commit 3f24e5742230f300aff4585eb9ede9fc90b88d98
author Jens Johansen <jensj@google.com> Wed Sep 25 06:47:14 2024 +0000
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed Sep 25 06:47:14 2024 +0000
tree 795e0fc342ad057601cb082d875acfd00bd3e14a
parent d4b9bd6c38827b51deab10792269f1ed6b4c2e13

[scanner] Add scanner benchmark

E.g. we might do this

```
$ out/ReleaseX64/dart-sdk/bin/dart compile aot-snapshot pkg/_fe_analyzer_shared/test/scanner_benchmark.dart
Generated: /usr/local/google/home/jensj/code/dart-sdk/sdk/pkg/_fe_analyzer_shared/test/scanner_benchmark.aot

$ for type in --bytes --bytes0 --string --stringtobytes --count ; do out/ReleaseX64/dart-sdk/bin/dartaotruntime pkg/_fe_analyzer_shared/test/scanner_benchmark.aot pkg/kernel/lib/ast.dart $type; done
Scanned 466534 bytes 1000 times in 0:00:04.413011
Found errors 0 times
That's 105.71784208106438 bytes per microsecond

Scanned 466534 bytes 1000 times in 0:00:04.911947
Found errors 0 times
That's 94.97944501437007 bytes per microsecond

Scanned 466532 string characters 1000 times in 0:00:05.413169
Found errors 0 times
That's 86.18463602374136 string characters per microsecond

Scanned 466532 string characters as bytes 1000 times in 0:00:06.722731
Found errors 0 times
That's 69.39620222793386 string characters as bytes per microsecond

Scanned 466534 bytes 1000 times in 0:00:00.641854
Found errors 0 times
That's 726.8537704836302 bytes per microsecond
```

to see that scanning pre-0-at-the-end'ed bytes scan at ~105 bytes/µs,
doing a copy to add the 0 at then end, then parse bytes scan at ~95,
scanning strings runs at ~86, converting strings to bytes, then scanning
the bytes at ~69 and - for comparision - just running through the bytes
counting linebreaks runs at ~726.

The benchmark is also useful for comparing optimizations.

Change-Id: I67c12850505e7f712660fd353575e8c7a455f112
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/385920
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Jens Johansen <jensj@google.com>