1 /*

     2  * Copyright (c) 2006, 2016, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #include "precompiled.hpp"

    26 #include "runtime/sharedRuntime.hpp"

    27 #include "utilities/align.hpp"

    28 #include "utilities/copy.hpp"

    29 

    30 

    31 // Copy bytes; larger units are filled atomically if everything is aligned.

    32 void Copy::conjoint_memory_atomic(void* from, void* to, size_t size) {

    33   address src = (address) from;

    34   address dst = (address) to;

    35   uintptr_t bits = (uintptr_t) src | (uintptr_t) dst | (uintptr_t) size;

    36 

    37   // (Note:  We could improve performance by ignoring the low bits of size,

    38   // and putting a short cleanup loop after each bulk copy loop.

    39   // There are plenty of other ways to make this faster also,

    40   // and it's a slippery slope.  For now, let's keep this code simple

    41   // since the simplicity helps clarify the atomicity semantics of

    42   // this operation.  There are also CPU-specific assembly versions

    43   // which may or may not want to include such optimizations.)

    44 

    45   if (bits % sizeof(jlong) == 0) {

    46     Copy::conjoint_jlongs_atomic((jlong*) src, (jlong*) dst, size / sizeof(jlong));

    47   } else if (bits % sizeof(jint) == 0) {

    48     Copy::conjoint_jints_atomic((jint*) src, (jint*) dst, size / sizeof(jint));

    49   } else if (bits % sizeof(jshort) == 0) {

    50     Copy::conjoint_jshorts_atomic((jshort*) src, (jshort*) dst, size / sizeof(jshort));

    51   } else {

    52     // Not aligned, so no need to be atomic.

    53     Copy::conjoint_jbytes((void*) src, (void*) dst, size);

    54   }

    55 }

    56 

    57 class CopySwap : AllStatic {

    58 public:

    59   /**

    60    * Copy and optionally byte swap elements

    61    *

    62    * <swap> - true if elements should be byte swapped

    63    *

    64    * @param src address of source

    65    * @param dst address of destination

    66    * @param byte_count number of bytes to copy

    67    * @param elem_size size of the elements to copy-swap

    68    */

    69   template<bool swap>

    70   static void conjoint_swap_if_needed(const void* src, void* dst, size_t byte_count, size_t elem_size) {

    71     assert(src != NULL, "address must not be NULL");

    72     assert(dst != NULL, "address must not be NULL");

    73     assert(elem_size == 2 || elem_size == 4 || elem_size == 8,

    74            "incorrect element size: " SIZE_FORMAT, elem_size);

    75     assert(is_aligned(byte_count, elem_size),

    76            "byte_count " SIZE_FORMAT " must be multiple of element size " SIZE_FORMAT, byte_count, elem_size);

    77 

    78     address src_end = (address)src + byte_count;

    79 

    80     if (dst <= src || dst >= src_end) {

    81       do_conjoint_swap<RIGHT,swap>(src, dst, byte_count, elem_size);

    82     } else {

    83       do_conjoint_swap<LEFT,swap>(src, dst, byte_count, elem_size);

    84     }

    85   }

    86 

    87 private:

    88   /**

    89    * Byte swap a 16-bit value

    90    */

    91   static uint16_t byte_swap(uint16_t x) {

    92     return (x << 8) | (x >> 8);

    93   }

    94 

    95   /**

    96    * Byte swap a 32-bit value

    97    */

    98   static uint32_t byte_swap(uint32_t x) {

    99     uint16_t lo = (uint16_t)x;

   100     uint16_t hi = (uint16_t)(x >> 16);

   101 

   102     return ((uint32_t)byte_swap(lo) << 16) | (uint32_t)byte_swap(hi);

   103   }

   104 

   105   /**

   106    * Byte swap a 64-bit value

   107    */

   108   static uint64_t byte_swap(uint64_t x) {

   109     uint32_t lo = (uint32_t)x;

   110     uint32_t hi = (uint32_t)(x >> 32);

   111 

   112     return ((uint64_t)byte_swap(lo) << 32) | (uint64_t)byte_swap(hi);

   113   }

   114 

   115   enum CopyDirection {

   116     RIGHT, // lower -> higher address

   117     LEFT   // higher -> lower address

   118   };

   119 

   120   /**

   121    * Copy and byte swap elements

   122    *

   123    * <T> - type of element to copy

   124    * <D> - copy direction

   125    * <is_src_aligned> - true if src argument is aligned to element size

   126    * <is_dst_aligned> - true if dst argument is aligned to element size

   127    *

   128    * @param src address of source

   129    * @param dst address of destination

   130    * @param byte_count number of bytes to copy

   131    */

   132   template <typename T, CopyDirection D, bool swap, bool is_src_aligned, bool is_dst_aligned>

   133   static void do_conjoint_swap(const void* src, void* dst, size_t byte_count) {

   134     const char* cur_src;

   135     char* cur_dst;

   136 

   137     switch (D) {

   138     case RIGHT:

   139       cur_src = (const char*)src;

   140       cur_dst = (char*)dst;

   141       break;

   142     case LEFT:

   143       cur_src = (const char*)src + byte_count - sizeof(T);

   144       cur_dst = (char*)dst + byte_count - sizeof(T);

   145       break;

   146     }

   147 

   148     for (size_t i = 0; i < byte_count / sizeof(T); i++) {

   149       T tmp;

   150 

   151       if (is_src_aligned) {

   152         tmp = *(T*)cur_src;

   153       } else {

   154         memcpy(&tmp, cur_src, sizeof(T));

   155       }

   156 

   157       if (swap) {

   158         tmp = byte_swap(tmp);

   159       }

   160 

   161       if (is_dst_aligned) {

   162         *(T*)cur_dst = tmp;

   163       } else {

   164         memcpy(cur_dst, &tmp, sizeof(T));

   165       }

   166 

   167       switch (D) {

   168       case RIGHT:

   169         cur_src += sizeof(T);

   170         cur_dst += sizeof(T);

   171         break;

   172       case LEFT:

   173         cur_src -= sizeof(T);

   174         cur_dst -= sizeof(T);

   175         break;

   176       }

   177     }

   178   }

   179 

   180   /**

   181    * Copy and byte swap elements

   182    *

   183    * <T>    - type of element to copy

   184    * <D>    - copy direction

   185    * <swap> - true if elements should be byte swapped

   186    *

   187    * @param src address of source

   188    * @param dst address of destination

   189    * @param byte_count number of bytes to copy

   190    */

   191   template <typename T, CopyDirection direction, bool swap>

   192   static void do_conjoint_swap(const void* src, void* dst, size_t byte_count) {

   193     if (is_aligned(src, sizeof(T))) {

   194       if (is_aligned(dst, sizeof(T))) {

   195         do_conjoint_swap<T,direction,swap,true,true>(src, dst, byte_count);

   196       } else {

   197         do_conjoint_swap<T,direction,swap,true,false>(src, dst, byte_count);

   198       }

   199     } else {

   200       if (is_aligned(dst, sizeof(T))) {

   201         do_conjoint_swap<T,direction,swap,false,true>(src, dst, byte_count);

   202       } else {

   203         do_conjoint_swap<T,direction,swap,false,false>(src, dst, byte_count);

   204       }

   205     }

   206   }

   207 

   208 

   209   /**

   210    * Copy and byte swap elements

   211    *

   212    * <D>    - copy direction

   213    * <swap> - true if elements should be byte swapped

   214    *

   215    * @param src address of source

   216    * @param dst address of destination

   217    * @param byte_count number of bytes to copy

   218    * @param elem_size size of the elements to copy-swap

   219    */

   220   template <CopyDirection D, bool swap>

   221   static void do_conjoint_swap(const void* src, void* dst, size_t byte_count, size_t elem_size) {

   222     switch (elem_size) {

   223     case 2: do_conjoint_swap<uint16_t,D,swap>(src, dst, byte_count); break;

   224     case 4: do_conjoint_swap<uint32_t,D,swap>(src, dst, byte_count); break;

   225     case 8: do_conjoint_swap<uint64_t,D,swap>(src, dst, byte_count); break;

   226     default: guarantee(false, "do_conjoint_swap: Invalid elem_size " SIZE_FORMAT "\n", elem_size);

   227     }

   228   }

   229 };

   230 

   231 void Copy::conjoint_copy(const void* src, void* dst, size_t byte_count, size_t elem_size) {

   232   CopySwap::conjoint_swap_if_needed<false>(src, dst, byte_count, elem_size);

   233 }

   234 

   235 void Copy::conjoint_swap(const void* src, void* dst, size_t byte_count, size_t elem_size) {

   236   CopySwap::conjoint_swap_if_needed<true>(src, dst, byte_count, elem_size);

   237 }

   238 

   239 // Fill bytes; larger units are filled atomically if everything is aligned.

   240 void Copy::fill_to_memory_atomic(void* to, size_t size, jubyte value) {

   241   address dst = (address) to;

   242   uintptr_t bits = (uintptr_t) to | (uintptr_t) size;

   243   if (bits % sizeof(jlong) == 0) {

   244     jlong fill = (julong)( (jubyte)value ); // zero-extend

   245     if (fill != 0) {

   246       fill += fill << 8;

   247       fill += fill << 16;

   248       fill += fill << 32;

   249     }

   250     //Copy::fill_to_jlongs_atomic((jlong*) dst, size / sizeof(jlong));

   251     for (uintptr_t off = 0; off < size; off += sizeof(jlong)) {

   252       *(jlong*)(dst + off) = fill;

   253     }

   254   } else if (bits % sizeof(jint) == 0) {

   255     jint fill = (juint)( (jubyte)value ); // zero-extend

   256     if (fill != 0) {

   257       fill += fill << 8;

   258       fill += fill << 16;

   259     }

   260     //Copy::fill_to_jints_atomic((jint*) dst, size / sizeof(jint));

   261     for (uintptr_t off = 0; off < size; off += sizeof(jint)) {

   262       *(jint*)(dst + off) = fill;

   263     }

   264   } else if (bits % sizeof(jshort) == 0) {

   265     jshort fill = (jushort)( (jubyte)value ); // zero-extend

   266     fill += fill << 8;

   267     //Copy::fill_to_jshorts_atomic((jshort*) dst, size / sizeof(jshort));

   268     for (uintptr_t off = 0; off < size; off += sizeof(jshort)) {

   269       *(jshort*)(dst + off) = fill;

   270     }

   271   } else {

   272     // Not aligned, so no need to be atomic.

   273     Copy::fill_to_bytes(dst, size, value);

   274   }

   275 }