Rename Closure instance field type_arguments_ to instantiator_.

Rename Closure instance field type_arguments_ to instantiator_.
Simplify handling of closures as deferred objects.
The name "type_arguments_" is confusing, because class Closure is not generic.
Class Closure was forcefully made (kinda) generic by setting its
type_arguments_field_offset_in_words_ field to a valid value, so that the
type_arguments_ field in closure instances could be accessed similarly as in
generic instances. With generic functions, closures will potentially have more
than one instantiator and the name type_arguments_ becomes nonsensical.

R=johnmccutchan@google.com

Committed: https://github.com/dart-lang/sdk/commit/3633c5bd5ec0b6b876433b204d6c94bbfa118351

[regis, 2017-02-24 21:51:01]

regis@google.com changed reviewers:
+ johnmccutchan@google.com, rmacnak@google.com

[Cutch, 2017-02-24 22:15:37]

https://codereview.chromium.org/2719603002/diff/1/runtime/lib/function.dart
File runtime/lib/function.dart (right):

https://codereview.chromium.org/2719603002/diff/1/runtime/lib/function.dart#n...
runtime/lib/function.dart:18: // Caution: These fields are not Dart instances,
but VM objects.
Add a note that no fields can be added *before* these fields or else the field
offsets will not match.

Maybe also add an ASSERT that looks these fields up and verifies the offsets
match the offset into RawClosure?

https://codereview.chromium.org/2719603002/diff/1/runtime/vm/raw_object.h
File runtime/vm/raw_object.h (right):

https://codereview.chromium.org/2719603002/diff/1/runtime/vm/raw_object.h#new...
runtime/vm/raw_object.h:1788: // These 3 fields are also declared in the Dart
source of class _Closure.
Add a note here that no fields can be added *before* these or the offsets will
not match the Dart code

[Cutch, 2017-02-24 22:15:43]

lgtm

[regis, 2017-02-24 22:54:41]

Thanks!

https://codereview.chromium.org/2719603002/diff/1/runtime/lib/function.dart
File runtime/lib/function.dart (right):

https://codereview.chromium.org/2719603002/diff/1/runtime/lib/function.dart#n...
runtime/lib/function.dart:18: // Caution: These fields are not Dart instances,
but VM objects.
On 2017/02/24 22:15:37, Cutch wrote:
> Add a note that no fields can be added *before* these fields or else the field
> offsets will not match.
> 
> Maybe also add an ASSERT that looks these fields up and verifies the offsets
> match the offset into RawClosure?

Good points. All done.

https://codereview.chromium.org/2719603002/diff/1/runtime/vm/raw_object.h
File runtime/vm/raw_object.h (right):

https://codereview.chromium.org/2719603002/diff/1/runtime/vm/raw_object.h#new...
runtime/vm/raw_object.h:1788: // These 3 fields are also declared in the Dart
source of class _Closure.
On 2017/02/24 22:15:37, Cutch wrote:
> Add a note here that no fields can be added *before* these or the offsets will
> not match the Dart code

Done.

[Cutch, 2017-02-24 22:58:32]

https://codereview.chromium.org/2719603002/diff/20001/runtime/vm/bootstrap.cc
File runtime/vm/bootstrap.cc (right):

https://codereview.chromium.org/2719603002/diff/20001/runtime/vm/bootstrap.cc...
runtime/vm/bootstrap.cc:279: field ^= fields.At(0);
Maybe also verify field name?

[regis, 2017-02-24 23:02:35]

https://codereview.chromium.org/2719603002/diff/20001/runtime/vm/bootstrap.cc
File runtime/vm/bootstrap.cc (right):

https://codereview.chromium.org/2719603002/diff/20001/runtime/vm/bootstrap.cc...
runtime/vm/bootstrap.cc:279: field ^= fields.At(0);
On 2017/02/24 22:58:32, Cutch wrote:
> Maybe also verify field name?

The Dart names are never used. As long as we have 3 fields, we are good.

[regis, 2017-02-27 19:14:10]

Description was changed from

==========
Rename Closure instance field type_arguments_ to instantiator_.
Simplify handling of closures as deferred objects.
The name "type_arguments_" is confusing, because class Closure is not generic.
Class Closure was forcefully made (kinda) generic by setting its
type_arguments_field_offset_in_words_ field to a valid value, so that the
type_arguments_ field in closure instances could be accessed similarly as in
generic instances. With generic functions, closures will potentially have more
than one instantiator and the name type_arguments_ becomes nonsensical.
==========

to

==========
Rename Closure instance field type_arguments_ to instantiator_.
Simplify handling of closures as deferred objects.
The name "type_arguments_" is confusing, because class Closure is not generic.
Class Closure was forcefully made (kinda) generic by setting its
type_arguments_field_offset_in_words_ field to a valid value, so that the
type_arguments_ field in closure instances could be accessed similarly as in
generic instances. With generic functions, closures will potentially have more
than one instantiator and the name type_arguments_ becomes nonsensical.

R=johnmccutchan@google.com

Committed:
https://github.com/dart-lang/sdk/commit/3633c5bd5ec0b6b876433b204d6c94bbfa118351
==========

[regis, 2017-02-27 19:14:11]

Committed patchset #3 (id:40001) manually as
3633c5bd5ec0b6b876433b204d6c94bbfa118351 (presubmit successful).