Fix missing cases of empty_string canonicalization

Fix missing cases of empty_string canonicalization

Review-Url: https://codereview.chromium.org/2683903002
Cr-Commit-Position: refs/heads/master@{#43047}
Committed: https://chromium.googlesource.com/v8/v8/+/01882d7f6a2b8115c20482dd375dee65308edbf0

[Jakob Kummerow, 2017-02-08 01:41:56]

jkummerow@chromium.org changed reviewers:
+ ishell@chromium.org

[Jakob Kummerow, 2017-02-08 01:41:57]

Igor: PTAL.

Benedikt: FYI.

https://codereview.chromium.org/2683903002/diff/1/src/arm/macro-assembler-arm.cc
File src/arm/macro-assembler-arm.cc (left):

https://codereview.chromium.org/2683903002/diff/1/src/arm/macro-assembler-arm...
src/arm/macro-assembler-arm.cc:1541: void
MacroAssembler::InitializeNewString(Register string,
Found some dead code along the way ;-)

https://codereview.chromium.org/2683903002/diff/1/src/factory.cc
File src/factory.cc (right):

https://codereview.chromium.org/2683903002/diff/1/src/factory.cc#newcode823
src/factory.cc:823: if (length == 0) return empty_string();
Our public API would be fine with a DCHECK here, but we have cctests relying on
calling this function directly with zero-length inputs.

[Benedikt Meurer, 2017-02-08 03:53:07]

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

[Benedikt Meurer, 2017-02-08 03:53:08]

LGTM%nit

https://codereview.chromium.org/2683903002/diff/1/src/objects-debug.cc
File src/objects-debug.cc (right):

https://codereview.chromium.org/2683903002/diff/1/src/objects-debug.cc#newcod...
src/objects-debug.cc:555: CHECK(length() > 0 || this ==
GetHeap()->empty_string());
Nit: use CHECK_IMPLIES here.

[Igor Sheludko, 2017-02-08 07:27:52]

lgtm

[Jakob Kummerow, 2017-02-08 07:30:50]

The CQ bit was checked by jkummerow@chromium.org

[Jakob Kummerow, 2017-02-08 07:30:51]

The patchset sent to the CQ was uploaded after l-g-t-m from ishell@chromium.org,
bmeurer@chromium.org
Link to the patchset: https://codereview.chromium.org/2683903002/#ps20001
(title: "address nit")

[commit-bot: I haz the power, 2017-02-08 07:31:01]

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, 2017-02-08 07:50:47]

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

[commit-bot: I haz the power, 2017-02-08 07:50:49]

Try jobs failed on following builders:
  v8_linux64_asan_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_asan_rel_ng/buil...)
  v8_linux64_asan_rel_ng_triggered on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_asan_rel_ng_trig...)

[Jakob Kummerow, 2017-02-08 20:29:12]

The CQ bit was checked by jkummerow@chromium.org

[Jakob Kummerow, 2017-02-08 20:29:12]

The patchset sent to the CQ was uploaded after l-g-t-m from ishell@chromium.org,
bmeurer@chromium.org
Link to the patchset: https://codereview.chromium.org/2683903002/#ps40001
(title: "make LSan happy")

[commit-bot: I haz the power, 2017-02-08 20:29:22]

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, 2017-02-08 21:12:46]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1486585752241050,
"parent_rev": "ac231d625cad65bf8d28ff4eabbe6409627865cf", "commit_rev":
"01882d7f6a2b8115c20482dd375dee65308edbf0"}

[commit-bot: I haz the power, 2017-02-08 21:12:52]

Description was changed from

==========
Fix missing cases of empty_string canonicalization
==========

to

==========
Fix missing cases of empty_string canonicalization

Review-Url: https://codereview.chromium.org/2683903002
Cr-Commit-Position: refs/heads/master@{#43047}
Committed:
https://chromium.googlesource.com/v8/v8/+/01882d7f6a2b8115c20482dd375dee65308...
==========

[commit-bot: I haz the power, 2017-02-08 21:12:53]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/v8/v8/+/01882d7f6a2b8115c20482dd375dee65308...

[jgruber, 2017-02-10 10:10:39]

On 2017/02/08 21:12:53, commit-bot: I haz the power wrote:
> Committed patchset #3 (id:40001) as
>
https://chromium.googlesource.com/v8/v8/+/01882d7f6a2b8115c20482dd375dee65308...

FYI looks like this comes with nice perf improvements for RegExp
microbenchmarks:
https://chromeperf.appspot.com/report?sid=3e654f11cbb46bc96e70cc13501a44895da...