[Webkit-unassigned] [Bug 113862] Negative zero checks cause unnecessary speculation failures on SunSpider math-spectral-norm.

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=113862





--- Comment #2 from Roman Zhuykov <zhroma at ispras.ru>  2013-04-03 06:45:11 PST ---
Created an attachment (id=196342)
 --> (https://bugs.webkit.org/attachment.cgi?id=196342&action=review)
testcase

For problem with wrong "isNotNegZero" implementation I just found the following testcase:

function main() {
  var x = 1;
  var y = -1;
  var s;
  var i;
  for (i = 0; i < 100000; i++) {
    if (i == 99999)
      x = 0;
    s = 1/(x/y+(-0));
  }
  return s;
}

print(1/(0/-1+(-0)));
print(main());

On x86-64 Linux this prints (wrong):
-Infinity
Infinity

While on ARMv7 Linux (right):
-Infinity
-Infinity

My patch fixes this.

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