Introduce StringImpl::createPreallocatedStatic

third_party/WebKit/Source/wtf/text/StringImpl.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller ( mueller@kde.org )
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Andrew Wellington (proton@wiretapped.net)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 325 matching lines @@
 {
     ASSERT(isMainThread());
 
 #if ENABLE(ASSERT)
     s_allowCreationOfStaticStrings = false;
 #endif
 }
 
 unsigned StringImpl::m_highestStaticStringLength = 0;
 
+StringImpl* StringImpl::createPreallocatedStatic(void* buffer, unsigned length, unsigned hash)
+{
+    ASSERT(s_allowCreationOfStaticStrings);
+    ASSERT(buffer);
+    ASSERT(length);
+
+    StringImpl* impl = static_cast<StringImpl*>(buffer);
+
+    StaticStringsTable::const_iterator it = staticStrings().find(hash);
+    if (it != staticStrings().end()) {
+        ASSERT(!memcmp(reinterpret_cast<LChar*>(impl + 1), it->value + 1, length * sizeof(LChar)));
+        return it->value;

[kouhei (in TOK), 2015/10/21 01:08:17]

Are we ever going to reach here? If not, ASSERT?

[tzik, 2015/10/28 14:33:31]

We do actually reach here due to duplicated static strings, namely:
a, autocomplete, color, direction, end, height, href, image, lang, max,
media, method, min, name, onfocusin, onfocusout, pattern, readonly, role,
script, style, target, text, title, type, version, width, xmlns

+    }
+
+    impl = new (impl) StringImpl(length, hash, StaticString);
+#if ENABLE(ASSERT)
+    impl->assertHashIsCorrect();
+#endif
+
+    ASSERT(isMainThread());
+    m_highestStaticStringLength = std::max(m_highestStaticStringLength, length);
+    staticStrings().add(hash, impl);
+    WTF_ANNOTATE_BENIGN_RACE(impl,
+        "Benign race on the reference counter of a static string created by StringImpl::createStatic");

[tkent, 2015/10/21 03:19:34]

createStatic -> createPreallocatedStatic?

[tzik, 2015/10/28 14:33:31]

Done.

+
+    return impl;
+}
+
 StringImpl* StringImpl::createStatic(const char* string, unsigned length, unsigned hash)
 {
     ASSERT(s_allowCreationOfStaticStrings);
     ASSERT(string);
     ASSERT(length);
 
     StaticStringsTable::const_iterator it = staticStrings().find(hash);
     if (it != staticStrings().end()) {
         ASSERT(!memcmp(string, it->value + 1, length * sizeof(LChar)));
         return it->value;
@@ skipping 1753 matching lines @@
         } else if (localeIdMatchesLang(localeIdentifier, "lt")) {
             // TODO(rob.buis) implement upper-casing rules for lt
             // like in StringImpl::upper(locale).
         }
     }
 
     return toUpper(c);
 }
 
 } // namespace WTF