Turn Scope::locals_ into a ThreadedList

Turn Scope::locals_ into a ThreadedList

This turns the ZoneList with minimum 6 words overhead into a linked list through variables, using 2 words for the empty list. Additionally the average number of pointers per entry goes down to the optimal 1 per variable that's in a list.

This does introduce 1 pointer unnecessary overhead for dynamic variables. If that becomes a problem we could distinguish between variables in lists and variables not in lists. We can distinguish them at construction-time.

BUG=v8:5209
Committed: https://crrev.com/4fa2ebcbe0d8207cbea45dae6610725c24052915
Cr-Commit-Position: refs/heads/master@{#40714}

[Toon Verwaest, 2016-11-02 15:55:32]

Description was changed from

==========
Turn Scope::locals_ into a ThreadedList

BUG=v8:5209
==========

to

==========
Turn Scope::locals_ into a ThreadedList

This turns the ZoneList with minimum 6 words overhead into a linked list through
variables, using 2 words for the empty list. Additionally the average number of
pointers per entry goes down to the optimal 1 per variable that's in a list.

This does introduce 1 pointer unnecessary overhead for dynamic variables. If
that becomes a problem we could distinguish between variables in lists and
variables not in lists. We can distinguish them at construction-time.

BUG=v8:5209
==========

[Toon Verwaest, 2016-11-02 15:55:32]

verwaest@chromium.org changed reviewers:
+ adamk@chromium.org

[Toon Verwaest, 2016-11-02 15:55:39]

ptal

[adamk, 2016-11-02 18:54:05]

lgtm % nits/comments

https://codereview.chromium.org/2475433002/diff/60001/src/ast/scopes.cc
File src/ast/scopes.cc (right):

https://codereview.chromium.org/2475433002/diff/60001/src/ast/scopes.cc#newco...
src/ast/scopes.cc:1273: *var->next() = nullptr;
Please add TODOs here and below, since it looks like you're trying to get rid of
these?

https://codereview.chromium.org/2475433002/diff/60001/src/utils.h
File src/utils.h (right):

https://codereview.chromium.org/2475433002/diff/60001/src/utils.h#newcode1651
src/utils.h:1651: void MoveTail(ThreadedList<T>& parent, Iterator location) {
Please make this a pointer, I don't think we generally use non-const references
like this.

Also this method could use a comment.

[Toon Verwaest, 2016-11-02 18:59:58]

https://codereview.chromium.org/2475433002/diff/60001/src/ast/scopes.cc
File src/ast/scopes.cc (right):

https://codereview.chromium.org/2475433002/diff/60001/src/ast/scopes.cc#newco...
src/ast/scopes.cc:1273: *var->next() = nullptr;
On 2016/11/02 18:54:05, adamk wrote:
> Please add TODOs here and below, since it looks like you're trying to get rid
of
> these?

Will do. There's already a cl in the pipeline from Marja that removes the need
for this entire block. It's kinda included in the TODO above, but I can add it
here as well.

[Yang, 2016-11-03 08:13:19]

yangguo@chromium.org changed reviewers:
+ yangguo@chromium.org

[Yang, 2016-11-03 08:13:19]

https://codereview.chromium.org/2475433002/diff/60001/src/debug/liveedit.cc
File src/debug/liveedit.cc (right):

https://codereview.chromium.org/2475433002/diff/60001/src/debug/liveedit.cc#n...
src/debug/liveedit.cc:1903: for (Variable* var : *current_scope->locals()) {
lgtm.

[Toon Verwaest, 2016-11-03 09:39:29]

Addressed comments.

[Toon Verwaest, 2016-11-03 09:39:33]

The CQ bit was checked by verwaest@chromium.org

[Toon Verwaest, 2016-11-03 09:39:34]

The patchset sent to the CQ was uploaded after l-g-t-m from adamk@chromium.org,
yangguo@chromium.org
Link to the patchset: https://codereview.chromium.org/2475433002/#ps80001
(title: "Addressed comments")

[commit-bot: I haz the power, 2016-11-03 09:39:35]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-11-03 10:06:32]

Description was changed from

==========
Turn Scope::locals_ into a ThreadedList

This turns the ZoneList with minimum 6 words overhead into a linked list through
variables, using 2 words for the empty list. Additionally the average number of
pointers per entry goes down to the optimal 1 per variable that's in a list.

This does introduce 1 pointer unnecessary overhead for dynamic variables. If
that becomes a problem we could distinguish between variables in lists and
variables not in lists. We can distinguish them at construction-time.

BUG=v8:5209
==========

to

==========
Turn Scope::locals_ into a ThreadedList

This turns the ZoneList with minimum 6 words overhead into a linked list through
variables, using 2 words for the empty list. Additionally the average number of
pointers per entry goes down to the optimal 1 per variable that's in a list.

This does introduce 1 pointer unnecessary overhead for dynamic variables. If
that becomes a problem we could distinguish between variables in lists and
variables not in lists. We can distinguish them at construction-time.

BUG=v8:5209
==========

[commit-bot: I haz the power, 2016-11-03 10:06:33]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2016-11-17 22:20:01]

Description was changed from

==========
Turn Scope::locals_ into a ThreadedList

This turns the ZoneList with minimum 6 words overhead into a linked list through
variables, using 2 words for the empty list. Additionally the average number of
pointers per entry goes down to the optimal 1 per variable that's in a list.

This does introduce 1 pointer unnecessary overhead for dynamic variables. If
that becomes a problem we could distinguish between variables in lists and
variables not in lists. We can distinguish them at construction-time.

BUG=v8:5209
==========

to

==========
Turn Scope::locals_ into a ThreadedList

This turns the ZoneList with minimum 6 words overhead into a linked list through
variables, using 2 words for the empty list. Additionally the average number of
pointers per entry goes down to the optimal 1 per variable that's in a list.

This does introduce 1 pointer unnecessary overhead for dynamic variables. If
that becomes a problem we could distinguish between variables in lists and
variables not in lists. We can distinguish them at construction-time.

BUG=v8:5209

Committed: https://crrev.com/4fa2ebcbe0d8207cbea45dae6610725c24052915
Cr-Commit-Position: refs/heads/master@{#40714}
==========

[commit-bot: I haz the power, 2016-11-17 22:20:02]

Patchset 5 (id:??) landed as
https://crrev.com/4fa2ebcbe0d8207cbea45dae6610725c24052915
Cr-Commit-Position: refs/heads/master@{#40714}