Generalize if-conversion to arbitrary smi comparisons.

Generalize if-conversion to arbitrary smi comparisons.

Until now only == and != comparisons were supported.

Further changes are:
 Remove flag FLAG_new_identity_spec: It is not needed anymore.
 Invoke Canonicalize another time before branch optimizations.
 Fixes support for TestSmiInstr with the branch-simplifier pass.

R=kmillikin@google.com

Committed: https://code.google.com/p/dart/source/detail?r=30622

[Kevin Millikin (Google), 2013-11-22 14:09:33]

LGTM.

https://codereview.chromium.org/78733002/diff/120001/runtime/vm/compiler.cc
File runtime/vm/compiler.cc (right):

https://codereview.chromium.org/78733002/diff/120001/runtime/vm/compiler.cc#n...
runtime/vm/compiler.cc:374: // Invoke Canonicalize twice in order to fully
canonicalize certains
certains ==> certain, or just get rid of it because it's a noise word.

https://codereview.chromium.org/78733002/diff/120001/runtime/vm/flow_graph_bu...
File runtime/vm/flow_graph_builder.cc (right):

https://codereview.chromium.org/78733002/diff/120001/runtime/vm/flow_graph_bu...
runtime/vm/flow_graph_builder.cc:3098: const bool needs_number_check = false;
I guess it's a matter of taste, but this naming scheme sounds like it does need
a number check at the call site.

I prefer to emphasize the const-ness and create a pseudo enum here:

const bool kNoNumberCheck = false;
...

Or you could create a genuine enum.

https://codereview.chromium.org/78733002/diff/120001/runtime/vm/flow_graph_op...
File runtime/vm/flow_graph_optimizer.cc (right):

https://codereview.chromium.org/78733002/diff/120001/runtime/vm/flow_graph_op...
runtime/vm/flow_graph_optimizer.cc:6281: ASSERT(value.IsBool());
Probably should assert that it's also not IsNull()?

[Florian Schneider, 2013-11-25 13:02:05]

Committed patchset #3 manually as r30622 (presubmit successful).