Add new style of string interpolation optimization: new nodes, working constant folding.

Add new style of string interpolation optimization: new nodes, working constant folding.
TODO: partial constant fold of incoming arguments.

R=kmillikin@google.com

Committed: https://code.google.com/p/dart/source/detail?r=28741

[Kevin Millikin (Google), 2013-10-16 15:14:03]

LGTM.

https://codereview.chromium.org/27192005/diff/74001/runtime/vm/flow_graph_opt...
File runtime/vm/flow_graph_optimizer.cc (right):

https://codereview.chromium.org/27192005/diff/74001/runtime/vm/flow_graph_opt...
runtime/vm/flow_graph_optimizer.cc:6232: //   v8 <- StaticCall(_interpolate, v2)
This is not StaticCall anymore.

https://codereview.chromium.org/27192005/diff/74001/runtime/vm/flow_graph_opt...
runtime/vm/flow_graph_optimizer.cc:6247: SetValue(instr,
store->value()->definition()->constant_value());
This is the only place where we potentially call SetValue(instr,
unknown_constant_).  We avoid that elsewhere because we don't want to ever move
down the lattice --- we should only call that if it is already unknown_constant.

Maybe we should rewrite here to something like:

const Object& value = ...
if (IsNonConstant(value)) {
  SetValue(instr, non_constant_);
  return;
} else if (IsUnknown(value)) {
  ASSERT(IsUnknown(instr));
  return;
}

https://codereview.chromium.org/27192005/diff/74001/runtime/vm/intermediate_l...
File runtime/vm/intermediate_language.h (right):

https://codereview.chromium.org/27192005/diff/74001/runtime/vm/intermediate_l...
runtime/vm/intermediate_language.h:3665: virtual bool CanDeoptimize() const {
return true; }
Really?

[srdjan, 2013-10-16 17:46:37]

Thanks!

https://codereview.chromium.org/27192005/diff/74001/runtime/vm/flow_graph_opt...
File runtime/vm/flow_graph_optimizer.cc (right):

https://codereview.chromium.org/27192005/diff/74001/runtime/vm/flow_graph_opt...
runtime/vm/flow_graph_optimizer.cc:6232: //   v8 <- StaticCall(_interpolate, v2)
On 2013/10/16 15:14:03, kmillikin wrote:
> This is not StaticCall anymore.

v8 <- StringInterpolate(v2)

https://codereview.chromium.org/27192005/diff/74001/runtime/vm/flow_graph_opt...
runtime/vm/flow_graph_optimizer.cc:6247: SetValue(instr,
store->value()->definition()->constant_value());
On 2013/10/16 15:14:03, kmillikin wrote:
> This is the only place where we potentially call SetValue(instr,
> unknown_constant_).  We avoid that elsewhere because we don't want to ever
move
> down the lattice --- we should only call that if it is already
unknown_constant.
> 
> Maybe we should rewrite here to something like:
> 
> const Object& value = ...
> if (IsNonConstant(value)) {
>   SetValue(instr, non_constant_);
>   return;
> } else if (IsUnknown(value)) {
>   ASSERT(IsUnknown(instr));
>   return;
> }

Done.

https://codereview.chromium.org/27192005/diff/74001/runtime/vm/intermediate_l...
File runtime/vm/intermediate_language.h (right):

https://codereview.chromium.org/27192005/diff/74001/runtime/vm/intermediate_l...
runtime/vm/intermediate_language.h:3665: virtual bool CanDeoptimize() const {
return true; }
On 2013/10/16 15:14:03, kmillikin wrote:
> Really?

Offline discsussion: adapt Effects, CanDeoptimize, Dependencies to behave same
as the static call instruction. StrinfInterpolation emits a static call to dart
code which in turn calls toString on individual objects.

[srdjan, 2013-10-16 18:12:19]

Committed patchset #9 manually as r28741.