SConstruct revision 10066
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', 'PYTHONPATH',
197                 '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.match(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 = '1.3.34'
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# Older versions of swig do not play well with more recent versions of
736# gcc due to assumptions on implicit includes (cstddef) and use of
737# namespaces
738if main['GCC'] and compareVersions(gcc_version, '4.6') > 0 and \
739        compareVersions(swig_version[2], '2') < 0:
740    print '\n' + termcap.Yellow + termcap.Bold + \
741        'Warning: SWIG 1.x cause issues with gcc 4.6 and later.\n' + \
742        termcap.Normal + \
743        'Use SWIG 2.x to avoid assumptions on implicit includes\n' + \
744        'and use of namespaces\n'
745
746# Set up SWIG flags & scanner
747swig_flags=Split('-c++ -python -modern -templatereduce $_CPPINCFLAGS')
748main.Append(SWIGFLAGS=swig_flags)
749
750# filter out all existing swig scanners, they mess up the dependency
751# stuff for some reason
752scanners = []
753for scanner in main['SCANNERS']:
754    skeys = scanner.skeys
755    if skeys == '.i':
756        continue
757
758    if isinstance(skeys, (list, tuple)) and '.i' in skeys:
759        continue
760
761    scanners.append(scanner)
762
763# add the new swig scanner that we like better
764from SCons.Scanner import ClassicCPP as CPPScanner
765swig_inc_re = '^[ \t]*[%,#][ \t]*(?:include|import)[ \t]*(<|")([^>"]+)(>|")'
766scanners.append(CPPScanner("SwigScan", [ ".i" ], "CPPPATH", swig_inc_re))
767
768# replace the scanners list that has what we want
769main['SCANNERS'] = scanners
770
771# Add a custom Check function to the Configure context so that we can
772# figure out if the compiler adds leading underscores to global
773# variables.  This is needed for the autogenerated asm files that we
774# use for embedding the python code.
775def CheckLeading(context):
776    context.Message("Checking for leading underscore in global variables...")
777    # 1) Define a global variable called x from asm so the C compiler
778    #    won't change the symbol at all.
779    # 2) Declare that variable.
780    # 3) Use the variable
781    #
782    # If the compiler prepends an underscore, this will successfully
783    # link because the external symbol 'x' will be called '_x' which
784    # was defined by the asm statement.  If the compiler does not
785    # prepend an underscore, this will not successfully link because
786    # '_x' will have been defined by assembly, while the C portion of
787    # the code will be trying to use 'x'
788    ret = context.TryLink('''
789        asm(".globl _x; _x: .byte 0");
790        extern int x;
791        int main() { return x; }
792        ''', extension=".c")
793    context.env.Append(LEADING_UNDERSCORE=ret)
794    context.Result(ret)
795    return ret
796
797# Add a custom Check function to test for structure members.
798def CheckMember(context, include, decl, member, include_quotes="<>"):
799    context.Message("Checking for member %s in %s..." %
800                    (member, decl))
801    text = """
802#include %(header)s
803int main(){
804  %(decl)s test;
805  (void)test.%(member)s;
806  return 0;
807};
808""" % { "header" : include_quotes[0] + include + include_quotes[1],
809        "decl" : decl,
810        "member" : member,
811        }
812
813    ret = context.TryCompile(text, extension=".cc")
814    context.Result(ret)
815    return ret
816
817# Platform-specific configuration.  Note again that we assume that all
818# builds under a given build root run on the same host platform.
819conf = Configure(main,
820                 conf_dir = joinpath(build_root, '.scons_config'),
821                 log_file = joinpath(build_root, 'scons_config.log'),
822                 custom_tests = {
823        'CheckLeading' : CheckLeading,
824        'CheckMember' : CheckMember,
825        })
826
827# Check for leading underscores.  Don't really need to worry either
828# way so don't need to check the return code.
829conf.CheckLeading()
830
831# Check if we should compile a 64 bit binary on Mac OS X/Darwin
832try:
833    import platform
834    uname = platform.uname()
835    if uname[0] == 'Darwin' and compareVersions(uname[2], '9.0.0') >= 0:
836        if int(readCommand('sysctl -n hw.cpu64bit_capable')[0]):
837            main.Append(CCFLAGS=['-arch', 'x86_64'])
838            main.Append(CFLAGS=['-arch', 'x86_64'])
839            main.Append(LINKFLAGS=['-arch', 'x86_64'])
840            main.Append(ASFLAGS=['-arch', 'x86_64'])
841except:
842    pass
843
844# Recent versions of scons substitute a "Null" object for Configure()
845# when configuration isn't necessary, e.g., if the "--help" option is
846# present.  Unfortuantely this Null object always returns false,
847# breaking all our configuration checks.  We replace it with our own
848# more optimistic null object that returns True instead.
849if not conf:
850    def NullCheck(*args, **kwargs):
851        return True
852
853    class NullConf:
854        def __init__(self, env):
855            self.env = env
856        def Finish(self):
857            return self.env
858        def __getattr__(self, mname):
859            return NullCheck
860
861    conf = NullConf(main)
862
863# Cache build files in the supplied directory.
864if main['M5_BUILD_CACHE']:
865    print 'Using build cache located at', main['M5_BUILD_CACHE']
866    CacheDir(main['M5_BUILD_CACHE'])
867
868# Find Python include and library directories for embedding the
869# interpreter. We rely on python-config to resolve the appropriate
870# includes and linker flags. ParseConfig does not seem to understand
871# the more exotic linker flags such as -Xlinker and -export-dynamic so
872# we add them explicitly below. If you want to link in an alternate
873# version of python, see above for instructions on how to invoke
874# scons with the appropriate PATH set.
875py_includes = readCommand(['python-config', '--includes'],
876                          exception='').split()
877# Strip the -I from the include folders before adding them to the
878# CPPPATH
879main.Append(CPPPATH=map(lambda inc: inc[2:], py_includes))
880
881# Read the linker flags and split them into libraries and other link
882# flags. The libraries are added later through the call the CheckLib.
883py_ld_flags = readCommand(['python-config', '--ldflags'], exception='').split()
884py_libs = []
885for lib in py_ld_flags:
886     if not lib.startswith('-l'):
887         main.Append(LINKFLAGS=[lib])
888     else:
889         lib = lib[2:]
890         if lib not in py_libs:
891             py_libs.append(lib)
892
893# verify that this stuff works
894if not conf.CheckHeader('Python.h', '<>'):
895    print "Error: can't find Python.h header in", py_includes
896    print "Install Python headers (package python-dev on Ubuntu and RedHat)"
897    Exit(1)
898
899for lib in py_libs:
900    if not conf.CheckLib(lib):
901        print "Error: can't find library %s required by python" % lib
902        Exit(1)
903
904# On Solaris you need to use libsocket for socket ops
905if not conf.CheckLibWithHeader(None, 'sys/socket.h', 'C++', 'accept(0,0,0);'):
906   if not conf.CheckLibWithHeader('socket', 'sys/socket.h', 'C++', 'accept(0,0,0);'):
907       print "Can't find library with socket calls (e.g. accept())"
908       Exit(1)
909
910# Check for zlib.  If the check passes, libz will be automatically
911# added to the LIBS environment variable.
912if not conf.CheckLibWithHeader('z', 'zlib.h', 'C++','zlibVersion();'):
913    print 'Error: did not find needed zlib compression library '\
914          'and/or zlib.h header file.'
915    print '       Please install zlib and try again.'
916    Exit(1)
917
918# If we have the protobuf compiler, also make sure we have the
919# development libraries. If the check passes, libprotobuf will be
920# automatically added to the LIBS environment variable. After
921# this, we can use the HAVE_PROTOBUF flag to determine if we have
922# got both protoc and libprotobuf available.
923main['HAVE_PROTOBUF'] = main['PROTOC'] and \
924    conf.CheckLibWithHeader('protobuf', 'google/protobuf/message.h',
925                            'C++', 'GOOGLE_PROTOBUF_VERIFY_VERSION;')
926
927# If we have the compiler but not the library, print another warning.
928if main['PROTOC'] and not main['HAVE_PROTOBUF']:
929    print termcap.Yellow + termcap.Bold + \
930        'Warning: did not find protocol buffer library and/or headers.\n' + \
931    '       Please install libprotobuf-dev for tracing support.' + \
932    termcap.Normal
933
934# Check for librt.
935have_posix_clock = \
936    conf.CheckLibWithHeader(None, 'time.h', 'C',
937                            'clock_nanosleep(0,0,NULL,NULL);') or \
938    conf.CheckLibWithHeader('rt', 'time.h', 'C',
939                            'clock_nanosleep(0,0,NULL,NULL);')
940
941have_posix_timers = \
942    conf.CheckLibWithHeader([None, 'rt'], [ 'time.h', 'signal.h' ], 'C',
943                            'timer_create(CLOCK_MONOTONIC, NULL, NULL);')
944
945if conf.CheckLib('tcmalloc'):
946    main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
947elif conf.CheckLib('tcmalloc_minimal'):
948    main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
949else:
950    print termcap.Yellow + termcap.Bold + \
951          "You can get a 12% performance improvement by installing tcmalloc "\
952          "(libgoogle-perftools-dev package on Ubuntu or RedHat)." + \
953          termcap.Normal
954
955if not have_posix_clock:
956    print "Can't find library for POSIX clocks."
957
958# Check for <fenv.h> (C99 FP environment control)
959have_fenv = conf.CheckHeader('fenv.h', '<>')
960if not have_fenv:
961    print "Warning: Header file <fenv.h> not found."
962    print "         This host has no IEEE FP rounding mode control."
963
964# Check if we should enable KVM-based hardware virtualization. The API
965# we rely on exists since version 2.6.36 of the kernel, but somehow
966# the KVM_API_VERSION does not reflect the change. We test for one of
967# the types as a fall back.
968have_kvm = conf.CheckHeader('linux/kvm.h', '<>') and \
969    conf.CheckTypeSize('struct kvm_xsave', '#include <linux/kvm.h>') != 0
970if not have_kvm:
971    print "Info: Compatible header file <linux/kvm.h> not found, " \
972        "disabling KVM support."
973
974# Check if the requested target ISA is compatible with the host
975def is_isa_kvm_compatible(isa):
976    isa_comp_table = {
977        "arm" : ( "armv7l" ),
978        "x86" : ( "x86_64" ),
979        }
980    try:
981        import platform
982        host_isa = platform.machine()
983    except:
984        print "Warning: Failed to determine host ISA."
985        return False
986
987    return host_isa in isa_comp_table.get(isa, [])
988
989
990# Check if the exclude_host attribute is available. We want this to
991# get accurate instruction counts in KVM.
992main['HAVE_PERF_ATTR_EXCLUDE_HOST'] = conf.CheckMember(
993    'linux/perf_event.h', 'struct perf_event_attr', 'exclude_host')
994
995
996######################################################################
997#
998# Finish the configuration
999#
1000main = conf.Finish()
1001
1002######################################################################
1003#
1004# Collect all non-global variables
1005#
1006
1007# Define the universe of supported ISAs
1008all_isa_list = [ ]
1009Export('all_isa_list')
1010
1011class CpuModel(object):
1012    '''The CpuModel class encapsulates everything the ISA parser needs to
1013    know about a particular CPU model.'''
1014
1015    # Dict of available CPU model objects.  Accessible as CpuModel.dict.
1016    dict = {}
1017    list = []
1018    defaults = []
1019
1020    # Constructor.  Automatically adds models to CpuModel.dict.
1021    def __init__(self, name, filename, includes, strings, default=False):
1022        self.name = name           # name of model
1023        self.filename = filename   # filename for output exec code
1024        self.includes = includes   # include files needed in exec file
1025        # The 'strings' dict holds all the per-CPU symbols we can
1026        # substitute into templates etc.
1027        self.strings = strings
1028
1029        # This cpu is enabled by default
1030        self.default = default
1031
1032        # Add self to dict
1033        if name in CpuModel.dict:
1034            raise AttributeError, "CpuModel '%s' already registered" % name
1035        CpuModel.dict[name] = self
1036        CpuModel.list.append(name)
1037
1038Export('CpuModel')
1039
1040# Sticky variables get saved in the variables file so they persist from
1041# one invocation to the next (unless overridden, in which case the new
1042# value becomes sticky).
1043sticky_vars = Variables(args=ARGUMENTS)
1044Export('sticky_vars')
1045
1046# Sticky variables that should be exported
1047export_vars = []
1048Export('export_vars')
1049
1050# For Ruby
1051all_protocols = []
1052Export('all_protocols')
1053protocol_dirs = []
1054Export('protocol_dirs')
1055slicc_includes = []
1056Export('slicc_includes')
1057
1058# Walk the tree and execute all SConsopts scripts that wil add to the
1059# above variables
1060if not GetOption('verbose'):
1061    print "Reading SConsopts"
1062for bdir in [ base_dir ] + extras_dir_list:
1063    if not isdir(bdir):
1064        print "Error: directory '%s' does not exist" % bdir
1065        Exit(1)
1066    for root, dirs, files in os.walk(bdir):
1067        if 'SConsopts' in files:
1068            if GetOption('verbose'):
1069                print "Reading", joinpath(root, 'SConsopts')
1070            SConscript(joinpath(root, 'SConsopts'))
1071
1072all_isa_list.sort()
1073
1074sticky_vars.AddVariables(
1075    EnumVariable('TARGET_ISA', 'Target ISA', 'alpha', all_isa_list),
1076    ListVariable('CPU_MODELS', 'CPU models',
1077                 sorted(n for n,m in CpuModel.dict.iteritems() if m.default),
1078                 sorted(CpuModel.list)),
1079    BoolVariable('EFENCE', 'Link with Electric Fence malloc debugger',
1080                 False),
1081    BoolVariable('SS_COMPATIBLE_FP',
1082                 'Make floating-point results compatible with SimpleScalar',
1083                 False),
1084    BoolVariable('USE_SSE2',
1085                 'Compile for SSE2 (-msse2) to get IEEE FP on x86 hosts',
1086                 False),
1087    BoolVariable('USE_POSIX_CLOCK', 'Use POSIX Clocks', have_posix_clock),
1088    BoolVariable('USE_FENV', 'Use <fenv.h> IEEE mode control', have_fenv),
1089    BoolVariable('CP_ANNOTATE', 'Enable critical path annotation capability', False),
1090    BoolVariable('USE_KVM', 'Enable hardware virtualized (KVM) CPU models', have_kvm),
1091    EnumVariable('PROTOCOL', 'Coherence protocol for Ruby', 'None',
1092                  all_protocols),
1093    )
1094
1095# These variables get exported to #defines in config/*.hh (see src/SConscript).
1096export_vars += ['USE_FENV', 'SS_COMPATIBLE_FP', 'TARGET_ISA', 'CP_ANNOTATE',
1097                'USE_POSIX_CLOCK', 'PROTOCOL', 'HAVE_PROTOBUF',
1098                'HAVE_PERF_ATTR_EXCLUDE_HOST']
1099
1100###################################################
1101#
1102# Define a SCons builder for configuration flag headers.
1103#
1104###################################################
1105
1106# This function generates a config header file that #defines the
1107# variable symbol to the current variable setting (0 or 1).  The source
1108# operands are the name of the variable and a Value node containing the
1109# value of the variable.
1110def build_config_file(target, source, env):
1111    (variable, value) = [s.get_contents() for s in source]
1112    f = file(str(target[0]), 'w')
1113    print >> f, '#define', variable, value
1114    f.close()
1115    return None
1116
1117# Combine the two functions into a scons Action object.
1118config_action = MakeAction(build_config_file, Transform("CONFIG H", 2))
1119
1120# The emitter munges the source & target node lists to reflect what
1121# we're really doing.
1122def config_emitter(target, source, env):
1123    # extract variable name from Builder arg
1124    variable = str(target[0])
1125    # True target is config header file
1126    target = joinpath('config', variable.lower() + '.hh')
1127    val = env[variable]
1128    if isinstance(val, bool):
1129        # Force value to 0/1
1130        val = int(val)
1131    elif isinstance(val, str):
1132        val = '"' + val + '"'
1133
1134    # Sources are variable name & value (packaged in SCons Value nodes)
1135    return ([target], [Value(variable), Value(val)])
1136
1137config_builder = Builder(emitter = config_emitter, action = config_action)
1138
1139main.Append(BUILDERS = { 'ConfigFile' : config_builder })
1140
1141# libelf build is shared across all configs in the build root.
1142main.SConscript('ext/libelf/SConscript',
1143                variant_dir = joinpath(build_root, 'libelf'))
1144
1145# gzstream build is shared across all configs in the build root.
1146main.SConscript('ext/gzstream/SConscript',
1147                variant_dir = joinpath(build_root, 'gzstream'))
1148
1149# libfdt build is shared across all configs in the build root.
1150main.SConscript('ext/libfdt/SConscript',
1151                variant_dir = joinpath(build_root, 'libfdt'))
1152
1153# fputils build is shared across all configs in the build root.
1154main.SConscript('ext/fputils/SConscript',
1155                variant_dir = joinpath(build_root, 'fputils'))
1156
1157# DRAMSim2 build is shared across all configs in the build root.
1158main.SConscript('ext/dramsim2/SConscript',
1159                variant_dir = joinpath(build_root, 'dramsim2'))
1160
1161###################################################
1162#
1163# This function is used to set up a directory with switching headers
1164#
1165###################################################
1166
1167main['ALL_ISA_LIST'] = all_isa_list
1168def make_switching_dir(dname, switch_headers, env):
1169    # Generate the header.  target[0] is the full path of the output
1170    # header to generate.  'source' is a dummy variable, since we get the
1171    # list of ISAs from env['ALL_ISA_LIST'].
1172    def gen_switch_hdr(target, source, env):
1173        fname = str(target[0])
1174        f = open(fname, 'w')
1175        isa = env['TARGET_ISA'].lower()
1176        print >>f, '#include "%s/%s/%s"' % (dname, isa, basename(fname))
1177        f.close()
1178
1179    # Build SCons Action object. 'varlist' specifies env vars that this
1180    # action depends on; when env['ALL_ISA_LIST'] changes these actions
1181    # should get re-executed.
1182    switch_hdr_action = MakeAction(gen_switch_hdr,
1183                          Transform("GENERATE"), varlist=['ALL_ISA_LIST'])
1184
1185    # Instantiate actions for each header
1186    for hdr in switch_headers:
1187        env.Command(hdr, [], switch_hdr_action)
1188Export('make_switching_dir')
1189
1190###################################################
1191#
1192# Define build environments for selected configurations.
1193#
1194###################################################
1195
1196for variant_path in variant_paths:
1197    print "Building in", variant_path
1198
1199    # Make a copy of the build-root environment to use for this config.
1200    env = main.Clone()
1201    env['BUILDDIR'] = variant_path
1202
1203    # variant_dir is the tail component of build path, and is used to
1204    # determine the build parameters (e.g., 'ALPHA_SE')
1205    (build_root, variant_dir) = splitpath(variant_path)
1206
1207    # Set env variables according to the build directory config.
1208    sticky_vars.files = []
1209    # Variables for $BUILD_ROOT/$VARIANT_DIR are stored in
1210    # $BUILD_ROOT/variables/$VARIANT_DIR so you can nuke
1211    # $BUILD_ROOT/$VARIANT_DIR without losing your variables settings.
1212    current_vars_file = joinpath(build_root, 'variables', variant_dir)
1213    if isfile(current_vars_file):
1214        sticky_vars.files.append(current_vars_file)
1215        print "Using saved variables file %s" % current_vars_file
1216    else:
1217        # Build dir-specific variables file doesn't exist.
1218
1219        # Make sure the directory is there so we can create it later
1220        opt_dir = dirname(current_vars_file)
1221        if not isdir(opt_dir):
1222            mkdir(opt_dir)
1223
1224        # Get default build variables from source tree.  Variables are
1225        # normally determined by name of $VARIANT_DIR, but can be
1226        # overridden by '--default=' arg on command line.
1227        default = GetOption('default')
1228        opts_dir = joinpath(main.root.abspath, 'build_opts')
1229        if default:
1230            default_vars_files = [joinpath(build_root, 'variables', default),
1231                                  joinpath(opts_dir, default)]
1232        else:
1233            default_vars_files = [joinpath(opts_dir, variant_dir)]
1234        existing_files = filter(isfile, default_vars_files)
1235        if existing_files:
1236            default_vars_file = existing_files[0]
1237            sticky_vars.files.append(default_vars_file)
1238            print "Variables file %s not found,\n  using defaults in %s" \
1239                  % (current_vars_file, default_vars_file)
1240        else:
1241            print "Error: cannot find variables file %s or " \
1242                  "default file(s) %s" \
1243                  % (current_vars_file, ' or '.join(default_vars_files))
1244            Exit(1)
1245
1246    # Apply current variable settings to env
1247    sticky_vars.Update(env)
1248
1249    help_texts["local_vars"] += \
1250        "Build variables for %s:\n" % variant_dir \
1251                 + sticky_vars.GenerateHelpText(env)
1252
1253    # Process variable settings.
1254
1255    if not have_fenv and env['USE_FENV']:
1256        print "Warning: <fenv.h> not available; " \
1257              "forcing USE_FENV to False in", variant_dir + "."
1258        env['USE_FENV'] = False
1259
1260    if not env['USE_FENV']:
1261        print "Warning: No IEEE FP rounding mode control in", variant_dir + "."
1262        print "         FP results may deviate slightly from other platforms."
1263
1264    if env['EFENCE']:
1265        env.Append(LIBS=['efence'])
1266
1267    if env['USE_KVM']:
1268        if not have_kvm:
1269            print "Warning: Can not enable KVM, host seems to lack KVM support"
1270            env['USE_KVM'] = False
1271        elif not have_posix_timers:
1272            print "Warning: Can not enable KVM, host seems to lack support " \
1273                "for POSIX timers"
1274            env['USE_KVM'] = False
1275        elif not is_isa_kvm_compatible(env['TARGET_ISA']):
1276            print "Info: KVM support disabled due to unsupported host and " \
1277                "target ISA combination"
1278            env['USE_KVM'] = False
1279
1280    # Warn about missing optional functionality
1281    if env['USE_KVM']:
1282        if not main['HAVE_PERF_ATTR_EXCLUDE_HOST']:
1283            print "Warning: perf_event headers lack support for the " \
1284                "exclude_host attribute. KVM instruction counts will " \
1285                "be inaccurate."
1286
1287    # Save sticky variable settings back to current variables file
1288    sticky_vars.Save(current_vars_file, env)
1289
1290    if env['USE_SSE2']:
1291        env.Append(CCFLAGS=['-msse2'])
1292
1293    # The src/SConscript file sets up the build rules in 'env' according
1294    # to the configured variables.  It returns a list of environments,
1295    # one for each variant build (debug, opt, etc.)
1296    envList = SConscript('src/SConscript', variant_dir = variant_path,
1297                         exports = 'env')
1298
1299    # Set up the regression tests for each build.
1300    for e in envList:
1301        SConscript('tests/SConscript',
1302                   variant_dir = joinpath(variant_path, 'tests', e.Label),
1303                   exports = { 'env' : e }, duplicate = False)
1304
1305# base help text
1306Help('''
1307Usage: scons [scons options] [build variables] [target(s)]
1308
1309Extra scons options:
1310%(options)s
1311
1312Global build variables:
1313%(global_vars)s
1314
1315%(local_vars)s
1316''' % help_texts)
1317