Sprinkle LLVM_READONLY/READNONE on a few DeclAttribute accessors

[jrose-apple]

No intended functionality change. Probably no performance change either, but might as well.

[jrose-apple]

@swift-ci Please smoke test

[jrose-apple]

@swift-ci Please smoke test compiler performance

[swift-ci]

Build comment file:

Compilation-performance test failed

[jrose-apple]

@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	23.7s	23.4s	-314.2ms	-1.32% ✅

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

name	old	new	delta	delta_pct
Frontend.NumInstructionsExecuted	218,692,366,712	218,758,446,885	66,080,173	0.03%
LLVM.NumLLVMBytesOutput	9,451,772	9,451,772	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	5,848	5,848	0	0.0%
AST.NumLoadedModules	1,281	1,281	0	0.0%
AST.NumTotalClangImportedEntities	17,993	17,993	0	0.0%
AST.NumUsedConformances	1,344	1,344	0	0.0%
IRModule.NumIRBasicBlocks	31,484	31,484	0	0.0%
IRModule.NumIRFunctions	16,822	16,822	0	0.0%
IRModule.NumIRGlobals	14,378	14,378	0	0.0%
IRModule.NumIRInsts	440,416	440,416	0	0.0%
IRModule.NumIRValueSymbols	29,879	29,879	0	0.0%
LLVM.NumLLVMBytesOutput	9,451,772	9,451,772	0	0.0%
SILModule.NumSILGenFunctions	7,911	7,911	0	0.0%
SILModule.NumSILOptFunctions	10,717	10,717	0	0.0%
Sema.NumConformancesDeserialized	31,571	31,571	0	0.0%
Sema.NumConstraintScopes	71,146	71,146	0	0.0%
Sema.NumDeclsDeserialized	256,112	256,112	0	0.0%
Sema.NumDeclsValidated	16,273	16,273	0	0.0%
Sema.NumFunctionsTypechecked	7,047	7,047	0	0.0%
Sema.NumGenericSignatureBuilders	10,877	10,877	0	0.0%
Sema.NumLazyGenericEnvironments	50,393	50,393	0	0.0%
Sema.NumLazyGenericEnvironmentsLoaded	5,778	5,778	0	0.0%
Sema.NumLazyIterableDeclContexts	40,996	40,996	0	0.0%
Sema.NumTypesDeserialized	116,041	116,041	0	0.0%
Sema.NumTypesValidated	13,937	13,937	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) (3)

name	old	new	delta	delta_pct
Frontend.NumInstructionsExecuted	230,608,465,271	230,521,669,112	-86,796,159	-0.04%
LLVM.NumLLVMBytesOutput	10,527,132	10,527,132	0	0.0%
time.swift-driver.wall	38.7s	38.7s	17.2ms	0.04%

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	1,385	1,385	0	0.0%
AST.NumLoadedModules	100	100	0	0.0%
AST.NumTotalClangImportedEntities	4,901	4,901	0	0.0%
AST.NumUsedConformances	1,346	1,346	0	0.0%
IRModule.NumIRBasicBlocks	34,321	34,321	0	0.0%
IRModule.NumIRFunctions	15,068	15,068	0	0.0%
IRModule.NumIRGlobals	13,758	13,758	0	0.0%
IRModule.NumIRInsts	334,979	334,979	0	0.0%
IRModule.NumIRValueSymbols	27,725	27,725	0	0.0%
LLVM.NumLLVMBytesOutput	10,527,132	10,527,132	0	0.0%
SILModule.NumSILGenFunctions	6,138	6,138	0	0.0%
SILModule.NumSILOptFunctions	9,104	9,104	0	0.0%
Sema.NumConformancesDeserialized	16,584	16,584	0	0.0%
Sema.NumConstraintScopes	69,710	69,710	0	0.0%
Sema.NumDeclsDeserialized	52,007	52,007	0	0.0%
Sema.NumDeclsValidated	10,362	10,362	0	0.0%
Sema.NumFunctionsTypechecked	4,362	4,362	0	0.0%
Sema.NumGenericSignatureBuilders	2,585	2,585	0	0.0%
Sema.NumLazyGenericEnvironments	9,461	9,461	0	0.0%
Sema.NumLazyGenericEnvironmentsLoaded	1,312	1,312	0	0.0%
Sema.NumLazyIterableDeclContexts	5,811	5,811	0	0.0%
Sema.NumTypesDeserialized	30,810	30,810	0	0.0%
Sema.NumTypesValidated	7,103	7,103	0	0.0%

---