[MLIR][mlir-link] Add mlir-link tool main entry-point

This commit introduces mlir-link tool suited for mlir module linking. Followup commits will add its logic and more options.

The structure of this tool is similar to mlir-opt and mlir-translate, i.e. the implementation is structured as a library that users can call into to implement entry points that contain the dialects/passes that they are interested in.

Note: This tool is inspired by llvm-link, copying most of its logic to create a generalized solution using MLIR interfaces. This approach was chosen as an effective initial path, with the option to unify it in the future if minimal divergence from llvm-link occurs.

Author: xlauko

mlir/include/mlir/Tools/mlir-link/MlirLinkMain.h

@@ -0,0 +1,31 @@
+//===- MlirLinkMain.h - MLIR Link main --------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Main entry function for mlir-link for when built as standalone binary.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef MLIR_TOOLS_MLIR_LINK_MLIRLINKMAIN_H
+#define MLIR_TOOLS_MLIR_LINK_MLIRLINKMAIN_H
+
+namespace llvm {
+struct LogicalResult;
+} // namespace llvm
+
+namespace mlir {
+class DialectRegistry;
+
+/// Implementation for tools like `mlir-link`.
+/// - registry should contain all the dialects that can be parsed in source IR
+/// passed to the linker.
+llvm::LogicalResult MlirLinkMain(int argc, char **argv,
+                                 DialectRegistry &registry);
+
+} // namespace mlir
+
+#endif // MLIR_TOOLS_MLIR_LINK_MLIRLINKMAIN_H

mlir/lib/Tools/CMakeLists.txt

@@ -1,4 +1,5 @@
 add_subdirectory(lsp-server-support)
+add_subdirectory(mlir-link)
 add_subdirectory(mlir-lsp-server)
 add_subdirectory(mlir-opt)
 add_subdirectory(mlir-pdll-lsp-server)

mlir/lib/Tools/mlir-link/CMakeLists.txt

@@ -0,0 +1,11 @@
+add_mlir_library(MLIRLinkLib
+  MlirLinkMain.cpp
+
+  ADDITIONAL_HEADER_DIRS
+  ${MLIR_MAIN_INCLUDE_DIR}/mlir/Tools/mlir-link
+
+  LINK_LIBS PUBLIC
+  MLIRFunctionInterfaces
+  MLIRIR
+  MLIRParser
+  )

mlir/lib/Tools/mlir-link/MlirLinkMain.cpp

@@ -0,0 +1,40 @@
+//===- MlirLinkMain.cpp - MLIR Link main ----------------------------------===//
+//
+// 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/Tools/mlir-link/MlirLinkMain.h"
+#include "mlir/IR/Dialect.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/InitLLVM.h"
+#include "llvm/Support/WithColor.h"
+
+using namespace mlir;
+using namespace llvm;
+
+LogicalResult mlir::MlirLinkMain(int argc, char **argv,
+                                 DialectRegistry &registry) {
+  static cl::OptionCategory linkCategory("Link options");
+
+  static cl::list<std::string> inputFilenames(cl::Positional, cl::OneOrMore,
+                                              cl::desc("<input mlir files>"),
+                                              cl::cat(linkCategory));
+
+  static cl::opt<std::string> outputFilename(
+      "o", cl::desc("Override output filename"), cl::init("-"),
+      cl::value_desc("filename"), cl::cat(linkCategory));
+
+  static ExitOnError ExitOnErr;
+
+  InitLLVM y(argc, argv);
+  ExitOnErr.setBanner(std::string(argv[0]) + ": ");
+
+  cl::HideUnrelatedOptions({&linkCategory, &getColorCategory()});
+  cl::ParseCommandLineOptions(argc, argv, "mlir linker\n");
+
+  return success();
+}

mlir/tools/CMakeLists.txt

@@ -1,3 +1,4 @@
+add_subdirectory(mlir-link)
 add_subdirectory(mlir-lsp-server)
 add_subdirectory(mlir-opt)
 add_subdirectory(mlir-parser-fuzzer)

mlir/tools/mlir-link/CMakeLists.txt

@@ -0,0 +1,37 @@
+get_property(dialect_libs GLOBAL PROPERTY MLIR_DIALECT_LIBS)
+get_property(conversion_libs GLOBAL PROPERTY MLIR_CONVERSION_LIBS)
+set(LLVM_LINK_COMPONENTS
+  Core
+  Support
+  AsmParser
+  )
+
+if(MLIR_INCLUDE_TESTS)
+  set(test_libs
+    )
+endif()
+
+set(LIBS
+  ${conversion_libs}
+  ${dialect_libs}
+  ${test_libs}
+  MLIRDialect
+  MLIRFuncAllExtensions
+  MLIRIR
+  MLIRLinkLib
+  MLIRSupport
+  MLIRTensorAllExtensions
+  )
+
+add_mlir_tool(mlir-link
+  mlir-link.cpp
+
+  DEPENDS
+  ${LIBS}
+  )
+
+target_link_libraries(mlir-link PRIVATE ${LIBS})
+llvm_update_compile_flags(mlir-link)
+
+mlir_check_all_link_libraries(mlir-link)
+export_executable_symbols_for_plugins(mlir-link)

mlir/tools/mlir-link/mlir-link.cpp

@@ -0,0 +1,28 @@
+//===- mlir-link.cpp - MLIR linker ----------------------------------------===//
+//
+// 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 utility may be invoked in the following manner:
+//  mlir-link a.mlir b.mlir c.mlir -o x.mlir
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/IR/Dialect.h"
+#include "mlir/IR/MLIRContext.h"
+#include "mlir/InitAllDialects.h"
+#include "mlir/InitAllExtensions.h"
+#include "mlir/Tools/mlir-link/MlirLinkMain.h"
+
+using namespace mlir;
+
+int main(int argc, char **argv) {
+    DialectRegistry registry;
+    registerAllDialects(registry);
+    registerAllExtensions(registry);
+
+    return failed(MlirLinkMain(argc, argv, registry));
+}