[flang][fir] Add fir-opt tool

This patch introduce the fir-opt tool. Similar to mlir-opt for FIR.
It will be used in following patches to test fir opt and round-trip.

Reviewed By: schweitz, mehdi_amini

Differential Revision: https://reviews.llvm.org/D96535

Author: clementval

flang/test/CMakeLists.txt

@@ -34,7 +34,7 @@ set(FLANG_TEST_PARAMS
   flang_site_config=${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg.py)
 
 set(FLANG_TEST_DEPENDS
-  f18 FileCheck count not module_files
+  f18 FileCheck count not module_files fir-opt
 )
 
 list(APPEND FLANG_TEST_DEPENDS tco)

flang/test/Fir/fir-ops.fir

@@ -1,6 +1,6 @@
 // Test the FIR operations
-
-// RUN: tco -emit-fir %s | tco -emit-fir | FileCheck %s
+// Parse operations and check that we can reparse what we print.
+// RUN: fir-opt %s | fir-opt | FileCheck %s
 
 // CHECK-LABEL: func private @it1() -> !fir.int<4>
 // CHECK: func private @box1() -> !fir.boxchar<2>

flang/test/Fir/fir-types.fir

@@ -1,6 +1,6 @@
 // Test the FIR types
-
-// RUN: tco -emit-fir %s | tco -emit-fir | FileCheck %s
+// Parse types and check that we can reparse what we print.
+// RUN: fir-opt %s | fir-opt | FileCheck %s
 
 // Fortran Intrinsic types
 // CHECK-LABEL: func private @it1() -> !fir.int<4>

flang/tools/CMakeLists.txt

@@ -12,3 +12,4 @@ if(FLANG_BUILD_NEW_DRIVER)
 endif()
 add_subdirectory(tco)
 add_subdirectory(f18-parse-demo)
+add_subdirectory(fir-opt)

flang/tools/fir-opt/CMakeLists.txt

@@ -0,0 +1,13 @@
+add_flang_tool(fir-opt fir-opt.cpp)
+llvm_update_compile_flags(fir-opt)
+get_property(dialect_libs GLOBAL PROPERTY MLIR_DIALECT_LIBS)
+
+target_link_libraries(fir-opt PRIVATE
+  FIROptimizer
+  ${dialect_libs}
+
+  # TODO: these should be transitive dependencies from a target providing
+  # "registerFIRPasses()"
+  MLIRAffineToStandard
+  MLIROptLib
+)

flang/tools/fir-opt/fir-opt.cpp

@@ -0,0 +1,25 @@
+//===- fir-opt.cpp - FIR Optimizer Driver -----------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This is to be like LLVM's opt program, only for FIR.  Such a program is
+// required for roundtrip testing, etc.
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Support/MlirOptMain.h"
+#include "flang/Optimizer/Support/InitFIR.h"
+
+using namespace mlir;
+
+int main(int argc, char **argv) {
+  fir::support::registerFIRPasses();
+  DialectRegistry registry;
+  fir::support::registerDialects(registry);
+  return failed(MlirOptMain(argc, argv, "FIR modular optimizer driver\n",
+      registry, /*preloadDialectsInContext*/ false));
+}