SConstruct

# Copyright 2015, VIXL authors
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#   * Redistributions of source code must retain the above copyright notice,
#     this list of conditions and the following disclaimer.
#   * Redistributions in binary form must reproduce the above copyright notice,
#     this list of conditions and the following disclaimer in the documentation
#     and/or other materials provided with the distribution.
#   * Neither the name of ARM Limited nor the names of its contributors may be
#     used to endorse or promote products derived from this software without
#     specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

import glob
import os
from os.path import join
import platform
import subprocess
import sys
from collections import OrderedDict

root_dir = os.path.dirname(File('SConstruct').rfile().abspath)
sys.path.insert(0, join(root_dir, 'tools'))
import config
import util


Help('''
Build system for the VIXL project.
See README.md for documentation and details about the build system.
''')


# We track top-level targets to automatically generate help and alias them.
class TopLevelTargets:
  def __init__(self):
    self.targets = []
    self.help_messages = []
  def Add(self, target, help_message):
    self.targets.append(target)
    self.help_messages.append(help_message)
  def Help(self):
    res = ""
    for i in range(len(self.targets)):
      res += '\t{0:<{1}}{2:<{3}}\n'.format(
        'scons ' + self.targets[i],
        len('scons ') + max(map(len, self.targets)),
        ' : ' + self.help_messages[i],
        len(' : ') + max(map(len, self.help_messages)))
    return res

top_level_targets = TopLevelTargets()



# Build options ----------------------------------------------------------------

# Store all the options in a dictionary.
# The SConstruct will check the build variables and construct the build
# environment as appropriate.
options = {
    'all' : { # Unconditionally processed.
      'CCFLAGS' : ['-Wall',
                   '-Werror',
                   '-fdiagnostics-show-option',
                   '-Wextra',
                   '-Wredundant-decls',
                   '-pedantic',
                   '-Wmissing-noreturn',
                   '-Wwrite-strings',
                   '-Wunused'],
      'CPPPATH' : [config.dir_src_vixl]
      },
#   'build_option:value' : {
#     'environment_key' : 'values to append'
#     },
    'mode:debug' : {
      'CCFLAGS' : ['-DVIXL_DEBUG', '-O0']
      },
    'mode:release' : {
      'CCFLAGS' : ['-O3'],
      },
    'simulator:aarch64' : {
      'CCFLAGS' : ['-DVIXL_INCLUDE_SIMULATOR_AARCH64'],
      },
    'symbols:on' : {
      'CCFLAGS' : ['-g'],
      'LINKFLAGS' : ['-g']
      },
    }


# A `DefaultVariable` has a default value that depends on elements not known
# when variables are first evaluated.
# Each `DefaultVariable` has a handler that will compute the default value for
# the given environment.
def modifiable_flags_handler(env):
  env['modifiable_flags'] = \
      'on' if 'mode' in env and env['mode'] == 'debug' else 'off'


def symbols_handler(env):
  env['symbols'] = 'on' if 'mode' in env and env['mode'] == 'debug' else 'off'


# The architecture targeted by default will depend on the compiler being
# used. 'host_arch' is extracted from the compiler while 'target_arch' can be
# set by the user.
# By default, we target both AArch32 and AArch64 unless the compiler
# targets AArch32. At the moment, we cannot build VIXL's AArch64 support on a 32
# bit platform.
# TODO: Port VIXL to build on a 32 bit platform.
def target_arch_handler(env):
  if env['host_arch'] == 'aarch32':
    env['target_arch'] = 'aarch32'
  else:
    env['target_arch'] = 'both'


# By default, include the simulator only if AArch64 is targeted and we are not
# building VIXL natively for AArch64.
def simulator_handler(env):
  if env['host_arch'] != 'aarch64' and \
     env['target_arch'] in ['aarch64', 'both']:
    env['simulator'] = 'aarch64'
  else:
    env['simulator'] = 'none'


# Default variables may depend on each other, therefore we need this dictionnary
# to be ordered.
vars_default_handlers = OrderedDict({
    # variable_name    : [ 'default val', 'handler'                ]
    'symbols'          : [ 'mode==debug', symbols_handler          ],
    'modifiable_flags' : [ 'mode==debug', modifiable_flags_handler ],
    'target_arch'      : [ 'same as host architecture if running on AArch32 - '
                           'otherwise both',
                           target_arch_handler ],
    'simulator'        : ['on if the target architectures include AArch64 but '
                           'the host is not AArch64, else off',
                           simulator_handler ]
    })


def DefaultVariable(name, help, allowed_values):
  help = '%s (%s)' % (help, '|'.join(allowed_values))
  default_value = vars_default_handlers[name][0]
  def validator(name, value, env):
    if value != default_value and value not in allowed_values:
        raise SCons.Errors.UserError(
            'Invalid value for option {name}: {value}.  '
            'Valid values are: {allowed_values}'.format(name,
                                                        value,
                                                        allowed_values))
  return (name, help, default_value, validator)


vars = Variables()
# Define command line build options.
vars.AddVariables(
    EnumVariable('mode', 'Build mode',
                 'release', allowed_values=config.build_options_modes),
    DefaultVariable('symbols', 'Include debugging symbols in the binaries',
                    ['on', 'off']),
    DefaultVariable('target_arch', 'Target architecture',
                    ['aarch32', 'aarch64', 'both']),
    DefaultVariable('simulator', 'Simulators to include', ['aarch64', 'none']),
    ('std', 'C++ standard. The standards tested are: %s.' % \
                                         ', '.join(config.tested_cpp_standards))
    )

# Abort the build if any command line option is unknown or invalid.
unknown_build_options = vars.UnknownVariables()
if unknown_build_options:
  print 'Unknown build options:',  unknown_build_options.keys()
  Exit(1)

# We use 'variant directories' to avoid recompiling multiple times when build
# options are changed, different build paths are used depending on the options
# set. These are the options that should be reflected in the build directory
# path.
options_influencing_build_path = [
  'target_arch', 'mode', 'symbols', 'CXX', 'std', 'simulator'
]



# Build helpers ----------------------------------------------------------------

def RetrieveEnvironmentVariables(env):
  for key in ['CC', 'CXX', 'AR', 'RANLIB', 'LD']:
    if os.getenv(key): env[key] = os.getenv(key)
  if os.getenv('LD_LIBRARY_PATH'): env['LIBPATH'] = os.getenv('LD_LIBRARY_PATH')
  if os.getenv('CCFLAGS'):
    env.Append(CCFLAGS = os.getenv('CCFLAGS').split())
  if os.getenv('CXXFLAGS'):
    env.Append(CXXFLAGS = os.getenv('CXXFLAGS').split())
  if os.getenv('LINKFLAGS'):
    env.Append(LINKFLAGS = os.getenv('LINKFLAGS').split())
  # This allows colors to be displayed when using with clang.
  env['ENV']['TERM'] = os.getenv('TERM')


def ProcessBuildOptions(env):
  # 'all' is unconditionally processed.
  if 'all' in options:
    for var in options['all']:
      if var in env and env[var]:
        env[var] += options['all'][var]
      else:
        env[var] = options['all'][var]

  # Other build options must match 'option:value'
  env_dict = env.Dictionary()

  # First apply the default variables handlers in order.
  for key, value in vars_default_handlers.items():
    default = value[0]
    handler = value[1]
    if env_dict.get(key) == default:
      handler(env_dict)

  for key in env_dict.keys():
    # Then update the environment according to the value of the variable.
    key_val_couple = key + ':%s' % env_dict[key]
    if key_val_couple in options:
      for var in options[key_val_couple]:
        env[var] += options[key_val_couple][var]


def ConfigureEnvironmentForCompiler(env):
  def is_compiler(compiler):
    return env['CXX'].find(compiler) == 0
  if is_compiler('clang++'):
    # These warnings only work for Clang.
    # -Wimplicit-fallthrough only works when compiling the code base as C++11 or
    # newer. The compiler does not complain if the option is passed when
    # compiling earlier C++ standards.
    env.Append(CPPFLAGS = ['-Wimplicit-fallthrough', '-Wshorten-64-to-32'])

    # The '-Wunreachable-code' flag breaks builds for clang 3.4.
    process = subprocess.Popen(env['CXX'] + ' --version | grep "clang.*3\.4"',
                               shell = True,
                               stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    stdout, stderr = process.communicate()
    using_clang3_4 = stdout != ''
    if not using_clang3_4:
      env.Append(CPPFLAGS = ['-Wunreachable-code'])

    env.Append(CPPFLAGS = ['-Wno-shorten-64-to-32'])

  # GCC 4.8 has a bug which produces a warning saying that an anonymous Operand
  # object might be used uninitialized:
  #   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57045
  # The bug does not seem to appear in GCC 4.7, or in debug builds with GCC 4.8.
  if env['mode'] == 'release':
    process = subprocess.Popen(env['CXX'] + ' --version 2>&1 | grep "g++.*4\.8"',
                               shell = True,
                               stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    stdout, unused = process.communicate()
    using_gcc48 = stdout != ''
    if using_gcc48:
      env.Append(CPPFLAGS = ['-Wno-maybe-uninitialized'])
  # On OSX, compilers complain about `long long` being a C++11 extension when no
  # standard is passed.
  if 'std' not in env or env['std'] == 'c++98':
    env.Append(CPPFLAGS = ['-Wno-c++11-long-long'])


def ConfigureEnvironment(env):
  RetrieveEnvironmentVariables(env)
  env['host_arch'] = util.GetHostArch(env['CXX'])
  ProcessBuildOptions(env)
  if 'std' in env:
    env.Append(CPPFLAGS = ['-std=' + env['std']])
    std_path = env['std']
  ConfigureEnvironmentForCompiler(env)


def TargetBuildDir(env):
  # Build-time option values are embedded in the build path to avoid requiring a
  # full build when an option changes.
  build_dir = config.dir_build
  for option in options_influencing_build_path:
    option_value = env[option] if option in env else ''
    build_dir = join(build_dir, option + '_'+ option_value)
  return build_dir


def PrepareVariantDir(location, build_dir):
  location_build_dir = join(build_dir, location)
  VariantDir(location_build_dir, location)
  return location_build_dir


def VIXLLibraryTarget(env):
  build_dir = TargetBuildDir(env)
  # Create a link to the latest build directory.
  # Use `-r` to avoid failure when `latest` exists and is a directory.
  subprocess.check_call(["rm", "-rf", config.dir_build_latest])
  util.ensure_dir(build_dir)
  subprocess.check_call(["ln", "-s", build_dir, config.dir_build_latest])
  # Source files are in `src` and in `src/aarch64/`.
  variant_dir_vixl = PrepareVariantDir(join('src'), build_dir)
  sources = [Glob(join(variant_dir_vixl, '*.cc'))]
  if env['target_arch'] in ['aarch32', 'both']:
    variant_dir_aarch32 = PrepareVariantDir(join('src', 'aarch32'), build_dir)
    sources.append(Glob(join(variant_dir_aarch32, '*.cc')))
  if env['target_arch'] in ['aarch64', 'both']:
    variant_dir_aarch64 = PrepareVariantDir(join('src', 'aarch64'), build_dir)
    sources.append(Glob(join(variant_dir_aarch64, '*.cc')))
  return env.Library(join(build_dir, 'vixl'), sources)



# Build ------------------------------------------------------------------------

# The VIXL library, built by default.
env = Environment(variables = vars)
ConfigureEnvironment(env)
Help(vars.GenerateHelpText(env))
libvixl = VIXLLibraryTarget(env)
Default(libvixl)
env.Alias('libvixl', libvixl)
top_level_targets.Add('', 'Build the VIXL library.')


# Common test code.
test_build_dir = PrepareVariantDir('test', TargetBuildDir(env))
test_objects = [env.Object(Glob(join(test_build_dir, '*.cc')))]

# AArch32 support
if env['target_arch'] in ['aarch32', 'both']:
  # The examples.
  aarch32_example_names = util.ListCCFilesWithoutExt(config.dir_aarch32_examples)
  aarch32_examples_build_dir = PrepareVariantDir('examples/aarch32', TargetBuildDir(env))
  aarch32_example_targets = []
  for example in aarch32_example_names:
    prog = env.Program(join(aarch32_examples_build_dir, example),
                       join(aarch32_examples_build_dir, example + '.cc'),
                       LIBS=[libvixl])
    aarch32_example_targets.append(prog)
  env.Alias('aarch32_examples', aarch32_example_targets)
  top_level_targets.Add('aarch32_examples', 'Build the examples for AArch32.')

  # The tests.
  test_aarch32_build_dir = PrepareVariantDir(join('test', 'aarch32'), TargetBuildDir(env))
  test_objects.append(env.Object(
      Glob(join(test_aarch32_build_dir, '*.cc')),
      CPPPATH = env['CPPPATH'] + [config.dir_tests]))

# AArch64 support
if env['target_arch'] in ['aarch64', 'both']:
  # The benchmarks.
  aarch64_benchmark_names = util.ListCCFilesWithoutExt(config.dir_aarch64_benchmarks)
  aarch64_benchmarks_build_dir = PrepareVariantDir('benchmarks/aarch64', TargetBuildDir(env))
  aarch64_benchmark_targets = []
  for bench in aarch64_benchmark_names:
    prog = env.Program(join(aarch64_benchmarks_build_dir, bench),
                       join(aarch64_benchmarks_build_dir, bench + '.cc'),
                       LIBS=[libvixl])
    aarch64_benchmark_targets.append(prog)
  env.Alias('aarch64_benchmarks', aarch64_benchmark_targets)
  top_level_targets.Add('aarch64_benchmarks', 'Build the benchmarks for AArch64.')

  # The examples.
  aarch64_example_names = util.ListCCFilesWithoutExt(config.dir_aarch64_examples)
  aarch64_examples_build_dir = PrepareVariantDir('examples/aarch64', TargetBuildDir(env))
  aarch64_example_targets = []
  for example in aarch64_example_names:
    prog = env.Program(join(aarch64_examples_build_dir, example),
                       join(aarch64_examples_build_dir, example + '.cc'),
                       LIBS=[libvixl])
    aarch64_example_targets.append(prog)
  env.Alias('aarch64_examples', aarch64_example_targets)
  top_level_targets.Add('aarch64_examples', 'Build the examples for AArch64.')

  # The tests.
  test_aarch64_build_dir = PrepareVariantDir(join('test', 'aarch64'), TargetBuildDir(env))
  test_objects.append(env.Object(
      Glob(join(test_aarch64_build_dir, '*.cc')),
      CPPPATH = env['CPPPATH'] + [config.dir_tests]))

  # The test requires building the example files with specific options, so we
  # create a separate variant dir for the example objects built this way.
  test_aarch64_examples_vdir = join(TargetBuildDir(env), 'test', 'aarch64', 'test_examples')
  VariantDir(test_aarch64_examples_vdir, '.')
  test_aarch64_examples_obj = env.Object(
      [Glob(join(test_aarch64_examples_vdir, join('test', 'aarch64', 'examples/aarch64', '*.cc'))),
       Glob(join(test_aarch64_examples_vdir, join('examples/aarch64', '*.cc')))],
      CCFLAGS = env['CCFLAGS'] + ['-DTEST_EXAMPLES'],
      CPPPATH = env['CPPPATH'] + [config.dir_aarch64_examples] + [config.dir_tests])
  test_objects.append(test_aarch64_examples_obj)

test = env.Program(join(test_build_dir, 'test-runner'), test_objects,
                   LIBS=[libvixl])
env.Alias('tests', test)
top_level_targets.Add('tests', 'Build the tests.')


env.Alias('all', top_level_targets.targets)
top_level_targets.Add('all', 'Build all the targets above.')

Help('\n\nAvailable top level targets:\n' + top_level_targets.Help())