1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/*
18 * This optimization recognizes the common diamond selection pattern and
19 * replaces it with an instance of the HSelect instruction.
20 *
21 * Recognized pattern:
22 *
23 *          If [ Condition ]
24 *            /          \
25 *      false branch  true branch
26 *            \          /
27 *     Phi [FalseValue, TrueValue]
28 *
29 * The pattern will be simplified if `true_branch` and `false_branch` each
30 * contain at most one instruction without any side effects.
31 *
32 * Blocks are merged into one and Select replaces the If and the Phi:
33 *              true branch
34 *              false branch
35 *              Select [FalseValue, TrueValue, Condition]
36 *
37 * Note: In order to recognize no side-effect blocks, this optimization must be
38 * run after the instruction simplifier has removed redundant suspend checks.
39 */
40
41#ifndef ART_COMPILER_OPTIMIZING_SELECT_GENERATOR_H_
42#define ART_COMPILER_OPTIMIZING_SELECT_GENERATOR_H_
43
44#include "optimization.h"
45
46namespace art {
47
48class HSelectGenerator : public HOptimization {
49 public:
50  HSelectGenerator(HGraph* graph, OptimizingCompilerStats* stats)
51    : HOptimization(graph, kSelectGeneratorPassName, stats) {}
52
53  void Run() OVERRIDE;
54
55  static constexpr const char* kSelectGeneratorPassName = "select_generator";
56
57 private:
58  DISALLOW_COPY_AND_ASSIGN(HSelectGenerator);
59};
60
61}  // namespace art
62
63#endif  // ART_COMPILER_OPTIMIZING_SELECT_GENERATOR_H_
64