feat: Set up the MLIR dialect

Add CXX_ENABLE_MLIR option to enable building
the MLIR dialect.

Signed-off-by: Roberto Raggi <[email protected]>

Author: robertoraggi

CMakeLists.txt

@@ -40,6 +40,7 @@ file(READ "${CMAKE_CURRENT_SOURCE_DIR}/package.json" package_json)
 option(CXX_INSTALL_TOOLS "Install tools" ON)
 option(CXX_INSTALL_WASI_SYSROOT "Install wasi sysroot" OFF)
 option(CXX_ENABLE_FLATBUFFERS "Enable flatbuffers" ON)
+option(CXX_ENABLE_MLIR "Enable MLIR" OFF)
 option(CXX_LIBCXX_WITH_CLANG "Link with libc++" OFF)
 option(CXX_BUILD_TESTS "Build tests" ON)
 option(CXX_INTERPROCEDURAL_OPTIMIZATION "Enable interprocedural optimization" OFF)

src/CMakeLists.txt

@@ -21,4 +21,9 @@ add_subdirectory(lib)
 add_subdirectory(parser)
 add_subdirectory(lsp)
 add_subdirectory(js)
+
+if (CXX_ENABLE_MLIR)
+  add_subdirectory(mlir)
+endif()
+
 add_subdirectory(frontend)

src/frontend/CMakeLists.txt

@@ -23,6 +23,11 @@ add_executable(cxx ${SOURCES})
 
 target_link_libraries(cxx PRIVATE cxx-lsp)
 
+if (CXX_ENABLE_MLIR)
+    target_compile_definitions(cxx PRIVATE CXX_WITH_MLIR)
+    target_link_libraries(cxx PRIVATE cxx-mlir)
+endif()
+
 if(EMSCRIPTEN)
     target_link_options(cxx PRIVATE
         "SHELL:-s EXIT_RUNTIME=1"

src/frontend/cxx/frontend.cc

@@ -38,6 +38,11 @@
 #include <cxx/wasm32_wasi_toolchain.h>
 #include <cxx/windows_toolchain.h>
 
+#ifdef CXX_WITH_MLIR
+#include <cxx/mlir/codegen.h>
+#include <cxx/mlir/cxx_dialect.h>
+#endif
+
 #include <cassert>
 #include <format>
 #include <fstream>
@@ -289,6 +294,21 @@ auto runOnFile(const CLI& cli, const std::string& fileName) -> bool {
       ASTPrinter printAST(&unit, std::cout);
       printAST(unit.ast());
     }
+
+#ifdef CXX_WITH_MLIR
+    if (cli.opt_ir_dump) {
+      mlir::MLIRContext context;
+      context.loadDialect<mlir::cxx::CxxDialect>();
+
+      cxx::Codegen codegen(context, &unit);
+
+      auto ir = codegen(unit.ast());
+
+      mlir::OpPrintingFlags flags;
+      flags.enableDebugInfo(true);
+      ir.module->print(llvm::outs(), flags);
+    }
+#endif
   }
 
   diagnosticsClient.verifyExpectedDiagnostics();

src/mlir/CMakeLists.txt

@@ -0,0 +1,18 @@
+
+if(POLICY CMP0116)
+    cmake_policy(SET CMP0116 NEW)
+endif()
+
+find_package(MLIR REQUIRED CONFIG)
+
+LIST(APPEND CMAKE_MODULE_PATH "${MLIR_CMAKE_DIR}" "${LLVM_CMAKE_DIR}")
+
+include(AddMLIR)
+include(AddLLVM)
+include(TableGen)
+include(HandleLLVMOptions)
+
+SET(CXX_MLIR_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
+SET(CXX_MLIR_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
+
+add_subdirectory(cxx/mlir)

src/mlir/cxx/mlir/CMakeLists.txt

@@ -0,0 +1,29 @@
+
+include_directories(${MLIR_INCLUDE_DIRS} ${LLVM_INCLUDE_DIRS}) # for tablegen
+add_mlir_dialect(CxxOps cxx)
+
+aux_source_directory(. SOURCES)
+add_library(cxx-mlir ${SOURCES})
+
+llvm_update_compile_flags(cxx-mlir)
+
+target_include_directories(cxx-mlir
+    PUBLIC ${CXX_MLIR_SOURCE_DIR} ${CXX_MLIR_BINARY_DIR}
+    ${MLIR_INCLUDE_DIRS}
+    ${LLVM_INCLUDE_DIRS}
+)
+
+target_link_libraries(cxx-mlir PUBLIC
+    cxx-parser
+    MLIRIR
+    MLIRFuncDialect
+    MLIRControlFlowDialect
+)
+add_dependencies(cxx-mlir MLIRCxxOpsIncGen)
+
+if (CMAKE_CXX_COMPILER_ID MATCHES "Clang|GNU")
+    target_compile_options(cxx-mlir PRIVATE
+        -Wno-unused-variable
+        -Wno-covered-switch-default
+    )
+endif()

src/mlir/cxx/mlir/CxxOps.td

@@ -0,0 +1,57 @@
+// Copyright (c) 2025 Roberto Raggi <[email protected]>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+include "mlir/IR/OpBase.td"
+include "mlir/IR/AttrTypeBase.td"
+
+def Cxx_Dialect : Dialect {
+  let name = "cxx";
+  let cppNamespace = "mlir::cxx";
+  let useDefaultTypePrinterParser = 1;
+  let dependentDialects = [
+    "mlir::func::FuncDialect",
+    "mlir::cf::ControlFlowDialect",
+  ];
+}
+
+class Cxx_Type<string name, string typeMnemonic, list<Trait> traits = []> : TypeDef<Cxx_Dialect, name, traits> {
+    let mnemonic = typeMnemonic;
+}
+
+class Cxx_Op<string mnemonic, list<Trait> traits = []> : Op<Cxx_Dialect, mnemonic, traits> {
+}
+
+def Cxx_ExprType : Cxx_Type<"Expr", "expr">;
+
+def Cxx_TodoExprOp : Cxx_Op<"todo.expr"> {
+  let arguments = (ins StrAttr:$message);
+  let results = (outs Cxx_ExprType:$result);
+  let assemblyFormat = "$message attr-dict `:` type($result)";
+  let builders = [
+    OpBuilder<(ins "::llvm::StringRef":$message),
+      [{ build($_builder, $_state, $_builder.getType<ExprType>(), message); }]>,
+  ];
+}
+
+def Cxx_TodoStmtOp : Cxx_Op<"todo.stmt"> {
+  let arguments = (ins StrAttr:$message);
+  let results = (outs);
+  let assemblyFormat = "$message attr-dict";
+}