dart2js cps: Replace getter/setter calls with direct field access.

dart2js cps: Replace getter/setter calls with direct field access.

.length on JS arrays are not introduced yet because that is not
seen as field accesses by our class hierarchy.

I've changed the contract on Primitives so they can have side effects,
depend on state, diverge, throw, anything goes. GetField on possibly
null receivers would not be allowed otherwise.

AFAIK there are no optimizations that actually used the contract on
primitives, it just seemed like a good idea at one point in the past,
so that change only affects a single doc comment.

I'll migrate some of the classes that can now be primitives in another
CL.

BuiltinOperators are still required to be pure, although that too may
possibly change soon.

BUG=
R=kmillikin@google.com

Committed: https://github.com/dart-lang/sdk/commit/2f3b889c7b515ccbd720507f85a1b45ce9a5a998

[asgerf, 2015-06-18 17:17:05]

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

[Kevin Millikin (Google), 2015-06-19 11:40:36]

There is one place where we rely on primitives having a notion of purity: in the
shrinking reductions pass we eliminate unused primitives.

If you prevent that when it's not safe, the rest LGTM.

[asgerf, 2015-06-19 11:47:24]

Thanks for catching that. I'm surprised the test suite did not catch that. I
added a new test.

[Kevin Millikin (Google), 2015-06-19 12:00:53]

Nice, thanks.

[sra1, 2015-06-19 18:21:00]

DBC

https://codereview.chromium.org/1188253006/diff/40001/pkg/compiler/lib/src/cp...
File pkg/compiler/lib/src/cps_ir/type_propagation.dart (right):

https://codereview.chromium.org/1188253006/diff/40001/pkg/compiler/lib/src/cp...
pkg/compiler/lib/src/cps_ir/type_propagation.dart:691: SetField set = new
SetField(getDartReceiver(node),
This is not valid in checked mode unless we can prove setter's type assertion
never fires.

[asgerf, 2015-06-22 09:31:58]

https://codereview.chromium.org/1188253006/diff/40001/pkg/compiler/lib/src/cp...
File pkg/compiler/lib/src/cps_ir/type_propagation.dart (right):

https://codereview.chromium.org/1188253006/diff/40001/pkg/compiler/lib/src/cp...
pkg/compiler/lib/src/cps_ir/type_propagation.dart:691: SetField set = new
SetField(getDartReceiver(node),
On 2015/06/19 18:21:00, sra1 wrote:
> This is not valid in checked mode unless we can prove setter's type assertion
> never fires.

Nicely spotted, although we are not at all trying to support checked mode right
now.

[asgerf, 2015-06-22 14:08:56]

Committed patchset #3 (id:40001) manually as
2f3b889c7b515ccbd720507f85a1b45ce9a5a998 (presubmit successful).