1 /*
2 * Copyright 1999-2006 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 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_c1_IR.cpp.incl"
27
28
29 // Implementation of XHandlers
30 //
31 // Note: This code could eventually go away if we are
32 // just using the ciExceptionHandlerStream.
33
34 XHandlers::XHandlers(ciMethod* method) : _list(method->exception_table_length()) {
35 ciExceptionHandlerStream s(method);
36 while (!s.is_done()) {
37 _list.append(new XHandler(s.handler()));
38 s.next();
39 }
40 assert(s.count() == method->exception_table_length(), "exception table lengths inconsistent");
41 }
42
43 // deep copy of all XHandler contained in list
44 XHandlers::XHandlers(XHandlers* other) :
45 _list(other->length())
46 {
47 for (int i = 0; i < other->length(); i++) {
48 _list.append(new XHandler(other->handler_at(i)));
49 }
50 }
51
52 // Returns whether a particular exception type can be caught. Also
53 // returns true if klass is unloaded or any exception handler
54 // classes are unloaded. type_is_exact indicates whether the throw
55 // is known to be exactly that class or it might throw a subtype.
56 bool XHandlers::could_catch(ciInstanceKlass* klass, bool type_is_exact) const {
57 // the type is unknown so be conservative
58 if (!klass->is_loaded()) {
59 return true;
60 }
61
62 for (int i = 0; i < length(); i++) {
63 XHandler* handler = handler_at(i);
64 if (handler->is_catch_all()) {
65 // catch of ANY
66 return true;
67 }
68 ciInstanceKlass* handler_klass = handler->catch_klass();
69 // if it's unknown it might be catchable
70 if (!handler_klass->is_loaded()) {
71 return true;
72 }
73 // if the throw type is definitely a subtype of the catch type
74 // then it can be caught.
75 if (klass->is_subtype_of(handler_klass)) {
76 return true;
77 }
78 if (!type_is_exact) {
79 // If the type isn't exactly known then it can also be caught by
80 // catch statements where the inexact type is a subtype of the
81 // catch type.
82 // given: foo extends bar extends Exception
83 // throw bar can be caught by catch foo, catch bar, and catch
84 // Exception, however it can't be caught by any handlers without
85 // bar in its type hierarchy.
86 if (handler_klass->is_subtype_of(klass)) {
87 return true;
88 }
89 }
90 }
91
92 return false;
93 }
94
95
96 bool XHandlers::equals(XHandlers* others) const {
97 if (others == NULL) return false;
98 if (length() != others->length()) return false;
99
100 for (int i = 0; i < length(); i++) {
101 if (!handler_at(i)->equals(others->handler_at(i))) return false;
102 }
103 return true;
104 }
105
106 bool XHandler::equals(XHandler* other) const {
107 assert(entry_pco() != -1 && other->entry_pco() != -1, "must have entry_pco");
108
109 if (entry_pco() != other->entry_pco()) return false;
110 if (scope_count() != other->scope_count()) return false;
111 if (_desc != other->_desc) return false;
112
113 assert(entry_block() == other->entry_block(), "entry_block must be equal when entry_pco is equal");
114 return true;
115 }
116
117
118 // Implementation of IRScope
119
120 BlockBegin* IRScope::header_block(BlockBegin* entry, BlockBegin::Flag f, ValueStack* state) {
121 if (entry == NULL) return NULL;
122 assert(entry->is_set(f), "entry/flag mismatch");
123 // create header block
124 BlockBegin* h = new BlockBegin(entry->bci());
125 BlockEnd* g = new Goto(entry, false);
126 h->set_next(g, entry->bci());
127 h->set_end(g);
128 h->set(f);
129 // setup header block end state
130 ValueStack* s = state->copy(); // can use copy since stack is empty (=> no phis)
131 assert(s->stack_is_empty(), "must have empty stack at entry point");
132 g->set_state(s);
133 return h;
134 }
135
136
137 BlockBegin* IRScope::build_graph(Compilation* compilation, int osr_bci) {
138 GraphBuilder gm(compilation, this);
139 NOT_PRODUCT(if (PrintValueNumbering && Verbose) gm.print_stats());
140 if (compilation->bailed_out()) return NULL;
141 return gm.start();
142 }
143
144
145 IRScope::IRScope(Compilation* compilation, IRScope* caller, int caller_bci, ciMethod* method, int osr_bci, bool create_graph)
146 : _callees(2)
147 , _compilation(compilation)
148 , _lock_stack_size(-1)
149 , _requires_phi_function(method->max_locals())
150 {
151 _caller = caller;
152 _caller_bci = caller == NULL ? -1 : caller_bci;
153 _caller_state = NULL; // Must be set later if needed
154 _level = caller == NULL ? 0 : caller->level() + 1;
155 _method = method;
156 _xhandlers = new XHandlers(method);
157 _number_of_locks = 0;
158 _monitor_pairing_ok = method->has_balanced_monitors();
159 _start = NULL;
160
161 if (osr_bci == -1) {
162 _requires_phi_function.clear();
163 } else {
164 // selective creation of phi functions is not possibel in osr-methods
165 _requires_phi_function.set_range(0, method->max_locals());
166 }
167
168 assert(method->holder()->is_loaded() , "method holder must be loaded");
169
170 // build graph if monitor pairing is ok
171 if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci);
172 }
173
174
175 int IRScope::max_stack() const {
176 int my_max = method()->max_stack();
177 int callee_max = 0;
178 for (int i = 0; i < number_of_callees(); i++) {
179 callee_max = MAX2(callee_max, callee_no(i)->max_stack());
180 }
181 return my_max + callee_max;
182 }
183
184
185 void IRScope::compute_lock_stack_size() {
186 if (!InlineMethodsWithExceptionHandlers) {
187 _lock_stack_size = 0;
188 return;
189 }
190
191 // Figure out whether we have to preserve expression stack elements
192 // for parent scopes, and if so, how many
193 IRScope* cur_scope = this;
194 while (cur_scope != NULL && !cur_scope->xhandlers()->has_handlers()) {
195 cur_scope = cur_scope->caller();
196 }
197 _lock_stack_size = (cur_scope == NULL ? 0 :
198 (cur_scope->caller_state() == NULL ? 0 :
199 cur_scope->caller_state()->stack_size()));
200 }
201
202 int IRScope::top_scope_bci() const {
203 assert(!is_top_scope(), "no correct answer for top scope possible");
204 const IRScope* scope = this;
205 while (!scope->caller()->is_top_scope()) {
206 scope = scope->caller();
207 }
208 return scope->caller_bci();
209 }
210
211
212
213 // Implementation of CodeEmitInfo
214
215 // Stack must be NON-null
216 CodeEmitInfo::CodeEmitInfo(int bci, ValueStack* stack, XHandlers* exception_handlers)
217 : _scope(stack->scope())
218 , _bci(bci)
219 , _scope_debug_info(NULL)
220 , _oop_map(NULL)
221 , _stack(stack)
222 , _exception_handlers(exception_handlers)
223 , _next(NULL)
224 , _id(-1) {
225 assert(_stack != NULL, "must be non null");
226 assert(_bci == SynchronizationEntryBCI || Bytecodes::is_defined(scope()->method()->java_code_at_bci(_bci)), "make sure bci points at a real bytecode");
227 }
228
229
230 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, bool lock_stack_only)
231 : _scope(info->_scope)
232 , _exception_handlers(NULL)
233 , _bci(info->_bci)
234 , _scope_debug_info(NULL)
235 , _oop_map(NULL) {
236 if (lock_stack_only) {
237 if (info->_stack != NULL) {
238 _stack = info->_stack->copy_locks();
239 } else {
240 _stack = NULL;
241 }
242 } else {
243 _stack = info->_stack;
244 }
245
246 // deep copy of exception handlers
247 if (info->_exception_handlers != NULL) {
248 _exception_handlers = new XHandlers(info->_exception_handlers);
249 }
250 }
251
252
253 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) {
254 // record the safepoint before recording the debug info for enclosing scopes
255 recorder->add_safepoint(pc_offset, _oop_map->deep_copy());
256 _scope_debug_info->record_debug_info(recorder, pc_offset);
257 recorder->end_safepoint(pc_offset);
258 }
259
260
261 void CodeEmitInfo::add_register_oop(LIR_Opr opr) {
262 assert(_oop_map != NULL, "oop map must already exist");
263 assert(opr->is_single_cpu(), "should not call otherwise");
264
265 int frame_size = frame_map()->framesize();
266 int arg_count = frame_map()->oop_map_arg_count();
267 VMReg name = frame_map()->regname(opr);
268 _oop_map->set_oop(name);
269 }
270
271
272
273
274 // Implementation of IR
275
276 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) :
277 _locals_size(in_WordSize(-1))
278 , _num_loops(0) {
279 // initialize data structures
280 ValueType::initialize();
281 Instruction::initialize();
282 BlockBegin::initialize();
283 GraphBuilder::initialize();
284 // setup IR fields
285 _compilation = compilation;
286 _top_scope = new IRScope(compilation, NULL, -1, method, osr_bci, true);
287 _code = NULL;
288 }
289
290
291 void IR::optimize() {
292 Optimizer opt(this);
293 if (DoCEE) {
294 opt.eliminate_conditional_expressions();
295 #ifndef PRODUCT
296 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
297 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
298 #endif
299 }
300 if (EliminateBlocks) {
301 opt.eliminate_blocks();
302 #ifndef PRODUCT
303 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
304 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
305 #endif
306 }
307 if (EliminateNullChecks) {
308 opt.eliminate_null_checks();
309 #ifndef PRODUCT
310 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
311 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
312 #endif
313 }
314 }
315
316
317 static int sort_pairs(BlockPair** a, BlockPair** b) {
318 if ((*a)->from() == (*b)->from()) {
319 return (*a)->to()->block_id() - (*b)->to()->block_id();
320 } else {
321 return (*a)->from()->block_id() - (*b)->from()->block_id();
322 }
323 }
324
325
326 class CriticalEdgeFinder: public BlockClosure {
327 BlockPairList blocks;
328 IR* _ir;
329
330 public:
331 CriticalEdgeFinder(IR* ir): _ir(ir) {}
332 void block_do(BlockBegin* bb) {
333 BlockEnd* be = bb->end();
334 int nos = be->number_of_sux();
335 if (nos >= 2) {
336 for (int i = 0; i < nos; i++) {
337 BlockBegin* sux = be->sux_at(i);
338 if (sux->number_of_preds() >= 2) {
339 blocks.append(new BlockPair(bb, sux));
340 }
341 }
342 }
343 }
344
345 void split_edges() {
346 BlockPair* last_pair = NULL;
347 blocks.sort(sort_pairs);
348 for (int i = 0; i < blocks.length(); i++) {
349 BlockPair* pair = blocks.at(i);
350 if (last_pair != NULL && pair->is_same(last_pair)) continue;
351 BlockBegin* from = pair->from();
352 BlockBegin* to = pair->to();
353 BlockBegin* split = from->insert_block_between(to);
354 #ifndef PRODUCT
355 if ((PrintIR || PrintIR1) && Verbose) {
356 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
357 from->block_id(), to->block_id(), split->block_id());
358 }
359 #endif
360 last_pair = pair;
361 }
362 }
363 };
364
365 void IR::split_critical_edges() {
366 CriticalEdgeFinder cef(this);
367
368 iterate_preorder(&cef);
369 cef.split_edges();
370 }
371
372
373 class UseCountComputer: public AllStatic {
374 private:
375 static void update_use_count(Value* n) {
376 // Local instructions and Phis for expression stack values at the
377 // start of basic blocks are not added to the instruction list
378 if ((*n)->bci() == -99 && (*n)->as_Local() == NULL &&
379 (*n)->as_Phi() == NULL) {
380 assert(false, "a node was not appended to the graph");
381 Compilation::current_compilation()->bailout("a node was not appended to the graph");
382 }
383 // use n's input if not visited before
384 if (!(*n)->is_pinned() && !(*n)->has_uses()) {
385 // note: a) if the instruction is pinned, it will be handled by compute_use_count
386 // b) if the instruction has uses, it was touched before
387 // => in both cases we don't need to update n's values
388 uses_do(n);
389 }
390 // use n
391 (*n)->_use_count++;
392 }
393
394 static Values* worklist;
395 static int depth;
396 enum {
397 max_recurse_depth = 20
398 };
399
400 static void uses_do(Value* n) {
401 depth++;
402 if (depth > max_recurse_depth) {
403 // don't allow the traversal to recurse too deeply
404 worklist->push(*n);
405 } else {
406 (*n)->input_values_do(update_use_count);
407 // special handling for some instructions
408 if ((*n)->as_BlockEnd() != NULL) {
409 // note on BlockEnd:
410 // must 'use' the stack only if the method doesn't
411 // terminate, however, in those cases stack is empty
412 (*n)->state_values_do(update_use_count);
413 }
414 }
415 depth--;
416 }
417
418 static void basic_compute_use_count(BlockBegin* b) {
419 depth = 0;
420 // process all pinned nodes as the roots of expression trees
421 for (Instruction* n = b; n != NULL; n = n->next()) {
422 if (n->is_pinned()) uses_do(&n);
423 }
424 assert(depth == 0, "should have counted back down");
425
426 // now process any unpinned nodes which recursed too deeply
427 while (worklist->length() > 0) {
428 Value t = worklist->pop();
429 if (!t->is_pinned()) {
430 // compute the use count
431 uses_do(&t);
432
433 // pin the instruction so that LIRGenerator doesn't recurse
434 // too deeply during it's evaluation.
435 t->pin();
436 }
437 }
438 assert(depth == 0, "should have counted back down");
439 }
440
441 public:
442 static void compute(BlockList* blocks) {
443 worklist = new Values();
444 blocks->blocks_do(basic_compute_use_count);
445 worklist = NULL;
446 }
447 };
448
449
450 Values* UseCountComputer::worklist = NULL;
451 int UseCountComputer::depth = 0;
452
453 // helper macro for short definition of trace-output inside code
454 #ifndef PRODUCT
455 #define TRACE_LINEAR_SCAN(level, code) \
456 if (TraceLinearScanLevel >= level) { \
457 code; \
458 }
459 #else
460 #define TRACE_LINEAR_SCAN(level, code)
461 #endif
462
463 class ComputeLinearScanOrder : public StackObj {
464 private:
465 int _max_block_id; // the highest block_id of a block
466 int _num_blocks; // total number of blocks (smaller than _max_block_id)
467 int _num_loops; // total number of loops
468 bool _iterative_dominators;// method requires iterative computation of dominatiors
469
470 BlockList* _linear_scan_order; // the resulting list of blocks in correct order
471
472 BitMap _visited_blocks; // used for recursive processing of blocks
473 BitMap _active_blocks; // used for recursive processing of blocks
474 BitMap _dominator_blocks; // temproary BitMap used for computation of dominator
475 intArray _forward_branches; // number of incoming forward branches for each block
476 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges
477 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop
478 BlockList _work_list; // temporary list (used in mark_loops and compute_order)
479
480 // accessors for _visited_blocks and _active_blocks
481 void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); }
482 bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); }
483 bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); }
484 void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); }
485 void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); }
486 void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); }
487
488 // accessors for _forward_branches
489 void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); }
490 int dec_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) - 1); return _forward_branches.at(b->block_id()); }
491
492 // accessors for _loop_map
493 bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); }
494 void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); }
495 void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); }
496
497 // count edges between blocks
498 void count_edges(BlockBegin* cur, BlockBegin* parent);
499
500 // loop detection
501 void mark_loops();
502 void clear_non_natural_loops(BlockBegin* start_block);
503 void assign_loop_depth(BlockBegin* start_block);
504
505 // computation of final block order
506 BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b);
507 void compute_dominator(BlockBegin* cur, BlockBegin* parent);
508 int compute_weight(BlockBegin* cur);
509 bool ready_for_processing(BlockBegin* cur);
510 void sort_into_work_list(BlockBegin* b);
511 void append_block(BlockBegin* cur);
512 void compute_order(BlockBegin* start_block);
513
514 // fixup of dominators for non-natural loops
515 bool compute_dominators_iter();
516 void compute_dominators();
517
518 // debug functions
519 NOT_PRODUCT(void print_blocks();)
520 DEBUG_ONLY(void verify();)
521
522 public:
523 ComputeLinearScanOrder(BlockBegin* start_block);
524
525 // accessors for final result
526 BlockList* linear_scan_order() const { return _linear_scan_order; }
527 int num_loops() const { return _num_loops; }
528 };
529
530
531 ComputeLinearScanOrder::ComputeLinearScanOrder(BlockBegin* start_block) :
532 _max_block_id(BlockBegin::number_of_blocks()),
533 _num_blocks(0),
534 _num_loops(0),
535 _iterative_dominators(false),
536 _visited_blocks(_max_block_id),
537 _active_blocks(_max_block_id),
538 _dominator_blocks(_max_block_id),
539 _forward_branches(_max_block_id, 0),
540 _loop_end_blocks(8),
541 _work_list(8),
542 _linear_scan_order(NULL), // initialized later with correct size
543 _loop_map(0, 0) // initialized later with correct size
544 {
545 TRACE_LINEAR_SCAN(2, "***** computing linear-scan block order");
546
547 init_visited();
548 count_edges(start_block, NULL);
549
550 if (_num_loops > 0) {
551 mark_loops();
552 clear_non_natural_loops(start_block);
553 assign_loop_depth(start_block);
554 }
555
556 compute_order(start_block);
557 compute_dominators();
558
559 NOT_PRODUCT(print_blocks());
560 DEBUG_ONLY(verify());
561 }
562
563
564 // Traverse the CFG:
565 // * count total number of blocks
566 // * count all incoming edges and backward incoming edges
567 // * number loop header blocks
568 // * create a list with all loop end blocks
569 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
570 TRACE_LINEAR_SCAN(3, tty->print_cr("Enter count_edges for block B%d coming from B%d", cur->block_id(), parent != NULL ? parent->block_id() : -1));
571 assert(cur->dominator() == NULL, "dominator already initialized");
572
573 if (is_active(cur)) {
574 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
575 assert(is_visited(cur), "block must be visisted when block is active");
576 assert(parent != NULL, "must have parent");
577 assert(parent->number_of_sux() == 1, "loop end blocks must have one successor (critical edges are split)");
578
579 cur->set(BlockBegin::linear_scan_loop_header_flag);
580 cur->set(BlockBegin::backward_branch_target_flag);
581
582 parent->set(BlockBegin::linear_scan_loop_end_flag);
583 _loop_end_blocks.append(parent);
584 return;
585 }
586
587 // increment number of incoming forward branches
588 inc_forward_branches(cur);
589
590 if (is_visited(cur)) {
591 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
592 return;
593 }
594
595 _num_blocks++;
596 set_visited(cur);
597 set_active(cur);
598
599 // recursive call for all successors
600 int i;
601 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
602 count_edges(cur->sux_at(i), cur);
603 }
604 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
605 count_edges(cur->exception_handler_at(i), cur);
606 }
607
608 clear_active(cur);
609
610 // Each loop has a unique number.
611 // When multiple loops are nested, assign_loop_depth assumes that the
612 // innermost loop has the lowest number. This is guaranteed by setting
613 // the loop number after the recursive calls for the successors above
614 // have returned.
615 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
616 assert(cur->loop_index() == -1, "cannot set loop-index twice");
617 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
618
619 cur->set_loop_index(_num_loops);
620 _num_loops++;
621 }
622
623 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
624 }
625
626
627 void ComputeLinearScanOrder::mark_loops() {
628 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
629
630 _loop_map = BitMap2D(_num_loops, _max_block_id);
631 _loop_map.clear();
632
633 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
634 BlockBegin* loop_end = _loop_end_blocks.at(i);
635 BlockBegin* loop_start = loop_end->sux_at(0);
636 int loop_idx = loop_start->loop_index();
637
638 TRACE_LINEAR_SCAN(3, tty->print_cr("Processing loop from B%d to B%d (loop %d):", loop_start->block_id(), loop_end->block_id(), loop_idx));
639 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
640 assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
641 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
642 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
643 assert(_work_list.is_empty(), "work list must be empty before processing");
644
645 // add the end-block of the loop to the working list
646 _work_list.push(loop_end);
647 set_block_in_loop(loop_idx, loop_end);
648 do {
649 BlockBegin* cur = _work_list.pop();
650
651 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id()));
652 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
653
654 // recursive processing of all predecessors ends when start block of loop is reached
655 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
656 for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
657 BlockBegin* pred = cur->pred_at(j);
658
659 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
660 // this predecessor has not been processed yet, so add it to work list
661 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id()));
662 _work_list.push(pred);
663 set_block_in_loop(loop_idx, pred);
664 }
665 }
666 }
667 } while (!_work_list.is_empty());
668 }
669 }
670
671
672 // check for non-natural loops (loops where the loop header does not dominate
673 // all other loop blocks = loops with mulitple entries).
674 // such loops are ignored
675 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
676 for (int i = _num_loops - 1; i >= 0; i--) {
677 if (is_block_in_loop(i, start_block)) {
678 // loop i contains the entry block of the method
679 // -> this is not a natural loop, so ignore it
680 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
681
682 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
683 clear_block_in_loop(i, block_id);
684 }
685 _iterative_dominators = true;
686 }
687 }
688 }
689
690 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
691 TRACE_LINEAR_SCAN(3, "----- computing loop-depth and weight");
692 init_visited();
693
694 assert(_work_list.is_empty(), "work list must be empty before processing");
695 _work_list.append(start_block);
696
697 do {
698 BlockBegin* cur = _work_list.pop();
699
700 if (!is_visited(cur)) {
701 set_visited(cur);
702 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
703
704 // compute loop-depth and loop-index for the block
705 assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
706 int i;
707 int loop_depth = 0;
708 int min_loop_idx = -1;
709 for (i = _num_loops - 1; i >= 0; i--) {
710 if (is_block_in_loop(i, cur)) {
711 loop_depth++;
712 min_loop_idx = i;
713 }
714 }
715 cur->set_loop_depth(loop_depth);
716 cur->set_loop_index(min_loop_idx);
717
718 // append all unvisited successors to work list
719 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
720 _work_list.append(cur->sux_at(i));
721 }
722 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
723 _work_list.append(cur->exception_handler_at(i));
724 }
725 }
726 } while (!_work_list.is_empty());
727 }
728
729
730 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
731 assert(a != NULL && b != NULL, "must have input blocks");
732
733 _dominator_blocks.clear();
734 while (a != NULL) {
735 _dominator_blocks.set_bit(a->block_id());
736 assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
737 a = a->dominator();
738 }
739 while (b != NULL && !_dominator_blocks.at(b->block_id())) {
740 assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
741 b = b->dominator();
742 }
743
744 assert(b != NULL, "could not find dominator");
745 return b;
746 }
747
748 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
749 if (cur->dominator() == NULL) {
750 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
751 cur->set_dominator(parent);
752
753 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
754 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: computing dominator of B%d: common dominator of B%d and B%d is B%d", cur->block_id(), parent->block_id(), cur->dominator()->block_id(), common_dominator(cur->dominator(), parent)->block_id()));
755 assert(cur->number_of_preds() > 1, "");
756 cur->set_dominator(common_dominator(cur->dominator(), parent));
757 }
758 }
759
760
761 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
762 BlockBegin* single_sux = NULL;
763 if (cur->number_of_sux() == 1) {
764 single_sux = cur->sux_at(0);
765 }
766
767 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
768 int weight = (cur->loop_depth() & 0x7FFF) << 16;
769
770 // general macro for short definition of weight flags
771 // the first instance of INC_WEIGHT_IF has the highest priority
772 int cur_bit = 15;
773 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
774
775 // this is necessery for the (very rare) case that two successing blocks have
776 // the same loop depth, but a different loop index (can happen for endless loops
777 // with exception handlers)
778 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
779
780 // loop end blocks (blocks that end with a backward branch) are added
781 // after all other blocks of the loop.
782 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
783
784 // critical edge split blocks are prefered because than they have a bigger
785 // proability to be completely empty
786 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
787
788 // exceptions should not be thrown in normal control flow, so these blocks
789 // are added as late as possible
790 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL));
791 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
792
793 // exceptions handlers are added as late as possible
794 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
795
796 // guarantee that weight is > 0
797 weight |= 1;
798
799 #undef INC_WEIGHT_IF
800 assert(cur_bit >= 0, "too many flags");
801 assert(weight > 0, "weight cannot become negative");
802
803 return weight;
804 }
805
806 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
807 // Discount the edge just traveled.
808 // When the number drops to zero, all forward branches were processed
809 if (dec_forward_branches(cur) != 0) {
810 return false;
811 }
812
813 assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
814 assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
815 return true;
816 }
817
818 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
819 assert(_work_list.index_of(cur) == -1, "block already in work list");
820
821 int cur_weight = compute_weight(cur);
822
823 // the linear_scan_number is used to cache the weight of a block
824 cur->set_linear_scan_number(cur_weight);
825
826 #ifndef PRODUCT
827 if (StressLinearScan) {
828 _work_list.insert_before(0, cur);
829 return;
830 }
831 #endif
832
833 _work_list.append(NULL); // provide space for new element
834
835 int insert_idx = _work_list.length() - 1;
836 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
837 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
838 insert_idx--;
839 }
840 _work_list.at_put(insert_idx, cur);
841
842 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
843 TRACE_LINEAR_SCAN(3, for (int i = 0; i < _work_list.length(); i++) tty->print_cr("%8d B%2d weight:%6x", i, _work_list.at(i)->block_id(), _work_list.at(i)->linear_scan_number()));
844
845 #ifdef ASSERT
846 for (int i = 0; i < _work_list.length(); i++) {
847 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
848 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
849 }
850 #endif
851 }
852
853 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
854 TRACE_LINEAR_SCAN(3, tty->print_cr("appending block B%d (weight 0x%6x) to linear-scan order", cur->block_id(), cur->linear_scan_number()));
855 assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
856
857 // currently, the linear scan order and code emit order are equal.
858 // therefore the linear_scan_number and the weight of a block must also
859 // be equal.
860 cur->set_linear_scan_number(_linear_scan_order->length());
861 _linear_scan_order->append(cur);
862 }
863
864 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
865 TRACE_LINEAR_SCAN(3, "----- computing final block order");
866
867 // the start block is always the first block in the linear scan order
868 _linear_scan_order = new BlockList(_num_blocks);
869 append_block(start_block);
870
871 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
872 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
873 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
874
875 BlockBegin* sux_of_osr_entry = NULL;
876 if (osr_entry != NULL) {
877 // special handling for osr entry:
878 // ignore the edge between the osr entry and its successor for processing
879 // the osr entry block is added manually below
880 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
881 assert(osr_entry->sux_at(0)->number_of_preds() >= 2, "sucessor of osr entry must have two predecessors (otherwise it is not present in normal control flow");
882
883 sux_of_osr_entry = osr_entry->sux_at(0);
884 dec_forward_branches(sux_of_osr_entry);
885
886 compute_dominator(osr_entry, start_block);
887 _iterative_dominators = true;
888 }
889 compute_dominator(std_entry, start_block);
890
891 // start processing with standard entry block
892 assert(_work_list.is_empty(), "list must be empty before processing");
893
894 if (ready_for_processing(std_entry)) {
895 sort_into_work_list(std_entry);
896 } else {
897 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
898 }
899
900 do {
901 BlockBegin* cur = _work_list.pop();
902
903 if (cur == sux_of_osr_entry) {
904 // the osr entry block is ignored in normal processing, it is never added to the
905 // work list. Instead, it is added as late as possible manually here.
906 append_block(osr_entry);
907 compute_dominator(cur, osr_entry);
908 }
909 append_block(cur);
910
911 int i;
912 int num_sux = cur->number_of_sux();
913 // changed loop order to get "intuitive" order of if- and else-blocks
914 for (i = 0; i < num_sux; i++) {
915 BlockBegin* sux = cur->sux_at(i);
916 compute_dominator(sux, cur);
917 if (ready_for_processing(sux)) {
918 sort_into_work_list(sux);
919 }
920 }
921 num_sux = cur->number_of_exception_handlers();
922 for (i = 0; i < num_sux; i++) {
923 BlockBegin* sux = cur->exception_handler_at(i);
924 compute_dominator(sux, cur);
925 if (ready_for_processing(sux)) {
926 sort_into_work_list(sux);
927 }
928 }
929 } while (_work_list.length() > 0);
930 }
931
932
933 bool ComputeLinearScanOrder::compute_dominators_iter() {
934 bool changed = false;
935 int num_blocks = _linear_scan_order->length();
936
937 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
938 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
939 for (int i = 1; i < num_blocks; i++) {
940 BlockBegin* block = _linear_scan_order->at(i);
941
942 BlockBegin* dominator = block->pred_at(0);
943 int num_preds = block->number_of_preds();
944 for (int i = 1; i < num_preds; i++) {
945 dominator = common_dominator(dominator, block->pred_at(i));
946 }
947
948 if (dominator != block->dominator()) {
949 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: updating dominator of B%d from B%d to B%d", block->block_id(), block->dominator()->block_id(), dominator->block_id()));
950
951 block->set_dominator(dominator);
952 changed = true;
953 }
954 }
955 return changed;
956 }
957
958 void ComputeLinearScanOrder::compute_dominators() {
959 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
960
961 // iterative computation of dominators is only required for methods with non-natural loops
962 // and OSR-methods. For all other methods, the dominators computed when generating the
963 // linear scan block order are correct.
964 if (_iterative_dominators) {
965 do {
966 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
967 } while (compute_dominators_iter());
968 }
969
970 // check that dominators are correct
971 assert(!compute_dominators_iter(), "fix point not reached");
972 }
973
974
975 #ifndef PRODUCT
976 void ComputeLinearScanOrder::print_blocks() {
977 if (TraceLinearScanLevel >= 2) {
978 tty->print_cr("----- loop information:");
979 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
980 BlockBegin* cur = _linear_scan_order->at(block_idx);
981
982 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
983 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
984 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
985 }
986 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
987 }
988 }
989
990 if (TraceLinearScanLevel >= 1) {
991 tty->print_cr("----- linear-scan block order:");
992 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
993 BlockBegin* cur = _linear_scan_order->at(block_idx);
994 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
995
996 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
997 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
998 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
999 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
1000
1001 if (cur->dominator() != NULL) {
1002 tty->print(" dom: B%d ", cur->dominator()->block_id());
1003 } else {
1004 tty->print(" dom: NULL ");
1005 }
1006
1007 if (cur->number_of_preds() > 0) {
1008 tty->print(" preds: ");
1009 for (int j = 0; j < cur->number_of_preds(); j++) {
1010 BlockBegin* pred = cur->pred_at(j);
1011 tty->print("B%d ", pred->block_id());
1012 }
1013 }
1014 if (cur->number_of_sux() > 0) {
1015 tty->print(" sux: ");
1016 for (int j = 0; j < cur->number_of_sux(); j++) {
1017 BlockBegin* sux = cur->sux_at(j);
1018 tty->print("B%d ", sux->block_id());
1019 }
1020 }
1021 if (cur->number_of_exception_handlers() > 0) {
1022 tty->print(" ex: ");
1023 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1024 BlockBegin* ex = cur->exception_handler_at(j);
1025 tty->print("B%d ", ex->block_id());
1026 }
1027 }
1028 tty->cr();
1029 }
1030 }
1031 }
1032 #endif
1033
1034 #ifdef ASSERT
1035 void ComputeLinearScanOrder::verify() {
1036 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1037
1038 if (StressLinearScan) {
1039 // blocks are scrambled when StressLinearScan is used
1040 return;
1041 }
1042
1043 // check that all successors of a block have a higher linear-scan-number
1044 // and that all predecessors of a block have a lower linear-scan-number
1045 // (only backward branches of loops are ignored)
1046 int i;
1047 for (i = 0; i < _linear_scan_order->length(); i++) {
1048 BlockBegin* cur = _linear_scan_order->at(i);
1049
1050 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1051 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
1052
1053 int j;
1054 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1055 BlockBegin* sux = cur->sux_at(j);
1056
1057 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
1058 if (!cur->is_set(BlockBegin::linear_scan_loop_end_flag)) {
1059 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1060 }
1061 if (cur->loop_depth() == sux->loop_depth()) {
1062 assert(cur->loop_index() == sux->loop_index() || sux->is_set(BlockBegin::linear_scan_loop_header_flag), "successing blocks with same loop depth must have same loop index");
1063 }
1064 }
1065
1066 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1067 BlockBegin* pred = cur->pred_at(j);
1068
1069 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
1070 if (!cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
1071 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1072 }
1073 if (cur->loop_depth() == pred->loop_depth()) {
1074 assert(cur->loop_index() == pred->loop_index() || cur->is_set(BlockBegin::linear_scan_loop_header_flag), "successing blocks with same loop depth must have same loop index");
1075 }
1076
1077 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1078 }
1079
1080 // check dominator
1081 if (i == 0) {
1082 assert(cur->dominator() == NULL, "first block has no dominator");
1083 } else {
1084 assert(cur->dominator() != NULL, "all but first block must have dominator");
1085 }
1086 assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0), "Single predecessor must also be dominator");
1087 }
1088
1089 // check that all loops are continuous
1090 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1091 int block_idx = 0;
1092 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1093
1094 // skip blocks before the loop
1095 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1096 block_idx++;
1097 }
1098 // skip blocks of loop
1099 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1100 block_idx++;
1101 }
1102 // after the first non-loop block, there must not be another loop-block
1103 while (block_idx < _num_blocks) {
1104 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1105 block_idx++;
1106 }
1107 }
1108 }
1109 #endif
1110
1111
1112 void IR::compute_code() {
1113 assert(is_valid(), "IR must be valid");
1114
1115 ComputeLinearScanOrder compute_order(start());
1116 _num_loops = compute_order.num_loops();
1117 _code = compute_order.linear_scan_order();
1118 }
1119
1120
1121 void IR::compute_use_counts() {
1122 // make sure all values coming out of this block get evaluated.
1123 int num_blocks = _code->length();
1124 for (int i = 0; i < num_blocks; i++) {
1125 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1126 }
1127
1128 // compute use counts
1129 UseCountComputer::compute(_code);
1130 }
1131
1132
1133 void IR::iterate_preorder(BlockClosure* closure) {
1134 assert(is_valid(), "IR must be valid");
1135 start()->iterate_preorder(closure);
1136 }
1137
1138
1139 void IR::iterate_postorder(BlockClosure* closure) {
1140 assert(is_valid(), "IR must be valid");
1141 start()->iterate_postorder(closure);
1142 }
1143
1144 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1145 linear_scan_order()->iterate_forward(closure);
1146 }
1147
1148
1149 #ifndef PRODUCT
1150 class BlockPrinter: public BlockClosure {
1151 private:
1152 InstructionPrinter* _ip;
1153 bool _cfg_only;
1154 bool _live_only;
1155
1156 public:
1157 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1158 _ip = ip;
1159 _cfg_only = cfg_only;
1160 _live_only = live_only;
1161 }
1162
1163 virtual void block_do(BlockBegin* block) {
1164 if (_cfg_only) {
1165 _ip->print_instr(block); tty->cr();
1166 } else {
1167 block->print_block(*_ip, _live_only);
1168 }
1169 }
1170 };
1171
1172
1173 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1174 ttyLocker ttyl;
1175 InstructionPrinter ip(!cfg_only);
1176 BlockPrinter bp(&ip, cfg_only, live_only);
1177 start->iterate_preorder(&bp);
1178 tty->cr();
1179 }
1180
1181 void IR::print(bool cfg_only, bool live_only) {
1182 if (is_valid()) {
1183 print(start(), cfg_only, live_only);
1184 } else {
1185 tty->print_cr("invalid IR");
1186 }
1187 }
1188
1189
1190 define_array(BlockListArray, BlockList*)
1191 define_stack(BlockListList, BlockListArray)
1192
1193 class PredecessorValidator : public BlockClosure {
1194 private:
1195 BlockListList* _predecessors;
1196 BlockList* _blocks;
1197
1198 static int cmp(BlockBegin** a, BlockBegin** b) {
1199 return (*a)->block_id() - (*b)->block_id();
1200 }
1201
1202 public:
1203 PredecessorValidator(IR* hir) {
1204 ResourceMark rm;
1205 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
1206 _blocks = new BlockList();
1207
1208 int i;
1209 hir->start()->iterate_preorder(this);
1210 if (hir->code() != NULL) {
1211 assert(hir->code()->length() == _blocks->length(), "must match");
1212 for (i = 0; i < _blocks->length(); i++) {
1213 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1214 }
1215 }
1216
1217 for (i = 0; i < _blocks->length(); i++) {
1218 BlockBegin* block = _blocks->at(i);
1219 BlockList* preds = _predecessors->at(block->block_id());
1220 if (preds == NULL) {
1221 assert(block->number_of_preds() == 0, "should be the same");
1222 continue;
1223 }
1224
1225 // clone the pred list so we can mutate it
1226 BlockList* pred_copy = new BlockList();
1227 int j;
1228 for (j = 0; j < block->number_of_preds(); j++) {
1229 pred_copy->append(block->pred_at(j));
1230 }
1231 // sort them in the same order
1232 preds->sort(cmp);
1233 pred_copy->sort(cmp);
1234 int length = MIN2(preds->length(), block->number_of_preds());
1235 for (j = 0; j < block->number_of_preds(); j++) {
1236 assert(preds->at(j) == pred_copy->at(j), "must match");
1237 }
1238
1239 assert(preds->length() == block->number_of_preds(), "should be the same");
1240 }
1241 }
1242
1243 virtual void block_do(BlockBegin* block) {
1244 _blocks->append(block);
1245 BlockEnd* be = block->end();
1246 int n = be->number_of_sux();
1247 int i;
1248 for (i = 0; i < n; i++) {
1249 BlockBegin* sux = be->sux_at(i);
1250 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1251
1252 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1253 if (preds == NULL) {
1254 preds = new BlockList();
1255 _predecessors->at_put(sux->block_id(), preds);
1256 }
1257 preds->append(block);
1258 }
1259
1260 n = block->number_of_exception_handlers();
1261 for (i = 0; i < n; i++) {
1262 BlockBegin* sux = block->exception_handler_at(i);
1263 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1264
1265 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1266 if (preds == NULL) {
1267 preds = new BlockList();
1268 _predecessors->at_put(sux->block_id(), preds);
1269 }
1270 preds->append(block);
1271 }
1272 }
1273 };
1274
1275 void IR::verify() {
1276 #ifdef ASSERT
1277 PredecessorValidator pv(this);
1278 #endif
1279 }
1280
1281 #endif // PRODUCT
1282
1283 void SubstitutionResolver::substitute(Value* v) {
1284 Value v0 = *v;
1285 if (v0) {
1286 Value vs = v0->subst();
1287 if (vs != v0) {
1288 *v = v0->subst();
1289 }
1290 }
1291 }
1292
1293 #ifdef ASSERT
1294 void check_substitute(Value* v) {
1295 Value v0 = *v;
1296 if (v0) {
1297 Value vs = v0->subst();
1298 assert(vs == v0, "missed substitution");
1299 }
1300 }
1301 #endif
1302
1303
1304 void SubstitutionResolver::block_do(BlockBegin* block) {
1305 Instruction* last = NULL;
1306 for (Instruction* n = block; n != NULL;) {
1307 n->values_do(substitute);
1308 // need to remove this instruction from the instruction stream
1309 if (n->subst() != n) {
1310 assert(last != NULL, "must have last");
1311 last->set_next(n->next(), n->next()->bci());
1312 } else {
1313 last = n;
1314 }
1315 n = last->next();
1316 }
1317
1318 #ifdef ASSERT
1319 if (block->state()) block->state()->values_do(check_substitute);
1320 block->block_values_do(check_substitute);
1321 if (block->end() && block->end()->state()) block->end()->state()->values_do(check_substitute);
1322 #endif
1323 }