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comparison test/compiler/6603011/Test.java @ 567:bbef4344adb2

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6800154: Add comments to long_by_long_mulhi() for better understandability Summary: This patch adds a comment pointing to the Hacker's Delight version of the algorithm plus a verbatim copy of it. Furthermore it adds inline comments. Reviewed-by: kvn, jrose
author twisti
date Fri, 13 Feb 2009 09:09:35 -0800
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children c18cbe5936b8
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566:91263420e1c6 567:bbef4344adb2
1 /*
2 * Copyright 2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 */
23
24 /**
25 * @test
26 * @bug 6603011
27 * @summary long/int division by constant
28 *
29 * @run main/othervm -Xcomp -Xbatch -XX:-Inline Test
30 */
31
32 //
33 // -XX:-Inline is essential to this test so that verification functions
34 // divi, modi, divl and modl generate "plain" divides.
35 // -Xcomp -Xbatch are also useful to ensure the full range of
36 // dividend and divisor combinations are tested
37 //
38
39 import java.net.*;
40
41 class s {
42 static int divi(int dividend, int divisor) { return dividend / divisor; }
43 static int modi(int dividend, int divisor) { return dividend % divisor; }
44 static long divl(long dividend, long divisor) { return dividend / divisor; }
45 static long modl(long dividend, long divisor) { return dividend % divisor; }
46 }
47
48 public class Test implements Runnable {
49 // Report verbose messages on failure; turn off to suppress
50 // too much output with gross numbers of failures.
51 static final boolean VERBOSE = true;
52
53 // Initailize DIVISOR so that it is final in this class.
54 static final int DIVISOR;
55 static {
56 int value = 0;
57 try {
58 value = Integer.decode(System.getProperty("divisor"));
59 } catch (Throwable e) {
60 }
61 DIVISOR = value;
62 }
63
64 // The methods of interest. We want the JIT to compile these
65 // and convert the divide into a multiply.
66 public int divbyI (int dividend) { return dividend / DIVISOR; }
67 public int modbyI (int dividend) { return dividend % DIVISOR; }
68 public long divbyL (long dividend) { return dividend / DIVISOR; }
69 public long modbyL (long dividend) { return dividend % DIVISOR; }
70
71 public int divisor() { return DIVISOR; }
72
73 public boolean checkI (int dividend) {
74 int quo = divbyI(dividend);
75 int rem = modbyI(dividend);
76 int quo0 = s.divi(dividend, divisor());
77 int rem0 = s.modi(dividend, divisor());
78
79 if (quo != quo0 || rem != rem0) {
80 if (VERBOSE) {
81 System.out.println("Computed: " + dividend + " / " + divisor() + " = " +
82 quo + ", " + dividend + " % " + divisor() + " = " + rem );
83 System.out.println("expected: " + dividend + " / " + divisor() + " = " +
84 quo0 + ", " + dividend + " % " + divisor() + " = " + rem0);
85 // Report sign of rem failure
86 if (rem != 0 && (rem ^ dividend) < 0) {
87 System.out.println(" rem & dividend have different signs");
88 }
89 // Report range of rem failure
90 if (java.lang.Math.abs(rem) >= java.lang.Math.abs(divisor())) {
91 System.out.println(" remainder out of range");
92 }
93 // Report quo/rem identity relationship failure
94 if ((quo * divisor()) + rem != dividend) {
95 System.out.println(" quotien/remainder invariant broken");
96 }
97 }
98 return false;
99 }
100 return true;
101 }
102
103 public boolean checkL (long dividend) {
104 long quo = divbyL(dividend);
105 long rem = modbyL(dividend);
106 long quo0 = s.divl(dividend, divisor());
107 long rem0 = s.modl(dividend, divisor());
108
109 if (quo != quo0 || rem != rem0) {
110 if (VERBOSE) {
111 System.out.println(" " + dividend + " / " + divisor() + " = " +
112 quo + ", " + dividend + " % " + divisor() + " = " + rem);
113 // Report sign of rem failure
114 if (rem != 0 && (rem ^ dividend) < 0) {
115 System.out.println(" rem & dividend have different signs");
116 }
117 // Report range of rem failure
118 if (java.lang.Math.abs(rem) >= java.lang.Math.abs(divisor())) {
119 System.out.println(" remainder out of range");
120 }
121 // Report quo/rem identity relationship failure
122 if ((quo * divisor()) + rem != dividend) {
123 System.out.println(" (" + quo + " * " + divisor() + ") + " + rem + " != "
124 + dividend);
125 }
126 }
127 return false;
128 }
129 return true;
130 }
131
132 public void run() {
133 // Don't try to divide by zero
134 if (divisor() == 0) return;
135
136 // Range of dividends to check. Try dividends from start to end
137 // inclusive, as well as variations on those values as shifted
138 // left.
139 int start = -1024;
140 int end = 1024;
141
142 // Test int division using a variety of dividends.
143 int wrong = 0;
144 int total = 0;
145
146 outerloop:
147 for (int i = start; i <= end; i++) {
148 for (int s = 0; s < 32; s += 4) {
149 total++;
150 int dividend = i << s;
151 if (!checkI(dividend)) {
152 wrong++;
153 // Stop on the first failure
154 // break outerloop;
155 }
156 }
157 }
158 if (wrong > 0) {
159 System.out.println("divisor " + divisor() + ": " +
160 wrong + "/" + total + " wrong int divisions");
161 }
162
163 // Test long division using a variety of dividends.
164 wrong = 0;
165 total = 0;
166
167 outerloop:
168 for (int i = start; i <= end; i++) {
169 for (int s = 0; s < 64; s += 4) {
170 total++;
171 long dividend = i << s;
172 if (!checkL(dividend)) {
173 wrong++;
174 // Stop on the first failure
175 // break outerloop;
176 }
177 }
178 }
179 if (wrong > 0) {
180 System.out.println("divisor " + divisor() + ": " +
181 wrong + "/" + total + " wrong long divisions");
182 }
183
184 }
185
186 // Reload this class with the "divisor" property set to the input parameter.
187 // This allows the JIT to see q.DIVISOR as a final constant, and change
188 // any divisions or mod operations into multiplies.
189 public static void test_divisor(int divisor,
190 URLClassLoader apploader) throws Exception {
191 System.setProperty("divisor", "" + divisor);
192 ClassLoader loader = new URLClassLoader(apploader.getURLs(),
193 apploader.getParent());
194 Class c = loader.loadClass("Test");
195 Runnable r = (Runnable)c.newInstance();
196 r.run();
197 }
198
199 public static void main(String[] args) throws Exception {
200 Class cl = Class.forName("Test");
201 URLClassLoader apploader = (URLClassLoader)cl.getClassLoader();
202
203
204 // Test every divisor between -100 and 100.
205 for (int i = -100; i <= 100; i++) {
206 test_divisor(i, apploader);
207 }
208
209 // Try a few divisors outside the typical range.
210 // The values below have been observed in rt.jar.
211 test_divisor(101, apploader);
212 test_divisor(400, apploader);
213 test_divisor(1000, apploader);
214 test_divisor(3600, apploader);
215 test_divisor(9973, apploader);
216 test_divisor(86400, apploader);
217 test_divisor(1000000, apploader);
218 }
219
220 }