Introduce VMAccess API

The `VMAccess` API can be used to retrieve JVMCI and Graal compiler
providers that reflect the state of a JVM. `VMAccess.Builder` can be
used to create such a JVM based on a class path, module path etc.

This commit adds 2 implementations of `VMAccess.Builder` that can be
looked up via service loaders:
* A "host" VMAccess which reflects on the host JVM similar to how the
  native-image builder works today.
* A "espresso-context" VMAccess which creates and reflects on an
  espresso context.

The implementation of the espresso context vm access is partial and is
done as a refactoring of Espresso's existing "internal" JVMCI
implementation.
* On the JVMCI side, the main espresso JVMCI implementation classes are
  turned into abstract classes that are extended by 2 sublasses: one for
  internal JVMCI which works as before via substitutions of native
  methods; and one for the new external JVMCI which is implemented via
  polyglot interop.
* In espresso, some common code is moved from the existing substitution
  classes to some *Util classes. External JVMCI works over interop so
  some exisiting classes now implement interop and a number of new
  interop wrappers to util objects are introduced.

Author: gilles-duboscq

compiler/mx.compiler/suite.py

@@ -321,6 +321,53 @@
       "workingSets" : "Graal,HotSpot",
     },
 
+    "com.oracle.graal.vmaccess": {
+      "subDir": "src",
+      "sourceDirs": ["src"],
+      "dependencies": [
+        "jdk.graal.compiler",
+      ],
+      "requires": [
+        "jdk.internal.vm.ci",
+      ],
+      "requiresConcealed": {
+        "jdk.internal.vm.ci": [
+          "jdk.vm.ci.meta",
+          "jdk.vm.ci.code",
+        ],
+        "java.base": [
+          "jdk.internal.module",
+        ],
+      },
+      "javaCompliance": "21+",
+      "checkstyle" : "jdk.graal.compiler",
+    },
+
+    "com.oracle.graal.hostvmaccess": {
+      "subDir": "src",
+      "sourceDirs": ["src"],
+      "dependencies": [
+        "com.oracle.graal.vmaccess",
+      ],
+      "requires": [
+        "jdk.internal.vm.ci",
+      ],
+      "requiresConcealed": {
+        "java.base": [
+          "jdk.internal.access",
+          "jdk.internal.loader",
+          "jdk.internal.module",
+        ],
+        "jdk.internal.vm.ci": [
+          "jdk.vm.ci.meta",
+          "jdk.vm.ci.runtime",
+          "jdk.vm.ci.code",
+        ],
+      },
+      "javaCompliance": "21+",
+      "checkstyle" : "jdk.graal.compiler",
+    },
+
     "jdk.graal.compiler.microbenchmarks" : {
       "subDir" : "src",
       "sourceDirs" : ["src"],
@@ -636,6 +683,81 @@
       },
     },
 
+    "VMACCESS": {
+      "moduleInfo": {
+        "name": "jdk.graal.compiler.vmaccess",
+        "requires": [
+          "jdk.internal.vm.ci",
+          "jdk.graal.compiler",
+        ],
+        "exports": [
+          "com.oracle.graal.vmaccess",
+        ],
+        "requiresConcealed": {
+          "jdk.internal.vm.ci": [
+            "jdk.vm.ci.meta",
+            "jdk.vm.ci.code",
+          ],
+          "jdk.graal.compiler": [
+            "jdk.graal.compiler.phases.util",
+          ]
+        },
+        "uses": [
+          "com.oracle.graal.vmaccess.VMAccess",
+        ],
+      },
+      "subDir": "src",
+      "dependencies": [
+        "com.oracle.graal.vmaccess",
+      ],
+      "distDependencies": [
+        "GRAAL",
+      ],
+      "useModulePath": True,
+      "maven": False,
+    },
+
+    "HOSTVMACCESS": {
+      "moduleInfo": {
+        "name": "jdk.graal.compiler.hostvmaccess",
+        "requires": [
+          "jdk.graal.compiler",
+          "jdk.graal.compiler.vmaccess",
+          "jdk.internal.vm.ci",
+        ],
+        "exports": [
+          "com.oracle.graal.hostvmaccess",
+        ],
+        "requiresConcealed": {
+          "java.base": [
+            "jdk.internal.access",
+            "jdk.internal.loader",
+            "jdk.internal.module",
+          ],
+          "jdk.internal.vm.ci": [
+            "jdk.vm.ci.meta",
+            "jdk.vm.ci.runtime",
+          ],
+          "jdk.graal.compiler": [
+            "jdk.graal.compiler.api.replacements",
+            "jdk.graal.compiler.api.runtime",
+            "jdk.graal.compiler.core.target",
+            "jdk.graal.compiler.phases.util",
+            "jdk.graal.compiler.runtime",
+          ]
+        },
+      },
+      "subDir": "src",
+      "dependencies": [
+        "com.oracle.graal.hostvmaccess",
+      ],
+      "distDependencies": [
+        "VMACCESS",
+      ],
+      "useModulePath": True,
+      "maven": False,
+    },
+
     "LIBGRAAL_LOADER" : {
       "subDir": "src",
       "dependencies" : [

compiler/src/com.oracle.graal.hostvmaccess/src/META-INF/services/com.oracle.graal.vmaccess.VMAccess$Builder

@@ -0,0 +1 @@
+com.oracle.graal.hostvmaccess.HostVMAccessBuilder

compiler/src/com.oracle.graal.hostvmaccess/src/com/oracle/graal/hostvmaccess/HostVMAccess.java

@@ -0,0 +1,160 @@
+/*
+ * Copyright (c) 2025, 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.
+ */
+package com.oracle.graal.hostvmaccess;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Executable;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+
+import com.oracle.graal.vmaccess.InvocationException;
+import com.oracle.graal.vmaccess.VMAccess;
+
+import jdk.graal.compiler.api.replacements.SnippetReflectionProvider;
+import jdk.graal.compiler.api.runtime.GraalJVMCICompiler;
+import jdk.graal.compiler.api.runtime.GraalRuntime;
+import jdk.graal.compiler.core.target.Backend;
+import jdk.graal.compiler.phases.util.Providers;
+import jdk.graal.compiler.runtime.RuntimeProvider;
+import jdk.vm.ci.meta.JavaConstant;
+import jdk.vm.ci.meta.JavaKind;
+import jdk.vm.ci.meta.ResolvedJavaMethod;
+import jdk.vm.ci.meta.ResolvedJavaType;
+import jdk.vm.ci.meta.Signature;
+import jdk.vm.ci.runtime.JVMCI;
+
+/**
+ * An implementation of {@link VMAccess} that reflects on the JVM it's currently running inside.
+ * There is no isolation between the current JVM and the JVM being accessed through this
+ * implementation, it is the same JVM.
+ * <p>
+ * Note that each instance of this VM access creates a dedicated class loader and module layer that
+ * it uses to implement {@link VMAccess#lookupAppClassLoaderType} instead of using the host JVM's
+ * {@linkplain ClassLoader#getSystemClassLoader system/app classloader}.
+ */
+final class HostVMAccess implements VMAccess {
+    private final ClassLoader appClassLoader;
+    private final Providers providers;
+
+    HostVMAccess(ClassLoader appClassLoader) {
+        this.appClassLoader = appClassLoader;
+        GraalRuntime graalRuntime = ((GraalJVMCICompiler) JVMCI.getRuntime().getCompiler()).getGraalRuntime();
+        Backend hostBackend = graalRuntime.getCapability(RuntimeProvider.class).getHostBackend();
+        providers = hostBackend.getProviders();
+    }
+
+    @Override
+    public Providers getProviders() {
+        return providers;
+    }
+
+    @Override
+    public JavaConstant invoke(ResolvedJavaMethod method, JavaConstant receiver, JavaConstant... arguments) {
+        SnippetReflectionProvider snippetReflection = providers.getSnippetReflection();
+        Executable executable = snippetReflection.originalMethod(method);
+        executable.setAccessible(true);
+        boolean isConstructor = executable instanceof Constructor;
+        Class<?>[] parameterTypes = executable.getParameterTypes();
+        if (Modifier.isStatic(executable.getModifiers()) || isConstructor) {
+            if (receiver != null) {
+                throw new IllegalArgumentException("For static methods or constructor, the receiver argument must be null");
+            }
+        } else if (receiver == null) {
+            throw new NullPointerException("For instance methods, the receiver argument must not be null");
+        } else if (receiver.isNull()) {
+            throw new IllegalArgumentException("For instance methods, the receiver argument must not represent a null constant");
+        }
+        if (parameterTypes.length != arguments.length) {
+            throw new IllegalArgumentException("Wrong number of arguments: expected " + parameterTypes.length + " but got " + arguments.length);
+        }
+        Signature signature = method.getSignature();
+        Object[] unboxedArguments = new Object[parameterTypes.length];
+        for (int i = 0; i < unboxedArguments.length; i++) {
+            JavaKind parameterKind = signature.getParameterKind(i);
+            JavaConstant argument = arguments[i];
+            if (parameterKind.isObject()) {
+                unboxedArguments[i] = snippetReflection.asObject(parameterTypes[i], argument);
+            } else {
+                assert parameterKind.isPrimitive();
+                unboxedArguments[i] = argument.asBoxedPrimitive();
+            }
+        }
+        try {
+            if (isConstructor) {
+                Constructor<?> constructor = (Constructor<?>) executable;
+                return snippetReflection.forObject(constructor.newInstance(unboxedArguments));
+            } else {
+                Method reflectionMethod = (Method) executable;
+                Object unboxedReceiver;
+                if (Modifier.isStatic(reflectionMethod.getModifiers())) {
+                    unboxedReceiver = null;
+                } else {
+                    unboxedReceiver = snippetReflection.asObject(reflectionMethod.getDeclaringClass(), receiver);
+                }
+                JavaKind returnKind = method.getSignature().getReturnKind();
+                Object result = reflectionMethod.invoke(unboxedReceiver, unboxedArguments);
+                if (returnKind == JavaKind.Void) {
+                    return null;
+                }
+                if (returnKind.isObject()) {
+                    return snippetReflection.forObject(result);
+                } else {
+                    return snippetReflection.forBoxed(returnKind, result);
+                }
+            }
+        } catch (InstantiationException e) {
+            throw new IllegalArgumentException(e);
+        } catch (InvocationTargetException e) {
+            throw new InvocationException(snippetReflection.forObject(e.getCause()), e);
+        } catch (IllegalAccessException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @Override
+    public ResolvedJavaType lookupBootClassLoaderType(String name) {
+        return lookupType(name, null);
+    }
+
+    @Override
+    public ResolvedJavaType lookupPlatformClassLoaderType(String name) {
+        return lookupType(name, ClassLoader.getPlatformClassLoader());
+    }
+
+    @Override
+    public ResolvedJavaType lookupAppClassLoaderType(String name) {
+        return lookupType(name, appClassLoader);
+    }
+
+    private ResolvedJavaType lookupType(String name, ClassLoader loader) {
+        try {
+            Class<?> cls = Class.forName(name, false, loader);
+            return providers.getMetaAccess().lookupJavaType(cls);
+        } catch (ClassNotFoundException e) {
+            return null;
+        }
+    }
+}