Import Dart's parallel move resolver.

And write a few tests while at it.

A parallel move resolver will be needed for performing multiple moves
that are conceptually parallel, for example moves at a block
exit that branches to a block with phi nodes.

Change-Id: Ib95b247b4fc3f2c2fcab3b8c8d032abbd6104cd7

1 files changed, 63 insertions, 0 deletions

diff --git a/compiler/optimizing/parallel_move_resolver.h b/compiler/optimizing/parallel_move_resolver.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_PARALLEL_MOVE_RESOLVER_H_
+#define ART_COMPILER_OPTIMIZING_PARALLEL_MOVE_RESOLVER_H_
+
+#include "utils/allocation.h"
+#include "utils/growable_array.h"
+
+namespace art {
+
+class HParallelMove;
+class MoveOperands;
+
+/**
+ * Helper class to resolve a set of parallel moves. Architecture dependent code
+ * generator must have their own subclass that implements the `EmitMove` and `EmitSwap`
+ * operations.
+ */
+class ParallelMoveResolver : public ValueObject {
+ public:
+  explicit ParallelMoveResolver(ArenaAllocator* allocator) : moves_(allocator, 32) {}
+
+  // Resolve a set of parallel moves, emitting assembler instructions.
+  void EmitNativeCode(HParallelMove* parallel_move);
+
+ protected:
+  // Emit a move.
+  virtual void EmitMove(size_t index) = 0;
+
+  // Execute a move by emitting a swap of two operands.
+  virtual void EmitSwap(size_t index) = 0;
+
+  // List of moves not yet resolved.
+  GrowableArray<MoveOperands*> moves_;
+
+ private:
+  // Build the initial list of moves.
+  void BuildInitialMoveList(HParallelMove* parallel_move);
+
+  // Perform the move at the moves_ index in question (possibly requiring
+  // other moves to satisfy dependencies).
+  void PerformMove(size_t index);
+
+  DISALLOW_COPY_AND_ASSIGN(ParallelMoveResolver);
+};
+
+}  // namespace art
+
+#endif  // ART_COMPILER_OPTIMIZING_PARALLEL_MOVE_RESOLVER_H_