Jens Johansen
2849d34c7c
The RegEx engine in the VM was updated in
e443b89f23 which caused the analyzer
analyzing the CFE to use ~150 mio instructions more.
Part of this was an increased cost in ignore comment processing which
relied on regex. Using regex before the updated engine made
`processPrecedingComments` have a cost of ~240 mio instructions,
updating the regex engine took that to ~264 mio instructions.
This CL gets rid of the regex and takes the cost of
`processPrecedingComments` to ~74.4 mio instructions a saving of about
189 mio instructions (all then analyzing the CFE and looking at output
from `valgrind --tool=callgrind`).
Benchmarking with `perf stat` with normal GC gives:
```
task-clock:u: -2.1760% +/- 1.6063% (-265608341.80 +/- 196062087.98) (12206056036.20 -> 11940447694.40)
page-faults:u: 0.2301% +/- 0.0313% (448.20 +/- 60.88) (194764.60 -> 195212.80)
cycles:u: -2.2906% +/- 1.6090% (-1180119481.60 +/- 828994273.75) (51521138476.00 -> 50341018994.40)
instructions:u: -0.3325% +/- 0.0032% (-196547942.60 +/- 1874215.18) (59120651337.60 -> 58924103395.00)
seconds time elapsed: -2.1715% +/- 1.6011% (-0.27 +/- 0.20) (12.21 -> 11.95)
seconds user: -2.2487% +/- 1.7816% (-0.27 +/- 0.21) (11.87 -> 11.60)
Comparing GC data:
'No' GC change.
```
Note that it must push the GC - the savings isn't really 2% in time.
And with GC disabled:
```
instructions:u: -0.4562% +/- 0.0029% (-185499444.00 +/- 1189012.77) (40663084597.80 -> 40477585153.80)
```
So here a saving of ~185 mio which fits okay with the data from
valgrind.
Change-Id: Ib203baeac6a93f5e37c737080fed342dbd0740a7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/487021
Commit-Queue: Jens Johansen <jensj@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
This package provides a library that performs static analysis of Dart code. It is useful for tool integration and embedding.
End-users should use the dart analyze command-line tool to analyze their Dart code.
Integrators that want to add Dart support to their editor should use the Dart Analysis Server. The Analysis Server API Specification is available. If you are adding Dart support to an editor or IDE, please let us know by emailing our list.
Configuring the analyzer
Both dart analyze and Dart Analysis Server can be configured with an
analysis_options.yaml file (using an .analysis_options file is deprecated).
This YAML file can control which files and paths are analyzed,
which lints are applied, and more.
If you are embedding the analyzer library in your project, you are responsible for finding the analysis options file, parsing it, and configuring the analyzer.
The analysis options file should live at the root of your project (for example,
next to your pubspec.yaml). Different embedders of analyzer, such as
dart analyze or Dart Analysis Server, may choose to find the file in various
different ways. Consult their documentation to learn more.
Here is an example file that instructs the analyzer to ignore two files:
analyzer:
exclude:
- test/_data/p4/lib/lib1.dart
- test/_data/p5/p5.dart
- test/_data/bad*.dart
- test/_brokendata/**
Note that you can use globs, as defined by the glob package.
Here is an example file that enables two lint rules:
linter:
rules:
- camel_case_types
- empty_constructor_bodies
Check out all the available Dart lint rules.
You can combine the analyzer section and the linter section into a single
configuration. Here is an example:
analyzer:
exclude:
- test/_data/p4/lib/lib1.dart
linter:
rules:
- camel_case_types
For more information, see the docs for customizing static analysis.
Who uses this library?
Many tools embed this library, such as:
- dart format - a formatter for Dart code
- dart doc - a documentation generator for Dart code
- Dart Analysis Server - a stateful server that supports IDEs and editors
Support
Post issues and feature requests at https://github.com/dart-lang/sdk/issues. These will be triaged according to the analyzer triage priorities.
Questions and discussions are welcome at the Dart Analyzer Discussion Group.
Background
The APIs in this package were originally machine generated by a translator and were based on an earlier Java implementation. Several of the API's still look like their Java predecessors rather than clean Dart APIs.
In addition, there is currently no clean distinction between public and internal APIs. We plan to address this issue but doing so will, unfortunately, require a large number of breaking changes. We will try to minimize the pain this causes for our clients, but some pain is inevitable.
License
See the LICENSE file.