroadcastTable4;
 
 public:
-  X86FoldTablesEmitter(RecordKeeper &R) : Records(R), Target(R) {}
+  X86FoldTablesEmitter(const RecordKeeper &R) : Records(R), Target(R) {}
 
   // run - Generate the 6 X86 memory fold tables.
   void run(raw_ostream &OS);
@@ -670,7 +670,7 @@ void X86FoldTablesEmitter::run(raw_ostream &OS) {
   // added into memory fold tables.
   auto RegInstsForBroadcast = RegInsts;
 
-  Record *AsmWriter = Target.getAsmWriter();
+  const Record *AsmWriter = Target.getAsmWriter();
   unsigned Variant = AsmWriter->getValueAsInt("Variant");
   auto FixUp = [&](const CodeGenInstruction *RegInst) {
     StringRef RegInstName = RegInst->TheDef->getName();
@@ -721,8 +721,8 @@ void X86FoldTablesEmitter::run(raw_ostream &OS) {
 
   // Add the manually mapped instructions listed above.
   for (const ManualMapEntry &Entry : ManualMapSet) {
-    Record *RegInstIter = Records.getDef(Entry.RegInstStr);
-    Record *MemInstIter = Records.getDef(Entry.MemInstStr);
+    const Record *RegInstIter = Records.getDef(Entry.RegInstStr);
+    const Record *MemInstIter = Records.getDef(Entry.MemInstStr);
 
     updateTables(&(Target.getInstruction(RegInstIter)),
                  &(Target.getInstruction(MemInstIter)), Entry.Strategy, true);