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/*
* Copyright (C) 2008 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_ACCOUNTING_SPACE_BITMAP_INL_H_
#define ART_RUNTIME_GC_ACCOUNTING_SPACE_BITMAP_INL_H_
#include "space_bitmap.h"
#include <memory>
#include <android-base/logging.h>
#include "base/atomic.h"
#include "base/bit_utils.h"
namespace art {
namespace gc {
namespace accounting {
template<size_t kAlignment>
inline bool SpaceBitmap<kAlignment>::AtomicTestAndSet(const mirror::Object* obj) {
uintptr_t addr = reinterpret_cast<uintptr_t>(obj);
DCHECK_GE(addr, heap_begin_);
const uintptr_t offset = addr - heap_begin_;
const size_t index = OffsetToIndex(offset);
const uintptr_t mask = OffsetToMask(offset);
Atomic<uintptr_t>* atomic_entry = &bitmap_begin_[index];
DCHECK_LT(index, bitmap_size_ / sizeof(intptr_t)) << " bitmap_size_ = " << bitmap_size_;
uintptr_t old_word;
do {
old_word = atomic_entry->load(std::memory_order_relaxed);
// Fast path: The bit is already set.
if ((old_word & mask) != 0) {
DCHECK(Test(obj));
return true;
}
} while (!atomic_entry->CompareAndSetWeakRelaxed(old_word, old_word | mask));
DCHECK(Test(obj));
return false;
}
template<size_t kAlignment>
inline bool SpaceBitmap<kAlignment>::Test(const mirror::Object* obj) const {
uintptr_t addr = reinterpret_cast<uintptr_t>(obj);
DCHECK(HasAddress(obj)) << obj;
DCHECK(bitmap_begin_ != nullptr);
DCHECK_GE(addr, heap_begin_);
const uintptr_t offset = addr - heap_begin_;
size_t index = OffsetToIndex(offset);
return (bitmap_begin_[index].load(std::memory_order_relaxed) & OffsetToMask(offset)) != 0;
}
template<size_t kAlignment>
template<typename Visitor>
inline void SpaceBitmap<kAlignment>::VisitMarkedRange(uintptr_t visit_begin,
uintptr_t visit_end,
Visitor&& visitor) const {
DCHECK_LE(visit_begin, visit_end);
#if 0
for (uintptr_t i = visit_begin; i < visit_end; i += kAlignment) {
mirror::Object* obj = reinterpret_cast<mirror::Object*>(i);
if (Test(obj)) {
visitor(obj);
}
}
#else
DCHECK_LE(heap_begin_, visit_begin);
DCHECK_LE(visit_end, HeapLimit());
const uintptr_t offset_start = visit_begin - heap_begin_;
const uintptr_t offset_end = visit_end - heap_begin_;
const uintptr_t index_start = OffsetToIndex(offset_start);
const uintptr_t index_end = OffsetToIndex(offset_end);
const size_t bit_start = (offset_start / kAlignment) % kBitsPerIntPtrT;
const size_t bit_end = (offset_end / kAlignment) % kBitsPerIntPtrT;
// Index(begin) ... Index(end)
// [xxxxx???][........][????yyyy]
// ^ ^
// | #---- Bit of visit_end
// #---- Bit of visit_begin
//
// Left edge.
uintptr_t left_edge = bitmap_begin_[index_start];
// Mark of lower bits that are not in range.
left_edge &= ~((static_cast<uintptr_t>(1) << bit_start) - 1);
// Right edge. Either unique, or left_edge.
uintptr_t right_edge;
if (index_start < index_end) {
// Left edge != right edge.
// Traverse left edge.
if (left_edge != 0) {
const uintptr_t ptr_base = IndexToOffset(index_start) + heap_begin_;
do {
const size_t shift = CTZ(left_edge);
mirror::Object* obj = reinterpret_cast<mirror::Object*>(ptr_base + shift * kAlignment);
visitor(obj);
left_edge ^= (static_cast<uintptr_t>(1)) << shift;
} while (left_edge != 0);
}
// Traverse the middle, full part.
for (size_t i = index_start + 1; i < index_end; ++i) {
uintptr_t w = bitmap_begin_[i].load(std::memory_order_relaxed);
if (w != 0) {
const uintptr_t ptr_base = IndexToOffset(i) + heap_begin_;
// Iterate on the bits set in word `w`, from the least to the most significant bit.
do {
const size_t shift = CTZ(w);
mirror::Object* obj = reinterpret_cast<mirror::Object*>(ptr_base + shift * kAlignment);
visitor(obj);
w ^= (static_cast<uintptr_t>(1)) << shift;
} while (w != 0);
}
}
// Right edge is unique.
// But maybe we don't have anything to do: visit_end starts in a new word...
if (bit_end == 0) {
// Do not read memory, as it could be after the end of the bitmap.
right_edge = 0;
} else {
right_edge = bitmap_begin_[index_end];
}
} else {
// Right edge = left edge.
right_edge = left_edge;
}
// Right edge handling.
right_edge &= ((static_cast<uintptr_t>(1) << bit_end) - 1);
if (right_edge != 0) {
const uintptr_t ptr_base = IndexToOffset(index_end) + heap_begin_;
// Iterate on the bits set in word `right_edge`, from the least to the most significant bit.
do {
const size_t shift = CTZ(right_edge);
mirror::Object* obj = reinterpret_cast<mirror::Object*>(ptr_base + shift * kAlignment);
visitor(obj);
right_edge ^= (static_cast<uintptr_t>(1)) << shift;
} while (right_edge != 0);
}
#endif
}
template<size_t kAlignment>
template<typename Visitor>
void SpaceBitmap<kAlignment>::Walk(Visitor&& visitor) {
CHECK(bitmap_begin_ != nullptr);
uintptr_t end = OffsetToIndex(HeapLimit() - heap_begin_ - 1);
Atomic<uintptr_t>* bitmap_begin = bitmap_begin_;
for (uintptr_t i = 0; i <= end; ++i) {
uintptr_t w = bitmap_begin[i].load(std::memory_order_relaxed);
if (w != 0) {
uintptr_t ptr_base = IndexToOffset(i) + heap_begin_;
do {
const size_t shift = CTZ(w);
mirror::Object* obj = reinterpret_cast<mirror::Object*>(ptr_base + shift * kAlignment);
visitor(obj);
w ^= (static_cast<uintptr_t>(1)) << shift;
} while (w != 0);
}
}
}
template<size_t kAlignment>
template<bool kSetBit>
inline bool SpaceBitmap<kAlignment>::Modify(const mirror::Object* obj) {
uintptr_t addr = reinterpret_cast<uintptr_t>(obj);
DCHECK_GE(addr, heap_begin_);
DCHECK(HasAddress(obj)) << obj;
const uintptr_t offset = addr - heap_begin_;
const size_t index = OffsetToIndex(offset);
const uintptr_t mask = OffsetToMask(offset);
DCHECK_LT(index, bitmap_size_ / sizeof(intptr_t)) << " bitmap_size_ = " << bitmap_size_;
Atomic<uintptr_t>* atomic_entry = &bitmap_begin_[index];
uintptr_t old_word = atomic_entry->load(std::memory_order_relaxed);
if (kSetBit) {
// Check the bit before setting the word incase we are trying to mark a read only bitmap
// like an image space bitmap. This bitmap is mapped as read only and will fault if we
// attempt to change any words. Since all of the objects are marked, this will never
// occur if we check before setting the bit. This also prevents dirty pages that would
// occur if the bitmap was read write and we did not check the bit.
if ((old_word & mask) == 0) {
atomic_entry->store(old_word | mask, std::memory_order_relaxed);
}
} else {
atomic_entry->store(old_word & ~mask, std::memory_order_relaxed);
}
DCHECK_EQ(Test(obj), kSetBit);
return (old_word & mask) != 0;
}
template<size_t kAlignment>
inline std::ostream& operator << (std::ostream& stream, const SpaceBitmap<kAlignment>& bitmap) {
return stream
<< bitmap.GetName() << "["
<< "begin=" << reinterpret_cast<const void*>(bitmap.HeapBegin())
<< ",end=" << reinterpret_cast<const void*>(bitmap.HeapLimit())
<< "]";
}
} // namespace accounting
} // namespace gc
} // namespace art
#endif // ART_RUNTIME_GC_ACCOUNTING_SPACE_BITMAP_INL_H_
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