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  #pragma once
27  
28  #include "CodeSpecializationKind.h"
29  #include <wtf/PrintStream.h>
30  
31  // CodeBlock hashes are useful for informally identifying code blocks. They correspond
32  // to the low 32 bits of a SHA1 hash of the source code with two low bit flipped
33  // according to the role that the code block serves (call, construct). Additionally, the
34  // hashes are typically operated over using a string in which the hash is transformed
35  // into a 6-byte alphanumeric representation. This can be retrieved by using
36  // toString(const CodeBlockHash&). Finally, we support CodeBlockHashes for native
37  // functions, in which case the hash is replaced by the function address.
38  
39  namespace JSC {
40  
41  class SourceCode;
42  
43  class CodeBlockHash {
44  public:
45      CodeBlockHash()
46          : m_hash(0)
47      {
48      }
49      
50      explicit CodeBlockHash(unsigned hash)
51          : m_hash(hash)
52      {
53      }
54      
55      CodeBlockHash(const SourceCode&, CodeSpecializationKind);
56      
57      explicit CodeBlockHash(const char*);
58  
59      bool isSet() const { return !!m_hash; }
60      bool operator!() const { return !isSet(); }
61      
62      unsigned hash() const { return m_hash; }
63      
64      void dump(PrintStream&) const;
65      
66      // Comparison methods useful for bisection.
67      bool operator==(const CodeBlockHash& other) const { return hash() == other.hash(); }
68      bool operator!=(const CodeBlockHash& other) const { return hash() != other.hash(); }
69      bool operator<(const CodeBlockHash& other) const { return hash() < other.hash(); }
70      bool operator>(const CodeBlockHash& other) const { return hash() > other.hash(); }
71      bool operator<=(const CodeBlockHash& other) const { return hash() <= other.hash(); }
72      bool operator>=(const CodeBlockHash& other) const { return hash() >= other.hash(); }
73      
74  private:
75      unsigned m_hash;
76  };
77  
78  } // namespace JSC