[LLVM][TableGen] Change all Init pointers to const (#112705)

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

clang/utils/TableGen/ClangOptionDocEmitter.cpp

@@ -367,13 +367,13 @@ void emitOption(const DocumentedOption &Option, const Record *DocInfo,
   for (const Record *VisibilityHelp :
        R->getValueAsListOfDefs("HelpTextsForVariants")) {
     // This is a list of visibilities.
-    ArrayRef<Init *> Visibilities =
+    ArrayRef<const Init *> Visibilities =
         VisibilityHelp->getValueAsListInit("Visibilities")->getValues();
 
     // See if any of the program's visibilities are in the list.
     for (StringRef DocInfoMask :
          DocInfo->getValueAsListOfStrings("VisibilityMask")) {
-      for (Init *Visibility : Visibilities) {
+      for (const Init *Visibility : Visibilities) {
         if (Visibility->getAsUnquotedString() == DocInfoMask) {
           // Use the first one we find.
           Description = escapeRST(VisibilityHelp->getValueAsString("Text"));

llvm/include/llvm/TableGen/Error.h

@@ -49,8 +49,8 @@ void PrintError(const RecordVal *RecVal, const Twine &Msg);
 [[noreturn]] void PrintFatalError(function_ref<void(raw_ostream &OS)> PrintMsg);
 
 // Returns true if the assert failed.
-bool CheckAssert(SMLoc Loc, Init *Condition, Init *Message);
-void dumpMessage(SMLoc Loc, Init *Message);
+bool CheckAssert(SMLoc Loc, const Init *Condition, const Init *Message);
+void dumpMessage(SMLoc Loc, const Init *Message);
 
 extern SourceMgr SrcMgr;
 extern unsigned ErrorsPrinted;