dart2js cps: Change rewriting of equality operators.

dart2js cps: Change rewriting of equality operators.

Dart == calls now are rewritten to an Identical node (if applicable),
which can then be specialized further into JS == and === nodes.

Previously, == calls would specialize directly to JS == and === nodes,
but some of these optimizations were then missed for the cases where
Identical nodes are introduced directly (e.g. for switch cases).

The rules have also changed a bit to be more effective, and there
are some small improvements to the utility functions.

BUG=
R=karlklose@google.com

Committed: https://github.com/dart-lang/sdk/commit/684b83ab0543bbdd404decf91145b8b8cdc70e0d

[asgerf, 2015-08-11 13:19:29]

asgerf@google.com changed reviewers:
+ karlklose@google.com

[karlklose, 2015-08-11 13:38:53]

LGTM.

https://codereview.chromium.org/1276843008/diff/20001/pkg/compiler/lib/src/cp...
File pkg/compiler/lib/src/cps_ir/type_propagation.dart (right):

https://codereview.chromium.org/1276843008/diff/20001/pkg/compiler/lib/src/cp...
pkg/compiler/lib/src/cps_ir/type_propagation.dart:1608: } else if
(lattice.isDefinitelyNum(left, allowNull: true) &&
Maybe use isDefinitelyNumBoolString and check if the types are the same.

[asgerf, 2015-08-11 13:41:43]

https://codereview.chromium.org/1276843008/diff/20001/pkg/compiler/lib/src/cp...
File pkg/compiler/lib/src/cps_ir/type_propagation.dart (right):

https://codereview.chromium.org/1276843008/diff/20001/pkg/compiler/lib/src/cp...
pkg/compiler/lib/src/cps_ir/type_propagation.dart:1608: } else if
(lattice.isDefinitelyNum(left, allowNull: true) &&
On 2015/08/11 13:38:53, karlklose wrote:
> Maybe use isDefinitelyNumBoolString and check if the types are the same.

Wouldn't work if, for example, both types are number|string.

[asgerf, 2015-08-11 13:47:54]

Committed patchset #3 (id:40001) manually as
684b83ab0543bbdd404decf91145b8b8cdc70e0d (presubmit successful).