1 /*
2 * Copyright 1999-2008 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
578 cur->set(BlockBegin::linear_scan_loop_header_flag);
579 cur->set(BlockBegin::backward_branch_target_flag);
580
581 parent->set(BlockBegin::linear_scan_loop_end_flag);
582
583 // When a loop header is also the start of an exception handler, then the backward branch is
584 // an exception edge. Because such edges are usually critical edges which cannot be split, the
585 // loop must be excluded here from processing.
586 if (cur->is_set(BlockBegin::exception_entry_flag)) {
587 // Make sure that dominators are correct in this weird situation
588 _iterative_dominators = true;
589 return;
590 }
591 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
592 "loop end blocks must have one successor (critical edges are split)");
593
594 _loop_end_blocks.append(parent);
595 return;
596 }
597
598 // increment number of incoming forward branches
599 inc_forward_branches(cur);
600
601 if (is_visited(cur)) {
602 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
603 return;
604 }
605
606 _num_blocks++;
607 set_visited(cur);
608 set_active(cur);
609
610 // recursive call for all successors
611 int i;
612 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
613 count_edges(cur->sux_at(i), cur);
614 }
615 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
616 count_edges(cur->exception_handler_at(i), cur);
617 }
618
619 clear_active(cur);
620
621 // Each loop has a unique number.
622 // When multiple loops are nested, assign_loop_depth assumes that the
623 // innermost loop has the lowest number. This is guaranteed by setting
624 // the loop number after the recursive calls for the successors above
625 // have returned.
626 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
627 assert(cur->loop_index() == -1, "cannot set loop-index twice");
628 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
629
630 cur->set_loop_index(_num_loops);
631 _num_loops++;
632 }
633
634 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
635 }
636
637
638 void ComputeLinearScanOrder::mark_loops() {
639 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
640
641 _loop_map = BitMap2D(_num_loops, _max_block_id);
642 _loop_map.clear();
643
644 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
645 BlockBegin* loop_end = _loop_end_blocks.at(i);
646 BlockBegin* loop_start = loop_end->sux_at(0);
647 int loop_idx = loop_start->loop_index();
648
649 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));
650 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
651 assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
652 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
653 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
654 assert(_work_list.is_empty(), "work list must be empty before processing");
655
656 // add the end-block of the loop to the working list
657 _work_list.push(loop_end);
658 set_block_in_loop(loop_idx, loop_end);
659 do {
660 BlockBegin* cur = _work_list.pop();
661
662 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id()));
663 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
664
665 // recursive processing of all predecessors ends when start block of loop is reached
666 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
667 for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
668 BlockBegin* pred = cur->pred_at(j);
669
670 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
671 // this predecessor has not been processed yet, so add it to work list
672 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id()));
673 _work_list.push(pred);
674 set_block_in_loop(loop_idx, pred);
675 }
676 }
677 }
678 } while (!_work_list.is_empty());
679 }
680 }
681
682
683 // check for non-natural loops (loops where the loop header does not dominate
684 // all other loop blocks = loops with mulitple entries).
685 // such loops are ignored
686 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
687 for (int i = _num_loops - 1; i >= 0; i--) {
688 if (is_block_in_loop(i, start_block)) {
689 // loop i contains the entry block of the method
690 // -> this is not a natural loop, so ignore it
691 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
692
693 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
694 clear_block_in_loop(i, block_id);
695 }
696 _iterative_dominators = true;
697 }
698 }
699 }
700
701 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
702 TRACE_LINEAR_SCAN(3, "----- computing loop-depth and weight");
703 init_visited();
704
705 assert(_work_list.is_empty(), "work list must be empty before processing");
706 _work_list.append(start_block);
707
708 do {
709 BlockBegin* cur = _work_list.pop();
710
711 if (!is_visited(cur)) {
712 set_visited(cur);
713 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
714
715 // compute loop-depth and loop-index for the block
716 assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
717 int i;
718 int loop_depth = 0;
719 int min_loop_idx = -1;
720 for (i = _num_loops - 1; i >= 0; i--) {
721 if (is_block_in_loop(i, cur)) {
722 loop_depth++;
723 min_loop_idx = i;
724 }
725 }
726 cur->set_loop_depth(loop_depth);
727 cur->set_loop_index(min_loop_idx);
728
729 // append all unvisited successors to work list
730 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
731 _work_list.append(cur->sux_at(i));
732 }
733 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
734 _work_list.append(cur->exception_handler_at(i));
735 }
736 }
737 } while (!_work_list.is_empty());
738 }
739
740
741 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
742 assert(a != NULL && b != NULL, "must have input blocks");
743
744 _dominator_blocks.clear();
745 while (a != NULL) {
746 _dominator_blocks.set_bit(a->block_id());
747 assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
748 a = a->dominator();
749 }
750 while (b != NULL && !_dominator_blocks.at(b->block_id())) {
751 assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
752 b = b->dominator();
753 }
754
755 assert(b != NULL, "could not find dominator");
756 return b;
757 }
758
759 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
760 if (cur->dominator() == NULL) {
761 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
762 cur->set_dominator(parent);
763
764 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
765 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()));
766 assert(cur->number_of_preds() > 1, "");
767 cur->set_dominator(common_dominator(cur->dominator(), parent));
768 }
769 }
770
771
772 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
773 BlockBegin* single_sux = NULL;
774 if (cur->number_of_sux() == 1) {
775 single_sux = cur->sux_at(0);
776 }
777
778 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
779 int weight = (cur->loop_depth() & 0x7FFF) << 16;
780
781 // general macro for short definition of weight flags
782 // the first instance of INC_WEIGHT_IF has the highest priority
783 int cur_bit = 15;
784 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
785
786 // this is necessery for the (very rare) case that two successing blocks have
787 // the same loop depth, but a different loop index (can happen for endless loops
788 // with exception handlers)
789 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
790
791 // loop end blocks (blocks that end with a backward branch) are added
792 // after all other blocks of the loop.
793 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
794
795 // critical edge split blocks are prefered because than they have a bigger
796 // proability to be completely empty
797 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
798
799 // exceptions should not be thrown in normal control flow, so these blocks
800 // are added as late as possible
801 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL));
802 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
803
804 // exceptions handlers are added as late as possible
805 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
806
807 // guarantee that weight is > 0
808 weight |= 1;
809
810 #undef INC_WEIGHT_IF
811 assert(cur_bit >= 0, "too many flags");
812 assert(weight > 0, "weight cannot become negative");
813
814 return weight;
815 }
816
817 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
818 // Discount the edge just traveled.
819 // When the number drops to zero, all forward branches were processed
820 if (dec_forward_branches(cur) != 0) {
821 return false;
822 }
823
824 assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
825 assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
826 return true;
827 }
828
829 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
830 assert(_work_list.index_of(cur) == -1, "block already in work list");
831
832 int cur_weight = compute_weight(cur);
833
834 // the linear_scan_number is used to cache the weight of a block
835 cur->set_linear_scan_number(cur_weight);
836
837 #ifndef PRODUCT
838 if (StressLinearScan) {
839 _work_list.insert_before(0, cur);
840 return;
841 }
842 #endif
843
844 _work_list.append(NULL); // provide space for new element
845
846 int insert_idx = _work_list.length() - 1;
847 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
848 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
849 insert_idx--;
850 }
851 _work_list.at_put(insert_idx, cur);
852
853 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
854 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()));
855
856 #ifdef ASSERT
857 for (int i = 0; i < _work_list.length(); i++) {
858 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
859 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
860 }
861 #endif
862 }
863
864 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
865 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()));
866 assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
867
868 // currently, the linear scan order and code emit order are equal.
869 // therefore the linear_scan_number and the weight of a block must also
870 // be equal.
871 cur->set_linear_scan_number(_linear_scan_order->length());
872 _linear_scan_order->append(cur);
873 }
874
875 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
876 TRACE_LINEAR_SCAN(3, "----- computing final block order");
877
878 // the start block is always the first block in the linear scan order
879 _linear_scan_order = new BlockList(_num_blocks);
880 append_block(start_block);
881
882 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
883 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
884 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
885
886 BlockBegin* sux_of_osr_entry = NULL;
887 if (osr_entry != NULL) {
888 // special handling for osr entry:
889 // ignore the edge between the osr entry and its successor for processing
890 // the osr entry block is added manually below
891 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
892 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");
893
894 sux_of_osr_entry = osr_entry->sux_at(0);
895 dec_forward_branches(sux_of_osr_entry);
896
897 compute_dominator(osr_entry, start_block);
898 _iterative_dominators = true;
899 }
900 compute_dominator(std_entry, start_block);
901
902 // start processing with standard entry block
903 assert(_work_list.is_empty(), "list must be empty before processing");
904
905 if (ready_for_processing(std_entry)) {
906 sort_into_work_list(std_entry);
907 } else {
908 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
909 }
910
911 do {
912 BlockBegin* cur = _work_list.pop();
913
914 if (cur == sux_of_osr_entry) {
915 // the osr entry block is ignored in normal processing, it is never added to the
916 // work list. Instead, it is added as late as possible manually here.
917 append_block(osr_entry);
918 compute_dominator(cur, osr_entry);
919 }
920 append_block(cur);
921
922 int i;
923 int num_sux = cur->number_of_sux();
924 // changed loop order to get "intuitive" order of if- and else-blocks
925 for (i = 0; i < num_sux; i++) {
926 BlockBegin* sux = cur->sux_at(i);
927 compute_dominator(sux, cur);
928 if (ready_for_processing(sux)) {
929 sort_into_work_list(sux);
930 }
931 }
932 num_sux = cur->number_of_exception_handlers();
933 for (i = 0; i < num_sux; i++) {
934 BlockBegin* sux = cur->exception_handler_at(i);
935 compute_dominator(sux, cur);
936 if (ready_for_processing(sux)) {
937 sort_into_work_list(sux);
938 }
939 }
940 } while (_work_list.length() > 0);
941 }
942
943
944 bool ComputeLinearScanOrder::compute_dominators_iter() {
945 bool changed = false;
946 int num_blocks = _linear_scan_order->length();
947
948 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
949 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
950 for (int i = 1; i < num_blocks; i++) {
951 BlockBegin* block = _linear_scan_order->at(i);
952
953 BlockBegin* dominator = block->pred_at(0);
954 int num_preds = block->number_of_preds();
955 for (int i = 1; i < num_preds; i++) {
956 dominator = common_dominator(dominator, block->pred_at(i));
957 }
958
959 if (dominator != block->dominator()) {
960 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()));
961
962 block->set_dominator(dominator);
963 changed = true;
964 }
965 }
966 return changed;
967 }
968
969 void ComputeLinearScanOrder::compute_dominators() {
970 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
971
972 // iterative computation of dominators is only required for methods with non-natural loops
973 // and OSR-methods. For all other methods, the dominators computed when generating the
974 // linear scan block order are correct.
975 if (_iterative_dominators) {
976 do {
977 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
978 } while (compute_dominators_iter());
979 }
980
981 // check that dominators are correct
982 assert(!compute_dominators_iter(), "fix point not reached");
983 }
984
985
986 #ifndef PRODUCT
987 void ComputeLinearScanOrder::print_blocks() {
988 if (TraceLinearScanLevel >= 2) {
989 tty->print_cr("----- loop information:");
990 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
991 BlockBegin* cur = _linear_scan_order->at(block_idx);
992
993 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
994 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
995 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
996 }
997 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
998 }
999 }
1000
1001 if (TraceLinearScanLevel >= 1) {
1002 tty->print_cr("----- linear-scan block order:");
1003 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1004 BlockBegin* cur = _linear_scan_order->at(block_idx);
1005 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
1006
1007 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
1008 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
1009 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
1010 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
1011
1012 if (cur->dominator() != NULL) {
1013 tty->print(" dom: B%d ", cur->dominator()->block_id());
1014 } else {
1015 tty->print(" dom: NULL ");
1016 }
1017
1018 if (cur->number_of_preds() > 0) {
1019 tty->print(" preds: ");
1020 for (int j = 0; j < cur->number_of_preds(); j++) {
1021 BlockBegin* pred = cur->pred_at(j);
1022 tty->print("B%d ", pred->block_id());
1023 }
1024 }
1025 if (cur->number_of_sux() > 0) {
1026 tty->print(" sux: ");
1027 for (int j = 0; j < cur->number_of_sux(); j++) {
1028 BlockBegin* sux = cur->sux_at(j);
1029 tty->print("B%d ", sux->block_id());
1030 }
1031 }
1032 if (cur->number_of_exception_handlers() > 0) {
1033 tty->print(" ex: ");
1034 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1035 BlockBegin* ex = cur->exception_handler_at(j);
1036 tty->print("B%d ", ex->block_id());
1037 }
1038 }
1039 tty->cr();
1040 }
1041 }
1042 }
1043 #endif
1044
1045 #ifdef ASSERT
1046 void ComputeLinearScanOrder::verify() {
1047 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1048
1049 if (StressLinearScan) {
1050 // blocks are scrambled when StressLinearScan is used
1051 return;
1052 }
1053
1054 // check that all successors of a block have a higher linear-scan-number
1055 // and that all predecessors of a block have a lower linear-scan-number
1056 // (only backward branches of loops are ignored)
1057 int i;
1058 for (i = 0; i < _linear_scan_order->length(); i++) {
1059 BlockBegin* cur = _linear_scan_order->at(i);
1060
1061 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1062 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
1063
1064 int j;
1065 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1066 BlockBegin* sux = cur->sux_at(j);
1067
1068 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
1069 if (!cur->is_set(BlockBegin::linear_scan_loop_end_flag)) {
1070 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1071 }
1072 if (cur->loop_depth() == sux->loop_depth()) {
1073 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");
1074 }
1075 }
1076
1077 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1078 BlockBegin* pred = cur->pred_at(j);
1079
1080 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
1081 if (!cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
1082 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1083 }
1084 if (cur->loop_depth() == pred->loop_depth()) {
1085 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");
1086 }
1087
1088 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1089 }
1090
1091 // check dominator
1092 if (i == 0) {
1093 assert(cur->dominator() == NULL, "first block has no dominator");
1094 } else {
1095 assert(cur->dominator() != NULL, "all but first block must have dominator");
1096 }
1097 assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0), "Single predecessor must also be dominator");
1098 }
1099
1100 // check that all loops are continuous
1101 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1102 int block_idx = 0;
1103 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1104
1105 // skip blocks before the loop
1106 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1107 block_idx++;
1108 }
1109 // skip blocks of loop
1110 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1111 block_idx++;
1112 }
1113 // after the first non-loop block, there must not be another loop-block
1114 while (block_idx < _num_blocks) {
1115 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1116 block_idx++;
1117 }
1118 }
1119 }
1120 #endif
1121
1122
1123 void IR::compute_code() {
1124 assert(is_valid(), "IR must be valid");
1125
1126 ComputeLinearScanOrder compute_order(start());
1127 _num_loops = compute_order.num_loops();
1128 _code = compute_order.linear_scan_order();
1129 }
1130
1131
1132 void IR::compute_use_counts() {
1133 // make sure all values coming out of this block get evaluated.
1134 int num_blocks = _code->length();
1135 for (int i = 0; i < num_blocks; i++) {
1136 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1137 }
1138
1139 // compute use counts
1140 UseCountComputer::compute(_code);
1141 }
1142
1143
1144 void IR::iterate_preorder(BlockClosure* closure) {
1145 assert(is_valid(), "IR must be valid");
1146 start()->iterate_preorder(closure);
1147 }
1148
1149
1150 void IR::iterate_postorder(BlockClosure* closure) {
1151 assert(is_valid(), "IR must be valid");
1152 start()->iterate_postorder(closure);
1153 }
1154
1155 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1156 linear_scan_order()->iterate_forward(closure);
1157 }
1158
1159
1160 #ifndef PRODUCT
1161 class BlockPrinter: public BlockClosure {
1162 private:
1163 InstructionPrinter* _ip;
1164 bool _cfg_only;
1165 bool _live_only;
1166
1167 public:
1168 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1169 _ip = ip;
1170 _cfg_only = cfg_only;
1171 _live_only = live_only;
1172 }
1173
1174 virtual void block_do(BlockBegin* block) {
1175 if (_cfg_only) {
1176 _ip->print_instr(block); tty->cr();
1177 } else {
1178 block->print_block(*_ip, _live_only);
1179 }
1180 }
1181 };
1182
1183
1184 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1185 ttyLocker ttyl;
1186 InstructionPrinter ip(!cfg_only);
1187 BlockPrinter bp(&ip, cfg_only, live_only);
1188 start->iterate_preorder(&bp);
1189 tty->cr();
1190 }
1191
1192 void IR::print(bool cfg_only, bool live_only) {
1193 if (is_valid()) {
1194 print(start(), cfg_only, live_only);
1195 } else {
1196 tty->print_cr("invalid IR");
1197 }
1198 }
1199
1200
1201 define_array(BlockListArray, BlockList*)
1202 define_stack(BlockListList, BlockListArray)
1203
1204 class PredecessorValidator : public BlockClosure {
1205 private:
1206 BlockListList* _predecessors;
1207 BlockList* _blocks;
1208
1209 static int cmp(BlockBegin** a, BlockBegin** b) {
1210 return (*a)->block_id() - (*b)->block_id();
1211 }
1212
1213 public:
1214 PredecessorValidator(IR* hir) {
1215 ResourceMark rm;
1216 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
1217 _blocks = new BlockList();
1218
1219 int i;
1220 hir->start()->iterate_preorder(this);
1221 if (hir->code() != NULL) {
1222 assert(hir->code()->length() == _blocks->length(), "must match");
1223 for (i = 0; i < _blocks->length(); i++) {
1224 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1225 }
1226 }
1227
1228 for (i = 0; i < _blocks->length(); i++) {
1229 BlockBegin* block = _blocks->at(i);
1230 BlockList* preds = _predecessors->at(block->block_id());
1231 if (preds == NULL) {
1232 assert(block->number_of_preds() == 0, "should be the same");
1233 continue;
1234 }
1235
1236 // clone the pred list so we can mutate it
1237 BlockList* pred_copy = new BlockList();
1238 int j;
1239 for (j = 0; j < block->number_of_preds(); j++) {
1240 pred_copy->append(block->pred_at(j));
1241 }
1242 // sort them in the same order
1243 preds->sort(cmp);
1244 pred_copy->sort(cmp);
1245 int length = MIN2(preds->length(), block->number_of_preds());
1246 for (j = 0; j < block->number_of_preds(); j++) {
1247 assert(preds->at(j) == pred_copy->at(j), "must match");
1248 }
1249
1250 assert(preds->length() == block->number_of_preds(), "should be the same");
1251 }
1252 }
1253
1254 virtual void block_do(BlockBegin* block) {
1255 _blocks->append(block);
1256 BlockEnd* be = block->end();
1257 int n = be->number_of_sux();
1258 int i;
1259 for (i = 0; i < n; i++) {
1260 BlockBegin* sux = be->sux_at(i);
1261 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1262
1263 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1264 if (preds == NULL) {
1265 preds = new BlockList();
1266 _predecessors->at_put(sux->block_id(), preds);
1267 }
1268 preds->append(block);
1269 }
1270
1271 n = block->number_of_exception_handlers();
1272 for (i = 0; i < n; i++) {
1273 BlockBegin* sux = block->exception_handler_at(i);
1274 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1275
1276 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1277 if (preds == NULL) {
1278 preds = new BlockList();
1279 _predecessors->at_put(sux->block_id(), preds);
1280 }
1281 preds->append(block);
1282 }
1283 }
1284 };
1285
1286 void IR::verify() {
1287 #ifdef ASSERT
1288 PredecessorValidator pv(this);
1289 #endif
1290 }
1291
1292 #endif // PRODUCT
1293
1294 void SubstitutionResolver::substitute(Value* v) {
1295 Value v0 = *v;
1296 if (v0) {
1297 Value vs = v0->subst();
1298 if (vs != v0) {
1299 *v = v0->subst();
1300 }
1301 }
1302 }
1303
1304 #ifdef ASSERT
1305 void check_substitute(Value* v) {
1306 Value v0 = *v;
1307 if (v0) {
1308 Value vs = v0->subst();
1309 assert(vs == v0, "missed substitution");
1310 }
1311 }
1312 #endif
1313
1314
1315 void SubstitutionResolver::block_do(BlockBegin* block) {
1316 Instruction* last = NULL;
1317 for (Instruction* n = block; n != NULL;) {
1318 n->values_do(substitute);
1319 // need to remove this instruction from the instruction stream
1320 if (n->subst() != n) {
1321 assert(last != NULL, "must have last");
1322 last->set_next(n->next(), n->next()->bci());
1323 } else {
1324 last = n;
1325 }
1326 n = last->next();
1327 }
1328
1329 #ifdef ASSERT
1330 if (block->state()) block->state()->values_do(check_substitute);
1331 block->block_values_do(check_substitute);
1332 if (block->end() && block->end()->state()) block->end()->state()->values_do(check_substitute);
1333 #endif
1334 }