Comment #2 on issue 1388 by [email protected]: Chrome v13 JS
Performance, Array Performance
http://code.google.com/p/v8/issues/detail?id=1388
Thanks for the report. I can reproduce the problem also on Linux Chrome 13
vs 12 and think that I found the candidate for the slowdown.
The problematic statement is in the function $backgroundBlitzer:
p = -this$static.loopyX;
solid = -this$static.loopyX;
initially those two variables get initializes with -0 since loopyX is 0.
Our optimizer interprets -0 (negative zero) differently in Chrome 13 and
therefore wrongly produces slower code. I'm working on a general fix.
That aside, the occurrence of -0 could be easily avoided by doing
bitwise-or with 0 e.g.
p = -this$static.loopyX | 0;
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