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::linear_scan_loop_header_flag);
583 cur->set(BlockBegin::backward_branch_target_flag);
584
585 parent->set(BlockBegin::linear_scan_loop_end_flag);
586
587 // When a loop header is also the start of an exception handler, then the backward branch is
588 // an exception edge. Because such edges are usually critical edges which cannot be split, the
589 // loop must be excluded here from processing.
590 if (cur->is_set(BlockBegin::exception_entry_flag)) {
591 // Make sure that dominators are correct in this weird situation
592 _iterative_dominators = true;
593 return;
594 }
595 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
596 "loop end blocks must have one successor (critical edges are split)");
597
598 _loop_end_blocks.append(parent);
599 return;
600 }
601
602 // increment number of incoming forward branches
603 inc_forward_branches(cur);
604
605 if (is_visited(cur)) {
606 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
607 return;
608 }
609
610 _num_blocks++;
611 set_visited(cur);
612 set_active(cur);
613
614 // recursive call for all successors
615 int i;
616 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
617 count_edges(cur->sux_at(i), cur);
618 }
619 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
620 count_edges(cur->exception_handler_at(i), cur);
621 }
622
623 clear_active(cur);
624
625 // Each loop has a unique number.
626 // When multiple loops are nested, assign_loop_depth assumes that the
627 // innermost loop has the lowest number. This is guaranteed by setting
628 // the loop number after the recursive calls for the successors above
629 // have returned.
630 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
631 assert(cur->loop_index() == -1, "cannot set loop-index twice");
632 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
633
634 cur->set_loop_index(_num_loops);
635 _loop_headers.append(cur);
636 _num_loops++;
637 }
638
639 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
640 }
641
642
643 void ComputeLinearScanOrder::mark_loops() {
644 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
645
646 _loop_map = BitMap2D(_num_loops, _max_block_id);
647 _loop_map.clear();
648
649 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
650 BlockBegin* loop_end = _loop_end_blocks.at(i);
651 BlockBegin* loop_start = loop_end->sux_at(0);
652 int loop_idx = loop_start->loop_index();
653
654 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));
655 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
656 assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
657 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
658 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
659 assert(_work_list.is_empty(), "work list must be empty before processing");
660
661 // add the end-block of the loop to the working list
662 _work_list.push(loop_end);
663 set_block_in_loop(loop_idx, loop_end);
664 do {
665 BlockBegin* cur = _work_list.pop();
666
667 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id()));
668 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
669
670 // recursive processing of all predecessors ends when start block of loop is reached
671 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
672 for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
673 BlockBegin* pred = cur->pred_at(j);
674
675 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
676 // this predecessor has not been processed yet, so add it to work list
677 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id()));
678 _work_list.push(pred);
679 set_block_in_loop(loop_idx, pred);
680 }
681 }
682 }
683 } while (!_work_list.is_empty());
684 }
685 }
686
687
688 // check for non-natural loops (loops where the loop header does not dominate
689 // all other loop blocks = loops with mulitple entries).
690 // such loops are ignored
691 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
692 for (int i = _num_loops - 1; i >= 0; i--) {
693 if (is_block_in_loop(i, start_block)) {
694 // loop i contains the entry block of the method
695 // -> this is not a natural loop, so ignore it
696 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
697
698 BlockBegin *loop_header = _loop_headers.at(i);
699 assert(loop_header->is_set(BlockBegin::linear_scan_loop_header_flag), "Must be loop header");
700
701 for (int j = 0; j < loop_header->number_of_preds(); j++) {
702 BlockBegin *pred = loop_header->pred_at(j);
703 pred->clear(BlockBegin::linear_scan_loop_end_flag);
704 }
705
706 loop_header->clear(BlockBegin::linear_scan_loop_header_flag);
707
708 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
709 clear_block_in_loop(i, block_id);
710 }
711 _iterative_dominators = true;
712 }
713 }
714 }
715
716 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
717 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing loop-depth and weight"));
718 init_visited();
719
720 assert(_work_list.is_empty(), "work list must be empty before processing");
721 _work_list.append(start_block);
722
723 do {
724 BlockBegin* cur = _work_list.pop();
725
726 if (!is_visited(cur)) {
727 set_visited(cur);
728 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
729
730 // compute loop-depth and loop-index for the block
731 assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
732 int i;
733 int loop_depth = 0;
734 int min_loop_idx = -1;
735 for (i = _num_loops - 1; i >= 0; i--) {
736 if (is_block_in_loop(i, cur)) {
737 loop_depth++;
738 min_loop_idx = i;
739 }
740 }
741 cur->set_loop_depth(loop_depth);
742 cur->set_loop_index(min_loop_idx);
743
744 // append all unvisited successors to work list
745 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
746 _work_list.append(cur->sux_at(i));
747 }
748 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
749 _work_list.append(cur->exception_handler_at(i));
750 }
751 }
752 } while (!_work_list.is_empty());
753 }
754
755
756 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
757 assert(a != NULL && b != NULL, "must have input blocks");
758
759 _dominator_blocks.clear();
760 while (a != NULL) {
761 _dominator_blocks.set_bit(a->block_id());
762 assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
763 a = a->dominator();
764 }
765 while (b != NULL && !_dominator_blocks.at(b->block_id())) {
766 assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
767 b = b->dominator();
768 }
769
770 assert(b != NULL, "could not find dominator");
771 return b;
772 }
773
774 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
775 if (cur->dominator() == NULL) {
776 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
777 cur->set_dominator(parent);
778
779 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
780 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()));
781 // Does not hold for exception blocks
782 assert(cur->number_of_preds() > 1 || cur->is_set(BlockBegin::exception_entry_flag), "");
783 cur->set_dominator(common_dominator(cur->dominator(), parent));
784 }
785
786 // Additional edge to xhandler of all our successors
787 // range check elimination needs that the state at the end of a
788 // block be valid in every block it dominates so cur must dominate
789 // the exception handlers of its successors.
790 int num_cur_xhandler = cur->number_of_exception_handlers();
791 for (int j = 0; j < num_cur_xhandler; j++) {
792 BlockBegin* xhandler = cur->exception_handler_at(j);
793 compute_dominator(xhandler, parent);
794 }
795 }
796
797
798 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
799 BlockBegin* single_sux = NULL;
800 if (cur->number_of_sux() == 1) {
801 single_sux = cur->sux_at(0);
802 }
803
804 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
805 int weight = (cur->loop_depth() & 0x7FFF) << 16;
806
807 // general macro for short definition of weight flags
808 // the first instance of INC_WEIGHT_IF has the highest priority
809 int cur_bit = 15;
810 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
811
812 // this is necessery for the (very rare) case that two successing blocks have
813 // the same loop depth, but a different loop index (can happen for endless loops
814 // with exception handlers)
815 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
816
817 // loop end blocks (blocks that end with a backward branch) are added
818 // after all other blocks of the loop.
819 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
820
821 // critical edge split blocks are prefered because than they have a bigger
822 // proability to be completely empty
823 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
824
825 // exceptions should not be thrown in normal control flow, so these blocks
826 // are added as late as possible
827 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL));
828 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
829
830 // exceptions handlers are added as late as possible
831 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
832
833 // guarantee that weight is > 0
834 weight |= 1;
835
836 #undef INC_WEIGHT_IF
837 assert(cur_bit >= 0, "too many flags");
838 assert(weight > 0, "weight cannot become negative");
839
840 return weight;
841 }
842
843 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
844 // Discount the edge just traveled.
845 // When the number drops to zero, all forward branches were processed
846 if (dec_forward_branches(cur) != 0) {
847 return false;
848 }
849
850 assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
851 assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
852 return true;
853 }
854
855 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
856 assert(_work_list.index_of(cur) == -1, "block already in work list");
857
858 int cur_weight = compute_weight(cur);
859
860 // the linear_scan_number is used to cache the weight of a block
861 cur->set_linear_scan_number(cur_weight);
862
863 #ifndef PRODUCT
864 if (StressLinearScan) {
865 _work_list.insert_before(0, cur);
866 return;
867 }
868 #endif
869
870 _work_list.append(NULL); // provide space for new element
871
872 int insert_idx = _work_list.length() - 1;
873 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
874 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
875 insert_idx--;
876 }
877 _work_list.at_put(insert_idx, cur);
878
879 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
880 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()));
881
882 #ifdef ASSERT
883 for (int i = 0; i < _work_list.length(); i++) {
884 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
885 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
886 }
887 #endif
888 }
889
890 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
891 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()));
892 assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
893
894 // currently, the linear scan order and code emit order are equal.
895 // therefore the linear_scan_number and the weight of a block must also
896 // be equal.
897 cur->set_linear_scan_number(_linear_scan_order->length());
898 _linear_scan_order->append(cur);
899 }
900
901 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
902 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing final block order"));
903
904 // the start block is always the first block in the linear scan order
905 _linear_scan_order = new BlockList(_num_blocks);
906 append_block(start_block);
907
908 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
909 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
910 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
911
912 BlockBegin* sux_of_osr_entry = NULL;
913 if (osr_entry != NULL) {
914 // special handling for osr entry:
915 // ignore the edge between the osr entry and its successor for processing
916 // the osr entry block is added manually below
917 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
918 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");
919
920 sux_of_osr_entry = osr_entry->sux_at(0);
921 dec_forward_branches(sux_of_osr_entry);
922
923 compute_dominator(osr_entry, start_block);
924 _iterative_dominators = true;
925 }
926 compute_dominator(std_entry, start_block);
927
928 // start processing with standard entry block
929 assert(_work_list.is_empty(), "list must be empty before processing");
930
931 if (ready_for_processing(std_entry)) {
932 sort_into_work_list(std_entry);
933 } else {
934 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
935 }
936
937 do {
938 BlockBegin* cur = _work_list.pop();
939
940 if (cur == sux_of_osr_entry) {
941 // the osr entry block is ignored in normal processing, it is never added to the
942 // work list. Instead, it is added as late as possible manually here.
943 append_block(osr_entry);
944 compute_dominator(cur, osr_entry);
945 }
946 append_block(cur);
947
948 int i;
949 int num_sux = cur->number_of_sux();
950 // changed loop order to get "intuitive" order of if- and else-blocks
951 for (i = 0; i < num_sux; i++) {
952 BlockBegin* sux = cur->sux_at(i);
953 compute_dominator(sux, cur);
954 if (ready_for_processing(sux)) {
955 sort_into_work_list(sux);
956 }
957 }
958 num_sux = cur->number_of_exception_handlers();
959 for (i = 0; i < num_sux; i++) {
960 BlockBegin* sux = cur->exception_handler_at(i);
961 if (ready_for_processing(sux)) {
962 sort_into_work_list(sux);
963 }
964 }
965 } while (_work_list.length() > 0);
966 }
967
968
969 bool ComputeLinearScanOrder::compute_dominators_iter() {
970 bool changed = false;
971 int num_blocks = _linear_scan_order->length();
972
973 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
974 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
975 for (int i = 1; i < num_blocks; i++) {
976 BlockBegin* block = _linear_scan_order->at(i);
977
978 BlockBegin* dominator = block->pred_at(0);
979 int num_preds = block->number_of_preds();
980
981 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: Processing B%d", block->block_id()));
982
983 for (int j = 0; j < num_preds; j++) {
984
985 BlockBegin *pred = block->pred_at(j);
986 TRACE_LINEAR_SCAN(4, tty->print_cr(" DOM: Subrocessing B%d", pred->block_id()));
987
988 if (block->is_set(BlockBegin::exception_entry_flag)) {
989 dominator = common_dominator(dominator, pred);
990 int num_pred_preds = pred->number_of_preds();
991 for (int k = 0; k < num_pred_preds; k++) {
992 dominator = common_dominator(dominator, pred->pred_at(k));
993 }
994 } else {
995 dominator = common_dominator(dominator, pred);
996 }
997 }
998
999 if (dominator != block->dominator()) {
1000 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()));
1001
1002 block->set_dominator(dominator);
1003 changed = true;
1004 }
1005 }
1006 return changed;
1007 }
1008
1009 void ComputeLinearScanOrder::compute_dominators() {
1010 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
1011
1012 // iterative computation of dominators is only required for methods with non-natural loops
1013 // and OSR-methods. For all other methods, the dominators computed when generating the
1014 // linear scan block order are correct.
1015 if (_iterative_dominators) {
1016 do {
1017 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
1018 } while (compute_dominators_iter());
1019 }
1020
1021 // check that dominators are correct
1022 assert(!compute_dominators_iter(), "fix point not reached");
1023
1024 // Add Blocks to dominates-Array
1025 int num_blocks = _linear_scan_order->length();
1026 for (int i = 0; i < num_blocks; i++) {
1027 BlockBegin* block = _linear_scan_order->at(i);
1028
1029 BlockBegin *dom = block->dominator();
1030 if (dom) {
1031 assert(dom->dominator_depth() != -1, "Dominator must have been visited before");
1032 dom->dominates()->append(block);
1033 block->set_dominator_depth(dom->dominator_depth() + 1);
1034 } else {
1035 block->set_dominator_depth(0);
1036 }
1037 }
1038 }
1039
1040
1041 #ifndef PRODUCT
1042 void ComputeLinearScanOrder::print_blocks() {
1043 if (TraceLinearScanLevel >= 2) {
1044 tty->print_cr("----- loop information:");
1045 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1046 BlockBegin* cur = _linear_scan_order->at(block_idx);
1047
1048 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
1049 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1050 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
1051 }
1052 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
1053 }
1054 }
1055
1056 if (TraceLinearScanLevel >= 1) {
1057 tty->print_cr("----- linear-scan block order:");
1058 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1059 BlockBegin* cur = _linear_scan_order->at(block_idx);
1060 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
1061
1062 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
1063 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
1064 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
1065 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
1066
1067 if (cur->dominator() != NULL) {
1068 tty->print(" dom: B%d ", cur->dominator()->block_id());
1069 } else {
1070 tty->print(" dom: NULL ");
1071 }
1072
1073 if (cur->number_of_preds() > 0) {
1074 tty->print(" preds: ");
1075 for (int j = 0; j < cur->number_of_preds(); j++) {
1076 BlockBegin* pred = cur->pred_at(j);
1077 tty->print("B%d ", pred->block_id());
1078 }
1079 }
1080 if (cur->number_of_sux() > 0) {
1081 tty->print(" sux: ");
1082 for (int j = 0; j < cur->number_of_sux(); j++) {
1083 BlockBegin* sux = cur->sux_at(j);
1084 tty->print("B%d ", sux->block_id());
1085 }
1086 }
1087 if (cur->number_of_exception_handlers() > 0) {
1088 tty->print(" ex: ");
1089 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1090 BlockBegin* ex = cur->exception_handler_at(j);
1091 tty->print("B%d ", ex->block_id());
1092 }
1093 }
1094 tty->cr();
1095 }
1096 }
1097 }
1098 #endif
1099
1100 #ifdef ASSERT
1101 void ComputeLinearScanOrder::verify() {
1102 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1103
1104 if (StressLinearScan) {
1105 // blocks are scrambled when StressLinearScan is used
1106 return;
1107 }
1108
1109 // check that all successors of a block have a higher linear-scan-number
1110 // and that all predecessors of a block have a lower linear-scan-number
1111 // (only backward branches of loops are ignored)
1112 int i;
1113 for (i = 0; i < _linear_scan_order->length(); i++) {
1114 BlockBegin* cur = _linear_scan_order->at(i);
1115
1116 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1117 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
1118
1119 int j;
1120 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1121 BlockBegin* sux = cur->sux_at(j);
1122
1123 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
1124 if (!sux->is_set(BlockBegin::backward_branch_target_flag)) {
1125 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1126 }
1127 if (cur->loop_depth() == sux->loop_depth()) {
1128 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");
1129 }
1130 }
1131
1132 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1133 BlockBegin* pred = cur->pred_at(j);
1134
1135 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
1136 if (!cur->is_set(BlockBegin::backward_branch_target_flag)) {
1137 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1138 }
1139 if (cur->loop_depth() == pred->loop_depth()) {
1140 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");
1141 }
1142
1143 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1144 }
1145
1146 // check dominator
1147 if (i == 0) {
1148 assert(cur->dominator() == NULL, "first block has no dominator");
1149 } else {
1150 assert(cur->dominator() != NULL, "all but first block must have dominator");
1151 }
1152 // Assertion does not hold for exception handlers
1153 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");
1154 }
1155
1156 // check that all loops are continuous
1157 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1158 int block_idx = 0;
1159 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1160
1161 // skip blocks before the loop
1162 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1163 block_idx++;
1164 }
1165 // skip blocks of loop
1166 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1167 block_idx++;
1168 }
1169 // after the first non-loop block, there must not be another loop-block
1170 while (block_idx < _num_blocks) {
1171 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1172 block_idx++;
1173 }
1174 }
1175 }
1176 #endif
1177
1178
1179 void IR::compute_code() {
1180 assert(is_valid(), "IR must be valid");
1181
1182 ComputeLinearScanOrder compute_order(compilation(), start());
1183 _num_loops = compute_order.num_loops();
1184 _code = compute_order.linear_scan_order();
1185 }
1186
1187
1188 void IR::compute_use_counts() {
1189 // make sure all values coming out of this block get evaluated.
1190 int num_blocks = _code->length();
1191 for (int i = 0; i < num_blocks; i++) {
1192 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1193 }
1194
1195 // compute use counts
1196 UseCountComputer::compute(_code);
1197 }
1198
1199
1200 void IR::iterate_preorder(BlockClosure* closure) {
1201 assert(is_valid(), "IR must be valid");
1202 start()->iterate_preorder(closure);
1203 }
1204
1205
1206 void IR::iterate_postorder(BlockClosure* closure) {
1207 assert(is_valid(), "IR must be valid");
1208 start()->iterate_postorder(closure);
1209 }
1210
1211 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1212 linear_scan_order()->iterate_forward(closure);
1213 }
1214
1215
1216 #ifndef PRODUCT
1217 class BlockPrinter: public BlockClosure {
1218 private:
1219 InstructionPrinter* _ip;
1220 bool _cfg_only;
1221 bool _live_only;
1222
1223 public:
1224 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1225 _ip = ip;
1226 _cfg_only = cfg_only;
1227 _live_only = live_only;
1228 }
1229
1230 virtual void block_do(BlockBegin* block) {
1231 if (_cfg_only) {
1232 _ip->print_instr(block); tty->cr();
1233 } else {
1234 block->print_block(*_ip, _live_only);
1235 }
1236 }
1237 };
1238
1239
1240 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1241 ttyLocker ttyl;
1242 InstructionPrinter ip(!cfg_only);
1243 BlockPrinter bp(&ip, cfg_only, live_only);
1244 start->iterate_preorder(&bp);
1245 tty->cr();
1246 }
1247
1248 void IR::print(bool cfg_only, bool live_only) {
1249 if (is_valid()) {
1250 print(start(), cfg_only, live_only);
1251 } else {
1252 tty->print_cr("invalid IR");
1253 }
1254 }
1255
1256
1257 define_array(BlockListArray, BlockList*)
1258 define_stack(BlockListList, BlockListArray)
1259
1260 class PredecessorValidator : public BlockClosure {
1261 private:
1262 BlockListList* _predecessors;
1263 BlockList* _blocks;
1264
1265 static int cmp(BlockBegin** a, BlockBegin** b) {
1266 return (*a)->block_id() - (*b)->block_id();
1267 }
1268
1269 public:
1270 PredecessorValidator(IR* hir) {
1271 ResourceMark rm;
1272 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
1273 _blocks = new BlockList();
1274
1275 int i;
1276 hir->start()->iterate_preorder(this);
1277 if (hir->code() != NULL) {
1278 assert(hir->code()->length() == _blocks->length(), "must match");
1279 for (i = 0; i < _blocks->length(); i++) {
1280 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1281 }
1282 }
1283
1284 for (i = 0; i < _blocks->length(); i++) {
1285 BlockBegin* block = _blocks->at(i);
1286 BlockList* preds = _predecessors->at(block->block_id());
1287 if (preds == NULL) {
1288 assert(block->number_of_preds() == 0, "should be the same");
1289 continue;
1290 }
1291
1292 // clone the pred list so we can mutate it
1293 BlockList* pred_copy = new BlockList();
1294 int j;
1295 for (j = 0; j < block->number_of_preds(); j++) {
1296 pred_copy->append(block->pred_at(j));
1297 }
1298 // sort them in the same order
1299 preds->sort(cmp);
1300 pred_copy->sort(cmp);
1301 int length = MIN2(preds->length(), block->number_of_preds());
1302 for (j = 0; j < block->number_of_preds(); j++) {
1303 assert(preds->at(j) == pred_copy->at(j), "must match");
1304 }
1305
1306 assert(preds->length() == block->number_of_preds(), "should be the same");
1307 }
1308 }
1309
1310 virtual void block_do(BlockBegin* block) {
1311 _blocks->append(block);
1312 BlockEnd* be = block->end();
1313 int n = be->number_of_sux();
1314 int i;
1315 for (i = 0; i < n; i++) {
1316 BlockBegin* sux = be->sux_at(i);
1317 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1318
1319 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1320 if (preds == NULL) {
1321 preds = new BlockList();
1322 _predecessors->at_put(sux->block_id(), preds);
1323 }
1324 preds->append(block);
1325 }
1326
1327 n = block->number_of_exception_handlers();
1328 for (i = 0; i < n; i++) {
1329 BlockBegin* sux = block->exception_handler_at(i);
1330 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1331
1332 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1333 if (preds == NULL) {
1334 preds = new BlockList();
1335 _predecessors->at_put(sux->block_id(), preds);
1336 }
1337 preds->append(block);
1338 }
1339 }
1340 };
1341
1342 class VerifyBlockBeginField : public BlockClosure {
1343
1344 public:
1345
1346 virtual void block_do(BlockBegin *block) {
1347 for ( Instruction *cur = block; cur != NULL; cur = cur->next()) {
1348 assert(cur->block() == block, "Block begin is not correct");
1349 }
1350 }
1351 };
1352
1353 void IR::verify() {
1354 #ifdef ASSERT
1355 PredecessorValidator pv(this);
1356 VerifyBlockBeginField verifier;
1357 this->iterate_postorder(&verifier);
1358 #endif
1359 }
1360
1361 #endif // PRODUCT
1362
1363 void SubstitutionResolver::visit(Value* v) {
1364 Value v0 = *v;
1365 if (v0) {
1366 Value vs = v0->subst();
1367 if (vs != v0) {
1368 *v = v0->subst();
1369 }
1370 }
1371 }
1372
1373 #ifdef ASSERT
1374 class SubstitutionChecker: public ValueVisitor {
1375 void visit(Value* v) {
1376 Value v0 = *v;
1377 if (v0) {
1378 Value vs = v0->subst();
1379 assert(vs == v0, "missed substitution");
1380 }
1381 }
1382 };
1383 #endif
1384
1385
1386 void SubstitutionResolver::block_do(BlockBegin* block) {
1387 Instruction* last = NULL;
1388 for (Instruction* n = block; n != NULL;) {
1389 n->values_do(this);
1390 // need to remove this instruction from the instruction stream
1391 if (n->subst() != n) {
1392 assert(last != NULL, "must have last");
1393 last->set_next(n->next());
1394 } else {
1395 last = n;
1396 }
1397 n = last->next();
1398 }
1399
1400 #ifdef ASSERT
1401 SubstitutionChecker check_substitute;
1402 if (block->state()) block->state()->values_do(&check_substitute);
1403 block->block_values_do(&check_substitute);
1404 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
1405 #endif
1406 }