1 /*
2 * Copyright (c) 1999, 2013, 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 _start = NULL;
147
148 if (osr_bci == -1) {
149 _requires_phi_function.clear();
150 } else {
151 // selective creation of phi functions is not possibel in osr-methods
152 _requires_phi_function.set_range(0, method->max_locals());
153 }
154
155 assert(method->holder()->is_loaded() , "method holder must be loaded");
156
157 // build graph if monitor pairing is ok
158 if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci);
159 }
160
161
162 int IRScope::max_stack() const {
163 int my_max = method()->max_stack();
164 int callee_max = 0;
165 for (int i = 0; i < number_of_callees(); i++) {
166 callee_max = MAX2(callee_max, callee_no(i)->max_stack());
167 }
168 return my_max + callee_max;
169 }
170
171
172 bool IRScopeDebugInfo::should_reexecute() {
173 ciMethod* cur_method = scope()->method();
174 int cur_bci = bci();
175 if (cur_method != NULL && cur_bci != SynchronizationEntryBCI) {
176 Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci);
177 return Interpreter::bytecode_should_reexecute(code);
178 } else
179 return false;
180 }
181
182
183 // Implementation of CodeEmitInfo
184
185 // Stack must be NON-null
186 CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers, bool deoptimize_on_exception)
187 : _scope(stack->scope())
188 , _scope_debug_info(NULL)
189 , _oop_map(NULL)
190 , _stack(stack)
191 , _exception_handlers(exception_handlers)
192 , _is_method_handle_invoke(false)
193 , _deoptimize_on_exception(deoptimize_on_exception) {
194 assert(_stack != NULL, "must be non null");
195 }
196
197
198 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack)
199 : _scope(info->_scope)
200 , _exception_handlers(NULL)
201 , _scope_debug_info(NULL)
202 , _oop_map(NULL)
203 , _stack(stack == NULL ? info->_stack : stack)
204 , _is_method_handle_invoke(info->_is_method_handle_invoke)
205 , _deoptimize_on_exception(info->_deoptimize_on_exception) {
206
207 // deep copy of exception handlers
208 if (info->_exception_handlers != NULL) {
209 _exception_handlers = new XHandlers(info->_exception_handlers);
210 }
211 }
212
213
214 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) {
215 // record the safepoint before recording the debug info for enclosing scopes
216 recorder->add_safepoint(pc_offset, _oop_map->deep_copy());
217 _scope_debug_info->record_debug_info(recorder, pc_offset, true/*topmost*/, _is_method_handle_invoke);
218 recorder->end_safepoint(pc_offset);
219 }
220
221
222 void CodeEmitInfo::add_register_oop(LIR_Opr opr) {
223 assert(_oop_map != NULL, "oop map must already exist");
224 assert(opr->is_single_cpu(), "should not call otherwise");
225
226 VMReg name = frame_map()->regname(opr);
227 _oop_map->set_oop(name);
228 }
229
230 // Mirror the stack size calculation in the deopt code
231 // How much stack space would we need at this point in the program in
232 // case of deoptimization?
233 int CodeEmitInfo::interpreter_frame_size() const {
234 ValueStack* state = _stack;
235 int size = 0;
236 int callee_parameters = 0;
237 int callee_locals = 0;
238 int extra_args = state->scope()->method()->max_stack() - state->stack_size();
239
240 while (state != NULL) {
241 int locks = state->locks_size();
242 int temps = state->stack_size();
243 bool is_top_frame = (state == _stack);
244 ciMethod* method = state->scope()->method();
245
246 int frame_size = BytesPerWord * Interpreter::size_activation(method->max_stack(),
247 temps + callee_parameters,
248 extra_args,
249 locks,
250 callee_parameters,
251 callee_locals,
252 is_top_frame);
253 size += frame_size;
254
255 callee_parameters = method->size_of_parameters();
256 callee_locals = method->max_locals();
257 extra_args = 0;
258 state = state->caller_state();
259 }
260 return size + Deoptimization::last_frame_adjust(0, callee_locals) * BytesPerWord;
261 }
262
263 // Implementation of IR
264
265 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) :
266 _num_loops(0) {
267 // setup IR fields
268 _compilation = compilation;
269 _top_scope = new IRScope(compilation, NULL, -1, method, osr_bci, true);
270 _code = NULL;
271 }
272
273
274 void IR::optimize_blocks() {
275 Optimizer opt(this);
276 if (!compilation()->profile_branches()) {
277 if (DoCEE) {
278 opt.eliminate_conditional_expressions();
279 #ifndef PRODUCT
280 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
281 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
282 #endif
283 }
284 if (EliminateBlocks) {
285 opt.eliminate_blocks();
286 #ifndef PRODUCT
287 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
288 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
289 #endif
290 }
291 }
292 }
293
294 void IR::eliminate_null_checks() {
295 Optimizer opt(this);
296 if (EliminateNullChecks) {
297 opt.eliminate_null_checks();
298 #ifndef PRODUCT
299 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
300 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
301 #endif
302 }
303 }
304
305
306 static int sort_pairs(BlockPair** a, BlockPair** b) {
307 if ((*a)->from() == (*b)->from()) {
308 return (*a)->to()->block_id() - (*b)->to()->block_id();
309 } else {
310 return (*a)->from()->block_id() - (*b)->from()->block_id();
311 }
312 }
313
314
315 class CriticalEdgeFinder: public BlockClosure {
316 BlockPairList blocks;
317 IR* _ir;
318
319 public:
320 CriticalEdgeFinder(IR* ir): _ir(ir) {}
321 void block_do(BlockBegin* bb) {
322 BlockEnd* be = bb->end();
323 int nos = be->number_of_sux();
324 if (nos >= 2) {
325 for (int i = 0; i < nos; i++) {
326 BlockBegin* sux = be->sux_at(i);
327 if (sux->number_of_preds() >= 2) {
328 blocks.append(new BlockPair(bb, sux));
329 }
330 }
331 }
332 }
333
334 void split_edges() {
335 BlockPair* last_pair = NULL;
336 blocks.sort(sort_pairs);
337 for (int i = 0; i < blocks.length(); i++) {
338 BlockPair* pair = blocks.at(i);
339 if (last_pair != NULL && pair->is_same(last_pair)) continue;
340 BlockBegin* from = pair->from();
341 BlockBegin* to = pair->to();
342 BlockBegin* split = from->insert_block_between(to);
343 #ifndef PRODUCT
344 if ((PrintIR || PrintIR1) && Verbose) {
345 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
346 from->block_id(), to->block_id(), split->block_id());
347 }
348 #endif
349 last_pair = pair;
350 }
351 }
352 };
353
354 void IR::split_critical_edges() {
355 CriticalEdgeFinder cef(this);
356
357 iterate_preorder(&cef);
358 cef.split_edges();
359 }
360
361
362 class UseCountComputer: public ValueVisitor, BlockClosure {
363 private:
364 void visit(Value* n) {
365 // Local instructions and Phis for expression stack values at the
366 // start of basic blocks are not added to the instruction list
367 if (!(*n)->is_linked() && (*n)->can_be_linked()) {
368 assert(false, "a node was not appended to the graph");
369 Compilation::current()->bailout("a node was not appended to the graph");
370 }
371 // use n's input if not visited before
372 if (!(*n)->is_pinned() && !(*n)->has_uses()) {
373 // note: a) if the instruction is pinned, it will be handled by compute_use_count
374 // b) if the instruction has uses, it was touched before
375 // => in both cases we don't need to update n's values
376 uses_do(n);
377 }
378 // use n
379 (*n)->_use_count++;
380 }
381
382 Values* worklist;
383 int depth;
384 enum {
385 max_recurse_depth = 20
386 };
387
388 void uses_do(Value* n) {
389 depth++;
390 if (depth > max_recurse_depth) {
391 // don't allow the traversal to recurse too deeply
392 worklist->push(*n);
393 } else {
394 (*n)->input_values_do(this);
395 // special handling for some instructions
396 if ((*n)->as_BlockEnd() != NULL) {
397 // note on BlockEnd:
398 // must 'use' the stack only if the method doesn't
399 // terminate, however, in those cases stack is empty
400 (*n)->state_values_do(this);
401 }
402 }
403 depth--;
404 }
405
406 void block_do(BlockBegin* b) {
407 depth = 0;
408 // process all pinned nodes as the roots of expression trees
409 for (Instruction* n = b; n != NULL; n = n->next()) {
410 if (n->is_pinned()) uses_do(&n);
411 }
412 assert(depth == 0, "should have counted back down");
413
414 // now process any unpinned nodes which recursed too deeply
415 while (worklist->length() > 0) {
416 Value t = worklist->pop();
417 if (!t->is_pinned()) {
418 // compute the use count
419 uses_do(&t);
420
421 // pin the instruction so that LIRGenerator doesn't recurse
422 // too deeply during it's evaluation.
423 t->pin();
424 }
425 }
426 assert(depth == 0, "should have counted back down");
427 }
428
429 UseCountComputer() {
430 worklist = new Values();
431 depth = 0;
432 }
433
434 public:
435 static void compute(BlockList* blocks) {
436 UseCountComputer ucc;
437 blocks->iterate_backward(&ucc);
438 }
439 };
440
441
442 // helper macro for short definition of trace-output inside code
443 #ifndef PRODUCT
444 #define TRACE_LINEAR_SCAN(level, code) \
445 if (TraceLinearScanLevel >= level) { \
446 code; \
447 }
448 #else
449 #define TRACE_LINEAR_SCAN(level, code)
450 #endif
451
452 class ComputeLinearScanOrder : public StackObj {
453 private:
454 int _max_block_id; // the highest block_id of a block
455 int _num_blocks; // total number of blocks (smaller than _max_block_id)
456 int _num_loops; // total number of loops
457 bool _iterative_dominators;// method requires iterative computation of dominatiors
458
459 BlockList* _linear_scan_order; // the resulting list of blocks in correct order
460
461 BitMap _visited_blocks; // used for recursive processing of blocks
462 BitMap _active_blocks; // used for recursive processing of blocks
463 BitMap _dominator_blocks; // temproary BitMap used for computation of dominator
464 intArray _forward_branches; // number of incoming forward branches for each block
465 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges
466 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop
467 BlockList _work_list; // temporary list (used in mark_loops and compute_order)
468 BlockList _loop_headers;
469
470 Compilation* _compilation;
471
472 // accessors for _visited_blocks and _active_blocks
473 void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); }
474 bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); }
475 bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); }
476 void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); }
477 void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); }
478 void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); }
479
480 // accessors for _forward_branches
481 void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); }
482 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()); }
483
484 // accessors for _loop_map
485 bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); }
486 void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); }
487 void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); }
488
489 // count edges between blocks
490 void count_edges(BlockBegin* cur, BlockBegin* parent);
491
492 // loop detection
493 void mark_loops();
494 void clear_non_natural_loops(BlockBegin* start_block);
495 void assign_loop_depth(BlockBegin* start_block);
496
497 // computation of final block order
498 BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b);
499 void compute_dominator(BlockBegin* cur, BlockBegin* parent);
500 int compute_weight(BlockBegin* cur);
501 bool ready_for_processing(BlockBegin* cur);
502 void sort_into_work_list(BlockBegin* b);
503 void append_block(BlockBegin* cur);
504 void compute_order(BlockBegin* start_block);
505
506 // fixup of dominators for non-natural loops
507 bool compute_dominators_iter();
508 void compute_dominators();
509
510 // debug functions
511 NOT_PRODUCT(void print_blocks();)
512 DEBUG_ONLY(void verify();)
513
514 Compilation* compilation() const { return _compilation; }
515 public:
516 ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block);
517
518 // accessors for final result
519 BlockList* linear_scan_order() const { return _linear_scan_order; }
520 int num_loops() const { return _num_loops; }
521 };
522
523
524 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) :
525 _max_block_id(BlockBegin::number_of_blocks()),
526 _num_blocks(0),
527 _num_loops(0),
528 _iterative_dominators(false),
529 _visited_blocks(_max_block_id),
530 _active_blocks(_max_block_id),
531 _dominator_blocks(_max_block_id),
532 _forward_branches(_max_block_id, 0),
533 _loop_end_blocks(8),
534 _work_list(8),
535 _linear_scan_order(NULL), // initialized later with correct size
536 _loop_map(0, 0), // initialized later with correct size
537 _compilation(c)
538 {
539 TRACE_LINEAR_SCAN(2, tty->print_cr("***** computing linear-scan block order"));
540
541 init_visited();
542 count_edges(start_block, NULL);
543
544 if (compilation()->is_profiling()) {
545 ciMethod *method = compilation()->method();
546 if (!method->is_accessor()) {
547 ciMethodData* md = method->method_data_or_null();
548 assert(md != NULL, "Sanity");
549 md->set_compilation_stats(_num_loops, _num_blocks);
550 }
551 }
552
553 if (_num_loops > 0) {
554 mark_loops();
555 clear_non_natural_loops(start_block);
556 assign_loop_depth(start_block);
557 }
558
559 compute_order(start_block);
560 compute_dominators();
561
562 NOT_PRODUCT(print_blocks());
563 DEBUG_ONLY(verify());
564 }
565
566
567 // Traverse the CFG:
568 // * count total number of blocks
569 // * count all incoming edges and backward incoming edges
570 // * number loop header blocks
571 // * create a list with all loop end blocks
572 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
573 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));
574 assert(cur->dominator() == NULL, "dominator already initialized");
575
576 if (is_active(cur)) {
577 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
578 assert(is_visited(cur), "block must be visisted when block is active");
579 assert(parent != NULL, "must have parent");
580
581 cur->set(BlockBegin::linear_scan_loop_header_flag);
582 cur->set(BlockBegin::backward_branch_target_flag);
583
584 parent->set(BlockBegin::linear_scan_loop_end_flag);
585
586 // When a loop header is also the start of an exception handler, then the backward branch is
587 // an exception edge. Because such edges are usually critical edges which cannot be split, the
588 // loop must be excluded here from processing.
589 if (cur->is_set(BlockBegin::exception_entry_flag)) {
590 // Make sure that dominators are correct in this weird situation
591 _iterative_dominators = true;
592 return;
593 }
594 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
595 "loop end blocks must have one successor (critical edges are split)");
596
597 _loop_end_blocks.append(parent);
598 return;
599 }
600
601 // increment number of incoming forward branches
602 inc_forward_branches(cur);
603
604 if (is_visited(cur)) {
605 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
606 return;
607 }
608
609 _num_blocks++;
610 set_visited(cur);
611 set_active(cur);
612
613 // recursive call for all successors
614 int i;
615 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
616 count_edges(cur->sux_at(i), cur);
617 }
618 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
619 count_edges(cur->exception_handler_at(i), cur);
620 }
621
622 clear_active(cur);
623
624 // Each loop has a unique number.
625 // When multiple loops are nested, assign_loop_depth assumes that the
626 // innermost loop has the lowest number. This is guaranteed by setting
627 // the loop number after the recursive calls for the successors above
628 // have returned.
629 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
630 assert(cur->loop_index() == -1, "cannot set loop-index twice");
631 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
632
633 cur->set_loop_index(_num_loops);
634 _loop_headers.append(cur);
635 _num_loops++;
636 }
637
638 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
639 }
640
641
642 void ComputeLinearScanOrder::mark_loops() {
643 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
644
645 _loop_map = BitMap2D(_num_loops, _max_block_id);
646 _loop_map.clear();
647
648 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
649 BlockBegin* loop_end = _loop_end_blocks.at(i);
650 BlockBegin* loop_start = loop_end->sux_at(0);
651 int loop_idx = loop_start->loop_index();
652
653 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));
654 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
655 assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
656 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
657 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
658 assert(_work_list.is_empty(), "work list must be empty before processing");
659
660 // add the end-block of the loop to the working list
661 _work_list.push(loop_end);
662 set_block_in_loop(loop_idx, loop_end);
663 do {
664 BlockBegin* cur = _work_list.pop();
665
666 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id()));
667 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
668
669 // recursive processing of all predecessors ends when start block of loop is reached
670 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
671 for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
672 BlockBegin* pred = cur->pred_at(j);
673
674 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
675 // this predecessor has not been processed yet, so add it to work list
676 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id()));
677 _work_list.push(pred);
678 set_block_in_loop(loop_idx, pred);
679 }
680 }
681 }
682 } while (!_work_list.is_empty());
683 }
684 }
685
686
687 // check for non-natural loops (loops where the loop header does not dominate
688 // all other loop blocks = loops with mulitple entries).
689 // such loops are ignored
690 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
691 for (int i = _num_loops - 1; i >= 0; i--) {
692 if (is_block_in_loop(i, start_block)) {
693 // loop i contains the entry block of the method
694 // -> this is not a natural loop, so ignore it
695 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
696
697 BlockBegin *loop_header = _loop_headers.at(i);
698 assert(loop_header->is_set(BlockBegin::linear_scan_loop_header_flag), "Must be loop header");
699
700 for (int j = 0; j < loop_header->number_of_preds(); j++) {
701 BlockBegin *pred = loop_header->pred_at(j);
702 pred->clear(BlockBegin::linear_scan_loop_end_flag);
703 }
704
705 loop_header->clear(BlockBegin::linear_scan_loop_header_flag);
706
707 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
708 clear_block_in_loop(i, block_id);
709 }
710 _iterative_dominators = true;
711 }
712 }
713 }
714
715 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
716 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing loop-depth and weight"));
717 init_visited();
718
719 assert(_work_list.is_empty(), "work list must be empty before processing");
720 _work_list.append(start_block);
721
722 do {
723 BlockBegin* cur = _work_list.pop();
724
725 if (!is_visited(cur)) {
726 set_visited(cur);
727 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
728
729 // compute loop-depth and loop-index for the block
730 assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
731 int i;
732 int loop_depth = 0;
733 int min_loop_idx = -1;
734 for (i = _num_loops - 1; i >= 0; i--) {
735 if (is_block_in_loop(i, cur)) {
736 loop_depth++;
737 min_loop_idx = i;
738 }
739 }
740 cur->set_loop_depth(loop_depth);
741 cur->set_loop_index(min_loop_idx);
742
743 // append all unvisited successors to work list
744 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
745 _work_list.append(cur->sux_at(i));
746 }
747 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
748 _work_list.append(cur->exception_handler_at(i));
749 }
750 }
751 } while (!_work_list.is_empty());
752 }
753
754
755 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
756 assert(a != NULL && b != NULL, "must have input blocks");
757
758 _dominator_blocks.clear();
759 while (a != NULL) {
760 _dominator_blocks.set_bit(a->block_id());
761 assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
762 a = a->dominator();
763 }
764 while (b != NULL && !_dominator_blocks.at(b->block_id())) {
765 assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
766 b = b->dominator();
767 }
768
769 assert(b != NULL, "could not find dominator");
770 return b;
771 }
772
773 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
774 if (cur->dominator() == NULL) {
775 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
776 cur->set_dominator(parent);
777
778 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
779 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()));
780 // Does not hold for exception blocks
781 assert(cur->number_of_preds() > 1 || cur->is_set(BlockBegin::exception_entry_flag), "");
782 cur->set_dominator(common_dominator(cur->dominator(), parent));
783 }
784
785 // Additional edge to xhandler of all our successors
786 // range check elimination needs that the state at the end of a
787 // block be valid in every block it dominates so cur must dominate
788 // the exception handlers of its successors.
789 int num_cur_xhandler = cur->number_of_exception_handlers();
790 for (int j = 0; j < num_cur_xhandler; j++) {
791 BlockBegin* xhandler = cur->exception_handler_at(j);
792 compute_dominator(xhandler, parent);
793 }
794 }
795
796
797 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
798 BlockBegin* single_sux = NULL;
799 if (cur->number_of_sux() == 1) {
800 single_sux = cur->sux_at(0);
801 }
802
803 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
804 int weight = (cur->loop_depth() & 0x7FFF) << 16;
805
806 // general macro for short definition of weight flags
807 // the first instance of INC_WEIGHT_IF has the highest priority
808 int cur_bit = 15;
809 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
810
811 // this is necessery for the (very rare) case that two successing blocks have
812 // the same loop depth, but a different loop index (can happen for endless loops
813 // with exception handlers)
814 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
815
816 // loop end blocks (blocks that end with a backward branch) are added
817 // after all other blocks of the loop.
818 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
819
820 // critical edge split blocks are prefered because than they have a bigger
821 // proability to be completely empty
822 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
823
824 // exceptions should not be thrown in normal control flow, so these blocks
825 // are added as late as possible
826 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL));
827 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
828
829 // exceptions handlers are added as late as possible
830 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
831
832 // guarantee that weight is > 0
833 weight |= 1;
834
835 #undef INC_WEIGHT_IF
836 assert(cur_bit >= 0, "too many flags");
837 assert(weight > 0, "weight cannot become negative");
838
839 return weight;
840 }
841
842 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
843 // Discount the edge just traveled.
844 // When the number drops to zero, all forward branches were processed
845 if (dec_forward_branches(cur) != 0) {
846 return false;
847 }
848
849 assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
850 assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
851 return true;
852 }
853
854 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
855 assert(_work_list.index_of(cur) == -1, "block already in work list");
856
857 int cur_weight = compute_weight(cur);
858
859 // the linear_scan_number is used to cache the weight of a block
860 cur->set_linear_scan_number(cur_weight);
861
862 #ifndef PRODUCT
863 if (StressLinearScan) {
864 _work_list.insert_before(0, cur);
865 return;
866 }
867 #endif
868
869 _work_list.append(NULL); // provide space for new element
870
871 int insert_idx = _work_list.length() - 1;
872 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
873 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
874 insert_idx--;
875 }
876 _work_list.at_put(insert_idx, cur);
877
878 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
879 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()));
880
881 #ifdef ASSERT
882 for (int i = 0; i < _work_list.length(); i++) {
883 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
884 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
885 }
886 #endif
887 }
888
889 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
890 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()));
891 assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
892
893 // currently, the linear scan order and code emit order are equal.
894 // therefore the linear_scan_number and the weight of a block must also
895 // be equal.
896 cur->set_linear_scan_number(_linear_scan_order->length());
897 _linear_scan_order->append(cur);
898 }
899
900 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
901 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing final block order"));
902
903 // the start block is always the first block in the linear scan order
904 _linear_scan_order = new BlockList(_num_blocks);
905 append_block(start_block);
906
907 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
908 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
909 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
910
911 BlockBegin* sux_of_osr_entry = NULL;
912 if (osr_entry != NULL) {
913 // special handling for osr entry:
914 // ignore the edge between the osr entry and its successor for processing
915 // the osr entry block is added manually below
916 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
917 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");
918
919 sux_of_osr_entry = osr_entry->sux_at(0);
920 dec_forward_branches(sux_of_osr_entry);
921
922 compute_dominator(osr_entry, start_block);
923 _iterative_dominators = true;
924 }
925 compute_dominator(std_entry, start_block);
926
927 // start processing with standard entry block
928 assert(_work_list.is_empty(), "list must be empty before processing");
929
930 if (ready_for_processing(std_entry)) {
931 sort_into_work_list(std_entry);
932 } else {
933 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
934 }
935
936 do {
937 BlockBegin* cur = _work_list.pop();
938
939 if (cur == sux_of_osr_entry) {
940 // the osr entry block is ignored in normal processing, it is never added to the
941 // work list. Instead, it is added as late as possible manually here.
942 append_block(osr_entry);
943 compute_dominator(cur, osr_entry);
944 }
945 append_block(cur);
946
947 int i;
948 int num_sux = cur->number_of_sux();
949 // changed loop order to get "intuitive" order of if- and else-blocks
950 for (i = 0; i < num_sux; i++) {
951 BlockBegin* sux = cur->sux_at(i);
952 compute_dominator(sux, cur);
953 if (ready_for_processing(sux)) {
954 sort_into_work_list(sux);
955 }
956 }
957 num_sux = cur->number_of_exception_handlers();
958 for (i = 0; i < num_sux; i++) {
959 BlockBegin* sux = cur->exception_handler_at(i);
960 if (ready_for_processing(sux)) {
961 sort_into_work_list(sux);
962 }
963 }
964 } while (_work_list.length() > 0);
965 }
966
967
968 bool ComputeLinearScanOrder::compute_dominators_iter() {
969 bool changed = false;
970 int num_blocks = _linear_scan_order->length();
971
972 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
973 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
974 for (int i = 1; i < num_blocks; i++) {
975 BlockBegin* block = _linear_scan_order->at(i);
976
977 BlockBegin* dominator = block->pred_at(0);
978 int num_preds = block->number_of_preds();
979
980 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: Processing B%d", block->block_id()));
981
982 for (int j = 0; j < num_preds; j++) {
983
984 BlockBegin *pred = block->pred_at(j);
985 TRACE_LINEAR_SCAN(4, tty->print_cr(" DOM: Subrocessing B%d", pred->block_id()));
986
987 if (block->is_set(BlockBegin::exception_entry_flag)) {
988 dominator = common_dominator(dominator, pred);
989 int num_pred_preds = pred->number_of_preds();
990 for (int k = 0; k < num_pred_preds; k++) {
991 dominator = common_dominator(dominator, pred->pred_at(k));
992 }
993 } else {
994 dominator = common_dominator(dominator, pred);
995 }
996 }
997
998 if (dominator != block->dominator()) {
999 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()));
1000
1001 block->set_dominator(dominator);
1002 changed = true;
1003 }
1004 }
1005 return changed;
1006 }
1007
1008 void ComputeLinearScanOrder::compute_dominators() {
1009 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
1010
1011 // iterative computation of dominators is only required for methods with non-natural loops
1012 // and OSR-methods. For all other methods, the dominators computed when generating the
1013 // linear scan block order are correct.
1014 if (_iterative_dominators) {
1015 do {
1016 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
1017 } while (compute_dominators_iter());
1018 }
1019
1020 // check that dominators are correct
1021 assert(!compute_dominators_iter(), "fix point not reached");
1022
1023 // Add Blocks to dominates-Array
1024 int num_blocks = _linear_scan_order->length();
1025 for (int i = 0; i < num_blocks; i++) {
1026 BlockBegin* block = _linear_scan_order->at(i);
1027
1028 BlockBegin *dom = block->dominator();
1029 if (dom) {
1030 assert(dom->dominator_depth() != -1, "Dominator must have been visited before");
1031 dom->dominates()->append(block);
1032 block->set_dominator_depth(dom->dominator_depth() + 1);
1033 } else {
1034 block->set_dominator_depth(0);
1035 }
1036 }
1037 }
1038
1039
1040 #ifndef PRODUCT
1041 void ComputeLinearScanOrder::print_blocks() {
1042 if (TraceLinearScanLevel >= 2) {
1043 tty->print_cr("----- loop information:");
1044 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1045 BlockBegin* cur = _linear_scan_order->at(block_idx);
1046
1047 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
1048 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1049 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
1050 }
1051 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
1052 }
1053 }
1054
1055 if (TraceLinearScanLevel >= 1) {
1056 tty->print_cr("----- linear-scan block order:");
1057 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1058 BlockBegin* cur = _linear_scan_order->at(block_idx);
1059 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
1060
1061 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
1062 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
1063 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
1064 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
1065
1066 if (cur->dominator() != NULL) {
1067 tty->print(" dom: B%d ", cur->dominator()->block_id());
1068 } else {
1069 tty->print(" dom: NULL ");
1070 }
1071
1072 if (cur->number_of_preds() > 0) {
1073 tty->print(" preds: ");
1074 for (int j = 0; j < cur->number_of_preds(); j++) {
1075 BlockBegin* pred = cur->pred_at(j);
1076 tty->print("B%d ", pred->block_id());
1077 }
1078 }
1079 if (cur->number_of_sux() > 0) {
1080 tty->print(" sux: ");
1081 for (int j = 0; j < cur->number_of_sux(); j++) {
1082 BlockBegin* sux = cur->sux_at(j);
1083 tty->print("B%d ", sux->block_id());
1084 }
1085 }
1086 if (cur->number_of_exception_handlers() > 0) {
1087 tty->print(" ex: ");
1088 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1089 BlockBegin* ex = cur->exception_handler_at(j);
1090 tty->print("B%d ", ex->block_id());
1091 }
1092 }
1093 tty->cr();
1094 }
1095 }
1096 }
1097 #endif
1098
1099 #ifdef ASSERT
1100 void ComputeLinearScanOrder::verify() {
1101 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1102
1103 if (StressLinearScan) {
1104 // blocks are scrambled when StressLinearScan is used
1105 return;
1106 }
1107
1108 // check that all successors of a block have a higher linear-scan-number
1109 // and that all predecessors of a block have a lower linear-scan-number
1110 // (only backward branches of loops are ignored)
1111 int i;
1112 for (i = 0; i < _linear_scan_order->length(); i++) {
1113 BlockBegin* cur = _linear_scan_order->at(i);
1114
1115 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1116 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
1117
1118 int j;
1119 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1120 BlockBegin* sux = cur->sux_at(j);
1121
1122 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
1123 if (!sux->is_set(BlockBegin::backward_branch_target_flag)) {
1124 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1125 }
1126 if (cur->loop_depth() == sux->loop_depth()) {
1127 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");
1128 }
1129 }
1130
1131 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1132 BlockBegin* pred = cur->pred_at(j);
1133
1134 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
1135 if (!cur->is_set(BlockBegin::backward_branch_target_flag)) {
1136 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1137 }
1138 if (cur->loop_depth() == pred->loop_depth()) {
1139 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");
1140 }
1141
1142 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1143 }
1144
1145 // check dominator
1146 if (i == 0) {
1147 assert(cur->dominator() == NULL, "first block has no dominator");
1148 } else {
1149 assert(cur->dominator() != NULL, "all but first block must have dominator");
1150 }
1151 // Assertion does not hold for exception handlers
1152 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");
1153 }
1154
1155 // check that all loops are continuous
1156 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1157 int block_idx = 0;
1158 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1159
1160 // skip blocks before the loop
1161 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1162 block_idx++;
1163 }
1164 // skip blocks of loop
1165 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1166 block_idx++;
1167 }
1168 // after the first non-loop block, there must not be another loop-block
1169 while (block_idx < _num_blocks) {
1170 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1171 block_idx++;
1172 }
1173 }
1174 }
1175 #endif
1176
1177
1178 void IR::compute_code() {
1179 assert(is_valid(), "IR must be valid");
1180
1181 ComputeLinearScanOrder compute_order(compilation(), start());
1182 _num_loops = compute_order.num_loops();
1183 _code = compute_order.linear_scan_order();
1184 }
1185
1186
1187 void IR::compute_use_counts() {
1188 // make sure all values coming out of this block get evaluated.
1189 int num_blocks = _code->length();
1190 for (int i = 0; i < num_blocks; i++) {
1191 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1192 }
1193
1194 // compute use counts
1195 UseCountComputer::compute(_code);
1196 }
1197
1198
1199 void IR::iterate_preorder(BlockClosure* closure) {
1200 assert(is_valid(), "IR must be valid");
1201 start()->iterate_preorder(closure);
1202 }
1203
1204
1205 void IR::iterate_postorder(BlockClosure* closure) {
1206 assert(is_valid(), "IR must be valid");
1207 start()->iterate_postorder(closure);
1208 }
1209
1210 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1211 linear_scan_order()->iterate_forward(closure);
1212 }
1213
1214
1215 #ifndef PRODUCT
1216 class BlockPrinter: public BlockClosure {
1217 private:
1218 InstructionPrinter* _ip;
1219 bool _cfg_only;
1220 bool _live_only;
1221
1222 public:
1223 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1224 _ip = ip;
1225 _cfg_only = cfg_only;
1226 _live_only = live_only;
1227 }
1228
1229 virtual void block_do(BlockBegin* block) {
1230 if (_cfg_only) {
1231 _ip->print_instr(block); tty->cr();
1232 } else {
1233 block->print_block(*_ip, _live_only);
1234 }
1235 }
1236 };
1237
1238
1239 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1240 ttyLocker ttyl;
1241 InstructionPrinter ip(!cfg_only);
1242 BlockPrinter bp(&ip, cfg_only, live_only);
1243 start->iterate_preorder(&bp);
1244 tty->cr();
1245 }
1246
1247 void IR::print(bool cfg_only, bool live_only) {
1248 if (is_valid()) {
1249 print(start(), cfg_only, live_only);
1250 } else {
1251 tty->print_cr("invalid IR");
1252 }
1253 }
1254
1255
1256 define_array(BlockListArray, BlockList*)
1257 define_stack(BlockListList, BlockListArray)
1258
1259 class PredecessorValidator : public BlockClosure {
1260 private:
1261 BlockListList* _predecessors;
1262 BlockList* _blocks;
1263
1264 static int cmp(BlockBegin** a, BlockBegin** b) {
1265 return (*a)->block_id() - (*b)->block_id();
1266 }
1267
1268 public:
1269 PredecessorValidator(IR* hir) {
1270 ResourceMark rm;
1271 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
1272 _blocks = new BlockList();
1273
1274 int i;
1275 hir->start()->iterate_preorder(this);
1276 if (hir->code() != NULL) {
1277 assert(hir->code()->length() == _blocks->length(), "must match");
1278 for (i = 0; i < _blocks->length(); i++) {
1279 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1280 }
1281 }
1282
1283 for (i = 0; i < _blocks->length(); i++) {
1284 BlockBegin* block = _blocks->at(i);
1285 BlockList* preds = _predecessors->at(block->block_id());
1286 if (preds == NULL) {
1287 assert(block->number_of_preds() == 0, "should be the same");
1288 continue;
1289 }
1290
1291 // clone the pred list so we can mutate it
1292 BlockList* pred_copy = new BlockList();
1293 int j;
1294 for (j = 0; j < block->number_of_preds(); j++) {
1295 pred_copy->append(block->pred_at(j));
1296 }
1297 // sort them in the same order
1298 preds->sort(cmp);
1299 pred_copy->sort(cmp);
1300 int length = MIN2(preds->length(), block->number_of_preds());
1301 for (j = 0; j < block->number_of_preds(); j++) {
1302 assert(preds->at(j) == pred_copy->at(j), "must match");
1303 }
1304
1305 assert(preds->length() == block->number_of_preds(), "should be the same");
1306 }
1307 }
1308
1309 virtual void block_do(BlockBegin* block) {
1310 _blocks->append(block);
1311 BlockEnd* be = block->end();
1312 int n = be->number_of_sux();
1313 int i;
1314 for (i = 0; i < n; i++) {
1315 BlockBegin* sux = be->sux_at(i);
1316 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1317
1318 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1319 if (preds == NULL) {
1320 preds = new BlockList();
1321 _predecessors->at_put(sux->block_id(), preds);
1322 }
1323 preds->append(block);
1324 }
1325
1326 n = block->number_of_exception_handlers();
1327 for (i = 0; i < n; i++) {
1328 BlockBegin* sux = block->exception_handler_at(i);
1329 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1330
1331 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1332 if (preds == NULL) {
1333 preds = new BlockList();
1334 _predecessors->at_put(sux->block_id(), preds);
1335 }
1336 preds->append(block);
1337 }
1338 }
1339 };
1340
1341 class VerifyBlockBeginField : public BlockClosure {
1342
1343 public:
1344
1345 virtual void block_do(BlockBegin *block) {
1346 for ( Instruction *cur = block; cur != NULL; cur = cur->next()) {
1347 assert(cur->block() == block, "Block begin is not correct");
1348 }
1349 }
1350 };
1351
1352 void IR::verify() {
1353 #ifdef ASSERT
1354 PredecessorValidator pv(this);
1355 VerifyBlockBeginField verifier;
1356 this->iterate_postorder(&verifier);
1357 #endif
1358 }
1359
1360 #endif // PRODUCT
1361
1362 void SubstitutionResolver::visit(Value* v) {
1363 Value v0 = *v;
1364 if (v0) {
1365 Value vs = v0->subst();
1366 if (vs != v0) {
1367 *v = v0->subst();
1368 }
1369 }
1370 }
1371
1372 #ifdef ASSERT
1373 class SubstitutionChecker: public ValueVisitor {
1374 void visit(Value* v) {
1375 Value v0 = *v;
1376 if (v0) {
1377 Value vs = v0->subst();
1378 assert(vs == v0, "missed substitution");
1379 }
1380 }
1381 };
1382 #endif
1383
1384
1385 void SubstitutionResolver::block_do(BlockBegin* block) {
1386 Instruction* last = NULL;
1387 for (Instruction* n = block; n != NULL;) {
1388 n->values_do(this);
1389 // need to remove this instruction from the instruction stream
1390 if (n->subst() != n) {
1391 assert(last != NULL, "must have last");
1392 last->set_next(n->next());
1393 } else {
1394 last = n;
1395 }
1396 n = last->next();
1397 }
1398
1399 #ifdef ASSERT
1400 SubstitutionChecker check_substitute;
1401 if (block->state()) block->state()->values_do(&check_substitute);
1402 block->block_values_do(&check_substitute);
1403 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
1404 #endif
1405 }