[Mlir-commits] [llvm] [mlir] [NFC][TableGen] Migrate IfDef/Namespace emitter from MLIR to LLVM (PR #161744)

Rahul Joshi llvmlistbot at llvm.org
Fri Oct 3 12:30:27 PDT 2025


https://github.com/jurahul updated https://github.com/llvm/llvm-project/pull/161744

>From 3f343bbd0ddf728e4dfc868c2b6cf3ec49659117 Mon Sep 17 00:00:00 2001
From: Rahul Joshi <rjoshi at nvidia.com>
Date: Thu, 2 Oct 2025 11:02:07 -0700
Subject: [PATCH 1/2] [NFC][TableGen] Migrate IfDef/Namespace emitter from MLIR
 to LLVM

Migrate IfDef and Namespace emitters from MLIR to LLVM TableGen.
Introduce a `DialectNamespaceEmitter` for MLIR specific use, and
do a minimal adoption these emitters in LLVM TableGen.

Eliminate duplicated version of IfDef emitter in DirectiveEmitter.
---
 llvm/include/llvm/TableGen/CodeGenHelpers.h   | 63 +++++++++++++++++++
 .../utils/TableGen/Basic/DirectiveEmitter.cpp | 56 +++++------------
 .../TableGen/Basic/TargetFeaturesEmitter.cpp  | 36 +++++------
 mlir/include/mlir/TableGen/CodeGenHelpers.h   | 42 +++----------
 mlir/include/mlir/TableGen/Dialect.h          |  1 +
 mlir/lib/TableGen/CodeGenHelpers.cpp          |  1 +
 mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp   | 20 +++---
 mlir/tools/mlir-tblgen/DialectGen.cpp         |  4 +-
 mlir/tools/mlir-tblgen/OmpOpGen.cpp           |  2 +-
 mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp   | 11 ++--
 mlir/tools/mlir-tblgen/SPIRVUtilsGen.cpp      |  3 +-
 11 files changed, 124 insertions(+), 115 deletions(-)
 create mode 100644 llvm/include/llvm/TableGen/CodeGenHelpers.h

diff --git a/llvm/include/llvm/TableGen/CodeGenHelpers.h b/llvm/include/llvm/TableGen/CodeGenHelpers.h
new file mode 100644
index 0000000000000..2a9ae8b4e995d
--- /dev/null
+++ b/llvm/include/llvm/TableGen/CodeGenHelpers.h
@@ -0,0 +1,63 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines common utilities for generating C++ code.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TABLEGEN_CODEGENHELPERS_H
+#define LLVM_TABLEGEN_CODEGENHELPERS_H
+
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/raw_ostream.h"
+#include <string>
+
+namespace llvm {
+// Simple RAII helper for emitting ifdef-undef-endif scope.
+class IfDefEmitter {
+public:
+  IfDefEmitter(raw_ostream &OS, StringRef Name) : Name(Name.str()), OS(OS) {
+    OS << "#ifdef " << Name << "\n"
+       << "#undef " << Name << "\n\n";
+  }
+  ~IfDefEmitter() { OS << "\n#endif // " << Name << "\n\n"; }
+
+private:
+  std::string Name;
+  raw_ostream &OS;
+};
+
+// Simple RAII helper for emitting namespace scope. Name can be a single
+// namespace (empty for anonymous namespace) or nested namespace.
+class NamespaceEmitter {
+public:
+  NamespaceEmitter(raw_ostream &OS, StringRef Name) : OS(OS) {
+    emitNamespaceStarts(Name);
+  }
+
+  ~NamespaceEmitter() {
+    for (StringRef NS : llvm::reverse(Namespaces))
+      OS << "} // namespace " << NS << "\n";
+  }
+
+private:
+  void emitNamespaceStarts(StringRef Name) {
+    llvm::SplitString(Name, Namespaces, "::");
+    for (StringRef NS : Namespaces)
+      OS << "namespace " << NS << " {\n";
+  }
+
+  SmallVector<StringRef, 2> Namespaces;
+  raw_ostream &OS;
+};
+
+} // end namespace llvm
+
+#endif // LLVM_TABLEGEN_CODEGENHELPERS_H
diff --git a/llvm/utils/TableGen/Basic/DirectiveEmitter.cpp b/llvm/utils/TableGen/Basic/DirectiveEmitter.cpp
index f0e23690367db..f99c1797428fe 100644
--- a/llvm/utils/TableGen/Basic/DirectiveEmitter.cpp
+++ b/llvm/utils/TableGen/Basic/DirectiveEmitter.cpp
@@ -19,6 +19,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/TableGen/CodeGenHelpers.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Record.h"
 #include "llvm/TableGen/TableGenBackend.h"
@@ -29,27 +30,11 @@
 
 using namespace llvm;
 
-namespace {
-// Simple RAII helper for defining ifdef-undef-endif scopes.
-class IfDefScope {
-public:
-  IfDefScope(StringRef Name, raw_ostream &OS) : Name(Name), OS(OS) {
-    OS << "#ifdef " << Name << "\n"
-       << "#undef " << Name << "\n";
-  }
-
-  ~IfDefScope() { OS << "\n#endif // " << Name << "\n\n"; }
-
-private:
-  StringRef Name;
-  raw_ostream &OS;
-};
-} // namespace
-
 namespace {
 enum class Frontend { LLVM, Flang, Clang };
+} // namespace
 
-StringRef getFESpelling(Frontend FE) {
+static StringRef getFESpelling(Frontend FE) {
   switch (FE) {
   case Frontend::LLVM:
     return "llvm";
@@ -60,7 +45,6 @@ StringRef getFESpelling(Frontend FE) {
   }
   llvm_unreachable("unknown FE kind");
 }
-} // namespace
 
 // Get the full namespace qualifier for the directive language.
 static std::string getQualifier(const DirectiveLanguage &DirLang,
@@ -971,11 +955,10 @@ static void generateDirectiveClauseSets(const DirectiveLanguage &DirLang,
   std::string IfDefName{"GEN_"};
   IfDefName += getFESpelling(FE).upper();
   IfDefName += "_DIRECTIVE_CLAUSE_SETS";
-  IfDefScope Scope(IfDefName, OS);
+  IfDefEmitter Scope(OS, IfDefName);
 
   StringRef Namespace =
       getFESpelling(FE == Frontend::Flang ? Frontend::LLVM : FE);
-  OS << "\n";
   // The namespace has to be different for clang vs flang, as 2 structs with the
   // same name but different layout is UB.  So just put the 'clang' on in the
   // clang namespace.
@@ -1016,9 +999,8 @@ static void generateDirectiveClauseMap(const DirectiveLanguage &DirLang,
   std::string IfDefName{"GEN_"};
   IfDefName += getFESpelling(FE).upper();
   IfDefName += "_DIRECTIVE_CLAUSE_MAP";
-  IfDefScope Scope(IfDefName, OS);
+  IfDefEmitter Scope(OS, IfDefName);
 
-  OS << "\n";
   OS << "{\n";
 
   // The namespace has to be different for clang vs flang, as 2 structs with the
@@ -1062,9 +1044,7 @@ static void generateDirectiveClauseMap(const DirectiveLanguage &DirLang,
 static void generateFlangClauseParserClass(const DirectiveLanguage &DirLang,
                                            raw_ostream &OS) {
 
-  IfDefScope Scope("GEN_FLANG_CLAUSE_PARSER_CLASSES", OS);
-
-  OS << "\n";
+  IfDefEmitter Scope(OS, "GEN_FLANG_CLAUSE_PARSER_CLASSES");
 
   for (const Clause Clause : DirLang.getClauses()) {
     if (!Clause.getFlangClass().empty()) {
@@ -1089,9 +1069,8 @@ static void generateFlangClauseParserClass(const DirectiveLanguage &DirLang,
 static void generateFlangClauseParserClassList(const DirectiveLanguage &DirLang,
                                                raw_ostream &OS) {
 
-  IfDefScope Scope("GEN_FLANG_CLAUSE_PARSER_CLASSES_LIST", OS);
+  IfDefEmitter Scope(OS, "GEN_FLANG_CLAUSE_PARSER_CLASSES_LIST");
 
-  OS << "\n";
   interleaveComma(DirLang.getClauses(), OS, [&](const Record *C) {
     Clause Clause(C);
     OS << Clause.getFormattedParserClassName() << "\n";
@@ -1102,9 +1081,8 @@ static void generateFlangClauseParserClassList(const DirectiveLanguage &DirLang,
 static void generateFlangClauseDump(const DirectiveLanguage &DirLang,
                                     raw_ostream &OS) {
 
-  IfDefScope Scope("GEN_FLANG_DUMP_PARSE_TREE_CLAUSES", OS);
+  IfDefEmitter Scope(OS, "GEN_FLANG_DUMP_PARSE_TREE_CLAUSES");
 
-  OS << "\n";
   for (const Clause Clause : DirLang.getClauses()) {
     OS << "NODE(" << DirLang.getFlangClauseBaseClass() << ", "
        << Clause.getFormattedParserClassName() << ")\n";
@@ -1116,10 +1094,9 @@ static void generateFlangClauseDump(const DirectiveLanguage &DirLang,
 static void generateFlangClauseUnparse(const DirectiveLanguage &DirLang,
                                        raw_ostream &OS) {
 
-  IfDefScope Scope("GEN_FLANG_CLAUSE_UNPARSE", OS);
+  IfDefEmitter Scope(OS, "GEN_FLANG_CLAUSE_UNPARSE");
 
   StringRef Base = DirLang.getFlangClauseBaseClass();
-  OS << "\n";
 
   for (const Clause Clause : DirLang.getClauses()) {
     if (Clause.skipFlangUnparser())
@@ -1172,9 +1149,8 @@ static void generateFlangClauseUnparse(const DirectiveLanguage &DirLang,
 static void generateFlangClauseCheckPrototypes(const DirectiveLanguage &DirLang,
                                                raw_ostream &OS) {
 
-  IfDefScope Scope("GEN_FLANG_CLAUSE_CHECK_ENTER", OS);
+  IfDefEmitter Scope(OS, "GEN_FLANG_CLAUSE_CHECK_ENTER");
 
-  OS << "\n";
   for (const Clause Clause : DirLang.getClauses()) {
     OS << "void Enter(const parser::" << DirLang.getFlangClauseBaseClass()
        << "::" << Clause.getFormattedParserClassName() << " &);\n";
@@ -1186,12 +1162,11 @@ static void generateFlangClauseCheckPrototypes(const DirectiveLanguage &DirLang,
 static void generateFlangClauseParserKindMap(const DirectiveLanguage &DirLang,
                                              raw_ostream &OS) {
 
-  IfDefScope Scope("GEN_FLANG_CLAUSE_PARSER_KIND_MAP", OS);
+  IfDefEmitter Scope(OS, "GEN_FLANG_CLAUSE_PARSER_KIND_MAP");
 
   StringRef Prefix = DirLang.getClausePrefix();
   std::string Qual = getQualifier(DirLang);
 
-  OS << "\n";
   for (const Record *R : DirLang.getClauses()) {
     Clause C(R);
     OS << "if constexpr (std::is_same_v<A, parser::"
@@ -1216,11 +1191,10 @@ static void generateFlangClausesParser(const DirectiveLanguage &DirLang,
   llvm::sort(Names, [](const auto &A, const auto &B) {
     return A.second.Name > B.second.Name;
   });
-  IfDefScope Scope("GEN_FLANG_CLAUSES_PARSER", OS);
+  IfDefEmitter Scope(OS, "GEN_FLANG_CLAUSES_PARSER");
   StringRef Base = DirLang.getFlangClauseBaseClass();
 
   unsigned LastIndex = Names.size() - 1;
-  OS << "\n";
   OS << "TYPE_PARSER(\n";
   for (auto [Index, RecSp] : llvm::enumerate(Names)) {
     auto [R, S] = RecSp;
@@ -1313,10 +1287,9 @@ static void emitDirectivesFlangImpl(const DirectiveLanguage &DirLang,
 static void generateClauseClassMacro(const DirectiveLanguage &DirLang,
                                      raw_ostream &OS) {
   // Generate macros style information for legacy code in clang
-  IfDefScope Scope("GEN_CLANG_CLAUSE_CLASS", OS);
+  IfDefEmitter Scope(OS, "GEN_CLANG_CLAUSE_CLASS");
 
   StringRef Prefix = DirLang.getClausePrefix();
-  OS << "\n";
 
   OS << "#ifndef CLAUSE\n";
   OS << "#define CLAUSE(Enum, Str, Implicit)\n";
@@ -1375,12 +1348,11 @@ static void generateClauseClassMacro(const DirectiveLanguage &DirLang,
 // language. This code can be included in library.
 void emitDirectivesBasicImpl(const DirectiveLanguage &DirLang,
                              raw_ostream &OS) {
-  IfDefScope Scope("GEN_DIRECTIVES_IMPL", OS);
+  IfDefEmitter Scope(OS, "GEN_DIRECTIVES_IMPL");
 
   StringRef DPrefix = DirLang.getDirectivePrefix();
   StringRef CPrefix = DirLang.getClausePrefix();
 
-  OS << "\n";
   OS << "#include \"llvm/Frontend/Directive/Spelling.h\"\n";
   OS << "#include \"llvm/Support/ErrorHandling.h\"\n";
   OS << "#include <utility>\n";
diff --git a/llvm/utils/TableGen/Basic/TargetFeaturesEmitter.cpp b/llvm/utils/TableGen/Basic/TargetFeaturesEmitter.cpp
index 6b723bc0fb02d..e2b524155a72c 100644
--- a/llvm/utils/TableGen/Basic/TargetFeaturesEmitter.cpp
+++ b/llvm/utils/TableGen/Basic/TargetFeaturesEmitter.cpp
@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "TargetFeaturesEmitter.h"
+#include "llvm/TableGen/CodeGenHelpers.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/TableGenBackend.h"
 #include "llvm/TargetParser/SubtargetFeature.h"
@@ -43,7 +44,7 @@ FeatureMapTy TargetFeaturesEmitter::enumeration(raw_ostream &OS) {
     PrintFatalError(
         "Too many subtarget features! Bump MAX_SUBTARGET_FEATURES.");
 
-  OS << "namespace " << Target << " {\n";
+  NamespaceEmitter NS(OS, Target);
 
   OS << "enum {\n";
 
@@ -58,9 +59,8 @@ FeatureMapTy TargetFeaturesEmitter::enumeration(raw_ostream &OS) {
 
   OS << "  " << "NumSubtargetFeatures = " << N << "\n";
 
-  // Close enumeration and namespace
+  // Close enumeration.
   OS << "};\n";
-  OS << "} // end namespace " << Target << "\n";
   return FeatureMap;
 }
 
@@ -149,25 +149,23 @@ void TargetFeaturesEmitter::printCPUKeyValues(raw_ostream &OS,
 void TargetFeaturesEmitter::run(raw_ostream &OS) {
   OS << "// Autogenerated by TargetFeatureEmitter.cpp\n\n";
 
-  OS << "\n#ifdef GET_SUBTARGETFEATURES_ENUM\n";
-  OS << "#undef GET_SUBTARGETFEATURES_ENUM\n\n";
-
-  OS << "namespace llvm {\n";
-  auto FeatureMap = enumeration(OS);
-  OS << "} // end namespace llvm\n\n";
-  OS << "#endif // GET_SUBTARGETFEATURES_ENUM\n\n";
+  FeatureMapTy FeatureMap;
+  {
+    IfDefEmitter IfDef(OS, "GET_SUBTARGETFEATURES_ENUM");
+    NamespaceEmitter NS(OS, "llvm");
+    FeatureMap = enumeration(OS);
+  }
 
-  OS << "\n#ifdef GET_SUBTARGETFEATURES_KV\n";
-  OS << "#undef GET_SUBTARGETFEATURES_KV\n\n";
+  {
+    IfDefEmitter IfDef(OS, "GET_SUBTARGETFEATURES_KV");
+    NamespaceEmitter NS(OS, "llvm");
 
-  OS << "namespace llvm {\n";
-  printFeatureKeyValues(OS, FeatureMap);
-  OS << "\n";
+    printFeatureKeyValues(OS, FeatureMap);
+    OS << "\n";
 
-  printCPUKeyValues(OS, FeatureMap);
-  OS << "\n";
-  OS << "} // end namespace llvm\n\n";
-  OS << "#endif // GET_SUBTARGETFEATURES_KV\n\n";
+    printCPUKeyValues(OS, FeatureMap);
+    OS << "\n";
+  }
 }
 
 static TableGen::Emitter::OptClass<TargetFeaturesEmitter>
diff --git a/mlir/include/mlir/TableGen/CodeGenHelpers.h b/mlir/include/mlir/TableGen/CodeGenHelpers.h
index cf14f65b93ed2..252da21419b6e 100644
--- a/mlir/include/mlir/TableGen/CodeGenHelpers.h
+++ b/mlir/include/mlir/TableGen/CodeGenHelpers.h
@@ -1,3 +1,4 @@
+//===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -20,6 +21,8 @@
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/TableGen/CodeGenHelpers.h"
+#include <utility>
 
 namespace llvm {
 class RecordKeeper;
@@ -36,46 +39,17 @@ std::string strfmt(const char *fmt, Parameters &&...parameters) {
   return llvm::formatv(fmt, std::forward<Parameters>(parameters)...).str();
 }
 
-// Simple RAII helper for defining ifdef-undef-endif scopes.
-class IfDefScope {
-public:
-  IfDefScope(llvm::StringRef name, llvm::raw_ostream &os)
-      : name(name.str()), os(os) {
-    os << "#ifdef " << name << "\n"
-       << "#undef " << name << "\n\n";
-  }
-  ~IfDefScope() { os << "\n#endif  // " << name << "\n\n"; }
-
-private:
-  std::string name;
-  llvm::raw_ostream &os;
-};
-
-// A helper RAII class to emit nested namespaces for this op.
-class NamespaceEmitter {
+// A helper RAII class to emit nested namespaces for a dialect.
+class DialectNamespaceEmitter {
 public:
-  NamespaceEmitter(raw_ostream &os, const Dialect &dialect) : os(os) {
+  DialectNamespaceEmitter(raw_ostream &os, const Dialect &dialect) {
     if (!dialect)
       return;
-    emitNamespaceStarts(os, dialect.getCppNamespace());
-  }
-  NamespaceEmitter(raw_ostream &os, StringRef cppNamespace) : os(os) {
-    emitNamespaceStarts(os, cppNamespace);
-  }
-
-  ~NamespaceEmitter() {
-    for (StringRef ns : llvm::reverse(namespaces))
-      os << "} // namespace " << ns << "\n";
+    nsEmitter.emplace(os, dialect.getCppNamespace());
   }
 
 private:
-  void emitNamespaceStarts(raw_ostream &os, StringRef cppNamespace) {
-    llvm::SplitString(cppNamespace, namespaces, "::");
-    for (StringRef ns : namespaces)
-      os << "namespace " << ns << " {\n";
-  }
-  raw_ostream &os;
-  SmallVector<StringRef, 2> namespaces;
+  std::optional<llvm::NamespaceEmitter> nsEmitter;
 };
 
 /// This class deduplicates shared operation verification code by emitting
diff --git a/mlir/include/mlir/TableGen/Dialect.h b/mlir/include/mlir/TableGen/Dialect.h
index ea8f40555e445..37c6427a9282a 100644
--- a/mlir/include/mlir/TableGen/Dialect.h
+++ b/mlir/include/mlir/TableGen/Dialect.h
@@ -107,6 +107,7 @@ class Dialect {
 
   // Returns whether the dialect is defined.
   explicit operator bool() const { return def != nullptr; }
+  bool isDefined() const { return def != nullptr; }
 
 private:
   const llvm::Record *def;
diff --git a/mlir/lib/TableGen/CodeGenHelpers.cpp b/mlir/lib/TableGen/CodeGenHelpers.cpp
index 2c119fd680b69..cb90ef82c1c39 100644
--- a/mlir/lib/TableGen/CodeGenHelpers.cpp
+++ b/mlir/lib/TableGen/CodeGenHelpers.cpp
@@ -16,6 +16,7 @@
 #include "mlir/TableGen/Pattern.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/Path.h"
+#include "llvm/TableGen/CodeGenHelpers.h"
 #include "llvm/TableGen/Record.h"
 
 using namespace llvm;
diff --git a/mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp b/mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp
index b9115657d6bf3..06ef396b9b21d 100644
--- a/mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp
+++ b/mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp
@@ -10,12 +10,12 @@
 #include "CppGenUtilities.h"
 #include "mlir/TableGen/AttrOrTypeDef.h"
 #include "mlir/TableGen/Class.h"
-#include "mlir/TableGen/CodeGenHelpers.h"
 #include "mlir/TableGen/Format.h"
 #include "mlir/TableGen/GenInfo.h"
 #include "mlir/TableGen/Interfaces.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/TableGen/CodeGenHelpers.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/TableGenBackend.h"
 
@@ -71,14 +71,14 @@ class DefGen {
 
   void emitDecl(raw_ostream &os) const {
     if (storageCls && def.genStorageClass()) {
-      NamespaceEmitter ns(os, def.getStorageNamespace());
+      llvm::NamespaceEmitter ns(os, def.getStorageNamespace());
       os << "struct " << def.getStorageClassName() << ";\n";
     }
     defCls.writeDeclTo(os);
   }
   void emitDef(raw_ostream &os) const {
     if (storageCls && def.genStorageClass()) {
-      NamespaceEmitter ns(os, def.getStorageNamespace());
+      llvm::NamespaceEmitter ns(os, def.getStorageNamespace());
       storageCls->writeDeclTo(os); // everything is inline
     }
     defCls.writeDefTo(os);
@@ -850,7 +850,7 @@ class AsmPrinter;
 
 bool DefGenerator::emitDecls(StringRef selectedDialect) {
   emitSourceFileHeader((defType + "Def Declarations").str(), os);
-  IfDefScope scope("GET_" + defType.upper() + "DEF_CLASSES", os);
+  llvm::IfDefEmitter scope(os, "GET_" + defType.upper() + "DEF_CLASSES");
 
   // Output the common "header".
   os << typeDefDeclHeader;
@@ -860,7 +860,7 @@ bool DefGenerator::emitDecls(StringRef selectedDialect) {
   if (defs.empty())
     return false;
   {
-    NamespaceEmitter nsEmitter(os, defs.front().getDialect());
+    DialectNamespaceEmitter nsEmitter(os, defs.front().getDialect());
 
     // Declare all the def classes first (in case they reference each other).
     for (const AttrOrTypeDef &def : defs) {
@@ -892,7 +892,7 @@ bool DefGenerator::emitDecls(StringRef selectedDialect) {
 //===----------------------------------------------------------------------===//
 
 void DefGenerator::emitTypeDefList(ArrayRef<AttrOrTypeDef> defs) {
-  IfDefScope scope("GET_" + defType.upper() + "DEF_LIST", os);
+  llvm::IfDefEmitter scope(os, "GET_" + defType.upper() + "DEF_LIST");
   auto interleaveFn = [&](const AttrOrTypeDef &def) {
     os << def.getDialect().getCppNamespace() << "::" << def.getCppClassName();
   };
@@ -1083,11 +1083,11 @@ bool DefGenerator::emitDefs(StringRef selectedDialect) {
     return false;
   emitTypeDefList(defs);
 
-  IfDefScope scope("GET_" + defType.upper() + "DEF_CLASSES", os);
+  llvm::IfDefEmitter scope(os, "GET_" + defType.upper() + "DEF_CLASSES");
   emitParsePrintDispatch(defs);
   for (const AttrOrTypeDef &def : defs) {
     {
-      NamespaceEmitter ns(os, def.getDialect());
+      DialectNamespaceEmitter ns(os, def.getDialect());
       DefGen gen(def);
       gen.emitDef(os);
     }
@@ -1102,7 +1102,7 @@ bool DefGenerator::emitDefs(StringRef selectedDialect) {
 
   // Emit the default parser/printer for Attributes if the dialect asked for it.
   if (isAttrGenerator && firstDialect.useDefaultAttributePrinterParser()) {
-    NamespaceEmitter nsEmitter(os, firstDialect);
+    DialectNamespaceEmitter nsEmitter(os, firstDialect);
     if (firstDialect.isExtensible()) {
       os << llvm::formatv(dialectDefaultAttrPrinterParserDispatch,
                           firstDialect.getCppClassName(),
@@ -1116,7 +1116,7 @@ bool DefGenerator::emitDefs(StringRef selectedDialect) {
 
   // Emit the default parser/printer for Types if the dialect asked for it.
   if (!isAttrGenerator && firstDialect.useDefaultTypePrinterParser()) {
-    NamespaceEmitter nsEmitter(os, firstDialect);
+    DialectNamespaceEmitter nsEmitter(os, firstDialect);
     if (firstDialect.isExtensible()) {
       os << llvm::formatv(dialectDefaultTypePrinterParserDispatch,
                           firstDialect.getCppClassName(),
diff --git a/mlir/tools/mlir-tblgen/DialectGen.cpp b/mlir/tools/mlir-tblgen/DialectGen.cpp
index 02941ec1268cb..2e8810d5d37f4 100644
--- a/mlir/tools/mlir-tblgen/DialectGen.cpp
+++ b/mlir/tools/mlir-tblgen/DialectGen.cpp
@@ -242,7 +242,7 @@ static const char *const discardableAttrHelperDecl = R"(
 static void emitDialectDecl(Dialect &dialect, raw_ostream &os) {
   // Emit all nested namespaces.
   {
-    NamespaceEmitter nsEmitter(os, dialect);
+    DialectNamespaceEmitter nsEmitter(os, dialect);
 
     // Emit the start of the decl.
     std::string cppName = dialect.getCppClassName();
@@ -358,7 +358,7 @@ static void emitDialectDef(Dialect &dialect, const RecordKeeper &records,
        << "::" << cppClassName << ")\n";
 
   // Emit all nested namespaces.
-  NamespaceEmitter nsEmitter(os, dialect);
+  DialectNamespaceEmitter nsEmitter(os, dialect);
 
   /// Build the list of dependent dialects.
   std::string dependentDialectRegistrations;
diff --git a/mlir/tools/mlir-tblgen/OmpOpGen.cpp b/mlir/tools/mlir-tblgen/OmpOpGen.cpp
index 91bc61bcdbb67..e1be11a0d92ed 100644
--- a/mlir/tools/mlir-tblgen/OmpOpGen.cpp
+++ b/mlir/tools/mlir-tblgen/OmpOpGen.cpp
@@ -342,7 +342,7 @@ static bool verifyDecls(const RecordKeeper &records, raw_ostream &) {
 /// structures according to the `clauses` argument of each definition deriving
 /// from `OpenMP_Op`.
 static bool genClauseOps(const RecordKeeper &records, raw_ostream &os) {
-  mlir::tblgen::NamespaceEmitter ns(os, "mlir::omp");
+  llvm::NamespaceEmitter ns(os, "mlir::omp");
   for (const Record *clause : records.getAllDerivedDefinitions("OpenMP_Clause"))
     genClauseOpsStruct(clause, os);
 
diff --git a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
index 7e8e559baf878..c3420d433523a 100644
--- a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
+++ b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
@@ -36,6 +36,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/TableGen/CodeGenHelpers.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Record.h"
 #include "llvm/TableGen/TableGenBackend.h"
@@ -4855,7 +4856,7 @@ static void emitOpClassDecls(const RecordKeeper &records,
   }
 
   // Emit the op class declarations.
-  IfDefScope scope("GET_OP_CLASSES", os);
+  IfDefEmitter scope(os, "GET_OP_CLASSES");
   if (defs.empty())
     return;
   StaticVerifierFunctionEmitter staticVerifierEmitter(os, records);
@@ -4898,7 +4899,7 @@ static bool emitOpDecls(const RecordKeeper &records, raw_ostream &os) {
     return false;
 
   Dialect dialect = Operator(defs.front()).getDialect();
-  NamespaceEmitter ns(os, dialect);
+  DialectNamespaceEmitter ns(os, dialect);
 
   const char *const opRegistrationHook =
       "void register{0}Operations{1}({2}::{0} *dialect);\n";
@@ -4921,7 +4922,7 @@ static void emitOpDefShard(const RecordKeeper &records,
   std::string shardGuard = "GET_OP_DEFS_";
   std::string indexStr = std::to_string(shardIndex);
   shardGuard += indexStr;
-  IfDefScope scope(shardGuard, os);
+  IfDefEmitter scope(os, shardGuard);
 
   // Emit the op registration hook in the first shard.
   const char *const opRegistrationHook =
@@ -4962,14 +4963,14 @@ static bool emitOpDefs(const RecordKeeper &records, raw_ostream &os) {
   // If no shard was requested, emit the regular op list and class definitions.
   if (shardedDefs.size() == 1) {
     {
-      IfDefScope scope("GET_OP_LIST", os);
+      IfDefEmitter scope(os, "GET_OP_LIST");
       interleave(
           defs, os,
           [&](const Record *def) { os << Operator(def).getQualCppClassName(); },
           ",\n");
     }
     {
-      IfDefScope scope("GET_OP_CLASSES", os);
+      IfDefEmitter scope(os, "GET_OP_CLASSES");
       emitOpClassDefs(records, defs, os);
     }
     return false;
diff --git a/mlir/tools/mlir-tblgen/SPIRVUtilsGen.cpp b/mlir/tools/mlir-tblgen/SPIRVUtilsGen.cpp
index 41ffdfcbde945..3ead2f0e37214 100644
--- a/mlir/tools/mlir-tblgen/SPIRVUtilsGen.cpp
+++ b/mlir/tools/mlir-tblgen/SPIRVUtilsGen.cpp
@@ -50,7 +50,6 @@ using mlir::tblgen::EnumCase;
 using mlir::tblgen::EnumInfo;
 using mlir::tblgen::NamedAttribute;
 using mlir::tblgen::NamedTypeConstraint;
-using mlir::tblgen::NamespaceEmitter;
 using mlir::tblgen::Operator;
 
 //===----------------------------------------------------------------------===//
@@ -261,7 +260,7 @@ static void emitInterfaceDecl(const Availability &availability,
       std::string(formatv("{0}Traits", interfaceName));
 
   StringRef cppNamespace = availability.getInterfaceClassNamespace();
-  NamespaceEmitter nsEmitter(os, cppNamespace);
+  llvm::NamespaceEmitter nsEmitter(os, cppNamespace);
   os << "class " << interfaceName << ";\n\n";
 
   // Emit the traits struct containing the concept and model declarations.

>From 23bf93f29b17fcb1a6738cd7e3c20f485dd40ddd Mon Sep 17 00:00:00 2001
From: Rahul Joshi <rjoshi at nvidia.com>
Date: Fri, 3 Oct 2025 12:29:42 -0700
Subject: [PATCH 2/2] Use NamespaceEmitter in DirectiveEmitter

---
 llvm/include/llvm/TableGen/CodeGenHelpers.h    |  6 +++++-
 llvm/utils/TableGen/Basic/DirectiveEmitter.cpp | 17 ++++-------------
 2 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/llvm/include/llvm/TableGen/CodeGenHelpers.h b/llvm/include/llvm/TableGen/CodeGenHelpers.h
index 2a9ae8b4e995d..7dca6a051ba75 100644
--- a/llvm/include/llvm/TableGen/CodeGenHelpers.h
+++ b/llvm/include/llvm/TableGen/CodeGenHelpers.h
@@ -42,9 +42,13 @@ class NamespaceEmitter {
     emitNamespaceStarts(Name);
   }
 
-  ~NamespaceEmitter() {
+  ~NamespaceEmitter() { close(); }
+
+  // Explicit function to close the namespace scopes.
+  void close() {
     for (StringRef NS : llvm::reverse(Namespaces))
       OS << "} // namespace " << NS << "\n";
+    Namespaces.clear();
   }
 
 private:
diff --git a/llvm/utils/TableGen/Basic/DirectiveEmitter.cpp b/llvm/utils/TableGen/Basic/DirectiveEmitter.cpp
index f99c1797428fe..b4d816ea211f7 100644
--- a/llvm/utils/TableGen/Basic/DirectiveEmitter.cpp
+++ b/llvm/utils/TableGen/Basic/DirectiveEmitter.cpp
@@ -281,13 +281,8 @@ static void emitDirectivesDecl(const RecordKeeper &Records, raw_ostream &OS) {
   OS << "#include <cstddef>\n"; // for size_t
   OS << "#include <utility>\n"; // for std::pair
   OS << "\n";
-  OS << "namespace llvm {\n";
-
-  // Open namespaces defined in the directive language
-  SmallVector<StringRef, 2> Namespaces;
-  SplitString(DirLang.getCppNamespace(), Namespaces, "::");
-  for (auto Ns : Namespaces)
-    OS << "namespace " << Ns << " {\n";
+  NamespaceEmitter LlvmNS(OS, "llvm");
+  NamespaceEmitter DirLangNS(OS, DirLang.getCppNamespace());
 
   if (DirLang.hasEnableBitmaskEnumInNamespace())
     OS << "\nLLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();\n";
@@ -364,9 +359,7 @@ static void emitDirectivesDecl(const RecordKeeper &Records, raw_ostream &OS) {
     OS << "\n";
   }
 
-  // Closing namespaces
-  for (auto Ns : reverse(Namespaces))
-    OS << "} // namespace " << Ns << "\n";
+  DirLangNS.close();
 
   // These specializations need to be in ::llvm.
   for (StringRef Enum : {"Association", "Category", "Directive", "Clause"}) {
@@ -376,9 +369,7 @@ static void emitDirectivesDecl(const RecordKeeper &Records, raw_ostream &OS) {
     OS << "  static constexpr bool is_iterable = true;\n";
     OS << "};\n";
   }
-
-  OS << "} // namespace llvm\n";
-
+  LlvmNS.close();
   OS << "#endif // LLVM_" << Lang << "_INC\n";
 }
 



More information about the Mlir-commits mailing list