AuroraMiddleware/v8
1
0
Fork 0
Code Issues 2 Pull Requests Releases Wiki Activity

Optimize String.prototype.includes

Browse Source 
This patch removes the MathMax call from String.prototype.includes
in order to improve performance. With some quick and dirty benchmarking,
(test case courtesy of the node folks) a sizable performance gain is visible:

d8> function testIndexOf() { var stringArray = [ 'hello', 'world', '123', 'abc' ]; return stringArray.some(function(val, idx, arr) { return val.indexOf('world') !== -1 })}
d8> function testIncludes() { var stringArray = [ 'hello', 'world', '123', 'abc' ]; return stringArray.some(function(val, idx, arr) { return val.includes('world') })}
d8> function testTime(fn) { var before = Date.now(); fn(); return Date.now() - before; }
d8> testTime(function() { for (var i = 0; i < 10000000; i++) { testIncludes() } })
2244
d8> testTime(function() { for (var i = 0; i < 10000000; i++) { testIndexOf() } })
2212

Compare that to before the test, when the performance difference was much larger:

d8> testTime(function() { for (var i = 0; i < 10000000; i++) { testIndexOf() } })
2223
d8> testTime(function() { for (var i = 0; i < 10000000; i++) { testIncludes() } })
2650

In my runs, performance of both functions drifts up and down, but running them in quick
succession back and forth shows a roughly consistent delta of about this magnitude.

String.prototype.includes is still slightly (maybe 5%) slower than String.prototype.indexOf,
but the effect is significantly reduced.

R=adamk
BUG=v8:3807
LOG=Y

Review URL: https://codereview.chromium.org/1231673008

Cr-Commit-Position: refs/heads/master@{#29665}
This commit is contained in:
littledan 2015-07-14 18:01:42 -07:00 committed by Commit bot
parent 3ec841f2b5
commit d20a509042
1 changed files with 10 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
src/string.js
View File

@ -1031,27 +1031,29 @@ function StringEndsWith(searchString /* position */) { // length == 1
function StringIncludes(searchString /* position */) { // length == 1
CHECK_OBJECT_COERCIBLE(this, "String.prototype.includes");
var s = TO_STRING_INLINE(this);
var string = TO_STRING_INLINE(this);
if (IS_REGEXP(searchString)) {
throw MakeTypeError(kFirstArgumentNotRegExp, "String.prototype.includes");
}
var ss = TO_STRING_INLINE(searchString);
searchString = TO_STRING_INLINE(searchString);
var pos = 0;
if (%_ArgumentsLength() > 1) {
pos = %_Arguments(1); // position
pos = $toInteger(pos);
pos = TO_INTEGER(pos);
}
var s_len = s.length;
var start = MathMin(MathMax(pos, 0), s_len);
var ss_len = ss.length;
if (ss_len + start > s_len) {
var stringLength = string.length;
if (pos < 0) pos = 0;
if (pos > stringLength) pos = stringLength;
var searchStringLength = searchString.length;
if (searchStringLength + pos > stringLength) {
return false;
}
return %StringIndexOf(s, ss, start) !== -1;
return %StringIndexOf(string, searchString, pos) !== -1;
}