gn: Add an 'optimize' config for components

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 5e1e024ea5ff15eebdb3307d77058d67673073c9..4c32281faba650b5b8856c5ff9632376b2421c5d 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -1308,10 +1308,8 @@ config("no_optimize") {
   }
 }
 
-# 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:
@@ -1341,12 +1339,32 @@ config("optimize_max") {
           "/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") {