r102234 caused RuleData to use 33 bits in its bitmask

https://bugs.webkit.org/show_bug.cgi?id=74314

Reviewed by Antti Koivisto.

Lower m_position to something more reasonable. A million
should be plenty. Current large sites (e.g. gmail) seem to use
tens of thousands.

Added a COMPILE_ASSERT to ensure this doesn't regress.

No new tests.

* css/CSSStyleSelector.cpp:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@102613 268f45cc-cd09-0410-ab3c-d52691b4dbfc

diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
index e07b41a..c6f07ea 100644 (file)
--- a/Source/WebCore/ChangeLog
+++ b/Source/WebCore/ChangeLog
@@ -1,3 +1,20 @@
+2011-12-12  Ojan Vafai  <ojan@chromium.org>
+
+        r102234 caused RuleData to use 33 bits in its bitmask
+        https://bugs.webkit.org/show_bug.cgi?id=74314
+
+        Reviewed by Antti Koivisto.
+
+        Lower m_position to something more reasonable. A million
+        should be plenty. Current large sites (e.g. gmail) seem to use
+        tens of thousands.
+
+        Added a COMPILE_ASSERT to ensure this doesn't regress.
+
+        No new tests.
+
+        * css/CSSStyleSelector.cpp:
+
 2011-12-12  James Robinson  <jamesr@chromium.org>
 
         Rename webkitCancelRequestAnimationFrame to webkitCancelAnimationFrame to match spec change

diff --git a/Source/WebCore/css/CSSStyleSelector.cpp b/Source/WebCore/css/CSSStyleSelector.cpp
index a773f32..02a83ed 100644 (file)
--- a/Source/WebCore/css/CSSStyleSelector.cpp
+++ b/Source/WebCore/css/CSSStyleSelector.cpp
@@ -190,7 +190,9 @@ private:
     CSSStyleRule* m_rule;
     CSSSelector* m_selector;
     unsigned m_specificity;
-    unsigned m_position : 26;
+    // This number was picked fairly arbitrarily. We can probably lower it if we need to.
+    // Some simple testing showed <100,000 RuleData's on large sites.
+    unsigned m_position : 25;
     bool m_hasFastCheckableSelector : 1;
     bool m_hasMultipartSelector : 1;
     bool m_hasRightmostSelectorMatchingHTMLBasedOnRuleHash : 1;
@@ -200,6 +202,16 @@ private:
     // Use plain array instead of a Vector to minimize memory overhead.
     unsigned m_descendantSelectorIdentifierHashes[maximumIdentifierCount];
 };
+    
+struct SameSizeAsRuleData {
+    void* a;
+    void* b;
+    unsigned c;
+    unsigned d;
+    unsigned e[4];
+};
+
+COMPILE_ASSERT(sizeof(RuleData) == sizeof(SameSizeAsRuleData), RuleData_should_stay_small);
 
 class RuleSet {
     WTF_MAKE_NONCOPYABLE(RuleSet);