8167194: [JVMCI] no reliable mechanism for querying JVMCI system properties

Reviewed-by: kvn

hotspot/src/jdk.vm.ci/share/classes/jdk.vm.ci.hotspot/src/jdk/vm/ci/hotspot/HotSpotJVMCIRuntime.java

@@ -90,14 +90,17 @@ public final class HotSpotJVMCIRuntime implements HotSpotJVMCIRuntimeProvider {
      * A list of all supported JVMCI options.
      */
     public enum Option {
+        // @formatter:off
         Compiler(String.class, null, "Selects the system compiler."),
         // Note: The following one is not used (see InitTimer.ENABLED). It is added here
-        // so that -Djvmci.PrintFlags=true shows the option.
+        // so that -XX:+JVMCIPrintProperties shows the option.
-        InitTimer(boolean.class, false, "Specifies if initialization timing is enabled."),
+        InitTimer(Boolean.class, false, "Specifies if initialization timing is enabled."),
-        PrintConfig(boolean.class, false, "Prints VM configuration available via JVMCI and exits."),
+        PrintConfig(Boolean.class, false, "Prints VM configuration available via JVMCI."),
-        PrintFlags(boolean.class, false, "Prints all JVMCI flags and exits."),
+        TraceMethodDataFilter(String.class, null,
-        ShowFlags(boolean.class, false, "Prints all JVMCI flags and continues."),
+                        "Enables tracing of profiling info when read by JVMCI.",
-        TraceMethodDataFilter(String.class, null, "");
+                        "Empty value: trace all methods",
+                        "Non-empty value: trace methods whose fully qualified name contains the value.");
+        // @formatter:on
 
         /**
          * The prefix for system properties that are JVMCI options.
@@ -113,25 +116,25 @@ public final class HotSpotJVMCIRuntime implements HotSpotJVMCIRuntimeProvider {
         private Object value;
         private final Object defaultValue;
         private boolean isDefault;
-        private final String help;
+        private final String[] helpLines;
 
-        Option(Class<?> type, Object defaultValue, String help) {
+        Option(Class<?> type, Object defaultValue, String... helpLines) {
             assert Character.isUpperCase(name().charAt(0)) : "Option name must start with upper-case letter: " + name();
             this.type = type;
             this.value = UNINITIALIZED;
             this.defaultValue = defaultValue;
-            this.help = help;
+            this.helpLines = helpLines;
         }
 
         @SuppressFBWarnings(value = "ES_COMPARING_STRINGS_WITH_EQ", justification = "sentinel must be String since it's a static final in an enum")
         private Object getValue() {
             if (value == UNINITIALIZED) {
-                String propertyValue = VM.getSavedProperty(JVMCI_OPTION_PROPERTY_PREFIX + name());
+                String propertyValue = VM.getSavedProperty(getPropertyName());
                 if (propertyValue == null) {
                     this.value = defaultValue;
                     this.isDefault = true;
                 } else {
-                    if (type == boolean.class) {
+                    if (type == Boolean.class) {
                         this.value = Boolean.parseBoolean(propertyValue);
                     } else if (type == String.class) {
                         this.value = propertyValue;
@@ -146,6 +149,13 @@ public final class HotSpotJVMCIRuntime implements HotSpotJVMCIRuntimeProvider {
             return value;
         }
 
+        /**
+         * Gets the name of system property from which this option gets its value.
+         */
+        public String getPropertyName() {
+            return JVMCI_OPTION_PROPERTY_PREFIX + name();
+        }
+
         /**
          * Returns the option's value as boolean.
          *
@@ -165,16 +175,31 @@ public final class HotSpotJVMCIRuntime implements HotSpotJVMCIRuntimeProvider {
         }
 
         /**
-         * Prints all option flags to {@code out}.
+         * Prints a description of the properties used to configure shared JVMCI code.
          *
          * @param out stream to print to
          */
-        public static void printFlags(PrintStream out) {
+        public static void printProperties(PrintStream out) {
-            out.println("[List of JVMCI options]");
+            out.println("[JVMCI properties]");
-            for (Option option : values()) {
+            int typeWidth = 0;
+            int nameWidth = 0;
+            Option[] values = values();
+            for (Option option : values) {
+                typeWidth = Math.max(typeWidth, option.type.getSimpleName().length());
+                nameWidth = Math.max(nameWidth, option.getPropertyName().length());
+            }
+            for (Option option : values) {
                 Object value = option.getValue();
-                String assign = option.isDefault ? ":=" : " =";
+                if (value instanceof String) {
-                out.printf("%9s %-40s %s %-14s %s%n", option.type.getSimpleName(), option, assign, value, option.help);
+                    value = '"' + String.valueOf(value) + '"';
+                }
+                String assign = option.isDefault ? " =" : ":=";
+                String format = "%" + (typeWidth + 1) + "s %-" + (nameWidth + 1) + "s %s %s%n";
+                out.printf(format, option.type.getSimpleName(), option.getPropertyName(), assign, value);
+                String helpFormat = "%" + (typeWidth + 1) + "s %s%n";
+                for (String line : option.helpLines) {
+                    out.printf(helpFormat, "", line);
+                }
             }
         }
     }
@@ -239,7 +264,6 @@ public final class HotSpotJVMCIRuntime implements HotSpotJVMCIRuntimeProvider {
     @SuppressWarnings("unused") private final String[] trivialPrefixes;
 
     @SuppressWarnings("try")
-    @SuppressFBWarnings(value = "DM_EXIT", justification = "PrintFlags is meant to exit the VM")
     private HotSpotJVMCIRuntime() {
         compilerToVm = new CompilerToVM();
 
@@ -261,20 +285,6 @@ public final class HotSpotJVMCIRuntime implements HotSpotJVMCIRuntimeProvider {
 
         metaAccessContext = new HotSpotJVMCIMetaAccessContext();
 
-        boolean printFlags = Option.PrintFlags.getBoolean();
-        boolean showFlags = Option.ShowFlags.getBoolean();
-        if (printFlags || showFlags) {
-            Option.printFlags(System.out);
-            if (printFlags) {
-                System.exit(0);
-            }
-        }
-
-        if (Option.PrintConfig.getBoolean()) {
-            printConfig(configStore, compilerToVm);
-            System.exit(0);
-        }
-
         compilerFactory = HotSpotJVMCICompilerConfig.getCompilerFactory();
         if (compilerFactory instanceof HotSpotJVMCICompilerFactory) {
             hsCompilerFactory = (HotSpotJVMCICompilerFactory) compilerFactory;
@@ -298,6 +308,16 @@ public final class HotSpotJVMCIRuntime implements HotSpotJVMCIRuntimeProvider {
             trivialPrefixes = null;
             compilationLevelAdjustment = config.compLevelAdjustmentNone;
         }
+
+        if (config.getFlag("JVMCIPrintProperties", Boolean.class)) {
+            PrintStream out = new PrintStream(getLogStream());
+            Option.printProperties(out);
+            compilerFactory.printProperties(out);
+        }
+
+        if (Option.PrintConfig.getBoolean()) {
+            printConfig(configStore, compilerToVm);
+        }
     }
 
     private JVMCIBackend registerBackend(JVMCIBackend backend) {

hotspot/src/jdk.vm.ci/share/classes/jdk.vm.ci.runtime/src/jdk/vm/ci/runtime/services/JVMCICompilerFactory.java

@@ -22,6 +22,8 @@
  */
 package jdk.vm.ci.runtime.services;
 
+import java.io.PrintStream;
+
 import jdk.vm.ci.runtime.JVMCICompiler;
 import jdk.vm.ci.runtime.JVMCIRuntime;
 import jdk.vm.ci.services.JVMCIPermission;
@@ -70,4 +72,12 @@ public abstract class JVMCICompilerFactory {
      * Create a new instance of a {@link JVMCICompiler}.
      */
     public abstract JVMCICompiler createCompiler(JVMCIRuntime runtime);
+
+    /**
+     * Prints a description of the properties used to configure this compiler.
+     *
+     * @param out where to print the message
+     */
+    public void printProperties(PrintStream out) {
+    }
 }

hotspot/src/share/vm/jvmci/jvmci_globals.cpp

@@ -85,6 +85,7 @@ bool JVMCIGlobals::check_jvmci_flags_are_consistent() {
   CHECK_NOT_SET(JVMCIUseFastLocking,          EnableJVMCI)
   CHECK_NOT_SET(JVMCINMethodSizeLimit,        EnableJVMCI)
   CHECK_NOT_SET(MethodProfileWidth,           EnableJVMCI)
+  CHECK_NOT_SET(JVMCIPrintProperties,         EnableJVMCI)
   CHECK_NOT_SET(TraceUncollectedSpeculations, EnableJVMCI)
 
 #ifndef PRODUCT

hotspot/src/share/vm/jvmci/jvmci_globals.hpp

@@ -49,6 +49,9 @@
   experimental(bool, UseJVMCICompiler, false,                               \
           "Use JVMCI as the default compiler")                              \
                                                                             \
+  experimental(bool, JVMCIPrintProperties, false,                           \
+          "Prints properties used by the JVMCI compiler")                   \
+                                                                            \
   experimental(bool, BootstrapJVMCI, false,                                 \
           "Bootstrap JVMCI before running Java main method")                \
                                                                             \

hotspot/src/share/vm/runtime/thread.cpp

@@ -3768,11 +3768,22 @@ jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) {
   SystemDictionary::compute_java_system_loader(CHECK_(JNI_ERR));
 
 #if INCLUDE_JVMCI
-  if (EnableJVMCI && UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation)) {
+  if (EnableJVMCI) {
+    // Initialize JVMCI eagerly if JVMCIPrintProperties is enabled.
+    // The JVMCI Java initialization code will read this flag and
+    // do the printing if it's set.
+    bool init = JVMCIPrintProperties;
+
+    if (!init) {
       // 8145270: Force initialization of JVMCI runtime otherwise requests for blocking
       // compilations via JVMCI will not actually block until JVMCI is initialized.
+      init = UseJVMCICompiler && (!UseInterpreter || !BackgroundCompilation);
+    }
+
+    if (init) {
       JVMCIRuntime::force_initialization(CHECK_JNI_ERR);
     }
+  }
 #endif
 
   // Always call even when there are not JVMTI environments yet, since environments

hotspot/test/compiler/jvmci/TestJVMCIPrintProperties.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2015, 2016, 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.
+ */
+
+/*
+ * @test TestBasicLogOutput
+ * @summary Ensure -XX:-JVMCIPrintProperties can be enabled and successfully prints expected output to stdout.
+ * @requires (vm.simpleArch == "x64" | vm.simpleArch == "sparcv9" | vm.simpleArch == "aarch64")
+ * @library /test/lib
+ */
+
+import jdk.test.lib.process.ProcessTools;
+import jdk.test.lib.process.OutputAnalyzer;
+
+public class TestJVMCIPrintProperties {
+
+    public static void main(String[] args) throws Exception {
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
+            "-XX:+UnlockExperimentalVMOptions",
+            "-XX:+EnableJVMCI",
+            "-XX:+JVMCIPrintProperties",
+            "-version");
+        OutputAnalyzer output = new OutputAnalyzer(pb.start());
+        output.shouldContain("[JVMCI properties]"); // expected message
+        output.shouldContain("String jvmci.Compiler"); // expected message
+        output.shouldContain("Boolean jvmci.InitTimer"); // expected message
+        output.shouldContain("Boolean jvmci.PrintConfig"); // expected message
+        output.shouldContain("String jvmci.TraceMethodDataFilter"); // expected message
+        output.shouldHaveExitValue(0);
+    }
+}