Bug 13384 – [js-collector-tweaks] Shrink PropertyMap by 8 bytes

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Maciej Stachowiak]

This is working towards a cell size of 32 bytes, which enables significant performance wins.

[Maciej Stachowiak]

Created attachment 14065 [details]
04-js-gc-shrink-propertymap.patch.txt

[Darin Adler]

Comment on attachment 14065 [details]
04-js-gc-shrink-propertymap.patch.txt

We should just get rid of m_singleEntryAttributes and allow single entries only when attributes are 0. But that won't save any size.

-inline PropertyMap::PropertyMap() : _table(0)
+inline PropertyMap::PropertyMap() 
+  : m_singleEntryKey(0)
+  , m_getterSetterFlag(false)
+  , m_usingTable(false)
+
 {
-    _singleEntry.globalGetterSetterFlag = 0;
+  m_u.table = 0;
 }

Should be 4-character indented.

Why are we initializing m_u.table?

Otherwise looks good. I read the whole thing.

[Maciej Stachowiak]

I fixed the indents and removed initialization of m_u, since it isn't needed unless either m_usingTable is true or m_singleEntryKey is non-NULL.