Skip object classification for shared type facts by Andarist · Pull Request #64188 · microsoft/TypeScript

Mateusz Burzyński (Andarist) · 2026-09-07T09:29:13Z

This allows the compiler to skip some work at times. Some of the isEmptyObjectType, isFunctionObjectType calls and alikes performed down the line can be skipped.

typescript-automation · 2026-09-07T09:29:18Z

This PR doesn't have any linked issues. Please open an issue that references this PR. From there we can discuss and prioritise.

Copilot

🟢 Approval recommended

The optimization preserves requested type facts while safely avoiding unnecessary member resolution.

Pull request overview

Optimizes type-fact computation by avoiding unnecessary object classification when all object kinds share the requested facts.

Changes:

Computes facts common to empty, function, and regular objects.
Returns shared facts early when classification cannot affect the result.

File summaries

File	Description
`tsc/internal/checker/checker.go`	Adds the shared-fact fast path.

Review details

Files reviewed: 1/1 changed files
Comments generated: 0
Review effort level: Balanced

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Jake Bailey (jakebailey) · 2026-09-08T17:49:20Z

TypeScript Bot (@typescript-bot) test it

typescript-automation · 2026-09-08T17:49:26Z

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

Command	Status	Results
`test top400`	✅ Started	✅ Results
`user test this`	✅ Started	✅ Results
`run dt`	✅ Started
`perf test this faster`	✅ Started	👀 Results

typescript-automation · 2026-09-08T18:17:12Z

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	_115,480	_115,445	_{-35 (- 0.03%)}	_~	_~	_{p=0.000 n=12}
_Types	_96,945	_96,944	_{-1 (- 0.00%)}	_~	_~	_{p=0.000 n=12}
_{Memory Used}	_{149,083k (± 0.47%)}	_{148,938k (± 0.64%)}	_~	_146,630k	_151,494k	_{p=0.713 n=12}
_{Memory Allocs}	_{2,271,360 (± 0.01%)}	_{2,271,116 (± 0.00%)}	_{-243 (- 0.01%)}	_2,270,986	_2,271,467	_{p=0.007 n=12}
_{Config Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.042s (± 5.44%)}	_{0.041s (± 3.31%)}	_~	_0.039s	_0.046s	_{p=0.503 n=12}
_{Bind Time}	_{0.013s (±15.05%)}	_{0.012s (± 9.27%)}	_~	_0.010s	_0.015s	_{p=0.848 n=12}
_{Check Time}	_{0.493s (± 1.05%)}	_{0.493s (± 1.21%)}	_~	_0.481s	_0.508s	_{p=0.831 n=12}
_{Emit Time}	_{0.268s (± 1.34%)}	_{0.269s (± 2.58%)}	_~	_0.252s	_0.289s	_{p=0.723 n=12}
_{Total Time}	_{0.821s (± 0.75%)}	_{0.822s (± 1.25%)}	_~	_0.794s	_0.846s	_{p=0.989 n=12}
_{angular-1 - native}
_Errors	₃	₃	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_{847,027 (± 0.11%)}	_{845,757 (± 0.10%)}	_~	_843,670	_848,103	_{p=0.068 n=12}
_Types	_{249,854 (± 0.00%)}	_{249,801 (± 0.00%)}	_{-53 (- 0.02%)}	_249,799	_249,805	_{p=0.000 n=12}
_{Memory Used}	_{794,040k (± 0.09%)}	_{793,372k (± 0.08%)}	_~	_791,977k	_795,524k	_{p=0.114 n=12}
_{Memory Allocs}	_{12,955,126 (± 0.05%)}	_{12,953,592 (± 0.03%)}	_~	_12,947,426	_12,969,234	_{p=0.478 n=12}
_{Config Time}	_0.016s	_0.016s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.274s (± 2.44%)}	_{0.271s (± 1.70%)}	_~	_0.262s	_0.281s	_{p=0.325 n=12}
_{Bind Time}	_{0.064s (±13.12%)}	_{0.060s (± 4.98%)}	_~	_0.057s	_0.075s	_{p=0.740 n=12}
_{Check Time}	_0s	_0s	_~	_~	_~	_{p=1.000 n=12}
_{Emit Time}	_{1.638s (± 1.20%)}	_{1.625s (± 0.80%)}	_~	_1.606s	_1.685s	_{p=0.091 n=12}
_{Total Time}	_{2.009s (± 1.36%)}	_{1.989s (± 0.93%)}	_~	_1.960s	_2.072s	_{p=0.070 n=12}
_{mui-docs - native}
_Errors	_{11,276 (± 0.03%)}	_{11,274 (± 0.05%)}	_~	_11,259	_11,281	_{p=0.765 n=12}
_Symbols	_4,267,465	_4,262,971	_{-4,494 (- 0.11%)}	_~	_~	_{p=0.000 n=12}
_Types	_1,475,860	_1,475,558	_{-302 (- 0.02%)}	_~	_~	_{p=0.000 n=12}
_{Memory Used}	_{4,672,776k (± 0.03%)}	_{4,670,728k (± 0.02%)}	_{-2,048k (- 0.04%)}	_4,667,552k	_4,674,841k	_{p=0.039 n=12}
_{Memory Allocs}	_{42,719,555 (± 0.04%)}	_{42,717,437 (± 0.03%)}	_~	_42,682,970	_42,752,562	_{p=0.977 n=12}
_{Config Time}	_{0.016s (± 2.08%)}	_{0.016s (± 2.12%)}	_~	_0.015s	_0.016s	_{p=1.000 n=12}
_{Parse Time}	_{0.552s (± 2.13%)}	_{0.538s (± 2.84%)}	_~	_0.499s	_0.569s	_{p=0.173 n=12}
_{Bind Time}	_0.002s	_0.002s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{16.673s (± 0.51%)}	_{16.753s (± 0.49%)}	_~	_16.547s	_16.884s	_{p=0.147 n=12}
_{Emit Time}	_{0.441s (± 2.06%)}	_{0.476s (±15.29%)}	_~	_0.431s	_0.840s	_{p=0.353 n=12}
_{Total Time}	_{18.429s (± 0.54%)}	_{18.559s (± 0.43%)}	_~	_18.286s	_18.744s	_{p=0.052 n=12}
_{strada-build-src - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,394,252	_1,392,696	_{-1,556 (- 0.11%)}	_~	_~	_{p=0.000 n=12}
_Types	_443,418	_443,410	_{-8 (- 0.00%)}	_~	_~	_{p=0.000 n=12}
_{Memory Used}	_{1,649,289k (± 0.30%)}	_{1,643,730k (± 0.24%)}	_{-5,559k (- 0.34%)}	_1,630,027k	_1,650,341k	_{p=0.039 n=12}
_{Memory Allocs}	_{97,074,757 (± 0.04%)}	_{97,019,652 (± 0.04%)}	_~	_96,929,038	_97,096,131	_{p=0.060 n=12}
_{Config Time}	_{0.004s (±20.20%)}	_{0.004s (±21.07%)}	_~	_0.002s	_0.008s	_{p=0.611 n=12}
_{Parse Time}	_{0.193s (± 2.36%)}	_{0.196s (± 1.89%)}	_~	_0.187s	_0.204s	_{p=0.139 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{1.802s (± 0.32%)}	_{1.800s (± 0.35%)}	_~	_1.783s	_1.822s	_{p=0.370 n=12}
_{Emit Time}	_{0.272s (± 6.87%)}	_{0.275s (± 5.88%)}	_~	_0.239s	_0.322s	_{p=0.681 n=12}
_{Total Time}	_{24.634s (± 0.73%)}	_{24.675s (± 0.61%)}	_~	_24.404s	_25.062s	_{p=0.799 n=12}
_{strada-compiler - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_337,531	_337,418	_{-113 (- 0.03%)}	_~	_~	_{p=0.000 n=12}
_Types	_198,830	_198,827	_{-3 (- 0.00%)}	_~	_~	_{p=0.000 n=12}
_{Memory Used}	_{319,553k (± 0.03%)}	_{319,571k (± 0.07%)}	_~	_319,276k	_320,549k	_{p=0.523 n=12}
_{Memory Allocs}	_{4,672,972 (± 0.01%)}	_{4,672,884 (± 0.01%)}	_~	_4,671,748	_4,674,020	_{p=0.799 n=12}
_{Config Time}	_0.001s	_0.001s	_~	_~	_~	_{p=1.000 n=12}
_{Parse Time}	_{0.113s (± 6.21%)}	_{0.114s (± 5.67%)}	_~	_0.100s	_0.132s	_{p=0.701 n=12}
_{Bind Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Check Time}	_{1.045s (± 0.32%)}	_{1.048s (± 0.56%)}	_~	_1.037s	_1.062s	_{p=0.619 n=12}
_{Emit Time}	_{0.129s (±11.11%)}	_{0.143s (±10.08%)}	_~	_0.102s	_0.160s	_{p=0.097 n=12}
_{Total Time}	_{1.341s (± 0.93%)}	_{1.356s (± 0.75%)}	_~	_1.334s	_1.382s	_{p=0.103 n=12}
_{ts-pre-modules - native}
_Errors	₈₇	₈₇	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_305,179	_305,172	_{-7 (- 0.00%)}	_~	_~	_{p=0.000 n=12}
_Types	_181,876	_181,874	_{-2 (- 0.00%)}	_~	_~	_{p=0.000 n=12}
_{Memory Used}	_{277,217k (± 0.02%)}	_{277,119k (± 0.02%)}	_~	_276,825k	_277,224k	_{p=0.071 n=12}
_{Memory Allocs}	_{1,641,939 (± 0.01%)}	_{1,641,910 (± 0.01%)}	_~	_1,641,326	_1,642,432	_{p=0.843 n=12}
_{Config Time}	_{0.000s (±146.91%)}	_{0.000s (±113.79%)}	_~	_0.000s	_0.001s	_{p=1.000 n=12}
_{Parse Time}	_{0.098s (± 5.01%)}	_{0.101s (± 4.20%)}	_~	_0.091s	_0.115s	_{p=0.223 n=12}
_{Bind Time}	_{0.039s (±10.61%)}	_{0.038s (±10.42%)}	_~	_0.031s	_0.052s	_{p=0.966 n=12}
_{Check Time}	_{0.835s (± 0.61%)}	_{0.836s (± 0.57%)}	_~	_0.823s	_0.848s	_{p=0.765 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{0.986s (± 0.93%)}	_{0.989s (± 0.82%)}	_~	_0.971s	_1.011s	_{p=0.504 n=12}
_{vscode - native}
_Errors	₃₄₉	₃₄₉	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_8,463,646	_8,451,219	_{-12,427 (- 0.15%)}	_~	_~	_{p=0.000 n=12}
_Types	_2,898,728	_2,897,065	_{-1,663 (- 0.06%)}	_~	_~	_{p=0.000 n=12}
_{Memory Used}	_{5,713,459k (± 0.02%)}	_{5,709,986k (± 0.02%)}	_{-3,473k (- 0.06%)}	_5,707,415k	_5,712,690k	_{p=0.000 n=12}
_{Memory Allocs}	_{43,911,056 (± 0.02%)}	_{43,898,750 (± 0.03%)}	_{-12,306 (- 0.03%)}	_43,886,057	_43,968,153	_{p=0.000 n=12}
_{Config Time}	_{0.064s (± 0.51%)}	_{0.064s (± 1.65%)}	_~	_0.063s	_0.069s	_{p=0.751 n=12}
_{Parse Time}	_{1.655s (± 3.46%)}	_{1.681s (± 2.63%)}	_~	_1.566s	_1.760s	_{p=0.468 n=12}
_{Bind Time}	_{0.440s (±18.14%)}	_{0.402s (±19.07%)}	_{🟩-0.037s (- 8.47%)}	_0.333s	_0.749s	_{p=0.047 n=12}
_{Check Time}	_{10.236s (± 1.64%)}	_{10.285s (± 1.23%)}	_~	_9.771s	_10.452s	_{p=0.682 n=12}
_{Emit Time}	_{3.738s (±13.15%)}	_{3.547s (±11.31%)}	_~	_3.168s	_4.856s	_{p=0.355 n=12}
_{Total Time}	_{16.228s (± 2.28%)}	_{16.071s (± 2.05%)}	_~	_15.679s	_17.257s	_{p=0.198 n=12}
_{webpack - native}
_Errors	₅₆₀	₅₆₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_929,346	_927,905	_{-1,441 (- 0.16%)}	_~	_~	_{p=0.000 n=12}
_Types	_426,678	_426,651	_{-27 (- 0.01%)}	_~	_~	_{p=0.000 n=12}
_{Memory Used}	_{718,503k (± 0.02%)}	_{718,006k (± 0.02%)}	_{-498k (- 0.07%)}	_717,571k	_718,465k	_{p=0.000 n=12}
_{Memory Allocs}	_{4,699,968 (± 0.02%)}	_{4,699,041 (± 0.02%)}	_~	_4,697,557	_4,702,644	_{p=0.052 n=12}
_{Config Time}	_0.008s	_{0.008s (± 5.88%)}	_~	_0.008s	_0.010s	_{p=0.478 n=12}
_{Parse Time}	_{0.230s (± 1.97%)}	_{0.234s (± 2.91%)}	_~	_0.218s	_0.252s	_{p=0.310 n=12}
_{Bind Time}	_{0.045s (± 0.93%)}	_{0.051s (±12.36%)}	_{🔻+0.006s (+13.12%)}	_0.045s	_0.074s	_{p=0.006 n=12}
_{Check Time}	_{1.255s (± 0.64%)}	_{1.282s (± 2.12%)}	_~	_1.238s	_1.368s	_{p=0.103 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{1.563s (± 0.76%)}	_{1.602s (± 2.32%)}	_~	_1.537s	_1.741s	_{p=0.057 n=12}
_{xstate-main - native}
_Errors	₀	₀	_~	_~	_~	_{p=1.000 n=12}
_Symbols	_1,022,532	_1,017,683	_{-4,849 (- 0.47%)}	_~	_~	_{p=0.000 n=12}
_Types	_376,962	_376,476	_{-486 (- 0.13%)}	_~	_~	_{p=0.000 n=12}
_{Memory Used}	_{603,501k (± 0.01%)}	_{601,585k (± 0.02%)}	_{-1,916k (- 0.32%)}	_601,315k	_601,918k	_{p=0.000 n=12}
_{Memory Allocs}	_{4,754,287 (± 0.04%)}	_{4,745,354 (± 0.04%)}	_{-8,933 (- 0.19%)}	_4,739,818	_4,750,272	_{p=0.000 n=12}
_{Config Time}	_{0.003s (±12.54%)}	_{0.003s (±10.34%)}	_~	_0.002s	_0.003s	_{p=0.667 n=12}
_{Parse Time}	_{0.146s (± 3.32%)}	_{0.151s (± 3.19%)}	_~	_0.141s	_0.163s	_{p=0.202 n=12}
_{Bind Time}	_{0.043s (±17.16%)}	_{0.050s (±15.63%)}	_~	_0.034s	_0.070s	_{p=0.171 n=12}
_{Check Time}	_{1.047s (± 1.52%)}	_{1.086s (± 3.32%)}	_{+0.040s (+ 3.79%)}	_1.023s	_1.235s	_{p=0.011 n=12}
_{Emit Time}	_0.000s	_0.000s	_~	_~	_~	_{p=1.000 n=12}
_{Total Time}	_{1.249s (± 1.35%)}	_{1.302s (± 3.25%)}	_{🔻+0.053s (+ 4.24%)}	_1.223s	_1.460s	_{p=0.017 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

Developer Information:

Download Benchmarks

typescript-automation · 2026-09-08T18:17:13Z

Jake Bailey (@jakebailey) Here are the results of running the user tests with tsc comparing main and refs/pull/64188/merge:

There were infrastructure failures potentially unrelated to your change:

2 instances of "Package install failed"
1 instance of "Git clone failed"

Otherwise...

Everything looks good!

typescript-automation · 2026-09-08T19:02:56Z

Jake Bailey (@jakebailey) Here are the results of running the top 400 repos with tsc comparing main and refs/pull/64188/merge:

Everything looks good!

Skip object classification for shared type facts

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Copilot AI balanced review requested due to automatic review settings September 7, 2026 09:29

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Skip object classification for shared type facts - #64188

Skip object classification for shared type facts#64188
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