Fix allocation stub switching

Fix allocation stub switching

- When disabling the allocation stub for a class, patch the stub so that the next caller will regenerate the stub.
- Use allocation profiling to test that stub switching and regeneration works.

R=koda@google.com

Committed: https://github.com/dart-lang/sdk/commit/48dfce84b1328c156c93ebb652557ad5a7fbbfa1

[Cutch, 2015-06-26 16:20:02]

johnmccutchan@google.com changed reviewers:
+ koda@google.com, srdjan@google.com

[koda, 2015-06-26 16:58:55]

LGTM

I will think about how to improve compiler_test.cc:RegenerateAllocStubs, which
currently doesn't verify much at all. (It's a bit tricky to do it black-box,
since opt/unopt should not have side-effects.)

[srdjan, 2015-06-26 18:12:36]

https://chromiumcodereview.appspot.com/1215773002/diff/1/runtime/vm/profiler_...
File runtime/vm/profiler_test.cc (right):

https://chromiumcodereview.appspot.com/1215773002/diff/1/runtime/vm/profiler_...
runtime/vm/profiler_test.cc:205: 
I would also add a simpler test in object_test.cc: Run allocating code once,
then patch/disable the allocation stub and then run again.

[Cutch, 2015-06-26 19:24:00]

https://chromiumcodereview.appspot.com/1215773002/diff/1/runtime/vm/profiler_...
File runtime/vm/profiler_test.cc (right):

https://chromiumcodereview.appspot.com/1215773002/diff/1/runtime/vm/profiler_...
runtime/vm/profiler_test.cc:205: 
On 2015/06/26 18:12:36, srdjan wrote:
> I would also add a simpler test in object_test.cc: Run allocating code once,
> then patch/disable the allocation stub and then run again.

There is already one: 'RegenerateAllocStubs'

[Cutch, 2015-06-26 19:36:00]

Committed patchset #2 (id:20001) manually as
48dfce84b1328c156c93ebb652557ad5a7fbbfa1 (presubmit successful).