Fix bugs in load elimination and type propagation.

Fix bugs in load elimination and type propagation.

Load elimination should consider the representation of loads/stores
when numbering places. Different representations result now in different
places so that there can't be mixed representations at phis after
load elimination.

Removed the flag --propagate-types because type propagation is required
for correctness of smi-check hoisting. Therefore, switching it off does not
 make sense anymore.

BUG=https://code.google.com/p/dart/issues/detail?id=6663, https://code.google.com/p/dart/issues/detail?id=14271
R=kmillikin@google.com

Committed: https://code.google.com/p/dart/source/detail?r=28931

[Kevin Millikin (Google), 2013-10-21 13:05:23]

LGTM, with one comment.

https://codereview.chromium.org/28633003/diff/70001/runtime/vm/flow_graph_typ...
File runtime/vm/flow_graph_type_propagator.cc (right):

https://codereview.chromium.org/28633003/diff/70001/runtime/vm/flow_graph_typ...
runtime/vm/flow_graph_type_propagator.cc:24:
DEBUG_ASSERT(flow_graph->VerifyUseLists());
Except for a couple instances during inlining, all other calls to VerifyUseLists
are in compiler.cc.  We did that by design so it would be easy to see which
passes preserved use lists (though most of them do).

I sort of like to keep it that way, also because it flags places where the graph
can change and makes it easy to see that we have verification code everywhere.

[Florian Schneider, 2013-10-21 13:30:04]

https://codereview.chromium.org/28633003/diff/70001/runtime/vm/flow_graph_typ...
File runtime/vm/flow_graph_type_propagator.cc (right):

https://codereview.chromium.org/28633003/diff/70001/runtime/vm/flow_graph_typ...
runtime/vm/flow_graph_type_propagator.cc:24:
DEBUG_ASSERT(flow_graph->VerifyUseLists());
On 2013/10/21 13:05:23, kmillikin wrote:
> Except for a couple instances during inlining, all other calls to
VerifyUseLists
> are in compiler.cc.  We did that by design so it would be easy to see which
> passes preserved use lists (though most of them do).
> 
> I sort of like to keep it that way, also because it flags places where the
graph
> can change and makes it easy to see that we have verification code everywhere.

Done.

[Florian Schneider, 2013-10-21 14:00:03]

Committed patchset #2 manually as r28931 (presubmit successful).

[srdjan, 2013-10-21 17:42:34]

https://codereview.chromium.org/28633003/diff/70001/runtime/vm/flow_graph_opt...
File runtime/vm/flow_graph_optimizer.cc (right):

https://codereview.chromium.org/28633003/diff/70001/runtime/vm/flow_graph_opt...
runtime/vm/flow_graph_optimizer.cc:4165: representation_ =
store_instance_field->RequiredInputRepresentation(1);
Please factor repeated use of 0, 1 and 2 into constants.