Tue, 21 Feb 2012 13:14:55 -0500
7120481: storeStore barrier in constructor with final field
Summary: Issue storestore barrier before constructor return if the constructor write final field.
Reviewed-by: dholmes, jrose, roland, coleenp
Contributed-by: Jiangli Zhou <jiangli.zhou@oracle.com>
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 */
25 #include "precompiled.hpp"
26 #include "c1/c1_Compilation.hpp"
27 #include "c1/c1_FrameMap.hpp"
28 #include "c1/c1_GraphBuilder.hpp"
29 #include "c1/c1_IR.hpp"
30 #include "c1/c1_InstructionPrinter.hpp"
31 #include "c1/c1_Optimizer.hpp"
32 #include "utilities/bitMap.inline.hpp"
35 // Implementation of XHandlers
36 //
37 // Note: This code could eventually go away if we are
38 // just using the ciExceptionHandlerStream.
40 XHandlers::XHandlers(ciMethod* method) : _list(method->exception_table_length()) {
41 ciExceptionHandlerStream s(method);
42 while (!s.is_done()) {
43 _list.append(new XHandler(s.handler()));
44 s.next();
45 }
46 assert(s.count() == method->exception_table_length(), "exception table lengths inconsistent");
47 }
49 // deep copy of all XHandler contained in list
50 XHandlers::XHandlers(XHandlers* other) :
51 _list(other->length())
52 {
53 for (int i = 0; i < other->length(); i++) {
54 _list.append(new XHandler(other->handler_at(i)));
55 }
56 }
58 // Returns whether a particular exception type can be caught. Also
59 // returns true if klass is unloaded or any exception handler
60 // classes are unloaded. type_is_exact indicates whether the throw
61 // is known to be exactly that class or it might throw a subtype.
62 bool XHandlers::could_catch(ciInstanceKlass* klass, bool type_is_exact) const {
63 // the type is unknown so be conservative
64 if (!klass->is_loaded()) {
65 return true;
66 }
68 for (int i = 0; i < length(); i++) {
69 XHandler* handler = handler_at(i);
70 if (handler->is_catch_all()) {
71 // catch of ANY
72 return true;
73 }
74 ciInstanceKlass* handler_klass = handler->catch_klass();
75 // if it's unknown it might be catchable
76 if (!handler_klass->is_loaded()) {
77 return true;
78 }
79 // if the throw type is definitely a subtype of the catch type
80 // then it can be caught.
81 if (klass->is_subtype_of(handler_klass)) {
82 return true;
83 }
84 if (!type_is_exact) {
85 // If the type isn't exactly known then it can also be caught by
86 // catch statements where the inexact type is a subtype of the
87 // catch type.
88 // given: foo extends bar extends Exception
89 // throw bar can be caught by catch foo, catch bar, and catch
90 // Exception, however it can't be caught by any handlers without
91 // bar in its type hierarchy.
92 if (handler_klass->is_subtype_of(klass)) {
93 return true;
94 }
95 }
96 }
98 return false;
99 }
102 bool XHandlers::equals(XHandlers* others) const {
103 if (others == NULL) return false;
104 if (length() != others->length()) return false;
106 for (int i = 0; i < length(); i++) {
107 if (!handler_at(i)->equals(others->handler_at(i))) return false;
108 }
109 return true;
110 }
112 bool XHandler::equals(XHandler* other) const {
113 assert(entry_pco() != -1 && other->entry_pco() != -1, "must have entry_pco");
115 if (entry_pco() != other->entry_pco()) return false;
116 if (scope_count() != other->scope_count()) return false;
117 if (_desc != other->_desc) return false;
119 assert(entry_block() == other->entry_block(), "entry_block must be equal when entry_pco is equal");
120 return true;
121 }
124 // Implementation of IRScope
125 BlockBegin* IRScope::build_graph(Compilation* compilation, int osr_bci) {
126 GraphBuilder gm(compilation, this);
127 NOT_PRODUCT(if (PrintValueNumbering && Verbose) gm.print_stats());
128 if (compilation->bailed_out()) return NULL;
129 return gm.start();
130 }
133 IRScope::IRScope(Compilation* compilation, IRScope* caller, int caller_bci, ciMethod* method, int osr_bci, bool create_graph)
134 : _callees(2)
135 , _compilation(compilation)
136 , _requires_phi_function(method->max_locals())
137 {
138 _caller = caller;
139 _level = caller == NULL ? 0 : caller->level() + 1;
140 _method = method;
141 _xhandlers = new XHandlers(method);
142 _number_of_locks = 0;
143 _monitor_pairing_ok = method->has_balanced_monitors();
144 _wrote_final = false;
145 _start = NULL;
147 if (osr_bci == -1) {
148 _requires_phi_function.clear();
149 } else {
150 // selective creation of phi functions is not possibel in osr-methods
151 _requires_phi_function.set_range(0, method->max_locals());
152 }
154 assert(method->holder()->is_loaded() , "method holder must be loaded");
156 // build graph if monitor pairing is ok
157 if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci);
158 }
161 int IRScope::max_stack() const {
162 int my_max = method()->max_stack();
163 int callee_max = 0;
164 for (int i = 0; i < number_of_callees(); i++) {
165 callee_max = MAX2(callee_max, callee_no(i)->max_stack());
166 }
167 return my_max + callee_max;
168 }
171 bool IRScopeDebugInfo::should_reexecute() {
172 ciMethod* cur_method = scope()->method();
173 int cur_bci = bci();
174 if (cur_method != NULL && cur_bci != SynchronizationEntryBCI) {
175 Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci);
176 return Interpreter::bytecode_should_reexecute(code);
177 } else
178 return false;
179 }
182 // Implementation of CodeEmitInfo
184 // Stack must be NON-null
185 CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers)
186 : _scope(stack->scope())
187 , _scope_debug_info(NULL)
188 , _oop_map(NULL)
189 , _stack(stack)
190 , _exception_handlers(exception_handlers)
191 , _is_method_handle_invoke(false) {
192 assert(_stack != NULL, "must be non null");
193 }
196 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack)
197 : _scope(info->_scope)
198 , _exception_handlers(NULL)
199 , _scope_debug_info(NULL)
200 , _oop_map(NULL)
201 , _stack(stack == NULL ? info->_stack : stack)
202 , _is_method_handle_invoke(info->_is_method_handle_invoke) {
204 // deep copy of exception handlers
205 if (info->_exception_handlers != NULL) {
206 _exception_handlers = new XHandlers(info->_exception_handlers);
207 }
208 }
211 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) {
212 // record the safepoint before recording the debug info for enclosing scopes
213 recorder->add_safepoint(pc_offset, _oop_map->deep_copy());
214 _scope_debug_info->record_debug_info(recorder, pc_offset, true/*topmost*/, _is_method_handle_invoke);
215 recorder->end_safepoint(pc_offset);
216 }
219 void CodeEmitInfo::add_register_oop(LIR_Opr opr) {
220 assert(_oop_map != NULL, "oop map must already exist");
221 assert(opr->is_single_cpu(), "should not call otherwise");
223 VMReg name = frame_map()->regname(opr);
224 _oop_map->set_oop(name);
225 }
230 // Implementation of IR
232 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) :
233 _locals_size(in_WordSize(-1))
234 , _num_loops(0) {
235 // setup IR fields
236 _compilation = compilation;
237 _top_scope = new IRScope(compilation, NULL, -1, method, osr_bci, true);
238 _code = NULL;
239 }
242 void IR::optimize() {
243 Optimizer opt(this);
244 if (!compilation()->profile_branches()) {
245 if (DoCEE) {
246 opt.eliminate_conditional_expressions();
247 #ifndef PRODUCT
248 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
249 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
250 #endif
251 }
252 if (EliminateBlocks) {
253 opt.eliminate_blocks();
254 #ifndef PRODUCT
255 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
256 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
257 #endif
258 }
259 }
260 if (EliminateNullChecks) {
261 opt.eliminate_null_checks();
262 #ifndef PRODUCT
263 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
264 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
265 #endif
266 }
267 }
270 static int sort_pairs(BlockPair** a, BlockPair** b) {
271 if ((*a)->from() == (*b)->from()) {
272 return (*a)->to()->block_id() - (*b)->to()->block_id();
273 } else {
274 return (*a)->from()->block_id() - (*b)->from()->block_id();
275 }
276 }
279 class CriticalEdgeFinder: public BlockClosure {
280 BlockPairList blocks;
281 IR* _ir;
283 public:
284 CriticalEdgeFinder(IR* ir): _ir(ir) {}
285 void block_do(BlockBegin* bb) {
286 BlockEnd* be = bb->end();
287 int nos = be->number_of_sux();
288 if (nos >= 2) {
289 for (int i = 0; i < nos; i++) {
290 BlockBegin* sux = be->sux_at(i);
291 if (sux->number_of_preds() >= 2) {
292 blocks.append(new BlockPair(bb, sux));
293 }
294 }
295 }
296 }
298 void split_edges() {
299 BlockPair* last_pair = NULL;
300 blocks.sort(sort_pairs);
301 for (int i = 0; i < blocks.length(); i++) {
302 BlockPair* pair = blocks.at(i);
303 if (last_pair != NULL && pair->is_same(last_pair)) continue;
304 BlockBegin* from = pair->from();
305 BlockBegin* to = pair->to();
306 BlockBegin* split = from->insert_block_between(to);
307 #ifndef PRODUCT
308 if ((PrintIR || PrintIR1) && Verbose) {
309 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
310 from->block_id(), to->block_id(), split->block_id());
311 }
312 #endif
313 last_pair = pair;
314 }
315 }
316 };
318 void IR::split_critical_edges() {
319 CriticalEdgeFinder cef(this);
321 iterate_preorder(&cef);
322 cef.split_edges();
323 }
326 class UseCountComputer: public ValueVisitor, BlockClosure {
327 private:
328 void visit(Value* n) {
329 // Local instructions and Phis for expression stack values at the
330 // start of basic blocks are not added to the instruction list
331 if (!(*n)->is_linked() && (*n)->can_be_linked()) {
332 assert(false, "a node was not appended to the graph");
333 Compilation::current()->bailout("a node was not appended to the graph");
334 }
335 // use n's input if not visited before
336 if (!(*n)->is_pinned() && !(*n)->has_uses()) {
337 // note: a) if the instruction is pinned, it will be handled by compute_use_count
338 // b) if the instruction has uses, it was touched before
339 // => in both cases we don't need to update n's values
340 uses_do(n);
341 }
342 // use n
343 (*n)->_use_count++;
344 }
346 Values* worklist;
347 int depth;
348 enum {
349 max_recurse_depth = 20
350 };
352 void uses_do(Value* n) {
353 depth++;
354 if (depth > max_recurse_depth) {
355 // don't allow the traversal to recurse too deeply
356 worklist->push(*n);
357 } else {
358 (*n)->input_values_do(this);
359 // special handling for some instructions
360 if ((*n)->as_BlockEnd() != NULL) {
361 // note on BlockEnd:
362 // must 'use' the stack only if the method doesn't
363 // terminate, however, in those cases stack is empty
364 (*n)->state_values_do(this);
365 }
366 }
367 depth--;
368 }
370 void block_do(BlockBegin* b) {
371 depth = 0;
372 // process all pinned nodes as the roots of expression trees
373 for (Instruction* n = b; n != NULL; n = n->next()) {
374 if (n->is_pinned()) uses_do(&n);
375 }
376 assert(depth == 0, "should have counted back down");
378 // now process any unpinned nodes which recursed too deeply
379 while (worklist->length() > 0) {
380 Value t = worklist->pop();
381 if (!t->is_pinned()) {
382 // compute the use count
383 uses_do(&t);
385 // pin the instruction so that LIRGenerator doesn't recurse
386 // too deeply during it's evaluation.
387 t->pin();
388 }
389 }
390 assert(depth == 0, "should have counted back down");
391 }
393 UseCountComputer() {
394 worklist = new Values();
395 depth = 0;
396 }
398 public:
399 static void compute(BlockList* blocks) {
400 UseCountComputer ucc;
401 blocks->iterate_backward(&ucc);
402 }
403 };
406 // helper macro for short definition of trace-output inside code
407 #ifndef PRODUCT
408 #define TRACE_LINEAR_SCAN(level, code) \
409 if (TraceLinearScanLevel >= level) { \
410 code; \
411 }
412 #else
413 #define TRACE_LINEAR_SCAN(level, code)
414 #endif
416 class ComputeLinearScanOrder : public StackObj {
417 private:
418 int _max_block_id; // the highest block_id of a block
419 int _num_blocks; // total number of blocks (smaller than _max_block_id)
420 int _num_loops; // total number of loops
421 bool _iterative_dominators;// method requires iterative computation of dominatiors
423 BlockList* _linear_scan_order; // the resulting list of blocks in correct order
425 BitMap _visited_blocks; // used for recursive processing of blocks
426 BitMap _active_blocks; // used for recursive processing of blocks
427 BitMap _dominator_blocks; // temproary BitMap used for computation of dominator
428 intArray _forward_branches; // number of incoming forward branches for each block
429 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges
430 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop
431 BlockList _work_list; // temporary list (used in mark_loops and compute_order)
433 Compilation* _compilation;
435 // accessors for _visited_blocks and _active_blocks
436 void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); }
437 bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); }
438 bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); }
439 void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); }
440 void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); }
441 void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); }
443 // accessors for _forward_branches
444 void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); }
445 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()); }
447 // accessors for _loop_map
448 bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); }
449 void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); }
450 void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); }
452 // count edges between blocks
453 void count_edges(BlockBegin* cur, BlockBegin* parent);
455 // loop detection
456 void mark_loops();
457 void clear_non_natural_loops(BlockBegin* start_block);
458 void assign_loop_depth(BlockBegin* start_block);
460 // computation of final block order
461 BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b);
462 void compute_dominator(BlockBegin* cur, BlockBegin* parent);
463 int compute_weight(BlockBegin* cur);
464 bool ready_for_processing(BlockBegin* cur);
465 void sort_into_work_list(BlockBegin* b);
466 void append_block(BlockBegin* cur);
467 void compute_order(BlockBegin* start_block);
469 // fixup of dominators for non-natural loops
470 bool compute_dominators_iter();
471 void compute_dominators();
473 // debug functions
474 NOT_PRODUCT(void print_blocks();)
475 DEBUG_ONLY(void verify();)
477 Compilation* compilation() const { return _compilation; }
478 public:
479 ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block);
481 // accessors for final result
482 BlockList* linear_scan_order() const { return _linear_scan_order; }
483 int num_loops() const { return _num_loops; }
484 };
487 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) :
488 _max_block_id(BlockBegin::number_of_blocks()),
489 _num_blocks(0),
490 _num_loops(0),
491 _iterative_dominators(false),
492 _visited_blocks(_max_block_id),
493 _active_blocks(_max_block_id),
494 _dominator_blocks(_max_block_id),
495 _forward_branches(_max_block_id, 0),
496 _loop_end_blocks(8),
497 _work_list(8),
498 _linear_scan_order(NULL), // initialized later with correct size
499 _loop_map(0, 0), // initialized later with correct size
500 _compilation(c)
501 {
502 TRACE_LINEAR_SCAN(2, "***** computing linear-scan block order");
504 init_visited();
505 count_edges(start_block, NULL);
507 if (compilation()->is_profiling()) {
508 ciMethod *method = compilation()->method();
509 if (!method->is_accessor()) {
510 ciMethodData* md = method->method_data_or_null();
511 assert(md != NULL, "Sanity");
512 md->set_compilation_stats(_num_loops, _num_blocks);
513 }
514 }
516 if (_num_loops > 0) {
517 mark_loops();
518 clear_non_natural_loops(start_block);
519 assign_loop_depth(start_block);
520 }
522 compute_order(start_block);
523 compute_dominators();
525 NOT_PRODUCT(print_blocks());
526 DEBUG_ONLY(verify());
527 }
530 // Traverse the CFG:
531 // * count total number of blocks
532 // * count all incoming edges and backward incoming edges
533 // * number loop header blocks
534 // * create a list with all loop end blocks
535 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
536 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));
537 assert(cur->dominator() == NULL, "dominator already initialized");
539 if (is_active(cur)) {
540 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
541 assert(is_visited(cur), "block must be visisted when block is active");
542 assert(parent != NULL, "must have parent");
544 cur->set(BlockBegin::linear_scan_loop_header_flag);
545 cur->set(BlockBegin::backward_branch_target_flag);
547 parent->set(BlockBegin::linear_scan_loop_end_flag);
549 // When a loop header is also the start of an exception handler, then the backward branch is
550 // an exception edge. Because such edges are usually critical edges which cannot be split, the
551 // loop must be excluded here from processing.
552 if (cur->is_set(BlockBegin::exception_entry_flag)) {
553 // Make sure that dominators are correct in this weird situation
554 _iterative_dominators = true;
555 return;
556 }
557 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
558 "loop end blocks must have one successor (critical edges are split)");
560 _loop_end_blocks.append(parent);
561 return;
562 }
564 // increment number of incoming forward branches
565 inc_forward_branches(cur);
567 if (is_visited(cur)) {
568 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
569 return;
570 }
572 _num_blocks++;
573 set_visited(cur);
574 set_active(cur);
576 // recursive call for all successors
577 int i;
578 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
579 count_edges(cur->sux_at(i), cur);
580 }
581 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
582 count_edges(cur->exception_handler_at(i), cur);
583 }
585 clear_active(cur);
587 // Each loop has a unique number.
588 // When multiple loops are nested, assign_loop_depth assumes that the
589 // innermost loop has the lowest number. This is guaranteed by setting
590 // the loop number after the recursive calls for the successors above
591 // have returned.
592 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
593 assert(cur->loop_index() == -1, "cannot set loop-index twice");
594 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
596 cur->set_loop_index(_num_loops);
597 _num_loops++;
598 }
600 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
601 }
604 void ComputeLinearScanOrder::mark_loops() {
605 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
607 _loop_map = BitMap2D(_num_loops, _max_block_id);
608 _loop_map.clear();
610 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
611 BlockBegin* loop_end = _loop_end_blocks.at(i);
612 BlockBegin* loop_start = loop_end->sux_at(0);
613 int loop_idx = loop_start->loop_index();
615 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));
616 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
617 assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
618 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
619 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
620 assert(_work_list.is_empty(), "work list must be empty before processing");
622 // add the end-block of the loop to the working list
623 _work_list.push(loop_end);
624 set_block_in_loop(loop_idx, loop_end);
625 do {
626 BlockBegin* cur = _work_list.pop();
628 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id()));
629 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
631 // recursive processing of all predecessors ends when start block of loop is reached
632 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
633 for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
634 BlockBegin* pred = cur->pred_at(j);
636 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
637 // this predecessor has not been processed yet, so add it to work list
638 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id()));
639 _work_list.push(pred);
640 set_block_in_loop(loop_idx, pred);
641 }
642 }
643 }
644 } while (!_work_list.is_empty());
645 }
646 }
649 // check for non-natural loops (loops where the loop header does not dominate
650 // all other loop blocks = loops with mulitple entries).
651 // such loops are ignored
652 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
653 for (int i = _num_loops - 1; i >= 0; i--) {
654 if (is_block_in_loop(i, start_block)) {
655 // loop i contains the entry block of the method
656 // -> this is not a natural loop, so ignore it
657 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
659 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
660 clear_block_in_loop(i, block_id);
661 }
662 _iterative_dominators = true;
663 }
664 }
665 }
667 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
668 TRACE_LINEAR_SCAN(3, "----- computing loop-depth and weight");
669 init_visited();
671 assert(_work_list.is_empty(), "work list must be empty before processing");
672 _work_list.append(start_block);
674 do {
675 BlockBegin* cur = _work_list.pop();
677 if (!is_visited(cur)) {
678 set_visited(cur);
679 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
681 // compute loop-depth and loop-index for the block
682 assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
683 int i;
684 int loop_depth = 0;
685 int min_loop_idx = -1;
686 for (i = _num_loops - 1; i >= 0; i--) {
687 if (is_block_in_loop(i, cur)) {
688 loop_depth++;
689 min_loop_idx = i;
690 }
691 }
692 cur->set_loop_depth(loop_depth);
693 cur->set_loop_index(min_loop_idx);
695 // append all unvisited successors to work list
696 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
697 _work_list.append(cur->sux_at(i));
698 }
699 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
700 _work_list.append(cur->exception_handler_at(i));
701 }
702 }
703 } while (!_work_list.is_empty());
704 }
707 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
708 assert(a != NULL && b != NULL, "must have input blocks");
710 _dominator_blocks.clear();
711 while (a != NULL) {
712 _dominator_blocks.set_bit(a->block_id());
713 assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
714 a = a->dominator();
715 }
716 while (b != NULL && !_dominator_blocks.at(b->block_id())) {
717 assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
718 b = b->dominator();
719 }
721 assert(b != NULL, "could not find dominator");
722 return b;
723 }
725 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
726 if (cur->dominator() == NULL) {
727 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
728 cur->set_dominator(parent);
730 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
731 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()));
732 assert(cur->number_of_preds() > 1, "");
733 cur->set_dominator(common_dominator(cur->dominator(), parent));
734 }
735 }
738 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
739 BlockBegin* single_sux = NULL;
740 if (cur->number_of_sux() == 1) {
741 single_sux = cur->sux_at(0);
742 }
744 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
745 int weight = (cur->loop_depth() & 0x7FFF) << 16;
747 // general macro for short definition of weight flags
748 // the first instance of INC_WEIGHT_IF has the highest priority
749 int cur_bit = 15;
750 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
752 // this is necessery for the (very rare) case that two successing blocks have
753 // the same loop depth, but a different loop index (can happen for endless loops
754 // with exception handlers)
755 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
757 // loop end blocks (blocks that end with a backward branch) are added
758 // after all other blocks of the loop.
759 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
761 // critical edge split blocks are prefered because than they have a bigger
762 // proability to be completely empty
763 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
765 // exceptions should not be thrown in normal control flow, so these blocks
766 // are added as late as possible
767 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL));
768 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
770 // exceptions handlers are added as late as possible
771 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
773 // guarantee that weight is > 0
774 weight |= 1;
776 #undef INC_WEIGHT_IF
777 assert(cur_bit >= 0, "too many flags");
778 assert(weight > 0, "weight cannot become negative");
780 return weight;
781 }
783 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
784 // Discount the edge just traveled.
785 // When the number drops to zero, all forward branches were processed
786 if (dec_forward_branches(cur) != 0) {
787 return false;
788 }
790 assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
791 assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
792 return true;
793 }
795 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
796 assert(_work_list.index_of(cur) == -1, "block already in work list");
798 int cur_weight = compute_weight(cur);
800 // the linear_scan_number is used to cache the weight of a block
801 cur->set_linear_scan_number(cur_weight);
803 #ifndef PRODUCT
804 if (StressLinearScan) {
805 _work_list.insert_before(0, cur);
806 return;
807 }
808 #endif
810 _work_list.append(NULL); // provide space for new element
812 int insert_idx = _work_list.length() - 1;
813 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
814 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
815 insert_idx--;
816 }
817 _work_list.at_put(insert_idx, cur);
819 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
820 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()));
822 #ifdef ASSERT
823 for (int i = 0; i < _work_list.length(); i++) {
824 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
825 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
826 }
827 #endif
828 }
830 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
831 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()));
832 assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
834 // currently, the linear scan order and code emit order are equal.
835 // therefore the linear_scan_number and the weight of a block must also
836 // be equal.
837 cur->set_linear_scan_number(_linear_scan_order->length());
838 _linear_scan_order->append(cur);
839 }
841 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
842 TRACE_LINEAR_SCAN(3, "----- computing final block order");
844 // the start block is always the first block in the linear scan order
845 _linear_scan_order = new BlockList(_num_blocks);
846 append_block(start_block);
848 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
849 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
850 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
852 BlockBegin* sux_of_osr_entry = NULL;
853 if (osr_entry != NULL) {
854 // special handling for osr entry:
855 // ignore the edge between the osr entry and its successor for processing
856 // the osr entry block is added manually below
857 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
858 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");
860 sux_of_osr_entry = osr_entry->sux_at(0);
861 dec_forward_branches(sux_of_osr_entry);
863 compute_dominator(osr_entry, start_block);
864 _iterative_dominators = true;
865 }
866 compute_dominator(std_entry, start_block);
868 // start processing with standard entry block
869 assert(_work_list.is_empty(), "list must be empty before processing");
871 if (ready_for_processing(std_entry)) {
872 sort_into_work_list(std_entry);
873 } else {
874 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
875 }
877 do {
878 BlockBegin* cur = _work_list.pop();
880 if (cur == sux_of_osr_entry) {
881 // the osr entry block is ignored in normal processing, it is never added to the
882 // work list. Instead, it is added as late as possible manually here.
883 append_block(osr_entry);
884 compute_dominator(cur, osr_entry);
885 }
886 append_block(cur);
888 int i;
889 int num_sux = cur->number_of_sux();
890 // changed loop order to get "intuitive" order of if- and else-blocks
891 for (i = 0; i < num_sux; i++) {
892 BlockBegin* sux = cur->sux_at(i);
893 compute_dominator(sux, cur);
894 if (ready_for_processing(sux)) {
895 sort_into_work_list(sux);
896 }
897 }
898 num_sux = cur->number_of_exception_handlers();
899 for (i = 0; i < num_sux; i++) {
900 BlockBegin* sux = cur->exception_handler_at(i);
901 compute_dominator(sux, cur);
902 if (ready_for_processing(sux)) {
903 sort_into_work_list(sux);
904 }
905 }
906 } while (_work_list.length() > 0);
907 }
910 bool ComputeLinearScanOrder::compute_dominators_iter() {
911 bool changed = false;
912 int num_blocks = _linear_scan_order->length();
914 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
915 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
916 for (int i = 1; i < num_blocks; i++) {
917 BlockBegin* block = _linear_scan_order->at(i);
919 BlockBegin* dominator = block->pred_at(0);
920 int num_preds = block->number_of_preds();
921 for (int i = 1; i < num_preds; i++) {
922 dominator = common_dominator(dominator, block->pred_at(i));
923 }
925 if (dominator != block->dominator()) {
926 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()));
928 block->set_dominator(dominator);
929 changed = true;
930 }
931 }
932 return changed;
933 }
935 void ComputeLinearScanOrder::compute_dominators() {
936 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
938 // iterative computation of dominators is only required for methods with non-natural loops
939 // and OSR-methods. For all other methods, the dominators computed when generating the
940 // linear scan block order are correct.
941 if (_iterative_dominators) {
942 do {
943 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
944 } while (compute_dominators_iter());
945 }
947 // check that dominators are correct
948 assert(!compute_dominators_iter(), "fix point not reached");
949 }
952 #ifndef PRODUCT
953 void ComputeLinearScanOrder::print_blocks() {
954 if (TraceLinearScanLevel >= 2) {
955 tty->print_cr("----- loop information:");
956 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
957 BlockBegin* cur = _linear_scan_order->at(block_idx);
959 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
960 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
961 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
962 }
963 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
964 }
965 }
967 if (TraceLinearScanLevel >= 1) {
968 tty->print_cr("----- linear-scan block order:");
969 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
970 BlockBegin* cur = _linear_scan_order->at(block_idx);
971 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
973 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
974 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
975 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
976 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
978 if (cur->dominator() != NULL) {
979 tty->print(" dom: B%d ", cur->dominator()->block_id());
980 } else {
981 tty->print(" dom: NULL ");
982 }
984 if (cur->number_of_preds() > 0) {
985 tty->print(" preds: ");
986 for (int j = 0; j < cur->number_of_preds(); j++) {
987 BlockBegin* pred = cur->pred_at(j);
988 tty->print("B%d ", pred->block_id());
989 }
990 }
991 if (cur->number_of_sux() > 0) {
992 tty->print(" sux: ");
993 for (int j = 0; j < cur->number_of_sux(); j++) {
994 BlockBegin* sux = cur->sux_at(j);
995 tty->print("B%d ", sux->block_id());
996 }
997 }
998 if (cur->number_of_exception_handlers() > 0) {
999 tty->print(" ex: ");
1000 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1001 BlockBegin* ex = cur->exception_handler_at(j);
1002 tty->print("B%d ", ex->block_id());
1003 }
1004 }
1005 tty->cr();
1006 }
1007 }
1008 }
1009 #endif
1011 #ifdef ASSERT
1012 void ComputeLinearScanOrder::verify() {
1013 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1015 if (StressLinearScan) {
1016 // blocks are scrambled when StressLinearScan is used
1017 return;
1018 }
1020 // check that all successors of a block have a higher linear-scan-number
1021 // and that all predecessors of a block have a lower linear-scan-number
1022 // (only backward branches of loops are ignored)
1023 int i;
1024 for (i = 0; i < _linear_scan_order->length(); i++) {
1025 BlockBegin* cur = _linear_scan_order->at(i);
1027 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1028 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
1030 int j;
1031 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1032 BlockBegin* sux = cur->sux_at(j);
1034 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
1035 if (!cur->is_set(BlockBegin::linear_scan_loop_end_flag)) {
1036 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1037 }
1038 if (cur->loop_depth() == sux->loop_depth()) {
1039 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");
1040 }
1041 }
1043 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1044 BlockBegin* pred = cur->pred_at(j);
1046 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
1047 if (!cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
1048 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1049 }
1050 if (cur->loop_depth() == pred->loop_depth()) {
1051 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");
1052 }
1054 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1055 }
1057 // check dominator
1058 if (i == 0) {
1059 assert(cur->dominator() == NULL, "first block has no dominator");
1060 } else {
1061 assert(cur->dominator() != NULL, "all but first block must have dominator");
1062 }
1063 assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0), "Single predecessor must also be dominator");
1064 }
1066 // check that all loops are continuous
1067 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1068 int block_idx = 0;
1069 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1071 // skip blocks before the loop
1072 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1073 block_idx++;
1074 }
1075 // skip blocks of loop
1076 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1077 block_idx++;
1078 }
1079 // after the first non-loop block, there must not be another loop-block
1080 while (block_idx < _num_blocks) {
1081 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1082 block_idx++;
1083 }
1084 }
1085 }
1086 #endif
1089 void IR::compute_code() {
1090 assert(is_valid(), "IR must be valid");
1092 ComputeLinearScanOrder compute_order(compilation(), start());
1093 _num_loops = compute_order.num_loops();
1094 _code = compute_order.linear_scan_order();
1095 }
1098 void IR::compute_use_counts() {
1099 // make sure all values coming out of this block get evaluated.
1100 int num_blocks = _code->length();
1101 for (int i = 0; i < num_blocks; i++) {
1102 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1103 }
1105 // compute use counts
1106 UseCountComputer::compute(_code);
1107 }
1110 void IR::iterate_preorder(BlockClosure* closure) {
1111 assert(is_valid(), "IR must be valid");
1112 start()->iterate_preorder(closure);
1113 }
1116 void IR::iterate_postorder(BlockClosure* closure) {
1117 assert(is_valid(), "IR must be valid");
1118 start()->iterate_postorder(closure);
1119 }
1121 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1122 linear_scan_order()->iterate_forward(closure);
1123 }
1126 #ifndef PRODUCT
1127 class BlockPrinter: public BlockClosure {
1128 private:
1129 InstructionPrinter* _ip;
1130 bool _cfg_only;
1131 bool _live_only;
1133 public:
1134 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1135 _ip = ip;
1136 _cfg_only = cfg_only;
1137 _live_only = live_only;
1138 }
1140 virtual void block_do(BlockBegin* block) {
1141 if (_cfg_only) {
1142 _ip->print_instr(block); tty->cr();
1143 } else {
1144 block->print_block(*_ip, _live_only);
1145 }
1146 }
1147 };
1150 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1151 ttyLocker ttyl;
1152 InstructionPrinter ip(!cfg_only);
1153 BlockPrinter bp(&ip, cfg_only, live_only);
1154 start->iterate_preorder(&bp);
1155 tty->cr();
1156 }
1158 void IR::print(bool cfg_only, bool live_only) {
1159 if (is_valid()) {
1160 print(start(), cfg_only, live_only);
1161 } else {
1162 tty->print_cr("invalid IR");
1163 }
1164 }
1167 define_array(BlockListArray, BlockList*)
1168 define_stack(BlockListList, BlockListArray)
1170 class PredecessorValidator : public BlockClosure {
1171 private:
1172 BlockListList* _predecessors;
1173 BlockList* _blocks;
1175 static int cmp(BlockBegin** a, BlockBegin** b) {
1176 return (*a)->block_id() - (*b)->block_id();
1177 }
1179 public:
1180 PredecessorValidator(IR* hir) {
1181 ResourceMark rm;
1182 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
1183 _blocks = new BlockList();
1185 int i;
1186 hir->start()->iterate_preorder(this);
1187 if (hir->code() != NULL) {
1188 assert(hir->code()->length() == _blocks->length(), "must match");
1189 for (i = 0; i < _blocks->length(); i++) {
1190 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1191 }
1192 }
1194 for (i = 0; i < _blocks->length(); i++) {
1195 BlockBegin* block = _blocks->at(i);
1196 BlockList* preds = _predecessors->at(block->block_id());
1197 if (preds == NULL) {
1198 assert(block->number_of_preds() == 0, "should be the same");
1199 continue;
1200 }
1202 // clone the pred list so we can mutate it
1203 BlockList* pred_copy = new BlockList();
1204 int j;
1205 for (j = 0; j < block->number_of_preds(); j++) {
1206 pred_copy->append(block->pred_at(j));
1207 }
1208 // sort them in the same order
1209 preds->sort(cmp);
1210 pred_copy->sort(cmp);
1211 int length = MIN2(preds->length(), block->number_of_preds());
1212 for (j = 0; j < block->number_of_preds(); j++) {
1213 assert(preds->at(j) == pred_copy->at(j), "must match");
1214 }
1216 assert(preds->length() == block->number_of_preds(), "should be the same");
1217 }
1218 }
1220 virtual void block_do(BlockBegin* block) {
1221 _blocks->append(block);
1222 BlockEnd* be = block->end();
1223 int n = be->number_of_sux();
1224 int i;
1225 for (i = 0; i < n; i++) {
1226 BlockBegin* sux = be->sux_at(i);
1227 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1229 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1230 if (preds == NULL) {
1231 preds = new BlockList();
1232 _predecessors->at_put(sux->block_id(), preds);
1233 }
1234 preds->append(block);
1235 }
1237 n = block->number_of_exception_handlers();
1238 for (i = 0; i < n; i++) {
1239 BlockBegin* sux = block->exception_handler_at(i);
1240 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1242 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1243 if (preds == NULL) {
1244 preds = new BlockList();
1245 _predecessors->at_put(sux->block_id(), preds);
1246 }
1247 preds->append(block);
1248 }
1249 }
1250 };
1252 void IR::verify() {
1253 #ifdef ASSERT
1254 PredecessorValidator pv(this);
1255 #endif
1256 }
1258 #endif // PRODUCT
1260 void SubstitutionResolver::visit(Value* v) {
1261 Value v0 = *v;
1262 if (v0) {
1263 Value vs = v0->subst();
1264 if (vs != v0) {
1265 *v = v0->subst();
1266 }
1267 }
1268 }
1270 #ifdef ASSERT
1271 class SubstitutionChecker: public ValueVisitor {
1272 void visit(Value* v) {
1273 Value v0 = *v;
1274 if (v0) {
1275 Value vs = v0->subst();
1276 assert(vs == v0, "missed substitution");
1277 }
1278 }
1279 };
1280 #endif
1283 void SubstitutionResolver::block_do(BlockBegin* block) {
1284 Instruction* last = NULL;
1285 for (Instruction* n = block; n != NULL;) {
1286 n->values_do(this);
1287 // need to remove this instruction from the instruction stream
1288 if (n->subst() != n) {
1289 assert(last != NULL, "must have last");
1290 last->set_next(n->next());
1291 } else {
1292 last = n;
1293 }
1294 n = last->next();
1295 }
1297 #ifdef ASSERT
1298 SubstitutionChecker check_substitute;
1299 if (block->state()) block->state()->values_do(&check_substitute);
1300 block->block_values_do(&check_substitute);
1301 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
1302 #endif
1303 }