Changeset 201645 in webkit

Timestamp:

Jun 3, 2016 9:43:10 AM (8 years ago)

Author:

akling@apple.com

Message:

Eliminate two large sources of temporary StringImpl objects.
<​https://webkit.org/b/158336>

Reviewed by Anders Carlsson.

We were jumping through some inefficient hoops when creating Identifiers due to the
convenience of our String(const char*) constructor.

This patch avoids just over 1 million temporary StringImpl objects on the PLUM benchmark.

• runtime/JSObject.h:

(JSC::makeIdentifier): Add an overload for string literals so we can stop creating a temporary
String just for passing to Identifier::fromString().

• runtime/Lookup.h:

(JSC::reifyStaticProperties): Use the Identifier::fromString() that takes an LChar* and a length
instead of creating a temporary String.

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• runtime/JSObject.h (modified) (1 diff)
• runtime/Lookup.h (modified) (1 diff)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2016-06-03  Andreas Kling  <akling@apple.com>
+
+        Eliminate two large sources of temporary StringImpl objects.
+        <https://webkit.org/b/158336>
+
+        Reviewed by Anders Carlsson.
+
+        We were jumping through some inefficient hoops when creating Identifiers due to the
+        convenience of our String(const char*) constructor.
+
+        This patch avoids just over 1 million temporary StringImpl objects on the PLUM benchmark.
+
+        * runtime/JSObject.h:
+        (JSC::makeIdentifier): Add an overload for string literals so we can stop creating a temporary
+        String just for passing to Identifier::fromString().
+
+        * runtime/Lookup.h:
+        (JSC::reifyStaticProperties): Use the Identifier::fromString() that takes an LChar* and a length
+        instead of creating a temporary String.
+
 2016-06-03  Mark Lam  <mark.lam@apple.com>
 

trunk/Source/JavaScriptCore/runtime/JSObject.h

@@ -1625 +1625 @@
 COMPILE_ASSERT(!(sizeof(JSObject) % sizeof(WriteBarrierBase<Unknown>)), JSObject_inline_storage_has_correct_alignment);
 
+template<unsigned charactersCount>
+ALWAYS_INLINE Identifier makeIdentifier(VM& vm, const char (&characters)[charactersCount])
+{
+    return Identifier::fromString(&vm, characters);
+}
+
 ALWAYS_INLINE Identifier makeIdentifier(VM& vm, const char* name)
 {

trunk/Source/JavaScriptCore/runtime/Lookup.h

@@ -429 +429 @@
         if (!value.m_key)
             continue;
-        auto key = Identifier::fromString(&vm, value.m_key);
+        auto key = Identifier::fromString(&vm, reinterpret_cast<const LChar*>(value.m_key), strlen(value.m_key));
         reifyStaticProperty(vm, key, value, thisObj);
     }