Make Uri._makeQuery easier to analyze

Make Uri._makeQuery easier to analyze

In many programs dart2js can tell that [queryParameters] is always null.

It is too hard for dart2js to infer from the previous conditions that
the last test 'query != null' must always be true. By changing the
liveness predicate for the forEach code to be a function of one
variable, we can help dart2js understand that the forEach code is dead
when queryParameters is null.

BUG=
R=lrn@google.com

Committed: https://github.com/dart-lang/sdk/commit/1381749356ec1b4c0d0a75c7fe579639946b72c8

[sra1, 2016-08-16 21:23:09]

sra@google.com changed reviewers:
+ lrn@google.com

[Lasse Reichstein Nielsen, 2016-08-17 10:53:12]

https://codereview.chromium.org/2245323004/diff/1/sdk/lib/core/uri.dart
File sdk/lib/core/uri.dart (right):

https://codereview.chromium.org/2245323004/diff/1/sdk/lib/core/uri.dart#newco...
sdk/lib/core/uri.dart:1388: if (query != null) return _normalize(query, start,
end, _queryCharTable);
I hate seeing `if (query != null` twice.
How about:

if (query != null) {
  if (queryParameters == null) { 
    return _normalize(query, ...);
  }
  throw ...;
}
if (queryParameters == null) return null;
...

?

[Lasse Reichstein Nielsen, 2016-08-17 10:53:51]

... but if you don't want to change it, what we have now isn't worse than
before, and LGTM then.

[sra1, 2016-08-17 17:41:35]

https://codereview.chromium.org/2245323004/diff/1/sdk/lib/core/uri.dart
File sdk/lib/core/uri.dart (right):

https://codereview.chromium.org/2245323004/diff/1/sdk/lib/core/uri.dart#newco...
sdk/lib/core/uri.dart:1388: if (query != null) return _normalize(query, start,
end, _queryCharTable);
On 2016/08/17 10:53:12, Lasse Reichstein Nielsen wrote:
> I hate seeing `if (query != null` twice.
> How about:
> 
> if (query != null) {
>   if (queryParameters == null) { 
>     return _normalize(query, ...);
>   }
>   throw ...;
> }
> if (queryParameters == null) return null;
> ...
> 
> ?

Done.

[sra1, 2016-08-17 17:45:21]

Description was changed from

==========
Make Uri._makeQuery easier to analyze

In many programs dart2js can tell that [queryParameters] is always null.

It is too hard for dart2js to infer from the previous conditions that
the last test 'query != null' must always be true. By changing the
liveness predicate for the forEach code to be a function of one
variable, we can help dart2js understand that the forEach code is dead
when queryParameters is null.

BUG=
==========

to

==========
Make Uri._makeQuery easier to analyze

In many programs dart2js can tell that [queryParameters] is always null.

It is too hard for dart2js to infer from the previous conditions that
the last test 'query != null' must always be true. By changing the
liveness predicate for the forEach code to be a function of one
variable, we can help dart2js understand that the forEach code is dead
when queryParameters is null.

BUG=
R=lrn@google.com

Committed:
https://github.com/dart-lang/sdk/commit/1381749356ec1b4c0d0a75c7fe579639946b72c8
==========

[sra1, 2016-08-17 17:45:23]

Committed patchset #2 (id:20001) manually as
1381749356ec1b4c0d0a75c7fe579639946b72c8 (presubmit successful).