Avoid FieldVector outer constructor inference

[charleskawczynski]

I realized that most of the allocations in the callbacks are actually coming from inference in the FieldVector outer constructor:

This PR should (hopefully) avoid this, by calling the outer constructor where the undertype is pre-specified.

[charleskawczynski]

Also, I plan to update the flame allocation tests once we get numbers from CI.

[charleskawczynski]

Allocations in the callbacks flame in this PR:

[simonbyrne]

should we just @nospecialize the constructor?

[charleskawczynski]

should we just @nospecialize the constructor?

Will that help? I think it's the recursive promote_type (T = promote_type(map(RecursiveArrayTools.recursive_bottom_eltype, values)...,)) that's type unstable. I think it's okay so long we avoid it in hot loops 🤷🏻

[charleskawczynski]

I realized that most of the allocations in the callbacks are actually coming from inference in the FieldVector outer constructor:

Correction: most of the allocations in the callbacks that Profile.allocs sees (see JuliaLang/julia#50187)

[charleskawczynski]

bors r+

[bors]

Build failed:

• buildkite/climaatmos-ci

[charleskawczynski]

bors r+

[bors]

Build succeeded!

The publicly hosted instance of bors-ng is deprecated and will go away soon.

If you want to self-host your own instance, instructions are here.
For more help, visit the forum.

If you want to switch to GitHub's built-in merge queue, visit their help page.

• buildkite/climaatmos-ci
• docbuild
• format