Remove dead blocks for the blocks_ array.
This prevents crashing because of structurally incorrect
blocks. Also we now don't need to remove its instructions.
Test case courtesy of Serguei I Katkov.
Change-Id: Ia3ef9580549fc3546e8cd5f346079b1f0ceb2a61
diff --git a/compiler/optimizing/dominator_test.cc b/compiler/optimizing/dominator_test.cc
index 7623e42..61a7697 100644
--- a/compiler/optimizing/dominator_test.cc
+++ b/compiler/optimizing/dominator_test.cc
@@ -36,7 +36,13 @@
ASSERT_EQ(graph->GetBlocks().Size(), blocks_length);
for (size_t i = 0, e = blocks_length; i < e; ++i) {
if (blocks[i] == -1) {
- ASSERT_EQ(nullptr, graph->GetBlocks().Get(i)->GetDominator());
+ if (graph->GetBlocks().Get(i) == nullptr) {
+ // Dead block.
+ } else {
+ // Only the entry block has no dominator.
+ ASSERT_EQ(nullptr, graph->GetBlocks().Get(i)->GetDominator());
+ ASSERT_TRUE(graph->GetBlocks().Get(i)->IsEntryBlock());
+ }
} else {
ASSERT_NE(nullptr, graph->GetBlocks().Get(i)->GetDominator());
ASSERT_EQ(blocks[i], graph->GetBlocks().Get(i)->GetDominator()->GetBlockId());
diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index d8a8554..ada3487 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -51,9 +51,7 @@
for (size_t i = 0; i < blocks_.Size(); ++i) {
if (!visited.IsBitSet(i)) {
HBasicBlock* block = blocks_.Get(i);
- for (HInstructionIterator it(block->GetPhis()); !it.Done(); it.Advance()) {
- RemoveAsUser(it.Current());
- }
+ DCHECK(block->GetPhis().IsEmpty()) << "Phis are not inserted at this stage";
for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
RemoveAsUser(it.Current());
}
@@ -61,19 +59,17 @@
}
}
-void HGraph::RemoveDeadBlocks(const ArenaBitVector& visited) const {
+void HGraph::RemoveDeadBlocks(const ArenaBitVector& visited) {
for (size_t i = 0; i < blocks_.Size(); ++i) {
if (!visited.IsBitSet(i)) {
HBasicBlock* block = blocks_.Get(i);
+ // We only need to update the successor, which might be live.
for (size_t j = 0; j < block->GetSuccessors().Size(); ++j) {
block->GetSuccessors().Get(j)->RemovePredecessor(block);
}
- for (HInstructionIterator it(block->GetPhis()); !it.Done(); it.Advance()) {
- block->RemovePhi(it.Current()->AsPhi(), /*ensure_safety=*/ false);
- }
- for (HInstructionIterator it(block->GetInstructions()); !it.Done(); it.Advance()) {
- block->RemoveInstruction(it.Current(), /*ensure_safety=*/ false);
- }
+ // Remove the block from the list of blocks, so that further analyses
+ // never see it.
+ blocks_.Put(i, nullptr);
}
}
}
@@ -258,6 +254,7 @@
// (2): Simplify loops by having only one back edge, and one preheader.
for (size_t i = 0; i < blocks_.Size(); ++i) {
HBasicBlock* block = blocks_.Get(i);
+ if (block == nullptr) continue;
if (block->GetSuccessors().Size() > 1) {
for (size_t j = 0; j < block->GetSuccessors().Size(); ++j) {
HBasicBlock* successor = block->GetSuccessors().Get(j);
@@ -274,8 +271,9 @@
}
bool HGraph::AnalyzeNaturalLoops() const {
- for (size_t i = 0; i < blocks_.Size(); ++i) {
- HBasicBlock* block = blocks_.Get(i);
+ // Order does not matter.
+ for (HReversePostOrderIterator it(*this); !it.Done(); it.Advance()) {
+ HBasicBlock* block = it.Current();
if (block->IsLoopHeader()) {
HLoopInformation* info = block->GetLoopInformation();
if (!info->Populate()) {
diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 539e0b5..4bca9aa 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -253,7 +253,7 @@
ArenaBitVector* visited,
ArenaBitVector* visiting);
void RemoveInstructionsAsUsersFromDeadBlocks(const ArenaBitVector& visited) const;
- void RemoveDeadBlocks(const ArenaBitVector& visited) const;
+ void RemoveDeadBlocks(const ArenaBitVector& visited);
template <class InstType, typename ValueType>
InstType* CreateConstant(ValueType value, ArenaSafeMap<ValueType, InstType*>* cache);