1 /*
   2  * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 package jdk.vm.ci.services;
  24 
  25 import java.util.Map;
  26 import java.util.Set;
  27 
  28 import jdk.internal.misc.VM;
  29 
  30 /**
  31  * Provides utilities needed by JVMCI clients.
  32  */
  33 public final class Services {
  34 
  35     // This class must be compilable and executable on JDK 8 since it's used in annotation
  36     // processors while building JDK 9 so use of API added in JDK 9 is made via reflection.
  37 
  38     /**
  39      * Guards code that should be run when building a native image but should be excluded from
  40      * (being compiled into) the image. Such code must be directly guarded by an {@code if}
  41      * statement on this field - the guard cannot be behind a method call.
  42      */
  43     public static final boolean IS_BUILDING_NATIVE_IMAGE;
  44 
  45     /**
  46      * Guards code that should only be run in native image. Such code must be directly guarded by an
  47      * {@code if} statement on this field - the guard cannot be behind a method call.
  48      *
  49      * The value of this field seen during analysis and compilation of an SVM image must be
  50      * {@code true}.
  51      */
  52     public static final boolean IS_IN_NATIVE_IMAGE;
  53 
  54     static {
  55         /*
  56          * Prevents javac from constant folding use of this field. It is set to true in the SVM
  57          * image via substitution during image building.
  58          */
  59         IS_IN_NATIVE_IMAGE = false;
  60         IS_BUILDING_NATIVE_IMAGE = false;
  61     }
  62 
  63     private Services() {
  64     }
  65 
  66     static final Map<String, String> SAVED_PROPERTIES = VM.getSavedProperties();
  67     static final boolean JVMCI_ENABLED = Boolean.parseBoolean(SAVED_PROPERTIES.get("jdk.internal.vm.ci.enabled"));
  68 
  69     /**
  70      * Checks that JVMCI is enabled in the VM and throws an error if it isn't.
  71      */
  72     static void checkJVMCIEnabled() {
  73         if (!JVMCI_ENABLED) {
  74             throw new Error("The EnableJVMCI VM option must be true (i.e., -XX:+EnableJVMCI) to use JVMCI");
  75         }
  76     }
  77 
  78     /**
  79      * Gets an unmodifiable copy of the system properties saved when {@link System} is initialized.
  80      */
  81     public static Map<String, String> getSavedProperties() {
  82         checkJVMCIEnabled();
  83         SecurityManager sm = System.getSecurityManager();
  84         if (sm != null) {
  85             sm.checkPermission(new JVMCIPermission());
  86         }
  87         return SAVED_PROPERTIES;
  88     }
  89 
  90     /**
  91      * Causes the JVMCI subsystem to be initialized if it isn't already initialized.
  92      */
  93     public static void initializeJVMCI() {
  94         checkJVMCIEnabled();
  95         try {
  96             Class.forName("jdk.vm.ci.runtime.JVMCI");
  97         } catch (ClassNotFoundException e) {
  98             throw new InternalError(e);
  99         }
 100     }
 101 
 102     /**
 103      * Opens all JVMCI packages to {@code otherModule}.
 104      */
 105     static void openJVMCITo(Module otherModule) {
 106         Module jvmci = Services.class.getModule();
 107         if (jvmci != otherModule) {
 108             Set<String> packages = jvmci.getPackages();
 109             for (String pkg : packages) {
 110                 boolean opened = jvmci.isOpen(pkg, otherModule);
 111                 if (!opened) {
 112                     jvmci.addOpens(pkg, otherModule);
 113                 }
 114             }
 115         }
 116     }
 117 }