long RandomGenerator.nextLong(long)

Author: Gaming32

RuntimeDep/src/main/java/net/raphimc/javadowngrader/runtime/jdk/internal/util/random/RandomSupport.java

@@ -0,0 +1,45 @@
+/*
+ * This file is part of JavaDowngrader - https://github.com/RaphiMC/JavaDowngrader
+ * Copyright (C) 2023 RK_01/RaphiMC and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package net.raphimc.javadowngrader.runtime.jdk.internal.util.random;
+
+import java.util.Random;
+
+public class RandomSupport {
+    public static final String BAD_BOUND = "bound must be positive";
+
+    public static void checkBound(long bound) {
+        if (bound <= 0) {
+            throw new IllegalArgumentException(BAD_BOUND);
+        }
+    }
+
+    public static long boundedNextLong(Random rng, long bound) {
+        final long m = bound - 1;
+        long r = rng.nextLong();
+        if ((bound & m) == 0L) {
+            r &= m;
+        } else {
+            //noinspection StatementWithEmptyBody
+            for (long u = r >>> 1;
+                 u + m - (r = u % bound) < 0L;
+                 u = rng.nextLong() >>> 1)
+                ;
+        }
+        return r;
+    }
+}

src/main/java/net/raphimc/javadowngrader/transformer/j16/Java17ToJava16.java

@@ -18,12 +18,23 @@
 package net.raphimc.javadowngrader.transformer.j16;
 
 import net.raphimc.javadowngrader.transformer.DowngradingTransformer;
+import net.raphimc.javadowngrader.transformer.j16.methodcallreplacer.RandomGeneratorNextLongMCR;
 import org.objectweb.asm.Opcodes;
 
 public class Java17ToJava16 extends DowngradingTransformer {
+    public static final String RANDOM_SUPPORT = "net/raphimc/javadowngrader/runtime/jdk/internal/util/random/RandomSupport";
 
     public Java17ToJava16() {
         super(Opcodes.V17, Opcodes.V16);
+
+        final String[] randomClasses = {
+            "java/util/Random",
+            "java/security/SecureRandom",
+            "java/util/concurrent/ThreadLocalRandom"
+        };
+        for (final String clazz : randomClasses) {
+            addMethodCallReplacer(Opcodes.INVOKEVIRTUAL, clazz, "nextLong", "(J)J", new RandomGeneratorNextLongMCR());
+        }
     }
 
 }

src/main/java/net/raphimc/javadowngrader/transformer/j16/methodcallreplacer/RandomGeneratorNextLongMCR.java

@@ -0,0 +1,41 @@
+/*
+ * This file is part of JavaDowngrader - https://github.com/RaphiMC/JavaDowngrader
+ * Copyright (C) 2023 RK_01/RaphiMC and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package net.raphimc.javadowngrader.transformer.j16.methodcallreplacer;
+
+import net.raphimc.javadowngrader.transformer.MethodCallReplacer;
+import org.objectweb.asm.Opcodes;
+import org.objectweb.asm.tree.*;
+
+import static net.raphimc.javadowngrader.transformer.j16.Java17ToJava16.RANDOM_SUPPORT;
+
+public class RandomGeneratorNextLongMCR implements MethodCallReplacer {
+    @Override
+    public InsnList getReplacement(ClassNode classNode, MethodNode method, String originalName, String originalDesc) {
+        final InsnList replacement = new InsnList();
+
+        // Random long1 long2
+        replacement.add(new InsnNode(Opcodes.DUP2));
+        // Random long1 long2 long1 long2
+        replacement.add(new MethodInsnNode(Opcodes.INVOKESTATIC, RANDOM_SUPPORT, "checkBound", "(J)V"));
+        // Random long1 long2
+        replacement.add(new MethodInsnNode(Opcodes.INVOKESTATIC, RANDOM_SUPPORT, "boundedNextLong", "(Ljava/util/Random;J)J"));
+        // long1 long2
+
+        return replacement;
+    }
+}

src/main/java/net/raphimc/javadowngrader/transformer/j8/methodcallreplacer/BufferMCR.java

@@ -35,7 +35,7 @@ public InsnList getReplacement(ClassNode classNode, MethodNode methodNode, Strin
         final String newDesc = Type.getMethodDescriptor(Type.getObjectType("java/nio/Buffer"), Type.getArgumentTypes(originalDesc));
 
         final InsnList replacement = new InsnList();
-        replacement.add(new MethodInsnNode(Opcodes.INVOKEVIRTUAL, "java/nio/Buffer", originalName, newDesc));
+        replacement.add(new MethodInsnNode(Opcodes.INVOKEVIRTUAL, bufferClass, originalName, newDesc));
         replacement.add(new TypeInsnNode(Opcodes.CHECKCAST, this.bufferClass));
         return replacement;
     }