Start the compiler with compact object headers

src/main/kotlin/global/InstallationManager.kt

@@ -24,6 +24,7 @@ object InstallationManager {
     private const val LANGUAGE_AGENT_DOC_ENTRY = "agent-docs/WURST_LANGUAGE.md"
     private const val GRILL_JAR_NAME = "grill.jar"
     private const val LEGACY_GRILL_JAR_NAME = "WurstSetup.jar"
+    private const val COMPACT_OBJECT_HEADERS = "-XX:+UseCompactObjectHeaders"
 
     val installDir: Path get() = configuredInstallDir()
     val compilerDir: Path get() = installDir.resolve("wurst-compiler")
@@ -193,7 +194,9 @@ object InstallationManager {
     fun compilerLaunchCommand(vararg extraArgs: String): Array<String> {
         val compiler = detectCompilerJar() ?: compilerJar
         val java = bundledJavaCommand()
-        return arrayOf(java, "-jar", compiler.toAbsolutePath().toString(), *extraArgs)
+        // The compiler holds millions of small objects, and the runtime of the distribution carries the base class
+        // data sharing archive for compact object headers, which a JVM uses only in the header mode it runs with.
+        return arrayOf(java, COMPACT_OBJECT_HEADERS, "-jar", compiler.toAbsolutePath().toString(), *extraArgs)
     }
 
     private fun bundledJavaCommand(): String {

src/test/kotlin/InstallationTests.kt

@@ -19,6 +19,38 @@ class InstallationTests {
 		assert(InstallationManager.status != InstallationManager.InstallationStatus.NOT_INSTALLED)
 	}
 
+	@Test(priority = 8)
+	fun testCompilerLaunchCommandUsesCompactObjectHeaders() {
+		val previousInstallDir = System.getProperty("wurst.install.dir")
+		val installDir = Files.createTempDirectory("wurst-setup-launch")
+		try {
+			System.setProperty("wurst.install.dir", installDir.toString())
+			Files.createDirectories(InstallationManager.compilerDir)
+			JarOutputStream(Files.newOutputStream(InstallationManager.compilerJar)).use { }
+			Files.createDirectories(InstallationManager.bundledJava.parent)
+			Files.writeString(InstallationManager.bundledJava, "")
+			InstallationManager.bundledJava.toFile().setExecutable(true)
+
+			// the compiler holds millions of small objects; the runtime of the distribution has the base archive for this mode
+			Assert.assertEquals(
+				InstallationManager.compilerLaunchCommand("-build").toList(),
+				listOf(
+					InstallationManager.bundledJava.toAbsolutePath().toString(),
+					"-XX:+UseCompactObjectHeaders",
+					"-jar",
+					InstallationManager.compilerJar.toAbsolutePath().toString(),
+					"-build"
+				)
+			)
+		} finally {
+			if (previousInstallDir == null) {
+				System.clearProperty("wurst.install.dir")
+			} else {
+				System.setProperty("wurst.install.dir", previousInstallDir)
+			}
+		}
+	}
+
 	@Test(priority = 8)
 	fun testCompilerWithoutAgentDocsRemovesStaleLanguageDoc() {
 		val previousInstallDir = System.getProperty("wurst.install.dir")