Make the out-of-tree build approach optional

Signed-off-by: Bili Dong <qobilidop@gmail.com>

CMakeLists.txt

@@ -1,27 +1,35 @@
 cmake_minimum_required(VERSION 3.20.0)
-project(p4mlir LANGUAGES CXX C)
+project(p4mlir LANGUAGES CXX)
+
+# TODO: Consider unify the build process and remove this option.
+option(BUILD_P4MLIR_OUT_OF_TREE "Whether to build P4MLIR out-of-tree" OFF)
 
 set(CMAKE_BUILD_WITH_INSTALL_NAME_DIR ON)
 
 set(CMAKE_CXX_STANDARD 17 CACHE STRING "C++ standard to conform to")
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-find_package(MLIR REQUIRED CONFIG)
+if(BUILD_P4MLIR_OUT_OF_TREE)
+    find_package(MLIR REQUIRED CONFIG)
 
-message(STATUS "Using MLIRConfig.cmake in: ${MLIR_DIR}")
-message(STATUS "Using LLVMConfig.cmake in: ${LLVM_DIR}")
+    message(STATUS "Using MLIRConfig.cmake in: ${MLIR_DIR}")
+    message(STATUS "Using LLVMConfig.cmake in: ${LLVM_DIR}")
 
-set(LLVM_RUNTIME_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/bin)
-set(LLVM_LIBRARY_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/lib)
-set(MLIR_BINARY_DIR ${CMAKE_BINARY_DIR})
+    set(LLVM_RUNTIME_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/bin)
+    set(LLVM_LIBRARY_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/lib)
+    set(MLIR_BINARY_DIR ${CMAKE_BINARY_DIR})
 
-list(APPEND CMAKE_MODULE_PATH "${MLIR_CMAKE_DIR}")
-list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_DIR}")
+    list(APPEND CMAKE_MODULE_PATH "${MLIR_CMAKE_DIR}")
+    list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_DIR}")
 
-include(TableGen)
-include(AddLLVM)
-include(AddMLIR)
-include(HandleLLVMOptions)
+    include(TableGen)
+    include(AddLLVM)
+    include(AddMLIR)
+    include(HandleLLVMOptions)
+else()
+    add_subdirectory(third_party)
+    set(LLVM_RUNTIME_OUTPUT_INTDIR ${P4MLIR_BINARY_DIR}/bin)
+endif()
 
 set(P4MLIR_SOURCE_DIR ${PROJECT_SOURCE_DIR})
 set(P4MLIR_BINARY_DIR ${PROJECT_BINARY_DIR})

build_tools/build_p4c_with_p4mlir_ext.sh

@@ -47,6 +47,7 @@ CMAKE_FLAGS+=" -DENABLE_TEST_TOOLS=OFF"
 CMAKE_FLAGS+=" -DENABLE_P4C_GRAPHS=OFF"
 
 # Configure P4MLIR CMake flags
+CMAKE_FLAGS+=" -DBUILD_P4MLIR_OUT_OF_TREE=ON"
 CMAKE_FLAGS+=" -DCMAKE_INSTALL_PREFIX=$LLVM_INSTALL_DIR"
 CMAKE_FLAGS+=" -DMLIR_DIR=$LLVM_INSTALL_DIR/lib/cmake/mlir"
 CMAKE_FLAGS+=" -DLLVM_EXTERNAL_LIT=$LLVM_BUILD_DIR/bin/llvm-lit"

lib/Dialect/P4HIR/P4HIR_Attrs.cpp

@@ -12,10 +12,6 @@
 using namespace mlir;
 using namespace P4::P4MLIR::P4HIR;
 
-Type BoolType::parse(mlir::AsmParser &parser) { return get(parser.getContext()); }
-
-void BoolType::print(mlir::AsmPrinter &printer) const {}
-
 Attribute IntAttr::parse(AsmParser &parser, Type odsType) {
     mlir::APInt APValue;