Replace StringImpl::empty{16Bit}() with a static member

Replace StringImpl::empty{16Bit}() with a static member

These static method calls have been showing up in profiles, especially
for StringView("string literal") construction. This patch eliminates
that overhead.

BUG=684604
Review-Url: https://codereview.chromium.org/2655853003
Cr-Commit-Position: refs/heads/master@{#447526}
Committed: https://chromium.googlesource.com/chromium/src/+/2c3e23286499227cda716bdadd43f8f4ef319cc6

[Charlie Harrison, 2017-01-25 16:33:29]

The CQ bit was checked by csharrison@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-01-25 16:33:43]

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

[Charlie Harrison, 2017-01-25 18:10:04]

csharrison@chromium.org changed reviewers:
+ esprehn@chromium.org

[Charlie Harrison, 2017-01-25 18:10:04]

Hey Elliott, PTAL at this approach. I opted to keep the empties as static
members because StringImpl::empty is much more readable to me than emptyImpl or
emptyStringImpl just hanging off WTF like the atoms.

I verified that this improves the profiled construction time.

[commit-bot: I haz the power, 2017-01-25 18:55:23]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-01-25 18:55:24]

Dry run: This issue passed the CQ dry run.

[esprehn, 2017-02-01 05:23:44]

lgtm

https://codereview.chromium.org/2655853003/diff/1/third_party/WebKit/Source/w...
File third_party/WebKit/Source/wtf/text/WTFString.cpp (right):

https://codereview.chromium.org/2655853003/diff/1/third_party/WebKit/Source/w...
third_party/WebKit/Source/wtf/text/WTFString.cpp:789: return emptyString;
We should probably make these statics too.

[Charlie Harrison, 2017-02-01 05:29:48]

thanks

https://codereview.chromium.org/2655853003/diff/1/third_party/WebKit/Source/w...
File third_party/WebKit/Source/wtf/text/WTFString.cpp (right):

https://codereview.chromium.org/2655853003/diff/1/third_party/WebKit/Source/w...
third_party/WebKit/Source/wtf/text/WTFString.cpp:789: return emptyString;
On 2017/02/01 05:23:44, esprehn wrote:
> We should probably make these statics too.

Yeah I can probably do another patch for this, but there are a *lot* more
callers so the patch will be intense (unless we do something weird like inline
the function).

[Charlie Harrison, 2017-02-01 05:29:55]

The CQ bit was checked by csharrison@chromium.org

[commit-bot: I haz the power, 2017-02-01 05:30:12]

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

[esprehn, 2017-02-01 05:47:39]

https://codereview.chromium.org/2655853003/diff/1/third_party/WebKit/Source/w...
File third_party/WebKit/Source/wtf/text/WTFString.cpp (right):

https://codereview.chromium.org/2655853003/diff/1/third_party/WebKit/Source/w...
third_party/WebKit/Source/wtf/text/WTFString.cpp:789: return emptyString;
On 2017/02/01 at 05:29:48, Charlie Harrison-slow til Feb3 wrote:
> On 2017/02/01 05:23:44, esprehn wrote:
> > We should probably make these statics too.
> 
> Yeah I can probably do another patch for this, but there are a *lot* more
callers so the patch will be intense (unless we do something weird like inline
the function).

That seems like a reasonable thing to do. Add String::empty and then make the
function inline and just return it. Add a TODO to clean up the tons of callers.
Then someone motivated (maybe you later) can clean it up.

[commit-bot: I haz the power, 2017-02-01 06:39:56]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-02-01 06:39:57]

Try jobs failed on following builders:
  linux_chromium_tsan_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[Charlie Harrison, 2017-02-01 06:46:14]

Guessing we need to annotate a benign race, let me try again.

[Charlie Harrison, 2017-02-01 07:48:55]

The CQ bit was checked by csharrison@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-02-01 07:49:08]

Dry run: 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, 2017-02-01 10:04:01]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-02-01 10:04:02]

Dry run: This issue passed the CQ dry run.

[Charlie Harrison, 2017-02-01 16:10:44]

The CQ bit was checked by csharrison@chromium.org

[Charlie Harrison, 2017-02-01 16:10:45]

The patchset sent to the CQ was uploaded after l-g-t-m from esprehn@chromium.org
Link to the patchset: https://codereview.chromium.org/2655853003/#ps40001
(title: "annotate race")

[commit-bot: I haz the power, 2017-02-01 16:10:56]

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, 2017-02-01 16:15:29]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1485965444791030,
"parent_rev": "be62e9d349e2570467d4d86326d9b8f31bedc0fc", "commit_rev":
"2c3e23286499227cda716bdadd43f8f4ef319cc6"}

[commit-bot: I haz the power, 2017-02-01 16:16:02]

Description was changed from

==========
Replace StringImpl::empty{16Bit}() with a static member

These static method calls have been showing up in profiles, especially
for StringView("string literal") construction. This patch eliminates
that overhead.

BUG=684604
==========

to

==========
Replace StringImpl::empty{16Bit}() with a static member

These static method calls have been showing up in profiles, especially
for StringView("string literal") construction. This patch eliminates
that overhead.

BUG=684604

Review-Url: https://codereview.chromium.org/2655853003
Cr-Commit-Position: refs/heads/master@{#447526}
Committed:
https://chromium.googlesource.com/chromium/src/+/2c3e23286499227cda716bdadd43...
==========

[commit-bot: I haz the power, 2017-02-01 16:16:04]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/chromium/src/+/2c3e23286499227cda716bdadd43...