Optimize static field and context load/stores as part of CSE pass.

Optimize static field and context load/stores as part of CSE pass.

This change also introduces basic abstractions for aliasing.

R=srdjan@google.com
BUG=

Committed: https://code.google.com/p/dart/source/detail?r=21866

[srdjan, 2013-04-22 22:00:05]

LGTM

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
File runtime/vm/flow_graph_optimizer.cc (right):

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3074: // if they have the same alias.
Optional: There are various TODO-s which probably will require Alias to become
ZoneAllocated, we could do it now.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3081: // different typed data and normal
arrays.
You could (as TODO) also incorporate the index ranges.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3082: static Alias Indices() {
We are using indexes instead of indeces in the VM.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3133: intptr_t alias_;
const

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3198: bool Contains(Alias alias) {
const

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3203: BitVector* Get(Alias alias) {
const

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3212: sets_.Add(NULL);
indent

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3227: GrowableArray<BitVector*> sets_;
Add comment what sets_ represents.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3256: static inline intptr_t Hashcode(Key
key) {
Why the inline? The code in the body is not that lightweight, it seems to me.

[Vyacheslav Egorov (Google), 2013-04-23 11:00:06]

Thanks for the review. Landing.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
File runtime/vm/flow_graph_optimizer.cc (right):

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3074: // if they have the same alias.
On 2013/04/22 22:00:05, srdjan wrote:
> Optional: There are various TODO-s which probably will require Alias to become
> ZoneAllocated, we could do it now.

I'll keep it ValueObject for now. I don't think it'll becoeme ZoneObject right
away.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3081: // different typed data and normal
arrays.
On 2013/04/22 22:00:05, srdjan wrote:
> You could (as TODO) also incorporate the index ranges.

I have doubts that it's common to have disjoint ranges.

Most ranges would be [0, N] and thus intersect.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3082: static Alias Indices() {
On 2013/04/22 22:00:05, srdjan wrote:
> We are using indexes instead of indeces in the VM.

Done.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3133: intptr_t alias_;
On 2013/04/22 22:00:05, srdjan wrote:
> const

Done.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3198: bool Contains(Alias alias) {
On 2013/04/22 22:00:05, srdjan wrote:
> const

Done.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3203: BitVector* Get(Alias alias) {
On 2013/04/22 22:00:05, srdjan wrote:
> const

Done.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3212: sets_.Add(NULL);
On 2013/04/22 22:00:05, srdjan wrote:
> indent

Done.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3227: GrowableArray<BitVector*> sets_;
On 2013/04/22 22:00:05, srdjan wrote:
> Add comment what sets_ represents.

Done.

https://codereview.chromium.org/14326006/diff/1/runtime/vm/flow_graph_optimiz...
runtime/vm/flow_graph_optimizer.cc:3256: static inline intptr_t Hashcode(Key
key) {
On 2013/04/22 22:00:05, srdjan wrote:
> Why the inline? The code in the body is not that lightweight, it seems to me.

Done.

[Vyacheslav Egorov (Google), 2013-04-23 11:09:44]

Committed patchset #2 manually as r21866 (presubmit successful).