[test] unaligned loads of large, generic SIMD types

Author: glessard

test/stdlib/UnsafeRawPointer.swift

@@ -114,6 +114,35 @@ UnsafeMutableRawPointerExtraTestSuite.test("load.unaligned")
   expectEqual(result, 0xffff_0000)
 }
 
+UnsafeMutableRawPointerExtraTestSuite.test("load.unaligned.SIMD")
+.skip(.custom({
+  if #available(SwiftStdlib 5.7, *) { return false }
+  return true
+}, reason: "Requires Swift 5.7's stdlib"))
+.code {
+  guard #available(SwiftStdlib 5.7, *) else { return }
+  var bytes: [UInt8] = Array(0..<64)
+  var offset = 3
+  let vector16 = bytes.withUnsafeBytes { buffer -> SIMD16<UInt8> in
+    let aligned = buffer.baseAddress!.alignedUp(for: SIMD16<UInt8>.self)
+    offset += buffer.baseAddress!.distance(to: aligned)
+    return buffer.loadUnaligned(fromByteOffset: offset, as: SIMD16<UInt8>.self)
+  }
+  expectEqual(Int(vector16[0]), offset)
+  var lastIndex = vector16.indices.last!
+  expectEqual(Int(vector16[lastIndex]), offset+lastIndex)
+
+  offset = 11
+  let vector32 = bytes.withUnsafeMutableBytes { buffer -> SIMD32<UInt8> in
+    let aligned = buffer.baseAddress!.alignedUp(for: SIMD16<UInt8>.self)
+    offset += buffer.baseAddress!.distance(to: aligned)
+    return buffer.loadUnaligned(fromByteOffset: offset, as: SIMD32<UInt8>.self)
+  }
+  expectEqual(Int(vector32[0]), offset)
+  lastIndex = vector32.indices.last!
+  expectEqual(Int(vector32[lastIndex]), offset+lastIndex)
+}
+
 UnsafeMutableRawPointerExtraTestSuite.test("load.invalid")
 .skip(.custom({ !_isDebugAssertConfiguration() },
               reason: "This tests a debug precondition.."))