8346107: Generators: testing utility for random value generation

Co-authored-by: Emanuel Peter <epeter@openjdk.org>
Reviewed-by: epeter, chagedorn

Author: 2 people

test/hotspot/jtreg/compiler/lib/generators/AnyBitsDoubleGenerator.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package compiler.lib.generators;
+
+/**
+ * Provides an any-bits double distribution random generator, i.e. the bits are uniformly sampled,
+ * thus creating any possible double value, including the multiple different NaN representations.
+ */
+final class AnyBitsDoubleGenerator extends BoundGenerator<Double> {
+    /**
+     * Create a new {@link AnyBitsDoubleGenerator}.
+     */
+    public AnyBitsDoubleGenerator(Generators g) {
+        super(g);
+    }
+
+    @Override
+    public Double next() {
+        return Double.longBitsToDouble(g.random.nextLong());
+    }
+}

test/hotspot/jtreg/compiler/lib/generators/AnyBitsFloatGenerator.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package compiler.lib.generators;
+
+/**
+ * Provides an any-bits float distribution random generator, i.e. the bits are uniformly sampled,
+ * thus creating any possible float value, including the multiple different NaN representations.
+ */
+final class AnyBitsFloatGenerator extends BoundGenerator<Float> {
+
+    /**
+     * Creates a new {@link AnyBitsFloatGenerator}.
+     */
+    public AnyBitsFloatGenerator(Generators g) {
+        super(g);
+    }
+
+    @Override
+    public Float next() {
+        return Float.intBitsToFloat(g.random.nextInt());
+    }
+}

test/hotspot/jtreg/compiler/lib/generators/BoundGenerator.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package compiler.lib.generators;
+
+/**
+ * This is a common superclass for all generators that maintain a reference to the Generators object that created them.
+ * This allows internally creating other generators or using the {@link RandomnessSource} provided in
+ * {@link Generators#random}.
+ */
+abstract class BoundGenerator<T> implements Generator<T> {
+    Generators g;
+
+    BoundGenerator(Generators g) {
+        this.g = g;
+    }
+}

test/hotspot/jtreg/compiler/lib/generators/EmptyGeneratorException.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package compiler.lib.generators;
+
+/**
+ * An EmptyGeneratorException is thrown if a generator configuration is requested that would result in an empty
+ * set of values. For example, bounds such as [1, 0] cause an EmptyGeneratorException. Another example would be
+ * restricting a uniform integer generator over the range [0, 1] to [10, 11].
+ */
+public class EmptyGeneratorException extends RuntimeException {
+    public EmptyGeneratorException() {}
+}

test/hotspot/jtreg/compiler/lib/generators/Generator.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2024, 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package compiler.lib.generators;
+
+/**
+ * A stream of values according to a specific distribution.
+ */
+public interface Generator<T> {
+    /**
+     * Returns the next value from the stream.
+     */
+    T next();
+}