1 /*
2 * Copyright (c) 1999, 2015, 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 "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"
33
34
35 // Implementation of XHandlers
36 //
37 // Note: This code could eventually go away if we are
38 // just using the ciExceptionHandlerStream.
39
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 }
48
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 }
57
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 }
67
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 }
97
98 return false;
99 }
100
101
102 bool XHandlers::equals(XHandlers* others) const {
103 if (others == NULL) return false;
104 if (length() != others->length()) return false;
105
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 }
111
112 bool XHandler::equals(XHandler* other) const {
113 assert(entry_pco() != -1 && other->entry_pco() != -1, "must have entry_pco");
114
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;
118
119 assert(entry_block() == other->entry_block(), "entry_block must be equal when entry_pco is equal");
120 return true;
121 }
122
123
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 }
131
132
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 _wrote_fields = false;
146 _wrote_volatile = false;
147 _start = NULL;
148
149 if (osr_bci == -1) {
150 _requires_phi_function.clear();
151 } else {
152 // selective creation of phi functions is not possibel in osr-methods
153 _requires_phi_function.set_range(0, method->max_locals());
154 }
155
156 assert(method->holder()->is_loaded() , "method holder must be loaded");
157
158 // build graph if monitor pairing is ok
159 if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci);
160 }
161
162
163 int IRScope::max_stack() const {
164 int my_max = method()->max_stack();
165 int callee_max = 0;
166 for (int i = 0; i < number_of_callees(); i++) {
167 callee_max = MAX2(callee_max, callee_no(i)->max_stack());
168 }
169 return my_max + callee_max;
170 }
171
172
173 bool IRScopeDebugInfo::should_reexecute() {
174 ciMethod* cur_method = scope()->method();
175 int cur_bci = bci();
176 if (cur_method != NULL && cur_bci != SynchronizationEntryBCI) {
177 Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci);
178 return Interpreter::bytecode_should_reexecute(code);
179 } else
180 return false;
181 }
182
183
184 // Implementation of CodeEmitInfo
185
186 // Stack must be NON-null
187 CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers, bool deoptimize_on_exception)
188 : _scope(stack->scope())
189 , _scope_debug_info(NULL)
190 , _oop_map(NULL)
191 , _stack(stack)
192 , _exception_handlers(exception_handlers)
193 , _is_method_handle_invoke(false)
194 , _deoptimize_on_exception(deoptimize_on_exception) {
195 assert(_stack != NULL, "must be non null");
196 }
197
198
199 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack)
200 : _scope(info->_scope)
201 , _exception_handlers(NULL)
202 , _scope_debug_info(NULL)
203 , _oop_map(NULL)
204 , _stack(stack == NULL ? info->_stack : stack)
205 , _is_method_handle_invoke(info->_is_method_handle_invoke)
206 , _deoptimize_on_exception(info->_deoptimize_on_exception) {
207
208 // deep copy of exception handlers
209 if (info->_exception_handlers != NULL) {
210 _exception_handlers = new XHandlers(info->_exception_handlers);
211 }
212 }
213
214
215 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) {
216 // record the safepoint before recording the debug info for enclosing scopes
217 recorder->add_safepoint(pc_offset, _oop_map->deep_copy());
218 _scope_debug_info->record_debug_info(recorder, pc_offset, true/*topmost*/, _is_method_handle_invoke);
219 recorder->end_safepoint(pc_offset);
220 }
221
222
223 void CodeEmitInfo::add_register_oop(LIR_Opr opr) {
224 assert(_oop_map != NULL, "oop map must already exist");
225 assert(opr->is_single_cpu(), "should not call otherwise");
226
227 VMReg name = frame_map()->regname(opr);
228 _oop_map->set_oop(name);
229 }
230
231 // Mirror the stack size calculation in the deopt code
232 // How much stack space would we need at this point in the program in
233 // case of deoptimization?
234 int CodeEmitInfo::interpreter_frame_size() const {
235 ValueStack* state = _stack;
236 int size = 0;
237 int callee_parameters = 0;
238 int callee_locals = 0;
239 int extra_args = state->scope()->method()->max_stack() - state->stack_size();
240
241 while (state != NULL) {
242 int locks = state->locks_size();
243 int temps = state->stack_size();
244 bool is_top_frame = (state == _stack);
245 ciMethod* method = state->scope()->method();
246
247 int frame_size = BytesPerWord * Interpreter::size_activation(method->max_stack(),
248 temps + callee_parameters,
249 extra_args,
250 locks,
251 callee_parameters,
252 callee_locals,
253 is_top_frame);
254 size += frame_size;
255
256 callee_parameters = method->size_of_parameters();
257 callee_locals = method->max_locals();
258 extra_args = 0;
259 state = state->caller_state();
260 }
261 return size + Deoptimization::last_frame_adjust(0, callee_locals) * BytesPerWord;
262 }
263
264 // Implementation of IR
265
266 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) :
267 _num_loops(0) {
268 // setup IR fields
269 _compilation = compilation;
270 _top_scope = new IRScope(compilation, NULL, -1, method, osr_bci, true);
271 _code = NULL;
272 }
273
274
275 void IR::optimize_blocks() {
276 Optimizer opt(this);
277 if (!compilation()->profile_branches()) {
278 if (DoCEE) {
279 opt.eliminate_conditional_expressions();
280 #ifndef PRODUCT
281 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
282 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
283 #endif
284 }
285 if (EliminateBlocks) {
286 opt.eliminate_blocks();
287 #ifndef PRODUCT
288 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
289 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
290 #endif
291 }
292 }
293 }
294
295 void IR::eliminate_null_checks() {
296 Optimizer opt(this);
297 if (EliminateNullChecks) {
298 opt.eliminate_null_checks();
299 #ifndef PRODUCT
300 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
301 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
302 #endif
303 }
304 }
305
306
307 static int sort_pairs(BlockPair** a, BlockPair** b) {
308 if ((*a)->from() == (*b)->from()) {
309 return (*a)->to()->block_id() - (*b)->to()->block_id();
310 } else {
311 return (*a)->from()->block_id() - (*b)->from()->block_id();
312 }
313 }
314
315
316 class CriticalEdgeFinder: public BlockClosure {
317 BlockPairList blocks;
318 IR* _ir;
319
320 public:
321 CriticalEdgeFinder(IR* ir): _ir(ir) {}
322 void block_do(BlockBegin* bb) {
323 BlockEnd* be = bb->end();
324 int nos = be->number_of_sux();
325 if (nos >= 2) {
326 for (int i = 0; i < nos; i++) {
327 BlockBegin* sux = be->sux_at(i);
328 if (sux->number_of_preds() >= 2) {
329 blocks.append(new BlockPair(bb, sux));
330 }
331 }
332 }
333 }
334
335 void split_edges() {
336 BlockPair* last_pair = NULL;
337 blocks.sort(sort_pairs);
338 for (int i = 0; i < blocks.length(); i++) {
339 BlockPair* pair = blocks.at(i);
340 if (last_pair != NULL && pair->is_same(last_pair)) continue;
341 BlockBegin* from = pair->from();
342 BlockBegin* to = pair->to();
343 BlockBegin* split = from->insert_block_between(to);
344 #ifndef PRODUCT
345 if ((PrintIR || PrintIR1) && Verbose) {
346 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
347 from->block_id(), to->block_id(), split->block_id());
348 }
349 #endif
350 last_pair = pair;
351 }
352 }
353 };
354
355 void IR::split_critical_edges() {
356 CriticalEdgeFinder cef(this);
357
358 iterate_preorder(&cef);
359 cef.split_edges();
360 }
361
362
363 class UseCountComputer: public ValueVisitor, BlockClosure {
364 private:
365 void visit(Value* n) {
366 // Local instructions and Phis for expression stack values at the
367 // start of basic blocks are not added to the instruction list
368 if (!(*n)->is_linked() && (*n)->can_be_linked()) {
369 assert(false, "a node was not appended to the graph");
370 Compilation::current()->bailout("a node was not appended to the graph");
371 }
372 // use n's input if not visited before
373 if (!(*n)->is_pinned() && !(*n)->has_uses()) {
374 // note: a) if the instruction is pinned, it will be handled by compute_use_count
375 // b) if the instruction has uses, it was touched before
376 // => in both cases we don't need to update n's values
377 uses_do(n);
378 }
379 // use n
380 (*n)->_use_count++;
381 }
382
383 Values* worklist;
384 int depth;
385 enum {
386 max_recurse_depth = 20
387 };
388
389 void uses_do(Value* n) {
390 depth++;
391 if (depth > max_recurse_depth) {
392 // don't allow the traversal to recurse too deeply
393 worklist->push(*n);
394 } else {
395 (*n)->input_values_do(this);
396 // special handling for some instructions
397 if ((*n)->as_BlockEnd() != NULL) {
398 // note on BlockEnd:
399 // must 'use' the stack only if the method doesn't
400 // terminate, however, in those cases stack is empty
401 (*n)->state_values_do(this);
402 }
403 }
404 depth--;
405 }
406
407 void block_do(BlockBegin* b) {
408 depth = 0;
409 // process all pinned nodes as the roots of expression trees
410 for (Instruction* n = b; n != NULL; n = n->next()) {
411 if (n->is_pinned()) uses_do(&n);
412 }
413 assert(depth == 0, "should have counted back down");
414
415 // now process any unpinned nodes which recursed too deeply
416 while (worklist->length() > 0) {
417 Value t = worklist->pop();
418 if (!t->is_pinned()) {
419 // compute the use count
420 uses_do(&t);
421
422 // pin the instruction so that LIRGenerator doesn't recurse
423 // too deeply during it's evaluation.
424 t->pin();
425 }
426 }
427 assert(depth == 0, "should have counted back down");
428 }
429
430 UseCountComputer() {
431 worklist = new Values();
432 depth = 0;
433 }
434
435 public:
436 static void compute(BlockList* blocks) {
437 UseCountComputer ucc;
438 blocks->iterate_backward(&ucc);
439 }
440 };
441
442
443 // helper macro for short definition of trace-output inside code
444 #ifndef PRODUCT
445 #define TRACE_LINEAR_SCAN(level, code) \
446 if (TraceLinearScanLevel >= level) { \
447 code; \
448 }
449 #else
450 #define TRACE_LINEAR_SCAN(level, code)
451 #endif
452
453 class ComputeLinearScanOrder : public StackObj {
454 private:
455 int _max_block_id; // the highest block_id of a block
456 int _num_blocks; // total number of blocks (smaller than _max_block_id)
457 int _num_loops; // total number of loops
458 bool _iterative_dominators;// method requires iterative computation of dominatiors
459
460 BlockList* _linear_scan_order; // the resulting list of blocks in correct order
461
462 BitMap _visited_blocks; // used for recursive processing of blocks
463 BitMap _active_blocks; // used for recursive processing of blocks
464 BitMap _dominator_blocks; // temproary BitMap used for computation of dominator
465 intArray _forward_branches; // number of incoming forward branches for each block
466 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges
467 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop
468 BlockList _work_list; // temporary list (used in mark_loops and compute_order)
469 BlockList _loop_headers;
470
471 Compilation* _compilation;
472
473 // accessors for _visited_blocks and _active_blocks
474 void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); }
475 bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); }
476 bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); }
477 void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); }
478 void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); }
479 void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); }
480
481 // accessors for _forward_branches
482 void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); }
483 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()); }
484
485 // accessors for _loop_map
486 bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); }
487 void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); }
488 void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); }
489
490 // count edges between blocks
491 void count_edges(BlockBegin* cur, BlockBegin* parent);
492
493 // loop detection
494 void mark_loops();
495 void clear_non_natural_loops(BlockBegin* start_block);
496 void assign_loop_depth(BlockBegin* start_block);
497
498 // computation of final block order
499 BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b);
500 void compute_dominator(BlockBegin* cur, BlockBegin* parent);
501 int compute_weight(BlockBegin* cur);
502 bool ready_for_processing(BlockBegin* cur);
503 void sort_into_work_list(BlockBegin* b);
504 void append_block(BlockBegin* cur);
505 void compute_order(BlockBegin* start_block);
506
507 // fixup of dominators for non-natural loops
508 bool compute_dominators_iter();
509 void compute_dominators();
510
511 // debug functions
512 NOT_PRODUCT(void print_blocks();)
513 DEBUG_ONLY(void verify();)
514
515 Compilation* compilation() const { return _compilation; }
516 public:
517 ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block);
518
519 // accessors for final result
520 BlockList* linear_scan_order() const { return _linear_scan_order; }
521 int num_loops() const { return _num_loops; }
522 };
523
524
525 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) :
526 _max_block_id(BlockBegin::number_of_blocks()),
527 _num_blocks(0),
528 _num_loops(0),
529 _iterative_dominators(false),
530 _visited_blocks(_max_block_id),
531 _active_blocks(_max_block_id),
532 _dominator_blocks(_max_block_id),
533 _forward_branches(_max_block_id, 0),
534 _loop_end_blocks(8),
535 _work_list(8),
536 _linear_scan_order(NULL), // initialized later with correct size
537 _loop_map(0, 0), // initialized later with correct size
538 _compilation(c)
539 {
540 TRACE_LINEAR_SCAN(2, tty->print_cr("***** computing linear-scan block order"));
541
542 init_visited();
543 count_edges(start_block, NULL);
544
545 if (compilation()->is_profiling()) {
546 ciMethod *method = compilation()->method();
547 if (!method->is_accessor()) {
548 ciMethodData* md = method->method_data_or_null();
549 assert(md != NULL, "Sanity");
550 md->set_compilation_stats(_num_loops, _num_blocks);
551 }
552 }
553
554 if (_num_loops > 0) {
555 mark_loops();
556 clear_non_natural_loops(start_block);
557 assign_loop_depth(start_block);
558 }
559
560 compute_order(start_block);
561 compute_dominators();
562
563 NOT_PRODUCT(print_blocks());
564 DEBUG_ONLY(verify());
565 }
566
567
568 // Traverse the CFG:
569 // * count total number of blocks
570 // * count all incoming edges and backward incoming edges
571 // * number loop header blocks
572 // * create a list with all loop end blocks
573 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
574 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));
575 assert(cur->dominator() == NULL, "dominator already initialized");
576
577 if (is_active(cur)) {
578 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
579 assert(is_visited(cur), "block must be visisted when block is active");
580 assert(parent != NULL, "must have parent");
581
582 cur->set(BlockBegin::backward_branch_target_flag);
583
584 // When a loop header is also the start of an exception handler, then the backward branch is
585 // an exception edge. Because such edges are usually critical edges which cannot be split, the
586 // loop must be excluded here from processing.
587 if (cur->is_set(BlockBegin::exception_entry_flag)) {
588 // Make sure that dominators are correct in this weird situation
589 _iterative_dominators = true;
590 return;
591 }
592
593 cur->set(BlockBegin::linear_scan_loop_header_flag);
594 parent->set(BlockBegin::linear_scan_loop_end_flag);
595
596 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
597 "loop end blocks must have one successor (critical edges are split)");
598
599 _loop_end_blocks.append(parent);
600 return;
601 }
602
603 // increment number of incoming forward branches
604 inc_forward_branches(cur);
605
606 if (is_visited(cur)) {
607 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
608 return;
609 }
610
611 _num_blocks++;
612 set_visited(cur);
613 set_active(cur);
614
615 // recursive call for all successors
616 int i;
617 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
618 count_edges(cur->sux_at(i), cur);
619 }
620 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
621 count_edges(cur->exception_handler_at(i), cur);
622 }
623
624 clear_active(cur);
625
626 // Each loop has a unique number.
627 // When multiple loops are nested, assign_loop_depth assumes that the
628 // innermost loop has the lowest number. This is guaranteed by setting
629 // the loop number after the recursive calls for the successors above
630 // have returned.
631 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
632 assert(cur->loop_index() == -1, "cannot set loop-index twice");
633 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
634
635 cur->set_loop_index(_num_loops);
636 _loop_headers.append(cur);
637 _num_loops++;
638 }
639
640 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
641 }
642
643
644 void ComputeLinearScanOrder::mark_loops() {
645 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
646
647 _loop_map = BitMap2D(_num_loops, _max_block_id);
648 _loop_map.clear();
649
650 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
651 BlockBegin* loop_end = _loop_end_blocks.at(i);
652 BlockBegin* loop_start = loop_end->sux_at(0);
653 int loop_idx = loop_start->loop_index();
654
655 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));
656 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
657 assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
658 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
659 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
660 assert(_work_list.is_empty(), "work list must be empty before processing");
661
662 // add the end-block of the loop to the working list
663 _work_list.push(loop_end);
664 set_block_in_loop(loop_idx, loop_end);
665 do {
666 BlockBegin* cur = _work_list.pop();
667
668 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id()));
669 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
670
671 // recursive processing of all predecessors ends when start block of loop is reached
672 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
673 for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
674 BlockBegin* pred = cur->pred_at(j);
675
676 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
677 // this predecessor has not been processed yet, so add it to work list
678 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id()));
679 _work_list.push(pred);
680 set_block_in_loop(loop_idx, pred);
681 }
682 }
683 }
684 } while (!_work_list.is_empty());
685 }
686 }
687
688
689 // check for non-natural loops (loops where the loop header does not dominate
690 // all other loop blocks = loops with mulitple entries).
691 // such loops are ignored
692 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
693 for (int i = _num_loops - 1; i >= 0; i--) {
694 if (is_block_in_loop(i, start_block)) {
695 // loop i contains the entry block of the method
696 // -> this is not a natural loop, so ignore it
697 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
698
699 BlockBegin *loop_header = _loop_headers.at(i);
700 assert(loop_header->is_set(BlockBegin::linear_scan_loop_header_flag), "Must be loop header");
701
702 for (int j = 0; j < loop_header->number_of_preds(); j++) {
703 BlockBegin *pred = loop_header->pred_at(j);
704 pred->clear(BlockBegin::linear_scan_loop_end_flag);
705 }
706
707 loop_header->clear(BlockBegin::linear_scan_loop_header_flag);
708
709 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
710 clear_block_in_loop(i, block_id);
711 }
712 _iterative_dominators = true;
713 }
714 }
715 }
716
717 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
718 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing loop-depth and weight"));
719 init_visited();
720
721 assert(_work_list.is_empty(), "work list must be empty before processing");
722 _work_list.append(start_block);
723
724 do {
725 BlockBegin* cur = _work_list.pop();
726
727 if (!is_visited(cur)) {
728 set_visited(cur);
729 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
730
731 // compute loop-depth and loop-index for the block
732 assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
733 int i;
734 int loop_depth = 0;
735 int min_loop_idx = -1;
736 for (i = _num_loops - 1; i >= 0; i--) {
737 if (is_block_in_loop(i, cur)) {
738 loop_depth++;
739 min_loop_idx = i;
740 }
741 }
742 cur->set_loop_depth(loop_depth);
743 cur->set_loop_index(min_loop_idx);
744
745 // append all unvisited successors to work list
746 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
747 _work_list.append(cur->sux_at(i));
748 }
749 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
750 _work_list.append(cur->exception_handler_at(i));
751 }
752 }
753 } while (!_work_list.is_empty());
754 }
755
756
757 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
758 assert(a != NULL && b != NULL, "must have input blocks");
759
760 _dominator_blocks.clear();
761 while (a != NULL) {
762 _dominator_blocks.set_bit(a->block_id());
763 assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
764 a = a->dominator();
765 }
766 while (b != NULL && !_dominator_blocks.at(b->block_id())) {
767 assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
768 b = b->dominator();
769 }
770
771 assert(b != NULL, "could not find dominator");
772 return b;
773 }
774
775 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
776 if (cur->dominator() == NULL) {
777 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
778 cur->set_dominator(parent);
779
780 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
781 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()));
782 // Does not hold for exception blocks
783 assert(cur->number_of_preds() > 1 || cur->is_set(BlockBegin::exception_entry_flag), "");
784 cur->set_dominator(common_dominator(cur->dominator(), parent));
785 }
786
787 // Additional edge to xhandler of all our successors
788 // range check elimination needs that the state at the end of a
789 // block be valid in every block it dominates so cur must dominate
790 // the exception handlers of its successors.
791 int num_cur_xhandler = cur->number_of_exception_handlers();
792 for (int j = 0; j < num_cur_xhandler; j++) {
793 BlockBegin* xhandler = cur->exception_handler_at(j);
794 compute_dominator(xhandler, parent);
795 }
796 }
797
798
799 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
800 BlockBegin* single_sux = NULL;
801 if (cur->number_of_sux() == 1) {
802 single_sux = cur->sux_at(0);
803 }
804
805 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
806 int weight = (cur->loop_depth() & 0x7FFF) << 16;
807
808 // general macro for short definition of weight flags
809 // the first instance of INC_WEIGHT_IF has the highest priority
810 int cur_bit = 15;
811 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
812
813 // this is necessery for the (very rare) case that two successing blocks have
814 // the same loop depth, but a different loop index (can happen for endless loops
815 // with exception handlers)
816 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
817
818 // loop end blocks (blocks that end with a backward branch) are added
819 // after all other blocks of the loop.
820 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
821
822 // critical edge split blocks are prefered because than they have a bigger
823 // proability to be completely empty
824 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
825
826 // exceptions should not be thrown in normal control flow, so these blocks
827 // are added as late as possible
828 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL));
829 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
830
831 // exceptions handlers are added as late as possible
832 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
833
834 // guarantee that weight is > 0
835 weight |= 1;
836
837 #undef INC_WEIGHT_IF
838 assert(cur_bit >= 0, "too many flags");
839 assert(weight > 0, "weight cannot become negative");
840
841 return weight;
842 }
843
844 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
845 // Discount the edge just traveled.
846 // When the number drops to zero, all forward branches were processed
847 if (dec_forward_branches(cur) != 0) {
848 return false;
849 }
850
851 assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
852 assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
853 return true;
854 }
855
856 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
857 assert(_work_list.index_of(cur) == -1, "block already in work list");
858
859 int cur_weight = compute_weight(cur);
860
861 // the linear_scan_number is used to cache the weight of a block
862 cur->set_linear_scan_number(cur_weight);
863
864 #ifndef PRODUCT
865 if (StressLinearScan) {
866 _work_list.insert_before(0, cur);
867 return;
868 }
869 #endif
870
871 _work_list.append(NULL); // provide space for new element
872
873 int insert_idx = _work_list.length() - 1;
874 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
875 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
876 insert_idx--;
877 }
878 _work_list.at_put(insert_idx, cur);
879
880 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
881 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()));
882
883 #ifdef ASSERT
884 for (int i = 0; i < _work_list.length(); i++) {
885 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
886 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
887 }
888 #endif
889 }
890
891 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
892 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()));
893 assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
894
895 // currently, the linear scan order and code emit order are equal.
896 // therefore the linear_scan_number and the weight of a block must also
897 // be equal.
898 cur->set_linear_scan_number(_linear_scan_order->length());
899 _linear_scan_order->append(cur);
900 }
901
902 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
903 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing final block order"));
904
905 // the start block is always the first block in the linear scan order
906 _linear_scan_order = new BlockList(_num_blocks);
907 append_block(start_block);
908
909 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
910 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
911 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
912
913 BlockBegin* sux_of_osr_entry = NULL;
914 if (osr_entry != NULL) {
915 // special handling for osr entry:
916 // ignore the edge between the osr entry and its successor for processing
917 // the osr entry block is added manually below
918 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
919 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");
920
921 sux_of_osr_entry = osr_entry->sux_at(0);
922 dec_forward_branches(sux_of_osr_entry);
923
924 compute_dominator(osr_entry, start_block);
925 _iterative_dominators = true;
926 }
927 compute_dominator(std_entry, start_block);
928
929 // start processing with standard entry block
930 assert(_work_list.is_empty(), "list must be empty before processing");
931
932 if (ready_for_processing(std_entry)) {
933 sort_into_work_list(std_entry);
934 } else {
935 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
936 }
937
938 do {
939 BlockBegin* cur = _work_list.pop();
940
941 if (cur == sux_of_osr_entry) {
942 // the osr entry block is ignored in normal processing, it is never added to the
943 // work list. Instead, it is added as late as possible manually here.
944 append_block(osr_entry);
945 compute_dominator(cur, osr_entry);
946 }
947 append_block(cur);
948
949 int i;
950 int num_sux = cur->number_of_sux();
951 // changed loop order to get "intuitive" order of if- and else-blocks
952 for (i = 0; i < num_sux; i++) {
953 BlockBegin* sux = cur->sux_at(i);
954 compute_dominator(sux, cur);
955 if (ready_for_processing(sux)) {
956 sort_into_work_list(sux);
957 }
958 }
959 num_sux = cur->number_of_exception_handlers();
960 for (i = 0; i < num_sux; i++) {
961 BlockBegin* sux = cur->exception_handler_at(i);
962 if (ready_for_processing(sux)) {
963 sort_into_work_list(sux);
964 }
965 }
966 } while (_work_list.length() > 0);
967 }
968
969
970 bool ComputeLinearScanOrder::compute_dominators_iter() {
971 bool changed = false;
972 int num_blocks = _linear_scan_order->length();
973
974 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
975 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
976 for (int i = 1; i < num_blocks; i++) {
977 BlockBegin* block = _linear_scan_order->at(i);
978
979 BlockBegin* dominator = block->pred_at(0);
980 int num_preds = block->number_of_preds();
981
982 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: Processing B%d", block->block_id()));
983
984 for (int j = 0; j < num_preds; j++) {
985
986 BlockBegin *pred = block->pred_at(j);
987 TRACE_LINEAR_SCAN(4, tty->print_cr(" DOM: Subrocessing B%d", pred->block_id()));
988
989 if (block->is_set(BlockBegin::exception_entry_flag)) {
990 dominator = common_dominator(dominator, pred);
991 int num_pred_preds = pred->number_of_preds();
992 for (int k = 0; k < num_pred_preds; k++) {
993 dominator = common_dominator(dominator, pred->pred_at(k));
994 }
995 } else {
996 dominator = common_dominator(dominator, pred);
997 }
998 }
999
1000 if (dominator != block->dominator()) {
1001 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()));
1002
1003 block->set_dominator(dominator);
1004 changed = true;
1005 }
1006 }
1007 return changed;
1008 }
1009
1010 void ComputeLinearScanOrder::compute_dominators() {
1011 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
1012
1013 // iterative computation of dominators is only required for methods with non-natural loops
1014 // and OSR-methods. For all other methods, the dominators computed when generating the
1015 // linear scan block order are correct.
1016 if (_iterative_dominators) {
1017 do {
1018 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
1019 } while (compute_dominators_iter());
1020 }
1021
1022 // check that dominators are correct
1023 assert(!compute_dominators_iter(), "fix point not reached");
1024
1025 // Add Blocks to dominates-Array
1026 int num_blocks = _linear_scan_order->length();
1027 for (int i = 0; i < num_blocks; i++) {
1028 BlockBegin* block = _linear_scan_order->at(i);
1029
1030 BlockBegin *dom = block->dominator();
1031 if (dom) {
1032 assert(dom->dominator_depth() != -1, "Dominator must have been visited before");
1033 dom->dominates()->append(block);
1034 block->set_dominator_depth(dom->dominator_depth() + 1);
1035 } else {
1036 block->set_dominator_depth(0);
1037 }
1038 }
1039 }
1040
1041
1042 #ifndef PRODUCT
1043 void ComputeLinearScanOrder::print_blocks() {
1044 if (TraceLinearScanLevel >= 2) {
1045 tty->print_cr("----- loop information:");
1046 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1047 BlockBegin* cur = _linear_scan_order->at(block_idx);
1048
1049 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
1050 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1051 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
1052 }
1053 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
1054 }
1055 }
1056
1057 if (TraceLinearScanLevel >= 1) {
1058 tty->print_cr("----- linear-scan block order:");
1059 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1060 BlockBegin* cur = _linear_scan_order->at(block_idx);
1061 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
1062
1063 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
1064 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
1065 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
1066 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
1067
1068 if (cur->dominator() != NULL) {
1069 tty->print(" dom: B%d ", cur->dominator()->block_id());
1070 } else {
1071 tty->print(" dom: NULL ");
1072 }
1073
1074 if (cur->number_of_preds() > 0) {
1075 tty->print(" preds: ");
1076 for (int j = 0; j < cur->number_of_preds(); j++) {
1077 BlockBegin* pred = cur->pred_at(j);
1078 tty->print("B%d ", pred->block_id());
1079 }
1080 }
1081 if (cur->number_of_sux() > 0) {
1082 tty->print(" sux: ");
1083 for (int j = 0; j < cur->number_of_sux(); j++) {
1084 BlockBegin* sux = cur->sux_at(j);
1085 tty->print("B%d ", sux->block_id());
1086 }
1087 }
1088 if (cur->number_of_exception_handlers() > 0) {
1089 tty->print(" ex: ");
1090 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1091 BlockBegin* ex = cur->exception_handler_at(j);
1092 tty->print("B%d ", ex->block_id());
1093 }
1094 }
1095 tty->cr();
1096 }
1097 }
1098 }
1099 #endif
1100
1101 #ifdef ASSERT
1102 void ComputeLinearScanOrder::verify() {
1103 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1104
1105 if (StressLinearScan) {
1106 // blocks are scrambled when StressLinearScan is used
1107 return;
1108 }
1109
1110 // check that all successors of a block have a higher linear-scan-number
1111 // and that all predecessors of a block have a lower linear-scan-number
1112 // (only backward branches of loops are ignored)
1113 int i;
1114 for (i = 0; i < _linear_scan_order->length(); i++) {
1115 BlockBegin* cur = _linear_scan_order->at(i);
1116
1117 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1118 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
1119
1120 int j;
1121 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1122 BlockBegin* sux = cur->sux_at(j);
1123
1124 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
1125 if (!sux->is_set(BlockBegin::backward_branch_target_flag)) {
1126 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1127 }
1128 if (cur->loop_depth() == sux->loop_depth()) {
1129 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");
1130 }
1131 }
1132
1133 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1134 BlockBegin* pred = cur->pred_at(j);
1135
1136 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
1137 if (!cur->is_set(BlockBegin::backward_branch_target_flag)) {
1138 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1139 }
1140 if (cur->loop_depth() == pred->loop_depth()) {
1141 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");
1142 }
1143
1144 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1145 }
1146
1147 // check dominator
1148 if (i == 0) {
1149 assert(cur->dominator() == NULL, "first block has no dominator");
1150 } else {
1151 assert(cur->dominator() != NULL, "all but first block must have dominator");
1152 }
1153 // Assertion does not hold for exception handlers
1154 assert(cur->number_of_preds() != 1 || cur->dominator() == cur->pred_at(0) || cur->is_set(BlockBegin::exception_entry_flag), "Single predecessor must also be dominator");
1155 }
1156
1157 // check that all loops are continuous
1158 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1159 int block_idx = 0;
1160 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1161
1162 // skip blocks before the loop
1163 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1164 block_idx++;
1165 }
1166 // skip blocks of loop
1167 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1168 block_idx++;
1169 }
1170 // after the first non-loop block, there must not be another loop-block
1171 while (block_idx < _num_blocks) {
1172 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1173 block_idx++;
1174 }
1175 }
1176 }
1177 #endif
1178
1179
1180 void IR::compute_code() {
1181 assert(is_valid(), "IR must be valid");
1182
1183 ComputeLinearScanOrder compute_order(compilation(), start());
1184 _num_loops = compute_order.num_loops();
1185 _code = compute_order.linear_scan_order();
1186 }
1187
1188
1189 void IR::compute_use_counts() {
1190 // make sure all values coming out of this block get evaluated.
1191 int num_blocks = _code->length();
1192 for (int i = 0; i < num_blocks; i++) {
1193 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1194 }
1195
1196 // compute use counts
1197 UseCountComputer::compute(_code);
1198 }
1199
1200
1201 void IR::iterate_preorder(BlockClosure* closure) {
1202 assert(is_valid(), "IR must be valid");
1203 start()->iterate_preorder(closure);
1204 }
1205
1206
1207 void IR::iterate_postorder(BlockClosure* closure) {
1208 assert(is_valid(), "IR must be valid");
1209 start()->iterate_postorder(closure);
1210 }
1211
1212 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1213 linear_scan_order()->iterate_forward(closure);
1214 }
1215
1216
1217 #ifndef PRODUCT
1218 class BlockPrinter: public BlockClosure {
1219 private:
1220 InstructionPrinter* _ip;
1221 bool _cfg_only;
1222 bool _live_only;
1223
1224 public:
1225 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1226 _ip = ip;
1227 _cfg_only = cfg_only;
1228 _live_only = live_only;
1229 }
1230
1231 virtual void block_do(BlockBegin* block) {
1232 if (_cfg_only) {
1233 _ip->print_instr(block); tty->cr();
1234 } else {
1235 block->print_block(*_ip, _live_only);
1236 }
1237 }
1238 };
1239
1240
1241 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1242 ttyLocker ttyl;
1243 InstructionPrinter ip(!cfg_only);
1244 BlockPrinter bp(&ip, cfg_only, live_only);
1245 start->iterate_preorder(&bp);
1246 tty->cr();
1247 }
1248
1249 void IR::print(bool cfg_only, bool live_only) {
1250 if (is_valid()) {
1251 print(start(), cfg_only, live_only);
1252 } else {
1253 tty->print_cr("invalid IR");
1254 }
1255 }
1256
1257
1258 define_array(BlockListArray, BlockList*)
1259 define_stack(BlockListList, BlockListArray)
1260
1261 class PredecessorValidator : public BlockClosure {
1262 private:
1263 BlockListList* _predecessors;
1264 BlockList* _blocks;
1265
1266 static int cmp(BlockBegin** a, BlockBegin** b) {
1267 return (*a)->block_id() - (*b)->block_id();
1268 }
1269
1270 public:
1271 PredecessorValidator(IR* hir) {
1272 ResourceMark rm;
1273 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
1274 _blocks = new BlockList();
1275
1276 int i;
1277 hir->start()->iterate_preorder(this);
1278 if (hir->code() != NULL) {
1279 assert(hir->code()->length() == _blocks->length(), "must match");
1280 for (i = 0; i < _blocks->length(); i++) {
1281 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1282 }
1283 }
1284
1285 for (i = 0; i < _blocks->length(); i++) {
1286 BlockBegin* block = _blocks->at(i);
1287 BlockList* preds = _predecessors->at(block->block_id());
1288 if (preds == NULL) {
1289 assert(block->number_of_preds() == 0, "should be the same");
1290 continue;
1291 }
1292
1293 // clone the pred list so we can mutate it
1294 BlockList* pred_copy = new BlockList();
1295 int j;
1296 for (j = 0; j < block->number_of_preds(); j++) {
1297 pred_copy->append(block->pred_at(j));
1298 }
1299 // sort them in the same order
1300 preds->sort(cmp);
1301 pred_copy->sort(cmp);
1302 int length = MIN2(preds->length(), block->number_of_preds());
1303 for (j = 0; j < block->number_of_preds(); j++) {
1304 assert(preds->at(j) == pred_copy->at(j), "must match");
1305 }
1306
1307 assert(preds->length() == block->number_of_preds(), "should be the same");
1308 }
1309 }
1310
1311 virtual void block_do(BlockBegin* block) {
1312 _blocks->append(block);
1313 BlockEnd* be = block->end();
1314 int n = be->number_of_sux();
1315 int i;
1316 for (i = 0; i < n; i++) {
1317 BlockBegin* sux = be->sux_at(i);
1318 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1319
1320 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1321 if (preds == NULL) {
1322 preds = new BlockList();
1323 _predecessors->at_put(sux->block_id(), preds);
1324 }
1325 preds->append(block);
1326 }
1327
1328 n = block->number_of_exception_handlers();
1329 for (i = 0; i < n; i++) {
1330 BlockBegin* sux = block->exception_handler_at(i);
1331 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1332
1333 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1334 if (preds == NULL) {
1335 preds = new BlockList();
1336 _predecessors->at_put(sux->block_id(), preds);
1337 }
1338 preds->append(block);
1339 }
1340 }
1341 };
1342
1343 class VerifyBlockBeginField : public BlockClosure {
1344
1345 public:
1346
1347 virtual void block_do(BlockBegin *block) {
1348 for ( Instruction *cur = block; cur != NULL; cur = cur->next()) {
1349 assert(cur->block() == block, "Block begin is not correct");
1350 }
1351 }
1352 };
1353
1354 void IR::verify() {
1355 #ifdef ASSERT
1356 PredecessorValidator pv(this);
1357 VerifyBlockBeginField verifier;
1358 this->iterate_postorder(&verifier);
1359 #endif
1360 }
1361
1362 #endif // PRODUCT
1363
1364 void SubstitutionResolver::visit(Value* v) {
1365 Value v0 = *v;
1366 if (v0) {
1367 Value vs = v0->subst();
1368 if (vs != v0) {
1369 *v = v0->subst();
1370 }
1371 }
1372 }
1373
1374 #ifdef ASSERT
1375 class SubstitutionChecker: public ValueVisitor {
1376 void visit(Value* v) {
1377 Value v0 = *v;
1378 if (v0) {
1379 Value vs = v0->subst();
1380 assert(vs == v0, "missed substitution");
1381 }
1382 }
1383 };
1384 #endif
1385
1386
1387 void SubstitutionResolver::block_do(BlockBegin* block) {
1388 Instruction* last = NULL;
1389 for (Instruction* n = block; n != NULL;) {
1390 n->values_do(this);
1391 // need to remove this instruction from the instruction stream
1392 if (n->subst() != n) {
1393 assert(last != NULL, "must have last");
1394 last->set_next(n->next());
1395 } else {
1396 last = n;
1397 }
1398 n = last->next();
1399 }
1400
1401 #ifdef ASSERT
1402 SubstitutionChecker check_substitute;
1403 if (block->state()) block->state()->values_do(&check_substitute);
1404 block->block_values_do(&check_substitute);
1405 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
1406 #endif
1407 }