SConstruct revision 10458:64809024b924
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 itertools
113import os
114import re
115import subprocess
116import sys
117
118from os import mkdir, environ
119from os.path import abspath, basename, dirname, expanduser, normpath
120from os.path import exists,  isdir, isfile
121from os.path import join as joinpath, split as splitpath
122
123# SCons includes
124import SCons
125import SCons.Node
126
127extra_python_paths = [
128    Dir('src/python').srcnode().abspath, # gem5 includes
129    Dir('ext/ply').srcnode().abspath, # ply is used by several files
130    ]
131
132sys.path[1:1] = extra_python_paths
133
134from m5.util import compareVersions, readCommand
135from m5.util.terminal import get_termcap
136
137help_texts = {
138    "options" : "",
139    "global_vars" : "",
140    "local_vars" : ""
141}
142
143Export("help_texts")
144
145
146# There's a bug in scons in that (1) by default, the help texts from
147# AddOption() are supposed to be displayed when you type 'scons -h'
148# and (2) you can override the help displayed by 'scons -h' using the
149# Help() function, but these two features are incompatible: once
150# you've overridden the help text using Help(), there's no way to get
151# at the help texts from AddOptions.  See:
152#     http://scons.tigris.org/issues/show_bug.cgi?id=2356
153#     http://scons.tigris.org/issues/show_bug.cgi?id=2611
154# This hack lets us extract the help text from AddOptions and
155# re-inject it via Help().  Ideally someday this bug will be fixed and
156# we can just use AddOption directly.
157def AddLocalOption(*args, **kwargs):
158    col_width = 30
159
160    help = "  " + ", ".join(args)
161    if "help" in kwargs:
162        length = len(help)
163        if length >= col_width:
164            help += "\n" + " " * col_width
165        else:
166            help += " " * (col_width - length)
167        help += kwargs["help"]
168    help_texts["options"] += help + "\n"
169
170    AddOption(*args, **kwargs)
171
172AddLocalOption('--colors', dest='use_colors', action='store_true',
173               help="Add color to abbreviated scons output")
174AddLocalOption('--no-colors', dest='use_colors', action='store_false',
175               help="Don't add color to abbreviated scons output")
176AddLocalOption('--with-cxx-config', dest='with_cxx_config',
177               action='store_true',
178               help="Build with support for C++-based configuration")
179AddLocalOption('--default', dest='default', type='string', action='store',
180               help='Override which build_opts file to use for defaults')
181AddLocalOption('--ignore-style', dest='ignore_style', action='store_true',
182               help='Disable style checking hooks')
183AddLocalOption('--no-lto', dest='no_lto', action='store_true',
184               help='Disable Link-Time Optimization for fast')
185AddLocalOption('--update-ref', dest='update_ref', action='store_true',
186               help='Update test reference outputs')
187AddLocalOption('--verbose', dest='verbose', action='store_true',
188               help='Print full tool command lines')
189AddLocalOption('--without-python', dest='without_python',
190               action='store_true',
191               help='Build without Python configuration support')
192AddLocalOption('--without-tcmalloc', dest='without_tcmalloc',
193               action='store_true',
194               help='Disable linking against tcmalloc')
195AddLocalOption('--with-ubsan', dest='with_ubsan', action='store_true',
196               help='Build with Undefined Behavior Sanitizer if available')
197
198termcap = get_termcap(GetOption('use_colors'))
199
200########################################################################
201#
202# Set up the main build environment.
203#
204########################################################################
205
206# export TERM so that clang reports errors in color
207use_vars = set([ 'AS', 'AR', 'CC', 'CXX', 'HOME', 'LD_LIBRARY_PATH',
208                 'LIBRARY_PATH', 'PATH', 'PKG_CONFIG_PATH', 'PROTOC',
209                 'PYTHONPATH', 'RANLIB', 'SWIG', 'TERM' ])
210
211use_prefixes = [
212    "M5",           # M5 configuration (e.g., path to kernels)
213    "DISTCC_",      # distcc (distributed compiler wrapper) configuration
214    "CCACHE_",      # ccache (caching compiler wrapper) configuration
215    "CCC_",         # clang static analyzer configuration
216    ]
217
218use_env = {}
219for key,val in os.environ.iteritems():
220    if key in use_vars or \
221            any([key.startswith(prefix) for prefix in use_prefixes]):
222        use_env[key] = val
223
224main = Environment(ENV=use_env)
225main.Decider('MD5-timestamp')
226main.root = Dir(".")         # The current directory (where this file lives).
227main.srcdir = Dir("src")     # The source directory
228
229main_dict_keys = main.Dictionary().keys()
230
231# Check that we have a C/C++ compiler
232if not ('CC' in main_dict_keys and 'CXX' in main_dict_keys):
233    print "No C++ compiler installed (package g++ on Ubuntu and RedHat)"
234    Exit(1)
235
236# Check that swig is present
237if not 'SWIG' in main_dict_keys:
238    print "swig is not installed (package swig on Ubuntu and RedHat)"
239    Exit(1)
240
241# add useful python code PYTHONPATH so it can be used by subprocesses
242# as well
243main.AppendENVPath('PYTHONPATH', extra_python_paths)
244
245########################################################################
246#
247# Mercurial Stuff.
248#
249# If the gem5 directory is a mercurial repository, we should do some
250# extra things.
251#
252########################################################################
253
254hgdir = main.root.Dir(".hg")
255
256mercurial_style_message = """
257You're missing the gem5 style hook, which automatically checks your code
258against the gem5 style rules on hg commit and qrefresh commands.  This
259script will now install the hook in your .hg/hgrc file.
260Press enter to continue, or ctrl-c to abort: """
261
262mercurial_style_hook = """
263# The following lines were automatically added by gem5/SConstruct
264# to provide the gem5 style-checking hooks
265[extensions]
266style = %s/util/style.py
267
268[hooks]
269pretxncommit.style = python:style.check_style
270pre-qrefresh.style = python:style.check_style
271# End of SConstruct additions
272
273""" % (main.root.abspath)
274
275mercurial_lib_not_found = """
276Mercurial libraries cannot be found, ignoring style hook.  If
277you are a gem5 developer, please fix this and run the style
278hook. It is important.
279"""
280
281# Check for style hook and prompt for installation if it's not there.
282# Skip this if --ignore-style was specified, there's no .hg dir to
283# install a hook in, or there's no interactive terminal to prompt.
284if not GetOption('ignore_style') and hgdir.exists() and sys.stdin.isatty():
285    style_hook = True
286    try:
287        from mercurial import ui
288        ui = ui.ui()
289        ui.readconfig(hgdir.File('hgrc').abspath)
290        style_hook = ui.config('hooks', 'pretxncommit.style', None) and \
291                     ui.config('hooks', 'pre-qrefresh.style', None)
292    except ImportError:
293        print mercurial_lib_not_found
294
295    if not style_hook:
296        print mercurial_style_message,
297        # continue unless user does ctrl-c/ctrl-d etc.
298        try:
299            raw_input()
300        except:
301            print "Input exception, exiting scons.\n"
302            sys.exit(1)
303        hgrc_path = '%s/.hg/hgrc' % main.root.abspath
304        print "Adding style hook to", hgrc_path, "\n"
305        try:
306            hgrc = open(hgrc_path, 'a')
307            hgrc.write(mercurial_style_hook)
308            hgrc.close()
309        except:
310            print "Error updating", hgrc_path
311            sys.exit(1)
312
313
314###################################################
315#
316# Figure out which configurations to set up based on the path(s) of
317# the target(s).
318#
319###################################################
320
321# Find default configuration & binary.
322Default(environ.get('M5_DEFAULT_BINARY', 'build/ALPHA/gem5.debug'))
323
324# helper function: find last occurrence of element in list
325def rfind(l, elt, offs = -1):
326    for i in range(len(l)+offs, 0, -1):
327        if l[i] == elt:
328            return i
329    raise ValueError, "element not found"
330
331# Take a list of paths (or SCons Nodes) and return a list with all
332# paths made absolute and ~-expanded.  Paths will be interpreted
333# relative to the launch directory unless a different root is provided
334def makePathListAbsolute(path_list, root=GetLaunchDir()):
335    return [abspath(joinpath(root, expanduser(str(p))))
336            for p in path_list]
337
338# Each target must have 'build' in the interior of the path; the
339# directory below this will determine the build parameters.  For
340# example, for target 'foo/bar/build/ALPHA_SE/arch/alpha/blah.do' we
341# recognize that ALPHA_SE specifies the configuration because it
342# follow 'build' in the build path.
343
344# The funky assignment to "[:]" is needed to replace the list contents
345# in place rather than reassign the symbol to a new list, which
346# doesn't work (obviously!).
347BUILD_TARGETS[:] = makePathListAbsolute(BUILD_TARGETS)
348
349# Generate a list of the unique build roots and configs that the
350# collected targets reference.
351variant_paths = []
352build_root = None
353for t in BUILD_TARGETS:
354    path_dirs = t.split('/')
355    try:
356        build_top = rfind(path_dirs, 'build', -2)
357    except:
358        print "Error: no non-leaf 'build' dir found on target path", t
359        Exit(1)
360    this_build_root = joinpath('/',*path_dirs[:build_top+1])
361    if not build_root:
362        build_root = this_build_root
363    else:
364        if this_build_root != build_root:
365            print "Error: build targets not under same build root\n"\
366                  "  %s\n  %s" % (build_root, this_build_root)
367            Exit(1)
368    variant_path = joinpath('/',*path_dirs[:build_top+2])
369    if variant_path not in variant_paths:
370        variant_paths.append(variant_path)
371
372# Make sure build_root exists (might not if this is the first build there)
373if not isdir(build_root):
374    mkdir(build_root)
375main['BUILDROOT'] = build_root
376
377Export('main')
378
379main.SConsignFile(joinpath(build_root, "sconsign"))
380
381# Default duplicate option is to use hard links, but this messes up
382# when you use emacs to edit a file in the target dir, as emacs moves
383# file to file~ then copies to file, breaking the link.  Symbolic
384# (soft) links work better.
385main.SetOption('duplicate', 'soft-copy')
386
387#
388# Set up global sticky variables... these are common to an entire build
389# tree (not specific to a particular build like ALPHA_SE)
390#
391
392global_vars_file = joinpath(build_root, 'variables.global')
393
394global_vars = Variables(global_vars_file, args=ARGUMENTS)
395
396global_vars.AddVariables(
397    ('CC', 'C compiler', environ.get('CC', main['CC'])),
398    ('CXX', 'C++ compiler', environ.get('CXX', main['CXX'])),
399    ('SWIG', 'SWIG tool', environ.get('SWIG', main['SWIG'])),
400    ('PROTOC', 'protoc tool', environ.get('PROTOC', 'protoc')),
401    ('BATCH', 'Use batch pool for build and tests', False),
402    ('BATCH_CMD', 'Batch pool submission command name', 'qdo'),
403    ('M5_BUILD_CACHE', 'Cache built objects in this directory', False),
404    ('EXTRAS', 'Add extra directories to the compilation', '')
405    )
406
407# Update main environment with values from ARGUMENTS & global_vars_file
408global_vars.Update(main)
409help_texts["global_vars"] += global_vars.GenerateHelpText(main)
410
411# Save sticky variable settings back to current variables file
412global_vars.Save(global_vars_file, main)
413
414# Parse EXTRAS variable to build list of all directories where we're
415# look for sources etc.  This list is exported as extras_dir_list.
416base_dir = main.srcdir.abspath
417if main['EXTRAS']:
418    extras_dir_list = makePathListAbsolute(main['EXTRAS'].split(':'))
419else:
420    extras_dir_list = []
421
422Export('base_dir')
423Export('extras_dir_list')
424
425# the ext directory should be on the #includes path
426main.Append(CPPPATH=[Dir('ext')])
427
428def strip_build_path(path, env):
429    path = str(path)
430    variant_base = env['BUILDROOT'] + os.path.sep
431    if path.startswith(variant_base):
432        path = path[len(variant_base):]
433    elif path.startswith('build/'):
434        path = path[6:]
435    return path
436
437# Generate a string of the form:
438#   common/path/prefix/src1, src2 -> tgt1, tgt2
439# to print while building.
440class Transform(object):
441    # all specific color settings should be here and nowhere else
442    tool_color = termcap.Normal
443    pfx_color = termcap.Yellow
444    srcs_color = termcap.Yellow + termcap.Bold
445    arrow_color = termcap.Blue + termcap.Bold
446    tgts_color = termcap.Yellow + termcap.Bold
447
448    def __init__(self, tool, max_sources=99):
449        self.format = self.tool_color + (" [%8s] " % tool) \
450                      + self.pfx_color + "%s" \
451                      + self.srcs_color + "%s" \
452                      + self.arrow_color + " -> " \
453                      + self.tgts_color + "%s" \
454                      + termcap.Normal
455        self.max_sources = max_sources
456
457    def __call__(self, target, source, env, for_signature=None):
458        # truncate source list according to max_sources param
459        source = source[0:self.max_sources]
460        def strip(f):
461            return strip_build_path(str(f), env)
462        if len(source) > 0:
463            srcs = map(strip, source)
464        else:
465            srcs = ['']
466        tgts = map(strip, target)
467        # surprisingly, os.path.commonprefix is a dumb char-by-char string
468        # operation that has nothing to do with paths.
469        com_pfx = os.path.commonprefix(srcs + tgts)
470        com_pfx_len = len(com_pfx)
471        if com_pfx:
472            # do some cleanup and sanity checking on common prefix
473            if com_pfx[-1] == ".":
474                # prefix matches all but file extension: ok
475                # back up one to change 'foo.cc -> o' to 'foo.cc -> .o'
476                com_pfx = com_pfx[0:-1]
477            elif com_pfx[-1] == "/":
478                # common prefix is directory path: OK
479                pass
480            else:
481                src0_len = len(srcs[0])
482                tgt0_len = len(tgts[0])
483                if src0_len == com_pfx_len:
484                    # source is a substring of target, OK
485                    pass
486                elif tgt0_len == com_pfx_len:
487                    # target is a substring of source, need to back up to
488                    # avoid empty string on RHS of arrow
489                    sep_idx = com_pfx.rfind(".")
490                    if sep_idx != -1:
491                        com_pfx = com_pfx[0:sep_idx]
492                    else:
493                        com_pfx = ''
494                elif src0_len > com_pfx_len and srcs[0][com_pfx_len] == ".":
495                    # still splitting at file extension: ok
496                    pass
497                else:
498                    # probably a fluke; ignore it
499                    com_pfx = ''
500        # recalculate length in case com_pfx was modified
501        com_pfx_len = len(com_pfx)
502        def fmt(files):
503            f = map(lambda s: s[com_pfx_len:], files)
504            return ', '.join(f)
505        return self.format % (com_pfx, fmt(srcs), fmt(tgts))
506
507Export('Transform')
508
509# enable the regression script to use the termcap
510main['TERMCAP'] = termcap
511
512if GetOption('verbose'):
513    def MakeAction(action, string, *args, **kwargs):
514        return Action(action, *args, **kwargs)
515else:
516    MakeAction = Action
517    main['CCCOMSTR']        = Transform("CC")
518    main['CXXCOMSTR']       = Transform("CXX")
519    main['ASCOMSTR']        = Transform("AS")
520    main['SWIGCOMSTR']      = Transform("SWIG")
521    main['ARCOMSTR']        = Transform("AR", 0)
522    main['LINKCOMSTR']      = Transform("LINK", 0)
523    main['RANLIBCOMSTR']    = Transform("RANLIB", 0)
524    main['M4COMSTR']        = Transform("M4")
525    main['SHCCCOMSTR']      = Transform("SHCC")
526    main['SHCXXCOMSTR']     = Transform("SHCXX")
527Export('MakeAction')
528
529# Initialize the Link-Time Optimization (LTO) flags
530main['LTO_CCFLAGS'] = []
531main['LTO_LDFLAGS'] = []
532
533# According to the readme, tcmalloc works best if the compiler doesn't
534# assume that we're using the builtin malloc and friends. These flags
535# are compiler-specific, so we need to set them after we detect which
536# compiler we're using.
537main['TCMALLOC_CCFLAGS'] = []
538
539CXX_version = readCommand([main['CXX'],'--version'], exception=False)
540CXX_V = readCommand([main['CXX'],'-V'], exception=False)
541
542main['GCC'] = CXX_version and CXX_version.find('g++') >= 0
543main['CLANG'] = CXX_version and CXX_version.find('clang') >= 0
544if main['GCC'] + main['CLANG'] > 1:
545    print 'Error: How can we have two at the same time?'
546    Exit(1)
547
548# Set up default C++ compiler flags
549if main['GCC'] or main['CLANG']:
550    # As gcc and clang share many flags, do the common parts here
551    main.Append(CCFLAGS=['-pipe'])
552    main.Append(CCFLAGS=['-fno-strict-aliasing'])
553    # Enable -Wall and then disable the few warnings that we
554    # consistently violate
555    main.Append(CCFLAGS=['-Wall', '-Wno-sign-compare', '-Wundef'])
556    # We always compile using C++11, but only gcc >= 4.7 and clang 3.1
557    # actually use that name, so we stick with c++0x
558    main.Append(CXXFLAGS=['-std=c++0x'])
559    # Add selected sanity checks from -Wextra
560    main.Append(CXXFLAGS=['-Wmissing-field-initializers',
561                          '-Woverloaded-virtual'])
562else:
563    print termcap.Yellow + termcap.Bold + 'Error' + termcap.Normal,
564    print "Don't know what compiler options to use for your compiler."
565    print termcap.Yellow + '       compiler:' + termcap.Normal, main['CXX']
566    print termcap.Yellow + '       version:' + termcap.Normal,
567    if not CXX_version:
568        print termcap.Yellow + termcap.Bold + "COMMAND NOT FOUND!" +\
569               termcap.Normal
570    else:
571        print CXX_version.replace('\n', '<nl>')
572    print "       If you're trying to use a compiler other than GCC"
573    print "       or clang, there appears to be something wrong with your"
574    print "       environment."
575    print "       "
576    print "       If you are trying to use a compiler other than those listed"
577    print "       above you will need to ease fix SConstruct and "
578    print "       src/SConscript to support that compiler."
579    Exit(1)
580
581if main['GCC']:
582    # Check for a supported version of gcc. >= 4.6 is chosen for its
583    # level of c++11 support. See
584    # http://gcc.gnu.org/projects/cxx0x.html for details. 4.6 is also
585    # the first version with proper LTO support.
586    gcc_version = readCommand([main['CXX'], '-dumpversion'], exception=False)
587    if compareVersions(gcc_version, "4.6") < 0:
588        print 'Error: gcc version 4.6 or newer required.'
589        print '       Installed version:', gcc_version
590        Exit(1)
591
592    main['GCC_VERSION'] = gcc_version
593
594    # gcc from version 4.8 and above generates "rep; ret" instructions
595    # to avoid performance penalties on certain AMD chips. Older
596    # assemblers detect this as an error, "Error: expecting string
597    # instruction after `rep'"
598    if compareVersions(gcc_version, "4.8") > 0:
599        as_version = readCommand([main['AS'], '-v', '/dev/null'],
600                                 exception=False).split()
601
602        if not as_version or compareVersions(as_version[-1], "2.23") < 0:
603            print termcap.Yellow + termcap.Bold + \
604                'Warning: This combination of gcc and binutils have' + \
605                ' known incompatibilities.\n' + \
606                '         If you encounter build problems, please update ' + \
607                'binutils to 2.23.' + \
608                termcap.Normal
609
610    # Make sure we warn if the user has requested to compile with the
611    # Undefined Benahvior Sanitizer and this version of gcc does not
612    # support it.
613    if GetOption('with_ubsan') and \
614            compareVersions(gcc_version, '4.9') < 0:
615        print termcap.Yellow + termcap.Bold + \
616            'Warning: UBSan is only supported using gcc 4.9 and later.' + \
617            termcap.Normal
618
619    # Add the appropriate Link-Time Optimization (LTO) flags
620    # unless LTO is explicitly turned off. Note that these flags
621    # are only used by the fast target.
622    if not GetOption('no_lto'):
623        # Pass the LTO flag when compiling to produce GIMPLE
624        # output, we merely create the flags here and only append
625        # them later
626        main['LTO_CCFLAGS'] = ['-flto=%d' % GetOption('num_jobs')]
627
628        # Use the same amount of jobs for LTO as we are running
629        # scons with
630        main['LTO_LDFLAGS'] = ['-flto=%d' % GetOption('num_jobs')]
631
632    main.Append(TCMALLOC_CCFLAGS=['-fno-builtin-malloc', '-fno-builtin-calloc',
633                                  '-fno-builtin-realloc', '-fno-builtin-free'])
634
635elif main['CLANG']:
636    # Check for a supported version of clang, >= 3.0 is needed to
637    # support similar features as gcc 4.6. See
638    # http://clang.llvm.org/cxx_status.html for details
639    clang_version_re = re.compile(".* version (\d+\.\d+)")
640    clang_version_match = clang_version_re.search(CXX_version)
641    if (clang_version_match):
642        clang_version = clang_version_match.groups()[0]
643        if compareVersions(clang_version, "3.0") < 0:
644            print 'Error: clang version 3.0 or newer required.'
645            print '       Installed version:', clang_version
646            Exit(1)
647    else:
648        print 'Error: Unable to determine clang version.'
649        Exit(1)
650
651    # clang has a few additional warnings that we disable,
652    # tautological comparisons are allowed due to unsigned integers
653    # being compared to constants that happen to be 0, and extraneous
654    # parantheses are allowed due to Ruby's printing of the AST,
655    # finally self assignments are allowed as the generated CPU code
656    # is relying on this
657    main.Append(CCFLAGS=['-Wno-tautological-compare',
658                         '-Wno-parentheses',
659                         '-Wno-self-assign',
660                         # Some versions of libstdc++ (4.8?) seem to
661                         # use struct hash and class hash
662                         # interchangeably.
663                         '-Wno-mismatched-tags',
664                         ])
665
666    main.Append(TCMALLOC_CCFLAGS=['-fno-builtin'])
667
668    # On Mac OS X/Darwin we need to also use libc++ (part of XCode) as
669    # opposed to libstdc++, as the later is dated.
670    if sys.platform == "darwin":
671        main.Append(CXXFLAGS=['-stdlib=libc++'])
672        main.Append(LIBS=['c++'])
673
674else:
675    print termcap.Yellow + termcap.Bold + 'Error' + termcap.Normal,
676    print "Don't know what compiler options to use for your compiler."
677    print termcap.Yellow + '       compiler:' + termcap.Normal, main['CXX']
678    print termcap.Yellow + '       version:' + termcap.Normal,
679    if not CXX_version:
680        print termcap.Yellow + termcap.Bold + "COMMAND NOT FOUND!" +\
681               termcap.Normal
682    else:
683        print CXX_version.replace('\n', '<nl>')
684    print "       If you're trying to use a compiler other than GCC"
685    print "       or clang, there appears to be something wrong with your"
686    print "       environment."
687    print "       "
688    print "       If you are trying to use a compiler other than those listed"
689    print "       above you will need to ease fix SConstruct and "
690    print "       src/SConscript to support that compiler."
691    Exit(1)
692
693# Set up common yacc/bison flags (needed for Ruby)
694main['YACCFLAGS'] = '-d'
695main['YACCHXXFILESUFFIX'] = '.hh'
696
697# Do this after we save setting back, or else we'll tack on an
698# extra 'qdo' every time we run scons.
699if main['BATCH']:
700    main['CC']     = main['BATCH_CMD'] + ' ' + main['CC']
701    main['CXX']    = main['BATCH_CMD'] + ' ' + main['CXX']
702    main['AS']     = main['BATCH_CMD'] + ' ' + main['AS']
703    main['AR']     = main['BATCH_CMD'] + ' ' + main['AR']
704    main['RANLIB'] = main['BATCH_CMD'] + ' ' + main['RANLIB']
705
706if sys.platform == 'cygwin':
707    # cygwin has some header file issues...
708    main.Append(CCFLAGS=["-Wno-uninitialized"])
709
710# Check for the protobuf compiler
711protoc_version = readCommand([main['PROTOC'], '--version'],
712                             exception='').split()
713
714# First two words should be "libprotoc x.y.z"
715if len(protoc_version) < 2 or protoc_version[0] != 'libprotoc':
716    print termcap.Yellow + termcap.Bold + \
717        'Warning: Protocol buffer compiler (protoc) not found.\n' + \
718        '         Please install protobuf-compiler for tracing support.' + \
719        termcap.Normal
720    main['PROTOC'] = False
721else:
722    # Based on the availability of the compress stream wrappers,
723    # require 2.1.0
724    min_protoc_version = '2.1.0'
725    if compareVersions(protoc_version[1], min_protoc_version) < 0:
726        print termcap.Yellow + termcap.Bold + \
727            'Warning: protoc version', min_protoc_version, \
728            'or newer required.\n' + \
729            '         Installed version:', protoc_version[1], \
730            termcap.Normal
731        main['PROTOC'] = False
732    else:
733        # Attempt to determine the appropriate include path and
734        # library path using pkg-config, that means we also need to
735        # check for pkg-config. Note that it is possible to use
736        # protobuf without the involvement of pkg-config. Later on we
737        # check go a library config check and at that point the test
738        # will fail if libprotobuf cannot be found.
739        if readCommand(['pkg-config', '--version'], exception=''):
740            try:
741                # Attempt to establish what linking flags to add for protobuf
742                # using pkg-config
743                main.ParseConfig('pkg-config --cflags --libs-only-L protobuf')
744            except:
745                print termcap.Yellow + termcap.Bold + \
746                    'Warning: pkg-config could not get protobuf flags.' + \
747                    termcap.Normal
748
749# Check for SWIG
750if not main.has_key('SWIG'):
751    print 'Error: SWIG utility not found.'
752    print '       Please install (see http://www.swig.org) and retry.'
753    Exit(1)
754
755# Check for appropriate SWIG version
756swig_version = readCommand([main['SWIG'], '-version'], exception='').split()
757# First 3 words should be "SWIG Version x.y.z"
758if len(swig_version) < 3 or \
759        swig_version[0] != 'SWIG' or swig_version[1] != 'Version':
760    print 'Error determining SWIG version.'
761    Exit(1)
762
763min_swig_version = '2.0.4'
764if compareVersions(swig_version[2], min_swig_version) < 0:
765    print 'Error: SWIG version', min_swig_version, 'or newer required.'
766    print '       Installed version:', swig_version[2]
767    Exit(1)
768
769# Check for known incompatibilities. The standard library shipped with
770# gcc >= 4.9 does not play well with swig versions prior to 3.0
771if main['GCC'] and compareVersions(gcc_version, '4.9') >= 0 and \
772        compareVersions(swig_version[2], '3.0') < 0:
773    print termcap.Yellow + termcap.Bold + \
774        'Warning: This combination of gcc and swig have' + \
775        ' known incompatibilities.\n' + \
776        '         If you encounter build problems, please update ' + \
777        'swig to 3.0 or later.' + \
778        termcap.Normal
779
780# Set up SWIG flags & scanner
781swig_flags=Split('-c++ -python -modern -templatereduce $_CPPINCFLAGS')
782main.Append(SWIGFLAGS=swig_flags)
783
784# Check for 'timeout' from GNU coreutils.  If present, regressions
785# will be run with a time limit.
786TIMEOUT_version = readCommand(['timeout', '--version'], exception=False)
787main['TIMEOUT'] = TIMEOUT_version and TIMEOUT_version.find('timeout') == 0
788
789# filter out all existing swig scanners, they mess up the dependency
790# stuff for some reason
791scanners = []
792for scanner in main['SCANNERS']:
793    skeys = scanner.skeys
794    if skeys == '.i':
795        continue
796
797    if isinstance(skeys, (list, tuple)) and '.i' in skeys:
798        continue
799
800    scanners.append(scanner)
801
802# add the new swig scanner that we like better
803from SCons.Scanner import ClassicCPP as CPPScanner
804swig_inc_re = '^[ \t]*[%,#][ \t]*(?:include|import)[ \t]*(<|")([^>"]+)(>|")'
805scanners.append(CPPScanner("SwigScan", [ ".i" ], "CPPPATH", swig_inc_re))
806
807# replace the scanners list that has what we want
808main['SCANNERS'] = scanners
809
810# Add a custom Check function to the Configure context so that we can
811# figure out if the compiler adds leading underscores to global
812# variables.  This is needed for the autogenerated asm files that we
813# use for embedding the python code.
814def CheckLeading(context):
815    context.Message("Checking for leading underscore in global variables...")
816    # 1) Define a global variable called x from asm so the C compiler
817    #    won't change the symbol at all.
818    # 2) Declare that variable.
819    # 3) Use the variable
820    #
821    # If the compiler prepends an underscore, this will successfully
822    # link because the external symbol 'x' will be called '_x' which
823    # was defined by the asm statement.  If the compiler does not
824    # prepend an underscore, this will not successfully link because
825    # '_x' will have been defined by assembly, while the C portion of
826    # the code will be trying to use 'x'
827    ret = context.TryLink('''
828        asm(".globl _x; _x: .byte 0");
829        extern int x;
830        int main() { return x; }
831        ''', extension=".c")
832    context.env.Append(LEADING_UNDERSCORE=ret)
833    context.Result(ret)
834    return ret
835
836# Add a custom Check function to test for structure members.
837def CheckMember(context, include, decl, member, include_quotes="<>"):
838    context.Message("Checking for member %s in %s..." %
839                    (member, decl))
840    text = """
841#include %(header)s
842int main(){
843  %(decl)s test;
844  (void)test.%(member)s;
845  return 0;
846};
847""" % { "header" : include_quotes[0] + include + include_quotes[1],
848        "decl" : decl,
849        "member" : member,
850        }
851
852    ret = context.TryCompile(text, extension=".cc")
853    context.Result(ret)
854    return ret
855
856# Platform-specific configuration.  Note again that we assume that all
857# builds under a given build root run on the same host platform.
858conf = Configure(main,
859                 conf_dir = joinpath(build_root, '.scons_config'),
860                 log_file = joinpath(build_root, 'scons_config.log'),
861                 custom_tests = {
862        'CheckLeading' : CheckLeading,
863        'CheckMember' : CheckMember,
864        })
865
866# Check for leading underscores.  Don't really need to worry either
867# way so don't need to check the return code.
868conf.CheckLeading()
869
870# Check if we should compile a 64 bit binary on Mac OS X/Darwin
871try:
872    import platform
873    uname = platform.uname()
874    if uname[0] == 'Darwin' and compareVersions(uname[2], '9.0.0') >= 0:
875        if int(readCommand('sysctl -n hw.cpu64bit_capable')[0]):
876            main.Append(CCFLAGS=['-arch', 'x86_64'])
877            main.Append(CFLAGS=['-arch', 'x86_64'])
878            main.Append(LINKFLAGS=['-arch', 'x86_64'])
879            main.Append(ASFLAGS=['-arch', 'x86_64'])
880except:
881    pass
882
883# Recent versions of scons substitute a "Null" object for Configure()
884# when configuration isn't necessary, e.g., if the "--help" option is
885# present.  Unfortuantely this Null object always returns false,
886# breaking all our configuration checks.  We replace it with our own
887# more optimistic null object that returns True instead.
888if not conf:
889    def NullCheck(*args, **kwargs):
890        return True
891
892    class NullConf:
893        def __init__(self, env):
894            self.env = env
895        def Finish(self):
896            return self.env
897        def __getattr__(self, mname):
898            return NullCheck
899
900    conf = NullConf(main)
901
902# Cache build files in the supplied directory.
903if main['M5_BUILD_CACHE']:
904    print 'Using build cache located at', main['M5_BUILD_CACHE']
905    CacheDir(main['M5_BUILD_CACHE'])
906
907if not GetOption('without_python'):
908    # Find Python include and library directories for embedding the
909    # interpreter. We rely on python-config to resolve the appropriate
910    # includes and linker flags. ParseConfig does not seem to understand
911    # the more exotic linker flags such as -Xlinker and -export-dynamic so
912    # we add them explicitly below. If you want to link in an alternate
913    # version of python, see above for instructions on how to invoke
914    # scons with the appropriate PATH set.
915    #
916    # First we check if python2-config exists, else we use python-config
917    python_config = readCommand(['which', 'python2-config'],
918                                exception='').strip()
919    if not os.path.exists(python_config):
920        python_config = readCommand(['which', 'python-config'],
921                                    exception='').strip()
922    py_includes = readCommand([python_config, '--includes'],
923                              exception='').split()
924    # Strip the -I from the include folders before adding them to the
925    # CPPPATH
926    main.Append(CPPPATH=map(lambda inc: inc[2:], py_includes))
927
928    # Read the linker flags and split them into libraries and other link
929    # flags. The libraries are added later through the call the CheckLib.
930    py_ld_flags = readCommand([python_config, '--ldflags'],
931        exception='').split()
932    py_libs = []
933    for lib in py_ld_flags:
934         if not lib.startswith('-l'):
935             main.Append(LINKFLAGS=[lib])
936         else:
937             lib = lib[2:]
938             if lib not in py_libs:
939                 py_libs.append(lib)
940
941    # verify that this stuff works
942    if not conf.CheckHeader('Python.h', '<>'):
943        print "Error: can't find Python.h header in", py_includes
944        print "Install Python headers (package python-dev on Ubuntu and RedHat)"
945        Exit(1)
946
947    for lib in py_libs:
948        if not conf.CheckLib(lib):
949            print "Error: can't find library %s required by python" % lib
950            Exit(1)
951
952# On Solaris you need to use libsocket for socket ops
953if not conf.CheckLibWithHeader(None, 'sys/socket.h', 'C++', 'accept(0,0,0);'):
954   if not conf.CheckLibWithHeader('socket', 'sys/socket.h', 'C++', 'accept(0,0,0);'):
955       print "Can't find library with socket calls (e.g. accept())"
956       Exit(1)
957
958# Check for zlib.  If the check passes, libz will be automatically
959# added to the LIBS environment variable.
960if not conf.CheckLibWithHeader('z', 'zlib.h', 'C++','zlibVersion();'):
961    print 'Error: did not find needed zlib compression library '\
962          'and/or zlib.h header file.'
963    print '       Please install zlib and try again.'
964    Exit(1)
965
966# If we have the protobuf compiler, also make sure we have the
967# development libraries. If the check passes, libprotobuf will be
968# automatically added to the LIBS environment variable. After
969# this, we can use the HAVE_PROTOBUF flag to determine if we have
970# got both protoc and libprotobuf available.
971main['HAVE_PROTOBUF'] = main['PROTOC'] and \
972    conf.CheckLibWithHeader('protobuf', 'google/protobuf/message.h',
973                            'C++', 'GOOGLE_PROTOBUF_VERIFY_VERSION;')
974
975# If we have the compiler but not the library, print another warning.
976if main['PROTOC'] and not main['HAVE_PROTOBUF']:
977    print termcap.Yellow + termcap.Bold + \
978        'Warning: did not find protocol buffer library and/or headers.\n' + \
979    '       Please install libprotobuf-dev for tracing support.' + \
980    termcap.Normal
981
982# Check for librt.
983have_posix_clock = \
984    conf.CheckLibWithHeader(None, 'time.h', 'C',
985                            'clock_nanosleep(0,0,NULL,NULL);') or \
986    conf.CheckLibWithHeader('rt', 'time.h', 'C',
987                            'clock_nanosleep(0,0,NULL,NULL);')
988
989have_posix_timers = \
990    conf.CheckLibWithHeader([None, 'rt'], [ 'time.h', 'signal.h' ], 'C',
991                            'timer_create(CLOCK_MONOTONIC, NULL, NULL);')
992
993if not GetOption('without_tcmalloc'):
994    if conf.CheckLib('tcmalloc'):
995        main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
996    elif conf.CheckLib('tcmalloc_minimal'):
997        main.Append(CCFLAGS=main['TCMALLOC_CCFLAGS'])
998    else:
999        print termcap.Yellow + termcap.Bold + \
1000              "You can get a 12% performance improvement by "\
1001              "installing tcmalloc (libgoogle-perftools-dev package "\
1002              "on Ubuntu or RedHat)." + termcap.Normal
1003
1004if not have_posix_clock:
1005    print "Can't find library for POSIX clocks."
1006
1007# Check for <fenv.h> (C99 FP environment control)
1008have_fenv = conf.CheckHeader('fenv.h', '<>')
1009if not have_fenv:
1010    print "Warning: Header file <fenv.h> not found."
1011    print "         This host has no IEEE FP rounding mode control."
1012
1013# Check if we should enable KVM-based hardware virtualization. The API
1014# we rely on exists since version 2.6.36 of the kernel, but somehow
1015# the KVM_API_VERSION does not reflect the change. We test for one of
1016# the types as a fall back.
1017have_kvm = conf.CheckHeader('linux/kvm.h', '<>') and \
1018    conf.CheckTypeSize('struct kvm_xsave', '#include <linux/kvm.h>') != 0
1019if not have_kvm:
1020    print "Info: Compatible header file <linux/kvm.h> not found, " \
1021        "disabling KVM support."
1022
1023# Check if the requested target ISA is compatible with the host
1024def is_isa_kvm_compatible(isa):
1025    isa_comp_table = {
1026        "arm" : ( "armv7l" ),
1027        "x86" : ( "x86_64" ),
1028        }
1029    try:
1030        import platform
1031        host_isa = platform.machine()
1032    except:
1033        print "Warning: Failed to determine host ISA."
1034        return False
1035
1036    return host_isa in isa_comp_table.get(isa, [])
1037
1038
1039# Check if the exclude_host attribute is available. We want this to
1040# get accurate instruction counts in KVM.
1041main['HAVE_PERF_ATTR_EXCLUDE_HOST'] = conf.CheckMember(
1042    'linux/perf_event.h', 'struct perf_event_attr', 'exclude_host')
1043
1044
1045######################################################################
1046#
1047# Finish the configuration
1048#
1049main = conf.Finish()
1050
1051######################################################################
1052#
1053# Collect all non-global variables
1054#
1055
1056# Define the universe of supported ISAs
1057all_isa_list = [ ]
1058Export('all_isa_list')
1059
1060class CpuModel(object):
1061    '''The CpuModel class encapsulates everything the ISA parser needs to
1062    know about a particular CPU model.'''
1063
1064    # Dict of available CPU model objects.  Accessible as CpuModel.dict.
1065    dict = {}
1066
1067    # Constructor.  Automatically adds models to CpuModel.dict.
1068    def __init__(self, name, default=False):
1069        self.name = name           # name of model
1070
1071        # This cpu is enabled by default
1072        self.default = default
1073
1074        # Add self to dict
1075        if name in CpuModel.dict:
1076            raise AttributeError, "CpuModel '%s' already registered" % name
1077        CpuModel.dict[name] = self
1078
1079Export('CpuModel')
1080
1081# Sticky variables get saved in the variables file so they persist from
1082# one invocation to the next (unless overridden, in which case the new
1083# value becomes sticky).
1084sticky_vars = Variables(args=ARGUMENTS)
1085Export('sticky_vars')
1086
1087# Sticky variables that should be exported
1088export_vars = []
1089Export('export_vars')
1090
1091# For Ruby
1092all_protocols = []
1093Export('all_protocols')
1094protocol_dirs = []
1095Export('protocol_dirs')
1096slicc_includes = []
1097Export('slicc_includes')
1098
1099# Walk the tree and execute all SConsopts scripts that wil add to the
1100# above variables
1101if GetOption('verbose'):
1102    print "Reading SConsopts"
1103for bdir in [ base_dir ] + extras_dir_list:
1104    if not isdir(bdir):
1105        print "Error: directory '%s' does not exist" % bdir
1106        Exit(1)
1107    for root, dirs, files in os.walk(bdir):
1108        if 'SConsopts' in files:
1109            if GetOption('verbose'):
1110                print "Reading", joinpath(root, 'SConsopts')
1111            SConscript(joinpath(root, 'SConsopts'))
1112
1113all_isa_list.sort()
1114
1115sticky_vars.AddVariables(
1116    EnumVariable('TARGET_ISA', 'Target ISA', 'alpha', all_isa_list),
1117    ListVariable('CPU_MODELS', 'CPU models',
1118                 sorted(n for n,m in CpuModel.dict.iteritems() if m.default),
1119                 sorted(CpuModel.dict.keys())),
1120    BoolVariable('EFENCE', 'Link with Electric Fence malloc debugger',
1121                 False),
1122    BoolVariable('SS_COMPATIBLE_FP',
1123                 'Make floating-point results compatible with SimpleScalar',
1124                 False),
1125    BoolVariable('USE_SSE2',
1126                 'Compile for SSE2 (-msse2) to get IEEE FP on x86 hosts',
1127                 False),
1128    BoolVariable('USE_POSIX_CLOCK', 'Use POSIX Clocks', have_posix_clock),
1129    BoolVariable('USE_FENV', 'Use <fenv.h> IEEE mode control', have_fenv),
1130    BoolVariable('CP_ANNOTATE', 'Enable critical path annotation capability', False),
1131    BoolVariable('USE_KVM', 'Enable hardware virtualized (KVM) CPU models', have_kvm),
1132    EnumVariable('PROTOCOL', 'Coherence protocol for Ruby', 'None',
1133                  all_protocols),
1134    )
1135
1136# These variables get exported to #defines in config/*.hh (see src/SConscript).
1137export_vars += ['USE_FENV', 'SS_COMPATIBLE_FP', 'TARGET_ISA', 'CP_ANNOTATE',
1138                'USE_POSIX_CLOCK', 'PROTOCOL', 'HAVE_PROTOBUF',
1139                'HAVE_PERF_ATTR_EXCLUDE_HOST']
1140
1141###################################################
1142#
1143# Define a SCons builder for configuration flag headers.
1144#
1145###################################################
1146
1147# This function generates a config header file that #defines the
1148# variable symbol to the current variable setting (0 or 1).  The source
1149# operands are the name of the variable and a Value node containing the
1150# value of the variable.
1151def build_config_file(target, source, env):
1152    (variable, value) = [s.get_contents() for s in source]
1153    f = file(str(target[0]), 'w')
1154    print >> f, '#define', variable, value
1155    f.close()
1156    return None
1157
1158# Combine the two functions into a scons Action object.
1159config_action = MakeAction(build_config_file, Transform("CONFIG H", 2))
1160
1161# The emitter munges the source & target node lists to reflect what
1162# we're really doing.
1163def config_emitter(target, source, env):
1164    # extract variable name from Builder arg
1165    variable = str(target[0])
1166    # True target is config header file
1167    target = joinpath('config', variable.lower() + '.hh')
1168    val = env[variable]
1169    if isinstance(val, bool):
1170        # Force value to 0/1
1171        val = int(val)
1172    elif isinstance(val, str):
1173        val = '"' + val + '"'
1174
1175    # Sources are variable name & value (packaged in SCons Value nodes)
1176    return ([target], [Value(variable), Value(val)])
1177
1178config_builder = Builder(emitter = config_emitter, action = config_action)
1179
1180main.Append(BUILDERS = { 'ConfigFile' : config_builder })
1181
1182# libelf build is shared across all configs in the build root.
1183main.SConscript('ext/libelf/SConscript',
1184                variant_dir = joinpath(build_root, 'libelf'))
1185
1186# gzstream build is shared across all configs in the build root.
1187main.SConscript('ext/gzstream/SConscript',
1188                variant_dir = joinpath(build_root, 'gzstream'))
1189
1190# libfdt build is shared across all configs in the build root.
1191main.SConscript('ext/libfdt/SConscript',
1192                variant_dir = joinpath(build_root, 'libfdt'))
1193
1194# fputils build is shared across all configs in the build root.
1195main.SConscript('ext/fputils/SConscript',
1196                variant_dir = joinpath(build_root, 'fputils'))
1197
1198# DRAMSim2 build is shared across all configs in the build root.
1199main.SConscript('ext/dramsim2/SConscript',
1200                variant_dir = joinpath(build_root, 'dramsim2'))
1201
1202# DRAMPower build is shared across all configs in the build root.
1203main.SConscript('ext/drampower/SConscript',
1204                variant_dir = joinpath(build_root, 'drampower'))
1205
1206###################################################
1207#
1208# This function is used to set up a directory with switching headers
1209#
1210###################################################
1211
1212main['ALL_ISA_LIST'] = all_isa_list
1213all_isa_deps = {}
1214def make_switching_dir(dname, switch_headers, env):
1215    # Generate the header.  target[0] is the full path of the output
1216    # header to generate.  'source' is a dummy variable, since we get the
1217    # list of ISAs from env['ALL_ISA_LIST'].
1218    def gen_switch_hdr(target, source, env):
1219        fname = str(target[0])
1220        isa = env['TARGET_ISA'].lower()
1221        try:
1222            f = open(fname, 'w')
1223            print >>f, '#include "%s/%s/%s"' % (dname, isa, basename(fname))
1224            f.close()
1225        except IOError:
1226            print "Failed to create %s" % fname
1227            raise
1228
1229    # Build SCons Action object. 'varlist' specifies env vars that this
1230    # action depends on; when env['ALL_ISA_LIST'] changes these actions
1231    # should get re-executed.
1232    switch_hdr_action = MakeAction(gen_switch_hdr,
1233                          Transform("GENERATE"), varlist=['ALL_ISA_LIST'])
1234
1235    # Instantiate actions for each header
1236    for hdr in switch_headers:
1237        env.Command(hdr, [], switch_hdr_action)
1238
1239    isa_target = Dir('.').up().name.lower().replace('_', '-')
1240    env['PHONY_BASE'] = '#'+isa_target
1241    all_isa_deps[isa_target] = None
1242
1243Export('make_switching_dir')
1244
1245# all-isas -> all-deps -> all-environs -> all_targets
1246main.Alias('#all-isas', [])
1247main.Alias('#all-deps', '#all-isas')
1248
1249# Dummy target to ensure all environments are created before telling
1250# SCons what to actually make (the command line arguments).  We attach
1251# them to the dependence graph after the environments are complete.
1252ORIG_BUILD_TARGETS = list(BUILD_TARGETS) # force a copy; gets closure to work.
1253def environsComplete(target, source, env):
1254    for t in ORIG_BUILD_TARGETS:
1255        main.Depends('#all-targets', t)
1256
1257# Each build/* switching_dir attaches its *-environs target to #all-environs.
1258main.Append(BUILDERS = {'CompleteEnvirons' :
1259                        Builder(action=MakeAction(environsComplete, None))})
1260main.CompleteEnvirons('#all-environs', [])
1261
1262def doNothing(**ignored): pass
1263main.Append(BUILDERS = {'Dummy': Builder(action=MakeAction(doNothing, None))})
1264
1265# The final target to which all the original targets ultimately get attached.
1266main.Dummy('#all-targets', '#all-environs')
1267BUILD_TARGETS[:] = ['#all-targets']
1268
1269###################################################
1270#
1271# Define build environments for selected configurations.
1272#
1273###################################################
1274
1275for variant_path in variant_paths:
1276    if not GetOption('silent'):
1277        print "Building in", variant_path
1278
1279    # Make a copy of the build-root environment to use for this config.
1280    env = main.Clone()
1281    env['BUILDDIR'] = variant_path
1282
1283    # variant_dir is the tail component of build path, and is used to
1284    # determine the build parameters (e.g., 'ALPHA_SE')
1285    (build_root, variant_dir) = splitpath(variant_path)
1286
1287    # Set env variables according to the build directory config.
1288    sticky_vars.files = []
1289    # Variables for $BUILD_ROOT/$VARIANT_DIR are stored in
1290    # $BUILD_ROOT/variables/$VARIANT_DIR so you can nuke
1291    # $BUILD_ROOT/$VARIANT_DIR without losing your variables settings.
1292    current_vars_file = joinpath(build_root, 'variables', variant_dir)
1293    if isfile(current_vars_file):
1294        sticky_vars.files.append(current_vars_file)
1295        if not GetOption('silent'):
1296            print "Using saved variables file %s" % current_vars_file
1297    else:
1298        # Build dir-specific variables file doesn't exist.
1299
1300        # Make sure the directory is there so we can create it later
1301        opt_dir = dirname(current_vars_file)
1302        if not isdir(opt_dir):
1303            mkdir(opt_dir)
1304
1305        # Get default build variables from source tree.  Variables are
1306        # normally determined by name of $VARIANT_DIR, but can be
1307        # overridden by '--default=' arg on command line.
1308        default = GetOption('default')
1309        opts_dir = joinpath(main.root.abspath, 'build_opts')
1310        if default:
1311            default_vars_files = [joinpath(build_root, 'variables', default),
1312                                  joinpath(opts_dir, default)]
1313        else:
1314            default_vars_files = [joinpath(opts_dir, variant_dir)]
1315        existing_files = filter(isfile, default_vars_files)
1316        if existing_files:
1317            default_vars_file = existing_files[0]
1318            sticky_vars.files.append(default_vars_file)
1319            print "Variables file %s not found,\n  using defaults in %s" \
1320                  % (current_vars_file, default_vars_file)
1321        else:
1322            print "Error: cannot find variables file %s or " \
1323                  "default file(s) %s" \
1324                  % (current_vars_file, ' or '.join(default_vars_files))
1325            Exit(1)
1326
1327    # Apply current variable settings to env
1328    sticky_vars.Update(env)
1329
1330    help_texts["local_vars"] += \
1331        "Build variables for %s:\n" % variant_dir \
1332                 + sticky_vars.GenerateHelpText(env)
1333
1334    # Process variable settings.
1335
1336    if not have_fenv and env['USE_FENV']:
1337        print "Warning: <fenv.h> not available; " \
1338              "forcing USE_FENV to False in", variant_dir + "."
1339        env['USE_FENV'] = False
1340
1341    if not env['USE_FENV']:
1342        print "Warning: No IEEE FP rounding mode control in", variant_dir + "."
1343        print "         FP results may deviate slightly from other platforms."
1344
1345    if env['EFENCE']:
1346        env.Append(LIBS=['efence'])
1347
1348    if env['USE_KVM']:
1349        if not have_kvm:
1350            print "Warning: Can not enable KVM, host seems to lack KVM support"
1351            env['USE_KVM'] = False
1352        elif not have_posix_timers:
1353            print "Warning: Can not enable KVM, host seems to lack support " \
1354                "for POSIX timers"
1355            env['USE_KVM'] = False
1356        elif not is_isa_kvm_compatible(env['TARGET_ISA']):
1357            print "Info: KVM support disabled due to unsupported host and " \
1358                "target ISA combination"
1359            env['USE_KVM'] = False
1360
1361    # Warn about missing optional functionality
1362    if env['USE_KVM']:
1363        if not main['HAVE_PERF_ATTR_EXCLUDE_HOST']:
1364            print "Warning: perf_event headers lack support for the " \
1365                "exclude_host attribute. KVM instruction counts will " \
1366                "be inaccurate."
1367
1368    # Save sticky variable settings back to current variables file
1369    sticky_vars.Save(current_vars_file, env)
1370
1371    if env['USE_SSE2']:
1372        env.Append(CCFLAGS=['-msse2'])
1373
1374    # The src/SConscript file sets up the build rules in 'env' according
1375    # to the configured variables.  It returns a list of environments,
1376    # one for each variant build (debug, opt, etc.)
1377    SConscript('src/SConscript', variant_dir = variant_path, exports = 'env')
1378
1379def pairwise(iterable):
1380    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
1381    a, b = itertools.tee(iterable)
1382    b.next()
1383    return itertools.izip(a, b)
1384
1385# Create false dependencies so SCons will parse ISAs, establish
1386# dependencies, and setup the build Environments serially. Either
1387# SCons (likely) and/or our SConscripts (possibly) cannot cope with -j
1388# greater than 1. It appears to be standard race condition stuff; it
1389# doesn't always fail, but usually, and the behaviors are different.
1390# Every time I tried to remove this, builds would fail in some
1391# creative new way. So, don't do that. You'll want to, though, because
1392# tests/SConscript takes a long time to make its Environments.
1393for t1, t2 in pairwise(sorted(all_isa_deps.iterkeys())):
1394    main.Depends('#%s-deps'     % t2, '#%s-deps'     % t1)
1395    main.Depends('#%s-environs' % t2, '#%s-environs' % t1)
1396
1397# base help text
1398Help('''
1399Usage: scons [scons options] [build variables] [target(s)]
1400
1401Extra scons options:
1402%(options)s
1403
1404Global build variables:
1405%(global_vars)s
1406
1407%(local_vars)s
1408''' % help_texts)
1409