[turbopack] Optimize TaskInput implementations (#94202)
# What
Replace the `derive` macros for TaskInput with a proc macro
`[turbo_tasks::task_input]` (and analogous support inside of the
`turbo_tasks::value` macro.
Introduce a hand written `CloneResolved` future type for TaskInput
implementations that are always resolved.
# Why
This allows us to take advantage of the `NonLocalValue` marker trait. If
a type is `NonLocalValue` then `TaskInput` can have trivial
`is_resolved` and `resolve_input` implementations. This applies to the
vast majority of TaskInputs but the current `derive` implementation
always produces a recursive `async` `resolve_input` implementation but
it is rarely needed and rustc/llvm do a bad job of optimizing it.
## Code-size impact
`next-swc.darwin-arm64.node` — release profile, `pnpm swc-build-native
--release`, macOS aarch64.
| Metric | canary | this branch | Δ bytes | Δ % |
| --- | ---: | ---: | ---: | ---: |
| Raw `.node` | 124,494,592 | 124,217,280 | −277,312 | −0.22% |
| Stripped (`strip -x`) | 84,294,000 | 84,013,136 | −280,864 | −0.33% |
| Stripped + gzip -9 | 29,123,538 | 28,898,920 | −224,618 | −0.77% |
## Performance
A similar measurement of performance was neutral
| Metric | canary | temporary | Δ | % |
|---|---|---|---|---|
| wall time (s) | 42.659 ± 1.851 | 42.501 ± 2.028 | −0.158 | −0.4% |
| user time (s) | 294.322 ± 1.834 | 293.207 ± 2.070 | −1.115 | −0.4% |
| sys time (s) | 74.158 ± 4.197 | 73.543 ± 5.725 | −0.615 | −0.8% |
| MaxRSS (MB) | 13650.1 ± 66.0 | 13610.1 ± 57.5 | −40.0 | −0.3% |
All deltas are smaller than one standard deviation — statistically
indistinguishable from noise on this benchmark, as expected for a small
optimization.
