[arm64] Use acquire/release memory accesses for atomics

[arm64] Use acquire/release memory accesses for atomics

Implement ASSEMBLE_ATOMIC_LOAD/STORE_INTEGER using acquire/release instructions,
to match the existing ASSEMBLE_ATOMIC_EXCHANGE_INTEGER macro.

BUG=v8:6097
Review-Url: https://codereview.chromium.org/2760963002
Cr-Commit-Position: refs/heads/master@{#44184}
Committed: https://chromium.googlesource.com/v8/v8/+/630c33c6f48ba3b2da5c38dd894f5155df4c8f3b

[martyn.capewell, 2017-03-20 17:17:56]

martyn.capewell@arm.com changed reviewers:
+ aseemgarg@chromium.org, binji@chromium.org, bmeurer@chromium.org,
jarin@chromium.org

[martyn.capewell, 2017-03-20 17:17:57]

In place of https://codereview.chromium.org/2754543006/ , using acquire/release
on existing atomics instead.

[aseemgarg, 2017-03-20 20:56:47]

https://codereview.chromium.org/2760963002/diff/1/src/compiler/arm64/code-gen...
File src/compiler/arm64/code-generator-arm64.cc (right):

https://codereview.chromium.org/2760963002/diff/1/src/compiler/arm64/code-gen...
src/compiler/arm64/code-generator-arm64.cc:1652:
ASSEMBLE_ATOMIC_STORE_INTEGER(Stlrb);
Is this correct? Since, stlr/b/h is store with release, will it work without
being preceded by a ldar/b/h?
Other than that looks good but someone else will have to l-g-t-m.

[martyn.capewell, 2017-03-21 11:42:40]

Providing that the buffer is only accessed through acquire/release instructions,
we believe it should work fine. From an internal study:

"[In the SMB spec] A set of atomic operations is provided to allow threads to
communicate in a predictable manner. In
particular, an atomic write operation guarantees that all preceding accesses in
the thread (in program
order) are observed by other threads before the atomic write itself."

"Conversely, the specification does not obviously state that the atomic write
must be observed before
operations that follow it (in program order). This is also supported by the
ordering description in
specification itself. As a result, we can safely use ARMv8's acquire-release
semantics here, as long
as we do so consistently."

[martyn.capewell, 2017-03-21 14:49:06]

Description was changed from

==========
[arm64] Use acquire/release memory accesses for atomics

Implement ASSEMBLE_ATOMIC_LOAD/STORE_INTEGER using acquire/release instructions,
to match the existing ASSEMBLE_ATOMIC_EXCHANGE_INTEGER macro.

BUG=
==========

to

==========
[arm64] Use acquire/release memory accesses for atomics

Implement ASSEMBLE_ATOMIC_LOAD/STORE_INTEGER using acquire/release instructions,
to match the existing ASSEMBLE_ATOMIC_EXCHANGE_INTEGER macro.

BUG=v8:6097
==========

[binji, 2017-03-24 20:32:42]

lgtm

[martyn.capewell, 2017-03-27 17:39:52]

The CQ bit was checked by martyn.capewell@arm.com

[commit-bot: I haz the power, 2017-03-27 17:40:03]

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, 2017-03-27 17:42:36]

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

[commit-bot: I haz the power, 2017-03-27 17:42:37]

Try jobs failed on following builders:
  v8_presubmit on master.tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/37741)

[Benedikt Meurer, 2017-03-28 04:28:01]

LGTM (rubber-stamped)

[martyn.capewell, 2017-03-28 09:44:46]

The CQ bit was checked by martyn.capewell@arm.com

[commit-bot: I haz the power, 2017-03-28 09:44:56]

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, 2017-03-28 10:06:59]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1490694286453840, "parent_rev":
"88a7061a53ad200121f7ee2b2bdcc05d793de806", "commit_rev":
"630c33c6f48ba3b2da5c38dd894f5155df4c8f3b"}

[commit-bot: I haz the power, 2017-03-28 10:07:05]

Description was changed from

==========
[arm64] Use acquire/release memory accesses for atomics

Implement ASSEMBLE_ATOMIC_LOAD/STORE_INTEGER using acquire/release instructions,
to match the existing ASSEMBLE_ATOMIC_EXCHANGE_INTEGER macro.

BUG=v8:6097
==========

to

==========
[arm64] Use acquire/release memory accesses for atomics

Implement ASSEMBLE_ATOMIC_LOAD/STORE_INTEGER using acquire/release instructions,
to match the existing ASSEMBLE_ATOMIC_EXCHANGE_INTEGER macro.

BUG=v8:6097

Review-Url: https://codereview.chromium.org/2760963002
Cr-Commit-Position: refs/heads/master@{#44184}
Committed:
https://chromium.googlesource.com/v8/v8/+/630c33c6f48ba3b2da5c38dd894f5155df4...
==========

[commit-bot: I haz the power, 2017-03-28 10:07:06]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/630c33c6f48ba3b2da5c38dd894f5155df4...