# Copyright 2013-2016 Numenta Inc.
#
# Copyright may exist in Contributors' modifications
# and/or contributions to the work.
#
# Use of this source code is governed by the MIT
# license that can be found in the LICENSE file or at
# https://opensource.org/licenses/MIT.


# Configures common compiler/linker/loader settings for internal and external
# sources.
#
# NOTE SETTINGS THAT ARE SPECIFIC TO THIS OR THAT MODULE DO NOT BELONG HERE.

# INPUTS:
#
# PLATFORM: lowercase ${CMAKE_SYSTEM_NAME}

# OUTPUTS:
#
# BITNESS: Platform bitness: 32 or 64
#
# COMMON_COMPILER_DEFINITIONS: list of -D define flags for the compilation of
#                               source files; e.g., for cmake `add_definitions()`
# COMMON_COMPILER_DEFINITIONS_STR: string variant of COMMON_COMPILER_DEFINITIONS
#
# EXTERNAL_C_FLAGS_UNOPTIMIZED: string of C flags without explicit optimization flags for 3rd-party sources
#
# EXTERNAL_C_FLAGS_OPTIMIZED: EXTERNAL_C_FLAGS_UNOPTIMIZED plus optimizations
#
# EXTERNAL_CXX_FLAGS_UNOPTIMIZED: string of C++ flags without explicit optimization flags for 3rd-party sources.
#
# EXTERNAL_LINKER_FLAGS_UNOPTIMIZED: string of linker flags for linking 3rd-party executables
#                      and shared libraries (DLLs) without explicit optimization
#                      settings. This property is for use with
#                      EXTERNAL_C_FLAGS_UNOPTIMIZED and EXTERNAL_CXX_FLAGS_UNOPTIMIZED
#
# EXTERNAL_LINKER_FLAGS_OPTIMIZED: string of linker flags for linking 3rd-party executables
#                      and shared libraries (DLLs) with optimizations that are
#                      compatible with EXTERNAL_C_FLAGS_OPTIMIZED and EXTERNAL_CXX_FLAGS_OPTIMIZED
#
# EXTERNAL_STATICLIB_CMAKE_DEFINITIONS_OPTIMIZED: list of -D cmake definitions corresponding to
#                      EXTERNAL_C_FLAGS_OPTIMIZED (e. g. use of gcc-ar and gcc-ranlib wrappers for gcc >= 4.9
#                      in combination with Link Time Optimization)
#
# EXTERNAL_STATICLIB_CONFIGURE_DEFINITIONS_OPTIMIZED: variant of
#                      EXTERNAL_STATICLIB_CMAKE_DEFINITIONS_OPTIMIZED used for
#                      configure-based builds
#
# INTERNAL_CXX_FLAGS_OPTIMIZED: string of C++ flags with explicit optimization flags for internal sources
#
# INTERNAL_LINKER_FLAGS_OPTIMIZED: string of linker flags for linking internal executables
#                      and shared libraries (DLLs) with optimizations that are
#                      compatible with INTERNAL_CXX_FLAGS_OPTIMIZED
#
# PYEXT_LINKER_FLAGS_OPTIMIZED: string of linker flags for linking python extension
#                      shared libraries (DLLs) with optimizations that are
#                      compatible with EXTERNAL_CXX_FLAGS_OPTIMIZED.
#
# CMAKE_AR: Name of archiving tool (ar) for static libraries. See cmake documentation
#
# CMAKE_RANLIB: Name of randomizing tool (ranlib) for static libraries. See cmake documentation
#
# CMAKE_LINKER: updated, if needed; use ld.gold if available. See cmake
#               documentation
#
# NOTE The XXX_OPTIMIZED flags are quite aggresive - if your code misbehaves for
# strange reasons, try compiling without them.

# NOTE much of the code below was factored out from src/CMakeLists.txt

if(NOT DEFINED PLATFORM)
    message(FATAL_ERROR "PLATFORM property not defined: PLATFORM=${PLATFORM}")
endif()

include(CheckCXXCompilerFlag)


# Init exported properties
set(COMMON_COMPILER_DEFINITIONS)
set(COMMON_COMPILER_DEFINITIONS_STR)

set(INTERNAL_CXX_FLAGS_OPTIMIZED)
set(INTERNAL_LINKER_FLAGS_OPTIMIZED)

set(PYEXT_LINKER_FLAGS_OPTIMIZED)

set(EXTERNAL_C_FLAGS_UNOPTIMIZED)
set(EXTERNAL_C_FLAGS_OPTIMIZED)

set(EXTERNAL_CXX_FLAGS_UNOPTIMIZED)
set(EXTERNAL_CXX_FLAGS_OPTIMIZED)

set(EXTERNAL_LINKER_FLAGS_UNOPTIMIZED)
set(EXTERNAL_LINKER_FLAGS_OPTIMIZED)

set(EXTERNAL_STATICLIB_CMAKE_DEFINITIONS_OPTIMIZED)
set(EXTERNAL_STATICLIB_CONFIGURE_DEFINITIONS_OPTIMIZED)

# Identify platform "bitness".
if(CMAKE_SIZEOF_VOID_P EQUAL 8)
  set(BITNESS 64)
else()
  set(BITNESS 32)
endif()

message(STATUS "CMAKE BITNESS=${BITNESS}")


# Check memory limits (in megabytes)
if(CMAKE_MAJOR_VERSION GREATER 2)
  cmake_host_system_information(RESULT available_physical_memory QUERY AVAILABLE_PHYSICAL_MEMORY)
  cmake_host_system_information(RESULT available_virtual_memory QUERY AVAILABLE_VIRTUAL_MEMORY)
  math(EXPR available_memory "${available_physical_memory}+${available_virtual_memory}")
  message(STATUS "CMAKE MEMORY=${available_memory}")

  # Python bindings (particularly mathPYTHON_wrap.cxx) requires more than
  # 1GB of memory for compiling with GCC. Send a warning if available memory
  # (physical plus virtual(swap)) is less than 1GB
  if(${available_memory} LESS 1024)
    message(WARNING "Less than 1GB of memory available, compilation may run out of memory!")
  endif()
endif()


# Compiler `-D*` definitions
if(UNIX) # or UNIX like (i.e. APPLE and CYGWIN)
  set(COMMON_COMPILER_DEFINITIONS
      ${COMMON_COMPILER_DEFINITIONS}
      -DHAVE_UNISTD_H)
elseif(MSVC OR MSYS OR MINGW)
  set(COMMON_COMPILER_DEFINITIONS
      ${COMMON_COMPILER_DEFINITIONS}
      -DPSAPI_VERSION=1
      -DWIN32
      -D_WINDOWS
      -D_MBCS
      -D_CRT_SECURE_NO_WARNINGS
      -DNDEBUG
      -D_VARIADIC_MAX=10
      -DNOMINMAX)
  if(MSYS OR MINGW)
    set(COMMON_COMPILER_DEFINITIONS
        ${COMMON_COMPILER_DEFINITIONS}
        -DHAVE_UNISTD_H)
  endif()
endif()


#
# Set linker (ld)
# use ld.gold if available
#
execute_process(COMMAND ld.gold --version RESULT_VARIABLE EXIT_CODE)
if(EXIT_CODE EQUAL 0)
  message("Using ld.gold as LINKER.")
  set(CMAKE_LINKER "ld.gold")
endif()


#
# Determine stdlib settings
#
set(stdlib_cxx "")
set(stdlib_common "")

if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
  set(stdlib_cxx "${stdlib_cxx} -stdlib=libc++")
endif()

if (${CMAKE_CXX_COMPILER_ID} STREQUAL "GNU")
  if (${NUPIC_BUILD_PYEXT_MODULES} AND "${PLATFORM}" STREQUAL "linux")
    # NOTE When building manylinux python extensions, we want the static
    # libstdc++ due to differences in c++ ABI between the older toolchain in the
    # manylinux Docker image and libstdc++ in newer linux distros that is
    # compiled with the c++11 ABI. for example, with shared libstdc++, the
    # manylinux-built extension is unable to catch std::ios::failure exception
    # raised by the shared libstdc++.so while running on Ubuntu 16.04.
    set(stdlib_cxx "${stdlib_cxx} -static-libstdc++")

    # NOTE We need to use shared libgcc to be able to throw and catch exceptions
    # across different shared libraries, as may be the case when our python
    # extensions runtime-link to capnproto symbols in pycapnp's extension.
    set(stdlib_common "${stdlib_common} -shared-libgcc")
  else()
    set(stdlib_common "${stdlib_common} -static-libgcc")
    set(stdlib_cxx "${stdlib_cxx} -static-libstdc++")
  endif()
endif()


#
# Determine Optimization flags here
# These are quite aggresive flags, if your code misbehaves for strange reasons,
# try compiling without them.
#
if(NOT ${CMAKE_CXX_COMPILER_ID} STREQUAL "MSVC")
  set(optimization_flags_cc "${optimization_flags_cc} -O2")
  set(optimization_flags_cc "-pipe ${optimization_flags_cc}") #TODO use -Ofast instead of -O3
  set(optimization_flags_lt "-O2 ${optimization_flags_lt}")

  if(NOT ${CMAKE_SYSTEM_PROCESSOR} STREQUAL "armv7l")
    set(optimization_flags_cc "${optimization_flags_cc} -mtune=generic")
  endif()

  if(${CMAKE_CXX_COMPILER_ID} STREQUAL "GNU" AND NOT MINGW)
    set(optimization_flags_cc "${optimization_flags_cc} -fuse-ld=gold")
    # NOTE -flto must go together in both cc and ld flags; also, it's presently incompatible
    # with the -g option in at least some GNU compilers (saw in `man gcc` on Ubuntu)
    set(optimization_flags_cc "${optimization_flags_cc} -fuse-linker-plugin -flto-report -flto") #TODO fix LTO for clang
    set(optimization_flags_lt "${optimization_flags_lt} -flto") #TODO LTO for clang too
  endif()
endif()


#
# compiler specific settings and warnings here
#

set(shared_compile_flags "")
set(internal_compiler_warning_flags "")
set(external_compiler_warning_flags "")
set(cxx_flags_unoptimized "")
set(shared_linker_flags_unoptimized "")
set(fail_link_on_undefined_symbols_flags "")
set(allow_link_with_undefined_symbols_flags "")

if(${CMAKE_CXX_COMPILER_ID} STREQUAL "MSVC")
  # MS Visual C
  set(shared_compile_flags "${shared_compile_flags} /Zc:wchar_t /Gm- /fp:precise /errorReport:prompt /W1 /WX- /GR /Gd /GS /Oy- /EHs /analyze- /nologo")
  set(shared_linker_flags_unoptimized "${shared_linker_flags_unoptimized} /NOLOGO /SAFESEH:NO /NODEFAULTLIB:LIBCMT")
  if("${BITNESS}" STREQUAL "32")
    set(shared_linker_flags_unoptimized "${shared_linker_flags_unoptimized} /MACHINE:X86")
  else()
    set(shared_linker_flags_unoptimized "${shared_linker_flags_unoptimized} /MACHINE:X${BITNESS}")
  endif()

else()
  # LLVM Clang / Gnu GCC
  set(cxx_flags_unoptimized "${cxx_flags_unoptimized} ${stdlib_cxx} -std=c++11")

  if (${NUPIC_BUILD_PYEXT_MODULES})
    # Hide all symbols in DLLs except the ones with explicit visibility;
    # see https://gcc.gnu.org/wiki/Visibility
    set(cxx_flags_unoptimized "${cxx_flags_unoptimized} -fvisibility-inlines-hidden")
    set(shared_compile_flags "${shared_compile_flags} -fvisibility=hidden")
  endif()

  set(shared_compile_flags "${shared_compile_flags} ${stdlib_common} -fdiagnostics-show-option")
  set (internal_compiler_warning_flags "${internal_compiler_warning_flags} -Werror -Wextra -Wreturn-type -Wunused -Wno-unused-variable -Wno-unused-parameter -Wno-missing-field-initializers")
  set (external_compiler_warning_flags "${external_compiler_warning_flags} -Wno-unused-variable -Wno-unused-parameter -Wno-incompatible-pointer-types -Wno-deprecated-declarations")

  CHECK_CXX_COMPILER_FLAG(-m${BITNESS} compiler_supports_machine_option)
  if (compiler_supports_machine_option)
    set(shared_compile_flags "${shared_compile_flags} -m${BITNESS}")
    set(shared_linker_flags_unoptimized "${shared_linker_flags_unoptimized} -m${BITNESS}")
  endif()
  if("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "armv7l")
    set(shared_compile_flags "${shared_compile_flags} -marm")
    set(shared_linker_flags_unoptimized "${shared_linker_flags_unoptimized} -marm")
  endif()

  if(NOT ${CMAKE_SYSTEM_NAME} MATCHES "Windows")
    set(shared_compile_flags "${shared_compile_flags} -fPIC")
    set (internal_compiler_warning_flags "${internal_compiler_warning_flags} -Wall")

    if(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")
      set(shared_compile_flags "${shared_compile_flags} -Wno-deprecated-register")
    endif()
  endif()

  set(shared_linker_flags_unoptimized "${shared_linker_flags_unoptimized} ${stdlib_common} ${stdlib_cxx}")
endif()

# Don't allow undefined symbols when linking executables
if(${CMAKE_CXX_COMPILER_ID} STREQUAL "GNU")
  set(fail_link_on_undefined_symbols_flags "-Wl,--no-undefined")
elseif(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")
  set(fail_link_on_undefined_symbols_flags "-Wl,-undefined,error")
endif()

# Don't force python extensions to link to specific libpython during build:
# python symbols are made available to extensions atomatically once loaded
#
# NOTE Windows DLLs are shared executables with their own main; they require
# all symbols to resolve at link time.
if(NOT "${PLATFORM}" STREQUAL "windows")
  if(${CMAKE_CXX_COMPILER_ID} STREQUAL "GNU")
    set(allow_link_with_undefined_symbols_flags "-Wl,--allow-shlib-undefined")
  elseif(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")
    set(allow_link_with_undefined_symbols_flags "-Wl,-undefined,dynamic_lookup")
  endif()
endif()


# Compatibility with gcc >= 4.9 which requires the use of gcc's own wrappers for
# ar and ranlib in combination with LTO works also with LTO disabled
IF(UNIX AND CMAKE_COMPILER_IS_GNUCXX AND (NOT "${CMAKE_BUILD_TYPE}" STREQUAL "Debug") AND
      (CMAKE_CXX_COMPILER_VERSION VERSION_GREATER "4.9" OR
       CMAKE_CXX_COMPILER_VERSION VERSION_EQUAL "4.9"))
    set(CMAKE_AR "gcc-ar")
    set(CMAKE_RANLIB "gcc-ranlib")
    # EXTERNAL_STATICLIB_CMAKE_DEFINITIONS_OPTIMIZED duplicates settings for
    # CMAKE_AR and CMAKE_RANLIB. This is a workaround for a CMAKE bug
    # (https://gitlab.kitware.com/cmake/cmake/issues/15547) that prevents
    # the correct propagation of CMAKE_AR and CMAKE_RANLIB variables to all
    # externals
    list(APPEND EXTERNAL_STATICLIB_CMAKE_DEFINITIONS_OPTIMIZED
         -DCMAKE_AR:PATH=gcc-ar
         -DCMAKE_RANLIB:PATH=gcc-ranlib)
    # And ditto for externals that use the configure-based build system
    list(APPEND EXTERNAL_STATICLIB_CONFIGURE_DEFINITIONS_OPTIMIZED
         AR=gcc-ar
         RANLIB=gcc-ranlib)
ENDIF()

#
# Set up Debug vs. Release options
#
set(build_type_specific_compile_flags)
set(build_type_specific_linker_flags)

if("${CMAKE_BUILD_TYPE}" STREQUAL "Debug")
  set (build_type_specific_compile_flags "${build_type_specific_compile_flags} -g")

  set(build_type_specific_linker_flags "${build_type_specific_linker_flags} -O0")

  if(${CMAKE_CXX_COMPILER_ID} STREQUAL "GNU" OR MINGW)
    set (build_type_specific_compile_flags "${build_type_specific_compile_flags} -Og")

    # Enable diagnostic features of standard class templates, including ability
    # to examine containers in gdb.
    # See https://gcc.gnu.org/onlinedocs/libstdc++/manual/debug_mode_using.html
    list(APPEND COMMON_COMPILER_DEFINITIONS -D_GLIBCXX_DEBUG)
  elseif(${CMAKE_CXX_COMPILER_ID} STREQUAL "Clang")
    # NOTE: debug mode is immature in Clang, and values of _LIBCPP_DEBUG above 0
    # require  the debug build of libc++ to be present at linktime on OS X.
    list(APPEND COMMON_COMPILER_DEFINITIONS -D_LIBCPP_DEBUG=0)
  endif()

  # Disable optimizations
  set(optimization_flags_cc)
  set(optimization_flags_lt)
endif()


#
# Assemble compiler and linker properties
#

# Settings for internal nupic.core code
set(INTERNAL_CXX_FLAGS_OPTIMIZED "${build_type_specific_compile_flags} ${shared_compile_flags} ${cxx_flags_unoptimized} ${internal_compiler_warning_flags} ${optimization_flags_cc}")

set(complete_linker_flags_unoptimized "${build_type_specific_linker_flags} ${shared_linker_flags_unoptimized}")
set(complete_linker_flags_unoptimized "${complete_linker_flags_unoptimized} ${fail_link_on_undefined_symbols_flags}")
set(INTERNAL_LINKER_FLAGS_OPTIMIZED "${complete_linker_flags_unoptimized} ${optimization_flags_lt}")

# Settings for third-party code and code generated by 3rd-party tools (e.g., Swig bindings)
# (NOTE we omit the explicit compiler warning-related flags here to avoid
#  polluting build output with warnings from code that we don't control)
set(EXTERNAL_C_FLAGS_UNOPTIMIZED "${build_type_specific_compile_flags} ${shared_compile_flags} ${external_compiler_warning_flags}")
set(EXTERNAL_C_FLAGS_OPTIMIZED "${EXTERNAL_C_FLAGS_UNOPTIMIZED} ${optimization_flags_cc}")

set(PYEXT_LINKER_FLAGS_OPTIMIZED "${build_type_specific_linker_flags} ${shared_linker_flags_unoptimized}")
set(PYEXT_LINKER_FLAGS_OPTIMIZED "${PYEXT_LINKER_FLAGS_OPTIMIZED} ${optimization_flags_lt}")
set(PYEXT_LINKER_FLAGS_OPTIMIZED "${PYEXT_LINKER_FLAGS_OPTIMIZED} ${allow_link_with_undefined_symbols_flags}")

set(EXTERNAL_CXX_FLAGS_UNOPTIMIZED "${build_type_specific_compile_flags} ${shared_compile_flags} ${external_compiler_warning_flags} ${cxx_flags_unoptimized}")
set(EXTERNAL_CXX_FLAGS_OPTIMIZED "${EXTERNAL_CXX_FLAGS_UNOPTIMIZED} ${optimization_flags_cc}")

set(EXTERNAL_LINKER_FLAGS_UNOPTIMIZED "${complete_linker_flags_unoptimized}")
set(EXTERNAL_LINKER_FLAGS_OPTIMIZED "${INTERNAL_LINKER_FLAGS_OPTIMIZED}")


#
# Provide a string variant of the COMMON_COMPILER_DEFINITIONS list
#
set(COMMON_COMPILER_DEFINITIONS_STR)
foreach(compiler_definition ${COMMON_COMPILER_DEFINITIONS})
  set(COMMON_COMPILER_DEFINITIONS_STR "${COMMON_COMPILER_DEFINITIONS_STR} ${compiler_definition}")
endforeach()

message(STATUS "INTERNAL_CXX_FLAGS_OPTIMIZED=${INTERNAL_CXX_FLAGS_OPTIMIZED}")
message(STATUS "INTERNAL_LINKER_FLAGS_OPTIMIZED=${INTERNAL_LINKER_FLAGS_OPTIMIZED}")
message(STATUS "EXTERNAL_C_FLAGS_UNOPTIMIZED=${EXTERNAL_C_FLAGS_UNOPTIMIZED}")
message(STATUS "EXTERNAL_C_FLAGS_OPTIMIZED=${EXTERNAL_C_FLAGS_OPTIMIZED}")
message(STATUS "PYEXT_LINKER_FLAGS_OPTIMIZED=${PYEXT_LINKER_FLAGS_OPTIMIZED}")
message(STATUS "EXTERNAL_CXX_FLAGS_UNOPTIMIZED=${EXTERNAL_CXX_FLAGS_UNOPTIMIZED}")
message(STATUS "EXTERNAL_CXX_FLAGS_OPTIMIZED=${EXTERNAL_CXX_FLAGS_OPTIMIZED}")
message(STATUS "EXTERNAL_LINKER_FLAGS_UNOPTIMIZED=${EXTERNAL_LINKER_FLAGS_UNOPTIMIZED}")
message(STATUS "EXTERNAL_LINKER_FLAGS_OPTIMIZED=${EXTERNAL_LINKER_FLAGS_OPTIMIZED}")
message(STATUS "COMMON_COMPILER_DEFINITIONS=${COMMON_COMPILER_DEFINITIONS}")
message(STATUS "COMMON_COMPILER_DEFINITIONS_STR=${COMMON_COMPILER_DEFINITIONS_STR}")
message(STATUS "EXTERNAL_STATICLIB_CMAKE_DEFINITIONS_OPTIMIZED=${EXTERNAL_STATICLIB_CMAKE_DEFINITIONS_OPTIMIZED}")
message(STATUS "EXTERNAL_STATICLIB_CONFIGURE_DEFINITIONS_OPTIMIZED=${EXTERNAL_STATICLIB_CONFIGURE_DEFINITIONS_OPTIMIZED}")