LightMetal - Add Flatbuffers into cmake infra/build as cpm package (#…

…17039)

 - Mostly unused here, used by light metal capture/replay coming in follow up PR
 - Add CMAKE_POSITION_INDEPENDENT_CODE=ON globally (-fPIC) following discussion
   (needed for flatbuffer to avoid linking errors when lifting to tt-mlir project.
 - Use -Wno-restrict for flatbuffers compile to supress warning in g++12 build,
   though don't know why they were fine previously with flatbuffers from UMD
 - Misc PR feedback about PUBLIC vs PRIVATE, etc.

CMakeLists.txt

@@ -43,6 +43,7 @@ include(clang-tidy)
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
+set(CMAKE_POSITION_INDEPENDENT_CODE TRUE)
 
 if(NOT ENABLE_LIBCXX)
     # required when linking with libstdc++ with clang and gcc

cmake/flatbuffers.cmake

@@ -0,0 +1,17 @@
+# Function to generate FlatBuffers C++ headers from schema files
+function(GENERATE_FBS_HEADER FBS_FILE)
+    get_filename_component(FBS_FILE_NAME ${FBS_FILE} NAME_WE)
+    set(FBS_GENERATED_HEADER_DIR "${CMAKE_CURRENT_BINARY_DIR}/flatbuffers")
+    set(FBS_GENERATED_HEADER_FILE "${FBS_GENERATED_HEADER_DIR}/${FBS_FILE_NAME}_generated.h")
+    add_custom_command(
+        OUTPUT
+            ${FBS_GENERATED_HEADER_FILE}
+        COMMAND
+            flatc --cpp --scoped-enums -I ${CMAKE_CURRENT_SOURCE_DIR} -o "${FBS_GENERATED_HEADER_DIR}" ${FBS_FILE}
+        DEPENDS
+            flatc
+            ${FBS_FILE}
+        COMMENT "Building C++ header for ${FBS_FILE}"
+    )
+    set(FBS_GENERATED_HEADER_FILE ${FBS_GENERATED_HEADER_FILE} PARENT_SCOPE)
+endfunction()

cmake/tracy.cmake

@@ -20,8 +20,6 @@ set_target_properties(
             "${PROJECT_BINARY_DIR}/lib"
         ARCHIVE_OUTPUT_DIRECTORY
             "${PROJECT_BINARY_DIR}/lib"
-        POSITION_INDEPENDENT_CODE
-            ON # this is equivalent to adding -fPIC
         OUTPUT_NAME
             "tracy"
 )

dependencies/CMakeLists.txt

@@ -173,3 +173,24 @@ CPMAddPackage(
         "CMAKE_MESSAGE_LOG_LEVEL NOTICE" # Taskflow's CMakeLists.txt is super noisy
 )
 add_library(Taskflow::Taskflow ALIAS Taskflow)
+
+############################################################################################################################
+# flatbuffers : https://github.com/google/flatbuffers
+############################################################################################################################
+
+CPMAddPackage(
+    NAME flatbuffers
+    GITHUB_REPOSITORY google/flatbuffers
+    GIT_TAG v24.3.25
+    OPTIONS
+        "FLATBUFFERS_BUILD_FLATC ON"
+        "FLATBUFFERS_BUILD_TESTS OFF"
+        "FLATBUFFERS_SKIP_MONSTER_EXTRA ON"
+        "FLATBUFFERS_STRICT_MODE ON"
+)
+
+if(flatbuffers_ADDED)
+    # Few files including idl_gen_dart.cpp:175:18, Possibly related: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105329
+    target_compile_options(flatc PRIVATE -Wno-restrict)
+    target_compile_options(flatbuffers PRIVATE -Wno-restrict)
+endif()

tt_metal/impl/CMakeLists.txt

@@ -45,6 +45,16 @@ set(IMPL_SRC
     ${CMAKE_CURRENT_SOURCE_DIR}/event/event.cpp
 )
 
+# Include helper functions and generate headers from flatbuffer schemas
+include(flatbuffers)
+
+set(FLATBUFFER_SCHEMAS) # Empty to start, coming soon.
+
+foreach(FBS_FILE ${FLATBUFFER_SCHEMAS})
+    GENERATE_FBS_HEADER(${FBS_FILE})
+    list(APPEND IMPL_SRC ${FBS_GENERATED_HEADER_FILE})
+endforeach()
+
 add_library(impl OBJECT ${IMPL_SRC})
 add_library(Metalium::Metal::Impl ALIAS impl)
 
@@ -60,6 +70,7 @@ target_link_libraries(
         Taskflow::Taskflow
         TT::Metalium::HostDevCommon
         Metalium::Metal::Hardware
+        FlatBuffers::FlatBuffers
 )
 
 target_include_directories(
@@ -68,6 +79,8 @@ target_include_directories(
         ${PROJECT_SOURCE_DIR}/tt_metal
         ${CMAKE_CURRENT_SOURCE_DIR}
         ${PROJECT_SOURCE_DIR}/tt_metal/include
+    PRIVATE
+        ${CMAKE_CURRENT_BINARY_DIR}/flatbuffers
 )
 
 target_compile_options(impl PUBLIC -Wno-int-to-pointer-cast)