Teach EscapeAnalysis to ignore end_access markers.

[atrick]

The presence of end_access markers was causing object properties to
appear to escape globally. That's too conservative.

[atrick]

@swift-ci test

[atrick]

@swift-ci benchmark

[atrick]

@swift-ci test source compatibility

[swift-ci]

Performance: -O

Code size: -O

Performance: -Osize

Improvement	OLD	NEW	DELTA	RATIO
FlattenListFlatMap	3848	3507	-8.9%	1.10x (?)

Code size: -Osize

Performance: -Onone

Regression	OLD	NEW	DELTA	RATIO
DataAppendDataSmallToSmall	2780	3120	+12.2%	0.89x (?)
Improvement	OLD	NEW	DELTA	RATIO
ObjectiveCBridgeStubToNSDateRef	2720	2540	-6.6%	1.07x (?)
WordCountHistogramASCII	94100	87900	-6.6%	1.07x (?)

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: 6-Core 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

[meg-gupta]

lgtm