Enable incremental linking in release component builds

build/config/win/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/clang/clang.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/win/visual_studio_version.gni")
 import("//build/toolchain/toolchain.gni")
 
@@ skipping 84 matching lines @@
     }
 
     # Clang runtime libraries, such as the sanitizer runtimes, live here.
     lib_dirs = [ "$clang_base_path/lib/clang/$clang_version/lib/windows" ]
   }
 
   # Ensures that the PDB file contains FIXUP information (growing the PDB file
   # by about 5%) but does not otherwise alter the output binary. This
   # information is used by the Syzygy optimization tool when decomposing the
   # release image.
-  if (!is_debug && !is_win_fastlink && !is_clang) {
+  if (!is_debug && !is_win_fastlink && !is_clang && !is_component_build) {

[Peter Kasting, 2016/09/14 01:15:17]

Should this match the condition on line 317?  I'm wondering if we should still
have this flag for the "is_syzyasan" case since we don't incrementally link in
that case anyway.

[brucedawson, 2016/09/14 17:49:25]

I had been thinking that it didn't really matter - not all combinations of the
flags are supported or used - but special casing syzyasan is easy enough.

Done.

     ldflags = [ "/PROFILE" ]
   }
 
   # arflags apply only to static_libraries. The normal linker configs are only
   # set for executable and shared library targets so arflags must be set
   # elsewhere. Since this is relatively contained, we just apply them in this
   # more general config and they will only have an effect on static libraries.
   arflags = [
     # "No public symbols found; archive member will be inaccessible." This
     # means that one or more object files in the library can never be
@@ skipping 189 matching lines @@
 }
 config("windowed") {
   ldflags = [ "/SUBSYSTEM:WINDOWS$subsystem_version_suffix" ]
 }
 
 # Incremental linking ----------------------------------------------------------
 
 incremental_linking_on_switch = [ "/INCREMENTAL" ]
 incremental_linking_off_switch = [ "/INCREMENTAL:NO" ]
 
-# Disable incremental linking for syzyasan
-if (is_debug && !is_syzyasan) {
+# Disable incremental linking for syzyasan, enable for debug builds and all
+# component builds - any builds where performance is not job one.
+if ((is_debug || is_component_build) && !is_syzyasan) {
   default_incremental_linking_switch = incremental_linking_on_switch
 } else {
   default_incremental_linking_switch = incremental_linking_off_switch
 }
 
 # Applies incremental linking or not depending on the current configuration.
 config("default_incremental_linking") {
   ldflags = default_incremental_linking_switch
 }
 
@@ skipping 65 matching lines @@
 
 # Internal stuff --------------------------------------------------------------
 
 # Config used by the MIDL template to disable warnings.
 config("midl_warnings") {
   if (is_clang) {
     # MIDL generates code like "#endif !_MIDL_USE_GUIDDEF_".
     cflags = [ "-Wno-extra-tokens" ]
   }
 }