LetSwift 컨퍼런스 스위프트 Internals 발표 자료

1. let swift(16)
Internals
LLVM, Type system, Swift Foundation
OSXDEV.orgj

2. Agenda
Swift Compiler
Swift Type System
Swift Type Internals
Swift Foundation
Summary

3. let swift(16)
Swift Compiler
LLVM, Clang, Swiftc

5. A LoNG Time AGo,
in a galaxy
far, far away...

6. LLVM
Low-Level Virtual Machine
An Infrastructure for Multi-stage Optimization
− by Chris Arthur Lattner @2002
Design and Implementation of a compiler infrastructure
− support a unique multi-stage optimization system
− support inter-procedural and profile-driven optimizations
LLVM virtual instruction (IR)
− with high-level type information
Sponsored by APPLE

7. Chris Lattner
The Father of LLVM

8. LLVM Compiler
GCC#4.2#
프론트엔드#
C"
Tree*SSA#
최적화기#
코드 생성기#C++"
Objec)ve+C"
실행파일"
GCC"4.2"
GCC#4.2#
프론트엔드#
C"
LLVM#
최적화기#
LLVM#
코드 생성기#
C++"
Objec)ve+C"
실행파일"
LLVM+GCC"4.2"
Clang#
프론트엔드#
C"
LLVM#
최적화기#
LLVM#
코드 생성기#
C++"
Objec)ve+C"
실행파일"
LLVM"

10. Swift Compiler
yp RVHES
− 9 RHMF DL MSH M RHR
− % < OD GD D
p
− d S MREN L % -: % DMD H
> : c
k ib p ib y AHM
.swift 기계코드

11. let swift(16)
Swift Type System
Duck Type vs. HM Type Inference

12. Objective-C Type System
Static Type + Duck Type System
− C-style static type
− Smalltalk-style duck type
Duck Type History
− a message to comp.lang.python Newsgroup (2000)
Don't check whether it IS-a duck: check whether it QUACKS-like-a
duck, WALKS-like-a duck, etc, etc, depending on exactly what subset
of duck-like behaviour you need to play your language-games with.
“
”

13. Swift Type System
Bi-directional type inference
Constraint-based type checker
− Based classical Hindley-Milner type system
− Include polymorphic types & function overloading
− Step : Generate ➔ Solve ➔ Solution Application
func foo(x: Double) -> Int { … }
var doubleValue : Double = 3.141592
var unknown = foo(doubleValue)
func bar<T>(x: T) -> T { return x }
var floatValue: Float = -bar(1.414)

14. “The Principal Type-Scheme of an Object in
Combinatory Logic” Hindley, J. Roger (1969)
− Describe what types an expression can have
− Present an algorithm actually computing a type.
Deductive System
First implemented as part of the system of ML.
Hindley-Milner Type System
A, A ➔ B
B
(rule)

15. Hindley-Milner Type System
Expression
e = x
| e1 e2
| 𝞴x . e
| let x=e1 in e2
Types
mono 𝞃 = 𝝰
| D𝞃…𝞃
poly 𝞂 = 𝞃
| ∀𝝰.𝞂
variable
application
abstraction
variable
application
quantifier
Syntax
Context 𝛤 = 𝛜
| 𝛤, x : 𝝰
Typing = 𝛤 ⊢e : 𝞂

16. Hindley-Milner Algorithm W
[Var]
[App]
[Abs]
[Let]

17. Type Checker - Constraints
0PT HS x
TAS OD r
NMUD RHNM r q DPT HS RTAS OD
NMRS T SHNM s r q
DLAD c% h
NMEN L M D p
GD DC RS R q
-OO H A D ETM SHNM d
UD N C AHMCHMF y
RR
NMITMSHNM /HRITM SHNM a i p i

18. Constraint Solving
Take a given set of constraints
Determine the most specific type binding for each of the type
variables
The Design of the solver
− Simplification : Relational, Member constraints
− Strategies : solver scope, overload selection
− Comparing solutions : choose solution with smaller scores
“more specific” type
the super-type of overload binds

20. let swift(16)
Swift Type Internals
class, enumeration, struct, protocol

21. Native class type
class NativePen {
let id = 512
var sequence = 1024
}
// class.NativePen.__deallocating_deinit
@_TFC5class9NativePenD : $@convention(method) (@owned NativePen) -> () {
%0 : $NativePen, let, name "self", argno 1
%3 = class.NativePen.deinit(%0)
%4 = unchecked_ref_cast(%3) // $Builtin.NativeObject to $NativePen
dealloc_ref(%4)
}
// class.NativePen.deinit
@_TFC5class9NativePend : $@convention(method) (@guaranteed NativePen) -> @owned
Builtin.NativeObject {
%0 : $NativePen, let, name "self", argno 1
%2 = unchecked_ref_cast(%0) // $NativePen to $Builtin.NativeObject
return %2 // $Builtin.NativeObject
}
deinit

22. Native class type
// class.NativePen.init () -> class.NativePen
@_TFC5class9NativePencfT_S0_ : $@convention(method) (@owned NativePen) -> @owned
NativePen {
%0 : $NativePen, let, name "self"
%2 = mark_uninitialized([rootself], %0)
%4 = metatype(Int.Type)
%5 = integer_literal($Builtin.Int2048, 512)
%6 = Swift.Int.init(%5, %4)
%7 = ref_element_addr(%2 : $NativePen, #NativePen.id)
assign(%6 to %7)
%10 = metatype(Int.Type)
%11 = integer_literal($Builtin.Int2048, 1024)
%12 = Swift.Int.init(%11, %10)
%13 = ref_element_addr(%2 : $NativePen, #NativePen.sequence)
assign (%12 to %13)
return %2 // $NativePen
}
// class.NativePen.__allocating_init () -> class.NativePen
@_TFC5class9NativePenCfT_S0_ : $@convention(thin) (@thick NativePen.Type) -> @owned
NativePen {
%1 = alloc_ref($NativePen)
%3 = class.NativePen.init(%1)
return %3 : $NativePen
}
init

23. enumeration type
_ p r q
− _l u q p
RG A D O NSN N
0PT S A D O NSN N
public protocol Hashable : Equatable {
var hashValue: Int { get }
}
public protocol Equatable {
@warn_unused_result
func == (lhs: Self, rhs: Self) -> Bool
}

24. enum type example
enum PenModels {
case BallPen
case NamePen
}
// enum.PenModels.hashValue.getter : Swift.Int
@_TFO4enum9PenModelsg9hashValueSi : $@convention(method) (PenModels) -> Int {
%2 = alloc_box($Int, var, name "index")
%3 = mark_uninitialized([var] %2#1 : $*Int)
switch_enum %0 : $PenModels,
case #PenModels.BallPen!enumelt: bb1,
case #PenModels.NamePen!enumelt: bb2
bb1:
%6 = metatype($@thin Int.Type)
%7 = integer_literal($Builtin.Int2048, 0)
%8 = Swift.Int.init(%7, %6) // (Builtin.Int2048, @thin Int.Type) -> Int
assign(%8 to %3)
br bb3
bb2:
%12 = metatype($@thin Int.Type)
%13 = integer_literal($Builtin.Int2048, 1)
%14 = Swift.Int.init(%13, %12) // (Builtin.Int2048, @thin Int.Type) -> Int
assign(%14 to %3)
br bb3
bb3:
%17 = load(%3 : $*Int)
%19 = Swift.Int.hashValue.getter(%17) // $@convention(method) (Int) -> Int
strong_release(%2#0) // $@box Int
return %19
}
getter

25. enum type example
// protocol witness for static Swift.Equatable.== infix (A, A) -> Swift.Bool
@_TTWO4enum9PenModelss9EquatableS_ZFS1_oi2eefTxx_Sb :
$@convention(witness_method) (@in PenModels, @in PenModels, @thick
PenModels.Type) -> Bool {
%3 = load(%0 : $*PenModels)
%4 = load(%1 : $*PenModels)
%6 = enum.== infix(%3, %4)
return %6 // $Bool
}
// protocol witness for Swift.Hashable.hashValue.getter : Swift.Int
@_TTWO4enum9PenModelss8HashableS_FS1_g9hashValueSi :
$@convention(witness_method) (@in_guaranteed PenModels) -> Int {
%1 = alloc_stack($PenModels)
copy_addr(%0 to [initialization] %1 : $*PenModels)
%3 = load(%1 : $*PenModels)
%5 = enum.PenModels.hashValue.getter(%3)
dealloc_stack(%1 : $*PenModels)
return %5 // $Int
}
sil_witness_table PenModels: Equatable module enum {
method #Equatable."=="!1:
@_TTWO4enum9PenModelss9EquatableS_ZFS1_oi2eefTxx_Sb
}
sil_witness_table PenModels: Hashable module enum {
base_protocol Equatable: PenModels: Equatable module enum
method #Hashable.hashValue!getter.1:
@_TTWO4enum9PenModelss8HashableS_FS1_g9hashValueSi
}
Protocol Witness Table

26. struct type
i wp p
− MS - % DS% /H SHNM t )(
f
i HED D c
− r
n g b r
− DS HM D D RD

27. struct type - let example
struct Car {
let model = "apple"
}
// struct.Car.init () -> struct.Car
@_TFV6struct3CarCfT_S0_ : $@convention(thin) (@thin Car.Type) -> @owned Car {
%1 = alloc_box($Car, var, name "self", argno 1)
%2 = mark_uninitialized([rootself] %1#1 : $*Car)
%4 = metatype($@thin String.Type)
%5 = string_literal(utf8 "apple")
%6 = integer_literal($Builtin.Word, 5)
%7 = integer_literal($Builtin.Int1, -1)
%8 = Swift.String.init(%5, %6, %7, %4)
%9 = struct_element_addr(%2 : $*Car, #Car.model)
assign(%8 to %9 : $*String)
%11 = load(%2 : $*Car)
retain_value(%11 : $Car)
strong_release(%1#0 : $@box Car)
return %11
}
// struct.Car.model.getter : Swift.String
@_TFV6struct3Carg5modelSS : $@convention(method) (@guaranteed Car) -> @owned String {
%2 = struct_extract(%0 : $Car, #Car.model)
retain_value(%2 : $String)
return %2
}

28. struct type - var example
struct Car {
var driver = "tim"
}
// struct.Car.init (driver : Swift.String) -> struct.Car
@_TFV6struct3CarCfT6driverSS_S0_ : $@convention(thin) (@owned String, @thin Car.Type)
-> @owned Car {
%2 = struct.$Car(%0 : $String)
return %2
}
// struct.Car.init () -> struct.Car
@_TFV6struct3CarCfT_S0_ : $@convention(thin) (@thin Car.Type) -> @owned Car {
%1 = alloc_box($Car, var, name "self", argno 1)
%2 = mark_uninitialized([rootself] %1#1 : $*Car)
%4 = metatype($@thin String.Type)
%5 = string_literal(utf8 "tim")
%6 = integer_literal($Builtin.Word, 3)
%7 = integer_literal($Builtin.Int1, -1)
%8 = Swift.String.init(%5, %6, %7, %4)
%9 = struct_element_addr(%2 : $*Car, #Car.driver)
assign(%8 to %9 : $*String)
%11 = load(%2 : $*Car)
retain_value(%11 : $Car)
strong_release(%1#0 : $@box Car)
return %11
}
init

29. struct type - var example
// struct.Car.driver.getter : Swift.String
@_TFV6struct3Carg6driverSS : $@convention(method) (@guaranteed Car) -> @owned String {
%2 = struct_extract(%0 : $Car, #Car.driver)
retain_value(%2 : $String)
return %2
}
// struct.Car.driver.setter : Swift.String
@_TFV6struct3Cars6driverSS : $@convention(method) (@owned String, @inout Car) -> () {
%3 = alloc_box($Car, var, name "self", argno 2)
copy_addr(%1 to [initialization] %3#1 : $*Car)
retain_value(%0 : $String)
%6 = struct_element_addr(%3#1 : $*Car, #Car.driver)
assign(%0 to %6 : $*String)
copy_addr(%3#1 to %1 : $*Car)
strong_release(%3#0 : $@box Car)
release_value(%0 : $String)
%11 = tuple ()
return %11
}
// struct.Car.driver.materializeForSet : Swift.String
@_TFV6struct3Carm6driverSS : $@convention(method) (Builtin.RawPointer, @inout
Builtin.UnsafeValueBuffer, @inout Car) -> (Builtin.RawPointer, Optional<@convention(thin)
(Builtin.RawPointer, inout Builtin.UnsafeValueBuffer, inout Car, @thick Car.Type) -> ()>) {
%3 = struct_element_addr(%2 : $*Car, #Car.driver)
%4 = address_to_pointer(%3 : $*String to $Builtin.RawPointer)
%5 = enum $Optional<@convention(thin) (Builtin.RawPointer, inout
Builtin.UnsafeValueBuffer, inout Car, @thick Car.Type) -> ()>, #Optional.None!enumelt
%6 = tuple (%4 : $Builtin.RawPointer, %5 : $Optional<@convention(thin)
(Builtin.RawPointer, inout Builtin.UnsafeValueBuffer, inout Car, @thick Car.Type) -> ()>)
return %6 : $(Builtin.RawPointer, Optional<@convention(thin) (Builtin.RawPointer, inout
Builtin.UnsafeValueBuffer, inout Car, @thick Car.Type) -> ()>)
}
getter/setter

30. let swift(16)
Swift 3 Foundation

31. Foundation SDK
source : WWDC 2016. Session207. Whats new in foundation for swift

32. 파일 구분 관련 타입들 설명
AffineTransform OTA H RS T S -EEHMD< MREN L -EEHMD< MREN L v p f
CharacterSet
HMSD M EHM RR
VHES G SD DS
G SD DS d TS A D G SD DS p n
Data HMSD M EHM RR VHES / S / S TS A D/ S p n
Date OTA H RS T S / SD <HLD MSD U SHLD m b p
DateComponents OTA H RS T S / SD NLONMDMSR / SD NLONMDMSR p m
DateInterval OTA H RS T S / SD MSD U / SD MSD U p m i o
Decimal D SDMRHNM /D HL
t % e % /D HL TLAD
a p
FileManager OTA H RR H D M FD H D M FD
IndexPath OTA H RS T S MCD 9 SG MCD 9 SG v p o f
IndexSet OTA H RS T S MCD DS MCD DS v p o f
Measurement
OTA H RS T S D RT DLDMS+ MHS< OD
MHS,
D RT DLDMS v p o f
Notification OTA H RS T S NSHEH SHNM NSHEH SHNM v p o f
NSError D SDMRHNM 0 N 0 N 9 NSN N 0 N o u
URL OTA H RS T S : : p f
URLComponents OTA H RS T S : NLONMDMSR : NLONMDMSR p f
URLRequest OTA H RS T S : :DPTDRS TS A D : :DPTDRS p f

33. Summary
Swift Compiler
− LLVM + Chris Lattner, Talyer swift
Type System
− HM Type System + W Algorithm
Type Internals
− class, enumeration, struct, protocol Types
Swift Foundation
− IndexPath, IndexSet, Measurement, Notification

34. References
llvm.org
swift.org
https://github.com/apple/swift-evolution
https://github.com/apple/swift/tree/swift-3.0-preview-2-branch
https://en.wikipedia.org/wiki/Duck_typing
https://en.wikipedia.org/wiki/
Hindley%E2%80%93Milner_type_system
http://akgupta.ca/blog/2013/05/14/so-you-still-dont-understand-
hindley-milner/
https://developer.apple.com/videos/wwdc2016/

35. let swift(16)