Teach LoadOptimizer to interblock multi-indirection redundancies in one pass.

Teach LoadOptimizer to handle intrablock multi-indirection redundancies in one pass.

Do this by renumbering loads as we move forward.

R=fschneider@google.com
BUG=

Committed: https://code.google.com/p/dart/source/detail?r=41779

[Florian Schneider, 2014-11-17 12:46:03]

lgtm

https://codereview.chromium.org/728863005/diff/1/runtime/vm/flow_graph_optimi...
File runtime/vm/flow_graph_optimizer.cc (right):

https://codereview.chromium.org/728863005/diff/1/runtime/vm/flow_graph_optimi...
runtime/vm/flow_graph_optimizer.cc:5644: bool IsStore(Instruction* instr,
BitVector** killed) {
The name is a little misleading since this method has multiple side-effects:

For stores it updates the killed bit-vector, for loads it may re-number the
place-id.

Or maybe pass a Place computed outside in and have a AliasedSet::HandleStore and
and HandleLoad method?

[Vyacheslav Egorov (Google), 2014-11-17 15:34:32]

Committed patchset #1 (id:1) manually as 41779 (presubmit successful).