Introduce StringImpl::createPreallocatedStatic

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

Index: third_party/WebKit/Source/wtf/text/StringImpl.cpp
diff --git a/third_party/WebKit/Source/wtf/text/StringImpl.cpp b/third_party/WebKit/Source/wtf/text/StringImpl.cpp
index 303ee9d1ddd1707c356393bd1b2eabdde4c4fce9..9591ba9a05404eae927f140c22f2482dfb14a4af 100644
--- a/third_party/WebKit/Source/wtf/text/StringImpl.cpp
+++ b/third_party/WebKit/Source/wtf/text/StringImpl.cpp
@@ -343,6 +343,34 @@ void StringImpl::freezeStaticStrings()
 
 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);