1. Add flag --trace-api to trace API function invocation

1. Add flag --trace-api to trace API function invocation
2. Add tracing of external native functions under --trace-natives flag
3. Added a _printCurrentStacktrace() function so that one could get a
   dart stack trace under 'gdb' when in a native or runtime function.

R=regis@google.com

Committed: https://code.google.com/p/dart/source/detail?r=27166

[regis, 2013-09-04 23:05:14]

LGTM

https://codereview.chromium.org/23453035/diff/1/runtime/vm/dart_api_impl.cc
File runtime/vm/dart_api_impl.cc (right):

https://codereview.chromium.org/23453035/diff/1/runtime/vm/dart_api_impl.cc#n...
runtime/vm/dart_api_impl.cc:41: DEFINE_FLAG(bool, trace_api, false, "Trace
invocation of API calls");
should you add "(debug mode only)"?

https://codereview.chromium.org/23453035/diff/1/runtime/vm/dart_api_impl.cc#n...
runtime/vm/dart_api_impl.cc:312: DART_EXPORT const char*
Dart_GetError(Dart_Handle handle) {
You did not add TRACE_API_CALLS here or to the functions below. Is there a
reason?

https://codereview.chromium.org/23453035/diff/1/runtime/vm/dart_api_impl.h
File runtime/vm/dart_api_impl.h (right):

https://codereview.chromium.org/23453035/diff/1/runtime/vm/dart_api_impl.h#ne...
runtime/vm/dart_api_impl.h:27: #define TRACE_API_CALLS(name)                    
                             \
Should it be TRACE_API_CALL(name), since you use it for a single call at a time?

https://codereview.chromium.org/23453035/diff/1/runtime/vm/native_arguments.h
File runtime/vm/native_arguments.h (right):

https://codereview.chromium.org/23453035/diff/1/runtime/vm/native_arguments.h...
runtime/vm/native_arguments.h:51: #define TRACE_NATIVES(format, name)           
                                \
TRACE_NATIVE_CALL for symmetry with TRACE_API_CALL?
OK, the flags are not symmetric.

[siva, 2013-09-04 23:27:42]

https://codereview.chromium.org/23453035/diff/1/runtime/vm/dart_api_impl.cc
File runtime/vm/dart_api_impl.cc (right):

https://codereview.chromium.org/23453035/diff/1/runtime/vm/dart_api_impl.cc#n...
runtime/vm/dart_api_impl.cc:41: DEFINE_FLAG(bool, trace_api, false, "Trace
invocation of API calls");
On 2013/09/04 23:05:15, regis wrote:
> should you add "(debug mode only)"?

Done.

https://codereview.chromium.org/23453035/diff/1/runtime/vm/dart_api_impl.cc#n...
runtime/vm/dart_api_impl.cc:312: DART_EXPORT const char*
Dart_GetError(Dart_Handle handle) {
Most of these functions have DARTISOLATE or CHECK_ISOLATE in the code and I
added TRACE_API_CALLS to these macros.

On 2013/09/04 23:05:15, regis wrote:
> You did not add TRACE_API_CALLS here or to the functions below. Is there a
> reason?

https://codereview.chromium.org/23453035/diff/1/runtime/vm/dart_api_impl.h
File runtime/vm/dart_api_impl.h (right):

https://codereview.chromium.org/23453035/diff/1/runtime/vm/dart_api_impl.h#ne...
runtime/vm/dart_api_impl.h:27: #define TRACE_API_CALLS(name)                    
                             \
On 2013/09/04 23:05:15, regis wrote:
> Should it be TRACE_API_CALL(name), since you use it for a single call at a
time?

Done.

https://codereview.chromium.org/23453035/diff/1/runtime/vm/native_arguments.h
File runtime/vm/native_arguments.h (right):

https://codereview.chromium.org/23453035/diff/1/runtime/vm/native_arguments.h...
runtime/vm/native_arguments.h:51: #define TRACE_NATIVES(format, name)           
                                \
Changed the name to TRACE_NATIVE_CALL

On 2013/09/04 23:05:15, regis wrote:
> TRACE_NATIVE_CALL for symmetry with TRACE_API_CALL?
> OK, the flags are not symmetric.

[siva, 2013-09-04 23:42:17]

Committed patchset #2 manually as r27166 (presubmit successful).