Fix for issue 2132.

Fix for issue 2132.

BUG=2132
TEST=

[Massi, 2012-05-18 11:08:38]

Since you opened the issue, could you review this?

[Florian Schneider, 2012-05-18 16:12:06]

another idea: How about splitting Canonicalize phase into two (e.g.
CanonicalizeEarly and CanonicalizeLate)? There are potentially more things that
depend on later optimization passes and it would be more a general solution than
patching up the range analysis.

https://chromiumcodereview.appspot.com/10411016/diff/1/src/hydrogen.cc
File src/hydrogen.cc (right):

https://chromiumcodereview.appspot.com/10411016/diff/1/src/hydrogen.cc#newcod...
src/hydrogen.cc:1112: || !value->HasRange());
Can't you just check HasRange() here and leave it alone if there is an exisiting
range calculated?

[Vyacheslav Egorov (Chromium), 2012-05-18 17:39:05]

I think Florian's suggestion is the way to go.

https://chromiumcodereview.appspot.com/10411016/diff/1/src/hydrogen-instructi...
File src/hydrogen-instructions.cc (right):

https://chromiumcodereview.appspot.com/10411016/diff/1/src/hydrogen-instructi...
src/hydrogen-instructions.cc:880:
right()->range()->set_can_be_minus_zero(false);
I don't think this is correct. Consider code like:

function mul(a, b) {
  var x = a * b;
  x | 0;
  return x;
}

your code will remove minus zero from the range of x but this is incorrect.