Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame^] | 1 | // Copyright 2015 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #include "src/heap/slots-buffer.h" |
| 6 | |
| 7 | #include "src/assembler.h" |
| 8 | #include "src/heap/heap.h" |
| 9 | #include "src/objects-inl.h" |
| 10 | |
| 11 | namespace v8 { |
| 12 | namespace internal { |
| 13 | |
| 14 | bool SlotsBuffer::IsTypedSlot(ObjectSlot slot) { |
| 15 | return reinterpret_cast<uintptr_t>(slot) < NUMBER_OF_SLOT_TYPES; |
| 16 | } |
| 17 | |
| 18 | |
| 19 | bool SlotsBuffer::AddTo(SlotsBufferAllocator* allocator, |
| 20 | SlotsBuffer** buffer_address, SlotType type, |
| 21 | Address addr, AdditionMode mode) { |
| 22 | SlotsBuffer* buffer = *buffer_address; |
| 23 | if (buffer == NULL || !buffer->HasSpaceForTypedSlot()) { |
| 24 | if (mode == FAIL_ON_OVERFLOW && ChainLengthThresholdReached(buffer)) { |
| 25 | allocator->DeallocateChain(buffer_address); |
| 26 | return false; |
| 27 | } |
| 28 | buffer = allocator->AllocateBuffer(buffer); |
| 29 | *buffer_address = buffer; |
| 30 | } |
| 31 | DCHECK(buffer->HasSpaceForTypedSlot()); |
| 32 | buffer->Add(reinterpret_cast<ObjectSlot>(type)); |
| 33 | buffer->Add(reinterpret_cast<ObjectSlot>(addr)); |
| 34 | return true; |
| 35 | } |
| 36 | |
| 37 | |
| 38 | void SlotsBuffer::RemoveInvalidSlots(Heap* heap, SlotsBuffer* buffer) { |
| 39 | // Remove entries by replacing them with an old-space slot containing a smi |
| 40 | // that is located in an unmovable page. |
| 41 | const ObjectSlot kRemovedEntry = HeapObject::RawField( |
| 42 | heap->empty_fixed_array(), FixedArrayBase::kLengthOffset); |
| 43 | DCHECK(Page::FromAddress(reinterpret_cast<Address>(kRemovedEntry)) |
| 44 | ->NeverEvacuate()); |
| 45 | |
| 46 | while (buffer != NULL) { |
| 47 | SlotsBuffer::ObjectSlot* slots = buffer->slots_; |
| 48 | intptr_t slots_count = buffer->idx_; |
| 49 | |
| 50 | for (int slot_idx = 0; slot_idx < slots_count; ++slot_idx) { |
| 51 | ObjectSlot slot = slots[slot_idx]; |
| 52 | if (!IsTypedSlot(slot)) { |
| 53 | Object* object = *slot; |
| 54 | // Slots are invalid when they currently: |
| 55 | // - do not point to a heap object (SMI) |
| 56 | // - point to a heap object in new space |
| 57 | // - are not within a live heap object on a valid pointer slot |
| 58 | // - point to a heap object not on an evacuation candidate |
| 59 | if (!object->IsHeapObject() || heap->InNewSpace(object) || |
| 60 | !heap->mark_compact_collector()->IsSlotInLiveObject( |
| 61 | reinterpret_cast<Address>(slot)) || |
| 62 | !Page::FromAddress(reinterpret_cast<Address>(object)) |
| 63 | ->IsEvacuationCandidate()) { |
| 64 | // TODO(hpayer): Instead of replacing slots with kRemovedEntry we |
| 65 | // could shrink the slots buffer in-place. |
| 66 | slots[slot_idx] = kRemovedEntry; |
| 67 | } |
| 68 | } else { |
| 69 | ++slot_idx; |
| 70 | DCHECK(slot_idx < slots_count); |
| 71 | } |
| 72 | } |
| 73 | buffer = buffer->next(); |
| 74 | } |
| 75 | } |
| 76 | |
| 77 | |
| 78 | void SlotsBuffer::RemoveObjectSlots(Heap* heap, SlotsBuffer* buffer, |
| 79 | Address start_slot, Address end_slot) { |
| 80 | // Remove entries by replacing them with an old-space slot containing a smi |
| 81 | // that is located in an unmovable page. |
| 82 | const ObjectSlot kRemovedEntry = HeapObject::RawField( |
| 83 | heap->empty_fixed_array(), FixedArrayBase::kLengthOffset); |
| 84 | DCHECK(Page::FromAddress(reinterpret_cast<Address>(kRemovedEntry)) |
| 85 | ->NeverEvacuate()); |
| 86 | |
| 87 | while (buffer != NULL) { |
| 88 | SlotsBuffer::ObjectSlot* slots = buffer->slots_; |
| 89 | intptr_t slots_count = buffer->idx_; |
| 90 | bool is_typed_slot = false; |
| 91 | |
| 92 | for (int slot_idx = 0; slot_idx < slots_count; ++slot_idx) { |
| 93 | ObjectSlot slot = slots[slot_idx]; |
| 94 | if (!IsTypedSlot(slot)) { |
| 95 | Address slot_address = reinterpret_cast<Address>(slot); |
| 96 | if (slot_address >= start_slot && slot_address < end_slot) { |
| 97 | // TODO(hpayer): Instead of replacing slots with kRemovedEntry we |
| 98 | // could shrink the slots buffer in-place. |
| 99 | slots[slot_idx] = kRemovedEntry; |
| 100 | if (is_typed_slot) { |
| 101 | slots[slot_idx - 1] = kRemovedEntry; |
| 102 | } |
| 103 | } |
| 104 | is_typed_slot = false; |
| 105 | } else { |
| 106 | is_typed_slot = true; |
| 107 | DCHECK(slot_idx < slots_count); |
| 108 | } |
| 109 | } |
| 110 | buffer = buffer->next(); |
| 111 | } |
| 112 | } |
| 113 | |
| 114 | |
| 115 | void SlotsBuffer::VerifySlots(Heap* heap, SlotsBuffer* buffer) { |
| 116 | while (buffer != NULL) { |
| 117 | SlotsBuffer::ObjectSlot* slots = buffer->slots_; |
| 118 | intptr_t slots_count = buffer->idx_; |
| 119 | |
| 120 | for (int slot_idx = 0; slot_idx < slots_count; ++slot_idx) { |
| 121 | ObjectSlot slot = slots[slot_idx]; |
| 122 | if (!IsTypedSlot(slot)) { |
| 123 | Object* object = *slot; |
| 124 | if (object->IsHeapObject()) { |
| 125 | HeapObject* heap_object = HeapObject::cast(object); |
| 126 | CHECK(!heap->InNewSpace(object)); |
| 127 | heap->mark_compact_collector()->VerifyIsSlotInLiveObject( |
| 128 | reinterpret_cast<Address>(slot), heap_object); |
| 129 | } |
| 130 | } else { |
| 131 | ++slot_idx; |
| 132 | DCHECK(slot_idx < slots_count); |
| 133 | } |
| 134 | } |
| 135 | buffer = buffer->next(); |
| 136 | } |
| 137 | } |
| 138 | |
| 139 | |
| 140 | SlotsBuffer* SlotsBufferAllocator::AllocateBuffer(SlotsBuffer* next_buffer) { |
| 141 | return new SlotsBuffer(next_buffer); |
| 142 | } |
| 143 | |
| 144 | |
| 145 | void SlotsBufferAllocator::DeallocateBuffer(SlotsBuffer* buffer) { |
| 146 | delete buffer; |
| 147 | } |
| 148 | |
| 149 | |
| 150 | void SlotsBufferAllocator::DeallocateChain(SlotsBuffer** buffer_address) { |
| 151 | SlotsBuffer* buffer = *buffer_address; |
| 152 | while (buffer != NULL) { |
| 153 | SlotsBuffer* next_buffer = buffer->next(); |
| 154 | DeallocateBuffer(buffer); |
| 155 | buffer = next_buffer; |
| 156 | } |
| 157 | *buffer_address = NULL; |
| 158 | } |
| 159 | |
| 160 | } // namespace internal |
| 161 | } // namespace v8 |