[clang][TableGen] Change AST Nodes Emitter to use const RecordKeeper (#108270)

Change AST Nodes Emitter 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

clang/utils/TableGen/ClangASTNodesEmitter.cpp

@@ -34,7 +34,7 @@ class ClangASTNodesEmitter {
   typedef ChildMap::const_iterator ChildIterator;
 
   std::set<ASTNode> PrioritizedClasses;
-  RecordKeeper &Records;
+  const RecordKeeper &Records;
   ASTNode Root;
   const std::string &NodeClassName;
   const std::string &BaseSuffix;
@@ -70,14 +70,12 @@ class ClangASTNodesEmitter {
 
   std::pair<ASTNode, ASTNode> EmitNode(raw_ostream& OS, ASTNode Base);
 public:
-  explicit ClangASTNodesEmitter(RecordKeeper &R, const std::string &N,
+  explicit ClangASTNodesEmitter(const RecordKeeper &R, const std::string &N,
                                 const std::string &S,
                                 std::string_view PriorizeIfSubclassOf)
       : Records(R), NodeClassName(N), BaseSuffix(S) {
-    auto vecPrioritized =
-        PriorizeIfSubclassOf.empty()
-            ? std::vector<Record *>{}
-            : R.getAllDerivedDefinitions(PriorizeIfSubclassOf);
+    ArrayRef<const Record *> vecPrioritized =
+        R.getAllDerivedDefinitionsIfDefined(PriorizeIfSubclassOf);
     PrioritizedClasses =
         std::set<ASTNode>(vecPrioritized.begin(), vecPrioritized.end());
   }
@@ -169,10 +167,7 @@ void ClangASTNodesEmitter::deriveChildTree() {
   assert(!Root && "already computed tree");
 
   // Emit statements
-  const std::vector<Record*> Stmts
-    = Records.getAllDerivedDefinitions(NodeClassName);
-
-  for (auto *R : Stmts) {
+  for (const Record *R : Records.getAllDerivedDefinitions(NodeClassName)) {
     if (auto B = R->getValueAsOptionalDef(BaseFieldName))
       Tree.insert(std::make_pair(B, R));
     else if (Root)
@@ -217,14 +212,14 @@ void ClangASTNodesEmitter::run(raw_ostream &OS) {
   OS << "#undef ABSTRACT_" << macroHierarchyName() << "\n";
 }
 
-void clang::EmitClangASTNodes(RecordKeeper &RK, raw_ostream &OS,
+void clang::EmitClangASTNodes(const RecordKeeper &RK, raw_ostream &OS,
                               const std::string &N, const std::string &S,
                               std::string_view PriorizeIfSubclassOf) {
   ClangASTNodesEmitter(RK, N, S, PriorizeIfSubclassOf).run(OS);
 }
 
-void printDeclContext(const std::multimap<Record *, Record *> &Tree,
-                      Record *DeclContext, raw_ostream &OS) {
+void printDeclContext(const std::multimap<const Record *, const Record *> &Tree,
+                      const Record *DeclContext, raw_ostream &OS) {
   if (!DeclContext->getValueAsBit(AbstractFieldName))
     OS << "DECL_CONTEXT(" << DeclContext->getName() << ")\n";
   auto i = Tree.lower_bound(DeclContext);
@@ -236,7 +231,7 @@ void printDeclContext(const std::multimap<Record *, Record *> &Tree,
 
 // Emits and addendum to a .inc file to enumerate the clang declaration
 // contexts.
-void clang::EmitClangDeclContext(RecordKeeper &Records, raw_ostream &OS) {
+void clang::EmitClangDeclContext(const RecordKeeper &Records, raw_ostream &OS) {
   // FIXME: Find a .td file format to allow for this to be represented better.
 
   emitSourceFileHeader("List of AST Decl nodes", OS, Records);
@@ -245,22 +240,15 @@ void clang::EmitClangDeclContext(RecordKeeper &Records, raw_ostream &OS) {
   OS << "#  define DECL_CONTEXT(DECL)\n";
   OS << "#endif\n";
 
-  std::vector<Record *> DeclContextsVector =
-      Records.getAllDerivedDefinitions(DeclContextNodeClassName);
-  std::vector<Record *> Decls =
-      Records.getAllDerivedDefinitions(DeclNodeClassName);
-
-  std::multimap<Record *, Record *> Tree;
-
-  const std::vector<Record *> Stmts =
-      Records.getAllDerivedDefinitions(DeclNodeClassName);
+  std::multimap<const Record *, const Record *> Tree;
 
-  for (auto *R : Stmts) {
+  for (const Record *R : Records.getAllDerivedDefinitions(DeclNodeClassName)) {
     if (auto *B = R->getValueAsOptionalDef(BaseFieldName))
       Tree.insert(std::make_pair(B, R));
   }
 
-  for (auto *DeclContext : DeclContextsVector) {
+  for (const Record *DeclContext :
+       Records.getAllDerivedDefinitions(DeclContextNodeClassName)) {
     printDeclContext(Tree, DeclContext, OS);
   }
 

clang/utils/TableGen/TableGenBackends.h

@@ -24,15 +24,15 @@ class RecordKeeper;
 
 namespace clang {
 
-void EmitClangDeclContext(llvm::RecordKeeper &RK, llvm::raw_ostream &OS);
+void EmitClangDeclContext(const llvm::RecordKeeper &RK, llvm::raw_ostream &OS);
 /**
   @param PriorizeIfSubclassOf These classes should be prioritized in the output.
   This is useful to force enum generation/jump tables/lookup tables to be more
   compact in both size and surrounding code in hot functions. An example use is
   in Decl for classes that inherit from DeclContext, for functions like
   castFromDeclContext.
   */
-void EmitClangASTNodes(llvm::RecordKeeper &RK, llvm::raw_ostream &OS,
+void EmitClangASTNodes(const llvm::RecordKeeper &RK, llvm::raw_ostream &OS,
                        const std::string &N, const std::string &S,
                        std::string_view PriorizeIfSubclassOf = "");
 void EmitClangBasicReader(llvm::RecordKeeper &Records, llvm::raw_ostream &OS);