Oilpan: Always enter a GCScope when we run a GC

Oilpan: Always enter a GCScope when we run a GC

Currently a thread-termination GC doesn't enter a GCScope but
I want to make sure that we always enter a GCScope (which keeps track of
the status of the current GC) when we run a GC. This CL makes
a thread-termination GC enter a GCScope.

This is a preparation for landing https://codereview.chromium.org/1159773004/

BUG=490087
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=196155

[haraken, 2015-05-29 10:49:48]

haraken@chromium.org changed reviewers:
+ oilpan-reviews@chromium.org, sigbjornf@opera.com

[haraken, 2015-05-29 10:49:48]

PTAL

Maybe you can land https://codereview.chromium.org/1145423009/ first.

[sof, 2015-05-29 10:55:35]

On 2015/05/29 10:49:48, haraken wrote:
> PTAL
> 
> Maybe you can land https://codereview.chromium.org/1145423009/ first.

I've painted myself into a corner wrt
https://code.google.com/p/chromium/issues/detail?id=487952#c9 , so landing it
will have to wait.

[sof, 2015-05-29 13:14:07]

https://codereview.chromium.org/1160143002/diff/20001/Source/platform/heap/He...
File Source/platform/heap/Heap.cpp (right):

https://codereview.chromium.org/1160143002/diff/20001/Source/platform/heap/He...
Source/platform/heap/Heap.cpp:133: // FIXME: in an unlikely coincidence that two
threads decide
nit: s/FIXME/TODO/

https://codereview.chromium.org/1160143002/diff/20001/Source/platform/heap/He...
Source/platform/heap/Heap.cpp:1986: GCScope
gcScope(ThreadState::NoHeapPointersOnStack, ThreadState::ThreadTerminationGC);
Just to make sure I understand motivation -- this GCScope will provide some
value once GCScope starts flagging GCForbidden? It doesn't do much now apart
from a trace call on enter.

[haraken, 2015-05-29 14:42:27]

https://codereview.chromium.org/1160143002/diff/20001/Source/platform/heap/He...
File Source/platform/heap/Heap.cpp (right):

https://codereview.chromium.org/1160143002/diff/20001/Source/platform/heap/He...
Source/platform/heap/Heap.cpp:133: // FIXME: in an unlikely coincidence that two
threads decide
On 2015/05/29 13:14:07, sof wrote:
> nit: s/FIXME/TODO/

Done.

https://codereview.chromium.org/1160143002/diff/20001/Source/platform/heap/He...
Source/platform/heap/Heap.cpp:1986: GCScope
gcScope(ThreadState::NoHeapPointersOnStack, ThreadState::ThreadTerminationGC);
On 2015/05/29 13:14:07, sof wrote:
> Just to make sure I understand motivation -- this GCScope will provide some
> value once GCScope starts flagging GCForbidden? It doesn't do much now apart
> from a trace call on enter.

Sorry for not being clear.

I want to implement GCScope::current()->gcType() in pushXXXCallbacks() to know
the type of a GC that the GCing thread is currently doing. To let
GCScope::current() return the current GCScope, we need to make sure that all GCs
enter a GCScope.

[sof, 2015-05-29 14:44:15]

thanks for clarifying, lgtm.

[haraken, 2015-05-29 14:45:40]

The CQ bit was checked by haraken@chromium.org

[commit-bot: I haz the power, 2015-05-29 14:46:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1160143002/40001

[commit-bot: I haz the power, 2015-05-29 15:53:45]

Committed patchset #3 (id:40001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=196155