turbo: One canonical instance per type (3% faster) - #6261
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August 24, 2026 21:49
This is ported over from PHPantom and how it handles types internally. The benefits aren't as big as I had hoped since part of it was already being performed in the majority of cases, but it still provided a very real 3% improvement to turbo's performance. Keep one canonical instance per distinct type value, keyed by the same 128-bit structural hash the memo already computes. Operations that reach the same value by different routes then hand back the same object, so the identity checks already on the hot paths — pt_types_identical_or_equal() on scope merges, `$a === $b` in TypeCombinator::doUnion() — decide comparisons that used to recurse into two graphs. Entries are borrowed exactly like the memo's: a weak map whose dtor releases the slot, so a canonical instance is retained only as long as some live scope holds it anyway. The open-addressing table is now a SlotTable shared by the memo and the intern table. Worth -3.1% user CPU on serial self-analysis (81.8 -> 79.2 s, three interleaved rotated rounds). Instrumented over src/Type + src/Analyser: 793k TypeCombinator calls, 184k memo misses, and 110,874 of those misses (60%) recompute a value that already exists — it reduces the lifetime type instance count by 60%, though since they're short-lived there's no real memory benefit to this; only 73k distinct values are ever canonical. Every substitution was verified equals()-true and describe()-identical. Peak RSS is unchanged — the deduplicated results are short-lived, and peak RSS is set by reflection and parser state instead. Interning is only sound because doUnion() now returns the same type for equal array operands as for identical ones; before that fix, making the operands identical changed inference at tests/PHPStan/Rules/Variables/data/bug-8113.php:47 and analysis output was no longer identical with the extension on and off. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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August 24, 2026 21:59
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This is ported over from PHPantom and how it handles types internally. The benefits aren't as big as I had hoped since part of it was already being performed in the majority of cases but it still provided a very real 3% improvement to turbo's performance.
It reduces life time type instances by 60% but since they are short lived there's no real memory benefit to this.
Entries are borrowed exactly like the memo's: a weak map whose dtor releases the slot, so a canonical instance is retained only as long as some live scope holds it anyway. The open-addressing table is now a SlotTable shared by the memo and the intern table.
Interning is only sound because doUnion() now returns the same type for equal array operands as for identical ones; before that fix, making the operands identical changed inference at tests/PHPStan/Rules/Variables/data/bug-8113.php:47 and analysis output was no longer identical with the extension on and off.