Take representation into account in ConstantPropagator::VisitInstanceOfInstr

Take representation into account in ConstantPropagator::VisitInstanceOfInstr

BUG=
R=fschneider@google.com, srdjan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=30012

[Cutch, 2013-10-01 21:23:30]

Related to https://code.google.com/p/dart/issues/detail?id=12417

Need to figure out this failure:
=== Failure summary:


FAILED: none-vm debug_ia32 lib/math/min_max_test
Expected: Pass 
Actual: Crash
CommandOutput[vm]:

stderr:
runtime/vm/flow_graph_optimizer.cc:6972: error: expected:
reachable_->Contains(if_false->preorder_number())


Command[vm]: out/DebugIA32/dart --optimization-counter-threshold=10
--ignore-unrecognized-flags --package-root=out/DebugIA32/packages/
/usr/local/google/home/johnmccutchan/workspace/dart-repo/dart/tests/lib/math/min_max_test.dart
Took 0:00:00.492000

Short reproduction command (experimental):
    python tools/test.py -t120 lib/math/min_max_test



===
=== 1 test failed
===

[Cutch, 2013-10-01 23:53:52]

Hi Florian,

After discussing with Srdjan I will take a different approach to this. I'll ping
the CL when it is ready.

[Cutch, 2013-10-02 18:33:38]

PTAL.

[srdjan, 2013-10-02 21:07:49]

lgtm

[Cutch, 2013-10-02 22:15:05]

Florian?

[Florian Schneider, 2013-10-03 09:06:55]

LGTM with a suggested improvement.

https://codereview.chromium.org/25604003/diff/10001/runtime/vm/flow_graph_opt...
File runtime/vm/flow_graph_optimizer.cc (right):

https://codereview.chromium.org/25604003/diff/10001/runtime/vm/flow_graph_opt...
runtime/vm/flow_graph_optimizer.cc:6336: // The representation guarantees the
type check to be true.
Maybe add an ASSERT that the compile-type of instr->value()->Type() matches with
the representation.

You could also use the type here - it should be slightly more general - i.e.
type checks on boxed values with a known type could be optimized as well: e.g.
smis

[Cutch, 2013-11-06 23:04:42]

https://codereview.chromium.org/25604003/diff/10001/runtime/vm/flow_graph_opt...
File runtime/vm/flow_graph_optimizer.cc (right):

https://codereview.chromium.org/25604003/diff/10001/runtime/vm/flow_graph_opt...
runtime/vm/flow_graph_optimizer.cc:6336: // The representation guarantees the
type check to be true.
On 2013/10/03 09:06:55, Florian Schneider wrote:
> Maybe add an ASSERT that the compile-type of instr->value()->Type() matches
with
> the representation.
> 

Done.

> You could also use the type here - it should be slightly more general - i.e.
> type checks on boxed values with a known type could be optimized as well: e.g.
> smis

I'll save that for a follow up CL.

[Cutch, 2013-11-06 23:48:05]

Committed patchset #3 manually as r30012 (presubmit successful).