Make ktfmt up to 100x faster via native-image

[sgammon]

Native ktfmt

Introduces support for a native binary version of ktfmt, via GraalVM native-image; no code changes have taken place, just build changes, in order to make kotlinc's infrastructure (which ktfmt depends on) usable under SVM, Substrate Virtual Machine.

After some optimization and cleanup, I have some initial numbers which show promising gains:

The native version of ktfmt is identical in every way to the regular JVM version, except it is built AOT, and, since it is already machine code, it does not need a JVM installed at runtime.

We have been using this version of ktfmt internally for some time now -- a few weeks -- and it is stable for us even on codebases with hundreds or thousands of files. Once you hit many thousands of files, the performance gap between JVM and SVM begins to close (this is tunable). That makes sense, considering JVM's warmed-up JIT state is still known to beat SVM at peak performance.

However, for smaller executions of ktfmt -- particularly ones which only format changed code -- the difference can be quite persuasive toward native, because of essentially instant startup time.

Note: To actually ship this on ktfmt, we are going to need build infrastructure for each target OS/architecture pair. GraalVM's support matrix currently includes:

• Linux amd64 / arm64
• macOS amd64 / arm64
• Windows amd64

I am able to build ktfmt for each of the above targets, and have CI (personally) to help, but will need to transition that stuff to GHA and Meta's control. In conversations with Nivaldo (@hick209), he indicated CI should be no problem.

Fixes and closes #441 cc / @ZacSweers

Trying it out

Here are pre-built binaries for Linux amd64 and macOS arm64, if you'd like to try it out. Each package comes with ktfmt and ktfmt-build-report.html, which is a standalone file you can open in your browser. It shows the full contents of the native image and various stats about its contents.

Download for macOS arm64
Download for Linux amd64

The final compressed packages end up at about 13MB for macOS and 16MB for Linux.

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[sgammon]

self-review

[ZacSweers]

I don't work at facebook and am not a maintainer on this project. I just filed that FR 🙃

[ZacSweers]

yeah I meant to react to the PR description, accidentally did the wrong one 🙈

[meta-cla]

Thank you for signing our Contributor License Agreement. We can now accept your code for this (and any) Meta Open Source project. Thanks!

[hick209]

Initial batch. There shall be more tomorrow 😃

Here are my initial comments. No need to act on anything just yet if you do not desire.

[hick209]

It's honestly a lot of things I don't really understand here.
From my limited understanding this seems like a good improvement and I'm tempted to just merge it in and give it a go.

Right now I see there some CI jobs (here from GH) failed, could you take a look to see if any of that makes sense before I pull this in for internal review?

[eduardb]

Was this PR abandoned? 😢

[sgammon]

@eduardb not abandoned, no, just trying to figure out windows CI; meta must facilitate windows and mac CI in order to support this on all operating systems. we have offered to provide those CI services at our own cost.

i will be updating this to match main

[sgammon]

if, in the meantime, any community members would like ktfmt in native mode, please use the downloads in this PR, or use Elide, which has ktfmt built in at elide ktfmt -- .... It's free. this is the only way we know how to provide this download to users before this PR is merged.

[hick209]

Is the build break there expected?

Not the CodeQL one, that one seem broken for all commits, so don't worry

[sgammon]

@hick209 now the only broken step is codeql

[sgammon]

@hick209 OK, I have split it up, rebased, and cleaned it up a bit:

1. fix: lazily initialize Kotlin parser environment
   Isolates the only actual code change; Parser.env is now initialized lazily, which helps native-image avoid performing Kotlin's compiler setup too early. That should happen at runtime, rather than build time. There is effectively zero behavior change on JVM.

2. feat: build ktfmt native image
   What changed:

• Moved native image build logic to a convention plugin, so it is isolated and doesn't pollute the main build logic
• Moved native image libraries to a dedicated version catalog, at gradle/native-image.versions.toml
• Split PGO out into another branch, so it can be added later (this removes a lot of stuff)
• Marks reachability metadata as generated in .gitattributes so it doesn't pollute review

3. chore: run CI on native-image branch
   This is just a temporary commit to get CI to run on my fork. I intend to test there a bit as I go. This commit should be dropped before merge

[hick209]

We only plan to keep the main branch, so I guess we can drop this here, right?

[sgammon]

Yes, this is a temporary commit only, so that testing can happen on my fork; I can make sure the build is green before pinging you for a build approval

[hick209]

Nice! It looks much better / cleaner now! Thank you

[meta-codesync]

@hick209 has imported this pull request. If you are a Meta employee, you can view this in D108930075.