fuse some null checks with type checks, introduce a special bool variant

fuse some null checks with type checks, introduce a special bool variant
fixes #536

R=sra@google.com

Committed: https://github.com/dart-lang/dev_compiler/commit/0bb4eecc13d72514b079b6eafc4fa9e2e01b1e85

[Jennifer Messerly, 2016-05-10 23:42:11]

jmesserly@google.com changed reviewers:
+ leafp@google.com, sra@google.com

[Jennifer Messerly, 2016-05-10 23:42:12]

https://codereview.chromium.org/1964263002/diff/1/lib/src/compiler/code_gener...
File lib/src/compiler/code_generator.dart (right):

https://codereview.chromium.org/1964263002/diff/1/lib/src/compiler/code_gener...
lib/src/compiler/code_generator.dart:459: JS.Expression
maybeCheckNull(JS.Expression jsExpr) {
aside: it might be a better architecture to fuse the helper calls at the JS AST
level, rather than merge the code paths.

The reason the code path merge seemed okay: if we have not-null types, the "to"
type will encode this information, so notNull will just be a cast to a not null
type.

In other words, it's sort of groundwork for a future Dart language feature.
Maybe. :)

https://codereview.chromium.org/1964263002/diff/1/test/codegen/expect/notnull.js
File test/codegen/expect/notnull.js (right):

https://codereview.chromium.org/1964263002/diff/1/test/codegen/expect/notnull...
test/codegen/expect/notnull.js:158: core.print(1 + dart.asNotNull(this.varField,
core.num) + 2);
`num` and `String` are a couple of other ones I want to take a look at soon.

[Jennifer Messerly, 2016-05-10 23:42:44]

Description was changed from

==========
fuse some null checks with type checks, introduce a special bool variant
==========

to

==========
fuse some null checks with type checks, introduce a special bool variant
fixes #536
==========

[Jennifer Messerly, 2016-05-10 23:43:00]

Oops forgot issue number. It's this one:
https://github.com/dart-lang/dev_compiler/issues/536

[Jennifer Messerly, 2016-05-11 00:11:44]

On 2016/05/10 23:43:00, John Messerly wrote:
> Oops forgot issue number. It's this one:
> https://github.com/dart-lang/dev_compiler/issues/536

Stephen pointed out the asNotNull is not useful since we're only doing that for
primitive types. I agree, I'll remove it for now. What we really want is a
notNull+String/int/num/double checks.

[sra1, 2016-05-11 00:28:23]

LGTM

I'm not sure asNotNull pays its way, since it is only used for primitive types
which could each have their own fast concise function

[Jennifer Messerly, 2016-05-11 18:04:34]

On 2016/05/11 00:28:23, sra1 wrote:
> LGTM
> 
> I'm not sure asNotNull pays its way, since it is only used for primitive types
> which could each have their own fast concise function

Thanks! Yup removed that.

[sra1, 2016-05-11 18:12:03]

Still LGTM

[Jennifer Messerly, 2016-05-11 18:16:07]

Description was changed from

==========
fuse some null checks with type checks, introduce a special bool variant
fixes #536
==========

to

==========
fuse some null checks with type checks, introduce a special bool variant
fixes #536

R=sra@google.com

Committed:
https://github.com/dart-lang/dev_compiler/commit/0bb4eecc13d72514b079b6eafc4f...
==========

[Jennifer Messerly, 2016-05-11 18:16:09]

Committed patchset #2 (id:20001) manually as
0bb4eecc13d72514b079b6eafc4fa9e2e01b1e85 (presubmit successful).