dart-sdk/runtime/vm/bit_vector.cc
Samir Jindel 4c6a2ab47c Re-land "[vm] Aggressive write-barrier elimination."
Three bugs were fixed:

1. BitVector::Equals was not fully fixed by the original CL.
2. We need to add old objects to the deferred marking queue during
   RememberLiveTemporaries().
3. The thread being scanned in RestoreWriteBarrierInvariant may not
   be scheduled, so we cannot use its store buffer block.

In addition, this changed uncovered another bug fixed in:
https://dart-review.googlesource.com/c/sdk/+/138960.

Original CL is in patchset 3.

This reverts commit 30a12a349e.

Change-Id: I36169b09563998ed5b3c3eac70ee0ebe78853e62
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/138920
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Samir Jindel <sjindel@google.com>
2020-03-11 13:05:59 +00:00

118 lines
3 KiB
C++

// Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/bit_vector.h"
#include "vm/log.h"
#include "vm/os.h"
namespace dart {
void BitVector::Iterator::Advance() {
++bit_index_;
// Skip zero words.
if (current_word_ == 0) {
do {
++word_index_;
if (Done()) return;
current_word_ = target_->data_[word_index_];
} while (current_word_ == 0);
bit_index_ = word_index_ * kBitsPerWord;
}
// Skip zero bytes.
while ((current_word_ & 0xff) == 0) {
current_word_ >>= 8;
bit_index_ += 8;
}
// Skip zero bits.
while ((current_word_ & 0x1) == 0) {
current_word_ >>= 1;
++bit_index_;
}
current_word_ = current_word_ >> 1;
}
bool BitVector::Equals(const BitVector& other) const {
if (length_ != other.length_) return false;
intptr_t i = 0;
for (; i < data_length_ - 1; i++) {
if (data_[i] != other.data_[i]) return false;
}
if (i < data_length_) {
if (length_ % kBitsPerWord == 0) return data_[i] == other.data_[i];
// Don't compare bits beyond length_.
const intptr_t shift_size = kBitsPerWord - (length_ % kBitsPerWord);
const uword mask = static_cast<uword>(-1) >> shift_size;
if ((data_[i] & mask) != (other.data_[i] & mask)) return false;
}
return true;
}
bool BitVector::AddAll(const BitVector* from) {
ASSERT(data_length_ == from->data_length_);
bool changed = false;
for (intptr_t i = 0; i < data_length_; i++) {
const uword before = data_[i];
const uword after = data_[i] | from->data_[i];
if (before != after) {
changed = true;
data_[i] = after;
}
}
return changed;
}
bool BitVector::RemoveAll(const BitVector* from) {
ASSERT(data_length_ == from->data_length_);
bool changed = false;
for (intptr_t i = 0; i < data_length_; i++) {
const uword before = data_[i];
const uword after = data_[i] & ~from->data_[i];
if (before != after) {
changed = true;
data_[i] = after;
}
}
return changed;
}
bool BitVector::KillAndAdd(BitVector* kill, BitVector* gen) {
ASSERT(data_length_ == kill->data_length_);
ASSERT(data_length_ == gen->data_length_);
bool changed = false;
for (intptr_t i = 0; i < data_length_; i++) {
const uword before = data_[i];
const uword after = data_[i] | (gen->data_[i] & ~kill->data_[i]);
if (before != after) changed = true;
data_[i] = after;
}
return changed;
}
void BitVector::Intersect(const BitVector* other) {
ASSERT(other->length() == length());
for (intptr_t i = 0; i < data_length_; i++) {
data_[i] = data_[i] & other->data_[i];
}
}
bool BitVector::IsEmpty() const {
for (intptr_t i = 0; i < data_length_; i++) {
if (data_[i] != 0) {
return false;
}
}
return true;
}
void BitVector::Print() const {
THR_Print("[");
for (intptr_t i = 0; i < length_; i++) {
THR_Print(Contains(i) ? "1" : "0");
}
THR_Print("]");
}
} // namespace dart