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Unified Diff: src/heap/slot-set.h

Issue 1725073003: Revert of Replace slots buffer with remembered set. (Closed) Base URL: https://chromium.googlesource.com/v8/v8.git@master
Patch Set: Created 4 years, 10 months ago
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Index: src/heap/slot-set.h
diff --git a/src/heap/slot-set.h b/src/heap/slot-set.h
index e55ffe98e60aa88f74c2e886f226f37eb21bab93..6144706f71e3ed34d81693557b4fe87492499619 100644
--- a/src/heap/slot-set.h
+++ b/src/heap/slot-set.h
@@ -7,12 +7,9 @@
#include "src/allocation.h"
#include "src/base/bits.h"
-#include "src/utils.h"
namespace v8 {
namespace internal {
-
-enum SlotCallbackResult { KEEP_SLOT, REMOVE_SLOT };
// Data structure for maintaining a set of slots in a standard (non-large)
// page. The base address of the page must be set with SetPageStart before any
@@ -22,6 +19,8 @@
// Each bucket is a bitmap with a bit corresponding to a single slot offset.
class SlotSet : public Malloced {
public:
+ enum CallbackResult { KEEP_SLOT, REMOVE_SLOT };
+
SlotSet() {
for (int i = 0; i < kBuckets; i++) {
bucket[i] = nullptr;
@@ -214,124 +213,6 @@
Address page_start_;
};
-enum SlotType {
- EMBEDDED_OBJECT_SLOT,
- OBJECT_SLOT,
- RELOCATED_CODE_OBJECT,
- CELL_TARGET_SLOT,
- CODE_TARGET_SLOT,
- CODE_ENTRY_SLOT,
- DEBUG_TARGET_SLOT,
- NUMBER_OF_SLOT_TYPES
-};
-
-// Data structure for maintaining a multiset of typed slots in a page.
-// Typed slots can only appear in Code and JSFunction objects, so
-// the maximum possible offset is limited by the LargePage::kMaxCodePageSize.
-// The implementation is a chain of chunks, where each chunks is an array of
-// encoded (slot type, slot offset) pairs.
-// There is no duplicate detection and we do not expect many duplicates because
-// typed slots contain V8 internal pointers that are not directly exposed to JS.
-class TypedSlotSet {
- public:
- typedef uint32_t TypedSlot;
- static const int kMaxOffset = 1 << 29;
-
- explicit TypedSlotSet(Address page_start) : page_start_(page_start) {
- chunk_ = new Chunk(nullptr, kInitialBufferSize);
- }
-
- ~TypedSlotSet() {
- Chunk* chunk = chunk_;
- while (chunk != nullptr) {
- Chunk* next = chunk->next;
- delete chunk;
- chunk = next;
- }
- }
-
- // The slot offset specifies a slot at address page_start_ + offset.
- void Insert(SlotType type, int offset) {
- TypedSlot slot = ToTypedSlot(type, offset);
- if (!chunk_->AddSlot(slot)) {
- chunk_ = new Chunk(chunk_, NextCapacity(chunk_->capacity));
- bool added = chunk_->AddSlot(slot);
- DCHECK(added);
- USE(added);
- }
- }
-
- // Iterate over all slots in the set and for each slot invoke the callback.
- // If the callback returns REMOVE_SLOT then the slot is removed from the set.
- // Returns the new number of slots.
- //
- // Sample usage:
- // Iterate([](SlotType slot_type, Address slot_address) {
- // if (good(slot_type, slot_address)) return KEEP_SLOT;
- // else return REMOVE_SLOT;
- // });
- template <typename Callback>
- int Iterate(Callback callback) {
- STATIC_ASSERT(NUMBER_OF_SLOT_TYPES < 8);
- const TypedSlot kRemovedSlot = TypeField::encode(NUMBER_OF_SLOT_TYPES);
- Chunk* chunk = chunk_;
- int new_count = 0;
- while (chunk != nullptr) {
- TypedSlot* buffer = chunk->buffer;
- int count = chunk->count;
- for (int i = 0; i < count; i++) {
- TypedSlot slot = buffer[i];
- if (slot != kRemovedSlot) {
- SlotType type = TypeField::decode(slot);
- Address addr = page_start_ + OffsetField::decode(slot);
- if (callback(type, addr) == KEEP_SLOT) {
- new_count++;
- } else {
- buffer[i] = kRemovedSlot;
- }
- }
- }
- chunk = chunk->next;
- }
- return new_count;
- }
-
- private:
- static const int kInitialBufferSize = 100;
- static const int kMaxBufferSize = 16 * KB;
-
- static int NextCapacity(int capacity) {
- return Min(kMaxBufferSize, capacity * 2);
- }
-
- static TypedSlot ToTypedSlot(SlotType type, int offset) {
- return TypeField::encode(type) | OffsetField::encode(offset);
- }
-
- class OffsetField : public BitField<int, 0, 29> {};
- class TypeField : public BitField<SlotType, 29, 3> {};
-
- struct Chunk : Malloced {
- explicit Chunk(Chunk* next_chunk, int capacity)
- : next(next_chunk), count(0), capacity(capacity) {
- buffer = NewArray<TypedSlot>(capacity);
- }
- bool AddSlot(TypedSlot slot) {
- if (count == capacity) return false;
- buffer[count++] = slot;
- return true;
- }
- ~Chunk() { DeleteArray(buffer); }
- Chunk* next;
- int count;
- int capacity;
- TypedSlot* buffer;
- };
-
- Address page_start_;
- Chunk* chunk_;
-};
-
} // namespace internal
} // namespace v8
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