Thu, 21 Feb 2008 14:03:41 -0800
6621084: ciMethodBlocks::split_block_at() is broken for methods with exception handler
Summary: After an exception handler block is split the exception information is not moved to the new block which starts in exception handler BCI.
Reviewed-by: jrose
1 /*
2 * Copyright 2006 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 #include "incls/_precompiled.incl"
26 #include "incls/_ciMethodBlocks.cpp.incl"
28 // ciMethodBlocks
32 ciBlock *ciMethodBlocks::block_containing(int bci) {
33 ciBlock *blk = _bci_to_block[bci];
34 return blk;
35 }
37 bool ciMethodBlocks::is_block_start(int bci) {
38 assert(bci >=0 && bci < _code_size, "valid bytecode range");
39 ciBlock *b = _bci_to_block[bci];
40 assert(b != NULL, "must have block for bytecode");
41 return b->start_bci() == bci;
42 }
44 // ------------------------------------------------------------------
45 // ciMethodBlocks::split_block_at
46 //
47 // Split the block spanning bci into two separate ranges. The former
48 // block becomes the second half and a new range is created for the
49 // first half. Returns the range beginning at bci.
50 ciBlock *ciMethodBlocks::split_block_at(int bci) {
51 ciBlock *former_block = block_containing(bci);
52 ciBlock *new_block = new(_arena) ciBlock(_method, _num_blocks++, this, former_block->start_bci());
53 _blocks->append(new_block);
54 assert(former_block != NULL, "must not be NULL");
55 new_block->set_limit_bci(bci);
56 former_block->set_start_bci(bci);
57 for (int pos=bci-1; pos >= 0; pos--) {
58 ciBlock *current_block = block_containing(pos);
59 if (current_block == former_block) {
60 // Replace it.
61 _bci_to_block[pos] = new_block;
62 } else if (current_block == NULL) {
63 // Non-bytecode start. Skip.
64 continue;
65 } else {
66 // We are done with our backwards walk
67 break;
68 }
69 }
70 // Move an exception handler information if needed.
71 if (former_block->is_handler()) {
72 int ex_start = former_block->ex_start_bci();
73 int ex_end = former_block->ex_limit_bci();
74 new_block->set_exception_range(ex_start, ex_end);
75 // Clear information in former_block.
76 former_block->clear_exception_handler();
77 }
78 return former_block;
79 }
81 ciBlock *ciMethodBlocks::make_block_at(int bci) {
82 ciBlock *cb = block_containing(bci);
83 if (cb == NULL ) {
84 // This is our first time visiting this bytecode. Create
85 // a fresh block and assign it this starting point.
86 ciBlock *nb = new(_arena) ciBlock(_method, _num_blocks++, this, bci);
87 _blocks->append(nb);
88 _bci_to_block[bci] = nb;
89 return nb;
90 } else if (cb->start_bci() == bci) {
91 // The block begins at bci. Simply return it.
92 return cb;
93 } else {
94 // We have already created a block containing bci but
95 // not starting at bci. This existing block needs to
96 // be split into two.
97 return split_block_at(bci);
98 }
99 }
101 void ciMethodBlocks::do_analysis() {
102 ciBytecodeStream s(_method);
103 ciBlock *cur_block = block_containing(0);
104 int limit_bci = _method->code_size();
106 while (s.next() != ciBytecodeStream::EOBC()) {
107 int bci = s.cur_bci();
108 // Determine if a new block has been made at the current bci. If
109 // this block differs from our current range, switch to the new
110 // one and end the old one.
111 assert(cur_block != NULL, "must always have a current block");
112 ciBlock *new_block = block_containing(bci);
113 if (new_block == NULL || new_block == cur_block) {
114 // We have not marked this bci as the start of a new block.
115 // Keep interpreting the current_range.
116 _bci_to_block[bci] = cur_block;
117 } else {
118 cur_block->set_limit_bci(bci);
119 cur_block = new_block;
120 }
122 switch (s.cur_bc()) {
123 case Bytecodes::_ifeq :
124 case Bytecodes::_ifne :
125 case Bytecodes::_iflt :
126 case Bytecodes::_ifge :
127 case Bytecodes::_ifgt :
128 case Bytecodes::_ifle :
129 case Bytecodes::_if_icmpeq :
130 case Bytecodes::_if_icmpne :
131 case Bytecodes::_if_icmplt :
132 case Bytecodes::_if_icmpge :
133 case Bytecodes::_if_icmpgt :
134 case Bytecodes::_if_icmple :
135 case Bytecodes::_if_acmpeq :
136 case Bytecodes::_if_acmpne :
137 case Bytecodes::_ifnull :
138 case Bytecodes::_ifnonnull :
139 {
140 cur_block->set_control_bci(bci);
141 ciBlock *fall_through = make_block_at(s.next_bci());
142 int dest_bci = s.get_dest();
143 ciBlock *dest = make_block_at(dest_bci);
144 break;
145 }
147 case Bytecodes::_goto :
148 {
149 cur_block->set_control_bci(bci);
150 if (s.next_bci() < limit_bci) {
151 (void) make_block_at(s.next_bci());
152 }
153 int dest_bci = s.get_dest();
154 ciBlock *dest = make_block_at(dest_bci);
155 break;
156 }
158 case Bytecodes::_jsr :
159 {
160 cur_block->set_control_bci(bci);
161 ciBlock *ret = make_block_at(s.next_bci());
162 int dest_bci = s.get_dest();
163 ciBlock *dest = make_block_at(dest_bci);
164 break;
165 }
167 case Bytecodes::_tableswitch :
168 {
169 cur_block->set_control_bci(bci);
170 Bytecode_tableswitch* switch_ = Bytecode_tableswitch_at(s.cur_bcp());
171 int len = switch_->length();
172 ciBlock *dest;
173 int dest_bci;
174 for (int i = 0; i < len; i++) {
175 dest_bci = s.cur_bci() + switch_->dest_offset_at(i);
176 dest = make_block_at(dest_bci);
177 }
178 dest_bci = s.cur_bci() + switch_->default_offset();
179 make_block_at(dest_bci);
180 if (s.next_bci() < limit_bci) {
181 dest = make_block_at(s.next_bci());
182 }
183 }
184 break;
186 case Bytecodes::_lookupswitch:
187 {
188 cur_block->set_control_bci(bci);
189 Bytecode_lookupswitch* switch_ = Bytecode_lookupswitch_at(s.cur_bcp());
190 int len = switch_->number_of_pairs();
191 ciBlock *dest;
192 int dest_bci;
193 for (int i = 0; i < len; i++) {
194 dest_bci = s.cur_bci() + switch_->pair_at(i)->offset();
195 dest = make_block_at(dest_bci);
196 }
197 dest_bci = s.cur_bci() + switch_->default_offset();
198 dest = make_block_at(dest_bci);
199 if (s.next_bci() < limit_bci) {
200 dest = make_block_at(s.next_bci());
201 }
202 }
203 break;
205 case Bytecodes::_goto_w :
206 {
207 cur_block->set_control_bci(bci);
208 if (s.next_bci() < limit_bci) {
209 (void) make_block_at(s.next_bci());
210 }
211 int dest_bci = s.get_far_dest();
212 ciBlock *dest = make_block_at(dest_bci);
213 break;
214 }
216 case Bytecodes::_jsr_w :
217 {
218 cur_block->set_control_bci(bci);
219 ciBlock *ret = make_block_at(s.next_bci());
220 int dest_bci = s.get_far_dest();
221 ciBlock *dest = make_block_at(dest_bci);
222 break;
223 }
225 case Bytecodes::_athrow :
226 cur_block->set_may_throw();
227 // fall-through
228 case Bytecodes::_ret :
229 case Bytecodes::_ireturn :
230 case Bytecodes::_lreturn :
231 case Bytecodes::_freturn :
232 case Bytecodes::_dreturn :
233 case Bytecodes::_areturn :
234 case Bytecodes::_return :
235 cur_block->set_control_bci(bci);
236 if (s.next_bci() < limit_bci) {
237 (void) make_block_at(s.next_bci());
238 }
239 break;
240 }
241 }
242 // End the last block
243 cur_block->set_limit_bci(limit_bci);
244 }
246 ciMethodBlocks::ciMethodBlocks(Arena *arena, ciMethod *meth): _method(meth),
247 _arena(arena), _num_blocks(0), _code_size(meth->code_size()) {
248 int block_estimate = _code_size / 8;
250 _blocks = new(_arena) GrowableArray<ciBlock *>(block_estimate);
251 int b2bsize = _code_size * sizeof(ciBlock **);
252 _bci_to_block = (ciBlock **) arena->Amalloc(b2bsize);
253 Copy::zero_to_words((HeapWord*) _bci_to_block, b2bsize / sizeof(HeapWord));
255 // create initial block covering the entire method
256 ciBlock *b = new(arena) ciBlock(_method, _num_blocks++, this, 0);
257 _blocks->append(b);
258 _bci_to_block[0] = b;
260 // create blocks for exception handlers
261 if (meth->has_exception_handlers()) {
262 for(ciExceptionHandlerStream str(meth); !str.is_done(); str.next()) {
263 ciExceptionHandler* handler = str.handler();
264 ciBlock *eb = make_block_at(handler->handler_bci());
265 //
266 // Several exception handlers can have the same handler_bci:
267 //
268 // try {
269 // if (a.foo(b) < 0) {
270 // return a.error();
271 // }
272 // return CoderResult.UNDERFLOW;
273 // } finally {
274 // a.position(b);
275 // }
276 //
277 // The try block above is divided into 2 exception blocks
278 // separated by 'areturn' bci.
279 //
280 int ex_start = handler->start();
281 int ex_end = handler->limit();
282 if (eb->is_handler()) {
283 // Extend old handler exception range to cover additional range.
284 int old_ex_start = eb->ex_start_bci();
285 int old_ex_end = eb->ex_limit_bci();
286 if (ex_start > old_ex_start)
287 ex_start = old_ex_start;
288 if (ex_end < old_ex_end)
289 ex_end = old_ex_end;
290 eb->clear_exception_handler(); // Reset exception information
291 }
292 eb->set_exception_range(ex_start, ex_end);
293 // ensure a block at the start of exception range and start of following code
294 (void) make_block_at(ex_start);
295 if (ex_end < _code_size)
296 (void) make_block_at(ex_end);
297 }
298 }
300 // scan the bytecodes and identify blocks
301 do_analysis();
303 // mark blocks that have exception handlers
304 if (meth->has_exception_handlers()) {
305 for(ciExceptionHandlerStream str(meth); !str.is_done(); str.next()) {
306 ciExceptionHandler* handler = str.handler();
307 int ex_start = handler->start();
308 int ex_end = handler->limit();
310 int bci = ex_start;
311 while (bci < ex_end) {
312 ciBlock *b = block_containing(bci);
313 b->set_has_handler();
314 bci = b->limit_bci();
315 }
316 }
317 }
318 }
320 void ciMethodBlocks::clear_processed() {
321 for (int i = 0; i < _blocks->length(); i++)
322 _blocks->at(i)->clear_processed();
323 }
325 #ifndef PRODUCT
326 void ciMethodBlocks::dump() {
327 tty->print("---- blocks for method: ");
328 _method->print();
329 tty->cr();
330 for (int i = 0; i < _blocks->length(); i++) {
331 tty->print(" B%d: ", i); _blocks->at(i)->dump();
332 }
333 }
334 #endif
337 ciBlock::ciBlock(ciMethod *method, int index, ciMethodBlocks *mb, int start_bci) :
338 #ifndef PRODUCT
339 _method(method),
340 #endif
341 _idx(index), _flags(0), _start_bci(start_bci), _limit_bci(-1), _control_bci(fall_through_bci),
342 _ex_start_bci(-1), _ex_limit_bci(-1) {
343 }
345 void ciBlock::set_exception_range(int start_bci, int limit_bci) {
346 assert(limit_bci >= start_bci, "valid range");
347 assert(!is_handler() && _ex_start_bci == -1 && _ex_limit_bci == -1, "must not be handler");
348 _ex_start_bci = start_bci;
349 _ex_limit_bci = limit_bci;
350 set_handler();
351 }
353 #ifndef PRODUCT
354 static char *flagnames[] = {
355 "Processed",
356 "Handler",
357 "MayThrow",
358 "Jsr",
359 "Ret",
360 "RetTarget",
361 "HasHandler",
362 };
364 void ciBlock::dump() {
365 tty->print(" [%d .. %d), {", _start_bci, _limit_bci);
366 for (int i = 0; i < 8; i++) {
367 if ((_flags & (1 << i)) != 0) {
368 tty->print(" %s", flagnames[i]);
369 }
370 }
371 tty->print(" ]");
372 if (is_handler())
373 tty->print(" handles(%d..%d)", _ex_start_bci, _ex_limit_bci);
374 tty->cr();
375 }
377 // ------------------------------------------------------------------
378 // ciBlock::print_on
379 void ciBlock::print_on(outputStream* st) const {
380 st->print_cr("--------------------------------------------------------");
381 st->print ("ciBlock [%d - %d) control : ", start_bci(), limit_bci());
382 if (control_bci() == fall_through_bci) {
383 st->print_cr("%d:fall through", limit_bci());
384 } else {
385 st->print_cr("%d:%s", control_bci(),
386 Bytecodes::name(method()->java_code_at_bci(control_bci())));
387 }
389 if (Verbose || WizardMode) {
390 method()->print_codes_on(start_bci(), limit_bci(), st);
391 }
392 }
393 #endif