Changeset 39675 in webkit for trunk/JavaScriptCore/bytecompiler

Timestamp:

Jan 7, 2009, 12:16:52 AM (16 years ago)

Author:

[email protected]

Message:

2009-01-06 Gavin Barraclough <​[email protected]>

Reviewed by Maciej Stachowiak.

Replace accidentally removed references in BytecodeGenerator, deleting these
will be hindering the sharing of constant numbers and strings.

The code to add a new constant (either number or string) to their respective
map works by attempting to add a null entry, then checking the result of the
add for null. The first time, this should return the null (or noValue).
The code checks for null (to see if this is the initial add), and then allocates
a new number / string object. This code relies on the result returned from
the add to the map being stored as a reference, such that the allocated object
will be stored in the map, and will be resused if the same constant is encountered
again. By failing to use a reference we will be leaking GC object for each
additional entry added to the map. As GC objects they should be clollected,
be we should no be allocatin them in the first place.

​https://bugs.webkit.org/show_bug.cgi?id=23158

• bytecompiler/BytecodeGenerator.cpp: (JSC::BytecodeGenerator::emitLoad):

File:

• trunk/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp (modified) (2 diffs)

trunk/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp

@@ -868 +868 @@
     if (number == HashTraits<double>::emptyValue() || HashTraits<double>::isDeletedValue(number))
         return emitLoad(dst, jsNumber(globalData(), number));
-    JSValuePtr valueInMap = m_numberMap.add(number, noValue()).first->second;
+    JSValuePtr& valueInMap = m_numberMap.add(number, noValue()).first->second;
     if (!valueInMap)
         valueInMap = jsNumber(globalData(), number);
@@ -876 +876 @@
 RegisterID* BytecodeGenerator::emitLoad(RegisterID* dst, const Identifier& identifier)
 {
-    JSValuePtr valueInMap = m_stringMap.add(identifier.ustring().rep(), 0).first->second;
-    if (!valueInMap)
-        valueInMap = jsOwnedString(globalData(), identifier.ustring());
-    return emitLoad(dst, valueInMap);
+    JSString*& stringInMap = m_stringMap.add(identifier.ustring().rep(), 0).first->second;
+    if (!stringInMap)
+        stringInMap = jsOwnedString(globalData(), identifier.ustring());
+    return emitLoad(dst, JSValuePtr(stringInMap));
 }