VM precompiler: Compute and use result type of static initializers of final fields.

VM precompiler: Compute and use result type of static initializers of final fields.

Perform a preprocessing pass to record
the result type of static initializers of static final fields.

The following round of precompilation benefits from result types for all loads from final
static fields.

BUG=
R=vegorov@google.com

Committed: https://github.com/dart-lang/sdk/commit/f0a4c407099b6f8d0eaea815f0fccc8584abf7ee

[Florian Schneider, 2016-05-12 11:09:07]

Description was changed from

==========
Compute and use result type of static initializers of final fields.

Perform two iterations of tree-shaking and precompilation and record
the result type of static initializers of static final fields.

The second round benefits from result types for all loads from final
static fields.

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

to

==========
VM precompiler: Compute and use result type of static initializers of final
fields.

Perform two iterations of tree-shaking and precompilation and record
the result type of static initializers of static final fields.

The second round benefits from result types for all loads from final
static fields.

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

[Florian Schneider, 2016-05-12 11:09:25]

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

[Vyacheslav Egorov (Google), 2016-05-12 11:18:55]

LGTM 

my main concern is negative impact on the compilation time this is going to
have.

https://codereview.chromium.org/1973553003/diff/20001/runtime/vm/precompiler.cc
File runtime/vm/precompiler.cc (right):

https://codereview.chromium.org/1973553003/diff/20001/runtime/vm/precompiler....
runtime/vm/precompiler.cc:57: DEFINE_FLAG(int, precompiler_rounds, 2, "Number of
precompiler iterations");
We should check that this does not slow down Flutter iteration times too much,
e.g. going from 7 seconds to to 14 seconds might be a bad idea.

Maybe have a true fix-point where we try to figure out which functions can be
affected and recompile only those?

[Florian Schneider, 2016-05-12 11:37:17]

https://codereview.chromium.org/1973553003/diff/20001/runtime/vm/precompiler.cc
File runtime/vm/precompiler.cc (right):

https://codereview.chromium.org/1973553003/diff/20001/runtime/vm/precompiler....
runtime/vm/precompiler.cc:57: DEFINE_FLAG(int, precompiler_rounds, 2, "Number of
precompiler iterations");
On 2016/05/12 11:18:55, Vyacheslav Egorov (Google) wrote:
> We should check that this does not slow down Flutter iteration times too much,
> e.g. going from 7 seconds to to 14 seconds might be a bad idea.
> 
> Maybe have a true fix-point where we try to figure out which functions can be
> affected and recompile only those?

Agree.

Current measurements shows 60% increase in snapshot generation time:

dart2js 13s -> 20s
hello 2.5s -> 4s

As discussed I'll look into selectively recompiling affected functions only to
bring this cost down.

[Florian Schneider, 2016-05-12 14:31:09]

Patchset #3 (id:40001) has been deleted

[Florian Schneider, 2016-05-13 08:54:34]

Patchset #3 (id:60001) has been deleted

[Florian Schneider, 2016-05-13 11:09:29]

Description was changed from

==========
VM precompiler: Compute and use result type of static initializers of final
fields.

Perform two iterations of tree-shaking and precompilation and record
the result type of static initializers of static final fields.

The second round benefits from result types for all loads from final
static fields.

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

to

==========
VM precompiler: Compute and use result type of static initializers of final
fields.

Perform a preprocessing pass to record
the result type of static initializers of static final fields.

The following round of precompilation benefits from result types for all loads
from final
static fields.

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

[Florian Schneider, 2016-05-13 11:12:12]

Ptal. Instead of doing two full iterations, I added a preprocessing step for
static initializers.

[Vyacheslav Egorov (Google), 2016-05-13 12:09:14]

lgtm

[Florian Schneider, 2016-05-13 13:43:43]

Description was changed from

==========
VM precompiler: Compute and use result type of static initializers of final
fields.

Perform a preprocessing pass to record
the result type of static initializers of static final fields.

The following round of precompilation benefits from result types for all loads
from final
static fields.

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

to

==========
VM precompiler: Compute and use result type of static initializers of final
fields.

Perform a preprocessing pass to record
the result type of static initializers of static final fields.

The following round of precompilation benefits from result types for all loads
from final
static fields.

BUG=
R=vegorov@google.com

Committed:
https://github.com/dart-lang/sdk/commit/f0a4c407099b6f8d0eaea815f0fccc8584abf7ee
==========

[Florian Schneider, 2016-05-13 13:43:46]

Committed patchset #4 (id:100001) manually as
f0a4c407099b6f8d0eaea815f0fccc8584abf7ee (presubmit successful).