Refactoring of graph linearization and linear order.

Rationale:
Ownership of graph's linear order and iterators was
a bit unclear now that other phases are using it.
New approach allows phases to compute their own
order, while ssa_liveness is sole owner for graph
(since it is not mutated afterwards).

Also shortens lifetime of loop's arena.

Test: test-art-host
Change-Id: Ib7137d1203a1e0a12db49868f4117d48a4277f30

1 files changed, 45 insertions, 0 deletions

diff --git a/compiler/optimizing/linear_order.h b/compiler/optimizing/linear_order.h
new file mode 100644
index 0000000000..cdbdd0714b
--- /dev/null
+++ b/compiler/optimizing/linear_order.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2016 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_LINEAR_ORDER_H_
+#define ART_COMPILER_OPTIMIZING_LINEAR_ORDER_H_
+
+#include "nodes.h"
+
+namespace art {
+
+// Linearizes the 'graph' such that:
+// (1): a block is always after its dominator,
+// (2): blocks of loops are contiguous.
+//
+// Storage is obtained through 'allocator' and the linear order it computed
+// into 'linear_order'. Once computed, iteration can be expressed as:
+//
+// for (HBasicBlock* block : linear_order)                   // linear order
+//
+// for (HBasicBlock* block : LinearPostOrder(linear_order))  // linear post order
+//
+void LinearizeGraph(const HGraph* graph,
+                    ArenaAllocator* allocator,
+                    ArenaVector<HBasicBlock*>* linear_order);
+
+inline auto LinearPostOrder(const ArenaVector<HBasicBlock*>& linear_order) {
+  return MakeIterationRange(linear_order.rbegin(), linear_order.rend());
+}
+
+}  // namespace art
+
+#endif  // ART_COMPILER_OPTIMIZING_LINEAR_ORDER_H_