7902929: JMH generators fail for benchmark in unnamed package

Reviewed-by: shade

jmh-core-ct/src/test/java/UnnamedPackageTest.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2021, 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+
+import org.junit.Test;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.ct.CompileTest;
+
+public class UnnamedPackageTest {
+    @Benchmark
+    public void test() {
+    }
+
+    @Test
+    public void compileTest() {
+        CompileTest.assertFail(getClass(), "Benchmark class should have package other than default.");
+    }
+}

jmh-generator-asm/src/main/java/org/openjdk/jmh/generators/asm/ASMClassInfo.java

@@ -79,11 +79,24 @@ public void visit(int version, int access, String name, String signature, String
         this.superName = superName;
         this.idName = name;
         this.access = access;
-        qualifiedName = name.replace("/", ".");
-        packageName = qualifiedName.substring(0, qualifiedName.lastIndexOf("."));
-        origQualifiedName = qualifiedName;
-        qualifiedName = qualifiedName.replace('$', '.');
-        this.name = qualifiedName.substring(qualifiedName.lastIndexOf(".") + 1);
+        this.qualifiedName = name.replace("/", ".");
+
+        int dotIndex = qualifiedName.lastIndexOf(".");
+        if (dotIndex != -1) {
+            packageName = qualifiedName.substring(0, dotIndex);
+        } else {
+            packageName = "";
+        }
+
+        this.origQualifiedName = qualifiedName;
+        this.qualifiedName = qualifiedName.replace('$', '.');
+
+        dotIndex = qualifiedName.lastIndexOf(".");
+        if (dotIndex != -1) {
+            this.name = qualifiedName.substring(dotIndex + 1);
+        } else {
+            this.name = qualifiedName;
+        }
     }
 
     @Override

jmh-generator-reflection/src/main/java/org/openjdk/jmh/generators/reflection/RFClassInfo.java

@@ -46,9 +46,9 @@ public RFClassInfo(Class<?> klass) {
     @Override
     public String getPackageName() {
         if (klass.getDeclaringClass() != null) {
-            return klass.getDeclaringClass().getPackage().getName();
+            return nameOf(klass.getDeclaringClass().getPackage());
         } else {
-            return klass.getPackage().getName();
+            return nameOf(klass.getPackage());
         }
     }
 
@@ -171,4 +171,8 @@ public Collection<String> getEnumConstants() {
     public String toString() {
         return getQualifiedName();
     }
+
+    private String nameOf(Package pack) {
+        return pack == null ? "" : pack.getName();
+    }
 }