Jens Johansen
0c2d7decd7
The analyzer makes a copy of `lineStarts` without the last element,
and copying it in to a `Uint16List` or an `Uint32List` depending on
what's needed (to avoid using more ram than necessary).
Because the (actual) scanner (`AbstractScanner`) does the same trick
with `Uint16List`/`Uint32List` the linestarts output from the scanner,
while a `List<int>`, is actually a `LineStarts` class, and copying that
into a `Uint16List` (or `Uint32List`) goes into
`_TypedIntListMixin._SlowSetRange` which as the name suggests is slower
than it has to be.
This CL puts the copying into the `LineStarts` class where it actually
has a `Uint16List`/`Uint32List` already, and doing the copy from that
instead avoids the slowdown.
Numbers from `perf stat`:
Before:
```
39,552,191,101 instructions:u
39,552,058,132 instructions:u
39,552,065,649 instructions:u
```
After:
```
39,419,426,977 instructions:u
39,419,429,914 instructions:u
39,419,441,613 instructions:u
```
Saving: about 132 million instructions.
Change-Id: Ibf6c7f6cc9324a54d2bd99c37058103af106164c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/508580
Reviewed-by: Johnni Winther <johnniwinther@google.com>
FE/analyzer shared code
This package contains logic that is shared between the front_end and analyzer packages. It is intended solely to facilitate development of the Dart SDK, and is not intended for use by end users. In particular, this package has no public API, so no guarantee is made of compatibility between one version of the package and the next.
End users should consider using the analyzer package to analyze Dart source code.