[mlir][tblgen] Move `GenRegistration` and `GenNameParser` implementations into `TableGen` library

[zero9178]

Summary

These utilities are declared in the header mlir/TableGen/GenInfo.h and mlir/TableGen/GenNameParser.h. Despite this, their implementations are in mlir-tablegen.cpp, making it not possible to use them by simply linking against the MLIRTableGen target.

This patch fixes that by moving the implementations of those classes into a source file part of the MLIRTableGen target. Note that having them both be implemented in the same source file is necessary at this moment due to requiring access to the managed static generatorRegistry.

[mehdi_amini]

What is the use case you want to unblock with this?

[zero9178]

In D131074#3696708, @mehdi_amini wrote:

What is the use case you want to unblock with this?

Being able to use these in downstream TableGen backends. The registration mechanism used here is very convenient.

[mehdi_amini]

Being able to use these in downstream TableGen backends. The registration mechanism used here is very convenient.

OK but I don't think this patch is the best way to achieve this: what about modeling this with what we did with the OptMainLib instead?

[zero9178]

In D131074#3696792, @mehdi_amini wrote:

Being able to use these in downstream TableGen backends. The registration mechanism used here is very convenient.

OK but I don't think this patch is the best way to achieve this: what about modeling this with what we did with the OptMainLib instead?

That's true, this is essentially the bare minimum to run a similar setup.
I've posted https://reviews.llvm.org/D131112 as an alternative with your suggestion implemented.

[zero9178]

Abandoned in favour of https://reviews.llvm.org/D131112

mlir/lib/TableGen/CMakeLists.txt

llvm_add_library(MLIRTableGen STATIC
   Argument.cpp
   Attribute.cpp
   AttrOrTypeDef.cpp
   Builder.cpp
   Class.cpp
   Constraint.cpp
   Dialect.cpp
   Format.cpp
+  GenInfo.cpp
   Interfaces.cpp
   Operator.cpp
   Pass.cpp
   Pattern.cpp
   Predicate.cpp
   Region.cpp
   SideEffects.cpp
   Successor.cpp

mlir/lib/TableGen/GenInfo.cpp

+//===- GenInfo.cpp - Generator info -----------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/TableGen/GenInfo.h"
+
+#include "mlir/TableGen/GenNameParser.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ManagedStatic.h"
+
+using namespace mlir;
+
+static llvm::ManagedStatic<std::vector<GenInfo>> generatorRegistry;
+
+mlir::GenRegistration::GenRegistration(StringRef arg, StringRef description,
+                                       const GenFunction &function) {
+  generatorRegistry->emplace_back(arg, description, function);
+}
+
+GenNameParser::GenNameParser(llvm::cl::Option &opt)
+    : llvm::cl::parser<const GenInfo *>(opt) {
+  for (const auto &kv : *generatorRegistry) {
+    addLiteralOption(kv.getGenArgument(), &kv, kv.getGenDescription());
+  }
+}
+
+void GenNameParser::printOptionInfo(const llvm::cl::Option &o,
+                                    size_t globalWidth) const {
+  GenNameParser *tp = const_cast<GenNameParser *>(this);
+  llvm::array_pod_sort(tp->Values.begin(), tp->Values.end(),
+                       [](const GenNameParser::OptionInfo *vT1,
+                          const GenNameParser::OptionInfo *vT2) {
+                         return vT1->Name.compare(vT2->Name);
+                       });
+  using llvm::cl::parser;
+  parser<const GenInfo *>::printOptionInfo(o, globalWidth);
+}

mlir/tools/mlir-tblgen/mlir-tblgen.cpp

 //===- mlir-tblgen.cpp - Top-Level TableGen implementation for MLIR -------===//
 //
 // 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 contains the main function for MLIR's TableGen.
 //
 //===----------------------------------------------------------------------===//
 
 #include "mlir/TableGen/GenInfo.h"
 #include "mlir/TableGen/GenNameParser.h"
-#include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/InitLLVM.h"
-#include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/TableGen/Error.h"
 #include "llvm/TableGen/Main.h"
 #include "llvm/TableGen/Record.h"
-#include "llvm/TableGen/TableGenBackend.h"
 
 using namespace llvm;
 using namespace mlir;
 
 enum DeprecatedAction { None, Warn, Error };
 llvm::cl::opt<DeprecatedAction> actionOnDeprecated(
     "on-deprecated", llvm::cl::init(Warn),
     llvm::cl::desc("Action to perform on deprecated def"),
     llvm::cl::values(clEnumValN(DeprecatedAction::None, "none", "No action"),
                      clEnumValN(DeprecatedAction::Warn, "warn", "Warn on use"),
                      clEnumValN(DeprecatedAction::Error, "error",
                                 "Error on use")));
 
-static llvm::ManagedStatic<std::vector<GenInfo>> generatorRegistry;
-
-mlir::GenRegistration::GenRegistration(StringRef arg, StringRef description,
-                                       const GenFunction &function) {
-  generatorRegistry->emplace_back(arg, description, function);
-}
-
-GenNameParser::GenNameParser(llvm::cl::Option &opt)
-    : llvm::cl::parser<const GenInfo *>(opt) {
-  for (const auto &kv : *generatorRegistry) {
-    addLiteralOption(kv.getGenArgument(), &kv, kv.getGenDescription());
-  }
-}
-
-void GenNameParser::printOptionInfo(const llvm::cl::Option &o,
-                                    size_t globalWidth) const {
-  GenNameParser *tp = const_cast<GenNameParser *>(this);
-  llvm::array_pod_sort(tp->Values.begin(), tp->Values.end(),
-                       [](const GenNameParser::OptionInfo *vT1,
-                          const GenNameParser::OptionInfo *vT2) {
-                         return vT1->Name.compare(vT2->Name);
-                       });
-  using llvm::cl::parser;
-  parser<const GenInfo *>::printOptionInfo(o, globalWidth);
-}
-
 // Generator that prints records.
 GenRegistration printRecords("print-records", "Print all records to stdout",
                              [](const RecordKeeper &records, raw_ostream &os) {
                                os << records;
                                return false;
                              });
 
 // Generator to invoke.