dart2js cps: Hoist unsafe expressions from loop entry.

dart2js cps: Hoist unsafe expressions from loop entry.

Primitives that potentially throw cannot normally be hoisted, but we can
sometimes hoist them anyway if they are at the loop entry.

We now hoist GetLength, GetField, GetIndex, NullCheck, and BoundsCheck.

BUG=
R=sigmund@google.com

Committed: https://github.com/dart-lang/sdk/commit/c85916dedc773135bdb4bb4a79112b2ab1a18b52

[asgerf, 2016-01-11 21:57:02]

asgerf@google.com changed reviewers:
+ kmillikin@google.com, sigmund@google.com, sra@google.com

[Siggi Cherem (dart-lang), 2016-01-11 21:59:29]

lgtm

[asgerf, 2016-01-12 23:18:33]

Description was changed from

==========
dart2js cps: Hoist unsafe expressions from loop entry.

Primitives that potentially throw cannot normally be hoisted, but we can
sometimes hoist them anyway if they are at the loop entry.

We now hoist GetLength, GetField, GetIndex, NullCheck, and BoundsCheck.

BUG=
==========

to

==========
dart2js cps: Hoist unsafe expressions from loop entry.

Primitives that potentially throw cannot normally be hoisted, but we can
sometimes hoist them anyway if they are at the loop entry.

We now hoist GetLength, GetField, GetIndex, NullCheck, and BoundsCheck.

BUG=
R=sigmund@google.com

Committed:
https://github.com/dart-lang/sdk/commit/c85916dedc773135bdb4bb4a79112b2ab1a18b52
==========

[asgerf, 2016-01-12 23:18:34]

Committed patchset #2 (id:20001) manually as
c85916dedc773135bdb4bb4a79112b2ab1a18b52 (presubmit successful).