[turbofan] Remove special JSForInStep and JSForInDone.

[turbofan] Remove special JSForInStep and JSForInDone.

These JavaScript operators were special hacks to ensure that we always
operate on Smis for the magic for-in index variable, but this never
really worked in the OSR case, because the OsrValue for the index
variable didn't have the proper information (that we have for the
JSForInPrepare in the non-OSR case).

Now that we have loop induction variable analysis and binary operation
hints, we can just use JSLessThan and JSAdd instead with appropriate
Smi hints, which handle the OSR case by inserting Smi checks (that are
always true). Thanks to OSR deconstruction and loop peeling these Smi
checks will be hoisted so they don't hurt the OSR case too much.

Drive-by-change: Rename the ForInDone bytecode to ForInContinue, since
we have to lower it to JSLessThan to get the loop induction variable
goodness.

R=epertoso@chromium.org
BUG=v8:5267
Committed: https://crrev.com/1915762cc8caea42727daebfe738bfcdca8ac859
Cr-Commit-Position: refs/heads/master@{#38968}

[Benedikt Meurer, 2016-08-29 08:06:18]

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

[commit-bot: I haz the power, 2016-08-29 08:06:26]

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, 2016-08-29 08:32:01]

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

[commit-bot: I haz the power, 2016-08-29 08:32:02]

Dry run: This issue passed the CQ dry run.

[epertoso, 2016-08-29 08:32:07]

lgtm

[Benedikt Meurer, 2016-08-29 08:45:28]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2016-08-29 08:45:32]

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, 2016-08-29 08:47:17]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-29 08:47:45]

Description was changed from

==========
[turbofan] Remove special JSForInStep and JSForInDone.

These JavaScript operators were special hacks to ensure that we always
operate on Smis for the magic for-in index variable, but this never
really worked in the OSR case, because the OsrValue for the index
variable didn't have the proper information (that we have for the
JSForInPrepare in the non-OSR case).

Now that we have loop induction variable analysis and binary operation
hints, we can just use JSLessThan and JSAdd instead with appropriate
Smi hints, which handle the OSR case by inserting Smi checks (that are
always true). Thanks to OSR deconstruction and loop peeling these Smi
checks will be hoisted so they don't hurt the OSR case too much.

Drive-by-change: Rename the ForInDone bytecode to ForInContinue, since
we have to lower it to JSLessThan to get the loop induction variable
goodness.

R=epertoso@chromium.org
BUG=v8:5267
==========

to

==========
[turbofan] Remove special JSForInStep and JSForInDone.

These JavaScript operators were special hacks to ensure that we always
operate on Smis for the magic for-in index variable, but this never
really worked in the OSR case, because the OsrValue for the index
variable didn't have the proper information (that we have for the
JSForInPrepare in the non-OSR case).

Now that we have loop induction variable analysis and binary operation
hints, we can just use JSLessThan and JSAdd instead with appropriate
Smi hints, which handle the OSR case by inserting Smi checks (that are
always true). Thanks to OSR deconstruction and loop peeling these Smi
checks will be hoisted so they don't hurt the OSR case too much.

Drive-by-change: Rename the ForInDone bytecode to ForInContinue, since
we have to lower it to JSLessThan to get the loop induction variable
goodness.

R=epertoso@chromium.org
BUG=v8:5267

Committed: https://crrev.com/1915762cc8caea42727daebfe738bfcdca8ac859
Cr-Commit-Position: refs/heads/master@{#38968}
==========

[commit-bot: I haz the power, 2016-08-29 08:47:46]

Patchset 1 (id:??) landed as
https://crrev.com/1915762cc8caea42727daebfe738bfcdca8ac859
Cr-Commit-Position: refs/heads/master@{#38968}