gem5/SConstruct
Nathan Binkert 1aef5c06a3 Rework the way SCons recurses into subdirectories, making it
automatic.  The point is that now a subdirectory can be added
to the build process just by creating a SConscript file in it.
The process has two passes.  On the first pass, all subdirs
of the root of the tree are searched for SConsopts files.
These files contain any command line options that ought to be
added for a particular subdirectory.  On the second pass,
all subdirs of the src directory are searched for SConscript
files.  These files describe how to build any given subdirectory.
I have added a Source() function.  Any file (relative to the
directory in which the SConscript resides) passed to that
function is added to the build.  Clean up everything to take
advantage of Source().
function is added to the list of files to be built.

--HG--
extra : convert_revision : 103f6b490d2eb224436688c89cdc015211c4fd30
2007-03-10 23:00:54 -08:00

676 lines
25 KiB
Python

# -*- mode:python -*-
# Copyright (c) 2004-2005 The Regents of The University of Michigan
# 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 the copyright holders 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 AND 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.
#
# Authors: Steve Reinhardt
###################################################
#
# SCons top-level build description (SConstruct) file.
#
# While in this directory ('m5'), just type 'scons' to build the default
# configuration (see below), or type 'scons build/<CONFIG>/<binary>'
# to build some other configuration (e.g., 'build/ALPHA_FS/m5.opt' for
# the optimized full-system version).
#
# You can build M5 in a different directory as long as there is a
# 'build/<CONFIG>' somewhere along the target path. The build system
# expects that all configs under the same build directory are being
# built for the same host system.
#
# Examples:
#
# The following two commands are equivalent. The '-u' option tells
# scons to search up the directory tree for this SConstruct file.
# % cd <path-to-src>/m5 ; scons build/ALPHA_FS/m5.debug
# % cd <path-to-src>/m5/build/ALPHA_FS; scons -u m5.debug
#
# The following two commands are equivalent and demonstrate building
# in a directory outside of the source tree. The '-C' option tells
# scons to chdir to the specified directory to find this SConstruct
# file.
# % cd <path-to-src>/m5 ; scons /local/foo/build/ALPHA_FS/m5.debug
# % cd /local/foo/build/ALPHA_FS; scons -C <path-to-src>/m5 m5.debug
#
# You can use 'scons -H' to print scons options. If you're in this
# 'm5' directory (or use -u or -C to tell scons where to find this
# file), you can use 'scons -h' to print all the M5-specific build
# options as well.
#
###################################################
import sys
import os
import subprocess
from os.path import join as joinpath
# Check for recent-enough Python and SCons versions. If your system's
# default installation of Python is not recent enough, you can use a
# non-default installation of the Python interpreter by either (1)
# rearranging your PATH so that scons finds the non-default 'python'
# first or (2) explicitly invoking an alternative interpreter on the
# scons script, e.g., "/usr/local/bin/python2.4 `which scons` [args]".
EnsurePythonVersion(2,4)
# Ironically, SCons 0.96 dies if you give EnsureSconsVersion a
# 3-element version number.
min_scons_version = (0,96,91)
try:
EnsureSConsVersion(*min_scons_version)
except:
print "Error checking current SCons version."
print "SCons", ".".join(map(str,min_scons_version)), "or greater required."
Exit(2)
# The absolute path to the current directory (where this file lives).
ROOT = Dir('.').abspath
# Path to the M5 source tree.
SRCDIR = joinpath(ROOT, 'src')
# tell python where to find m5 python code
sys.path.append(joinpath(ROOT, 'src/python'))
###################################################
#
# Figure out which configurations to set up based on the path(s) of
# the target(s).
#
###################################################
# Find default configuration & binary.
Default(os.environ.get('M5_DEFAULT_BINARY', 'build/ALPHA_SE/m5.debug'))
# helper function: find last occurrence of element in list
def rfind(l, elt, offs = -1):
for i in range(len(l)+offs, 0, -1):
if l[i] == elt:
return i
raise ValueError, "element not found"
# helper function: compare dotted version numbers.
# E.g., compare_version('1.3.25', '1.4.1')
# returns -1, 0, 1 if v1 is <, ==, > v2
def compare_versions(v1, v2):
# Convert dotted strings to lists
v1 = map(int, v1.split('.'))
v2 = map(int, v2.split('.'))
# Compare corresponding elements of lists
for n1,n2 in zip(v1, v2):
if n1 < n2: return -1
if n1 > n2: return 1
# all corresponding values are equal... see if one has extra values
if len(v1) < len(v2): return -1
if len(v1) > len(v2): return 1
return 0
# Each target must have 'build' in the interior of the path; the
# directory below this will determine the build parameters. For
# example, for target 'foo/bar/build/ALPHA_SE/arch/alpha/blah.do' we
# recognize that ALPHA_SE specifies the configuration because it
# follow 'build' in the bulid path.
# Generate absolute paths to targets so we can see where the build dir is
if COMMAND_LINE_TARGETS:
# Ask SCons which directory it was invoked from
launch_dir = GetLaunchDir()
# Make targets relative to invocation directory
abs_targets = map(lambda x: os.path.normpath(joinpath(launch_dir, str(x))),
COMMAND_LINE_TARGETS)
else:
# Default targets are relative to root of tree
abs_targets = map(lambda x: os.path.normpath(joinpath(ROOT, str(x))),
DEFAULT_TARGETS)
# Generate a list of the unique build roots and configs that the
# collected targets reference.
build_paths = []
build_root = None
for t in abs_targets:
path_dirs = t.split('/')
try:
build_top = rfind(path_dirs, 'build', -2)
except:
print "Error: no non-leaf 'build' dir found on target path", t
Exit(1)
this_build_root = joinpath('/',*path_dirs[:build_top+1])
if not build_root:
build_root = this_build_root
else:
if this_build_root != build_root:
print "Error: build targets not under same build root\n"\
" %s\n %s" % (build_root, this_build_root)
Exit(1)
build_path = joinpath('/',*path_dirs[:build_top+2])
if build_path not in build_paths:
build_paths.append(build_path)
###################################################
#
# Set up the default build environment. This environment is copied
# and modified according to each selected configuration.
#
###################################################
env = Environment(ENV = os.environ, # inherit user's environment vars
ROOT = ROOT,
SRCDIR = SRCDIR)
Export('env')
#Parse CC/CXX early so that we use the correct compiler for
# to test for dependencies/versions/libraries/includes
if ARGUMENTS.get('CC', None):
env['CC'] = ARGUMENTS.get('CC')
if ARGUMENTS.get('CXX', None):
env['CXX'] = ARGUMENTS.get('CXX')
env.SConsignFile(joinpath(build_root,"sconsign"))
# Default duplicate option is to use hard links, but this messes up
# when you use emacs to edit a file in the target dir, as emacs moves
# file to file~ then copies to file, breaking the link. Symbolic
# (soft) links work better.
env.SetOption('duplicate', 'soft-copy')
# I waffle on this setting... it does avoid a few painful but
# unnecessary builds, but it also seems to make trivial builds take
# noticeably longer.
if False:
env.TargetSignatures('content')
# M5_PLY is used by isa_parser.py to find the PLY package.
env.Append(ENV = { 'M5_PLY' : Dir('ext/ply') })
env['GCC'] = False
env['SUNCC'] = False
env['ICC'] = False
env['GCC'] = subprocess.Popen(env['CXX'] + ' --version', shell=True,
stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
close_fds=True).communicate()[0].find('GCC') >= 0
env['SUNCC'] = subprocess.Popen(env['CXX'] + ' -V', shell=True,
stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
close_fds=True).communicate()[0].find('Sun C++') >= 0
env['ICC'] = subprocess.Popen(env['CXX'] + ' -V', shell=True,
stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
close_fds=True).communicate()[0].find('Intel') >= 0
if env['GCC'] + env['SUNCC'] + env['ICC'] > 1:
print 'Error: How can we have two at the same time?'
Exit(1)
# Set up default C++ compiler flags
if env['GCC']:
env.Append(CCFLAGS='-pipe')
env.Append(CCFLAGS='-fno-strict-aliasing')
env.Append(CCFLAGS=Split('-Wall -Wno-sign-compare -Werror -Wundef'))
elif env['ICC']:
pass #Fix me... add warning flags once we clean up icc warnings
elif env['SUNCC']:
env.Append(CCFLAGS='-Qoption ccfe')
env.Append(CCFLAGS='-features=gcc')
env.Append(CCFLAGS='-features=extensions')
env.Append(CCFLAGS='-library=stlport4')
env.Append(CCFLAGS='-xar')
# env.Append(CCFLAGS='-instances=semiexplicit')
else:
print 'Error: Don\'t know what compiler options to use for your compiler.'
print ' Please fix SConstruct and src/SConscript and try again.'
Exit(1)
if sys.platform == 'cygwin':
# cygwin has some header file issues...
env.Append(CCFLAGS=Split("-Wno-uninitialized"))
env.Append(CPPPATH=[Dir('ext/dnet')])
# Check for SWIG
if not env.has_key('SWIG'):
print 'Error: SWIG utility not found.'
print ' Please install (see http://www.swig.org) and retry.'
Exit(1)
# Check for appropriate SWIG version
swig_version = os.popen('swig -version').read().split()
# First 3 words should be "SWIG Version x.y.z"
if swig_version[0] != 'SWIG' or swig_version[1] != 'Version':
print 'Error determining SWIG version.'
Exit(1)
min_swig_version = '1.3.28'
if compare_versions(swig_version[2], min_swig_version) < 0:
print 'Error: SWIG version', min_swig_version, 'or newer required.'
print ' Installed version:', swig_version[2]
Exit(1)
# Set up SWIG flags & scanner
env.Append(SWIGFLAGS=Split('-c++ -python -modern $_CPPINCFLAGS'))
import SCons.Scanner
swig_inc_re = '^[ \t]*[%,#][ \t]*(?:include|import)[ \t]*(<|")([^>"]+)(>|")'
swig_scanner = SCons.Scanner.ClassicCPP("SwigScan", ".i", "CPPPATH",
swig_inc_re)
env.Append(SCANNERS = swig_scanner)
# Platform-specific configuration. Note again that we assume that all
# builds under a given build root run on the same host platform.
conf = Configure(env,
conf_dir = joinpath(build_root, '.scons_config'),
log_file = joinpath(build_root, 'scons_config.log'))
# Find Python include and library directories for embedding the
# interpreter. For consistency, we will use the same Python
# installation used to run scons (and thus this script). If you want
# to link in an alternate version, see above for instructions on how
# to invoke scons with a different copy of the Python interpreter.
# Get brief Python version name (e.g., "python2.4") for locating
# include & library files
py_version_name = 'python' + sys.version[:3]
# include path, e.g. /usr/local/include/python2.4
py_header_path = joinpath(sys.exec_prefix, 'include', py_version_name)
env.Append(CPPPATH = py_header_path)
# verify that it works
if not conf.CheckHeader('Python.h', '<>'):
print "Error: can't find Python.h header in", py_header_path
Exit(1)
# add library path too if it's not in the default place
py_lib_path = None
if sys.exec_prefix != '/usr':
py_lib_path = joinpath(sys.exec_prefix, 'lib')
elif sys.platform == 'cygwin':
# cygwin puts the .dll in /bin for some reason
py_lib_path = '/bin'
if py_lib_path:
env.Append(LIBPATH = py_lib_path)
print 'Adding', py_lib_path, 'to LIBPATH for', py_version_name
if not conf.CheckLib(py_version_name):
print "Error: can't find Python library", py_version_name
Exit(1)
# On Solaris you need to use libsocket for socket ops
if not conf.CheckLibWithHeader(None, 'sys/socket.h', 'C++', 'accept(0,0,0);'):
if not conf.CheckLibWithHeader('socket', 'sys/socket.h', 'C++', 'accept(0,0,0);'):
print "Can't find library with socket calls (e.g. accept())"
Exit(1)
# Check for zlib. If the check passes, libz will be automatically
# added to the LIBS environment variable.
if not conf.CheckLibWithHeader('z', 'zlib.h', 'C++','zlibVersion();'):
print 'Error: did not find needed zlib compression library '\
'and/or zlib.h header file.'
print ' Please install zlib and try again.'
Exit(1)
# Check for <fenv.h> (C99 FP environment control)
have_fenv = conf.CheckHeader('fenv.h', '<>')
if not have_fenv:
print "Warning: Header file <fenv.h> not found."
print " This host has no IEEE FP rounding mode control."
# Check for mysql.
mysql_config = WhereIs('mysql_config')
have_mysql = mysql_config != None
# Check MySQL version.
if have_mysql:
mysql_version = os.popen(mysql_config + ' --version').read()
min_mysql_version = '4.1'
if compare_versions(mysql_version, min_mysql_version) < 0:
print 'Warning: MySQL', min_mysql_version, 'or newer required.'
print ' Version', mysql_version, 'detected.'
have_mysql = False
# Set up mysql_config commands.
if have_mysql:
mysql_config_include = mysql_config + ' --include'
if os.system(mysql_config_include + ' > /dev/null') != 0:
# older mysql_config versions don't support --include, use
# --cflags instead
mysql_config_include = mysql_config + ' --cflags | sed s/\\\'//g'
# This seems to work in all versions
mysql_config_libs = mysql_config + ' --libs'
env = conf.Finish()
# Define the universe of supported ISAs
all_isa_list = [ ]
Export('all_isa_list')
# Define the universe of supported CPU models
all_cpu_list = [ ]
default_cpus = [ ]
Export('all_cpu_list', 'default_cpus')
# Sticky options get saved in the options file so they persist from
# one invocation to the next (unless overridden, in which case the new
# value becomes sticky).
sticky_opts = Options(args=ARGUMENTS)
Export('sticky_opts')
# Non-sticky options only apply to the current build.
nonsticky_opts = Options(args=ARGUMENTS)
Export('nonsticky_opts')
# Walk the tree and execute all SConsopts scripts that wil add to the
# above options
for root, dirs, files in os.walk('.'):
if 'SConsopts' in files:
SConscript(os.path.join(root, 'SConsopts'))
all_isa_list.sort()
all_cpu_list.sort()
default_cpus.sort()
sticky_opts.AddOptions(
EnumOption('TARGET_ISA', 'Target ISA', 'alpha', all_isa_list),
BoolOption('FULL_SYSTEM', 'Full-system support', False),
# There's a bug in scons 0.96.1 that causes ListOptions with list
# values (more than one value) not to be able to be restored from
# a saved option file. If this causes trouble then upgrade to
# scons 0.96.90 or later.
ListOption('CPU_MODELS', 'CPU models', default_cpus, all_cpu_list),
BoolOption('NO_FAST_ALLOC', 'Disable fast object allocator', False),
BoolOption('EFENCE', 'Link with Electric Fence malloc debugger',
False),
BoolOption('SS_COMPATIBLE_FP',
'Make floating-point results compatible with SimpleScalar',
False),
BoolOption('USE_SSE2',
'Compile for SSE2 (-msse2) to get IEEE FP on x86 hosts',
False),
BoolOption('USE_MYSQL', 'Use MySQL for stats output', have_mysql),
BoolOption('USE_FENV', 'Use <fenv.h> IEEE mode control', have_fenv),
BoolOption('USE_CHECKER', 'Use checker for detailed CPU models', False),
('CC', 'C compiler', os.environ.get('CC', env['CC'])),
('CXX', 'C++ compiler', os.environ.get('CXX', env['CXX'])),
BoolOption('BATCH', 'Use batch pool for build and tests', False),
('BATCH_CMD', 'Batch pool submission command name', 'qdo'),
('PYTHONHOME',
'Override the default PYTHONHOME for this system (use with caution)',
'%s:%s' % (sys.prefix, sys.exec_prefix))
)
nonsticky_opts.AddOptions(
BoolOption('update_ref', 'Update test reference outputs', False)
)
# These options get exported to #defines in config/*.hh (see src/SConscript).
env.ExportOptions = ['FULL_SYSTEM', 'ALPHA_TLASER', 'USE_FENV', \
'USE_MYSQL', 'NO_FAST_ALLOC', 'SS_COMPATIBLE_FP', \
'USE_CHECKER', 'PYTHONHOME', 'TARGET_ISA']
# Define a handy 'no-op' action
def no_action(target, source, env):
return 0
env.NoAction = Action(no_action, None)
###################################################
#
# Define a SCons builder for configuration flag headers.
#
###################################################
# This function generates a config header file that #defines the
# option symbol to the current option setting (0 or 1). The source
# operands are the name of the option and a Value node containing the
# value of the option.
def build_config_file(target, source, env):
(option, value) = [s.get_contents() for s in source]
f = file(str(target[0]), 'w')
print >> f, '#define', option, value
f.close()
return None
# Generate the message to be printed when building the config file.
def build_config_file_string(target, source, env):
(option, value) = [s.get_contents() for s in source]
return "Defining %s as %s in %s." % (option, value, target[0])
# Combine the two functions into a scons Action object.
config_action = Action(build_config_file, build_config_file_string)
# The emitter munges the source & target node lists to reflect what
# we're really doing.
def config_emitter(target, source, env):
# extract option name from Builder arg
option = str(target[0])
# True target is config header file
target = joinpath('config', option.lower() + '.hh')
val = env[option]
if isinstance(val, bool):
# Force value to 0/1
val = int(val)
elif isinstance(val, str):
val = '"' + val + '"'
# Sources are option name & value (packaged in SCons Value nodes)
return ([target], [Value(option), Value(val)])
config_builder = Builder(emitter = config_emitter, action = config_action)
env.Append(BUILDERS = { 'ConfigFile' : config_builder })
###################################################
#
# Define a SCons builder for copying files. This is used by the
# Python zipfile code in src/python/SConscript, but is placed up here
# since it's potentially more generally applicable.
#
###################################################
copy_builder = Builder(action = Copy("$TARGET", "$SOURCE"))
env.Append(BUILDERS = { 'CopyFile' : copy_builder })
###################################################
#
# Define a simple SCons builder to concatenate files.
#
# Used to append the Python zip archive to the executable.
#
###################################################
concat_builder = Builder(action = Action(['cat $SOURCES > $TARGET',
'chmod +x $TARGET']))
env.Append(BUILDERS = { 'Concat' : concat_builder })
# base help text
help_text = '''
Usage: scons [scons options] [build options] [target(s)]
'''
# libelf build is shared across all configs in the build root.
env.SConscript('ext/libelf/SConscript',
build_dir = joinpath(build_root, 'libelf'),
exports = 'env')
###################################################
#
# This function is used to set up a directory with switching headers
#
###################################################
env['ALL_ISA_LIST'] = all_isa_list
def make_switching_dir(dirname, switch_headers, env):
# Generate the header. target[0] is the full path of the output
# header to generate. 'source' is a dummy variable, since we get the
# list of ISAs from env['ALL_ISA_LIST'].
def gen_switch_hdr(target, source, env):
fname = str(target[0])
basename = os.path.basename(fname)
f = open(fname, 'w')
f.write('#include "arch/isa_specific.hh"\n')
cond = '#if'
for isa in all_isa_list:
f.write('%s THE_ISA == %s_ISA\n#include "%s/%s/%s"\n'
% (cond, isa.upper(), dirname, isa, basename))
cond = '#elif'
f.write('#else\n#error "THE_ISA not set"\n#endif\n')
f.close()
return 0
# String to print when generating header
def gen_switch_hdr_string(target, source, env):
return "Generating switch header " + str(target[0])
# Build SCons Action object. 'varlist' specifies env vars that this
# action depends on; when env['ALL_ISA_LIST'] changes these actions
# should get re-executed.
switch_hdr_action = Action(gen_switch_hdr, gen_switch_hdr_string,
varlist=['ALL_ISA_LIST'])
# Instantiate actions for each header
for hdr in switch_headers:
env.Command(hdr, [], switch_hdr_action)
Export('make_switching_dir')
###################################################
#
# Define build environments for selected configurations.
#
###################################################
# rename base env
base_env = env
for build_path in build_paths:
print "Building in", build_path
# build_dir is the tail component of build path, and is used to
# determine the build parameters (e.g., 'ALPHA_SE')
(build_root, build_dir) = os.path.split(build_path)
# Make a copy of the build-root environment to use for this config.
env = base_env.Copy()
# Set env options according to the build directory config.
sticky_opts.files = []
# Options for $BUILD_ROOT/$BUILD_DIR are stored in
# $BUILD_ROOT/options/$BUILD_DIR so you can nuke
# $BUILD_ROOT/$BUILD_DIR without losing your options settings.
current_opts_file = joinpath(build_root, 'options', build_dir)
if os.path.isfile(current_opts_file):
sticky_opts.files.append(current_opts_file)
print "Using saved options file %s" % current_opts_file
else:
# Build dir-specific options file doesn't exist.
# Make sure the directory is there so we can create it later
opt_dir = os.path.dirname(current_opts_file)
if not os.path.isdir(opt_dir):
os.mkdir(opt_dir)
# Get default build options from source tree. Options are
# normally determined by name of $BUILD_DIR, but can be
# overriden by 'default=' arg on command line.
default_opts_file = joinpath('build_opts',
ARGUMENTS.get('default', build_dir))
if os.path.isfile(default_opts_file):
sticky_opts.files.append(default_opts_file)
print "Options file %s not found,\n using defaults in %s" \
% (current_opts_file, default_opts_file)
else:
print "Error: cannot find options file %s or %s" \
% (current_opts_file, default_opts_file)
Exit(1)
# Apply current option settings to env
sticky_opts.Update(env)
nonsticky_opts.Update(env)
help_text += "Sticky options for %s:\n" % build_dir \
+ sticky_opts.GenerateHelpText(env) \
+ "\nNon-sticky options for %s:\n" % build_dir \
+ nonsticky_opts.GenerateHelpText(env)
# Process option settings.
if not have_fenv and env['USE_FENV']:
print "Warning: <fenv.h> not available; " \
"forcing USE_FENV to False in", build_dir + "."
env['USE_FENV'] = False
if not env['USE_FENV']:
print "Warning: No IEEE FP rounding mode control in", build_dir + "."
print " FP results may deviate slightly from other platforms."
if env['EFENCE']:
env.Append(LIBS=['efence'])
if env['USE_MYSQL']:
if not have_mysql:
print "Warning: MySQL not available; " \
"forcing USE_MYSQL to False in", build_dir + "."
env['USE_MYSQL'] = False
else:
print "Compiling in", build_dir, "with MySQL support."
env.ParseConfig(mysql_config_libs)
env.ParseConfig(mysql_config_include)
# Save sticky option settings back to current options file
sticky_opts.Save(current_opts_file, env)
# Do this after we save setting back, or else we'll tack on an
# extra 'qdo' every time we run scons.
if env['BATCH']:
env['CC'] = env['BATCH_CMD'] + ' ' + env['CC']
env['CXX'] = env['BATCH_CMD'] + ' ' + env['CXX']
if env['USE_SSE2']:
env.Append(CCFLAGS='-msse2')
# The src/SConscript file sets up the build rules in 'env' according
# to the configured options. It returns a list of environments,
# one for each variant build (debug, opt, etc.)
envList = SConscript('src/SConscript', build_dir = build_path,
exports = 'env')
# Set up the regression tests for each build.
for e in envList:
SConscript('tests/SConscript',
build_dir = joinpath(build_path, 'tests', e.Label),
exports = { 'env' : e }, duplicate = False)
Help(help_text)
###################################################
#
# Let SCons do its thing. At this point SCons will use the defined
# build environments to build the requested targets.
#
###################################################