Initiate a dead code elimination pass in the optimizing compiler.
Change-Id: Ie9db5d8e2c2c30e34145a0f7d2386b8ec58cfc4e
diff --git a/compiler/optimizing/dead_code_elimination_test.cc b/compiler/optimizing/dead_code_elimination_test.cc
new file mode 100644
index 0000000..245bcb2
--- /dev/null
+++ b/compiler/optimizing/dead_code_elimination_test.cc
@@ -0,0 +1,185 @@
+/*
+ * 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.
+ */
+
+#include "dead_code_elimination.h"
+#include "pretty_printer.h"
+#include "graph_checker.h"
+#include "optimizing_unit_test.h"
+
+#include "gtest/gtest.h"
+
+namespace art {
+
+static void TestCode(const uint16_t* data,
+ const std::string& expected_before,
+ const std::string& expected_after) {
+ ArenaPool pool;
+ ArenaAllocator allocator(&pool);
+ HGraph* graph = CreateCFG(&allocator, data);
+ ASSERT_NE(graph, nullptr);
+
+ graph->BuildDominatorTree();
+ graph->TransformToSSA();
+
+ StringPrettyPrinter printer_before(graph);
+ printer_before.VisitInsertionOrder();
+ std::string actual_before = printer_before.str();
+ ASSERT_EQ(actual_before, expected_before);
+
+ DeadCodeElimination(graph).Run();
+
+ StringPrettyPrinter printer_after(graph);
+ printer_after.VisitInsertionOrder();
+ std::string actual_after = printer_after.str();
+ ASSERT_EQ(actual_after, expected_after);
+
+ SSAChecker ssa_checker(&allocator, graph);
+ ssa_checker.VisitInsertionOrder();
+ ASSERT_TRUE(ssa_checker.IsValid());
+}
+
+
+/**
+ * Small three-register program.
+ *
+ * 16-bit
+ * offset
+ * ------
+ * v1 <- 1 0. const/4 v1, #+1
+ * v0 <- 0 1. const/4 v0, #+0
+ * if v1 >= 0 goto L1 2. if-gez v1, +3
+ * v0 <- v1 4. move v0, v1
+ * L1: v2 <- v0 + v1 5. add-int v2, v0, v1
+ * return-void 7. return
+ */
+TEST(DeadCodeElimination, AdditionAndConditionalJump) {
+ const uint16_t data[] = THREE_REGISTERS_CODE_ITEM(
+ Instruction::CONST_4 | 1 << 8 | 1 << 12,
+ Instruction::CONST_4 | 0 << 8 | 0 << 12,
+ Instruction::IF_GEZ | 1 << 8, 3,
+ Instruction::MOVE | 0 << 8 | 1 << 12,
+ Instruction::ADD_INT | 2 << 8, 0 | 1 << 8,
+ Instruction::RETURN_VOID);
+
+ std::string expected_before =
+ "BasicBlock 0, succ: 1\n"
+ " 3: IntConstant [15, 22, 8]\n"
+ " 5: IntConstant [22, 8]\n"
+ " 19: SuspendCheck\n"
+ " 20: Goto 1\n"
+ "BasicBlock 1, pred: 0, succ: 5, 2\n"
+ " 8: GreaterThanOrEqual(3, 5) [9]\n"
+ " 9: If(8)\n"
+ "BasicBlock 2, pred: 1, succ: 3\n"
+ " 12: Goto 3\n"
+ "BasicBlock 3, pred: 2, 5, succ: 4\n"
+ " 22: Phi(3, 5) [15]\n"
+ " 15: Add(22, 3)\n"
+ " 17: ReturnVoid\n"
+ "BasicBlock 4, pred: 3\n"
+ " 18: Exit\n"
+ "BasicBlock 5, pred: 1, succ: 3\n"
+ " 21: Goto 3\n";
+
+ diff_t expected_diff = {
+ { " 3: IntConstant [15, 22, 8]\n", " 3: IntConstant [22, 8]\n" },
+ { " 22: Phi(3, 5) [15]\n", " 22: Phi(3, 5)\n" },
+ { " 15: Add(22, 3)\n", removed }
+ };
+ std::string expected_after = Patch(expected_before, expected_diff);
+
+ TestCode(data, expected_before, expected_after);
+}
+
+/**
+ * Three-register program with jumps leading to the creation of many
+ * blocks.
+ *
+ * The intent of this test is to ensure that all dead instructions are
+ * actually pruned at compile-time, thanks to the (backward)
+ * post-order traversal of the the dominator tree.
+ *
+ * 16-bit
+ * offset
+ * ------
+ * v0 <- 0 0. const/4 v0, #+0
+ * v1 <- 1 1. const/4 v1, #+1
+ * v2 <- v0 + v1 2. add-int v2, v0, v1
+ * goto L2 4. goto +4
+ * L1: v1 <- v0 + 3 5. add-int/lit16 v1, v0, #+3
+ * goto L3 7. goto +4
+ * L2: v0 <- v2 + 2 8. add-int/lit16 v0, v2, #+2
+ * goto L1 10. goto +(-5)
+ * L3: v2 <- v1 + 4 11. add-int/lit16 v2, v1, #+4
+ * return 13. return-void
+ */
+TEST(DeadCodeElimination, AdditionsAndInconditionalJumps) {
+ const uint16_t data[] = THREE_REGISTERS_CODE_ITEM(
+ Instruction::CONST_4 | 0 << 8 | 0 << 12,
+ Instruction::CONST_4 | 1 << 8 | 1 << 12,
+ Instruction::ADD_INT | 2 << 8, 0 | 1 << 8,
+ Instruction::GOTO | 4 << 8,
+ Instruction::ADD_INT_LIT16 | 1 << 8 | 0 << 12, 3,
+ Instruction::GOTO | 4 << 8,
+ Instruction::ADD_INT_LIT16 | 0 << 8 | 2 << 12, 2,
+ static_cast<uint16_t>(Instruction::GOTO | -5 << 8),
+ Instruction::ADD_INT_LIT16 | 2 << 8 | 1 << 12, 4,
+ Instruction::RETURN_VOID);
+
+ std::string expected_before =
+ "BasicBlock 0, succ: 1\n"
+ " 3: IntConstant [9]\n"
+ " 5: IntConstant [9]\n"
+ " 13: IntConstant [14]\n"
+ " 18: IntConstant [19]\n"
+ " 24: IntConstant [25]\n"
+ " 29: SuspendCheck\n"
+ " 30: Goto 1\n"
+ "BasicBlock 1, pred: 0, succ: 3\n"
+ " 9: Add(3, 5) [19]\n"
+ " 11: Goto 3\n"
+ "BasicBlock 2, pred: 3, succ: 4\n"
+ " 14: Add(19, 13) [25]\n"
+ " 16: Goto 4\n"
+ "BasicBlock 3, pred: 1, succ: 2\n"
+ " 19: Add(9, 18) [14]\n"
+ " 21: SuspendCheck\n"
+ " 22: Goto 2\n"
+ "BasicBlock 4, pred: 2, succ: 5\n"
+ " 25: Add(14, 24)\n"
+ " 27: ReturnVoid\n"
+ "BasicBlock 5, pred: 4\n"
+ " 28: Exit\n";
+
+ // Expected difference after constant propagation.
+ diff_t expected_diff = {
+ { " 13: IntConstant [14]\n", removed },
+ { " 24: IntConstant [25]\n", removed },
+ { " 14: Add(19, 13) [25]\n", removed },
+ // The SuspendCheck instruction following this Add instruction
+ // inserts the latter in an environment, thus making it "used" and
+ // therefore non removable. It ensues that some other Add and
+ // IntConstant instructions cannot be removed, as they are direct
+ // or indirect inputs of the initial Add instruction.
+ { " 19: Add(9, 18) [14]\n", " 19: Add(9, 18) []\n" },
+ { " 25: Add(14, 24)\n", removed },
+ };
+ std::string expected_after = Patch(expected_before, expected_diff);
+
+ TestCode(data, expected_before, expected_after);
+}
+
+} // namespace art