1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /*
26 * This file is available under and governed by the GNU General Public
27 * License version 2 only, as published by the Free Software Foundation.
28 * However, the following notice accompanied the original version of this
29 * file:
30 *
31 * ASM: a very small and fast Java bytecode manipulation framework
32 * Copyright (c) 2000-2011 INRIA, France Telecom
33 * All rights reserved.
34 *
35 * Redistribution and use in source and binary forms, with or without
36 * modification, are permitted provided that the following conditions
37 * are met:
38 * 1. Redistributions of source code must retain the above copyright
39 * notice, this list of conditions and the following disclaimer.
40 * 2. Redistributions in binary form must reproduce the above copyright
41 * notice, this list of conditions and the following disclaimer in the
42 * documentation and/or other materials provided with the distribution.
43 * 3. Neither the name of the copyright holders nor the names of its
44 * contributors may be used to endorse or promote products derived from
45 * this software without specific prior written permission.
46 *
47 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
48 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
49 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
50 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
51 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
52 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
53 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
54 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
55 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
56 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
57 * THE POSSIBILITY OF SUCH DAMAGE.
58 */
59 package jdk.internal.org.objectweb.asm;
60
61 /**
62 * Information about the input and output stack map frames of a basic block.
63 *
64 * @author Eric Bruneton
65 */
66 class Frame {
67
68 /*
69 * Frames are computed in a two steps process: during the visit of each
70 * instruction, the state of the frame at the end of current basic block is
71 * updated by simulating the action of the instruction on the previous state
72 * of this so called "output frame". In visitMaxs, a fix point algorithm is
73 * used to compute the "input frame" of each basic block, i.e. the stack map
74 * frame at the beginning of the basic block, starting from the input frame
75 * of the first basic block (which is computed from the method descriptor),
76 * and by using the previously computed output frames to compute the input
77 * state of the other blocks.
78 *
79 * All output and input frames are stored as arrays of integers. Reference
80 * and array types are represented by an index into a type table (which is
81 * not the same as the constant pool of the class, in order to avoid adding
82 * unnecessary constants in the pool - not all computed frames will end up
83 * being stored in the stack map table). This allows very fast type
84 * comparisons.
85 *
86 * Output stack map frames are computed relatively to the input frame of the
87 * basic block, which is not yet known when output frames are computed. It
88 * is therefore necessary to be able to represent abstract types such as
89 * "the type at position x in the input frame locals" or "the type at
90 * position x from the top of the input frame stack" or even "the type at
91 * position x in the input frame, with y more (or less) array dimensions".
92 * This explains the rather complicated type format used in output frames.
93 *
94 * This format is the following: DIM KIND VALUE (4, 4 and 24 bits). DIM is a
95 * signed number of array dimensions (from -8 to 7). KIND is either BASE,
96 * LOCAL or STACK. BASE is used for types that are not relative to the input
97 * frame. LOCAL is used for types that are relative to the input local
98 * variable types. STACK is used for types that are relative to the input
99 * stack types. VALUE depends on KIND. For LOCAL types, it is an index in
100 * the input local variable types. For STACK types, it is a position
101 * relatively to the top of input frame stack. For BASE types, it is either
102 * one of the constants defined below, or for OBJECT and UNINITIALIZED
103 * types, a tag and an index in the type table.
104 *
105 * Output frames can contain types of any kind and with a positive or
106 * negative dimension (and even unassigned types, represented by 0 - which
107 * does not correspond to any valid type value). Input frames can only
108 * contain BASE types of positive or null dimension. In all cases the type
109 * table contains only internal type names (array type descriptors are
110 * forbidden - dimensions must be represented through the DIM field).
111 *
112 * The LONG and DOUBLE types are always represented by using two slots (LONG
113 * + TOP or DOUBLE + TOP), for local variable types as well as in the
114 * operand stack. This is necessary to be able to simulate DUPx_y
115 * instructions, whose effect would be dependent on the actual type values
116 * if types were always represented by a single slot in the stack (and this
117 * is not possible, since actual type values are not always known - cf LOCAL
118 * and STACK type kinds).
119 */
120
121 /**
122 * Mask to get the dimension of a frame type. This dimension is a signed
123 * integer between -8 and 7.
124 */
125 static final int DIM = 0xF0000000;
126
127 /**
128 * Constant to be added to a type to get a type with one more dimension.
129 */
130 static final int ARRAY_OF = 0x10000000;
131
132 /**
133 * Constant to be added to a type to get a type with one less dimension.
134 */
135 static final int ELEMENT_OF = 0xF0000000;
136
137 /**
138 * Mask to get the kind of a frame type.
139 *
140 * @see #BASE
141 * @see #LOCAL
142 * @see #STACK
143 */
144 static final int KIND = 0xF000000;
145
146 /**
147 * Flag used for LOCAL and STACK types. Indicates that if this type happens
148 * to be a long or double type (during the computations of input frames),
149 * then it must be set to TOP because the second word of this value has been
150 * reused to store other data in the basic block. Hence the first word no
151 * longer stores a valid long or double value.
152 */
153 static final int TOP_IF_LONG_OR_DOUBLE = 0x800000;
154
155 /**
156 * Mask to get the value of a frame type.
157 */
158 static final int VALUE = 0x7FFFFF;
159
160 /**
161 * Mask to get the kind of base types.
162 */
163 static final int BASE_KIND = 0xFF00000;
164
165 /**
166 * Mask to get the value of base types.
167 */
168 static final int BASE_VALUE = 0xFFFFF;
169
170 /**
171 * Kind of the types that are not relative to an input stack map frame.
172 */
173 static final int BASE = 0x1000000;
174
175 /**
176 * Base kind of the base reference types. The BASE_VALUE of such types is an
177 * index into the type table.
178 */
179 static final int OBJECT = BASE | 0x700000;
180
181 /**
182 * Base kind of the uninitialized base types. The BASE_VALUE of such types
183 * in an index into the type table (the Item at that index contains both an
184 * instruction offset and an internal class name).
185 */
186 static final int UNINITIALIZED = BASE | 0x800000;
187
188 /**
189 * Kind of the types that are relative to the local variable types of an
190 * input stack map frame. The value of such types is a local variable index.
191 */
192 private static final int LOCAL = 0x2000000;
193
194 /**
195 * Kind of the the types that are relative to the stack of an input stack
196 * map frame. The value of such types is a position relatively to the top of
197 * this stack.
198 */
199 private static final int STACK = 0x3000000;
200
201 /**
202 * The TOP type. This is a BASE type.
203 */
204 static final int TOP = BASE | 0;
205
206 /**
207 * The BOOLEAN type. This is a BASE type mainly used for array types.
208 */
209 static final int BOOLEAN = BASE | 9;
210
211 /**
212 * The BYTE type. This is a BASE type mainly used for array types.
213 */
214 static final int BYTE = BASE | 10;
215
216 /**
217 * The CHAR type. This is a BASE type mainly used for array types.
218 */
219 static final int CHAR = BASE | 11;
220
221 /**
222 * The SHORT type. This is a BASE type mainly used for array types.
223 */
224 static final int SHORT = BASE | 12;
225
226 /**
227 * The INTEGER type. This is a BASE type.
228 */
229 static final int INTEGER = BASE | 1;
230
231 /**
232 * The FLOAT type. This is a BASE type.
233 */
234 static final int FLOAT = BASE | 2;
235
236 /**
237 * The DOUBLE type. This is a BASE type.
238 */
239 static final int DOUBLE = BASE | 3;
240
241 /**
242 * The LONG type. This is a BASE type.
243 */
244 static final int LONG = BASE | 4;
245
246 /**
247 * The NULL type. This is a BASE type.
248 */
249 static final int NULL = BASE | 5;
250
251 /**
252 * The UNINITIALIZED_THIS type. This is a BASE type.
253 */
254 static final int UNINITIALIZED_THIS = BASE | 6;
255
256 /**
257 * The stack size variation corresponding to each JVM instruction. This
258 * stack variation is equal to the size of the values produced by an
259 * instruction, minus the size of the values consumed by this instruction.
260 */
261 static final int[] SIZE;
262
263 /**
264 * Computes the stack size variation corresponding to each JVM instruction.
265 */
266 static {
267 int i;
268 int[] b = new int[202];
269 String s = "EFFFFFFFFGGFFFGGFFFEEFGFGFEEEEEEEEEEEEEEEEEEEEDEDEDDDDD"
270 + "CDCDEEEEEEEEEEEEEEEEEEEEBABABBBBDCFFFGGGEDCDCDCDCDCDCDCDCD"
271 + "CDCEEEEDDDDDDDCDCDCEFEFDDEEFFDEDEEEBDDBBDDDDDDCCCCCCCCEFED"
272 + "DDCDCDEEEEEEEEEEFEEEEEEDDEEDDEE";
273 for (i = 0; i < b.length; ++i) {
274 b[i] = s.charAt(i) - 'E';
275 }
276 SIZE = b;
277
278 // code to generate the above string
279 //
280 // int NA = 0; // not applicable (unused opcode or variable size opcode)
281 //
282 // b = new int[] {
283 // 0, //NOP, // visitInsn
284 // 1, //ACONST_NULL, // -
285 // 1, //ICONST_M1, // -
286 // 1, //ICONST_0, // -
287 // 1, //ICONST_1, // -
288 // 1, //ICONST_2, // -
289 // 1, //ICONST_3, // -
290 // 1, //ICONST_4, // -
291 // 1, //ICONST_5, // -
292 // 2, //LCONST_0, // -
293 // 2, //LCONST_1, // -
294 // 1, //FCONST_0, // -
295 // 1, //FCONST_1, // -
296 // 1, //FCONST_2, // -
297 // 2, //DCONST_0, // -
298 // 2, //DCONST_1, // -
299 // 1, //BIPUSH, // visitIntInsn
300 // 1, //SIPUSH, // -
301 // 1, //LDC, // visitLdcInsn
302 // NA, //LDC_W, // -
303 // NA, //LDC2_W, // -
304 // 1, //ILOAD, // visitVarInsn
305 // 2, //LLOAD, // -
306 // 1, //FLOAD, // -
307 // 2, //DLOAD, // -
308 // 1, //ALOAD, // -
309 // NA, //ILOAD_0, // -
310 // NA, //ILOAD_1, // -
311 // NA, //ILOAD_2, // -
312 // NA, //ILOAD_3, // -
313 // NA, //LLOAD_0, // -
314 // NA, //LLOAD_1, // -
315 // NA, //LLOAD_2, // -
316 // NA, //LLOAD_3, // -
317 // NA, //FLOAD_0, // -
318 // NA, //FLOAD_1, // -
319 // NA, //FLOAD_2, // -
320 // NA, //FLOAD_3, // -
321 // NA, //DLOAD_0, // -
322 // NA, //DLOAD_1, // -
323 // NA, //DLOAD_2, // -
324 // NA, //DLOAD_3, // -
325 // NA, //ALOAD_0, // -
326 // NA, //ALOAD_1, // -
327 // NA, //ALOAD_2, // -
328 // NA, //ALOAD_3, // -
329 // -1, //IALOAD, // visitInsn
330 // 0, //LALOAD, // -
331 // -1, //FALOAD, // -
332 // 0, //DALOAD, // -
333 // -1, //AALOAD, // -
334 // -1, //BALOAD, // -
335 // -1, //CALOAD, // -
336 // -1, //SALOAD, // -
337 // -1, //ISTORE, // visitVarInsn
338 // -2, //LSTORE, // -
339 // -1, //FSTORE, // -
340 // -2, //DSTORE, // -
341 // -1, //ASTORE, // -
342 // NA, //ISTORE_0, // -
343 // NA, //ISTORE_1, // -
344 // NA, //ISTORE_2, // -
345 // NA, //ISTORE_3, // -
346 // NA, //LSTORE_0, // -
347 // NA, //LSTORE_1, // -
348 // NA, //LSTORE_2, // -
349 // NA, //LSTORE_3, // -
350 // NA, //FSTORE_0, // -
351 // NA, //FSTORE_1, // -
352 // NA, //FSTORE_2, // -
353 // NA, //FSTORE_3, // -
354 // NA, //DSTORE_0, // -
355 // NA, //DSTORE_1, // -
356 // NA, //DSTORE_2, // -
357 // NA, //DSTORE_3, // -
358 // NA, //ASTORE_0, // -
359 // NA, //ASTORE_1, // -
360 // NA, //ASTORE_2, // -
361 // NA, //ASTORE_3, // -
362 // -3, //IASTORE, // visitInsn
363 // -4, //LASTORE, // -
364 // -3, //FASTORE, // -
365 // -4, //DASTORE, // -
366 // -3, //AASTORE, // -
367 // -3, //BASTORE, // -
368 // -3, //CASTORE, // -
369 // -3, //SASTORE, // -
370 // -1, //POP, // -
371 // -2, //POP2, // -
372 // 1, //DUP, // -
373 // 1, //DUP_X1, // -
374 // 1, //DUP_X2, // -
375 // 2, //DUP2, // -
376 // 2, //DUP2_X1, // -
377 // 2, //DUP2_X2, // -
378 // 0, //SWAP, // -
379 // -1, //IADD, // -
380 // -2, //LADD, // -
381 // -1, //FADD, // -
382 // -2, //DADD, // -
383 // -1, //ISUB, // -
384 // -2, //LSUB, // -
385 // -1, //FSUB, // -
386 // -2, //DSUB, // -
387 // -1, //IMUL, // -
388 // -2, //LMUL, // -
389 // -1, //FMUL, // -
390 // -2, //DMUL, // -
391 // -1, //IDIV, // -
392 // -2, //LDIV, // -
393 // -1, //FDIV, // -
394 // -2, //DDIV, // -
395 // -1, //IREM, // -
396 // -2, //LREM, // -
397 // -1, //FREM, // -
398 // -2, //DREM, // -
399 // 0, //INEG, // -
400 // 0, //LNEG, // -
401 // 0, //FNEG, // -
402 // 0, //DNEG, // -
403 // -1, //ISHL, // -
404 // -1, //LSHL, // -
405 // -1, //ISHR, // -
406 // -1, //LSHR, // -
407 // -1, //IUSHR, // -
408 // -1, //LUSHR, // -
409 // -1, //IAND, // -
410 // -2, //LAND, // -
411 // -1, //IOR, // -
412 // -2, //LOR, // -
413 // -1, //IXOR, // -
414 // -2, //LXOR, // -
415 // 0, //IINC, // visitIincInsn
416 // 1, //I2L, // visitInsn
417 // 0, //I2F, // -
418 // 1, //I2D, // -
419 // -1, //L2I, // -
420 // -1, //L2F, // -
421 // 0, //L2D, // -
422 // 0, //F2I, // -
423 // 1, //F2L, // -
424 // 1, //F2D, // -
425 // -1, //D2I, // -
426 // 0, //D2L, // -
427 // -1, //D2F, // -
428 // 0, //I2B, // -
429 // 0, //I2C, // -
430 // 0, //I2S, // -
431 // -3, //LCMP, // -
432 // -1, //FCMPL, // -
433 // -1, //FCMPG, // -
434 // -3, //DCMPL, // -
435 // -3, //DCMPG, // -
436 // -1, //IFEQ, // visitJumpInsn
437 // -1, //IFNE, // -
438 // -1, //IFLT, // -
439 // -1, //IFGE, // -
440 // -1, //IFGT, // -
441 // -1, //IFLE, // -
442 // -2, //IF_ICMPEQ, // -
443 // -2, //IF_ICMPNE, // -
444 // -2, //IF_ICMPLT, // -
445 // -2, //IF_ICMPGE, // -
446 // -2, //IF_ICMPGT, // -
447 // -2, //IF_ICMPLE, // -
448 // -2, //IF_ACMPEQ, // -
449 // -2, //IF_ACMPNE, // -
450 // 0, //GOTO, // -
451 // 1, //JSR, // -
452 // 0, //RET, // visitVarInsn
453 // -1, //TABLESWITCH, // visiTableSwitchInsn
454 // -1, //LOOKUPSWITCH, // visitLookupSwitch
455 // -1, //IRETURN, // visitInsn
456 // -2, //LRETURN, // -
457 // -1, //FRETURN, // -
458 // -2, //DRETURN, // -
459 // -1, //ARETURN, // -
460 // 0, //RETURN, // -
461 // NA, //GETSTATIC, // visitFieldInsn
462 // NA, //PUTSTATIC, // -
463 // NA, //GETFIELD, // -
464 // NA, //PUTFIELD, // -
465 // NA, //INVOKEVIRTUAL, // visitMethodInsn
466 // NA, //INVOKESPECIAL, // -
467 // NA, //INVOKESTATIC, // -
468 // NA, //INVOKEINTERFACE, // -
469 // NA, //INVOKEDYNAMIC, // visitInvokeDynamicInsn
470 // 1, //NEW, // visitTypeInsn
471 // 0, //NEWARRAY, // visitIntInsn
472 // 0, //ANEWARRAY, // visitTypeInsn
473 // 0, //ARRAYLENGTH, // visitInsn
474 // NA, //ATHROW, // -
475 // 0, //CHECKCAST, // visitTypeInsn
476 // 0, //INSTANCEOF, // -
477 // -1, //MONITORENTER, // visitInsn
478 // -1, //MONITOREXIT, // -
479 // NA, //WIDE, // NOT VISITED
480 // NA, //MULTIANEWARRAY, // visitMultiANewArrayInsn
481 // -1, //IFNULL, // visitJumpInsn
482 // -1, //IFNONNULL, // -
483 // NA, //GOTO_W, // -
484 // NA, //JSR_W, // -
485 // };
486 // for (i = 0; i < b.length; ++i) {
487 // System.err.print((char)('E' + b[i]));
488 // }
489 // System.err.println();
490 }
491
492 /**
493 * The label (i.e. basic block) to which these input and output stack map
494 * frames correspond.
495 */
496 Label owner;
497
498 /**
499 * The input stack map frame locals.
500 */
501 int[] inputLocals;
502
503 /**
504 * The input stack map frame stack.
505 */
506 int[] inputStack;
507
508 /**
509 * The output stack map frame locals.
510 */
511 private int[] outputLocals;
512
513 /**
514 * The output stack map frame stack.
515 */
516 private int[] outputStack;
517
518 /**
519 * Relative size of the output stack. The exact semantics of this field
520 * depends on the algorithm that is used.
521 *
522 * When only the maximum stack size is computed, this field is the size of
523 * the output stack relatively to the top of the input stack.
524 *
525 * When the stack map frames are completely computed, this field is the
526 * actual number of types in {@link #outputStack}.
527 */
528 int outputStackTop;
529
530 /**
531 * Number of types that are initialized in the basic block.
532 *
533 * @see #initializations
534 */
535 private int initializationCount;
536
537 /**
538 * The types that are initialized in the basic block. A constructor
539 * invocation on an UNINITIALIZED or UNINITIALIZED_THIS type must replace
540 * <i>every occurence</i> of this type in the local variables and in the
541 * operand stack. This cannot be done during the first phase of the
542 * algorithm since, during this phase, the local variables and the operand
543 * stack are not completely computed. It is therefore necessary to store the
544 * types on which constructors are invoked in the basic block, in order to
545 * do this replacement during the second phase of the algorithm, where the
546 * frames are fully computed. Note that this array can contain types that
547 * are relative to input locals or to the input stack (see below for the
548 * description of the algorithm).
549 */
550 private int[] initializations;
551
552 /**
553 * Sets this frame to the given value.
554 *
555 * @param cw
556 * the ClassWriter to which this label belongs.
557 * @param nLocal
558 * the number of local variables.
559 * @param local
560 * the local variable types. Primitive types are represented by
561 * {@link Opcodes#TOP}, {@link Opcodes#INTEGER},
562 * {@link Opcodes#FLOAT}, {@link Opcodes#LONG},
563 * {@link Opcodes#DOUBLE},{@link Opcodes#NULL} or
564 * {@link Opcodes#UNINITIALIZED_THIS} (long and double are
565 * represented by a single element). Reference types are
566 * represented by String objects (representing internal names),
567 * and uninitialized types by Label objects (this label
568 * designates the NEW instruction that created this uninitialized
569 * value).
570 * @param nStack
571 * the number of operand stack elements.
572 * @param stack
573 * the operand stack types (same format as the "local" array).
574 */
575 final void set(ClassWriter cw, final int nLocal, final Object[] local,
576 final int nStack, final Object[] stack) {
577 int i = convert(cw, nLocal, local, inputLocals);
578 while (i < local.length) {
579 inputLocals[i++] = TOP;
580 }
581 int nStackTop = 0;
582 for (int j = 0; j < nStack; ++j) {
583 if (stack[j] == Opcodes.LONG || stack[j] == Opcodes.DOUBLE) {
584 ++nStackTop;
585 }
586 }
587 inputStack = new int[nStack + nStackTop];
588 convert(cw, nStack, stack, inputStack);
589 outputStackTop = 0;
590 initializationCount = 0;
591 }
592
593 /**
594 * Converts types from the MethodWriter.visitFrame() format to the Frame
595 * format.
596 *
597 * @param cw
598 * the ClassWriter to which this label belongs.
599 * @param nInput
600 * the number of types to convert.
601 * @param input
602 * the types to convert. Primitive types are represented by
603 * {@link Opcodes#TOP}, {@link Opcodes#INTEGER},
604 * {@link Opcodes#FLOAT}, {@link Opcodes#LONG},
605 * {@link Opcodes#DOUBLE},{@link Opcodes#NULL} or
606 * {@link Opcodes#UNINITIALIZED_THIS} (long and double are
607 * represented by a single element). Reference types are
608 * represented by String objects (representing internal names),
609 * and uninitialized types by Label objects (this label
610 * designates the NEW instruction that created this uninitialized
611 * value).
612 * @param output
613 * where to store the converted types.
614 * @return the number of output elements.
615 */
616 private static int convert(ClassWriter cw, int nInput, Object[] input,
617 int[] output) {
618 int i = 0;
619 for (int j = 0; j < nInput; ++j) {
620 if (input[j] instanceof Integer) {
621 output[i++] = BASE | ((Integer) input[j]).intValue();
622 if (input[j] == Opcodes.LONG || input[j] == Opcodes.DOUBLE) {
623 output[i++] = TOP;
624 }
625 } else if (input[j] instanceof String) {
626 output[i++] = type(cw, Type.getObjectType((String) input[j])
627 .getDescriptor());
628 } else {
629 output[i++] = UNINITIALIZED
630 | cw.addUninitializedType("",
631 ((Label) input[j]).position);
632 }
633 }
634 return i;
635 }
636
637 /**
638 * Sets this frame to the value of the given frame. WARNING: after this
639 * method is called the two frames share the same data structures. It is
640 * recommended to discard the given frame f to avoid unexpected side
641 * effects.
642 *
643 * @param f
644 * The new frame value.
645 */
646 final void set(final Frame f) {
647 inputLocals = f.inputLocals;
648 inputStack = f.inputStack;
649 outputLocals = f.outputLocals;
650 outputStack = f.outputStack;
651 outputStackTop = f.outputStackTop;
652 initializationCount = f.initializationCount;
653 initializations = f.initializations;
654 }
655
656 /**
657 * Returns the output frame local variable type at the given index.
658 *
659 * @param local
660 * the index of the local that must be returned.
661 * @return the output frame local variable type at the given index.
662 */
663 private int get(final int local) {
664 if (outputLocals == null || local >= outputLocals.length) {
665 // this local has never been assigned in this basic block,
666 // so it is still equal to its value in the input frame
667 return LOCAL | local;
668 } else {
669 int type = outputLocals[local];
670 if (type == 0) {
671 // this local has never been assigned in this basic block,
672 // so it is still equal to its value in the input frame
673 type = outputLocals[local] = LOCAL | local;
674 }
675 return type;
676 }
677 }
678
679 /**
680 * Sets the output frame local variable type at the given index.
681 *
682 * @param local
683 * the index of the local that must be set.
684 * @param type
685 * the value of the local that must be set.
686 */
687 private void set(final int local, final int type) {
688 // creates and/or resizes the output local variables array if necessary
689 if (outputLocals == null) {
690 outputLocals = new int[10];
691 }
692 int n = outputLocals.length;
693 if (local >= n) {
694 int[] t = new int[Math.max(local + 1, 2 * n)];
695 System.arraycopy(outputLocals, 0, t, 0, n);
696 outputLocals = t;
697 }
698 // sets the local variable
699 outputLocals[local] = type;
700 }
701
702 /**
703 * Pushes a new type onto the output frame stack.
704 *
705 * @param type
706 * the type that must be pushed.
707 */
708 private void push(final int type) {
709 // creates and/or resizes the output stack array if necessary
710 if (outputStack == null) {
711 outputStack = new int[10];
712 }
713 int n = outputStack.length;
714 if (outputStackTop >= n) {
715 int[] t = new int[Math.max(outputStackTop + 1, 2 * n)];
716 System.arraycopy(outputStack, 0, t, 0, n);
717 outputStack = t;
718 }
719 // pushes the type on the output stack
720 outputStack[outputStackTop++] = type;
721 // updates the maximum height reached by the output stack, if needed
722 int top = owner.inputStackTop + outputStackTop;
723 if (top > owner.outputStackMax) {
724 owner.outputStackMax = top;
725 }
726 }
727
728 /**
729 * Pushes a new type onto the output frame stack.
730 *
731 * @param cw
732 * the ClassWriter to which this label belongs.
733 * @param desc
734 * the descriptor of the type to be pushed. Can also be a method
735 * descriptor (in this case this method pushes its return type
736 * onto the output frame stack).
737 */
738 private void push(final ClassWriter cw, final String desc) {
739 int type = type(cw, desc);
740 if (type != 0) {
741 push(type);
742 if (type == LONG || type == DOUBLE) {
743 push(TOP);
744 }
745 }
746 }
747
748 /**
749 * Returns the int encoding of the given type.
750 *
751 * @param cw
752 * the ClassWriter to which this label belongs.
753 * @param desc
754 * a type descriptor.
755 * @return the int encoding of the given type.
756 */
757 static int type(final ClassWriter cw, final String desc) {
758 String t;
759 int index = desc.charAt(0) == '(' ? desc.indexOf(')') + 1 : 0;
760 switch (desc.charAt(index)) {
761 case 'V':
762 return 0;
763 case 'Z':
764 case 'C':
765 case 'B':
766 case 'S':
767 case 'I':
768 return INTEGER;
769 case 'F':
770 return FLOAT;
771 case 'J':
772 return LONG;
773 case 'D':
774 return DOUBLE;
775 case 'L':
776 // stores the internal name, not the descriptor!
777 t = desc.substring(index + 1, desc.length() - 1);
778 return OBJECT | cw.addType(t);
779 // case '[':
780 default:
781 // extracts the dimensions and the element type
782 int data;
783 int dims = index + 1;
784 while (desc.charAt(dims) == '[') {
785 ++dims;
786 }
787 switch (desc.charAt(dims)) {
788 case 'Z':
789 data = BOOLEAN;
790 break;
791 case 'C':
792 data = CHAR;
793 break;
794 case 'B':
795 data = BYTE;
796 break;
797 case 'S':
798 data = SHORT;
799 break;
800 case 'I':
801 data = INTEGER;
802 break;
803 case 'F':
804 data = FLOAT;
805 break;
806 case 'J':
807 data = LONG;
808 break;
809 case 'D':
810 data = DOUBLE;
811 break;
812 // case 'L':
813 default:
814 // stores the internal name, not the descriptor
815 t = desc.substring(dims + 1, desc.length() - 1);
816 data = OBJECT | cw.addType(t);
817 }
818 return (dims - index) << 28 | data;
819 }
820 }
821
822 /**
823 * Pops a type from the output frame stack and returns its value.
824 *
825 * @return the type that has been popped from the output frame stack.
826 */
827 private int pop() {
828 if (outputStackTop > 0) {
829 return outputStack[--outputStackTop];
830 } else {
831 // if the output frame stack is empty, pops from the input stack
832 return STACK | -(--owner.inputStackTop);
833 }
834 }
835
836 /**
837 * Pops the given number of types from the output frame stack.
838 *
839 * @param elements
840 * the number of types that must be popped.
841 */
842 private void pop(final int elements) {
843 if (outputStackTop >= elements) {
844 outputStackTop -= elements;
845 } else {
846 // if the number of elements to be popped is greater than the number
847 // of elements in the output stack, clear it, and pops the remaining
848 // elements from the input stack.
849 owner.inputStackTop -= elements - outputStackTop;
850 outputStackTop = 0;
851 }
852 }
853
854 /**
855 * Pops a type from the output frame stack.
856 *
857 * @param desc
858 * the descriptor of the type to be popped. Can also be a method
859 * descriptor (in this case this method pops the types
860 * corresponding to the method arguments).
861 */
862 private void pop(final String desc) {
863 char c = desc.charAt(0);
864 if (c == '(') {
865 pop((Type.getArgumentsAndReturnSizes(desc) >> 2) - 1);
866 } else if (c == 'J' || c == 'D') {
867 pop(2);
868 } else {
869 pop(1);
870 }
871 }
872
873 /**
874 * Adds a new type to the list of types on which a constructor is invoked in
875 * the basic block.
876 *
877 * @param var
878 * a type on a which a constructor is invoked.
879 */
880 private void init(final int var) {
881 // creates and/or resizes the initializations array if necessary
882 if (initializations == null) {
883 initializations = new int[2];
884 }
885 int n = initializations.length;
886 if (initializationCount >= n) {
887 int[] t = new int[Math.max(initializationCount + 1, 2 * n)];
888 System.arraycopy(initializations, 0, t, 0, n);
889 initializations = t;
890 }
891 // stores the type to be initialized
892 initializations[initializationCount++] = var;
893 }
894
895 /**
896 * Replaces the given type with the appropriate type if it is one of the
897 * types on which a constructor is invoked in the basic block.
898 *
899 * @param cw
900 * the ClassWriter to which this label belongs.
901 * @param t
902 * a type
903 * @return t or, if t is one of the types on which a constructor is invoked
904 * in the basic block, the type corresponding to this constructor.
905 */
906 private int init(final ClassWriter cw, final int t) {
907 int s;
908 if (t == UNINITIALIZED_THIS) {
909 s = OBJECT | cw.addType(cw.thisName);
910 } else if ((t & (DIM | BASE_KIND)) == UNINITIALIZED) {
911 String type = cw.typeTable[t & BASE_VALUE].strVal1;
912 s = OBJECT | cw.addType(type);
913 } else {
914 return t;
915 }
916 for (int j = 0; j < initializationCount; ++j) {
917 int u = initializations[j];
918 int dim = u & DIM;
919 int kind = u & KIND;
920 if (kind == LOCAL) {
921 u = dim + inputLocals[u & VALUE];
922 } else if (kind == STACK) {
923 u = dim + inputStack[inputStack.length - (u & VALUE)];
924 }
925 if (t == u) {
926 return s;
927 }
928 }
929 return t;
930 }
931
932 /**
933 * Initializes the input frame of the first basic block from the method
934 * descriptor.
935 *
936 * @param cw
937 * the ClassWriter to which this label belongs.
938 * @param access
939 * the access flags of the method to which this label belongs.
940 * @param args
941 * the formal parameter types of this method.
942 * @param maxLocals
943 * the maximum number of local variables of this method.
944 */
945 final void initInputFrame(final ClassWriter cw, final int access,
946 final Type[] args, final int maxLocals) {
947 inputLocals = new int[maxLocals];
948 inputStack = new int[0];
949 int i = 0;
950 if ((access & Opcodes.ACC_STATIC) == 0) {
951 if ((access & MethodWriter.ACC_CONSTRUCTOR) == 0) {
952 inputLocals[i++] = OBJECT | cw.addType(cw.thisName);
953 } else {
954 inputLocals[i++] = UNINITIALIZED_THIS;
955 }
956 }
957 for (int j = 0; j < args.length; ++j) {
958 int t = type(cw, args[j].getDescriptor());
959 inputLocals[i++] = t;
960 if (t == LONG || t == DOUBLE) {
961 inputLocals[i++] = TOP;
962 }
963 }
964 while (i < maxLocals) {
965 inputLocals[i++] = TOP;
966 }
967 }
968
969 /**
970 * Simulates the action of the given instruction on the output stack frame.
971 *
972 * @param opcode
973 * the opcode of the instruction.
974 * @param arg
975 * the operand of the instruction, if any.
976 * @param cw
977 * the class writer to which this label belongs.
978 * @param item
979 * the operand of the instructions, if any.
980 */
981 void execute(final int opcode, final int arg, final ClassWriter cw,
982 final Item item) {
983 int t1, t2, t3, t4;
984 switch (opcode) {
985 case Opcodes.NOP:
986 case Opcodes.INEG:
987 case Opcodes.LNEG:
988 case Opcodes.FNEG:
989 case Opcodes.DNEG:
990 case Opcodes.I2B:
991 case Opcodes.I2C:
992 case Opcodes.I2S:
993 case Opcodes.GOTO:
994 case Opcodes.RETURN:
995 break;
996 case Opcodes.ACONST_NULL:
997 push(NULL);
998 break;
999 case Opcodes.ICONST_M1:
1000 case Opcodes.ICONST_0:
1001 case Opcodes.ICONST_1:
1002 case Opcodes.ICONST_2:
1003 case Opcodes.ICONST_3:
1004 case Opcodes.ICONST_4:
1005 case Opcodes.ICONST_5:
1006 case Opcodes.BIPUSH:
1007 case Opcodes.SIPUSH:
1008 case Opcodes.ILOAD:
1009 push(INTEGER);
1010 break;
1011 case Opcodes.LCONST_0:
1012 case Opcodes.LCONST_1:
1013 case Opcodes.LLOAD:
1014 push(LONG);
1015 push(TOP);
1016 break;
1017 case Opcodes.FCONST_0:
1018 case Opcodes.FCONST_1:
1019 case Opcodes.FCONST_2:
1020 case Opcodes.FLOAD:
1021 push(FLOAT);
1022 break;
1023 case Opcodes.DCONST_0:
1024 case Opcodes.DCONST_1:
1025 case Opcodes.DLOAD:
1026 push(DOUBLE);
1027 push(TOP);
1028 break;
1029 case Opcodes.LDC:
1030 switch (item.type) {
1031 case ClassWriter.INT:
1032 push(INTEGER);
1033 break;
1034 case ClassWriter.LONG:
1035 push(LONG);
1036 push(TOP);
1037 break;
1038 case ClassWriter.FLOAT:
1039 push(FLOAT);
1040 break;
1041 case ClassWriter.DOUBLE:
1042 push(DOUBLE);
1043 push(TOP);
1044 break;
1045 case ClassWriter.CLASS:
1046 push(OBJECT | cw.addType("java/lang/Class"));
1047 break;
1048 case ClassWriter.STR:
1049 push(OBJECT | cw.addType("java/lang/String"));
1050 break;
1051 case ClassWriter.MTYPE:
1052 push(OBJECT | cw.addType("java/lang/invoke/MethodType"));
1053 break;
1054 // case ClassWriter.HANDLE_BASE + [1..9]:
1055 default:
1056 push(OBJECT | cw.addType("java/lang/invoke/MethodHandle"));
1057 }
1058 break;
1059 case Opcodes.ALOAD:
1060 push(get(arg));
1061 break;
1062 case Opcodes.IALOAD:
1063 case Opcodes.BALOAD:
1064 case Opcodes.CALOAD:
1065 case Opcodes.SALOAD:
1066 pop(2);
1067 push(INTEGER);
1068 break;
1069 case Opcodes.LALOAD:
1070 case Opcodes.D2L:
1071 pop(2);
1072 push(LONG);
1073 push(TOP);
1074 break;
1075 case Opcodes.FALOAD:
1076 pop(2);
1077 push(FLOAT);
1078 break;
1079 case Opcodes.DALOAD:
1080 case Opcodes.L2D:
1081 pop(2);
1082 push(DOUBLE);
1083 push(TOP);
1084 break;
1085 case Opcodes.AALOAD:
1086 pop(1);
1087 t1 = pop();
1088 push(t1 == NULL ? t1 : ELEMENT_OF + t1);
1089 break;
1090 case Opcodes.ISTORE:
1091 case Opcodes.FSTORE:
1092 case Opcodes.ASTORE:
1093 t1 = pop();
1094 set(arg, t1);
1095 if (arg > 0) {
1096 t2 = get(arg - 1);
1097 // if t2 is of kind STACK or LOCAL we cannot know its size!
1098 if (t2 == LONG || t2 == DOUBLE) {
1099 set(arg - 1, TOP);
1100 } else if ((t2 & KIND) != BASE) {
1101 set(arg - 1, t2 | TOP_IF_LONG_OR_DOUBLE);
1102 }
1103 }
1104 break;
1105 case Opcodes.LSTORE:
1106 case Opcodes.DSTORE:
1107 pop(1);
1108 t1 = pop();
1109 set(arg, t1);
1110 set(arg + 1, TOP);
1111 if (arg > 0) {
1112 t2 = get(arg - 1);
1113 // if t2 is of kind STACK or LOCAL we cannot know its size!
1114 if (t2 == LONG || t2 == DOUBLE) {
1115 set(arg - 1, TOP);
1116 } else if ((t2 & KIND) != BASE) {
1117 set(arg - 1, t2 | TOP_IF_LONG_OR_DOUBLE);
1118 }
1119 }
1120 break;
1121 case Opcodes.IASTORE:
1122 case Opcodes.BASTORE:
1123 case Opcodes.CASTORE:
1124 case Opcodes.SASTORE:
1125 case Opcodes.FASTORE:
1126 case Opcodes.AASTORE:
1127 pop(3);
1128 break;
1129 case Opcodes.LASTORE:
1130 case Opcodes.DASTORE:
1131 pop(4);
1132 break;
1133 case Opcodes.POP:
1134 case Opcodes.IFEQ:
1135 case Opcodes.IFNE:
1136 case Opcodes.IFLT:
1137 case Opcodes.IFGE:
1138 case Opcodes.IFGT:
1139 case Opcodes.IFLE:
1140 case Opcodes.IRETURN:
1141 case Opcodes.FRETURN:
1142 case Opcodes.ARETURN:
1143 case Opcodes.TABLESWITCH:
1144 case Opcodes.LOOKUPSWITCH:
1145 case Opcodes.ATHROW:
1146 case Opcodes.MONITORENTER:
1147 case Opcodes.MONITOREXIT:
1148 case Opcodes.IFNULL:
1149 case Opcodes.IFNONNULL:
1150 pop(1);
1151 break;
1152 case Opcodes.POP2:
1153 case Opcodes.IF_ICMPEQ:
1154 case Opcodes.IF_ICMPNE:
1155 case Opcodes.IF_ICMPLT:
1156 case Opcodes.IF_ICMPGE:
1157 case Opcodes.IF_ICMPGT:
1158 case Opcodes.IF_ICMPLE:
1159 case Opcodes.IF_ACMPEQ:
1160 case Opcodes.IF_ACMPNE:
1161 case Opcodes.LRETURN:
1162 case Opcodes.DRETURN:
1163 pop(2);
1164 break;
1165 case Opcodes.DUP:
1166 t1 = pop();
1167 push(t1);
1168 push(t1);
1169 break;
1170 case Opcodes.DUP_X1:
1171 t1 = pop();
1172 t2 = pop();
1173 push(t1);
1174 push(t2);
1175 push(t1);
1176 break;
1177 case Opcodes.DUP_X2:
1178 t1 = pop();
1179 t2 = pop();
1180 t3 = pop();
1181 push(t1);
1182 push(t3);
1183 push(t2);
1184 push(t1);
1185 break;
1186 case Opcodes.DUP2:
1187 t1 = pop();
1188 t2 = pop();
1189 push(t2);
1190 push(t1);
1191 push(t2);
1192 push(t1);
1193 break;
1194 case Opcodes.DUP2_X1:
1195 t1 = pop();
1196 t2 = pop();
1197 t3 = pop();
1198 push(t2);
1199 push(t1);
1200 push(t3);
1201 push(t2);
1202 push(t1);
1203 break;
1204 case Opcodes.DUP2_X2:
1205 t1 = pop();
1206 t2 = pop();
1207 t3 = pop();
1208 t4 = pop();
1209 push(t2);
1210 push(t1);
1211 push(t4);
1212 push(t3);
1213 push(t2);
1214 push(t1);
1215 break;
1216 case Opcodes.SWAP:
1217 t1 = pop();
1218 t2 = pop();
1219 push(t1);
1220 push(t2);
1221 break;
1222 case Opcodes.IADD:
1223 case Opcodes.ISUB:
1224 case Opcodes.IMUL:
1225 case Opcodes.IDIV:
1226 case Opcodes.IREM:
1227 case Opcodes.IAND:
1228 case Opcodes.IOR:
1229 case Opcodes.IXOR:
1230 case Opcodes.ISHL:
1231 case Opcodes.ISHR:
1232 case Opcodes.IUSHR:
1233 case Opcodes.L2I:
1234 case Opcodes.D2I:
1235 case Opcodes.FCMPL:
1236 case Opcodes.FCMPG:
1237 pop(2);
1238 push(INTEGER);
1239 break;
1240 case Opcodes.LADD:
1241 case Opcodes.LSUB:
1242 case Opcodes.LMUL:
1243 case Opcodes.LDIV:
1244 case Opcodes.LREM:
1245 case Opcodes.LAND:
1246 case Opcodes.LOR:
1247 case Opcodes.LXOR:
1248 pop(4);
1249 push(LONG);
1250 push(TOP);
1251 break;
1252 case Opcodes.FADD:
1253 case Opcodes.FSUB:
1254 case Opcodes.FMUL:
1255 case Opcodes.FDIV:
1256 case Opcodes.FREM:
1257 case Opcodes.L2F:
1258 case Opcodes.D2F:
1259 pop(2);
1260 push(FLOAT);
1261 break;
1262 case Opcodes.DADD:
1263 case Opcodes.DSUB:
1264 case Opcodes.DMUL:
1265 case Opcodes.DDIV:
1266 case Opcodes.DREM:
1267 pop(4);
1268 push(DOUBLE);
1269 push(TOP);
1270 break;
1271 case Opcodes.LSHL:
1272 case Opcodes.LSHR:
1273 case Opcodes.LUSHR:
1274 pop(3);
1275 push(LONG);
1276 push(TOP);
1277 break;
1278 case Opcodes.IINC:
1279 set(arg, INTEGER);
1280 break;
1281 case Opcodes.I2L:
1282 case Opcodes.F2L:
1283 pop(1);
1284 push(LONG);
1285 push(TOP);
1286 break;
1287 case Opcodes.I2F:
1288 pop(1);
1289 push(FLOAT);
1290 break;
1291 case Opcodes.I2D:
1292 case Opcodes.F2D:
1293 pop(1);
1294 push(DOUBLE);
1295 push(TOP);
1296 break;
1297 case Opcodes.F2I:
1298 case Opcodes.ARRAYLENGTH:
1299 case Opcodes.INSTANCEOF:
1300 pop(1);
1301 push(INTEGER);
1302 break;
1303 case Opcodes.LCMP:
1304 case Opcodes.DCMPL:
1305 case Opcodes.DCMPG:
1306 pop(4);
1307 push(INTEGER);
1308 break;
1309 case Opcodes.JSR:
1310 case Opcodes.RET:
1311 throw new RuntimeException(
1312 "JSR/RET are not supported with computeFrames option");
1313 case Opcodes.GETSTATIC:
1314 push(cw, item.strVal3);
1315 break;
1316 case Opcodes.PUTSTATIC:
1317 pop(item.strVal3);
1318 break;
1319 case Opcodes.GETFIELD:
1320 pop(1);
1321 push(cw, item.strVal3);
1322 break;
1323 case Opcodes.PUTFIELD:
1324 pop(item.strVal3);
1325 pop();
1326 break;
1327 case Opcodes.INVOKEVIRTUAL:
1328 case Opcodes.INVOKESPECIAL:
1329 case Opcodes.INVOKESTATIC:
1330 case Opcodes.INVOKEINTERFACE:
1331 pop(item.strVal3);
1332 if (opcode != Opcodes.INVOKESTATIC) {
1333 t1 = pop();
1334 if (opcode == Opcodes.INVOKESPECIAL
1335 && item.strVal2.charAt(0) == '<') {
1336 init(t1);
1337 }
1338 }
1339 push(cw, item.strVal3);
1340 break;
1341 case Opcodes.INVOKEDYNAMIC:
1342 pop(item.strVal2);
1343 push(cw, item.strVal2);
1344 break;
1345 case Opcodes.NEW:
1346 push(UNINITIALIZED | cw.addUninitializedType(item.strVal1, arg));
1347 break;
1348 case Opcodes.NEWARRAY:
1349 pop();
1350 switch (arg) {
1351 case Opcodes.T_BOOLEAN:
1352 push(ARRAY_OF | BOOLEAN);
1353 break;
1354 case Opcodes.T_CHAR:
1355 push(ARRAY_OF | CHAR);
1356 break;
1357 case Opcodes.T_BYTE:
1358 push(ARRAY_OF | BYTE);
1359 break;
1360 case Opcodes.T_SHORT:
1361 push(ARRAY_OF | SHORT);
1362 break;
1363 case Opcodes.T_INT:
1364 push(ARRAY_OF | INTEGER);
1365 break;
1366 case Opcodes.T_FLOAT:
1367 push(ARRAY_OF | FLOAT);
1368 break;
1369 case Opcodes.T_DOUBLE:
1370 push(ARRAY_OF | DOUBLE);
1371 break;
1372 // case Opcodes.T_LONG:
1373 default:
1374 push(ARRAY_OF | LONG);
1375 break;
1376 }
1377 break;
1378 case Opcodes.ANEWARRAY:
1379 String s = item.strVal1;
1380 pop();
1381 if (s.charAt(0) == '[') {
1382 push(cw, '[' + s);
1383 } else {
1384 push(ARRAY_OF | OBJECT | cw.addType(s));
1385 }
1386 break;
1387 case Opcodes.CHECKCAST:
1388 s = item.strVal1;
1389 pop();
1390 if (s.charAt(0) == '[') {
1391 push(cw, s);
1392 } else {
1393 push(OBJECT | cw.addType(s));
1394 }
1395 break;
1396 // case Opcodes.MULTIANEWARRAY:
1397 default:
1398 pop(arg);
1399 push(cw, item.strVal1);
1400 break;
1401 }
1402 }
1403
1404 /**
1405 * Merges the input frame of the given basic block with the input and output
1406 * frames of this basic block. Returns <tt>true</tt> if the input frame of
1407 * the given label has been changed by this operation.
1408 *
1409 * @param cw
1410 * the ClassWriter to which this label belongs.
1411 * @param frame
1412 * the basic block whose input frame must be updated.
1413 * @param edge
1414 * the kind of the {@link Edge} between this label and 'label'.
1415 * See {@link Edge#info}.
1416 * @return <tt>true</tt> if the input frame of the given label has been
1417 * changed by this operation.
1418 */
1419 final boolean merge(final ClassWriter cw, final Frame frame, final int edge) {
1420 boolean changed = false;
1421 int i, s, dim, kind, t;
1422
1423 int nLocal = inputLocals.length;
1424 int nStack = inputStack.length;
1425 if (frame.inputLocals == null) {
1426 frame.inputLocals = new int[nLocal];
1427 changed = true;
1428 }
1429
1430 for (i = 0; i < nLocal; ++i) {
1431 if (outputLocals != null && i < outputLocals.length) {
1432 s = outputLocals[i];
1433 if (s == 0) {
1434 t = inputLocals[i];
1435 } else {
1436 dim = s & DIM;
1437 kind = s & KIND;
1438 if (kind == BASE) {
1439 t = s;
1440 } else {
1441 if (kind == LOCAL) {
1442 t = dim + inputLocals[s & VALUE];
1443 } else {
1444 t = dim + inputStack[nStack - (s & VALUE)];
1445 }
1446 if ((s & TOP_IF_LONG_OR_DOUBLE) != 0
1447 && (t == LONG || t == DOUBLE)) {
1448 t = TOP;
1449 }
1450 }
1451 }
1452 } else {
1453 t = inputLocals[i];
1454 }
1455 if (initializations != null) {
1456 t = init(cw, t);
1457 }
1458 changed |= merge(cw, t, frame.inputLocals, i);
1459 }
1460
1461 if (edge > 0) {
1462 for (i = 0; i < nLocal; ++i) {
1463 t = inputLocals[i];
1464 changed |= merge(cw, t, frame.inputLocals, i);
1465 }
1466 if (frame.inputStack == null) {
1467 frame.inputStack = new int[1];
1468 changed = true;
1469 }
1470 changed |= merge(cw, edge, frame.inputStack, 0);
1471 return changed;
1472 }
1473
1474 int nInputStack = inputStack.length + owner.inputStackTop;
1475 if (frame.inputStack == null) {
1476 frame.inputStack = new int[nInputStack + outputStackTop];
1477 changed = true;
1478 }
1479
1480 for (i = 0; i < nInputStack; ++i) {
1481 t = inputStack[i];
1482 if (initializations != null) {
1483 t = init(cw, t);
1484 }
1485 changed |= merge(cw, t, frame.inputStack, i);
1486 }
1487 for (i = 0; i < outputStackTop; ++i) {
1488 s = outputStack[i];
1489 dim = s & DIM;
1490 kind = s & KIND;
1491 if (kind == BASE) {
1492 t = s;
1493 } else {
1494 if (kind == LOCAL) {
1495 t = dim + inputLocals[s & VALUE];
1496 } else {
1497 t = dim + inputStack[nStack - (s & VALUE)];
1498 }
1499 if ((s & TOP_IF_LONG_OR_DOUBLE) != 0
1500 && (t == LONG || t == DOUBLE)) {
1501 t = TOP;
1502 }
1503 }
1504 if (initializations != null) {
1505 t = init(cw, t);
1506 }
1507 changed |= merge(cw, t, frame.inputStack, nInputStack + i);
1508 }
1509 return changed;
1510 }
1511
1512 /**
1513 * Merges the type at the given index in the given type array with the given
1514 * type. Returns <tt>true</tt> if the type array has been modified by this
1515 * operation.
1516 *
1517 * @param cw
1518 * the ClassWriter to which this label belongs.
1519 * @param t
1520 * the type with which the type array element must be merged.
1521 * @param types
1522 * an array of types.
1523 * @param index
1524 * the index of the type that must be merged in 'types'.
1525 * @return <tt>true</tt> if the type array has been modified by this
1526 * operation.
1527 */
1528 private static boolean merge(final ClassWriter cw, int t,
1529 final int[] types, final int index) {
1530 int u = types[index];
1531 if (u == t) {
1532 // if the types are equal, merge(u,t)=u, so there is no change
1533 return false;
1534 }
1535 if ((t & ~DIM) == NULL) {
1536 if (u == NULL) {
1537 return false;
1538 }
1539 t = NULL;
1540 }
1541 if (u == 0) {
1542 // if types[index] has never been assigned, merge(u,t)=t
1543 types[index] = t;
1544 return true;
1545 }
1546 int v;
1547 if ((u & BASE_KIND) == OBJECT || (u & DIM) != 0) {
1548 // if u is a reference type of any dimension
1549 if (t == NULL) {
1550 // if t is the NULL type, merge(u,t)=u, so there is no change
1551 return false;
1552 } else if ((t & (DIM | BASE_KIND)) == (u & (DIM | BASE_KIND))) {
1553 // if t and u have the same dimension and same base kind
1554 if ((u & BASE_KIND) == OBJECT) {
1555 // if t is also a reference type, and if u and t have the
1556 // same dimension merge(u,t) = dim(t) | common parent of the
1557 // element types of u and t
1558 v = (t & DIM) | OBJECT
1559 | cw.getMergedType(t & BASE_VALUE, u & BASE_VALUE);
1560 } else {
1561 // if u and t are array types, but not with the same element
1562 // type, merge(u,t) = dim(u) - 1 | java/lang/Object
1563 int vdim = ELEMENT_OF + (u & DIM);
1564 v = vdim | OBJECT | cw.addType("java/lang/Object");
1565 }
1566 } else if ((t & BASE_KIND) == OBJECT || (t & DIM) != 0) {
1567 // if t is any other reference or array type, the merged type
1568 // is min(udim, tdim) | java/lang/Object, where udim is the
1569 // array dimension of u, minus 1 if u is an array type with a
1570 // primitive element type (and similarly for tdim).
1571 int tdim = (((t & DIM) == 0 || (t & BASE_KIND) == OBJECT) ? 0
1572 : ELEMENT_OF) + (t & DIM);
1573 int udim = (((u & DIM) == 0 || (u & BASE_KIND) == OBJECT) ? 0
1574 : ELEMENT_OF) + (u & DIM);
1575 v = Math.min(tdim, udim) | OBJECT
1576 | cw.addType("java/lang/Object");
1577 } else {
1578 // if t is any other type, merge(u,t)=TOP
1579 v = TOP;
1580 }
1581 } else if (u == NULL) {
1582 // if u is the NULL type, merge(u,t)=t,
1583 // or TOP if t is not a reference type
1584 v = (t & BASE_KIND) == OBJECT || (t & DIM) != 0 ? t : TOP;
1585 } else {
1586 // if u is any other type, merge(u,t)=TOP whatever t
1587 v = TOP;
1588 }
1589 if (u != v) {
1590 types[index] = v;
1591 return true;
1592 }
1593 return false;
1594 }
1595 }