1 /*
   2  * Copyright (c) 2008, 2023, 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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.lang.invoke;
  27 
  28 import jdk.internal.value.PrimitiveClass;
  29 import sun.invoke.util.VerifyAccess;
  30 
  31 import java.lang.reflect.Constructor;
  32 import java.lang.reflect.Field;
  33 import java.lang.reflect.Member;
  34 import java.lang.reflect.Method;
  35 import java.lang.reflect.Modifier;
  36 import java.util.Objects;
  37 
  38 import static java.lang.invoke.MethodHandleNatives.Constants.*;
  39 import static java.lang.invoke.MethodHandleStatics.newIllegalArgumentException;
  40 import static java.lang.invoke.MethodHandleStatics.newInternalError;
  41 
  42 /**
  43  * A {@code MemberName} is a compact symbolic datum which fully characterizes
  44  * a method or field reference.
  45  * A member name refers to a field, method, constructor, or member type.
  46  * Every member name has a simple name (a string) and a type (either a Class or MethodType).
  47  * A member name may also have a non-null declaring class, or it may be simply
  48  * a naked name/type pair.
  49  * A member name may also have non-zero modifier flags.
  50  * Finally, a member name may be either resolved or unresolved.
  51  * If it is resolved, the existence of the named member has been determined by the JVM.
  52  * <p>
  53  * Whether resolved or not, a member name provides no access rights or
  54  * invocation capability to its possessor.  It is merely a compact
  55  * representation of all symbolic information necessary to link to
  56  * and properly use the named member.
  57  * <p>
  58  * When resolved, a member name's internal implementation may include references to JVM metadata.
  59  * This representation is stateless and only descriptive.
  60  * It provides no private information and no capability to use the member.
  61  * <p>
  62  * By contrast, a {@linkplain java.lang.reflect.Method} contains fuller information
  63  * about the internals of a method (except its bytecodes) and also
  64  * allows invocation.  A MemberName is much lighter than a Method,
  65  * since it contains about 7 fields to the 16 of Method (plus its sub-arrays),
  66  * and those seven fields omit much of the information in Method.
  67  * @author jrose
  68  */
  69 
  70 /*non-public*/
  71 final class MemberName implements Member, Cloneable {
  72     private Class<?> clazz;       // class in which the member is defined
  73     private String   name;        // may be null if not yet materialized
  74     private Object   type;        // may be null if not yet materialized
  75     private int      flags;       // modifier bits; see reflect.Modifier
  76     private ResolvedMethodName method;    // cached resolved method information
  77     //@Injected intptr_t       vmindex;   // vtable index or offset of resolved member
  78     Object   resolution;  // if null, this guy is resolved
  79 
  80     /** Return the declaring class of this member.
  81      *  In the case of a bare name and type, the declaring class will be null.
  82      */
  83     public Class<?> getDeclaringClass() {
  84         return clazz;
  85     }
  86 
  87     /** Utility method producing the class loader of the declaring class. */
  88     public ClassLoader getClassLoader() {
  89         return clazz.getClassLoader();
  90     }
  91 
  92     /** Return the simple name of this member.
  93      *  For a type, it is the same as {@link Class#getSimpleName}.
  94      *  For a method or field, it is the simple name of the member.
  95      *  For an identity object constructor, it is {@code "<init>"}.
  96      *  For a value class static factory method, it is {@code "<vnew>"}.
  97      */
  98     public String getName() {
  99         if (name == null) {
 100             expandFromVM();
 101             if (name == null) {
 102                 return null;
 103             }
 104         }
 105         return name;
 106     }
 107 
 108     public MethodType getMethodOrFieldType() {
 109         if (isInvocable())
 110             return getMethodType();
 111         if (isGetter())
 112             return MethodType.methodType(getFieldType());
 113         if (isSetter())
 114             return MethodType.methodType(void.class, getFieldType());
 115         throw new InternalError("not a method or field: "+this);
 116     }
 117 
 118     /** Return the declared type of this member, which
 119      *  must be a method or constructor.
 120      */
 121     public MethodType getMethodType() {
 122         if (type == null) {
 123             expandFromVM();
 124             if (type == null) {
 125                 return null;
 126             }
 127         }
 128         if (!isInvocable()) {
 129             throw newIllegalArgumentException("not invocable, no method type");
 130         }
 131 
 132         {
 133             // Get a snapshot of type which doesn't get changed by racing threads.
 134             final Object type = this.type;
 135             if (type instanceof MethodType mt) {
 136                 return mt;
 137             }
 138         }
 139 
 140         // type is not a MethodType yet.  Convert it thread-safely.
 141         synchronized (this) {
 142             if (type instanceof String sig) {
 143                 MethodType res = MethodType.fromDescriptor(sig, getClassLoader());
 144                 type = res;
 145             } else if (type instanceof Object[] typeInfo) {
 146                 Class<?>[] ptypes = (Class<?>[]) typeInfo[1];
 147                 Class<?> rtype = (Class<?>) typeInfo[0];
 148                 MethodType res = MethodType.methodType(rtype, ptypes, true);
 149                 type = res;
 150             }
 151             // Make sure type is a MethodType for racing threads.
 152             assert type instanceof MethodType : "bad method type " + type;
 153         }
 154         return (MethodType) type;
 155     }
 156 
 157     /** Return the descriptor of this member, which
 158      *  must be a method or constructor.
 159      */
 160     String getMethodDescriptor() {
 161         if (type == null) {
 162             expandFromVM();
 163             if (type == null) {
 164                 return null;
 165             }
 166         }
 167         if (!isInvocable()) {
 168             throw newIllegalArgumentException("not invocable, no method type");
 169         }
 170 
 171         // Get a snapshot of type which doesn't get changed by racing threads.
 172         final Object type = this.type;
 173         if (type instanceof String str) {
 174             return str;
 175         } else {
 176             return getMethodType().toMethodDescriptorString();
 177         }
 178     }
 179 
 180     /** Return the actual type under which this method or constructor must be invoked.
 181      *  For non-static methods or constructors, this is the type with a leading parameter,
 182      *  a reference to declaring class.  For static methods, it is the same as the declared type.
 183      */
 184     public MethodType getInvocationType() {
 185         MethodType itype = getMethodOrFieldType();
 186         Class<?> c = PrimitiveClass.isPrimitiveClass(clazz) ? PrimitiveClass.asValueType(clazz) : clazz;
 187         if (isObjectConstructor() && getReferenceKind() == REF_newInvokeSpecial)
 188             return itype.changeReturnType(c);
 189         if (!isStatic())
 190             return itype.insertParameterTypes(0, c);
 191         return itype;
 192     }
 193 
 194     /** Return the declared type of this member, which
 195      *  must be a field or type.
 196      *  If it is a type member, that type itself is returned.
 197      */
 198     public Class<?> getFieldType() {
 199         if (type == null) {
 200             expandFromVM();
 201             if (type == null) {
 202                 return null;
 203             }
 204         }
 205         if (isInvocable()) {
 206             throw newIllegalArgumentException("not a field or nested class, no simple type");
 207         }
 208 
 209         {
 210             // Get a snapshot of type which doesn't get changed by racing threads.
 211             final Object type = this.type;
 212             if (type instanceof Class<?> cl) {
 213                 return cl;
 214             }
 215         }
 216 
 217         // type is not a Class yet.  Convert it thread-safely.
 218         synchronized (this) {
 219             if (type instanceof String sig) {
 220                 MethodType mtype = MethodType.fromDescriptor("()"+sig, getClassLoader());
 221                 Class<?> res = mtype.returnType();
 222                 type = res;
 223             }
 224             // Make sure type is a Class for racing threads.
 225             assert type instanceof Class<?> : "bad field type " + type;
 226         }
 227         return (Class<?>) type;
 228     }
 229 
 230     /** Utility method to produce either the method type or field type of this member. */
 231     public Object getType() {
 232         return (isInvocable() ? getMethodType() : getFieldType());
 233     }
 234 
 235     /** Return the modifier flags of this member.
 236      *  @see java.lang.reflect.Modifier
 237      */
 238     public int getModifiers() {
 239         return (flags & RECOGNIZED_MODIFIERS);
 240     }
 241 
 242     /** Return the reference kind of this member, or zero if none.
 243      */
 244     public byte getReferenceKind() {
 245         return (byte) ((flags >>> MN_REFERENCE_KIND_SHIFT) & MN_REFERENCE_KIND_MASK);
 246     }
 247     private boolean referenceKindIsConsistent() {
 248         byte refKind = getReferenceKind();
 249         if (refKind == REF_NONE)  return isType();
 250         if (isField()) {
 251             assert(staticIsConsistent());
 252             assert(MethodHandleNatives.refKindIsField(refKind));
 253         } else if (isObjectConstructor()) {
 254             assert(refKind == REF_newInvokeSpecial || refKind == REF_invokeSpecial);
 255         } else if (isMethod()) {
 256             assert(staticIsConsistent());
 257             assert(MethodHandleNatives.refKindIsMethod(refKind));
 258             if (clazz.isInterface())
 259                 assert(refKind == REF_invokeInterface ||
 260                        refKind == REF_invokeStatic    ||
 261                        refKind == REF_invokeSpecial   ||
 262                        refKind == REF_invokeVirtual && isObjectPublicMethod());
 263         } else {
 264             assert(false);
 265         }
 266         return true;
 267     }
 268     private boolean isObjectPublicMethod() {
 269         if (clazz == Object.class)  return true;
 270         MethodType mtype = getMethodType();
 271         if (name.equals("toString") && mtype.returnType() == String.class && mtype.parameterCount() == 0)
 272             return true;
 273         if (name.equals("hashCode") && mtype.returnType() == int.class && mtype.parameterCount() == 0)
 274             return true;
 275         if (name.equals("equals") && mtype.returnType() == boolean.class && mtype.parameterCount() == 1 && mtype.parameterType(0) == Object.class)
 276             return true;
 277         return false;
 278     }
 279 
 280     /*non-public*/
 281     boolean referenceKindIsConsistentWith(int originalRefKind) {
 282         int refKind = getReferenceKind();
 283         if (refKind == originalRefKind) return true;
 284         if (getClass().desiredAssertionStatus()) {
 285             switch (originalRefKind) {
 286                 case REF_invokeInterface -> {
 287                     // Looking up an interface method, can get (e.g.) Object.hashCode
 288                     assert (refKind == REF_invokeVirtual || refKind == REF_invokeSpecial) : this;
 289                 }
 290                 case REF_invokeVirtual, REF_newInvokeSpecial -> {
 291                     // Looked up a virtual, can get (e.g.) final String.hashCode.
 292                     assert (refKind == REF_invokeSpecial) : this;
 293                 }
 294                 default -> {
 295                     assert (false) : this + " != " + MethodHandleNatives.refKindName((byte) originalRefKind);
 296                 }
 297             }
 298         }
 299         return true;
 300     }
 301     private boolean staticIsConsistent() {
 302         byte refKind = getReferenceKind();
 303         return MethodHandleNatives.refKindIsStatic(refKind) == isStatic() || getModifiers() == 0;
 304     }
 305     private boolean vminfoIsConsistent() {
 306         byte refKind = getReferenceKind();
 307         assert(isResolved());  // else don't call
 308         Object vminfo = MethodHandleNatives.getMemberVMInfo(this);
 309         assert(vminfo instanceof Object[]);
 310         long vmindex = (Long) ((Object[])vminfo)[0];
 311         Object vmtarget = ((Object[])vminfo)[1];
 312         if (MethodHandleNatives.refKindIsField(refKind)) {
 313             assert(vmindex >= 0) : vmindex + ":" + this;
 314             assert(vmtarget instanceof Class);
 315         } else {
 316             if (MethodHandleNatives.refKindDoesDispatch(refKind))
 317                 assert(vmindex >= 0) : vmindex + ":" + this;
 318             else
 319                 assert(vmindex < 0) : vmindex;
 320             assert(vmtarget instanceof MemberName) : vmtarget + " in " + this;
 321         }
 322         return true;
 323     }
 324 
 325     private MemberName changeReferenceKind(byte refKind, byte oldKind) {
 326         assert(getReferenceKind() == oldKind && MethodHandleNatives.refKindIsValid(refKind));
 327         flags += (((int)refKind - oldKind) << MN_REFERENCE_KIND_SHIFT);
 328         return this;
 329     }
 330 
 331     private boolean matchingFlagsSet(int mask, int flags) {
 332         return (this.flags & mask) == flags;
 333     }
 334     private boolean allFlagsSet(int flags) {
 335         return (this.flags & flags) == flags;
 336     }
 337     private boolean anyFlagSet(int flags) {
 338         return (this.flags & flags) != 0;
 339     }
 340 
 341     /** Utility method to query if this member is a method handle invocation (invoke or invokeExact).
 342      */
 343     public boolean isMethodHandleInvoke() {
 344         final int bits = MH_INVOKE_MODS &~ Modifier.PUBLIC;
 345         final int negs = Modifier.STATIC;
 346         if (matchingFlagsSet(bits | negs, bits) && clazz == MethodHandle.class) {
 347             return isMethodHandleInvokeName(name);
 348         }
 349         return false;
 350     }
 351     public static boolean isMethodHandleInvokeName(String name) {
 352         return switch (name) {
 353             case "invoke", "invokeExact" -> true;
 354             default -> false;
 355         };
 356     }
 357     public boolean isVarHandleMethodInvoke() {
 358         final int bits = MH_INVOKE_MODS &~ Modifier.PUBLIC;
 359         final int negs = Modifier.STATIC;
 360         if (matchingFlagsSet(bits | negs, bits) && clazz == VarHandle.class) {
 361             return isVarHandleMethodInvokeName(name);
 362         }
 363         return false;
 364     }
 365     public static boolean isVarHandleMethodInvokeName(String name) {
 366         try {
 367             VarHandle.AccessMode.valueFromMethodName(name);
 368             return true;
 369         } catch (IllegalArgumentException e) {
 370             return false;
 371         }
 372     }
 373     private static final int MH_INVOKE_MODS = Modifier.NATIVE | Modifier.FINAL | Modifier.PUBLIC;
 374 
 375     /** Utility method to query the modifier flags of this member. */
 376     public boolean isStatic() {
 377         return Modifier.isStatic(flags);
 378     }
 379     /** Utility method to query the modifier flags of this member. */
 380     public boolean isPublic() {
 381         return Modifier.isPublic(flags);
 382     }
 383     /** Utility method to query the modifier flags of this member. */
 384     public boolean isPrivate() {
 385         return Modifier.isPrivate(flags);
 386     }
 387     /** Utility method to query the modifier flags of this member. */
 388     public boolean isProtected() {
 389         return Modifier.isProtected(flags);
 390     }
 391     /** Utility method to query the modifier flags of this member. */
 392     public boolean isFinal() {
 393         // all fields declared in a value type are effectively final
 394         assert(!clazz.isValue() || !isField() || Modifier.isFinal(flags));
 395         return Modifier.isFinal(flags);
 396     }
 397     /** Utility method to query whether this member or its defining class is final. */
 398     public boolean canBeStaticallyBound() {
 399         return Modifier.isFinal(flags | clazz.getModifiers());
 400     }
 401     /** Utility method to query the modifier flags of this member. */
 402     public boolean isVolatile() {
 403         return Modifier.isVolatile(flags);
 404     }
 405     /** Utility method to query the modifier flags of this member. */
 406     public boolean isAbstract() {
 407         return Modifier.isAbstract(flags);
 408     }
 409     /** Utility method to query the modifier flags of this member. */
 410     public boolean isNative() {
 411         return Modifier.isNative(flags);
 412     }
 413     // let the rest (native, volatile, transient, etc.) be tested via Modifier.isFoo
 414 
 415     // unofficial modifier flags, used by HotSpot:
 416     static final int BRIDGE      = 0x00000040;
 417     static final int VARARGS     = 0x00000080;
 418     static final int SYNTHETIC   = 0x00001000;
 419     static final int ANNOTATION  = 0x00002000;
 420     static final int ENUM        = 0x00004000;
 421 
 422     /** Utility method to query the modifier flags of this member; returns false if the member is not a method. */
 423     public boolean isBridge() {
 424         return allFlagsSet(IS_METHOD | BRIDGE);
 425     }
 426     /** Utility method to query the modifier flags of this member; returns false if the member is not a method. */
 427     public boolean isVarargs() {
 428         return allFlagsSet(VARARGS) && isInvocable();
 429     }
 430     /** Utility method to query the modifier flags of this member; returns false if the member is not a method. */
 431     public boolean isSynthetic() {
 432         return allFlagsSet(SYNTHETIC);
 433     }
 434 
 435     /** Query whether this member is a flattened field */
 436     public boolean isFlattened() { return (flags & MN_FLATTENED) == MN_FLATTENED; }
 437 
 438     /** Query whether this member is a field of a primitive class. */
 439     public boolean isInlineableField()  {
 440         if (isField()) {
 441             Class<?> type = getFieldType();
 442             return PrimitiveClass.isPrimitiveValueType(type) || (type.isValue() && !PrimitiveClass.isPrimitiveClass(type));
 443         }
 444         return false;
 445     }
 446 
 447     static final String CONSTRUCTOR_NAME = "<init>";
 448     static final String VALUE_FACTORY_NAME = "<vnew>";  // the ever-popular
 449 
 450     // modifiers exported by the JVM:
 451     static final int RECOGNIZED_MODIFIERS = 0xFFFF;
 452 
 453     // private flags, not part of RECOGNIZED_MODIFIERS:
 454     static final int
 455             IS_METHOD             = MN_IS_METHOD,              // method (not object constructor)
 456             IS_OBJECT_CONSTRUCTOR = MN_IS_OBJECT_CONSTRUCTOR,  // object constructor
 457             IS_FIELD              = MN_IS_FIELD,               // field
 458             IS_TYPE               = MN_IS_TYPE,                // nested type
 459             CALLER_SENSITIVE      = MN_CALLER_SENSITIVE,       // @CallerSensitive annotation detected
 460             TRUSTED_FINAL         = MN_TRUSTED_FINAL;    // trusted final field
 461 
 462     static final int ALL_ACCESS = Modifier.PUBLIC | Modifier.PRIVATE | Modifier.PROTECTED;
 463     static final int ALL_KINDS = IS_METHOD | IS_OBJECT_CONSTRUCTOR | IS_FIELD | IS_TYPE;
 464     static final int IS_INVOCABLE = IS_METHOD | IS_OBJECT_CONSTRUCTOR;
 465 
 466     /** Utility method to query whether this member is a method or constructor. */
 467     public boolean isInvocable() {
 468         return anyFlagSet(IS_INVOCABLE);
 469     }
 470     /** Query whether this member is a method. */
 471     public boolean isMethod() {
 472         return allFlagsSet(IS_METHOD);
 473     }
 474     /** Query whether this member is a constructor. */
 475     public boolean isObjectConstructor() {
 476         return allFlagsSet(IS_OBJECT_CONSTRUCTOR);
 477     }
 478     /** Query whether this member is an object constructor or static <init> factory */
 479     public boolean isStaticValueFactoryMethod() {
 480         return VALUE_FACTORY_NAME.equals(name) && isMethod();
 481     }
 482 
 483     /** Query whether this member is a field. */
 484     public boolean isField() {
 485         return allFlagsSet(IS_FIELD);
 486     }
 487     /** Query whether this member is a type. */
 488     public boolean isType() {
 489         return allFlagsSet(IS_TYPE);
 490     }
 491     /** Utility method to query whether this member is neither public, private, nor protected. */
 492     public boolean isPackage() {
 493         return !anyFlagSet(ALL_ACCESS);
 494     }
 495     /** Query whether this member has a CallerSensitive annotation. */
 496     public boolean isCallerSensitive() {
 497         return allFlagsSet(CALLER_SENSITIVE);
 498     }
 499     /** Query whether this member is a trusted final field. */
 500     public boolean isTrustedFinalField() {
 501         return allFlagsSet(TRUSTED_FINAL | IS_FIELD);
 502     }
 503 
 504     /**
 505      * Check if MemberName is a call to a method named {@code name} in class {@code declaredClass}.
 506      */
 507     public boolean refersTo(Class<?> declc, String n) {
 508         return clazz == declc && getName().equals(n);
 509     }
 510 
 511     /** Initialize a query.   It is not resolved. */
 512     private void init(Class<?> defClass, String name, Object type, int flags) {
 513         // defining class is allowed to be null (for a naked name/type pair)
 514         //name.toString();  // null check
 515         //type.equals(type);  // null check
 516         // fill in fields:
 517         this.clazz = defClass;
 518         this.name = name;
 519         this.type = type;
 520         this.flags = flags;
 521         assert(anyFlagSet(ALL_KINDS) && this.resolution == null);  // nobody should have touched this yet
 522         //assert(referenceKindIsConsistent());  // do this after resolution
 523     }
 524 
 525     /**
 526      * Calls down to the VM to fill in the fields.  This method is
 527      * synchronized to avoid racing calls.
 528      */
 529     private void expandFromVM() {
 530         if (type != null) {
 531             return;
 532         }
 533         if (!isResolved()) {
 534             return;
 535         }
 536         MethodHandleNatives.expand(this);
 537     }
 538 
 539     // Capturing information from the Core Reflection API:
 540     private static int flagsMods(int flags, int mods, byte refKind) {
 541         assert((flags & RECOGNIZED_MODIFIERS) == 0
 542                 && (mods & ~RECOGNIZED_MODIFIERS) == 0
 543                 && (refKind & ~MN_REFERENCE_KIND_MASK) == 0);
 544         return flags | mods | (refKind << MN_REFERENCE_KIND_SHIFT);
 545     }
 546     /** Create a name for the given reflected method.  The resulting name will be in a resolved state. */
 547     public MemberName(Method m) {
 548         this(m, false);
 549     }
 550     @SuppressWarnings("LeakingThisInConstructor")
 551     public MemberName(Method m, boolean wantSpecial) {
 552         Objects.requireNonNull(m);
 553         // fill in vmtarget, vmindex while we have m in hand:
 554         MethodHandleNatives.init(this, m);
 555         if (clazz == null) {  // MHN.init failed
 556             if (m.getDeclaringClass() == MethodHandle.class &&
 557                 isMethodHandleInvokeName(m.getName())) {
 558                 // The JVM did not reify this signature-polymorphic instance.
 559                 // Need a special case here.
 560                 // See comments on MethodHandleNatives.linkMethod.
 561                 MethodType type = MethodType.methodType(m.getReturnType(), m.getParameterTypes());
 562                 int flags = flagsMods(IS_METHOD, m.getModifiers(), REF_invokeVirtual);
 563                 init(MethodHandle.class, m.getName(), type, flags);
 564                 if (isMethodHandleInvoke())
 565                     return;
 566             }
 567             if (m.getDeclaringClass() == VarHandle.class &&
 568                 isVarHandleMethodInvokeName(m.getName())) {
 569                 // The JVM did not reify this signature-polymorphic instance.
 570                 // Need a special case here.
 571                 // See comments on MethodHandleNatives.linkMethod.
 572                 MethodType type = MethodType.methodType(m.getReturnType(), m.getParameterTypes());
 573                 int flags = flagsMods(IS_METHOD, m.getModifiers(), REF_invokeVirtual);
 574                 init(VarHandle.class, m.getName(), type, flags);
 575                 if (isVarHandleMethodInvoke())
 576                     return;
 577             }
 578             throw new LinkageError(m.toString());
 579         }
 580         assert(isResolved());
 581         this.name = m.getName();
 582         if (this.type == null)
 583             this.type = new Object[] { m.getReturnType(), m.getParameterTypes() };
 584         if (wantSpecial) {
 585             if (isAbstract())
 586                 throw new AbstractMethodError(this.toString());
 587             if (getReferenceKind() == REF_invokeVirtual)
 588                 changeReferenceKind(REF_invokeSpecial, REF_invokeVirtual);
 589             else if (getReferenceKind() == REF_invokeInterface)
 590                 // invokeSpecial on a default method
 591                 changeReferenceKind(REF_invokeSpecial, REF_invokeInterface);
 592         }
 593     }
 594     public MemberName asSpecial() {
 595         switch (getReferenceKind()) {
 596         case REF_invokeSpecial:     return this;
 597         case REF_invokeVirtual:     return clone().changeReferenceKind(REF_invokeSpecial, REF_invokeVirtual);
 598         case REF_invokeInterface:   return clone().changeReferenceKind(REF_invokeSpecial, REF_invokeInterface);
 599         case REF_newInvokeSpecial:  return clone().changeReferenceKind(REF_invokeSpecial, REF_newInvokeSpecial);
 600         }
 601         throw new IllegalArgumentException(this.toString());
 602     }
 603     /** If this MN is not REF_newInvokeSpecial, return a clone with that ref. kind.
 604      *  In that case it must already be REF_invokeSpecial.
 605      */
 606     public MemberName asObjectConstructor() {
 607         switch (getReferenceKind()) {
 608         case REF_invokeSpecial:     return clone().changeReferenceKind(REF_newInvokeSpecial, REF_invokeSpecial);
 609         case REF_newInvokeSpecial:  return this;
 610         }
 611         throw new IllegalArgumentException(this.toString());
 612     }
 613     /** If this MN is a REF_invokeSpecial, return a clone with the "normal" kind
 614      *  REF_invokeVirtual; also switch either to REF_invokeInterface if clazz.isInterface.
 615      *  The end result is to get a fully virtualized version of the MN.
 616      *  (Note that resolving in the JVM will sometimes devirtualize, changing
 617      *  REF_invokeVirtual of a final to REF_invokeSpecial, and REF_invokeInterface
 618      *  in some corner cases to either of the previous two; this transform
 619      *  undoes that change under the assumption that it occurred.)
 620      */
 621     public MemberName asNormalOriginal() {
 622         byte refKind = getReferenceKind();
 623         byte newRefKind = switch (refKind) {
 624             case REF_invokeInterface,
 625                  REF_invokeVirtual,
 626                  REF_invokeSpecial -> clazz.isInterface() ? REF_invokeInterface : REF_invokeVirtual;
 627             default -> refKind;
 628         };
 629         if (newRefKind == refKind)
 630             return this;
 631         MemberName result = clone().changeReferenceKind(newRefKind, refKind);
 632         assert(this.referenceKindIsConsistentWith(result.getReferenceKind()));
 633         return result;
 634     }
 635     /** Create a name for the given reflected constructor.  The resulting name will be in a resolved state. */
 636     @SuppressWarnings("LeakingThisInConstructor")
 637     public MemberName(Constructor<?> ctor) {
 638         Objects.requireNonNull(ctor);
 639         // fill in vmtarget, vmindex while we have ctor in hand:
 640         MethodHandleNatives.init(this, ctor);
 641         assert(isResolved() && this.clazz != null);
 642         this.name = this.clazz.isValue() ? VALUE_FACTORY_NAME : CONSTRUCTOR_NAME;
 643         if (this.type == null) {
 644             Class<?> rtype = void.class;
 645             if (isStatic()) {  // a value class static factory, not a true constructor
 646                 rtype = getDeclaringClass();
 647             }
 648             this.type = new Object[] { rtype, ctor.getParameterTypes() };
 649         }
 650     }
 651     /** Create a name for the given reflected field.  The resulting name will be in a resolved state.
 652      */
 653     public MemberName(Field fld) {
 654         this(fld, false);
 655     }
 656     static {
 657         // the following MemberName constructor relies on these ranges matching up
 658         assert((REF_putStatic - REF_getStatic) == (REF_putField - REF_getField));
 659     }
 660     @SuppressWarnings("LeakingThisInConstructor")
 661     public MemberName(Field fld, boolean makeSetter) {
 662         Objects.requireNonNull(fld);
 663         // fill in vmtarget, vmindex while we have fld in hand:
 664         MethodHandleNatives.init(this, fld);
 665         assert(isResolved() && this.clazz != null);
 666         this.name = fld.getName();
 667         this.type = fld.getType();
 668         byte refKind = this.getReferenceKind();
 669         assert(refKind == (isStatic() ? REF_getStatic : REF_getField));
 670         if (makeSetter) {
 671             changeReferenceKind((byte)(refKind + (REF_putStatic - REF_getStatic)), refKind);
 672         }
 673     }
 674     public boolean isGetter() {
 675         return MethodHandleNatives.refKindIsGetter(getReferenceKind());
 676     }
 677     public boolean isSetter() {
 678         return MethodHandleNatives.refKindIsSetter(getReferenceKind());
 679     }
 680 
 681     /** Create a name for the given class.  The resulting name will be in a resolved state. */
 682     public MemberName(Class<?> type) {
 683         init(type.getDeclaringClass(), type.getSimpleName(), type,
 684                 flagsMods(IS_TYPE, type.getModifiers(), REF_NONE));
 685         initResolved(true);
 686     }
 687 
 688     /**
 689      * Create a name for a signature-polymorphic invoker.
 690      * This is a placeholder for a signature-polymorphic instance
 691      * (of MH.invokeExact, etc.) that the JVM does not reify.
 692      * See comments on {@link MethodHandleNatives#linkMethod}.
 693      */
 694     static MemberName makeMethodHandleInvoke(String name, MethodType type) {
 695         return makeMethodHandleInvoke(name, type, MH_INVOKE_MODS | SYNTHETIC);
 696     }
 697     static MemberName makeMethodHandleInvoke(String name, MethodType type, int mods) {
 698         MemberName mem = new MemberName(MethodHandle.class, name, type, REF_invokeVirtual);
 699         mem.flags |= mods;  // it's not resolved, but add these modifiers anyway
 700         assert(mem.isMethodHandleInvoke()) : mem;
 701         return mem;
 702     }
 703 
 704     static MemberName makeVarHandleMethodInvoke(String name, MethodType type) {
 705         return makeVarHandleMethodInvoke(name, type, MH_INVOKE_MODS | SYNTHETIC);
 706     }
 707     static MemberName makeVarHandleMethodInvoke(String name, MethodType type, int mods) {
 708         MemberName mem = new MemberName(VarHandle.class, name, type, REF_invokeVirtual);
 709         mem.flags |= mods;  // it's not resolved, but add these modifiers anyway
 710         assert(mem.isVarHandleMethodInvoke()) : mem;
 711         return mem;
 712     }
 713 
 714     // bare-bones constructor; the JVM will fill it in
 715     MemberName() { }
 716 
 717     // locally useful cloner
 718     @Override protected MemberName clone() {
 719         try {
 720             return (MemberName) super.clone();
 721         } catch (CloneNotSupportedException ex) {
 722             throw newInternalError(ex);
 723         }
 724      }
 725 
 726     /** Get the definition of this member name.
 727      *  This may be in a super-class of the declaring class of this member.
 728      */
 729     public MemberName getDefinition() {
 730         if (!isResolved())  throw new IllegalStateException("must be resolved: "+this);
 731         if (isType())  return this;
 732         MemberName res = this.clone();
 733         res.clazz = null;
 734         res.type = null;
 735         res.name = null;
 736         res.resolution = res;
 737         res.expandFromVM();
 738         assert(res.getName().equals(this.getName()));
 739         return res;
 740     }
 741 
 742     @Override
 743     @SuppressWarnings({"deprecation", "removal"})
 744     public int hashCode() {
 745         // Avoid autoboxing getReferenceKind(), since this is used early and will force
 746         // early initialization of Byte$ByteCache
 747         return Objects.hash(clazz, new Byte(getReferenceKind()), name, getType());
 748     }
 749 
 750     @Override
 751     public boolean equals(Object that) {
 752         return that instanceof MemberName mn && this.equals(mn);
 753     }
 754 
 755     /** Decide if two member names have exactly the same symbolic content.
 756      *  Does not take into account any actual class members, so even if
 757      *  two member names resolve to the same actual member, they may
 758      *  be distinct references.
 759      */
 760     public boolean equals(MemberName that) {
 761         if (this == that)  return true;
 762         if (that == null)  return false;
 763         return this.clazz == that.clazz
 764                 && this.getReferenceKind() == that.getReferenceKind()
 765                 && Objects.equals(this.name, that.name)
 766                 && Objects.equals(this.getType(), that.getType());
 767     }
 768 
 769     // Construction from symbolic parts, for queries:
 770     /** Create a field or type name from the given components:
 771      *  Declaring class, name, type, reference kind.
 772      *  The declaring class may be supplied as null if this is to be a bare name and type.
 773      *  The resulting name will in an unresolved state.
 774      */
 775     public MemberName(Class<?> defClass, String name, Class<?> type, byte refKind) {
 776         init(defClass, name, type, flagsMods(IS_FIELD, 0, refKind));
 777         initResolved(false);
 778     }
 779     /** Create a method or constructor name from the given components:
 780      *  Declaring class, name, type, reference kind.
 781      *  It will be an object constructor if and only if the name is {@code "<init>"}.
 782      *  It will be a value class instance factory method if and only if the name is {@code "<vnew>"}.
 783      *  The declaring class may be supplied as null if this is to be a bare name and type.
 784      *  The last argument is optional, a boolean which requests REF_invokeSpecial.
 785      *  The resulting name will in an unresolved state.
 786      */
 787     public MemberName(Class<?> defClass, String name, MethodType type, byte refKind) {
 788         int initFlags = CONSTRUCTOR_NAME.equals(name) ? IS_OBJECT_CONSTRUCTOR : IS_METHOD;
 789         init(defClass, name, type, flagsMods(initFlags, 0, refKind));
 790         initResolved(false);
 791     }
 792     /** Create a method, constructor, or field name from the given components:
 793      *  Reference kind, declaring class, name, type.
 794      */
 795     public MemberName(byte refKind, Class<?> defClass, String name, Object type) {
 796         int kindFlags;
 797         if (MethodHandleNatives.refKindIsField(refKind)) {
 798             kindFlags = IS_FIELD;
 799             if (!(type instanceof Class))
 800                 throw newIllegalArgumentException("not a field type");
 801         } else if (MethodHandleNatives.refKindIsMethod(refKind)) {
 802             kindFlags = IS_METHOD;
 803             if (!(type instanceof MethodType))
 804                 throw newIllegalArgumentException("not a method type");
 805         } else if (refKind == REF_newInvokeSpecial) {
 806             kindFlags = IS_OBJECT_CONSTRUCTOR;
 807             if (!(type instanceof MethodType) ||
 808                 !CONSTRUCTOR_NAME.equals(name))
 809                 throw newIllegalArgumentException("not a constructor type or name");
 810         } else {
 811             throw newIllegalArgumentException("bad reference kind "+refKind);
 812         }
 813         init(defClass, name, type, flagsMods(kindFlags, 0, refKind));
 814         initResolved(false);
 815     }
 816 
 817     /** Query whether this member name is resolved.
 818      *  A resolved member name is one for which the JVM has found
 819      *  a method, constructor, field, or type binding corresponding exactly to the name.
 820      *  (Document?)
 821      */
 822     public boolean isResolved() {
 823         return resolution == null;
 824     }
 825 
 826     void initResolved(boolean isResolved) {
 827         assert(this.resolution == null);  // not initialized yet!
 828         if (!isResolved)
 829             this.resolution = this;
 830         assert(isResolved() == isResolved);
 831     }
 832 
 833     void checkForTypeAlias(Class<?> refc) {
 834         if (isInvocable()) {
 835             MethodType type;
 836             if (this.type instanceof MethodType mt)
 837                 type = mt;
 838             else
 839                 this.type = type = getMethodType();
 840             if (type.erase() == type)  return;
 841             if (VerifyAccess.isTypeVisible(type, refc))  return;
 842             throw new LinkageError("bad method type alias: "+type+" not visible from "+refc);
 843         } else {
 844             Class<?> type;
 845             if (this.type instanceof Class<?> cl)
 846                 type = cl;
 847             else
 848                 this.type = type = getFieldType();
 849             if (VerifyAccess.isTypeVisible(type, refc))  return;
 850             throw new LinkageError("bad field type alias: "+type+" not visible from "+refc);
 851         }
 852     }
 853 
 854 
 855     /** Produce a string form of this member name.
 856      *  For types, it is simply the type's own string (as reported by {@code toString}).
 857      *  For fields, it is {@code "DeclaringClass.name/type"}.
 858      *  For methods and constructors, it is {@code "DeclaringClass.name(ptype...)rtype"}.
 859      *  If the declaring class is null, the prefix {@code "DeclaringClass."} is omitted.
 860      *  If the member is unresolved, a prefix {@code "*."} is prepended.
 861      */
 862     @SuppressWarnings("LocalVariableHidesMemberVariable")
 863     @Override
 864     public String toString() {
 865         if (isType())
 866             return type.toString();  // class java.lang.String
 867         // else it is a field, method, or constructor
 868         StringBuilder buf = new StringBuilder();
 869         if (getDeclaringClass() != null) {
 870             buf.append(getName(clazz));
 871             buf.append('.');
 872         }
 873         String name = this.name; // avoid expanding from VM
 874         buf.append(name == null ? "*" : name);
 875         Object type = this.type; // avoid expanding from VM
 876         if (!isInvocable()) {
 877             buf.append('/');
 878             buf.append(type == null ? "*" : getName(type));
 879         } else {
 880             buf.append(type == null ? "(*)*" : getName(type));
 881         }
 882         byte refKind = getReferenceKind();
 883         if (refKind != REF_NONE) {
 884             buf.append('/');
 885             buf.append(MethodHandleNatives.refKindName(refKind));
 886         }
 887         //buf.append("#").append(System.identityHashCode(this));
 888         return buf.toString();
 889     }
 890     private static String getName(Object obj) {
 891         if (obj instanceof Class<?> cl)
 892             return cl.getName();
 893         return String.valueOf(obj);
 894     }
 895 
 896     public IllegalAccessException makeAccessException(String message, Object from) {
 897         message = message + ": " + this;
 898         if (from != null)  {
 899             if (from == MethodHandles.publicLookup()) {
 900                 message += ", from public Lookup";
 901             } else {
 902                 Module m;
 903                 Class<?> plc;
 904                 if (from instanceof MethodHandles.Lookup lookup) {
 905                     from = lookup.lookupClass();
 906                     m = lookup.lookupClass().getModule();
 907                     plc = lookup.previousLookupClass();
 908                 } else {
 909                     m = ((Class<?>)from).getModule();
 910                     plc = null;
 911                 }
 912                 message += ", from " + from + " (" + m + ")";
 913                 if (plc != null) {
 914                     message += ", previous lookup " +
 915                         plc.getName() + " (" + plc.getModule() + ")";
 916                 }
 917             }
 918         }
 919         return new IllegalAccessException(message);
 920     }
 921     private String message() {
 922         if (isResolved())
 923             return "no access";
 924         else if (isObjectConstructor())
 925             return "no such constructor";
 926         else if (isMethod())
 927             return "no such method";
 928         else
 929             return "no such field";
 930     }
 931     public ReflectiveOperationException makeAccessException() {
 932         String message = message() + ": " + this;
 933         ReflectiveOperationException ex;
 934         if (isResolved() || !(resolution instanceof NoSuchMethodError ||
 935                               resolution instanceof NoSuchFieldError))
 936             ex = new IllegalAccessException(message);
 937         else if (isObjectConstructor())
 938             ex = new NoSuchMethodException(message);
 939         else if (isMethod())
 940             ex = new NoSuchMethodException(message);
 941         else
 942             ex = new NoSuchFieldException(message);
 943         if (resolution instanceof Throwable res)
 944             ex.initCause(res);
 945         return ex;
 946     }
 947 
 948     /** Actually making a query requires an access check. */
 949     /*non-public*/
 950     static Factory getFactory() {
 951         return Factory.INSTANCE;
 952     }
 953     /** A factory type for resolving member names with the help of the VM.
 954      *  TBD: Define access-safe public constructors for this factory.
 955      */
 956     /*non-public*/
 957     static class Factory {
 958         private Factory() { } // singleton pattern
 959         static final Factory INSTANCE = new Factory();
 960 
 961         /** Produce a resolved version of the given member.
 962          *  Super types are searched (for inherited members) if {@code searchSupers} is true.
 963          *  Access checking is performed on behalf of the given {@code lookupClass}.
 964          *  If lookup fails or access is not permitted, null is returned.
 965          *  Otherwise a fresh copy of the given member is returned, with modifier bits filled in.
 966          */
 967         private MemberName resolve(byte refKind, MemberName ref, Class<?> lookupClass, int allowedModes,
 968                                    boolean speculativeResolve) {
 969             MemberName m = ref.clone();  // JVM will side-effect the ref
 970             assert(refKind == m.getReferenceKind());
 971             try {
 972                 // There are 4 entities in play here:
 973                 //   * LC: lookupClass
 974                 //   * REFC: symbolic reference class (MN.clazz before resolution);
 975                 //   * DEFC: resolved method holder (MN.clazz after resolution);
 976                 //   * PTYPES: parameter types (MN.type)
 977                 //
 978                 // What we care about when resolving a MemberName is consistency between DEFC and PTYPES.
 979                 // We do type alias (TA) checks on DEFC to ensure that. DEFC is not known until the JVM
 980                 // finishes the resolution, so do TA checks right after MHN.resolve() is over.
 981                 //
 982                 // All parameters passed by a caller are checked against MH type (PTYPES) on every invocation,
 983                 // so it is safe to call a MH from any context.
 984                 //
 985                 // REFC view on PTYPES doesn't matter, since it is used only as a starting point for resolution and doesn't
 986                 // participate in method selection.
 987                 m = MethodHandleNatives.resolve(m, lookupClass, allowedModes, speculativeResolve);
 988                 if (m == null && speculativeResolve) {
 989                     return null;
 990                 }
 991                 m.checkForTypeAlias(m.getDeclaringClass());
 992                 m.resolution = null;
 993             } catch (ClassNotFoundException | LinkageError ex) {
 994                 // JVM reports that the "bytecode behavior" would get an error
 995                 assert(!m.isResolved());
 996                 m.resolution = ex;
 997                 return m;
 998             }
 999             assert(m.referenceKindIsConsistent());
1000             m.initResolved(true);
1001             assert(m.vminfoIsConsistent());
1002             return m;
1003         }
1004         /** Produce a resolved version of the given member.
1005          *  Super types are searched (for inherited members) if {@code searchSupers} is true.
1006          *  Access checking is performed on behalf of the given {@code lookupClass}.
1007          *  If lookup fails or access is not permitted, a {@linkplain ReflectiveOperationException} is thrown.
1008          *  Otherwise a fresh copy of the given member is returned, with modifier bits filled in.
1009          */
1010         public <NoSuchMemberException extends ReflectiveOperationException>
1011                 MemberName resolveOrFail(byte refKind, MemberName m,
1012                                          Class<?> lookupClass, int allowedModes,
1013                                          Class<NoSuchMemberException> nsmClass)
1014                 throws IllegalAccessException, NoSuchMemberException {
1015             assert lookupClass != null || allowedModes == LM_TRUSTED;
1016             MemberName result = resolve(refKind, m, lookupClass, allowedModes, false);
1017             if (result.isResolved())
1018                 return result;
1019             ReflectiveOperationException ex = result.makeAccessException();
1020             if (ex instanceof IllegalAccessException iae) throw iae;
1021             throw nsmClass.cast(ex);
1022         }
1023         /** Produce a resolved version of the given member.
1024          *  Super types are searched (for inherited members) if {@code searchSupers} is true.
1025          *  Access checking is performed on behalf of the given {@code lookupClass}.
1026          *  If lookup fails or access is not permitted, return null.
1027          *  Otherwise a fresh copy of the given member is returned, with modifier bits filled in.
1028          */
1029         public MemberName resolveOrNull(byte refKind, MemberName m, Class<?> lookupClass, int allowedModes) {
1030             assert lookupClass != null || allowedModes == LM_TRUSTED;
1031             MemberName result = resolve(refKind, m, lookupClass, allowedModes, true);
1032             if (result != null && result.isResolved())
1033                 return result;
1034             return null;
1035         }
1036     }
1037 }