[csa] micro-optimization of Allocation

[csa] micro-optimization of Allocation

Instead of loading the address both the limit and top pointers, rely on the
property that the limit pointer is always directly after the top pointer so that
it can be loaded with the limit pointer's address plus a fixed offset.

This generates smaller code and reduces the number of registers required by the
allocation sequence by one.

LOG=N
R=epertoso@chromium.org

Review-Url: https://codereview.chromium.org/2605043002
Cr-Commit-Position: refs/heads/master@{#41975}
Committed: https://chromium.googlesource.com/v8/v8/+/133b8dfa198d9a340a160e08001e8857a63b74f9

[danno, 2016-12-28 15:53:49]

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

[commit-bot: I haz the power, 2016-12-28 15:53:56]

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

[danno, 2016-12-28 15:54:31]

ptal

[epertoso, 2016-12-28 15:59:10]

Neat, lgtm.

[commit-bot: I haz the power, 2016-12-28 16:18:14]

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

[commit-bot: I haz the power, 2016-12-28 16:18:15]

Dry run: This issue passed the CQ dry run.

[danno, 2016-12-28 16:22:24]

The CQ bit was checked by danno@chromium.org

[commit-bot: I haz the power, 2016-12-28 16:22:35]

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, 2016-12-28 16:24:09]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1482942144350300, "parent_rev":
"1d96354714bda107bfef69fbbc1f0ee8f91fe6df", "commit_rev":
"133b8dfa198d9a340a160e08001e8857a63b74f9"}

[commit-bot: I haz the power, 2016-12-28 16:24:13]

Description was changed from

==========
[csa] micro-optimization of Allocation

Instead of loading the address both the limit and top pointers, rely on the
property that the limit pointer is always directly after the top pointer so that
it can be loaded with the limit pointer's address plus a fixed offset.

This generates smaller code and reduces the number of registers required by the
allocation sequence by one.

LOG=N
R=epertoso@chromium.org
==========

to

==========
[csa] micro-optimization of Allocation

Instead of loading the address both the limit and top pointers, rely on the
property that the limit pointer is always directly after the top pointer so that
it can be loaded with the limit pointer's address plus a fixed offset.

This generates smaller code and reduces the number of registers required by the
allocation sequence by one.

LOG=N
R=epertoso@chromium.org

Review-Url: https://codereview.chromium.org/2605043002
Cr-Commit-Position: refs/heads/master@{#41975}
Committed:
https://chromium.googlesource.com/v8/v8/+/133b8dfa198d9a340a160e08001e8857a63...
==========

[commit-bot: I haz the power, 2016-12-28 16:24:15]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/133b8dfa198d9a340a160e08001e8857a63...