1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   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
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  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 }