SConstruct revision 10181:6270235e0585
1# -*- mode:python -*-
2
3# Copyright (c) 2013 ARM Limited
4# All rights reserved.
5#
6# The license below extends only to copyright in the software and shall
7# not be construed as granting a license to any other intellectual
8# property including but not limited to intellectual property relating
9# to a hardware implementation of the functionality of the software
10# licensed hereunder.  You may use the software subject to the license
11# terms below provided that you ensure that this notice is replicated
12# unmodified and in its entirety in all distributions of the software,
13# modified or unmodified, in source code or in binary form.
14#
15# Copyright (c) 2011 Advanced Micro Devices, Inc.
16# Copyright (c) 2009 The Hewlett-Packard Development Company
17# Copyright (c) 2004-2005 The Regents of The University of Michigan
18# All rights reserved.
19#
20# Redistribution and use in source and binary forms, with or without
21# modification, are permitted provided that the following conditions are
22# met: redistributions of source code must retain the above copyright
23# notice, this list of conditions and the following disclaimer;
24# redistributions in binary form must reproduce the above copyright
25# notice, this list of conditions and the following disclaimer in the
26# documentation and/or other materials provided with the distribution;
27# neither the name of the copyright holders nor the names of its
28# contributors may be used to endorse or promote products derived from
29# this software without specific prior written permission.
30#
31# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
32# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
33# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
34# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
35# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
36# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
37# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
38# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
39# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
40# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
41# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42#
43# Authors: Steve Reinhardt
44#          Nathan Binkert
45
46###################################################
47#
48# SCons top-level build description (SConstruct) file.
49#
50# While in this directory ('gem5'), just type 'scons' to build the default
51# configuration (see below), or type 'scons build/<CONFIG>/<binary>'
52# to build some other configuration (e.g., 'build/ALPHA/gem5.opt' for
53# the optimized full-system version).
54#
55# You can build gem5 in a different directory as long as there is a
56# 'build/<CONFIG>' somewhere along the target path.  The build system
57# expects that all configs under the same build directory are being
58# built for the same host system.
59#
60# Examples:
61#
62#   The following two commands are equivalent.  The '-u' option tells
63#   scons to search up the directory tree for this SConstruct file.
64#   % cd <path-to-src>/gem5 ; scons build/ALPHA/gem5.debug
65#   % cd <path-to-src>/gem5/build/ALPHA; scons -u gem5.debug
66#
67#   The following two commands are equivalent and demonstrate building
68#   in a directory outside of the source tree.  The '-C' option tells
69#   scons to chdir to the specified directory to find this SConstruct
70#   file.
71#   % cd <path-to-src>/gem5 ; scons /local/foo/build/ALPHA/gem5.debug
72#   % cd /local/foo/build/ALPHA; scons -C <path-to-src>/gem5 gem5.debug
73#
74# You can use 'scons -H' to print scons options.  If you're in this
75# 'gem5' directory (or use -u or -C to tell scons where to find this
76# file), you can use 'scons -h' to print all the gem5-specific build
77# options as well.
78#
79###################################################
80
81# Check for recent-enough Python and SCons versions.
82try:
83    # Really old versions of scons only take two options for the
84    # function, so check once without the revision and once with the
85    # revision, the first instance will fail for stuff other than
86    # 0.98, and the second will fail for 0.98.0
87    EnsureSConsVersion(0, 98)
88    EnsureSConsVersion(0, 98, 1)
89except SystemExit, e:
90    print """
91For more details, see:
92    http://gem5.org/Dependencies
93"""
94    raise
95
96# We ensure the python version early because because python-config
97# requires python 2.5
98try:
99    EnsurePythonVersion(2, 5)
100except SystemExit, e:
101    print """
102You can use a non-default installation of the Python interpreter by
103rearranging your PATH so that scons finds the non-default 'python' and
104'python-config' first.
105
106For more details, see:
107    http://gem5.org/wiki/index.php/Using_a_non-default_Python_installation
108"""
109    raise
110
111# Global Python includes
112import os
113import re
114import subprocess
115import sys
116
117from os import mkdir, environ
118from os.path import abspath, basename, dirname, expanduser, normpath
119from os.path import exists,  isdir, isfile
120from os.path import join as joinpath, split as splitpath
121
122# SCons includes
123import SCons
124import SCons.Node
125
126extra_python_paths = [
127    Dir('src/python').srcnode().abspath, # gem5 includes
128    Dir('ext/ply').srcnode().abspath, # ply is used by several files
129    ]
130
131sys.path[1:1] = extra_python_paths
132
133from m5.util import compareVersions, readCommand
134from m5.util.terminal import get_termcap
135
136help_texts = {
137    "options" : "",
138    "global_vars" : "",
139    "local_vars" : ""
140}
141
142Export("help_texts")
143
144
145# There's a bug in scons in that (1) by default, the help texts from
146# AddOption() are supposed to be displayed when you type 'scons -h'
147# and (2) you can override the help displayed by 'scons -h' using the
148# Help() function, but these two features are incompatible: once
149# you've overridden the help text using Help(), there's no way to get
150# at the help texts from AddOptions.  See:
151#     http://scons.tigris.org/issues/show_bug.cgi?id=2356
152#     http://scons.tigris.org/issues/show_bug.cgi?id=2611
153# This hack lets us extract the help text from AddOptions and
154# re-inject it via Help().  Ideally someday this bug will be fixed and
155# we can just use AddOption directly.
156def AddLocalOption(*args, **kwargs):
157    col_width = 30
158
159    help = "  " + ", ".join(args)
160    if "help" in kwargs:
161        length = len(help)
162        if length >= col_width:
163            help += "\n" + " " * col_width
164        else:
165            help += " " * (col_width - length)
166        help += kwargs["help"]
167    help_texts["options"] += help + "\n"
168
169    AddOption(*args, **kwargs)
170
171AddLocalOption('--colors', dest='use_colors', action='store_true',
172               help="Add color to abbreviated scons output")
173AddLocalOption('--no-colors', dest='use_colors', action='store_false',
174               help="Don't add color to abbreviated scons output")
175AddLocalOption('--default', dest='default', type='string', action='store',
176               help='Override which build_opts file to use for defaults')
177AddLocalOption('--ignore-style', dest='ignore_style', action='store_true',
178               help='Disable style checking hooks')
179AddLocalOption('--no-lto', dest='no_lto', action='store_true',
180               help='Disable Link-Time Optimization for fast')
181AddLocalOption('--update-ref', dest='update_ref', action='store_true',
182               help='Update test reference outputs')
183AddLocalOption('--verbose', dest='verbose', action='store_true',
184               help='Print full tool command lines')
185
186termcap = get_termcap(GetOption('use_colors'))
187
188########################################################################
189#
190# Set up the main build environment.
191#
192########################################################################
193
194# export TERM so that clang reports errors in color
195use_vars = set([ 'AS', 'AR', 'CC', 'CXX', 'HOME', 'LD_LIBRARY_PATH',
196                 'LIBRARY_PATH', 'PATH', 'PKG_CONFIG_PATH', 'PROTOC',
197                 'PYTHONPATH', 'RANLIB', 'SWIG', 'TERM' ])
198
199use_prefixes = [
200    "M5",           # M5 configuration (e.g., path to kernels)
201    "DISTCC_",      # distcc (distributed compiler wrapper) configuration
202    "CCACHE_",      # ccache (caching compiler wrapper) configuration
203    "CCC_",         # clang static analyzer configuration
204    ]
205
206use_env = {}
207for key,val in os.environ.iteritems():
208    if key in use_vars or \
209            any([key.startswith(prefix) for prefix in use_prefixes]):
210        use_env[key] = val
211
212main = Environment(ENV=use_env)
213main.Decider('MD5-timestamp')
214main.root = Dir(".")         # The current directory (where this file lives).
215main.srcdir = Dir("src")     # The source directory
216
217main_dict_keys = main.Dictionary().keys()
218
219# Check that we have a C/C++ compiler
220if not ('CC' in main_dict_keys and 'CXX' in main_dict_keys):
221    print "No C++ compiler installed (package g++ on Ubuntu and RedHat)"
222    Exit(1)
223
224# Check that swig is present
225if not 'SWIG' in main_dict_keys:
226    print "swig is not installed (package swig on Ubuntu and RedHat)"
227    Exit(1)
228
229# add useful python code PYTHONPATH so it can be used by subprocesses
230# as well
231main.AppendENVPath('PYTHONPATH', extra_python_paths)
232
233########################################################################
234#
235# Mercurial Stuff.
236#
237# If the gem5 directory is a mercurial repository, we should do some
238# extra things.
239#
240########################################################################
241
242hgdir = main.root.Dir(".hg")
243
244mercurial_style_message = """
245You're missing the gem5 style hook, which automatically checks your code
246against the gem5 style rules on hg commit and qrefresh commands.  This
247script will now install the hook in your .hg/hgrc file.
248Press enter to continue, or ctrl-c to abort: """
249
250mercurial_style_hook = """
251# The following lines were automatically added by gem5/SConstruct
252# to provide the gem5 style-checking hooks
253[extensions]
254style = %s/util/style.py
255
256[hooks]
257pretxncommit.style = python:style.check_style
258pre-qrefresh.style = python:style.check_style
259# End of SConstruct additions
260
261""" % (main.root.abspath)
262
263mercurial_lib_not_found = """
264Mercurial libraries cannot be found, ignoring style hook.  If
265you are a gem5 developer, please fix this and run the style
266hook. It is important.
267"""
268
269# Check for style hook and prompt for installation if it's not there.
270# Skip this if --ignore-style was specified, there's no .hg dir to
271# install a hook in, or there's no interactive terminal to prompt.
272if not GetOption('ignore_style') and hgdir.exists() and sys.stdin.isatty():
273    style_hook = True
274    try:
275        from mercurial import ui
276        ui = ui.ui()
277        ui.readconfig(hgdir.File('hgrc').abspath)
278        style_hook = ui.config('hooks', 'pretxncommit.style', None) and \
279                     ui.config('hooks', 'pre-qrefresh.style', None)
280    except ImportError:
281        print mercurial_lib_not_found
282
283    if not style_hook:
284        print mercurial_style_message,
285        # continue unless user does ctrl-c/ctrl-d etc.
286        try:
287            raw_input()
288        except:
289            print "Input exception, exiting scons.\n"
290            sys.exit(1)
291        hgrc_path = '%s/.hg/hgrc' % main.root.abspath
292        print "Adding style hook to", hgrc_path, "\n"
293        try:
294            hgrc = open(hgrc_path, 'a')
295            hgrc.write(mercurial_style_hook)
296            hgrc.close()
297        except:
298            print "Error updating", hgrc_path
299            sys.exit(1)
300
301
302###################################################
303#
304# Figure out which configurations to set up based on the path(s) of
305# the target(s).
306#
307###################################################
308
309# Find default configuration & binary.
310Default(environ.get('M5_DEFAULT_BINARY', 'build/ALPHA/gem5.debug'))
311
312# helper function: find last occurrence of element in list
313def rfind(l, elt, offs = -1):
314    for i in range(len(l)+offs, 0, -1):
315        if l[i] == elt:
316            return i
317    raise ValueError, "element not found"
318
319# Take a list of paths (or SCons Nodes) and return a list with all
320# paths made absolute and ~-expanded.  Paths will be interpreted
321# relative to the launch directory unless a different root is provided
322def makePathListAbsolute(path_list, root=GetLaunchDir()):
323    return [abspath(joinpath(root, expanduser(str(p))))
324            for p in path_list]
325
326# Each target must have 'build' in the interior of the path; the
327# directory below this will determine the build parameters.  For
328# example, for target 'foo/bar/build/ALPHA_SE/arch/alpha/blah.do' we
329# recognize that ALPHA_SE specifies the configuration because it
330# follow 'build' in the build path.
331
332# The funky assignment to "[:]" is needed to replace the list contents
333# in place rather than reassign the symbol to a new list, which
334# doesn't work (obviously!).
335BUILD_TARGETS[:] = makePathListAbsolute(BUILD_TARGETS)
336
337# Generate a list of the unique build roots and configs that the
338# collected targets reference.
339variant_paths = []
340build_root = None
341for t in BUILD_TARGETS:
342    path_dirs = t.split('/')
343    try:
344        build_top = rfind(path_dirs, 'build', -2)
345    except:
346        print "Error: no non-leaf 'build' dir found on target path", t
347        Exit(1)
348    this_build_root = joinpath('/',*path_dirs[:build_top+1])
349    if not build_root:
350        build_root = this_build_root
351    else:
352        if this_build_root != build_root:
353            print "Error: build targets not under same build root\n"\
354                  "  %s\n  %s" % (build_root, this_build_root)
355            Exit(1)
356    variant_path = joinpath('/',*path_dirs[:build_top+2])
357    if variant_path not in variant_paths:
358        variant_paths.append(variant_path)
359
360# Make sure build_root exists (might not if this is the first build there)
361if not isdir(build_root):
362    mkdir(build_root)
363main['BUILDROOT'] = build_root
364
365Export('main')
366
367main.SConsignFile(joinpath(build_root, "sconsign"))
368
369# Default duplicate option is to use hard links, but this messes up
370# when you use emacs to edit a file in the target dir, as emacs moves
371# file to file~ then copies to file, breaking the link.  Symbolic
372# (soft) links work better.
373main.SetOption('duplicate', 'soft-copy')
374
375#
376# Set up global sticky variables... these are common to an entire build
377# tree (not specific to a particular build like ALPHA_SE)
378#
379
380global_vars_file = joinpath(build_root, 'variables.global')
381
382global_vars = Variables(global_vars_file, args=ARGUMENTS)
383
384global_vars.AddVariables(
385    ('CC', 'C compiler', environ.get('CC', main['CC'])),
386    ('CXX', 'C++ compiler', environ.get('CXX', main['CXX'])),
387    ('SWIG', 'SWIG tool', environ.get('SWIG', main['SWIG'])),
388    ('PROTOC', 'protoc tool', environ.get('PROTOC', 'protoc')),
389    ('BATCH', 'Use batch pool for build and tests', False),
390    ('BATCH_CMD', 'Batch pool submission command name', 'qdo'),
391    ('M5_BUILD_CACHE', 'Cache built objects in this directory', False),
392    ('EXTRAS', 'Add extra directories to the compilation', '')
393    )
394
395# Update main environment with values from ARGUMENTS & global_vars_file
396global_vars.Update(main)
397help_texts["global_vars"] += global_vars.GenerateHelpText(main)
398
399# Save sticky variable settings back to current variables file
400global_vars.Save(global_vars_file, main)
401
402# Parse EXTRAS variable to build list of all directories where we're
403# look for sources etc.  This list is exported as extras_dir_list.
404base_dir = main.srcdir.abspath
405if main['EXTRAS']:
406    extras_dir_list = makePathListAbsolute(main['EXTRAS'].split(':'))
407else:
408    extras_dir_list = []
409
410Export('base_dir')
411Export('extras_dir_list')
412
413# the ext directory should be on the #includes path
414main.Append(CPPPATH=[Dir('ext')])
415
416def strip_build_path(path, env):
417    path = str(path)
418    variant_base = env['BUILDROOT'] + os.path.sep
419    if path.startswith(variant_base):
420        path = path[len(variant_base):]
421    elif path.startswith('build/'):
422        path = path[6:]
423    return path
424
425# Generate a string of the form:
426#   common/path/prefix/src1, src2 -> tgt1, tgt2
427# to print while building.
428class Transform(object):
429    # all specific color settings should be here and nowhere else
430    tool_color = termcap.Normal
431    pfx_color = termcap.Yellow
432    srcs_color = termcap.Yellow + termcap.Bold
433    arrow_color = termcap.Blue + termcap.Bold
434    tgts_color = termcap.Yellow + termcap.Bold
435
436    def __init__(self, tool, max_sources=99):
437        self.format = self.tool_color + (" [%8s] " % tool) \
438                      + self.pfx_color + "%s" \
439                      + self.srcs_color + "%s" \
440                      + self.arrow_color + " -> " \
441                      + self.tgts_color + "%s" \
442                      + termcap.Normal
443        self.max_sources = max_sources
444
445    def __call__(self, target, source, env, for_signature=None):
446        # truncate source list according to max_sources param
447        source = source[0:self.max_sources]
448        def strip(f):
449            return strip_build_path(str(f), env)
450        if len(source) > 0:
451            srcs = map(strip, source)
452        else:
453            srcs = ['']
454        tgts = map(strip, target)
455        # surprisingly, os.path.commonprefix is a dumb char-by-char string
456        # operation that has nothing to do with paths.
457        com_pfx = os.path.commonprefix(srcs + tgts)
458        com_pfx_len = len(com_pfx)
459        if com_pfx:
460            # do some cleanup and sanity checking on common prefix
461            if com_pfx[-1] == ".":
462                # prefix matches all but file extension: ok
463                # back up one to change 'foo.cc -> o' to 'foo.cc -> .o'
464                com_pfx = com_pfx[0:-1]
465            elif com_pfx[-1] == "/":
466                # common prefix is directory path: OK
467                pass
468            else:
469                src0_len = len(srcs[0])
470                tgt0_len = len(tgts[0])
471                if src0_len == com_pfx_len:
472                    # source is a substring of target, OK
473                    pass
474                elif tgt0_len == com_pfx_len:
475                    # target is a substring of source, need to back up to
476                    # avoid empty string on RHS of arrow
477                    sep_idx = com_pfx.rfind(".")
478                    if sep_idx != -1:
479                        com_pfx = com_pfx[0:sep_idx]
480                    else:
481                        com_pfx = ''
482                elif src0_len > com_pfx_len and srcs[0][com_pfx_len] == ".":
483                    # still splitting at file extension: ok
484                    pass
485                else:
486                    # probably a fluke; ignore it
487                    com_pfx = ''
488        # recalculate length in case com_pfx was modified
489        com_pfx_len = len(com_pfx)
490        def fmt(files):
491            f = map(lambda s: s[com_pfx_len:], files)
492            return ', '.join(f)
493        return self.format % (com_pfx, fmt(srcs), fmt(tgts))
494
495Export('Transform')
496
497# enable the regression script to use the termcap
498main['TERMCAP'] = termcap
499
500if GetOption('verbose'):
501    def MakeAction(action, string, *args, **kwargs):
502        return Action(action, *args, **kwargs)
503else:
504    MakeAction = Action
505    main['CCCOMSTR']        = Transform("CC")
506    main['CXXCOMSTR']       = Transform("CXX")
507    main['ASCOMSTR']        = Transform("AS")
508    main['SWIGCOMSTR']      = Transform("SWIG")
509    main['ARCOMSTR']        = Transform("AR", 0)
510    main['LINKCOMSTR']      = Transform("LINK", 0)
511    main['RANLIBCOMSTR']    = Transform("RANLIB", 0)
512    main['M4COMSTR']        = Transform("M4")
513    main['SHCCCOMSTR']      = Transform("SHCC")
514    main['SHCXXCOMSTR']     = Transform("SHCXX")
515Export('MakeAction')
516
517# Initialize the Link-Time Optimization (LTO) flags
518main['LTO_CCFLAGS'] = []
519main['LTO_LDFLAGS'] = []
520
521# According to the readme, tcmalloc works best if the compiler doesn't
522# assume that we're using the builtin malloc and friends. These flags
523# are compiler-specific, so we need to set them after we detect which
524# compiler we're using.
525main['TCMALLOC_CCFLAGS'] = []
526
527CXX_version = readCommand([main['CXX'],'--version'], exception=False)
528CXX_V = readCommand([main['CXX'],'-V'], exception=False)
529
530main['GCC'] = CXX_version and CXX_version.find('g++') >= 0
531main['CLANG'] = CXX_version and CXX_version.find('clang') >= 0
532if main['GCC'] + main['CLANG'] > 1:
533    print 'Error: How can we have two at the same time?'
534    Exit(1)
535
536# Set up default C++ compiler flags
537if main['GCC'] or main['CLANG']:
538    # As gcc and clang share many flags, do the common parts here
539    main.Append(CCFLAGS=['-pipe'])
540    main.Append(CCFLAGS=['-fno-strict-aliasing'])
541    # Enable -Wall and then disable the few warnings that we
542    # consistently violate
543    main.Append(CCFLAGS=['-Wall', '-Wno-sign-compare', '-Wundef'])
544    # We always compile using C++11, but only gcc >= 4.7 and clang 3.1
545    # actually use that name, so we stick with c++0x
546    main.Append(CXXFLAGS=['-std=c++0x'])
547    # Add selected sanity checks from -Wextra
548    main.Append(CXXFLAGS=['-Wmissing-field-initializers',
549                          '-Woverloaded-virtual'])
550else:
551    print termcap.Yellow + termcap.Bold + 'Error' + termcap.Normal,
552    print "Don't know what compiler options to use for your compiler."
553    print termcap.Yellow + '       compiler:' + termcap.Normal, main['CXX']
554    print termcap.Yellow + '       version:' + termcap.Normal,
555    if not CXX_version:
556        print termcap.Yellow + termcap.Bold + "COMMAND NOT FOUND!" +\
557               termcap.Normal
558    else:
559        print CXX_version.replace('\n', '<nl>')
560    print "       If you're trying to use a compiler other than GCC"
561    print "       or clang, there appears to be something wrong with your"
562    print "       environment."
563    print "       "
564    print "       If you are trying to use a compiler other than those listed"
565    print "       above you will need to ease fix SConstruct and "
566    print "       src/SConscript to support that compiler."
567    Exit(1)
568
569if main['GCC']:
570    # Check for a supported version of gcc, >= 4.4 is needed for c++0x
571    # support. See http://gcc.gnu.org/projects/cxx0x.html for details
572    gcc_version = readCommand([main['CXX'], '-dumpversion'], exception=False)
573    if compareVersions(gcc_version, "4.4") < 0:
574        print 'Error: gcc version 4.4 or newer required.'
575        print '       Installed version:', gcc_version
576        Exit(1)
577
578    main['GCC_VERSION'] = gcc_version
579
580    # Check for versions with bugs
581    if not compareVersions(gcc_version, '4.4.1') or \
582       not compareVersions(gcc_version, '4.4.2'):
583        print 'Info: Tree vectorizer in GCC 4.4.1 & 4.4.2 is buggy, disabling.'
584        main.Append(CCFLAGS=['-fno-tree-vectorize'])
585
586    # LTO support is only really working properly from 4.6 and beyond
587    if compareVersions(gcc_version, '4.6') >= 0:
588        # Add the appropriate Link-Time Optimization (LTO) flags
589        # unless LTO is explicitly turned off. Note that these flags
590        # are only used by the fast target.
591        if not GetOption('no_lto'):
592            # Pass the LTO flag when compiling to produce GIMPLE
593            # output, we merely create the flags here and only append
594            # them later/
595            main['LTO_CCFLAGS'] = ['-flto=%d' % GetOption('num_jobs')]
596
597            # Use the same amount of jobs for LTO as we are running
598            # scons with, we hardcode the use of the linker plugin
599            # which requires either gold or GNU ld >= 2.21
600            main['LTO_LDFLAGS'] = ['-flto=%d' % GetOption('num_jobs'),
601                                   '-fuse-linker-plugin']
602
603    main.Append(TCMALLOC_CCFLAGS=['-fno-builtin-malloc', '-fno-builtin-calloc',
604                                  '-fno-builtin-realloc', '-fno-builtin-free'])
605
606elif main['CLANG']:
607    # Check for a supported version of clang, >= 2.9 is needed to
608    # support similar features as gcc 4.4. See
609    # http://clang.llvm.org/cxx_status.html for details
610    clang_version_re = re.compile(".* version (\d+\.\d+)")
611    clang_version_match = clang_version_re.search(CXX_version)
612    if (clang_version_match):
613        clang_version = clang_version_match.groups()[0]
614        if compareVersions(clang_version, "2.9") < 0:
615            print 'Error: clang version 2.9 or newer required.'
616            print '       Installed version:', clang_version
617            Exit(1)
618    else:
619        print 'Error: Unable to determine clang version.'
620        Exit(1)
621
622    # clang has a few additional warnings that we disable,
623    # tautological comparisons are allowed due to unsigned integers
624    # being compared to constants that happen to be 0, and extraneous
625    # parantheses are allowed due to Ruby's printing of the AST,
626    # finally self assignments are allowed as the generated CPU code
627    # is relying on this
628    main.Append(CCFLAGS=['-Wno-tautological-compare',
629                         '-Wno-parentheses',
630                         '-Wno-self-assign'])
631
632    main.Append(TCMALLOC_CCFLAGS=['-fno-builtin'])
633
634    # On Mac OS X/Darwin we need to also use libc++ (part of XCode) as
635    # opposed to libstdc++, as the later is dated.
636    if sys.platform == "darwin":
637        main.Append(CXXFLAGS=['-stdlib=libc++'])
638        main.Append(LIBS=['c++'])
639
640else:
641    print termcap.Yellow + termcap.Bold + 'Error' + termcap.Normal,
642    print "Don't know what compiler options to use for your compiler."
643    print termcap.Yellow + '       compiler:' + termcap.Normal, main['CXX']
644    print termcap.Yellow + '       version:' + termcap.Normal,
645    if not CXX_version:
646        print termcap.Yellow + termcap.Bold + "COMMAND NOT FOUND!" +\
647               termcap.Normal
648    else:
649        print CXX_version.replace('\n', '<nl>')
650    print "       If you're trying to use a compiler other than GCC"
651    print "       or clang, there appears to be something wrong with your"
652    print "       environment."
653    print "       "
654    print "       If you are trying to use a compiler other than those listed"
655    print "       above you will need to ease fix SConstruct and "
656    print "       src/SConscript to support that compiler."
657    Exit(1)
658
659# Set up common yacc/bison flags (needed for Ruby)
660main['YACCFLAGS'] = '-d'
661main['YACCHXXFILESUFFIX'] = '.hh'
662
663# Do this after we save setting back, or else we'll tack on an
664# extra 'qdo' every time we run scons.
665if main['BATCH']:
666    main['CC']     = main['BATCH_CMD'] + ' ' + main['CC']
667    main['CXX']    = main['BATCH_CMD'] + ' ' + main['CXX']
668    main['AS']     = main['BATCH_CMD'] + ' ' + main['AS']
669    main['AR']     = main['BATCH_CMD'] + ' ' + main['AR']
670    main['RANLIB'] = main['BATCH_CMD'] + ' ' + main['RANLIB']
671
672if sys.platform == 'cygwin':
673    # cygwin has some header file issues...
674    main.Append(CCFLAGS=["-Wno-uninitialized"])
675
676# Check for the protobuf compiler
677protoc_version = readCommand([main['PROTOC'], '--version'],
678                             exception='').split()
679
680# First two words should be "libprotoc x.y.z"
681if len(protoc_version) < 2 or protoc_version[0] != 'libprotoc':
682    print termcap.Yellow + termcap.Bold + \
683        'Warning: Protocol buffer compiler (protoc) not found.\n' + \
684        '         Please install protobuf-compiler for tracing support.' + \
685        termcap.Normal
686    main['PROTOC'] = False
687else:
688    # Based on the availability of the compress stream wrappers,
689    # require 2.1.0
690    min_protoc_version = '2.1.0'
691    if compareVersions(protoc_version[1], min_protoc_version) < 0:
692        print termcap.Yellow + termcap.Bold + \
693            'Warning: protoc version', min_protoc_version, \
694            'or newer required.\n' + \
695            '         Installed version:', protoc_version[1], \
696            termcap.Normal
697        main['PROTOC'] = False
698    else:
699        # Attempt to determine the appropriate include path and
700        # library path using pkg-config, that means we also need to
701        # check for pkg-config. Note that it is possible to use
702        # protobuf without the involvement of pkg-config. Later on we
703        # check go a library config check and at that point the test
704        # will fail if libprotobuf cannot be found.
705        if readCommand(['pkg-config', '--version'], exception=''):
706            try:
707                # Attempt to establish what linking flags to add for protobuf
708                # using pkg-config
709                main.ParseConfig('pkg-config --cflags --libs-only-L protobuf')
710            except:
711                print termcap.Yellow + termcap.Bold + \
712                    'Warning: pkg-config could not get protobuf flags.' + \
713                    termcap.Normal
714
715# Check for SWIG
716if not main.has_key('SWIG'):
717    print 'Error: SWIG utility not found.'
718    print '       Please install (see http://www.swig.org) and retry.'
719    Exit(1)
720
721# Check for appropriate SWIG version
722swig_version = readCommand([main['SWIG'], '-version'], exception='').split()
723# First 3 words should be "SWIG Version x.y.z"
724if len(swig_version) < 3 or \
725        swig_version[0] != 'SWIG' or swig_version[1] != 'Version':
726    print 'Error determining SWIG version.'
727    Exit(1)
728
729min_swig_version = '2.0.4'
730if compareVersions(swig_version[2], min_swig_version) < 0:
731    print 'Error: SWIG version', min_swig_version, 'or newer required.'
732    print '       Installed version:', swig_version[2]
733    Exit(1)
734
735# Set up SWIG flags & scanner
736swig_flags=Split('-c++ -python -modern -templatereduce $_CPPINCFLAGS')
737main.Append(SWIGFLAGS=swig_flags)
738
739# filter out all existing swig scanners, they mess up the dependency
740# stuff for some reason
741scanners = []
742for scanner in main['SCANNERS']:
743    skeys = scanner.skeys
744    if skeys == '.i':
745        continue
746
747    if isinstance(skeys, (list, tuple)) and '.i' in skeys:
748        continue
749
750    scanners.append(scanner)
751
752# add the new swig scanner that we like better
753from SCons.Scanner import ClassicCPP as CPPScanner
754swig_inc_re = '^[ \t]*[%,#][ \t]*(?:include|import)[ \t]*(<|")([^>"]+)(>|")'
755scanners.append(CPPScanner("SwigScan", [ ".i" ], "CPPPATH", swig_inc_re))
756
757# replace the scanners list that has what we want
758main['SCANNERS'] = scanners
759
760# Add a custom Check function to the Configure context so that we can
761# figure out if the compiler adds leading underscores to global
762# variables.  This is needed for the autogenerated asm files that we
763# use for embedding the python code.
764def CheckLeading(context):
765    context.Message("Checking for leading underscore in global variables...")
766    # 1) Define a global variable called x from asm so the C compiler
767    #    won't change the symbol at all.
768    # 2) Declare that variable.
769    # 3) Use the variable
770    #
771    # If the compiler prepends an underscore, this will successfully
772    # link because the external symbol 'x' will be called '_x' which
773    # was defined by the asm statement.  If the compiler does not
774    # prepend an underscore, this will not successfully link because
775    # '_x' will have been defined by assembly, while the C portion of
776    # the code will be trying to use 'x'
777    ret = context.TryLink('''
778        asm(".globl _x; _x: .byte 0");
779        extern int x;
780        int main() { return x; }
781        ''', extension=".c")
782    context.env.Append(LEADING_UNDERSCORE=ret)
783    context.Result(ret)
784    return ret
785
786# Add a custom Check function to test for structure members.
787def CheckMember(context, include, decl, member, include_quotes="<>"):
788    context.Message("Checking for member %s in %s..." %
789                    (member, decl))
790    text = """
791#include %(header)s
792int main(){
793  %(decl)s test;
794  (void)test.%(member)s;
795  return 0;
796};
797""" % { "header" : include_quotes[0] + include + include_quotes[1],
798        "decl" : decl,
799        "member" : member,
800        }
801
802    ret = context.TryCompile(text, extension=".cc")
803    context.Result(ret)
804    return ret
805
806# Platform-specific configuration.  Note again that we assume that all
807# builds under a given build root run on the same host platform.
808conf = Configure(main,
809                 conf_dir = joinpath(build_root, '.scons_config'),
810                 log_file = joinpath(build_root, 'scons_config.log'),
811                 custom_tests = {
812        'CheckLeading' : CheckLeading,
813        'CheckMember' : CheckMember,
814        })
815
816# Check for leading underscores.  Don't really need to worry either
817# way so don't need to check the return code.
818conf.CheckLeading()
819
820# Check if we should compile a 64 bit binary on Mac OS X/Darwin
821try:
822    import platform
823    uname = platform.uname()
824    if uname[0] == 'Darwin' and compareVersions(uname[2], '9.0.0') >= 0:
825        if int(readCommand('sysctl -n hw.cpu64bit_capable')[0]):
826            main.Append(CCFLAGS=['-arch', 'x86_64'])
827            main.Append(CFLAGS=['-arch', 'x86_64'])
828            main.Append(LINKFLAGS=['-arch', 'x86_64'])
829            main.Append(ASFLAGS=['-arch', 'x86_64'])
830except:
831    pass
832
833# Recent versions of scons substitute a "Null" object for Configure()
834# when configuration isn't necessary, e.g., if the "--help" option is
835# present.  Unfortuantely this Null object always returns false,
836# breaking all our configuration checks.  We replace it with our own
837# more optimistic null object that returns True instead.
838if not conf:
839    def NullCheck(*args, **kwargs):
840        return True
841
842    class NullConf:
843        def __init__(self, env):
844            self.env = env
845        def Finish(self):
846            return self.env
847        def __getattr__(self, mname):
848            return NullCheck
849
850    conf = NullConf(main)
851
852# Cache build files in the supplied directory.
853if main['M5_BUILD_CACHE']:
854    print 'Using build cache located at', main['M5_BUILD_CACHE']
855    CacheDir(main['M5_BUILD_CACHE'])
856
857# Find Python include and library directories for embedding the
858# interpreter. We rely on python-config to resolve the appropriate
859# includes and linker flags. ParseConfig does not seem to understand
860# the more exotic linker flags such as -Xlinker and -export-dynamic so
861# we add them explicitly below. If you want to link in an alternate
862# version of python, see above for instructions on how to invoke
863# scons with the appropriate PATH set.
864#
865# First we check if python2-config exists, else we use python-config
866python_config = readCommand(['which', 'python2-config'], exception='').strip()
867if not os.path.exists(python_config):
868    python_config = readCommand(['which', 'python-config'],
869                                exception='').strip()
870py_includes = readCommand([python_config, '--includes'],
871                          exception='').split()
872# Strip the -I from the include folders before adding them to the
873# CPPPATH
874main.Append(CPPPATH=map(lambda inc: inc[2:], py_includes))
875
876# Read the linker flags and split them into libraries and other link
877# flags. The libraries are added later through the call the CheckLib.
878py_ld_flags = readCommand([python_config, '--ldflags'], exception='').split()
879py_libs = []
880for lib in py_ld_flags:
881     if not lib.startswith('-l'):
882         main.Append(LINKFLAGS=[lib])
883     else:
884         lib = lib[2:]
885         if lib not in py_libs:
886             py_libs.append(lib)
887
888# verify that this stuff works
889if not conf.CheckHeader('Python.h', '<>'):
890    print "Error: can't find Python.h header in", py_includes
891    print "Install Python headers (package python-dev on Ubuntu and RedHat)"
892    Exit(1)
893
894for lib in py_libs:
895    if not conf.CheckLib(lib):
896        print "Error: can't find library %s required by python" % lib
897        Exit(1)
898
899# On Solaris you need to use libsocket for socket ops
900if not conf.CheckLibWithHeader(None, 'sys/socket.h', 'C++', 'accept(0,0,0);'):
901   if not conf.CheckLibWithHeader('socket', 'sys/socket.h', 'C++', 'accept(0,0,0);'):
902       print "Can't find library with socket calls (e.g. accept())"
903       Exit(1)
904
905# Check for zlib.  If the check passes, libz will be automatically
906# added to the LIBS environment variable.
907if not conf.CheckLibWithHeader('z', 'zlib.h', 'C++','zlibVersion();'):
908    print 'Error: did not find needed zlib compression library '\
909          'and/or zlib.h header file.'
910    print '       Please install zlib and try again.'
911    Exit(1)
912
913# If we have the protobuf compiler, also make sure we have the
914# development libraries. If the check passes, libprotobuf will be
915# automatically added to the LIBS environment variable. After
916# this, we can use the HAVE_PROTOBUF flag to determine if we have
917# got both protoc and libprotobuf available.
918main['HAVE_PROTOBUF'] = main['PROTOC'] and \
919    conf.CheckLibWithHeader('protobuf', 'google/protobuf/message.h',
920                            'C++', 'GOOGLE_PROTOBUF_VERIFY_VERSION;')
921
922# If we have the compiler but not the library, print another warning.
923if main['PROTOC'] and not main['HAVE_PROTOBUF']:
924    print termcap.Yellow + termcap.Bold + \
925        'Warning: did not find protocol buffer library and/or headers.\n' + \
926    '       Please install libprotobuf-dev for tracing support.' + \
927    termcap.Normal
928
929# Check for librt.
930have_posix_clock = \
931    conf.CheckLibWithHeader(None, 'time.h', 'C',
932                            'clock_nanosleep(0,0,NULL,NULL);') or \
933    conf.CheckLibWithHeader('rt', 'time.h', 'C',
934                            'clock_nanosleep(0,0,NULL,NULL);')
935
936have_posix_timers = \
937    conf.CheckLibWithHeader([None, 'rt'], [ 'time.h', 'signal.h' ], 'C',
938                            'timer_create(CLOCK_MONOTONIC, NULL, NULL);')
939
940if conf.CheckLib('tcmalloc'):
941    main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
942elif conf.CheckLib('tcmalloc_minimal'):
943    main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
944else:
945    print termcap.Yellow + termcap.Bold + \
946          "You can get a 12% performance improvement by installing tcmalloc "\
947          "(libgoogle-perftools-dev package on Ubuntu or RedHat)." + \
948          termcap.Normal
949
950if not have_posix_clock:
951    print "Can't find library for POSIX clocks."
952
953# Check for <fenv.h> (C99 FP environment control)
954have_fenv = conf.CheckHeader('fenv.h', '<>')
955if not have_fenv:
956    print "Warning: Header file <fenv.h> not found."
957    print "         This host has no IEEE FP rounding mode control."
958
959# Check if we should enable KVM-based hardware virtualization. The API
960# we rely on exists since version 2.6.36 of the kernel, but somehow
961# the KVM_API_VERSION does not reflect the change. We test for one of
962# the types as a fall back.
963have_kvm = conf.CheckHeader('linux/kvm.h', '<>') and \
964    conf.CheckTypeSize('struct kvm_xsave', '#include <linux/kvm.h>') != 0
965if not have_kvm:
966    print "Info: Compatible header file <linux/kvm.h> not found, " \
967        "disabling KVM support."
968
969# Check if the requested target ISA is compatible with the host
970def is_isa_kvm_compatible(isa):
971    isa_comp_table = {
972        "arm" : ( "armv7l" ),
973        "x86" : ( "x86_64" ),
974        }
975    try:
976        import platform
977        host_isa = platform.machine()
978    except:
979        print "Warning: Failed to determine host ISA."
980        return False
981
982    return host_isa in isa_comp_table.get(isa, [])
983
984
985# Check if the exclude_host attribute is available. We want this to
986# get accurate instruction counts in KVM.
987main['HAVE_PERF_ATTR_EXCLUDE_HOST'] = conf.CheckMember(
988    'linux/perf_event.h', 'struct perf_event_attr', 'exclude_host')
989
990
991######################################################################
992#
993# Finish the configuration
994#
995main = conf.Finish()
996
997######################################################################
998#
999# Collect all non-global variables
1000#
1001
1002# Define the universe of supported ISAs
1003all_isa_list = [ ]
1004Export('all_isa_list')
1005
1006class CpuModel(object):
1007    '''The CpuModel class encapsulates everything the ISA parser needs to
1008    know about a particular CPU model.'''
1009
1010    # Dict of available CPU model objects.  Accessible as CpuModel.dict.
1011    dict = {}
1012    list = []
1013    defaults = []
1014
1015    # Constructor.  Automatically adds models to CpuModel.dict.
1016    def __init__(self, name, filename, includes, strings, default=False):
1017        self.name = name           # name of model
1018        self.filename = filename   # filename for output exec code
1019        self.includes = includes   # include files needed in exec file
1020        # The 'strings' dict holds all the per-CPU symbols we can
1021        # substitute into templates etc.
1022        self.strings = strings
1023
1024        # This cpu is enabled by default
1025        self.default = default
1026
1027        # Add self to dict
1028        if name in CpuModel.dict:
1029            raise AttributeError, "CpuModel '%s' already registered" % name
1030        CpuModel.dict[name] = self
1031        CpuModel.list.append(name)
1032
1033Export('CpuModel')
1034
1035# Sticky variables get saved in the variables file so they persist from
1036# one invocation to the next (unless overridden, in which case the new
1037# value becomes sticky).
1038sticky_vars = Variables(args=ARGUMENTS)
1039Export('sticky_vars')
1040
1041# Sticky variables that should be exported
1042export_vars = []
1043Export('export_vars')
1044
1045# For Ruby
1046all_protocols = []
1047Export('all_protocols')
1048protocol_dirs = []
1049Export('protocol_dirs')
1050slicc_includes = []
1051Export('slicc_includes')
1052
1053# Walk the tree and execute all SConsopts scripts that wil add to the
1054# above variables
1055if GetOption('verbose'):
1056    print "Reading SConsopts"
1057for bdir in [ base_dir ] + extras_dir_list:
1058    if not isdir(bdir):
1059        print "Error: directory '%s' does not exist" % bdir
1060        Exit(1)
1061    for root, dirs, files in os.walk(bdir):
1062        if 'SConsopts' in files:
1063            if GetOption('verbose'):
1064                print "Reading", joinpath(root, 'SConsopts')
1065            SConscript(joinpath(root, 'SConsopts'))
1066
1067all_isa_list.sort()
1068
1069sticky_vars.AddVariables(
1070    EnumVariable('TARGET_ISA', 'Target ISA', 'alpha', all_isa_list),
1071    ListVariable('CPU_MODELS', 'CPU models',
1072                 sorted(n for n,m in CpuModel.dict.iteritems() if m.default),
1073                 sorted(CpuModel.list)),
1074    BoolVariable('EFENCE', 'Link with Electric Fence malloc debugger',
1075                 False),
1076    BoolVariable('SS_COMPATIBLE_FP',
1077                 'Make floating-point results compatible with SimpleScalar',
1078                 False),
1079    BoolVariable('USE_SSE2',
1080                 'Compile for SSE2 (-msse2) to get IEEE FP on x86 hosts',
1081                 False),
1082    BoolVariable('USE_POSIX_CLOCK', 'Use POSIX Clocks', have_posix_clock),
1083    BoolVariable('USE_FENV', 'Use <fenv.h> IEEE mode control', have_fenv),
1084    BoolVariable('CP_ANNOTATE', 'Enable critical path annotation capability', False),
1085    BoolVariable('USE_KVM', 'Enable hardware virtualized (KVM) CPU models', have_kvm),
1086    EnumVariable('PROTOCOL', 'Coherence protocol for Ruby', 'None',
1087                  all_protocols),
1088    )
1089
1090# These variables get exported to #defines in config/*.hh (see src/SConscript).
1091export_vars += ['USE_FENV', 'SS_COMPATIBLE_FP', 'TARGET_ISA', 'CP_ANNOTATE',
1092                'USE_POSIX_CLOCK', 'PROTOCOL', 'HAVE_PROTOBUF',
1093                'HAVE_PERF_ATTR_EXCLUDE_HOST']
1094
1095###################################################
1096#
1097# Define a SCons builder for configuration flag headers.
1098#
1099###################################################
1100
1101# This function generates a config header file that #defines the
1102# variable symbol to the current variable setting (0 or 1).  The source
1103# operands are the name of the variable and a Value node containing the
1104# value of the variable.
1105def build_config_file(target, source, env):
1106    (variable, value) = [s.get_contents() for s in source]
1107    f = file(str(target[0]), 'w')
1108    print >> f, '#define', variable, value
1109    f.close()
1110    return None
1111
1112# Combine the two functions into a scons Action object.
1113config_action = MakeAction(build_config_file, Transform("CONFIG H", 2))
1114
1115# The emitter munges the source & target node lists to reflect what
1116# we're really doing.
1117def config_emitter(target, source, env):
1118    # extract variable name from Builder arg
1119    variable = str(target[0])
1120    # True target is config header file
1121    target = joinpath('config', variable.lower() + '.hh')
1122    val = env[variable]
1123    if isinstance(val, bool):
1124        # Force value to 0/1
1125        val = int(val)
1126    elif isinstance(val, str):
1127        val = '"' + val + '"'
1128
1129    # Sources are variable name & value (packaged in SCons Value nodes)
1130    return ([target], [Value(variable), Value(val)])
1131
1132config_builder = Builder(emitter = config_emitter, action = config_action)
1133
1134main.Append(BUILDERS = { 'ConfigFile' : config_builder })
1135
1136# libelf build is shared across all configs in the build root.
1137main.SConscript('ext/libelf/SConscript',
1138                variant_dir = joinpath(build_root, 'libelf'))
1139
1140# gzstream build is shared across all configs in the build root.
1141main.SConscript('ext/gzstream/SConscript',
1142                variant_dir = joinpath(build_root, 'gzstream'))
1143
1144# libfdt build is shared across all configs in the build root.
1145main.SConscript('ext/libfdt/SConscript',
1146                variant_dir = joinpath(build_root, 'libfdt'))
1147
1148# fputils build is shared across all configs in the build root.
1149main.SConscript('ext/fputils/SConscript',
1150                variant_dir = joinpath(build_root, 'fputils'))
1151
1152# DRAMSim2 build is shared across all configs in the build root.
1153main.SConscript('ext/dramsim2/SConscript',
1154                variant_dir = joinpath(build_root, 'dramsim2'))
1155
1156###################################################
1157#
1158# This function is used to set up a directory with switching headers
1159#
1160###################################################
1161
1162main['ALL_ISA_LIST'] = all_isa_list
1163def make_switching_dir(dname, switch_headers, env):
1164    # Generate the header.  target[0] is the full path of the output
1165    # header to generate.  'source' is a dummy variable, since we get the
1166    # list of ISAs from env['ALL_ISA_LIST'].
1167    def gen_switch_hdr(target, source, env):
1168        fname = str(target[0])
1169        f = open(fname, 'w')
1170        isa = env['TARGET_ISA'].lower()
1171        print >>f, '#include "%s/%s/%s"' % (dname, isa, basename(fname))
1172        f.close()
1173
1174    # Build SCons Action object. 'varlist' specifies env vars that this
1175    # action depends on; when env['ALL_ISA_LIST'] changes these actions
1176    # should get re-executed.
1177    switch_hdr_action = MakeAction(gen_switch_hdr,
1178                          Transform("GENERATE"), varlist=['ALL_ISA_LIST'])
1179
1180    # Instantiate actions for each header
1181    for hdr in switch_headers:
1182        env.Command(hdr, [], switch_hdr_action)
1183Export('make_switching_dir')
1184
1185###################################################
1186#
1187# Define build environments for selected configurations.
1188#
1189###################################################
1190
1191for variant_path in variant_paths:
1192    if not GetOption('silent'):
1193        print "Building in", variant_path
1194
1195    # Make a copy of the build-root environment to use for this config.
1196    env = main.Clone()
1197    env['BUILDDIR'] = variant_path
1198
1199    # variant_dir is the tail component of build path, and is used to
1200    # determine the build parameters (e.g., 'ALPHA_SE')
1201    (build_root, variant_dir) = splitpath(variant_path)
1202
1203    # Set env variables according to the build directory config.
1204    sticky_vars.files = []
1205    # Variables for $BUILD_ROOT/$VARIANT_DIR are stored in
1206    # $BUILD_ROOT/variables/$VARIANT_DIR so you can nuke
1207    # $BUILD_ROOT/$VARIANT_DIR without losing your variables settings.
1208    current_vars_file = joinpath(build_root, 'variables', variant_dir)
1209    if isfile(current_vars_file):
1210        sticky_vars.files.append(current_vars_file)
1211        if not GetOption('silent'):
1212            print "Using saved variables file %s" % current_vars_file
1213    else:
1214        # Build dir-specific variables file doesn't exist.
1215
1216        # Make sure the directory is there so we can create it later
1217        opt_dir = dirname(current_vars_file)
1218        if not isdir(opt_dir):
1219            mkdir(opt_dir)
1220
1221        # Get default build variables from source tree.  Variables are
1222        # normally determined by name of $VARIANT_DIR, but can be
1223        # overridden by '--default=' arg on command line.
1224        default = GetOption('default')
1225        opts_dir = joinpath(main.root.abspath, 'build_opts')
1226        if default:
1227            default_vars_files = [joinpath(build_root, 'variables', default),
1228                                  joinpath(opts_dir, default)]
1229        else:
1230            default_vars_files = [joinpath(opts_dir, variant_dir)]
1231        existing_files = filter(isfile, default_vars_files)
1232        if existing_files:
1233            default_vars_file = existing_files[0]
1234            sticky_vars.files.append(default_vars_file)
1235            print "Variables file %s not found,\n  using defaults in %s" \
1236                  % (current_vars_file, default_vars_file)
1237        else:
1238            print "Error: cannot find variables file %s or " \
1239                  "default file(s) %s" \
1240                  % (current_vars_file, ' or '.join(default_vars_files))
1241            Exit(1)
1242
1243    # Apply current variable settings to env
1244    sticky_vars.Update(env)
1245
1246    help_texts["local_vars"] += \
1247        "Build variables for %s:\n" % variant_dir \
1248                 + sticky_vars.GenerateHelpText(env)
1249
1250    # Process variable settings.
1251
1252    if not have_fenv and env['USE_FENV']:
1253        print "Warning: <fenv.h> not available; " \
1254              "forcing USE_FENV to False in", variant_dir + "."
1255        env['USE_FENV'] = False
1256
1257    if not env['USE_FENV']:
1258        print "Warning: No IEEE FP rounding mode control in", variant_dir + "."
1259        print "         FP results may deviate slightly from other platforms."
1260
1261    if env['EFENCE']:
1262        env.Append(LIBS=['efence'])
1263
1264    if env['USE_KVM']:
1265        if not have_kvm:
1266            print "Warning: Can not enable KVM, host seems to lack KVM support"
1267            env['USE_KVM'] = False
1268        elif not have_posix_timers:
1269            print "Warning: Can not enable KVM, host seems to lack support " \
1270                "for POSIX timers"
1271            env['USE_KVM'] = False
1272        elif not is_isa_kvm_compatible(env['TARGET_ISA']):
1273            print "Info: KVM support disabled due to unsupported host and " \
1274                "target ISA combination"
1275            env['USE_KVM'] = False
1276
1277    # Warn about missing optional functionality
1278    if env['USE_KVM']:
1279        if not main['HAVE_PERF_ATTR_EXCLUDE_HOST']:
1280            print "Warning: perf_event headers lack support for the " \
1281                "exclude_host attribute. KVM instruction counts will " \
1282                "be inaccurate."
1283
1284    # Save sticky variable settings back to current variables file
1285    sticky_vars.Save(current_vars_file, env)
1286
1287    if env['USE_SSE2']:
1288        env.Append(CCFLAGS=['-msse2'])
1289
1290    # The src/SConscript file sets up the build rules in 'env' according
1291    # to the configured variables.  It returns a list of environments,
1292    # one for each variant build (debug, opt, etc.)
1293    envList = SConscript('src/SConscript', variant_dir = variant_path,
1294                         exports = 'env')
1295
1296    # Set up the regression tests for each build.
1297    for e in envList:
1298        SConscript('tests/SConscript',
1299                   variant_dir = joinpath(variant_path, 'tests', e.Label),
1300                   exports = { 'env' : e }, duplicate = False)
1301
1302# base help text
1303Help('''
1304Usage: scons [scons options] [build variables] [target(s)]
1305
1306Extra scons options:
1307%(options)s
1308
1309Global build variables:
1310%(global_vars)s
1311
1312%(local_vars)s
1313''' % help_texts)
1314