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// RUN: %target-run-simple-swift
// REQUIRES: executable_test
import StdlibUnittest
import DifferentiationUnittest
var StoreBorrowAdjTest = TestSuite("StoreBorrowAdjTest")
public struct ConstantTimeAccessor<Element>: Differentiable where Element: Differentiable, Element: AdditiveArithmetic {
public struct TangentVector: Differentiable, AdditiveArithmetic {
public typealias TangentVector = ConstantTimeAccessor.TangentVector
public var _base: [Element.TangentVector]
public var accessed: Element.TangentVector
public init(_base: [Element.TangentVector], accessed: Element.TangentVector) {
self._base = _base
self.accessed = accessed
}
}
@usableFromInline
var _values: [Element]
public var accessed: Element
@inlinable
@differentiable(reverse)
public init(_ values: [Element], accessed: Element = .zero) {
self._values = values
self.accessed = accessed
}
@inlinable
@differentiable(reverse)
public var array: [Element] { return _values }
@noDerivative
public var count: Int { return _values.count }
}
public extension ConstantTimeAccessor {
@inlinable
@derivative(of: init(_:accessed:))
static func _vjpInit(_ values: [Element],
accessed: Element = .zero)
-> (value: ConstantTimeAccessor, pullback: (TangentVector) -> (Array<Element>.TangentVector, Element.TangentVector)) {
return (ConstantTimeAccessor(values, accessed: accessed), { v in
let base: Array<Element>.TangentVector
if v._base.count < values.count {
base = Array<Element>
.TangentVector(v._base + Array<Element.TangentVector>(repeating: .zero, count: values.count - v._base.count))
}
else {
base = Array<Element>.TangentVector(v._base)
}
return (base, v.accessed)
})
}
@inlinable
@derivative(of: array)
func vjpArray() -> (value: [Element], pullback: (Array<Element>.TangentVector) -> TangentVector) {
func pullback(v: Array<Element>.TangentVector) -> TangentVector {
var base: [Element.TangentVector]
let localZero = Element.TangentVector.zero
if v.base.allSatisfy({ $0 == localZero }) {
base = []
}
else {
base = v.base
}
return TangentVector(_base: base, accessed: Element.TangentVector.zero)
}
return (_values, pullback)
}
mutating func move(by offset: TangentVector) {
self.accessed.move(by: offset.accessed)
_values.move(by: Array<Element>.TangentVector(offset._base))
}
}
public extension ConstantTimeAccessor.TangentVector {
@inlinable
static func + (lhs: Self, rhs: Self) -> Self {
if rhs._base.isEmpty {
return lhs
}
else if lhs._base.isEmpty {
return rhs
}
else {
var base = zip(lhs._base, rhs._base).map(+)
if lhs._base.count < rhs._base.count {
base.append(contentsOf: rhs._base.suffix(from: lhs._base.count))
}
else if lhs._base.count > rhs._base.count {
base.append(contentsOf: lhs._base.suffix(from: rhs._base.count))
}
return Self(_base: base, accessed: lhs.accessed + rhs.accessed)
}
}
@inlinable
static func - (lhs: Self, rhs: Self) -> Self {
if rhs._base.isEmpty {
return lhs
}
else {
var base = zip(lhs._base, rhs._base).map(-)
if lhs._base.count < rhs._base.count {
base.append(contentsOf: rhs._base.suffix(from: lhs._base.count).map { .zero - $0 })
}
else if lhs._base.count > rhs._base.count {
base.append(contentsOf: lhs._base.suffix(from: rhs._base.count))
}
return Self(_base: base, accessed: lhs.accessed - rhs.accessed)
}
}
@inlinable
static var zero: Self { Self(_base: [], accessed: .zero) }
}
StoreBorrowAdjTest.test("NonZeroGrad") {
@differentiable(reverse)
func testInits(input: [Float]) -> Float {
let internalAccessor = ConstantTimeAccessor(input)
let internalArray = internalAccessor.array
return internalArray[1]
}
let grad = gradient(at: [42.0, 146.0, 73.0], of: testInits)
expectEqual(grad[1], 1.0)
}
runAllTests()
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