dart2js: Better big-number shortening.

dart2js: Better big-number shortening.

R=sra@google.com

Committed: https://code.google.com/p/dart/source/detail?r=43980

[floitsch, 2015-02-20 20:23:19]

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

[sra1, 2015-02-20 22:08:26]

lgtm

https://codereview.chromium.org/938323003/diff/1/pkg/compiler/lib/src/js_back...
File pkg/compiler/lib/src/js_backend/constant_emitter.dart (right):

https://codereview.chromium.org/938323003/diff/1/pkg/compiler/lib/src/js_back...
pkg/compiler/lib/src/js_backend/constant_emitter.dart:209: if
(!compiler.enableMinification) return numberString;
I would still do this, the cutoff avoids most weird looking numbers like 1e3.

https://codereview.chromium.org/938323003/diff/1/pkg/compiler/lib/src/js_back...
pkg/compiler/lib/src/js_backend/constant_emitter.dart:217: int pos = 2;
int pos = numberString.indexOf('e', 2);

Or you could match the pieces with a regexp, which might be able to take care of
all the special cases.

https://codereview.chromium.org/938323003/diff/1/pkg/compiler/lib/src/js_back...
pkg/compiler/lib/src/js_backend/constant_emitter.dart:240: // (like
1234567890123456789012345 which becomes 1.2345678901234568e+24).
This comment might not be accurate - no +.

[floitsch, 2015-02-23 18:35:56]

New patchsets have been uploaded after l-g-t-m from sra@google.com

[floitsch, 2015-02-23 18:36:23]

https://codereview.chromium.org/938323003/diff/1/pkg/compiler/lib/src/js_back...
File pkg/compiler/lib/src/js_backend/constant_emitter.dart (right):

https://codereview.chromium.org/938323003/diff/1/pkg/compiler/lib/src/js_back...
pkg/compiler/lib/src/js_backend/constant_emitter.dart:209: if
(!compiler.enableMinification) return numberString;
On 2015/02/20 22:08:25, sra1 wrote:
> I would still do this, the cutoff avoids most weird looking numbers like 1e3.

It was to avoid running it for visitDouble but done.

https://codereview.chromium.org/938323003/diff/1/pkg/compiler/lib/src/js_back...
pkg/compiler/lib/src/js_backend/constant_emitter.dart:217: int pos = 2;
On 2015/02/20 22:08:25, sra1 wrote:
> int pos = numberString.indexOf('e', 2);
> 
> Or you could match the pieces with a regexp, which might be able to take care
of
> all the special cases.

Exponential representations always start with a single digit. No need to search
for more.

I just did a regexp, but in the end I don't think it's worth it.
Keeping the manual parsing.

https://codereview.chromium.org/938323003/diff/1/pkg/compiler/lib/src/js_back...
pkg/compiler/lib/src/js_backend/constant_emitter.dart:240: // (like
1234567890123456789012345 which becomes 1.2345678901234568e+24).
On 2015/02/20 22:08:25, sra1 wrote:
> This comment might not be accurate - no +.

Done.

[floitsch, 2015-02-24 10:22:21]

Committed patchset #2 (id:20001) manually as 43980 (presubmit successful).

[sra1, 2015-02-24 16:58:41]

The code forgot to handle negative numbers.
From minified swarm:

if(isNaN(y)||y<-8.64e+15||y>864e13)return