Fix a bug with await in finally.

Kernel: Fix a bug with await in finally.

The translation for async and async* functions translates returns into
two statements, where the second one is a return.  The VM's compilation
strategy is to inline the code for all finally blocks immediately before
a return statement.

This causes future completion/stream cancellation to occur before
finally blocks, instead of after as intended.

The solution here is to translate returns into a break from a labeled
block and put a single async/async* return sequence, outside any finally
blocks, after the labeled block.

BUG=
R=asgerf@google.com

Committed: https://github.com/dart-lang/kernel/commit/290f955760a219902e4d5b716668bff29711d1ab

[Kevin Millikin (Google), 2016-11-03 09:22:56]

Description was changed from

==========
Fix a bug with await in finally.

The translation for async and async* functions translates returns into
two statements, where the second one is a return.  The VM's compilation
strategy is to inline the code for all finally blocks immediately before
a return statement.

This causes future completion/stream cancellation to occur before
finally blocks, instead of after as intended.

The solution here is to translate returns into a break from a labeled
block and put a single async/async* return sequence, outside any finally
blocks, after the labeled block.

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

to

==========
Kernel: Fix a bug with await in finally.

The translation for async and async* functions translates returns into
two statements, where the second one is a return.  The VM's compilation
strategy is to inline the code for all finally blocks immediately before
a return statement.

This causes future completion/stream cancellation to occur before
finally blocks, instead of after as intended.

The solution here is to translate returns into a break from a labeled
block and put a single async/async* return sequence, outside any finally
blocks, after the labeled block.

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

[Kevin Millikin (Google), 2016-11-03 09:22:57]

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

[asgerf, 2016-11-03 09:31:08]

LGTM

[asgerf, 2016-11-03 09:32:39]

https://codereview.chromium.org/2476513003/diff/1/lib/transformations/continu...
File lib/transformations/continuation.dart (right):

https://codereview.chromium.org/2476513003/diff/1/lib/transformations/continu...
lib/transformations/continuation.dart:718: statements.add(new
BreakStatement(labeledBody));
Maybe copy over the breakpoint location from the return statement.

[Kevin Millikin (Google), 2016-11-03 09:43:53]

https://codereview.chromium.org/2476513003/diff/1/lib/transformations/continu...
File lib/transformations/continuation.dart (right):

https://codereview.chromium.org/2476513003/diff/1/lib/transformations/continu...
lib/transformations/continuation.dart:718: statements.add(new
BreakStatement(labeledBody));
On 2016/11/03 09:32:39, asgerf wrote:
> Maybe copy over the breakpoint location from the return statement.

Thanks, done.

[Kevin Millikin (Google), 2016-11-03 09:44:28]

Description was changed from

==========
Kernel: Fix a bug with await in finally.

The translation for async and async* functions translates returns into
two statements, where the second one is a return.  The VM's compilation
strategy is to inline the code for all finally blocks immediately before
a return statement.

This causes future completion/stream cancellation to occur before
finally blocks, instead of after as intended.

The solution here is to translate returns into a break from a labeled
block and put a single async/async* return sequence, outside any finally
blocks, after the labeled block.

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

to

==========
Kernel: Fix a bug with await in finally.

The translation for async and async* functions translates returns into
two statements, where the second one is a return.  The VM's compilation
strategy is to inline the code for all finally blocks immediately before
a return statement.

This causes future completion/stream cancellation to occur before
finally blocks, instead of after as intended.

The solution here is to translate returns into a break from a labeled
block and put a single async/async* return sequence, outside any finally
blocks, after the labeled block.

BUG=
R=asgerf@google.com

Committed:
https://github.com/dart-lang/kernel/commit/290f955760a219902e4d5b716668bff297...
==========

[Kevin Millikin (Google), 2016-11-03 09:44:29]

Committed patchset #2 (id:20001) manually as
290f955760a219902e4d5b716668bff29711d1ab (presubmit successful).