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-rw-r--r--compiler/optimizing/linearize_test.cc59
-rw-r--r--compiler/optimizing/nodes.h2
-rw-r--r--compiler/optimizing/ssa_liveness_analysis.cc94
-rw-r--r--compiler/optimizing/ssa_liveness_analysis.h34
4 files changed, 128 insertions, 61 deletions
diff --git a/compiler/optimizing/linearize_test.cc b/compiler/optimizing/linearize_test.cc
index 6dd4207795..c49cf7e03f 100644
--- a/compiler/optimizing/linearize_test.cc
+++ b/compiler/optimizing/linearize_test.cc
@@ -50,10 +50,9 @@ static void TestCode(const uint16_t* data, const int* expected_order, size_t num
SsaLivenessAnalysis liveness(*graph, &codegen);
liveness.Analyze();
- ASSERT_EQ(liveness.GetLinearPostOrder().Size(), number_of_blocks);
+ ASSERT_EQ(liveness.GetLinearOrder().Size(), number_of_blocks);
for (size_t i = 0; i < number_of_blocks; ++i) {
- ASSERT_EQ(liveness.GetLinearPostOrder().Get(number_of_blocks - i - 1)->GetBlockId(),
- expected_order[i]);
+ ASSERT_EQ(liveness.GetLinearOrder().Get(i)->GetBlockId(), expected_order[i]);
}
}
@@ -194,4 +193,58 @@ TEST(LinearizeTest, CFG5) {
TestCode(data, blocks, 12);
}
+TEST(LinearizeTest, CFG6) {
+ // Block0
+ // |
+ // Block1
+ // |
+ // Block2 ++++++++++++++
+ // | +
+ // Block3 +
+ // / \ +
+ // Block8 Block4 +
+ // | / \ +
+ // Block5 <- Block9 Block6 +
+ // |
+ // Block7
+ const uint16_t data[] = ONE_REGISTER_CODE_ITEM(
+ Instruction::CONST_4 | 0 | 0,
+ Instruction::GOTO | 0x0100,
+ Instruction::IF_EQ, 0x0004,
+ Instruction::IF_EQ, 0x0003,
+ Instruction::RETURN_VOID,
+ Instruction::GOTO | 0xFA00);
+
+ const int blocks[] = {0, 1, 2, 3, 4, 6, 9, 8, 5, 7};
+ TestCode(data, blocks, arraysize(blocks));
+}
+
+TEST(LinearizeTest, CFG7) {
+ // Structure of this graph (+ are back edges)
+ // Block0
+ // |
+ // Block1
+ // |
+ // Block2 ++++++++
+ // | +
+ // Block3 +
+ // / \ +
+ // Block4 Block8 +
+ // / \ | +
+ // Block5 Block9 - Block6 +
+ // |
+ // Block7
+ //
+ const uint16_t data[] = ONE_REGISTER_CODE_ITEM(
+ Instruction::CONST_4 | 0 | 0,
+ Instruction::GOTO | 0x0100,
+ Instruction::IF_EQ, 0x0005,
+ Instruction::IF_EQ, 0x0003,
+ Instruction::RETURN_VOID,
+ Instruction::GOTO | 0xFA00);
+
+ const int blocks[] = {0, 1, 2, 3, 4, 9, 8, 6, 5, 7};
+ TestCode(data, blocks, arraysize(blocks));
+}
+
} // namespace art
diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 7d52d7d221..19cd120c5c 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -233,7 +233,7 @@ class HLoopInformation : public ArenaObject<kArenaAllocMisc> {
return false;
}
- int NumberOfBackEdges() const {
+ size_t NumberOfBackEdges() const {
return back_edges_.Size();
}
diff --git a/compiler/optimizing/ssa_liveness_analysis.cc b/compiler/optimizing/ssa_liveness_analysis.cc
index 0085b27c58..54eb5813b8 100644
--- a/compiler/optimizing/ssa_liveness_analysis.cc
+++ b/compiler/optimizing/ssa_liveness_analysis.cc
@@ -28,11 +28,6 @@ void SsaLivenessAnalysis::Analyze() {
ComputeLiveness();
}
-static bool IsLoopExit(HLoopInformation* current, HLoopInformation* to) {
- // `to` is either not part of a loop, or `current` is an inner loop of `to`.
- return to == nullptr || (current != to && current->IsIn(*to));
-}
-
static bool IsLoop(HLoopInformation* info) {
return info != nullptr;
}
@@ -48,46 +43,65 @@ static bool IsInnerLoop(HLoopInformation* outer, HLoopInformation* inner) {
&& inner->IsIn(*outer);
}
-static void VisitBlockForLinearization(HBasicBlock* block,
- GrowableArray<HBasicBlock*>* order,
- ArenaBitVector* visited) {
- if (visited->IsBitSet(block->GetBlockId())) {
- return;
- }
- visited->SetBit(block->GetBlockId());
- size_t number_of_successors = block->GetSuccessors().Size();
- if (number_of_successors == 0) {
- // Nothing to do.
- } else if (number_of_successors == 1) {
- VisitBlockForLinearization(block->GetSuccessors().Get(0), order, visited);
- } else {
- DCHECK_EQ(number_of_successors, 2u);
- HBasicBlock* first_successor = block->GetSuccessors().Get(0);
- HBasicBlock* second_successor = block->GetSuccessors().Get(1);
- HLoopInformation* my_loop = block->GetLoopInformation();
- HLoopInformation* first_loop = first_successor->GetLoopInformation();
- HLoopInformation* second_loop = second_successor->GetLoopInformation();
-
- if (!IsLoop(my_loop)) {
- // Nothing to do. Current order is fine.
- } else if (IsLoopExit(my_loop, second_loop) && InSameLoop(my_loop, first_loop)) {
- // Visit the loop exit first in post order.
- std::swap(first_successor, second_successor);
- } else if (IsInnerLoop(my_loop, first_loop) && !IsInnerLoop(my_loop, second_loop)) {
- // Visit the inner loop last in post order.
- std::swap(first_successor, second_successor);
+static void AddToListForLinearization(GrowableArray<HBasicBlock*>* worklist, HBasicBlock* block) {
+ size_t insert_at = worklist->Size();
+ HLoopInformation* block_loop = block->GetLoopInformation();
+ for (; insert_at > 0; --insert_at) {
+ HBasicBlock* current = worklist->Get(insert_at - 1);
+ HLoopInformation* current_loop = current->GetLoopInformation();
+ if (InSameLoop(block_loop, current_loop)
+ || !IsLoop(current_loop)
+ || IsInnerLoop(current_loop, block_loop)) {
+ // The block can be processed immediately.
+ break;
}
- VisitBlockForLinearization(first_successor, order, visited);
- VisitBlockForLinearization(second_successor, order, visited);
}
- order->Add(block);
+ worklist->InsertAt(insert_at, block);
}
void SsaLivenessAnalysis::LinearizeGraph() {
- // For simplicity of the implementation, we create post linear order. The order for
- // computing live ranges is the reverse of that order.
- ArenaBitVector visited(graph_.GetArena(), graph_.GetBlocks().Size(), false);
- VisitBlockForLinearization(graph_.GetEntryBlock(), &linear_post_order_, &visited);
+ // Create a reverse post ordering with the following properties:
+ // - Blocks in a loop are consecutive,
+ // - Back-edge is the last block before loop exits.
+
+ // (1): Record the number of forward predecessors for each block. This is to
+ // ensure the resulting order is reverse post order. We could use the
+ // current reverse post order in the graph, but it would require making
+ // order queries to a GrowableArray, which is not the best data structure
+ // for it.
+ GrowableArray<uint32_t> forward_predecessors(graph_.GetArena(), graph_.GetBlocks().Size());
+ forward_predecessors.SetSize(graph_.GetBlocks().Size());
+ for (size_t i = 0, e = graph_.GetBlocks().Size(); i < e; ++i) {
+ HBasicBlock* block = graph_.GetBlocks().Get(i);
+ size_t number_of_forward_predecessors = block->GetPredecessors().Size();
+ if (block->IsLoopHeader()) {
+ // We rely on having simplified the CFG.
+ DCHECK_EQ(1u, block->GetLoopInformation()->NumberOfBackEdges());
+ number_of_forward_predecessors--;
+ }
+ forward_predecessors.Put(block->GetBlockId(), number_of_foward_predecessors);
+ }
+
+ // (2): Following a worklist approach, first start with the entry block, and
+ // iterate over the successors. When all non-back edge predecessors of a
+ // successor block are visited, the successor block is added in the worklist
+ // following an order that satisfies the requirements to build our linear graph.
+ GrowableArray<HBasicBlock*> worklist(graph_.GetArena(), 1);
+ worklist.Add(graph_.GetEntryBlock());
+ do {
+ HBasicBlock* current = worklist.Pop();
+ linear_order_.Add(current);
+ for (size_t i = 0, e = current->GetSuccessors().Size(); i < e; ++i) {
+ HBasicBlock* successor = current->GetSuccessors().Get(i);
+ int block_id = successor->GetBlockId();
+ size_t number_of_remaining_predecessors = forward_predecessors.Get(block_id);
+ if (number_of_remaining_predecessors == 1) {
+ AddToListForLinearization(&worklist, successor);
+ } else {
+ forward_predecessors.Put(block_id, number_of_remaining_predecessors - 1);
+ }
+ }
+ } while (!worklist.IsEmpty());
}
void SsaLivenessAnalysis::NumberInstructions() {
diff --git a/compiler/optimizing/ssa_liveness_analysis.h b/compiler/optimizing/ssa_liveness_analysis.h
index ca08d5b3e6..46cea6de8c 100644
--- a/compiler/optimizing/ssa_liveness_analysis.h
+++ b/compiler/optimizing/ssa_liveness_analysis.h
@@ -582,7 +582,7 @@ class SsaLivenessAnalysis : public ValueObject {
SsaLivenessAnalysis(const HGraph& graph, CodeGenerator* codegen)
: graph_(graph),
codegen_(codegen),
- linear_post_order_(graph.GetArena(), graph.GetBlocks().Size()),
+ linear_order_(graph.GetArena(), graph.GetBlocks().Size()),
block_infos_(graph.GetArena(), graph.GetBlocks().Size()),
instructions_from_ssa_index_(graph.GetArena(), 0),
instructions_from_lifetime_position_(graph.GetArena(), 0),
@@ -604,8 +604,8 @@ class SsaLivenessAnalysis : public ValueObject {
return &block_infos_.Get(block.GetBlockId())->kill_;
}
- const GrowableArray<HBasicBlock*>& GetLinearPostOrder() const {
- return linear_post_order_;
+ const GrowableArray<HBasicBlock*>& GetLinearOrder() const {
+ return linear_order_;
}
HInstruction* GetInstructionFromSsaIndex(size_t index) const {
@@ -661,7 +661,7 @@ class SsaLivenessAnalysis : public ValueObject {
const HGraph& graph_;
CodeGenerator* const codegen_;
- GrowableArray<HBasicBlock*> linear_post_order_;
+ GrowableArray<HBasicBlock*> linear_order_;
GrowableArray<BlockInfo*> block_infos_;
// Temporary array used when computing live_in, live_out, and kill sets.
@@ -674,36 +674,36 @@ class SsaLivenessAnalysis : public ValueObject {
DISALLOW_COPY_AND_ASSIGN(SsaLivenessAnalysis);
};
-class HLinearOrderIterator : public ValueObject {
+class HLinearPostOrderIterator : public ValueObject {
public:
- explicit HLinearOrderIterator(const SsaLivenessAnalysis& liveness)
- : post_order_(liveness.GetLinearPostOrder()), index_(liveness.GetLinearPostOrder().Size()) {}
+ explicit HLinearPostOrderIterator(const SsaLivenessAnalysis& liveness)
+ : order_(liveness.GetLinearOrder()), index_(liveness.GetLinearOrder().Size()) {}
bool Done() const { return index_ == 0; }
- HBasicBlock* Current() const { return post_order_.Get(index_ -1); }
+ HBasicBlock* Current() const { return order_.Get(index_ -1); }
void Advance() { --index_; DCHECK_GE(index_, 0U); }
private:
- const GrowableArray<HBasicBlock*>& post_order_;
+ const GrowableArray<HBasicBlock*>& order_;
size_t index_;
- DISALLOW_COPY_AND_ASSIGN(HLinearOrderIterator);
+ DISALLOW_COPY_AND_ASSIGN(HLinearPostOrderIterator);
};
-class HLinearPostOrderIterator : public ValueObject {
+class HLinearOrderIterator : public ValueObject {
public:
- explicit HLinearPostOrderIterator(const SsaLivenessAnalysis& liveness)
- : post_order_(liveness.GetLinearPostOrder()), index_(0) {}
+ explicit HLinearOrderIterator(const SsaLivenessAnalysis& liveness)
+ : order_(liveness.GetLinearOrder()), index_(0) {}
- bool Done() const { return index_ == post_order_.Size(); }
- HBasicBlock* Current() const { return post_order_.Get(index_); }
+ bool Done() const { return index_ == order_.Size(); }
+ HBasicBlock* Current() const { return order_.Get(index_); }
void Advance() { ++index_; }
private:
- const GrowableArray<HBasicBlock*>& post_order_;
+ const GrowableArray<HBasicBlock*>& order_;
size_t index_;
- DISALLOW_COPY_AND_ASSIGN(HLinearPostOrderIterator);
+ DISALLOW_COPY_AND_ASSIGN(HLinearOrderIterator);
};
} // namespace art
generated by cgit v1.2.3-59-g8ed1b (git 2.39.0) at 2025-10-20 21:05:15 +0000