dart2js: don't emit big integers as integer, but instead use their exponential representation.

dart2js: don't emit big integers as integer, but instead use their exponential representation.

BUG= http://dartbug.com/16600
R=herhut@google.com

Committed: https://code.google.com/p/dart/source/detail?r=43913

[floitsch, 2015-02-20 13:33:42]

floitsch@google.com changed reviewers:
+ herhut@google.com

[herhut, 2015-02-20 13:57:31]

lgtm

[floitsch, 2015-02-20 14:29:53]

Committed patchset #1 (id:1) manually as 43913 (presubmit successful).

[sra1, 2015-02-20 17:02:53]

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

[sra1, 2015-02-20 17:02:54]

I think I would keep "1000" for the sanity of the reader and only generate "1e3"
in minified mode.

How does gzip like the shorter format?

https://codereview.chromium.org/944863002/diff/1/pkg/compiler/lib/src/js_back...
File pkg/compiler/lib/src/js_backend/constant_emitter.dart (right):

https://codereview.chromium.org/944863002/diff/1/pkg/compiler/lib/src/js_back...
pkg/compiler/lib/src/js_backend/constant_emitter.dart:208: // For example:
"1e+4" is shorter than "10000".
The + is not necessary, making "1e3" shorter than "1000".
The period is never necessary for integer values:

1.2e+10 ->  12e9

I might be a bit nervous about hacking the string output outside the
exact-integer (2^53) range, but the parser should be just counting digits to
adjust the exponent before dividing.

Make sure all this works when running dart2js self-compiled, when the 'int' is
represented as an integer valued double.  This basically means you can't rely on
the int toString() returning only digits.

https://codereview.chromium.org/944863002/diff/1/pkg/compiler/lib/src/js_back...
pkg/compiler/lib/src/js_backend/constant_emitter.dart:212: // However, since
JavaScript engines implicitly convert to double, these
nit. They don't 'implicitly convert to' so much as 'represent as'.

https://codereview.chromium.org/944863002/diff/1/tests/compiler/dart2js/numbe...
File tests/compiler/dart2js/number_output_test.dart (right):

https://codereview.chromium.org/944863002/diff/1/tests/compiler/dart2js/numbe...
tests/compiler/dart2js/number_output_test.dart:24:
Expect.isTrue(jsOutput.contains('1.23e+7')); // Shorter than 12300000.
123e5 would be better

[floitsch, 2015-02-20 20:23:21]

Didn't test gzip. It most likely depends on the program. The main-benefit of
this patch is to make sure we don't emit 308 characters for some constants...

https://codereview.chromium.org/944863002/diff/1/pkg/compiler/lib/src/js_back...
File pkg/compiler/lib/src/js_backend/constant_emitter.dart (right):

https://codereview.chromium.org/944863002/diff/1/pkg/compiler/lib/src/js_back...
pkg/compiler/lib/src/js_backend/constant_emitter.dart:208: // For example:
"1e+4" is shorter than "10000".
On 2015/02/20 17:02:54, sra1 wrote:
> The + is not necessary, making "1e3" shorter than "1000".
> The period is never necessary for integer values:
> 
> 1.2e+10 ->  12e9
> 
> I might be a bit nervous about hacking the string output outside the
> exact-integer (2^53) range, but the parser should be just counting digits to
> adjust the exponent before dividing.
> 
> Make sure all this works when running dart2js self-compiled, when the 'int' is
> represented as an integer valued double.  This basically means you can't rely
on
> the int toString() returning only digits.

https://codereview.chromium.org/938323003

https://codereview.chromium.org/944863002/diff/1/pkg/compiler/lib/src/js_back...
pkg/compiler/lib/src/js_backend/constant_emitter.dart:212: // However, since
JavaScript engines implicitly convert to double, these
On 2015/02/20 17:02:54, sra1 wrote:
> nit. They don't 'implicitly convert to' so much as 'represent as'.

done in https://codereview.chromium.org/938323003

https://codereview.chromium.org/944863002/diff/1/tests/compiler/dart2js/numbe...
File tests/compiler/dart2js/number_output_test.dart (right):

https://codereview.chromium.org/944863002/diff/1/tests/compiler/dart2js/numbe...
tests/compiler/dart2js/number_output_test.dart:24:
Expect.isTrue(jsOutput.contains('1.23e+7')); // Shorter than 12300000.
On 2015/02/20 17:02:54, sra1 wrote:
> 123e5 would be better

https://codereview.chromium.org/938323003