| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.impl.services.bytecode.BCMethod |
| 4 | |
| 5 | Copyright 1997, 2005 The Apache Software Foundation or its licensors, as applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.impl.services.bytecode; |
| 22 | |
| 23 | import org.apache.derby.iapi.services.compiler.ClassBuilder; |
| 24 | import org.apache.derby.iapi.services.compiler.MethodBuilder; |
| 25 | import org.apache.derby.iapi.services.classfile.ClassFormatOutput; |
| 26 | import org.apache.derby.iapi.services.compiler.LocalField; |
| 27 | import org.apache.derby.iapi.services.classfile.ClassHolder; |
| 28 | import org.apache.derby.iapi.services.classfile.ClassMember; |
| 29 | |
| 30 | import org.apache.derby.iapi.services.sanity.SanityManager; |
| 31 | |
| 32 | import org.apache.derby.iapi.services.classfile.VMDescriptor; |
| 33 | import org.apache.derby.iapi.services.classfile.VMOpcode; |
| 34 | |
| 35 | import java.lang.reflect.Modifier; |
| 36 | import java.util.Vector; |
| 37 | import java.io.IOException; |
| 38 | |
| 39 | /** |
| 40 | * MethodBuilder is used to piece together a method when |
| 41 | * building a java class definition. |
| 42 | * <p> |
| 43 | * When a method is first created, it has: |
| 44 | * <ul> |
| 45 | * <li> a return type |
| 46 | * <li> modifiers |
| 47 | * <li> a name |
| 48 | * <li> an empty parameter list |
| 49 | * <li> an empty throws list |
| 50 | * <li> an empty statement block |
| 51 | * </ul> |
| 52 | * <p> |
| 53 | * MethodBuilder implementations are required to supply a way for |
| 54 | * Statements and Expressions to give them code. Most typically, they may have |
| 55 | * a stream to which their contents writes the code that is of |
| 56 | * the type to satisfy what the contents represent. |
| 57 | * MethodBuilder implementations also have to have a way to supply |
| 58 | * ClassBuilders with their code, that satisfies the type of class |
| 59 | * builder they are implemented with. This is implementation-dependent, |
| 60 | * so ClassBuilders, MethodBuilders, Statements, and Expressions all have |
| 61 | * to be of the same implementation in order to interact to generate a class. |
| 62 | * <p> |
| 63 | * Method Builder implementation for generating bytecode. |
| 64 | * |
| 65 | */ |
| 66 | class BCMethod implements MethodBuilder { |
| 67 | |
| 68 | /** |
| 69 | * Code length at which to split into sub-methods. |
| 70 | * Normally set to the maximim code length the |
| 71 | * JVM can support, but for testing the split code |
| 72 | * it can be reduced so that the standard tests |
| 73 | * cause some splitting. Tested with value set to 2000. |
| 74 | */ |
| 75 | static final int CODE_SPLIT_LENGTH = VMOpcode.MAX_CODE_LENGTH; |
| 76 | |
| 77 | final BCClass cb; |
| 78 | protected final ClassHolder modClass; // the class it is in (modifiable fmt) |
| 79 | private final String myReturnType; |
| 80 | |
| 81 | /** |
| 82 | * The original name of the method, this |
| 83 | * represents how any user would call this method. |
| 84 | */ |
| 85 | private final String myName; |
| 86 | |
| 87 | /** |
| 88 | * Fast access for the parametes, will be null |
| 89 | * if the method has no parameters. |
| 90 | */ |
| 91 | BCLocalField[] parameters; |
| 92 | |
| 93 | /** |
| 94 | * List of parameter types with java language class names. |
| 95 | * Can be null or zero length for no parameters. |
| 96 | */ |
| 97 | private final String[] parameterTypes; |
| 98 | |
| 99 | |
| 100 | Vector thrownExceptions; // expected to be names of Classes under Throwable |
| 101 | |
| 102 | CodeChunk myCode; |
| 103 | protected ClassMember myEntry; |
| 104 | |
| 105 | private int currentVarNum; |
| 106 | private int statementNum; |
| 107 | |
| 108 | /** |
| 109 | * True if we are currently switching control |
| 110 | * over to a sub method to avoid hitting the code generation |
| 111 | * limit of 65535 bytes per method. |
| 112 | */ |
| 113 | private boolean handlingOverflow; |
| 114 | |
| 115 | /** |
| 116 | * How many sub-methods we have overflowed to. |
| 117 | */ |
| 118 | private int subMethodCount; |
| 119 | |
| 120 | BCMethod(ClassBuilder cb, |
| 121 | String returnType, |
| 122 | String methodName, |
| 123 | int modifiers, |
| 124 | String[] parms, |
| 125 | BCJava factory) { |
| 126 | |
| 127 | this.cb = (BCClass) cb; |
| 128 | modClass = this.cb.modify(); |
| 129 | myReturnType = returnType; |
| 130 | myName = methodName; |
| 131 | |
| 132 | if (SanityManager.DEBUG) { |
| 133 | this.cb.validateType(returnType); |
| 134 | } |
| 135 | |
| 136 | // if the method is not static, allocate for "this". |
| 137 | if ((modifiers & Modifier.STATIC) == 0 ) |
| 138 | currentVarNum = 1; |
| 139 | |
| 140 | String[] vmParamterTypes; |
| 141 | |
| 142 | if (parms != null && parms.length != 0) { |
| 143 | int len = parms.length; |
| 144 | vmParamterTypes = new String[len]; |
| 145 | parameters = new BCLocalField[len]; |
| 146 | for (int i = 0; i < len; i++) { |
| 147 | Type t = factory.type(parms[i]); |
| 148 | parameters[i] = new BCLocalField(t, currentVarNum); |
| 149 | currentVarNum += t.width(); |
| 150 | |
| 151 | // convert to vmname for the BCMethodDescriptor.get() call |
| 152 | vmParamterTypes[i] = t.vmName(); |
| 153 | } |
| 154 | } |
| 155 | else |
| 156 | vmParamterTypes = BCMethodDescriptor.EMPTY; |
| 157 | |
| 158 | // create a code attribute |
| 159 | String sig = BCMethodDescriptor.get(vmParamterTypes, factory.type(returnType).vmName(), factory); |
| 160 | |
| 161 | // stuff the completed information into the class. |
| 162 | myEntry = modClass.addMember(methodName, sig, modifiers); |
| 163 | |
| 164 | // get code chunk |
| 165 | myCode = new CodeChunk(); |
| 166 | |
| 167 | parameterTypes = parms; |
| 168 | } |
| 169 | // |
| 170 | // MethodBuilder interface |
| 171 | // |
| 172 | |
| 173 | /** |
| 174 | * Return the logical name of the method. The current |
| 175 | * myEntry refers to the sub method we are currently |
| 176 | * overflowing to. Those sub-methods are hidden from any caller. |
| 177 | */ |
| 178 | public String getName() { |
| 179 | return myName; |
| 180 | } |
| 181 | |
| 182 | public void getParameter(int id) { |
| 183 | |
| 184 | int num = parameters[id].cpi; |
| 185 | short typ = parameters[id].type.vmType(); |
| 186 | if (num < 4) |
| 187 | myCode.addInstr((short) (CodeChunk.LOAD_VARIABLE_FAST[typ]+num)); |
| 188 | else |
| 189 | myCode.addInstrWide(CodeChunk.LOAD_VARIABLE[typ], num); |
| 190 | |
| 191 | growStack(parameters[id].type); |
| 192 | } |
| 193 | |
| 194 | /** |
| 195 | * a throwable can be added to the end of |
| 196 | * the list of thrownExceptions. |
| 197 | */ |
| 198 | public void addThrownException(String exceptionClass) { |
| 199 | |
| 200 | // cannot add exceptions after code generation has started. |
| 201 | // Allowing this would cause the method overflow/split to |
| 202 | // break as the top-level method would not have the exception |
| 203 | // added in the sub method. |
| 204 | if (SanityManager.DEBUG) |
| 205 | { |
| 206 | if (myCode.getPC() != 0) |
| 207 | SanityManager.THROWASSERT("Adding exception after code generation " + exceptionClass |
| 208 | + " to method " + getName()); |
| 209 | } |
| 210 | |
| 211 | if (thrownExceptions == null) |
| 212 | thrownExceptions = new Vector(); |
| 213 | thrownExceptions.addElement(exceptionClass); |
| 214 | } |
| 215 | |
| 216 | /** |
| 217 | * when the method has had all of its parameters |
| 218 | * and thrown exceptions defined, and its statement |
| 219 | * block has been completed, it can be completed and |
| 220 | * its class file information generated. |
| 221 | * <p> |
| 222 | * further alterations of the method will not be |
| 223 | * reflected in the code generated for it. |
| 224 | */ |
| 225 | public void complete() { |
| 226 | |
| 227 | // myCode.getPC() gives the code length since |
| 228 | // the program counter will be positioned after |
| 229 | // the last instruction. Note this value can |
| 230 | // be changed by the splitMethod call. |
| 231 | |
| 232 | if (myCode.getPC() > CODE_SPLIT_LENGTH) |
| 233 | splitMethod(); |
| 234 | |
| 235 | // write exceptions attribute info |
| 236 | writeExceptions(); |
| 237 | |
| 238 | // get the code attribute to put itself into the class |
| 239 | // provide the final header information needed |
| 240 | myCode.complete(this, modClass, myEntry, maxStack, currentVarNum); |
| 241 | } |
| 242 | |
| 243 | /** |
| 244 | * Attempt to split a large method by pushing code out to several |
| 245 | * sub-methods. Performs a number of steps. |
| 246 | * <OL> |
| 247 | * <LI> Split at zero stack depth. |
| 248 | * <LI> Split at non-zero stack depth (FUTURE) |
| 249 | * </OL> |
| 250 | * |
| 251 | * If the class has already exceeded some limit in building the |
| 252 | * class file format structures then don't attempt to split. |
| 253 | * Most likely the number of constant pool entries has been exceeded |
| 254 | * and thus the built class file no longer has integrity. |
| 255 | * The split code relies on being able to read the in-memory |
| 256 | * version of the class file in order to determine descriptors |
| 257 | * for methods and fields. |
| 258 | */ |
| 259 | private void splitMethod() { |
| 260 | |
| 261 | int split_pc = 0; |
| 262 | for (int codeLength = myCode.getPC(); |
| 263 | (cb.limitMsg == null) && |
| 264 | (codeLength > CODE_SPLIT_LENGTH); |
| 265 | codeLength = myCode.getPC()) |
| 266 | { |
| 267 | int lengthToCheck = codeLength - split_pc; |
| 268 | |
| 269 | int optimalMinLength; |
| 270 | if (codeLength < CODE_SPLIT_LENGTH * 2) { |
| 271 | // minimum required |
| 272 | optimalMinLength = codeLength - CODE_SPLIT_LENGTH; |
| 273 | } else { |
| 274 | // try to split as much as possible |
| 275 | // need one for the return instruction |
| 276 | optimalMinLength = CODE_SPLIT_LENGTH - 1; |
| 277 | } |
| 278 | |
| 279 | if (optimalMinLength > lengthToCheck) |
| 280 | optimalMinLength = lengthToCheck; |
| 281 | |
| 282 | split_pc = myCode.splitZeroStack(this, modClass, split_pc, |
| 283 | lengthToCheck, optimalMinLength); |
| 284 | |
| 285 | // Negative split point returned means that no split |
| 286 | // was possible. Give up on this approach and goto |
| 287 | // the next approach (none-yet). |
| 288 | if (split_pc < 0) { |
| 289 | break; |
| 290 | } |
| 291 | |
| 292 | // success, continue on splitting after the call to the |
| 293 | // sub-method if the method still execeeds the maximum length. |
| 294 | } |
| 295 | } |
| 296 | |
| 297 | /* |
| 298 | * class interface |
| 299 | */ |
| 300 | |
| 301 | /** |
| 302 | * In their giveCode methods, the parts of the method body will want to get |
| 303 | * to the constant pool to add their constants. We really only want them |
| 304 | * treating it like a constant pool inclusion mechanism, we could write a |
| 305 | * wrapper to limit it to that. |
| 306 | */ |
| 307 | ClassHolder constantPool() { |
| 308 | return modClass; |
| 309 | } |
| 310 | |
| 311 | |
| 312 | // |
| 313 | // Class implementation |
| 314 | // |
| 315 | |
| 316 | |
| 317 | /** |
| 318 | * sets exceptionBytes to the attribute_info needed |
| 319 | * for a method's Exceptions attribute. |
| 320 | * The ClassUtilities take care of the header 6 bytes for us, |
| 321 | * so they are not included here. |
| 322 | * See The Java Virtual Machine Specification Section 4.7.5, |
| 323 | * Exceptions attribute. |
| 324 | */ |
| 325 | protected void writeExceptions() { |
| 326 | if (thrownExceptions == null) |
| 327 | return; |
| 328 | |
| 329 | int numExc = thrownExceptions.size(); |
| 330 | |
| 331 | // don't write an Exceptions attribute if there are no exceptions. |
| 332 | if (numExc != 0) { |
| 333 | |
| 334 | try{ |
| 335 | ClassFormatOutput eout = new ClassFormatOutput((numExc * 2) + 2); |
| 336 | |
| 337 | eout.putU2(numExc); // number_of_exceptions |
| 338 | |
| 339 | for (int i = 0; i < numExc; i++) { |
| 340 | // put each exception into the constant pool |
| 341 | String e = thrownExceptions.elementAt(i).toString(); |
| 342 | int ei2 = modClass.addClassReference(e); |
| 343 | |
| 344 | // add constant pool index to exception attribute_info |
| 345 | eout.putU2(ei2); |
| 346 | } |
| 347 | |
| 348 | myEntry.addAttribute("Exceptions", eout); |
| 349 | |
| 350 | } catch (IOException ioe) { |
| 351 | } |
| 352 | } |
| 353 | } |
| 354 | |
| 355 | /* |
| 356 | ** New push compiler api. |
| 357 | */ |
| 358 | |
| 359 | /** |
| 360 | * Array of the current types of the values on the stack. |
| 361 | * A type that types up two words on the stack, e.g. double |
| 362 | * will only occupy one element in this array. |
| 363 | * This array is dynamically re-sized as needed. |
| 364 | */ |
| 365 | private Type[] stackTypes = new Type[8]; |
| 366 | |
| 367 | /** |
| 368 | * Points to the next array offset in stackTypes |
| 369 | * to be used. Really it's the number of valid entries |
| 370 | * in stackTypes. |
| 371 | */ |
| 372 | private int stackTypeOffset; |
| 373 | |
| 374 | /** |
| 375 | * Maximum stack depth seen in this method, measured in words. |
| 376 | * Corresponds to max_stack in the Code attribute of section 4.7.3 |
| 377 | * of the vm spec. |
| 378 | */ |
| 379 | int maxStack; |
| 380 | |
| 381 | /** |
| 382 | * Current stack depth in this method, measured in words. |
| 383 | */ |
| 384 | private int stackDepth; |
| 385 | |
| 386 | private void growStack(int size, Type type) { |
| 387 | stackDepth += size; |
| 388 | if (stackDepth > maxStack) |
| 389 | maxStack = stackDepth; |
| 390 | |
| 391 | if (stackTypeOffset >= stackTypes.length) { |
| 392 | |
| 393 | Type[] newStackTypes = new Type[stackTypes.length + 8]; |
| 394 | System.arraycopy(stackTypes, 0, newStackTypes, 0, stackTypes.length); |
| 395 | stackTypes = newStackTypes; |
| 396 | } |
| 397 | |
| 398 | stackTypes[stackTypeOffset++] = type; |
| 399 | |
| 400 | if (SanityManager.DEBUG) { |
| 401 | |
| 402 | int sum = 0; |
| 403 | for (int i = 0 ; i < stackTypeOffset; i++) { |
| 404 | sum += stackTypes[i].width(); |
| 405 | } |
| 406 | if (sum != stackDepth) { |
| 407 | SanityManager.THROWASSERT("invalid stack depth " + stackDepth + " calc " + sum); |
| 408 | } |
| 409 | } |
| 410 | } |
| 411 | |
| 412 | private void growStack(Type type) { |
| 413 | growStack(type.width(), type); |
| 414 | } |
| 415 | |
| 416 | private Type popStack() { |
| 417 | stackTypeOffset--; |
| 418 | Type topType = stackTypes[stackTypeOffset]; |
| 419 | stackDepth -= topType.width(); |
| 420 | return topType; |
| 421 | |
| 422 | } |
| 423 | |
| 424 | private Type[] copyStack() |
| 425 | { |
| 426 | Type[] stack = new Type[stackTypeOffset]; |
| 427 | System.arraycopy(stackTypes, 0, stack, 0, stackTypeOffset); |
| 428 | return stack; |
| 429 | } |
| 430 | |
| 431 | public void pushThis() { |
| 432 | myCode.addInstr(VMOpcode.ALOAD_0); |
| 433 | growStack(1, cb.classType); |
| 434 | } |
| 435 | |
| 436 | public void push(byte value) { |
| 437 | push(value, Type.BYTE); |
| 438 | } |
| 439 | |
| 440 | public void push(boolean value) { |
| 441 | push(value ? 1 : 0, Type.BOOLEAN); |
| 442 | } |
| 443 | |
| 444 | public void push(short value) { |
| 445 | push(value, Type.SHORT); |
| 446 | } |
| 447 | |
| 448 | public void push(int value) { |
| 449 | push(value, Type.INT); |
| 450 | } |
| 451 | |
| 452 | public void dup() { |
| 453 | Type dup = popStack(); |
| 454 | myCode.addInstr(dup.width() == 2 ? VMOpcode.DUP2 : VMOpcode.DUP); |
| 455 | growStack(dup); |
| 456 | growStack(dup); |
| 457 | |
| 458 | } |
| 459 | |
| 460 | public void swap() { |
| 461 | |
| 462 | // have A,B |
| 463 | // want B,A |
| 464 | |
| 465 | Type wB = popStack(); |
| 466 | Type wA = popStack(); |
| 467 | growStack(wB); |
| 468 | growStack(wA); |
| 469 | |
| 470 | if (wB.width() == 1) { |
| 471 | // top value is one word |
| 472 | if (wA.width() == 1) { |
| 473 | myCode.addInstr(VMOpcode.SWAP); |
| 474 | return; |
| 475 | } else { |
| 476 | myCode.addInstr(VMOpcode.DUP_X2); |
| 477 | myCode.addInstr(VMOpcode.POP); |
| 478 | } |
| 479 | } else { |
| 480 | // top value is two words |
| 481 | if (wA.width() == 1) { |
| 482 | myCode.addInstr(VMOpcode.DUP2_X1); |
| 483 | myCode.addInstr(VMOpcode.POP2); |
| 484 | } else { |
| 485 | myCode.addInstr(VMOpcode.DUP2_X2); |
| 486 | myCode.addInstr(VMOpcode.POP2); |
| 487 | } |
| 488 | } |
| 489 | |
| 490 | // all except the simple swap push an extra |
| 491 | // copy of B which needs to be popped. |
| 492 | growStack(wB); |
| 493 | popStack(); |
| 494 | |
| 495 | } |
| 496 | |
| 497 | /** |
| 498 | * Push an integer value. Uses the special integer opcodes |
| 499 | * for the constants -1 to 5, BIPUSH for values that fit in |
| 500 | * a byte and SIPUSH for values that fit in a short. Otherwise |
| 501 | * uses LDC with a constant pool entry. |
| 502 | * |
| 503 | * @param value Value to be pushed |
| 504 | * @param type Final type of the value. |
| 505 | */ |
| 506 | private void push(int value, Type type) { |
| 507 | |
| 508 | CodeChunk chunk = myCode; |
| 509 | |
| 510 | if (value >= -1 && value <= 5) |
| 511 | chunk.addInstr((short)(VMOpcode.ICONST_0+value)); |
| 512 | else if (value >= Byte.MIN_VALUE && value <= Byte.MAX_VALUE) |
| 513 | chunk.addInstrU1(VMOpcode.BIPUSH,value); |
| 514 | else if (value >= Short.MIN_VALUE && value <= Short.MAX_VALUE) |
| 515 | chunk.addInstrU2(VMOpcode.SIPUSH,value); |
| 516 | else { |
| 517 | int cpe = modClass.addConstant(value); |
| 518 | addInstrCPE(VMOpcode.LDC, cpe); |
| 519 | } |
| 520 | growStack(type.width(), type); |
| 521 | |
| 522 | } |
| 523 | |
| 524 | /** |
| 525 | * Push a long value onto the stack. |
| 526 | * For the values zero and one the LCONST_0 and |
| 527 | * LCONST_1 instructions are used. |
| 528 | * For values betwee Short.MIN_VALUE and Short.MAX_VALUE |
| 529 | * inclusive an byte/short/int value is pushed |
| 530 | * using push(int, Type) followed by an I2L instruction. |
| 531 | * This saves using a constant pool entry for such values. |
| 532 | * All other values use a constant pool entry. For values |
| 533 | * in the range of an Integer an integer constant pool |
| 534 | * entry is created to allow sharing with integer constants |
| 535 | * and to reduce constant pool slot entries. |
| 536 | */ |
| 537 | public void push(long value) { |
| 538 | CodeChunk chunk = myCode; |
| 539 | |
| 540 | if (value == 0L || value == 1L) { |
| 541 | short opcode = value == 0L ? VMOpcode.LCONST_0 : VMOpcode.LCONST_1; |
| 542 | chunk.addInstr(opcode); |
| 543 | } else if (value >= Integer.MIN_VALUE && value <= Integer.MAX_VALUE) { |
| 544 | // the push(int, Type) method grows the stack for us. |
| 545 | push((int) value, Type.LONG); |
| 546 | chunk.addInstr(VMOpcode.I2L); |
| 547 | return; |
| 548 | } else { |
| 549 | int cpe = modClass.addConstant(value); |
| 550 | chunk.addInstrU2(VMOpcode.LDC2_W, cpe); |
| 551 | } |
| 552 | growStack(2, Type.LONG); |
| 553 | } |
| 554 | public void push(float value) { |
| 555 | |
| 556 | CodeChunk chunk = myCode; |
| 557 | |
| 558 | if (value == 0.0) |
| 559 | { |
| 560 | chunk.addInstr(VMOpcode.FCONST_0); |
| 561 | } |
| 562 | else if (value == 1.0) |
| 563 | { |
| 564 | chunk.addInstr(VMOpcode.FCONST_1); |
| 565 | } |
| 566 | else if (value == 2.0) |
| 567 | { |
| 568 | chunk.addInstr(VMOpcode.FCONST_2); |
| 569 | } |
| 570 | else |
| 571 | { |
| 572 | int cpe = modClass.addConstant(value); |
| 573 | addInstrCPE(VMOpcode.LDC, cpe); |
| 574 | } |
| 575 | growStack(1, Type.FLOAT); |
| 576 | } |
| 577 | |
| 578 | public void push(double value) { |
| 579 | CodeChunk chunk = myCode; |
| 580 | |
| 581 | if (value == 0.0) { |
| 582 | chunk.addInstr(VMOpcode.DCONST_0); |
| 583 | } |
| 584 | else { |
| 585 | int cpe = modClass.addConstant(value); |
| 586 | chunk.addInstrU2(VMOpcode.LDC2_W, cpe); |
| 587 | } |
| 588 | growStack(2, Type.DOUBLE); |
| 589 | } |
| 590 | public void push(String value) { |
| 591 | int cpe = modClass.addConstant(value); |
| 592 | addInstrCPE(VMOpcode.LDC, cpe); |
| 593 | growStack(1, Type.STRING); |
| 594 | } |
| 595 | |
| 596 | |
| 597 | public void methodReturn() { |
| 598 | |
| 599 | short opcode; |
| 600 | if (stackDepth != 0) { |
| 601 | Type topType = popStack(); |
| 602 | opcode = CodeChunk.RETURN_OPCODE[topType.vmType()]; |
| 603 | } else { |
| 604 | opcode = VMOpcode.RETURN; |
| 605 | } |
| 606 | |
| 607 | myCode.addInstr(opcode); |
| 608 | |
| 609 | if (SanityManager.DEBUG) { |
| 610 | if (stackDepth != 0) |
| 611 | SanityManager.THROWASSERT("items left on stack " + stackDepth); |
| 612 | } |
| 613 | } |
| 614 | |
| 615 | public Object describeMethod(short opcode, String declaringClass, String methodName, String returnType) { |
| 616 | |
| 617 | Type rt = cb.factory.type(returnType); |
| 618 | |
| 619 | String methodDescriptor = BCMethodDescriptor.get(BCMethodDescriptor.EMPTY, rt.vmName(), cb.factory); |
| 620 | |
| 621 | if ((declaringClass == null) && (opcode != VMOpcode.INVOKESTATIC)) { |
| 622 | |
| 623 | Type dt = stackTypes[stackTypeOffset - 1]; |
| 624 | |
| 625 | if (declaringClass == null) |
| 626 | declaringClass = dt.javaName(); |
| 627 | } |
| 628 | |
| 629 | int cpi = modClass.addMethodReference(declaringClass, methodName, |
| 630 | methodDescriptor, opcode == VMOpcode.INVOKEINTERFACE); |
| 631 | |
| 632 | return new BCMethodCaller(opcode, rt, cpi); |
| 633 | } |
| 634 | |
| 635 | public int callMethod(Object methodDescriptor) { |
| 636 | |
| 637 | // pop the reference off the stack |
| 638 | popStack(); |
| 639 | |
| 640 | BCMethodCaller mc = (BCMethodCaller) methodDescriptor; |
| 641 | |
| 642 | int cpi = mc.cpi; |
| 643 | short opcode = mc.opcode; |
| 644 | |
| 645 | if (opcode == VMOpcode.INVOKEINTERFACE) { |
| 646 | myCode.addInstrU2U1U1(opcode, cpi, (short) 1, (short) 0); |
| 647 | } |
| 648 | else |
| 649 | myCode.addInstrU2(opcode, cpi); |
| 650 | |
| 651 | // this is the return type of the method |
| 652 | Type rt = mc.type; |
| 653 | int rw = rt.width(); |
| 654 | if (rw != 0) |
| 655 | growStack(rw, rt); |
| 656 | else |
| 657 | { |
| 658 | if (stackDepth == 0) |
| 659 | overflowMethodCheck(); |
| 660 | } |
| 661 | return cpi; |
| 662 | } |
| 663 | |
| 664 | public int callMethod(short opcode, String declaringClass, String methodName, |
| 665 | String returnType, int numArgs) { |
| 666 | |
| 667 | Type rt = cb.factory.type(returnType); |
| 668 | |
| 669 | int initialStackDepth = stackDepth; |
| 670 | |
| 671 | // get the array of parameter types |
| 672 | |
| 673 | String [] debugParameterTypes = null; |
| 674 | String[] vmParameterTypes; |
| 675 | if (numArgs == 0) { |
| 676 | vmParameterTypes = BCMethodDescriptor.EMPTY; |
| 677 | } else { |
| 678 | if (SanityManager.DEBUG) { |
| 679 | debugParameterTypes = new String[numArgs]; |
| 680 | } |
| 681 | vmParameterTypes = new String[numArgs]; |
| 682 | for (int i = numArgs - 1; i >= 0; i--) { |
| 683 | Type at = popStack(); |
| 684 | |
| 685 | vmParameterTypes[i] = at.vmName(); |
| 686 | if (SanityManager.DEBUG) { |
| 687 | debugParameterTypes[i] = at.javaName(); |
| 688 | } |
| 689 | } |
| 690 | } |
| 691 | |
| 692 | String methodDescriptor = BCMethodDescriptor.get(vmParameterTypes, rt.vmName(), cb.factory); |
| 693 | |
| 694 | Type dt = null; |
| 695 | if (opcode != VMOpcode.INVOKESTATIC) { |
| 696 | |
| 697 | dt = popStack(); |
| 698 | } |
| 699 | Type dtu = vmNameDeclaringClass(declaringClass); |
| 700 | if (dtu != null) |
| 701 | dt = dtu; |
| 702 | |
| 703 | int cpi = modClass.addMethodReference(dt.vmNameSimple, methodName, |
| 704 | methodDescriptor, opcode == VMOpcode.INVOKEINTERFACE); |
| 705 | |
| 706 | if (opcode == VMOpcode.INVOKEINTERFACE) { |
| 707 | short callArgCount = (short) (initialStackDepth - stackDepth); |
| 708 | myCode.addInstrU2U1U1(opcode, cpi, callArgCount, (short) 0); |
| 709 | } |
| 710 | else |
| 711 | myCode.addInstrU2(opcode, cpi); |
| 712 | |
| 713 | // this is the return type of the method |
| 714 | int rw = rt.width(); |
| 715 | if (rw != 0) |
| 716 | growStack(rw, rt); |
| 717 | else |
| 718 | { |
| 719 | if (stackDepth == 0) |
| 720 | overflowMethodCheck(); |
| 721 | } |
| 722 | // Check the declared type of the method |
| 723 | if (SanityManager.DEBUG) { |
| 724 | |
| 725 | d_BCValidate.checkMethod(opcode, dt, methodName, debugParameterTypes, rt); |
| 726 | } |
| 727 | |
| 728 | return cpi; |
| 729 | } |
| 730 | |
| 731 | private Type vmNameDeclaringClass(String declaringClass) { |
| 732 | if (declaringClass == null) |
| 733 | return null; |
| 734 | return cb.factory.type(declaringClass); |
| 735 | } |
| 736 | |
| 737 | public void callSuper() { |
| 738 | |
| 739 | pushThis(); |
| 740 | callMethod(VMOpcode.INVOKESPECIAL, cb.getSuperClassName(), "<init>", "void", 0); |
| 741 | } |
| 742 | |
| 743 | public void pushNewStart(String className) { |
| 744 | |
| 745 | int cpi = modClass.addClassReference(className); |
| 746 | |
| 747 | // Use U2, not CPE, since only wide form exists. |
| 748 | myCode.addInstrU2(VMOpcode.NEW, cpi); |
| 749 | myCode.addInstr(VMOpcode.DUP); |
| 750 | |
| 751 | // Grow the stack twice as we are pushing |
| 752 | // two instances of newly created reference |
| 753 | Type nt = cb.factory.type(className); |
| 754 | growStack(1, nt); |
| 755 | growStack(1, nt); |
| 756 | } |
| 757 | |
| 758 | public void pushNewComplete(int numArgs) { |
| 759 | callMethod(VMOpcode.INVOKESPECIAL, (String) null, "<init>", "void", numArgs); |
| 760 | } |
| 761 | |
| 762 | public void upCast(String className) { |
| 763 | Type uct = cb.factory.type(className); |
| 764 | |
| 765 | stackTypes[stackTypeOffset - 1] = uct; |
| 766 | //popStack(); |
| 767 | //growStack(1, uct); |
| 768 | } |
| 769 | |
| 770 | public void cast(String className) { |
| 771 | |
| 772 | // Perform a simple optimization to not |
| 773 | // insert a checkcast when the classname |
| 774 | // of the cast exactly matches the type name |
| 775 | // currently on the stack. |
| 776 | // This can reduce the amount of generated code. |
| 777 | // This compiler/class generator does not load |
| 778 | // classes to check relationships or any other |
| 779 | // information. Thus other optimizations where a cast |
| 780 | // is not required are not implemented. |
| 781 | Type tbc = stackTypes[stackTypeOffset - 1]; |
| 782 | |
| 783 | short sourceType = tbc.vmType(); |
| 784 | |
| 785 | if (sourceType == BCExpr.vm_reference) |
| 786 | { |
| 787 | // Simple optimize step |
| 788 | if (className.equals(tbc.javaName())) |
| 789 | { |
| 790 | // do nothing, exact matching type |
| 791 | return; |
| 792 | } |
| 793 | } |
| 794 | |
| 795 | Type ct = cb.factory.type(className); |
| 796 | popStack(); |
| 797 | |
| 798 | short targetType = ct.vmType(); |
| 799 | |
| 800 | if (SanityManager.DEBUG) { |
| 801 | |
| 802 | if (!((sourceType == BCExpr.vm_reference && |
| 803 | targetType == BCExpr.vm_reference) || |
| 804 | (sourceType != BCExpr.vm_reference && |
| 805 | targetType != BCExpr.vm_reference))) { |
| 806 | SanityManager.THROWASSERT("Both or neither must be object types " + ct.javaName() + " " + tbc.javaName()); |
| 807 | } |
| 808 | } |
| 809 | |
| 810 | // if it is an object type, do a checkcast on it. |
| 811 | if (sourceType == BCExpr.vm_reference) { |
| 812 | |
| 813 | int cpi = modClass.addClassReference(ct.vmNameSimple); |
| 814 | myCode.addInstrU2(VMOpcode.CHECKCAST, cpi); |
| 815 | } |
| 816 | // otherwise, try to convert it. |
| 817 | else { |
| 818 | short opcode = VMOpcode.NOP; |
| 819 | |
| 820 | // we use the conversionInfo array |
| 821 | // to determine how to convert; if |
| 822 | // the result type of the conversion |
| 823 | // is not our target type, we are not done |
| 824 | // yet. Make sure there are no |
| 825 | // infinite loop possibilities in the |
| 826 | // conversionInfo array! |
| 827 | while (sourceType!=targetType && opcode!=VMOpcode.BAD) { |
| 828 | short[] currentConversion = |
| 829 | CodeChunk.CAST_CONVERSION_INFO[sourceType][targetType]; |
| 830 | sourceType = currentConversion[1]; |
| 831 | opcode = currentConversion[0]; |
| 832 | if (opcode != VMOpcode.NOP) { |
| 833 | myCode.addInstr(opcode); |
| 834 | } |
| 835 | } |
| 836 | if (SanityManager.DEBUG) { |
| 837 | SanityManager.ASSERT(opcode != VMOpcode.BAD, |
| 838 | "BAD VMOpcode not expected in cast"); |
| 839 | } |
| 840 | } |
| 841 | growStack(ct); |
| 842 | } |
| 843 | |
| 844 | public void isInstanceOf(String className) { |
| 845 | int cpi = modClass.addClassReference(className); |
| 846 | myCode.addInstrU2(VMOpcode.INSTANCEOF, cpi); |
| 847 | popStack(); |
| 848 | growStack(1, Type.BOOLEAN); |
| 849 | } |
| 850 | |
| 851 | public void pushNull(String type) { |
| 852 | myCode.addInstr(VMOpcode.ACONST_NULL); |
| 853 | growStack(1, cb.factory.type(type)); |
| 854 | } |
| 855 | |
| 856 | |
| 857 | public void getField(LocalField field) { |
| 858 | |
| 859 | BCLocalField lf = (BCLocalField) field; |
| 860 | Type lt = lf.type; |
| 861 | |
| 862 | pushThis(); |
| 863 | myCode.addInstrU2(VMOpcode.GETFIELD, lf.cpi); |
| 864 | |
| 865 | popStack(); |
| 866 | growStack(lt); |
| 867 | |
| 868 | } |
| 869 | |
| 870 | public void getField(String declaringClass, String fieldName, String fieldType) { |
| 871 | Type dt = popStack(); |
| 872 | |
| 873 | Type dtu = vmNameDeclaringClass(declaringClass); |
| 874 | if (dtu != null) |
| 875 | dt = dtu; |
| 876 | |
| 877 | getField(VMOpcode.GETFIELD, dt.vmNameSimple, fieldName, fieldType); |
| 878 | } |
| 879 | /** |
| 880 | Push the contents of the described static field onto the stack. |
| 881 | */ |
| 882 | public void getStaticField(String declaringClass, String fieldName, String fieldType) { |
| 883 | getField(VMOpcode.GETSTATIC, declaringClass, fieldName, fieldType); |
| 884 | } |
| 885 | |
| 886 | private void getField(short opcode, String declaringClass, String fieldName, String fieldType) { |
| 887 | |
| 888 | Type ft = cb.factory.type(fieldType); |
| 889 | int cpi = modClass.addFieldReference(vmNameDeclaringClass(declaringClass).vmNameSimple, fieldName, ft.vmName()); |
| 890 | myCode.addInstrU2(opcode, cpi); |
| 891 | |
| 892 | growStack(ft); |
| 893 | } |
| 894 | |
| 895 | /** |
| 896 | * Set the field but don't duplicate its value so |
| 897 | * nothing is left on the stack after this call. |
| 898 | */ |
| 899 | public void setField(LocalField field) { |
| 900 | BCLocalField lf = (BCLocalField) field; |
| 901 | Type lt = lf.type; |
| 902 | |
| 903 | putField(lf.type, lf.cpi, false); |
| 904 | |
| 905 | if (stackDepth == 0) |
| 906 | overflowMethodCheck(); |
| 907 | } |
| 908 | |
| 909 | /** |
| 910 | Upon entry the top word(s) on the stack is |
| 911 | the value to be put into the field. Ie. |
| 912 | we have |
| 913 | <PRE> |
| 914 | word |
| 915 | </PRE> |
| 916 | |
| 917 | Before the call we need |
| 918 | <PRE> |
| 919 | word |
| 920 | this |
| 921 | word |
| 922 | </PRE> |
| 923 | word2,word1 -> word2, word1, word2 |
| 924 | |
| 925 | So that we are left with word after the put. |
| 926 | |
| 927 | */ |
| 928 | public void putField(LocalField field) { |
| 929 | BCLocalField lf = (BCLocalField) field; |
| 930 | Type lt = lf.type; |
| 931 | |
| 932 | putField(lf.type, lf.cpi, true); |
| 933 | } |
| 934 | |
| 935 | /** |
| 936 | Pop the top stack value and store it in the instance field of this class. |
| 937 | */ |
| 938 | public void putField(String fieldName, String fieldType) { |
| 939 | |
| 940 | Type ft = cb.factory.type(fieldType); |
| 941 | int cpi = modClass.addFieldReference(cb.classType.vmNameSimple, fieldName, ft.vmName()); |
| 942 | |
| 943 | putField(ft, cpi, true); |
| 944 | } |
| 945 | |
| 946 | private void putField(Type fieldType, int cpi, boolean dup) { |
| 947 | |
| 948 | // now have ...,value |
| 949 | if (dup) |
| 950 | { |
| 951 | myCode.addInstr(fieldType.width() == 2 ? VMOpcode.DUP2 : VMOpcode.DUP); |
| 952 | growStack(fieldType); |
| 953 | } |
| 954 | // now have |
| 955 | // dup true: ...,value,value |
| 956 | // dup false: ...,value, |
| 957 | |
| 958 | pushThis(); |
| 959 | // now have |
| 960 | // dup true: ...,value,value,this |
| 961 | // dup false: ...,value,this |
| 962 | |
| 963 | swap(); |
| 964 | // now have |
| 965 | // dup true: ...,value,this,value |
| 966 | // dup false: ...,this,value |
| 967 | |
| 968 | myCode.addInstrU2(VMOpcode.PUTFIELD, cpi); |
| 969 | popStack(); // the value |
| 970 | popStack(); // this |
| 971 | |
| 972 | // now have |
| 973 | // dup true: ...,value |
| 974 | // dup false: ... |
| 975 | } |
| 976 | /** |
| 977 | Pop the top stack value and store it in the field. |
| 978 | This call requires the instance to be pushed by the caller. |
| 979 | */ |
| 980 | public void putField(String declaringClass, String fieldName, String fieldType) { |
| 981 | Type vt = popStack(); |
| 982 | Type dt = popStack(); |
| 983 | |
| 984 | if (SanityManager.DEBUG) { |
| 985 | if (dt.width() != 1) |
| 986 | SanityManager.THROWASSERT("reference expected for field access - is " + dt.javaName()); |
| 987 | } |
| 988 | |
| 989 | // have objectref,value |
| 990 | // need value,objectref,value |
| 991 | |
| 992 | myCode.addInstr(vt.width() == 2 ? VMOpcode.DUP2_X1 : VMOpcode.DUP_X1); |
| 993 | growStack(vt); |
| 994 | growStack(dt); |
| 995 | growStack(vt); |
| 996 | |
| 997 | Type dtu = vmNameDeclaringClass(declaringClass); |
| 998 | if (dtu != null) |
| 999 | dt = dtu; |
| 1000 | |
| 1001 | Type ft = cb.factory.type(fieldType); |
| 1002 | int cpi = modClass.addFieldReference(dt.vmNameSimple, fieldName, ft.vmName()); |
| 1003 | myCode.addInstrU2(VMOpcode.PUTFIELD, cpi); |
| 1004 | |
| 1005 | popStack(); // value |
| 1006 | popStack(); // reference |
| 1007 | } |
| 1008 | |
| 1009 | public void conditionalIfNull() { |
| 1010 | |
| 1011 | conditionalIf(VMOpcode.IFNONNULL); |
| 1012 | } |
| 1013 | |
| 1014 | public void conditionalIf() { |
| 1015 | conditionalIf(VMOpcode.IFEQ); |
| 1016 | } |
| 1017 | |
| 1018 | private Conditional condition; |
| 1019 | |
| 1020 | private void conditionalIf(short opcode) { |
| 1021 | popStack(); |
| 1022 | |
| 1023 | // Save the stack upon entry to the 'then' block of the |
| 1024 | // 'if' so that we can set up the 'else' block with the |
| 1025 | // correct stack on entry. |
| 1026 | |
| 1027 | condition = new Conditional(condition, myCode, opcode, copyStack()); |
| 1028 | } |
| 1029 | |
| 1030 | public void startElseCode() { |
| 1031 | |
| 1032 | // start the else code |
| 1033 | Type[] entryStack = condition.startElse(this, myCode, copyStack()); |
| 1034 | |
| 1035 | for (int i = stackDepth = 0; i < entryStack.length; i++) |
| 1036 | { |
| 1037 | stackDepth += (stackTypes[i] = entryStack[i]).width(); |
| 1038 | } |
| 1039 | this.stackTypeOffset = entryStack.length; |
| 1040 | |
| 1041 | } |
| 1042 | public void completeConditional() { |
| 1043 | condition = condition.end(this, myCode, stackTypes, stackTypeOffset); |
| 1044 | } |
| 1045 | |
| 1046 | public void pop() { |
| 1047 | if (SanityManager.DEBUG) { |
| 1048 | if (stackDepth == 0) |
| 1049 | SanityManager.THROWASSERT("pop when stack is empty!"); |
| 1050 | } |
| 1051 | Type toPop = popStack(); |
| 1052 | |
| 1053 | myCode.addInstr(toPop.width() == 2 ? VMOpcode.POP2 : VMOpcode.POP); |
| 1054 | |
| 1055 | if (stackDepth == 0) |
| 1056 | overflowMethodCheck(); |
| 1057 | } |
| 1058 | |
| 1059 | public void endStatement() { |
| 1060 | if (stackDepth != 0) { |
| 1061 | pop(); |
| 1062 | } |
| 1063 | |
| 1064 | //if (SanityManager.DEBUG) { |
| 1065 | // if (stackDepth != 0) |
| 1066 | // SanityManager.THROWASSERT("items left on stack " + stackDepth); |
| 1067 | // } |
| 1068 | } |
| 1069 | |
| 1070 | /** |
| 1071 | */ |
| 1072 | public void getArrayElement(int element) { |
| 1073 | |
| 1074 | push(element); |
| 1075 | popStack(); // int just pushed will be popped by array access |
| 1076 | |
| 1077 | Type arrayType = popStack(); |
| 1078 | |
| 1079 | String arrayJava = arrayType.javaName(); |
| 1080 | String componentString = arrayJava.substring(0,arrayJava.length()-2); |
| 1081 | |
| 1082 | Type componentType = cb.factory.type(componentString); |
| 1083 | |
| 1084 | short typ = componentType.vmType(); |
| 1085 | |
| 1086 | // boolean has a type id of integer, here it needs to be byte. |
| 1087 | if ((typ == BCExpr.vm_int) && (componentType.vmName().equals("Z"))) |
| 1088 | typ = BCExpr.vm_byte; |
| 1089 | myCode.addInstr(CodeChunk.ARRAY_ACCESS[typ]); |
| 1090 | |
| 1091 | growStack(componentType); |
| 1092 | |
| 1093 | } |
| 1094 | // come in with ref, value |
| 1095 | |
| 1096 | public void setArrayElement(int element) { |
| 1097 | |
| 1098 | // ref, value |
| 1099 | |
| 1100 | push(element); |
| 1101 | |
| 1102 | // ref, value, index |
| 1103 | swap(); |
| 1104 | |
| 1105 | Type componentType = popStack(); // value |
| 1106 | popStack(); // int just pushed will be popped by array access |
| 1107 | |
| 1108 | popStack(); // array ref. |
| 1109 | |
| 1110 | short typ = componentType.vmType(); |
| 1111 | |
| 1112 | // boolean has a type id of integer, here it needs to be byte. |
| 1113 | if ((typ == BCExpr.vm_int) && (componentType.vmName().equals("Z"))) |
| 1114 | typ = BCExpr.vm_byte; |
| 1115 | |
| 1116 | myCode.addInstr(CodeChunk.ARRAY_STORE[typ]); |
| 1117 | } |
| 1118 | /** |
| 1119 | this array maps the BCExpr vm_* constants 0..6 to |
| 1120 | the expected VM type constants for the newarray instruction. |
| 1121 | <p> |
| 1122 | Because boolean was mapped to integer for general instructions, |
| 1123 | it will have to be specially matched and mapped to its value |
| 1124 | directly (4). |
| 1125 | */ |
| 1126 | private static final byte newArrayElementTypeMap[] = { 8, 9, 10, 11, 6, 7, 5 }; |
| 1127 | static final byte T_BOOLEAN = 4; |
| 1128 | /** |
| 1129 | Create an array instance |
| 1130 | |
| 1131 | Stack ... => |
| 1132 | ...,arrayref |
| 1133 | */ |
| 1134 | public void pushNewArray(String className, int size) { |
| 1135 | |
| 1136 | push(size); |
| 1137 | popStack(); // int just pushed will be popped by array creation |
| 1138 | |
| 1139 | Type elementType = cb.factory.type(className); |
| 1140 | |
| 1141 | // determine the instruction to use based on the element type |
| 1142 | if (elementType.vmType() == BCExpr.vm_reference) { |
| 1143 | |
| 1144 | // For an array of Java class/interface elements, generate: |
| 1145 | // ANEWARRAY #cpei ; where cpei is a constant pool index for the class |
| 1146 | |
| 1147 | int cpi = modClass.addClassReference(elementType.javaName()); |
| 1148 | // Use U2, not CPE, since only wide form exists. |
| 1149 | myCode.addInstrU2(VMOpcode.ANEWARRAY, cpi); |
| 1150 | } else { |
| 1151 | byte atype; |
| 1152 | |
| 1153 | // get the argument for the array type |
| 1154 | // if the element type is boolean, we can't use the map |
| 1155 | // because the type id will say integer. |
| 1156 | // but we can use vm_int test to weed out some tests |
| 1157 | if (elementType.vmType() == BCExpr.vm_int && |
| 1158 | VMDescriptor.C_BOOLEAN == elementType.vmName().charAt(0)) |
| 1159 | atype = T_BOOLEAN; |
| 1160 | else |
| 1161 | atype = newArrayElementTypeMap[elementType.vmType()]; |
| 1162 | |
| 1163 | // For an array of Java builtin type elements, generate: |
| 1164 | // NEWARRAY #atype ; where atype is a constant for the builtin type |
| 1165 | |
| 1166 | myCode.addInstrU1(VMOpcode.NEWARRAY, atype); |
| 1167 | } |
| 1168 | |
| 1169 | // an array reference is an object, hence width of 1 |
| 1170 | growStack(1, cb.factory.type(className.concat("[]"))); |
| 1171 | } |
| 1172 | |
| 1173 | /** |
| 1174 | * Write a instruction that uses a constant pool entry |
| 1175 | * as an operand, add a limit exceeded message if |
| 1176 | * the number of constant pool entries has exceeded |
| 1177 | * the limit. |
| 1178 | */ |
| 1179 | private void addInstrCPE(short opcode, int cpe) |
| 1180 | { |
| 1181 | if (cpe >= VMOpcode.MAX_CONSTANT_POOL_ENTRIES) |
| 1182 | cb.addLimitExceeded(this, "constant_pool_count", |
| 1183 | VMOpcode.MAX_CONSTANT_POOL_ENTRIES, cpe); |
| 1184 | |
| 1185 | myCode.addInstrCPE(opcode, cpe); |
| 1186 | } |
| 1187 | |
| 1188 | /** |
| 1189 | Tell if statement number in this method builder hits limit. This |
| 1190 | method builder keeps a counter of how many statements are added to it. |
| 1191 | Caller should call this function every time it tries to add a statement |
| 1192 | to this method builder (counter is increased by 1), then the function |
| 1193 | returns whether the accumulated statement number hits a limit. |
| 1194 | The reason of doing this is that Java compiler has a limit of 64K code |
| 1195 | size for each method. We might hit this limit if an extremely long |
| 1196 | insert statement is issued, for example (see beetle 4293). Counting |
| 1197 | statement number is an approximation without too much overhead. |
| 1198 | */ |
| 1199 | public boolean statementNumHitLimit(int noStatementsAdded) |
| 1200 | { |
| 1201 | if (statementNum > 2048) // 2K limit |
| 1202 | { |
| 1203 | return true; |
| 1204 | } |
| 1205 | else |
| 1206 | { |
| 1207 | statementNum = statementNum + noStatementsAdded; |
| 1208 | return false; |
| 1209 | } |
| 1210 | } |
| 1211 | |
| 1212 | /** |
| 1213 | * Check to see if the current method byte code is nearing the |
| 1214 | * limit of 65535. If it is start overflowing to a new method. |
| 1215 | * <P> |
| 1216 | * Overflow is handled for a method named e23 as: |
| 1217 | * <CODE> |
| 1218 | public Object e23() |
| 1219 | { |
| 1220 | ... existing code |
| 1221 | // split point |
| 1222 | return e23_0(); |
| 1223 | } |
| 1224 | private Object e23_0() |
| 1225 | { |
| 1226 | ... first set overflowed code |
| 1227 | // split point |
| 1228 | return e23_1(); |
| 1229 | } |
| 1230 | private Object e23_1() |
| 1231 | { |
| 1232 | ... second set overflowed code |
| 1233 | // method complete |
| 1234 | return result; |
| 1235 | } |
| 1236 | </CODE> |
| 1237 | <P> |
| 1238 | |
| 1239 | These overflow methods are hidden from the code using this MethodBuilder, |
| 1240 | it continues to think that it is building a single method with the |
| 1241 | original name. |
| 1242 | |
| 1243 | |
| 1244 | * <BR> Restrictions: |
| 1245 | * <UL> |
| 1246 | * <LI> Only handles methods with no arguments |
| 1247 | * <LI> Stack depth must be zero |
| 1248 | * </UL> |
| 1249 | * |
| 1250 | * |
| 1251 | */ |
| 1252 | private void overflowMethodCheck() |
| 1253 | { |
| 1254 | if (handlingOverflow) |
| 1255 | return; |
| 1256 | |
| 1257 | // don't sub method in the middle of a conditional |
| 1258 | if (condition != null) |
| 1259 | return; |
| 1260 | |
| 1261 | int currentCodeSize = myCode.getPC(); |
| 1262 | |
| 1263 | // Overflow at >= 55,000 bytes which is someway |
| 1264 | // below the limit of 65,535. Ideally overflow |
| 1265 | // would occur at 65535 minus the few bytes needed |
| 1266 | // to call the sub-method, but the issue is at this level |
| 1267 | // we don't know frequently we are called given the restriction |
| 1268 | // of only being called when the stack depth is zero. |
| 1269 | // Thus split earlier to try ensure most cases are caught. |
| 1270 | // Only downside is that we may split into N methods when N-1 would suffice. |
| 1271 | if (currentCodeSize < 55000) |
| 1272 | return; |
| 1273 | |
| 1274 | // only handle no-arg methods at the moment. |
| 1275 | if (parameters != null) |
| 1276 | { |
| 1277 | if (parameters.length != 0) |
| 1278 | return; |
| 1279 | } |
| 1280 | |
| 1281 | BCMethod subMethod = getNewSubMethod(myReturnType, false); |
| 1282 | |
| 1283 | // stop any recursion |
| 1284 | handlingOverflow = true; |
| 1285 | |
| 1286 | // in this method make a call to the sub method we will |
| 1287 | // be transferring control to. |
| 1288 | callSubMethod(subMethod); |
| 1289 | |
| 1290 | // and return its value, works just as well for a void method! |
| 1291 | this.methodReturn(); |
| 1292 | this.complete(); |
| 1293 | |
| 1294 | handlingOverflow = false; |
| 1295 | |
| 1296 | // now the tricky bit, make this object take over the |
| 1297 | // code etc. from the sub method. This is done so |
| 1298 | // that any code that has a reference to this MethodBuilder |
| 1299 | // will continue to work. They will be writing code into the |
| 1300 | // new sub method. |
| 1301 | |
| 1302 | this.myEntry = subMethod.myEntry; |
| 1303 | this.myCode = subMethod.myCode; |
| 1304 | this.currentVarNum = subMethod.currentVarNum; |
| 1305 | this.statementNum = subMethod.statementNum; |
| 1306 | |
| 1307 | // copy stack info |
| 1308 | this.stackTypes = subMethod.stackTypes; |
| 1309 | this.stackTypeOffset = subMethod.stackTypeOffset; |
| 1310 | this.maxStack = subMethod.maxStack; |
| 1311 | this.stackDepth = subMethod.stackDepth; |
| 1312 | } |
| 1313 | |
| 1314 | /** |
| 1315 | * Create a sub-method from this method to allow the code builder to split a |
| 1316 | * single logical method into multiple methods to avoid the 64k per-method |
| 1317 | * code size limit. The sub method with inherit the thrown exceptions of |
| 1318 | * this method. |
| 1319 | * |
| 1320 | * @param returnType |
| 1321 | * Return type of the new method |
| 1322 | * @param withParameters |
| 1323 | * True to define the method with matching parameters false to |
| 1324 | * define it with no parameters. |
| 1325 | * @return A valid empty sub method. |
| 1326 | */ |
| 1327 | final BCMethod getNewSubMethod(String returnType, boolean withParameters) { |
| 1328 | int modifiers = myEntry.getModifier(); |
| 1329 | |
| 1330 | // the sub-method can be private to ensure that no-one |
| 1331 | // can call it accidentally from outside the class. |
| 1332 | modifiers &= ~(Modifier.PROTECTED | Modifier.PUBLIC); |
| 1333 | modifiers |= Modifier.PRIVATE; |
| 1334 | |
| 1335 | String subMethodName = myName + "_s" |
| 1336 | + Integer.toString(subMethodCount++); |
| 1337 | BCMethod subMethod = (BCMethod) cb.newMethodBuilder(modifiers, |
| 1338 | returnType, subMethodName, withParameters ? parameterTypes |
| 1339 | : null); |
| 1340 | subMethod.thrownExceptions = this.thrownExceptions; |
| 1341 | |
| 1342 | return subMethod; |
| 1343 | } |
| 1344 | |
| 1345 | /** |
| 1346 | * Call a sub-method created by getNewSubMethod handling parameters |
| 1347 | * correctly. |
| 1348 | */ |
| 1349 | final void callSubMethod(BCMethod subMethod) { |
| 1350 | // in this method make a call to the sub method we will |
| 1351 | // be transferring control to. |
| 1352 | short op; |
| 1353 | if ((myEntry.getModifier() & Modifier.STATIC) == 0) { |
| 1354 | op = VMOpcode.INVOKEVIRTUAL; |
| 1355 | this.pushThis(); |
| 1356 | } else { |
| 1357 | op = VMOpcode.INVOKESTATIC; |
| 1358 | } |
| 1359 | |
| 1360 | int parameterCount = subMethod.parameters == null ? 0 |
| 1361 | : subMethod.parameters.length; |
| 1362 | |
| 1363 | // push my parameter values for the call. |
| 1364 | for (int pi = 0; pi < parameterCount; pi++) |
| 1365 | this.getParameter(pi); |
| 1366 | |
| 1367 | this.callMethod(op, modClass.getName(), subMethod.getName(), |
| 1368 | subMethod.myReturnType, parameterCount); |
| 1369 | } |
| 1370 | } |
| 1371 | |