--- /dev/null
+++ dyld/dyld-1340/cache_builder/ParallelUtils.h
@@ -0,0 +1,74 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+*
+* Copyright (c) 2017 Apple Inc. All rights reserved.
+*
+* @APPLE_LICENSE_HEADER_START@
+*
+* This file contains Original Code and/or Modifications of Original Code
+* as defined in and that are subject to the Apple Public Source License
+* Version 2.0 (the 'License'). You may not use this file except in
+* compliance with the License. Please obtain a copy of the License at
+* http://www.opensource.apple.com/apsl/ and read it before using this
+* file.
+*
+* The Original Code and all software distributed under the License are
+* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+* Please see the License for the specific language governing rights and
+* limitations under the License.
+*
+* @APPLE_LICENSE_HEADER_END@
+*/
+
+#ifndef ParallelUtils_hpp
+#define ParallelUtils_hpp
+
+#include "Array.h"
+#include "Error.h"
+
+#include <dispatch/dispatch.h>
+#include <span>
+#include <vector>
+
+namespace parallel
+{
+
+template<typename T>
+static error::Error forEach(std::span<T> array, error::Error (^callback)(size_t index, T& element))
+{
+    const bool RunInSerial = false;
+
+    dispatch_queue_t queue = RunInSerial ? dispatch_queue_create("serial", DISPATCH_QUEUE_SERIAL) : DISPATCH_APPLY_AUTO;
+
+    BLOCK_ACCCESSIBLE_ARRAY(error::Error, errors, array.size());
+
+    dispatch_apply(array.size(), queue, ^(size_t iteration) {
+        T& element = array[iteration];
+        errors[iteration] = callback(iteration, element);
+    });
+
+    if ( RunInSerial )
+        dispatch_release(queue);
+
+    // Return the first error we find
+    for ( uint32_t i = 0; i != array.size(); ++i ) {
+        error::Error& err = errors[i];
+        if ( err.hasError() )
+            return std::move(err);
+    }
+
+    return error::Error();
+}
+
+// Because "could not match 'span' against 'vector'", for some reason
+template<typename T>
+static error::Error forEach(std::vector<T>& array, error::Error (^callback)(size_t index, T& element))
+{
+    return forEach(std::span<T>(array), callback);
+}
+
+} // namespace parallel
+
+#endif /* ParallelUtils_hpp */