Conditionally enable bounds checking for unsafe buffer pointers

[DougGregor]

Currently, bounds checking is only enabled for unsafe buffer pointers in debug builds. Introduce a new precondition check kind, _boundsCheckPrecondition, and use it for the bounds checking of unsafe buffer pointers. This check is enabled both in debug builds and in builds where the experimental feature UnsafePointerBoundsSafety is enabled.

Also add [unchecked:] and [uncheckedBounds:] subscripts to Collection and the various array and buffer types, which only perform bounds checking in debug builds. These can be used in places where the optimizer is not eliminating bounds checks that it should be.

[DougGregor]

@swift-ci please smoke test

[DougGregor]

@swift-ci please benchmark

[DougGregor]

@swift-ci please smoke test

[DougGregor]

@swift-ci please benchmark

[DougGregor]

@swift-ci please smoke test

[DougGregor]

Performance (x86_64): -O

Regression	OLD	NEW	DELTA	RATIO
FlattenListFlatMap	2853.0	4297.0	+50.6%	0.66x (?)
AngryPhonebook	275.414	359.116	+30.4%	0.77x (?)
AngryPhonebook.ASCII2.Small	113.833	148.0	+30.0%	0.77x (?)
ArrayAppendGenericStructs	1387.5	1790.0	+29.0%	0.78x (?)
LessSubstringSubstring	24.259	30.594	+26.1%	0.79x (?)
EqualSubstringString	24.364	30.692	+26.0%	0.79x (?)
EqualSubstringSubstring	24.613	30.92	+25.6%	0.80x (?)
UTF8Decode_InitFromData	142.667	177.7	+24.6%	0.80x (?)
EqualStringSubstring	24.815	30.8	+24.1%	0.81x (?)
EqualSubstringSubstringGenericEquatable	24.704	30.594	+23.8%	0.81x (?)
UTF8Decode_InitFromBytes	147.25	178.4	+21.2%	0.83x
String.replaceSubrange.String.Small	38.87	45.821	+17.9%	0.85x (?)
AngryPhonebook.Strasse	538.75	627.333	+16.4%	0.86x (?)
StringWordBuilderReservingCapacity	1140.714	1326.154	+16.3%	0.86x (?)
DistinctClassFieldAccesses	40.378	46.923	+16.2%	0.86x (?)
StringWordBuilder	1177.143	1363.636	+15.8%	0.86x (?)
SubstringEqualString	175.889	203.0	+15.4%	0.87x (?)
StringComparison_longSharedPrefix	210.2	241.222	+14.8%	0.87x (?)
PrefixWhileAnySequence	195.0	222.889	+14.3%	0.87x (?)
PrefixWhileSequence	195.1	222.0	+13.8%	0.88x (?)
String.replaceSubrange.String	9.478	10.783	+13.8%	0.88x (?)
AngryPhonebook.Cyrillic	596.5	678.0	+13.7%	0.88x (?)
String.initRepeating.1AsciiChar.Count100	476.5	541.333	+13.6%	0.88x (?)
AngryPhonebook.Armenian	569.75	645.667	+13.3%	0.88x
StringHasSuffixAscii	3462.0	3916.0	+13.1%	0.88x (?)
FlattenListLoop	1448.0	1624.0	+12.2%	0.89x (?)
Breadcrumbs.UTF16ToIdx.longASCII	39.313	43.582	+10.9%	0.90x (?)
StringBuilder	233.333	256.0	+9.7%	0.91x (?)
String.replaceSubrange.ArrChar.Small	39.333	42.739	+8.7%	0.92x (?)
StringEnumRawValueInitialization	394.815	424.762	+7.6%	0.93x (?)
Improvement	OLD	NEW	DELTA	RATIO
KeyPathNestedStructs	6.853	3.324	-51.5%	2.06x
KeyPathsSmallStruct	21.438	10.537	-50.8%	2.03x
KeyPathReadPerformance	29.568	18.711	-36.7%	1.58x
Dictionary4	239.333	157.4	-34.2%	1.52x
Dictionary4OfObjects	263.833	189.429	-28.2%	1.39x
Array.removeAll.keepingCapacity.Object	7.376	5.75	-22.0%	1.28x (?)
UTF8Decode_InitDecoding	167.9	139.286	-17.0%	1.21x (?)
UTF8Decode_InitFromCustom_contiguous	167.154	139.385	-16.6%	1.20x (?)
Data.hash.Medium	28.074	24.29	-13.5%	1.16x (?)
UTF8Decode_InitFromCustom_noncontiguous	208.0	182.3	-12.4%	1.14x (?)
NormalizedIterator_emoji	365.231	323.034	-11.6%	1.13x (?)
NormalizedIterator_nonBMPSlowestPrenormal	474.5	430.233	-9.3%	1.10x (?)
ArrayAppendAscii	2043.4	1888.889	-7.6%	1.08x (?)
NormalizedIterator_slowerPrenormal	317.073	295.366	-6.8%	1.07x (?)

Code size: -O

Performance (x86_64): -Osize

Regression	OLD	NEW	DELTA	RATIO
Array.removeAll.keepingCapacity.Object	5.577	7.461	+33.8%	0.75x (?)
AngryPhonebook	273.237	360.267	+31.9%	0.76x (?)
AngryPhonebook.ASCII2.Small	113.706	147.786	+30.0%	0.77x (?)
EqualSubstringSubstring	23.844	30.279	+27.0%	0.79x (?)
EqualStringSubstring	23.833	30.259	+27.0%	0.79x (?)
EqualSubstringSubstringGenericEquatable	23.941	30.269	+26.4%	0.79x (?)
LessSubstringSubstringGenericComparable	24.946	31.345	+25.7%	0.80x (?)
EqualSubstringString	24.813	31.135	+25.5%	0.80x (?)
LessSubstringSubstring	24.917	31.258	+25.4%	0.80x (?)
UTF8Decode_InitFromData	142.091	177.727	+25.1%	0.80x (?)
UTF8Decode_InitFromBytes	144.0	178.222	+23.8%	0.81x (?)
StringWordBuilderReservingCapacity	1145.0	1355.385	+18.4%	0.84x (?)
SubstringEqualString	177.364	209.333	+18.0%	0.85x (?)
String.replaceSubrange.String.Small	39.103	46.0	+17.6%	0.85x (?)
StringComparison_longSharedPrefix	205.667	239.3	+16.4%	0.86x (?)
StringWordBuilder	1191.667	1385.0	+16.2%	0.86x (?)
AngryPhonebook.Strasse	539.5	627.0	+16.2%	0.86x (?)
String.replaceSubrange.String	9.588	10.986	+14.6%	0.87x (?)
Breadcrumbs.UTF16ToIdx.longASCII	39.322	44.673	+13.6%	0.88x (?)
AngryPhonebook.Cyrillic	597.333	678.0	+13.5%	0.88x (?)
String.initRepeating.1AsciiChar.Count100	477.25	541.25	+13.4%	0.88x (?)
AngryPhonebook.Armenian	570.25	645.667	+13.2%	0.88x (?)
NormalizedIterator_fastPrenormal	488.958	539.535	+10.3%	0.91x (?)
ArrayInClass	200.694	219.571	+9.4%	0.91x (?)
StringBuilder	235.25	257.0	+9.2%	0.92x (?)
SubstringFromLongString2	23.943	26.129	+9.1%	0.92x (?)
StringBuilderSmallReservingCapacity	242.857	263.5	+8.5%	0.92x (?)
Breadcrumbs.MutatedUTF16ToIdx.ASCII	2.476	2.666	+7.7%	0.93x (?)
Improvement	OLD	NEW	DELTA	RATIO
KeyPathsSmallStruct	21.479	10.589	-50.7%	2.03x
KeyPathNestedStructs	7.469	3.735	-50.0%	2.00x
KeyPathReadPerformance	29.571	18.738	-36.6%	1.58x
UTF8Decode_InitFromCustom_contiguous	169.0	140.083	-17.1%	1.21x
UTF8Decode_InitDecoding	168.4	141.909	-15.7%	1.19x (?)
Data.hash.Medium	28.074	24.265	-13.6%	1.16x (?)
UTF8Decode_InitFromCustom_noncontiguous	331.0	304.143	-8.1%	1.09x (?)

Code size: -Osize

Performance (x86_64): -Onone

Regression	OLD	NEW	DELTA	RATIO
ArrayAppendReserved	2547.143	3226.0	+26.7%	0.79x (?)
EqualStringSubstring	28.542	35.8	+25.4%	0.80x (?)
ObjectiveCBridgeStubDateMutation	348.6	435.75	+25.0%	0.80x (?)
EqualSubstringSubstring	28.72	35.828	+24.7%	0.80x (?)
LessSubstringSubstringGenericComparable	26.577	33.097	+24.5%	0.80x (?)
EqualSubstringSubstringGenericEquatable	27.656	34.4	+24.4%	0.80x (?)
UTF8Decode_InitFromData	143.833	178.6	+24.2%	0.81x
UTF8Decode_InitFromBytes	146.75	181.1	+23.4%	0.81x
EqualSubstringString	29.063	35.815	+23.2%	0.81x (?)
LessSubstringSubstring	28.656	35.207	+22.9%	0.81x (?)
StringWordBuilder	1386.667	1647.273	+18.8%	0.84x
StringWordBuilderReservingCapacity	1350.833	1592.5	+17.9%	0.85x
BinaryFloatingPointPropertiesBinade	53.174	61.857	+16.3%	0.86x (?)
AngryPhonebook.Strasse	540.0	627.333	+16.2%	0.86x (?)
String.replaceSubrange.String.Small	41.148	47.32	+15.0%	0.87x (?)
ObjectiveCBridgeStubDateAccess	3258.0	3726.0	+14.4%	0.87x (?)
PrefixCountableRange	261.714	297.714	+13.8%	0.88x (?)
SuffixCountableRange	90.941	103.0	+13.3%	0.88x (?)
AngryPhonebook.Cyrillic	599.25	678.333	+13.2%	0.88x (?)
AngryPhonebook.Armenian	570.5	645.667	+13.2%	0.88x (?)
DropLastCountableRange	90.895	102.75	+13.0%	0.88x (?)
DropFirstCountableRange	261.714	295.571	+12.9%	0.89x (?)
ArraySetElement	809.5	911.0	+12.5%	0.89x
XorLoop	4489.0	5018.0	+11.8%	0.89x (?)
BinaryFloatingPointPropertiesUlp	70.778	79.0	+11.6%	0.90x (?)
DataSubscriptMedium	56.625	63.158	+11.5%	0.90x (?)
Data.hash.Empty	99.133	109.643	+10.6%	0.90x (?)
ObjectiveCBridgeStubNSDateRefAccess	3369.0	3723.0	+10.5%	0.90x (?)
String.replaceSubrange.String	11.659	12.851	+10.2%	0.91x (?)
BinaryFloatingPointPropertiesNextUp	67.458	74.3	+10.1%	0.91x (?)
DataSubscriptSmall	76.118	82.75	+8.7%	0.92x (?)
ObjectiveCBridgeStubToNSStringRef	111.5	120.923	+8.5%	0.92x (?)
Improvement	OLD	NEW	DELTA	RATIO
KeyPathsSmallStruct	21.939	10.1	-54.0%	2.17x
SubstringRemoveFirst1	0.222	0.143	-35.4%	1.55x (?)
KeyPathNestedStructs	16.769	13.185	-21.4%	1.27x (?)
ArrayAppendGenericStructs	1390.0	1130.0	-18.7%	1.23x (?)
UTF8Decode_InitDecoding	175.333	148.0	-15.6%	1.18x (?)
UTF8Decode_InitFromCustom_contiguous	177.7	150.417	-15.4%	1.18x (?)
KeyPathReadPerformance	47.167	40.462	-14.2%	1.17x (?)
NSStringConversion.InlineBuffer.ASCII	5884.0	5193.0	-11.7%	1.13x (?)
NSStringConversion.InlineBuffer.UTF8	3574.0	3202.0	-10.4%	1.12x (?)
Data.hash.Medium	32.44	29.091	-10.3%	1.12x (?)

Code size: -swiftlibs

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 mini
  Model Identifier: Macmini8,1
  Processor Name: 6-Core Intel Core i7
  Processor Speed: 3.2 GHz
  Number of Processors: 1
  Total Number of Cores: 6
  L2 Cache (per Core): 256 KB
  L3 Cache: 12 MB
  Memory: 32 GB

[glessard]

Nice!

[benrimmington]

Collection has three _failEarlyRangeCheck requirements and default implementations.

• Should the default implementations be changed, to match the documentation comments?

• UnsafeRawBufferPointer doesn't implement any of the methods, but it has a TODO comment.

• UnsafeBufferPointer doesn't implement the method with a ClosedRange parameter, and neither do many other types.

[DougGregor]

@benrimmington (EDITED) the default implementations use _precondition, which is the right thing: we're already unconditionally doing bounds checking, so there's nothing to update.

What do you think about providing specific implementations of these for UnsafeRawBufferPointer, @glessard?

As for the ClosedRange version... I don't know why we're missing them, but I'd like to separate out that task from this bounds-safety one.

[DougGregor]

@swift-ci please test

[DougGregor]

@swift-ci please benchmark

[DougGregor]

Now updated with comprehensive checking, as well as the subscript(unchecked:) and subscript(uncheckedBounds:) operations.

[DougGregor]

From the last benchmark run...

Performance (x86_64): -O

Regression	OLD	NEW	DELTA	RATIO
AngryPhonebook	278.091	433.054	+55.7%	0.64x
AngryPhonebook.ASCII2.Small	113.938	175.417	+54.0%	0.65x
SubstringEqualString	165.273	222.667	+34.7%	0.74x
SequenceAlgosAnySequence	19570.0	24822.222	+26.8%	0.79x (?)
DropLastAnySeqCntRangeLazy	31955.0	40516.0	+26.8%	0.79x
DropLastAnySeqCRangeIterLazy	32507.0	41074.0	+26.4%	0.79x
SuffixAnySeqCntRangeLazy	31915.0	40029.0	+25.4%	0.80x
SuffixAnySeqCRangeIterLazy	32191.0	40117.0	+24.6%	0.80x
UTF8Decode_InitDecoding	139.727	172.818	+23.7%	0.81x
UTF8Decode_InitFromCustom_contiguous	140.154	173.077	+23.5%	0.81x (?)
UTF8Decode_InitFromCustom_noncontiguous	180.143	212.0	+17.7%	0.85x
String.replaceSubrange.String.Small	40.741	47.533	+16.7%	0.86x (?)
SubstringEquatable	328.833	382.8	+16.4%	0.86x
Data.hash.Medium	24.3	28.094	+15.6%	0.86x (?)
NormalizedIterator_fastPrenormal	464.231	534.419	+15.1%	0.87x (?)
String.replaceSubrange.Substring	11.0	12.643	+14.9%	0.87x (?)
SuffixAnyCollectionLazy	15769.0	17894.0	+13.5%	0.88x
NormalizedIterator_latin1	168.545	190.783	+13.2%	0.88x (?)
StringWordBuilderReservingCapacity	1205.714	1364.615	+13.2%	0.88x (?)
String.initRepeating.1AsciiChar.Count100	483.0	543.5	+12.5%	0.89x (?)
StringHasPrefixAscii	3703.333	4166.0	+12.5%	0.89x (?)
StringDistance.utf16.mixed	71.333	80.0	+12.1%	0.89x (?)
CStringLongNonAscii	139.429	156.333	+12.1%	0.89x (?)
PrefixAnyCollectionLazy	47199.0	52908.0	+12.1%	0.89x
StringHasSuffixUnicode	72176.471	80388.889	+11.4%	0.90x (?)
StringWordBuilder	1264.286	1406.667	+11.3%	0.90x (?)
DropLastAnyCollectionLazy	15884.0	17642.0	+11.1%	0.90x (?)
DropFirstAnyCollectionLazy	47420.0	52582.0	+10.9%	0.90x (?)
Breadcrumbs.IdxToUTF16Range.longMixed	273.0	302.0	+10.6%	0.90x (?)
StringHasSuffixAscii	3800.0	4200.0	+10.5%	0.90x (?)
AngryPhonebook.Strasse	561.75	620.667	+10.5%	0.91x (?)
AngryPhonebook.Cyrillic	607.75	669.0	+10.1%	0.91x (?)
NormalizedIterator_ascii	93.154	102.286	+9.8%	0.91x (?)
CxxStringConversion.cxx.to.swift	113.5	124.5	+9.7%	0.91x (?)
AngryPhonebook.Armenian	583.5	638.0	+9.3%	0.91x (?)
NormalizedIterator_emoji	311.484	340.296	+9.2%	0.92x (?)
Breadcrumbs.MutatedIdxToUTF16.ASCII	2.5	2.728	+9.1%	0.92x (?)
String.replaceSubrange.Substring.Small	44.885	48.952	+9.1%	0.92x (?)
Breadcrumbs.IdxToUTF16.longMixed	734.5	795.0	+8.2%	0.92x (?)
KeyPathWritePerformance	27.0	29.081	+7.7%	0.93x (?)
DropLastSequenceLazy	296.286	318.833	+7.6%	0.93x (?)
Improvement	OLD	NEW	DELTA	RATIO
KeyPathNestedStructs	6.844	3.286	-52.0%	2.08x
KeyPathsSmallStruct	21.477	10.543	-50.9%	2.04x
KeyPathReadPerformance	29.568	18.759	-36.6%	1.58x (?)
Dictionary4	191.833	156.4	-18.5%	1.23x
Dictionary4OfObjects	219.333	183.429	-16.4%	1.20x
FlattenListLoop	1624.0	1387.0	-14.6%	1.17x (?)
Breadcrumbs.UTF16ToIdx.longASCII	45.759	39.328	-14.1%	1.16x (?)
StringBuilderSmallReservingCapacity	265.714	239.125	-10.0%	1.11x (?)

Code size: -O

Performance (x86_64): -Osize

Regression	OLD	NEW	DELTA	RATIO
AngryPhonebook	273.125	432.297	+58.3%	0.63x
AngryPhonebook.ASCII2.Small	113.625	174.917	+53.9%	0.65x
SubstringEqualString	168.846	213.889	+26.7%	0.79x (?)
SequenceAlgosAnySequence	19580.0	24750.0	+26.4%	0.79x (?)
SuffixAnySeqCntRangeLazy	31745.0	39952.0	+25.9%	0.79x
SuffixAnySeqCRangeIterLazy	31879.0	40035.0	+25.6%	0.80x
DropLastAnySeqCntRangeLazy	32245.0	40122.0	+24.4%	0.80x
DropLastAnySeqCRangeIterLazy	32623.0	40183.0	+23.2%	0.81x
UTF8Decode_InitFromCustom_contiguous	140.615	172.091	+22.4%	0.82x (?)
UTF8Decode_InitDecoding	139.636	170.0	+21.7%	0.82x (?)
Data.hash.Medium	24.292	28.517	+17.4%	0.85x (?)
String.replaceSubrange.Substring	11.111	12.882	+15.9%	0.86x (?)
SubstringEquatable	335.0	385.8	+15.2%	0.87x (?)
String.replaceSubrange.String.Small	40.621	46.769	+15.1%	0.87x (?)
StringHasPrefixAscii	3652.0	4162.0	+14.0%	0.88x (?)
OpenClose	52.261	58.818	+12.5%	0.89x (?)
CStringLongNonAscii	139.615	156.545	+12.1%	0.89x (?)
StringDistance.utf16.mixed	70.5	78.933	+12.0%	0.89x (?)
PrefixAnyCollectionLazy	47927.0	53425.0	+11.5%	0.90x (?)
StringWordBuilderReservingCapacity	1216.667	1345.0	+10.5%	0.90x (?)
SuffixAnyCollectionLazy	15891.0	17550.0	+10.4%	0.91x (?)
StringHasSuffixUnicode	72200.0	79736.842	+10.4%	0.91x (?)
AngryPhonebook.Strasse	560.75	619.25	+10.4%	0.91x (?)
NormalizedIterator_ascii	91.923	101.5	+10.4%	0.91x (?)
StringHasSuffixAscii	3812.0	4204.0	+10.3%	0.91x (?)
RemoveWhereFilterString	220.8	243.4	+10.2%	0.91x (?)
NSStringConversion.Rebridge	50.8	55.974	+10.2%	0.91x (?)
Breadcrumbs.IdxToUTF16Range.longMixed	273.667	301.333	+10.1%	0.91x (?)
String.initRepeating.1AsciiChar.Count100	493.25	540.5	+9.6%	0.91x (?)
StringWordBuilder	1259.286	1379.231	+9.5%	0.91x (?)
StringFromLongWholeSubstring	2.827	3.075	+8.8%	0.92x (?)
StringDistance.utf16.ascii	138.882	151.0	+8.7%	0.92x (?)
RomanNumbers2	455.25	492.75	+8.2%	0.92x (?)
Chars2	3227.273	3493.103	+8.2%	0.92x (?)
ArrayAppendAscii	1876.375	2028.667	+8.1%	0.92x (?)
Breadcrumbs.MutatedIdxToUTF16.ASCII	2.534	2.737	+8.0%	0.93x (?)
DropLastAnyCollectionLazy	16502.0	17763.0	+7.6%	0.93x (?)
Improvement	OLD	NEW	DELTA	RATIO
KeyPathsSmallStruct	21.511	10.571	-50.9%	2.03x
KeyPathNestedStructs	7.471	3.806	-49.0%	1.96x
KeyPathReadPerformance	29.629	18.762	-36.7%	1.58x
FlattenListFlatMap	3800.0	2620.0	-31.1%	1.45x (?)
FlattenListLoop	1386.0	986.0	-28.9%	1.41x (?)
Breadcrumbs.UTF16ToIdx.longASCII	43.586	39.313	-9.8%	1.11x
StringAdder	309.333	280.0	-9.5%	1.10x (?)
CharacterRecognizer.ascii	102.722	93.647	-8.8%	1.10x (?)
String.replaceSubrange.String	10.782	9.833	-8.8%	1.10x (?)
UTF8Decode_InitFromData_ascii_as_ascii	181.0	166.273	-8.1%	1.09x (?)
Data.hash.Empty	56.63	52.25	-7.7%	1.08x (?)
StringInterpolationManySmallSegments	6652.381	6214.286	-6.6%	1.07x (?)

Code size: -Osize

Performance (x86_64): -Onone

Regression	OLD	NEW	DELTA	RATIO
StringWithCString2	0.006	0.01	+57.1%	0.64x
PrefixWhileCountableRange	22762.0	29687.0	+30.4%	0.77x
PrefixWhileAnyCollection	46939.0	59927.0	+27.7%	0.78x
DropFirstAnySeqCRangeIter	32560.0	41425.0	+27.2%	0.79x
SuffixAnyCollection	8090.0	10275.0	+27.0%	0.79x
PrefixAnyCollection	23978.0	30259.0	+26.2%	0.79x
DropLastAnyCollection	7975.0	10064.0	+26.2%	0.79x
SequenceAlgosAnySequence	19922.222	25075.0	+25.9%	0.79x (?)
DropWhileAnyCollection	31794.0	39928.0	+25.6%	0.80x
DropFirstAnyCollection	24083.0	30244.0	+25.6%	0.80x
DropFirstAnySeqCntRange	32697.0	41051.0	+25.5%	0.80x
DropFirstAnySeqCntRangeLazy	32776.0	41012.0	+25.1%	0.80x
DropWhileCountableRange	7931.0	9919.0	+25.1%	0.80x
ObjectiveCBridgeStubDateMutation	348.6	435.75	+25.0%	0.80x
SequenceAlgosRange	1955680.0	2436690.0	+24.6%	0.80x
DropWhileAnySeqCRangeIter	37170.0	46162.0	+24.2%	0.81x
LazilyFilteredRange	849290.0	1050740.0	+23.7%	0.81x
PrefixAnySeqCRangeIter	26370.0	32601.0	+23.6%	0.81x
SuffixAnySeqCntRangeLazy	34838.0	43043.0	+23.6%	0.81x (?)
DropWhileAnySeqCntRange	37157.0	45860.0	+23.4%	0.81x
PrefixAnySeqCntRangeLazy	25931.0	31999.0	+23.4%	0.81x
SuffixAnySeqCntRange	34162.0	42141.0	+23.4%	0.81x
PrefixAnySeqCntRange	26529.0	32689.0	+23.2%	0.81x
SuffixAnySeqCRangeIterLazy	34983.0	43062.0	+23.1%	0.81x
PrefixAnySeqCRangeIterLazy	25926.0	31905.0	+23.1%	0.81x
DropFirstAnySeqCRangeIterLazy	33295.0	40957.0	+23.0%	0.81x
SuffixAnySeqCRangeIter	34860.0	42826.0	+22.9%	0.81x
DropLastAnySeqCntRange	35998.0	44211.0	+22.8%	0.81x
DropWhileCountableRangeLazy	35941.0	44097.0	+22.7%	0.82x
DropWhileAnyCollectionLazy	36321.0	44544.0	+22.6%	0.82x
PrefixWhileCountableRangeLazy	27643.0	33896.0	+22.6%	0.82x
DropWhileAnySeqCRangeIterLazy	36296.0	44420.0	+22.4%	0.82x
DropWhileAnySeqCntRangeLazy	36202.0	44265.0	+22.3%	0.82x
DropLastAnySeqCRangeIterLazy	36758.0	44861.0	+22.0%	0.82x
UTF8Decode_InitDecoding	146.0	178.0	+21.9%	0.82x (?)
DropLastAnySeqCRangeIter	36566.0	44534.0	+21.8%	0.82x
PrefixWhileAnySeqCntRangeLazy	28045.0	34101.0	+21.6%	0.82x
DropLastAnySeqCntRangeLazy	36829.0	44775.0	+21.6%	0.82x
PrefixWhileAnyCollectionLazy	28343.0	34454.0	+21.6%	0.82x
PrefixWhileAnySeqCRangeIterLazy	28241.0	34297.0	+21.4%	0.82x
UTF8Decode_InitFromCustom_contiguous	148.583	180.333	+21.4%	0.82x (?)
DictionaryGroup	4783.0	5740.0	+20.0%	0.83x (?)
BinaryFloatingPointPropertiesUlp	66.545	78.944	+18.6%	0.84x (?)
PrefixWhileAnySeqCntRange	32611.0	38449.0	+17.9%	0.85x
DropLastCountableRangeLazy	14793.0	17378.0	+17.5%	0.85x
ReversedBidirectional	55925.0	65571.0	+17.2%	0.85x
PrefixWhileAnySeqCRangeIter	33532.0	39046.0	+16.4%	0.86x
String.replaceSubrange.String.Small	42.364	49.125	+16.0%	0.86x (?)
String.replaceSubrange.Substring	12.528	14.5	+15.7%	0.86x (?)
BinaryFloatingPointPropertiesBinade	53.136	61.478	+15.7%	0.86x (?)
DropFirstCountableRangeLazy	44953.0	51751.0	+15.1%	0.87x
PrefixCountableRangeLazy	45160.0	51926.0	+15.0%	0.87x
RemoveWhereQuadraticInts	7508.0	8564.0	+14.1%	0.88x (?)
SuffixCountableRangeLazy	15152.0	17264.0	+13.9%	0.88x
StringWordBuilderReservingCapacity	1342.308	1528.333	+13.9%	0.88x (?)
Sim2DArray	5518.0	6280.0	+13.8%	0.88x (?)
CharacterPropertiesPrecomputed	1786.154	2023.636	+13.3%	0.88x (?)
StringHasPrefixAscii	5295.0	5993.333	+13.2%	0.88x
StringWordBuilder	1406.667	1590.909	+13.1%	0.88x (?)
DropLastCountableRange	90.941	102.75	+13.0%	0.89x (?)
SuffixCountableRange	90.737	102.125	+12.6%	0.89x (?)
DropFirstCountableRange	262.143	294.857	+12.5%	0.89x (?)
PrefixCountableRange	261.875	294.429	+12.4%	0.89x (?)
RemoveWhereFilterString	318.714	357.0	+12.0%	0.89x (?)
RemoveWhereQuadraticStrings	8221.0	9207.0	+12.0%	0.89x (?)
SIMDReduce.Int8	6422.0	7180.0	+11.8%	0.89x (?)
StringHasSuffixAscii	5352.5	5976.667	+11.7%	0.90x (?)
DataSubscriptMedium	56.619	63.158	+11.5%	0.90x (?)
StringInterpolationManySmallSegments	7453.333	8309.091	+11.5%	0.90x (?)
BinaryFloatingPointPropertiesNextUp	67.476	75.05	+11.2%	0.90x (?)
DropFirstAnyCollectionLazy	85641.0	94964.0	+10.9%	0.90x (?)
StringHasSuffixUnicode	74400.0	82473.684	+10.9%	0.90x (?)
DataCreateEmpty	807.895	893.0	+10.5%	0.90x (?)
AngryPhonebook.Strasse	561.75	620.0	+10.4%	0.91x (?)
CharacterPropertiesStashedMemo	2064.286	2277.143	+10.3%	0.91x (?)
String.initRepeating.1AsciiChar.Count100	492.5	542.667	+10.2%	0.91x (?)
CStringLongNonAscii	156.615	172.545	+10.2%	0.91x (?)
AngryPhonebook.Cyrillic	607.0	668.333	+10.1%	0.91x (?)
DataCreateMedium	126600.0	139000.0	+9.8%	0.91x (?)
SuffixSequence	10841.0	11886.0	+9.6%	0.91x (?)
DropLastAnyCollectionLazy	28813.0	31565.0	+9.6%	0.91x (?)
AngryPhonebook.Armenian	581.5	637.0	+9.5%	0.91x (?)
PrefixAnyCollectionLazy	86548.0	94567.0	+9.3%	0.92x (?)
SuffixAnyCollectionLazy	28785.0	31443.0	+9.2%	0.92x (?)
SuffixSequenceLazy	10886.0	11841.0	+8.8%	0.92x (?)
String.replaceSubrange.Substring.Small	46.32	50.269	+8.5%	0.92x (?)
DataSubscriptSmall	76.4	82.75	+8.3%	0.92x (?)
Data.hash.Empty	100.2	108.182	+8.0%	0.93x (?)
Improvement	OLD	NEW	DELTA	RATIO
KeyPathsSmallStruct	21.909	10.09	-53.9%	2.17x
KeyPathNestedStructs	16.897	13.192	-21.9%	1.28x
KeyPathReadPerformance	46.684	40.786	-12.6%	1.14x (?)
CharIndexing_punctuated_unicodeScalars_Backwards	66280.0	59920.0	-9.6%	1.11x (?)
StringEnumRawValueInitialization	7232.0	6743.333	-6.8%	1.07x (?)
Set.isSuperset.Seq.Int.Empty	1289.0	1202.0	-6.7%	1.07x (?)

Code size: -swiftlibs

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 mini
  Model Identifier: Macmini8,1
  Processor Name: 6-Core Intel Core i7
  Processor Speed: 3.2 GHz
  Number of Processors: 1
  Total Number of Cores: 6
  L2 Cache (per Core): 256 KB
  L3 Cache: 12 MB
  Memory: 32 GB

[DougGregor]

@swift-ci please smoke test

[eeckstein]

Interestingly, benchmarks like AngryPhonebook don't use any unsafe stuff. It would be good to look at least into one of those benchmark regressions and try to understand the underlying issue

[eeckstein]

Maybe the regression stem from the internals for the String implementation, where it would be okay to opt out of bounds checking (because it's stdlib internal and behind the "safety border")

[stephentyrone]

Yes, that's correct.

[glessard]

What do you think about providing specific implementations of these for UnsafeRawBufferPointer?

I think the reason we hadn't done so thus far is that we got away with it. If we no longer get away with it, then we'll add them.

[DougGregor]

@swift-ci please smoke test

[DougGregor]

@swift-ci please test

[DougGregor]

@swift-ci please test