1 /*
2 * Copyright (c) 2016, 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.replacements;
24
25 import static org.graalvm.compiler.replacements.SnippetTemplate.DEFAULT_REPLACER;
26
27 import org.graalvm.compiler.api.replacements.Snippet;
28 import org.graalvm.compiler.api.replacements.Snippet.ConstantParameter;
29 import org.graalvm.compiler.api.replacements.SnippetReflectionProvider;
30 import org.graalvm.compiler.nodes.StructuredGraph;
31 import org.graalvm.compiler.nodes.spi.LoweringTool;
32 import org.graalvm.compiler.options.OptionValues;
33 import org.graalvm.compiler.phases.util.Providers;
34 import org.graalvm.compiler.replacements.SnippetTemplate.AbstractTemplates;
35 import org.graalvm.compiler.replacements.SnippetTemplate.Arguments;
36 import org.graalvm.compiler.replacements.SnippetTemplate.SnippetInfo;
37 import org.graalvm.compiler.replacements.nodes.ExplodeLoopNode;
38
39 import jdk.vm.ci.code.TargetDescription;
40 import sun.misc.Unsafe;
41
42 public class ConstantStringIndexOfSnippets implements Snippets {
43 public static class Templates extends AbstractTemplates {
44
45 private final SnippetInfo indexOfConstant = snippet(ConstantStringIndexOfSnippets.class, "indexOfConstant");
46
47 public Templates(OptionValues options, Providers providers, SnippetReflectionProvider snippetReflection, TargetDescription target) {
48 super(options, providers, snippetReflection, target);
49 }
50
51 public void lower(SnippetLowerableMemoryNode stringIndexOf, LoweringTool tool) {
52 StructuredGraph graph = stringIndexOf.graph();
53 Arguments args = new Arguments(indexOfConstant, graph.getGuardsStage(), tool.getLoweringStage());
54 args.add("source", stringIndexOf.getArgument(0));
55 args.add("sourceOffset", stringIndexOf.getArgument(1));
56 args.add("sourceCount", stringIndexOf.getArgument(2));
57 args.addConst("target", stringIndexOf.getArgument(3));
58 args.add("targetOffset", stringIndexOf.getArgument(4));
59 args.add("targetCount", stringIndexOf.getArgument(5));
60 args.add("origFromIndex", stringIndexOf.getArgument(6));
61 char[] targetCharArray = snippetReflection.asObject(char[].class, stringIndexOf.getArgument(3).asJavaConstant());
62 args.addConst("md2", md2(targetCharArray));
63 args.addConst("cache", computeCache(targetCharArray));
64 template(args).instantiate(providers.getMetaAccess(), stringIndexOf, DEFAULT_REPLACER, args);
65 }
66 }
67
68 static int md2(char[] target) {
69 int c = target.length;
70 if (c == 0) {
71 return 0;
72 }
73 char lastChar = target[c - 1];
74 int md2 = c;
75 for (int i = 0; i < c - 1; i++) {
76 if (target[i] == lastChar) {
77 md2 = (c - 1) - i;
78 }
79 }
80 return md2;
81 }
82
83 static long computeCache(char[] s) {
84 int c = s.length;
85 int cache = 0;
86 int i;
87 for (i = 0; i < c - 1; i++) {
88 cache |= (1 << (s[i] & 63));
89 }
90 return cache;
91 }
92
93 @Snippet
94 public static int indexOfConstant(char[] source, int sourceOffset, int sourceCount,
95 @ConstantParameter char[] target, int targetOffset, int targetCount,
96 int origFromIndex, @ConstantParameter int md2, @ConstantParameter long cache) {
97 int fromIndex = origFromIndex;
98 if (fromIndex >= sourceCount) {
99 return (targetCount == 0 ? sourceCount : -1);
100 }
101 if (fromIndex < 0) {
102 fromIndex = 0;
103 }
104 if (targetCount == 0) {
105 return fromIndex;
106 }
107
108 int targetCountLess1 = targetCount - 1;
109 int sourceEnd = sourceCount - targetCountLess1;
110
111 long base = Unsafe.ARRAY_CHAR_BASE_OFFSET;
112 int lastChar = UnsafeAccess.UNSAFE.getChar(target, base + targetCountLess1 * 2);
113
114 outer_loop: for (long i = sourceOffset + fromIndex; i < sourceEnd;) {
115 int src = UnsafeAccess.UNSAFE.getChar(source, base + (i + targetCountLess1) * 2);
116 if (src == lastChar) {
117 // With random strings and a 4-character alphabet,
118 // reverse matching at this point sets up 0.8% fewer
119 // frames, but (paradoxically) makes 0.3% more probes.
120 // Since those probes are nearer the lastChar probe,
121 // there is may be a net D$ win with reverse matching.
122 // But, reversing loop inhibits unroll of inner loop
123 // for unknown reason. So, does running outer loop from
124 // (sourceOffset - targetCountLess1) to (sourceOffset + sourceCount)
125 if (targetCount <= 8) {
126 ExplodeLoopNode.explodeLoop();
127 }
128 for (long j = 0; j < targetCountLess1; j++) {
129 char sourceChar = UnsafeAccess.UNSAFE.getChar(source, base + (i + j) * 2);
130 if (UnsafeAccess.UNSAFE.getChar(target, base + (targetOffset + j) * 2) != sourceChar) {
131 if ((cache & (1 << sourceChar)) == 0) {
132 if (md2 < j + 1) {
133 i += j + 1;
134 continue outer_loop;
135 }
136 }
137 i += md2;
138 continue outer_loop;
139 }
140 }
141 return (int) (i - sourceOffset);
142 }
143 if ((cache & (1 << src)) == 0) {
144 i += targetCountLess1;
145 }
146 i++;
147 }
148 return -1;
149 }
150 }