Previously doubles was saved as strings in the string table,
with a DoubleLiteral holding a StringReference.
This can cause overhead in both computation time
(converting the double to and from string) as well as size
(e.g. a single usage of the previously unused double 1000000.42
would use (at least)
* 10 bytes for the characters
* 1 byte for the size
* 1 byte for the reference to the string
whereas saving it as a double would simply save the 8 bytes.
On the other hand the string table doesn't contain duplicates so
many usages of the same double will use more space.
The SDK dill file size decreases slightly (< 1 KB).
On a Dart file with 1M different doubles (0.42, 1.42, ..., 999999.42)
added to a list:
Before:
compile and write via fasta (non-strong-mode): 0:12.18
Reading (via dart, eager): 2500-2600 ms
Writing (to null sink) (after reading): 1600-1800 ms
Output dill file (via fasta compile): ~62 MB
After:
compile and write via fasta (non-strong-mode): 0:11.76
Reading (via dart, eager): 2050-2350 ms
Writing (to null sink) (after reading): 400-550 ms
Output dill file (via fasta compile): ~54 MB
Running the dill file is ~the same time, but "Maximum resident set size
(kbytes)" (from /usr/bin/time -v) decreases with ~4%.
On the other side, if it's 1M of the same doubles (0.42), while
compiling is ~the same speed, the output dill goes from 43MB to 50MB.
Surprisingly the "Maximum resident set size (kbytes)" still decreases
though (~3%).
Running flutter test in flutter/packages/flutter:
Before:
```
02:33 +2425 ~18: All tests passed!
02:28 +2425 ~18: All tests passed!
02:28 +2425 ~18: All tests passed!
```
After:
```
02:12 +2425 ~18: All tests passed!
02:11 +2425 ~18: All tests passed!
02:12 +2425 ~18: All tests passed!
```
So that's -12.0267% +/- 3.15253%
File size of a dill file of an arbitrary test using flutter is reduced by ~44 KB (~0.3%).
Change-Id: I64151376cde1dae6f0d02b3d96991bc432a994ae
Reviewed-on: https://dart-review.googlesource.com/41660
Commit-Queue: Jens Johansen <jensj@google.com>
Reviewed-by: Kevin Millikin <kmillikin@google.com>
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Jens Johansen
6e2536f585