Mirrors memory usage tweaks.

Mirrors memory usage tweaks.

- Don't build and cache vestigial members/constructors maps.
- Avoid creating multiple LibraryMirrors for the same library.
- Store infrequently used method flags as a bitfield.
- Don't cache MethodMirror source.

mirrors_reader_test final heap size: 10.8 -> 8.9 MB (-17.5%)
mirrors_reader_test time: 1.55 -> 1.33 seconds (-14.2%)

R=asiva@google.com

Committed: https://code.google.com/p/dart/source/detail?r=45352

[rmacnak, 2015-04-21 22:27:23]

rmacnak@google.com changed reviewers:
+ asiva@google.com

[siva, 2015-04-22 00:00:47]

LGTM with one comment.

https://codereview.chromium.org/1080393006/diff/1/runtime/lib/mirrors.cc
File runtime/lib/mirrors.cc (right):

https://codereview.chromium.org/1080393006/diff/1/runtime/lib/mirrors.cc#newc...
runtime/lib/mirrors.cc:255: // These offsets much be kept in sync with those in
mirrors_impl.dart.
Can you declare some constants in mirrors_impl.dart and assert that these values
match some constants here during start up.
Something similar to ClassFinalizer::VerifyImplicitFieldOffsets()

[rmacnak, 2015-04-22 17:09:02]

https://codereview.chromium.org/1080393006/diff/1/runtime/lib/mirrors.cc
File runtime/lib/mirrors.cc (right):

https://codereview.chromium.org/1080393006/diff/1/runtime/lib/mirrors.cc#newc...
runtime/lib/mirrors.cc:255: // These offsets much be kept in sync with those in
mirrors_impl.dart.
On 2015/04/22 00:00:47, siva wrote:
> Can you declare some constants in mirrors_impl.dart and assert that these
values
> match some constants here during start up.
> Something similar to ClassFinalizer::VerifyImplicitFieldOffsets()

Added debug-only hook in CreateMirrorSystem, which will run during about half of
the mirror tests. PTAL

[siva, 2015-04-22 17:32:55]

still LGTM.

https://codereview.chromium.org/1080393006/diff/100001/runtime/lib/mirrors.cc
File runtime/lib/mirrors.cc (right):

https://codereview.chromium.org/1080393006/diff/100001/runtime/lib/mirrors.cc...
runtime/lib/mirrors.cc:566: }
Not sure if linker optimizes out empty static methods, maybe more size friendly
to do
#ifdef DEBUG
static void VerifyMethodKindShifts() }
....
....
}
#endif

static RawInstance* CreateMirrorSysmte() {
#ifdef DEBUG
  VerifyMethodKindShifts();
#endif
  ...
  ...
}

[rmacnak, 2015-04-22 17:51:41]

https://codereview.chromium.org/1080393006/diff/100001/runtime/lib/mirrors.cc
File runtime/lib/mirrors.cc (right):

https://codereview.chromium.org/1080393006/diff/100001/runtime/lib/mirrors.cc...
runtime/lib/mirrors.cc:566: }
On 2015/04/22 17:32:55, siva wrote:
> Not sure if linker optimizes out empty static methods, maybe more size
friendly
> to do
> #ifdef DEBUG
> static void VerifyMethodKindShifts() }
> ....
> ....
> }
> #endif
> 
> static RawInstance* CreateMirrorSysmte() {
> #ifdef DEBUG
>   VerifyMethodKindShifts();
> #endif
>   ...
>   ...
> }

gcc and clang drop it at -O1. The compiler can drop it even before linking.

[rmacnak, 2015-04-22 17:51:57]

Committed patchset #7 (id:120001) manually as 45352 (presubmit successful).