jit/JITStubRoutine.h

   1 /*
   2  * Copyright (C) 2012, 2014 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 JITStubRoutine_h
  27 #define JITStubRoutine_h
  28
  29 #if ENABLE(JIT)
  30
  31 #include "ExecutableAllocator.h"
  32 #include "MacroAssemblerCodeRef.h"
  33 #include <wtf/RefCounted.h>
  34 #include <wtf/Vector.h>
  35
  36 namespace JSC {
  37
  38 class JITStubRoutineSet;
  39 class RepatchBuffer;
  40
  41 // This is a base-class for JIT stub routines, and also the class you want
  42 // to instantiate directly if you have a routine that does not need any
  43 // help from the GC. If in doubt, use one of the other stub routines. But
  44 // if you know for sure that the stub routine cannot be on the stack while
  45 // someone triggers a stub routine reset, then using this will speed up
  46 // memory reclamation. One case where a stub routine satisfies this
  47 // condition is if it doesn't make any calls, to either C++ or JS code. In
  48 // such a routine you know that it cannot be on the stack when anything
  49 // interesting happens.
  50 // See GCAwareJITStubRoutine.h for the other stub routines.
  51 class JITStubRoutine {
  52     WTF_MAKE_NONCOPYABLE(JITStubRoutine);
  53     WTF_MAKE_FAST_ALLOCATED;
  54 public:
  55     JITStubRoutine(const MacroAssemblerCodeRef& code)
  56         : m_code(code)
  57         , m_refCount(1)
  58     {
  59     }
  60
  61     // Use this if you want to pass a CodePtr to someone who insists on taking
  62     // a RefPtr<JITStubRoutine>.
  63     static PassRefPtr<JITStubRoutine> createSelfManagedRoutine(
  64         MacroAssemblerCodePtr rawCodePointer)
  65     {
  66         return adoptRef(new JITStubRoutine(MacroAssemblerCodeRef::createSelfManagedCodeRef(rawCodePointer)));
  67     }
  68
  69     virtual ~JITStubRoutine();
  70
  71     // MacroAssemblerCodeRef is copyable, but at the cost of reference
  72     // counting churn. Returning a reference is a good way of reducing
  73     // the churn.
  74     const MacroAssemblerCodeRef& code() const { return m_code; }
  75
  76     static MacroAssemblerCodePtr asCodePtr(PassRefPtr<JITStubRoutine> stubRoutine)
  77     {
  78         if (!stubRoutine)
  79             return MacroAssemblerCodePtr();
  80
  81         MacroAssemblerCodePtr result = stubRoutine->code().code();
  82         ASSERT(!!result);
  83         return result;
  84     }
  85
  86     void ref()
  87     {
  88         m_refCount++;
  89     }
  90
  91     void deref()
  92     {
  93         if (--m_refCount)
  94             return;
  95         observeZeroRefCount();
  96     }
  97
  98     // Helpers for the GC to determine how to deal with marking JIT stub
  99     // routines.
 100     uintptr_t startAddress() const { return m_code.executableMemory()->startAsInteger(); }
 101     uintptr_t endAddress() const { return m_code.executableMemory()->endAsInteger(); }
 102     static uintptr_t addressStep() { return jitAllocationGranule; }
 103
 104     static bool canPerformRangeFilter()
 105     {
 106 #if ENABLE(EXECUTABLE_ALLOCATOR_FIXED)
 107         return true;
 108 #else
 109         return false;
 110 #endif
 111     }
 112     static uintptr_t filteringStartAddress()
 113     {
 114 #if ENABLE(EXECUTABLE_ALLOCATOR_FIXED)
 115         return startOfFixedExecutableMemoryPool;
 116 #else
 117         UNREACHABLE_FOR_PLATFORM();
 118         return 0;
 119 #endif
 120     }
 121     static size_t filteringExtentSize()
 122     {
 123 #if ENABLE(EXECUTABLE_ALLOCATOR_FIXED)
 124         return fixedExecutableMemoryPoolSize;
 125 #else
 126         UNREACHABLE_FOR_PLATFORM();
 127         return 0;
 128 #endif
 129     }
 130     static bool passesFilter(uintptr_t address)
 131     {
 132         if (!canPerformRangeFilter()) {
 133             // Just check that the address doesn't use any special values that would make
 134             // our hashtables upset.
 135             return address >= jitAllocationGranule && address != std::numeric_limits<uintptr_t>::max();
 136         }
 137
 138         if (address - filteringStartAddress() >= filteringExtentSize())
 139             return false;
 140
 141         return true;
 142     }
 143
 144     virtual bool visitWeak(RepatchBuffer&);
 145
 146 protected:
 147     virtual void observeZeroRefCount();
 148
 149     MacroAssemblerCodeRef m_code;
 150     unsigned m_refCount;
 151 };
 152
 153 // Helper for the creation of simple stub routines that need no help from the GC.
 154 #define FINALIZE_CODE_FOR_STUB(codeBlock, patchBuffer, dataLogFArguments) \
 155     (adoptRef(new JITStubRoutine(FINALIZE_CODE_FOR((codeBlock), (patchBuffer), dataLogFArguments))))
 156
 157 } // namespace JSC
 158
 159 #endif // ENABLE(JIT)
 160
 161 #endif // JITStubRoutine_h
 162