Tree shaker:

Tree shaker:
 - Don't remove entries from a library's dictionary while iterating over it.
 - Remove library prefixes from library dictionaries.
 - Compact library dictionaries after removing entries.
 - Track snapshot references in debug mode and give a backtrace when unencountering an unexpected object.
 - Verify removed libraries are not included in the snapshot by marking their top-level classes.

R=asiva@google.com

Committed: https://github.com/dart-lang/sdk/commit/17e43f284b05f037cd567ea7b038907987b7aff7

[rmacnak, 2017-04-18 19:53:41]

Description was changed from

==========
WIP: shake prefixes
==========

to

==========
Tree shaker:
 - Don't remove entries from a library's dictionary while iterating over it.
 - Remove library prefixes from library dictionaries.
 - Compact library dictionaries after removing entries.
 - Track snapshot references in debug mode and give a backtrace when
unencountering an unexpected object.
 - Verify removed libraries are not included in the snapshot by marking their
top-level classes.
==========

[rmacnak, 2017-04-18 19:57:42]

Description was changed from

==========
Tree shaker:
 - Don't remove entries from a library's dictionary while iterating over it.
 - Remove library prefixes from library dictionaries.
 - Compact library dictionaries after removing entries.
 - Track snapshot references in debug mode and give a backtrace when
unencountering an unexpected object.
 - Verify removed libraries are not included in the snapshot by marking their
top-level classes.
==========

to

==========
Tree shaker:
 - Don't remove entries from a library's dictionary while iterating over it.
 - Remove library prefixes from library dictionaries.
 - Compact library dictionaries after removing entries.
 - Track snapshot references in debug mode and give a backtrace when
unencountering an unexpected object.
 - Verify removed libraries are not included in the snapshot by marking their
top-level classes.
==========

[rmacnak, 2017-04-18 20:19:43]

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

[rmacnak, 2017-04-18 20:53:54]

On 2017/04/18 20:19:44, rmacnak wrote:

Removes an additional 53 libraries from //apps/sysui/userpicker_device_shell.

script:
478 libraries

aot before:
275 libraries
VMIsolate(CodeSize): 4760
Isolate(CodeSize): 1693986
ReadOnlyData(CodeSize): 3072688
Instructions(CodeSize): 9486944
Total(CodeSize): 14258378

aot after:
222 libraries
VMIsolate(CodeSize): 4760
Isolate(CodeSize): 1679024 -0.88%
ReadOnlyData(CodeSize): 3063984
Instructions(CodeSize): 9463264
Total(CodeSize): 14211032 -0.33%

I'll note that the tree shaker says most (53%) imports in this program are
unused.

[siva, 2017-04-18 21:17:59]

lgtm

https://codereview.chromium.org/2823873003/diff/60001/runtime/vm/clustered_sn...
File runtime/vm/clustered_snapshot.h (right):

https://codereview.chromium.org/2823873003/diff/60001/runtime/vm/clustered_sn...
runtime/vm/clustered_snapshot.h:25: #endif
If this is going to be always on when DEBUG is defined why have this extra
define, why not just use #if defined(DEBUG) for the code that is used for
snapshot backtraces.

[rmacnak, 2017-04-18 23:48:14]

On 2017/04/18 21:17:59, siva wrote:
> lgtm
> 
>
https://codereview.chromium.org/2823873003/diff/60001/runtime/vm/clustered_sn...
> File runtime/vm/clustered_snapshot.h (right):
> 
>
https://codereview.chromium.org/2823873003/diff/60001/runtime/vm/clustered_sn...
> runtime/vm/clustered_snapshot.h:25: #endif
> If this is going to be always on when DEBUG is defined why have this extra
> define, why not just use #if defined(DEBUG) for the code that is used for
> snapshot backtraces.

It's like Srdjan's TAG_IC_DATA. It lets one turn it on in another mode if needed
for debugging. For instance, we include fewer objects in product mode than
release mode because we don't support the profiler, and that potentially affects
what references pull in an object.

[rmacnak, 2017-04-19 17:03:47]

Description was changed from

==========
Tree shaker:
 - Don't remove entries from a library's dictionary while iterating over it.
 - Remove library prefixes from library dictionaries.
 - Compact library dictionaries after removing entries.
 - Track snapshot references in debug mode and give a backtrace when
unencountering an unexpected object.
 - Verify removed libraries are not included in the snapshot by marking their
top-level classes.
==========

to

==========
Tree shaker:
 - Don't remove entries from a library's dictionary while iterating over it.
 - Remove library prefixes from library dictionaries.
 - Compact library dictionaries after removing entries.
 - Track snapshot references in debug mode and give a backtrace when
unencountering an unexpected object.
 - Verify removed libraries are not included in the snapshot by marking their
top-level classes.

R=asiva@google.com

Committed:
https://github.com/dart-lang/sdk/commit/17e43f284b05f037cd567ea7b038907987b7aff7
==========

[rmacnak, 2017-04-19 17:03:51]

Committed patchset #4 (id:60001) manually as
17e43f284b05f037cd567ea7b038907987b7aff7 (presubmit successful).