Reviewers: jarin,
Description:
Make prev and next pointer in pages list AtomicWords and access them using
acquire/release semantics.
BUG=
Please review this at https://codereview.chromium.org/150413009/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+27, -24 lines):
M src/spaces.h
M src/spaces.cc
Index: src/spaces.cc
diff --git a/src/spaces.cc b/src/spaces.cc
index
a80341bd7fc6baa7750e76c89528ba6cbbeb29fe..08b8531deb5fbd8c3183c25f170697e57bd7cace
100644
--- a/src/spaces.cc
+++ b/src/spaces.cc
@@ -560,21 +560,12 @@ bool MemoryChunk::CommitArea(size_t requested) {
void MemoryChunk::InsertAfter(MemoryChunk* other) {
- next_chunk_ = other->next_chunk_;
- prev_chunk_ = other;
+ MemoryChunk* other_next = other->next_chunk();
- // This memory barrier is needed since concurrent sweeper threads may
iterate
- // over the list of pages while a new page is inserted.
- // TODO(hpayer): find a cleaner way to guarantee that the page list can
be
- // expanded concurrently
- MemoryBarrier();
-
- // The following two write operations can take effect in arbitrary order
- // since pages are always iterated by the sweeper threads in LIFO order,
i.e,
- // the inserted page becomes visible for the sweeper threads after
- // other->next_chunk_ = this;
- other->next_chunk_->prev_chunk_ = this;
- other->next_chunk_ = this;
+ set_next_chunk(other_next);
+ set_prev_chunk(other);
+ other_next->set_prev_chunk(this);
+ other->set_next_chunk(this);
}
@@ -583,10 +574,12 @@ void MemoryChunk::Unlink() {
heap_->decrement_scan_on_scavenge_pages();
ClearFlag(SCAN_ON_SCAVENGE);
}
- next_chunk_->prev_chunk_ = prev_chunk_;
- prev_chunk_->next_chunk_ = next_chunk_;
- prev_chunk_ = NULL;
- next_chunk_ = NULL;
+ MemoryChunk* next_element = next_chunk();
+ MemoryChunk* prev_element = prev_chunk();
+ next_element->set_prev_chunk(prev_element);
+ prev_element->set_next_chunk(next_element);
+ set_prev_chunk(NULL);
+ set_next_chunk(NULL);
}
Index: src/spaces.h
diff --git a/src/spaces.h b/src/spaces.h
index
9d47f81ac63dbbf65d357769c02f6307bf6ff15f..99ea080fc4dd73b52c1b63af776ea4d4a5dad339
100644
--- a/src/spaces.h
+++ b/src/spaces.h
@@ -313,11 +313,21 @@ class MemoryChunk {
bool is_valid() { return address() != NULL; }
- MemoryChunk* next_chunk() const { return next_chunk_; }
- MemoryChunk* prev_chunk() const { return prev_chunk_; }
+ MemoryChunk* next_chunk() const {
+ return reinterpret_cast<MemoryChunk*>(Acquire_Load(&next_chunk_));
+ }
+
+ MemoryChunk* prev_chunk() const {
+ return reinterpret_cast<MemoryChunk*>(Acquire_Load(&prev_chunk_));
+ }
- void set_next_chunk(MemoryChunk* next) { next_chunk_ = next; }
- void set_prev_chunk(MemoryChunk* prev) { prev_chunk_ = prev; }
+ void set_next_chunk(MemoryChunk* next) {
+ Release_Store(&next_chunk_, reinterpret_cast<AtomicWord>(next));
+ }
+
+ void set_prev_chunk(MemoryChunk* prev) {
+ Release_Store(&prev_chunk_, reinterpret_cast<AtomicWord>(prev));
+ }
Space* owner() const {
if ((reinterpret_cast<intptr_t>(owner_) & kFailureTagMask) ==
@@ -671,8 +681,8 @@ class MemoryChunk {
static inline void UpdateHighWaterMark(Address mark);
protected:
- MemoryChunk* next_chunk_;
- MemoryChunk* prev_chunk_;
+ AtomicWord next_chunk_;
+ AtomicWord prev_chunk_;
size_t size_;
intptr_t flags_;
--
--
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