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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/210735">210735</a></dd>
<dt>Author</dt> <dd>utatane.tea@gmail.com</dd>
<dt>Date</dt> <dd>2017-01-13 10:30:09 -0800 (Fri, 13 Jan 2017)</dd>
</dl>
<h3>Log Message</h3>
<pre>Reserve capacity for StringBuilder in unescape
https://bugs.webkit.org/show_bug.cgi?id=167008
Reviewed by Sam Weinig.
`unescape` function is frequently called in Kraken sha256-iterative.
This patch just reserves the capacity for the StringBuilder.
Currently, we select the length of the string for the reserved capacity.
It improves the performance 2.73%.
Benchmark report for Kraken on sakura-trick.
VMs tested:
"baseline" at /home/yusukesuzuki/dev/WebKit/WebKitBuild/untot/Release/bin/jsc
"patched" at /home/yusukesuzuki/dev/WebKit/WebKitBuild/un/Release/bin/jsc
Collected 100 samples per benchmark/VM, with 100 VM invocations per benchmark. Emitted a call to gc() between
sample measurements. Used 1 benchmark iteration per VM invocation for warm-up. Used the jsc-specific preciseTime()
function to get microsecond-level timing. Reporting benchmark execution times with 95% confidence intervals in
milliseconds.
baseline patched
stanford-crypto-sha256-iterative 51.609+-0.672 50.237+-0.860 might be 1.0273x faster
<arithmetic> 51.609+-0.672 50.237+-0.860 might be 1.0273x faster
* runtime/JSGlobalObjectFunctions.cpp:
(JSC::globalFuncUnescape):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreruntimeJSGlobalObjectFunctionscpp">trunk/Source/JavaScriptCore/runtime/JSGlobalObjectFunctions.cpp</a></li>
</ul>
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<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (210734 => 210735)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2017-01-13 18:09:34 UTC (rev 210734)
+++ trunk/Source/JavaScriptCore/ChangeLog 2017-01-13 18:30:09 UTC (rev 210735)
</span><span class="lines">@@ -1,3 +1,36 @@
</span><ins>+2017-01-13 Yusuke Suzuki <utatane.tea@gmail.com>
+
+ Reserve capacity for StringBuilder in unescape
+ https://bugs.webkit.org/show_bug.cgi?id=167008
+
+ Reviewed by Sam Weinig.
+
+ `unescape` function is frequently called in Kraken sha256-iterative.
+ This patch just reserves the capacity for the StringBuilder.
+
+ Currently, we select the length of the string for the reserved capacity.
+ It improves the performance 2.73%.
+
+ Benchmark report for Kraken on sakura-trick.
+
+ VMs tested:
+ "baseline" at /home/yusukesuzuki/dev/WebKit/WebKitBuild/untot/Release/bin/jsc
+ "patched" at /home/yusukesuzuki/dev/WebKit/WebKitBuild/un/Release/bin/jsc
+
+ Collected 100 samples per benchmark/VM, with 100 VM invocations per benchmark. Emitted a call to gc() between
+ sample measurements. Used 1 benchmark iteration per VM invocation for warm-up. Used the jsc-specific preciseTime()
+ function to get microsecond-level timing. Reporting benchmark execution times with 95% confidence intervals in
+ milliseconds.
+
+ baseline patched
+
+ stanford-crypto-sha256-iterative 51.609+-0.672 50.237+-0.860 might be 1.0273x faster
+
+ <arithmetic> 51.609+-0.672 50.237+-0.860 might be 1.0273x faster
+
+ * runtime/JSGlobalObjectFunctions.cpp:
+ (JSC::globalFuncUnescape):
+
</ins><span class="cx"> 2017-01-12 Saam Barati <sbarati@apple.com>
</span><span class="cx">
</span><span class="cx"> Add a slice intrinsic to the DFG/FTL
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreruntimeJSGlobalObjectFunctionscpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/runtime/JSGlobalObjectFunctions.cpp (210734 => 210735)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/runtime/JSGlobalObjectFunctions.cpp 2017-01-13 18:09:34 UTC (rev 210734)
+++ trunk/Source/JavaScriptCore/runtime/JSGlobalObjectFunctions.cpp 2017-01-13 18:30:09 UTC (rev 210735)
</span><span class="lines">@@ -814,22 +814,24 @@
</span><span class="cx"> EncodedJSValue JSC_HOST_CALL globalFuncUnescape(ExecState* exec)
</span><span class="cx"> {
</span><span class="cx"> return JSValue::encode(toStringView(exec, exec->argument(0), [&] (StringView view) {
</span><ins>+ unsigned k = 0;
+ unsigned length = view.length();
+
</ins><span class="cx"> StringBuilder builder;
</span><del>- int k = 0;
- int len = view.length();
</del><ins>+ builder.reserveCapacity(length);
</ins><span class="cx">
</span><span class="cx"> if (view.is8Bit()) {
</span><span class="cx"> const LChar* characters = view.characters8();
</span><span class="cx"> LChar convertedLChar;
</span><del>- while (k < len) {
</del><ins>+ while (k < length) {
</ins><span class="cx"> const LChar* c = characters + k;
</span><del>- if (c[0] == '%' && k <= len - 6 && c[1] == 'u') {
</del><ins>+ if (c[0] == '%' && k <= length - 6 && c[1] == 'u') {
</ins><span class="cx"> if (isASCIIHexDigit(c[2]) && isASCIIHexDigit(c[3]) && isASCIIHexDigit(c[4]) && isASCIIHexDigit(c[5])) {
</span><span class="cx"> builder.append(Lexer<UChar>::convertUnicode(c[2], c[3], c[4], c[5]));
</span><span class="cx"> k += 6;
</span><span class="cx"> continue;
</span><span class="cx"> }
</span><del>- } else if (c[0] == '%' && k <= len - 3 && isASCIIHexDigit(c[1]) && isASCIIHexDigit(c[2])) {
</del><ins>+ } else if (c[0] == '%' && k <= length - 3 && isASCIIHexDigit(c[1]) && isASCIIHexDigit(c[2])) {
</ins><span class="cx"> convertedLChar = LChar(Lexer<LChar>::convertHex(c[1], c[2]));
</span><span class="cx"> c = &convertedLChar;
</span><span class="cx"> k += 2;
</span><span class="lines">@@ -840,16 +842,16 @@
</span><span class="cx"> } else {
</span><span class="cx"> const UChar* characters = view.characters16();
</span><span class="cx">
</span><del>- while (k < len) {
</del><ins>+ while (k < length) {
</ins><span class="cx"> const UChar* c = characters + k;
</span><span class="cx"> UChar convertedUChar;
</span><del>- if (c[0] == '%' && k <= len - 6 && c[1] == 'u') {
</del><ins>+ if (c[0] == '%' && k <= length - 6 && c[1] == 'u') {
</ins><span class="cx"> if (isASCIIHexDigit(c[2]) && isASCIIHexDigit(c[3]) && isASCIIHexDigit(c[4]) && isASCIIHexDigit(c[5])) {
</span><span class="cx"> convertedUChar = Lexer<UChar>::convertUnicode(c[2], c[3], c[4], c[5]);
</span><span class="cx"> c = &convertedUChar;
</span><span class="cx"> k += 5;
</span><span class="cx"> }
</span><del>- } else if (c[0] == '%' && k <= len - 3 && isASCIIHexDigit(c[1]) && isASCIIHexDigit(c[2])) {
</del><ins>+ } else if (c[0] == '%' && k <= length - 3 && isASCIIHexDigit(c[1]) && isASCIIHexDigit(c[2])) {
</ins><span class="cx"> convertedUChar = UChar(Lexer<UChar>::convertHex(c[1], c[2]));
</span><span class="cx"> c = &convertedUChar;
</span><span class="cx"> k += 2;
</span></span></pre>
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