Revert "Implement a custom Data.Iterator" (#3848)

Author: tkremenek

benchmark/CMakeLists.txt

@@ -37,7 +37,6 @@ set(SWIFT_BENCH_MODULES
     single-source/CaptureProp
     single-source/Chars
     single-source/ClassArrayGetter
-    single-source/Data
     single-source/DeadArray
     single-source/DictionaryBridge
     single-source/DictionaryLiteral

benchmark/single-source/Data.swift

@@ -38,7 +38,6 @@ import Calculator
 import CaptureProp
 import Chars
 import ClassArrayGetter
-import Data
 import DeadArray
 import DictTest
 import DictTest2
@@ -142,7 +141,6 @@ precommitTests = [
   "HashTest": run_HashTest,
   "Histogram": run_Histogram,
   "Integrate": run_Integrate,
-  "IterateData": run_IterateData,
   "Join": run_Join,
   "LinkedList": run_LinkedList,
   "MapReduce": run_MapReduce,

benchmark/utils/main.swift

@@ -647,40 +647,7 @@ public struct Data : ReferenceConvertible, Equatable, Hashable, RandomAccessColl
     ///
     /// The iterator will increment byte-by-byte.
     public func makeIterator() -> Data.Iterator {
-        return Iterator(_data: self)
-    }
-
-    public struct Iterator : IteratorProtocol {
-        private let _data: Data
-        private var _buffer: (
-            UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8,
-            UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8,
-            UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8,
-            UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8, UInt8)
-        private var _idx: Data.Index
-        private let _endIdx: Data.Index
-
-        private init(_data: Data) {
-            self._data = _data
-            _buffer = (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)
-            _idx = 0
-            _endIdx = _data.endIndex
-        }
-
-        public mutating func next() -> UInt8? {
-            guard _idx < _endIdx else { return nil }
-            defer { _idx += 1 }
-            let bufferSize = sizeofValue(_buffer)
-            return withUnsafeMutablePointer(to: &_buffer) { ptr_ in
-                let ptr = UnsafeMutableRawPointer(ptr_).assumingMemoryBound(to: UInt8.self)
-                let bufferIdx = _idx % bufferSize
-                if bufferIdx == 0 {
-                    // populate the buffer
-                    _data.copyBytes(to: ptr, from: _idx..<(_endIdx - _idx > bufferSize ? _idx + bufferSize : _endIdx))
-                }
-                return ptr[bufferIdx]
-            }
-        }
+        return IndexingIterator(_elements: self)
     }
 
     // MARK: -