1 /*
2 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "c1/c1_Compilation.hpp"
27 #include "c1/c1_FrameMap.hpp"
28 #include "c1/c1_GraphBuilder.hpp"
29 #include "c1/c1_IR.hpp"
30 #include "c1/c1_InstructionPrinter.hpp"
31 #include "c1/c1_Optimizer.hpp"
32 #include "utilities/bitMap.inline.hpp"
33
34
35 // Implementation of XHandlers
36 //
37 // Note: This code could eventually go away if we are
38 // just using the ciExceptionHandlerStream.
39
40 XHandlers::XHandlers(ciMethod* method) : _list(method->exception_table_length()) {
41 ciExceptionHandlerStream s(method);
42 while (!s.is_done()) {
43 _list.append(new XHandler(s.handler()));
44 s.next();
45 }
46 assert(s.count() == method->exception_table_length(), "exception table lengths inconsistent");
47 }
48
49 // deep copy of all XHandler contained in list
50 XHandlers::XHandlers(XHandlers* other) :
51 _list(other->length())
52 {
53 for (int i = 0; i < other->length(); i++) {
54 _list.append(new XHandler(other->handler_at(i)));
55 }
56 }
57
58 // Returns whether a particular exception type can be caught. Also
59 // returns true if klass is unloaded or any exception handler
60 // classes are unloaded. type_is_exact indicates whether the throw
61 // is known to be exactly that class or it might throw a subtype.
62 bool XHandlers::could_catch(ciInstanceKlass* klass, bool type_is_exact) const {
63 // the type is unknown so be conservative
64 if (!klass->is_loaded()) {
65 return true;
66 }
67
68 for (int i = 0; i < length(); i++) {
69 XHandler* handler = handler_at(i);
70 if (handler->is_catch_all()) {
71 // catch of ANY
72 return true;
73 }
74 ciInstanceKlass* handler_klass = handler->catch_klass();
75 // if it's unknown it might be catchable
76 if (!handler_klass->is_loaded()) {
77 return true;
78 }
79 // if the throw type is definitely a subtype of the catch type
80 // then it can be caught.
81 if (klass->is_subtype_of(handler_klass)) {
82 return true;
83 }
84 if (!type_is_exact) {
85 // If the type isn't exactly known then it can also be caught by
86 // catch statements where the inexact type is a subtype of the
87 // catch type.
88 // given: foo extends bar extends Exception
89 // throw bar can be caught by catch foo, catch bar, and catch
90 // Exception, however it can't be caught by any handlers without
91 // bar in its type hierarchy.
92 if (handler_klass->is_subtype_of(klass)) {
93 return true;
94 }
95 }
96 }
97
98 return false;
99 }
100
101
102 bool XHandlers::equals(XHandlers* others) const {
103 if (others == NULL) return false;
104 if (length() != others->length()) return false;
105
106 for (int i = 0; i < length(); i++) {
107 if (!handler_at(i)->equals(others->handler_at(i))) return false;
108 }
109 return true;
110 }
111
112 bool XHandler::equals(XHandler* other) const {
113 assert(entry_pco() != -1 && other->entry_pco() != -1, "must have entry_pco");
114
115 if (entry_pco() != other->entry_pco()) return false;
116 if (scope_count() != other->scope_count()) return false;
117 if (_desc != other->_desc) return false;
118
119 assert(entry_block() == other->entry_block(), "entry_block must be equal when entry_pco is equal");
120 return true;
121 }
122
123
124 // Implementation of IRScope
125 BlockBegin* IRScope::build_graph(Compilation* compilation, int osr_bci) {
126 GraphBuilder gm(compilation, this);
127 NOT_PRODUCT(if (PrintValueNumbering && Verbose) gm.print_stats());
128 if (compilation->bailed_out()) return NULL;
129 return gm.start();
130 }
131
132
133 IRScope::IRScope(Compilation* compilation, IRScope* caller, int caller_bci, ciMethod* method, int osr_bci, bool create_graph)
134 : _callees(2)
135 , _compilation(compilation)
136 , _requires_phi_function(method->max_locals())
137 {
138 _caller = caller;
139 _level = caller == NULL ? 0 : caller->level() + 1;
140 _method = method;
141 _xhandlers = new XHandlers(method);
142 _number_of_locks = 0;
143 _monitor_pairing_ok = method->has_balanced_monitors();
144 _wrote_final = false;
145 _wrote_fields = false;
146 _start = NULL;
147
148 if (osr_bci == -1) {
149 _requires_phi_function.clear();
150 } else {
151 // selective creation of phi functions is not possibel in osr-methods
152 _requires_phi_function.set_range(0, method->max_locals());
153 }
154
155 assert(method->holder()->is_loaded() , "method holder must be loaded");
156
157 // build graph if monitor pairing is ok
158 if (create_graph && monitor_pairing_ok()) _start = build_graph(compilation, osr_bci);
159 }
160
161
162 int IRScope::max_stack() const {
163 int my_max = method()->max_stack();
164 int callee_max = 0;
165 for (int i = 0; i < number_of_callees(); i++) {
166 callee_max = MAX2(callee_max, callee_no(i)->max_stack());
167 }
168 return my_max + callee_max;
169 }
170
171
172 bool IRScopeDebugInfo::should_reexecute() {
173 ciMethod* cur_method = scope()->method();
174 int cur_bci = bci();
175 if (cur_method != NULL && cur_bci != SynchronizationEntryBCI) {
176 Bytecodes::Code code = cur_method->java_code_at_bci(cur_bci);
177 return Interpreter::bytecode_should_reexecute(code);
178 } else
179 return false;
180 }
181
182
183 // Implementation of CodeEmitInfo
184
185 // Stack must be NON-null
186 CodeEmitInfo::CodeEmitInfo(ValueStack* stack, XHandlers* exception_handlers, bool deoptimize_on_exception)
187 : _scope(stack->scope())
188 , _scope_debug_info(NULL)
189 , _oop_map(NULL)
190 , _stack(stack)
191 , _exception_handlers(exception_handlers)
192 , _is_method_handle_invoke(false)
193 , _deoptimize_on_exception(deoptimize_on_exception) {
194 assert(_stack != NULL, "must be non null");
195 }
196
197
198 CodeEmitInfo::CodeEmitInfo(CodeEmitInfo* info, ValueStack* stack)
199 : _scope(info->_scope)
200 , _exception_handlers(NULL)
201 , _scope_debug_info(NULL)
202 , _oop_map(NULL)
203 , _stack(stack == NULL ? info->_stack : stack)
204 , _is_method_handle_invoke(info->_is_method_handle_invoke)
205 , _deoptimize_on_exception(info->_deoptimize_on_exception) {
206
207 // deep copy of exception handlers
208 if (info->_exception_handlers != NULL) {
209 _exception_handlers = new XHandlers(info->_exception_handlers);
210 }
211 }
212
213
214 void CodeEmitInfo::record_debug_info(DebugInformationRecorder* recorder, int pc_offset) {
215 // record the safepoint before recording the debug info for enclosing scopes
216 recorder->add_safepoint(pc_offset, _oop_map->deep_copy());
217 _scope_debug_info->record_debug_info(recorder, pc_offset, true/*topmost*/, _is_method_handle_invoke);
218 recorder->end_safepoint(pc_offset);
219 }
220
221
222 void CodeEmitInfo::add_register_oop(LIR_Opr opr) {
223 assert(_oop_map != NULL, "oop map must already exist");
224 assert(opr->is_single_cpu(), "should not call otherwise");
225
226 VMReg name = frame_map()->regname(opr);
227 _oop_map->set_oop(name);
228 }
229
230 // Mirror the stack size calculation in the deopt code
231 // How much stack space would we need at this point in the program in
232 // case of deoptimization?
233 int CodeEmitInfo::interpreter_frame_size() const {
234 ValueStack* state = _stack;
235 int size = 0;
236 int callee_parameters = 0;
237 int callee_locals = 0;
238 int popframe_extra_args = 0;
239
240 if (JvmtiExport::can_pop_frame() && state->kind() != ValueStack::StateBefore) {
241 ciMethod* method = state->scope()->method();
242 int bci = state->bci();
243 popframe_extra_args = MAX2(-method->get_stack_effect_if_at_invoke(bci), 0);
244 }
245
246 while (state != NULL) {
247 int locks = state->locks_size();
248 int temps = state->stack_size();
249 bool is_top_frame = (state->caller_state() == NULL);
250 ciMethod* method = state->scope()->method();
251
252 int frame_size = BytesPerWord * Interpreter::size_activation(method->max_stack(),
253 temps + callee_parameters,
254 popframe_extra_args,
255 locks,
256 callee_parameters,
257 callee_locals,
258 is_top_frame);
259 size += frame_size;
260
261 callee_parameters = method->size_of_parameters();
262 callee_locals = method->max_locals();
263 popframe_extra_args = 0;
264 state = state->caller_state();
265 }
266 return size + Deoptimization::last_frame_adjust(0, callee_locals) * BytesPerWord;
267 }
268
269 // Implementation of IR
270
271 IR::IR(Compilation* compilation, ciMethod* method, int osr_bci) :
272 _locals_size(in_WordSize(-1))
273 , _num_loops(0) {
274 // setup IR fields
275 _compilation = compilation;
276 _top_scope = new IRScope(compilation, NULL, -1, method, osr_bci, true);
277 _code = NULL;
278 }
279
280
281 void IR::optimize_blocks() {
282 Optimizer opt(this);
283 if (!compilation()->profile_branches()) {
284 if (DoCEE) {
285 opt.eliminate_conditional_expressions();
286 #ifndef PRODUCT
287 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after CEE"); print(true); }
288 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after CEE"); print(false); }
289 #endif
290 }
291 if (EliminateBlocks) {
292 opt.eliminate_blocks();
293 #ifndef PRODUCT
294 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after block elimination"); print(true); }
295 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after block elimination"); print(false); }
296 #endif
297 }
298 }
299 }
300
301 void IR::eliminate_null_checks() {
302 Optimizer opt(this);
303 if (EliminateNullChecks) {
304 opt.eliminate_null_checks();
305 #ifndef PRODUCT
306 if (PrintCFG || PrintCFG1) { tty->print_cr("CFG after null check elimination"); print(true); }
307 if (PrintIR || PrintIR1 ) { tty->print_cr("IR after null check elimination"); print(false); }
308 #endif
309 }
310 }
311
312
313 static int sort_pairs(BlockPair** a, BlockPair** b) {
314 if ((*a)->from() == (*b)->from()) {
315 return (*a)->to()->block_id() - (*b)->to()->block_id();
316 } else {
317 return (*a)->from()->block_id() - (*b)->from()->block_id();
318 }
319 }
320
321
322 class CriticalEdgeFinder: public BlockClosure {
323 BlockPairList blocks;
324 IR* _ir;
325
326 public:
327 CriticalEdgeFinder(IR* ir): _ir(ir) {}
328 void block_do(BlockBegin* bb) {
329 BlockEnd* be = bb->end();
330 int nos = be->number_of_sux();
331 if (nos >= 2) {
332 for (int i = 0; i < nos; i++) {
333 BlockBegin* sux = be->sux_at(i);
334 if (sux->number_of_preds() >= 2) {
335 blocks.append(new BlockPair(bb, sux));
336 }
337 }
338 }
339 }
340
341 void split_edges() {
342 BlockPair* last_pair = NULL;
343 blocks.sort(sort_pairs);
344 for (int i = 0; i < blocks.length(); i++) {
345 BlockPair* pair = blocks.at(i);
346 if (last_pair != NULL && pair->is_same(last_pair)) continue;
347 BlockBegin* from = pair->from();
348 BlockBegin* to = pair->to();
349 BlockBegin* split = from->insert_block_between(to);
350 #ifndef PRODUCT
351 if ((PrintIR || PrintIR1) && Verbose) {
352 tty->print_cr("Split critical edge B%d -> B%d (new block B%d)",
353 from->block_id(), to->block_id(), split->block_id());
354 }
355 #endif
356 last_pair = pair;
357 }
358 }
359 };
360
361 void IR::split_critical_edges() {
362 CriticalEdgeFinder cef(this);
363
364 iterate_preorder(&cef);
365 cef.split_edges();
366 }
367
368
369 class UseCountComputer: public ValueVisitor, BlockClosure {
370 private:
371 void visit(Value* n) {
372 // Local instructions and Phis for expression stack values at the
373 // start of basic blocks are not added to the instruction list
374 if (!(*n)->is_linked() && (*n)->can_be_linked()) {
375 assert(false, "a node was not appended to the graph");
376 Compilation::current()->bailout("a node was not appended to the graph");
377 }
378 // use n's input if not visited before
379 if (!(*n)->is_pinned() && !(*n)->has_uses()) {
380 // note: a) if the instruction is pinned, it will be handled by compute_use_count
381 // b) if the instruction has uses, it was touched before
382 // => in both cases we don't need to update n's values
383 uses_do(n);
384 }
385 // use n
386 (*n)->_use_count++;
387 }
388
389 Values* worklist;
390 int depth;
391 enum {
392 max_recurse_depth = 20
393 };
394
395 void uses_do(Value* n) {
396 depth++;
397 if (depth > max_recurse_depth) {
398 // don't allow the traversal to recurse too deeply
399 worklist->push(*n);
400 } else {
401 (*n)->input_values_do(this);
402 // special handling for some instructions
403 if ((*n)->as_BlockEnd() != NULL) {
404 // note on BlockEnd:
405 // must 'use' the stack only if the method doesn't
406 // terminate, however, in those cases stack is empty
407 (*n)->state_values_do(this);
408 }
409 }
410 depth--;
411 }
412
413 void block_do(BlockBegin* b) {
414 depth = 0;
415 // process all pinned nodes as the roots of expression trees
416 for (Instruction* n = b; n != NULL; n = n->next()) {
417 if (n->is_pinned()) uses_do(&n);
418 }
419 assert(depth == 0, "should have counted back down");
420
421 // now process any unpinned nodes which recursed too deeply
422 while (worklist->length() > 0) {
423 Value t = worklist->pop();
424 if (!t->is_pinned()) {
425 // compute the use count
426 uses_do(&t);
427
428 // pin the instruction so that LIRGenerator doesn't recurse
429 // too deeply during it's evaluation.
430 t->pin();
431 }
432 }
433 assert(depth == 0, "should have counted back down");
434 }
435
436 UseCountComputer() {
437 worklist = new Values();
438 depth = 0;
439 }
440
441 public:
442 static void compute(BlockList* blocks) {
443 UseCountComputer ucc;
444 blocks->iterate_backward(&ucc);
445 }
446 };
447
448
449 // helper macro for short definition of trace-output inside code
450 #ifndef PRODUCT
451 #define TRACE_LINEAR_SCAN(level, code) \
452 if (TraceLinearScanLevel >= level) { \
453 code; \
454 }
455 #else
456 #define TRACE_LINEAR_SCAN(level, code)
457 #endif
458
459 class ComputeLinearScanOrder : public StackObj {
460 private:
461 int _max_block_id; // the highest block_id of a block
462 int _num_blocks; // total number of blocks (smaller than _max_block_id)
463 int _num_loops; // total number of loops
464 bool _iterative_dominators;// method requires iterative computation of dominatiors
465
466 BlockList* _linear_scan_order; // the resulting list of blocks in correct order
467
468 BitMap _visited_blocks; // used for recursive processing of blocks
469 BitMap _active_blocks; // used for recursive processing of blocks
470 BitMap _dominator_blocks; // temproary BitMap used for computation of dominator
471 intArray _forward_branches; // number of incoming forward branches for each block
472 BlockList _loop_end_blocks; // list of all loop end blocks collected during count_edges
473 BitMap2D _loop_map; // two-dimensional bit set: a bit is set if a block is contained in a loop
474 BlockList _work_list; // temporary list (used in mark_loops and compute_order)
475 BlockList _loop_headers;
476
477 Compilation* _compilation;
478
479 // accessors for _visited_blocks and _active_blocks
480 void init_visited() { _active_blocks.clear(); _visited_blocks.clear(); }
481 bool is_visited(BlockBegin* b) const { return _visited_blocks.at(b->block_id()); }
482 bool is_active(BlockBegin* b) const { return _active_blocks.at(b->block_id()); }
483 void set_visited(BlockBegin* b) { assert(!is_visited(b), "already set"); _visited_blocks.set_bit(b->block_id()); }
484 void set_active(BlockBegin* b) { assert(!is_active(b), "already set"); _active_blocks.set_bit(b->block_id()); }
485 void clear_active(BlockBegin* b) { assert(is_active(b), "not already"); _active_blocks.clear_bit(b->block_id()); }
486
487 // accessors for _forward_branches
488 void inc_forward_branches(BlockBegin* b) { _forward_branches.at_put(b->block_id(), _forward_branches.at(b->block_id()) + 1); }
489 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()); }
490
491 // accessors for _loop_map
492 bool is_block_in_loop (int loop_idx, BlockBegin* b) const { return _loop_map.at(loop_idx, b->block_id()); }
493 void set_block_in_loop (int loop_idx, BlockBegin* b) { _loop_map.set_bit(loop_idx, b->block_id()); }
494 void clear_block_in_loop(int loop_idx, int block_id) { _loop_map.clear_bit(loop_idx, block_id); }
495
496 // count edges between blocks
497 void count_edges(BlockBegin* cur, BlockBegin* parent);
498
499 // loop detection
500 void mark_loops();
501 void clear_non_natural_loops(BlockBegin* start_block);
502 void assign_loop_depth(BlockBegin* start_block);
503
504 // computation of final block order
505 BlockBegin* common_dominator(BlockBegin* a, BlockBegin* b);
506 void compute_dominator(BlockBegin* cur, BlockBegin* parent);
507 int compute_weight(BlockBegin* cur);
508 bool ready_for_processing(BlockBegin* cur);
509 void sort_into_work_list(BlockBegin* b);
510 void append_block(BlockBegin* cur);
511 void compute_order(BlockBegin* start_block);
512
513 // fixup of dominators for non-natural loops
514 bool compute_dominators_iter();
515 void compute_dominators();
516
517 // debug functions
518 NOT_PRODUCT(void print_blocks();)
519 DEBUG_ONLY(void verify();)
520
521 Compilation* compilation() const { return _compilation; }
522 public:
523 ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block);
524
525 // accessors for final result
526 BlockList* linear_scan_order() const { return _linear_scan_order; }
527 int num_loops() const { return _num_loops; }
528 };
529
530
531 ComputeLinearScanOrder::ComputeLinearScanOrder(Compilation* c, BlockBegin* start_block) :
532 _max_block_id(BlockBegin::number_of_blocks()),
533 _num_blocks(0),
534 _num_loops(0),
535 _iterative_dominators(false),
536 _visited_blocks(_max_block_id),
537 _active_blocks(_max_block_id),
538 _dominator_blocks(_max_block_id),
539 _forward_branches(_max_block_id, 0),
540 _loop_end_blocks(8),
541 _work_list(8),
542 _linear_scan_order(NULL), // initialized later with correct size
543 _loop_map(0, 0), // initialized later with correct size
544 _compilation(c)
545 {
546 TRACE_LINEAR_SCAN(2, tty->print_cr("***** computing linear-scan block order"));
547
548 init_visited();
549 count_edges(start_block, NULL);
550
551 if (compilation()->is_profiling()) {
552 ciMethod *method = compilation()->method();
553 if (!method->is_accessor()) {
554 ciMethodData* md = method->method_data_or_null();
555 assert(md != NULL, "Sanity");
556 md->set_compilation_stats(_num_loops, _num_blocks);
557 }
558 }
559
560 if (_num_loops > 0) {
561 mark_loops();
562 clear_non_natural_loops(start_block);
563 assign_loop_depth(start_block);
564 }
565
566 compute_order(start_block);
567 compute_dominators();
568
569 NOT_PRODUCT(print_blocks());
570 DEBUG_ONLY(verify());
571 }
572
573
574 // Traverse the CFG:
575 // * count total number of blocks
576 // * count all incoming edges and backward incoming edges
577 // * number loop header blocks
578 // * create a list with all loop end blocks
579 void ComputeLinearScanOrder::count_edges(BlockBegin* cur, BlockBegin* parent) {
580 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));
581 assert(cur->dominator() == NULL, "dominator already initialized");
582
583 if (is_active(cur)) {
584 TRACE_LINEAR_SCAN(3, tty->print_cr("backward branch"));
585 assert(is_visited(cur), "block must be visisted when block is active");
586 assert(parent != NULL, "must have parent");
587
588 cur->set(BlockBegin::linear_scan_loop_header_flag);
589 cur->set(BlockBegin::backward_branch_target_flag);
590
591 parent->set(BlockBegin::linear_scan_loop_end_flag);
592
593 // When a loop header is also the start of an exception handler, then the backward branch is
594 // an exception edge. Because such edges are usually critical edges which cannot be split, the
595 // loop must be excluded here from processing.
596 if (cur->is_set(BlockBegin::exception_entry_flag)) {
597 // Make sure that dominators are correct in this weird situation
598 _iterative_dominators = true;
599 return;
600 }
601 assert(parent->number_of_sux() == 1 && parent->sux_at(0) == cur,
602 "loop end blocks must have one successor (critical edges are split)");
603
604 _loop_end_blocks.append(parent);
605 return;
606 }
607
608 // increment number of incoming forward branches
609 inc_forward_branches(cur);
610
611 if (is_visited(cur)) {
612 TRACE_LINEAR_SCAN(3, tty->print_cr("block already visited"));
613 return;
614 }
615
616 _num_blocks++;
617 set_visited(cur);
618 set_active(cur);
619
620 // recursive call for all successors
621 int i;
622 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
623 count_edges(cur->sux_at(i), cur);
624 }
625 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
626 count_edges(cur->exception_handler_at(i), cur);
627 }
628
629 clear_active(cur);
630
631 // Each loop has a unique number.
632 // When multiple loops are nested, assign_loop_depth assumes that the
633 // innermost loop has the lowest number. This is guaranteed by setting
634 // the loop number after the recursive calls for the successors above
635 // have returned.
636 if (cur->is_set(BlockBegin::linear_scan_loop_header_flag)) {
637 assert(cur->loop_index() == -1, "cannot set loop-index twice");
638 TRACE_LINEAR_SCAN(3, tty->print_cr("Block B%d is loop header of loop %d", cur->block_id(), _num_loops));
639
640 cur->set_loop_index(_num_loops);
641 _loop_headers.append(cur);
642 _num_loops++;
643 }
644
645 TRACE_LINEAR_SCAN(3, tty->print_cr("Finished count_edges for block B%d", cur->block_id()));
646 }
647
648
649 void ComputeLinearScanOrder::mark_loops() {
650 TRACE_LINEAR_SCAN(3, tty->print_cr("----- marking loops"));
651
652 _loop_map = BitMap2D(_num_loops, _max_block_id);
653 _loop_map.clear();
654
655 for (int i = _loop_end_blocks.length() - 1; i >= 0; i--) {
656 BlockBegin* loop_end = _loop_end_blocks.at(i);
657 BlockBegin* loop_start = loop_end->sux_at(0);
658 int loop_idx = loop_start->loop_index();
659
660 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));
661 assert(loop_end->is_set(BlockBegin::linear_scan_loop_end_flag), "loop end flag must be set");
662 assert(loop_end->number_of_sux() == 1, "incorrect number of successors");
663 assert(loop_start->is_set(BlockBegin::linear_scan_loop_header_flag), "loop header flag must be set");
664 assert(loop_idx >= 0 && loop_idx < _num_loops, "loop index not set");
665 assert(_work_list.is_empty(), "work list must be empty before processing");
666
667 // add the end-block of the loop to the working list
668 _work_list.push(loop_end);
669 set_block_in_loop(loop_idx, loop_end);
670 do {
671 BlockBegin* cur = _work_list.pop();
672
673 TRACE_LINEAR_SCAN(3, tty->print_cr(" processing B%d", cur->block_id()));
674 assert(is_block_in_loop(loop_idx, cur), "bit in loop map must be set when block is in work list");
675
676 // recursive processing of all predecessors ends when start block of loop is reached
677 if (cur != loop_start && !cur->is_set(BlockBegin::osr_entry_flag)) {
678 for (int j = cur->number_of_preds() - 1; j >= 0; j--) {
679 BlockBegin* pred = cur->pred_at(j);
680
681 if (!is_block_in_loop(loop_idx, pred) /*&& !pred->is_set(BlockBeginosr_entry_flag)*/) {
682 // this predecessor has not been processed yet, so add it to work list
683 TRACE_LINEAR_SCAN(3, tty->print_cr(" pushing B%d", pred->block_id()));
684 _work_list.push(pred);
685 set_block_in_loop(loop_idx, pred);
686 }
687 }
688 }
689 } while (!_work_list.is_empty());
690 }
691 }
692
693
694 // check for non-natural loops (loops where the loop header does not dominate
695 // all other loop blocks = loops with mulitple entries).
696 // such loops are ignored
697 void ComputeLinearScanOrder::clear_non_natural_loops(BlockBegin* start_block) {
698 for (int i = _num_loops - 1; i >= 0; i--) {
699 if (is_block_in_loop(i, start_block)) {
700 // loop i contains the entry block of the method
701 // -> this is not a natural loop, so ignore it
702 TRACE_LINEAR_SCAN(2, tty->print_cr("Loop %d is non-natural, so it is ignored", i));
703
704 BlockBegin *loop_header = _loop_headers.at(i);
705 assert(loop_header->is_set(BlockBegin::linear_scan_loop_header_flag), "Must be loop header");
706
707 for (int j = 0; j < loop_header->number_of_preds(); j++) {
708 BlockBegin *pred = loop_header->pred_at(j);
709 pred->clear(BlockBegin::linear_scan_loop_end_flag);
710 }
711
712 loop_header->clear(BlockBegin::linear_scan_loop_header_flag);
713
714 for (int block_id = _max_block_id - 1; block_id >= 0; block_id--) {
715 clear_block_in_loop(i, block_id);
716 }
717 _iterative_dominators = true;
718 }
719 }
720 }
721
722 void ComputeLinearScanOrder::assign_loop_depth(BlockBegin* start_block) {
723 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing loop-depth and weight"));
724 init_visited();
725
726 assert(_work_list.is_empty(), "work list must be empty before processing");
727 _work_list.append(start_block);
728
729 do {
730 BlockBegin* cur = _work_list.pop();
731
732 if (!is_visited(cur)) {
733 set_visited(cur);
734 TRACE_LINEAR_SCAN(4, tty->print_cr("Computing loop depth for block B%d", cur->block_id()));
735
736 // compute loop-depth and loop-index for the block
737 assert(cur->loop_depth() == 0, "cannot set loop-depth twice");
738 int i;
739 int loop_depth = 0;
740 int min_loop_idx = -1;
741 for (i = _num_loops - 1; i >= 0; i--) {
742 if (is_block_in_loop(i, cur)) {
743 loop_depth++;
744 min_loop_idx = i;
745 }
746 }
747 cur->set_loop_depth(loop_depth);
748 cur->set_loop_index(min_loop_idx);
749
750 // append all unvisited successors to work list
751 for (i = cur->number_of_sux() - 1; i >= 0; i--) {
752 _work_list.append(cur->sux_at(i));
753 }
754 for (i = cur->number_of_exception_handlers() - 1; i >= 0; i--) {
755 _work_list.append(cur->exception_handler_at(i));
756 }
757 }
758 } while (!_work_list.is_empty());
759 }
760
761
762 BlockBegin* ComputeLinearScanOrder::common_dominator(BlockBegin* a, BlockBegin* b) {
763 assert(a != NULL && b != NULL, "must have input blocks");
764
765 _dominator_blocks.clear();
766 while (a != NULL) {
767 _dominator_blocks.set_bit(a->block_id());
768 assert(a->dominator() != NULL || a == _linear_scan_order->at(0), "dominator must be initialized");
769 a = a->dominator();
770 }
771 while (b != NULL && !_dominator_blocks.at(b->block_id())) {
772 assert(b->dominator() != NULL || b == _linear_scan_order->at(0), "dominator must be initialized");
773 b = b->dominator();
774 }
775
776 assert(b != NULL, "could not find dominator");
777 return b;
778 }
779
780 void ComputeLinearScanOrder::compute_dominator(BlockBegin* cur, BlockBegin* parent) {
781 if (cur->dominator() == NULL) {
782 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: initializing dominator of B%d to B%d", cur->block_id(), parent->block_id()));
783 cur->set_dominator(parent);
784
785 } else if (!(cur->is_set(BlockBegin::linear_scan_loop_header_flag) && parent->is_set(BlockBegin::linear_scan_loop_end_flag))) {
786 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()));
787 // Does not hold for exception blocks
788 assert(cur->number_of_preds() > 1 || cur->is_set(BlockBegin::exception_entry_flag), "");
789 cur->set_dominator(common_dominator(cur->dominator(), parent));
790 }
791
792 // Additional edge to xhandler of all our successors
793 // range check elimination needs that the state at the end of a
794 // block be valid in every block it dominates so cur must dominate
795 // the exception handlers of its successors.
796 int num_cur_xhandler = cur->number_of_exception_handlers();
797 for (int j = 0; j < num_cur_xhandler; j++) {
798 BlockBegin* xhandler = cur->exception_handler_at(j);
799 compute_dominator(xhandler, parent);
800 }
801 }
802
803
804 int ComputeLinearScanOrder::compute_weight(BlockBegin* cur) {
805 BlockBegin* single_sux = NULL;
806 if (cur->number_of_sux() == 1) {
807 single_sux = cur->sux_at(0);
808 }
809
810 // limit loop-depth to 15 bit (only for security reason, it will never be so big)
811 int weight = (cur->loop_depth() & 0x7FFF) << 16;
812
813 // general macro for short definition of weight flags
814 // the first instance of INC_WEIGHT_IF has the highest priority
815 int cur_bit = 15;
816 #define INC_WEIGHT_IF(condition) if ((condition)) { weight |= (1 << cur_bit); } cur_bit--;
817
818 // this is necessery for the (very rare) case that two successing blocks have
819 // the same loop depth, but a different loop index (can happen for endless loops
820 // with exception handlers)
821 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_header_flag));
822
823 // loop end blocks (blocks that end with a backward branch) are added
824 // after all other blocks of the loop.
825 INC_WEIGHT_IF(!cur->is_set(BlockBegin::linear_scan_loop_end_flag));
826
827 // critical edge split blocks are prefered because than they have a bigger
828 // proability to be completely empty
829 INC_WEIGHT_IF(cur->is_set(BlockBegin::critical_edge_split_flag));
830
831 // exceptions should not be thrown in normal control flow, so these blocks
832 // are added as late as possible
833 INC_WEIGHT_IF(cur->end()->as_Throw() == NULL && (single_sux == NULL || single_sux->end()->as_Throw() == NULL));
834 INC_WEIGHT_IF(cur->end()->as_Return() == NULL && (single_sux == NULL || single_sux->end()->as_Return() == NULL));
835
836 // exceptions handlers are added as late as possible
837 INC_WEIGHT_IF(!cur->is_set(BlockBegin::exception_entry_flag));
838
839 // guarantee that weight is > 0
840 weight |= 1;
841
842 #undef INC_WEIGHT_IF
843 assert(cur_bit >= 0, "too many flags");
844 assert(weight > 0, "weight cannot become negative");
845
846 return weight;
847 }
848
849 bool ComputeLinearScanOrder::ready_for_processing(BlockBegin* cur) {
850 // Discount the edge just traveled.
851 // When the number drops to zero, all forward branches were processed
852 if (dec_forward_branches(cur) != 0) {
853 return false;
854 }
855
856 assert(_linear_scan_order->index_of(cur) == -1, "block already processed (block can be ready only once)");
857 assert(_work_list.index_of(cur) == -1, "block already in work-list (block can be ready only once)");
858 return true;
859 }
860
861 void ComputeLinearScanOrder::sort_into_work_list(BlockBegin* cur) {
862 assert(_work_list.index_of(cur) == -1, "block already in work list");
863
864 int cur_weight = compute_weight(cur);
865
866 // the linear_scan_number is used to cache the weight of a block
867 cur->set_linear_scan_number(cur_weight);
868
869 #ifndef PRODUCT
870 if (StressLinearScan) {
871 _work_list.insert_before(0, cur);
872 return;
873 }
874 #endif
875
876 _work_list.append(NULL); // provide space for new element
877
878 int insert_idx = _work_list.length() - 1;
879 while (insert_idx > 0 && _work_list.at(insert_idx - 1)->linear_scan_number() > cur_weight) {
880 _work_list.at_put(insert_idx, _work_list.at(insert_idx - 1));
881 insert_idx--;
882 }
883 _work_list.at_put(insert_idx, cur);
884
885 TRACE_LINEAR_SCAN(3, tty->print_cr("Sorted B%d into worklist. new worklist:", cur->block_id()));
886 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()));
887
888 #ifdef ASSERT
889 for (int i = 0; i < _work_list.length(); i++) {
890 assert(_work_list.at(i)->linear_scan_number() > 0, "weight not set");
891 assert(i == 0 || _work_list.at(i - 1)->linear_scan_number() <= _work_list.at(i)->linear_scan_number(), "incorrect order in worklist");
892 }
893 #endif
894 }
895
896 void ComputeLinearScanOrder::append_block(BlockBegin* cur) {
897 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()));
898 assert(_linear_scan_order->index_of(cur) == -1, "cannot add the same block twice");
899
900 // currently, the linear scan order and code emit order are equal.
901 // therefore the linear_scan_number and the weight of a block must also
902 // be equal.
903 cur->set_linear_scan_number(_linear_scan_order->length());
904 _linear_scan_order->append(cur);
905 }
906
907 void ComputeLinearScanOrder::compute_order(BlockBegin* start_block) {
908 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing final block order"));
909
910 // the start block is always the first block in the linear scan order
911 _linear_scan_order = new BlockList(_num_blocks);
912 append_block(start_block);
913
914 assert(start_block->end()->as_Base() != NULL, "start block must end with Base-instruction");
915 BlockBegin* std_entry = ((Base*)start_block->end())->std_entry();
916 BlockBegin* osr_entry = ((Base*)start_block->end())->osr_entry();
917
918 BlockBegin* sux_of_osr_entry = NULL;
919 if (osr_entry != NULL) {
920 // special handling for osr entry:
921 // ignore the edge between the osr entry and its successor for processing
922 // the osr entry block is added manually below
923 assert(osr_entry->number_of_sux() == 1, "osr entry must have exactly one successor");
924 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");
925
926 sux_of_osr_entry = osr_entry->sux_at(0);
927 dec_forward_branches(sux_of_osr_entry);
928
929 compute_dominator(osr_entry, start_block);
930 _iterative_dominators = true;
931 }
932 compute_dominator(std_entry, start_block);
933
934 // start processing with standard entry block
935 assert(_work_list.is_empty(), "list must be empty before processing");
936
937 if (ready_for_processing(std_entry)) {
938 sort_into_work_list(std_entry);
939 } else {
940 assert(false, "the std_entry must be ready for processing (otherwise, the method has no start block)");
941 }
942
943 do {
944 BlockBegin* cur = _work_list.pop();
945
946 if (cur == sux_of_osr_entry) {
947 // the osr entry block is ignored in normal processing, it is never added to the
948 // work list. Instead, it is added as late as possible manually here.
949 append_block(osr_entry);
950 compute_dominator(cur, osr_entry);
951 }
952 append_block(cur);
953
954 int i;
955 int num_sux = cur->number_of_sux();
956 // changed loop order to get "intuitive" order of if- and else-blocks
957 for (i = 0; i < num_sux; i++) {
958 BlockBegin* sux = cur->sux_at(i);
959 compute_dominator(sux, cur);
960 if (ready_for_processing(sux)) {
961 sort_into_work_list(sux);
962 }
963 }
964 num_sux = cur->number_of_exception_handlers();
965 for (i = 0; i < num_sux; i++) {
966 BlockBegin* sux = cur->exception_handler_at(i);
967 if (ready_for_processing(sux)) {
968 sort_into_work_list(sux);
969 }
970 }
971 } while (_work_list.length() > 0);
972 }
973
974
975 bool ComputeLinearScanOrder::compute_dominators_iter() {
976 bool changed = false;
977 int num_blocks = _linear_scan_order->length();
978
979 assert(_linear_scan_order->at(0)->dominator() == NULL, "must not have dominator");
980 assert(_linear_scan_order->at(0)->number_of_preds() == 0, "must not have predecessors");
981 for (int i = 1; i < num_blocks; i++) {
982 BlockBegin* block = _linear_scan_order->at(i);
983
984 BlockBegin* dominator = block->pred_at(0);
985 int num_preds = block->number_of_preds();
986
987 TRACE_LINEAR_SCAN(4, tty->print_cr("DOM: Processing B%d", block->block_id()));
988
989 for (int j = 0; j < num_preds; j++) {
990
991 BlockBegin *pred = block->pred_at(j);
992 TRACE_LINEAR_SCAN(4, tty->print_cr(" DOM: Subrocessing B%d", pred->block_id()));
993
994 if (block->is_set(BlockBegin::exception_entry_flag)) {
995 dominator = common_dominator(dominator, pred);
996 int num_pred_preds = pred->number_of_preds();
997 for (int k = 0; k < num_pred_preds; k++) {
998 dominator = common_dominator(dominator, pred->pred_at(k));
999 }
1000 } else {
1001 dominator = common_dominator(dominator, pred);
1002 }
1003 }
1004
1005 if (dominator != block->dominator()) {
1006 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()));
1007
1008 block->set_dominator(dominator);
1009 changed = true;
1010 }
1011 }
1012 return changed;
1013 }
1014
1015 void ComputeLinearScanOrder::compute_dominators() {
1016 TRACE_LINEAR_SCAN(3, tty->print_cr("----- computing dominators (iterative computation reqired: %d)", _iterative_dominators));
1017
1018 // iterative computation of dominators is only required for methods with non-natural loops
1019 // and OSR-methods. For all other methods, the dominators computed when generating the
1020 // linear scan block order are correct.
1021 if (_iterative_dominators) {
1022 do {
1023 TRACE_LINEAR_SCAN(1, tty->print_cr("DOM: next iteration of fix-point calculation"));
1024 } while (compute_dominators_iter());
1025 }
1026
1027 // check that dominators are correct
1028 assert(!compute_dominators_iter(), "fix point not reached");
1029
1030 // Add Blocks to dominates-Array
1031 int num_blocks = _linear_scan_order->length();
1032 for (int i = 0; i < num_blocks; i++) {
1033 BlockBegin* block = _linear_scan_order->at(i);
1034
1035 BlockBegin *dom = block->dominator();
1036 if (dom) {
1037 assert(dom->dominator_depth() != -1, "Dominator must have been visited before");
1038 dom->dominates()->append(block);
1039 block->set_dominator_depth(dom->dominator_depth() + 1);
1040 } else {
1041 block->set_dominator_depth(0);
1042 }
1043 }
1044 }
1045
1046
1047 #ifndef PRODUCT
1048 void ComputeLinearScanOrder::print_blocks() {
1049 if (TraceLinearScanLevel >= 2) {
1050 tty->print_cr("----- loop information:");
1051 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1052 BlockBegin* cur = _linear_scan_order->at(block_idx);
1053
1054 tty->print("%4d: B%2d: ", cur->linear_scan_number(), cur->block_id());
1055 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1056 tty->print ("%d ", is_block_in_loop(loop_idx, cur));
1057 }
1058 tty->print_cr(" -> loop_index: %2d, loop_depth: %2d", cur->loop_index(), cur->loop_depth());
1059 }
1060 }
1061
1062 if (TraceLinearScanLevel >= 1) {
1063 tty->print_cr("----- linear-scan block order:");
1064 for (int block_idx = 0; block_idx < _linear_scan_order->length(); block_idx++) {
1065 BlockBegin* cur = _linear_scan_order->at(block_idx);
1066 tty->print("%4d: B%2d loop: %2d depth: %2d", cur->linear_scan_number(), cur->block_id(), cur->loop_index(), cur->loop_depth());
1067
1068 tty->print(cur->is_set(BlockBegin::exception_entry_flag) ? " ex" : " ");
1069 tty->print(cur->is_set(BlockBegin::critical_edge_split_flag) ? " ce" : " ");
1070 tty->print(cur->is_set(BlockBegin::linear_scan_loop_header_flag) ? " lh" : " ");
1071 tty->print(cur->is_set(BlockBegin::linear_scan_loop_end_flag) ? " le" : " ");
1072
1073 if (cur->dominator() != NULL) {
1074 tty->print(" dom: B%d ", cur->dominator()->block_id());
1075 } else {
1076 tty->print(" dom: NULL ");
1077 }
1078
1079 if (cur->number_of_preds() > 0) {
1080 tty->print(" preds: ");
1081 for (int j = 0; j < cur->number_of_preds(); j++) {
1082 BlockBegin* pred = cur->pred_at(j);
1083 tty->print("B%d ", pred->block_id());
1084 }
1085 }
1086 if (cur->number_of_sux() > 0) {
1087 tty->print(" sux: ");
1088 for (int j = 0; j < cur->number_of_sux(); j++) {
1089 BlockBegin* sux = cur->sux_at(j);
1090 tty->print("B%d ", sux->block_id());
1091 }
1092 }
1093 if (cur->number_of_exception_handlers() > 0) {
1094 tty->print(" ex: ");
1095 for (int j = 0; j < cur->number_of_exception_handlers(); j++) {
1096 BlockBegin* ex = cur->exception_handler_at(j);
1097 tty->print("B%d ", ex->block_id());
1098 }
1099 }
1100 tty->cr();
1101 }
1102 }
1103 }
1104 #endif
1105
1106 #ifdef ASSERT
1107 void ComputeLinearScanOrder::verify() {
1108 assert(_linear_scan_order->length() == _num_blocks, "wrong number of blocks in list");
1109
1110 if (StressLinearScan) {
1111 // blocks are scrambled when StressLinearScan is used
1112 return;
1113 }
1114
1115 // check that all successors of a block have a higher linear-scan-number
1116 // and that all predecessors of a block have a lower linear-scan-number
1117 // (only backward branches of loops are ignored)
1118 int i;
1119 for (i = 0; i < _linear_scan_order->length(); i++) {
1120 BlockBegin* cur = _linear_scan_order->at(i);
1121
1122 assert(cur->linear_scan_number() == i, "incorrect linear_scan_number");
1123 assert(cur->linear_scan_number() >= 0 && cur->linear_scan_number() == _linear_scan_order->index_of(cur), "incorrect linear_scan_number");
1124
1125 int j;
1126 for (j = cur->number_of_sux() - 1; j >= 0; j--) {
1127 BlockBegin* sux = cur->sux_at(j);
1128
1129 assert(sux->linear_scan_number() >= 0 && sux->linear_scan_number() == _linear_scan_order->index_of(sux), "incorrect linear_scan_number");
1130 if (!sux->is_set(BlockBegin::backward_branch_target_flag)) {
1131 assert(cur->linear_scan_number() < sux->linear_scan_number(), "invalid order");
1132 }
1133 if (cur->loop_depth() == sux->loop_depth()) {
1134 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");
1135 }
1136 }
1137
1138 for (j = cur->number_of_preds() - 1; j >= 0; j--) {
1139 BlockBegin* pred = cur->pred_at(j);
1140
1141 assert(pred->linear_scan_number() >= 0 && pred->linear_scan_number() == _linear_scan_order->index_of(pred), "incorrect linear_scan_number");
1142 if (!cur->is_set(BlockBegin::backward_branch_target_flag)) {
1143 assert(cur->linear_scan_number() > pred->linear_scan_number(), "invalid order");
1144 }
1145 if (cur->loop_depth() == pred->loop_depth()) {
1146 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");
1147 }
1148
1149 assert(cur->dominator()->linear_scan_number() <= cur->pred_at(j)->linear_scan_number(), "dominator must be before predecessors");
1150 }
1151
1152 // check dominator
1153 if (i == 0) {
1154 assert(cur->dominator() == NULL, "first block has no dominator");
1155 } else {
1156 assert(cur->dominator() != NULL, "all but first block must have dominator");
1157 }
1158 // Assertion does not hold for exception handlers
1159 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");
1160 }
1161
1162 // check that all loops are continuous
1163 for (int loop_idx = 0; loop_idx < _num_loops; loop_idx++) {
1164 int block_idx = 0;
1165 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "the first block must not be present in any loop");
1166
1167 // skip blocks before the loop
1168 while (block_idx < _num_blocks && !is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1169 block_idx++;
1170 }
1171 // skip blocks of loop
1172 while (block_idx < _num_blocks && is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx))) {
1173 block_idx++;
1174 }
1175 // after the first non-loop block, there must not be another loop-block
1176 while (block_idx < _num_blocks) {
1177 assert(!is_block_in_loop(loop_idx, _linear_scan_order->at(block_idx)), "loop not continuous in linear-scan order");
1178 block_idx++;
1179 }
1180 }
1181 }
1182 #endif
1183
1184
1185 void IR::compute_code() {
1186 assert(is_valid(), "IR must be valid");
1187
1188 ComputeLinearScanOrder compute_order(compilation(), start());
1189 _num_loops = compute_order.num_loops();
1190 _code = compute_order.linear_scan_order();
1191 }
1192
1193
1194 void IR::compute_use_counts() {
1195 // make sure all values coming out of this block get evaluated.
1196 int num_blocks = _code->length();
1197 for (int i = 0; i < num_blocks; i++) {
1198 _code->at(i)->end()->state()->pin_stack_for_linear_scan();
1199 }
1200
1201 // compute use counts
1202 UseCountComputer::compute(_code);
1203 }
1204
1205
1206 void IR::iterate_preorder(BlockClosure* closure) {
1207 assert(is_valid(), "IR must be valid");
1208 start()->iterate_preorder(closure);
1209 }
1210
1211
1212 void IR::iterate_postorder(BlockClosure* closure) {
1213 assert(is_valid(), "IR must be valid");
1214 start()->iterate_postorder(closure);
1215 }
1216
1217 void IR::iterate_linear_scan_order(BlockClosure* closure) {
1218 linear_scan_order()->iterate_forward(closure);
1219 }
1220
1221
1222 #ifndef PRODUCT
1223 class BlockPrinter: public BlockClosure {
1224 private:
1225 InstructionPrinter* _ip;
1226 bool _cfg_only;
1227 bool _live_only;
1228
1229 public:
1230 BlockPrinter(InstructionPrinter* ip, bool cfg_only, bool live_only = false) {
1231 _ip = ip;
1232 _cfg_only = cfg_only;
1233 _live_only = live_only;
1234 }
1235
1236 virtual void block_do(BlockBegin* block) {
1237 if (_cfg_only) {
1238 _ip->print_instr(block); tty->cr();
1239 } else {
1240 block->print_block(*_ip, _live_only);
1241 }
1242 }
1243 };
1244
1245
1246 void IR::print(BlockBegin* start, bool cfg_only, bool live_only) {
1247 ttyLocker ttyl;
1248 InstructionPrinter ip(!cfg_only);
1249 BlockPrinter bp(&ip, cfg_only, live_only);
1250 start->iterate_preorder(&bp);
1251 tty->cr();
1252 }
1253
1254 void IR::print(bool cfg_only, bool live_only) {
1255 if (is_valid()) {
1256 print(start(), cfg_only, live_only);
1257 } else {
1258 tty->print_cr("invalid IR");
1259 }
1260 }
1261
1262
1263 define_array(BlockListArray, BlockList*)
1264 define_stack(BlockListList, BlockListArray)
1265
1266 class PredecessorValidator : public BlockClosure {
1267 private:
1268 BlockListList* _predecessors;
1269 BlockList* _blocks;
1270
1271 static int cmp(BlockBegin** a, BlockBegin** b) {
1272 return (*a)->block_id() - (*b)->block_id();
1273 }
1274
1275 public:
1276 PredecessorValidator(IR* hir) {
1277 ResourceMark rm;
1278 _predecessors = new BlockListList(BlockBegin::number_of_blocks(), NULL);
1279 _blocks = new BlockList();
1280
1281 int i;
1282 hir->start()->iterate_preorder(this);
1283 if (hir->code() != NULL) {
1284 assert(hir->code()->length() == _blocks->length(), "must match");
1285 for (i = 0; i < _blocks->length(); i++) {
1286 assert(hir->code()->contains(_blocks->at(i)), "should be in both lists");
1287 }
1288 }
1289
1290 for (i = 0; i < _blocks->length(); i++) {
1291 BlockBegin* block = _blocks->at(i);
1292 BlockList* preds = _predecessors->at(block->block_id());
1293 if (preds == NULL) {
1294 assert(block->number_of_preds() == 0, "should be the same");
1295 continue;
1296 }
1297
1298 // clone the pred list so we can mutate it
1299 BlockList* pred_copy = new BlockList();
1300 int j;
1301 for (j = 0; j < block->number_of_preds(); j++) {
1302 pred_copy->append(block->pred_at(j));
1303 }
1304 // sort them in the same order
1305 preds->sort(cmp);
1306 pred_copy->sort(cmp);
1307 int length = MIN2(preds->length(), block->number_of_preds());
1308 for (j = 0; j < block->number_of_preds(); j++) {
1309 assert(preds->at(j) == pred_copy->at(j), "must match");
1310 }
1311
1312 assert(preds->length() == block->number_of_preds(), "should be the same");
1313 }
1314 }
1315
1316 virtual void block_do(BlockBegin* block) {
1317 _blocks->append(block);
1318 BlockEnd* be = block->end();
1319 int n = be->number_of_sux();
1320 int i;
1321 for (i = 0; i < n; i++) {
1322 BlockBegin* sux = be->sux_at(i);
1323 assert(!sux->is_set(BlockBegin::exception_entry_flag), "must not be xhandler");
1324
1325 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1326 if (preds == NULL) {
1327 preds = new BlockList();
1328 _predecessors->at_put(sux->block_id(), preds);
1329 }
1330 preds->append(block);
1331 }
1332
1333 n = block->number_of_exception_handlers();
1334 for (i = 0; i < n; i++) {
1335 BlockBegin* sux = block->exception_handler_at(i);
1336 assert(sux->is_set(BlockBegin::exception_entry_flag), "must be xhandler");
1337
1338 BlockList* preds = _predecessors->at_grow(sux->block_id(), NULL);
1339 if (preds == NULL) {
1340 preds = new BlockList();
1341 _predecessors->at_put(sux->block_id(), preds);
1342 }
1343 preds->append(block);
1344 }
1345 }
1346 };
1347
1348 class VerifyBlockBeginField : public BlockClosure {
1349
1350 public:
1351
1352 virtual void block_do(BlockBegin *block) {
1353 for ( Instruction *cur = block; cur != NULL; cur = cur->next()) {
1354 assert(cur->block() == block, "Block begin is not correct");
1355 }
1356 }
1357 };
1358
1359 void IR::verify() {
1360 #ifdef ASSERT
1361 PredecessorValidator pv(this);
1362 VerifyBlockBeginField verifier;
1363 this->iterate_postorder(&verifier);
1364 #endif
1365 }
1366
1367 #endif // PRODUCT
1368
1369 void SubstitutionResolver::visit(Value* v) {
1370 Value v0 = *v;
1371 if (v0) {
1372 Value vs = v0->subst();
1373 if (vs != v0) {
1374 *v = v0->subst();
1375 }
1376 }
1377 }
1378
1379 #ifdef ASSERT
1380 class SubstitutionChecker: public ValueVisitor {
1381 void visit(Value* v) {
1382 Value v0 = *v;
1383 if (v0) {
1384 Value vs = v0->subst();
1385 assert(vs == v0, "missed substitution");
1386 }
1387 }
1388 };
1389 #endif
1390
1391
1392 void SubstitutionResolver::block_do(BlockBegin* block) {
1393 Instruction* last = NULL;
1394 for (Instruction* n = block; n != NULL;) {
1395 n->values_do(this);
1396 // need to remove this instruction from the instruction stream
1397 if (n->subst() != n) {
1398 assert(last != NULL, "must have last");
1399 last->set_next(n->next());
1400 } else {
1401 last = n;
1402 }
1403 n = last->next();
1404 }
1405
1406 #ifdef ASSERT
1407 SubstitutionChecker check_substitute;
1408 if (block->state()) block->state()->values_do(&check_substitute);
1409 block->block_values_do(&check_substitute);
1410 if (block->end() && block->end()->state()) block->end()->state()->values_do(&check_substitute);
1411 #endif
1412 }