1  /*
  2   * Copyright (C) 2018 Yusuke Suzuki <utatane.tea@gmail.com>.
  3   * Copyright (C) 2018 Apple Inc. All rights reserved.
  4   *
  5   * Redistribution and use in source and binary forms, with or without
  6   * modification, are permitted provided that the following conditions
  7   * are met:
  8   * 1. Redistributions of source code must retain the above copyright
  9   *    notice, this list of conditions and the following disclaimer.
 10   * 2. Redistributions in binary form must reproduce the above copyright
 11   *    notice, this list of conditions and the following disclaimer in the
 12   *    documentation and/or other materials provided with the distribution.
 13   *
 14   * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 15   * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 16   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 17   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 18   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 19   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 20   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 21   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 22   * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 23   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 24   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 25   */
 26  
 27  #pragma once
 28  
 29  #include "CallLinkStatus.h"
 30  #include "CodeOrigin.h"
 31  #include "ConcurrentJSLock.h"
 32  #include "ICStatusMap.h"
 33  #include "InByIdVariant.h"
 34  #include "StubInfoSummary.h"
 35  
 36  namespace JSC {
 37  
 38  class AccessCase;
 39  class CodeBlock;
 40  class StructureStubInfo;
 41  
 42  class InByIdStatus final {
 43      WTF_MAKE_FAST_ALLOCATED;
 44  public:
 45      enum State {
 46          // It's uncached so we have no information.
 47          NoInformation,
 48          // It's cached for a simple access to a known object property with
 49          // a possible structure chain and a possible specific value.
 50          Simple,
 51          // It's known to often take slow path.
 52          TakesSlowPath,
 53      };
 54  
 55      InByIdStatus() = default;
 56  
 57      InByIdStatus(State state, const InByIdVariant& variant = InByIdVariant())
 58          : m_state(state)
 59      {
 60          ASSERT((state == Simple) == variant.isSet());
 61          if (variant.isSet())
 62              m_variants.append(variant);
 63      }
 64  
 65      explicit InByIdStatus(StubInfoSummary summary)
 66      {
 67          switch (summary) {
 68          case StubInfoSummary::NoInformation:
 69              m_state = NoInformation;
 70              return;
 71          case StubInfoSummary::Simple:
 72          case StubInfoSummary::MakesCalls:
 73              RELEASE_ASSERT_NOT_REACHED();
 74              return;
 75          case StubInfoSummary::TakesSlowPath:
 76          case StubInfoSummary::TakesSlowPathAndMakesCalls:
 77              m_state = TakesSlowPath;
 78              return;
 79          }
 80          RELEASE_ASSERT_NOT_REACHED();
 81      }
 82      
 83      static InByIdStatus computeFor(CodeBlock*, ICStatusMap&, BytecodeIndex, UniquedStringImpl* uid);
 84      static InByIdStatus computeFor(CodeBlock*, ICStatusMap&, BytecodeIndex, UniquedStringImpl* uid, ExitFlag);
 85      static InByIdStatus computeFor(CodeBlock* baselineBlock, ICStatusMap& baselineMap, ICStatusContextStack& contextStack, CodeOrigin, UniquedStringImpl* uid);
 86  
 87  #if ENABLE(DFG_JIT)
 88      static InByIdStatus computeForStubInfo(const ConcurrentJSLocker&, CodeBlock* baselineBlock, StructureStubInfo*, CodeOrigin, UniquedStringImpl* uid);
 89  #endif
 90  
 91      State state() const { return m_state; }
 92  
 93      bool isSet() const { return m_state != NoInformation; }
 94      explicit operator bool() const { return isSet(); }
 95      bool isSimple() const { return m_state == Simple; }
 96  
 97      size_t numVariants() const { return m_variants.size(); }
 98      const Vector<InByIdVariant, 1>& variants() const { return m_variants; }
 99      const InByIdVariant& at(size_t index) const { return m_variants[index]; }
100      const InByIdVariant& operator[](size_t index) const { return at(index); }
101  
102      bool takesSlowPath() const { return m_state == TakesSlowPath; }
103      
104      void merge(const InByIdStatus&);
105  
106      // Attempts to reduce the set of variants to fit the given structure set. This may be approximate.
107      void filter(const StructureSet&);
108      
109      void markIfCheap(SlotVisitor&);
110      bool finalize(VM&);
111  
112      void dump(PrintStream&) const;
113  
114  private:
115  #if ENABLE(DFG_JIT)
116      static InByIdStatus computeForStubInfoWithoutExitSiteFeedback(const ConcurrentJSLocker&, VM&, StructureStubInfo*, UniquedStringImpl* uid);
117  #endif
118      bool appendVariant(const InByIdVariant&);
119  
120      State m_state { NoInformation };
121      Vector<InByIdVariant, 1> m_variants;
122  };
123  
124  } // namespace JSC