Create a Builder object for .isa files in arch/SConscript.

Start using SCons File objects to avoid fixed paths in
subordinate SConscripts.

SConscript:
    Push isa_parser stuff (including .isa scanner) down into
    arch/SConscript.
arch/SConscript:
    Create a Builder object for .isa files, including existing scanner.
    Return file objects generated by isa-specific SConscript
    back up to parent.
arch/alpha/SConscript:
arch/mips/SConscript:
arch/sparc/SConscript:
    Convert sources to scons File objects, so file names can be specified
    relative to the current directory.
    Invoke new builder for isa description, and get generated sources from
    there (instead of listing them explicitly).
arch/isa_parser.py:
    Get rid of third argument ("include_path").
    It was a pain to generate this from scons, and it turned out
    it's not needed anyway, since the only included file
    (decoder.hh) will be in the same directory as the sources.

--HG--
extra : convert_revision : 36861bcef36763f229704d8cb7a642b4486a3581

arch/SConscript

@@ -31,11 +31,17 @@ import os.path
 # Import build environment variable from SConstruct.
 Import('env')
 
+# Right now there are no source files immediately in this directory
+sources = []
+
+#################################################################
 #
 # ISA "switch header" generation.
 #
 # Auto-generate arch headers that include the right ISA-specific
 # header based on the setting of THE_ISA preprocessor variable.
+#
+#################################################################
 
 # List of headers to generate
 isa_switch_hdrs = Split('''
@@ -72,3 +78,69 @@ switch_hdr_action = Action(gen_switch_hdr, gen_switch_hdr_string,
 # Instantiate actions for each header
 for hdr in isa_switch_hdrs:
     env.Command(hdr, [], switch_hdr_action)
+
+#################################################################
+#
+# Include architecture-specific files.
+#
+#################################################################
+
+#
+# Build a SCons scanner for ISA files
+#
+import SCons.Scanner
+
+def ISAScan():
+   return SCons.Scanner.Classic("ISAScan",
+                                "$ISASUFFIXES",
+                                "SRCDIR",
+                                '^[ \t]*##[ \t]*include[ \t]*"([^>"]+)"')
+
+def ISAPath(env, dir, target=None, source=None, a=None):
+   return (Dir(env['SRCDIR']), Dir('.'))   
+
+iscan = Scanner(function = ISAScan().scan, skeys = [".isa", ".ISA"],
+                path_function = ISAPath)
+env.Append(SCANNERS = iscan)
+
+#
+# Now create a Builder object that uses isa_parser.py to generate C++
+# output from the ISA description (*.isa) files.
+#
+
+# several files are generated from the ISA description
+isa_desc_gen_files = Split('''
+	decoder.cc
+        alpha_o3_exec.cc
+	fast_cpu_exec.cc
+        simple_cpu_exec.cc
+        full_cpu_exec.cc
+	decoder.hh
+        ''')
+
+# Convert to File node to fix path
+isa_parser = File('isa_parser.py')
+
+# The emitter patches up the sources & targets to include the
+# autogenerated files as targets and isa parser itself as a source.
+def isa_desc_emitter(target, source, env):
+    return (isa_desc_gen_files, [isa_parser] + source)
+
+# Pieces are in place, so create the builder.
+isa_desc_builder = Builder(action='${SOURCES[0]} ${SOURCES[1]} $TARGET.dir',
+                           source_scanner = iscan,
+                           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', duplicate = False)
+
+Return('sources')