scons: allow building without duplicating source files

This adds a new scons flag --no-duplicate-sources to build without
linking source files to the build directory.

I find this very helpful when using CLion, since I can now generate a
compilation database using
`bear scons build/ALL/gem5.debug --no-duplicate-sources` and CLion will
now correctly semantically analyze all the files inside src/.
It also ensures that clicking on a build warning/error now opens the
real source file rather than a symlink.

This is not enabled by default since it's possible that certain use
cases are not working correctly, but the basic testing I've done so
far appears to work just fine.

It appears that with this change the `<root>/src` directory is no longer
added to `PYTHONPATH` when running `tests/main.py`, so this change
depends on https://gem5-review.git.corp.google.com/c/public/gem5/+/68757

Change-Id: Iddc9bf9c8211e68e5432c0a07f5c95f427c1ca16
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/68518
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>

SConstruct

@@ -145,6 +145,9 @@ AddOption('--gprof', action='store_true',
           help='Enable support for the gprof profiler')
 AddOption('--pprof', action='store_true',
           help='Enable support for the pprof profiler')
+AddOption('--no-duplicate-sources', action='store_false',
+          dest='duplicate_sources',
+          help='Do not create symlinks to sources in the build directory')
 
 # Inject the built_tools directory into the python path.
 sys.path[1:1] = [ Dir('#build_tools').abspath ]
@@ -264,6 +267,7 @@ main.Append(CPPPATH=[Dir('ext')])
 
 # Add shared top-level headers
 main.Prepend(CPPPATH=Dir('include'))
+main.Prepend(CPPPATH=Dir('src'))
 
 
 ########################################################################
@@ -774,11 +778,13 @@ Build variables for {dir}:
             build_dir = os.path.relpath(root, ext_dir)
             SConscript(os.path.join(root, 'SConscript'),
                        variant_dir=os.path.join(variant_ext, build_dir),
-                       exports=exports)
+                       exports=exports,
+                       duplicate=GetOption('duplicate_sources'))
 
     # The src/SConscript file sets up the build rules in 'env' according
     # to the configured variables.  It returns a list of environments,
     # one for each variant build (debug, opt, etc.)
-    SConscript('src/SConscript', variant_dir=variant_path, exports=exports)
+    SConscript('src/SConscript', variant_dir=variant_path, exports=exports,
+               duplicate=GetOption('duplicate_sources'))
 
 atexit.register(summarize_warnings)

ext/drampower/SConscript

@@ -41,7 +41,7 @@ import os
 
 Import('env')
 
-env.Prepend(CPPPATH=Dir('./src'))
+env.Prepend(CPPPATH=Dir('./src').srcnode())
 
 # Add the appropriate files for the library
 drampower_files = []

ext/dramsim2/SConscript

@@ -85,6 +85,6 @@ dramenv.Append(CCFLAGS=['-DNO_STORAGE'])
 
 dramenv.Library('dramsim2', [dramenv.SharedObject(f) for f in dram_files])
 
-env.Prepend(CPPPATH=Dir('.'))
+env.Prepend(CPPPATH=Dir('.').srcnode())
 env.Append(LIBS=['dramsim2'])
 env.Prepend(LIBPATH=[Dir('.')])

ext/dramsim3/SConscript

@@ -56,12 +56,12 @@ dramsim_path = os.path.join(Dir('#').abspath, 'ext/dramsim3/DRAMsim3/')
 
 if thermal:
     superlu_path = os.path.join(dramsim_path, 'ext/SuperLU_MT_3.1/lib')
-    env.Prepend(CPPPATH=Dir('.'))
+    env.Prepend(CPPPATH=Dir('.').srcnode())
     env.Append(LIBS=['dramsim3', 'superlu_mt_OPENMP', 'm', 'f77blas',
                       'atlas', 'gomp'],
                 LIBPATH=[dramsim_path, superlu_path])
 else:
-    env.Prepend(CPPPATH=Dir('.'))
+    env.Prepend(CPPPATH=Dir('.').srcnode())
     # a littel hacky but can get a shared library working
     env.Append(LIBS=['dramsim3', 'gomp'],
                 LIBPATH=[dramsim_path],  # compile-time lookup

ext/fputils/SConscript

@@ -30,7 +30,7 @@
 
 Import('env')
 
-env.Prepend(CPPPATH=Dir('./include'))
+env.Prepend(CPPPATH=Dir('./include').srcnode())
 
 fpenv = env.Clone()
 

ext/iostream3/SConscript

@@ -41,6 +41,6 @@ Import('env')
 
 env.Library('iostream3', [env.SharedObject('zfstream.cc')])
 
-env.Prepend(CPPPATH=Dir('.'))
+env.Prepend(CPPPATH=Dir('.').srcnode())
 env.Append(LIBS=['iostream3'])
 env.Prepend(LIBPATH=[Dir('.')])

ext/libelf/SConscript

@@ -127,16 +127,19 @@ if not SCons.Tool.m4.exists(m4env):
 # Setup m4 tool
 m4env.Tool('m4')
 
-m4env.Append(M4FLAGS=['-DSRCDIR=%s' % Dir('.').path])
+m4env.Append(M4FLAGS=['-DSRCDIR=%s' % Dir('.').srcnode().path])
 m4env['M4COM'] = '$M4 $M4FLAGS $SOURCES > $TARGET'
 m4env.M4(target=File('libelf_convert.c'),
-         source=[File('elf_types.m4'), File('libelf_convert.m4')])
+         source=[File('elf_types.m4').srcnode(),
+                 File('libelf_convert.m4').srcnode()])
 m4env.M4(target=File('libelf_fsize.c'),
-         source=[File('elf_types.m4'), File('libelf_fsize.m4')])
+         source=[File('elf_types.m4').srcnode(),
+                 File('libelf_fsize.m4').srcnode()])
 m4env.M4(target=File('libelf_msize.c'),
-         source=[File('elf_types.m4'), File('libelf_msize.m4')])
+         source=[File('elf_types.m4').srcnode(),
+                 File('libelf_msize.m4').srcnode()])
 
-m4env.Append(CPPPATH=Dir('.'))
+m4env.Append(CPPPATH=[Dir('.'), Dir('.').srcnode()])
 
 # Build libelf as a static library with PIC code so it can be linked
 # into either m5 or the library
@@ -146,6 +149,6 @@ m4env.Library('elf', [m4env.SharedObject(f) for f in elf_files])
 m4env.Command(File('native-elf-format.h'), File('native-elf-format'),
               '${SOURCE} > ${TARGET}')
 
-env.Prepend(CPPPATH=Dir('.'))
+env.Prepend(CPPPATH=Dir('.').srcnode())
 env.Append(LIBS=[File('libelf.a')])
 env.Prepend(LIBPATH=[Dir('.')])

ext/libfdt/SConscript

@@ -44,6 +44,6 @@ FdtFile('fdt_empty_tree.c')
 FdtFile('fdt_strerror.c')
 
 env.Library('fdt', [env.SharedObject(f) for f in fdt_files])
-env.Prepend(CPPPATH=Dir('.'))
+env.Prepend(CPPPATH=Dir('.').srcnode())
 env.Append(LIBS=['fdt'])
 env.Prepend(LIBPATH=[Dir('.')])

ext/nomali/SConscript

@@ -39,7 +39,7 @@
 
 Import('env')
 
-env.Prepend(CPPPATH=Dir('./include'))
+env.Prepend(CPPPATH=Dir('include').srcnode())
 
 nomali = env.Clone()
 nomali.Append(CCFLAGS=['-Wno-ignored-qualifiers'])

ext/softfloat/SConscript

@@ -420,6 +420,6 @@ else:
 
 sf_env.Library('softfloat', [sf_env.SharedObject(f) for f in softfloat_files])
 
-env.Prepend(CPPPATH=Dir('./'))
+env.Prepend(CPPPATH=Dir('.').srcnode())
 env.Append(LIBS=['softfloat'])
 env.Prepend(LIBPATH=[Dir('.')])

ext/systemc/SConscript

@@ -25,6 +25,7 @@
 
 import os
 from m5.util.terminal import get_termcap
+import gem5_scons
 
 Import('env')
 systemc = env.Clone()
@@ -32,36 +33,30 @@ systemc = env.Clone()
 build_root = Dir('.').abspath
 src_root = Dir('.').srcdir.abspath
 
-systemc.Prepend(CPPPATH=Dir('./src'))
+systemc.Prepend(CPPPATH=Dir('./src').srcnode())
 systemc.Prepend(CPATH=Dir('./src'))
 
 systemc.Prepend(CXXFLAGS=['-DSC_INCLUDE_FX'])
 systemc.Prepend(CFLAGS=['-DSC_INCLUDE_FX'])
 
-conf = Configure(systemc,
+with gem5_scons.Configure(systemc) as conf:
-                 conf_dir = os.path.join(build_root, '.scons_config'),
+    if systemc['PLATFORM'] == 'darwin':
-                 log_file = os.path.join(build_root, 'scons_config.log'))
+        systemc.Append(LINKFLAGS=['-undefined', 'dynamic_lookup'])
-systemc = conf.env
 
-if systemc['PLATFORM'] == 'darwin':
+    arch = None
-    systemc.Append(LINKFLAGS=['-undefined', 'dynamic_lookup'])
+    systemc['COROUTINE_LIB'] = ''
-
+    if conf.CheckDeclaration('__i386__'):
-arch = None
+        systemc['COROUTINE_LIB'] = 'qt'
-systemc['COROUTINE_LIB'] = ''
+        systemc['QT_ARCH'] = 'i386'
-if conf.CheckDeclaration('__i386__'):
+        arch = 'i386'
-    systemc['COROUTINE_LIB'] = 'qt'
+    elif conf.CheckDeclaration('__x86_64__'):
-    systemc['QT_ARCH'] = 'i386'
+        systemc['COROUTINE_LIB'] = 'qt'
-    arch = 'i386'
+        systemc['QT_ARCH'] = 'iX86_64'
-elif conf.CheckDeclaration('__x86_64__'):
+        arch = 'x86_64'
-    systemc['COROUTINE_LIB'] = 'qt'
+    else:
-    systemc['QT_ARCH'] = 'iX86_64'
+        termcap = get_termcap(GetOption('use_colors'))
-    arch = 'x86_64'
+        print(termcap.Yellow + termcap.Bold +
-else:
+              "Warning: Unrecognized architecture for systemc." + termcap.Normal)
-    termcap = get_termcap(GetOption('use_colors'))
-    print(termcap.Yellow + termcap.Bold +
-          "Warning: Unrecognized architecture for systemc." + termcap.Normal)
-
-systemc = conf.Finish()
 
 if systemc['COROUTINE_LIB'] == 'pthreads':
     systemc.Prepend(CXXFLAGS=['-DSC_USE_PTHREADS'])
@@ -77,7 +72,8 @@ if arch:
             build_dir = os.path.relpath(root, src_root)
             systemc.SConscript(os.path.join(root, 'SConscript.sc'),
                                exports=['systemc', 'SystemCSource'],
-                               variant_dir=os.path.join(build_root, build_dir))
+                               variant_dir=os.path.join(build_root, build_dir),
+                               duplicate=GetOption('duplicate_sources'))
 
     systemc.Library('libsystemc', systemc_files)
     systemc.SharedLibrary('libsystemc', systemc_files)

site_scons/gem5_scons/sources.py

@@ -261,13 +261,13 @@ class SourceFile(SourceItem):
         if self.append:
             env = env.Clone()
             env.Append(**self.append)
-        return env.StaticObject(self.tnode)
+        return env.StaticObject(self.tnode.abspath)
 
     def shared(self, env):
         if self.append:
             env = env.Clone()
             env.Append(**self.append)
-        return env.SharedObject(self.tnode)
+        return env.SharedObject(self.tnode.abspath)
 
 
 __all__ = [

src/SConscript

@@ -86,10 +86,10 @@ build_tools = Dir('#build_tools')
 # as gem5. This is in an unorthodox location to avoid building it for every
 # variant.
 gem5py_env = gem5py_env.Clone()
-gem5py = gem5py_env.File('gem5py')
+gem5py = gem5py_env.File('gem5py', Dir(gem5py_env['BUILDDIR']))
-gem5py_m5 = gem5py_env.File('gem5py_m5')
+gem5py_m5 = gem5py_env.File('gem5py_m5', Dir(gem5py_env['BUILDDIR']))
-gem5py_env['GEM5PY'] = gem5py
+gem5py_env['GEM5PY'] = gem5py.get_abspath()
-gem5py_env['GEM5PY_M5'] = gem5py_m5
+gem5py_env['GEM5PY_M5'] = gem5py_m5.get_abspath()
 gem5py_env['OBJSUFFIX'] = '.pyo'
 # Inject build_tools into PYTHONPATH for when we run gem5py.
 pythonpath = gem5py_env['ENV'].get('PYTHONPATH', '').split(':')
@@ -121,7 +121,7 @@ class PySource(SourceFile):
 
         self.modpath = modpath
 
-        cpp = File(self.filename + '.cc')
+        cpp = self.tnode.target_from_source('', '.py.cc').get_abspath()
 
         overrides = {
             'PYSOURCE_MODPATH': modpath,
@@ -169,12 +169,13 @@ class SimObject(PySource):
                 return ' '.join(list('"${%s}"' % arg for arg in all_args))
 
             # Params header.
+            params_hh = build_dir.File(f'params/{simobj}.hh').get_abspath()
             gem5py_env.Command([ "${PARAMS_HH}" ], srcs,
                     MakeAction(cmdline('PARAMS_HH'), Transform("SO Param", 2)),
                     MODULE=module,
                     SIMOBJ=simobj,
                     PYSCRIPT=build_tools.File('sim_object_param_struct_hh.py'),
-                    PARAMS_HH=build_dir.File(f'params/{simobj}.hh'))
+                    PARAMS_HH=params_hh)
 
             # Params cc.
             cc_file = build_dir.File(f'python/_m5/param_{simobj}.cc')
@@ -184,18 +185,19 @@ class SimObject(PySource):
                     PYSCRIPT=build_tools.File('sim_object_param_struct_cc.py'),
                     MODULE=module,
                     SIMOBJ=simobj,
-                    PARAMS_CC=cc_file,
+                    PARAMS_CC=cc_file.get_abspath(),
                     USE_PYTHON=env['USE_PYTHON'])
-            Source(cc_file, tags=self.tags,
+            Source(cc_file.get_abspath(), tags=self.tags,
                    add_tags=('python' if env['USE_PYTHON'] else None))
 
             # CXX config header.
+            config_hh = build_dir.File(f'cxx_config/{simobj}.hh').get_abspath()
             gem5py_env.Command([ "${CXXCONFIG_HH}" ], srcs,
                     MakeAction(cmdline('CXXCONFIG_HH'),
                         Transform("CXXCPRHH", 2)),
                     PYSCRIPT=build_tools.File('cxx_config_hh.py'),
                     MODULE=module,
-                    CXXCONFIG_HH=build_dir.File(f'cxx_config/{simobj}.hh'))
+                    CXXCONFIG_HH=config_hh)
 
             # CXX config cc.
             cc_file=build_dir.File(f'cxx_config/{simobj}.cc')
@@ -204,9 +206,9 @@ class SimObject(PySource):
                         Transform("CXXCPRCC", 2)),
                     PYSCRIPT=build_tools.File('cxx_config_cc.py'),
                     MODULE=module,
-                    CXXCONFIG_CC=cc_file)
+                    CXXCONFIG_CC=cc_file.get_abspath())
             if GetOption('with_cxx_config'):
-                Source(cc_file, tags=self.tags)
+                Source(cc_file.get_abspath(), tags=self.tags)
 
         # C++ versions of enum params.
         for enum in enums:
@@ -218,7 +220,7 @@ class SimObject(PySource):
                         Transform("ENUMDECL", 2)),
                     MODULE=module,
                     ENUM=enum,
-                    ENUM_HH=build_dir.File(f'enums/{enum}.hh'),
+                    ENUM_HH=build_dir.File(f'enums/{enum}.hh').get_abspath(),
                     ENUMHH_PY=build_tools.File('enum_hh.py'))
             cc_file = build_dir.File(f'enums/{enum}.cc')
             gem5py_env.Command([ "${ENUM_CC}" ],
@@ -229,10 +231,10 @@ class SimObject(PySource):
                         Transform("ENUM STR", 2)),
                     MODULE=module,
                     ENUM=enum,
-                    ENUM_CC=cc_file,
+                    ENUM_CC=cc_file.get_abspath(),
                     ENUMCC_PY=build_tools.File('enum_cc.py'),
                     USE_PYTHON=env['USE_PYTHON'])
-            Source(cc_file, tags=self.tags,
+            Source(cc_file.get_abspath(), tags=self.tags,
                    add_tags=('python' if env['USE_PYTHON'] else None))
 
 # This regular expression is simplistic and assumes that the import takes up
@@ -415,8 +417,9 @@ class Executable(TopLevelBase):
             cmd = 'cp $SOURCE $TARGET; strip $TARGET'
         else:
             cmd = 'strip $SOURCE -o $TARGET'
-        stripped = env.Command(str(executable) + '.stripped',
+        stripped = env.Command(executable.abspath + '.stripped',
-                executable, MakeAction(cmd, Transform("STRIP")))[0]
+                               executable.abspath,
+                               MakeAction(cmd, Transform("STRIP")))[0]
 
         return [executable, stripped]
 
@@ -550,7 +553,8 @@ for root, dirs, files in os.walk(base_dir, topdown=True):
 
     if 'SConscript' in files:
         build_dir = os.path.join(env['BUILDDIR'], root[len(base_dir) + 1:])
-        SConscript(os.path.join(root, 'SConscript'), variant_dir=build_dir)
+        SConscript(os.path.join(root, 'SConscript'), variant_dir=build_dir,
+                   duplicate=GetOption('duplicate_sources'))
 
 for extra_dir in extras_dir_list:
     prefix_len = len(os.path.dirname(extra_dir)) + 1
@@ -566,7 +570,8 @@ for extra_dir in extras_dir_list:
 
         if 'SConscript' in files:
             build_dir = os.path.join(env['BUILDDIR'], root[prefix_len:])
-            SConscript(os.path.join(root, 'SConscript'), variant_dir=build_dir)
+            SConscript(os.path.join(root, 'SConscript'), variant_dir=build_dir,
+                       duplicate=GetOption('duplicate_sources'))
 
 for opt in env['CONF'].keys():
     env.ConfigFile(opt)

src/mem/slicc/symbols/SymbolTable.py

@@ -40,7 +40,7 @@ def makeDir(path):
         if not os.path.isdir(path):
             raise AttributeError(f"{path} exists but is not directory")
     else:
-        os.mkdir(path)
+        os.makedirs(path, exist_ok=True)
 
 
 class SymbolTable(object):

util/m5/SConstruct

@@ -179,10 +179,12 @@ native_dir = build_dir.Dir('native')
 
 # Bring in the googletest sources.
 native.SConscript(googletest_dir.File('SConscript'),
-        variant_dir=native_dir.Dir('googletest'), exports={ 'env': native })
+        variant_dir=native_dir.Dir('googletest'), exports={ 'env': native },
+                  duplicate=GetOption('duplicate_sources'))
 
 native.SConscript(src_dir.File('SConscript.native'),
-        variant_dir=native_dir, exports={ 'env': native })
+        variant_dir=native_dir, exports={ 'env': native },
+                  duplicate=GetOption('duplicate_sources'))
 
 main['CC'] = '${CROSS_COMPILE}gcc'
 main['CXX'] = '${CROSS_COMPILE}g++'
@@ -268,6 +270,7 @@ for root, dirs, files in os.walk(abspath(src_dir)):
         # Bring in the googletest sources.
         env.SConscript(googletest_dir.File('SConscript'),
                 variant_dir=abi_dir.Dir('googletest'),
-                exports='env')
+                exports='env', duplicate=GetOption('duplicate_sources'))
         env.SConscript(src_dir.File('SConscript'),
-                       variant_dir=abi_dir, exports='env')
+                       variant_dir=abi_dir, exports='env',
+                       duplicate=GetOption('duplicate_sources'))

util/statetrace/SConstruct

@@ -62,4 +62,5 @@ for arch in arches:
     env['CXX'] = ARGUMENTS.get(arch.upper() + 'CXX', env['CXX'])
     env.Append(CPPFLAGS = '-D__STATETRACE_%s__' % arch.upper())
     Export('env', 'arch')
-    env.SConscript('SConscript', variant_dir = os.path.join('build', arch))
+    env.SConscript('SConscript', variant_dir=os.path.join('build', arch),
+                   duplicate=GetOption('duplicate_sources'))

util/tlm/SConstruct

@@ -66,11 +66,13 @@ if gem5_variant == 'debug':
 
 deps = [] # keep track of all dependencies required for building the binaries
 
-deps += SConscript('src/SConscript', variant_dir='build/tlm', exports='env')
+deps += SConscript('src/SConscript', variant_dir='build/tlm', exports='env',
+                   duplicate=GetOption('duplicate_sources'))
 
 deps += SConscript('examples/common/SConscript',
                    variant_dir='build/examples/common',
-                   exports=['env'])
+                   exports=['env'],
+                   duplicate=GetOption('duplicate_sources'))
 
 # the SystemC SConscript makes certain assumptions, we need to fulfill these
 # assumptions before calling the SConscript.
@@ -81,7 +83,7 @@ AddOption('--no-colors', dest='use_colors', action='store_false',
 env.SConsignFile('build/systemc/sconsign')
 SConscript(gem5_root + '/ext/systemc/SConscript',
            variant_dir='build/systemc',
-           exports='env')
+           exports='env', duplicate=GetOption('duplicate_sources'))
 
 # By adding libraries as dependencies instead of using LIBS, we avoid that
 # the user needs to set the LD_LIBRARY_PATH
@@ -91,10 +93,12 @@ deps.append(File(os.path.join(gem5_root, 'build', gem5_arch,
 
 ex_master = SConscript('examples/master_port/SConscript',
                        variant_dir='build/examples/master_port',
-                       exports=['env', 'deps'])
+                       exports=['env', 'deps'],
+                       duplicate=GetOption('duplicate_sources'))
 
 ex_slave = SConscript('examples/slave_port/SConscript',
                       variant_dir='build/examples/slave_port',
-                      exports=['env', 'deps'])
+                      exports=['env', 'deps'],
+                      duplicate=GetOption('duplicate_sources'))
 
 Default(ex_master + ex_slave)