[stdlib] Uninline float description

[airspeedswift]

May help with some code bloat caused by the new string interpolation.

[airspeedswift]

@swift-ci please test

[airspeedswift]

@swift-ci please benchmark

[airspeedswift]

@tbkka I also removed some checks for inf that the C code was already handling. Be nice to remove the NaN check too but that results in more debug-style printing of nan that might not be desirable.

[airspeedswift]

This would also mean we don't need to export swift_format_double

[airspeedswift]

@swift-ci please benchmark

[airspeedswift]

@swift-ci please test

[swift-ci]

Build comment file:

Performance: -O

TEST	OLD	NEW	DELTA	RATIO
Regression
IterateData	1720	1905	+10.8%	0.90x (?)

Code size: -O

TEST	OLD	NEW	DELTA	RATIO
Improvement
FloatingPointPrinting.o	7223	6583	-8.9%	1.10x

Performance: -Osize

TEST	OLD	NEW	DELTA	RATIO
Regression
Array2D	6612	7208	+9.0%	0.92x

Code size: -Osize

TEST	OLD	NEW	DELTA	RATIO
Improvement
FloatingPointPrinting.o	6576	5712	-13.1%	1.15x

Performance: -Onone

TEST	OLD	NEW	DELTA	RATIO
Regression
RandomDoubleLCG	51076	63761	+24.8%	0.80x

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

---

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 92f8f80

[airspeedswift]

@swift-ci please clean test linux platform

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 92f8f80

[airspeedswift]

Unrelated linux failures need #20036

[tbkka]

Thanks for doing this! When I initially did this, I was a little alarmed at the amount of inlining going on, but never got back to it.

@tbkka I also removed some checks for inf that the C code was already handling. Be nice to remove the NaN check too but that results in more debug-style printing of nan that might not be desirable.

Regular description and debugDescription differ only in NaN printing. But you could handle that distinction further down in the code. Right now, I think the debug flag might be entirely ignored.

[tbkka]

Looks good!

[airspeedswift]

Cool. I'll merge this for now and we can revisit sinking the nan handling later, once it's not inlinable we have flexibility to do that whenever.

[airspeedswift]

@swift-ci please test linux platform