Add profiling to code serializer.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index 718c0dc8fb00b5ef17ab95546612e5406305e897..8d59dbca2dc90c185eb9eede87562f6bdf69387e 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -960,15 +960,22 @@ Handle<SharedFunctionInfo> Compiler::CompileScript(
   MaybeHandle<SharedFunctionInfo> maybe_result;
   Handle<SharedFunctionInfo> result;
   if (extension == NULL) {
-    maybe_result = compilation_cache->LookupScript(
-        source, script_name, line_offset, column_offset,
-        is_shared_cross_origin, context);
-    if (maybe_result.is_null() && FLAG_serialize_toplevel &&
+    if (FLAG_serialize_toplevel &&
         compile_options == ScriptCompiler::kConsumeCodeCache) {
       return CodeSerializer::Deserialize(isolate, *cached_data, source);
+    } else {

[Yang, 2014/07/22 08:58:17]

Without this change, --cache=code for d8 has no effect, since the compilation
cache kicks in before we consume the code cache. We may change this later when
we turn on --serialize-toplevel by default, though.

+      maybe_result = compilation_cache->LookupScript(
+          source, script_name, line_offset, column_offset,
+          is_shared_cross_origin, context);
     }
   }
 
+  base::ElapsedTimer timer;
+  if (FLAG_profile_deserialization && FLAG_serialize_toplevel &&
+      compile_options == ScriptCompiler::kProduceCodeCache) {
+    timer.Start();
+  }
+
   if (!maybe_result.ToHandle(&result)) {
     // No cache entry found. Compile the script.
 
@@ -1002,6 +1009,10 @@ Handle<SharedFunctionInfo> Compiler::CompileScript(
       if (FLAG_serialize_toplevel &&
           compile_options == ScriptCompiler::kProduceCodeCache) {
         *cached_data = CodeSerializer::Serialize(isolate, result, source);
+        if (FLAG_profile_deserialization) {
+          PrintF("[Compiling and serializing %d bytes took %0.3f ms]\n",
+                 (*cached_data)->length(), timer.Elapsed().InMillisecondsF());
+        }
       }
     }