1 files changed, 69 insertions, 7 deletions

diff --git a/src/arch/SConscript b/src/arch/SConscript
index e7d74ce51..e9b5c5365 100644
--- a/src/arch/SConscript
+++ b/src/arch/SConscript
@@ -30,6 +30,7 @@
 
 import sys
 import os
+import re
 
 Import('*')
 
@@ -97,18 +98,32 @@ def isa_desc_emitter(target, source, env):
     cpu_models = list(env['CPU_MODELS'])
     cpu_models.append('CheckerCPU')
 
-    # Several files are generated from the ISA description.
-    # We always get the basic decoder and header file.
-    target = [ 'decoder.cc', 'decoder.hh', 'max_inst_regs.hh' ]
-    # We also get an execute file for each selected CPU model.
-    target += [CpuModel.dict[cpu].filename for cpu in cpu_models]
-
     # List the isa parser as a source.
     source += [ isa_parser ]
     # Add in the CPU models.
     source += [ Value(m) for m in cpu_models ]
 
-    return [os.path.join("generated", t) for t in target], source
+    # Specify different targets depending on if we're running the ISA
+    # parser for its dependency information, or for the generated files.
+    # (As an optimization, the ISA parser detects the useless second run
+    # and skips doing any work, if the first run was performed, since it
+    # always generates all its files). The way we track this in SCons is the
+    # <arch>_isa_outputs value in the environment (env). If it's unset, we
+    # don't know what the dependencies are so we ask for generated/inc.d to
+    # be generated so they can be acquired. If we know what they are, then
+    # it's because we've already processed inc.d and then claim that our
+    # outputs (targets) will be thus.
+    isa = env['TARGET_ISA']
+    key = '%s_isa_outputs' % isa
+    if key in env:
+        targets = [ os.path.join('generated', f) for f in env[key] ]
+    else:
+        targets = [ os.path.join('generated','inc.d') ]
+
+    def prefix(s):
+        return os.path.join(target[0].dir.up().abspath, s)
+
+    return [ prefix(t) for t in targets ], source
 
 ARCH_DIR = Dir('.')
 
@@ -133,6 +148,53 @@ isa_desc_builder = Builder(action=isa_desc_action, emitter=isa_desc_emitter)
 
 env.Append(BUILDERS = { 'ISADesc' : isa_desc_builder })
 
+# The ISA is generated twice: the first time to find out what it generates,
+# and the second time to make scons happy by telling the ISADesc builder
+# what it will make before it builds it.
+def scan_isa_deps(target, source, env):
+    # Process dependency file generated by the ISA parser --
+    # add the listed files to the dependency tree of the build.
+    source = source[0]
+    archbase = source.dir.up().path
+
+    try:
+        depfile = open(source.abspath, 'r')
+    except:
+        print "scan_isa_deps: Can't open ISA deps file '%s' in %s" % \
+              (source.path,os.getcwd())
+        raise
+
+    # Scan through the lines
+    targets = {}
+    for line in depfile:
+        # Read the dependency line with the format
+        # <target file>: [ <dependent file>* ]
+        m = re.match(r'^\s*([^:]+\.([^\.:]+))\s*:\s*(.*)', line)
+        assert(m)
+        targ, extn = m.group(1,2)
+        deps = m.group(3).split()
+
+        files = [ targ ] + deps
+        for f in files:
+            targets[f] = True
+            # Eliminate unnecessary re-generation if we already generated it
+            env.Precious(os.path.join(archbase, 'generated', f))
+
+        files = [ os.path.join(archbase, 'generated', f) for f in files ]
+
+        if extn == 'cc':
+            Source(os.path.join(archbase,'generated', targ))
+    depfile.close()
+    env[env['TARGET_ISA'] + '_isa_outputs'] = targets.keys()
+
+    isa = env.ISADesc(os.path.join(archbase,'isa','main.isa'))
+    for t in targets:
+        env.Depends('#all-isas', isa)
+
+env.Append(BUILDERS = {'ScanISA' :
+                        Builder(action=MakeAction(scan_isa_deps,
+                                                  Transform("NEW DEPS", 1)))})
+
 DebugFlag('IntRegs')
 DebugFlag('FloatRegs')
 DebugFlag('CCRegs')