[5.0] Make SIMD types Codable.

stdlib/public/core/SIMDVector.swift

@@ -23,7 +23,7 @@ prefix operator .!
 /// conform to `SIMD`.
 public protocol SIMDStorage {
   /// The type of scalars in the vector space.
-  associatedtype Scalar : Hashable
+  associatedtype Scalar : Codable, Hashable
 
   /// The number of scalars, or elements, in the vector.
   var scalarCount: Int { get }
@@ -51,6 +51,7 @@ public protocol SIMDScalar {
 
 /// A SIMD vector of a fixed number of elements.
 public protocol SIMD : SIMDStorage,
+                       Codable,
                        Hashable,
                        CustomStringConvertible,
                        ExpressibleByArrayLiteral {
@@ -85,6 +86,42 @@ public extension SIMD {
     for i in indices { hasher.combine(self[i]) }
   }
 
+  /// Encodes the scalars of this vector into the given encoder in an unkeyed
+  /// container.
+  ///
+  /// This function throws an error if any values are invalid for the given
+  /// encoder's format.
+  ///
+  /// - Parameter encoder: The encoder to write data to.
+  func encode(to encoder: Encoder) throws {
+    var container = encoder.unkeyedContainer()
+    for i in indices {
+      try container.encode(self[i])
+    }
+  }
+
+  /// Creates a new vector by decoding scalars from the given decoder.
+  ///
+  /// This initializer throws an error if reading from the decoder fails, or
+  /// if the data read is corrupted or otherwise invalid.
+  ///
+  /// - Parameter decoder: The decoder to read data from.
+  init(from decoder: Decoder) throws {
+    self.init()
+    var container = try decoder.unkeyedContainer()
+    guard container.count == scalarCount else {
+      throw DecodingError.dataCorrupted(
+        DecodingError.Context(
+          codingPath: decoder.codingPath,
+          debugDescription: "Expected vector with exactly \(scalarCount) elements."
+        )
+      )
+    }
+    for i in indices {
+      self[i] = try container.decode(Scalar.self)
+    }
+  }
+
   /// A textual description of the vector.
   var description: String {
     get {

test/api-digester/Outputs/stability-stdlib-abi.swift.expected

@@ -45,3 +45,7 @@ Var _RawSetStorage.empty has declared type change from _EmptySetSingleton to __E
 
 Func tryReallocateUniquelyReferenced(buffer:newMinimumCapacity:) has been removed
 
+Protocol SIMD has added inherited protocol Decodable
+Protocol SIMD has added inherited protocol Encodable
+Protocol SIMD has generic signature change from <τ_0_0 : CustomStringConvertible, τ_0_0 : ExpressibleByArrayLiteral, τ_0_0 : Hashable, τ_0_0 : SIMDStorage, τ_0_0.MaskStorage : SIMD, τ_0_0.MaskStorage.Scalar : FixedWidthInteger, τ_0_0.MaskStorage.Scalar : SignedInteger> to <τ_0_0 : CustomStringConvertible, τ_0_0 : Decodable, τ_0_0 : Encodable, τ_0_0 : ExpressibleByArrayLiteral, τ_0_0 : Hashable, τ_0_0 : SIMDStorage, τ_0_0.MaskStorage : SIMD, τ_0_0.MaskStorage.Scalar : FixedWidthInteger, τ_0_0.MaskStorage.Scalar : SignedInteger>
+Protocol SIMDStorage has generic signature change from <τ_0_0.Scalar : Hashable> to <τ_0_0.Scalar : Decodable, τ_0_0.Scalar : Encodable, τ_0_0.Scalar : Hashable>

test/api-digester/Outputs/stability-stdlib-source.swift.expected

@@ -1 +1,5 @@
 Func tryReallocateUniquelyReferenced(buffer:newMinimumCapacity:) has been removed
+Protocol SIMD has added inherited protocol Decodable
+Protocol SIMD has added inherited protocol Encodable
+Protocol SIMD has generic signature change from <Self : CustomStringConvertible, Self : ExpressibleByArrayLiteral, Self : Hashable, Self : SIMDStorage, Self.MaskStorage : SIMD, Self.MaskStorage.Scalar : FixedWidthInteger, Self.MaskStorage.Scalar : SignedInteger> to <Self : CustomStringConvertible, Self : Decodable, Self : Encodable, Self : ExpressibleByArrayLiteral, Self : Hashable, Self : SIMDStorage, Self.MaskStorage : SIMD, Self.MaskStorage.Scalar : FixedWidthInteger, Self.MaskStorage.Scalar : SignedInteger>
+Protocol SIMDStorage has generic signature change from <Self.Scalar : Hashable> to <Self.Scalar : Decodable, Self.Scalar : Encodable, Self.Scalar : Hashable>

test/stdlib/SIMD.swift

@@ -0,0 +1,91 @@
+// RUN: %target-run-simple-swift
+// REQUIRES: executable_test
+// REQUIRES: objc_interop
+
+import Foundation
+import StdlibUnittest
+
+let SIMDCodableTests = TestSuite("SIMDCodable")
+
+// Round an integer to the closest representable JS integer value
+func jsInteger<T>(_ value: T) -> T
+where T : SIMD, T.Scalar : FixedWidthInteger {
+  // Attempt to round-trip though Double; if that fails it's because the
+  // rounded value is too large to fit in T, so use the largest value that
+  // does fit instead.
+  let upperBound = T.Scalar(Double(T.Scalar.max).nextDown)
+  var result = T()
+  for i in result.indices {
+    result[i] = T.Scalar(exactly: Double(value[i])) ?? upperBound
+  }
+  return result
+}
+
+func testRoundTrip<T>(_ for: T.Type)
+where T : SIMD, T.Scalar : FixedWidthInteger {
+  let input = jsInteger(T.random(in: T.Scalar.min ... T.Scalar.max))
+  let encoder = JSONEncoder()
+  let decoder = JSONDecoder()
+  do {
+    let data = try encoder.encode(input)
+    let output = try decoder.decode(T.self, from: data)
+    expectEqual(input, output)
+  }
+  catch {
+    expectUnreachableCatch(error)
+  }
+}
+
+func testRoundTrip<T>(_ for: T.Type)
+where T : SIMD, T.Scalar : BinaryFloatingPoint,
+      T.Scalar.RawSignificand : FixedWidthInteger {
+  let input = T.random(in: -16 ..< 16)
+  let encoder = JSONEncoder()
+  let decoder = JSONDecoder()
+  do {
+    let data = try encoder.encode(input)
+    let output = try decoder.decode(T.self, from: data)
+    expectEqual(input, output)
+  }
+  catch {
+    expectUnreachableCatch(error)
+  }
+}
+
+// Very basic round-trip test. We can be much more sophisticated in the future,
+// but we want to at least exercise the API. Also need to add some negative
+// tests for the error paths, and test a more substantial set of types.
+SIMDCodableTests.test("roundTrip") {
+  testRoundTrip(SIMD2<Int8>.self)
+  testRoundTrip(SIMD3<Int8>.self)
+  testRoundTrip(SIMD4<Int8>.self)
+  testRoundTrip(SIMD2<UInt8>.self)
+  testRoundTrip(SIMD3<UInt8>.self)
+  testRoundTrip(SIMD4<UInt8>.self)
+  testRoundTrip(SIMD2<Int32>.self)
+  testRoundTrip(SIMD3<Int32>.self)
+  testRoundTrip(SIMD4<Int32>.self)
+  testRoundTrip(SIMD2<UInt32>.self)
+  testRoundTrip(SIMD3<UInt32>.self)
+  testRoundTrip(SIMD4<UInt32>.self)
+  testRoundTrip(SIMD2<Int>.self)
+  testRoundTrip(SIMD3<Int>.self)
+  testRoundTrip(SIMD4<Int>.self)
+  testRoundTrip(SIMD2<UInt>.self)
+  testRoundTrip(SIMD3<UInt>.self)
+  testRoundTrip(SIMD4<UInt>.self)
+/* Apparently these fail to round trip not only for i386 but also on older
+   macOS versions, so we'll disable them entirely for now.
+#if !arch(i386)
+  // https://bugs.swift.org/browse/SR-9759
+  testRoundTrip(SIMD2<Float>.self)
+  testRoundTrip(SIMD3<Float>.self)
+  testRoundTrip(SIMD4<Float>.self)
+  testRoundTrip(SIMD2<Double>.self)
+  testRoundTrip(SIMD3<Double>.self)
+  testRoundTrip(SIMD4<Double>.self)
+#endif
+  */
+}
+
+runAllTests()