Convert a == to a builtin identity check if the receiver type can only hit Object==.

Convert a == to a builtin identity check if the receiver type can only hit Object==.
Committed: https://code.google.com/p/dart/source/detail?r=20308

[ngeoffray, 2013-03-20 22:02:27]

This should get rid of the remaining $eq calls we found.

[kasperl, 2013-03-21 07:07:04]

LGTM.

https://codereview.chromium.org/12974002/diff/1/sdk/lib/_internal/compiler/im...
File
sdk/lib/_internal/compiler/implementation/ssa/invoke_dynamic_specializers.dart
(right):

https://codereview.chromium.org/12974002/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/ssa/invoke_dynamic_specializers.dart:548:
// JSNull::operator==.
Do we need the JSNull operator ==? If we ignore it even when the receiver might
be null, it seems like we could be able to get rid of it?

[ngeoffray, 2013-03-21 08:59:01]

Thanks Kasper.

https://codereview.chromium.org/12974002/diff/1/sdk/lib/_internal/compiler/im...
File
sdk/lib/_internal/compiler/implementation/ssa/invoke_dynamic_specializers.dart
(right):

https://codereview.chromium.org/12974002/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/ssa/invoke_dynamic_specializers.dart:548:
// JSNull::operator==.
On 2013/03/21 07:07:04, kasperl wrote:
> Do we need the JSNull operator ==? If we ignore it even when the receiver
might
> be null, it seems like we could be able to get rid of it?

We can't get rid of it. If we have no clue what the receiver is, and there are
multiple operator==, we'll do a getInterceptor(receiver).eq(other). The
getInterceptor will return JSNull.prototype, which must have a specialized
operator== because the Object implementation does not consider the receiver to
be null.

It's a bit complicated...

[sra1, 2013-03-21 08:59:07]

https://codereview.chromium.org/12974002/diff/1/sdk/lib/_internal/compiler/im...
File
sdk/lib/_internal/compiler/implementation/ssa/invoke_dynamic_specializers.dart
(right):

https://codereview.chromium.org/12974002/diff/1/sdk/lib/_internal/compiler/im...
sdk/lib/_internal/compiler/implementation/ssa/invoke_dynamic_specializers.dart:548:
// JSNull::operator==.
On 2013/03/21 07:07:04, kasperl wrote:
> Do we need the JSNull operator ==? If we ignore it even when the receiver
might
> be null, it seems like we could be able to get rid of it?

I'm not sure whether you mean get rid of this check (and generate HIdentity more
often), or get rid of operator== on JSNull?

[ngeoffray, 2013-03-21 09:51:35]

Committed patchset #2 manually as r20308 (presubmit successful).