[temp-rvalue] Teach how to optimize unchecked_take_enum_data_addr of an Optional type.

[gottesmm]

unchecked_take_enum_data_addr only writes to memory in certain cases. Optional
is not one of those cases luckily.

Given that I am adding support here just for optionals so that we can get rid of
temporaries that are used with a switch_enum_addr. This is an example of a case
where we need to eliminate temporary allocations to allow for Semantic ARC Opts
to eliminate further traffic.

[gottesmm]

Just slicing off small improvements.

[gottesmm]

@swift-ci benchmark

[gottesmm]

@swift-ci smoke test

[swift-ci]

Performance: -O

Improvement	OLD	NEW	DELTA	RATIO
FlattenListFlatMap	5628	4027	-28.4%	1.40x (?)
FlattenListLoop	3178	2676	-15.8%	1.19x (?)

Code size: -O

Performance: -Osize

Code size: -Osize

Performance: -Onone

Regression	OLD	NEW	DELTA	RATIO
StringInterpolationManySmallSegments	10300	12800	+24.3%	0.80x (?)

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: 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: 64 GB