[turbofan] Eliminate unused effectful nodes during representation selection.

[turbofan] Eliminate unused effectful nodes during representation selection.

We can actually eliminate certain effectful operations like loads and
speculative number operations during representation selection if we
discover that their value outputs are unused (we also propagate this
information through pure operations as well, so that we remove the
maximum number of effectful nodes possible).

R=jarin@chromium.org

Committed: https://crrev.com/2744fcbb6cbb5e038601505e7ecdf09ba447d3fe
Cr-Commit-Position: refs/heads/master@{#37928}

[Benedikt Meurer, 2016-07-21 08:19:45]

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

[commit-bot: I haz the power, 2016-07-21 08:19:48]

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

[Jarin, 2016-07-21 08:23:09]

Nice. Thanks!

https://codereview.chromium.org/2168023002/diff/1/src/compiler/simplified-low...
File src/compiler/simplified-lowering.cc (right):

https://codereview.chromium.org/2168023002/diff/1/src/compiler/simplified-low...
src/compiler/simplified-lowering.cc:1194: return VisitLeaf(node,
MachineRepresentation::kTagged);
Comment why this is needed, please.

[Jarin, 2016-07-21 08:23:15]

lgtm

[Benedikt Meurer, 2016-07-21 08:26:21]

The CQ bit was checked by bmeurer@chromium.org

[Benedikt Meurer, 2016-07-21 08:26:21]

The patchset sent to the CQ was uploaded after l-g-t-m from jarin@chromium.org
Link to the patchset: https://codereview.chromium.org/2168023002/#ps20001
(title: "Add comment.")

[commit-bot: I haz the power, 2016-07-21 08:26:31]

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, 2016-07-21 08:41:13]

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

[commit-bot: I haz the power, 2016-07-21 08:41:14]

Try jobs failed on following builders:
  v8_linux64_avx2_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng/buil...)
  v8_linux64_avx2_rel_ng_triggered on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_avx2_rel_ng_trig...)

[Benedikt Meurer, 2016-07-21 08:44:21]

The CQ bit was checked by bmeurer@chromium.org

[Benedikt Meurer, 2016-07-21 08:44:22]

The patchset sent to the CQ was uploaded after l-g-t-m from jarin@chromium.org
Link to the patchset: https://codereview.chromium.org/2168023002/#ps40001
(title: "Fix VisitUnused for JS operators.")

[commit-bot: I haz the power, 2016-07-21 08:44:24]

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, 2016-07-21 09:09:34]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-07-21 09:10:16]

Description was changed from

==========
[turbofan] Eliminate unused effectful nodes during representation selection.

We can actually eliminate certain effectful operations like loads and
speculative number operations during representation selection if we
discover that their value outputs are unused (we also propagate this
information through pure operations as well, so that we remove the
maximum number of effectful nodes possible).

R=jarin@chromium.org
==========

to

==========
[turbofan] Eliminate unused effectful nodes during representation selection.

We can actually eliminate certain effectful operations like loads and
speculative number operations during representation selection if we
discover that their value outputs are unused (we also propagate this
information through pure operations as well, so that we remove the
maximum number of effectful nodes possible).

R=jarin@chromium.org

Committed: https://crrev.com/2744fcbb6cbb5e038601505e7ecdf09ba447d3fe
Cr-Commit-Position: refs/heads/master@{#37928}
==========

[commit-bot: I haz the power, 2016-07-21 09:10:17]

Patchset 3 (id:??) landed as
https://crrev.com/2744fcbb6cbb5e038601505e7ecdf09ba447d3fe
Cr-Commit-Position: refs/heads/master@{#37928}