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Unified Diff: src/mark-compact.cc

Issue 19182002: Added mark bit cell iterator. (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: Created 7 years, 5 months ago
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Index: src/mark-compact.cc
diff --git a/src/mark-compact.cc b/src/mark-compact.cc
index ab5e9366dd0e2701ca82febb38dd61a5700def51..df39a8ae860f646f5c1586b0e3d0bf2fed4f5662 100644
--- a/src/mark-compact.cc
+++ b/src/mark-compact.cc
@@ -1939,40 +1939,28 @@ static void DiscoverGreyObjectsOnPage(MarkingDeque* marking_deque,
ASSERT(strcmp(Marking::kGreyBitPattern, "11") == 0);
ASSERT(strcmp(Marking::kImpossibleBitPattern, "01") == 0);
- MarkBit::CellType* cells = p->markbits()->cells();
-
- int last_cell_index =
- Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(p->area_end())));
-
- Address cell_base = p->area_start();
- int cell_index = Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(cell_base)));
+ for (MarkBitCellIterator it(p); !it.Done(); it.Advance()) {
+ Address cell_base = it.CurrentCellBase();
+ MarkBit::CellType* cell = it.CurrentCell();
-
- for (;
- cell_index < last_cell_index;
- cell_index++, cell_base += 32 * kPointerSize) {
- ASSERT(static_cast<unsigned>(cell_index) ==
- Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(cell_base))));
-
- const MarkBit::CellType current_cell = cells[cell_index];
+ const MarkBit::CellType current_cell = *cell;
if (current_cell == 0) continue;
- const MarkBit::CellType next_cell = cells[cell_index + 1];
- MarkBit::CellType grey_objects = current_cell &
- ((current_cell >> 1) | (next_cell << (Bitmap::kBitsPerCell - 1)));
+ MarkBit::CellType grey_objects;
+ if (it.HasNext()) {
+ const MarkBit::CellType next_cell = *(cell+1);
+ grey_objects = current_cell &
+ ((current_cell >> 1) | (next_cell << (Bitmap::kBitsPerCell - 1)));
+ } else {
+ grey_objects = current_cell & (current_cell >> 1);
+ }
int offset = 0;
while (grey_objects != 0) {
int trailing_zeros = CompilerIntrinsics::CountTrailingZeros(grey_objects);
grey_objects >>= trailing_zeros;
offset += trailing_zeros;
- MarkBit markbit(&cells[cell_index], 1 << offset, false);
+ MarkBit markbit(cell, 1 << offset, false);
ASSERT(Marking::IsGrey(markbit));
Marking::GreyToBlack(markbit);
Address addr = cell_base + offset * kPointerSize;
@@ -2000,25 +1988,11 @@ int MarkCompactCollector::DiscoverAndPromoteBlackObjectsOnPage(
MarkBit::CellType* cells = p->markbits()->cells();
int survivors_size = 0;
- int last_cell_index =
- Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(p->area_end())));
-
- Address cell_base = p->area_start();
- int cell_index = Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(cell_base)));
-
- for (;
- cell_index < last_cell_index;
- cell_index++, cell_base += 32 * kPointerSize) {
- ASSERT(static_cast<unsigned>(cell_index) ==
- Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(cell_base))));
-
- MarkBit::CellType current_cell = cells[cell_index];
+ for (MarkBitCellIterator it(p); !it.Done(); it.Advance()) {
+ Address cell_base = it.CurrentCellBase();
+ MarkBit::CellType* cell = it.CurrentCell();
+
+ MarkBit::CellType current_cell = *cell;
if (current_cell == 0) continue;
int offset = 0;
@@ -2058,7 +2032,7 @@ int MarkCompactCollector::DiscoverAndPromoteBlackObjectsOnPage(
size,
NEW_SPACE);
}
- cells[cell_index] = 0;
+ *cells = 0;
}
return survivors_size;
}
@@ -2985,31 +2959,17 @@ void MarkCompactCollector::EvacuateLiveObjectsFromPage(Page* p) {
AlwaysAllocateScope always_allocate;
PagedSpace* space = static_cast<PagedSpace*>(p->owner());
ASSERT(p->IsEvacuationCandidate() && !p->WasSwept());
- MarkBit::CellType* cells = p->markbits()->cells();
p->MarkSweptPrecisely();
- int last_cell_index =
- Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(p->area_end())));
-
- Address cell_base = p->area_start();
- int cell_index = Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(cell_base)));
-
int offsets[16];
- for (;
- cell_index < last_cell_index;
- cell_index++, cell_base += 32 * kPointerSize) {
- ASSERT(static_cast<unsigned>(cell_index) ==
- Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(cell_base))));
- if (cells[cell_index] == 0) continue;
+ for (MarkBitCellIterator it(p); !it.Done(); it.Advance()) {
+ Address cell_base = it.CurrentCellBase();
+ MarkBit::CellType* cell = it.CurrentCell();
+
+ if (*cell == 0) continue;
- int live_objects = MarkWordToObjectStarts(cells[cell_index], offsets);
+ int live_objects = MarkWordToObjectStarts(*cell, offsets);
for (int i = 0; i < live_objects; i++) {
Address object_addr = cell_base + offsets[i] * kPointerSize;
HeapObject* object = HeapObject::FromAddress(object_addr);
@@ -3034,7 +2994,7 @@ void MarkCompactCollector::EvacuateLiveObjectsFromPage(Page* p) {
}
// Clear marking bits for current cell.
- cells[cell_index] = 0;
+ *cell = 0;
}
p->ResetLiveBytes();
}
@@ -3155,22 +3115,10 @@ static void SweepPrecisely(PagedSpace* space,
start_time = OS::TimeCurrentMillis();
}
- MarkBit::CellType* cells = p->markbits()->cells();
p->MarkSweptPrecisely();
- int last_cell_index =
- Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(p->area_end())));
-
Address free_start = p->area_start();
- int cell_index =
- Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(free_start)));
-
ASSERT(reinterpret_cast<intptr_t>(free_start) % (32 * kPointerSize) == 0);
- Address object_address = free_start;
int offsets[16];
SkipList* skip_list = p->skip_list();
@@ -3179,17 +3127,13 @@ static void SweepPrecisely(PagedSpace* space,
skip_list->Clear();
}
- for (;
- cell_index < last_cell_index;
- cell_index++, object_address += 32 * kPointerSize) {
- ASSERT(static_cast<unsigned>(cell_index) ==
- Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(object_address))));
- int live_objects = MarkWordToObjectStarts(cells[cell_index], offsets);
+ for (MarkBitCellIterator it(p); !it.Done(); it.Advance()) {
+ Address cell_base = it.CurrentCellBase();
+ MarkBit::CellType* cell = it.CurrentCell();
+ int live_objects = MarkWordToObjectStarts(*cell, offsets);
int live_index = 0;
for ( ; live_objects != 0; live_objects--) {
- Address free_end = object_address + offsets[live_index++] * kPointerSize;
+ Address free_end = cell_base + offsets[live_index++] * kPointerSize;
if (free_end != free_start) {
space->Free(free_start, static_cast<int>(free_end - free_start));
#ifdef ENABLE_GDB_JIT_INTERFACE
@@ -3219,7 +3163,7 @@ static void SweepPrecisely(PagedSpace* space,
free_start = free_end + size;
}
// Clear marking bits for current cell.
- cells[cell_index] = 0;
+ *cell = 0;
}
if (free_start != p->area_end()) {
space->Free(free_start, static_cast<int>(p->area_end() - free_start));
@@ -3886,40 +3830,32 @@ intptr_t MarkCompactCollector::SweepConservatively(PagedSpace* space,
(mode == MarkCompactCollector::SWEEP_SEQUENTIALLY &&
free_list == NULL));
- MarkBit::CellType* cells = p->markbits()->cells();
p->MarkSweptConservatively();
- int last_cell_index =
- Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(p->area_end())));
-
- int cell_index =
- Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(p->area_start())));
-
intptr_t freed_bytes = 0;
-
- // This is the start of the 32 word block that we are currently looking at.
- Address block_address = p->area_start();
+ size_t size = 0;
// Skip over all the dead objects at the start of the page and mark them free.
- for (;
- cell_index < last_cell_index;
- cell_index++, block_address += 32 * kPointerSize) {
- if (cells[cell_index] != 0) break;
+ Address cell_base = 0;
+ MarkBit::CellType* cell = NULL;
+ MarkBitCellIterator it(p);
+ for (; !it.Done(); it.Advance()) {
+ cell_base = it.CurrentCellBase();
+ cell = it.CurrentCell();
+ if (*cell != 0) break;
}
- size_t size = block_address - p->area_start();
- if (cell_index == last_cell_index) {
+
+ if (it.Done()) {
+ size = p->area_end() - p->area_start();
freed_bytes += Free<mode>(space, free_list, p->area_start(),
static_cast<int>(size));
ASSERT_EQ(0, p->LiveBytes());
return freed_bytes;
}
+
// Grow the size of the start-of-page free space a little to get up to the
// first live object.
- Address free_end = StartOfLiveObject(block_address, cells[cell_index]);
+ Address free_end = StartOfLiveObject(cell_base, *cell);
// Free the first free space.
size = free_end - p->area_start();
freed_bytes += Free<mode>(space, free_list, p->area_start(),
@@ -3931,45 +3867,40 @@ intptr_t MarkCompactCollector::SweepConservatively(PagedSpace* space,
// started. Unless we find a large free space in the bitmap we will not
// digest this pair into a real address. We start the iteration here at the
// first word in the marking bit map that indicates a live object.
- Address free_start = block_address;
- uint32_t free_start_cell = cells[cell_index];
-
- for ( ;
- cell_index < last_cell_index;
- cell_index++, block_address += 32 * kPointerSize) {
- ASSERT((unsigned)cell_index ==
- Bitmap::IndexToCell(
- Bitmap::CellAlignIndex(
- p->AddressToMarkbitIndex(block_address))));
- uint32_t cell = cells[cell_index];
- if (cell != 0) {
+ Address free_start = cell_base;
+ MarkBit::CellType free_start_cell = *cell;
+
+ for (; !it.Done(); it.Advance()) {
+ cell_base = it.CurrentCellBase();
+ cell = it.CurrentCell();
+ if (*cell != 0) {
// We have a live object. Check approximately whether it is more than 32
// words since the last live object.
- if (block_address - free_start > 32 * kPointerSize) {
+ if (cell_base - free_start > 32 * kPointerSize) {
free_start = DigestFreeStart(free_start, free_start_cell);
- if (block_address - free_start > 32 * kPointerSize) {
+ if (cell_base - free_start > 32 * kPointerSize) {
// Now that we know the exact start of the free space it still looks
// like we have a large enough free space to be worth bothering with.
// so now we need to find the start of the first live object at the
// end of the free space.
- free_end = StartOfLiveObject(block_address, cell);
+ free_end = StartOfLiveObject(cell_base, *cell);
freed_bytes += Free<mode>(space, free_list, free_start,
static_cast<int>(free_end - free_start));
}
}
// Update our undigested record of where the current free area started.
- free_start = block_address;
- free_start_cell = cell;
+ free_start = cell_base;
+ free_start_cell = *cell;
// Clear marking bits for current cell.
- cells[cell_index] = 0;
+ *cell = 0;
}
}
// Handle the free space at the end of the page.
- if (block_address - free_start > 32 * kPointerSize) {
+ if (cell_base - free_start > 32 * kPointerSize) {
free_start = DigestFreeStart(free_start, free_start_cell);
freed_bytes += Free<mode>(space, free_list, free_start,
- static_cast<int>(block_address - free_start));
+ static_cast<int>(p->area_end() - free_start));
}
p->ResetLiveBytes();
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