Add range to kBIT_AND with positive constants. Use that range to eliminate compares in left shifts.

Add range to kBIT_AND with positive constants. Use that range to eliminate compares in left shifts.
Committed: https://code.google.com/p/dart/source/detail?r=14304

[Vyacheslav Egorov (Google), 2012-10-19 20:05:28]

https://codereview.chromium.org/11175013/diff/1/runtime/vm/intermediate_langu...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/11175013/diff/1/runtime/vm/intermediate_langu...
runtime/vm/intermediate_language.cc:2201: if (range_ == NULL) {
I sense a problem here. Range of a phi can start like [0, 0] but be later
expanded due to the flow of information on the back edge. However we will loose
this fact and stop updating the range correctly.

Please test it on the code:

var j, k = -0xff;
for (var i = 0; i >= -10; i--) {
  print(k & i); // range of this & should not be [0, 0].
}

[srdjan, 2012-10-25 21:44:05]

Please have another look.

[Vyacheslav Egorov (Google), 2012-10-26 12:21:42]

lgtm

https://codereview.chromium.org/11175013/diff/8001/runtime/vm/intermediate_la...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/11175013/diff/8001/runtime/vm/intermediate_la...
runtime/vm/intermediate_language.cc:2243: if (!min().IsConstant() ||
(min().value() < min_int)) return false;
I suggest using LowerBound() and UpperBound() here instead of limiting function
to constant boundaries.

[srdjan, 2012-10-30 18:21:13]

Better late than never.

https://codereview.chromium.org/11175013/diff/8001/runtime/vm/intermediate_la...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/11175013/diff/8001/runtime/vm/intermediate_la...
runtime/vm/intermediate_language.cc:2243: if (!min().IsConstant() ||
(min().value() < min_int)) return false;
On 2012/10/26 12:21:42, Vyacheslav Egorov (Google) wrote:
> I suggest using LowerBound() and UpperBound() here instead of limiting
function
> to constant boundaries.

Done.