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 // initialize data structures
291 ValueType::initialize();
292 Instruction::initialize();
293 BlockBegin::initialize();
294 GraphBuilder::initialize();
295 // setup IR fields
296 _compilation = compilation;
297 _top_scope = new IRScope(compilation, NULL, -1, method, osr_bci, true);
298 _code = NULL;
299 }
300
301
302 void IR::optimize() {
303 Optimizer opt(this);
304 if (DoCEE) {
305 opt.eliminate_conditional_expressions();
306 #ifndef PRODUCT
307 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
308 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
309 #endif
310 }
311 if (EliminateBlocks) {
312 opt.eliminate_blocks();
313 #ifndef PRODUCT
314 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
315 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
316 #endif
317 }
318 if (EliminateNullChecks) {
319 opt.eliminate_null_checks();
320 #ifndef PRODUCT
321 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
322 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
323 #endif
324 }
325 }
326
327
328 static int sort_pairs(BlockPair** a, BlockPair** b) {
329 if ((*a)->from() == (*b)->from()) {
330 return (*a)->to()->block_id() - (*b)->to()->block_id();
331 } else {
332 return (*a)->from()->block_id() - (*b)->from()->block_id();
333 }
334 }
335
336
337 class CriticalEdgeFinder: public BlockClosure {
338 BlockPairList blocks;
339 IR* _ir;
340
341 public:
342 CriticalEdgeFinder(IR* ir): _ir(ir) {}
343 void block_do(BlockBegin* bb) {
344 BlockEnd* be = bb->end();
345 int nos = be->number_of_sux();
346 if (nos >= 2) {
347 for (int i = 0; i < nos; i++) {
348 BlockBegin* sux = be->sux_at(i);
349 if (sux->number_of_preds() >= 2) {
350 blocks.append(new BlockPair(bb, sux));
351 }
352 }
353 }
354 }
355
356 void split_edges() {
357 BlockPair* last_pair = NULL;
358 blocks.sort(sort_pairs);
359 for (int i = 0; i < blocks.length(); i++) {
360 BlockPair* pair = blocks.at(i);
361 if (last_pair != NULL && pair->is_same(last_pair)) continue;
362 BlockBegin* from = pair->from();
363 BlockBegin* to = pair->to();
364 BlockBegin* split = from->insert_block_between(to);
365 #ifndef PRODUCT
366 if ((PrintIR || PrintIR1) && Verbose) {
367 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
368 from->block_id(), to->block_id(), split->block_id());
369 }
370 #endif
371 last_pair = pair;
372 }
373 }
374 };
375
376 void IR::split_critical_edges() {
377 CriticalEdgeFinder cef(this);
378
379 iterate_preorder(&cef);
380 cef.split_edges();
381 }
382
383
384 class UseCountComputer: public AllStatic {
385 private:
386 static void update_use_count(Value* n) {
387 // Local instructions and Phis for expression stack values at the
388 // start of basic blocks are not added to the instruction list
389 if ((*n)->bci() == -99 && (*n)->as_Local() == NULL &&
390 (*n)->as_Phi() == NULL) {
391 assert(false, "a node was not appended to the graph");
392 Compilation::current_compilation()->bailout("a node was not appended to the graph");
393 }
394 // use n's input if not visited before
395 if (!(*n)->is_pinned() && !(*n)->has_uses()) {
396 // note: a) if the instruction is pinned, it will be handled by compute_use_count
397 // b) if the instruction has uses, it was touched before
398 // => in both cases we don't need to update n's values
399 uses_do(n);
400 }
401 // use n
402 (*n)->_use_count++;
403 }
404
405 static Values* worklist;
406 static int depth;
407 enum {
408 max_recurse_depth = 20
409 };
410
411 static void uses_do(Value* n) {
412 depth++;
413 if (depth > max_recurse_depth) {
414 // don't allow the traversal to recurse too deeply
415 worklist->push(*n);
416 } else {
417 (*n)->input_values_do(update_use_count);
418 // special handling for some instructions
419 if ((*n)->as_BlockEnd() != NULL) {
420 // note on BlockEnd:
421 // must 'use' the stack only if the method doesn't
422 // terminate, however, in those cases stack is empty
423 (*n)->state_values_do(update_use_count);
424 }
425 }
426 depth--;
427 }
428
429 static void basic_compute_use_count(BlockBegin* b) {
430 depth = 0;
431 // process all pinned nodes as the roots of expression trees
432 for (Instruction* n = b; n != NULL; n = n->next()) {
433 if (n->is_pinned()) uses_do(&n);
434 }
435 assert(depth == 0, "should have counted back down");
436
437 // now process any unpinned nodes which recursed too deeply
438 while (worklist->length() > 0) {
439 Value t = worklist->pop();
440 if (!t->is_pinned()) {
441 // compute the use count
442 uses_do(&t);
443
444 // pin the instruction so that LIRGenerator doesn't recurse
445 // too deeply during it's evaluation.
446 t->pin();
447 }
448 }
449 assert(depth == 0, "should have counted back down");
450 }
451
452 public:
453 static void compute(BlockList* blocks) {
454 worklist = new Values();
455 blocks->blocks_do(basic_compute_use_count);
456 worklist = NULL;
457 }
458 };
459
460
461 Values* UseCountComputer::worklist = NULL;
462 int UseCountComputer::depth = 0;
463
464 // helper macro for short definition of trace-output inside code
465 #ifndef PRODUCT
466 #define TRACE_LINEAR_SCAN(level, code) \
467 if (TraceLinearScanLevel >= level) { \
468 code; \
469 }
470 #else
471 #define TRACE_LINEAR_SCAN(level, code)
472 #endif
473
474 class ComputeLinearScanOrder : public StackObj {
475 private:
476 int _max_block_id; // the highest block_id of a block
477 int _num_blocks; // total number of blocks (smaller than _max_block_id)
478 int _num_loops; // total number of loops
479 bool _iterative_dominators;// method requires iterative computation of dominatiors
480
481 BlockList* _linear_scan_order; // the resulting list of blocks in correct order
482
483 BitMap _visited_blocks; // used for recursive processing of blocks
484 BitMap _active_blocks; // used for recursive processing of blocks
485 BitMap _dominator_blocks; // temproary BitMap used for computation of dominator
486 intArray _forward_branches; // number of incoming forward branches for each block
487 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges
488 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop
489 BlockList _work_list; // temporary list (used in mark_loops and compute_order)
490
491 // accessors for _visited_blocks and _active_blocks
492 void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); }
493 bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); }
494 bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); }
495 void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); }
496 void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); }
497 void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); }
498
499 // accessors for _forward_branches
500 void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); }
501 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()); }
502
503 // accessors for _loop_map
504 bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); }
505 void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); }
506 void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); }
507
508 // count edges between blocks
509 void count_edges(BlockBegin* cur, BlockBegin* parent);
510
511 // loop detection
512 void mark_loops();
513 void clear_non_natural_loops(BlockBegin* start_block);
514 void assign_loop_depth(BlockBegin* start_block);
515
516 // computation of final block order
517 BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b);
518 void compute_dominator(BlockBegin* cur, BlockBegin* parent);
519 int compute_weight(BlockBegin* cur);
520 bool ready_for_processing(BlockBegin* cur);
521 void sort_into_work_list(BlockBegin* b);
522 void append_block(BlockBegin* cur);
523 void compute_order(BlockBegin* start_block);
524
525 // fixup of dominators for non-natural loops
526 bool compute_dominators_iter();
527 void compute_dominators();
528
529 // debug functions
530 NOT_PRODUCT(void print_blocks();)
531 DEBUG_ONLY(void verify();)
532
533 public:
534 ComputeLinearScanOrder(BlockBegin* start_block);
535
536 // accessors for final result
537 BlockList* linear_scan_order() const { return _linear_scan_order; }
538 int num_loops() const { return _num_loops; }
539 };
540
541
542 ComputeLinearScanOrder::ComputeLinearScanOrder(BlockBegin* start_block) :
543 _max_block_id(BlockBegin::number_of_blocks()),
544 _num_blocks(0),
545 _num_loops(0),
546 _iterative_dominators(false),
547 _visited_blocks(_max_block_id),
548 _active_blocks(_max_block_id),
549 _dominator_blocks(_max_block_id),
550 _forward_branches(_max_block_id, 0),
551 _loop_end_blocks(8),
552 _work_list(8),
553 _linear_scan_order(NULL), // initialized later with correct size
554 _loop_map(0, 0) // initialized later with correct size
555 {
556 TRACE_LINEAR_SCAN(2, "***** computing linear-scan block order");
557
558 init_visited();
559 count_edges(start_block, NULL);
560
561 if (_num_loops > 0) {
562 mark_loops();
563 clear_non_natural_loops(start_block);
564 assign_loop_depth(start_block);
565 }
566
567 compute_order(start_block);
568 compute_dominators();
569
570 NOT_PRODUCT(print_blocks());
571 DEBUG_ONLY(verify());
572 }
573
574
575 // Traverse the CFG:
576 // * count total number of blocks
577 // * count all incoming edges and backward incoming edges
578 // * number loop header blocks
579 // * create a list with all loop end blocks
580 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
581 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));
582 assert(cur->dominator() == NULL, "dominator already initialized");
583
584 if (is_active(cur)) {
585 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
586 assert(is_visited(cur), "block must be visisted when block is active");
587 assert(parent != NULL, "must have parent");
588
589 cur->set(BlockBegin::linear_scan_loop_header_flag);
590 cur->set(BlockBegin::backward_branch_target_flag);
591
592 parent->set(BlockBegin::linear_scan_loop_end_flag);
593
594 // When a loop header is also the start of an exception handler, then the backward branch is
595 // an exception edge. Because such edges are usually critical edges which cannot be split, the
596 // loop must be excluded here from processing.
597 if (cur->is_set(BlockBegin::exception_entry_flag)) {
598 // Make sure that dominators are correct in this weird situation
599 _iterative_dominators = true;
600 return;
601 }
602 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
603 "loop end blocks must have one successor (critical edges are split)");
604
605 _loop_end_blocks.append(parent);
606 return;
607 }
608
609 // increment number of incoming forward branches
610 inc_forward_branches(cur);
611
612 if (is_visited(cur)) {
613 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
614 return;
615 }
616
617 _num_blocks++;
618 set_visited(cur);
619 set_active(cur);
620
621 // recursive call for all successors
622 int i;
623 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
624 count_edges(cur->sux_at(i), cur);
625 }
626 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
627 count_edges(cur->exception_handler_at(i), cur);
628 }
629
630 clear_active(cur);
631
632 // Each loop has a unique number.
633 // When multiple loops are nested, assign_loop_depth assumes that the
634 // innermost loop has the lowest number. This is guaranteed by setting
635 // the loop number after the recursive calls for the successors above
636 // have returned.
637 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
638 assert(cur->loop_index() == -1, "cannot set loop-index twice");
639 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
640
641 cur->set_loop_index(_num_loops);
642 _num_loops++;
643 }
644
645 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
646 }
647
648
649 void ComputeLinearScanOrder::mark_loops() {
650 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
651
652 _loop_map = BitMap2D(_num_loops, _max_block_id);
653 _loop_map.clear();
654
655 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
656 BlockBegin* loop_end = _loop_end_blocks.at(i);
657 BlockBegin* loop_start = loop_end->sux_at(0);
658 int loop_idx = loop_start->loop_index();
659
660 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));
661 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
662 assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
663 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
664 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
665 assert(_work_list.is_empty(), "work list must be empty before processing");
666
667 // add the end-block of the loop to the working list
668 _work_list.push(loop_end);
669 set_block_in_loop(loop_idx, loop_end);
670 do {
671 BlockBegin* cur = _work_list.pop();
672
673 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id()));
674 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
675
676 // recursive processing of all predecessors ends when start block of loop is reached
677 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
678 for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
679 BlockBegin* pred = cur->pred_at(j);
680
681 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
682 // this predecessor has not been processed yet, so add it to work list
683 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id()));
684 _work_list.push(pred);
685 set_block_in_loop(loop_idx, pred);
686 }
687 }
688 }
689 } while (!_work_list.is_empty());
690 }
691 }
692
693
694 // check for non-natural loops (loops where the loop header does not dominate
695 // all other loop blocks = loops with mulitple entries).
696 // such loops are ignored
697 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
698 for (int i = _num_loops - 1; i >= 0; i--) {
699 if (is_block_in_loop(i, start_block)) {
700 // loop i contains the entry block of the method
701 // -> this is not a natural loop, so ignore it
702 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
703
704 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
705 clear_block_in_loop(i, block_id);
706 }
707 _iterative_dominators = true;
708 }
709 }
710 }
711
712 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
713 TRACE_LINEAR_SCAN(3, "----- computing loop-depth and weight");
714 init_visited();
715
716 assert(_work_list.is_empty(), "work list must be empty before processing");
717 _work_list.append(start_block);
718
719 do {
720 BlockBegin* cur = _work_list.pop();
721
722 if (!is_visited(cur)) {
723 set_visited(cur);
724 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
725
726 // compute loop-depth and loop-index for the block
727 assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
728 int i;
729 int loop_depth = 0;
730 int min_loop_idx = -1;
731 for (i = _num_loops - 1; i >= 0; i--) {
732 if (is_block_in_loop(i, cur)) {
733 loop_depth++;
734 min_loop_idx = i;
735 }
736 }
737 cur->set_loop_depth(loop_depth);
738 cur->set_loop_index(min_loop_idx);
739
740 // append all unvisited successors to work list
741 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
742 _work_list.append(cur->sux_at(i));
743 }
744 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
745 _work_list.append(cur->exception_handler_at(i));
746 }
747 }
748 } while (!_work_list.is_empty());
749 }
750
751
752 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
753 assert(a != NULL && b != NULL, "must have input blocks");
754
755 _dominator_blocks.clear();
756 while (a != NULL) {
757 _dominator_blocks.set_bit(a->block_id());
758 assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
759 a = a->dominator();
760 }
761 while (b != NULL && !_dominator_blocks.at(b->block_id())) {
762 assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
763 b = b->dominator();
764 }
765
766 assert(b != NULL, "could not find dominator");
767 return b;
768 }
769
770 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
771 if (cur->dominator() == NULL) {
772 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
773 cur->set_dominator(parent);
774
775 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
776 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()));
777 assert(cur->number_of_preds() > 1, "");
778 cur->set_dominator(common_dominator(cur->dominator(), parent));
779 }
780 }
781
782
783 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
784 BlockBegin* single_sux = NULL;
785 if (cur->number_of_sux() == 1) {
786 single_sux = cur->sux_at(0);
787 }
788
789 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
790 int weight = (cur->loop_depth() & 0x7FFF) << 16;
791
792 // general macro for short definition of weight flags
793 // the first instance of INC_WEIGHT_IF has the highest priority
794 int cur_bit = 15;
795 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
796
797 // this is necessery for the (very rare) case that two successing blocks have
798 // the same loop depth, but a different loop index (can happen for endless loops
799 // with exception handlers)
800 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
801
802 // loop end blocks (blocks that end with a backward branch) are added
803 // after all other blocks of the loop.
804 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
805
806 // critical edge split blocks are prefered because than they have a bigger
807 // proability to be completely empty
808 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
809
810 // exceptions should not be thrown in normal control flow, so these blocks
811 // are added as late as possible
812 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL));
813 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
814
815 // exceptions handlers are added as late as possible
816 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
817
818 // guarantee that weight is > 0
819 weight |= 1;
820
821 #undef INC_WEIGHT_IF
822 assert(cur_bit >= 0, "too many flags");
823 assert(weight > 0, "weight cannot become negative");
824
825 return weight;
826 }
827
828 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
829 // Discount the edge just traveled.
830 // When the number drops to zero, all forward branches were processed
831 if (dec_forward_branches(cur) != 0) {
832 return false;
833 }
834
835 assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
836 assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
837 return true;
838 }
839
840 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
841 assert(_work_list.index_of(cur) == -1, "block already in work list");
842
843 int cur_weight = compute_weight(cur);
844
845 // the linear_scan_number is used to cache the weight of a block
846 cur->set_linear_scan_number(cur_weight);
847
848 #ifndef PRODUCT
849 if (StressLinearScan) {
850 _work_list.insert_before(0, cur);
851 return;
852 }
853 #endif
854
855 _work_list.append(NULL); // provide space for new element
856
857 int insert_idx = _work_list.length() - 1;
858 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
859 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
860 insert_idx--;
861 }
862 _work_list.at_put(insert_idx, cur);
863
864 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
865 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()));
866
867 #ifdef ASSERT
868 for (int i = 0; i < _work_list.length(); i++) {
869 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
870 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
871 }
872 #endif
873 }
874
875 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
876 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()));
877 assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
878
879 // currently, the linear scan order and code emit order are equal.
880 // therefore the linear_scan_number and the weight of a block must also
881 // be equal.
882 cur->set_linear_scan_number(_linear_scan_order->length());
883 _linear_scan_order->append(cur);
884 }
885
886 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
887 TRACE_LINEAR_SCAN(3, "----- computing final block order");
888
889 // the start block is always the first block in the linear scan order
890 _linear_scan_order = new BlockList(_num_blocks);
891 append_block(start_block);
892
893 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
894 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
895 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
896
897 BlockBegin* sux_of_osr_entry = NULL;
898 if (osr_entry != NULL) {
899 // special handling for osr entry:
900 // ignore the edge between the osr entry and its successor for processing
901 // the osr entry block is added manually below
902 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
903 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");
904
905 sux_of_osr_entry = osr_entry->sux_at(0);
906 dec_forward_branches(sux_of_osr_entry);
907
908 compute_dominator(osr_entry, start_block);
909 _iterative_dominators = true;
910 }
911 compute_dominator(std_entry, start_block);
912
913 // start processing with standard entry block
914 assert(_work_list.is_empty(), "list must be empty before processing");
915
916 if (ready_for_processing(std_entry)) {
917 sort_into_work_list(std_entry);
918 } else {
919 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
920 }
921
922 do {
923 BlockBegin* cur = _work_list.pop();
924
925 if (cur == sux_of_osr_entry) {
926 // the osr entry block is ignored in normal processing, it is never added to the
927 // work list. Instead, it is added as late as possible manually here.
928 append_block(osr_entry);
929 compute_dominator(cur, osr_entry);
930 }
931 append_block(cur);
932
933 int i;
934 int num_sux = cur->number_of_sux();
935 // changed loop order to get "intuitive" order of if- and else-blocks
936 for (i = 0; i < num_sux; i++) {
937 BlockBegin* sux = cur->sux_at(i);
938 compute_dominator(sux, cur);
939 if (ready_for_processing(sux)) {
940 sort_into_work_list(sux);
941 }
942 }
943 num_sux = cur->number_of_exception_handlers();
944 for (i = 0; i < num_sux; i++) {
945 BlockBegin* sux = cur->exception_handler_at(i);
946 compute_dominator(sux, cur);
947 if (ready_for_processing(sux)) {
948 sort_into_work_list(sux);
949 }
950 }
951 } while (_work_list.length() > 0);
952 }
953
954
955 bool ComputeLinearScanOrder::compute_dominators_iter() {
956 bool changed = false;
957 int num_blocks = _linear_scan_order->length();
958
959 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
960 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
961 for (int i = 1; i < num_blocks; i++) {
962 BlockBegin* block = _linear_scan_order->at(i);
963
964 BlockBegin* dominator = block->pred_at(0);
965 int num_preds = block->number_of_preds();
966 for (int i = 1; i < num_preds; i++) {
967 dominator = common_dominator(dominator, block->pred_at(i));
968 }
969
970 if (dominator != block->dominator()) {
971 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()));
972
973 block->set_dominator(dominator);
974 changed = true;
975 }
976 }
977 return changed;
978 }
979
980 void ComputeLinearScanOrder::compute_dominators() {
981 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
982
983 // iterative computation of dominators is only required for methods with non-natural loops
984 // and OSR-methods. For all other methods, the dominators computed when generating the
985 // linear scan block order are correct.
986 if (_iterative_dominators) {
987 do {
988 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
989 } while (compute_dominators_iter());
990 }
991
992 // check that dominators are correct
993 assert(!compute_dominators_iter(), "fix point not reached");
994 }
995
996
997 #ifndef PRODUCT
998 void ComputeLinearScanOrder::print_blocks() {
999 if (TraceLinearScanLevel >= 2) {
1000 tty->print_cr("----- loop information:");
1001 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1002 BlockBegin* cur = _linear_scan_order->at(block_idx);
1003
1004 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
1005 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1006 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
1007 }
1008 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
1009 }
1010 }
1011
1012 if (TraceLinearScanLevel >= 1) {
1013 tty->print_cr("----- linear-scan block order:");
1014 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1015 BlockBegin* cur = _linear_scan_order->at(block_idx);
1016 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
1017
1018 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
1019 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
1020 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
1021 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
1022
1023 if (cur->dominator() != NULL) {
1024 tty->print(" dom: B%d ", cur->dominator()->block_id());
1025 } else {
1026 tty->print(" dom: NULL ");
1027 }
1028
1029 if (cur->number_of_preds() > 0) {
1030 tty->print(" preds: ");
1031 for (int j = 0; j < cur->number_of_preds(); j++) {
1032 BlockBegin* pred = cur->pred_at(j);
1033 tty->print("B%d ", pred->block_id());
1034 }
1035 }
1036 if (cur->number_of_sux() > 0) {
1037 tty->print(" sux: ");
1038 for (int j = 0; j < cur->number_of_sux(); j++) {
1039 BlockBegin* sux = cur->sux_at(j);
1040 tty->print("B%d ", sux->block_id());
1041 }
1042 }
1043 if (cur->number_of_exception_handlers() > 0) {
1044 tty->print(" ex: ");
1045 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1046 BlockBegin* ex = cur->exception_handler_at(j);
1047 tty->print("B%d ", ex->block_id());
1048 }
1049 }
1050 tty->cr();
1051 }
1052 }
1053 }
1054 #endif
1055
1056 #ifdef ASSERT
1057 void ComputeLinearScanOrder::verify() {
1058 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1059
1060 if (StressLinearScan) {
1061 // blocks are scrambled when StressLinearScan is used
1062 return;
1063 }
1064
1065 // check that all successors of a block have a higher linear-scan-number
1066 // and that all predecessors of a block have a lower linear-scan-number
1067 // (only backward branches of loops are ignored)
1068 int i;
1069 for (i = 0; i < _linear_scan_order->length(); i++) {
1070 BlockBegin* cur = _linear_scan_order->at(i);
1071
1072 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1073 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
1074
1075 int j;
1076 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1077 BlockBegin* sux = cur->sux_at(j);
1078
1079 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
1080 if (!cur->is_set(BlockBegin::linear_scan_loop_end_flag)) {
1081 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1082 }
1083 if (cur->loop_depth() == sux->loop_depth()) {
1084 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");
1085 }
1086 }
1087
1088 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1089 BlockBegin* pred = cur->pred_at(j);
1090
1091 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
1092 if (!cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
1093 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1094 }
1095 if (cur->loop_depth() == pred->loop_depth()) {
1096 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");
1097 }
1098
1099 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1100 }
1101
1102 // check dominator
1103 if (i == 0) {
1104 assert(cur->dominator() == NULL, "first block has no dominator");
1105 } else {
1106 assert(cur->dominator() != NULL, "all but first block must have dominator");
1107 }
1108 assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0), "Single predecessor must also be dominator");
1109 }
1110
1111 // check that all loops are continuous
1112 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1113 int block_idx = 0;
1114 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1115
1116 // skip blocks before the loop
1117 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1118 block_idx++;
1119 }
1120 // skip blocks of loop
1121 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1122 block_idx++;
1123 }
1124 // after the first non-loop block, there must not be another loop-block
1125 while (block_idx < _num_blocks) {
1126 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1127 block_idx++;
1128 }
1129 }
1130 }
1131 #endif
1132
1133
1134 void IR::compute_code() {
1135 assert(is_valid(), "IR must be valid");
1136
1137 ComputeLinearScanOrder compute_order(start());
1138 _num_loops = compute_order.num_loops();
1139 _code = compute_order.linear_scan_order();
1140 }
1141
1142
1143 void IR::compute_use_counts() {
1144 // make sure all values coming out of this block get evaluated.
1145 int num_blocks = _code->length();
1146 for (int i = 0; i < num_blocks; i++) {
1147 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1148 }
1149
1150 // compute use counts
1151 UseCountComputer::compute(_code);
1152 }
1153
1154
1155 void IR::iterate_preorder(BlockClosure* closure) {
1156 assert(is_valid(), "IR must be valid");
1157 start()->iterate_preorder(closure);
1158 }
1159
1160
1161 void IR::iterate_postorder(BlockClosure* closure) {
1162 assert(is_valid(), "IR must be valid");
1163 start()->iterate_postorder(closure);
1164 }
1165
1166 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1167 linear_scan_order()->iterate_forward(closure);
1168 }
1169
1170
1171 #ifndef PRODUCT
1172 class BlockPrinter: public BlockClosure {
1173 private:
1174 InstructionPrinter* _ip;
1175 bool _cfg_only;
1176 bool _live_only;
1177
1178 public:
1179 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1180 _ip = ip;
1181 _cfg_only = cfg_only;
1182 _live_only = live_only;
1183 }
1184
1185 virtual void block_do(BlockBegin* block) {
1186 if (_cfg_only) {
1187 _ip->print_instr(block); tty->cr();
1188 } else {
1189 block->print_block(*_ip, _live_only);
1190 }
1191 }
1192 };
1193
1194
1195 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1196 ttyLocker ttyl;
1197 InstructionPrinter ip(!cfg_only);
1198 BlockPrinter bp(&ip, cfg_only, live_only);
1199 start->iterate_preorder(&bp);
1200 tty->cr();
1201 }
1202
1203 void IR::print(bool cfg_only, bool live_only) {
1204 if (is_valid()) {
1205 print(start(), cfg_only, live_only);
1206 } else {
1207 tty->print_cr("invalid IR");
1208 }
1209 }
1210
1211
1212 define_array(BlockListArray, BlockList*)
1213 define_stack(BlockListList, BlockListArray)
1214
1215 class PredecessorValidator : public BlockClosure {
1216 private:
1217 BlockListList* _predecessors;
1218 BlockList* _blocks;
1219
1220 static int cmp(BlockBegin** a, BlockBegin** b) {
1221 return (*a)->block_id() - (*b)->block_id();
1222 }
1223
1224 public:
1225 PredecessorValidator(IR* hir) {
1226 ResourceMark rm;
1227 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
1228 _blocks = new BlockList();
1229
1230 int i;
1231 hir->start()->iterate_preorder(this);
1232 if (hir->code() != NULL) {
1233 assert(hir->code()->length() == _blocks->length(), "must match");
1234 for (i = 0; i < _blocks->length(); i++) {
1235 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1236 }
1237 }
1238
1239 for (i = 0; i < _blocks->length(); i++) {
1240 BlockBegin* block = _blocks->at(i);
1241 BlockList* preds = _predecessors->at(block->block_id());
1242 if (preds == NULL) {
1243 assert(block->number_of_preds() == 0, "should be the same");
1244 continue;
1245 }
1246
1247 // clone the pred list so we can mutate it
1248 BlockList* pred_copy = new BlockList();
1249 int j;
1250 for (j = 0; j < block->number_of_preds(); j++) {
1251 pred_copy->append(block->pred_at(j));
1252 }
1253 // sort them in the same order
1254 preds->sort(cmp);
1255 pred_copy->sort(cmp);
1256 int length = MIN2(preds->length(), block->number_of_preds());
1257 for (j = 0; j < block->number_of_preds(); j++) {
1258 assert(preds->at(j) == pred_copy->at(j), "must match");
1259 }
1260
1261 assert(preds->length() == block->number_of_preds(), "should be the same");
1262 }
1263 }
1264
1265 virtual void block_do(BlockBegin* block) {
1266 _blocks->append(block);
1267 BlockEnd* be = block->end();
1268 int n = be->number_of_sux();
1269 int i;
1270 for (i = 0; i < n; i++) {
1271 BlockBegin* sux = be->sux_at(i);
1272 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1273
1274 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1275 if (preds == NULL) {
1276 preds = new BlockList();
1277 _predecessors->at_put(sux->block_id(), preds);
1278 }
1279 preds->append(block);
1280 }
1281
1282 n = block->number_of_exception_handlers();
1283 for (i = 0; i < n; i++) {
1284 BlockBegin* sux = block->exception_handler_at(i);
1285 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1286
1287 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1288 if (preds == NULL) {
1289 preds = new BlockList();
1290 _predecessors->at_put(sux->block_id(), preds);
1291 }
1292 preds->append(block);
1293 }
1294 }
1295 };
1296
1297 void IR::verify() {
1298 #ifdef ASSERT
1299 PredecessorValidator pv(this);
1300 #endif
1301 }
1302
1303 #endif // PRODUCT
1304
1305 void SubstitutionResolver::substitute(Value* v) {
1306 Value v0 = *v;
1307 if (v0) {
1308 Value vs = v0->subst();
1309 if (vs != v0) {
1310 *v = v0->subst();
1311 }
1312 }
1313 }
1314
1315 #ifdef ASSERT
1316 void check_substitute(Value* v) {
1317 Value v0 = *v;
1318 if (v0) {
1319 Value vs = v0->subst();
1320 assert(vs == v0, "missed substitution");
1321 }
1322 }
1323 #endif
1324
1325
1326 void SubstitutionResolver::block_do(BlockBegin* block) {
1327 Instruction* last = NULL;
1328 for (Instruction* n = block; n != NULL;) {
1329 n->values_do(substitute);
1330 // need to remove this instruction from the instruction stream
1331 if (n->subst() != n) {
1332 assert(last != NULL, "must have last");
1333 last->set_next(n->next(), n->next()->bci());
1334 } else {
1335 last = n;
1336 }
1337 n = last->next();
1338 }
1339
1340 #ifdef ASSERT
1341 if (block->state()) block->state()->values_do(check_substitute);
1342 block->block_values_do(check_substitute);
1343 if (block->end() && block->end()->state()) block->end()->state()->values_do(check_substitute);
1344 #endif
1345 }