1 /*
2 * Copyright (c) 1999, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * 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 bool IRScopeDebugInfo::should_reexecute() {
212 ciMethod* cur_method = scope()->method();
213 int cur_bci = bci();
214 if (cur_method != NULL && cur_bci != SynchronizationEntryBCI) {
215 Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci);
216 return Interpreter::bytecode_should_reexecute(code);
217 } else
218 return false;
219 }
220
221
222 // Implementation of CodeEmitInfo
223
224 // Stack must be NON-null
225 CodeEmitInfo::CodeEmitInfo(int bci, ValueStack* stack, XHandlers* exception_handlers)
226 : _scope(stack->scope())
227 , _bci(bci)
228 , _scope_debug_info(NULL)
229 , _oop_map(NULL)
230 , _stack(stack)
231 , _exception_handlers(exception_handlers)
232 , _next(NULL)
233 , _id(-1)
234 , _is_method_handle_invoke(false) {
235 assert(_stack != NULL, "must be non null");
236 assert(_bci == SynchronizationEntryBCI || Bytecodes::is_defined(scope()->method()->java_code_at_bci(_bci)), "make sure bci points at a real bytecode");
237 }
238
239
240 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, bool lock_stack_only)
241 : _scope(info->_scope)
242 , _exception_handlers(NULL)
243 , _bci(info->_bci)
244 , _scope_debug_info(NULL)
245 , _oop_map(NULL)
246 , _is_method_handle_invoke(info->_is_method_handle_invoke) {
247 if (lock_stack_only) {
248 if (info->_stack != NULL) {
249 _stack = info->_stack->copy_locks();
250 } else {
251 _stack = NULL;
252 }
253 } else {
254 _stack = info->_stack;
255 }
256
257 // deep copy of exception handlers
258 if (info->_exception_handlers != NULL) {
259 _exception_handlers = new XHandlers(info->_exception_handlers);
260 }
261 }
262
263
264 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) {
265 // record the safepoint before recording the debug info for enclosing scopes
266 recorder->add_safepoint(pc_offset, _oop_map->deep_copy());
267 _scope_debug_info->record_debug_info(recorder, pc_offset, true/*topmost*/, _is_method_handle_invoke);
268 recorder->end_safepoint(pc_offset);
269 }
270
271
272 void CodeEmitInfo::add_register_oop(LIR_Opr opr) {
273 assert(_oop_map != NULL, "oop map must already exist");
274 assert(opr->is_single_cpu(), "should not call otherwise");
275
276 int frame_size = frame_map()->framesize();
277 int arg_count = frame_map()->oop_map_arg_count();
278 VMReg name = frame_map()->regname(opr);
279 _oop_map->set_oop(name);
280 }
281
282
283
284
285 // Implementation of IR
286
287 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) :
288 _locals_size(in_WordSize(-1))
289 , _num_loops(0) {
290 // setup IR fields
291 _compilation = compilation;
292 _top_scope = new IRScope(compilation, NULL, -1, method, osr_bci, true);
293 _code = NULL;
294 }
295
296
297 void IR::optimize() {
298 Optimizer opt(this);
299 if (DoCEE) {
300 opt.eliminate_conditional_expressions();
301 #ifndef PRODUCT
302 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
303 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
304 #endif
305 }
306 if (EliminateBlocks) {
307 opt.eliminate_blocks();
308 #ifndef PRODUCT
309 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
310 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
311 #endif
312 }
313 if (EliminateNullChecks) {
314 opt.eliminate_null_checks();
315 #ifndef PRODUCT
316 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
317 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
318 #endif
319 }
320 }
321
322
323 static int sort_pairs(BlockPair** a, BlockPair** b) {
324 if ((*a)->from() == (*b)->from()) {
325 return (*a)->to()->block_id() - (*b)->to()->block_id();
326 } else {
327 return (*a)->from()->block_id() - (*b)->from()->block_id();
328 }
329 }
330
331
332 class CriticalEdgeFinder: public BlockClosure {
333 BlockPairList blocks;
334 IR* _ir;
335
336 public:
337 CriticalEdgeFinder(IR* ir): _ir(ir) {}
338 void block_do(BlockBegin* bb) {
339 BlockEnd* be = bb->end();
340 int nos = be->number_of_sux();
341 if (nos >= 2) {
342 for (int i = 0; i < nos; i++) {
343 BlockBegin* sux = be->sux_at(i);
344 if (sux->number_of_preds() >= 2) {
345 blocks.append(new BlockPair(bb, sux));
346 }
347 }
348 }
349 }
350
351 void split_edges() {
352 BlockPair* last_pair = NULL;
353 blocks.sort(sort_pairs);
354 for (int i = 0; i < blocks.length(); i++) {
355 BlockPair* pair = blocks.at(i);
356 if (last_pair != NULL && pair->is_same(last_pair)) continue;
357 BlockBegin* from = pair->from();
358 BlockBegin* to = pair->to();
359 BlockBegin* split = from->insert_block_between(to);
360 #ifndef PRODUCT
361 if ((PrintIR || PrintIR1) && Verbose) {
362 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
363 from->block_id(), to->block_id(), split->block_id());
364 }
365 #endif
366 last_pair = pair;
367 }
368 }
369 };
370
371 void IR::split_critical_edges() {
372 CriticalEdgeFinder cef(this);
373
374 iterate_preorder(&cef);
375 cef.split_edges();
376 }
377
378
379 class UseCountComputer: public ValueVisitor, BlockClosure {
380 private:
381 void visit(Value* n) {
382 // Local instructions and Phis for expression stack values at the
383 // start of basic blocks are not added to the instruction list
384 if ((*n)->bci() == -99 && (*n)->as_Local() == NULL &&
385 (*n)->as_Phi() == NULL) {
386 assert(false, "a node was not appended to the graph");
387 Compilation::current()->bailout("a node was not appended to the graph");
388 }
389 // use n's input if not visited before
390 if (!(*n)->is_pinned() && !(*n)->has_uses()) {
391 // note: a) if the instruction is pinned, it will be handled by compute_use_count
392 // b) if the instruction has uses, it was touched before
393 // => in both cases we don't need to update n's values
394 uses_do(n);
395 }
396 // use n
397 (*n)->_use_count++;
398 }
399
400 Values* worklist;
401 int depth;
402 enum {
403 max_recurse_depth = 20
404 };
405
406 void uses_do(Value* n) {
407 depth++;
408 if (depth > max_recurse_depth) {
409 // don't allow the traversal to recurse too deeply
410 worklist->push(*n);
411 } else {
412 (*n)->input_values_do(this);
413 // special handling for some instructions
414 if ((*n)->as_BlockEnd() != NULL) {
415 // note on BlockEnd:
416 // must 'use' the stack only if the method doesn't
417 // terminate, however, in those cases stack is empty
418 (*n)->state_values_do(this);
419 }
420 }
421 depth--;
422 }
423
424 void block_do(BlockBegin* b) {
425 depth = 0;
426 // process all pinned nodes as the roots of expression trees
427 for (Instruction* n = b; n != NULL; n = n->next()) {
428 if (n->is_pinned()) uses_do(&n);
429 }
430 assert(depth == 0, "should have counted back down");
431
432 // now process any unpinned nodes which recursed too deeply
433 while (worklist->length() > 0) {
434 Value t = worklist->pop();
435 if (!t->is_pinned()) {
436 // compute the use count
437 uses_do(&t);
438
439 // pin the instruction so that LIRGenerator doesn't recurse
440 // too deeply during it's evaluation.
441 t->pin();
442 }
443 }
444 assert(depth == 0, "should have counted back down");
445 }
446
447 UseCountComputer() {
448 worklist = new Values();
449 depth = 0;
450 }
451
452 public:
453 static void compute(BlockList* blocks) {
454 UseCountComputer ucc;
455 blocks->iterate_backward(&ucc);
456 }
457 };
458
459
460 // helper macro for short definition of trace-output inside code
461 #ifndef PRODUCT
462 #define TRACE_LINEAR_SCAN(level, code) \
463 if (TraceLinearScanLevel >= level) { \
464 code; \
465 }
466 #else
467 #define TRACE_LINEAR_SCAN(level, code)
468 #endif
469
470 class ComputeLinearScanOrder : public StackObj {
471 private:
472 int _max_block_id; // the highest block_id of a block
473 int _num_blocks; // total number of blocks (smaller than _max_block_id)
474 int _num_loops; // total number of loops
475 bool _iterative_dominators;// method requires iterative computation of dominatiors
476
477 BlockList* _linear_scan_order; // the resulting list of blocks in correct order
478
479 BitMap _visited_blocks; // used for recursive processing of blocks
480 BitMap _active_blocks; // used for recursive processing of blocks
481 BitMap _dominator_blocks; // temproary BitMap used for computation of dominator
482 intArray _forward_branches; // number of incoming forward branches for each block
483 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges
484 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop
485 BlockList _work_list; // temporary list (used in mark_loops and compute_order)
486
487 // accessors for _visited_blocks and _active_blocks
488 void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); }
489 bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); }
490 bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); }
491 void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); }
492 void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); }
493 void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); }
494
495 // accessors for _forward_branches
496 void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); }
497 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()); }
498
499 // accessors for _loop_map
500 bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); }
501 void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); }
502 void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); }
503
504 // count edges between blocks
505 void count_edges(BlockBegin* cur, BlockBegin* parent);
506
507 // loop detection
508 void mark_loops();
509 void clear_non_natural_loops(BlockBegin* start_block);
510 void assign_loop_depth(BlockBegin* start_block);
511
512 // computation of final block order
513 BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b);
514 void compute_dominator(BlockBegin* cur, BlockBegin* parent);
515 int compute_weight(BlockBegin* cur);
516 bool ready_for_processing(BlockBegin* cur);
517 void sort_into_work_list(BlockBegin* b);
518 void append_block(BlockBegin* cur);
519 void compute_order(BlockBegin* start_block);
520
521 // fixup of dominators for non-natural loops
522 bool compute_dominators_iter();
523 void compute_dominators();
524
525 // debug functions
526 NOT_PRODUCT(void print_blocks();)
527 DEBUG_ONLY(void verify();)
528
529 public:
530 ComputeLinearScanOrder(BlockBegin* start_block);
531
532 // accessors for final result
533 BlockList* linear_scan_order() const { return _linear_scan_order; }
534 int num_loops() const { return _num_loops; }
535 };
536
537
538 ComputeLinearScanOrder::ComputeLinearScanOrder(BlockBegin* start_block) :
539 _max_block_id(BlockBegin::number_of_blocks()),
540 _num_blocks(0),
541 _num_loops(0),
542 _iterative_dominators(false),
543 _visited_blocks(_max_block_id),
544 _active_blocks(_max_block_id),
545 _dominator_blocks(_max_block_id),
546 _forward_branches(_max_block_id, 0),
547 _loop_end_blocks(8),
548 _work_list(8),
549 _linear_scan_order(NULL), // initialized later with correct size
550 _loop_map(0, 0) // initialized later with correct size
551 {
552 TRACE_LINEAR_SCAN(2, "***** computing linear-scan block order");
553
554 init_visited();
555 count_edges(start_block, NULL);
556
557 if (_num_loops > 0) {
558 mark_loops();
559 clear_non_natural_loops(start_block);
560 assign_loop_depth(start_block);
561 }
562
563 compute_order(start_block);
564 compute_dominators();
565
566 NOT_PRODUCT(print_blocks());
567 DEBUG_ONLY(verify());
568 }
569
570
571 // Traverse the CFG:
572 // * count total number of blocks
573 // * count all incoming edges and backward incoming edges
574 // * number loop header blocks
575 // * create a list with all loop end blocks
576 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
577 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));
578 assert(cur->dominator() == NULL, "dominator already initialized");
579
580 if (is_active(cur)) {
581 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
582 assert(is_visited(cur), "block must be visisted when block is active");
583 assert(parent != NULL, "must have parent");
584
585 cur->set(BlockBegin::linear_scan_loop_header_flag);
586 cur->set(BlockBegin::backward_branch_target_flag);
587
588 parent->set(BlockBegin::linear_scan_loop_end_flag);
589
590 // When a loop header is also the start of an exception handler, then the backward branch is
591 // an exception edge. Because such edges are usually critical edges which cannot be split, the
592 // loop must be excluded here from processing.
593 if (cur->is_set(BlockBegin::exception_entry_flag)) {
594 // Make sure that dominators are correct in this weird situation
595 _iterative_dominators = true;
596 return;
597 }
598 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
599 "loop end blocks must have one successor (critical edges are split)");
600
601 _loop_end_blocks.append(parent);
602 return;
603 }
604
605 // increment number of incoming forward branches
606 inc_forward_branches(cur);
607
608 if (is_visited(cur)) {
609 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
610 return;
611 }
612
613 _num_blocks++;
614 set_visited(cur);
615 set_active(cur);
616
617 // recursive call for all successors
618 int i;
619 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
620 count_edges(cur->sux_at(i), cur);
621 }
622 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
623 count_edges(cur->exception_handler_at(i), cur);
624 }
625
626 clear_active(cur);
627
628 // Each loop has a unique number.
629 // When multiple loops are nested, assign_loop_depth assumes that the
630 // innermost loop has the lowest number. This is guaranteed by setting
631 // the loop number after the recursive calls for the successors above
632 // have returned.
633 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
634 assert(cur->loop_index() == -1, "cannot set loop-index twice");
635 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
636
637 cur->set_loop_index(_num_loops);
638 _num_loops++;
639 }
640
641 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
642 }
643
644
645 void ComputeLinearScanOrder::mark_loops() {
646 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
647
648 _loop_map = BitMap2D(_num_loops, _max_block_id);
649 _loop_map.clear();
650
651 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
652 BlockBegin* loop_end = _loop_end_blocks.at(i);
653 BlockBegin* loop_start = loop_end->sux_at(0);
654 int loop_idx = loop_start->loop_index();
655
656 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));
657 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
658 assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
659 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
660 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
661 assert(_work_list.is_empty(), "work list must be empty before processing");
662
663 // add the end-block of the loop to the working list
664 _work_list.push(loop_end);
665 set_block_in_loop(loop_idx, loop_end);
666 do {
667 BlockBegin* cur = _work_list.pop();
668
669 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id()));
670 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
671
672 // recursive processing of all predecessors ends when start block of loop is reached
673 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
674 for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
675 BlockBegin* pred = cur->pred_at(j);
676
677 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
678 // this predecessor has not been processed yet, so add it to work list
679 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id()));
680 _work_list.push(pred);
681 set_block_in_loop(loop_idx, pred);
682 }
683 }
684 }
685 } while (!_work_list.is_empty());
686 }
687 }
688
689
690 // check for non-natural loops (loops where the loop header does not dominate
691 // all other loop blocks = loops with mulitple entries).
692 // such loops are ignored
693 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
694 for (int i = _num_loops - 1; i >= 0; i--) {
695 if (is_block_in_loop(i, start_block)) {
696 // loop i contains the entry block of the method
697 // -> this is not a natural loop, so ignore it
698 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
699
700 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
701 clear_block_in_loop(i, block_id);
702 }
703 _iterative_dominators = true;
704 }
705 }
706 }
707
708 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
709 TRACE_LINEAR_SCAN(3, "----- computing loop-depth and weight");
710 init_visited();
711
712 assert(_work_list.is_empty(), "work list must be empty before processing");
713 _work_list.append(start_block);
714
715 do {
716 BlockBegin* cur = _work_list.pop();
717
718 if (!is_visited(cur)) {
719 set_visited(cur);
720 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
721
722 // compute loop-depth and loop-index for the block
723 assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
724 int i;
725 int loop_depth = 0;
726 int min_loop_idx = -1;
727 for (i = _num_loops - 1; i >= 0; i--) {
728 if (is_block_in_loop(i, cur)) {
729 loop_depth++;
730 min_loop_idx = i;
731 }
732 }
733 cur->set_loop_depth(loop_depth);
734 cur->set_loop_index(min_loop_idx);
735
736 // append all unvisited successors to work list
737 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
738 _work_list.append(cur->sux_at(i));
739 }
740 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
741 _work_list.append(cur->exception_handler_at(i));
742 }
743 }
744 } while (!_work_list.is_empty());
745 }
746
747
748 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
749 assert(a != NULL && b != NULL, "must have input blocks");
750
751 _dominator_blocks.clear();
752 while (a != NULL) {
753 _dominator_blocks.set_bit(a->block_id());
754 assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
755 a = a->dominator();
756 }
757 while (b != NULL && !_dominator_blocks.at(b->block_id())) {
758 assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
759 b = b->dominator();
760 }
761
762 assert(b != NULL, "could not find dominator");
763 return b;
764 }
765
766 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
767 if (cur->dominator() == NULL) {
768 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
769 cur->set_dominator(parent);
770
771 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
772 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()));
773 assert(cur->number_of_preds() > 1, "");
774 cur->set_dominator(common_dominator(cur->dominator(), parent));
775 }
776 }
777
778
779 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
780 BlockBegin* single_sux = NULL;
781 if (cur->number_of_sux() == 1) {
782 single_sux = cur->sux_at(0);
783 }
784
785 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
786 int weight = (cur->loop_depth() & 0x7FFF) << 16;
787
788 // general macro for short definition of weight flags
789 // the first instance of INC_WEIGHT_IF has the highest priority
790 int cur_bit = 15;
791 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
792
793 // this is necessery for the (very rare) case that two successing blocks have
794 // the same loop depth, but a different loop index (can happen for endless loops
795 // with exception handlers)
796 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
797
798 // loop end blocks (blocks that end with a backward branch) are added
799 // after all other blocks of the loop.
800 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
801
802 // critical edge split blocks are prefered because than they have a bigger
803 // proability to be completely empty
804 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
805
806 // exceptions should not be thrown in normal control flow, so these blocks
807 // are added as late as possible
808 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL));
809 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
810
811 // exceptions handlers are added as late as possible
812 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
813
814 // guarantee that weight is > 0
815 weight |= 1;
816
817 #undef INC_WEIGHT_IF
818 assert(cur_bit >= 0, "too many flags");
819 assert(weight > 0, "weight cannot become negative");
820
821 return weight;
822 }
823
824 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
825 // Discount the edge just traveled.
826 // When the number drops to zero, all forward branches were processed
827 if (dec_forward_branches(cur) != 0) {
828 return false;
829 }
830
831 assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
832 assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
833 return true;
834 }
835
836 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
837 assert(_work_list.index_of(cur) == -1, "block already in work list");
838
839 int cur_weight = compute_weight(cur);
840
841 // the linear_scan_number is used to cache the weight of a block
842 cur->set_linear_scan_number(cur_weight);
843
844 #ifndef PRODUCT
845 if (StressLinearScan) {
846 _work_list.insert_before(0, cur);
847 return;
848 }
849 #endif
850
851 _work_list.append(NULL); // provide space for new element
852
853 int insert_idx = _work_list.length() - 1;
854 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
855 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
856 insert_idx--;
857 }
858 _work_list.at_put(insert_idx, cur);
859
860 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
861 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()));
862
863 #ifdef ASSERT
864 for (int i = 0; i < _work_list.length(); i++) {
865 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
866 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
867 }
868 #endif
869 }
870
871 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
872 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()));
873 assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
874
875 // currently, the linear scan order and code emit order are equal.
876 // therefore the linear_scan_number and the weight of a block must also
877 // be equal.
878 cur->set_linear_scan_number(_linear_scan_order->length());
879 _linear_scan_order->append(cur);
880 }
881
882 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
883 TRACE_LINEAR_SCAN(3, "----- computing final block order");
884
885 // the start block is always the first block in the linear scan order
886 _linear_scan_order = new BlockList(_num_blocks);
887 append_block(start_block);
888
889 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
890 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
891 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
892
893 BlockBegin* sux_of_osr_entry = NULL;
894 if (osr_entry != NULL) {
895 // special handling for osr entry:
896 // ignore the edge between the osr entry and its successor for processing
897 // the osr entry block is added manually below
898 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
899 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");
900
901 sux_of_osr_entry = osr_entry->sux_at(0);
902 dec_forward_branches(sux_of_osr_entry);
903
904 compute_dominator(osr_entry, start_block);
905 _iterative_dominators = true;
906 }
907 compute_dominator(std_entry, start_block);
908
909 // start processing with standard entry block
910 assert(_work_list.is_empty(), "list must be empty before processing");
911
912 if (ready_for_processing(std_entry)) {
913 sort_into_work_list(std_entry);
914 } else {
915 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
916 }
917
918 do {
919 BlockBegin* cur = _work_list.pop();
920
921 if (cur == sux_of_osr_entry) {
922 // the osr entry block is ignored in normal processing, it is never added to the
923 // work list. Instead, it is added as late as possible manually here.
924 append_block(osr_entry);
925 compute_dominator(cur, osr_entry);
926 }
927 append_block(cur);
928
929 int i;
930 int num_sux = cur->number_of_sux();
931 // changed loop order to get "intuitive" order of if- and else-blocks
932 for (i = 0; i < num_sux; i++) {
933 BlockBegin* sux = cur->sux_at(i);
934 compute_dominator(sux, cur);
935 if (ready_for_processing(sux)) {
936 sort_into_work_list(sux);
937 }
938 }
939 num_sux = cur->number_of_exception_handlers();
940 for (i = 0; i < num_sux; i++) {
941 BlockBegin* sux = cur->exception_handler_at(i);
942 compute_dominator(sux, cur);
943 if (ready_for_processing(sux)) {
944 sort_into_work_list(sux);
945 }
946 }
947 } while (_work_list.length() > 0);
948 }
949
950
951 bool ComputeLinearScanOrder::compute_dominators_iter() {
952 bool changed = false;
953 int num_blocks = _linear_scan_order->length();
954
955 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
956 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
957 for (int i = 1; i < num_blocks; i++) {
958 BlockBegin* block = _linear_scan_order->at(i);
959
960 BlockBegin* dominator = block->pred_at(0);
961 int num_preds = block->number_of_preds();
962 for (int i = 1; i < num_preds; i++) {
963 dominator = common_dominator(dominator, block->pred_at(i));
964 }
965
966 if (dominator != block->dominator()) {
967 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()));
968
969 block->set_dominator(dominator);
970 changed = true;
971 }
972 }
973 return changed;
974 }
975
976 void ComputeLinearScanOrder::compute_dominators() {
977 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
978
979 // iterative computation of dominators is only required for methods with non-natural loops
980 // and OSR-methods. For all other methods, the dominators computed when generating the
981 // linear scan block order are correct.
982 if (_iterative_dominators) {
983 do {
984 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
985 } while (compute_dominators_iter());
986 }
987
988 // check that dominators are correct
989 assert(!compute_dominators_iter(), "fix point not reached");
990 }
991
992
993 #ifndef PRODUCT
994 void ComputeLinearScanOrder::print_blocks() {
995 if (TraceLinearScanLevel >= 2) {
996 tty->print_cr("----- loop information:");
997 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
998 BlockBegin* cur = _linear_scan_order->at(block_idx);
999
1000 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
1001 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1002 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
1003 }
1004 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
1005 }
1006 }
1007
1008 if (TraceLinearScanLevel >= 1) {
1009 tty->print_cr("----- linear-scan block order:");
1010 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1011 BlockBegin* cur = _linear_scan_order->at(block_idx);
1012 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
1013
1014 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
1015 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
1016 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
1017 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
1018
1019 if (cur->dominator() != NULL) {
1020 tty->print(" dom: B%d ", cur->dominator()->block_id());
1021 } else {
1022 tty->print(" dom: NULL ");
1023 }
1024
1025 if (cur->number_of_preds() > 0) {
1026 tty->print(" preds: ");
1027 for (int j = 0; j < cur->number_of_preds(); j++) {
1028 BlockBegin* pred = cur->pred_at(j);
1029 tty->print("B%d ", pred->block_id());
1030 }
1031 }
1032 if (cur->number_of_sux() > 0) {
1033 tty->print(" sux: ");
1034 for (int j = 0; j < cur->number_of_sux(); j++) {
1035 BlockBegin* sux = cur->sux_at(j);
1036 tty->print("B%d ", sux->block_id());
1037 }
1038 }
1039 if (cur->number_of_exception_handlers() > 0) {
1040 tty->print(" ex: ");
1041 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1042 BlockBegin* ex = cur->exception_handler_at(j);
1043 tty->print("B%d ", ex->block_id());
1044 }
1045 }
1046 tty->cr();
1047 }
1048 }
1049 }
1050 #endif
1051
1052 #ifdef ASSERT
1053 void ComputeLinearScanOrder::verify() {
1054 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1055
1056 if (StressLinearScan) {
1057 // blocks are scrambled when StressLinearScan is used
1058 return;
1059 }
1060
1061 // check that all successors of a block have a higher linear-scan-number
1062 // and that all predecessors of a block have a lower linear-scan-number
1063 // (only backward branches of loops are ignored)
1064 int i;
1065 for (i = 0; i < _linear_scan_order->length(); i++) {
1066 BlockBegin* cur = _linear_scan_order->at(i);
1067
1068 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1069 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
1070
1071 int j;
1072 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1073 BlockBegin* sux = cur->sux_at(j);
1074
1075 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
1076 if (!cur->is_set(BlockBegin::linear_scan_loop_end_flag)) {
1077 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1078 }
1079 if (cur->loop_depth() == sux->loop_depth()) {
1080 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");
1081 }
1082 }
1083
1084 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1085 BlockBegin* pred = cur->pred_at(j);
1086
1087 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
1088 if (!cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
1089 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1090 }
1091 if (cur->loop_depth() == pred->loop_depth()) {
1092 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");
1093 }
1094
1095 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1096 }
1097
1098 // check dominator
1099 if (i == 0) {
1100 assert(cur->dominator() == NULL, "first block has no dominator");
1101 } else {
1102 assert(cur->dominator() != NULL, "all but first block must have dominator");
1103 }
1104 assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0), "Single predecessor must also be dominator");
1105 }
1106
1107 // check that all loops are continuous
1108 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1109 int block_idx = 0;
1110 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1111
1112 // skip blocks before the loop
1113 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1114 block_idx++;
1115 }
1116 // skip blocks of loop
1117 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1118 block_idx++;
1119 }
1120 // after the first non-loop block, there must not be another loop-block
1121 while (block_idx < _num_blocks) {
1122 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1123 block_idx++;
1124 }
1125 }
1126 }
1127 #endif
1128
1129
1130 void IR::compute_code() {
1131 assert(is_valid(), "IR must be valid");
1132
1133 ComputeLinearScanOrder compute_order(start());
1134 _num_loops = compute_order.num_loops();
1135 _code = compute_order.linear_scan_order();
1136 }
1137
1138
1139 void IR::compute_use_counts() {
1140 // make sure all values coming out of this block get evaluated.
1141 int num_blocks = _code->length();
1142 for (int i = 0; i < num_blocks; i++) {
1143 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1144 }
1145
1146 // compute use counts
1147 UseCountComputer::compute(_code);
1148 }
1149
1150
1151 void IR::iterate_preorder(BlockClosure* closure) {
1152 assert(is_valid(), "IR must be valid");
1153 start()->iterate_preorder(closure);
1154 }
1155
1156
1157 void IR::iterate_postorder(BlockClosure* closure) {
1158 assert(is_valid(), "IR must be valid");
1159 start()->iterate_postorder(closure);
1160 }
1161
1162 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1163 linear_scan_order()->iterate_forward(closure);
1164 }
1165
1166
1167 #ifndef PRODUCT
1168 class BlockPrinter: public BlockClosure {
1169 private:
1170 InstructionPrinter* _ip;
1171 bool _cfg_only;
1172 bool _live_only;
1173
1174 public:
1175 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1176 _ip = ip;
1177 _cfg_only = cfg_only;
1178 _live_only = live_only;
1179 }
1180
1181 virtual void block_do(BlockBegin* block) {
1182 if (_cfg_only) {
1183 _ip->print_instr(block); tty->cr();
1184 } else {
1185 block->print_block(*_ip, _live_only);
1186 }
1187 }
1188 };
1189
1190
1191 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1192 ttyLocker ttyl;
1193 InstructionPrinter ip(!cfg_only);
1194 BlockPrinter bp(&ip, cfg_only, live_only);
1195 start->iterate_preorder(&bp);
1196 tty->cr();
1197 }
1198
1199 void IR::print(bool cfg_only, bool live_only) {
1200 if (is_valid()) {
1201 print(start(), cfg_only, live_only);
1202 } else {
1203 tty->print_cr("invalid IR");
1204 }
1205 }
1206
1207
1208 define_array(BlockListArray, BlockList*)
1209 define_stack(BlockListList, BlockListArray)
1210
1211 class PredecessorValidator : public BlockClosure {
1212 private:
1213 BlockListList* _predecessors;
1214 BlockList* _blocks;
1215
1216 static int cmp(BlockBegin** a, BlockBegin** b) {
1217 return (*a)->block_id() - (*b)->block_id();
1218 }
1219
1220 public:
1221 PredecessorValidator(IR* hir) {
1222 ResourceMark rm;
1223 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
1224 _blocks = new BlockList();
1225
1226 int i;
1227 hir->start()->iterate_preorder(this);
1228 if (hir->code() != NULL) {
1229 assert(hir->code()->length() == _blocks->length(), "must match");
1230 for (i = 0; i < _blocks->length(); i++) {
1231 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1232 }
1233 }
1234
1235 for (i = 0; i < _blocks->length(); i++) {
1236 BlockBegin* block = _blocks->at(i);
1237 BlockList* preds = _predecessors->at(block->block_id());
1238 if (preds == NULL) {
1239 assert(block->number_of_preds() == 0, "should be the same");
1240 continue;
1241 }
1242
1243 // clone the pred list so we can mutate it
1244 BlockList* pred_copy = new BlockList();
1245 int j;
1246 for (j = 0; j < block->number_of_preds(); j++) {
1247 pred_copy->append(block->pred_at(j));
1248 }
1249 // sort them in the same order
1250 preds->sort(cmp);
1251 pred_copy->sort(cmp);
1252 int length = MIN2(preds->length(), block->number_of_preds());
1253 for (j = 0; j < block->number_of_preds(); j++) {
1254 assert(preds->at(j) == pred_copy->at(j), "must match");
1255 }
1256
1257 assert(preds->length() == block->number_of_preds(), "should be the same");
1258 }
1259 }
1260
1261 virtual void block_do(BlockBegin* block) {
1262 _blocks->append(block);
1263 BlockEnd* be = block->end();
1264 int n = be->number_of_sux();
1265 int i;
1266 for (i = 0; i < n; i++) {
1267 BlockBegin* sux = be->sux_at(i);
1268 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1269
1270 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1271 if (preds == NULL) {
1272 preds = new BlockList();
1273 _predecessors->at_put(sux->block_id(), preds);
1274 }
1275 preds->append(block);
1276 }
1277
1278 n = block->number_of_exception_handlers();
1279 for (i = 0; i < n; i++) {
1280 BlockBegin* sux = block->exception_handler_at(i);
1281 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1282
1283 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1284 if (preds == NULL) {
1285 preds = new BlockList();
1286 _predecessors->at_put(sux->block_id(), preds);
1287 }
1288 preds->append(block);
1289 }
1290 }
1291 };
1292
1293 void IR::verify() {
1294 #ifdef ASSERT
1295 PredecessorValidator pv(this);
1296 #endif
1297 }
1298
1299 #endif // PRODUCT
1300
1301 void SubstitutionResolver::visit(Value* v) {
1302 Value v0 = *v;
1303 if (v0) {
1304 Value vs = v0->subst();
1305 if (vs != v0) {
1306 *v = v0->subst();
1307 }
1308 }
1309 }
1310
1311 #ifdef ASSERT
1312 class SubstitutionChecker: public ValueVisitor {
1313 void visit(Value* v) {
1314 Value v0 = *v;
1315 if (v0) {
1316 Value vs = v0->subst();
1317 assert(vs == v0, "missed substitution");
1318 }
1319 }
1320 };
1321 #endif
1322
1323
1324 void SubstitutionResolver::block_do(BlockBegin* block) {
1325 Instruction* last = NULL;
1326 for (Instruction* n = block; n != NULL;) {
1327 n->values_do(this);
1328 // need to remove this instruction from the instruction stream
1329 if (n->subst() != n) {
1330 assert(last != NULL, "must have last");
1331 last->set_next(n->next(), n->next()->bci());
1332 } else {
1333 last = n;
1334 }
1335 n = last->next();
1336 }
1337
1338 #ifdef ASSERT
1339 SubstitutionChecker check_substitute;
1340 if (block->state()) block->state()->values_do(&check_substitute);
1341 block->block_values_do(&check_substitute);
1342 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
1343 #endif
1344 }