Less template literal and string literal reduction

[PranavSenthilnathan]

Checking perf impact of the naive change.

Fixes #56081

[PranavSenthilnathan]

@typescript-bot test this
@typescript-bot perf test this
@typescript-bot user test this

[jakebailey]

@typescript-bot test this
@typescript-bot perf test this
@typescript-bot user test this

I don't think you're on the author list so that doesn't work, though maybe it's some other list that does it.

[typescript-bot]

Heya @jakebailey, I've started to run the regular perf test suite on this PR at 8e76d16. You can monitor the build here.

Update: The results are in!

[typescript-bot]

Heya @jakebailey, I've started to run the diff-based user code test suite on this PR at 8e76d16. You can monitor the build here.

Update: The results are in!

[jakebailey]

What test case are you looking at for this? #52345?

[PranavSenthilnathan]

Updated comment. It's #56081

[typescript-bot]

@jakebailey Here are the results of running the user test suite comparing main and refs/pull/56165/merge:

There were infrastructure failures potentially unrelated to your change:

• 3 instances of "Package install failed"
• 1 instance of "Unknown failure"

Otherwise...

Everything looks good!

[typescript-bot]

@jakebailey
The results of the perf run you requested are in!

Here they are:

Compiler

Comparison Report - baseline..pr

Metric	baseline	pr	Delta	Best	Worst	p-value
Angular - node (v18.15.0, x64)
Memory used	295,123k (± 0.01%)	295,097k (± 0.01%)	~	295,046k	295,160k	p=0.199 n=6
Parse Time	2.63s (± 0.57%)	2.63s (± 0.29%)	~	2.62s	2.64s	p=0.503 n=6
Bind Time	0.84s (± 0.90%)	0.84s (± 1.30%)	~	0.83s	0.85s	p=0.865 n=6
Check Time	8.06s (± 0.31%)	8.06s (± 0.29%)	~	8.03s	8.10s	p=0.935 n=6
Emit Time	7.08s (± 0.12%)	7.06s (± 0.29%)	~	7.03s	7.08s	p=0.119 n=6
Total Time	18.61s (± 0.14%)	18.58s (± 0.19%)	~	18.53s	18.63s	p=0.076 n=6
Compiler-Unions - node (v18.15.0, x64)
Memory used	192,610k (± 1.56%)	193,587k (± 1.64%)	~	190,674k	196,533k	p=0.471 n=6
Parse Time	1.35s (± 1.30%)	1.36s (± 1.27%)	~	1.34s	1.38s	p=0.278 n=6
Bind Time	0.73s (± 0.00%)	0.73s (± 0.00%)	~	0.73s	0.73s	p=1.000 n=6
Check Time	9.18s (± 0.17%)	9.19s (± 0.34%)	~	9.13s	9.21s	p=0.413 n=6
Emit Time	2.65s (± 0.52%)	2.63s (± 0.40%)	~	2.62s	2.65s	p=0.161 n=6
Total Time	13.90s (± 0.22%)	13.91s (± 0.17%)	~	13.88s	13.93s	p=0.569 n=6
Monaco - node (v18.15.0, x64)
Memory used	347,301k (± 0.00%)	347,299k (± 0.00%)	~	347,276k	347,314k	p=0.630 n=6
Parse Time	2.46s (± 0.33%)	2.46s (± 0.60%)	~	2.44s	2.48s	p=0.508 n=6
Bind Time	0.94s (± 0.43%)	0.94s (± 0.00%)	~	0.94s	0.94s	p=0.405 n=6
Check Time	6.92s (± 0.33%)	6.92s (± 0.32%)	~	6.90s	6.96s	p=1.000 n=6
Emit Time	4.02s (± 0.44%)	4.02s (± 0.27%)	~	4.01s	4.04s	p=0.806 n=6
Total Time	14.34s (± 0.17%)	14.34s (± 0.27%)	~	14.30s	14.40s	p=0.935 n=6
TFS - node (v18.15.0, x64)
Memory used	302,535k (± 0.01%)	302,526k (± 0.01%)	~	302,486k	302,541k	p=0.688 n=6
Parse Time	2.00s (± 0.73%)	2.00s (± 0.52%)	~	1.99s	2.02s	p=1.000 n=6
Bind Time	1.00s (± 0.00%)	1.01s (± 1.46%)	~	0.99s	1.03s	p=0.295 n=6
Check Time	6.26s (± 0.42%)	6.25s (± 0.54%)	~	6.22s	6.31s	p=0.573 n=6
Emit Time	3.56s (± 0.58%)	3.56s (± 0.50%)	~	3.53s	3.58s	p=0.570 n=6
Total Time	12.81s (± 0.17%)	12.82s (± 0.17%)	~	12.79s	12.85s	p=0.571 n=6
material-ui - node (v18.15.0, x64)
Memory used	470,481k (± 0.00%)	470,483k (± 0.00%)	~	470,453k	470,504k	p=0.688 n=6
Parse Time	2.58s (± 0.53%)	2.58s (± 0.62%)	~	2.56s	2.61s	p=0.315 n=6
Bind Time	1.00s (± 1.21%)	0.99s (± 1.22%)	~	0.98s	1.01s	p=0.680 n=6
Check Time	16.62s (± 0.34%)	16.59s (± 0.29%)	~	16.52s	16.66s	p=0.470 n=6
Emit Time	0.00s (± 0.00%)	0.00s (± 0.00%)	~	0.00s	0.00s	p=1.000 n=6
Total Time	20.19s (± 0.38%)	20.17s (± 0.28%)	~	20.08s	20.25s	p=0.575 n=6
xstate - node (v18.15.0, x64)
Memory used	512,617k (± 0.01%)	512,621k (± 0.01%)	~	512,558k	512,726k	p=0.936 n=6
Parse Time	3.27s (± 0.42%)	3.28s (± 0.32%)	~	3.26s	3.29s	p=0.241 n=6
Bind Time	1.55s (± 0.26%)	1.55s (± 0.53%)	~	1.53s	1.55s	p=0.218 n=6
Check Time	2.88s (± 1.49%)	2.86s (± 1.01%)	~	2.82s	2.89s	p=0.574 n=6
Emit Time	0.08s (± 0.00%)	0.08s (± 0.00%)	~	0.08s	0.08s	p=1.000 n=6
Total Time	7.77s (± 0.68%)	7.75s (± 0.38%)	~	7.70s	7.78s	p=0.521 n=6

System info unknown

Hosts

• node (v18.15.0, x64)

Scenarios

• Angular - node (v18.15.0, x64)
• Compiler-Unions - node (v18.15.0, x64)
• Monaco - node (v18.15.0, x64)
• TFS - node (v18.15.0, x64)
• material-ui - node (v18.15.0, x64)
• xstate - node (v18.15.0, x64)

Benchmark	Name	Iterations
Current	pr	6
Baseline	baseline	6

tsserver

Comparison Report - baseline..pr

Metric	baseline	pr	Delta	Best	Worst	p-value
Compiler-UnionsTSServer - node (v18.15.0, x64)
Req 1 - updateOpen	2,376ms (± 1.44%)	2,360ms (± 1.26%)	~	2,335ms	2,412ms	p=0.575 n=6
Req 2 - geterr	5,339ms (± 1.13%)	5,446ms (± 1.13%)	+107ms (+ 2.01%)	5,322ms	5,483ms	p=0.016 n=6
Req 3 - references	326ms (± 0.19%)	327ms (± 0.81%)	~	325ms	332ms	p=0.557 n=6
Req 4 - navto	278ms (± 1.26%)	273ms (± 1.29%)	~	271ms	280ms	p=0.115 n=6
Req 5 - completionInfo count	1,356 (± 0.00%)	1,356 (± 0.00%)	~	1,356	1,356	p=1.000 n=6
Req 5 - completionInfo	78ms (± 4.93%)	86ms (± 7.24%)	~	74ms	90ms	p=0.075 n=6
CompilerTSServer - node (v18.15.0, x64)
Req 1 - updateOpen	2,490ms (± 1.06%)	2,488ms (± 1.07%)	~	2,455ms	2,533ms	p=0.810 n=6
Req 2 - geterr	4,113ms (± 2.06%)	4,127ms (± 1.78%)	~	4,055ms	4,219ms	p=0.378 n=6
Req 3 - references	340ms (± 1.61%)	341ms (± 1.74%)	~	333ms	348ms	p=0.934 n=6
Req 4 - navto	284ms (± 0.29%)	285ms (± 0.48%)	~	283ms	287ms	p=0.865 n=6
Req 5 - completionInfo count	1,518 (± 0.00%)	1,518 (± 0.00%)	~	1,518	1,518	p=1.000 n=6
Req 5 - completionInfo	84ms (± 6.63%)	84ms (± 6.77%)	~	77ms	89ms	p=1.000 n=6
xstateTSServer - node (v18.15.0, x64)
Req 1 - updateOpen	2,592ms (± 0.97%)	2,595ms (± 0.63%)	~	2,569ms	2,619ms	p=0.748 n=6
Req 2 - geterr	1,672ms (± 2.68%)	1,711ms (± 1.18%)	~	1,686ms	1,734ms	p=0.173 n=6
Req 3 - references	113ms (± 9.51%)	121ms (± 8.93%)	~	105ms	128ms	p=0.220 n=6
Req 4 - navto	359ms (± 0.45%)	362ms (± 0.77%)	~	359ms	367ms	p=0.101 n=6
Req 5 - completionInfo count	2,073 (± 0.00%)	2,073 (± 0.00%)	~	2,073	2,073	p=1.000 n=6
Req 5 - completionInfo	302ms (± 2.18%)	304ms (± 1.93%)	~	297ms	313ms	p=0.520 n=6

System info unknown

Hosts

• node (v18.15.0, x64)

Scenarios

• CompilerTSServer - node (v18.15.0, x64)
• Compiler-UnionsTSServer - node (v18.15.0, x64)
• xstateTSServer - node (v18.15.0, x64)

Benchmark	Name	Iterations
Current	pr	6
Baseline	baseline	6

Startup

Comparison Report - baseline..pr

Metric	baseline	pr	Delta	Best	Worst	p-value
tsc-startup - node (v18.15.0, x64)
Execution time	152.53ms (± 0.18%)	152.36ms (± 0.19%)	-0.17ms (- 0.11%)	151.08ms	156.17ms	p=0.000 n=600
tsserver-startup - node (v18.15.0, x64)
Execution time	227.29ms (± 0.15%)	227.18ms (± 0.16%)	-0.10ms (- 0.05%)	225.95ms	232.25ms	p=0.001 n=600
tsserverlibrary-startup - node (v18.15.0, x64)
Execution time	228.45ms (± 0.17%)	228.35ms (± 0.15%)	~	226.47ms	232.80ms	p=0.077 n=600
typescript-startup - node (v18.15.0, x64)
Execution time	228.73ms (± 0.15%)	228.79ms (± 0.15%)	~	227.44ms	231.94ms	p=0.092 n=600

System info unknown

Hosts

• node (v18.15.0, x64)

Scenarios

• tsc-startup - node (v18.15.0, x64)
• tsserver-startup - node (v18.15.0, x64)
• tsserverlibrary-startup - node (v18.15.0, x64)
• typescript-startup - node (v18.15.0, x64)

Benchmark	Name	Iterations
Current	pr	6
Baseline	baseline	6

Developer Information:

Download Benchmarks

[PranavSenthilnathan]

So this is not the solution since this was an intentional feature introduced in #41276. But I think there should probably be some middle ground between reducing eagerly during union creation and lazily when subtype reduction is performed. Maybe just doing subtype reduction when checking variable declaration nodes?

[jakebailey]

The main problem is that if we don't always reduce, then two unions that are actually the same thing can be present at once, which means you can't fast check for equality and such (maybe some other invariants).