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/*
* Copyright (C) 2015 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_BITMAP_INL_H_
#define ART_RUNTIME_GC_ACCOUNTING_BITMAP_INL_H_
#include "bitmap.h"
#include <memory>
#include "atomic.h"
#include "base/bit_utils.h"
#include "base/logging.h"
namespace art {
namespace gc {
namespace accounting {
inline bool Bitmap::AtomicTestAndSetBit(uintptr_t bit_index) {
CheckValidBitIndex(bit_index);
const size_t word_index = BitIndexToWordIndex(bit_index);
const uintptr_t word_mask = BitIndexToMask(bit_index);
auto* atomic_entry = reinterpret_cast<Atomic<uintptr_t>*>(&bitmap_begin_[word_index]);
uintptr_t old_word;
do {
old_word = atomic_entry->LoadRelaxed();
// Fast path: The bit is already set.
if ((old_word & word_mask) != 0) {
DCHECK(TestBit(bit_index));
return true;
}
} while (!atomic_entry->CompareExchangeWeakSequentiallyConsistent(old_word,
old_word | word_mask));
DCHECK(TestBit(bit_index));
return false;
}
inline bool Bitmap::TestBit(uintptr_t bit_index) const {
CheckValidBitIndex(bit_index);
return (bitmap_begin_[BitIndexToWordIndex(bit_index)] & BitIndexToMask(bit_index)) != 0;
}
template<typename Visitor>
inline void Bitmap::VisitSetBits(uintptr_t bit_start, uintptr_t bit_end, const Visitor& visitor)
const {
DCHECK_LE(bit_start, bit_end);
CheckValidBitIndex(bit_start);
const uintptr_t index_start = BitIndexToWordIndex(bit_start);
const uintptr_t index_end = BitIndexToWordIndex(bit_end);
if (bit_start != bit_end) {
CheckValidBitIndex(bit_end - 1);
}
// Index(begin) ... Index(end)
// [xxxxx???][........][????yyyy]
// ^ ^
// | #---- Bit of visit_end
// #---- Bit of visit_begin
//
// Left edge.
uintptr_t left_edge = bitmap_begin_[index_start];
// Clear the lower bits that are not in range.
left_edge &= ~((static_cast<uintptr_t>(1) << (bit_start % kBitsPerBitmapWord)) - 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 = WordIndexToBitIndex(index_start);
do {
const size_t shift = CTZ(left_edge);
visitor(ptr_base + shift);
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];
if (w != 0) {
const uintptr_t ptr_base = WordIndexToBitIndex(i);
do {
const size_t shift = CTZ(w);
visitor(ptr_base + shift);
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 handling.
right_edge &= ((static_cast<uintptr_t>(1) << (bit_end % kBitsPerBitmapWord)) - 1);
if (right_edge != 0) {
const uintptr_t ptr_base = WordIndexToBitIndex(index_end);
do {
const size_t shift = CTZ(right_edge);
visitor(ptr_base + shift);
right_edge ^= (static_cast<uintptr_t>(1)) << shift;
} while (right_edge != 0);
}
}
template<bool kSetBit>
inline bool Bitmap::ModifyBit(uintptr_t bit_index) {
CheckValidBitIndex(bit_index);
const size_t word_index = BitIndexToWordIndex(bit_index);
const uintptr_t word_mask = BitIndexToMask(bit_index);
uintptr_t* address = &bitmap_begin_[word_index];
uintptr_t old_word = *address;
if (kSetBit) {
*address = old_word | word_mask;
} else {
*address = old_word & ~word_mask;
}
DCHECK_EQ(TestBit(bit_index), kSetBit);
return (old_word & word_mask) != 0;
}
} // namespace accounting
} // namespace gc
} // namespace art
#endif // ART_RUNTIME_GC_ACCOUNTING_BITMAP_INL_H_
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