build_tools/cmake/iree_setup_toolchain.cmake

# Copyright 2020 The IREE Authors
#
# Licensed 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(CheckCXXCompilerFlag)
include(CheckLinkerFlag)
include(CheckSymbolExists)

# Appends ${VALUE} to each argument.
function(iree_append_to_lists VALUE)
  foreach(_VARIABLE ${ARGN})
    set(${_VARIABLE} "${${_VARIABLE}} ${VALUE}" PARENT_SCOPE)
  endforeach(_VARIABLE)
endfunction()

# Perform global "toolchain" setup. This customizes a variety of globals
# that need to be setup consistently if using IREE build machinery at a
# different level (i.e. a parent project which includes it as a sub-directory).
# Almost everything in here is technical debt which should be wired in
# explicitly or through global properties. Please don't add to it without
# a very good reason.
macro(iree_setup_toolchain)
  #-----------------------------------------------------------------------------
  # Supports dynamic library loading.
  #-----------------------------------------------------------------------------

  set(CMAKE_REQUIRED_LIBRARIES ${CMAKE_DL_LIBS})
  check_symbol_exists(dlopen dlfcn.h IREE_HAVE_DLOPEN)
  unset(CMAKE_REQUIRED_LIBRARIES)
  if(WIN32 OR IREE_HAVE_DLOPEN)
    set(IREE_HAVE_DYNAMIC_LIBRARY_LOADING ON)
  else()
    set(IREE_HAVE_DYNAMIC_LIBRARY_LOADING OFF)
  endif()

  #-----------------------------------------------------------------------------
  # Compiler flag support
  #-----------------------------------------------------------------------------

  check_cxx_compiler_flag(-fvisibility=default IREE_SUPPORTS_VISIBILITY_DEFAULT)

  #-----------------------------------------------------------------------------
  # Linker setup
  #-----------------------------------------------------------------------------

  if(IREE_ENABLE_LLD)
    if(IREE_USE_LINKER)
      message(FATAL_ERROR "IREE_ENABLE_LLD and IREE_USE_LINKER can't be set at the same time")
    endif()
    set(IREE_USE_LINKER "lld")
  endif()

  if(IREE_USE_LINKER)
    set(IREE_LINKER_FLAG "-fuse-ld=${IREE_USE_LINKER}")

    # Depending on how the C compiler is invoked, it may trigger an unused
    # argument warning about -fuse-ld, which can foul up compiler flag detection,
    # causing false negatives. We lack a finer grained way to suppress such a
    # thing, and this is deemed least bad.
    if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
      iree_append_to_lists("-Wno-unused-command-line-argument"
        CMAKE_REQUIRED_FLAGS
        CMAKE_EXE_LINKER_FLAGS
        CMAKE_MODULE_LINKER_FLAGS
        CMAKE_SHARED_LINKER_FLAGS
      )
    endif()

    iree_append_to_lists("${IREE_LINKER_FLAG}"
      CMAKE_REQUIRED_FLAGS
      CMAKE_EXE_LINKER_FLAGS
      CMAKE_MODULE_LINKER_FLAGS
      CMAKE_SHARED_LINKER_FLAGS
    )
    include(CheckCXXSourceCompiles)
    include(CheckCSourceCompiles)
    set(MINIMAL_SRC "int main() { return 0; }")
    check_cxx_source_compiles("${MINIMAL_SRC}" CXX_SUPPORTS_CUSTOM_LINKER)
    check_c_source_compiles("${MINIMAL_SRC}" CC_SUPPORTS_CUSTOM_LINKER)

    # Note: if you see errors here, check
    #   * logs in CMakeFiles/CMakeError.log in your build directory
    #   * that you have a recent version of your chosen linker (for example:
    #     install the version of lld that we use in our Docker images)
    if(NOT CXX_SUPPORTS_CUSTOM_LINKER)
      message(FATAL_ERROR "Compiler '${CMAKE_CXX_COMPILER}' does not support '${IREE_LINKER_FLAG}'")
    endif()
    if(NOT CC_SUPPORTS_CUSTOM_LINKER)
      message(FATAL_ERROR "Compiler '${CMAKE_C_COMPILER}' does not support '${IREE_LINKER_FLAG}'")
    endif()
  endif()

  #-----------------------------------------------------------------------------
  # Sanitizer configurations
  #-----------------------------------------------------------------------------

  # Note: we add these flags to the global CMake flags, not to IREE-specific
  # variables such as IREE_DEFAULT_COPTS so that all symbols are consistently
  # defined with the same sanitizer flags, including e.g. standard library
  # symbols that might be used by both IREE and non-IREE (e.g. LLVM) code.

  if(IREE_ENABLE_ASAN)
    string(APPEND CMAKE_CXX_FLAGS " -fsanitize=address")
    string(APPEND CMAKE_C_FLAGS " -fsanitize=address")

    # Not technically ASAN, but it guards against similar bugs in accessing
    # uninitialized memory. See the extensive description in that patch that
    # originally introduced it:
    # https://reviews.llvm.org/rG14daa20be1ad89639ec209d969232d19cf698845
    string(APPEND CMAKE_CXX_FLAGS " -ftrivial-auto-var-init=pattern")
    string(APPEND CMAKE_C_FLAGS " -ftrivial-auto-var-init=pattern")

    # If doing any kind of shared library builds, then we have to link against
    # the shared libasan, and the user will be responsible for adding the
    # appropriate path to LD_LIBRARY_PATH (or else binaries will fail to launch).
    if(BUILD_SHARED_LIBS OR IREE_COMPILER_BUILD_SHARED_LIBS)
      string(APPEND CMAKE_EXE_LINKER_FLAGS " -shared-libasan")
      string(APPEND CMAKE_SHARED_LINKER_FLAGS " -shared-libasan")
    endif()
  endif()
  if(IREE_ENABLE_MSAN)
    string(APPEND CMAKE_CXX_FLAGS " -fsanitize=memory")
    string(APPEND CMAKE_C_FLAGS " -fsanitize=memory")
  endif()
  if(IREE_ENABLE_TSAN)
    string(APPEND CMAKE_CXX_FLAGS " -fsanitize=thread")
    string(APPEND CMAKE_C_FLAGS " -fsanitize=thread")
  endif()
  if(IREE_ENABLE_UBSAN)
    string(APPEND CMAKE_CXX_FLAGS " -fsanitize=undefined")
    string(APPEND CMAKE_C_FLAGS " -fsanitize=undefined")
  endif()

  #-----------------------------------------------------------------------------
  # Build performance optimizations
  #-----------------------------------------------------------------------------

  # Split DWARF breaks debug information out of object files and stores them in
  # separate .dwo files. This reduces a lot of needless I/O during normal build
  # activities. It consists of the -gsplit-dwarf compiler flag and (for maximum
  # effect) the --gdb-index linker flag, which just emits an index to binaries
  # instead of full debug contents. gdb-index is supported by gold and partially
  # supported by LLD (LLD supports it if split-dwarf objects were compiled with
  # ggnu-pubnames).
  # If https://gitlab.kitware.com/cmake/cmake/-/issues/21179 is ever implemented,
  # use that.
  if(IREE_ENABLE_SPLIT_DWARF)
    check_cxx_compiler_flag(-gsplit-dwarf IREE_SUPPORTS_SPLIT_DWARF)
    if(IREE_SUPPORTS_SPLIT_DWARF)
      # Also add -ggnu-pubnames for compilation because it links faster and lld
      # doesn't do the slow path without it.
      iree_append_to_lists(" -gsplit-dwarf -ggnu-pubnames"
        CMAKE_C_FLAGS_DEBUG
        CMAKE_CXX_FLAGS_DEBUG
        CMAKE_C_FLAGS_RELWITHDEBINFO
        CMAKE_CXX_FLAGS_RELWITHDEBINFO
      )
    endif()
    check_linker_flag(CXX "-Wl,--gdb-index" IREE_SUPPORTS_GDB_INDEX)
    if(IREE_SUPPORTS_GDB_INDEX)
      message(STATUS "Enabling gdb-index (binaries with debug info are not relocatable)")
      iree_append_to_lists(" -Wl,--gdb-index"
        CMAKE_EXE_LINKER_FLAGS_DEBUG
        CMAKE_MODULE_LINKER_FLAGS_DEBUG
        CMAKE_SHARED_LINKER_FLAGS_DEBUG
        CMAKE_EXE_LINKER_FLAGS_RELWITHDEBINFO
        CMAKE_MODULE_LINKER_FLAGS_RELWITHDEBINFO
        CMAKE_SHARED_LINKER_FLAGS_RELWITHDEBINFO
      )
    endif()
  endif()

  # Thin archives makes static archives that only link to backing object files
  # instead of embedding them. This makes them non-relocatable but is almost
  # always the right thing outside of certain deployment/packaging scenarios.
  if(IREE_ENABLE_THIN_ARCHIVES)
    execute_process(COMMAND ${CMAKE_AR} -V OUTPUT_VARIABLE IREE_AR_VERSION)
    if ("${IREE_AR_VERSION}" MATCHES "^GNU ar|LLVM")
      message(STATUS "Enabling thin archives (static libraries will not be relocatable)")
      set(CMAKE_C_ARCHIVE_APPEND "<CMAKE_AR> qT <TARGET> <LINK_FLAGS> <OBJECTS>")
      set(CMAKE_CXX_ARCHIVE_APPEND "<CMAKE_AR> qT <TARGET> <LINK_FLAGS> <OBJECTS>")
      set(CMAKE_C_ARCHIVE_CREATE "<CMAKE_AR> crT <TARGET> <LINK_FLAGS> <OBJECTS>")
      set(CMAKE_CXX_ARCHIVE_CREATE "<CMAKE_AR> crT <TARGET> <LINK_FLAGS> <OBJECTS>")
    else()
      message(WARNING "Thin archives requested but not supported by ar")
    endif()
  endif()
endmacro()

iree_setup_toolchain()