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.CounterKey;
33 import org.graalvm.compiler.debug.DebugContext;
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.NestedBooleanOptionKey;
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 NestedBooleanOptionKey LIROptStackMoveOptimizer = new NestedBooleanOptionKey(LIROptimization, true);
62 // @formatter:on
63 }
64
65 private static final CounterKey eliminatedBackup = DebugContext.counter("StackMoveOptimizer[EliminatedScratchBackupRestore]");
66
67 @Override
68 protected void run(TargetDescription target, LIRGenerationResult lirGenRes, PostAllocationOptimizationContext context) {
69 LIR lir = lirGenRes.getLIR();
70 DebugContext debug = lir.getDebug();
71 for (AbstractBlockBase<?> block : lir.getControlFlowGraph().getBlocks()) {
72 ArrayList<LIRInstruction> instructions = lir.getLIRforBlock(block);
73 new Closure().process(debug, instructions);
74 }
75 }
76
77 private static class Closure {
78 private static final int NONE = -1;
79
80 private int begin = NONE;
81 private Register reg = null;
82 private List<AllocatableValue> dst;
83 private List<Value> src;
84 private AllocatableValue slot;
85 private boolean removed = false;
86
87 public void process(DebugContext debug, List<LIRInstruction> instructions) {
88 for (int i = 0; i < instructions.size(); i++) {
89 LIRInstruction inst = instructions.get(i);
90
91 if (isStackMove(inst)) {
92 AMD64StackMove move = asStackMove(inst);
93
94 if (reg != null && !reg.equals(move.getScratchRegister())) {
95 // end of trace & start of new
96 replaceStackMoves(debug, instructions);
97 }
98
99 // lazy initialize
100 if (dst == null) {
101 assert src == null;
102 dst = new ArrayList<>();
103 src = new ArrayList<>();
104 }
105
106 dst.add(move.getResult());
107 src.add(move.getInput());
108
109 if (begin == NONE) {
110 // trace begin
111 begin = i;
112 reg = move.getScratchRegister();
113 slot = move.getBackupSlot();
114 }
115
116 } else if (begin != NONE) {
117 // end of trace
118 replaceStackMoves(debug, instructions);
119 }
120 }
121 // remove instructions
122 if (removed) {
123 instructions.removeAll(Collections.singleton(null));
124 }
125
126 }
127
128 private void replaceStackMoves(DebugContext debug, List<LIRInstruction> instructions) {
129 int size = dst.size();
130 if (size > 1) {
131 AMD64MultiStackMove multiMove = new AMD64MultiStackMove(dst.toArray(new AllocatableValue[size]), src.toArray(new AllocatableValue[size]), reg, slot);
132 // replace first instruction
133 instructions.set(begin, multiMove);
134 // and null out others
135 Collections.fill(instructions.subList(begin + 1, begin + size), null);
136 // removed
137 removed = true;
138 eliminatedBackup.add(debug, size - 1);
139 }
140 // reset
141 dst.clear();
142 src.clear();
143 begin = NONE;
144 reg = null;
145 slot = null;
146 }
147 }
148
149 private static AMD64StackMove asStackMove(LIRInstruction inst) {
150 assert isStackMove(inst);
151 return (AMD64StackMove) inst;
152 }
153
154 private static boolean isStackMove(LIRInstruction inst) {
155 return inst instanceof AMD64StackMove;
156 }
157
158 }