8240567: MethodTooLargeException thrown while creating a jlink image

src/jdk.jlink/share/classes/jdk/tools/jlink/internal/plugins/SystemModulesPlugin.java

@@ -118,7 +118,7 @@ public final class SystemModulesPlugin extends AbstractPlugin {
             ClassDesc.ofInternalName("jdk/internal/module/SystemModules");
     private static final ClassDesc CD_SYSTEM_MODULES_MAP =
             ClassDesc.ofInternalName(SYSTEM_MODULES_MAP_CLASSNAME);
-    private boolean enabled;
+    private final boolean enabled;
 
     public SystemModulesPlugin() {
         super("system-modules");
@@ -666,23 +666,91 @@ private void genIncubatorModules(ClassBuilder clb) {
          * Generate bytecode for moduleDescriptors method
          */
         private void genModuleDescriptorsMethod(ClassBuilder clb) {
+            if (moduleInfos.size() <= 71) {
+                clb.withMethodBody(
+                        "moduleDescriptors",
+                        MethodTypeDesc.of(CD_MODULE_DESCRIPTOR.arrayType()),
+                        ACC_PUBLIC,
+                        cob -> {
+                            cob.constantInstruction(moduleInfos.size())
+                               .anewarray(CD_MODULE_DESCRIPTOR)
+                               .astore(MD_VAR);
+                            for (int index = 0; index < moduleInfos.size(); index++) {
+                                ModuleInfo minfo = moduleInfos.get(index);
+                                new ModuleDescriptorBuilder(cob,
+                                        minfo.descriptor(),
+                                        minfo.packages(),
+                                        index).build();
+                            }
+                            cob.aload(MD_VAR)
+                               .areturn();
+                        });
+                return;
+            }
+
+            // split up module infos in "consumable" packages
+            List<List<ModuleInfo>> splitModuleInfos = new ArrayList<>();
+            List<ModuleInfo> currentModuleInfos = null;
+            for (int index = 0; index < moduleInfos.size(); index++) {
+                // The method is "manually split" based on the heuristics that 90 ModuleDescriptors are smaller than 64kb
+                // The number 10 is chosen "randomly" to be below the 64kb limit of a method
+                if (index % 10 == 0) {
+                    // Prepare new list
+                    currentModuleInfos = new ArrayList<>();
+                    splitModuleInfos.add(currentModuleInfos);
+                }
+                currentModuleInfos.add(moduleInfos.get(index));
+            }
+            // generate all helper methods
+            final String helperMethodNamePrefix = "moduleDescriptorsSub";
+            final int[] globalCount = {0};
+            for (final int[] index = {0}; index[0] < splitModuleInfos.size(); index[0]++) {
+                clb.withMethodBody(
+                        helperMethodNamePrefix + index[0],
+                        MethodTypeDesc.of(CD_void, CD_MODULE_DESCRIPTOR.arrayType()),
+                        ACC_PUBLIC,
+                        cob -> {
+                            List<ModuleInfo> moduleInfosPackage = splitModuleInfos.get(index[0]);
+                            if (index[0] > 0) {
+                                // call last helper method
+                                cob.aload(0)
+                                   .aload(MD_VAR) // load first parameter, which is MD_VAR
+                                   .invokevirtual(
+                                           this.classDesc,
+                                           helperMethodNamePrefix + (index[0] - 1),
+                                           MethodTypeDesc.of(CD_void, CD_MODULE_DESCRIPTOR.arrayType())
+                                   );
+                            }
+                            for (int j = 0; j < moduleInfosPackage.size(); j++) {
+                                ModuleInfo minfo = moduleInfosPackage.get(j);
+                                // executed after the call, thus it is OK to overwrite index 0 (BUILDER_VAR)
+                                new ModuleDescriptorBuilder(cob,
+                                        minfo.descriptor(),
+                                        minfo.packages(),
+                                        globalCount[0]).build();
+                                globalCount[0]++;
+                            }
+                            cob.return_();
+                        });
+            }
+
+            // generate call to last helper method
             clb.withMethodBody(
                     "moduleDescriptors",
                     MethodTypeDesc.of(CD_MODULE_DESCRIPTOR.arrayType()),
                     ACC_PUBLIC,
                     cob -> {
                         cob.constantInstruction(moduleInfos.size())
                            .anewarray(CD_MODULE_DESCRIPTOR)
-                           .astore(MD_VAR);
-
-                        for (int index = 0; index < moduleInfos.size(); index++) {
-                            ModuleInfo minfo = moduleInfos.get(index);
-                            new ModuleDescriptorBuilder(cob,
-                                                        minfo.descriptor(),
-                                                        minfo.packages(),
-                                                        index).build();
-                        }
-                        cob.aload(MD_VAR)
+                           .astore(MD_VAR)
+                           .aload(MD_VAR) // storing for the return at the end
+                           .aload(0)
+                           .aload(MD_VAR)
+                           .invokevirtual(
+                                   this.classDesc,
+                                   helperMethodNamePrefix + (splitModuleInfos.size() - 1),
+                                   MethodTypeDesc.of(CD_void, CD_MODULE_DESCRIPTOR.arrayType())
+                           )
                            .areturn();
                     });
         }

test/jdk/tools/jlink/JLink100Modules.java

@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2022, 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.
+ */
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.StringJoiner;
+import java.util.spi.ToolProvider;
+import tests.JImageGenerator;
+import tests.JImageGenerator.JLinkTask;
+/*
+ * @test
+ * @summary Make sure that 100 modules can be linked using jlink.
+ * @bug 8240567
+ * @library ../lib
+ * @modules java.base/jdk.internal.jimage
+ *          jdk.jdeps/com.sun.tools.classfile
+ *          jdk.jlink/jdk.tools.jlink.internal
+ *          jdk.jlink/jdk.tools.jlink.plugin
+ *          jdk.jlink/jdk.tools.jmod
+ *          jdk.jlink/jdk.tools.jimage
+ *          jdk.compiler
+ * @build tests.*
+ * @run main/othervm -verbose:gc -Xmx1g -Xlog:init=debug -XX:+UnlockDiagnosticVMOptions -XX:+BytecodeVerificationLocal JLink100Modules
+ */
+public class JLink100Modules {
+    private static final ToolProvider JAVAC_TOOL = ToolProvider.findFirst("javac")
+                                                               .orElseThrow(() -> new RuntimeException("javac tool not found"));
+    private static final ToolProvider JLINK_TOOL = ToolProvider.findFirst("jlink")
+                                                               .orElseThrow(() -> new RuntimeException("jlink tool not found"));
+
+    static void report(String command, String[] args) {
+        System.out.println(command + " " + String.join(" ", Arrays.asList(args)));
+    }
+
+    static void javac(String[] args) {
+        report("javac", args);
+        JAVAC_TOOL.run(System.out, System.err, args);
+    }
+
+    static void jlink(String[] args) {
+        report("jlink", args);
+        JLINK_TOOL.run(System.out, System.err, args);
+    }
+
+    public static void main(String[] args) throws Exception {
+        Path src = Paths.get("bug8240567");
+
+        StringJoiner mainModuleInfoContent = new StringJoiner(";\n  requires ", "module bug8240567x {\n  requires ", "\n;}");
+
+        // create 100 modules. With this naming schema up to 130 seem to work
+        for (int i = 0; i < 150; i++) {
+            String name = "module" + i + "x";
+            Path moduleDir = Files.createDirectories(src.resolve(name));
+
+            StringBuilder builder = new StringBuilder("module ");
+            builder.append(name).append(" {");
+
+            for (int j = 0; j < i; j++) {
+                builder.append("requires module" + j + "x;");
+            }
+            builder.append("}\n");
+            Files.writeString(moduleDir.resolve("module-info.java"), builder.toString());
+            mainModuleInfoContent.add(name);
+        }
+
+        // create module reading the generated modules
+        Path mainModulePath = src.resolve("bug8240567x");
+        Files.createDirectories(mainModulePath);
+        Path mainModuleInfo = mainModulePath.resolve("module-info.java");
+        Files.writeString(mainModuleInfo, mainModuleInfoContent.toString());
+
+        Path mainClassDir = mainModulePath.resolve("testpackage");
+        Files.createDirectories(mainClassDir);
+
+        Files.writeString(mainClassDir.resolve("JLink100ModulesTest.java"), """
+                package testpackage;
+
+                public class JLink100ModulesTest {
+                    public static void main(String[] args) throws Exception {
+                        System.out.println("JLink100ModulesTest started.");
+                    }
+                }
+                """);
+
+        String out = src.resolve("out").toString();
+
+        javac(new String[] {
+                "-d", out,
+                "--module-source-path", src.toString(),
+                "--module", "bug8240567x"
+        });
+
+        JImageGenerator.getJLinkTask()
+                .modulePath(out)
+                .output(src.resolve("out-jlink"))
+                .addMods("bug8240567x")
+                .call().assertSuccess();
+    }
+}