Use Dart stack walker when we have an exit frame.

Use Dart stack walker when we have an exit frame.

This makes the profiler more Dart developer friendly (but less VM developer friendly).

Also, fixes a bug where the top exit frame info would be invalid after an exception occurs.

The flag: --profile-vm allows for profiling of VM internals.

R=asiva@google.com

Committed: https://code.google.com/p/dart/source/detail?r=37767

[siva, 2014-06-19 20:22:17]

lgtm

https://codereview.chromium.org/341083002/diff/1/runtime/vm/profiler.cc
File runtime/vm/profiler.cc (right):

https://codereview.chromium.org/341083002/diff/1/runtime/vm/profiler.cc#newco...
runtime/vm/profiler.cc:1863: }
Should there be an UNREACHEABLE() here, i.e you do not expect to record samples
before the stub code has been generated for the isolate.

[Cutch, 2014-06-23 17:30:12]

https://codereview.chromium.org/341083002/diff/1/runtime/vm/profiler.cc
File runtime/vm/profiler.cc (right):

https://codereview.chromium.org/341083002/diff/1/runtime/vm/profiler.cc#newco...
runtime/vm/profiler.cc:1863: }
On 2014/06/19 20:22:17, siva wrote:
> Should there be an UNREACHEABLE() here, i.e you do not expect to record
samples
> before the stub code has been generated for the isolate.

We want to collect samples during isolate start up.

[siva, 2014-06-26 20:45:00]

lgtm

[Cutch, 2014-06-26 22:06:39]

Committed patchset #4 manually as r37767 (presubmit successful).