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 _start = NULL;
146
147 if (osr_bci == -1) {
148 _requires_phi_function.clear();
149 } else {
150 // selective creation of phi functions is not possibel in osr-methods
151 _requires_phi_function.set_range(0, method->max_locals());
152 }
153
154 assert(method->holder()->is_loaded() , "method holder must be loaded");
155
156 // build graph if monitor pairing is ok
157 if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci);
158 }
159
160
161 int IRScope::max_stack() const {
162 int my_max = method()->max_stack();
163 int callee_max = 0;
164 for (int i = 0; i < number_of_callees(); i++) {
165 callee_max = MAX2(callee_max, callee_no(i)->max_stack());
166 }
167 return my_max + callee_max;
168 }
169
170
171 bool IRScopeDebugInfo::should_reexecute() {
172 ciMethod* cur_method = scope()->method();
173 int cur_bci = bci();
174 if (cur_method != NULL && cur_bci != SynchronizationEntryBCI) {
175 Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci);
176 return Interpreter::bytecode_should_reexecute(code);
177 } else
178 return false;
179 }
180
181
182 // Implementation of CodeEmitInfo
183
184 // Stack must be NON-null
185 CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers, bool deoptimize_on_exception)
186 : _scope(stack->scope())
187 , _scope_debug_info(NULL)
188 , _oop_map(NULL)
189 , _stack(stack)
190 , _exception_handlers(exception_handlers)
191 , _is_method_handle_invoke(false)
192 , _deoptimize_on_exception(deoptimize_on_exception) {
193 assert(_stack != NULL, "must be non null");
194 }
195
196
197 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack)
198 : _scope(info->_scope)
199 , _exception_handlers(NULL)
200 , _scope_debug_info(NULL)
201 , _oop_map(NULL)
202 , _stack(stack == NULL ? info->_stack : stack)
203 , _is_method_handle_invoke(info->_is_method_handle_invoke)
204 , _deoptimize_on_exception(info->_deoptimize_on_exception) {
205
206 // deep copy of exception handlers
207 if (info->_exception_handlers != NULL) {
208 _exception_handlers = new XHandlers(info->_exception_handlers);
209 }
210 }
211
212
213 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) {
214 // record the safepoint before recording the debug info for enclosing scopes
215 recorder->add_safepoint(pc_offset, _oop_map->deep_copy());
216 _scope_debug_info->record_debug_info(recorder, pc_offset, true/*topmost*/, _is_method_handle_invoke);
217 recorder->end_safepoint(pc_offset);
218 }
219
220
221 void CodeEmitInfo::record_non_safepoint_debug_info(DebugInformationRecorder* recorder, int pc_offset) {
222 if (recorder->recording_non_safepoints()) {
223 recorder->add_non_safepoint(pc_offset);
224 record_scope_non_safepoint_debug_info(recorder, pc_offset, scope(), stack());
225 recorder->end_non_safepoint(pc_offset);
226 }
227 }
228
229
230 void CodeEmitInfo::record_scope_non_safepoint_debug_info(DebugInformationRecorder* recorder, int pc_offset, IRScope *scope, ValueStack *state) {
231 if (scope->caller() != NULL) {
232 record_scope_non_safepoint_debug_info(recorder, pc_offset, scope->caller(), state->caller_state());
233 }
234 recorder->describe_scope(pc_offset, scope->method(), state->bci(), false);
235 }
236
237
238 void CodeEmitInfo::add_register_oop(LIR_Opr opr) {
239 assert(_oop_map != NULL, "oop map must already exist");
240 assert(opr->is_single_cpu(), "should not call otherwise");
241
242 VMReg name = frame_map()->regname(opr);
243 _oop_map->set_oop(name);
244 }
245
246 // Mirror the stack size calculation in the deopt code
247 // How much stack space would we need at this point in the program in
248 // case of deoptimization?
249 int CodeEmitInfo::interpreter_frame_size() const {
250 ValueStack* state = _stack;
251 int size = 0;
252 int callee_parameters = 0;
253 int callee_locals = 0;
254 int extra_args = state->scope()->method()->max_stack() - state->stack_size();
255
256 while (state != NULL) {
257 int locks = state->locks_size();
258 int temps = state->stack_size();
259 bool is_top_frame = (state == _stack);
260 ciMethod* method = state->scope()->method();
261
262 int frame_size = BytesPerWord * Interpreter::size_activation(method->max_stack(),
263 temps + callee_parameters,
264 extra_args,
265 locks,
266 callee_parameters,
267 callee_locals,
268 is_top_frame);
269 size += frame_size;
270
271 callee_parameters = method->size_of_parameters();
272 callee_locals = method->max_locals();
273 extra_args = 0;
274 state = state->caller_state();
275 }
276 return size + Deoptimization::last_frame_adjust(0, callee_locals) * BytesPerWord;
277 }
278
279 // Implementation of IR
280
281 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) :
282 _locals_size(in_WordSize(-1))
283 , _num_loops(0) {
284 // setup IR fields
285 _compilation = compilation;
286 _top_scope = new IRScope(compilation, NULL, -1, method, osr_bci, true);
287 _code = NULL;
288 }
289
290
291 void IR::optimize_blocks() {
292 Optimizer opt(this);
293 if (!compilation()->profile_branches()) {
294 if (DoCEE) {
295 opt.eliminate_conditional_expressions();
296 #ifndef PRODUCT
297 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
298 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
299 #endif
300 }
301 if (EliminateBlocks) {
302 opt.eliminate_blocks();
303 #ifndef PRODUCT
304 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
305 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
306 #endif
307 }
308 }
309 }
310
311 void IR::eliminate_null_checks() {
312 Optimizer opt(this);
313 if (EliminateNullChecks) {
314 opt.eliminate_null_checks();
315 #ifndef PRODUCT
316 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
317 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
318 #endif
319 }
320 }
321
322
323 static int sort_pairs(BlockPair** a, BlockPair** b) {
324 if ((*a)->from() == (*b)->from()) {
325 return (*a)->to()->block_id() - (*b)->to()->block_id();
326 } else {
327 return (*a)->from()->block_id() - (*b)->from()->block_id();
328 }
329 }
330
331
332 class CriticalEdgeFinder: public BlockClosure {
333 BlockPairList blocks;
334 IR* _ir;
335
336 public:
337 CriticalEdgeFinder(IR* ir): _ir(ir) {}
338 void block_do(BlockBegin* bb) {
339 BlockEnd* be = bb->end();
340 int nos = be->number_of_sux();
341 if (nos >= 2) {
342 for (int i = 0; i < nos; i++) {
343 BlockBegin* sux = be->sux_at(i);
344 if (sux->number_of_preds() >= 2) {
345 blocks.append(new BlockPair(bb, sux));
346 }
347 }
348 }
349 }
350
351 void split_edges() {
352 BlockPair* last_pair = NULL;
353 blocks.sort(sort_pairs);
354 for (int i = 0; i < blocks.length(); i++) {
355 BlockPair* pair = blocks.at(i);
356 if (last_pair != NULL && pair->is_same(last_pair)) continue;
357 BlockBegin* from = pair->from();
358 BlockBegin* to = pair->to();
359 BlockBegin* split = from->insert_block_between(to);
360 #ifndef PRODUCT
361 if ((PrintIR || PrintIR1) && Verbose) {
362 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
363 from->block_id(), to->block_id(), split->block_id());
364 }
365 #endif
366 last_pair = pair;
367 }
368 }
369 };
370
371 void IR::split_critical_edges() {
372 CriticalEdgeFinder cef(this);
373
374 iterate_preorder(&cef);
375 cef.split_edges();
376 }
377
378
379 class UseCountComputer: public ValueVisitor, BlockClosure {
380 private:
381 void visit(Value* n) {
382 // Local instructions and Phis for expression stack values at the
383 // start of basic blocks are not added to the instruction list
384 if (!(*n)->is_linked() && (*n)->can_be_linked()) {
385 assert(false, "a node was not appended to the graph");
386 Compilation::current()->bailout("a node was not appended to the graph");
387 }
388 // use n's input if not visited before
389 if (!(*n)->is_pinned() && !(*n)->has_uses()) {
390 // note: a) if the instruction is pinned, it will be handled by compute_use_count
391 // b) if the instruction has uses, it was touched before
392 // => in both cases we don't need to update n's values
393 uses_do(n);
394 }
395 // use n
396 (*n)->_use_count++;
397 }
398
399 Values* worklist;
400 int depth;
401 enum {
402 max_recurse_depth = 20
403 };
404
405 void uses_do(Value* n) {
406 depth++;
407 if (depth > max_recurse_depth) {
408 // don't allow the traversal to recurse too deeply
409 worklist->push(*n);
410 } else {
411 (*n)->input_values_do(this);
412 // special handling for some instructions
413 if ((*n)->as_BlockEnd() != NULL) {
414 // note on BlockEnd:
415 // must 'use' the stack only if the method doesn't
416 // terminate, however, in those cases stack is empty
417 (*n)->state_values_do(this);
418 }
419 }
420 depth--;
421 }
422
423 void block_do(BlockBegin* b) {
424 depth = 0;
425 // process all pinned nodes as the roots of expression trees
426 for (Instruction* n = b; n != NULL; n = n->next()) {
427 if (n->is_pinned()) uses_do(&n);
428 }
429 assert(depth == 0, "should have counted back down");
430
431 // now process any unpinned nodes which recursed too deeply
432 while (worklist->length() > 0) {
433 Value t = worklist->pop();
434 if (!t->is_pinned()) {
435 // compute the use count
436 uses_do(&t);
437
438 // pin the instruction so that LIRGenerator doesn't recurse
439 // too deeply during it's evaluation.
440 t->pin();
441 }
442 }
443 assert(depth == 0, "should have counted back down");
444 }
445
446 UseCountComputer() {
447 worklist = new Values();
448 depth = 0;
449 }
450
451 public:
452 static void compute(BlockList* blocks) {
453 UseCountComputer ucc;
454 blocks->iterate_backward(&ucc);
455 }
456 };
457
458
459 // helper macro for short definition of trace-output inside code
460 #ifndef PRODUCT
461 #define TRACE_LINEAR_SCAN(level, code) \
462 if (TraceLinearScanLevel >= level) { \
463 code; \
464 }
465 #else
466 #define TRACE_LINEAR_SCAN(level, code)
467 #endif
468
469 class ComputeLinearScanOrder : public StackObj {
470 private:
471 int _max_block_id; // the highest block_id of a block
472 int _num_blocks; // total number of blocks (smaller than _max_block_id)
473 int _num_loops; // total number of loops
474 bool _iterative_dominators;// method requires iterative computation of dominatiors
475
476 BlockList* _linear_scan_order; // the resulting list of blocks in correct order
477
478 BitMap _visited_blocks; // used for recursive processing of blocks
479 BitMap _active_blocks; // used for recursive processing of blocks
480 BitMap _dominator_blocks; // temproary BitMap used for computation of dominator
481 intArray _forward_branches; // number of incoming forward branches for each block
482 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges
483 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop
484 BlockList _work_list; // temporary list (used in mark_loops and compute_order)
485 BlockList _loop_headers;
486
487 Compilation* _compilation;
488
489 // accessors for _visited_blocks and _active_blocks
490 void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); }
491 bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); }
492 bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); }
493 void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); }
494 void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); }
495 void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); }
496
497 // accessors for _forward_branches
498 void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); }
499 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()); }
500
501 // accessors for _loop_map
502 bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); }
503 void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); }
504 void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); }
505
506 // count edges between blocks
507 void count_edges(BlockBegin* cur, BlockBegin* parent);
508
509 // loop detection
510 void mark_loops();
511 void clear_non_natural_loops(BlockBegin* start_block);
512 void assign_loop_depth(BlockBegin* start_block);
513
514 // computation of final block order
515 BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b);
516 void compute_dominator(BlockBegin* cur, BlockBegin* parent);
517 int compute_weight(BlockBegin* cur);
518 bool ready_for_processing(BlockBegin* cur);
519 void sort_into_work_list(BlockBegin* b);
520 void append_block(BlockBegin* cur);
521 void compute_order(BlockBegin* start_block);
522
523 // fixup of dominators for non-natural loops
524 bool compute_dominators_iter();
525 void compute_dominators();
526
527 // debug functions
528 NOT_PRODUCT(void print_blocks();)
529 DEBUG_ONLY(void verify();)
530
531 Compilation* compilation() const { return _compilation; }
532 public:
533 ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block);
534
535 // accessors for final result
536 BlockList* linear_scan_order() const { return _linear_scan_order; }
537 int num_loops() const { return _num_loops; }
538 };
539
540
541 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) :
542 _max_block_id(BlockBegin::number_of_blocks()),
543 _num_blocks(0),
544 _num_loops(0),
545 _iterative_dominators(false),
546 _visited_blocks(_max_block_id),
547 _active_blocks(_max_block_id),
548 _dominator_blocks(_max_block_id),
549 _forward_branches(_max_block_id, 0),
550 _loop_end_blocks(8),
551 _work_list(8),
552 _linear_scan_order(NULL), // initialized later with correct size
553 _loop_map(0, 0), // initialized later with correct size
554 _compilation(c)
555 {
556 TRACE_LINEAR_SCAN(2, tty->print_cr("***** computing linear-scan block order"));
557
558 init_visited();
559 count_edges(start_block, NULL);
560
561 if (compilation()->is_profiling()) {
562 ciMethod *method = compilation()->method();
563 if (!method->is_accessor()) {
564 ciMethodData* md = method->method_data_or_null();
565 assert(md != NULL, "Sanity");
566 md->set_compilation_stats(_num_loops, _num_blocks);
567 }
568 }
569
570 if (_num_loops > 0) {
571 mark_loops();
572 clear_non_natural_loops(start_block);
573 assign_loop_depth(start_block);
574 }
575
576 compute_order(start_block);
577 compute_dominators();
578
579 NOT_PRODUCT(print_blocks());
580 DEBUG_ONLY(verify());
581 }
582
583
584 // Traverse the CFG:
585 // * count total number of blocks
586 // * count all incoming edges and backward incoming edges
587 // * number loop header blocks
588 // * create a list with all loop end blocks
589 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
590 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));
591 assert(cur->dominator() == NULL, "dominator already initialized");
592
593 if (is_active(cur)) {
594 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
595 assert(is_visited(cur), "block must be visisted when block is active");
596 assert(parent != NULL, "must have parent");
597
598 cur->set(BlockBegin::linear_scan_loop_header_flag);
599 cur->set(BlockBegin::backward_branch_target_flag);
600
601 parent->set(BlockBegin::linear_scan_loop_end_flag);
602
603 // When a loop header is also the start of an exception handler, then the backward branch is
604 // an exception edge. Because such edges are usually critical edges which cannot be split, the
605 // loop must be excluded here from processing.
606 if (cur->is_set(BlockBegin::exception_entry_flag)) {
607 // Make sure that dominators are correct in this weird situation
608 _iterative_dominators = true;
609 return;
610 }
611 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
612 "loop end blocks must have one successor (critical edges are split)");
613
614 _loop_end_blocks.append(parent);
615 return;
616 }
617
618 // increment number of incoming forward branches
619 inc_forward_branches(cur);
620
621 if (is_visited(cur)) {
622 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
623 return;
624 }
625
626 _num_blocks++;
627 set_visited(cur);
628 set_active(cur);
629
630 // recursive call for all successors
631 int i;
632 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
633 count_edges(cur->sux_at(i), cur);
634 }
635 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
636 count_edges(cur->exception_handler_at(i), cur);
637 }
638
639 clear_active(cur);
640
641 // Each loop has a unique number.
642 // When multiple loops are nested, assign_loop_depth assumes that the
643 // innermost loop has the lowest number. This is guaranteed by setting
644 // the loop number after the recursive calls for the successors above
645 // have returned.
646 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
647 assert(cur->loop_index() == -1, "cannot set loop-index twice");
648 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
649
650 cur->set_loop_index(_num_loops);
651 _loop_headers.append(cur);
652 _num_loops++;
653 }
654
655 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
656 }
657
658
659 void ComputeLinearScanOrder::mark_loops() {
660 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
661
662 _loop_map = BitMap2D(_num_loops, _max_block_id);
663 _loop_map.clear();
664
665 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
666 BlockBegin* loop_end = _loop_end_blocks.at(i);
667 BlockBegin* loop_start = loop_end->sux_at(0);
668 int loop_idx = loop_start->loop_index();
669
670 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));
671 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
672 assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
673 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
674 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
675 assert(_work_list.is_empty(), "work list must be empty before processing");
676
677 // add the end-block of the loop to the working list
678 _work_list.push(loop_end);
679 set_block_in_loop(loop_idx, loop_end);
680 do {
681 BlockBegin* cur = _work_list.pop();
682
683 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id()));
684 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
685
686 // recursive processing of all predecessors ends when start block of loop is reached
687 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
688 for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
689 BlockBegin* pred = cur->pred_at(j);
690
691 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
692 // this predecessor has not been processed yet, so add it to work list
693 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id()));
694 _work_list.push(pred);
695 set_block_in_loop(loop_idx, pred);
696 }
697 }
698 }
699 } while (!_work_list.is_empty());
700 }
701 }
702
703
704 // check for non-natural loops (loops where the loop header does not dominate
705 // all other loop blocks = loops with mulitple entries).
706 // such loops are ignored
707 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
708 for (int i = _num_loops - 1; i >= 0; i--) {
709 if (is_block_in_loop(i, start_block)) {
710 // loop i contains the entry block of the method
711 // -> this is not a natural loop, so ignore it
712 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
713
714 BlockBegin *loop_header = _loop_headers.at(i);
715 assert(loop_header->is_set(BlockBegin::linear_scan_loop_header_flag), "Must be loop header");
716
717 for (int j = 0; j < loop_header->number_of_preds(); j++) {
718 BlockBegin *pred = loop_header->pred_at(j);
719 pred->clear(BlockBegin::linear_scan_loop_end_flag);
720 }
721
722 loop_header->clear(BlockBegin::linear_scan_loop_header_flag);
723
724 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
725 clear_block_in_loop(i, block_id);
726 }
727 _iterative_dominators = true;
728 }
729 }
730 }
731
732 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
733 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing loop-depth and weight"));
734 init_visited();
735
736 assert(_work_list.is_empty(), "work list must be empty before processing");
737 _work_list.append(start_block);
738
739 do {
740 BlockBegin* cur = _work_list.pop();
741
742 if (!is_visited(cur)) {
743 set_visited(cur);
744 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
745
746 // compute loop-depth and loop-index for the block
747 assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
748 int i;
749 int loop_depth = 0;
750 int min_loop_idx = -1;
751 for (i = _num_loops - 1; i >= 0; i--) {
752 if (is_block_in_loop(i, cur)) {
753 loop_depth++;
754 min_loop_idx = i;
755 }
756 }
757 cur->set_loop_depth(loop_depth);
758 cur->set_loop_index(min_loop_idx);
759
760 // append all unvisited successors to work list
761 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
762 _work_list.append(cur->sux_at(i));
763 }
764 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
765 _work_list.append(cur->exception_handler_at(i));
766 }
767 }
768 } while (!_work_list.is_empty());
769 }
770
771
772 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
773 assert(a != NULL && b != NULL, "must have input blocks");
774
775 _dominator_blocks.clear();
776 while (a != NULL) {
777 _dominator_blocks.set_bit(a->block_id());
778 assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
779 a = a->dominator();
780 }
781 while (b != NULL && !_dominator_blocks.at(b->block_id())) {
782 assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
783 b = b->dominator();
784 }
785
786 assert(b != NULL, "could not find dominator");
787 return b;
788 }
789
790 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
791 if (cur->dominator() == NULL) {
792 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
793 cur->set_dominator(parent);
794
795 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
796 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()));
797 // Does not hold for exception blocks
798 assert(cur->number_of_preds() > 1 || cur->is_set(BlockBegin::exception_entry_flag), "");
799 cur->set_dominator(common_dominator(cur->dominator(), parent));
800 }
801
802 // Additional edge to xhandler of all our successors
803 // range check elimination needs that the state at the end of a
804 // block be valid in every block it dominates so cur must dominate
805 // the exception handlers of its successors.
806 int num_cur_xhandler = cur->number_of_exception_handlers();
807 for (int j = 0; j < num_cur_xhandler; j++) {
808 BlockBegin* xhandler = cur->exception_handler_at(j);
809 compute_dominator(xhandler, parent);
810 }
811 }
812
813
814 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
815 BlockBegin* single_sux = NULL;
816 if (cur->number_of_sux() == 1) {
817 single_sux = cur->sux_at(0);
818 }
819
820 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
821 int weight = (cur->loop_depth() & 0x7FFF) << 16;
822
823 // general macro for short definition of weight flags
824 // the first instance of INC_WEIGHT_IF has the highest priority
825 int cur_bit = 15;
826 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
827
828 // this is necessery for the (very rare) case that two successing blocks have
829 // the same loop depth, but a different loop index (can happen for endless loops
830 // with exception handlers)
831 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
832
833 // loop end blocks (blocks that end with a backward branch) are added
834 // after all other blocks of the loop.
835 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
836
837 // critical edge split blocks are prefered because than they have a bigger
838 // proability to be completely empty
839 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
840
841 // exceptions should not be thrown in normal control flow, so these blocks
842 // are added as late as possible
843 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL));
844 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
845
846 // exceptions handlers are added as late as possible
847 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
848
849 // guarantee that weight is > 0
850 weight |= 1;
851
852 #undef INC_WEIGHT_IF
853 assert(cur_bit >= 0, "too many flags");
854 assert(weight > 0, "weight cannot become negative");
855
856 return weight;
857 }
858
859 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
860 // Discount the edge just traveled.
861 // When the number drops to zero, all forward branches were processed
862 if (dec_forward_branches(cur) != 0) {
863 return false;
864 }
865
866 assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
867 assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
868 return true;
869 }
870
871 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
872 assert(_work_list.index_of(cur) == -1, "block already in work list");
873
874 int cur_weight = compute_weight(cur);
875
876 // the linear_scan_number is used to cache the weight of a block
877 cur->set_linear_scan_number(cur_weight);
878
879 #ifndef PRODUCT
880 if (StressLinearScan) {
881 _work_list.insert_before(0, cur);
882 return;
883 }
884 #endif
885
886 _work_list.append(NULL); // provide space for new element
887
888 int insert_idx = _work_list.length() - 1;
889 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
890 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
891 insert_idx--;
892 }
893 _work_list.at_put(insert_idx, cur);
894
895 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
896 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()));
897
898 #ifdef ASSERT
899 for (int i = 0; i < _work_list.length(); i++) {
900 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
901 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
902 }
903 #endif
904 }
905
906 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
907 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()));
908 assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
909
910 // currently, the linear scan order and code emit order are equal.
911 // therefore the linear_scan_number and the weight of a block must also
912 // be equal.
913 cur->set_linear_scan_number(_linear_scan_order->length());
914 _linear_scan_order->append(cur);
915 }
916
917 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
918 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing final block order"));
919
920 // the start block is always the first block in the linear scan order
921 _linear_scan_order = new BlockList(_num_blocks);
922 append_block(start_block);
923
924 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
925 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
926 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
927
928 BlockBegin* sux_of_osr_entry = NULL;
929 if (osr_entry != NULL) {
930 // special handling for osr entry:
931 // ignore the edge between the osr entry and its successor for processing
932 // the osr entry block is added manually below
933 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
934 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");
935
936 sux_of_osr_entry = osr_entry->sux_at(0);
937 dec_forward_branches(sux_of_osr_entry);
938
939 compute_dominator(osr_entry, start_block);
940 _iterative_dominators = true;
941 }
942 compute_dominator(std_entry, start_block);
943
944 // start processing with standard entry block
945 assert(_work_list.is_empty(), "list must be empty before processing");
946
947 if (ready_for_processing(std_entry)) {
948 sort_into_work_list(std_entry);
949 } else {
950 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
951 }
952
953 do {
954 BlockBegin* cur = _work_list.pop();
955
956 if (cur == sux_of_osr_entry) {
957 // the osr entry block is ignored in normal processing, it is never added to the
958 // work list. Instead, it is added as late as possible manually here.
959 append_block(osr_entry);
960 compute_dominator(cur, osr_entry);
961 }
962 append_block(cur);
963
964 int i;
965 int num_sux = cur->number_of_sux();
966 // changed loop order to get "intuitive" order of if- and else-blocks
967 for (i = 0; i < num_sux; i++) {
968 BlockBegin* sux = cur->sux_at(i);
969 compute_dominator(sux, cur);
970 if (ready_for_processing(sux)) {
971 sort_into_work_list(sux);
972 }
973 }
974 num_sux = cur->number_of_exception_handlers();
975 for (i = 0; i < num_sux; i++) {
976 BlockBegin* sux = cur->exception_handler_at(i);
977 if (ready_for_processing(sux)) {
978 sort_into_work_list(sux);
979 }
980 }
981 } while (_work_list.length() > 0);
982 }
983
984
985 bool ComputeLinearScanOrder::compute_dominators_iter() {
986 bool changed = false;
987 int num_blocks = _linear_scan_order->length();
988
989 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
990 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
991 for (int i = 1; i < num_blocks; i++) {
992 BlockBegin* block = _linear_scan_order->at(i);
993
994 BlockBegin* dominator = block->pred_at(0);
995 int num_preds = block->number_of_preds();
996
997 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: Processing B%d", block->block_id()));
998
999 for (int j = 0; j < num_preds; j++) {
1000
1001 BlockBegin *pred = block->pred_at(j);
1002 TRACE_LINEAR_SCAN(4, tty->print_cr(" DOM: Subrocessing B%d", pred->block_id()));
1003
1004 if (block->is_set(BlockBegin::exception_entry_flag)) {
1005 dominator = common_dominator(dominator, pred);
1006 int num_pred_preds = pred->number_of_preds();
1007 for (int k = 0; k < num_pred_preds; k++) {
1008 dominator = common_dominator(dominator, pred->pred_at(k));
1009 }
1010 } else {
1011 dominator = common_dominator(dominator, pred);
1012 }
1013 }
1014
1015 if (dominator != block->dominator()) {
1016 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()));
1017
1018 block->set_dominator(dominator);
1019 changed = true;
1020 }
1021 }
1022 return changed;
1023 }
1024
1025 void ComputeLinearScanOrder::compute_dominators() {
1026 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
1027
1028 // iterative computation of dominators is only required for methods with non-natural loops
1029 // and OSR-methods. For all other methods, the dominators computed when generating the
1030 // linear scan block order are correct.
1031 if (_iterative_dominators) {
1032 do {
1033 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
1034 } while (compute_dominators_iter());
1035 }
1036
1037 // check that dominators are correct
1038 assert(!compute_dominators_iter(), "fix point not reached");
1039
1040 // Add Blocks to dominates-Array
1041 int num_blocks = _linear_scan_order->length();
1042 for (int i = 0; i < num_blocks; i++) {
1043 BlockBegin* block = _linear_scan_order->at(i);
1044
1045 BlockBegin *dom = block->dominator();
1046 if (dom) {
1047 assert(dom->dominator_depth() != -1, "Dominator must have been visited before");
1048 dom->dominates()->append(block);
1049 block->set_dominator_depth(dom->dominator_depth() + 1);
1050 } else {
1051 block->set_dominator_depth(0);
1052 }
1053 }
1054 }
1055
1056
1057 #ifndef PRODUCT
1058 void ComputeLinearScanOrder::print_blocks() {
1059 if (TraceLinearScanLevel >= 2) {
1060 tty->print_cr("----- loop information:");
1061 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1062 BlockBegin* cur = _linear_scan_order->at(block_idx);
1063
1064 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
1065 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1066 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
1067 }
1068 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
1069 }
1070 }
1071
1072 if (TraceLinearScanLevel >= 1) {
1073 tty->print_cr("----- linear-scan block order:");
1074 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1075 BlockBegin* cur = _linear_scan_order->at(block_idx);
1076 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
1077
1078 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
1079 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
1080 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
1081 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
1082
1083 if (cur->dominator() != NULL) {
1084 tty->print(" dom: B%d ", cur->dominator()->block_id());
1085 } else {
1086 tty->print(" dom: NULL ");
1087 }
1088
1089 if (cur->number_of_preds() > 0) {
1090 tty->print(" preds: ");
1091 for (int j = 0; j < cur->number_of_preds(); j++) {
1092 BlockBegin* pred = cur->pred_at(j);
1093 tty->print("B%d ", pred->block_id());
1094 }
1095 }
1096 if (cur->number_of_sux() > 0) {
1097 tty->print(" sux: ");
1098 for (int j = 0; j < cur->number_of_sux(); j++) {
1099 BlockBegin* sux = cur->sux_at(j);
1100 tty->print("B%d ", sux->block_id());
1101 }
1102 }
1103 if (cur->number_of_exception_handlers() > 0) {
1104 tty->print(" ex: ");
1105 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1106 BlockBegin* ex = cur->exception_handler_at(j);
1107 tty->print("B%d ", ex->block_id());
1108 }
1109 }
1110 tty->cr();
1111 }
1112 }
1113 }
1114 #endif
1115
1116 #ifdef ASSERT
1117 void ComputeLinearScanOrder::verify() {
1118 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1119
1120 if (StressLinearScan) {
1121 // blocks are scrambled when StressLinearScan is used
1122 return;
1123 }
1124
1125 // check that all successors of a block have a higher linear-scan-number
1126 // and that all predecessors of a block have a lower linear-scan-number
1127 // (only backward branches of loops are ignored)
1128 int i;
1129 for (i = 0; i < _linear_scan_order->length(); i++) {
1130 BlockBegin* cur = _linear_scan_order->at(i);
1131
1132 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1133 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
1134
1135 int j;
1136 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1137 BlockBegin* sux = cur->sux_at(j);
1138
1139 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
1140 if (!sux->is_set(BlockBegin::backward_branch_target_flag)) {
1141 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1142 }
1143 if (cur->loop_depth() == sux->loop_depth()) {
1144 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");
1145 }
1146 }
1147
1148 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1149 BlockBegin* pred = cur->pred_at(j);
1150
1151 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
1152 if (!cur->is_set(BlockBegin::backward_branch_target_flag)) {
1153 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1154 }
1155 if (cur->loop_depth() == pred->loop_depth()) {
1156 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");
1157 }
1158
1159 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1160 }
1161
1162 // check dominator
1163 if (i == 0) {
1164 assert(cur->dominator() == NULL, "first block has no dominator");
1165 } else {
1166 assert(cur->dominator() != NULL, "all but first block must have dominator");
1167 }
1168 // Assertion does not hold for exception handlers
1169 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");
1170 }
1171
1172 // check that all loops are continuous
1173 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1174 int block_idx = 0;
1175 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1176
1177 // skip blocks before the loop
1178 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1179 block_idx++;
1180 }
1181 // skip blocks of loop
1182 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1183 block_idx++;
1184 }
1185 // after the first non-loop block, there must not be another loop-block
1186 while (block_idx < _num_blocks) {
1187 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1188 block_idx++;
1189 }
1190 }
1191 }
1192 #endif
1193
1194
1195 void IR::compute_code() {
1196 assert(is_valid(), "IR must be valid");
1197
1198 ComputeLinearScanOrder compute_order(compilation(), start());
1199 _num_loops = compute_order.num_loops();
1200 _code = compute_order.linear_scan_order();
1201 }
1202
1203
1204 void IR::compute_use_counts() {
1205 // make sure all values coming out of this block get evaluated.
1206 int num_blocks = _code->length();
1207 for (int i = 0; i < num_blocks; i++) {
1208 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1209 }
1210
1211 // compute use counts
1212 UseCountComputer::compute(_code);
1213 }
1214
1215
1216 void IR::iterate_preorder(BlockClosure* closure) {
1217 assert(is_valid(), "IR must be valid");
1218 start()->iterate_preorder(closure);
1219 }
1220
1221
1222 void IR::iterate_postorder(BlockClosure* closure) {
1223 assert(is_valid(), "IR must be valid");
1224 start()->iterate_postorder(closure);
1225 }
1226
1227 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1228 linear_scan_order()->iterate_forward(closure);
1229 }
1230
1231
1232 #ifndef PRODUCT
1233 class BlockPrinter: public BlockClosure {
1234 private:
1235 InstructionPrinter* _ip;
1236 bool _cfg_only;
1237 bool _live_only;
1238
1239 public:
1240 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1241 _ip = ip;
1242 _cfg_only = cfg_only;
1243 _live_only = live_only;
1244 }
1245
1246 virtual void block_do(BlockBegin* block) {
1247 if (_cfg_only) {
1248 _ip->print_instr(block); tty->cr();
1249 } else {
1250 block->print_block(*_ip, _live_only);
1251 }
1252 }
1253 };
1254
1255
1256 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1257 ttyLocker ttyl;
1258 InstructionPrinter ip(!cfg_only);
1259 BlockPrinter bp(&ip, cfg_only, live_only);
1260 start->iterate_preorder(&bp);
1261 tty->cr();
1262 }
1263
1264 void IR::print(bool cfg_only, bool live_only) {
1265 if (is_valid()) {
1266 print(start(), cfg_only, live_only);
1267 } else {
1268 tty->print_cr("invalid IR");
1269 }
1270 }
1271
1272
1273 define_array(BlockListArray, BlockList*)
1274 define_stack(BlockListList, BlockListArray)
1275
1276 class PredecessorValidator : public BlockClosure {
1277 private:
1278 BlockListList* _predecessors;
1279 BlockList* _blocks;
1280
1281 static int cmp(BlockBegin** a, BlockBegin** b) {
1282 return (*a)->block_id() - (*b)->block_id();
1283 }
1284
1285 public:
1286 PredecessorValidator(IR* hir) {
1287 ResourceMark rm;
1288 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
1289 _blocks = new BlockList();
1290
1291 int i;
1292 hir->start()->iterate_preorder(this);
1293 if (hir->code() != NULL) {
1294 assert(hir->code()->length() == _blocks->length(), "must match");
1295 for (i = 0; i < _blocks->length(); i++) {
1296 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1297 }
1298 }
1299
1300 for (i = 0; i < _blocks->length(); i++) {
1301 BlockBegin* block = _blocks->at(i);
1302 BlockList* preds = _predecessors->at(block->block_id());
1303 if (preds == NULL) {
1304 assert(block->number_of_preds() == 0, "should be the same");
1305 continue;
1306 }
1307
1308 // clone the pred list so we can mutate it
1309 BlockList* pred_copy = new BlockList();
1310 int j;
1311 for (j = 0; j < block->number_of_preds(); j++) {
1312 pred_copy->append(block->pred_at(j));
1313 }
1314 // sort them in the same order
1315 preds->sort(cmp);
1316 pred_copy->sort(cmp);
1317 int length = MIN2(preds->length(), block->number_of_preds());
1318 for (j = 0; j < block->number_of_preds(); j++) {
1319 assert(preds->at(j) == pred_copy->at(j), "must match");
1320 }
1321
1322 assert(preds->length() == block->number_of_preds(), "should be the same");
1323 }
1324 }
1325
1326 virtual void block_do(BlockBegin* block) {
1327 _blocks->append(block);
1328 BlockEnd* be = block->end();
1329 int n = be->number_of_sux();
1330 int i;
1331 for (i = 0; i < n; i++) {
1332 BlockBegin* sux = be->sux_at(i);
1333 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1334
1335 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1336 if (preds == NULL) {
1337 preds = new BlockList();
1338 _predecessors->at_put(sux->block_id(), preds);
1339 }
1340 preds->append(block);
1341 }
1342
1343 n = block->number_of_exception_handlers();
1344 for (i = 0; i < n; i++) {
1345 BlockBegin* sux = block->exception_handler_at(i);
1346 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1347
1348 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1349 if (preds == NULL) {
1350 preds = new BlockList();
1351 _predecessors->at_put(sux->block_id(), preds);
1352 }
1353 preds->append(block);
1354 }
1355 }
1356 };
1357
1358 class VerifyBlockBeginField : public BlockClosure {
1359
1360 public:
1361
1362 virtual void block_do(BlockBegin *block) {
1363 for ( Instruction *cur = block; cur != NULL; cur = cur->next()) {
1364 assert(cur->block() == block, "Block begin is not correct");
1365 }
1366 }
1367 };
1368
1369 void IR::verify() {
1370 #ifdef ASSERT
1371 PredecessorValidator pv(this);
1372 VerifyBlockBeginField verifier;
1373 this->iterate_postorder(&verifier);
1374 #endif
1375 }
1376
1377 #endif // PRODUCT
1378
1379 void SubstitutionResolver::visit(Value* v) {
1380 Value v0 = *v;
1381 if (v0) {
1382 Value vs = v0->subst();
1383 if (vs != v0) {
1384 *v = v0->subst();
1385 }
1386 }
1387 }
1388
1389 #ifdef ASSERT
1390 class SubstitutionChecker: public ValueVisitor {
1391 void visit(Value* v) {
1392 Value v0 = *v;
1393 if (v0) {
1394 Value vs = v0->subst();
1395 assert(vs == v0, "missed substitution");
1396 }
1397 }
1398 };
1399 #endif
1400
1401
1402 void SubstitutionResolver::block_do(BlockBegin* block) {
1403 Instruction* last = NULL;
1404 for (Instruction* n = block; n != NULL;) {
1405 n->values_do(this);
1406 // need to remove this instruction from the instruction stream
1407 if (n->subst() != n) {
1408 assert(last != NULL, "must have last");
1409 last->set_next(n->next());
1410 } else {
1411 last = n;
1412 }
1413 n = last->next();
1414 }
1415
1416 #ifdef ASSERT
1417 SubstitutionChecker check_substitute;
1418 if (block->state()) block->state()->values_do(&check_substitute);
1419 block->block_values_do(&check_substitute);
1420 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
1421 #endif
1422 }