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| 1 | +/* | |
| 2 | + * Copyright (c) 1997, 2003, 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 sun.tools.tree; | |
| 27 | + | |
| 28 | +import sun.tools.java.*; | |
| 29 | +import sun.tools.tree.*; | |
| 30 | +import sun.tools.asm.Assembler; | |
| 31 | + | |
| 32 | +/** | |
| 33 | + * A reference from one scope to another. | |
| 34 | + * | |
| 35 | + * WARNING: The contents of this source file are not part of any | |
| 36 | + * supported API. Code that depends on them does so at its own risk: | |
| 37 | + * they are subject to change or removal without notice. | |
| 38 | + * | |
| 39 | + */ | |
| 40 | + | |
| 41 | +public | |
| 42 | +class UplevelReference implements Constants { | |
| 43 | + /** | |
| 44 | + * The class in which the reference occurs. | |
| 45 | + */ | |
| 46 | + ClassDefinition client; | |
| 47 | + | |
| 48 | + /** | |
| 49 | + * The field being referenced. | |
| 50 | + * It is always a final argument or a final local variable. | |
| 51 | + * (An uplevel reference to a field of a class C is fetched | |
| 52 | + * through an implicit uplevel reference to C.this, which is | |
| 53 | + * an argument.) | |
| 54 | + */ | |
| 55 | + LocalMember target; | |
| 56 | + | |
| 57 | + /** | |
| 58 | + * The local variable which bears a copy of the target's value, | |
| 59 | + * for all methods of the client class. | |
| 60 | + * Its name is "this$C" for <code>this.C</code> or | |
| 61 | + * "val$x" for other target variables <code>x</code>. | |
| 62 | + * <p> | |
| 63 | + * This local variable is always a constructor argument, | |
| 64 | + * and is therefore usable only in the constructor and in initializers. | |
| 65 | + * All other methods use the local field. | |
| 66 | + * @see #localField | |
| 67 | + */ | |
| 68 | + LocalMember localArgument; | |
| 69 | + | |
| 70 | + /** | |
| 71 | + * A private synthetic field of the client class which | |
| 72 | + * bears a copy of the target's value. | |
| 73 | + * The compiler tries to avoid creating it if possible. | |
| 74 | + * The field has the same name and type as the localArgument. | |
| 75 | + * @see #localArgument | |
| 76 | + */ | |
| 77 | + MemberDefinition localField; | |
| 78 | + | |
| 79 | + /** | |
| 80 | + * The next item on the references list of the client. | |
| 81 | + */ | |
| 82 | + UplevelReference next; | |
| 83 | + | |
| 84 | + /** | |
| 85 | + * constructor | |
| 86 | + */ | |
| 87 | + public UplevelReference(ClassDefinition client, LocalMember target) { | |
| 88 | + this.client = client; | |
| 89 | + this.target = target; | |
| 90 | + | |
| 91 | + // Choose a name and build a variable declaration node. | |
| 92 | + Identifier valName; | |
| 93 | + if (target.getName().equals(idThis)) { | |
| 94 | + ClassDefinition tc = target.getClassDefinition(); | |
| 95 | + // It should always be true that tc.enclosingClassOf(client). | |
| 96 | + // If it were false, the numbering scheme would fail | |
| 97 | + // to produce unique names, since we'd be trying | |
| 98 | + // to number classes which were not in the sequence | |
| 99 | + // of enclosing scopes. The next paragraph of this | |
| 100 | + // code robustly deals with that possibility, however, | |
| 101 | + // by detecting name collisions and perturbing the names. | |
| 102 | + int depth = 0; | |
| 103 | + for (ClassDefinition pd = tc; !pd.isTopLevel(); pd = pd.getOuterClass()) { | |
| 104 | + // The inner classes specification states that the name of | |
| 105 | + // a private field containing a reference to the outermost | |
| 106 | + // enclosing instance is named "this$0". That outermost | |
| 107 | + // enclosing instance is always the innermost toplevel class. | |
| 108 | + depth += 1; | |
| 109 | + } | |
| 110 | + // In this example, T1,T2,T3 are all top-level (static), | |
| 111 | + // while I4,I5,I6,I7 are all inner. Each of the inner classes | |
| 112 | + // will have a single up-level "this$N" reference to the next | |
| 113 | + // class out. Only the outermost "this$0" will refer to a | |
| 114 | + // top-level class, T3. | |
| 115 | + // | |
| 116 | + // class T1 { | |
| 117 | + // static class T2 { | |
| 118 | + // static class T3 { | |
| 119 | + // class I4 { | |
| 120 | + // class I5 { | |
| 121 | + // class I6 { | |
| 122 | + // // at this point we have these fields in various places: | |
| 123 | + // // I4 this$0; I5 this$1; I6 this$2; | |
| 124 | + // } | |
| 125 | + // } | |
| 126 | + // class I7 { | |
| 127 | + // // I4 this$0; I7 this$1; | |
| 128 | + // } | |
| 129 | + // } | |
| 130 | + // } | |
| 131 | + // } | |
| 132 | + // } | |
| 133 | + valName = Identifier.lookup(prefixThis + depth); | |
| 134 | + } else { | |
| 135 | + valName = Identifier.lookup(prefixVal + target.getName()); | |
| 136 | + } | |
| 137 | + | |
| 138 | + // Make reasonably certain that valName is unique to this client. | |
| 139 | + // (This check can be fooled by malicious naming of explicit | |
| 140 | + // constructor arguments, or of inherited fields.) | |
| 141 | + Identifier base = valName; | |
| 142 | + int tick = 0; | |
| 143 | + while (true) { | |
| 144 | + boolean failed = (client.getFirstMatch(valName) != null); | |
| 145 | + for (UplevelReference r = client.getReferences(); | |
| 146 | + r != null; r = r.next) { | |
| 147 | + if (r.target.getName().equals(valName)) { | |
| 148 | + failed = true; | |
| 149 | + } | |
| 150 | + } | |
| 151 | + if (!failed) { | |
| 152 | + break; | |
| 153 | + } | |
| 154 | + // try another name | |
| 155 | + valName = Identifier.lookup(base + "$" + (++tick)); | |
| 156 | + } | |
| 157 | + | |
| 158 | + // Build the constructor argument. | |
| 159 | + // Like "this", it wil be shared equally by all constructors of client. | |
| 160 | + localArgument = new LocalMember(target.getWhere(), | |
| 161 | + client, | |
| 162 | + M_FINAL | M_SYNTHETIC, | |
| 163 | + target.getType(), | |
| 164 | + valName); | |
| 165 | + } | |
| 166 | + | |
| 167 | + /** | |
| 168 | + * Insert self into a list of references. | |
| 169 | + * Maintain "isEarlierThan" as an invariant of the list. | |
| 170 | + * This is important (a) to maximize stability of signatures, | |
| 171 | + * and (b) to allow uplevel "this" parameters to come at the | |
| 172 | + * front of every argument list they appear in. | |
| 173 | + */ | |
| 174 | + public UplevelReference insertInto(UplevelReference references) { | |
| 175 | + if (references == null || isEarlierThan(references)) { | |
| 176 | + next = references; | |
| 177 | + return this; | |
| 178 | + } else { | |
| 179 | + UplevelReference prev = references; | |
| 180 | + while (!(prev.next == null || isEarlierThan(prev.next))) { | |
| 181 | + prev = prev.next; | |
| 182 | + } | |
| 183 | + next = prev.next; | |
| 184 | + prev.next = this; | |
| 185 | + return references; | |
| 186 | + } | |
| 187 | + } | |
| 188 | + | |
| 189 | + /** | |
| 190 | + * Tells if self precedes the other in the canonical ordering. | |
| 191 | + */ | |
| 192 | + public final boolean isEarlierThan(UplevelReference other) { | |
| 193 | + // Outer fields always come first. | |
| 194 | + if (isClientOuterField()) { | |
| 195 | + return true; | |
| 196 | + } else if (other.isClientOuterField()) { | |
| 197 | + return false; | |
| 198 | + } | |
| 199 | + | |
| 200 | + // Now it doesn't matter what the order is; use string comparison. | |
| 201 | + LocalMember target2 = other.target; | |
| 202 | + Identifier name = target.getName(); | |
| 203 | + Identifier name2 = target2.getName(); | |
| 204 | + int cmp = name.toString().compareTo(name2.toString()); | |
| 205 | + if (cmp != 0) { | |
| 206 | + return cmp < 0; | |
| 207 | + } | |
| 208 | + Identifier cname = target.getClassDefinition().getName(); | |
| 209 | + Identifier cname2 = target2.getClassDefinition().getName(); | |
| 210 | + int ccmp = cname.toString().compareTo(cname2.toString()); | |
| 211 | + return ccmp < 0; | |
| 212 | + } | |
| 213 | + | |
| 214 | + /** | |
| 215 | + * the target of this reference | |
| 216 | + */ | |
| 217 | + public final LocalMember getTarget() { | |
| 218 | + return target; | |
| 219 | + } | |
| 220 | + | |
| 221 | + /** | |
| 222 | + * the local argument for this reference | |
| 223 | + */ | |
| 224 | + public final LocalMember getLocalArgument() { | |
| 225 | + return localArgument; | |
| 226 | + } | |
| 227 | + | |
| 228 | + /** | |
| 229 | + * the field allocated in the client for this reference | |
| 230 | + */ | |
| 231 | + public final MemberDefinition getLocalField() { | |
| 232 | + return localField; | |
| 233 | + } | |
| 234 | + | |
| 235 | + /** | |
| 236 | + * Get the local field, creating one if necessary. | |
| 237 | + * The client class must not be frozen. | |
| 238 | + */ | |
| 239 | + public final MemberDefinition getLocalField(Environment env) { | |
| 240 | + if (localField == null) { | |
| 241 | + makeLocalField(env); | |
| 242 | + } | |
| 243 | + return localField; | |
| 244 | + } | |
| 245 | + | |
| 246 | + /** | |
| 247 | + * the client class | |
| 248 | + */ | |
| 249 | + public final ClassDefinition getClient() { | |
| 250 | + return client; | |
| 251 | + } | |
| 252 | + | |
| 253 | + /** | |
| 254 | + * the next reference in the client's list | |
| 255 | + */ | |
| 256 | + public final UplevelReference getNext() { | |
| 257 | + return next; | |
| 258 | + } | |
| 259 | + | |
| 260 | + /** | |
| 261 | + * Tell if this uplevel reference is the up-level "this" pointer | |
| 262 | + * of an inner class. Such references are treated differently | |
| 263 | + * than others, because they affect constructor calls across | |
| 264 | + * compilation units. | |
| 265 | + */ | |
| 266 | + public boolean isClientOuterField() { | |
| 267 | + MemberDefinition outerf = client.findOuterMember(); | |
| 268 | + return (outerf != null) && (localField == outerf); | |
| 269 | + } | |
| 270 | + | |
| 271 | + /** | |
| 272 | + * Tell if my local argument is directly available in this context. | |
| 273 | + * If not, the uplevel reference will have to be via a class field. | |
| 274 | + * <p> | |
| 275 | + * This must be called in a context which is local | |
| 276 | + * to the client of the uplevel reference. | |
| 277 | + */ | |
| 278 | + public boolean localArgumentAvailable(Environment env, Context ctx) { | |
| 279 | + MemberDefinition reff = ctx.field; | |
| 280 | + if (reff.getClassDefinition() != client) { | |
| 281 | + throw new CompilerError("localArgumentAvailable"); | |
| 282 | + } | |
| 283 | + return ( reff.isConstructor() | |
| 284 | + || reff.isVariable() | |
| 285 | + || reff.isInitializer() ); | |
| 286 | + } | |
| 287 | + | |
| 288 | + /** | |
| 289 | + * Process an uplevel reference. | |
| 290 | + * The only decision to make at this point is whether | |
| 291 | + * to build a "localField" instance variable, which | |
| 292 | + * is done (lazily) when localArgumentAvailable() proves false. | |
| 293 | + */ | |
| 294 | + public void noteReference(Environment env, Context ctx) { | |
| 295 | + if (localField == null && !localArgumentAvailable(env, ctx)) { | |
| 296 | + // We need an instance variable unless client is a constructor. | |
| 297 | + makeLocalField(env); | |
| 298 | + } | |
| 299 | + } | |
| 300 | + | |
| 301 | + private void makeLocalField(Environment env) { | |
| 302 | + // Cannot alter decisions like this one at a late date. | |
| 303 | + client.referencesMustNotBeFrozen(); | |
| 304 | + int mod = M_PRIVATE | M_FINAL | M_SYNTHETIC; | |
| 305 | + localField = env.makeMemberDefinition(env, | |
| 306 | + localArgument.getWhere(), | |
| 307 | + client, null, | |
| 308 | + mod, | |
| 309 | + localArgument.getType(), | |
| 310 | + localArgument.getName(), | |
| 311 | + null, null, null); | |
| 312 | + } | |
| 313 | + | |
| 314 | + /** | |
| 315 | + * Assuming noteReference() is all taken care of, | |
| 316 | + * build an uplevel reference. | |
| 317 | + * <p> | |
| 318 | + * This must be called in a context which is local | |
| 319 | + * to the client of the uplevel reference. | |
| 320 | + */ | |
| 321 | + public Expression makeLocalReference(Environment env, Context ctx) { | |
| 322 | + if (ctx.field.getClassDefinition() != client) { | |
| 323 | + throw new CompilerError("makeLocalReference"); | |
| 324 | + } | |
| 325 | + if (localArgumentAvailable(env, ctx)) { | |
| 326 | + return new IdentifierExpression(0, localArgument); | |
| 327 | + } else { | |
| 328 | + return makeFieldReference(env, ctx); | |
| 329 | + } | |
| 330 | + } | |
| 331 | + | |
| 332 | + /** | |
| 333 | + * As with makeLocalReference(), build a locally-usable reference. | |
| 334 | + * Ignore the availability of local arguments; always use a class field. | |
| 335 | + */ | |
| 336 | + public Expression makeFieldReference(Environment env, Context ctx) { | |
| 337 | + Expression e = ctx.findOuterLink(env, 0, localField); | |
| 338 | + return new FieldExpression(0, e, localField); | |
| 339 | + } | |
| 340 | + | |
| 341 | + /** | |
| 342 | + * During the inline phase, call this on a list of references | |
| 343 | + * for which the code phase will later emit arguments. | |
| 344 | + * It will make sure that any "double-uplevel" values | |
| 345 | + * needed by the callee are also present at the call site. | |
| 346 | + * <p> | |
| 347 | + * If any reference is a "ClientOuterField", it is skipped | |
| 348 | + * by this method (and by willCodeArguments). This is because | |
| 349 | + */ | |
| 350 | + public void willCodeArguments(Environment env, Context ctx) { | |
| 351 | + if (!isClientOuterField()) { | |
| 352 | + ctx.noteReference(env, target); | |
| 353 | + } | |
| 354 | + | |
| 355 | + if (next != null) { | |
| 356 | + next.willCodeArguments(env, ctx); | |
| 357 | + } | |
| 358 | + } | |
| 359 | + | |
| 360 | + /** | |
| 361 | + * Code is being generated for a call to a constructor of | |
| 362 | + * the client class. Push an argument for the constructor. | |
| 363 | + */ | |
| 364 | + public void codeArguments(Environment env, Context ctx, Assembler asm, | |
| 365 | + long where, MemberDefinition conField) { | |
| 366 | + if (!isClientOuterField()) { | |
| 367 | + Expression e = ctx.makeReference(env, target); | |
| 368 | + e.codeValue(env, ctx, asm); | |
| 369 | + } | |
| 370 | + | |
| 371 | + if (next != null) { | |
| 372 | + next.codeArguments(env, ctx, asm, where, conField); | |
| 373 | + } | |
| 374 | + } | |
| 375 | + | |
| 376 | + /** | |
| 377 | + * Code is being generated for a constructor of the client class. | |
| 378 | + * Emit code which initializes the instance. | |
| 379 | + */ | |
| 380 | + public void codeInitialization(Environment env, Context ctx, Assembler asm, | |
| 381 | + long where, MemberDefinition conField) { | |
| 382 | + // If the reference is a clientOuterField, then the initialization | |
| 383 | + // code is generated in MethodExpression.makeVarInits(). | |
| 384 | + // (Fix for bug 4075063.) | |
| 385 | + if (localField != null && !isClientOuterField()) { | |
| 386 | + Expression e = ctx.makeReference(env, target); | |
| 387 | + Expression f = makeFieldReference(env, ctx); | |
| 388 | + e = new AssignExpression(e.getWhere(), f, e); | |
| 389 | + e.type = localField.getType(); | |
| 390 | + e.code(env, ctx, asm); | |
| 391 | + } | |
| 392 | + | |
| 393 | + if (next != null) { | |
| 394 | + next.codeInitialization(env, ctx, asm, where, conField); | |
| 395 | + } | |
| 396 | + } | |
| 397 | + | |
| 398 | + public String toString() { | |
| 399 | + return "[" + localArgument + " in " + client + "]"; | |
| 400 | + } | |
| 401 | +} | |