Strengthen type assertions post-dominated by checks during type propagation.

Strengthen type assertions post-dominated by checks during type propagation.

If a type assertion for a value is post-dominated by a class or smi check over the same value then raise the check over the assertion.

This allows to eliminate type assertions in the cases like:

AssertAssignable(x, int)
CheckSmi(x)

Currently post-domination is computed within a single block because post-dominators are not available.

R=fschneider@google.com
BUG=

Committed: https://code.google.com/p/dart/source/detail?r=18777

[Florian Schneider, 2013-02-20 17:57:38]

lgtm

https://codereview.chromium.org/12317013/diff/1/runtime/vm/flow_graph_type_pr...
File runtime/vm/flow_graph_type_propagator.cc (right):

https://codereview.chromium.org/12317013/diff/1/runtime/vm/flow_graph_type_pr...
runtime/vm/flow_graph_type_propagator.cc:233: static AssertAssignableInstr*
kStrengthenedAssertMarker =
does it need to be global?

https://codereview.chromium.org/12317013/diff/1/runtime/vm/flow_graph_type_pr...
runtime/vm/flow_graph_type_propagator.cc:270: 
const AssertAssignableInstr* kStrengthenedAssertMarker = 
    reinterpret_cast<AssertAssignableInstr*>(-1);

https://codereview.chromium.org/12317013/diff/1/runtime/vm/flow_graph_type_pr...
runtime/vm/flow_graph_type_propagator.cc:275: 
You can also use deopt_id() of the AssertAssignableInstr itself. It should
always match the environmnent though. Maybe add here

ASSERT(assert->deopt_id() == assert->env()->deopt_id());

[Vyacheslav Egorov (Google), 2013-02-20 19:35:10]

https://codereview.chromium.org/12317013/diff/1/runtime/vm/flow_graph_type_pr...
File runtime/vm/flow_graph_type_propagator.cc (right):

https://codereview.chromium.org/12317013/diff/1/runtime/vm/flow_graph_type_pr...
runtime/vm/flow_graph_type_propagator.cc:233: static AssertAssignableInstr*
kStrengthenedAssertMarker =
On 2013/02/20 17:57:38, Florian Schneider wrote:
> does it need to be global?

Done.

https://codereview.chromium.org/12317013/diff/1/runtime/vm/flow_graph_type_pr...
runtime/vm/flow_graph_type_propagator.cc:270: 
On 2013/02/20 17:57:38, Florian Schneider wrote:
> const AssertAssignableInstr* kStrengthenedAssertMarker = 
>     reinterpret_cast<AssertAssignableInstr*>(-1);

Done.

https://codereview.chromium.org/12317013/diff/1/runtime/vm/flow_graph_type_pr...
runtime/vm/flow_graph_type_propagator.cc:275: 
On 2013/02/20 17:57:38, Florian Schneider wrote:
> You can also use deopt_id() of the AssertAssignableInstr itself. It should
> always match the environmnent though. Maybe add here
> 
> ASSERT(assert->deopt_id() == assert->env()->deopt_id());

Done.

[Vyacheslav Egorov (Google), 2013-02-20 19:40:41]

Committed manually as r18777 (presubmit successful).