bytecode/CodeBlockHash.h

   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 #ifndef CodeBlockHash_h
  27 #define CodeBlockHash_h
  28
  29 #include "CodeSpecializationKind.h"
  30 #include <wtf/PrintStream.h>
  31
  32 // CodeBlock hashes are useful for informally identifying code blocks. They correspond
  33 // to the low 32 bits of a SHA1 hash of the source code with two low bit flipped
  34 // according to the role that the code block serves (call, construct). Additionally, the
  35 // hashes are typically operated over using a string in which the hash is transformed
  36 // into a 6-byte alphanumeric representation. This can be retrieved by using
  37 // toString(const CodeBlockHash&). Finally, we support CodeBlockHashes for native
  38 // functions, in which case the hash is replaced by the function address.
  39
  40 namespace JSC {
  41
  42 class SourceCode;
  43
  44 class CodeBlockHash {
  45 public:
  46     CodeBlockHash()
  47         : m_hash(0)
  48     {
  49     }
  50
  51     explicit CodeBlockHash(unsigned hash)
  52         : m_hash(hash)
  53     {
  54     }
  55
  56     CodeBlockHash(const SourceCode&, CodeSpecializationKind);
  57
  58     explicit CodeBlockHash(const char*);
  59
  60     bool isSet() const { return !!m_hash; }
  61     bool operator!() const { return !isSet(); }
  62
  63     unsigned hash() const { return m_hash; }
  64
  65     void dump(PrintStream&) const;
  66
  67     // Comparison methods useful for bisection.
  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     bool operator>=(const CodeBlockHash& other) const { return hash() >= other.hash(); }
  74
  75 private:
  76     unsigned m_hash;
  77 };
  78
  79 } // namespace JSC
  80
  81 #endif // CodeBlockHash_h