Inline [] operator on one-byte strings.

Inline [] operator on one-byte strings.

str[i] is translated into

temp = str.charCodeAt(i)
result = StringFromCharCode(temp);

The existing code for charCodeAt is reused and contains
the necessary range class id and range check.
Committed: https://code.google.com/p/dart/source/detail?r=15246

[srdjan, 2012-11-21 16:38:15]

LGTM

https://codereview.chromium.org/11416129/diff/4002/runtime/vm/flow_graph_opti...
File runtime/vm/flow_graph_optimizer.cc (right):

https://codereview.chromium.org/11416129/diff/4002/runtime/vm/flow_graph_opti...
runtime/vm/flow_graph_optimizer.cc:1131: }
Why not just return the value instead? Is that handled somewhere else?

[srdjan, 2012-11-21 16:38:47]

And please add a test for constant array and index.

On 2012/11/21 16:38:15, srdjan wrote:
> LGTM
> 
>
https://codereview.chromium.org/11416129/diff/4002/runtime/vm/flow_graph_opti...
> File runtime/vm/flow_graph_optimizer.cc (right):
> 
>
https://codereview.chromium.org/11416129/diff/4002/runtime/vm/flow_graph_opti...
> runtime/vm/flow_graph_optimizer.cc:1131: }
> Why not just return the value instead? Is that handled somewhere else?

[Florian Schneider, 2012-11-22 11:05:58]

https://codereview.chromium.org/11416129/diff/4002/runtime/vm/flow_graph_opti...
File runtime/vm/flow_graph_optimizer.cc (right):

https://codereview.chromium.org/11416129/diff/4002/runtime/vm/flow_graph_opti...
runtime/vm/flow_graph_optimizer.cc:1131: }
On 2012/11/21 16:38:15, srdjan wrote:
> Why not just return the value instead? Is that handled somewhere else?

This helper builds the graph for charCodeAt, which is used two times below: in
for inlining charCodeAt and as a part of charAt. Also, I have not implemented
support for constant strings/constant indices yet, but added a TODO in the code
generator for now.