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/*
* Copyright 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_RUNTIME_GC_COLLECTOR_MARK_COMPACT_INL_H_
#define ART_RUNTIME_GC_COLLECTOR_MARK_COMPACT_INL_H_
#include "gc/space/bump_pointer_space.h"
#include "mark_compact.h"
#include "mirror/object-inl.h"
namespace art {
namespace gc {
namespace collector {
inline void MarkCompact::UpdateClassAfterObjectMap(mirror::Object* obj) {
mirror::Class* klass = obj->GetClass<kVerifyNone, kWithoutReadBarrier>();
// Track a class if it needs walking super-classes for visiting references or
// if it's higher in address order than its objects and is in moving space.
if (UNLIKELY(
(std::less<mirror::Object*>{}(obj, klass) && HasAddress(klass)) ||
(klass->GetReferenceInstanceOffsets<kVerifyNone>() == mirror::Class::kClassWalkSuper &&
walk_super_class_cache_ != klass))) {
// Since this function gets invoked in the compaction pause as well, it is
// preferable to store such super class separately rather than updating key
// as the latter would require traversing the hierarchy for every object of 'klass'.
auto ret1 = class_after_obj_hash_map_.try_emplace(ObjReference::FromMirrorPtr(klass),
ObjReference::FromMirrorPtr(obj));
if (ret1.second) {
if (klass->GetReferenceInstanceOffsets<kVerifyNone>() == mirror::Class::kClassWalkSuper) {
// In this case we require traversing through the super class hierarchy
// and find the super class at the highest address order.
mirror::Class* highest_klass = HasAddress(klass) ? klass : nullptr;
for (ObjPtr<mirror::Class> k = klass->GetSuperClass<kVerifyNone, kWithoutReadBarrier>();
k != nullptr;
k = k->GetSuperClass<kVerifyNone, kWithoutReadBarrier>()) {
// TODO: Can we break once we encounter a super class outside the moving space?
if (HasAddress(k.Ptr())) {
highest_klass = std::max(highest_klass, k.Ptr(), std::less<mirror::Class*>());
}
}
if (highest_klass != nullptr && highest_klass != klass) {
auto ret2 = super_class_after_class_hash_map_.try_emplace(
ObjReference::FromMirrorPtr(klass), ObjReference::FromMirrorPtr(highest_klass));
DCHECK(ret2.second);
} else {
walk_super_class_cache_ = klass;
}
}
} else if (std::less<mirror::Object*>{}(obj, ret1.first->second.AsMirrorPtr())) {
ret1.first->second = ObjReference::FromMirrorPtr(obj);
}
}
}
template <size_t kAlignment>
inline uintptr_t MarkCompact::LiveWordsBitmap<kAlignment>::SetLiveWords(uintptr_t begin,
size_t size) {
const uintptr_t begin_bit_idx = MemRangeBitmap::BitIndexFromAddr(begin);
DCHECK(!Bitmap::TestBit(begin_bit_idx));
// Range to set bit: [begin, end]
uintptr_t end = begin + size - kAlignment;
const uintptr_t end_bit_idx = MemRangeBitmap::BitIndexFromAddr(end);
uintptr_t* begin_bm_address = Bitmap::Begin() + Bitmap::BitIndexToWordIndex(begin_bit_idx);
uintptr_t* end_bm_address = Bitmap::Begin() + Bitmap::BitIndexToWordIndex(end_bit_idx);
ptrdiff_t diff = end_bm_address - begin_bm_address;
uintptr_t mask = Bitmap::BitIndexToMask(begin_bit_idx);
// Bits that needs to be set in the first word, if it's not also the last word
mask = ~(mask - 1);
if (diff > 0) {
*begin_bm_address |= mask;
mask = ~0;
// Even though memset can handle the (diff == 1) case but we should avoid the
// overhead of a function call for this, highly likely (as most of the objects
// are small), case.
if (diff > 1) {
// Set all intermediate bits to 1.
std::memset(static_cast<void*>(begin_bm_address + 1), 0xff, (diff - 1) * sizeof(uintptr_t));
}
}
uintptr_t end_mask = Bitmap::BitIndexToMask(end_bit_idx);
*end_bm_address |= mask & (end_mask | (end_mask - 1));
return begin_bit_idx;
}
template <size_t kAlignment> template <typename Visitor>
inline void MarkCompact::LiveWordsBitmap<kAlignment>::VisitLiveStrides(uintptr_t begin_bit_idx,
uint8_t* end,
const size_t bytes,
Visitor&& visitor) const {
// Range to visit [begin_bit_idx, end_bit_idx]
DCHECK(IsAligned<kAlignment>(end));
end -= kAlignment;
const uintptr_t end_bit_idx = MemRangeBitmap::BitIndexFromAddr(reinterpret_cast<uintptr_t>(end));
DCHECK_LE(begin_bit_idx, end_bit_idx);
uintptr_t begin_word_idx = Bitmap::BitIndexToWordIndex(begin_bit_idx);
const uintptr_t end_word_idx = Bitmap::BitIndexToWordIndex(end_bit_idx);
DCHECK(Bitmap::TestBit(begin_bit_idx));
size_t stride_size = 0;
size_t idx_in_word = 0;
size_t num_heap_words = bytes / kAlignment;
uintptr_t live_stride_start_idx;
uintptr_t word = Bitmap::Begin()[begin_word_idx];
// Setup the first word.
word &= ~(Bitmap::BitIndexToMask(begin_bit_idx) - 1);
begin_bit_idx = RoundDown(begin_bit_idx, Bitmap::kBitsPerBitmapWord);
do {
if (UNLIKELY(begin_word_idx == end_word_idx)) {
uintptr_t mask = Bitmap::BitIndexToMask(end_bit_idx);
word &= mask | (mask - 1);
}
if (~word == 0) {
// All bits in the word are marked.
if (stride_size == 0) {
live_stride_start_idx = begin_bit_idx;
}
stride_size += Bitmap::kBitsPerBitmapWord;
if (num_heap_words <= stride_size) {
break;
}
} else {
while (word != 0) {
// discard 0s
size_t shift = CTZ(word);
idx_in_word += shift;
word >>= shift;
if (stride_size > 0) {
if (shift > 0) {
if (num_heap_words <= stride_size) {
break;
}
visitor(live_stride_start_idx, stride_size, /*is_last*/ false);
num_heap_words -= stride_size;
live_stride_start_idx = begin_bit_idx + idx_in_word;
stride_size = 0;
}
} else {
live_stride_start_idx = begin_bit_idx + idx_in_word;
}
// consume 1s
shift = CTZ(~word);
DCHECK_NE(shift, 0u);
word >>= shift;
idx_in_word += shift;
stride_size += shift;
}
// If the whole word == 0 or the higher bits are 0s, then we exit out of
// the above loop without completely consuming the word, so call visitor,
// if needed.
if (idx_in_word < Bitmap::kBitsPerBitmapWord && stride_size > 0) {
if (num_heap_words <= stride_size) {
break;
}
visitor(live_stride_start_idx, stride_size, /*is_last*/ false);
num_heap_words -= stride_size;
stride_size = 0;
}
idx_in_word = 0;
}
begin_bit_idx += Bitmap::kBitsPerBitmapWord;
begin_word_idx++;
if (UNLIKELY(begin_word_idx > end_word_idx)) {
num_heap_words = std::min(stride_size, num_heap_words);
break;
}
word = Bitmap::Begin()[begin_word_idx];
} while (true);
if (stride_size > 0) {
visitor(live_stride_start_idx, num_heap_words, /*is_last*/ true);
}
}
template <size_t kAlignment>
inline
uint32_t MarkCompact::LiveWordsBitmap<kAlignment>::FindNthLiveWordOffset(size_t chunk_idx,
uint32_t n) const {
DCHECK_LT(n, kBitsPerVectorWord);
const size_t index = chunk_idx * kBitmapWordsPerVectorWord;
for (uint32_t i = 0; i < kBitmapWordsPerVectorWord; i++) {
uintptr_t word = Bitmap::Begin()[index + i];
if (~word == 0) {
if (n < Bitmap::kBitsPerBitmapWord) {
return i * Bitmap::kBitsPerBitmapWord + n;
}
n -= Bitmap::kBitsPerBitmapWord;
} else {
uint32_t j = 0;
while (word != 0) {
// count contiguous 0s
uint32_t shift = CTZ(word);
word >>= shift;
j += shift;
// count contiguous 1s
shift = CTZ(~word);
DCHECK_NE(shift, 0u);
if (shift > n) {
return i * Bitmap::kBitsPerBitmapWord + j + n;
}
n -= shift;
word >>= shift;
j += shift;
}
}
}
UNREACHABLE();
}
inline void MarkCompact::UpdateRef(mirror::Object* obj,
MemberOffset offset,
uint8_t* begin,
uint8_t* end) {
mirror::Object* old_ref = obj->GetFieldObject<
mirror::Object, kVerifyNone, kWithoutReadBarrier, /*kIsVolatile*/false>(offset);
if (kIsDebugBuild) {
if (HasAddress(old_ref) &&
reinterpret_cast<uint8_t*>(old_ref) < black_allocations_begin_ &&
!moving_space_bitmap_->Test(old_ref)) {
mirror::Object* from_ref = GetFromSpaceAddr(old_ref);
std::ostringstream oss;
heap_->DumpSpaces(oss);
MemMap::DumpMaps(oss, /* terse= */ true);
LOG(FATAL) << "Not marked in the bitmap ref=" << old_ref
<< " from_ref=" << from_ref
<< " offset=" << offset
<< " obj=" << obj
<< " obj-validity=" << IsValidObject(obj)
<< " from-space=" << static_cast<void*>(from_space_begin_)
<< " bitmap= " << moving_space_bitmap_->DumpMemAround(old_ref)
<< " from_ref "
<< heap_->GetVerification()->DumpRAMAroundAddress(
reinterpret_cast<uintptr_t>(from_ref), 128)
<< " obj "
<< heap_->GetVerification()->DumpRAMAroundAddress(
reinterpret_cast<uintptr_t>(obj), 128)
<< " old_ref " << heap_->GetVerification()->DumpRAMAroundAddress(
reinterpret_cast<uintptr_t>(old_ref), 128)
<< " maps\n" << oss.str();
}
}
mirror::Object* new_ref = PostCompactAddress(old_ref, begin, end);
if (new_ref != old_ref) {
obj->SetFieldObjectWithoutWriteBarrier<
/*kTransactionActive*/false, /*kCheckTransaction*/false, kVerifyNone, /*kIsVolatile*/false>(
offset,
new_ref);
}
}
inline bool MarkCompact::VerifyRootSingleUpdate(void* root,
mirror::Object* old_ref,
const RootInfo& info) {
// ASAN promotes stack-frames to heap in order to detect
// stack-use-after-return issues. So skip using this double-root update
// detection on ASAN as well.
if (kIsDebugBuild && !kMemoryToolIsAvailable) {
void* stack_low_addr = stack_low_addr_;
void* stack_high_addr = stack_high_addr_;
if (!HasAddress(old_ref)) {
return false;
}
Thread* self = Thread::Current();
if (UNLIKELY(stack_low_addr == nullptr)) {
stack_low_addr = self->GetStackEnd();
stack_high_addr = reinterpret_cast<char*>(stack_low_addr) + self->GetStackSize();
}
if (root < stack_low_addr || root > stack_high_addr) {
MutexLock mu(self, lock_);
auto ret = updated_roots_->insert(root);
DCHECK(ret.second) << "root=" << root << " old_ref=" << old_ref
<< " stack_low_addr=" << stack_low_addr
<< " stack_high_addr=" << stack_high_addr;
}
DCHECK(reinterpret_cast<uint8_t*>(old_ref) >= black_allocations_begin_ ||
live_words_bitmap_->Test(old_ref))
<< "ref=" << old_ref << " <" << mirror::Object::PrettyTypeOf(old_ref) << "> RootInfo ["
<< info << "]";
}
return true;
}
inline void MarkCompact::UpdateRoot(mirror::CompressedReference<mirror::Object>* root,
uint8_t* begin,
uint8_t* end,
const RootInfo& info) {
DCHECK(!root->IsNull());
mirror::Object* old_ref = root->AsMirrorPtr();
if (VerifyRootSingleUpdate(root, old_ref, info)) {
mirror::Object* new_ref = PostCompactAddress(old_ref, begin, end);
if (old_ref != new_ref) {
root->Assign(new_ref);
}
}
}
inline void MarkCompact::UpdateRoot(mirror::Object** root,
uint8_t* begin,
uint8_t* end,
const RootInfo& info) {
mirror::Object* old_ref = *root;
if (VerifyRootSingleUpdate(root, old_ref, info)) {
mirror::Object* new_ref = PostCompactAddress(old_ref, begin, end);
if (old_ref != new_ref) {
*root = new_ref;
}
}
}
template <size_t kAlignment>
inline size_t MarkCompact::LiveWordsBitmap<kAlignment>::CountLiveWordsUpto(size_t bit_idx) const {
const size_t word_offset = Bitmap::BitIndexToWordIndex(bit_idx);
uintptr_t word;
size_t ret = 0;
// This is needed only if we decide to make chunks 128-bit but still
// choose to use 64-bit word for bitmap. Ideally we should use 128-bit
// SIMD instructions to compute popcount.
if (kBitmapWordsPerVectorWord > 1) {
for (size_t i = RoundDown(word_offset, kBitmapWordsPerVectorWord); i < word_offset; i++) {
word = Bitmap::Begin()[i];
ret += POPCOUNT(word);
}
}
word = Bitmap::Begin()[word_offset];
const uintptr_t mask = Bitmap::BitIndexToMask(bit_idx);
DCHECK_NE(word & mask, 0u)
<< " word_offset:" << word_offset
<< " bit_idx:" << bit_idx
<< " bit_idx_in_word:" << (bit_idx % Bitmap::kBitsPerBitmapWord)
<< std::hex << " word: 0x" << word
<< " mask: 0x" << mask << std::dec;
ret += POPCOUNT(word & (mask - 1));
return ret;
}
inline mirror::Object* MarkCompact::PostCompactBlackObjAddr(mirror::Object* old_ref) const {
return reinterpret_cast<mirror::Object*>(reinterpret_cast<uint8_t*>(old_ref)
- black_objs_slide_diff_);
}
inline mirror::Object* MarkCompact::PostCompactOldObjAddr(mirror::Object* old_ref) const {
const uintptr_t begin = live_words_bitmap_->Begin();
const uintptr_t addr_offset = reinterpret_cast<uintptr_t>(old_ref) - begin;
const size_t vec_idx = addr_offset / kOffsetChunkSize;
const size_t live_bytes_in_bitmap_word =
live_words_bitmap_->CountLiveWordsUpto(addr_offset / kAlignment) * kAlignment;
return reinterpret_cast<mirror::Object*>(begin
+ chunk_info_vec_[vec_idx]
+ live_bytes_in_bitmap_word);
}
inline mirror::Object* MarkCompact::PostCompactAddressUnchecked(mirror::Object* old_ref) const {
if (reinterpret_cast<uint8_t*>(old_ref) >= black_allocations_begin_) {
return PostCompactBlackObjAddr(old_ref);
}
if (kIsDebugBuild) {
mirror::Object* from_ref = GetFromSpaceAddr(old_ref);
DCHECK(live_words_bitmap_->Test(old_ref))
<< "ref=" << old_ref;
if (!moving_space_bitmap_->Test(old_ref)) {
std::ostringstream oss;
Runtime::Current()->GetHeap()->DumpSpaces(oss);
MemMap::DumpMaps(oss, /* terse= */ true);
LOG(FATAL) << "ref=" << old_ref
<< " from_ref=" << from_ref
<< " from-space=" << static_cast<void*>(from_space_begin_)
<< " bitmap= " << moving_space_bitmap_->DumpMemAround(old_ref)
<< heap_->GetVerification()->DumpRAMAroundAddress(
reinterpret_cast<uintptr_t>(from_ref), 128)
<< " maps\n" << oss.str();
}
}
return PostCompactOldObjAddr(old_ref);
}
inline mirror::Object* MarkCompact::PostCompactAddress(mirror::Object* old_ref,
uint8_t* begin,
uint8_t* end) const {
if (LIKELY(HasAddress(old_ref, begin, end))) {
return PostCompactAddressUnchecked(old_ref);
}
return old_ref;
}
} // namespace collector
} // namespace gc
} // namespace art
#endif // ART_RUNTIME_GC_COLLECTOR_MARK_COMPACT_INL_H_