[compiler] Introduce code stubs for string relational comparisons.

[compiler] Introduce code stubs for string relational comparisons.

Add StringLessThanStub, StringLessThanOrEqualStub, StringGreaterThanStub
and StringGreaterThanOrEqualStub, based on the CodeStubAssembler, and
hook them up with TurboFan (and Ignition). The stubs are currently
essentially comparable with the StringCompareStub, which is now
obsolete. We can later extend these stubs to cover more interesting
cases (i.e. two byte sequential string comparisons, etc.).

R=epertoso@chromium.org

Committed: https://crrev.com/5912e0f014bd7b7d52cdc293145a912a4ecf2cf3
Cr-Commit-Position: refs/heads/master@{#34485}

[Benedikt Meurer, 2016-03-04 03:58:50]

Hey Enrico,

Here's the follow-up CL to add support for relational string comparisons.
Please take a look and CQ if you like it.

Thanks,
Benedikt

[Benedikt Meurer, 2016-03-04 04:00:27]

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

[commit-bot: I haz the power, 2016-03-04 04:00:33]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1765823002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1765823002/1

[commit-bot: I haz the power, 2016-03-04 04:39:17]

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

[commit-bot: I haz the power, 2016-03-04 04:39:20]

Dry run: This issue passed the CQ dry run.

[epertoso, 2016-03-04 09:22:25]

https://codereview.chromium.org/1765823002/diff/1/src/compiler/code-stub-asse...
File src/compiler/code-stub-assembler.cc (right):

https://codereview.chromium.org/1765823002/diff/1/src/compiler/code-stub-asse...
src/compiler/code-stub-assembler.cc:442: void
CodeStubAssembler::BranchIfInt32LessThan(Node* a, Node* b, Label* if_true,
Do we really need this? If so, it seems to me that we should directly use
if_true and if_false in the Branch instruction anyway.

[Benedikt Meurer, 2016-03-04 09:25:38]

https://codereview.chromium.org/1765823002/diff/1/src/compiler/code-stub-asse...
File src/compiler/code-stub-assembler.cc (right):

https://codereview.chromium.org/1765823002/diff/1/src/compiler/code-stub-asse...
src/compiler/code-stub-assembler.cc:442: void
CodeStubAssembler::BranchIfInt32LessThan(Node* a, Node* b, Label* if_true,
That's not correct because of edge-split-form, and you (currently) need a
dedicated Block for the IfTrue/IfFalse and another one for the Merge. You cannot
directly refer to a Merge block from a Branch.

[epertoso, 2016-03-04 09:35:16]

lgtm

https://codereview.chromium.org/1765823002/diff/1/src/compiler/code-stub-asse...
File src/compiler/code-stub-assembler.cc (right):

https://codereview.chromium.org/1765823002/diff/1/src/compiler/code-stub-asse...
src/compiler/code-stub-assembler.cc:442: void
CodeStubAssembler::BranchIfInt32LessThan(Node* a, Node* b, Label* if_true,
On 2016/03/04 at 09:25:38, Benedikt Meurer wrote:
> That's not correct because of edge-split-form, and you (currently) need a
dedicated Block for the IfTrue/IfFalse and another one for the Merge. You cannot
directly refer to a Merge block from a Branch.

Oh, I see what you mean. You use if_less and if_greater also with
BranchIfSmiLessThan. My bad.

[Benedikt Meurer, 2016-03-04 09:36:02]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2016-03-04 09:36:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1765823002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1765823002/1

[commit-bot: I haz the power, 2016-03-04 09:38:36]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-03-04 09:39:36]

Description was changed from

==========
[compiler] Introduce code stubs for string relational comparisons.

Add StringLessThanStub, StringLessThanOrEqualStub, StringGreaterThanStub
and StringGreaterThanOrEqualStub, based on the CodeStubAssembler, and
hook them up with TurboFan (and Ignition). The stubs are currently
essentially comparable with the StringCompareStub, which is now
obsolete. We can later extend these stubs to cover more interesting
cases (i.e. two byte sequential string comparisons, etc.).

R=epertoso@chromium.org
==========

to

==========
[compiler] Introduce code stubs for string relational comparisons.

Add StringLessThanStub, StringLessThanOrEqualStub, StringGreaterThanStub
and StringGreaterThanOrEqualStub, based on the CodeStubAssembler, and
hook them up with TurboFan (and Ignition). The stubs are currently
essentially comparable with the StringCompareStub, which is now
obsolete. We can later extend these stubs to cover more interesting
cases (i.e. two byte sequential string comparisons, etc.).

R=epertoso@chromium.org

Committed: https://crrev.com/5912e0f014bd7b7d52cdc293145a912a4ecf2cf3
Cr-Commit-Position: refs/heads/master@{#34485}
==========

[commit-bot: I haz the power, 2016-03-04 09:39:37]

Patchset 1 (id:??) landed as
https://crrev.com/5912e0f014bd7b7d52cdc293145a912a4ecf2cf3
Cr-Commit-Position: refs/heads/master@{#34485}