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Reply-To: yang...@chromium.org, verwa...@chromium.org, v8-dev@googlegroups.com
Message-ID: <047d7b5d451614dbe004cdc02...@google.com>
Date: Mon, 05 Nov 2012 14:16:36 +0000
Subject: Reduce stack frame size in JSON.stringify. (issue 11366087)
From: yang...@chromium.org
To: verwa...@chromium.org
Cc: v8-dev@googlegroups.com
Content-Type: text/plain; charset=ISO-8859-1; format=flowed; delsp=yes

Reviewers: Toon Verwaest,

Message:
PTAL.

Description:
Reduce stack frame size in JSON.stringify.

BUG=


Please review this at http://codereview.chromium.org/11366087/

SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge

Affected files:
   M src/json-stringifier.h


Index: src/json-stringifier.h
diff --git a/src/json-stringifier.h b/src/json-stringifier.h
index  
f083ff4916856f820ed8048ffb132ca7803b11d2..1aa72b71b4e08a3f519696488cb2efe2ed3fd0d4  
100644
--- a/src/json-stringifier.h
+++ b/src/json-stringifier.h
@@ -567,28 +567,26 @@ BasicJsonStringifier::Result  
BasicJsonStringifier::SerializeJSObject(
    if (object->HasFastProperties() &&
        !object->HasIndexedInterceptor() &&
        !object->HasNamedInterceptor() &&
-      object->elements() == isolate_->heap()->empty_fixed_array()) {
-    Handle<DescriptorArray> descs(
-        object->map()->instance_descriptors(), isolate_);
-    int num_desc = object->map()->NumberOfOwnDescriptors();
+      object->elements()->length() == 0) {
      Handle<Map> map(object->map());
-    bool map_changed = false;
+    int num_desc = map->NumberOfOwnDescriptors();
      for (int i = 0; i < num_desc; i++) {
-      Handle<String> key(descs->GetKey(i), isolate_);
-      PropertyDetails details = descs->GetDetails(i);
+      Handle<String> key(map->instance_descriptors()->GetKey(i), isolate_);
+      PropertyDetails details = map->instance_descriptors()->GetDetails(i);
        if (details.IsDontEnum() || details.IsDeleted()) continue;
        Handle<Object> property;
-      if (details.type() == FIELD && !map_changed) {
+      if (details.type() == FIELD && *map == object->map()) {
          property = Handle<Object>(
-            object->FastPropertyAt(descs->GetFieldIndex(i)), isolate_);
+                       object->FastPropertyAt(
+                           map->instance_descriptors()->GetFieldIndex(i)),
+                       isolate_);
        } else {
          property = GetProperty(object, key);
+        if (property.is_null()) return EXCEPTION;
        }
-      if (property.is_null()) return EXCEPTION;
        Result result = SerializeProperty(property, comma, key);
        if (!comma && result == SUCCESS) comma = true;
        if (result >= EXCEPTION) return result;
-      if (*map != object->map()) map_changed = true;
      }
    } else {
      bool has_exception = false;