[turbofan] Insert dummy values when changing from None type.

[turbofan] Insert dummy values when changing from None type.

Currently we choose the MachineRepresentation::kNone representation for
values of Type::None, and when converting values from the kNone representation
we use "impossible" conversions that will crash at runtime. This
assumes that the impossible conversions should never be hit (the only
way to produce the impossible values is to perform an always-failing
runtime check on a value, such as Smi-checking a string). Note that
this assumes that the runtime check is executed before the impossible
convesrion.

Introducing BitwiseOr type feedback broke this in two ways:

- we always pick Word32 representation for bitwise-or, so the
  impossible conversion does not trigger (it only triggers with
  None representation), and we could end up with unsupported
  conversions from Word32.

- even if we inserted impossible conversions, they are pure conversions.
  Since untagging, bitwise-or operations are also pure, we could hoist
  all these before the smi check of the inputs and we could hit the
  impossible conversions before we get to the smi check.

This CL addresses this by just providing dummy values for conversions
from the Type::None type. It also removes the impossible-to-* conversions.

BUG=chromium:638132
Committed: https://crrev.com/c83b21ab755f1420b6da85b3ff43d7e96ead9bbe
Cr-Commit-Position: refs/heads/master@{#38883}

[Jarin, 2016-08-22 08:41:17]

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

[commit-bot: I haz the power, 2016-08-22 08:41:26]

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, 2016-08-22 08:47:13]

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

[commit-bot: I haz the power, 2016-08-22 08:47:13]

Dry run: Try jobs failed on following builders:
  v8_android_arm_compile_rel on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_android_arm_compile_rel/...)

[Jarin, 2016-08-22 08:58:55]

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

[commit-bot: I haz the power, 2016-08-22 08:59:03]

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, 2016-08-22 09:04:14]

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

[commit-bot: I haz the power, 2016-08-22 09:04:15]

Dry run: 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...)

[Jarin, 2016-08-22 09:46:46]

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

[commit-bot: I haz the power, 2016-08-22 09:46:48]

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, 2016-08-22 10:04:55]

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

[commit-bot: I haz the power, 2016-08-22 10:04:56]

Dry run: 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...)

[Jarin, 2016-08-22 11:36:38]

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

[commit-bot: I haz the power, 2016-08-22 11:36:41]

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, 2016-08-22 12:01:49]

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

[commit-bot: I haz the power, 2016-08-22 12:01:50]

Dry run: This issue passed the CQ dry run.

[Jarin, 2016-08-22 12:19:06]

jarin@chromium.org changed reviewers:
+ mstarzinger@chromium.org

[Jarin, 2016-08-22 12:19:06]

Could you take a look, please?

[Michael Starzinger, 2016-08-24 14:22:20]

LGTM.

[Jarin, 2016-08-25 05:12:51]

The CQ bit was checked by jarin@chromium.org

[commit-bot: I haz the power, 2016-08-25 05:12:57]

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, 2016-08-25 05:14:08]

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

[commit-bot: I haz the power, 2016-08-25 05:14:09]

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_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux64_rel_ng/builds/11555)
  v8_linux_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_linux_rel_ng/builds/11495)
  v8_mac_rel_ng on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_mac_rel_ng/builds/7615)

[Jarin, 2016-08-25 05:40:18]

The CQ bit was checked by jarin@chromium.org

[Jarin, 2016-08-25 05:40:19]

The patchset sent to the CQ was uploaded after l-g-t-m from
mstarzinger@chromium.org
Link to the patchset: https://codereview.chromium.org/2266823002/#ps80001
(title: "Rebase")

[commit-bot: I haz the power, 2016-08-25 05:40:24]

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, 2016-08-25 06:06:49]

Committed patchset #5 (id:80001)

[commit-bot: I haz the power, 2016-08-25 06:07:07]

Description was changed from

==========
[turbofan] Insert dummy values when changing from None type.

Currently we choose the MachineRepresentation::kNone representation for
values of Type::None, and when converting values from the kNone representation
we use "impossible" conversions that will crash at runtime. This
assumes that the impossible conversions should never be hit (the only
way to produce the impossible values is to perform an always-failing
runtime check on a value, such as Smi-checking a string). Note that
this assumes that the runtime check is executed before the impossible
convesrion.

Introducing BitwiseOr type feedback broke this in two ways:

- we always pick Word32 representation for bitwise-or, so the
  impossible conversion does not trigger (it only triggers with
  None representation), and we could end up with unsupported
  conversions from Word32.

- even if we inserted impossible conversions, they are pure conversions.
  Since untagging, bitwise-or operations are also pure, we could hoist
  all these before the smi check of the inputs and we could hit the
  impossible conversions before we get to the smi check.

This CL addresses this by just providing dummy values for conversions
from the Type::None type. It also removes the impossible-to-* conversions.

BUG=chromium:638132
==========

to

==========
[turbofan] Insert dummy values when changing from None type.

Currently we choose the MachineRepresentation::kNone representation for
values of Type::None, and when converting values from the kNone representation
we use "impossible" conversions that will crash at runtime. This
assumes that the impossible conversions should never be hit (the only
way to produce the impossible values is to perform an always-failing
runtime check on a value, such as Smi-checking a string). Note that
this assumes that the runtime check is executed before the impossible
convesrion.

Introducing BitwiseOr type feedback broke this in two ways:

- we always pick Word32 representation for bitwise-or, so the
  impossible conversion does not trigger (it only triggers with
  None representation), and we could end up with unsupported
  conversions from Word32.

- even if we inserted impossible conversions, they are pure conversions.
  Since untagging, bitwise-or operations are also pure, we could hoist
  all these before the smi check of the inputs and we could hit the
  impossible conversions before we get to the smi check.

This CL addresses this by just providing dummy values for conversions
from the Type::None type. It also removes the impossible-to-* conversions.

BUG=chromium:638132

Committed: https://crrev.com/c83b21ab755f1420b6da85b3ff43d7e96ead9bbe
Cr-Commit-Position: refs/heads/master@{#38883}
==========

[commit-bot: I haz the power, 2016-08-25 06:07:08]

Patchset 5 (id:??) landed as
https://crrev.com/c83b21ab755f1420b6da85b3ff43d7e96ead9bbe
Cr-Commit-Position: refs/heads/master@{#38883}

[Benedikt Meurer, 2016-08-25 08:49:05]

A revert of this CL (patchset #5 id:80001) has been created in
https://codereview.chromium.org/2280613002/ by bmeurer@chromium.org.

The reason for reverting is: Octane/Mandreel aborts with an exception now:

TypeError: __FUNCTION_TABLE__[(r2 >> 2)] is not a function.