dart2js cps: Use 'this' instead of receiver when possible.

dart2js cps: Use 'this' instead of receiver-arg when possible.

This fixes a bug in how intercepted super calls were handled,
and enables the redundant receiver optimization.

BUG=
R=kmillikin@google.com

Committed: https://github.com/dart-lang/sdk/commit/0216e21efcb7768ddd2ba060fa3fd20c761b185a

[asgerf, 2015-08-26 10:16:36]

asgerf@google.com changed reviewers:
+ kmillikin@google.com

[Kevin Millikin (Google), 2015-08-26 10:26:22]

LGTM.

[asgerf, 2015-08-26 14:06:46]

Committed patchset #2 (id:20001) manually as
0216e21efcb7768ddd2ba060fa3fd20c761b185a (presubmit successful).

[sra1, 2015-08-26 15:04:43]

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

[sra1, 2015-08-26 15:04:43]

DBC

https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/cp...
File pkg/compiler/lib/src/cps_ir/type_propagation.dart (right):

https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/cp...
pkg/compiler/lib/src/cps_ir/type_propagation.dart:1611: // argument because
BoundClosure uses it for equality and hash code.
SSA backend has this TODO.

          // TODO(15933): Make automatically generated property extraction
          // closures work with the dummy receiver optimization.

Add a TODO here.
We loose a lot of opportunities for better looking code on get$length.

https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/cp...
pkg/compiler/lib/src/cps_ir/type_propagation.dart:1621: Constant dummy =
makeConstantPrimitive(new IntConstantValue(0));
There is a special constant for this purpose.
In constants/values.dart, SyntheticConstantValue.
The type of the constant is not 'int'.
The syntax '0' is deferred to the js generation.

SSA backend constructs this so:

            ConstantValue constant = new SyntheticConstantValue(
                SyntheticConstantKind.DUMMY_INTERCEPTOR,
                receiverArgument.instructionType);

https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/js...
File pkg/compiler/lib/src/js_backend/codegen/glue.dart (right):

https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/js...
pkg/compiler/lib/src/js_backend/codegen/glue.dart:57: bool
isUsedAsMixin(ClassElement clazz) {
nit: I'm not a fan of the non-word 'clazz'.
Other places in the compiler use 'element' or 'classElement'.
I'd prefer the CPS files were consistent.

[floitsch, 2015-09-10 16:11:18]

On 2015/08/26 15:04:43, sra1 wrote:
> DBC
> 
>
https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/cp...
> File pkg/compiler/lib/src/cps_ir/type_propagation.dart (right):
> 
>
https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/cp...
> pkg/compiler/lib/src/cps_ir/type_propagation.dart:1611: // argument because
> BoundClosure uses it for equality and hash code.
> SSA backend has this TODO.
> 
>           // TODO(15933): Make automatically generated property extraction
>           // closures work with the dummy receiver optimization.
> 
> Add a TODO here.
> We loose a lot of opportunities for better looking code on get$length.
> 
>
https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/cp...
> pkg/compiler/lib/src/cps_ir/type_propagation.dart:1621: Constant dummy =
> makeConstantPrimitive(new IntConstantValue(0));
> There is a special constant for this purpose.
> In constants/values.dart, SyntheticConstantValue.
> The type of the constant is not 'int'.
> The syntax '0' is deferred to the js generation.
> 
> SSA backend constructs this so:
> 
>             ConstantValue constant = new SyntheticConstantValue(
>                 SyntheticConstantKind.DUMMY_INTERCEPTOR,
>                 receiverArgument.instructionType);
> 
>
https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/js...
> File pkg/compiler/lib/src/js_backend/codegen/glue.dart (right):
> 
>
https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/js...
> pkg/compiler/lib/src/js_backend/codegen/glue.dart:57: bool
> isUsedAsMixin(ClassElement clazz) {
> nit: I'm not a fan of the non-word 'clazz'.
> Other places in the compiler use 'element' or 'classElement'.
> I'd prefer the CPS files were consistent.

@asgerf: I can see that the TODO was added, but the SyntheticConstantValue
wasn't.
Please follow up. (Either implement it, or explain in a response to Stephen's
comment).

[asgerf, 2015-09-11 10:24:52]

On 2015/09/10 16:11:18, floitsch wrote:
> On 2015/08/26 15:04:43, sra1 wrote:
> > DBC
> > 
> >
>
https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/cp...
> > File pkg/compiler/lib/src/cps_ir/type_propagation.dart (right):
> > 
> >
>
https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/cp...
> > pkg/compiler/lib/src/cps_ir/type_propagation.dart:1611: // argument because
> > BoundClosure uses it for equality and hash code.
> > SSA backend has this TODO.
> > 
> >           // TODO(15933): Make automatically generated property extraction
> >           // closures work with the dummy receiver optimization.
> > 
> > Add a TODO here.
> > We loose a lot of opportunities for better looking code on get$length.
> > 
> >
>
https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/cp...
> > pkg/compiler/lib/src/cps_ir/type_propagation.dart:1621: Constant dummy =
> > makeConstantPrimitive(new IntConstantValue(0));
> > There is a special constant for this purpose.
> > In constants/values.dart, SyntheticConstantValue.
> > The type of the constant is not 'int'.
> > The syntax '0' is deferred to the js generation.
> > 
> > SSA backend constructs this so:
> > 
> >             ConstantValue constant = new SyntheticConstantValue(
> >                 SyntheticConstantKind.DUMMY_INTERCEPTOR,
> >                 receiverArgument.instructionType);
> > 
> >
>
https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/js...
> > File pkg/compiler/lib/src/js_backend/codegen/glue.dart (right):
> > 
> >
>
https://codereview.chromium.org/1312393002/diff/20001/pkg/compiler/lib/src/js...
> > pkg/compiler/lib/src/js_backend/codegen/glue.dart:57: bool
> > isUsedAsMixin(ClassElement clazz) {
> > nit: I'm not a fan of the non-word 'clazz'.
> > Other places in the compiler use 'element' or 'classElement'.
> > I'd prefer the CPS files were consistent.
> 
> @asgerf: I can see that the TODO was added, but the SyntheticConstantValue
> wasn't.
> Please follow up. (Either implement it, or explain in a response to Stephen's
> comment).

I reverted this CL because the synthetic constant was causing strange problems.

The parts not related to the synthetic constant are here:
https://codereview.chromium.org/1304943003

The problems seem to start when receiver is a constant, because then we get a
constant C whose type
is another constant C'. Type propagation was not prepared for that.

But there's more going on. Last I tried to fix it I gave up after a long
fruitless debugging session,
but I'll give it another shot.

[asgerf, 2015-09-11 10:27:44]

Sorry, this CL was actually never reverted, but I added Stephen's comments in
this CL:

https://codereview.chromium.org/1317903002/

That CL was then reverted because of the synthetic constant.