bytecode/MethodOfGettingAValueProfile.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 MethodOfGettingAValueProfile_h
  27 #define MethodOfGettingAValueProfile_h
  28
  29 #include <wtf/Platform.h>
  30
  31 // This is guarded by ENABLE_DFG_JIT only because it uses some value profiles
  32 // that are currently only used if the DFG is enabled (i.e. they are not
  33 // available in the profile-only configuration). Hopefully someday all of
  34 // these #if's will disappear...
  35 #if ENABLE(DFG_JIT)
  36
  37 #include "JSCJSValue.h"
  38
  39 namespace JSC {
  40
  41 class CodeBlock;
  42 class LazyOperandValueProfileKey;
  43 struct ValueProfile;
  44
  45 class MethodOfGettingAValueProfile {
  46 public:
  47     MethodOfGettingAValueProfile()
  48         : m_kind(None)
  49     {
  50     }
  51
  52     explicit MethodOfGettingAValueProfile(ValueProfile* profile)
  53     {
  54         if (profile) {
  55             m_kind = Ready;
  56             u.profile = profile;
  57         } else
  58             m_kind = None;
  59     }
  60
  61     static MethodOfGettingAValueProfile fromLazyOperand(
  62         CodeBlock*, const LazyOperandValueProfileKey&);
  63
  64     bool operator!() const { return m_kind == None; }
  65
  66     // This logically has a pointer to a "There exists X such that
  67     // ValueProfileBase<X>". But since C++ does not have existential
  68     // templates, I cannot return it. So instead, for any methods that
  69     // users of this class would like to call, we'll just have to provide
  70     // a method here that does it through an indirection. Or we could
  71     // possibly just make ValueProfile less template-based. But last I
  72     // tried that, it felt more yucky than this class.
  73
  74     EncodedJSValue* getSpecFailBucket(unsigned index) const;
  75
  76 private:
  77     enum Kind {
  78         None,
  79         Ready,
  80         LazyOperand
  81     };
  82
  83     Kind m_kind;
  84     union {
  85         ValueProfile* profile;
  86         struct {
  87             CodeBlock* codeBlock;
  88             unsigned bytecodeOffset;
  89             int operand;
  90         } lazyOperand;
  91     } u;
  92 };
  93
  94 } // namespace JSC
  95
  96 #endif // ENABLE(DFG_JIT)
  97
  98 #endif // MethodOfGettingAValueProfile_h
  99