scons: Stop generating inc.d in the isa parser.
Generating dependency/build product information in the isa parser breaks scons idea of how a build is supposed to work. Arm twisting it into working forced a lot of false dependencies which slowed down the build. Change-Id: Iadee8c930fd7c80136d200d69870df7672a6b3ca Reviewed-on: https://gem5-review.googlesource.com/5081 Reviewed-by: Jason Lowe-Power <jason@lowepower.com> Maintainer: Gabe Black <gabeblack@google.com>
This commit is contained in:
Gabe Black
@@ -97,120 +97,130 @@ if env['BUILD_GPU']:
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# Build a SCons scanner for ISA files
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#
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import SCons.Scanner
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import SCons.Tool
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isa_scanner = SCons.Scanner.Classic("ISAScan",
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[".isa", ".ISA"],
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"SRCDIR",
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r'^\s*##include\s+"([\w/.-]*)"')
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scanner = SCons.Scanner.Classic("ISAScan",
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[".isa", ".ISA"],
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"SRCDIR",
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r'^\s*##include\s+"([\w/.-]*)"')
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env.Append(SCANNERS = isa_scanner)
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env.Append(SCANNERS=scanner)
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# Tell scons that when it sees a cc.inc file, it should scan it for includes.
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SCons.Tool.SourceFileScanner.add_scanner('.cc.inc', SCons.Tool.CScanner)
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#
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# Now create a Builder object that uses isa_parser.py to generate C++
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# output from the ISA description (*.isa) files.
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#
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isa_parser = File('isa_parser.py')
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# The emitter patches up the sources & targets to include the
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# autogenerated files as targets and isa parser itself as a source.
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def isa_desc_emitter(target, source, env):
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# List the isa parser as a source.
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source += [
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isa_parser,
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Value("ExecContext"),
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]
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# Specify different targets depending on if we're running the ISA
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# parser for its dependency information, or for the generated files.
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# (As an optimization, the ISA parser detects the useless second run
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# and skips doing any work, if the first run was performed, since it
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# always generates all its files). The way we track this in SCons is the
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# <arch>_isa_outputs value in the environment (env). If it's unset, we
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# don't know what the dependencies are so we ask for generated/inc.d to
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# be generated so they can be acquired. If we know what they are, then
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# it's because we've already processed inc.d and then claim that our
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# outputs (targets) will be thus.
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isa = env['TARGET_ISA']
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key = '%s_isa_outputs' % isa
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if key in env:
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targets = [ os.path.join('generated', f) for f in env[key] ]
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else:
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targets = [ os.path.join('generated','inc.d') ]
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def prefix(s):
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return os.path.join(target[0].dir.up().abspath, s)
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return [ prefix(t) for t in targets ], source
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ARCH_DIR = Dir('.')
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parser_py = File('isa_parser.py')
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micro_asm_py = File('micro_asm.py')
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# import ply here because SCons screws with sys.path when performing actions.
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import ply
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def isa_desc_action_func(target, source, env):
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# Add the current directory to the system path so we can import files
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sys.path[0:0] = [ ARCH_DIR.srcnode().abspath ]
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def run_parser(target, source, env):
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# Add the current directory to the system path so we can import files.
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sys.path[0:0] = [ parser_py.dir.abspath ]
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import isa_parser
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# Skip over the ISA description itself and the parser to the CPU models.
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models = [ s.get_contents() for s in source[2:] ]
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parser = isa_parser.ISAParser(target[0].dir.abspath)
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parser.parse_isa_desc(source[0].abspath)
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isa_desc_action = MakeAction(isa_desc_action_func, Transform("ISA DESC", 1))
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# Also include the CheckerCPU as one of the models if it is being
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# enabled via command line.
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isa_desc_builder = Builder(action=isa_desc_action, emitter=isa_desc_emitter)
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desc_action = MakeAction(run_parser, Transform("ISA DESC", 1))
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env.Append(BUILDERS = { 'ISADesc' : isa_desc_builder })
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IsaDescBuilder = Builder(action=desc_action)
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# The ISA is generated twice: the first time to find out what it generates,
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# and the second time to make scons happy by telling the ISADesc builder
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# what it will make before it builds it.
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def scan_isa_deps(target, source, env):
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# Process dependency file generated by the ISA parser --
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# add the listed files to the dependency tree of the build.
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source = source[0]
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archbase = source.dir.up().path
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try:
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depfile = open(source.abspath, 'r')
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except:
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print "scan_isa_deps: Can't open ISA deps file '%s' in %s" % \
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(source.path,os.getcwd())
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raise
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# ISAs should use this function to set up an IsaDescBuilder and not try to
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# set one up manually.
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def ISADesc(desc, decoder_splits=1, exec_splits=1):
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'''Set up a builder for an ISA description.
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# Scan through the lines
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targets = {}
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for line in depfile:
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# Read the dependency line with the format
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# <target file>: [ <dependent file>* ]
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m = re.match(r'^\s*([^:]+\.([^\.:]+))\s*:\s*(.*)', line)
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assert(m)
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targ, extn = m.group(1,2)
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deps = m.group(3).split()
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The decoder_splits and exec_splits parameters let us determine what
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files the isa parser is actually going to generate. This needs to match
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what files are actually generated, and there's no specific check for that
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right now.
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files = [ targ ] + deps
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for f in files:
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targets[f] = True
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# Eliminate unnecessary re-generation if we already generated it
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env.Precious(os.path.join(archbase, 'generated', f))
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If the parser itself is responsible for generating a list of its products
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and their dependencies, then using that output to set up the right
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dependencies. This is what we used to do. The problem is that scons
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fundamentally doesn't support using a build product to affect its graph
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of possible products, dependencies, builders, etc. There are a couple ways
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to work around that limitation.
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files = [ os.path.join(archbase, 'generated', f) for f in files ]
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One option is to compute dependencies while the build phase of scons is
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running. That method can be quite complicated and cumbersome, because we
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have to make sure our modifications are made before scons tries to
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consume them. There's also no guarantee that this mechanism will work since
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it subverts scons expectations and changes things behind its back. This
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was implemented previously and constrained the builds parallelism
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significantly.
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if extn == 'cc':
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Source(os.path.join(archbase,'generated', targ))
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depfile.close()
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env[env['TARGET_ISA'] + '_isa_outputs'] = targets.keys()
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Another option would be to recursively call scons to have it update the
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list of products/dependencies during the setup phase of this invocation of
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scons. The problem with that is that it would be very difficult to make
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the sub-invocation of scons observe the options passed to the primary one
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in all possible cases, or to even determine conclusively what the name of
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the scons executable is in the first place.
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isa = env.ISADesc(os.path.join(archbase,'isa','main.isa'))
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for t in targets:
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env.Depends('#all-isas', isa)
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Possible future changes to the isa parser might make it easier to
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determine what files it would generate, perhaps because there was a more
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direct correspondence between input files and output files. Or, if the
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parser could run quickly and determine what its output files would be
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without having do actually generate those files, then it could be run
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unconditionally without slowing down all builds or touching the output
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files unnecessarily.
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'''
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generated_dir = File(desc).dir.up().Dir('generated')
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def gen_file(name):
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return generated_dir.File(name)
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env.Append(BUILDERS = {'ScanISA' :
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Builder(action=MakeAction(scan_isa_deps,
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Transform("NEW DEPS", 1)))})
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gen = []
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def add_gen(name):
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gen.append(gen_file(name))
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# Tell scons about the various files the ISA parser will generate.
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add_gen('decoder-g.cc.inc')
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add_gen('decoder-ns.cc.inc')
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add_gen('decode-method.cc.inc')
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add_gen('decoder.hh')
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add_gen('decoder-g.hh.inc')
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add_gen('decoder-ns.hh.inc')
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add_gen('exec-g.cc.inc')
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add_gen('exec-ns.cc.inc')
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add_gen('max_inst_regs.hh')
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# These generated files are also top level sources.
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def source_gen(name):
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add_gen(name)
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Source(gen_file(name))
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source_gen('decoder.cc')
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if decoder_splits == 1:
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source_gen('inst-constrs.cc')
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else:
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for i in range(1, decoder_splits + 1):
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source_gen('inst-constrs-%d.cc' % i)
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if exec_splits == 1:
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source_gen('generic_cpu_exec.cc')
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else:
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for i in range(1, exec_splits + 1):
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source_gen('generic_cpu_exec_%d.cc' % i)
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# Actually create the builder.
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sources = [desc, parser_py, micro_asm_py]
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IsaDescBuilder(target=gen, source=sources, env=env)
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return gen
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Export('ISADesc')
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DebugFlag('IntRegs')
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DebugFlag('FloatRegs')
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