Changeset 101218 in webkit

Timestamp:

Nov 27, 2011, 7:50:23 PM (15 years ago)

Author:

andreas.kling@nokia.com

Message:

CSSStyleRule: Pack m_sourceLine with CSSRule bits.
<​http://webkit.org/b/73168>

Reviewed by Antti Koivisto.

Make CSSStyleRule::m_sourceLine a 27-bit integer and pack it with the rest
of the members in CSSRule. This shrinks CSSStyleRule by one CPU word
and reduces memory consumption by 81 kB on the GMail inbox (on 64-bit.)

• css/CSSRule.h:

(WebCore::CSSRule::CSSRule):

• css/CSSStyleRule.cpp:

(WebCore::CSSStyleRule::CSSStyleRule):

• css/CSSStyleRule.h:

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• css/CSSRule.h (modified) (2 diffs)
• css/CSSStyleRule.cpp (modified) (1 diff)
• css/CSSStyleRule.h (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2011-11-27  Andreas Kling  <kling@webkit.org>
+
+        CSSStyleRule: Pack m_sourceLine with CSSRule bits.
+        <http://webkit.org/b/73168>
+
+        Reviewed by Antti Koivisto.
+
+        Make CSSStyleRule::m_sourceLine a 27-bit integer and pack it with the rest
+        of the members in CSSRule. This shrinks CSSStyleRule by one CPU word
+        and reduces memory consumption by 81 kB on the GMail inbox (on 64-bit.)
+
+        * css/CSSRule.h:
+        (WebCore::CSSRule::CSSRule):
+        * css/CSSStyleRule.cpp:
+        (WebCore::CSSStyleRule::CSSStyleRule):
+        * css/CSSStyleRule.h:
+
 2011-11-27  Mark Rowe  <mrowe@apple.com>
 

trunk/Source/WebCore/css/CSSRule.h

@@ -110 +110 @@
 protected:
     CSSRule(CSSStyleSheet* parent, Type type)
-        : m_parentIsRule(false)
+        : m_sourceLine(0)
+        , m_parentIsRule(false)
         , m_type(type)
         , m_parentStyleSheet(parent)
@@ -121 +122 @@
     ~CSSRule() { }
 
+    // Only used by CSSStyleRule but kept here to maximize struct packing.
+    signed m_sourceLine : 27;
+
 private:
-    void destroy();
-
     bool m_parentIsRule : 1;
-    unsigned m_type : 31; // Plenty of space for additional flags here.
+    unsigned m_type : 4;
     union {
         CSSRule* m_parentRule;
         CSSStyleSheet* m_parentStyleSheet;
     };
+
+    void destroy();
 };
 

trunk/Source/WebCore/css/CSSStyleRule.cpp

@@ -36 +36 @@
 CSSStyleRule::CSSStyleRule(CSSStyleSheet* parent, int sourceLine, CSSRule::Type type)
     : CSSRule(parent, type)
-    , m_sourceLine(sourceLine)
 {
+    m_sourceLine = sourceLine;
+
+    // m_sourceLine is a bitfield, so let's catch any overflow early in debug mode.
+    ASSERT(m_sourceLine == sourceLine);
 }
 

trunk/Source/WebCore/css/CSSStyleRule.h

@@ -64 +64 @@
     RefPtr<CSSMutableStyleDeclaration> m_style;
     CSSSelectorList m_selectorList;
-    int m_sourceLine;
 };