57 lines
2.7 KiB
Markdown
57 lines
2.7 KiB
Markdown
# JVM-only Performance Optimization Plan (Saved)
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Date: 2025-11-10 22:14 (local)
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This document captures the agreed next optimization steps so we can restore the plan later if needed.
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## Objectives
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- Reduce overhead on the call/argument path.
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- Extend and harden PIC performance (fields/methods/locals).
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- Improve R-value fast paths and interpreter hot nodes (loops, ranges, lists).
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- Make scope frame pooling thread-safe on JVM so it can be enabled by default later.
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- Keep semantics correct and all JVM tests green.
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## Prioritized tasks (now)
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1) Call/argument path: fewer allocs, tighter fast paths
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- Extend small-arity zero-alloc path to 6–8 args; benchmark with `CallMixedArityBenchmarkTest`.
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- Splat handling: fast-path single-list splats; benchmark with `CallSplatBenchmarkTest`.
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- Arg builder micro-optimizations: capacity hints, avoid redundant copies, inline simple branches.
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- Optional-chaining fast return (`SKIP_ARGS_ON_NULL_RECEIVER`) coverage audit, add A/B bench.
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2) Scope frame pooling: per-thread safety on JVM
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- Replace global deque with ThreadLocal pool on JVM (and Android) actuals.
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- Keep `frameId` uniqueness and pool size cap.
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- Verify with `DeepPoolingStressJvmTest`, `CallPoolingBenchmarkTest`, and spot benches.
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- Do NOT flip default yet; keep `SCOPE_POOL=false` unless explicitly approved.
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## Next tasks (queued)
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3) PICs: cheaper misses, broader hits
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- Method PIC 2→3/4 entries (tiny LRU); validate with `PicInvalidationJvmTest`.
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- Field PIC micro-fast path for read-then-write pairs.
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4) Locals and slots
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- Ensure `EMIT_FAST_LOCAL_REFS` coverage across compiler sites.
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- Pre-size `slots`/`nameToSlot` when local counts are known; re-run `LocalVarBenchmarkTest`.
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5) R-value fast path coverage
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- Cover index reads on primitive lists, pure receivers, assignment RHS where safe.
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- Add benches in `ExpressionBenchmarkTest`.
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6) Collections & ranges
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- Tight counted loop for `(Int..Int)` in `for`.
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- Primitive-specialized `ObjList` ops (`map`, `filter`, `sum`, `contains`) under `PRIMITIVE_FASTOPS`.
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7) Regex and string ops
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- Cache compiled regex for string literals at compile time; tiny LRU for dynamic patterns under a new `REGEX_CACHE` flag.
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8) JIT micro-tweaks
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- Inline tiny helpers; prefer arrays for hot buffers; finalize hot classes where safe.
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## Validation matrix
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- Always re-run: `CallBenchmarkTest`, `CallMixedArityBenchmarkTest`, `PicBenchmarkTest`, `ExpressionBenchmarkTest`, `ArithmeticBenchmarkTest`, `CallPoolingBenchmarkTest`, `DeepPoolingStressJvmTest`.
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- Use 3× medians where comparing flags; keep `:lynglib:jvmTest` green.
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## Notes
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- All risky changes remain flag-guarded and JVM-only where applicable.
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- Documentation and perf tables updated after each cycle.
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