[Sema] Omit recording some conversion restrictions in constraint solutions

[gregomni]

Omit recording conversion restrictions in a solution that apply can just as easily figure out itself from the shape of the types. This is an implementation discussed in #18345.

Helps resolve SR-8314.

Recording and simplifying these types of restrictions takes almost 75% of the total compilation time in the test file in SR-8314, and by inspection, the coercion code executed in CSApply is exactly the same with or without.

[xedin]

This seems reasonable to me. For posterity - the reason why we can avoid recording these restriction types is because coerceToType already detects and handles them after the restriction switch so this is effectively a code deduplication.

[xedin]

@gregomni I guess alternative approach might be to keep restrictions but remove follow up code in coerceToType and see what breaks?

Looks like source compatibility testing is broken at the moment so let's wait a bit before merging this, just in case we've missed something.

[rudkx]

Yeah this seems totally reasonable.

[xedin]

@swift-ci please test source compatibility

[xedin]

@swift-ci please test

[xedin]

@swift-ci please smoke test compiler performance

[swift-ci]

Build comment file:

Summary for master smoketest

Unexpected test results, excluded stats for Kingfisher, ReactiveCocoa

No regressions above thresholds

• Debug
  • debug brief
  • debug detailed
• Release
  • release brief
  • release detailed

Debug

debug brief

Regressed (0)

name	old	new	delta	delta_pct

Improved (1)

name	old	new	delta	delta_pct
time.swift-driver.wall	19.7s	19.5s	-205.6ms	-1.04% ✅

Unchanged (delta < 1.0% or delta < 100.0ms) (1)

name	old	new	delta	delta_pct
LLVM.NumLLVMBytesOutput	9,429,960	9,429,960	0	0.0%

debug detailed

Regressed (0)

name	old	new	delta	delta_pct

Improved (0)

name	old	new	delta	delta_pct

Unchanged (delta < 1.0% or delta < 100.0ms) (23)

name	old	new	delta	delta_pct
AST.NumImportedExternalDefinitions	5,978	5,978	0	0.0%
AST.NumLoadedModules	1,281	1,281	0	0.0%
AST.NumTotalClangImportedEntities	17,774	17,774	0	0.0%
AST.NumUsedConformances	1,285	1,285	0	0.0%
IRModule.NumIRBasicBlocks	31,452	31,452	0	0.0%
IRModule.NumIRFunctions	17,230	17,230	0	0.0%
IRModule.NumIRGlobals	14,039	14,039	0	0.0%
IRModule.NumIRInsts	439,204	439,204	0	0.0%
IRModule.NumIRValueSymbols	29,460	29,460	0	0.0%
LLVM.NumLLVMBytesOutput	9,429,960	9,429,960	0	0.0%
SILModule.NumSILGenFunctions	8,060	8,060	0	0.0%
SILModule.NumSILOptFunctions	11,016	11,016	0	0.0%
Sema.NumConformancesDeserialized	40,982	40,982	0	0.0%
Sema.NumConstraintScopes	74,281	74,281	0	0.0%
Sema.NumDeclsDeserialized	259,195	259,195	0	0.0%
Sema.NumDeclsValidated	19,506	19,506	0	0.0%
Sema.NumFunctionsTypechecked	5,036	5,036	0	0.0%
Sema.NumGenericSignatureBuilders	11,918	11,918	0	0.0%
Sema.NumLazyGenericEnvironments	50,752	50,752	0	0.0%
Sema.NumLazyGenericEnvironmentsLoaded	5,999	5,999	0	0.0%
Sema.NumLazyIterableDeclContexts	38,500	38,500	0	0.0%
Sema.NumTypesDeserialized	277,064	277,064	0	0.0%
Sema.NumTypesValidated	35,914	35,914	0	0.0%

Release

release brief

Regressed (0)

name	old	new	delta	delta_pct

Improved (0)

name	old	new	delta	delta_pct

Unchanged (delta < 1.0% or delta < 100.0ms) (2)

name	old	new	delta	delta_pct
LLVM.NumLLVMBytesOutput	10,537,056	10,537,056	0	0.0%
time.swift-driver.wall	32.7s	32.8s	105.1ms	0.32%

release detailed

Regressed (0)

name	old	new	delta	delta_pct

Improved (0)

name	old	new	delta	delta_pct

Unchanged (delta < 1.0% or delta < 100.0ms) (23)

name	old	new	delta	delta_pct
AST.NumImportedExternalDefinitions	1,411	1,411	0	0.0%
AST.NumLoadedModules	100	100	0	0.0%
AST.NumTotalClangImportedEntities	4,902	4,902	0	0.0%
AST.NumUsedConformances	1,287	1,287	0	0.0%
IRModule.NumIRBasicBlocks	34,285	34,285	0	0.0%
IRModule.NumIRFunctions	15,390	15,390	0	0.0%
IRModule.NumIRGlobals	13,539	13,539	0	0.0%
IRModule.NumIRInsts	333,823	333,823	0	0.0%
IRModule.NumIRValueSymbols	27,422	27,422	0	0.0%
LLVM.NumLLVMBytesOutput	10,537,056	10,537,056	0	0.0%
SILModule.NumSILGenFunctions	6,207	6,207	0	0.0%
SILModule.NumSILOptFunctions	9,400	9,400	0	0.0%
Sema.NumConformancesDeserialized	19,784	19,784	0	0.0%
Sema.NumConstraintScopes	72,849	72,849	0	0.0%
Sema.NumDeclsDeserialized	55,114	55,114	0	0.0%
Sema.NumDeclsValidated	12,645	12,645	0	0.0%
Sema.NumFunctionsTypechecked	3,079	3,079	0	0.0%
Sema.NumGenericSignatureBuilders	2,835	2,835	0	0.0%
Sema.NumLazyGenericEnvironments	9,817	9,817	0	0.0%
Sema.NumLazyGenericEnvironmentsLoaded	1,382	1,382	0	0.0%
Sema.NumLazyIterableDeclContexts	5,644	5,644	0	0.0%
Sema.NumTypesDeserialized	71,315	71,315	0	0.0%
Sema.NumTypesValidated	17,086	17,086	0	0.0%

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