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 (!compilation()->profile_branches()) {
300 if (DoCEE) {
301 opt.eliminate_conditional_expressions();
302 #ifndef PRODUCT
303 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
304 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
305 #endif
306 }
307 if (EliminateBlocks) {
308 opt.eliminate_blocks();
309 #ifndef PRODUCT
310 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
311 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
312 #endif
313 }
314 }
315 if (EliminateNullChecks) {
316 opt.eliminate_null_checks();
317 #ifndef PRODUCT
318 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
319 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
320 #endif
321 }
322 }
323
324
325 static int sort_pairs(BlockPair** a, BlockPair** b) {
326 if ((*a)->from() == (*b)->from()) {
327 return (*a)->to()->block_id() - (*b)->to()->block_id();
328 } else {
329 return (*a)->from()->block_id() - (*b)->from()->block_id();
330 }
331 }
332
333
334 class CriticalEdgeFinder: public BlockClosure {
335 BlockPairList blocks;
336 IR* _ir;
337
338 public:
339 CriticalEdgeFinder(IR* ir): _ir(ir) {}
340 void block_do(BlockBegin* bb) {
341 BlockEnd* be = bb->end();
342 int nos = be->number_of_sux();
343 if (nos >= 2) {
344 for (int i = 0; i < nos; i++) {
345 BlockBegin* sux = be->sux_at(i);
346 if (sux->number_of_preds() >= 2) {
347 blocks.append(new BlockPair(bb, sux));
348 }
349 }
350 }
351 }
352
353 void split_edges() {
354 BlockPair* last_pair = NULL;
355 blocks.sort(sort_pairs);
356 for (int i = 0; i < blocks.length(); i++) {
357 BlockPair* pair = blocks.at(i);
358 if (last_pair != NULL && pair->is_same(last_pair)) continue;
359 BlockBegin* from = pair->from();
360 BlockBegin* to = pair->to();
361 BlockBegin* split = from->insert_block_between(to);
362 #ifndef PRODUCT
363 if ((PrintIR || PrintIR1) && Verbose) {
364 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
365 from->block_id(), to->block_id(), split->block_id());
366 }
367 #endif
368 last_pair = pair;
369 }
370 }
371 };
372
373 void IR::split_critical_edges() {
374 CriticalEdgeFinder cef(this);
375
376 iterate_preorder(&cef);
377 cef.split_edges();
378 }
379
380
381 class UseCountComputer: public ValueVisitor, BlockClosure {
382 private:
383 void visit(Value* n) {
384 // Local instructions and Phis for expression stack values at the
385 // start of basic blocks are not added to the instruction list
386 if ((*n)->bci() == -99 && (*n)->as_Local() == NULL &&
387 (*n)->as_Phi() == NULL) {
388 assert(false, "a node was not appended to the graph");
389 Compilation::current()->bailout("a node was not appended to the graph");
390 }
391 // use n's input if not visited before
392 if (!(*n)->is_pinned() && !(*n)->has_uses()) {
393 // note: a) if the instruction is pinned, it will be handled by compute_use_count
394 // b) if the instruction has uses, it was touched before
395 // => in both cases we don't need to update n's values
396 uses_do(n);
397 }
398 // use n
399 (*n)->_use_count++;
400 }
401
402 Values* worklist;
403 int depth;
404 enum {
405 max_recurse_depth = 20
406 };
407
408 void uses_do(Value* n) {
409 depth++;
410 if (depth > max_recurse_depth) {
411 // don't allow the traversal to recurse too deeply
412 worklist->push(*n);
413 } else {
414 (*n)->input_values_do(this);
415 // special handling for some instructions
416 if ((*n)->as_BlockEnd() != NULL) {
417 // note on BlockEnd:
418 // must 'use' the stack only if the method doesn't
419 // terminate, however, in those cases stack is empty
420 (*n)->state_values_do(this);
421 }
422 }
423 depth--;
424 }
425
426 void block_do(BlockBegin* b) {
427 depth = 0;
428 // process all pinned nodes as the roots of expression trees
429 for (Instruction* n = b; n != NULL; n = n->next()) {
430 if (n->is_pinned()) uses_do(&n);
431 }
432 assert(depth == 0, "should have counted back down");
433
434 // now process any unpinned nodes which recursed too deeply
435 while (worklist->length() > 0) {
436 Value t = worklist->pop();
437 if (!t->is_pinned()) {
438 // compute the use count
439 uses_do(&t);
440
441 // pin the instruction so that LIRGenerator doesn't recurse
442 // too deeply during it's evaluation.
443 t->pin();
444 }
445 }
446 assert(depth == 0, "should have counted back down");
447 }
448
449 UseCountComputer() {
450 worklist = new Values();
451 depth = 0;
452 }
453
454 public:
455 static void compute(BlockList* blocks) {
456 UseCountComputer ucc;
457 blocks->iterate_backward(&ucc);
458 }
459 };
460
461
462 // helper macro for short definition of trace-output inside code
463 #ifndef PRODUCT
464 #define TRACE_LINEAR_SCAN(level, code) \
465 if (TraceLinearScanLevel >= level) { \
466 code; \
467 }
468 #else
469 #define TRACE_LINEAR_SCAN(level, code)
470 #endif
471
472 class ComputeLinearScanOrder : public StackObj {
473 private:
474 int _max_block_id; // the highest block_id of a block
475 int _num_blocks; // total number of blocks (smaller than _max_block_id)
476 int _num_loops; // total number of loops
477 bool _iterative_dominators;// method requires iterative computation of dominatiors
478
479 BlockList* _linear_scan_order; // the resulting list of blocks in correct order
480
481 BitMap _visited_blocks; // used for recursive processing of blocks
482 BitMap _active_blocks; // used for recursive processing of blocks
483 BitMap _dominator_blocks; // temproary BitMap used for computation of dominator
484 intArray _forward_branches; // number of incoming forward branches for each block
485 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges
486 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop
487 BlockList _work_list; // temporary list (used in mark_loops and compute_order)
488
489 Compilation* _compilation;
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 Compilation* compilation() const { return _compilation; }
534 public:
535 ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block);
536
537 // accessors for final result
538 BlockList* linear_scan_order() const { return _linear_scan_order; }
539 int num_loops() const { return _num_loops; }
540 };
541
542
543 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) :
544 _max_block_id(BlockBegin::number_of_blocks()),
545 _num_blocks(0),
546 _num_loops(0),
547 _iterative_dominators(false),
548 _visited_blocks(_max_block_id),
549 _active_blocks(_max_block_id),
550 _dominator_blocks(_max_block_id),
551 _forward_branches(_max_block_id, 0),
552 _loop_end_blocks(8),
553 _work_list(8),
554 _linear_scan_order(NULL), // initialized later with correct size
555 _loop_map(0, 0), // initialized later with correct size
556 _compilation(c)
557 {
558 TRACE_LINEAR_SCAN(2, "***** computing linear-scan block order");
559
560 init_visited();
561 count_edges(start_block, NULL);
562
563 if (compilation()->is_profiling()) {
564 compilation()->method()->method_data()->set_compilation_stats(_num_loops, _num_blocks);
565 }
566
567 if (_num_loops > 0) {
568 mark_loops();
569 clear_non_natural_loops(start_block);
570 assign_loop_depth(start_block);
571 }
572
573 compute_order(start_block);
574 compute_dominators();
575
576 NOT_PRODUCT(print_blocks());
577 DEBUG_ONLY(verify());
578 }
579
580
581 // Traverse the CFG:
582 // * count total number of blocks
583 // * count all incoming edges and backward incoming edges
584 // * number loop header blocks
585 // * create a list with all loop end blocks
586 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
587 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));
588 assert(cur->dominator() == NULL, "dominator already initialized");
589
590 if (is_active(cur)) {
591 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
592 assert(is_visited(cur), "block must be visisted when block is active");
593 assert(parent != NULL, "must have parent");
594
595 cur->set(BlockBegin::linear_scan_loop_header_flag);
596 cur->set(BlockBegin::backward_branch_target_flag);
597
598 parent->set(BlockBegin::linear_scan_loop_end_flag);
599
600 // When a loop header is also the start of an exception handler, then the backward branch is
601 // an exception edge. Because such edges are usually critical edges which cannot be split, the
602 // loop must be excluded here from processing.
603 if (cur->is_set(BlockBegin::exception_entry_flag)) {
604 // Make sure that dominators are correct in this weird situation
605 _iterative_dominators = true;
606 return;
607 }
608 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
609 "loop end blocks must have one successor (critical edges are split)");
610
611 _loop_end_blocks.append(parent);
612 return;
613 }
614
615 // increment number of incoming forward branches
616 inc_forward_branches(cur);
617
618 if (is_visited(cur)) {
619 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
620 return;
621 }
622
623 _num_blocks++;
624 set_visited(cur);
625 set_active(cur);
626
627 // recursive call for all successors
628 int i;
629 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
630 count_edges(cur->sux_at(i), cur);
631 }
632 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
633 count_edges(cur->exception_handler_at(i), cur);
634 }
635
636 clear_active(cur);
637
638 // Each loop has a unique number.
639 // When multiple loops are nested, assign_loop_depth assumes that the
640 // innermost loop has the lowest number. This is guaranteed by setting
641 // the loop number after the recursive calls for the successors above
642 // have returned.
643 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
644 assert(cur->loop_index() == -1, "cannot set loop-index twice");
645 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
646
647 cur->set_loop_index(_num_loops);
648 _num_loops++;
649 }
650
651 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
652 }
653
654
655 void ComputeLinearScanOrder::mark_loops() {
656 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
657
658 _loop_map = BitMap2D(_num_loops, _max_block_id);
659 _loop_map.clear();
660
661 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
662 BlockBegin* loop_end = _loop_end_blocks.at(i);
663 BlockBegin* loop_start = loop_end->sux_at(0);
664 int loop_idx = loop_start->loop_index();
665
666 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));
667 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
668 assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
669 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
670 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
671 assert(_work_list.is_empty(), "work list must be empty before processing");
672
673 // add the end-block of the loop to the working list
674 _work_list.push(loop_end);
675 set_block_in_loop(loop_idx, loop_end);
676 do {
677 BlockBegin* cur = _work_list.pop();
678
679 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id()));
680 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
681
682 // recursive processing of all predecessors ends when start block of loop is reached
683 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
684 for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
685 BlockBegin* pred = cur->pred_at(j);
686
687 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
688 // this predecessor has not been processed yet, so add it to work list
689 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id()));
690 _work_list.push(pred);
691 set_block_in_loop(loop_idx, pred);
692 }
693 }
694 }
695 } while (!_work_list.is_empty());
696 }
697 }
698
699
700 // check for non-natural loops (loops where the loop header does not dominate
701 // all other loop blocks = loops with mulitple entries).
702 // such loops are ignored
703 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
704 for (int i = _num_loops - 1; i >= 0; i--) {
705 if (is_block_in_loop(i, start_block)) {
706 // loop i contains the entry block of the method
707 // -> this is not a natural loop, so ignore it
708 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
709
710 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
711 clear_block_in_loop(i, block_id);
712 }
713 _iterative_dominators = true;
714 }
715 }
716 }
717
718 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
719 TRACE_LINEAR_SCAN(3, "----- computing loop-depth and weight");
720 init_visited();
721
722 assert(_work_list.is_empty(), "work list must be empty before processing");
723 _work_list.append(start_block);
724
725 do {
726 BlockBegin* cur = _work_list.pop();
727
728 if (!is_visited(cur)) {
729 set_visited(cur);
730 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
731
732 // compute loop-depth and loop-index for the block
733 assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
734 int i;
735 int loop_depth = 0;
736 int min_loop_idx = -1;
737 for (i = _num_loops - 1; i >= 0; i--) {
738 if (is_block_in_loop(i, cur)) {
739 loop_depth++;
740 min_loop_idx = i;
741 }
742 }
743 cur->set_loop_depth(loop_depth);
744 cur->set_loop_index(min_loop_idx);
745
746 // append all unvisited successors to work list
747 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
748 _work_list.append(cur->sux_at(i));
749 }
750 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
751 _work_list.append(cur->exception_handler_at(i));
752 }
753 }
754 } while (!_work_list.is_empty());
755 }
756
757
758 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
759 assert(a != NULL && b != NULL, "must have input blocks");
760
761 _dominator_blocks.clear();
762 while (a != NULL) {
763 _dominator_blocks.set_bit(a->block_id());
764 assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
765 a = a->dominator();
766 }
767 while (b != NULL && !_dominator_blocks.at(b->block_id())) {
768 assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
769 b = b->dominator();
770 }
771
772 assert(b != NULL, "could not find dominator");
773 return b;
774 }
775
776 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
777 if (cur->dominator() == NULL) {
778 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
779 cur->set_dominator(parent);
780
781 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
782 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()));
783 assert(cur->number_of_preds() > 1, "");
784 cur->set_dominator(common_dominator(cur->dominator(), parent));
785 }
786 }
787
788
789 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
790 BlockBegin* single_sux = NULL;
791 if (cur->number_of_sux() == 1) {
792 single_sux = cur->sux_at(0);
793 }
794
795 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
796 int weight = (cur->loop_depth() & 0x7FFF) << 16;
797
798 // general macro for short definition of weight flags
799 // the first instance of INC_WEIGHT_IF has the highest priority
800 int cur_bit = 15;
801 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
802
803 // this is necessery for the (very rare) case that two successing blocks have
804 // the same loop depth, but a different loop index (can happen for endless loops
805 // with exception handlers)
806 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
807
808 // loop end blocks (blocks that end with a backward branch) are added
809 // after all other blocks of the loop.
810 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
811
812 // critical edge split blocks are prefered because than they have a bigger
813 // proability to be completely empty
814 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
815
816 // exceptions should not be thrown in normal control flow, so these blocks
817 // are added as late as possible
818 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL));
819 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
820
821 // exceptions handlers are added as late as possible
822 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
823
824 // guarantee that weight is > 0
825 weight |= 1;
826
827 #undef INC_WEIGHT_IF
828 assert(cur_bit >= 0, "too many flags");
829 assert(weight > 0, "weight cannot become negative");
830
831 return weight;
832 }
833
834 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
835 // Discount the edge just traveled.
836 // When the number drops to zero, all forward branches were processed
837 if (dec_forward_branches(cur) != 0) {
838 return false;
839 }
840
841 assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
842 assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
843 return true;
844 }
845
846 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
847 assert(_work_list.index_of(cur) == -1, "block already in work list");
848
849 int cur_weight = compute_weight(cur);
850
851 // the linear_scan_number is used to cache the weight of a block
852 cur->set_linear_scan_number(cur_weight);
853
854 #ifndef PRODUCT
855 if (StressLinearScan) {
856 _work_list.insert_before(0, cur);
857 return;
858 }
859 #endif
860
861 _work_list.append(NULL); // provide space for new element
862
863 int insert_idx = _work_list.length() - 1;
864 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
865 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
866 insert_idx--;
867 }
868 _work_list.at_put(insert_idx, cur);
869
870 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
871 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()));
872
873 #ifdef ASSERT
874 for (int i = 0; i < _work_list.length(); i++) {
875 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
876 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
877 }
878 #endif
879 }
880
881 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
882 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()));
883 assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
884
885 // currently, the linear scan order and code emit order are equal.
886 // therefore the linear_scan_number and the weight of a block must also
887 // be equal.
888 cur->set_linear_scan_number(_linear_scan_order->length());
889 _linear_scan_order->append(cur);
890 }
891
892 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
893 TRACE_LINEAR_SCAN(3, "----- computing final block order");
894
895 // the start block is always the first block in the linear scan order
896 _linear_scan_order = new BlockList(_num_blocks);
897 append_block(start_block);
898
899 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
900 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
901 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
902
903 BlockBegin* sux_of_osr_entry = NULL;
904 if (osr_entry != NULL) {
905 // special handling for osr entry:
906 // ignore the edge between the osr entry and its successor for processing
907 // the osr entry block is added manually below
908 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
909 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");
910
911 sux_of_osr_entry = osr_entry->sux_at(0);
912 dec_forward_branches(sux_of_osr_entry);
913
914 compute_dominator(osr_entry, start_block);
915 _iterative_dominators = true;
916 }
917 compute_dominator(std_entry, start_block);
918
919 // start processing with standard entry block
920 assert(_work_list.is_empty(), "list must be empty before processing");
921
922 if (ready_for_processing(std_entry)) {
923 sort_into_work_list(std_entry);
924 } else {
925 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
926 }
927
928 do {
929 BlockBegin* cur = _work_list.pop();
930
931 if (cur == sux_of_osr_entry) {
932 // the osr entry block is ignored in normal processing, it is never added to the
933 // work list. Instead, it is added as late as possible manually here.
934 append_block(osr_entry);
935 compute_dominator(cur, osr_entry);
936 }
937 append_block(cur);
938
939 int i;
940 int num_sux = cur->number_of_sux();
941 // changed loop order to get "intuitive" order of if- and else-blocks
942 for (i = 0; i < num_sux; i++) {
943 BlockBegin* sux = cur->sux_at(i);
944 compute_dominator(sux, cur);
945 if (ready_for_processing(sux)) {
946 sort_into_work_list(sux);
947 }
948 }
949 num_sux = cur->number_of_exception_handlers();
950 for (i = 0; i < num_sux; i++) {
951 BlockBegin* sux = cur->exception_handler_at(i);
952 compute_dominator(sux, cur);
953 if (ready_for_processing(sux)) {
954 sort_into_work_list(sux);
955 }
956 }
957 } while (_work_list.length() > 0);
958 }
959
960
961 bool ComputeLinearScanOrder::compute_dominators_iter() {
962 bool changed = false;
963 int num_blocks = _linear_scan_order->length();
964
965 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
966 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
967 for (int i = 1; i < num_blocks; i++) {
968 BlockBegin* block = _linear_scan_order->at(i);
969
970 BlockBegin* dominator = block->pred_at(0);
971 int num_preds = block->number_of_preds();
972 for (int i = 1; i < num_preds; i++) {
973 dominator = common_dominator(dominator, block->pred_at(i));
974 }
975
976 if (dominator != block->dominator()) {
977 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()));
978
979 block->set_dominator(dominator);
980 changed = true;
981 }
982 }
983 return changed;
984 }
985
986 void ComputeLinearScanOrder::compute_dominators() {
987 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
988
989 // iterative computation of dominators is only required for methods with non-natural loops
990 // and OSR-methods. For all other methods, the dominators computed when generating the
991 // linear scan block order are correct.
992 if (_iterative_dominators) {
993 do {
994 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
995 } while (compute_dominators_iter());
996 }
997
998 // check that dominators are correct
999 assert(!compute_dominators_iter(), "fix point not reached");
1000 }
1001
1002
1003 #ifndef PRODUCT
1004 void ComputeLinearScanOrder::print_blocks() {
1005 if (TraceLinearScanLevel >= 2) {
1006 tty->print_cr("----- loop information:");
1007 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1008 BlockBegin* cur = _linear_scan_order->at(block_idx);
1009
1010 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
1011 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1012 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
1013 }
1014 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
1015 }
1016 }
1017
1018 if (TraceLinearScanLevel >= 1) {
1019 tty->print_cr("----- linear-scan block order:");
1020 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1021 BlockBegin* cur = _linear_scan_order->at(block_idx);
1022 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
1023
1024 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
1025 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
1026 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
1027 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
1028
1029 if (cur->dominator() != NULL) {
1030 tty->print(" dom: B%d ", cur->dominator()->block_id());
1031 } else {
1032 tty->print(" dom: NULL ");
1033 }
1034
1035 if (cur->number_of_preds() > 0) {
1036 tty->print(" preds: ");
1037 for (int j = 0; j < cur->number_of_preds(); j++) {
1038 BlockBegin* pred = cur->pred_at(j);
1039 tty->print("B%d ", pred->block_id());
1040 }
1041 }
1042 if (cur->number_of_sux() > 0) {
1043 tty->print(" sux: ");
1044 for (int j = 0; j < cur->number_of_sux(); j++) {
1045 BlockBegin* sux = cur->sux_at(j);
1046 tty->print("B%d ", sux->block_id());
1047 }
1048 }
1049 if (cur->number_of_exception_handlers() > 0) {
1050 tty->print(" ex: ");
1051 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1052 BlockBegin* ex = cur->exception_handler_at(j);
1053 tty->print("B%d ", ex->block_id());
1054 }
1055 }
1056 tty->cr();
1057 }
1058 }
1059 }
1060 #endif
1061
1062 #ifdef ASSERT
1063 void ComputeLinearScanOrder::verify() {
1064 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1065
1066 if (StressLinearScan) {
1067 // blocks are scrambled when StressLinearScan is used
1068 return;
1069 }
1070
1071 // check that all successors of a block have a higher linear-scan-number
1072 // and that all predecessors of a block have a lower linear-scan-number
1073 // (only backward branches of loops are ignored)
1074 int i;
1075 for (i = 0; i < _linear_scan_order->length(); i++) {
1076 BlockBegin* cur = _linear_scan_order->at(i);
1077
1078 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1079 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
1080
1081 int j;
1082 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1083 BlockBegin* sux = cur->sux_at(j);
1084
1085 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
1086 if (!cur->is_set(BlockBegin::linear_scan_loop_end_flag)) {
1087 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1088 }
1089 if (cur->loop_depth() == sux->loop_depth()) {
1090 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");
1091 }
1092 }
1093
1094 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1095 BlockBegin* pred = cur->pred_at(j);
1096
1097 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
1098 if (!cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
1099 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1100 }
1101 if (cur->loop_depth() == pred->loop_depth()) {
1102 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");
1103 }
1104
1105 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1106 }
1107
1108 // check dominator
1109 if (i == 0) {
1110 assert(cur->dominator() == NULL, "first block has no dominator");
1111 } else {
1112 assert(cur->dominator() != NULL, "all but first block must have dominator");
1113 }
1114 assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0), "Single predecessor must also be dominator");
1115 }
1116
1117 // check that all loops are continuous
1118 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1119 int block_idx = 0;
1120 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1121
1122 // skip blocks before the loop
1123 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1124 block_idx++;
1125 }
1126 // skip blocks of loop
1127 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1128 block_idx++;
1129 }
1130 // after the first non-loop block, there must not be another loop-block
1131 while (block_idx < _num_blocks) {
1132 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1133 block_idx++;
1134 }
1135 }
1136 }
1137 #endif
1138
1139
1140 void IR::compute_code() {
1141 assert(is_valid(), "IR must be valid");
1142
1143 ComputeLinearScanOrder compute_order(compilation(), start());
1144 _num_loops = compute_order.num_loops();
1145 _code = compute_order.linear_scan_order();
1146 }
1147
1148
1149 void IR::compute_use_counts() {
1150 // make sure all values coming out of this block get evaluated.
1151 int num_blocks = _code->length();
1152 for (int i = 0; i < num_blocks; i++) {
1153 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1154 }
1155
1156 // compute use counts
1157 UseCountComputer::compute(_code);
1158 }
1159
1160
1161 void IR::iterate_preorder(BlockClosure* closure) {
1162 assert(is_valid(), "IR must be valid");
1163 start()->iterate_preorder(closure);
1164 }
1165
1166
1167 void IR::iterate_postorder(BlockClosure* closure) {
1168 assert(is_valid(), "IR must be valid");
1169 start()->iterate_postorder(closure);
1170 }
1171
1172 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1173 linear_scan_order()->iterate_forward(closure);
1174 }
1175
1176
1177 #ifndef PRODUCT
1178 class BlockPrinter: public BlockClosure {
1179 private:
1180 InstructionPrinter* _ip;
1181 bool _cfg_only;
1182 bool _live_only;
1183
1184 public:
1185 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1186 _ip = ip;
1187 _cfg_only = cfg_only;
1188 _live_only = live_only;
1189 }
1190
1191 virtual void block_do(BlockBegin* block) {
1192 if (_cfg_only) {
1193 _ip->print_instr(block); tty->cr();
1194 } else {
1195 block->print_block(*_ip, _live_only);
1196 }
1197 }
1198 };
1199
1200
1201 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1202 ttyLocker ttyl;
1203 InstructionPrinter ip(!cfg_only);
1204 BlockPrinter bp(&ip, cfg_only, live_only);
1205 start->iterate_preorder(&bp);
1206 tty->cr();
1207 }
1208
1209 void IR::print(bool cfg_only, bool live_only) {
1210 if (is_valid()) {
1211 print(start(), cfg_only, live_only);
1212 } else {
1213 tty->print_cr("invalid IR");
1214 }
1215 }
1216
1217
1218 define_array(BlockListArray, BlockList*)
1219 define_stack(BlockListList, BlockListArray)
1220
1221 class PredecessorValidator : public BlockClosure {
1222 private:
1223 BlockListList* _predecessors;
1224 BlockList* _blocks;
1225
1226 static int cmp(BlockBegin** a, BlockBegin** b) {
1227 return (*a)->block_id() - (*b)->block_id();
1228 }
1229
1230 public:
1231 PredecessorValidator(IR* hir) {
1232 ResourceMark rm;
1233 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
1234 _blocks = new BlockList();
1235
1236 int i;
1237 hir->start()->iterate_preorder(this);
1238 if (hir->code() != NULL) {
1239 assert(hir->code()->length() == _blocks->length(), "must match");
1240 for (i = 0; i < _blocks->length(); i++) {
1241 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1242 }
1243 }
1244
1245 for (i = 0; i < _blocks->length(); i++) {
1246 BlockBegin* block = _blocks->at(i);
1247 BlockList* preds = _predecessors->at(block->block_id());
1248 if (preds == NULL) {
1249 assert(block->number_of_preds() == 0, "should be the same");
1250 continue;
1251 }
1252
1253 // clone the pred list so we can mutate it
1254 BlockList* pred_copy = new BlockList();
1255 int j;
1256 for (j = 0; j < block->number_of_preds(); j++) {
1257 pred_copy->append(block->pred_at(j));
1258 }
1259 // sort them in the same order
1260 preds->sort(cmp);
1261 pred_copy->sort(cmp);
1262 int length = MIN2(preds->length(), block->number_of_preds());
1263 for (j = 0; j < block->number_of_preds(); j++) {
1264 assert(preds->at(j) == pred_copy->at(j), "must match");
1265 }
1266
1267 assert(preds->length() == block->number_of_preds(), "should be the same");
1268 }
1269 }
1270
1271 virtual void block_do(BlockBegin* block) {
1272 _blocks->append(block);
1273 BlockEnd* be = block->end();
1274 int n = be->number_of_sux();
1275 int i;
1276 for (i = 0; i < n; i++) {
1277 BlockBegin* sux = be->sux_at(i);
1278 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1279
1280 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1281 if (preds == NULL) {
1282 preds = new BlockList();
1283 _predecessors->at_put(sux->block_id(), preds);
1284 }
1285 preds->append(block);
1286 }
1287
1288 n = block->number_of_exception_handlers();
1289 for (i = 0; i < n; i++) {
1290 BlockBegin* sux = block->exception_handler_at(i);
1291 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1292
1293 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1294 if (preds == NULL) {
1295 preds = new BlockList();
1296 _predecessors->at_put(sux->block_id(), preds);
1297 }
1298 preds->append(block);
1299 }
1300 }
1301 };
1302
1303 void IR::verify() {
1304 #ifdef ASSERT
1305 PredecessorValidator pv(this);
1306 #endif
1307 }
1308
1309 #endif // PRODUCT
1310
1311 void SubstitutionResolver::visit(Value* v) {
1312 Value v0 = *v;
1313 if (v0) {
1314 Value vs = v0->subst();
1315 if (vs != v0) {
1316 *v = v0->subst();
1317 }
1318 }
1319 }
1320
1321 #ifdef ASSERT
1322 class SubstitutionChecker: public ValueVisitor {
1323 void visit(Value* v) {
1324 Value v0 = *v;
1325 if (v0) {
1326 Value vs = v0->subst();
1327 assert(vs == v0, "missed substitution");
1328 }
1329 }
1330 };
1331 #endif
1332
1333
1334 void SubstitutionResolver::block_do(BlockBegin* block) {
1335 Instruction* last = NULL;
1336 for (Instruction* n = block; n != NULL;) {
1337 n->values_do(this);
1338 // need to remove this instruction from the instruction stream
1339 if (n->subst() != n) {
1340 assert(last != NULL, "must have last");
1341 last->set_next(n->next(), n->next()->bci());
1342 } else {
1343 last = n;
1344 }
1345 n = last->next();
1346 }
1347
1348 #ifdef ASSERT
1349 SubstitutionChecker check_substitute;
1350 if (block->state()) block->state()->values_do(&check_substitute);
1351 block->block_values_do(&check_substitute);
1352 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
1353 #endif
1354 }