[turbofan] Let ChangeFloat64ToTagged canonicalize to Smi if possible.

[turbofan] Let ChangeFloat64ToTagged canonicalize to Smi if possible.

When the incoming value to ChangeFloat64ToTagged is in Smi range, we
represent it as Smi instead of a HeapNumber. This addresses a range of
problems where TurboFan unnecessarily deoptimizes because an operation
learned Smi feedback in Ignition, but was then confronted with a tagged
HeapNumber in TurboFan, just because the value was also represented as
unboxed double somewhere in the meantime.

BUG=v8:6256
R=yangguo@chromium.org

Review-Url: https://codereview.chromium.org/2815283002
Cr-Commit-Position: refs/heads/master@{#44631}
Committed: https://chromium.googlesource.com/v8/v8/+/385734bf11d3c4529cc30c553eef8c3e0d69afad

[Benedikt Meurer, 2017-04-13 06:34:39]

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

[commit-bot: I haz the power, 2017-04-13 06:34:47]

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

[Yang, 2017-04-13 06:36:45]

On 2017/04/13 06:34:38, Benedikt Meurer wrote:

lgtm. thanks.

[Benedikt Meurer, 2017-04-13 06:37:08]

The CQ bit was unchecked by bmeurer@chromium.org

[Benedikt Meurer, 2017-04-13 06:37:15]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2017-04-13 06:37:17]

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, 2017-04-13 06:57:05]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1492065435512430, "parent_rev":
"b2831b5ddc3d47b3a37570439ca4dc0d4d8d1e70", "commit_rev":
"385734bf11d3c4529cc30c553eef8c3e0d69afad"}

[commit-bot: I haz the power, 2017-04-13 06:57:10]

Description was changed from

==========
[turbofan] Let ChangeFloat64ToTagged canonicalize to Smi if possible.

When the incoming value to ChangeFloat64ToTagged is in Smi range, we
represent it as Smi instead of a HeapNumber. This addresses a range of
problems where TurboFan unnecessarily deoptimizes because an operation
learned Smi feedback in Ignition, but was then confronted with a tagged
HeapNumber in TurboFan, just because the value was also represented as
unboxed double somewhere in the meantime.

BUG=v8:6256
R=yangguo@chromium.org
==========

to

==========
[turbofan] Let ChangeFloat64ToTagged canonicalize to Smi if possible.

When the incoming value to ChangeFloat64ToTagged is in Smi range, we
represent it as Smi instead of a HeapNumber. This addresses a range of
problems where TurboFan unnecessarily deoptimizes because an operation
learned Smi feedback in Ignition, but was then confronted with a tagged
HeapNumber in TurboFan, just because the value was also represented as
unboxed double somewhere in the meantime.

BUG=v8:6256
R=yangguo@chromium.org

Review-Url: https://codereview.chromium.org/2815283002
Cr-Commit-Position: refs/heads/master@{#44631}
Committed:
https://chromium.googlesource.com/v8/v8/+/385734bf11d3c4529cc30c553eef8c3e0d6...
==========

[commit-bot: I haz the power, 2017-04-13 06:57:11]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/385734bf11d3c4529cc30c553eef8c3e0d6...