[wasm] Use weak reference for wasm deopt data.

[wasm] Use weak reference for wasm deopt data.

This unblocks moving off having to hold on to a compiled module
template.

Once we don't have the template, when we have a single instance, the
instance and wasm module share the same compiled code. We will want
to clear that code off instance-specific stuff, when the instance is
unreferenced and should be GC-ed (stuff like the instance heap, for
instance). However, the deopt data will maintain a strong reference,
blocking the GC: the module object strongly references the compiled
code, which strongly references the instance object through the deopt
data.

This change addresses that by making that last reference weak.

BUG=v8:5316
Committed: https://crrev.com/b9eb9ee779c1b5cfa464a10f2c5ba6e16524bbae
Cr-Commit-Position: refs/heads/master@{#38990}

[Mircea Trofin, 2016-08-28 03:17:22]

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

[commit-bot: I haz the power, 2016-08-28 03:17:24]

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

[Mircea Trofin, 2016-08-28 03:32:16]

Description was changed from

==========
[wasm] Use weak reference for wasm deopt data.

This unblocks moving off having to hold on to a compiled module
template.

Once we don't have the template, when we have a single instance, the
instance and wasm module share the same compiled code. We will want to
clear that code off instance-specific stuff, when the instance is
unreferenced and should be GC-ed (stuff like the instance heap, for
instance). However, the deopt data will maintain a strong reference,
blocking the GC: the module object strongly references the compiled
code, which strongly references the instance object through the deopt
data.

This change addresses that by making that last reference weak.

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

to

==========
[wasm] Use weak reference for wasm deopt data.

This unblocks moving off having to hold on to a compiled module
template.

Once we don't have the template, when we have a single instance, the
instance and wasm module share the same compiled code. We will want 
to clear that code off instance-specific stuff, when the instance is
unreferenced and should be GC-ed (stuff like the instance heap, for
instance). However, the deopt data will maintain a strong reference,
blocking the GC: the module object strongly references the compiled
code, which strongly references the instance object through the deopt
data.

This change addresses that by making that last reference weak.

BUG=v8:5316
==========

[Mircea Trofin, 2016-08-28 03:32:16]

mtrofin@chromium.org changed reviewers:
+ bradnelson@chromium.org, gdeepti@chromium.org

[Mircea Trofin, 2016-08-28 03:43:54]

PTAL

[commit-bot: I haz the power, 2016-08-28 04:07:57]

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

[commit-bot: I haz the power, 2016-08-28 04:07:58]

Dry run: This issue passed the CQ dry run.

[bradnelson, 2016-08-29 19:09:48]

https://codereview.chromium.org/2284683005/diff/1/src/wasm/wasm-module.cc
File src/wasm/wasm-module.cc (right):

https://codereview.chromium.org/2284683005/diff/1/src/wasm/wasm-module.cc#new...
src/wasm/wasm-module.cc:147: Object* GetOwningWasmInstance(Object* undefined,
Code* code) {
Why pass undefined in instead of the isolate?

[Mircea Trofin, 2016-08-29 19:12:22]

https://codereview.chromium.org/2284683005/diff/1/src/wasm/wasm-module.cc
File src/wasm/wasm-module.cc (right):

https://codereview.chromium.org/2284683005/diff/1/src/wasm/wasm-module.cc#new...
src/wasm/wasm-module.cc:147: Object* GetOwningWasmInstance(Object* undefined,
Code* code) {
On 2016/08/29 19:09:48, bradnelson wrote:
> Why pass undefined in instead of the isolate?

Because undefined is the only needed value, rather than the whole Isolate. I
suppose Isolate would be more in-
tune with the pattern used elsewhere?

[bradn, 2016-08-29 19:22:38]

bradnelson@google.com changed reviewers:
+ bradnelson@google.com

[bradn, 2016-08-29 19:22:38]

I suppose.
Ok. lgtm

[bradnelson, 2016-08-29 19:24:09]

lgtm from right account

[bradnelson, 2016-08-29 19:24:11]

lgtm from right account

[Mircea Trofin, 2016-08-29 19:49:12]

The CQ bit was checked by mtrofin@chromium.org

[commit-bot: I haz the power, 2016-08-29 19:49:21]

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 20:13:33]

Description was changed from

==========
[wasm] Use weak reference for wasm deopt data.

This unblocks moving off having to hold on to a compiled module
template.

Once we don't have the template, when we have a single instance, the
instance and wasm module share the same compiled code. We will want 
to clear that code off instance-specific stuff, when the instance is
unreferenced and should be GC-ed (stuff like the instance heap, for
instance). However, the deopt data will maintain a strong reference,
blocking the GC: the module object strongly references the compiled
code, which strongly references the instance object through the deopt
data.

This change addresses that by making that last reference weak.

BUG=v8:5316
==========

to

==========
[wasm] Use weak reference for wasm deopt data.

This unblocks moving off having to hold on to a compiled module
template.

Once we don't have the template, when we have a single instance, the
instance and wasm module share the same compiled code. We will want 
to clear that code off instance-specific stuff, when the instance is
unreferenced and should be GC-ed (stuff like the instance heap, for
instance). However, the deopt data will maintain a strong reference,
blocking the GC: the module object strongly references the compiled
code, which strongly references the instance object through the deopt
data.

This change addresses that by making that last reference weak.

BUG=v8:5316
==========

[commit-bot: I haz the power, 2016-08-29 20:13:35]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-29 20:13:58]

Description was changed from

==========
[wasm] Use weak reference for wasm deopt data.

This unblocks moving off having to hold on to a compiled module
template.

Once we don't have the template, when we have a single instance, the
instance and wasm module share the same compiled code. We will want 
to clear that code off instance-specific stuff, when the instance is
unreferenced and should be GC-ed (stuff like the instance heap, for
instance). However, the deopt data will maintain a strong reference,
blocking the GC: the module object strongly references the compiled
code, which strongly references the instance object through the deopt
data.

This change addresses that by making that last reference weak.

BUG=v8:5316
==========

to

==========
[wasm] Use weak reference for wasm deopt data.

This unblocks moving off having to hold on to a compiled module
template.

Once we don't have the template, when we have a single instance, the
instance and wasm module share the same compiled code. We will want
to clear that code off instance-specific stuff, when the instance is
unreferenced and should be GC-ed (stuff like the instance heap, for
instance). However, the deopt data will maintain a strong reference,
blocking the GC: the module object strongly references the compiled
code, which strongly references the instance object through the deopt
data.

This change addresses that by making that last reference weak.

BUG=v8:5316

Committed: https://crrev.com/b9eb9ee779c1b5cfa464a10f2c5ba6e16524bbae
Cr-Commit-Position: refs/heads/master@{#38990}
==========

[commit-bot: I haz the power, 2016-08-29 20:13:59]

Patchset 1 (id:??) landed as
https://crrev.com/b9eb9ee779c1b5cfa464a10f2c5ba6e16524bbae
Cr-Commit-Position: refs/heads/master@{#38990}