diff -r 4ebc2e2fb97c -r 71c04702a3d5 src/hotspot/share/utilities/copy.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/utilities/copy.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,275 @@
+/*
+ * Copyright (c) 2006, 2016, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "runtime/sharedRuntime.hpp"
+#include "utilities/align.hpp"
+#include "utilities/copy.hpp"
+
+
+// Copy bytes; larger units are filled atomically if everything is aligned.
+void Copy::conjoint_memory_atomic(void* from, void* to, size_t size) {
+  address src = (address) from;
+  address dst = (address) to;
+  uintptr_t bits = (uintptr_t) src | (uintptr_t) dst | (uintptr_t) size;
+
+  // (Note:  We could improve performance by ignoring the low bits of size,
+  // and putting a short cleanup loop after each bulk copy loop.
+  // There are plenty of other ways to make this faster also,
+  // and it's a slippery slope.  For now, let's keep this code simple
+  // since the simplicity helps clarify the atomicity semantics of
+  // this operation.  There are also CPU-specific assembly versions
+  // which may or may not want to include such optimizations.)
+
+  if (bits % sizeof(jlong) == 0) {
+    Copy::conjoint_jlongs_atomic((jlong*) src, (jlong*) dst, size / sizeof(jlong));
+  } else if (bits % sizeof(jint) == 0) {
+    Copy::conjoint_jints_atomic((jint*) src, (jint*) dst, size / sizeof(jint));
+  } else if (bits % sizeof(jshort) == 0) {
+    Copy::conjoint_jshorts_atomic((jshort*) src, (jshort*) dst, size / sizeof(jshort));
+  } else {
+    // Not aligned, so no need to be atomic.
+    Copy::conjoint_jbytes((void*) src, (void*) dst, size);
+  }
+}
+
+class CopySwap : AllStatic {
+public:
+  /**
+   * Copy and optionally byte swap elements
+   *
+   * <swap> - true if elements should be byte swapped
+   *
+   * @param src address of source
+   * @param dst address of destination
+   * @param byte_count number of bytes to copy
+   * @param elem_size size of the elements to copy-swap
+   */
+  template<bool swap>
+  static void conjoint_swap_if_needed(const void* src, void* dst, size_t byte_count, size_t elem_size) {
+    assert(src != NULL, "address must not be NULL");
+    assert(dst != NULL, "address must not be NULL");
+    assert(elem_size == 2 || elem_size == 4 || elem_size == 8,
+           "incorrect element size: " SIZE_FORMAT, elem_size);
+    assert(is_aligned(byte_count, elem_size),
+           "byte_count " SIZE_FORMAT " must be multiple of element size " SIZE_FORMAT, byte_count, elem_size);
+
+    address src_end = (address)src + byte_count;
+
+    if (dst <= src || dst >= src_end) {
+      do_conjoint_swap<RIGHT,swap>(src, dst, byte_count, elem_size);
+    } else {
+      do_conjoint_swap<LEFT,swap>(src, dst, byte_count, elem_size);
+    }
+  }
+
+private:
+  /**
+   * Byte swap a 16-bit value
+   */
+  static uint16_t byte_swap(uint16_t x) {
+    return (x << 8) | (x >> 8);
+  }
+
+  /**
+   * Byte swap a 32-bit value
+   */
+  static uint32_t byte_swap(uint32_t x) {
+    uint16_t lo = (uint16_t)x;
+    uint16_t hi = (uint16_t)(x >> 16);
+
+    return ((uint32_t)byte_swap(lo) << 16) | (uint32_t)byte_swap(hi);
+  }
+
+  /**
+   * Byte swap a 64-bit value
+   */
+  static uint64_t byte_swap(uint64_t x) {
+    uint32_t lo = (uint32_t)x;
+    uint32_t hi = (uint32_t)(x >> 32);
+
+    return ((uint64_t)byte_swap(lo) << 32) | (uint64_t)byte_swap(hi);
+  }
+
+  enum CopyDirection {
+    RIGHT, // lower -> higher address
+    LEFT   // higher -> lower address
+  };
+
+  /**
+   * Copy and byte swap elements
+   *
+   * <T> - type of element to copy
+   * <D> - copy direction
+   * <is_src_aligned> - true if src argument is aligned to element size
+   * <is_dst_aligned> - true if dst argument is aligned to element size
+   *
+   * @param src address of source
+   * @param dst address of destination
+   * @param byte_count number of bytes to copy
+   */
+  template <typename T, CopyDirection D, bool swap, bool is_src_aligned, bool is_dst_aligned>
+  static void do_conjoint_swap(const void* src, void* dst, size_t byte_count) {
+    const char* cur_src;
+    char* cur_dst;
+
+    switch (D) {
+    case RIGHT:
+      cur_src = (const char*)src;
+      cur_dst = (char*)dst;
+      break;
+    case LEFT:
+      cur_src = (const char*)src + byte_count - sizeof(T);
+      cur_dst = (char*)dst + byte_count - sizeof(T);
+      break;
+    }
+
+    for (size_t i = 0; i < byte_count / sizeof(T); i++) {
+      T tmp;
+
+      if (is_src_aligned) {
+        tmp = *(T*)cur_src;
+      } else {
+        memcpy(&tmp, cur_src, sizeof(T));
+      }
+
+      if (swap) {
+        tmp = byte_swap(tmp);
+      }
+
+      if (is_dst_aligned) {
+        *(T*)cur_dst = tmp;
+      } else {
+        memcpy(cur_dst, &tmp, sizeof(T));
+      }
+
+      switch (D) {
+      case RIGHT:
+        cur_src += sizeof(T);
+        cur_dst += sizeof(T);
+        break;
+      case LEFT:
+        cur_src -= sizeof(T);
+        cur_dst -= sizeof(T);
+        break;
+      }
+    }
+  }
+
+  /**
+   * Copy and byte swap elements
+   *
+   * <T>    - type of element to copy
+   * <D>    - copy direction
+   * <swap> - true if elements should be byte swapped
+   *
+   * @param src address of source
+   * @param dst address of destination
+   * @param byte_count number of bytes to copy
+   */
+  template <typename T, CopyDirection direction, bool swap>
+  static void do_conjoint_swap(const void* src, void* dst, size_t byte_count) {
+    if (is_aligned(src, sizeof(T))) {
+      if (is_aligned(dst, sizeof(T))) {
+        do_conjoint_swap<T,direction,swap,true,true>(src, dst, byte_count);
+      } else {
+        do_conjoint_swap<T,direction,swap,true,false>(src, dst, byte_count);
+      }
+    } else {
+      if (is_aligned(dst, sizeof(T))) {
+        do_conjoint_swap<T,direction,swap,false,true>(src, dst, byte_count);
+      } else {
+        do_conjoint_swap<T,direction,swap,false,false>(src, dst, byte_count);
+      }
+    }
+  }
+
+
+  /**
+   * Copy and byte swap elements
+   *
+   * <D>    - copy direction
+   * <swap> - true if elements should be byte swapped
+   *
+   * @param src address of source
+   * @param dst address of destination
+   * @param byte_count number of bytes to copy
+   * @param elem_size size of the elements to copy-swap
+   */
+  template <CopyDirection D, bool swap>
+  static void do_conjoint_swap(const void* src, void* dst, size_t byte_count, size_t elem_size) {
+    switch (elem_size) {
+    case 2: do_conjoint_swap<uint16_t,D,swap>(src, dst, byte_count); break;
+    case 4: do_conjoint_swap<uint32_t,D,swap>(src, dst, byte_count); break;
+    case 8: do_conjoint_swap<uint64_t,D,swap>(src, dst, byte_count); break;
+    default: guarantee(false, "do_conjoint_swap: Invalid elem_size " SIZE_FORMAT "\n", elem_size);
+    }
+  }
+};
+
+void Copy::conjoint_copy(const void* src, void* dst, size_t byte_count, size_t elem_size) {
+  CopySwap::conjoint_swap_if_needed<false>(src, dst, byte_count, elem_size);
+}
+
+void Copy::conjoint_swap(const void* src, void* dst, size_t byte_count, size_t elem_size) {
+  CopySwap::conjoint_swap_if_needed<true>(src, dst, byte_count, elem_size);
+}
+
+// Fill bytes; larger units are filled atomically if everything is aligned.
+void Copy::fill_to_memory_atomic(void* to, size_t size, jubyte value) {
+  address dst = (address) to;
+  uintptr_t bits = (uintptr_t) to | (uintptr_t) size;
+  if (bits % sizeof(jlong) == 0) {
+    jlong fill = (julong)( (jubyte)value ); // zero-extend
+    if (fill != 0) {
+      fill += fill << 8;
+      fill += fill << 16;
+      fill += fill << 32;
+    }
+    //Copy::fill_to_jlongs_atomic((jlong*) dst, size / sizeof(jlong));
+    for (uintptr_t off = 0; off < size; off += sizeof(jlong)) {
+      *(jlong*)(dst + off) = fill;
+    }
+  } else if (bits % sizeof(jint) == 0) {
+    jint fill = (juint)( (jubyte)value ); // zero-extend
+    if (fill != 0) {
+      fill += fill << 8;
+      fill += fill << 16;
+    }
+    //Copy::fill_to_jints_atomic((jint*) dst, size / sizeof(jint));
+    for (uintptr_t off = 0; off < size; off += sizeof(jint)) {
+      *(jint*)(dst + off) = fill;
+    }
+  } else if (bits % sizeof(jshort) == 0) {
+    jshort fill = (jushort)( (jubyte)value ); // zero-extend
+    fill += fill << 8;
+    //Copy::fill_to_jshorts_atomic((jshort*) dst, size / sizeof(jshort));
+    for (uintptr_t off = 0; off < size; off += sizeof(jshort)) {
+      *(jshort*)(dst + off) = fill;
+    }
+  } else {
+    // Not aligned, so no need to be atomic.
+    Copy::fill_to_bytes(dst, size, value);
+  }
+}