Update get$hashCode to not use JS for most uses. Also fix issue 6522 where the hashCode of a String…

Update get$hashCode to not use JS for most uses. Also fix issue 6522 where the hashCode of a String was always 0.
Committed: https://code.google.com/p/dart/source/detail?r=14785

[ngeoffray, 2012-11-12 12:10:33]

PTAL, test added and code tweaked as discussed.

[ahe, 2012-11-12 12:56:53]

Awesome, LGTM!

[sra1, 2012-11-12 18:20:58]

I filed Issue 6666 - that would have made it apparent that there was a bug when
you checked the code quality.

https://codereview.chromium.org/11369181/diff/3001/sdk/lib/_internal/compiler...
File sdk/lib/_internal/compiler/implementation/lib/interceptors.dart (right):

https://codereview.chromium.org/11369181/diff/3001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/lib/interceptors.dart:646: return
0x1fffffff & (hash + (0x00003fff & hash) << 15);
+ binds tighter than <<.
You want  (hash + ((0x00003fff & hash) << 15))

https://codereview.chromium.org/11369181/diff/3001/tests/compiler/dart2js_ext...
File tests/compiler/dart2js_extra/hash_code_test.dart (right):

https://codereview.chromium.org/11369181/diff/3001/tests/compiler/dart2js_ext...
tests/compiler/dart2js_extra/hash_code_test.dart:9: Expect.equals(67633152,
'a'.hashCode);
= 0x04080000

https://codereview.chromium.org/11369181/diff/3001/tests/compiler/dart2js_ext...
tests/compiler/dart2js_extra/hash_code_test.dart:10: Expect.equals(37224448,
'b'.hashCode);
= 0x02380000

There is something very wrong with these numbers.

[ahe, 2012-11-12 20:35:23]

Thank you, Stephen.

https://codereview.chromium.org/11369181/diff/3001/sdk/lib/_internal/compiler...
File sdk/lib/_internal/compiler/implementation/lib/interceptors.dart (right):

https://codereview.chromium.org/11369181/diff/3001/sdk/lib/_internal/compiler...
sdk/lib/_internal/compiler/implementation/lib/interceptors.dart:644: hash =
0x1fffffff & (hash + (0x03ffffff & hash) <<  3);
Same problem here as on line 646.

https://codereview.chromium.org/11369181/diff/3001/tests/compiler/dart2js_ext...
File tests/compiler/dart2js_extra/hash_code_test.dart (right):

https://codereview.chromium.org/11369181/diff/3001/tests/compiler/dart2js_ext...
tests/compiler/dart2js_extra/hash_code_test.dart:10: Expect.equals(37224448,
'b'.hashCode);
On 2012/11/12 18:20:58, sra1 wrote:
> = 0x02380000
> 
> There is something very wrong with these numbers.

I assume the problem is that these two value have roughly the same bits?