stdlib: extract the common code of _NativeDictionary.resize and copyAndResize into a separate function

[eeckstein]

For code size reduction.

[eeckstein]

@swift-ci test

[eeckstein]

@swift-ci benchmark

[swift-ci]

Performance: -O

Regression	OLD	NEW	DELTA	RATIO
ObjectiveCBridgeStringHash	67	78	+16.4%	0.86x
StringUTF16Builder	340	370	+8.8%	0.92x (?)
Improvement	OLD	NEW	DELTA	RATIO
EqualSubstringSubstring	42	39	-7.1%	1.08x (?)
LessSubstringSubstring	42	39	-7.1%	1.08x (?)
EqualSubstringSubstringGenericEquatable	42	39	-7.1%	1.08x (?)
EqualSubstringString	42	39	-7.1%	1.08x (?)
LessSubstringSubstringGenericComparable	42	39	-7.1%	1.08x
EqualStringSubstring	43	40	-7.0%	1.07x (?)

Code size: -O

Improvement	OLD	NEW	DELTA	RATIO
Histogram.o	3918	3182	-18.8%	1.23x
DictTest2.o	14333	11757	-18.0%	1.22x
DictionaryCompactMapValues.o	17441	14513	-16.8%	1.20x
DictionarySubscriptDefault.o	24699	20875	-15.5%	1.18x
DictionaryRemove.o	15528	13224	-14.8%	1.17x
DictionaryCopy.o	10454	8982	-14.1%	1.16x
StringRemoveDupes.o	6342	5462	-13.9%	1.16x
DictTest.o	18700	16124	-13.8%	1.16x
TwoSum.o	5160	4456	-13.6%	1.16x
DictTest3.o	20973	18461	-12.0%	1.14x
DictionarySwap.o	20925	18621	-11.0%	1.12x
RGBHistogram.o	24253	21933	-9.6%	1.11x
DictTest4Legacy.o	22756	20612	-9.4%	1.10x
DictionaryOfAnyHashableStrings.o	9071	8239	-9.2%	1.10x
DictTest4.o	21842	19954	-8.6%	1.09x
ReversedCollections.o	9414	8710	-7.5%	1.08x
DictionaryKeysContains.o	9689	8969	-7.4%	1.08x
PrimsNonStrongRef.o	92495	85935	-7.1%	1.08x
Prims.o	13275	12459	-6.1%	1.07x
PrimsSplit.o	13327	12511	-6.1%	1.07x
ReduceInto.o	14810	13930	-5.9%	1.06x
DictionaryGroup.o	14195	13507	-4.8%	1.05x
DictOfArraysToArrayOfDicts.o	20432	19648	-3.8%	1.04x
WordCount.o	39913	39049	-2.2%	1.02x
ObjectiveCBridging.o	61697	60897	-1.3%	1.01x

Performance: -Osize

Regression	OLD	NEW	DELTA	RATIO
ObjectiveCBridgeStringHash	67	77	+14.9%	0.87x
ObjectiveCBridgeFromNSSetAnyObjectToString	72500	80000	+10.3%	0.91x (?)
NSStringConversion.MutableCopy.Rebridge	819	896	+9.4%	0.91x (?)
Improvement	OLD	NEW	DELTA	RATIO
FlattenListFlatMap	7147	5551	-22.3%	1.29x (?)
EqualSubstringSubstring	44	40	-9.1%	1.10x
EqualStringSubstring	44	40	-9.1%	1.10x
EqualSubstringSubstringGenericEquatable	44	40	-9.1%	1.10x
DataAccessBytesMedium	102	94	-7.8%	1.09x
EqualSubstringString	42	39	-7.1%	1.08x (?)
LessSubstringSubstring	43	40	-7.0%	1.07x
LessSubstringSubstringGenericComparable	43	40	-7.0%	1.07x (?)

Code size: -Osize

Regression	OLD	NEW	DELTA	RATIO
DictTest2.o	9037	9213	+1.9%	0.98x
DictTest.o	11708	11884	+1.5%	0.99x
DictionaryRemove.o	10656	10816	+1.5%	0.99x
DictTest3.o	13181	13357	+1.3%	0.99x
DictionaryCopy.o	7506	7602	+1.3%	0.99x
DictionarySubscriptDefault.o	15199	15359	+1.1%	0.99x
Improvement	OLD	NEW	DELTA	RATIO
DictionaryCompactMapValues.o	12743	12119	-4.9%	1.05x

Performance: -Onone

Regression	OLD	NEW	DELTA	RATIO
ObjectiveCBridgeStringHash	67	78	+16.4%	0.86x
FloatingPointPrinting_Float80_description_uniform	57400	62200	+8.4%	0.92x (?)
CaptureProp	824890	893670	+8.3%	0.92x (?)
FindString.Rec3.Substring	910	985	+8.2%	0.92x (?)
FindString.Rec3.String	930	1005	+8.1%	0.93x (?)
Improvement	OLD	NEW	DELTA	RATIO
ObjectiveCBridgeFromNSString	3485	3090	-11.3%	1.13x (?)
SortStringsUnicode	4660	4270	-8.4%	1.09x
LessSubstringSubstringGenericComparable	50	46	-8.0%	1.09x (?)
LessSubstringSubstring	51	47	-7.8%	1.09x (?)
ArrayOfPOD	1121	1036	-7.6%	1.08x (?)

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 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

[lorentey]

Looks good!

[lorentey]

Should the @_semantics attribute here be applied to the new function?

[eeckstein]

A good question. I don't think so, because it's an alwaysEmitIntoClient function. Maybe it's better to remove it at all.
I'll experiment a bit.

[eeckstein]

@swift-ci smoke test and merge

[eeckstein]

@swift-ci smoke test and merge