Rework the way SCons recurses into subdirectories, making it

automatic.  The point is that now a subdirectory can be added
to the build process just by creating a SConscript file in it.
The process has two passes.  On the first pass, all subdirs
of the root of the tree are searched for SConsopts files.
These files contain any command line options that ought to be
added for a particular subdirectory.  On the second pass,
all subdirs of the src directory are searched for SConscript
files.  These files describe how to build any given subdirectory.
I have added a Source() function.  Any file (relative to the
directory in which the SConscript resides) passed to that
function is added to the build.  Clean up everything to take
advantage of Source().
function is added to the list of files to be built.

--HG--
extra : convert_revision : 103f6b490d2eb224436688c89cdc015211c4fd30

src/arch/SConscript

@@ -28,13 +28,9 @@
 #
 # Authors: Steve Reinhardt
 
-import os.path, sys
+import sys
 
-# Import build environment variable from SConstruct.
-Import('env')
-
-# Right now there are no source files immediately in this directory
-sources = []
+Import('*')
 
 #################################################################
 #
@@ -66,7 +62,7 @@ isa_switch_hdrs = Split('''
         ''')
 
 # Set up this directory to support switching headers
-env.make_switching_dir('arch', isa_switch_hdrs, env)
+make_switching_dir('arch', isa_switch_hdrs, env)
 
 #################################################################
 #
@@ -100,7 +96,7 @@ execfile(cpu_models_file.srcnode().abspath)
 
 # Several files are generated from the ISA description.
 # We always get the basic decoder and header file.
-isa_desc_gen_files = Split('decoder.cc decoder.hh')
+isa_desc_gen_files = [ 'decoder.cc', 'decoder.hh' ]
 # We also get an execute file for each selected CPU model.
 isa_desc_gen_files += [CpuModel.dict[cpu].filename
                        for cpu in env['CPU_MODELS']]
@@ -128,14 +124,3 @@ else:
                                emitter = isa_desc_emitter)
 
 env.Append(BUILDERS = { 'ISADesc' : isa_desc_builder })
-
-#
-# Now include other ISA-specific sources from the ISA subdirectories.
-#
-
-isa = env['TARGET_ISA'] # someday this may be a list of ISAs
-
-# Let the target architecture define what additional sources it needs
-sources += SConscript(os.path.join(isa, 'SConscript'), exports = 'env')
-
-Return('sources')