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Presize checker type-list cache keys - #64777
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The reservation logic preserves byte-stream behavior and is covered across inline and overflow boundaries.
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What changed in this PR
Presizes checker cache-key buffers to avoid repeated allocations while preserving encoded hashes.
Changes:
- Adds capacity reservation for type-list encoding.
- Tests hash stability and allocation boundaries.
- Adds focused allocation benchmarks.
| File | Description |
|---|---|
tsc/internal/checker/checker.go |
Reserves type-list key capacity before encoding. |
tsc/internal/checker/types_test.go |
Adds correctness, allocation, and benchmark coverage. |
tsc/internal/checker/checker_test.go |
Benchmarks fresh-program checking. |
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Large type lists repeatedly grow temporary hash buffers even though
their encoded length is already known. These discarded allocations
account for a substantial part of checker allocation traffic.
Reserve enough capacity before writing each list, retaining the small
inline path and the exact existing hash byte stream. Allocation tests
cover the inline boundary and large lists, and a fresh-program benchmark
includes parsing and binding rather than relying only on warmed ASTs.
CPU wall timings are noisy on this machine; report bytes and allocation
counts instead.
goos: linux
goarch: amd64
pkg: github.com/microsoft/TypeScript/tsc/internal/checker
cpu: Intel(R) Core(TM) i9-10900K CPU @ 3.70GHz
│ key-before.txt │ key-reserve.txt │
│ B/op │ B/op vs base │
TypeListKey/8-20 0.000 ± 0% 0.000 ± 0% ~ (p=1.000 n=6) ¹
TypeListKey/46-20 0.000 ± 0% 0.000 ± 0% ~ (p=1.000 n=6) ¹
TypeListKey/47-20 576.0 ± 0% 208.0 ± 0% -63.89% (p=0.002 n=6)
TypeListKey/256-20 2.375Ki ± 0% 1.125Ki ± 0% -52.63% (p=0.002 n=6)
TypeListKey/4096-20 81.25Ki ± 0% 18.00Ki ± 0% -77.85% (p=0.002 n=6)
geomean ² -48.03% ²
¹ all samples are equal
² summaries must be >0 to compute geomean
│ key-before.txt │ key-reserve.txt │
│ allocs/op │ allocs/op vs base │
TypeListKey/8-20 0.000 ± 0% 0.000 ± 0% ~ (p=1.000 n=6) ¹
TypeListKey/46-20 0.000 ± 0% 0.000 ± 0% ~ (p=1.000 n=6) ¹
TypeListKey/47-20 2.000 ± 0% 1.000 ± 0% -50.00% (p=0.002 n=6)
TypeListKey/256-20 4.000 ± 0% 1.000 ± 0% -75.00% (p=0.002 n=6)
TypeListKey/4096-20 13.000 ± 0% 1.000 ± 0% -92.31% (p=0.002 n=6)
geomean ² -60.50% ²
¹ all samples are equal
² summaries must be >0 to compute geomean
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Large type lists repeatedly grow temporary hash buffers even though their encoded size is known up front.
Part of the memory optimization stack summarized in #64734.