perf(minifier): use oxc_data_structures::stack::Stack for ClassSymbolsStack

[sapphi-red]

Changed ClassSymbolsStack to Stack from normal Vec.

[sapphi-red]

• perf(minifier): use oxc_data_structures::stack::Stack for ClassSymbolsStack #14029 👈 (View in Graphite)
• feat(mangler): mangle private class members #14027
• feat(minifier): remove unused private class members #14026
• main

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[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #14029 will not alter performance

_{Comparing 09-23-perf_minifier_use_oxc_data_structures_stack_stack_for_classsymbolsstack (c0ef5f3) with main (a05cb23)¹}

Summary

✅ 37 untouched

Footnotes

1. No successful run was found on main (0fe4d95) during the generation of this report, so a05cb23 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[overlookmotel]

I don't think the clear call should be required. From what I can see, the stack is filled and then emptied again during traversal, so it should be always be empty by exit_program anyway (and therefore still empty in the next enter_program call).

The pattern we generally use with stacks in transformer is:

struct SomeTransform {
  stack: Stack<ThingName>,
}

impl<'a> Traverse<'a> for SomeTransform {
  fn enter_program(&mut self, program: &mut Program, ctx: &mut TraverseCtx<'a>) {
    // Nothing to do. `stack` is always empty here.
  }

  fn enter_thing(&mut self, thing: &mut Thing<'a>, ctx: &mut TraverseCtx<'a> {
    self.stack.push(thing.name);
  }

  fn exit_thing(&mut self, thing: &mut Thing<'a>, ctx: &mut TraverseCtx<'a> {
    self.stack.pop().unwrap();
    // Or, if logic is simple enough that it's clear
    // there's no possibility of mismatched push-pop calls
    // unsafe { self.stack.pop_unchecked() };
  }

  #[inline] // Because it's a noop in release mode
  fn exit_program(&mut self, program: &mut Program, ctx: &mut TraverseCtx<'a>) {
    debug_assert!(self.stack.is_empty());
  }
}

This debug_assert! approach has the advantage of making sure that every push is followed by a corresponding pop, and the stack doesn't get out of sync with traversal.

---

You may find that oxc_data_structures::stack::NonEmptyStack is cheaper than Stack. That has really cheap last and last_mut methods. Downside is you have to provide a dummy first entry when creating the NonEmptyStack, but if MinifierState is being used over and over, that's a 1-off cost.

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Feel free not to take these suggestions into account. Just wanted to let you know the patterns we've found work well with the stack types, in case it's useful.

[sapphi-red]

Ah, true, clear isn't required! I saw Stack being used somewhere else and thought it might work here too. Thanks for the comment!

[sapphi-red]

Changed to NonEmptyStack 👍 Because the benchmark doesn't contain any class decls/exprs, it doesn't have any affect there. But I guess this change won't hurt anything.

[Boshen]

Merge activity

• Sep 24, 3:34 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Sep 24, 3:34 AM UTC: Boshen added this pull request to the Graphite merge queue.
• Sep 24, 3:42 AM UTC: Merged by the Graphite merge queue.