[wasm] Minor optimization for parallel compilation

[wasm] Minor optimization for parallel compilation

Skip parallel compilation if less than two functions need to be
compiled, and skip over imported functions instead of adding nullptrs
for them to the compilation_units_ vector.

R=titzer@chromium.org, ahaas@chromium.org

Review-Url: https://codereview.chromium.org/2718053002
Cr-Commit-Position: refs/heads/master@{#43449}
Committed: https://chromium.googlesource.com/v8/v8/+/b2177684cba03edae816ea9779c501a7a47ba6a2

[Clemens Hammacher, 2017-02-27 12:03:06]

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

[commit-bot: I haz the power, 2017-02-27 12:03:16]

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, 2017-02-27 12:31:05]

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

[commit-bot: I haz the power, 2017-02-27 12:31:06]

Dry run: This issue passed the CQ dry run.

[titzer, 2017-02-27 12:49:14]

lgtm

[ahaas, 2017-02-27 12:52:59]

lgtm

[Clemens Hammacher, 2017-02-27 12:55:08]

The CQ bit was checked by clemensh@chromium.org

[commit-bot: I haz the power, 2017-02-27 12:55:17]

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, 2017-02-27 12:56:54]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1488200108593180, "parent_rev":
"06aeb4eceaea75fd69671c447e25ddaa2fc1dd69", "commit_rev":
"b2177684cba03edae816ea9779c501a7a47ba6a2"}

[commit-bot: I haz the power, 2017-02-27 12:57:00]

Description was changed from

==========
[wasm] Minor optimization for parallel compilation

Skip parallel compilation if less than two functions need to be
compiled, and skip over imported functions instead of adding nullptrs
for them to the compilation_units_ vector.

R=titzer@chromium.org, ahaas@chromium.org
==========

to

==========
[wasm] Minor optimization for parallel compilation

Skip parallel compilation if less than two functions need to be
compiled, and skip over imported functions instead of adding nullptrs
for them to the compilation_units_ vector.

R=titzer@chromium.org, ahaas@chromium.org

Review-Url: https://codereview.chromium.org/2718053002
Cr-Commit-Position: refs/heads/master@{#43449}
Committed:
https://chromium.googlesource.com/v8/v8/+/b2177684cba03edae816ea9779c501a7a47...
==========

[commit-bot: I haz the power, 2017-02-27 12:57:01]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/b2177684cba03edae816ea9779c501a7a47...