ftl/FTLAbstractHeap.h

   1 /*
   2  * Copyright (C) 2013 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 FTLAbstractHeap_h
  27 #define FTLAbstractHeap_h
  28
  29 #if ENABLE(FTL_JIT)
  30
  31 #include "FTLAbbreviations.h"
  32 #include "JSCJSValue.h"
  33 #include <array>
  34 #include <wtf/FastMalloc.h>
  35 #include <wtf/HashMap.h>
  36 #include <wtf/Noncopyable.h>
  37 #include <wtf/OwnPtr.h>
  38 #include <wtf/Vector.h>
  39 #include <wtf/text/CString.h>
  40
  41 namespace JSC { namespace FTL {
  42
  43 // The FTL JIT tries to aid LLVM's TBAA. The FTL's notion of how this
  44 // happens is the AbstractHeap. AbstractHeaps are a simple type system
  45 // with sub-typing.
  46
  47 class AbstractHeapRepository;
  48 class Output;
  49 class TypedPointer;
  50
  51 class AbstractHeap {
  52     WTF_MAKE_NONCOPYABLE(AbstractHeap); WTF_MAKE_FAST_ALLOCATED;
  53 public:
  54     AbstractHeap()
  55         : m_parent(0)
  56         , m_heapName(0)
  57         , m_tbaaMetadata(0)
  58     {
  59     }
  60
  61     AbstractHeap(AbstractHeap* parent, const char* heapName)
  62         : m_parent(parent)
  63         , m_heapName(heapName)
  64         , m_tbaaMetadata(0)
  65     {
  66     }
  67
  68     bool isInitialized() const { return !!m_heapName; }
  69
  70     void initialize(AbstractHeap* parent, const char* heapName)
  71     {
  72         m_parent = parent;
  73         m_heapName = heapName;
  74     }
  75
  76     AbstractHeap* parent() const
  77     {
  78         ASSERT(isInitialized());
  79         return m_parent;
  80     }
  81
  82     const char* heapName() const
  83     {
  84         ASSERT(isInitialized());
  85         return m_heapName;
  86     }
  87
  88     LValue tbaaMetadata(const AbstractHeapRepository& repository) const
  89     {
  90         ASSERT(isInitialized());
  91         if (LIKELY(!!m_tbaaMetadata))
  92             return m_tbaaMetadata;
  93         return tbaaMetadataSlow(repository);
  94     }
  95
  96     void decorateInstruction(LValue instruction, const AbstractHeapRepository&) const;
  97
  98 private:
  99     friend class AbstractHeapRepository;
 100
 101     LValue tbaaMetadataSlow(const AbstractHeapRepository&) const;
 102
 103     AbstractHeap* m_parent;
 104     const char* m_heapName;
 105     mutable LValue m_tbaaMetadata;
 106 };
 107
 108 // Think of "AbstractField" as being an "AbstractHeapWithOffset". I would have named
 109 // it the latter except that I don't like typing that much.
 110 class AbstractField : public AbstractHeap {
 111 public:
 112     AbstractField()
 113     {
 114     }
 115
 116     AbstractField(AbstractHeap* parent, const char* heapName, ptrdiff_t offset)
 117         : AbstractHeap(parent, heapName)
 118         , m_offset(offset)
 119     {
 120     }
 121
 122     void initialize(AbstractHeap* parent, const char* heapName, ptrdiff_t offset)
 123     {
 124         AbstractHeap::initialize(parent, heapName);
 125         m_offset = offset;
 126     }
 127
 128     ptrdiff_t offset() const
 129     {
 130         ASSERT(isInitialized());
 131         return m_offset;
 132     }
 133
 134 private:
 135     ptrdiff_t m_offset;
 136 };
 137
 138 class IndexedAbstractHeap {
 139 public:
 140     IndexedAbstractHeap(LContext, AbstractHeap* parent, const char* heapName, ptrdiff_t offset, size_t elementSize);
 141     ~IndexedAbstractHeap();
 142
 143     const AbstractHeap& atAnyIndex() const { return m_heapForAnyIndex; }
 144
 145     const AbstractField& at(ptrdiff_t index)
 146     {
 147         if (static_cast<size_t>(index) < m_smallIndices.size())
 148             return returnInitialized(m_smallIndices[index], index);
 149         return atSlow(index);
 150     }
 151
 152     const AbstractField& operator[](ptrdiff_t index) { return at(index); }
 153
 154     TypedPointer baseIndex(Output& out, LValue base, LValue index, JSValue indexAsConstant = JSValue(), ptrdiff_t offset = 0);
 155
 156 private:
 157     const AbstractField& returnInitialized(AbstractField& field, ptrdiff_t index)
 158     {
 159         if (UNLIKELY(!field.isInitialized()))
 160             initialize(field, index);
 161         return field;
 162     }
 163
 164     const AbstractField& atSlow(ptrdiff_t index);
 165     void initialize(AbstractField& field, ptrdiff_t index);
 166
 167     AbstractHeap m_heapForAnyIndex;
 168     size_t m_heapNameLength;
 169     ptrdiff_t m_offset;
 170     size_t m_elementSize;
 171     LValue m_scaleTerm;
 172     bool m_canShift;
 173     std::array<AbstractField, 16> m_smallIndices;
 174
 175     struct WithoutZeroOrOneHashTraits : WTF::GenericHashTraits<ptrdiff_t> {
 176         static void constructDeletedValue(ptrdiff_t& slot) { slot = 1; }
 177         static bool isDeletedValue(ptrdiff_t value) { return value == 1; }
 178     };
 179     typedef HashMap<ptrdiff_t, std::unique_ptr<AbstractField>, WTF::IntHash<ptrdiff_t>, WithoutZeroOrOneHashTraits> MapType;
 180
 181     OwnPtr<MapType> m_largeIndices;
 182     Vector<CString, 16> m_largeIndexNames;
 183 };
 184
 185 // A numbered abstract heap is like an indexed abstract heap, except that you
 186 // can't rely on there being a relationship between the number you use to
 187 // retrieve the sub-heap, and the offset that this heap has. (In particular,
 188 // the sub-heaps don't have indices.)
 189
 190 class NumberedAbstractHeap {
 191 public:
 192     NumberedAbstractHeap(LContext, AbstractHeap* parent, const char* heapName);
 193     ~NumberedAbstractHeap();
 194
 195     const AbstractHeap& atAnyNumber() const { return m_indexedHeap.atAnyIndex(); }
 196
 197     const AbstractHeap& at(unsigned number) { return m_indexedHeap.at(number); }
 198     const AbstractHeap& operator[](unsigned number) { return at(number); }
 199
 200 private:
 201
 202     // We use the fact that the indexed heap already has a superset of the
 203     // functionality we need.
 204     IndexedAbstractHeap m_indexedHeap;
 205 };
 206
 207 class AbsoluteAbstractHeap {
 208 public:
 209     AbsoluteAbstractHeap(LContext, AbstractHeap* parent, const char* heapName);
 210     ~AbsoluteAbstractHeap();
 211
 212     const AbstractHeap& atAnyAddress() const { return m_indexedHeap.atAnyIndex(); }
 213
 214     const AbstractHeap& at(void* address)
 215     {
 216         return m_indexedHeap.at(bitwise_cast<ptrdiff_t>(address));
 217     }
 218
 219     const AbstractHeap& operator[](void* address) { return at(address); }
 220
 221 private:
 222     // The trick here is that the indexed heap is "indexed" by a pointer-width
 223     // integer. Pointers are themselves pointer-width integers. So we can reuse
 224     // all of the functionality.
 225     IndexedAbstractHeap m_indexedHeap;
 226 };
 227
 228 } } // namespace JSC::FTL
 229
 230 #endif // ENABLE(FTL_JIT)
 231
 232 #endif // FTLAbstractHeap_h
 233