Microbenchmarks for Swift -> ObjC string bridging

[Catfish-Man]

Currently we don't have anything testing these operations, this gets us some simple baseline coverage.

[Catfish-Man]

@swift-ci please benchmark

[swift-ci]

Build comment file:

Performance: -O

TEST	OLD	NEW	DELTA	RATIO
Improvement
FlattenListLoop	4332	3970	-8.4%	1.09x
MapReduceClass2	40	37	-7.5%	1.08x
FlattenListFlatMap	6866	6398	-6.8%	1.07x (?)
MapReduce	425	397	-6.6%	1.07x (?)
Added
ObjectiveCBridgeStringCompare	1281	1508	1357	—
ObjectiveCBridgeStringCompare2	1240	1301	1261	—
ObjectiveCBridgeStringGetASCIIContents	647	648	648	—
ObjectiveCBridgeStringGetUTF8Contents	511	511	511	—
ObjectiveCBridgeStringHash	156	157	156	—
ObjectiveCBridgeStringIsEqual	307	316	310	—
ObjectiveCBridgeStringIsEqual2	1134	1136	1135	—
ObjectiveCBridgeStringIsEqualAllSwift	981	981	981	—
ObjectiveCBridgeStringRangeOfString	1222	1280	1242	—
ObjectiveCBridgeStringUTF8String	358	358	358	—

Code size: -O

TEST	OLD	NEW	DELTA	RATIO
Regression
ObjectiveCTests.o	1902	16305	+757.3%	0.12x
ObjectiveCBridgingStubs.o	9133	18752	+105.3%	0.49x

Performance: -Osize

TEST	OLD	NEW	DELTA	RATIO
Improvement
FlattenListLoop	4431	4057	-8.4%	1.09x (?)
Array2D	7206	6611	-8.3%	1.09x
Added
ObjectiveCBridgeStringCompare	1277	1427	1327	—
ObjectiveCBridgeStringCompare2	1243	1305	1264	—
ObjectiveCBridgeStringGetASCIIContents	631	632	631	—
ObjectiveCBridgeStringGetUTF8Contents	511	511	511	—
ObjectiveCBridgeStringHash	156	158	157	—
ObjectiveCBridgeStringIsEqual	310	325	315	—
ObjectiveCBridgeStringIsEqual2	1160	1162	1161	—
ObjectiveCBridgeStringIsEqualAllSwift	998	999	998	—
ObjectiveCBridgeStringRangeOfString	1224	1280	1243	—
ObjectiveCBridgeStringUTF8String	359	360	359	—

Code size: -Osize

TEST	OLD	NEW	DELTA	RATIO
Regression
ObjectiveCTests.o	1902	16305	+757.3%	0.12x
ObjectiveCBridgingStubs.o	8925	17944	+101.1%	0.50x

Performance: -Onone

TEST	OLD	NEW	DELTA	RATIO
Regression
UTF8Decode_InitFromData_ascii	721	902	+25.1%	0.80x
Added
ObjectiveCBridgeStringCompare	1282	1422	1329	—
ObjectiveCBridgeStringCompare2	1241	1309	1264	—
ObjectiveCBridgeStringGetASCIIContents	641	642	642	—
ObjectiveCBridgeStringGetUTF8Contents	510	511	511	—
ObjectiveCBridgeStringHash	156	160	158	—
ObjectiveCBridgeStringIsEqual	314	315	314	—
ObjectiveCBridgeStringIsEqual2	1162	1165	1164	—
ObjectiveCBridgeStringIsEqualAllSwift	999	1000	1000	—
ObjectiveCBridgeStringRangeOfString	1224	1302	1251	—
ObjectiveCBridgeStringUTF8String	385	393	388	—

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

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[Catfish-Man]

@swift-ci please smoke test

[milseman]

LGTM