Support captured variables in debugger

Support captured variables in debugger

- Add context level ranges to LocalVarDescriptors
- Add callee-saved context chain register to LocalVarDescriptors
- Add context level and context offset of captured variables
  to LocalVarDescriptors
- Add context chain to ActivationFrame
- Add current context level to ActivationFrame
Committed: https://code.google.com/p/dart/source/detail?r=8863

[regis, 2012-06-19 18:14:41]

LGTM

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/debugger.cc
File runtime/vm/debugger.cc (right):

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/debugger.cc#newc...
runtime/vm/debugger.cc:120: desc_indices_(8),
We usually avoid setting an initial size.

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/debugger.cc#newc...
runtime/vm/debugger.cc:293: GrowableArray<String*> var_names(8);
I think we usually avoid setting an initial size (8 here).

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/debugger.h
File runtime/vm/debugger.h (right):

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/debugger.h#newco...
runtime/vm/debugger.h:135: intptr_t ContextLevel();
Add comment explaining what is the context level of an activation frame.
I suppose it is the context level of the call that left this frame?

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/raw_object.h
File runtime/vm/raw_object.h (right):

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/raw_object.h#new...
runtime/vm/raw_object.h:806: static const int8_t kContextChain = 4;
It should not be a problem to use an enum. See enum ClassState and the
corresponding raw field class_state_ as an example.

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/scopes.cc
File runtime/vm/scopes.cc (right):

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/scopes.cc#newcod...
runtime/vm/scopes.cc:224: (!parent()->HasContextLevel()) ||
No indentation needed.

[hausner, 2012-06-19 18:49:41]

Thank you.

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/debugger.cc
File runtime/vm/debugger.cc (right):

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/debugger.cc#newc...
runtime/vm/debugger.cc:120: desc_indices_(8),
On 2012/06/19 18:14:41, regis wrote:
> We usually avoid setting an initial size.

It avoids reallocating a couple of times in the very common case where there are
just a handful of local variables.

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/debugger.cc#newc...
runtime/vm/debugger.cc:293: GrowableArray<String*> var_names(8);
On 2012/06/19 18:14:41, regis wrote:
> I think we usually avoid setting an initial size (8 here).
Same comment as above.

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/debugger.h
File runtime/vm/debugger.h (right):

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/debugger.h#newco...
runtime/vm/debugger.h:135: intptr_t ContextLevel();
On 2012/06/19 18:14:41, regis wrote:
> Add comment explaining what is the context level of an activation frame.
> I suppose it is the context level of the call that left this frame? 
Correct. Added the comment.

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/raw_object.h
File runtime/vm/raw_object.h (right):

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/raw_object.h#new...
runtime/vm/raw_object.h:806: static const int8_t kContextChain = 4;
On 2012/06/19 18:14:41, regis wrote:
> It should not be a problem to use an enum. See enum ClassState and the
> corresponding raw field class_state_ as an example.

Hmm. I started out with an enum and ran into some problem converting between the
enum type and int8_t. I converted to enum again and it's fine now. Strange. In
any case: done.

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/scopes.cc
File runtime/vm/scopes.cc (right):

http://codereview.chromium.org/10579020/diff/3003/runtime/vm/scopes.cc#newcod...
runtime/vm/scopes.cc:224: (!parent()->HasContextLevel()) ||
On 2012/06/19 18:14:41, regis wrote:
> No indentation needed.

Ok. I try to indicate factors and terms by indentation. Removed.