SERVER-28390 Mark targets as Precious during incremental links

(cherry picked from commit 21628d6b2311eb726c01244f6c5dba1edb1f6256)

3 files changed, 50 insertions, 0 deletions

diff --git a/SConstruct b/SConstruct
index 19e0e671c4b..bb23b1287cb 100644
--- a/SConstruct
+++ b/SConstruct
@@ -2902,6 +2902,10 @@ if split_dwarf.exists(env):
 # compilation database entries for the configure tests, which is weird.
 env.Tool("compilation_db")
 
+incremental_link = Tool('incremental_link')
+if incremental_link.exists(env):
+    incremental_link(env)
+
 def checkErrorCodes():
     import buildscripts.errorcodes as x
     if x.checkErrorCodes() == False:
diff --git a/etc/scons/gold_incremental_link.vars b/etc/scons/gold_incremental_link.vars
new file mode 100644
index 00000000000..e298392f506
--- /dev/null
+++ b/etc/scons/gold_incremental_link.vars
@@ -0,0 +1 @@
+LINKFLAGS="-fuse-ld=gold -fno-use-linker-plugin -Wl,-z,norelro -Wl,--incremental"
diff --git a/site_scons/site_tools/incremental_link.py b/site_scons/site_tools/incremental_link.py
new file mode 100644
index 00000000000..cf74ef9674c
--- /dev/null
+++ b/site_scons/site_tools/incremental_link.py
@@ -0,0 +1,45 @@
+# 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
+
+def _tag_as_precious(target, source, env):
+    env.Precious(target)
+    return target, source
+
+def generate(env):
+    builders = env['BUILDERS']
+    for builder in ('Program', 'SharedLibrary', 'LoadableModule'):
+        emitter = builders[builder].emitter
+        builders[builder].emitter = SCons.Builder.ListEmitter([
+            emitter,
+            _tag_as_precious,
+        ])
+
+def exists(env):
+    # By default, the windows linker is incremental, so unless
+    # overridden in the environment with /INCREMENTAL:NO, the tool is
+    # in play.
+    if env.TargetOSIs('windows') and not "/INCREMENTAL:NO" in env['LINKFLAGS']:
+        return True
+
+    # On posix platforms, excluding darwin, we may have enabled
+    # incremental linking. Check for the relevant flags.
+    if env.TargetOSIs('posix') and \
+       not env.TargetOSIs('darwin') and \
+       "-fuse-ld=gold" in env['LINKFLAGS'] and \
+       "-Wl,--incremental" in env['LINKFLAGS']:
+        return True
+
+    return False