[temp-rvalueopt] Teach how to promote fix_lifetime.

[gottesmm]

In the case of copy_addr, we move it onto the source address and in the case of
a store, put it on the source object.

I just noted this pattern happening a bunch in the stdlib when I was looking
through it for ownership patterns.

[gottesmm]

This just cleans up the SIL.

[gottesmm]

@swift-ci smoke test

[gottesmm]

@swift-ci benchmark

[swift-ci]

Performance: -O

Regression	OLD	NEW	DELTA	RATIO
FlattenListFlatMap	6621	8745	+32.1%	0.76x (?)

Code size: -O

Performance: -Osize

Regression	OLD	NEW	DELTA	RATIO
String.data.LargeUnicode	93	108	+16.1%	0.86x (?)
Improvement	OLD	NEW	DELTA	RATIO
FlattenListFlatMap	6770	4707	-30.5%	1.44x (?)

Code size: -Osize

Performance: -Onone

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

[atrick]

Sweet. The title scared me but I do believe this is correct.