bytecode/CodeBlockHash.cpp

   1 /*
   2  * Copyright (C) 2012 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 "CodeBlockHash.h"
  28
  29 #include "SourceCode.h"
  30 #include <wtf/SHA1.h>
  31
  32 namespace JSC {
  33
  34 #define TABLE ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789")
  35
  36 CodeBlockHash::CodeBlockHash(const char* string)
  37     : m_hash(0)
  38 {
  39     RELEASE_ASSERT(strlen(string) == 6);
  40
  41     for (unsigned i = 0; i < 6; ++i) {
  42         m_hash *= 62;
  43         unsigned c = string[i];
  44         if (c >= 'A' && c <= 'Z') {
  45             m_hash += c - 'A';
  46             continue;
  47         }
  48         if (c >= 'a' && c <= 'z') {
  49             m_hash += c - 'a' + 26;
  50             continue;
  51         }
  52         ASSERT(c >= '0' && c <= '9');
  53         m_hash += c - '0' + 26 * 2;
  54     }
  55 }
  56
  57 CodeBlockHash::CodeBlockHash(const SourceCode& sourceCode, CodeSpecializationKind kind)
  58     : m_hash(0)
  59 {
  60     SHA1 sha1;
  61     sha1.addBytes(sourceCode.toString().utf8());
  62     Vector<uint8_t, 20> digest;
  63     sha1.computeHash(digest);
  64     m_hash += digest[0] | (digest[1] << 8) | (digest[2] << 16) | (digest[3] << 24);
  65     m_hash ^= static_cast<unsigned>(kind);
  66 }
  67
  68 void CodeBlockHash::dump(PrintStream& out) const
  69 {
  70     ASSERT(strlen(TABLE) == 62);
  71
  72     char buffer[7];
  73     unsigned accumulator = m_hash;
  74     for (unsigned i = 6; i--;) {
  75         buffer[i] = TABLE[accumulator % 62];
  76         accumulator /= 62;
  77     }
  78     buffer[6] = 0;
  79
  80 #if !ASSERT_DISABLED
  81     CodeBlockHash recompute(buffer);
  82     ASSERT(recompute == *this);
  83 #endif // !ASSERT_DISABLED
  84
  85     out.print(buffer);
  86 }
  87
  88 } // namespace JSC
  89