1 /*
2 * Copyright (C) 2014 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 #include "arch/x86/instruction_set_features_x86.h"
18 #include "code_generator_x86.h"
19 #include "dead_code_elimination.h"
20 #include "driver/compiler_options.h"
21 #include "graph_checker.h"
22 #include "optimizing_unit_test.h"
23 #include "pretty_printer.h"
24
25 #include "gtest/gtest.h"
26
27 namespace art {
28
29 class DeadCodeEliminationTest : public CommonCompilerTest {};
30
TestCode(const uint16_t * data,const std::string & expected_before,const std::string & expected_after)31 static void TestCode(const uint16_t* data,
32 const std::string& expected_before,
33 const std::string& expected_after) {
34 ArenaPool pool;
35 ArenaAllocator allocator(&pool);
36 HGraph* graph = CreateCFG(&allocator, data);
37 ASSERT_NE(graph, nullptr);
38
39 StringPrettyPrinter printer_before(graph);
40 printer_before.VisitInsertionOrder();
41 std::string actual_before = printer_before.str();
42 ASSERT_EQ(actual_before, expected_before);
43
44 std::unique_ptr<const X86InstructionSetFeatures> features_x86(
45 X86InstructionSetFeatures::FromCppDefines());
46 x86::CodeGeneratorX86 codegenX86(graph, *features_x86.get(), CompilerOptions());
47 HDeadCodeElimination(graph, nullptr /* stats */, "dead_code_elimination").Run();
48 GraphChecker graph_checker(graph);
49 graph_checker.Run();
50 ASSERT_TRUE(graph_checker.IsValid());
51
52 StringPrettyPrinter printer_after(graph);
53 printer_after.VisitInsertionOrder();
54 std::string actual_after = printer_after.str();
55 ASSERT_EQ(actual_after, expected_after);
56 }
57
58 /**
59 * Small three-register program.
60 *
61 * 16-bit
62 * offset
63 * ------
64 * v1 <- 1 0. const/4 v1, #+1
65 * v0 <- 0 1. const/4 v0, #+0
66 * if v1 >= 0 goto L1 2. if-gez v1, +3
67 * v0 <- v1 4. move v0, v1
68 * L1: v2 <- v0 + v1 5. add-int v2, v0, v1
69 * return-void 7. return
70 */
TEST_F(DeadCodeEliminationTest,AdditionAndConditionalJump)71 TEST_F(DeadCodeEliminationTest, AdditionAndConditionalJump) {
72 const uint16_t data[] = THREE_REGISTERS_CODE_ITEM(
73 Instruction::CONST_4 | 1 << 8 | 1 << 12,
74 Instruction::CONST_4 | 0 << 8 | 0 << 12,
75 Instruction::IF_GEZ | 1 << 8, 3,
76 Instruction::MOVE | 0 << 8 | 1 << 12,
77 Instruction::ADD_INT | 2 << 8, 0 | 1 << 8,
78 Instruction::RETURN_VOID);
79
80 std::string expected_before =
81 "BasicBlock 0, succ: 1\n"
82 " 3: IntConstant [9, 8, 5]\n"
83 " 4: IntConstant [8, 5]\n"
84 " 1: SuspendCheck\n"
85 " 2: Goto 1\n"
86 "BasicBlock 1, pred: 0, succ: 5, 2\n"
87 " 5: GreaterThanOrEqual(3, 4) [6]\n"
88 " 6: If(5)\n"
89 "BasicBlock 2, pred: 1, succ: 3\n"
90 " 7: Goto 3\n"
91 "BasicBlock 3, pred: 5, 2, succ: 4\n"
92 " 8: Phi(4, 3) [9]\n"
93 " 9: Add(8, 3)\n"
94 " 10: ReturnVoid\n"
95 "BasicBlock 4, pred: 3\n"
96 " 11: Exit\n"
97 "BasicBlock 5, pred: 1, succ: 3\n"
98 " 0: Goto 3\n";
99
100 // Expected difference after dead code elimination.
101 diff_t expected_diff = {
102 { " 3: IntConstant [9, 8, 5]\n", " 3: IntConstant [8, 5]\n" },
103 { " 8: Phi(4, 3) [9]\n", " 8: Phi(4, 3)\n" },
104 { " 9: Add(8, 3)\n", removed }
105 };
106 std::string expected_after = Patch(expected_before, expected_diff);
107
108 TestCode(data, expected_before, expected_after);
109 }
110
111 /**
112 * Three-register program with jumps leading to the creation of many
113 * blocks.
114 *
115 * The intent of this test is to ensure that all dead instructions are
116 * actually pruned at compile-time, thanks to the (backward)
117 * post-order traversal of the the dominator tree.
118 *
119 * 16-bit
120 * offset
121 * ------
122 * v0 <- 0 0. const/4 v0, #+0
123 * v1 <- 1 1. const/4 v1, #+1
124 * v2 <- v0 + v1 2. add-int v2, v0, v1
125 * goto L2 4. goto +4
126 * L1: v1 <- v0 + 3 5. add-int/lit16 v1, v0, #+3
127 * goto L3 7. goto +4
128 * L2: v0 <- v2 + 2 8. add-int/lit16 v0, v2, #+2
129 * goto L1 10. goto +(-5)
130 * L3: v2 <- v1 + 4 11. add-int/lit16 v2, v1, #+4
131 * return 13. return-void
132 */
TEST_F(DeadCodeEliminationTest,AdditionsAndInconditionalJumps)133 TEST_F(DeadCodeEliminationTest, AdditionsAndInconditionalJumps) {
134 const uint16_t data[] = THREE_REGISTERS_CODE_ITEM(
135 Instruction::CONST_4 | 0 << 8 | 0 << 12,
136 Instruction::CONST_4 | 1 << 8 | 1 << 12,
137 Instruction::ADD_INT | 2 << 8, 0 | 1 << 8,
138 Instruction::GOTO | 4 << 8,
139 Instruction::ADD_INT_LIT16 | 1 << 8 | 0 << 12, 3,
140 Instruction::GOTO | 4 << 8,
141 Instruction::ADD_INT_LIT16 | 0 << 8 | 2 << 12, 2,
142 static_cast<uint16_t>(Instruction::GOTO | 0xFFFFFFFB << 8),
143 Instruction::ADD_INT_LIT16 | 2 << 8 | 1 << 12, 4,
144 Instruction::RETURN_VOID);
145
146 std::string expected_before =
147 "BasicBlock 0, succ: 1\n"
148 " 2: IntConstant [4]\n"
149 " 3: IntConstant [4]\n"
150 " 6: IntConstant [7]\n"
151 " 9: IntConstant [10]\n"
152 " 12: IntConstant [13]\n"
153 " 0: SuspendCheck\n"
154 " 1: Goto 1\n"
155 "BasicBlock 1, pred: 0, succ: 3\n"
156 " 4: Add(2, 3) [7]\n"
157 " 5: Goto 3\n"
158 "BasicBlock 2, pred: 3, succ: 4\n"
159 " 10: Add(7, 9) [13]\n"
160 " 11: Goto 4\n"
161 "BasicBlock 3, pred: 1, succ: 2\n"
162 " 7: Add(4, 6) [10]\n"
163 " 8: Goto 2\n"
164 "BasicBlock 4, pred: 2, succ: 5\n"
165 " 13: Add(10, 12)\n"
166 " 14: ReturnVoid\n"
167 "BasicBlock 5, pred: 4\n"
168 " 15: Exit\n";
169
170 std::string expected_after =
171 "BasicBlock 0, succ: 1\n"
172 " 0: SuspendCheck\n"
173 " 1: Goto 1\n"
174 "BasicBlock 1, pred: 0, succ: 5\n"
175 " 14: ReturnVoid\n"
176 "BasicBlock 5, pred: 1\n"
177 " 15: Exit\n";
178
179 TestCode(data, expected_before, expected_after);
180 }
181
182 } // namespace art
183