Rewrite blocks of single operator into just a single operator.

Rewrite blocks of single operator into just a single operator.

There is an imporant exception, although somewhat artificial: if block
consists of variable definitions, we shouldn't do that not to break
scoping rules and violations.

R=smok@google.com

Committed: https://code.google.com/p/dart/source/detail?r=12764

[Roman, 2012-09-21 08:10:37]

https://codereview.chromium.org/10962015/diff/1/lib/compiler/implementation/d...
File lib/compiler/implementation/dart_backend/backend.dart (right):

https://codereview.chromium.org/10962015/diff/1/lib/compiler/implementation/d...
lib/compiler/implementation/dart_backend/backend.dart:85: rewritTo(Statement
statement) {
rewriteTo?
"rewriteTo" is a weird name. What does it mean?

https://codereview.chromium.org/10962015/diff/1/lib/compiler/implementation/d...
lib/compiler/implementation/dart_backend/backend.dart:90: if (single is
!VariableDefinitions) return single;
What about function declarations?

main() {
  f(){}
  {
    f(){}
  }
}

[Anton Muhin, 2012-09-21 12:02:14]

https://codereview.chromium.org/10962015/diff/1/lib/compiler/implementation/d...
File lib/compiler/implementation/dart_backend/backend.dart (right):

https://codereview.chromium.org/10962015/diff/1/lib/compiler/implementation/d...
lib/compiler/implementation/dart_backend/backend.dart:85: rewritTo(Statement
statement) {
On 2012/09/21 08:10:37, Roman wrote:
> rewriteTo?
> "rewriteTo" is a weird name. What does it mean?

Any better proposals?

https://codereview.chromium.org/10962015/diff/1/lib/compiler/implementation/d...
lib/compiler/implementation/dart_backend/backend.dart:90: if (single is
!VariableDefinitions) return single;
Well spotted, thanks a lot!

On 2012/09/21 08:10:37, Roman wrote:
> What about function declarations?
> 
> main() {
>   f(){}
>   {
>     f(){}
>   }
> }

[Roman, 2012-09-21 12:10:27]

https://codereview.chromium.org/10962015/diff/4001/lib/compiler/implementatio...
File lib/compiler/implementation/dart_backend/backend.dart (right):

https://codereview.chromium.org/10962015/diff/4001/lib/compiler/implementatio...
lib/compiler/implementation/dart_backend/backend.dart:85: rewritTo(Statement
statement) {
tryRewriteSingleStatementBlock?

[Anton Muhin, 2012-09-21 12:13:08]

https://codereview.chromium.org/10962015/diff/4001/lib/compiler/implementatio...
File lib/compiler/implementation/dart_backend/backend.dart (right):

https://codereview.chromium.org/10962015/diff/4001/lib/compiler/implementatio...
lib/compiler/implementation/dart_backend/backend.dart:85: rewritTo(Statement
statement) {
On 2012/09/21 12:10:27, Roman wrote:
> tryRewriteSingleStatementBlock?

There should be no references to single statement block as this will eventually
do all the kinds of rewrites.

And why try if it always returns something?

[Roman, 2012-09-21 12:16:00]

lgtm

https://codereview.chromium.org/10962015/diff/4001/lib/compiler/implementatio...
File lib/compiler/implementation/dart_backend/backend.dart (right):

https://codereview.chromium.org/10962015/diff/4001/lib/compiler/implementatio...
lib/compiler/implementation/dart_backend/backend.dart:85: rewritTo(Statement
statement) {
On 2012/09/21 12:13:08, Anton Muhin wrote:
> On 2012/09/21 12:10:27, Roman wrote:
> > tryRewriteSingleStatementBlock?
> 
> There should be no references to single statement block as this will
eventually
> do all the kinds of rewrites.
> 
> And why try if it always returns something?

then just rewriteStatement?

side note: does 'try' mean 'sometimes return something'?