1 /*
2 * Copyright (c) 2015, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23 package org.graalvm.compiler.lir.amd64.phases;
24
25 import static org.graalvm.compiler.lir.phases.LIRPhase.Options.LIROptimization;
26
27 import java.util.ArrayList;
28 import java.util.Collections;
29 import java.util.List;
30
31 import org.graalvm.compiler.core.common.cfg.AbstractBlockBase;
32 import org.graalvm.compiler.debug.Debug;
33 import org.graalvm.compiler.debug.DebugCounter;
34 import org.graalvm.compiler.lir.LIR;
35 import org.graalvm.compiler.lir.LIRInstruction;
36 import org.graalvm.compiler.lir.RedundantMoveElimination;
37 import org.graalvm.compiler.lir.amd64.AMD64Move.AMD64MultiStackMove;
38 import org.graalvm.compiler.lir.amd64.AMD64Move.AMD64StackMove;
39 import org.graalvm.compiler.lir.gen.LIRGenerationResult;
40 import org.graalvm.compiler.lir.phases.PostAllocationOptimizationPhase;
41 import org.graalvm.compiler.options.NestedBooleanOptionValue;
42 import org.graalvm.compiler.options.Option;
43 import org.graalvm.compiler.options.OptionType;
44
45 import jdk.vm.ci.code.Register;
46 import jdk.vm.ci.code.TargetDescription;
47 import jdk.vm.ci.meta.AllocatableValue;
48 import jdk.vm.ci.meta.Value;
49
50 /**
51 * Replaces sequential {@link AMD64StackMove}s of the same type with a single
52 * {@link AMD64MultiStackMove} to avoid storing/restoring the scratch register multiple times.
53 *
54 * Note: this phase must be inserted <b>after</b> {@link RedundantMoveElimination} phase because
55 * {@link AMD64MultiStackMove} are not probably detected.
56 */
57 public class StackMoveOptimizationPhase extends PostAllocationOptimizationPhase {
58 public static class Options {
59 // @formatter:off
60 @Option(help = "", type = OptionType.Debug)
61 public static final NestedBooleanOptionValue LIROptStackMoveOptimizer = new NestedBooleanOptionValue(LIROptimization, true);
62 // @formatter:on
63 }
64
65 private static final DebugCounter eliminatedBackup = Debug.counter("StackMoveOptimizer[EliminatedScratchBackupRestore]");
66
67 @Override
68 protected void run(TargetDescription target, LIRGenerationResult lirGenRes, PostAllocationOptimizationContext context) {
69 LIR lir = lirGenRes.getLIR();
70 for (AbstractBlockBase<?> block : lir.getControlFlowGraph().getBlocks()) {
71 List<LIRInstruction> instructions = lir.getLIRforBlock(block);
72 new Closure().process(instructions);
73 }
74 }
75
76 private static class Closure {
77 private static final int NONE = -1;
78
79 private int begin = NONE;
80 private Register reg = null;
81 private List<AllocatableValue> dst;
82 private List<Value> src;
83 private AllocatableValue slot;
84 private boolean removed = false;
85
86 public void process(List<LIRInstruction> instructions) {
87 for (int i = 0; i < instructions.size(); i++) {
88 LIRInstruction inst = instructions.get(i);
89
90 if (isStackMove(inst)) {
91 AMD64StackMove move = asStackMove(inst);
92
93 if (reg != null && !reg.equals(move.getScratchRegister())) {
94 // end of trace & start of new
95 replaceStackMoves(instructions);
96 }
97
98 // lazy initialize
99 if (dst == null) {
100 assert src == null;
101 dst = new ArrayList<>();
102 src = new ArrayList<>();
103 }
104
105 dst.add(move.getResult());
106 src.add(move.getInput());
107
108 if (begin == NONE) {
109 // trace begin
110 begin = i;
111 reg = move.getScratchRegister();
112 slot = move.getBackupSlot();
113 }
114
115 } else if (begin != NONE) {
116 // end of trace
117 replaceStackMoves(instructions);
118 }
119 }
120 // remove instructions
121 if (removed) {
122 instructions.removeAll(Collections.singleton(null));
123 }
124
125 }
126
127 private void replaceStackMoves(List<LIRInstruction> instructions) {
128 int size = dst.size();
129 if (size > 1) {
130 AMD64MultiStackMove multiMove = new AMD64MultiStackMove(dst.toArray(new AllocatableValue[size]), src.toArray(new AllocatableValue[size]), reg, slot);
131 // replace first instruction
132 instructions.set(begin, multiMove);
133 // and null out others
134 Collections.fill(instructions.subList(begin + 1, begin + size), null);
135 // removed
136 removed = true;
137 eliminatedBackup.add(size - 1);
138 }
139 // reset
140 dst.clear();
141 src.clear();
142 begin = NONE;
143 reg = null;
144 slot = null;
145 }
146 }
147
148 private static AMD64StackMove asStackMove(LIRInstruction inst) {
149 assert isStackMove(inst);
150 return (AMD64StackMove) inst;
151 }
152
153 private static boolean isStackMove(LIRInstruction inst) {
154 return inst instanceof AMD64StackMove;
155 }
156
157 }