Add GcRoot to clean up and enforce read barriers.
Introduce a value-type wrapper around Object* for GC roots so that 1)
we won't have to directly add the read barrier code in many places and
2) we can avoid accidentally bypassing/missing read barriers on GC
roots (the GcRoot interface ensures that the read barrier is executed
on a read).
The jdwp test passed.
Bug: 12687968
Change-Id: Ib167c7c325b3c7e3900133578815f04d219972a1
diff --git a/runtime/indirect_reference_table.cc b/runtime/indirect_reference_table.cc
index 26ddba2..9b2b82e 100644
--- a/runtime/indirect_reference_table.cc
+++ b/runtime/indirect_reference_table.cc
@@ -76,7 +76,7 @@
CHECK(table_mem_map_.get() != nullptr) << error_str;
CHECK_EQ(table_mem_map_->Size(), table_bytes);
- table_ = reinterpret_cast<mirror::Object**>(table_mem_map_->Begin());
+ table_ = reinterpret_cast<GcRoot<mirror::Object>*>(table_mem_map_->Begin());
CHECK(table_ != nullptr);
memset(table_, 0xd1, initial_bytes);
@@ -132,20 +132,22 @@
if (numHoles > 0) {
DCHECK_GT(topIndex, 1U);
// Find the first hole; likely to be near the end of the list.
- mirror::Object** pScan = &table_[topIndex - 1];
- DCHECK(*pScan != NULL);
- while (*--pScan != NULL) {
+ GcRoot<mirror::Object>* pScan = &table_[topIndex - 1];
+ DCHECK(!pScan->IsNull());
+ --pScan;
+ while (!pScan->IsNull()) {
DCHECK_GE(pScan, table_ + prevState.parts.topIndex);
+ --pScan;
}
UpdateSlotAdd(obj, pScan - table_);
result = ToIndirectRef(pScan - table_);
- *pScan = obj;
+ *pScan = GcRoot<mirror::Object>(obj);
segment_state_.parts.numHoles--;
} else {
// Add to the end.
UpdateSlotAdd(obj, topIndex);
result = ToIndirectRef(topIndex);
- table_[topIndex++] = obj;
+ table_[topIndex++] = GcRoot<mirror::Object>(obj);
segment_state_.parts.topIndex = topIndex;
}
if (false) {
@@ -211,15 +213,16 @@
return false;
}
- table_[idx] = NULL;
+ table_[idx] = GcRoot<mirror::Object>(nullptr);
int numHoles = segment_state_.parts.numHoles - prevState.parts.numHoles;
if (numHoles != 0) {
while (--topIndex > bottomIndex && numHoles != 0) {
if (false) {
LOG(INFO) << "+++ checking for hole at " << topIndex-1
- << " (cookie=" << cookie << ") val=" << table_[topIndex - 1];
+ << " (cookie=" << cookie << ") val="
+ << table_[topIndex - 1].Read<kWithoutReadBarrier>();
}
- if (table_[topIndex-1] != NULL) {
+ if (!table_[topIndex-1].IsNull()) {
break;
}
if (false) {
@@ -239,7 +242,7 @@
// Not the top-most entry. This creates a hole. We NULL out the
// entry to prevent somebody from deleting it twice and screwing up
// the hole count.
- if (table_[idx] == NULL) {
+ if (table_[idx].IsNull()) {
LOG(INFO) << "--- WEIRD: removing null entry " << idx;
return false;
}
@@ -247,7 +250,7 @@
return false;
}
- table_[idx] = NULL;
+ table_[idx] = GcRoot<mirror::Object>(nullptr);
segment_state_.parts.numHoles++;
if (false) {
LOG(INFO) << "+++ left hole at " << idx << ", holes=" << segment_state_.parts.numHoles;
@@ -269,17 +272,16 @@
os << kind_ << " table dump:\n";
ReferenceTable::Table entries;
for (size_t i = 0; i < Capacity(); ++i) {
- mirror::Object** root = &table_[i];
- mirror::Object* obj = *root;
+ mirror::Object* obj = table_[i].Read<kWithoutReadBarrier>();
if (UNLIKELY(obj == nullptr)) {
// Remove NULLs.
} else if (UNLIKELY(obj == kClearedJniWeakGlobal)) {
// ReferenceTable::Dump() will handle kClearedJniWeakGlobal
// while the read barrier won't.
- entries.push_back(obj);
+ entries.push_back(GcRoot<mirror::Object>(obj));
} else {
- obj = ReadBarrier::BarrierForRoot<mirror::Object, kWithReadBarrier>(root);
- entries.push_back(obj);
+ obj = table_[i].Read();
+ entries.push_back(GcRoot<mirror::Object>(obj));
}
}
ReferenceTable::Dump(os, entries);