SERVER-20540 Add an emitter for .dwo generated by -gsplit-dwarf

(cherry picked from commit 39f71f9f17103d47ef9b1234cb506aa8ad420114)

3 files changed, 93 insertions, 16 deletions

diff --git a/SConstruct b/SConstruct
index b1942eac382..19e0e671c4b 100644
--- a/SConstruct
+++ b/SConstruct
@@ -887,8 +887,8 @@ envDict = dict(BUILD_ROOT=buildDir,
                UNITTEST_LIST='$BUILD_ROOT/unittests.txt',
                INTEGRATION_TEST_ALIAS='integration_tests',
                INTEGRATION_TEST_LIST='$BUILD_ROOT/integration_tests.txt',
-               CONFIGUREDIR=sconsDataDir.Dir('sconf_temp'),
-               CONFIGURELOG=sconsDataDir.File('config.log'),
+               CONFIGUREDIR='$BUILD_ROOT/scons/$VARIANT_DIR/sconf_temp',
+               CONFIGURELOG='$BUILD_ROOT/scons/config.log',
                INSTALL_DIR=installDir,
                CONFIG_HEADER_DEFINES={},
                LIBDEPS_TAG_EXPANSIONS=[],
@@ -2892,6 +2892,12 @@ def doConfigure(myenv):
 
 env = doConfigure( env )
 
+# If the flags in the environment are configured for -gsplit-dwarf,
+# inject the necessary emitter.
+split_dwarf = Tool('split_dwarf')
+if split_dwarf.exists(env):
+    split_dwarf(env)
+
 # Load the compilation_db tool. We want to do this after configure so we don't end up with
 # compilation database entries for the configure tests, which is weird.
 env.Tool("compilation_db")
diff --git a/site_scons/site_tools/compilation_db.py b/site_scons/site_tools/compilation_db.py
index cd4619dcfa4..a8a9c8e603b 100644
--- a/site_scons/site_tools/compilation_db.py
+++ b/site_scons/site_tools/compilation_db.py
@@ -30,6 +30,16 @@ import itertools
 # communicate more gracefully?
 __COMPILATION_DB_ENTRIES=[]
 
+# Cribbed from Tool/cc.py and Tool/c++.py. It would be better if
+# we could obtain this from SCons.
+_CSuffixes = ['.c']
+if not SCons.Util.case_sensitive_suffixes('.c', '.C'):
+    _CSuffixes.append('.C')
+
+_CXXSuffixes = ['.cpp', '.cc', '.cxx', '.c++', '.C++']
+if SCons.Util.case_sensitive_suffixes('.c', '.C'):
+    _CXXSuffixes.append('.C')
+
 # We make no effort to avoid rebuilding the entries. Someday, perhaps we could and even
 # integrate with the cache, but there doesn't seem to be much call for it.
 class __CompilationDbNode(SCons.Node.Node):
@@ -99,20 +109,15 @@ def generate(env, **kwargs):
 
     static_obj, shared_obj = SCons.Tool.createObjBuilders(env)
 
-    # TODO: Is there a way to obtain the configured suffixes for C and C++
-    # from the existing obj builders? Seems unfortunate to re-iterate them.
-    CSuffixes = ['.c']
-    CXXSuffixes = ['.cc', '.cxx', '.cpp']
-
     env['COMPILATIONDB_COMSTR'] = kwargs.get(
         'COMPILATIONDB_COMSTR', 'Building compilation database $TARGET')
 
     components_by_suffix = itertools.chain(
-        itertools.product(CSuffixes, [
+        itertools.product(_CSuffixes, [
             (static_obj, SCons.Defaults.StaticObjectEmitter, '$CCCOM'),
             (shared_obj, SCons.Defaults.SharedObjectEmitter, '$SHCCCOM'),
         ]),
-        itertools.product(CXXSuffixes, [
+        itertools.product(_CXXSuffixes, [
             (static_obj, SCons.Defaults.StaticObjectEmitter, '$CXXCOM'),
             (shared_obj, SCons.Defaults.SharedObjectEmitter, '$SHCXXCOM'),
         ]),
@@ -122,13 +127,14 @@ def generate(env, **kwargs):
         suffix = entry[0]
         builder, base_emitter, command = entry[1]
 
-        builder.add_emitter(
-            suffix, SCons.Builder.ListEmitter(
-                [
-                    makeEmitCompilationDbEntry(command),
-                    base_emitter,
-                ]
-            ))
+        # Assumes a dictionary emitter
+        emitter = builder.emitter[suffix]
+        builder.emitter[suffix] = SCons.Builder.ListEmitter(
+            [
+                emitter,
+                makeEmitCompilationDbEntry(command),
+            ]
+        )
 
     env['BUILDERS']['__COMPILATIONDB_Entry'] = SCons.Builder.Builder(
         action=SCons.Action.Action(CompilationDbEntryAction, None),
diff --git a/site_scons/site_tools/split_dwarf.py b/site_scons/site_tools/split_dwarf.py
new file mode 100644
index 00000000000..95130c9e9a3
--- /dev/null
+++ b/site_scons/site_tools/split_dwarf.py
@@ -0,0 +1,65 @@
+# Copyright 2017 MongoDB Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import SCons
+
+_splitDwarfFlag = '-gsplit-dwarf'
+
+# Cribbed from Tool/cc.py and Tool/c++.py. It would be better if
+# we could obtain this from SCons.
+_CSuffixes = ['.c']
+if not SCons.Util.case_sensitive_suffixes('.c', '.C'):
+    _CSuffixes.append('.C')
+
+_CXXSuffixes = ['.cpp', '.cc', '.cxx', '.c++', '.C++']
+if SCons.Util.case_sensitive_suffixes('.c', '.C'):
+    _CXXSuffixes.append('.C')
+
+def _dwo_emitter(target, source, env):
+    new_targets = []
+    for t in target:
+        base, ext = SCons.Util.splitext(str(t))
+        if not any(ext == env[osuffix] for osuffix in ['OBJSUFFIX', 'SHOBJSUFFIX']):
+            continue
+        # TODO: Move 'dwo' into DWOSUFFIX so it can be customized? For
+        # now, GCC doesn't let you control the output filename, so it
+        # doesn't matter.
+        dwotarget = (t.builder.target_factory or env.File)(base + ".dwo")
+        new_targets.append(dwotarget)
+    targets = target + new_targets
+    return (targets, source)
+
+def generate(env):
+    suffixes = []
+    if _splitDwarfFlag in env['CCFLAGS']:
+        suffixes = _CSuffixes + _CXXSuffixes
+    else:
+        if _splitDwarfFlag in env['CFLAGS']:
+            suffixes.extend(_CSuffixes)
+        if _splitDwarfFlag in env['CXXFLAGS']:
+            suffixes.extend(_CXXSuffixes)
+
+    for object_builder in SCons.Tool.createObjBuilders(env):
+        emitterdict = object_builder.builder.emitter
+        for suffix in emitterdict.iterkeys():
+            if not suffix in suffixes:
+                continue
+            base = emitterdict[suffix]
+            emitterdict[suffix] = SCons.Builder.ListEmitter([
+                base,
+                _dwo_emitter,
+            ])
+
+def exists(env):
+    return any(_splitDwarfFlag in env[f] for f in ['CCFLAGS', 'CFLAGS', 'CXXFLAGS'])