Build live-in, live-out and kill sets for each block.
This information will be used when computing live ranges of
instructions.
Change-Id: I345ee833c1ccb4a8e725c7976453f6d58d350d74
diff --git a/compiler/optimizing/ssa_liveness_analysis.h b/compiler/optimizing/ssa_liveness_analysis.h
new file mode 100644
index 0000000..6a901d1
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+++ b/compiler/optimizing/ssa_liveness_analysis.h
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+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_COMPILER_OPTIMIZING_SSA_LIVENESS_ANALYSIS_H_
+#define ART_COMPILER_OPTIMIZING_SSA_LIVENESS_ANALYSIS_H_
+
+#include "nodes.h"
+
+namespace art {
+
+class BlockInfo : public ArenaObject {
+ public:
+ BlockInfo(ArenaAllocator* allocator, const HBasicBlock& block, size_t number_of_ssa_values)
+ : block_(block),
+ live_in_(allocator, number_of_ssa_values, false),
+ live_out_(allocator, number_of_ssa_values, false),
+ kill_(allocator, number_of_ssa_values, false) {
+ live_in_.ClearAllBits();
+ live_out_.ClearAllBits();
+ kill_.ClearAllBits();
+ }
+
+ private:
+ const HBasicBlock& block_;
+ ArenaBitVector live_in_;
+ ArenaBitVector live_out_;
+ ArenaBitVector kill_;
+
+ friend class SsaLivenessAnalysis;
+
+ DISALLOW_COPY_AND_ASSIGN(BlockInfo);
+};
+
+class SsaLivenessAnalysis : public ValueObject {
+ public:
+ explicit SsaLivenessAnalysis(const HGraph& graph)
+ : graph_(graph),
+ block_infos_(graph.GetArena(), graph.GetBlocks().Size()),
+ number_of_ssa_values_(0) {
+ block_infos_.SetSize(graph.GetBlocks().Size());
+ }
+
+ void Analyze();
+
+ BitVector* GetLiveInSet(const HBasicBlock& block) const {
+ return &block_infos_.Get(block.GetBlockId())->live_in_;
+ }
+
+ BitVector* GetLiveOutSet(const HBasicBlock& block) const {
+ return &block_infos_.Get(block.GetBlockId())->live_out_;
+ }
+
+ BitVector* GetKillSet(const HBasicBlock& block) const {
+ return &block_infos_.Get(block.GetBlockId())->kill_;
+ }
+
+ private:
+ // Give an SSA number to each instruction that defines a value used by another instruction.
+ void NumberInstructions();
+
+ // Compute live_in, live_out and kill sets.
+ void ComputeSets();
+
+ // Compute the initial live_in, live_out and kill sets, without analyzing
+ // backward branches.
+ void ComputeInitialSets();
+
+ // After computing the initial sets, this method does a fixed point
+ // calculation over the live_in and live_out set to take into account
+ // backwards branches.
+ void ComputeLiveInAndLiveOutSets();
+
+ // Update the live_in set of the block and returns whether it has changed.
+ bool UpdateLiveIn(const HBasicBlock& block);
+
+ // Update the live_out set of the block and returns whether it has changed.
+ bool UpdateLiveOut(const HBasicBlock& block);
+
+ const HGraph& graph_;
+ GrowableArray<BlockInfo*> block_infos_;
+ size_t number_of_ssa_values_;
+
+ DISALLOW_COPY_AND_ASSIGN(SsaLivenessAnalysis);
+};
+
+} // namespace art
+
+#endif // ART_COMPILER_OPTIMIZING_SSA_LIVENESS_ANALYSIS_H_