gn: Add an 'optimize' config for components

build/config/compiler/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/android/config.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/cc_wrapper.gni")
 import("//build/toolchain/toolchain.gni")
@@ skipping 1290 matching lines @@
 
     # Don't use gc-sections since it can cause links to succeed when they
     # actually shouldn't. http://crbug.com/159847
     ldflags = common_optimize_on_ldflags - [ "-Wl,--gc-sections" ]
   } else {
     cflags = [ "-O0" ]
     ldflags = []
   }
 }
 
-# Turns up the optimization level. On Windows, this implies whole program
-# optimization and link-time code generation which is very expensive and should
-# be used sparingly.
-config("optimize_max") {
+# Internal common config used by optimize_max and optimize_component.
+config("common_optimize_max") {

[Michael Achenbach, 2016/05/30 11:38:07]

Is there a better way to share a common config without making it publicly
available?

[Dirk Pranke, 2016/05/31 19:46:18]

Not really, but it's not something we tend to worry about yet.

   if (is_nacl_irt) {
     # The NaCl IRT is a special case and always wants its own config.
     # Various components do:
     #   if (!is_debug) {
     #     configs -= [ "//build/config/compiler:default_optimization" ]
     #     configs += [ "//build/config/compiler:optimize_max" ]
     #   }
     # So this config has to have the selection logic just like
     # "default_optimization", below.
     configs = [ "//build/config/nacl:irt_optimize" ]
   } else {
     ldflags = common_optimize_on_ldflags
     if (is_win) {
       # Favor speed over size, /O2 must be before the common flags. The GYP
       # build also specifies /Ot, /Oi, and /GF, but these are implied by /O2.
       cflags = [ "/O2" ] + common_optimize_on_cflags
 
       # TODO(thakis): Remove is_clang here, https://crbug.com/598772
       if (is_official_build && !is_clang) {
         cflags += [
           "/GL",  # Whole program optimization.
 
           # Disable Warning 4702 ("Unreachable code") for the WPO/PGO builds.
           # Probably anything that this would catch that wouldn't be caught in a
           # normal build isn't going to actually be a bug, so the incremental
           # value of C4702 for PGO builds is likely very small.
           "/wd4702",
         ]
       }
-    } else {
+    }
+  }
+}
+
+# Turns up the optimization level. On Windows, this implies whole program
+# optimization and link-time code generation which is very expensive and should
+# be used sparingly.
+config("optimize_max") {
+  configs = [ ":common_optimize_max" ]

[Michael Achenbach, 2016/05/30 11:38:07]

Does the line:
configs -= ["optimize_max"]
also remove subconfigs like common_optimize_max?

[Dirk Pranke, 2016/05/31 19:46:18]

Yes, I think so.

+  if (!is_nacl_irt) {
+    if (!is_win) {
       cflags = [ "-O2" ] + common_optimize_on_cflags
     }
   }
 }
 
+# Some components like v8 use higher optimization levels on linux and mac.
+config("optimize_component") {

[Michael Achenbach, 2016/05/30 11:38:07]

Named this optimize_component as I don't like optimize_really_max. Any better
ideas for a name?

+  configs = [ ":common_optimize_max" ]
+  if (!is_nacl_irt) {
+    if (!is_win) {
+      cflags = [ "-O3" ] + common_optimize_on_cflags
+    }
+  }
+}
+
 # The default optimization applied to all targets. This will be equivalent to
 # either "optimize" or "no_optimize", depending on the build flags.
 config("default_optimization") {
   if (is_nacl_irt) {
     # The NaCl IRT is a special case and always wants its own config.
     # It gets optimized the same way regardless of the type of build.
     configs = [ "//build/config/nacl:irt_optimize" ]
   } else if (is_debug) {
     configs = [ ":no_optimize" ]
   } else {
@@ skipping 89 matching lines @@
 
 if (is_ios || is_mac) {
   # On Mac and iOS, this enables support for ARC (automatic ref-counting).
   # See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
   config("enable_arc") {
     common_flags = [ "-fobjc-arc" ]
     cflags_objc = common_flags
     cflags_objcc = common_flags
   }
 }