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Compact checker type metadata - #64774
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Jake Bailey (jakebailey) merged 1 commit intoOct 14, 2026
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Each type carries a self-referential interface solely to recover its concrete representation. That costs space in every type and adds GC pointer work even though the representation is fixed at construction. A compact concrete-kind tag saves 16 bytes per type on 64-bit hosts. Keep it separate from mutable semantic flags so casts stay valid as checking discovers more information.
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Jake Bailey (jakebailey)
added this pull request to stack #64792
October 13, 2026 17:37
Jake Bailey (jakebailey)
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Jake Bailey (jakebailey)
marked this pull request as ready for review
October 13, 2026 17:41
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🔵 Needs a closer look
The foundational unsafe-pointer representation change affects every checker type and warrants final human validation.
0 open findings
What changed in this PR
Replaces self-referential type metadata with compact kind tags and offset-zero casts, reducing checker memory usage.
Changes:
- Adds tagged concrete and base-type casts with layout assertions.
- Updates type construction and tracing.
- Adds cast, allocation-lifetime, size tests, and a checker benchmark.
| File | Description |
|---|---|
tsc/internal/checker/types.go |
Defines compact type metadata and casts. |
tsc/internal/checker/checker.go |
Assigns concrete kinds during construction. |
tsc/internal/checker/tracer.go |
Uses kind-aware intrinsic access. |
tsc/internal/checker/types_test.go |
Tests casts and header size. |
tsc/internal/checker/checker_test.go |
Tests allocation lifetime and benchmarks checking. |
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Jake Bailey (jakebailey)
removed this pull request from stack #64792
October 13, 2026 20:15
Jake Bailey (jakebailey)
added this pull request to stack #64805
October 13, 2026 20:16
Jake Bailey (jakebailey)
removed this pull request from stack #64805
October 13, 2026 20:49
Jake Bailey (jakebailey)
added this pull request to stack #64806
October 13, 2026 20:50
Anders Hejlsberg (ahejlsberg)
approved these changes
Oct 13, 2026
Jake Bailey (jakebailey)
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October 14, 2026 01:07
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Each type carries a self-referential interface solely to recover its concrete representation. Replace it with a compact concrete-kind tag, separate from the mutable semantic flags, and recover the concrete type from its offset-zero header.
Part of the memory optimization stack summarized in #64734.