# -*- 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: Nathan Binkert

import imp
import os
import py_compile
import sys
import zipfile

from os.path import basename, exists, isdir, isfile, join as joinpath

import SCons

# This file defines how to build a particular configuration of M5
# based on variable settings in the 'env' build environment.

Import('*')

# Children need to see the environment
Export('env')

build_env = dict([(opt, env[opt]) for opt in env.ExportOptions])

def sort_list(_list):
    """return a sorted copy of '_list'"""
    if isinstance(_list, list):
        _list = _list[:]
    else:
        _list = list(_list)
    _list.sort()
    return _list

class PySourceFile(object):
    def __init__(self, package, source):
        filename = str(source)
        pyname = basename(filename)
        assert pyname.endswith('.py')
        name = pyname[:-3]
        path = package.split('.')
        modpath = path
        if name != '__init__':
            modpath += [name]
        modpath = '.'.join(modpath)

        arcpath = package.split('.') + [ pyname + 'c' ]
        arcname = joinpath(*arcpath)

        self.source = source
        self.pyname = pyname
        self.srcpath = source.srcnode().abspath
        self.package = package
        self.modpath = modpath
        self.arcname = arcname
        self.filename = filename
        self.compiled = File(filename + 'c')

########################################################################
# Code for adding source files of various types
#
cc_sources = []
def Source(source):
    '''Add a C/C++ source file to the build'''
    if not isinstance(source, SCons.Node.FS.File):
        source = File(source)

    cc_sources.append(source)

py_sources = []
def PySource(package, source):
    '''Add a python source file to the named package'''
    if not isinstance(source, SCons.Node.FS.File):
        source = File(source)

    source = PySourceFile(package, source)
    py_sources.append(source)

sim_objects_fixed = False
sim_object_modfiles = set()
def SimObject(source):
    '''Add a SimObject python file as a python source object and add
    it to a list of sim object modules'''

    if sim_objects_fixed:
        raise AttributeError, "Too late to call SimObject now."

    if not isinstance(source, SCons.Node.FS.File):
        source = File(source)

    PySource('m5.objects', source)
    modfile = basename(str(source))
    assert modfile.endswith('.py')
    modname = modfile[:-3]
    sim_object_modfiles.add(modname)

swig_sources = []
def SwigSource(package, source):
    '''Add a swig file to build'''
    if not isinstance(source, SCons.Node.FS.File):
        source = File(source)
    val = source,package
    swig_sources.append(val)

# Children should have access
Export('Source')
Export('PySource')
Export('SimObject')
Export('SwigSource')

########################################################################
#
# Trace Flags
#
all_flags = {}
trace_flags = []
def TraceFlag(name, desc=''):
    if name in all_flags:
        raise AttributeError, "Flag %s already specified" % name
    flag = (name, (), desc)
    trace_flags.append(flag)
    all_flags[name] = ()

def CompoundFlag(name, flags, desc=''):
    if name in all_flags:
        raise AttributeError, "Flag %s already specified" % name

    compound = tuple(flags)
    for flag in compound:
        if flag not in all_flags:
            raise AttributeError, "Trace flag %s not found" % flag
        if all_flags[flag]:
            raise AttributeError, \
                "Compound flag can't point to another compound flag"

    flag = (name, compound, desc)
    trace_flags.append(flag)
    all_flags[name] = compound

Export('TraceFlag')
Export('CompoundFlag')

########################################################################
#
# Set some compiler variables
#

# Include file paths are rooted in this directory.  SCons will
# automatically expand '.' to refer to both the source directory and
# the corresponding build directory to pick up generated include
# files.
env.Append(CPPPATH=Dir('.'))

# Add a flag defining what THE_ISA should be for all compilation
env.Append(CPPDEFINES=[('THE_ISA','%s_ISA' % env['TARGET_ISA'].upper())])

########################################################################
#
# Walk the tree and execute all SConscripts in subdirectories
#

for base_dir in base_dir_list:
    here = Dir('.').srcnode().abspath
    for root, dirs, files in os.walk(base_dir, topdown=True):
        if root == here:
            # we don't want to recurse back into this SConscript
            continue

        if 'SConscript' in files:
            build_dir = joinpath(env['BUILDDIR'], root[len(base_dir) + 1:])
            SConscript(joinpath(root, 'SConscript'), build_dir=build_dir)

for opt in env.ExportOptions:
    env.ConfigFile(opt)

########################################################################
#
# Prevent any SimObjects from being added after this point, they
# should all have been added in the SConscripts above
#
class DictImporter(object):
    '''This importer takes a dictionary of arbitrary module names that
    map to arbitrary filenames.'''
    def __init__(self, modules):
        self.modules = modules
        self.installed = set()

    def __del__(self):
        self.unload()

    def unload(self):
        import sys
        for module in self.installed:
            del sys.modules[module]
        self.installed = set()

    def find_module(self, fullname, path):
        if fullname == '__scons':
            return self

        if fullname == 'm5.objects':
            return self

        if fullname.startswith('m5.internal'):
            return None

        if fullname in self.modules and exists(self.modules[fullname]):
            return self

        return None

    def load_module(self, fullname):
        mod = imp.new_module(fullname)
        sys.modules[fullname] = mod
        self.installed.add(fullname)

        mod.__loader__ = self
        if fullname == 'm5.objects':
            mod.__path__ = fullname.split('.')
            return mod

        if fullname == '__scons':
            mod.__dict__['m5_build_env'] = build_env
            return mod

        srcfile = self.modules[fullname]
        if basename(srcfile) == '__init__.py':
            mod.__path__ = fullname.split('.')
        mod.__file__ = srcfile

        exec file(srcfile, 'r') in mod.__dict__

        return mod

py_modules = {}
for source in py_sources:
    py_modules[source.modpath] = source.srcpath

# install the python importer so we can grab stuff from the source
# tree itself.  We can't have SimObjects added after this point or
# else we won't know about them for the rest of the stuff.
sim_objects_fixed = True
importer = DictImporter(py_modules)
sys.meta_path[0:0] = [ importer ]

import m5

# import all sim objects so we can populate the all_objects list
# make sure that we're working with a list, then let's sort it
sim_objects = list(sim_object_modfiles)
sim_objects.sort()
for simobj in sim_objects:
    exec('from m5.objects import %s' % simobj)

# we need to unload all of the currently imported modules so that they
# will be re-imported the next time the sconscript is run
importer.unload()
sys.meta_path.remove(importer)

sim_objects = m5.SimObject.allClasses
all_enums = m5.params.allEnums

all_params = {}
for name,obj in sim_objects.iteritems():
    for param in obj._params.local.values():
        if not hasattr(param, 'swig_decl'):
            continue
        pname = param.ptype_str
        if pname not in all_params:
            all_params[pname] = param

########################################################################
#
# calculate extra dependencies
#
module_depends = ["m5", "m5.SimObject", "m5.params"]
depends = [ File(py_modules[dep]) for dep in module_depends ]

########################################################################
#
# Commands for the basic automatically generated python files
#

# Generate Python file containing a dict specifying the current
# build_env flags.
def makeDefinesPyFile(target, source, env):
    f = file(str(target[0]), 'w')
    print >>f, "m5_build_env = ", source[0]
    f.close()

# Generate python file containing info about the M5 source code
def makeInfoPyFile(target, source, env):
    f = file(str(target[0]), 'w')
    for src in source:
        data = ''.join(file(src.srcnode().abspath, 'r').xreadlines())
        print >>f, "%s = %s" % (src, repr(data))
    f.close()

# Generate the __init__.py file for m5.objects
def makeObjectsInitFile(target, source, env):
    f = file(str(target[0]), 'w')
    print >>f, 'from params import *'
    print >>f, 'from m5.SimObject import *'
    for module in source:
        print >>f, 'from %s import *' % module.get_contents()
    f.close()

# Generate a file with all of the compile options in it
env.Command('python/m5/defines.py', Value(build_env), makeDefinesPyFile)
PySource('m5', 'python/m5/defines.py')

# Generate a file that wraps the basic top level files
env.Command('python/m5/info.py',
            [ '#/AUTHORS', '#/LICENSE', '#/README', '#/RELEASE_NOTES' ],
            makeInfoPyFile)
PySource('m5', 'python/m5/info.py')

# Generate an __init__.py file for the objects package
env.Command('python/m5/objects/__init__.py',
            [ Value(o) for o in sort_list(sim_object_modfiles) ],
            makeObjectsInitFile)
PySource('m5.objects', 'python/m5/objects/__init__.py')

########################################################################
#
# Create all of the SimObject param headers and enum headers
#

def createSimObjectParam(target, source, env):
    assert len(target) == 1 and len(source) == 1

    hh_file = file(target[0].abspath, 'w')
    name = str(source[0].get_contents())
    obj = sim_objects[name]

    print >>hh_file, obj.cxx_decl()

def createSwigParam(target, source, env):
    assert len(target) == 1 and len(source) == 1

    i_file = file(target[0].abspath, 'w')
    name = str(source[0].get_contents())
    param = all_params[name]

    for line in param.swig_decl():
        print >>i_file, line

def createEnumStrings(target, source, env):
    assert len(target) == 1 and len(source) == 1

    cc_file = file(target[0].abspath, 'w')
    name = str(source[0].get_contents())
    obj = all_enums[name]

    print >>cc_file, obj.cxx_def()
    cc_file.close()

def createEnumParam(target, source, env):
    assert len(target) == 1 and len(source) == 1

    hh_file = file(target[0].abspath, 'w')
    name = str(source[0].get_contents())
    obj = all_enums[name]

    print >>hh_file, obj.cxx_decl()

# Generate all of the SimObject param struct header files
params_hh_files = []
for name,simobj in sim_objects.iteritems():
    extra_deps = [ File(py_modules[simobj.__module__]) ]

    hh_file = File('params/%s.hh' % name)
    params_hh_files.append(hh_file)
    env.Command(hh_file, Value(name), createSimObjectParam)
    env.Depends(hh_file, depends + extra_deps)

# Generate any parameter header files needed
params_i_files = []
for name,param in all_params.iteritems():
    if isinstance(param, m5.params.VectorParamDesc):
        ext = 'vptype'
    else:
        ext = 'ptype'

    i_file = File('params/%s_%s.i' % (name, ext))
    params_i_files.append(i_file)
    env.Command(i_file, Value(name), createSwigParam)
    env.Depends(i_file, depends)

# Generate all enum header files
for name,enum in all_enums.iteritems():
    extra_deps = [ File(py_modules[enum.__module__]) ]

    cc_file = File('enums/%s.cc' % name)
    env.Command(cc_file, Value(name), createEnumStrings)
    env.Depends(cc_file, depends + extra_deps)
    Source(cc_file)

    hh_file = File('enums/%s.hh' % name)
    env.Command(hh_file, Value(name), createEnumParam)
    env.Depends(hh_file, depends + extra_deps)

# Build the big monolithic swigged params module (wraps all SimObject
# param structs and enum structs)
def buildParams(target, source, env):
    names = [ s.get_contents() for s in source ]
    objs = [ sim_objects[name] for name in names ]
    out = file(target[0].abspath, 'w')

    ordered_objs = []
    obj_seen = set()
    def order_obj(obj):
        name = str(obj)
        if name in obj_seen:
            return

        obj_seen.add(name)
        if str(obj) != 'SimObject':
            order_obj(obj.__bases__[0])

        ordered_objs.append(obj)

    for obj in objs:
        order_obj(obj)

    enums = set()
    predecls = []
    pd_seen = set()

    def add_pds(*pds):
        for pd in pds:
            if pd not in pd_seen:
                predecls.append(pd)
                pd_seen.add(pd)

    for obj in ordered_objs:
        params = obj._params.local.values()
        for param in params:
            ptype = param.ptype
            if issubclass(ptype, m5.params.Enum):
                if ptype not in enums:
                    enums.add(ptype)
            pds = param.swig_predecls()
            if isinstance(pds, (list, tuple)):
                add_pds(*pds)
            else:
                add_pds(pds)

    print >>out, '%module params'

    print >>out, '%{'
    for obj in ordered_objs:
        print >>out, '#include "params/%s.hh"' % obj
    print >>out, '%}'

    for pd in predecls:
        print >>out, pd

    enums = list(enums)
    enums.sort()
    for enum in enums:
        print >>out, '%%include "enums/%s.hh"' % enum.__name__
    print >>out

    for obj in ordered_objs:
        if obj.swig_objdecls:
            for decl in obj.swig_objdecls:
                print >>out, decl
            continue

        code = ''
        base = obj.get_base()

        code += '// stop swig from creating/wrapping default ctor/dtor\n'
        code += '%%nodefault %s;\n' % obj.cxx_class
        code += 'class %s ' % obj.cxx_class
        if base:
            code += ': public %s' % base
        code += ' {};\n'

        klass = obj.cxx_class;
        if hasattr(obj, 'cxx_namespace'):
            new_code = 'namespace %s {\n' % obj.cxx_namespace
            new_code += code
            new_code += '}\n'
            code = new_code
            klass = '%s::%s' % (obj.cxx_namespace, klass)

        print >>out, code

    print >>out, '%%include "src/sim/sim_object_params.hh"' % obj
    for obj in ordered_objs:
        print >>out, '%%include "params/%s.hh"' % obj

params_file = File('params/params.i')
names = sort_list(sim_objects.keys())
env.Command(params_file, [ Value(v) for v in names ], buildParams)
env.Depends(params_file, params_hh_files + params_i_files + depends)
SwigSource('m5.objects', params_file)

# Build all swig modules
swig_modules = []
for source,package in swig_sources:
    filename = str(source)
    assert filename.endswith('.i')

    base = '.'.join(filename.split('.')[:-1])
    module = basename(base)
    cc_file = base + '_wrap.cc'
    py_file = base + '.py'

    env.Command([cc_file, py_file], source,
                '$SWIG $SWIGFLAGS -outdir ${TARGETS[1].dir} '
                '-o ${TARGETS[0]} $SOURCES')
    env.Depends(py_file, source)
    env.Depends(cc_file, source)

    swig_modules.append(Value(module))
    Source(cc_file)
    PySource(package, py_file)

# Generate the main swig init file
def makeSwigInit(target, source, env):
    f = file(str(target[0]), 'w')
    print >>f, 'extern "C" {'
    for module in source:
        print >>f, '    void init_%s();' % module.get_contents()
    print >>f, '}'
    print >>f, 'void init_swig() {'
    for module in source:
        print >>f, '    init_%s();' % module.get_contents()
    print >>f, '}'
    f.close()

env.Command('swig/init.cc', swig_modules, makeSwigInit)
Source('swig/init.cc')

# Generate traceflags.py
def traceFlagsPy(target, source, env):
    assert(len(target) == 1)

    f = file(str(target[0]), 'w')

    allFlags = []
    for s in source:
        val = eval(s.get_contents())
        allFlags.append(val)

    print >>f, 'baseFlags = ['
    for flag, compound, desc in allFlags:
        if not compound:
            print >>f, "    '%s'," % flag
    print >>f, "    ]"
    print >>f

    print >>f, 'compoundFlags = ['
    print >>f, "    'All',"
    for flag, compound, desc in allFlags:
        if compound:
            print >>f, "    '%s'," % flag
    print >>f, "    ]"
    print >>f

    print >>f, "allFlags = frozenset(baseFlags + compoundFlags)"
    print >>f

    print >>f, 'compoundFlagMap = {'
    all = tuple([flag for flag,compound,desc in allFlags if not compound])
    print >>f, "    'All' : %s," % (all, )
    for flag, compound, desc in allFlags:
        if compound:
            print >>f, "    '%s' : %s," % (flag, compound)
    print >>f, "    }"
    print >>f

    print >>f, 'flagDescriptions = {'
    print >>f, "    'All' : 'All flags',"
    for flag, compound, desc in allFlags:
        print >>f, "    '%s' : '%s'," % (flag, desc)
    print >>f, "    }"

    f.close()

def traceFlagsCC(target, source, env):
    assert(len(target) == 1)

    f = file(str(target[0]), 'w')

    allFlags = []
    for s in source:
        val = eval(s.get_contents())
        allFlags.append(val)

    # file header
    print >>f, '''
/*
 * DO NOT EDIT THIS FILE! Automatically generated
 */

#include "base/traceflags.hh"

using namespace Trace;

const char *Trace::flagStrings[] =
{'''

    # The string array is used by SimpleEnumParam to map the strings
    # provided by the user to enum values.
    for flag, compound, desc in allFlags:
        if not compound:
            print >>f, '    "%s",' % flag

    print >>f, '    "All",'
    for flag, compound, desc in allFlags:
        if compound:
            print >>f, '    "%s",' % flag

    print >>f, '};'
    print >>f
    print >>f, 'const int Trace::numFlagStrings = %d;' % (len(allFlags) + 1)
    print >>f

    #
    # Now define the individual compound flag arrays.  There is an array
    # for each compound flag listing the component base flags.
    #
    all = tuple([flag for flag,compound,desc in allFlags if not compound])
    print >>f, 'static const Flags AllMap[] = {'
    for flag, compound, desc in allFlags:
        if not compound:
            print >>f, "    %s," % flag
    print >>f, '};'
    print >>f

    for flag, compound, desc in allFlags:
        if not compound:
            continue
        print >>f, 'static const Flags %sMap[] = {' % flag
        for flag in compound:
            print >>f, "    %s," % flag
        print >>f, "    (Flags)-1"
        print >>f, '};'
        print >>f

    #
    # Finally the compoundFlags[] array maps the compound flags
    # to their individual arrays/
    #
    print >>f, 'const Flags *Trace::compoundFlags[] ='
    print >>f, '{'
    print >>f, '    AllMap,'
    for flag, compound, desc in allFlags:
        if compound:
            print >>f, '    %sMap,' % flag
    # file trailer
    print >>f, '};'

    f.close()

def traceFlagsHH(target, source, env):
    assert(len(target) == 1)

    f = file(str(target[0]), 'w')

    allFlags = []
    for s in source:
        val = eval(s.get_contents())
        allFlags.append(val)

    # file header boilerplate
    print >>f, '''
/*
 * DO NOT EDIT THIS FILE!
 *
 * Automatically generated from traceflags.py
 */

#ifndef __BASE_TRACE_FLAGS_HH__
#define __BASE_TRACE_FLAGS_HH__

namespace Trace {

enum Flags {'''

    # Generate the enum.  Base flags come first, then compound flags.
    idx = 0
    for flag, compound, desc in allFlags:
        if not compound:
            print >>f, '    %s = %d,' % (flag, idx)
            idx += 1

    numBaseFlags = idx
    print >>f, '    NumFlags = %d,' % idx

    # put a comment in here to separate base from compound flags
    print >>f, '''
// The remaining enum values are *not* valid indices for Trace::flags.
// They are "compound" flags, which correspond to sets of base
// flags, and are used by changeFlag.'''

    print >>f, '    All = %d,' % idx
    idx += 1
    for flag, compound, desc in allFlags:
        if compound:
            print >>f, '    %s = %d,' % (flag, idx)
            idx += 1

    numCompoundFlags = idx - numBaseFlags
    print >>f, '    NumCompoundFlags = %d' % numCompoundFlags

    # trailer boilerplate
    print >>f, '''\
}; // enum Flags

// Array of strings for SimpleEnumParam
extern const char *flagStrings[];
extern const int numFlagStrings;

// Array of arraay pointers: for each compound flag, gives the list of
// base flags to set.  Inidividual flag arrays are terminated by -1.
extern const Flags *compoundFlags[];

/* namespace Trace */ }

#endif // __BASE_TRACE_FLAGS_HH__
'''

    f.close()

flags = [ Value(f) for f in trace_flags ]
env.Command('base/traceflags.py', flags, traceFlagsPy)
PySource('m5', 'base/traceflags.py')

env.Command('base/traceflags.hh', flags, traceFlagsHH)
env.Command('base/traceflags.cc', flags, traceFlagsCC)
Source('base/traceflags.cc')

# Generate program_info.cc
def programInfo(target, source, env):
    def gen_file(target, rev, node, date):
        pi_stats = file(target, 'w')
        print >>pi_stats, 'const char *hgRev = "%s:%s";' %  (rev, node)
        print >>pi_stats, 'const char *hgDate = "%s";' % date
        pi_stats.close()

    target = str(target[0])
    scons_dir = str(source[0].get_contents())
    try:
        import mercurial.demandimport, mercurial.hg, mercurial.ui
        import mercurial.util, mercurial.node
        if not exists(scons_dir) or not isdir(scons_dir) or \
               not exists(joinpath(scons_dir, ".hg")):
            raise ValueError
        repo = mercurial.hg.repository(mercurial.ui.ui(), scons_dir)
        rev = mercurial.node.nullrev + repo.changelog.count()
        changenode = repo.changelog.node(rev)
        changes = repo.changelog.read(changenode)
        date = mercurial.util.datestr(changes[2])

        gen_file(target, rev, mercurial.node.hex(changenode), date)

        mercurial.demandimport.disable()
    except ImportError:
        gen_file(target, "Unknown", "Unknown", "Unknown")

    except:
        print "in except"
        gen_file(target, "Unknown", "Unknown", "Unknown")
        mercurial.demandimport.disable()

env.Command('base/program_info.cc',
            Value(str(SCons.Node.FS.default_fs.SConstruct_dir)),
            programInfo)

# Build the zip file
def compilePyFile(target, source, env):
    '''Action function to compile a .py into a .pyc'''
    py_compile.compile(str(source[0]), str(target[0]))

def buildPyZip(target, source, env):
    '''Action function to build the zip archive.  Uses the
    PyZipFile module included in the standard Python library.'''

    py_compiled = {}
    for s in py_sources:
        compname = str(s.compiled)
        assert compname not in py_compiled
        py_compiled[compname] = s

    zf = zipfile.ZipFile(str(target[0]), 'w')
    for s in source:
        zipname = str(s)
        arcname = py_compiled[zipname].arcname
        zf.write(zipname, arcname)
    zf.close()

py_compiled = []
py_zip_depends = []
for source in py_sources:
    env.Command(source.compiled, source.source, compilePyFile)
    py_compiled.append(source.compiled)

    # make the zipfile depend on the archive name so that the archive
    # is rebuilt if the name changes
    py_zip_depends.append(Value(source.arcname))

# Add the zip file target to the environment.
m5zip = File('m5py.zip')
env.Command(m5zip, py_compiled, buildPyZip)
env.Depends(m5zip, py_zip_depends)

########################################################################
#
# Define binaries.  Each different build type (debug, opt, etc.) gets
# a slightly different build environment.
#

# List of constructed environments to pass back to SConstruct
envList = []

# This function adds the specified sources to the given build
# environment, and returns a list of all the corresponding SCons
# Object nodes (including an extra one for date.cc).  We explicitly
# add the Object nodes so we can set up special dependencies for
# date.cc.
def make_objs(sources, env):
    objs = [env.Object(s) for s in sources]
  
    # make date.cc depend on all other objects so it always gets
    # recompiled whenever anything else does
    date_obj = env.Object('base/date.cc')

    # Make the generation of program_info.cc dependend on all 
    # the other cc files and the compiling of program_info.cc 
    # dependent on all the objects but program_info.o 
    pinfo_obj = env.Object('base/program_info.cc')
    env.Depends('base/program_info.cc', sources)
    env.Depends(date_obj, objs)
    env.Depends(pinfo_obj, objs)
    objs.extend([date_obj,pinfo_obj])
    return objs

# Function to create a new build environment as clone of current
# environment 'env' with modified object suffix and optional stripped
# binary.  Additional keyword arguments are appended to corresponding
# build environment vars.
def makeEnv(label, objsfx, strip = False, **kwargs):
    newEnv = env.Copy(OBJSUFFIX=objsfx)
    newEnv.Label = label
    newEnv.Append(**kwargs)
    exe = 'm5.' + label  # final executable
    bin = exe + '.bin'   # executable w/o appended Python zip archive
    newEnv.Program(bin, make_objs(cc_sources, newEnv))
    if strip:
        stripped_bin = bin + '.stripped'
        if sys.platform == 'sunos5':
            cmd = 'cp $SOURCE $TARGET; strip $TARGET'
        else:
            cmd = 'strip $SOURCE -o $TARGET'
        newEnv.Command(stripped_bin, bin, cmd)
        bin = stripped_bin
    targets = newEnv.Concat(exe, [bin, 'm5py.zip'])
    newEnv.M5Binary = targets[0]
    envList.append(newEnv)

# Debug binary
ccflags = {}
if env['GCC']:
    if sys.platform == 'sunos5':
        ccflags['debug'] = '-gstabs+'
    else:
        ccflags['debug'] = '-ggdb3'
    ccflags['opt'] = '-g -O3'
    ccflags['fast'] = '-O3'
    ccflags['prof'] = '-O3 -g -pg'
elif env['SUNCC']:
    ccflags['debug'] = '-g0'
    ccflags['opt'] = '-g -O'
    ccflags['fast'] = '-fast'
    ccflags['prof'] = '-fast -g -pg'
elif env['ICC']:
    ccflags['debug'] = '-g -O0'
    ccflags['opt'] = '-g -O'
    ccflags['fast'] = '-fast'
    ccflags['prof'] = '-fast -g -pg'
else:
    print 'Unknown compiler, please fix compiler options'
    Exit(1)

makeEnv('debug', '.do',
        CCFLAGS = Split(ccflags['debug']),
        CPPDEFINES = ['DEBUG', 'TRACING_ON=1'])

# Optimized binary
makeEnv('opt', '.o',
        CCFLAGS = Split(ccflags['opt']),
        CPPDEFINES = ['TRACING_ON=1'])

# "Fast" binary
makeEnv('fast', '.fo', strip = True,
        CCFLAGS = Split(ccflags['fast']),
        CPPDEFINES = ['NDEBUG', 'TRACING_ON=0'])

# Profiled binary
makeEnv('prof', '.po',
        CCFLAGS = Split(ccflags['prof']),
        CPPDEFINES = ['NDEBUG', 'TRACING_ON=0'],
        LINKFLAGS = '-pg')

Return('envList')