1  /*
 2   * Copyright (C) 2016 Apple Inc. All rights reserved.
 3   *
 4   * Redistribution and use in source and binary forms, with or without
 5   * modification, are permitted provided that the following conditions
 6   * are met:
 7   * 1. Redistributions of source code must retain the above copyright
 8   *    notice, this list of conditions and the following disclaimer.
 9   * 2. Redistributions in binary form must reproduce the above copyright
10   *    notice, this list of conditions and the following disclaimer in the
11   *    documentation and/or other materials provided with the distribution.
12   *
13   * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14   * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
17   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21   * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
24   */
25  
26  #include "config.h"
27  #include "ArrayConventions.h"
28  
29  #include "GCMemoryOperations.h"
30  
31  namespace JSC {
32  
33  #if USE(JSVALUE64)
34  void clearArrayMemset(WriteBarrier<Unknown>* base, unsigned count)
35  {
36      gcSafeZeroMemory(base, count * sizeof(WriteBarrier<Unknown>));
37  }
38  
39  void clearArrayMemset(double* base, unsigned count)
40  {
41  #if CPU(X86_64) && COMPILER(GCC_COMPATIBLE)
42      uint64_t pnan = bitwise_cast<uint64_t>(PNaN);
43      asm volatile (
44          "rep stosq\n\t"
45          : "+D"(base), "+c"(count)
46          : "a"(pnan)
47          : "memory"
48          );
49  #else // not CPU(X86_64)
50      // Oh no, we can't actually do any better than this!
51      for (unsigned i = count; i--;)
52          base[i] = PNaN;
53  #endif // generic CPU
54  }
55  #endif // USE(JSVALUE64)
56  
57  } // namespace JSC
58