Insert representation changes before doing range analysis.

Insert representation changes before doing range analysis and fix a bug in Range::Copy.

This improves our static type information by calculating the result type
of conversions (HChange) during range analysis. It allows e.g. to eliminate
the write barrier in the following example where it was not possible before:

function f(x) {
  var y = x + 1;
  if (y > 0 && y < 100) {
    a[0] = y;
  }
}


* Fix bug in Range::Copy. The minus-zero flags has to be preserved by default.
Committed: http://code.google.com/p/v8/source/detail?r=8994

[Vyacheslav Egorov (Chromium), 2011-08-22 12:53:30]

LGTM with comments addressed.

http://codereview.chromium.org/7634022/diff/4001/src/hydrogen-instructions.cc
File src/hydrogen-instructions.cc (right):

http://codereview.chromium.org/7634022/diff/4001/src/hydrogen-instructions.cc...
src/hydrogen-instructions.cc:886: return input_range != NULL ?
input_range->Copy() : HValue::InferRange();
It seems that if we are converting to integer type we can clear minus zero from
resulting range.

http://codereview.chromium.org/7634022/diff/4001/src/hydrogen.cc
File src/hydrogen.cc (right):

http://codereview.chromium.org/7634022/diff/4001/src/hydrogen.cc#newcode2328
src/hydrogen.cc:2328: graph()->InsertRepresentationChanges();
InsertRepresentationChange depends on kDeoptimizeOnUndefined flag which is
propagated in MarkDeoptimizeOnUndefined phase.

[fschneider, 2011-08-23 07:36:10]

http://codereview.chromium.org/7634022/diff/4001/src/hydrogen-instructions.cc
File src/hydrogen-instructions.cc (right):

http://codereview.chromium.org/7634022/diff/4001/src/hydrogen-instructions.cc...
src/hydrogen-instructions.cc:886: return input_range != NULL ?
input_range->Copy() : HValue::InferRange();
On 2011/08/22 12:53:31, Vyacheslav Egorov wrote:
> It seems that if we are converting to integer type we can clear minus zero
from
> resulting range.

Done.

http://codereview.chromium.org/7634022/diff/4001/src/hydrogen.cc
File src/hydrogen.cc (right):

http://codereview.chromium.org/7634022/diff/4001/src/hydrogen.cc#newcode2328
src/hydrogen.cc:2328: graph()->InsertRepresentationChanges();
On 2011/08/22 12:53:31, Vyacheslav Egorov wrote:
> InsertRepresentationChange depends on kDeoptimizeOnUndefined flag which is
> propagated in MarkDeoptimizeOnUndefined phase.

Done.