[benchmarks] Add a benchmark for printing using mirrors

[airspeedswift]

Two new benchmarks. One for using internal mirror reflection to convert types that don't conform to CustomStringConvertible to strings, and another for specifically getting a type's name as a string.

[airspeedswift]

@swift-ci please benchmark

[airspeedswift]

@swift-ci please test

[swift-ci]

Build failed before running benchmark.

[airspeedswift]

@swift-ci please benchmark

[airspeedswift]

benchmark failure seems unrelated

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - bf3c4ae

[swift-ci]

Performance: -O

Regression	OLD	NEW	DELTA	RATIO
ObjectiveCBridgeStubFromNSDateRef	4660	5780	+24.0%	0.81x (?)
Added	MIN	MAX	MEAN	MAX_RSS
MirrorDefault	29811	31206	30279	—
TypeName	18407	19323	18750	—

Code size: -O

Regression	OLD	NEW	DELTA	RATIO
main.o	55611	56667	+1.9%	0.98x

Performance: -Osize

Regression	OLD	NEW	DELTA	RATIO
ObjectiveCBridgeStubFromNSDate	5920	7410	+25.2%	0.80x (?)
Improvement	OLD	NEW	DELTA	RATIO
String.data.Medium	123	106	-13.8%	1.16x (?)
Added	MIN	MAX	MEAN	MAX_RSS
MirrorDefault	29552	30580	29919	—
TypeName	20136	20887	20391	—

Code size: -Osize

Regression	OLD	NEW	DELTA	RATIO
main.o	45963	46827	+1.9%	0.98x

Performance: -Onone

Regression	OLD	NEW	DELTA	RATIO
ObjectiveCBridgeStubFromNSDate	5840	6780	+16.1%	0.86x (?)
StringToDataMedium	4300	4900	+14.0%	0.88x (?)
DataReplaceSmallBuffer	10900	11900	+9.2%	0.92x (?)
Added	MIN	MAX	MEAN	MAX_RSS
MirrorDefault	31266	32166	31601	—
TypeName	23635	24175	23845	—

Code size: -swiftlibs

✅	Benchmark Check Report
⛔️⏱	TypeName execution took at least 14399 μs. Decrease the workload of TypeName by a factor of 16 (100), to be less than 1000 μs.
⛔️⏱	MirrorDefault execution took at least 27904 μs. Decrease the workload of MirrorDefault by a factor of 32 (100), to be less than 1000 μs.

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]

@swift-ci please smoke test and merge

[airspeedswift]

@swift-ci please smoke test and merge

[airspeedswift]

@swift-ci please smoke test Linux