Add flag to control number of stack frames collected by profiler

Add flag to control number of stack frames collected by profiler

BUG=
R=asiva@google.com

Committed: https://code.google.com/p/dart/source/detail?r=31924

[siva, 2014-01-16 23:34:23]

lgtm

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.cc
File runtime/vm/profiler.cc (right):

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.cc#n...
runtime/vm/profiler.cc:34: "Maximum number stack frames walked. Minimum 1.");
maybe profile_frames_depth

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.cc#n...
runtime/vm/profiler.cc:41: const int kMinimumFrames = 1;
We probably also want a max (not letting people arbitrarly collect huge stack
frames)

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.cc#n...
runtime/vm/profiler.cc:664: return sizeof(Sample) + (sizeof(intptr_t) *
FLAG_profile_frames);  // NOLINT.
Why did you choose this to be a function instead of just a static variable
instance_size_; that could be initialized in Profiler::InitOnce.

Not sure if all compilers will nicely constant fold the expression.

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.h
File runtime/vm/profiler.h (right):

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.h#ne...
runtime/vm/profiler.h:85: struct Sample {
why not just make it class Sample ?

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.h#ne...
runtime/vm/profiler.h:96: uintptr_t pcs[0];
Document that this needs to be the last field, no fields should be added after
this.

[Cutch, 2014-01-17 16:02:25]

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.cc
File runtime/vm/profiler.cc (right):

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.cc#n...
runtime/vm/profiler.cc:34: "Maximum number stack frames walked. Minimum 1.");
On 2014/01/16 23:34:23, siva wrote:
> maybe profile_frames_depth

profile_depth.

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.cc#n...
runtime/vm/profiler.cc:41: const int kMinimumFrames = 1;
On 2014/01/16 23:34:23, siva wrote:
> We probably also want a max (not letting people arbitrarly collect huge stack
> frames)

Max of 128.

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.cc#n...
runtime/vm/profiler.cc:664: return sizeof(Sample) + (sizeof(intptr_t) *
FLAG_profile_frames);  // NOLINT.
On 2014/01/16 23:34:23, siva wrote:
> Why did you choose this to be a function instead of just a static variable
> instance_size_; that could be initialized in Profiler::InitOnce.
> 
> Not sure if all compilers will nicely constant fold the expression.

Done.

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.h
File runtime/vm/profiler.h (right):

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.h#ne...
runtime/vm/profiler.h:85: struct Sample {
On 2014/01/16 23:34:23, siva wrote:
> why not just make it class Sample ?

Done.

https://codereview.chromium.org/131853007/diff/30001/runtime/vm/profiler.h#ne...
runtime/vm/profiler.h:96: uintptr_t pcs[0];
On 2014/01/16 23:34:23, siva wrote:
> Document that this needs to be the last field, no fields should be added after
> this.

Done.

[Cutch, 2014-01-17 16:32:59]

Committed patchset #3 manually as r31924 (presubmit successful).