Switch to `type SymbolName unique.Handle[string]` by jakebailey · Pull Request #64699 · microsoft/TypeScript

Jake Bailey (jakebailey) · 2026-10-08T21:59:08Z

WIP, slop for testing

Symbols should share canonical names so identity checks and symbol-table lookups do not repeatedly compare string contents. Preserve textual behavior for diagnostics, emitted output, and the JavaScript API.

Known names and intermediate name operations should stay interned; repeated interning and string round trips defeat the canonical representation in frequently used lookup paths.

Symbol names need their own constructor and representation boundary, without exposing generic string handles throughout the compiler. Give name serialization a lossless escaped spelling and distinguish unset names from valid empty names.

Jake Bailey (jakebailey) · 2026-10-08T21:59:46Z

TypeScript Bot (@typescript-bot) perf test this

typescript-automation · 2026-10-08T21:59:53Z

Starting jobs; this comment will be updated as builds start and complete.

Command	Status	Results
`perf test this`	✅ Started	👀 Results

typescript-automation · 2026-10-08T22:31:24Z

Jake Bailey (@jakebailey)
The results of the perf run you requested are in!

Here they are:

tsc

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-Unions - native}
_Errors	₄₁	₄₁	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_115,276	_115,276	_~	_~	_~	_{p=1.000 n=12}
_Types	_79,613	_79,613	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{135,310k (± 0.08%)}	_{134,555k (± 0.05%)}	_{-754k (- 0.56%)}	_134,394k	_134,762k	_{p=0.000 n=12}
_{Memory Allocs}	_{2,190,636 (± 0.00%)}	_{2,279,198 (± 0.05%)}	_{🔻+88,562 (+ 4.04%)}	_2,275,969	_2,282,067	_{p=0.000 n=12}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.050s (± 2.84%)}	_{0.049s (± 3.22%)}	_~	_0.044s	_0.053s	_{p=0.502 n=12}
_{Bind Time}	_{0.015s (±13.33%)}	_{0.030s (± 7.99%)}	_{🔻+0.015s (+99.45%)}	_0.026s	_0.036s	_{p=0.000 n=12}
_{Check Time}	_{0.615s (± 0.71%)}	_{0.612s (± 0.92%)}	_~	_0.602s	_0.630s	_{p=0.162 n=12}
_{Emit Time}	_{0.329s (± 2.14%)}	_{0.338s (± 1.22%)}	_{+0.009s (+ 2.68%)}	_0.324s	_0.348s	_{p=0.034 n=12}
_{Total Time}	_{1.018s (± 0.96%)}	_{1.037s (± 0.62%)}	_{+0.019s (+ 1.88%)}	_1.021s	_1.057s	_{p=0.001 n=12}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_{845,989 (± 0.05%)}	_{845,729 (± 0.09%)}	_~	_842,740	_847,317	_{p=0.932 n=12}
_Types	_{248,124 (± 0.00%)}	_{248,123 (± 0.00%)}	_~	_248,122	_248,125	_{p=0.993 n=12}
_{Memory Used}	_{764,653k (± 0.02%)}	_{746,535k (± 0.02%)}	_{-18,119k (- 2.37%)}	_746,119k	_746,997k	_{p=0.000 n=12}
_{Memory Allocs}	_{12,925,262 (± 0.06%)}	_{13,352,078 (± 0.04%)}	_{+426,816 (+ 3.30%)}	_13,345,546	_13,372,669	_{p=0.000 n=12}
_{Config Time}	_{0.016s (± 1.97%)}	_{0.017s (± 1.07%)}	_{+0.001s (+ 3.05%)}	_0.016s	_0.017s	_{p=0.027 n=12}
_{Parse Time}	_{0.257s (± 2.58%)}	_{0.259s (± 2.82%)}	_~	_0.234s	_0.268s	_{p=0.385 n=12}
_{Bind Time}	_{0.063s (±12.33%)}	_{0.100s (±10.80%)}	_{🔻+0.037s (+59.92%)}	_0.092s	_0.150s	_{p=0.000 n=12}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=12}
_{Emit Time}	_{1.587s (± 1.21%)}	_{1.626s (± 0.86%)}	_{+0.039s (+ 2.45%)}	_1.594s	_1.679s	_{p=0.004 n=12}
_{Total Time}	_{1.937s (± 1.28%)}	_{2.014s (± 0.99%)}	_{+0.076s (+ 3.94%)}	_1.979s	_2.101s	_{p=0.000 n=12}
_{mui-docs - native}
_Errors	_11,405	_11,405	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_4,359,614	_4,359,614	_~	_~	_~	_{p=1.000 n=12}
_Types	_1,376,379	_1,376,379	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{2,874,210k (± 0.05%)}	_{2,568,218k (± 0.05%)}	_{🟩-305,992k (-10.65%)}	_2,564,693k	_2,571,397k	_{p=0.000 n=12}
_{Memory Allocs}	_{32,870,213 (± 0.08%)}	_{33,621,012 (± 0.06%)}	_{+750,799 (+ 2.28%)}	_33,575,749	_33,692,494	_{p=0.000 n=12}
_{Config Time}	_{0.020s (± 1.21%)}	_{0.020s (± 1.52%)}	_~	_0.020s	_0.021s	_{p=0.640 n=12}
_{Parse Time}	_{0.624s (± 2.60%)}	_{0.604s (± 2.39%)}	_{🟩-0.020s (- 3.14%)}	_0.568s	_0.640s	_{p=0.050 n=12}
_{Bind Time}	_{0.003s (±13.14%)}	_{0.003s (±12.54%)}	_~	_0.002s	_0.003s	_{p=1.000 n=12}
_{Check Time}	_{10.344s (± 0.63%)}	_{9.367s (± 0.38%)}	_{🟩-0.977s (- 9.44%)}	_9.291s	_9.463s	_{p=0.000 n=12}
_{Emit Time}	_{0.510s (± 1.88%)}	_{0.513s (± 1.14%)}	_~	_0.505s	_0.535s	_{p=0.199 n=12}
_{Total Time}	_{12.430s (± 0.51%)}	_{11.545s (± 0.32%)}	_{🟩-0.886s (- 7.12%)}	_11.449s	_11.644s	_{p=0.000 n=12}
_{strada-build-src - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,390,229	_1,390,229	_~	_~	_~	_{p=1.000 n=12}
_Types	_441,498	_441,498	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{1,641,820k (± 0.88%)}	_{1,623,524k (± 0.28%)}	_{-18,296k (- 1.11%)}	_1,612,197k	_1,634,391k	_{p=0.028 n=12}
_{Memory Allocs}	_{92,093,413 (± 0.16%)}	_{95,246,262 (± 0.15%)}	_{+3,152,849 (+ 3.42%)}	_94,939,040	_95,592,937	_{p=0.000 n=12}
_{Config Time}	_{0.003s (±14.60%)}	_{0.003s (±14.59%)}	_~	_0.002s	_0.004s	_{p=0.784 n=12}
_{Parse Time}	_{0.191s (± 4.22%)}	_{0.188s (± 2.57%)}	_~	_0.176s	_0.199s	_{p=0.639 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{1.820s (± 0.66%)}	_{1.888s (± 0.45%)}	_{+0.068s (+ 3.72%)}	_1.869s	_1.908s	_{p=0.000 n=12}
_{Emit Time}	_{0.305s (± 5.01%)}	_{0.321s (± 4.73%)}	_~	_0.283s	_0.372s	_{p=0.173 n=12}
_{Total Time}	_{23.652s (± 0.97%)}	_{24.999s (± 0.56%)}	_{🔻+1.347s (+ 5.70%)}	_24.737s	_25.487s	_{p=0.000 n=12}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_334,953	_334,953	_~	_~	_~	_{p=1.000 n=12}
_Types	_197,616	_197,616	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{302,588k (± 0.03%)}	_{299,768k (± 0.02%)}	_{-2,820k (- 0.93%)}	_299,594k	_299,874k	_{p=0.000 n=12}
_{Memory Allocs}	_{4,622,914 (± 0.01%)}	_{4,830,806 (± 0.01%)}	_{🔻+207,892 (+ 4.50%)}	_4,830,094	_4,831,876	_{p=0.000 n=12}
_{Config Time}	_{0.001s (±29.38%)}	_{0.001s (±65.70%)}	_~	_0.000s	_0.001s	_{p=0.193 n=12}
_{Parse Time}	_{0.092s (± 5.04%)}	_{0.095s (± 4.82%)}	_~	_0.083s	_0.110s	_{p=0.223 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{0.878s (± 0.68%)}	_{0.912s (± 0.42%)}	_{+0.034s (+ 3.83%)}	_0.900s	_0.920s	_{p=0.000 n=12}
_{Emit Time}	_{0.109s (±10.35%)}	_{0.124s (± 6.74%)}	_{🔻+0.015s (+13.72%)}	_0.098s	_0.140s	_{p=0.013 n=12}
_{Total Time}	_{1.121s (± 1.06%)}	_{1.201s (± 1.07%)}	_{🔻+0.081s (+ 7.20%)}	_1.160s	_1.235s	_{p=0.000 n=12}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_303,834	_303,834	_~	_~	_~	_{p=1.000 n=12}
_Types	_181,663	_181,663	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{263,493k (± 0.02%)}	_{260,182k (± 0.02%)}	_{-3,311k (- 1.26%)}	_259,924k	_260,272k	_{p=0.000 n=12}
_{Memory Allocs}	_{1,616,022 (± 0.01%)}	_{1,791,998 (± 0.01%)}	_{🔻+175,976 (+10.89%)}	_1,791,727	_1,792,462	_{p=0.000 n=12}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.099s (± 3.19%)}	_{0.098s (± 4.94%)}	_~	_0.089s	_0.108s	_{p=0.832 n=12}
_{Bind Time}	_{0.037s (± 9.76%)}	_{0.070s (± 7.91%)}	_{🔻+0.034s (+90.97%)}	_0.058s	_0.081s	_{p=0.000 n=12}
_{Check Time}	_{0.829s (± 0.76%)}	_{0.860s (± 0.82%)}	_{+0.031s (+ 3.69%)}	_0.844s	_0.878s	_{p=0.000 n=12}
_{Emit Time}	_{0.000s (±217.90%)}	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{0.981s (± 0.53%)}	_{1.043s (± 0.71%)}	_{🔻+0.062s (+ 6.29%)}	_1.026s	_1.069s	_{p=0.000 n=12}
_{vscode - native}
_Errors	₃₈₀	₃₈₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_11,126,412	_11,126,412	_~	_~	_~	_{p=1.000 n=12}
_Types	_3,695,451	_3,695,451	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{6,709,468k (± 0.02%)}	_{6,472,806k (± 0.02%)}	_{🟩-236,662k (- 3.53%)}	_6,468,963k	_6,477,601k	_{p=0.000 n=12}
_{Memory Allocs}	_{54,762,461 (± 0.03%)}	_{56,714,048 (± 0.02%)}	_{+1,951,587 (+ 3.56%)}	_56,703,781	_56,758,908	_{p=0.000 n=12}
_{Config Time}	_{0.073s (± 0.56%)}	_{0.074s (± 0.44%)}	_{+0.001s (+ 1.48%)}	_0.074s	_0.075s	_{p=0.000 n=12}
_{Parse Time}	_{1.812s (± 3.88%)}	_{1.836s (± 3.66%)}	_~	_1.672s	_2.035s	_{p=0.671 n=12}
_{Bind Time}	_{0.622s (±18.49%)}	_{0.831s (±15.00%)}	_{🔻+0.209s (+33.64%)}	_0.690s	_1.232s	_{p=0.018 n=12}
_{Check Time}	_{13.958s (± 1.17%)}	_{14.712s (± 0.99%)}	_{🔻+0.753s (+ 5.40%)}	_14.238s	_14.937s	_{p=0.000 n=12}
_{Emit Time}	_{4.908s (±12.67%)}	_{4.654s (± 8.71%)}	_~	_4.184s	_6.004s	_{p=0.443 n=12}
_{Total Time}	_{21.463s (± 2.41%)}	_{22.186s (± 1.51%)}	_~	_21.711s	_23.306s	_{p=0.143 n=12}
_{webpack - native}
_Errors	₅₈₉	₅₈₉	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,304,270	_1,304,270	_~	_~	_~	_{p=1.000 n=12}
_Types	_618,461	_618,461	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{958,988k (± 0.01%)}	_{925,774k (± 0.02%)}	_{🟩-33,214k (- 3.46%)}	_925,297k	_926,313k	_{p=0.000 n=12}
_{Memory Allocs}	_{6,606,657 (± 0.01%)}	_{7,086,476 (± 0.04%)}	_{🔻+479,819 (+ 7.26%)}	_7,081,900	_7,094,237	_{p=0.000 n=12}
_{Config Time}	_0.009s	_0.009s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.288s (± 3.23%)}	_{0.291s (± 3.25%)}	_~	_0.267s	_0.319s	_{p=0.744 n=12}
_{Bind Time}	_{0.086s (±20.33%)}	_{0.128s (±10.05%)}	_{🔻+0.042s (+49.03%)}	_0.107s	_0.177s	_{p=0.001 n=12}
_{Check Time}	_{2.073s (± 1.02%)}	_{2.127s (± 0.88%)}	_{+0.054s (+ 2.62%)}	_2.073s	_2.162s	_{p=0.001 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{2.491s (± 0.52%)}	_{2.591s (± 0.63%)}	_{🔻+0.101s (+ 4.03%)}	_2.558s	_2.639s	_{p=0.000 n=12}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,055,452	_1,055,452	_~	_~	_~	_{p=1.000 n=12}
_Types	_386,738	_386,738	_~	_~	_~	_{p=1.000 n=12}
_{Memory Used}	_{570,764k (± 0.03%)}	_{545,375k (± 0.03%)}	_{🟩-25,389k (- 4.45%)}	_545,072k	_545,991k	_{p=0.000 n=12}
_{Memory Allocs}	_{4,859,932 (± 0.08%)}	_{5,156,372 (± 0.09%)}	_{🔻+296,440 (+ 6.10%)}	_5,146,655	_5,173,137	_{p=0.000 n=12}
_{Config Time}	_{0.003s (± 6.23%)}	_{0.003s (± 6.23%)}	_~	_0.002s	_0.003s	_{p=1.000 n=12}
_{Parse Time}	_{0.143s (± 2.40%)}	_{0.145s (± 3.12%)}	_~	_0.131s	_0.154s	_{p=0.416 n=12}
_{Bind Time}	_{0.044s (±21.01%)}	_{0.090s (±12.08%)}	_{🔻+0.046s (+104.91%)}	_0.066s	_0.111s	_{p=0.000 n=12}
_{Check Time}	_{1.128s (± 0.48%)}	_{1.130s (± 0.74%)}	_~	_1.112s	_1.164s	_{p=0.660 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{1.324s (± 0.56%)}	_{1.374s (± 0.76%)}	_{+0.050s (+ 3.78%)}	_1.344s	_1.394s	_{p=0.000 n=12}

System info unknown

Hosts

native

Scenarios

Compiler-Unions - native
angular-1 - native
mui-docs - native
strada-build-src - native
strada-compiler - native
ts-pre-modules - native
vscode - native
webpack - native
xstate-main - native

_Benchmark	_Name	_Iterations
_Current	_pr	₁₂
_Baseline	_baseline	₁₂

lsp

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{Compiler-UnionsLSP - native}
_{Req 1 - updateOpen}	_{13ms (±10.94%)}	_{14ms (±10.03%)}	_~	_11ms	_17ms	_{p=0.513 n=12}
_{Req 2 - geterr}	_{699ms (± 0.41%)}	_{709ms (± 0.64%)}	_{+9ms (+ 1.33%)}	_697ms	_717ms	_{p=0.002 n=12}
_{Req 3 - references}	_{53ms (± 4.78%)}	_{52ms (± 7.15%)}	_~	_43ms	_62ms	_{p=0.382 n=12}
_{Req 4 - navto}	_{20ms (± 3.00%)}	_{20ms (± 6.07%)}	_~	_18ms	_26ms	_{p=0.383 n=12}
_{Req 5 - completionInfo count}	_1,363	_1,363	_~	_~	_~	_{p=1.000 n=12}
_{Req 5 - completionInfo}	_{20ms (± 7.01%)}	_{20ms (±11.54%)}	_~	_16ms	_30ms	_{p=0.136 n=12}
_{CompilerLSP - native}
_{Req 1 - updateOpen}	_{12ms (±13.27%)}	_{11ms (±10.67%)}	_~	_10ms	_15ms	_{p=1.000 n=12}
_{Req 2 - geterr}	_{298ms (± 0.64%)}	_{318ms (± 0.60%)}	_{🔻+20ms (+ 6.76%)}	_313ms	_324ms	_{p=0.000 n=12}
_{Req 3 - references}	_{50ms (± 3.62%)}	_{49ms (± 4.22%)}	_~	_44ms	_54ms	_{p=0.678 n=12}
_{Req 4 - navto}	_{17ms (± 3.43%)}	_{17ms (± 2.54%)}	_~	_15ms	_17ms	_{p=0.167 n=12}
_{Req 5 - completionInfo count}	_1,525	_1,525	_~	_~	_~	_{p=1.000 n=12}
_{Req 5 - completionInfo}	_{17ms (± 6.11%)}	_{17ms (± 6.98%)}	_~	_15ms	_21ms	_{p=0.741 n=12}

System info unknown

Hosts

native

Scenarios

CompilerLSP - native
Compiler-UnionsLSP - native
xstate-main-1-LSP - native

_Benchmark	_Name	_Iterations
_Current	_pr	₁₂
_Baseline	_baseline	₁₂

startup

Comparison Report - baseline..pr

_Metric	_baseline	_pr	_Delta	_Best	_Worst	_p-value
_{lsp-startup - native}
_{Execution time}	_{4.80ms (±365.08%)}	_{4.83ms (±365.09%)}	_{+0.03ms (+ 0.62%)}	_0.00ms	_491.10ms	_{p=0.000 n=1200}
_{tsgo-startup - native}
_{Execution time}	_{5.83ms (±365.09%)}	_{5.88ms (±365.08%)}	_{+0.04ms (+ 0.73%)}	_0.00ms	_593.40ms	_{p=0.000 n=1200}

System info unknown

Hosts

native

Scenarios

lsp-startup - native
tsgo-startup - native

_Benchmark	_Name	_Iterations
_Current	_pr	₁₂
_Baseline	_baseline	₁₂

Developer Information:

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Jake Bailey (jakebailey) added 3 commits October 8, 2026 13:51

Intern symbol names with unique handles

d74b247

Symbols should share canonical names so identity checks and symbol-table lookups do not repeatedly compare string contents. Preserve textual behavior for diagnostics, emitted output, and the JavaScript API.

Hoist fixed symbol names and preserve handle boundaries

73e4b9e

Known names and intermediate name operations should stay interned; repeated interning and string round trips defeat the canonical representation in frequently used lookup paths.

typescript-automation Bot assigned Jake Bailey (jakebailey) Oct 8, 2026

typescript-automation Bot added Author: Team For Uncommitted Bug PR for untriaged, rejected, closed or missing bug labels Oct 8, 2026

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Switch to `type SymbolName unique.Handle[string]` - #64699

Switch to `type SymbolName unique.Handle[string]`#64699
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