[stdlib][DNM] Remove customization points from Sequence and Collection #19769

airspeedswift · 2018-10-08T16:58:52Z

This removes some unnecessary customization points on standard library protocols:

map and forEach on Sequence

It is unrealistic that a collection would be able to implement map (which takes a transformation closure) to create a mapped array faster than the default implementation.

While it is possible that a type's forEach implementation might be able to eek out a small performance benefit (for example, to avoid the reference count bump of putting self into an iterator), it is generally harmful to encourage this kind of "maybe forEach could be faster" micro-optimization (for example, see here where error control flow was used in order to break out of the for-each early).

first on Collection and last on BidirectionalCollection

It's important to remove these in order for collections of move-only types to be able to implement these protocols. Returning a single element of the collection inside an optional would otherwise need to consume the entire collection.

While it is conceivable that faster implementations of first for particular collections could exist, it's unlikely to be material and experience in benchmarking so far suggests that where they did exist, those implementations were actually slower.

airspeedswift · 2018-10-08T16:59:34Z

@swift-ci please smoke benchmark

airspeedswift · 2018-10-08T16:59:39Z

@swift-ci please smoke test compiler performance

airspeedswift · 2018-10-08T16:59:47Z

@swift-ci please test

swift-ci · 2018-10-08T17:46:16Z

Build comment file:

Performance: -O

TEST	OLD	NEW	DELTA	RATIO
Regression
MapReduceAnyCollection	398	6748	+1595.5%	0.06x
MapReduceAnyCollectionShort	2035	10519	+416.9%	0.19x
IterateData	1769	1909	+7.9%	0.93x (?)
CStringLongAscii	3301	3554	+7.7%	0.93x
Improvement
StringWordBuilderReservingCapacity	1214	1090	-10.2%	1.11x (?)
Array2D	7505	6910	-7.9%	1.09x
MapReduce	396	368	-7.1%	1.08x

Code size: -O

TEST	OLD	NEW	DELTA	RATIO
Regression
MapReduce.o	25781	27621	+7.1%	0.93x
Improvement
NibbleSort.o	14456	13976	-3.3%	1.03x
COWTree.o	14884	14724	-1.1%	1.01x

Performance: -Osize

TEST	OLD	NEW	DELTA	RATIO
Regression
MapReduceAnyCollection	436	11494	+2536.2%	0.04x
MapReduceAnyCollectionShort	2329	15428	+562.4%	0.15x
Improvement
StringWalk	2008	1701	-15.3%	1.18x
StringWordBuilderReservingCapacity	1248	1090	-12.7%	1.14x (?)
Array2D	7208	6611	-8.3%	1.09x

Code size: -Osize

TEST	OLD	NEW	DELTA	RATIO
Regression
MapReduce.o	22365	23557	+5.3%	0.95x
Improvement
NibbleSort.o	19504	18944	-2.9%	1.03x
COWTree.o	14062	13902	-1.1%	1.01x
LuhnAlgoLazy.o	15904	15744	-1.0%	1.01x
LuhnAlgoEager.o	15906	15746	-1.0%	1.01x

Performance: -Onone

TEST	OLD	NEW	DELTA	RATIO
Regression
MapReduceAnyCollection	25072	43746	+74.5%	0.57x
MapReduceAnyCollectionShort	38051	60490	+59.0%	0.63x
PrefixArrayLazy	31200	35976	+15.3%	0.87x
DropFirstArrayLazy	31389	35895	+14.4%	0.87x
Improvement
ArrayOfPOD	859	781	-9.1%	1.10x (?)
StringWordBuilderReservingCapacity	1431	1321	-7.7%	1.08x

Code size: Swift libraries

TEST	OLD	NEW	DELTA	RATIO
Improvement
libswiftCore.dylib	3969024	3907584	-1.5%	1.02x

How to read the data

The tables contain differences in performance which are larger than 8% and differences in code size which are larger than 1%.

If you see any unexpected regressions, you should consider fixing the regressions before you merge the PR.

Noise: Sometimes the performance results (not code size!) contain false alarms. Unexpected regressions which are marked with '(?)' are probably noise. If you see regressions which you cannot explain you can try to run the benchmarks again. If regressions still show up, please consult with the performance team (@eeckstein).

Hardware Overview

  Model Name: Mac Pro
  Model Identifier: MacPro6,1
  Processor Name: 12-Core Intel Xeon E5
  Processor Speed: 2.7 GHz
  Number of Processors: 1
  Total Number of Cores: 12
  L2 Cache (per Core): 256 KB
  L3 Cache: 30 MB
  Memory: 64 GB

swift-ci · 2018-10-08T18:22:36Z

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 (0)

name	old	new	delta	delta_pct

Unchanged (delta < 1.0% or delta < 100.0ms) (3)

name	old	new	delta	delta_pct
Frontend.NumInstructionsExecuted	183,183,666,227	183,268,040,707	84,374,480	0.05%
LLVM.NumLLVMBytesOutput	9,593,348	9,588,752	-4,596	-0.05%
time.swift-driver.wall	23.5s	23.6s	9.0ms	0.04%

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	4,559	4,559	0	0.0%
AST.NumLoadedModules	1,578	1,578	0	0.0%
AST.NumTotalClangImportedEntities	17,921	17,921	0	0.0%
AST.NumUsedConformances	1,352	1,352	0	0.0%
IRModule.NumIRBasicBlocks	32,760	32,744	-16	-0.05%
IRModule.NumIRFunctions	16,675	16,659	-16	-0.1%
IRModule.NumIRGlobals	14,608	14,592	-16	-0.11%
IRModule.NumIRInsts	444,841	444,769	-72	-0.02%
IRModule.NumIRValueSymbols	29,966	29,934	-32	-0.11%
LLVM.NumLLVMBytesOutput	9,593,348	9,588,752	-4,596	-0.05%
SILModule.NumSILGenFunctions	7,843	7,829	-14	-0.18%
SILModule.NumSILOptFunctions	10,695	10,665	-30	-0.28%
Sema.NumConformancesDeserialized	23,230	23,210	-20	-0.09%
Sema.NumConstraintScopes	70,308	70,304	-4	-0.01%
Sema.NumDeclsDeserialized	229,260	228,462	-798	-0.35%
Sema.NumDeclsValidated	16,641	16,641	0	0.0%
Sema.NumFunctionsTypechecked	6,090	6,090	0	0.0%
Sema.NumGenericSignatureBuilders	7,320	7,310	-10	-0.14%
Sema.NumLazyGenericEnvironments	52,371	52,072	-299	-0.57%
Sema.NumLazyGenericEnvironmentsLoaded	2,363	2,363	0	0.0%
Sema.NumLazyIterableDeclContexts	43,925	43,924	-1	-0.0%
Sema.NumTypesDeserialized	100,312	99,697	-615	-0.61%
Sema.NumTypesValidated	14,185	14,185	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	223,126,461,832	222,848,405,976	-278,055,856	-0.12%
LLVM.NumLLVMBytesOutput	10,708,980	10,704,312	-4,668	-0.04%
time.swift-driver.wall	41.3s	41.4s	127.9ms	0.31%

release detailed

Regressed (0)

name	old	new	delta	delta_pct

Improved (3)

name	old	new	delta	delta_pct
SILModule.NumSILOptFunctions	9,041	8,947	-94	-1.04% ✅
Sema.NumConformancesDeserialized	15,078	14,883	-195	-1.29% ✅
Sema.NumTypesDeserialized	26,687	26,209	-478	-1.79% ✅

Unchanged (delta < 1.0% or delta < 100.0ms) (20)

name	old	new	delta	delta_pct
AST.NumImportedExternalDefinitions	1,111	1,111	0	0.0%
AST.NumLoadedModules	105	105	0	0.0%
AST.NumTotalClangImportedEntities	4,764	4,764	0	0.0%
AST.NumUsedConformances	1,354	1,354	0	0.0%
IRModule.NumIRBasicBlocks	34,692	34,676	-16	-0.05%
IRModule.NumIRFunctions	15,176	15,160	-16	-0.11%
IRModule.NumIRGlobals	13,962	13,946	-16	-0.11%
IRModule.NumIRInsts	334,236	334,186	-50	-0.01%
IRModule.NumIRValueSymbols	28,044	28,012	-32	-0.11%
LLVM.NumLLVMBytesOutput	10,708,980	10,704,312	-4,668	-0.04%
SILModule.NumSILGenFunctions	6,076	6,066	-10	-0.16%
Sema.NumConstraintScopes	69,604	69,600	-4	-0.01%
Sema.NumDeclsDeserialized	45,627	45,493	-134	-0.29%
Sema.NumDeclsValidated	10,362	10,362	0	0.0%
Sema.NumFunctionsTypechecked	4,162	4,162	0	0.0%
Sema.NumGenericSignatureBuilders	2,033	2,029	-4	-0.2%
Sema.NumLazyGenericEnvironments	10,065	10,020	-45	-0.45%
Sema.NumLazyGenericEnvironmentsLoaded	201	201	0	0.0%
Sema.NumLazyIterableDeclContexts	5,861	5,861	0	0.0%
Sema.NumTypesValidated	7,103	7,103	0	0.0%

airspeedswift · 2018-10-08T23:25:02Z

@swift-ci please smoke benchmark

airspeedswift · 2018-10-08T23:35:30Z

@swift-ci please smoke test

swift-ci · 2018-10-09T00:12:40Z

Build comment file:

Performance: -O

TEST	OLD	NEW	DELTA	RATIO
Regression
CStringLongAscii	3294	3556	+8.0%	0.93x
Improvement
StringWordBuilderReservingCapacity	1214	1091	-10.1%	1.11x (?)
Array2D	7505	6908	-8.0%	1.09x
MapReduce	397	369	-7.1%	1.08x
MapReduceAnyCollection	398	370	-7.0%	1.08x

Code size: -O

TEST	OLD	NEW	DELTA	RATIO
Improvement
NibbleSort.o	14456	13976	-3.3%	1.03x
COWTree.o	14884	14724	-1.1%	1.01x

Performance: -Osize

TEST	OLD	NEW	DELTA	RATIO
Improvement
StringWordBuilderReservingCapacity	1214	1090	-10.2%	1.11x (?)
Array2D	7208	6612	-8.3%	1.09x

Code size: -Osize

TEST	OLD	NEW	DELTA	RATIO
Improvement
NibbleSort.o	19504	18944	-2.9%	1.03x
COWTree.o	14062	13902	-1.1%	1.01x
LuhnAlgoLazy.o	15904	15744	-1.0%	1.01x
LuhnAlgoEager.o	15906	15746	-1.0%	1.01x

Performance: -Onone

TEST	OLD	NEW	DELTA	RATIO
Improvement
ArrayOfPOD	860	780	-9.3%	1.10x (?)
StringWordBuilderReservingCapacity	1431	1321	-7.7%	1.08x

Code size: Swift libraries

TEST	OLD	NEW	DELTA	RATIO
Improvement
libswiftCore.dylib	3969024	3907584	-1.5%	1.02x

How to read the data

The tables contain differences in performance which are larger than 8% and differences in code size which are larger than 1%.

If you see any unexpected regressions, you should consider fixing the regressions before you merge the PR.

Noise: Sometimes the performance results (not code size!) contain false alarms. Unexpected regressions which are marked with '(?)' are probably noise. If you see regressions which you cannot explain you can try to run the benchmarks again. If regressions still show up, please consult with the performance team (@eeckstein).

Hardware Overview

  Model Name: Mac Pro
  Model Identifier: MacPro6,1
  Processor Name: 12-Core Intel Xeon E5
  Processor Speed: 2.7 GHz
  Number of Processors: 1
  Total Number of Cores: 12
  L2 Cache (per Core): 256 KB
  L3 Cache: 30 MB
  Memory: 64 GB

airspeedswift · 2018-10-24T02:34:11Z

Closing in favor of #19995

airspeedswift force-pushed the too-much-customization branch 2 times, most recently from f0d0c2e to e02c925 Compare October 8, 2018 23:21

Remove customization points from Sequence and Collection

f3edb42

airspeedswift force-pushed the too-much-customization branch from e02c925 to f3edb42 Compare October 23, 2018 14:42

airspeedswift closed this Oct 24, 2018

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[stdlib][DNM] Remove customization points from Sequence and Collection #19769

[stdlib][DNM] Remove customization points from Sequence and Collection #19769

airspeedswift commented Oct 8, 2018 •

edited

airspeedswift commented Oct 8, 2018

airspeedswift commented Oct 8, 2018

airspeedswift commented Oct 8, 2018

swift-ci commented Oct 8, 2018

swift-ci commented Oct 8, 2018

Debug

debug brief

debug detailed

Release

release brief

release detailed

airspeedswift commented Oct 8, 2018

airspeedswift commented Oct 8, 2018

swift-ci commented Oct 9, 2018

airspeedswift commented Oct 24, 2018

[stdlib][DNM] Remove customization points from Sequence and Collection #19769

[stdlib][DNM] Remove customization points from Sequence and Collection #19769

Conversation

airspeedswift commented Oct 8, 2018 • edited

airspeedswift commented Oct 8, 2018

airspeedswift commented Oct 8, 2018

airspeedswift commented Oct 8, 2018

swift-ci commented Oct 8, 2018

Build comment file:

Performance: -O

Code size: -O

Performance: -Osize

Code size: -Osize

Performance: -Onone

Code size: Swift libraries

swift-ci commented Oct 8, 2018

Build comment file:

Summary for master smoketest

Debug

debug brief

debug detailed

Release

release brief

release detailed

airspeedswift commented Oct 8, 2018

airspeedswift commented Oct 8, 2018

swift-ci commented Oct 9, 2018

Build comment file:

Performance: -O

Code size: -O

Performance: -Osize

Code size: -Osize

Performance: -Onone

Code size: Swift libraries

airspeedswift commented Oct 24, 2018

airspeedswift commented Oct 8, 2018 •

edited