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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/185067">185067</a></dd>
<dt>Author</dt> <dd>ggaren@apple.com</dd>
<dt>Date</dt> <dd>2015-06-01 11:40:30 -0700 (Mon, 01 Jun 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>REGRESSION: These sorting idioms used by Peacekeeper and Browsermark are ~20X slower
https://bugs.webkit.org/show_bug.cgi?id=145412
Reviewed by Darin Adler.
Moar speedup.
Added a bucket sort for string sorting.
* builtins/Array.prototype.js:
(sort.compactSparse):
(sort.compactSlow):
(sort.compact): Split out a compaction fast path for dense arrays. Without
it, compaction can increase sort time by 2X for simple sorts.
(sort.bucketSort):
(sort.stringSort): Use a bucket sorting algorithm if we know we're sorting
strings. This makes average case string sorting O(N) with O(N) additional
memory use.
The worst case bucket sort can require O(M * N) additional
space. We avoid this by falling back to merge sort when things are
simple or overly duplicative. These are the two cases that accumulate
excessive -- and potentially pathological -- bucketing overhead.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCorebuiltinsArrayprototypejs">trunk/Source/JavaScriptCore/builtins/Array.prototype.js</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (185066 => 185067)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-06-01 18:17:40 UTC (rev 185066)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-06-01 18:40:30 UTC (rev 185067)
</span><span class="lines">@@ -1,3 +1,30 @@
</span><ins>+2015-05-29 Geoffrey Garen <ggaren@apple.com>
+
+ REGRESSION: These sorting idioms used by Peacekeeper and Browsermark are ~20X slower
+ https://bugs.webkit.org/show_bug.cgi?id=145412
+
+ Reviewed by Darin Adler.
+
+ Moar speedup.
+
+ Added a bucket sort for string sorting.
+
+ * builtins/Array.prototype.js:
+ (sort.compactSparse):
+ (sort.compactSlow):
+ (sort.compact): Split out a compaction fast path for dense arrays. Without
+ it, compaction can increase sort time by 2X for simple sorts.
+
+ (sort.bucketSort):
+ (sort.stringSort): Use a bucket sorting algorithm if we know we're sorting
+ strings. This makes average case string sorting O(N) with O(N) additional
+ memory use.
+
+ The worst case bucket sort can require O(M * N) additional
+ space. We avoid this by falling back to merge sort when things are
+ simple or overly duplicative. These are the two cases that accumulate
+ excessive -- and potentially pathological -- bucketing overhead.
+
</ins><span class="cx"> 2015-06-01 Mark Lam <mark.lam@apple.com>
</span><span class="cx">
</span><span class="cx"> HandlerInfo::initialize() should not assume that CodeLocationLabel is available.
</span></span></pre></div>
<a id="trunkSourceJavaScriptCorebuiltinsArrayprototypejs"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/builtins/Array.prototype.js (185066 => 185067)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/builtins/Array.prototype.js 2015-06-01 18:17:40 UTC (rev 185066)
+++ trunk/Source/JavaScriptCore/builtins/Array.prototype.js 2015-06-01 18:40:30 UTC (rev 185067)
</span><span class="lines">@@ -420,8 +420,7 @@
</span><span class="cx"> return valueCount;
</span><span class="cx"> }
</span><span class="cx">
</span><del>- // Move undefineds and holes to the end of an array. Result is [values..., undefineds..., holes...].
- function compact(array, length)
</del><ins>+ function compactSlow(array, length)
</ins><span class="cx"> {
</span><span class="cx"> var holeCount = 0;
</span><span class="cx">
</span><span class="lines">@@ -436,6 +435,7 @@
</span><span class="cx"> var value = array[src];
</span><span class="cx"> if (value === undefined)
</span><span class="cx"> continue;
</span><ins>+
</ins><span class="cx"> array[dst++] = value;
</span><span class="cx"> }
</span><span class="cx">
</span><span class="lines">@@ -451,6 +451,17 @@
</span><span class="cx"> return valueCount;
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+ // Move undefineds and holes to the end of an array. Result is [values..., undefineds..., holes...].
+ function compact(array, length)
+ {
+ for (var i = 0; i < array.length; ++i) {
+ if (array[i] === undefined)
+ return compactSlow(array, length);
+ }
+
+ return length;
+ }
+
</ins><span class="cx"> function merge(dst, src, srcIndex, srcEnd, width, comparator)
</span><span class="cx"> {
</span><span class="cx"> var left = srcIndex;
</span><span class="lines">@@ -492,6 +503,39 @@
</span><span class="cx"> }
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+ function bucketSort(array, dst, bucket, depth)
+ {
+ if (bucket.length < 32 || depth > 32) {
+ mergeSort(bucket, bucket.length, stringComparator);
+ for (var i = 0; i < bucket.length; ++i)
+ array[dst++] = bucket[i].value;
+ return dst;
+ }
+
+ var buckets = [ ];
+ for (var i = 0; i < bucket.length; ++i) {
+ var entry = bucket[i];
+ var string = entry.string;
+ if (string.length == depth) {
+ array[dst++] = entry.value;
+ continue;
+ }
+
+ var c = string.@charCodeAt(depth);
+ if (!buckets[c])
+ buckets[c] = [ ];
+ buckets[c][buckets[c].length] = entry;
+ }
+
+ for (var i = 0; i < buckets.length; ++i) {
+ if (!buckets[i])
+ continue;
+ dst = bucketSort(array, dst, buckets[i], depth + 1);
+ }
+
+ return dst;
+ }
+
</ins><span class="cx"> function comparatorSort(array, comparator)
</span><span class="cx"> {
</span><span class="cx"> var length = array.length >>> 0;
</span><span class="lines">@@ -520,10 +564,7 @@
</span><span class="cx"> for (var i = 0; i < valueCount; ++i)
</span><span class="cx"> strings[i] = { string: @toString(array[i]), value: array[i] };
</span><span class="cx">
</span><del>- mergeSort(strings, valueCount, stringComparator);
-
- for (var i = 0; i < valueCount; ++i)
- array[i] = strings[i].value;
</del><ins>+ bucketSort(array, 0, strings, 0);
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> if (this === null)
</span></span></pre>
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