# Copyright 2021 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

# iree_c_module()
#
# Parameters:
# NAME: Name of target (see Note).
# SRC: MLIR source file to compile into a c module.
# H_FILE_OUTPUT: The H header file to output.
# COMPILE_TOOL: Compiler tool to invoke (CMake target). The default tool is
#     "iree-compile".
# FLAGS: Additional flags to pass to the compile tool (list of strings).
#     `--output-format=vm-c` is included automatically.
# STATIC_LIB_PATH: When added, the module is compiled into a LLVM static
#     library with the specified library path.
# TESTONLY: When added, this target will only be built if user passes
#     -DIREE_BUILD_TESTS=ON to CMake.
# NO_RUNTIME: When added, this target will be built without the runtime library
#     support.
#
# Note:
# By default, iree_c_module will create a library named ${NAME},
# and alias target iree::${NAME}. The iree:: form should always be used.
# This is to reduce namespace pollution.
function(iree_c_module)
  cmake_parse_arguments(
    _RULE
    "TESTONLY;NO_RUNTIME"
    "NAME;SRC;H_FILE_OUTPUT;COMPILE_TOOL;STATIC_LIB_PATH"
    "FLAGS"
    ${ARGN}
  )

  if(_RULE_TESTONLY AND NOT IREE_BUILD_TESTS)
    return()
  endif()

  if(_RULE_STATIC_LIB_PATH AND
     NOT (IREE_TARGET_BACKEND_LLVM_CPU OR IREE_HOST_BIN_DIR))
    message(SEND_ERROR "Static library only supports llvm-cpu backend")
  endif()

  # Replace dependencies passed by ::name with iree::package::name
  iree_package_ns(_PACKAGE_NS)
  list(TRANSFORM _RULE_DEPS REPLACE "^::" "${_PACKAGE_NS}::")

  # Prefix the library with the package name, so we get: iree_package_name.
  iree_package_name(_PACKAGE_NAME)
  set(_NAME "${_PACKAGE_NAME}_${_RULE_NAME}_hdrs")

  # Set defaults for COMPILE_TOOL.
  if(DEFINED _RULE_COMPILE_TOOL)
    set(_COMPILE_TOOL ${_RULE_COMPILE_TOOL})
  else()
    set(_COMPILE_TOOL "iree-compile")
  endif()

  get_filename_component(_SRC_PATH "${_RULE_SRC}" REALPATH)

  set(_ARGS "--output-format=vm-c")
  list(APPEND _ARGS "${_RULE_FLAGS}")
  list(APPEND _ARGS "${_SRC_PATH}")
  list(APPEND _ARGS "-o")
  list(APPEND _ARGS "${_RULE_H_FILE_OUTPUT}")

  set(_OUTPUT_FILES "${_RULE_H_FILE_OUTPUT}")
  # Check LLVM static library setting. If the static library output path is set,
  # retrieve the object path and the corresponding header file path.
  if(_RULE_STATIC_LIB_PATH)
    list(APPEND _ARGS "--iree-llvmcpu-link-embedded=false")
    list(APPEND _ARGS "--iree-llvmcpu-link-static")
    list(APPEND _ARGS "--iree-llvmcpu-static-library-output-path=${_RULE_STATIC_LIB_PATH}")

    string(REPLACE ".o" ".h" _STATIC_HDR_PATH "${_RULE_STATIC_LIB_PATH}")
    list(APPEND _OUTPUT_FILES "${_RULE_STATIC_LIB_PATH}" "${_STATIC_HDR_PATH}")
  endif()

  iree_compile_flags_for_platform(_PLATFORM_FLAGS "${_RULE_FLAGS}")
  if(_PLATFORM_FLAGS)
    list(APPEND _ARGS "${_PLATFORM_FLAGS}")
  endif()

  add_custom_command(
    OUTPUT ${_OUTPUT_FILES}
    COMMAND ${_COMPILE_TOOL} ${_ARGS}
    DEPENDS ${_COMPILE_TOOL} ${_SRC_PATH}
  )

  # Generated EmitC code may have unused variables from optimization
  # barriers and other cases where an SSA value is consumed by an op
  # that produces a new value. Suppress this warning for Clang/GCC.
  iree_select_compiler_opts(_EMITC_SUPPRESS_OPTS
    CLANG_OR_GCC
      "-Wno-unused-but-set-variable"
  )

  iree_cc_library(
    NAME ${_RULE_NAME}
    HDRS "${_RULE_H_FILE_OUTPUT}"
    SRCS "${IREE_SOURCE_DIR}/runtime/src/iree/vm/module_impl_emitc.c"
    INCLUDES "${CMAKE_CURRENT_BINARY_DIR}"
    COPTS
      "-DEMITC_IMPLEMENTATION=\"${_RULE_H_FILE_OUTPUT}\""
      ${_EMITC_SUPPRESS_OPTS}
      "${_TESTONLY_ARG}"
    DEPS
      # Include paths and options for the runtime sources.
      iree_defs
  )

  # Apply warning suppression to consumers (tests, etc.) that include the
  # generated headers.
  iree_package_name(_PACKAGE_NAME)
  set(_TARGET "${_PACKAGE_NAME}_${_RULE_NAME}")
  if(_EMITC_SUPPRESS_OPTS)
    target_compile_options(${_TARGET} INTERFACE ${_EMITC_SUPPRESS_OPTS})
  endif()

  if(_RULE_NO_RUNTIME)
    return()
  endif()

  set(_GEN_TARGET "${_NAME}_gen")
  add_custom_target(
    ${_GEN_TARGET}
    DEPENDS
      ${_RULE_H_FILE_OUTPUT}
  )

  add_library(${_NAME} INTERFACE)
  add_dependencies(${_NAME} ${_GEN_TARGET})
  add_dependencies(${_NAME}
    iree::vm
    iree::vm::ops
    iree::vm::ops_emitc
    iree::vm::shims_emitc
  )

  # Alias the iree_package_name library to iree::package::name.
  # This lets us more clearly map to Bazel and makes it possible to
  # disambiguate the underscores in paths vs. the separators.
  add_library(${_PACKAGE_NS}::${_RULE_NAME}_hdrs ALIAS ${_NAME})
  iree_package_dir(_PACKAGE_DIR)
  if(${_RULE_NAME}_hdrs STREQUAL ${_PACKAGE_DIR})
    # If the library name matches the package then treat it as a default.
    # For example, foo/bar/ library 'bar' would end up as 'foo::bar'.
    add_library(${_PACKAGE_NS} ALIAS ${_NAME})
  endif()
endfunction()