1/*
2 * Copyright (c) 1999, 2018, 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 "memory/resourceArea.hpp"
33#include "utilities/bitMap.inline.hpp"
34
35
36// Implementation of XHandlers
37//
38// Note: This code could eventually go away if we are
39// just using the ciExceptionHandlerStream.
40
41XHandlers::XHandlers(ciMethod* method) : _list(method->exception_table_length()) {
42 ciExceptionHandlerStream s(method);
43 while (!s.is_done()) {
44 _list.append(new XHandler(s.handler()));
45 s.next();
46 }
47 assert(s.count() == method->exception_table_length(), "exception table lengths inconsistent");
48}
49
50// deep copy of all XHandler contained in list
51XHandlers::XHandlers(XHandlers* other) :
52 _list(other->length())
53{
54 for (int i = 0; i < other->length(); i++) {
55 _list.append(new XHandler(other->handler_at(i)));
56 }
57}
58
59// Returns whether a particular exception type can be caught. Also
60// returns true if klass is unloaded or any exception handler
61// classes are unloaded. type_is_exact indicates whether the throw
62// is known to be exactly that class or it might throw a subtype.
63bool XHandlers::could_catch(ciInstanceKlass* klass, bool type_is_exact) const {
64 // the type is unknown so be conservative
65 if (!klass->is_loaded()) {
66 return true;
67 }
68
69 for (int i = 0; i < length(); i++) {
70 XHandler* handler = handler_at(i);
71 if (handler->is_catch_all()) {
72 // catch of ANY
73 return true;
74 }
75 ciInstanceKlass* handler_klass = handler->catch_klass();
76 // if it's unknown it might be catchable
77 if (!handler_klass->is_loaded()) {
78 return true;
79 }
80 // if the throw type is definitely a subtype of the catch type
81 // then it can be caught.
82 if (klass->is_subtype_of(handler_klass)) {
83 return true;
84 }
85 if (!type_is_exact) {
86 // If the type isn't exactly known then it can also be caught by
87 // catch statements where the inexact type is a subtype of the
88 // catch type.
89 // given: foo extends bar extends Exception
90 // throw bar can be caught by catch foo, catch bar, and catch
91 // Exception, however it can't be caught by any handlers without
92 // bar in its type hierarchy.
93 if (handler_klass->is_subtype_of(klass)) {
94 return true;
95 }
96 }
97 }
98
99 return false;
100}
101
102
103bool XHandlers::equals(XHandlers* others) const {
104 if (others == NULL) return false;
105 if (length() != others->length()) return false;
106
107 for (int i = 0; i < length(); i++) {
108 if (!handler_at(i)->equals(others->handler_at(i))) return false;
109 }
110 return true;
111}
112
113bool XHandler::equals(XHandler* other) const {
114 assert(entry_pco() != -1 && other->entry_pco() != -1, "must have entry_pco");
115
116 if (entry_pco() != other->entry_pco()) return false;
117 if (scope_count() != other->scope_count()) return false;
118 if (_desc != other->_desc) return false;
119
120 assert(entry_block() == other->entry_block(), "entry_block must be equal when entry_pco is equal");
121 return true;
122}
123
124
125// Implementation of IRScope
126BlockBegin* IRScope::build_graph(Compilation* compilation, int osr_bci) {
127 GraphBuilder gm(compilation, this);
128 NOT_PRODUCT(if (PrintValueNumbering && Verbose) gm.print_stats());
129 if (compilation->bailed_out()) return NULL;
130 return gm.start();
131}
132
133
134IRScope::IRScope(Compilation* compilation, IRScope* caller, int caller_bci, ciMethod* method, int osr_bci, bool create_graph)
135: _compilation(compilation)
136, _callees(2)
137, _requires_phi_function(method->max_locals())
138{
139 _caller = caller;
140 _level = caller == NULL ? 0 : caller->level() + 1;
141 _method = method;
142 _xhandlers = new XHandlers(method);
143 _number_of_locks = 0;
144 _monitor_pairing_ok = method->has_balanced_monitors();
145 _wrote_final = false;
146 _wrote_fields = false;
147 _wrote_volatile = false;
148 _start = NULL;
149
150 if (osr_bci != -1) {
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
162int 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
172bool 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
186CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers, bool deoptimize_on_exception)
187 : _scope_debug_info(NULL)
188 , _scope(stack->scope())
189 , _exception_handlers(exception_handlers)
190 , _oop_map(NULL)
191 , _stack(stack)
192 , _is_method_handle_invoke(false)
193 , _deoptimize_on_exception(deoptimize_on_exception) {
194 assert(_stack != NULL, "must be non null");
195}
196
197
198CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack)
199 : _scope_debug_info(NULL)
200 , _scope(info->_scope)
201 , _exception_handlers(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
214void 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
222void 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?
233int 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
265IR::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
274void 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
294void 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
306static 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
315class 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
354void IR::split_critical_edges() {
355 CriticalEdgeFinder cef(this);
356
357 iterate_preorder(&cef);
358 cef.split_edges();
359}
360
361
362class 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
452class 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 ResourceBitMap _visited_blocks; // used for recursive processing of blocks
462 ResourceBitMap _active_blocks; // used for recursive processing of blocks
463 ResourceBitMap _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 void compute_dominator_impl(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
525ComputeLinearScanOrder::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 _linear_scan_order(NULL), // initialized later with correct size
531 _visited_blocks(_max_block_id),
532 _active_blocks(_max_block_id),
533 _dominator_blocks(_max_block_id),
534 _forward_branches(_max_block_id, _max_block_id, 0),
535 _loop_end_blocks(8),
536 _loop_map(0), // initialized later with correct size
537 _work_list(8),
538 _compilation(c)
539{
540 TRACE_LINEAR_SCAN(2, tty->print_cr("***** computing linear-scan block order"));
541
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
572void 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::backward_branch_target_flag);
582
583 // When a loop header is also the start of an exception handler, then the backward branch is
584 // an exception edge. Because such edges are usually critical edges which cannot be split, the
585 // loop must be excluded here from processing.
586 if (cur->is_set(BlockBegin::exception_entry_flag)) {
587 // Make sure that dominators are correct in this weird situation
588 _iterative_dominators = true;
589 return;
590 }
591
592 cur->set(BlockBegin::linear_scan_loop_header_flag);
593 parent->set(BlockBegin::linear_scan_loop_end_flag);
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
643void ComputeLinearScanOrder::mark_loops() {
644 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
645
646 _loop_map = BitMap2D(_num_loops, _max_block_id);
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
690void 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
715void 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
755BlockBegin* 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
773void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
774 init_visited();
775 compute_dominator_impl(cur, parent);
776}
777
778void ComputeLinearScanOrder::compute_dominator_impl(BlockBegin* cur, BlockBegin* parent) {
779 // Mark as visited to avoid recursive calls with same parent
780 set_visited(cur);
781
782 if (cur->dominator() == NULL) {
783 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
784 cur->set_dominator(parent);
785
786 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
787 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()));
788 // Does not hold for exception blocks
789 assert(cur->number_of_preds() > 1 || cur->is_set(BlockBegin::exception_entry_flag), "");
790 cur->set_dominator(common_dominator(cur->dominator(), parent));
791 }
792
793 // Additional edge to xhandler of all our successors
794 // range check elimination needs that the state at the end of a
795 // block be valid in every block it dominates so cur must dominate
796 // the exception handlers of its successors.
797 int num_cur_xhandler = cur->number_of_exception_handlers();
798 for (int j = 0; j < num_cur_xhandler; j++) {
799 BlockBegin* xhandler = cur->exception_handler_at(j);
800 if (!is_visited(xhandler)) {
801 compute_dominator_impl(xhandler, parent);
802 }
803 }
804}
805
806
807int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
808 BlockBegin* single_sux = NULL;
809 if (cur->number_of_sux() == 1) {
810 single_sux = cur->sux_at(0);
811 }
812
813 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
814 int weight = (cur->loop_depth() & 0x7FFF) << 16;
815
816 // general macro for short definition of weight flags
817 // the first instance of INC_WEIGHT_IF has the highest priority
818 int cur_bit = 15;
819 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
820
821 // this is necessery for the (very rare) case that two successing blocks have
822 // the same loop depth, but a different loop index (can happen for endless loops
823 // with exception handlers)
824 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
825
826 // loop end blocks (blocks that end with a backward branch) are added
827 // after all other blocks of the loop.
828 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
829
830 // critical edge split blocks are prefered because than they have a bigger
831 // proability to be completely empty
832 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
833
834 // exceptions should not be thrown in normal control flow, so these blocks
835 // are added as late as possible
836 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL));
837 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
838
839 // exceptions handlers are added as late as possible
840 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
841
842 // guarantee that weight is > 0
843 weight |= 1;
844
845 #undef INC_WEIGHT_IF
846 assert(cur_bit >= 0, "too many flags");
847 assert(weight > 0, "weight cannot become negative");
848
849 return weight;
850}
851
852bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
853 // Discount the edge just traveled.
854 // When the number drops to zero, all forward branches were processed
855 if (dec_forward_branches(cur) != 0) {
856 return false;
857 }
858
859 assert(_linear_scan_order->find(cur) == -1, "block already processed (block can be ready only once)");
860 assert(_work_list.find(cur) == -1, "block already in work-list (block can be ready only once)");
861 return true;
862}
863
864void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
865 assert(_work_list.find(cur) == -1, "block already in work list");
866
867 int cur_weight = compute_weight(cur);
868
869 // the linear_scan_number is used to cache the weight of a block
870 cur->set_linear_scan_number(cur_weight);
871
872#ifndef PRODUCT
873 if (StressLinearScan) {
874 _work_list.insert_before(0, cur);
875 return;
876 }
877#endif
878
879 _work_list.append(NULL); // provide space for new element
880
881 int insert_idx = _work_list.length() - 1;
882 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
883 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
884 insert_idx--;
885 }
886 _work_list.at_put(insert_idx, cur);
887
888 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
889 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()));
890
891#ifdef ASSERT
892 for (int i = 0; i < _work_list.length(); i++) {
893 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
894 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
895 }
896#endif
897}
898
899void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
900 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()));
901 assert(_linear_scan_order->find(cur) == -1, "cannot add the same block twice");
902
903 // currently, the linear scan order and code emit order are equal.
904 // therefore the linear_scan_number and the weight of a block must also
905 // be equal.
906 cur->set_linear_scan_number(_linear_scan_order->length());
907 _linear_scan_order->append(cur);
908}
909
910void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
911 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing final block order"));
912
913 // the start block is always the first block in the linear scan order
914 _linear_scan_order = new BlockList(_num_blocks);
915 append_block(start_block);
916
917 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
918 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
919 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
920
921 BlockBegin* sux_of_osr_entry = NULL;
922 if (osr_entry != NULL) {
923 // special handling for osr entry:
924 // ignore the edge between the osr entry and its successor for processing
925 // the osr entry block is added manually below
926 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
927 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");
928
929 sux_of_osr_entry = osr_entry->sux_at(0);
930 dec_forward_branches(sux_of_osr_entry);
931
932 compute_dominator(osr_entry, start_block);
933 _iterative_dominators = true;
934 }
935 compute_dominator(std_entry, start_block);
936
937 // start processing with standard entry block
938 assert(_work_list.is_empty(), "list must be empty before processing");
939
940 if (ready_for_processing(std_entry)) {
941 sort_into_work_list(std_entry);
942 } else {
943 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
944 }
945
946 do {
947 BlockBegin* cur = _work_list.pop();
948
949 if (cur == sux_of_osr_entry) {
950 // the osr entry block is ignored in normal processing, it is never added to the
951 // work list. Instead, it is added as late as possible manually here.
952 append_block(osr_entry);
953 compute_dominator(cur, osr_entry);
954 }
955 append_block(cur);
956
957 int i;
958 int num_sux = cur->number_of_sux();
959 // changed loop order to get "intuitive" order of if- and else-blocks
960 for (i = 0; i < num_sux; i++) {
961 BlockBegin* sux = cur->sux_at(i);
962 compute_dominator(sux, cur);
963 if (ready_for_processing(sux)) {
964 sort_into_work_list(sux);
965 }
966 }
967 num_sux = cur->number_of_exception_handlers();
968 for (i = 0; i < num_sux; i++) {
969 BlockBegin* sux = cur->exception_handler_at(i);
970 if (ready_for_processing(sux)) {
971 sort_into_work_list(sux);
972 }
973 }
974 } while (_work_list.length() > 0);
975}
976
977
978bool ComputeLinearScanOrder::compute_dominators_iter() {
979 bool changed = false;
980 int num_blocks = _linear_scan_order->length();
981
982 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
983 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
984 for (int i = 1; i < num_blocks; i++) {
985 BlockBegin* block = _linear_scan_order->at(i);
986
987 BlockBegin* dominator = block->pred_at(0);
988 int num_preds = block->number_of_preds();
989
990 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: Processing B%d", block->block_id()));
991
992 for (int j = 0; j < num_preds; j++) {
993
994 BlockBegin *pred = block->pred_at(j);
995 TRACE_LINEAR_SCAN(4, tty->print_cr(" DOM: Subrocessing B%d", pred->block_id()));
996
997 if (block->is_set(BlockBegin::exception_entry_flag)) {
998 dominator = common_dominator(dominator, pred);
999 int num_pred_preds = pred->number_of_preds();
1000 for (int k = 0; k < num_pred_preds; k++) {
1001 dominator = common_dominator(dominator, pred->pred_at(k));
1002 }
1003 } else {
1004 dominator = common_dominator(dominator, pred);
1005 }
1006 }
1007
1008 if (dominator != block->dominator()) {
1009 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()));
1010
1011 block->set_dominator(dominator);
1012 changed = true;
1013 }
1014 }
1015 return changed;
1016}
1017
1018void ComputeLinearScanOrder::compute_dominators() {
1019 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
1020
1021 // iterative computation of dominators is only required for methods with non-natural loops
1022 // and OSR-methods. For all other methods, the dominators computed when generating the
1023 // linear scan block order are correct.
1024 if (_iterative_dominators) {
1025 do {
1026 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
1027 } while (compute_dominators_iter());
1028 }
1029
1030 // check that dominators are correct
1031 assert(!compute_dominators_iter(), "fix point not reached");
1032
1033 // Add Blocks to dominates-Array
1034 int num_blocks = _linear_scan_order->length();
1035 for (int i = 0; i < num_blocks; i++) {
1036 BlockBegin* block = _linear_scan_order->at(i);
1037
1038 BlockBegin *dom = block->dominator();
1039 if (dom) {
1040 assert(dom->dominator_depth() != -1, "Dominator must have been visited before");
1041 dom->dominates()->append(block);
1042 block->set_dominator_depth(dom->dominator_depth() + 1);
1043 } else {
1044 block->set_dominator_depth(0);
1045 }
1046 }
1047}
1048
1049
1050#ifndef PRODUCT
1051void ComputeLinearScanOrder::print_blocks() {
1052 if (TraceLinearScanLevel >= 2) {
1053 tty->print_cr("----- loop information:");
1054 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1055 BlockBegin* cur = _linear_scan_order->at(block_idx);
1056
1057 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
1058 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1059 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
1060 }
1061 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
1062 }
1063 }
1064
1065 if (TraceLinearScanLevel >= 1) {
1066 tty->print_cr("----- linear-scan block order:");
1067 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1068 BlockBegin* cur = _linear_scan_order->at(block_idx);
1069 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
1070
1071 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
1072 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
1073 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
1074 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
1075
1076 if (cur->dominator() != NULL) {
1077 tty->print(" dom: B%d ", cur->dominator()->block_id());
1078 } else {
1079 tty->print(" dom: NULL ");
1080 }
1081
1082 if (cur->number_of_preds() > 0) {
1083 tty->print(" preds: ");
1084 for (int j = 0; j < cur->number_of_preds(); j++) {
1085 BlockBegin* pred = cur->pred_at(j);
1086 tty->print("B%d ", pred->block_id());
1087 }
1088 }
1089 if (cur->number_of_sux() > 0) {
1090 tty->print(" sux: ");
1091 for (int j = 0; j < cur->number_of_sux(); j++) {
1092 BlockBegin* sux = cur->sux_at(j);
1093 tty->print("B%d ", sux->block_id());
1094 }
1095 }
1096 if (cur->number_of_exception_handlers() > 0) {
1097 tty->print(" ex: ");
1098 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1099 BlockBegin* ex = cur->exception_handler_at(j);
1100 tty->print("B%d ", ex->block_id());
1101 }
1102 }
1103 tty->cr();
1104 }
1105 }
1106}
1107#endif
1108
1109#ifdef ASSERT
1110void ComputeLinearScanOrder::verify() {
1111 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1112
1113 if (StressLinearScan) {
1114 // blocks are scrambled when StressLinearScan is used
1115 return;
1116 }
1117
1118 // check that all successors of a block have a higher linear-scan-number
1119 // and that all predecessors of a block have a lower linear-scan-number
1120 // (only backward branches of loops are ignored)
1121 int i;
1122 for (i = 0; i < _linear_scan_order->length(); i++) {
1123 BlockBegin* cur = _linear_scan_order->at(i);
1124
1125 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1126 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->find(cur), "incorrect linear_scan_number");
1127
1128 int j;
1129 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1130 BlockBegin* sux = cur->sux_at(j);
1131
1132 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->find(sux), "incorrect linear_scan_number");
1133 if (!sux->is_set(BlockBegin::backward_branch_target_flag)) {
1134 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1135 }
1136 if (cur->loop_depth() == sux->loop_depth()) {
1137 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");
1138 }
1139 }
1140
1141 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1142 BlockBegin* pred = cur->pred_at(j);
1143
1144 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->find(pred), "incorrect linear_scan_number");
1145 if (!cur->is_set(BlockBegin::backward_branch_target_flag)) {
1146 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1147 }
1148 if (cur->loop_depth() == pred->loop_depth()) {
1149 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");
1150 }
1151
1152 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1153 }
1154
1155 // check dominator
1156 if (i == 0) {
1157 assert(cur->dominator() == NULL, "first block has no dominator");
1158 } else {
1159 assert(cur->dominator() != NULL, "all but first block must have dominator");
1160 }
1161 // Assertion does not hold for exception handlers
1162 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");
1163 }
1164
1165 // check that all loops are continuous
1166 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1167 int block_idx = 0;
1168 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1169
1170 // skip blocks before the loop
1171 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1172 block_idx++;
1173 }
1174 // skip blocks of loop
1175 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1176 block_idx++;
1177 }
1178 // after the first non-loop block, there must not be another loop-block
1179 while (block_idx < _num_blocks) {
1180 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1181 block_idx++;
1182 }
1183 }
1184}
1185#endif
1186
1187
1188void IR::compute_code() {
1189 assert(is_valid(), "IR must be valid");
1190
1191 ComputeLinearScanOrder compute_order(compilation(), start());
1192 _num_loops = compute_order.num_loops();
1193 _code = compute_order.linear_scan_order();
1194}
1195
1196
1197void IR::compute_use_counts() {
1198 // make sure all values coming out of this block get evaluated.
1199 int num_blocks = _code->length();
1200 for (int i = 0; i < num_blocks; i++) {
1201 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1202 }
1203
1204 // compute use counts
1205 UseCountComputer::compute(_code);
1206}
1207
1208
1209void IR::iterate_preorder(BlockClosure* closure) {
1210 assert(is_valid(), "IR must be valid");
1211 start()->iterate_preorder(closure);
1212}
1213
1214
1215void IR::iterate_postorder(BlockClosure* closure) {
1216 assert(is_valid(), "IR must be valid");
1217 start()->iterate_postorder(closure);
1218}
1219
1220void IR::iterate_linear_scan_order(BlockClosure* closure) {
1221 linear_scan_order()->iterate_forward(closure);
1222}
1223
1224
1225#ifndef PRODUCT
1226class BlockPrinter: public BlockClosure {
1227 private:
1228 InstructionPrinter* _ip;
1229 bool _cfg_only;
1230 bool _live_only;
1231
1232 public:
1233 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1234 _ip = ip;
1235 _cfg_only = cfg_only;
1236 _live_only = live_only;
1237 }
1238
1239 virtual void block_do(BlockBegin* block) {
1240 if (_cfg_only) {
1241 _ip->print_instr(block); tty->cr();
1242 } else {
1243 block->print_block(*_ip, _live_only);
1244 }
1245 }
1246};
1247
1248
1249void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1250 ttyLocker ttyl;
1251 InstructionPrinter ip(!cfg_only);
1252 BlockPrinter bp(&ip, cfg_only, live_only);
1253 start->iterate_preorder(&bp);
1254 tty->cr();
1255}
1256
1257void IR::print(bool cfg_only, bool live_only) {
1258 if (is_valid()) {
1259 print(start(), cfg_only, live_only);
1260 } else {
1261 tty->print_cr("invalid IR");
1262 }
1263}
1264
1265
1266typedef GrowableArray<BlockList*> BlockListList;
1267
1268class PredecessorValidator : public BlockClosure {
1269 private:
1270 BlockListList* _predecessors;
1271 BlockList* _blocks;
1272
1273 static int cmp(BlockBegin** a, BlockBegin** b) {
1274 return (*a)->block_id() - (*b)->block_id();
1275 }
1276
1277 public:
1278 PredecessorValidator(IR* hir) {
1279 ResourceMark rm;
1280 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), BlockBegin::number_of_blocks(), NULL);
1281 _blocks = new BlockList();
1282
1283 int i;
1284 hir->start()->iterate_preorder(this);
1285 if (hir->code() != NULL) {
1286 assert(hir->code()->length() == _blocks->length(), "must match");
1287 for (i = 0; i < _blocks->length(); i++) {
1288 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1289 }
1290 }
1291
1292 for (i = 0; i < _blocks->length(); i++) {
1293 BlockBegin* block = _blocks->at(i);
1294 BlockList* preds = _predecessors->at(block->block_id());
1295 if (preds == NULL) {
1296 assert(block->number_of_preds() == 0, "should be the same");
1297 continue;
1298 }
1299
1300 // clone the pred list so we can mutate it
1301 BlockList* pred_copy = new BlockList();
1302 int j;
1303 for (j = 0; j < block->number_of_preds(); j++) {
1304 pred_copy->append(block->pred_at(j));
1305 }
1306 // sort them in the same order
1307 preds->sort(cmp);
1308 pred_copy->sort(cmp);
1309 int length = MIN2(preds->length(), block->number_of_preds());
1310 for (j = 0; j < block->number_of_preds(); j++) {
1311 assert(preds->at(j) == pred_copy->at(j), "must match");
1312 }
1313
1314 assert(preds->length() == block->number_of_preds(), "should be the same");
1315 }
1316 }
1317
1318 virtual void block_do(BlockBegin* block) {
1319 _blocks->append(block);
1320 BlockEnd* be = block->end();
1321 int n = be->number_of_sux();
1322 int i;
1323 for (i = 0; i < n; i++) {
1324 BlockBegin* sux = be->sux_at(i);
1325 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1326
1327 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1328 if (preds == NULL) {
1329 preds = new BlockList();
1330 _predecessors->at_put(sux->block_id(), preds);
1331 }
1332 preds->append(block);
1333 }
1334
1335 n = block->number_of_exception_handlers();
1336 for (i = 0; i < n; i++) {
1337 BlockBegin* sux = block->exception_handler_at(i);
1338 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1339
1340 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1341 if (preds == NULL) {
1342 preds = new BlockList();
1343 _predecessors->at_put(sux->block_id(), preds);
1344 }
1345 preds->append(block);
1346 }
1347 }
1348};
1349
1350class VerifyBlockBeginField : public BlockClosure {
1351
1352public:
1353
1354 virtual void block_do(BlockBegin *block) {
1355 for ( Instruction *cur = block; cur != NULL; cur = cur->next()) {
1356 assert(cur->block() == block, "Block begin is not correct");
1357 }
1358 }
1359};
1360
1361void IR::verify() {
1362#ifdef ASSERT
1363 PredecessorValidator pv(this);
1364 VerifyBlockBeginField verifier;
1365 this->iterate_postorder(&verifier);
1366#endif
1367}
1368
1369#endif // PRODUCT
1370
1371void SubstitutionResolver::visit(Value* v) {
1372 Value v0 = *v;
1373 if (v0) {
1374 Value vs = v0->subst();
1375 if (vs != v0) {
1376 *v = v0->subst();
1377 }
1378 }
1379}
1380
1381#ifdef ASSERT
1382class SubstitutionChecker: public ValueVisitor {
1383 void visit(Value* v) {
1384 Value v0 = *v;
1385 if (v0) {
1386 Value vs = v0->subst();
1387 assert(vs == v0, "missed substitution");
1388 }
1389 }
1390};
1391#endif
1392
1393
1394void SubstitutionResolver::block_do(BlockBegin* block) {
1395 Instruction* last = NULL;
1396 for (Instruction* n = block; n != NULL;) {
1397 n->values_do(this);
1398 // need to remove this instruction from the instruction stream
1399 if (n->subst() != n) {
1400 guarantee(last != NULL, "must have last");
1401 last->set_next(n->next());
1402 } else {
1403 last = n;
1404 }
1405 n = last->next();
1406 }
1407
1408#ifdef ASSERT
1409 SubstitutionChecker check_substitute;
1410 if (block->state()) block->state()->values_do(&check_substitute);
1411 block->block_values_do(&check_substitute);
1412 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
1413#endif
1414}
1415