VM: New, faster default Map construction.

VM: New, faster default Map construction.

Replace the C++ implementation of the default Map constructor with a
Dart version that uses the existing native setters to initialize members.

This avoid the expensive runtime transition when doing "new Map()".

BUG=#26046
R=asiva@google.com

Committed: https://github.com/dart-lang/sdk/commit/caceddba8f5d8fc86c859ea41fcc5b27772dcfe4

[Florian Schneider, 2016-08-26 00:29:21]

Description was changed from

==========
VM: New, faster Map construction.

Replace the C++ implementation of the default Map constructor with a
Dart version that uses the existing native setters to initialize members.

This avoid the expensive runtime transition when doing "new Map()".

BUG=#26046
==========

to

==========
VM: New, faster default Map construction.

Replace the C++ implementation of the default Map constructor with a
Dart version that uses the existing native setters to initialize members.

This avoid the expensive runtime transition when doing "new Map()".

BUG=#26046
==========

[Florian Schneider, 2016-08-26 00:30:56]

fschneider@google.com changed reviewers:
+ asiva@google.com

[sra1, 2016-08-26 00:36:35]

sra@google.com changed reviewers:
+ sra@google.com

[sra1, 2016-08-26 00:36:36]

DBC

https://codereview.chromium.org/2278273003/diff/1/runtime/lib/compact_hash.dart
File runtime/lib/compact_hash.dart (right):

https://codereview.chromium.org/2278273003/diff/1/runtime/lib/compact_hash.da...
runtime/lib/compact_hash.dart:126: _InternalLinkedHashMap() {
How about using initializers so that it is obvious that the fields can never be
observed to be null?

[Florian Schneider, 2016-08-26 00:40:33]

https://codereview.chromium.org/2278273003/diff/1/runtime/lib/compact_hash.dart
File runtime/lib/compact_hash.dart (right):

https://codereview.chromium.org/2278273003/diff/1/runtime/lib/compact_hash.da...
runtime/lib/compact_hash.dart:126: _InternalLinkedHashMap() {
On 2016/08/26 00:36:36, sra1 wrote:
> How about using initializers so that it is obvious that the fields can never
be
> observed to be null?

Initializers only work with real fields, not with setters (-> syntax error)

The return types of the native getters are already known to the compiler in any
case (i.e. non-nullable smi/List/Uint32List), so it does not matter how they are
initialized.

[siva, 2016-08-26 00:50:04]

lgtm

[Florian Schneider, 2016-08-26 00:51:49]

Description was changed from

==========
VM: New, faster default Map construction.

Replace the C++ implementation of the default Map constructor with a
Dart version that uses the existing native setters to initialize members.

This avoid the expensive runtime transition when doing "new Map()".

BUG=#26046
==========

to

==========
VM: New, faster default Map construction.

Replace the C++ implementation of the default Map constructor with a
Dart version that uses the existing native setters to initialize members.

This avoid the expensive runtime transition when doing "new Map()".

BUG=#26046
R=asiva@google.com

Committed:
https://github.com/dart-lang/sdk/commit/caceddba8f5d8fc86c859ea41fcc5b27772dcfe4
==========

[Florian Schneider, 2016-08-26 00:51:53]

Committed patchset #1 (id:1) manually as
caceddba8f5d8fc86c859ea41fcc5b27772dcfe4 (presubmit successful).

[Ivan Posva, 2016-08-26 16:03:09]

iposva@google.com changed reviewers:
+ iposva@google.com

[Ivan Posva, 2016-08-26 16:03:10]

LGTM -ip