Force slow objects for select objects during startup.

Force slow objects for select objects during startup.

BUG=
R=floitsch@google.com

Committed: https://code.google.com/p/dart/source/detail?r=44317

[herhut, 2015-02-24 14:11:34]

herhut@google.com changed reviewers:
+ floitsch@google.com

[herhut, 2015-02-24 14:11:34]

This improves startup performance of large applications. I see an about
200-300ms improvement.

This also contains another change that has little impact but cleans up the code.

[karlklose, 2015-02-24 14:58:47]

On 2015/02/24 14:11:34, herhut wrote:
> This improves startup performance of large applications. I see an about
> 200-300ms improvement.
> 
> This also contains another change that has little impact but cleans up the
code.

Could you extract the way to make fast/slow objects to a field in the emitter
that includes a short comment on the optimization?

[floitsch, 2015-02-24 20:21:39]

LGTM.

https://codereview.chromium.org/948383003/diff/1/pkg/compiler/lib/src/js_emit...
File pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart (right):

https://codereview.chromium.org/948383003/diff/1/pkg/compiler/lib/src/js_emit...
pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart:428: object.x = 0;
delete object.x; // Make object slow.
I discussed and benchmarked this with Slava. It looks like setting the __proto__
is a good option.
Short term this is the easier fix, though.

[herhut, 2015-02-26 15:18:37]

On 2015/02/24 14:58:47, karlklose wrote:
> On 2015/02/24 14:11:34, herhut wrote:
> > This improves startup performance of large applications. I see an about
> > 200-300ms improvement.
> > 
> > This also contains another change that has little impact but cleans up the
> code.
> 
> Could you extract the way to make fast/slow objects to a field in the emitter
> that includes a short comment on the optimization?

I will extract it in a follow-up CL. Currently under review in 

https://codereview.chromium.org/957343002/

[herhut, 2015-03-09 13:28:12]

Committed patchset #1 (id:1) manually as 44317 (presubmit successful).

[herhut, 2015-03-09 15:11:05]

https://codereview.chromium.org/948383003/diff/1/pkg/compiler/lib/src/js_emit...
File pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart (right):

https://codereview.chromium.org/948383003/diff/1/pkg/compiler/lib/src/js_emit...
pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart:428: object.x = 0;
delete object.x; // Make object slow.
On 2015/02/24 20:21:39, floitsch wrote:
> I discussed and benchmarked this with Slava. It looks like setting the
__proto__
> is a good option.
> Short term this is the easier fix, though.

Acknowledged.