Changeset 112540 in webkit

Timestamp:

Mar 29, 2012 9:25:24 AM (12 years ago)

Author:

yurys@chromium.org

Message:

Web Inspector: check more likely condition first in HeapSnapshot._buildAggregates
​https://bugs.webkit.org/show_bug.cgi?id=82621

Reviewed by Pavel Feldman.

• inspector/front-end/HeapSnapshot.js: selfSize === 0 is quite rare, moving this condition

to the first place saves 1 of 6 secs on the heap profiler perf test.
(WebInspector.HeapSnapshot.prototype._buildAggregates):
(WebInspector.HeapSnapshot.prototype._buildDominatedNodes): root node is always the first
one and is the only one that doesn't have dominator, so we may start iterating nodes from
the second node and avoid additional check in the loop.

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• inspector/front-end/HeapSnapshot.js (modified) (3 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2012-03-29  Yury Semikhatsky  <yurys@chromium.org>
+
+        Web Inspector: check more likely condition first in HeapSnapshot._buildAggregates
+        https://bugs.webkit.org/show_bug.cgi?id=82621
+
+        Reviewed by Pavel Feldman.
+
+        * inspector/front-end/HeapSnapshot.js: selfSize === 0 is quite rare, moving this condition
+        to the first place saves 1 of 6 secs on the heap profiler perf test.
+        (WebInspector.HeapSnapshot.prototype._buildAggregates):
+        (WebInspector.HeapSnapshot.prototype._buildDominatedNodes): root node is always the first
+        one and is the only one that doesn't have dominator, so we may start iterating nodes from
+        the second node and avoid additional check in the loop.
+
 2012-03-29  Pavel Feldman  <pfeldman@chromium.org>
 

trunk/Source/WebCore/inspector/front-end/HeapSnapshot.js

@@ -1092 +1092 @@
             if (filter && !filter(node))
                 return true;
-            if (!node.isNative && node.selfSize === 0)
+            if (!node.selfSize && !node.isNative)
                 return true;
             return false;
@@ -1177 +1177 @@
         var dominatedNodes = this._dominatedNodes = new Uint32Array(this.nodeCount - 1);
 
-        // Count the number of dominated nodes for each node
-        for (var nodeIndex = 0; nodeIndex < this._onlyNodes.length; nodeIndex += this._nodeFieldCount) {
+        // Count the number of dominated nodes for each node. Skip the root (node at
+        // index 0) as it is the only node that dominates itself.
+        for (var nodeIndex = this._nodeFieldCount; nodeIndex < this._onlyNodes.length; nodeIndex += this._nodeFieldCount) {
             var dominatorIndex = this._onlyNodes[nodeIndex + this._dominatorOffset];
             if (dominatorIndex % this._nodeFieldCount)
                 throw new Error("Wrong dominatorIndex " + dominatorIndex + " nodeIndex = " + nodeIndex + " nodeCount = " + this.nodeCount);
-            // Skip root node. We may simplify this by starting iteration from second node.
-            if (nodeIndex === dominatorIndex) continue;
             ++indexArray[dominatorIndex / this._nodeFieldCount];
         }
@@ -1189 +1188 @@
         // that will be filled.
         var firstDominatedNodeIndex = 0;
-        for (i = 0; i <= this.nodeCount; ++i) {
+        for (i = 0; i < this.nodeCount; ++i) {
             var dominatedCount = dominatedNodes[firstDominatedNodeIndex] = indexArray[i];
             indexArray[i] = firstDominatedNodeIndex;
             firstDominatedNodeIndex += dominatedCount;
         }
-        // Fill up the dominatedNodes array with indexes of dominated nodes.
-        for (var nodeIndex = 0; nodeIndex < this._onlyNodes.length; nodeIndex += this._nodeFieldCount) {
+        indexArray[this.nodeCount] = dominatedNodes.length;
+        // Fill up the dominatedNodes array with indexes of dominated nodes. Skip the root (node at
+        // index 0) as it is the only node that dominates itself.
+        for (var nodeIndex = this._nodeFieldCount; nodeIndex < this._onlyNodes.length; nodeIndex += this._nodeFieldCount) {
             var dominatorIndex = this._onlyNodes[nodeIndex + this._dominatorOffset];
             if (dominatorIndex % this._nodeFieldCount)
                 throw new Error("Wrong dominatorIndex " + dominatorIndex);
-            if (nodeIndex === dominatorIndex) continue;
             var dominatorPos = dominatorIndex / this._nodeFieldCount;
             var dominatedRefIndex = indexArray[dominatorPos];