Mercurial > hg > truffle
annotate src/share/vm/c1/c1_Optimizer.cpp @ 1764:14197af1010e
Merge
author | never |
---|---|
date | Fri, 27 Aug 2010 17:35:08 -0700 |
parents | b812ff5abc73 |
children | d5d065957597 |
rev | line source |
---|---|
0 | 1 /* |
1552
c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
trims
parents:
579
diff
changeset
|
2 * Copyright (c) 1999, 2009, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
1552
c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
trims
parents:
579
diff
changeset
|
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
trims
parents:
579
diff
changeset
|
20 * or visit www.oracle.com if you need additional information or have any |
c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
trims
parents:
579
diff
changeset
|
21 * questions. |
0 | 22 * |
23 */ | |
24 | |
25 #include "incls/_precompiled.incl" | |
26 #include "incls/_c1_Optimizer.cpp.incl" | |
27 | |
28 define_array(ValueSetArray, ValueSet*); | |
29 define_stack(ValueSetList, ValueSetArray); | |
30 | |
31 | |
32 Optimizer::Optimizer(IR* ir) { | |
33 assert(ir->is_valid(), "IR must be valid"); | |
34 _ir = ir; | |
35 } | |
36 | |
37 class CE_Eliminator: public BlockClosure { | |
38 private: | |
39 IR* _hir; | |
40 int _cee_count; // the number of CEs successfully eliminated | |
41 int _has_substitution; | |
42 | |
43 public: | |
44 CE_Eliminator(IR* hir) : _cee_count(0), _hir(hir) { | |
45 _has_substitution = false; | |
46 _hir->iterate_preorder(this); | |
47 if (_has_substitution) { | |
48 // substituted some phis so resolve the substitution | |
49 SubstitutionResolver sr(_hir); | |
50 } | |
51 } | |
52 int cee_count() const { return _cee_count; } | |
53 | |
54 void adjust_exception_edges(BlockBegin* block, BlockBegin* sux) { | |
55 int e = sux->number_of_exception_handlers(); | |
56 for (int i = 0; i < e; i++) { | |
57 BlockBegin* xhandler = sux->exception_handler_at(i); | |
58 block->add_exception_handler(xhandler); | |
59 | |
60 assert(xhandler->is_predecessor(sux), "missing predecessor"); | |
61 if (sux->number_of_preds() == 0) { | |
62 // sux is disconnected from graph so disconnect from exception handlers | |
63 xhandler->remove_predecessor(sux); | |
64 } | |
65 if (!xhandler->is_predecessor(block)) { | |
66 xhandler->add_predecessor(block); | |
67 } | |
68 } | |
69 } | |
70 | |
71 virtual void block_do(BlockBegin* block) { | |
72 // 1) find conditional expression | |
73 // check if block ends with an If | |
74 If* if_ = block->end()->as_If(); | |
75 if (if_ == NULL) return; | |
76 | |
77 // check if If works on int or object types | |
78 // (we cannot handle If's working on long, float or doubles yet, | |
79 // since IfOp doesn't support them - these If's show up if cmp | |
80 // operations followed by If's are eliminated) | |
81 ValueType* if_type = if_->x()->type(); | |
82 if (!if_type->is_int() && !if_type->is_object()) return; | |
83 | |
84 BlockBegin* t_block = if_->tsux(); | |
85 BlockBegin* f_block = if_->fsux(); | |
86 Instruction* t_cur = t_block->next(); | |
87 Instruction* f_cur = f_block->next(); | |
88 | |
89 // one Constant may be present between BlockBegin and BlockEnd | |
90 Value t_const = NULL; | |
91 Value f_const = NULL; | |
92 if (t_cur->as_Constant() != NULL && !t_cur->can_trap()) { | |
93 t_const = t_cur; | |
94 t_cur = t_cur->next(); | |
95 } | |
96 if (f_cur->as_Constant() != NULL && !f_cur->can_trap()) { | |
97 f_const = f_cur; | |
98 f_cur = f_cur->next(); | |
99 } | |
100 | |
101 // check if both branches end with a goto | |
102 Goto* t_goto = t_cur->as_Goto(); | |
103 if (t_goto == NULL) return; | |
104 Goto* f_goto = f_cur->as_Goto(); | |
105 if (f_goto == NULL) return; | |
106 | |
107 // check if both gotos merge into the same block | |
108 BlockBegin* sux = t_goto->default_sux(); | |
109 if (sux != f_goto->default_sux()) return; | |
110 | |
111 // check if at least one word was pushed on sux_state | |
112 ValueStack* sux_state = sux->state(); | |
113 if (sux_state->stack_size() <= if_->state()->stack_size()) return; | |
114 | |
115 // check if phi function is present at end of successor stack and that | |
116 // only this phi was pushed on the stack | |
117 Value sux_phi = sux_state->stack_at(if_->state()->stack_size()); | |
118 if (sux_phi == NULL || sux_phi->as_Phi() == NULL || sux_phi->as_Phi()->block() != sux) return; | |
119 if (sux_phi->type()->size() != sux_state->stack_size() - if_->state()->stack_size()) return; | |
120 | |
121 // get the values that were pushed in the true- and false-branch | |
122 Value t_value = t_goto->state()->stack_at(if_->state()->stack_size()); | |
123 Value f_value = f_goto->state()->stack_at(if_->state()->stack_size()); | |
124 | |
125 // backend does not support floats | |
126 assert(t_value->type()->base() == f_value->type()->base(), "incompatible types"); | |
127 if (t_value->type()->is_float_kind()) return; | |
128 | |
129 // check that successor has no other phi functions but sux_phi | |
130 // this can happen when t_block or f_block contained additonal stores to local variables | |
131 // that are no longer represented by explicit instructions | |
132 for_each_phi_fun(sux, phi, | |
133 if (phi != sux_phi) return; | |
134 ); | |
135 // true and false blocks can't have phis | |
136 for_each_phi_fun(t_block, phi, return; ); | |
137 for_each_phi_fun(f_block, phi, return; ); | |
138 | |
139 // 2) substitute conditional expression | |
140 // with an IfOp followed by a Goto | |
141 // cut if_ away and get node before | |
142 Instruction* cur_end = if_->prev(block); | |
143 int bci = if_->bci(); | |
144 | |
145 // append constants of true- and false-block if necessary | |
146 // clone constants because original block must not be destroyed | |
147 assert((t_value != f_const && f_value != t_const) || t_const == f_const, "mismatch"); | |
148 if (t_value == t_const) { | |
149 t_value = new Constant(t_const->type()); | |
150 cur_end = cur_end->set_next(t_value, bci); | |
151 } | |
152 if (f_value == f_const) { | |
153 f_value = new Constant(f_const->type()); | |
154 cur_end = cur_end->set_next(f_value, bci); | |
155 } | |
156 | |
157 // it is very unlikely that the condition can be statically decided | |
158 // (this was checked previously by the Canonicalizer), so always | |
159 // append IfOp | |
160 Value result = new IfOp(if_->x(), if_->cond(), if_->y(), t_value, f_value); | |
161 cur_end = cur_end->set_next(result, bci); | |
162 | |
163 // append Goto to successor | |
164 ValueStack* state_before = if_->is_safepoint() ? if_->state_before() : NULL; | |
165 Goto* goto_ = new Goto(sux, state_before, if_->is_safepoint() || t_goto->is_safepoint() || f_goto->is_safepoint()); | |
166 | |
167 // prepare state for Goto | |
168 ValueStack* goto_state = if_->state(); | |
169 while (sux_state->scope() != goto_state->scope()) { | |
170 goto_state = goto_state->pop_scope(); | |
171 assert(goto_state != NULL, "states do not match up"); | |
172 } | |
173 goto_state = goto_state->copy(); | |
174 goto_state->push(result->type(), result); | |
175 assert(goto_state->is_same_across_scopes(sux_state), "states must match now"); | |
176 goto_->set_state(goto_state); | |
177 | |
178 // Steal the bci for the goto from the sux | |
179 cur_end = cur_end->set_next(goto_, sux->bci()); | |
180 | |
181 // Adjust control flow graph | |
182 BlockBegin::disconnect_edge(block, t_block); | |
183 BlockBegin::disconnect_edge(block, f_block); | |
184 if (t_block->number_of_preds() == 0) { | |
185 BlockBegin::disconnect_edge(t_block, sux); | |
186 } | |
187 adjust_exception_edges(block, t_block); | |
188 if (f_block->number_of_preds() == 0) { | |
189 BlockBegin::disconnect_edge(f_block, sux); | |
190 } | |
191 adjust_exception_edges(block, f_block); | |
192 | |
193 // update block end | |
194 block->set_end(goto_); | |
195 | |
196 // substitute the phi if possible | |
197 if (sux_phi->as_Phi()->operand_count() == 1) { | |
198 assert(sux_phi->as_Phi()->operand_at(0) == result, "screwed up phi"); | |
199 sux_phi->set_subst(result); | |
200 _has_substitution = true; | |
201 } | |
202 | |
203 // 3) successfully eliminated a conditional expression | |
204 _cee_count++; | |
205 if (PrintCEE) { | |
206 tty->print_cr("%d. CEE in B%d (B%d B%d)", cee_count(), block->block_id(), t_block->block_id(), f_block->block_id()); | |
207 } | |
208 | |
209 _hir->verify(); | |
210 } | |
211 }; | |
212 | |
213 | |
214 void Optimizer::eliminate_conditional_expressions() { | |
215 // find conditional expressions & replace them with IfOps | |
216 CE_Eliminator ce(ir()); | |
217 } | |
218 | |
219 | |
220 class BlockMerger: public BlockClosure { | |
221 private: | |
222 IR* _hir; | |
223 int _merge_count; // the number of block pairs successfully merged | |
224 | |
225 public: | |
226 BlockMerger(IR* hir) | |
227 : _hir(hir) | |
228 , _merge_count(0) | |
229 { | |
230 _hir->iterate_preorder(this); | |
231 } | |
232 | |
233 bool try_merge(BlockBegin* block) { | |
234 BlockEnd* end = block->end(); | |
235 if (end->as_Goto() != NULL) { | |
236 assert(end->number_of_sux() == 1, "end must have exactly one successor"); | |
237 // Note: It would be sufficient to check for the number of successors (= 1) | |
238 // in order to decide if this block can be merged potentially. That | |
239 // would then also include switch statements w/ only a default case. | |
240 // However, in that case we would need to make sure the switch tag | |
241 // expression is executed if it can produce observable side effects. | |
242 // We should probably have the canonicalizer simplifying such switch | |
243 // statements and then we are sure we don't miss these merge opportunities | |
244 // here (was bug - gri 7/7/99). | |
245 BlockBegin* sux = end->default_sux(); | |
246 if (sux->number_of_preds() == 1 && !sux->is_entry_block() && !end->is_safepoint()) { | |
247 // merge the two blocks | |
248 | |
249 #ifdef ASSERT | |
250 // verify that state at the end of block and at the beginning of sux are equal | |
251 // no phi functions must be present at beginning of sux | |
252 ValueStack* sux_state = sux->state(); | |
253 ValueStack* end_state = end->state(); | |
254 while (end_state->scope() != sux_state->scope()) { | |
255 // match up inlining level | |
256 end_state = end_state->pop_scope(); | |
257 } | |
258 assert(end_state->stack_size() == sux_state->stack_size(), "stack not equal"); | |
259 assert(end_state->locals_size() == sux_state->locals_size(), "locals not equal"); | |
260 | |
261 int index; | |
262 Value sux_value; | |
263 for_each_stack_value(sux_state, index, sux_value) { | |
264 assert(sux_value == end_state->stack_at(index), "stack not equal"); | |
265 } | |
266 for_each_local_value(sux_state, index, sux_value) { | |
267 assert(sux_value == end_state->local_at(index), "locals not equal"); | |
268 } | |
269 assert(sux_state->caller_state() == end_state->caller_state(), "caller not equal"); | |
270 #endif | |
271 | |
272 // find instruction before end & append first instruction of sux block | |
273 Instruction* prev = end->prev(block); | |
274 Instruction* next = sux->next(); | |
275 assert(prev->as_BlockEnd() == NULL, "must not be a BlockEnd"); | |
276 prev->set_next(next, next->bci()); | |
277 sux->disconnect_from_graph(); | |
278 block->set_end(sux->end()); | |
279 // add exception handlers of deleted block, if any | |
280 for (int k = 0; k < sux->number_of_exception_handlers(); k++) { | |
281 BlockBegin* xhandler = sux->exception_handler_at(k); | |
282 block->add_exception_handler(xhandler); | |
283 | |
284 // also substitute predecessor of exception handler | |
285 assert(xhandler->is_predecessor(sux), "missing predecessor"); | |
286 xhandler->remove_predecessor(sux); | |
287 if (!xhandler->is_predecessor(block)) { | |
288 xhandler->add_predecessor(block); | |
289 } | |
290 } | |
291 | |
292 // debugging output | |
293 _merge_count++; | |
294 if (PrintBlockElimination) { | |
295 tty->print_cr("%d. merged B%d & B%d (stack size = %d)", | |
296 _merge_count, block->block_id(), sux->block_id(), sux->state()->stack_size()); | |
297 } | |
298 | |
299 _hir->verify(); | |
300 | |
301 If* if_ = block->end()->as_If(); | |
302 if (if_) { | |
303 IfOp* ifop = if_->x()->as_IfOp(); | |
304 Constant* con = if_->y()->as_Constant(); | |
305 bool swapped = false; | |
306 if (!con || !ifop) { | |
307 ifop = if_->y()->as_IfOp(); | |
308 con = if_->x()->as_Constant(); | |
309 swapped = true; | |
310 } | |
311 if (con && ifop) { | |
312 Constant* tval = ifop->tval()->as_Constant(); | |
313 Constant* fval = ifop->fval()->as_Constant(); | |
314 if (tval && fval) { | |
315 // Find the instruction before if_, starting with ifop. | |
316 // When if_ and ifop are not in the same block, prev | |
317 // becomes NULL In such (rare) cases it is not | |
318 // profitable to perform the optimization. | |
319 Value prev = ifop; | |
320 while (prev != NULL && prev->next() != if_) { | |
321 prev = prev->next(); | |
322 } | |
323 | |
324 if (prev != NULL) { | |
325 Instruction::Condition cond = if_->cond(); | |
326 BlockBegin* tsux = if_->tsux(); | |
327 BlockBegin* fsux = if_->fsux(); | |
328 if (swapped) { | |
329 cond = Instruction::mirror(cond); | |
330 } | |
331 | |
332 BlockBegin* tblock = tval->compare(cond, con, tsux, fsux); | |
333 BlockBegin* fblock = fval->compare(cond, con, tsux, fsux); | |
334 if (tblock != fblock && !if_->is_safepoint()) { | |
335 If* newif = new If(ifop->x(), ifop->cond(), false, ifop->y(), | |
336 tblock, fblock, if_->state_before(), if_->is_safepoint()); | |
337 newif->set_state(if_->state()->copy()); | |
338 | |
339 assert(prev->next() == if_, "must be guaranteed by above search"); | |
340 prev->set_next(newif, if_->bci()); | |
341 block->set_end(newif); | |
342 | |
343 _merge_count++; | |
344 if (PrintBlockElimination) { | |
345 tty->print_cr("%d. replaced If and IfOp at end of B%d with single If", _merge_count, block->block_id()); | |
346 } | |
347 | |
348 _hir->verify(); | |
349 } | |
350 } | |
351 } | |
352 } | |
353 } | |
354 | |
355 return true; | |
356 } | |
357 } | |
358 return false; | |
359 } | |
360 | |
361 virtual void block_do(BlockBegin* block) { | |
362 _hir->verify(); | |
363 // repeat since the same block may merge again | |
364 while (try_merge(block)) { | |
365 _hir->verify(); | |
366 } | |
367 } | |
368 }; | |
369 | |
370 | |
371 void Optimizer::eliminate_blocks() { | |
372 // merge blocks if possible | |
373 BlockMerger bm(ir()); | |
374 } | |
375 | |
376 | |
377 class NullCheckEliminator; | |
378 class NullCheckVisitor: public InstructionVisitor { | |
379 private: | |
380 NullCheckEliminator* _nce; | |
381 NullCheckEliminator* nce() { return _nce; } | |
382 | |
383 public: | |
384 NullCheckVisitor() {} | |
385 | |
386 void set_eliminator(NullCheckEliminator* nce) { _nce = nce; } | |
387 | |
388 void do_Phi (Phi* x); | |
389 void do_Local (Local* x); | |
390 void do_Constant (Constant* x); | |
391 void do_LoadField (LoadField* x); | |
392 void do_StoreField (StoreField* x); | |
393 void do_ArrayLength (ArrayLength* x); | |
394 void do_LoadIndexed (LoadIndexed* x); | |
395 void do_StoreIndexed (StoreIndexed* x); | |
396 void do_NegateOp (NegateOp* x); | |
397 void do_ArithmeticOp (ArithmeticOp* x); | |
398 void do_ShiftOp (ShiftOp* x); | |
399 void do_LogicOp (LogicOp* x); | |
400 void do_CompareOp (CompareOp* x); | |
401 void do_IfOp (IfOp* x); | |
402 void do_Convert (Convert* x); | |
403 void do_NullCheck (NullCheck* x); | |
404 void do_Invoke (Invoke* x); | |
405 void do_NewInstance (NewInstance* x); | |
406 void do_NewTypeArray (NewTypeArray* x); | |
407 void do_NewObjectArray (NewObjectArray* x); | |
408 void do_NewMultiArray (NewMultiArray* x); | |
409 void do_CheckCast (CheckCast* x); | |
410 void do_InstanceOf (InstanceOf* x); | |
411 void do_MonitorEnter (MonitorEnter* x); | |
412 void do_MonitorExit (MonitorExit* x); | |
413 void do_Intrinsic (Intrinsic* x); | |
414 void do_BlockBegin (BlockBegin* x); | |
415 void do_Goto (Goto* x); | |
416 void do_If (If* x); | |
417 void do_IfInstanceOf (IfInstanceOf* x); | |
418 void do_TableSwitch (TableSwitch* x); | |
419 void do_LookupSwitch (LookupSwitch* x); | |
420 void do_Return (Return* x); | |
421 void do_Throw (Throw* x); | |
422 void do_Base (Base* x); | |
423 void do_OsrEntry (OsrEntry* x); | |
424 void do_ExceptionObject(ExceptionObject* x); | |
425 void do_RoundFP (RoundFP* x); | |
426 void do_UnsafeGetRaw (UnsafeGetRaw* x); | |
427 void do_UnsafePutRaw (UnsafePutRaw* x); | |
428 void do_UnsafeGetObject(UnsafeGetObject* x); | |
429 void do_UnsafePutObject(UnsafePutObject* x); | |
430 void do_UnsafePrefetchRead (UnsafePrefetchRead* x); | |
431 void do_UnsafePrefetchWrite(UnsafePrefetchWrite* x); | |
432 void do_ProfileCall (ProfileCall* x); | |
433 void do_ProfileCounter (ProfileCounter* x); | |
434 }; | |
435 | |
436 | |
437 // Because of a static contained within (for the purpose of iteration | |
438 // over instructions), it is only valid to have one of these active at | |
439 // a time | |
1584 | 440 class NullCheckEliminator: public ValueVisitor { |
0 | 441 private: |
442 Optimizer* _opt; | |
443 | |
444 ValueSet* _visitable_instructions; // Visit each instruction only once per basic block | |
445 BlockList* _work_list; // Basic blocks to visit | |
446 | |
447 bool visitable(Value x) { | |
448 assert(_visitable_instructions != NULL, "check"); | |
449 return _visitable_instructions->contains(x); | |
450 } | |
451 void mark_visited(Value x) { | |
452 assert(_visitable_instructions != NULL, "check"); | |
453 _visitable_instructions->remove(x); | |
454 } | |
455 void mark_visitable(Value x) { | |
456 assert(_visitable_instructions != NULL, "check"); | |
457 _visitable_instructions->put(x); | |
458 } | |
459 void clear_visitable_state() { | |
460 assert(_visitable_instructions != NULL, "check"); | |
461 _visitable_instructions->clear(); | |
462 } | |
463 | |
464 ValueSet* _set; // current state, propagated to subsequent BlockBegins | |
465 ValueSetList _block_states; // BlockBegin null-check states for all processed blocks | |
466 NullCheckVisitor _visitor; | |
467 NullCheck* _last_explicit_null_check; | |
468 | |
469 bool set_contains(Value x) { assert(_set != NULL, "check"); return _set->contains(x); } | |
470 void set_put (Value x) { assert(_set != NULL, "check"); _set->put(x); } | |
471 void set_remove (Value x) { assert(_set != NULL, "check"); _set->remove(x); } | |
472 | |
473 BlockList* work_list() { return _work_list; } | |
474 | |
475 void iterate_all(); | |
476 void iterate_one(BlockBegin* block); | |
477 | |
478 ValueSet* state() { return _set; } | |
479 void set_state_from (ValueSet* state) { _set->set_from(state); } | |
480 ValueSet* state_for (BlockBegin* block) { return _block_states[block->block_id()]; } | |
481 void set_state_for (BlockBegin* block, ValueSet* stack) { _block_states[block->block_id()] = stack; } | |
482 // Returns true if caused a change in the block's state. | |
483 bool merge_state_for(BlockBegin* block, | |
484 ValueSet* incoming_state); | |
485 | |
486 public: | |
487 // constructor | |
488 NullCheckEliminator(Optimizer* opt) | |
489 : _opt(opt) | |
490 , _set(new ValueSet()) | |
491 , _last_explicit_null_check(NULL) | |
492 , _block_states(BlockBegin::number_of_blocks(), NULL) | |
493 , _work_list(new BlockList()) { | |
494 _visitable_instructions = new ValueSet(); | |
495 _visitor.set_eliminator(this); | |
496 } | |
497 | |
498 Optimizer* opt() { return _opt; } | |
499 IR* ir () { return opt()->ir(); } | |
500 | |
501 // Process a graph | |
502 void iterate(BlockBegin* root); | |
503 | |
1584 | 504 void visit(Value* f); |
505 | |
0 | 506 // In some situations (like NullCheck(x); getfield(x)) the debug |
507 // information from the explicit NullCheck can be used to populate | |
508 // the getfield, even if the two instructions are in different | |
509 // scopes; this allows implicit null checks to be used but the | |
510 // correct exception information to be generated. We must clear the | |
511 // last-traversed NullCheck when we reach a potentially-exception- | |
512 // throwing instruction, as well as in some other cases. | |
513 void set_last_explicit_null_check(NullCheck* check) { _last_explicit_null_check = check; } | |
514 NullCheck* last_explicit_null_check() { return _last_explicit_null_check; } | |
515 Value last_explicit_null_check_obj() { return (_last_explicit_null_check | |
516 ? _last_explicit_null_check->obj() | |
517 : NULL); } | |
518 NullCheck* consume_last_explicit_null_check() { | |
519 _last_explicit_null_check->unpin(Instruction::PinExplicitNullCheck); | |
520 _last_explicit_null_check->set_can_trap(false); | |
521 return _last_explicit_null_check; | |
522 } | |
523 void clear_last_explicit_null_check() { _last_explicit_null_check = NULL; } | |
524 | |
525 // Handlers for relevant instructions | |
526 // (separated out from NullCheckVisitor for clarity) | |
527 | |
528 // The basic contract is that these must leave the instruction in | |
529 // the desired state; must not assume anything about the state of | |
530 // the instruction. We make multiple passes over some basic blocks | |
531 // and the last pass is the only one whose result is valid. | |
532 void handle_AccessField (AccessField* x); | |
533 void handle_ArrayLength (ArrayLength* x); | |
534 void handle_LoadIndexed (LoadIndexed* x); | |
535 void handle_StoreIndexed (StoreIndexed* x); | |
536 void handle_NullCheck (NullCheck* x); | |
537 void handle_Invoke (Invoke* x); | |
538 void handle_NewInstance (NewInstance* x); | |
539 void handle_NewArray (NewArray* x); | |
540 void handle_AccessMonitor (AccessMonitor* x); | |
541 void handle_Intrinsic (Intrinsic* x); | |
542 void handle_ExceptionObject (ExceptionObject* x); | |
543 void handle_Phi (Phi* x); | |
544 }; | |
545 | |
546 | |
547 // NEEDS_CLEANUP | |
548 // There may be other instructions which need to clear the last | |
549 // explicit null check. Anything across which we can not hoist the | |
550 // debug information for a NullCheck instruction must clear it. It | |
551 // might be safer to pattern match "NullCheck ; {AccessField, | |
552 // ArrayLength, LoadIndexed}" but it is more easily structured this way. | |
553 // Should test to see performance hit of clearing it for all handlers | |
554 // with empty bodies below. If it is negligible then we should leave | |
555 // that in for safety, otherwise should think more about it. | |
556 void NullCheckVisitor::do_Phi (Phi* x) { nce()->handle_Phi(x); } | |
557 void NullCheckVisitor::do_Local (Local* x) {} | |
558 void NullCheckVisitor::do_Constant (Constant* x) { /* FIXME: handle object constants */ } | |
559 void NullCheckVisitor::do_LoadField (LoadField* x) { nce()->handle_AccessField(x); } | |
560 void NullCheckVisitor::do_StoreField (StoreField* x) { nce()->handle_AccessField(x); } | |
561 void NullCheckVisitor::do_ArrayLength (ArrayLength* x) { nce()->handle_ArrayLength(x); } | |
562 void NullCheckVisitor::do_LoadIndexed (LoadIndexed* x) { nce()->handle_LoadIndexed(x); } | |
563 void NullCheckVisitor::do_StoreIndexed (StoreIndexed* x) { nce()->handle_StoreIndexed(x); } | |
564 void NullCheckVisitor::do_NegateOp (NegateOp* x) {} | |
565 void NullCheckVisitor::do_ArithmeticOp (ArithmeticOp* x) { if (x->can_trap()) nce()->clear_last_explicit_null_check(); } | |
566 void NullCheckVisitor::do_ShiftOp (ShiftOp* x) {} | |
567 void NullCheckVisitor::do_LogicOp (LogicOp* x) {} | |
568 void NullCheckVisitor::do_CompareOp (CompareOp* x) {} | |
569 void NullCheckVisitor::do_IfOp (IfOp* x) {} | |
570 void NullCheckVisitor::do_Convert (Convert* x) {} | |
571 void NullCheckVisitor::do_NullCheck (NullCheck* x) { nce()->handle_NullCheck(x); } | |
572 void NullCheckVisitor::do_Invoke (Invoke* x) { nce()->handle_Invoke(x); } | |
573 void NullCheckVisitor::do_NewInstance (NewInstance* x) { nce()->handle_NewInstance(x); } | |
574 void NullCheckVisitor::do_NewTypeArray (NewTypeArray* x) { nce()->handle_NewArray(x); } | |
575 void NullCheckVisitor::do_NewObjectArray (NewObjectArray* x) { nce()->handle_NewArray(x); } | |
576 void NullCheckVisitor::do_NewMultiArray (NewMultiArray* x) { nce()->handle_NewArray(x); } | |
577 void NullCheckVisitor::do_CheckCast (CheckCast* x) {} | |
578 void NullCheckVisitor::do_InstanceOf (InstanceOf* x) {} | |
579 void NullCheckVisitor::do_MonitorEnter (MonitorEnter* x) { nce()->handle_AccessMonitor(x); } | |
580 void NullCheckVisitor::do_MonitorExit (MonitorExit* x) { nce()->handle_AccessMonitor(x); } | |
581 void NullCheckVisitor::do_Intrinsic (Intrinsic* x) { nce()->clear_last_explicit_null_check(); } | |
582 void NullCheckVisitor::do_BlockBegin (BlockBegin* x) {} | |
583 void NullCheckVisitor::do_Goto (Goto* x) {} | |
584 void NullCheckVisitor::do_If (If* x) {} | |
585 void NullCheckVisitor::do_IfInstanceOf (IfInstanceOf* x) {} | |
586 void NullCheckVisitor::do_TableSwitch (TableSwitch* x) {} | |
587 void NullCheckVisitor::do_LookupSwitch (LookupSwitch* x) {} | |
588 void NullCheckVisitor::do_Return (Return* x) {} | |
589 void NullCheckVisitor::do_Throw (Throw* x) { nce()->clear_last_explicit_null_check(); } | |
590 void NullCheckVisitor::do_Base (Base* x) {} | |
591 void NullCheckVisitor::do_OsrEntry (OsrEntry* x) {} | |
592 void NullCheckVisitor::do_ExceptionObject(ExceptionObject* x) { nce()->handle_ExceptionObject(x); } | |
593 void NullCheckVisitor::do_RoundFP (RoundFP* x) {} | |
594 void NullCheckVisitor::do_UnsafeGetRaw (UnsafeGetRaw* x) {} | |
595 void NullCheckVisitor::do_UnsafePutRaw (UnsafePutRaw* x) {} | |
596 void NullCheckVisitor::do_UnsafeGetObject(UnsafeGetObject* x) {} | |
597 void NullCheckVisitor::do_UnsafePutObject(UnsafePutObject* x) {} | |
598 void NullCheckVisitor::do_UnsafePrefetchRead (UnsafePrefetchRead* x) {} | |
599 void NullCheckVisitor::do_UnsafePrefetchWrite(UnsafePrefetchWrite* x) {} | |
600 void NullCheckVisitor::do_ProfileCall (ProfileCall* x) { nce()->clear_last_explicit_null_check(); } | |
601 void NullCheckVisitor::do_ProfileCounter (ProfileCounter* x) {} | |
602 | |
603 | |
1584 | 604 void NullCheckEliminator::visit(Value* p) { |
0 | 605 assert(*p != NULL, "should not find NULL instructions"); |
1584 | 606 if (visitable(*p)) { |
607 mark_visited(*p); | |
608 (*p)->visit(&_visitor); | |
0 | 609 } |
610 } | |
611 | |
612 bool NullCheckEliminator::merge_state_for(BlockBegin* block, ValueSet* incoming_state) { | |
613 ValueSet* state = state_for(block); | |
614 if (state == NULL) { | |
615 state = incoming_state->copy(); | |
616 set_state_for(block, state); | |
617 return true; | |
618 } else { | |
619 bool changed = state->set_intersect(incoming_state); | |
620 if (PrintNullCheckElimination && changed) { | |
621 tty->print_cr("Block %d's null check state changed", block->block_id()); | |
622 } | |
623 return changed; | |
624 } | |
625 } | |
626 | |
627 | |
628 void NullCheckEliminator::iterate_all() { | |
629 while (work_list()->length() > 0) { | |
630 iterate_one(work_list()->pop()); | |
631 } | |
632 } | |
633 | |
634 | |
635 void NullCheckEliminator::iterate_one(BlockBegin* block) { | |
636 clear_visitable_state(); | |
637 // clear out an old explicit null checks | |
638 set_last_explicit_null_check(NULL); | |
639 | |
640 if (PrintNullCheckElimination) { | |
641 tty->print_cr(" ...iterating block %d in null check elimination for %s::%s%s", | |
642 block->block_id(), | |
643 ir()->method()->holder()->name()->as_utf8(), | |
644 ir()->method()->name()->as_utf8(), | |
645 ir()->method()->signature()->as_symbol()->as_utf8()); | |
646 } | |
647 | |
648 // Create new state if none present (only happens at root) | |
649 if (state_for(block) == NULL) { | |
650 ValueSet* tmp_state = new ValueSet(); | |
651 set_state_for(block, tmp_state); | |
652 // Initial state is that local 0 (receiver) is non-null for | |
653 // non-static methods | |
654 ValueStack* stack = block->state(); | |
655 IRScope* scope = stack->scope(); | |
656 ciMethod* method = scope->method(); | |
657 if (!method->is_static()) { | |
658 Local* local0 = stack->local_at(0)->as_Local(); | |
659 assert(local0 != NULL, "must be"); | |
660 assert(local0->type() == objectType, "invalid type of receiver"); | |
661 | |
662 if (local0 != NULL) { | |
663 // Local 0 is used in this scope | |
664 tmp_state->put(local0); | |
665 if (PrintNullCheckElimination) { | |
666 tty->print_cr("Local 0 (value %d) proven non-null upon entry", local0->id()); | |
667 } | |
668 } | |
669 } | |
670 } | |
671 | |
672 // Must copy block's state to avoid mutating it during iteration | |
673 // through the block -- otherwise "not-null" states can accidentally | |
674 // propagate "up" through the block during processing of backward | |
675 // branches and algorithm is incorrect (and does not converge) | |
676 set_state_from(state_for(block)); | |
677 | |
678 // allow visiting of Phis belonging to this block | |
679 for_each_phi_fun(block, phi, | |
680 mark_visitable(phi); | |
681 ); | |
682 | |
683 BlockEnd* e = block->end(); | |
684 assert(e != NULL, "incomplete graph"); | |
685 int i; | |
686 | |
687 // Propagate the state before this block into the exception | |
688 // handlers. They aren't true successors since we aren't guaranteed | |
689 // to execute the whole block before executing them. Also putting | |
690 // them on first seems to help reduce the amount of iteration to | |
691 // reach a fixed point. | |
692 for (i = 0; i < block->number_of_exception_handlers(); i++) { | |
693 BlockBegin* next = block->exception_handler_at(i); | |
694 if (merge_state_for(next, state())) { | |
695 if (!work_list()->contains(next)) { | |
696 work_list()->push(next); | |
697 } | |
698 } | |
699 } | |
700 | |
701 // Iterate through block, updating state. | |
702 for (Instruction* instr = block; instr != NULL; instr = instr->next()) { | |
703 // Mark instructions in this block as visitable as they are seen | |
704 // in the instruction list. This keeps the iteration from | |
705 // visiting instructions which are references in other blocks or | |
706 // visiting instructions more than once. | |
707 mark_visitable(instr); | |
708 if (instr->is_root() || instr->can_trap() || (instr->as_NullCheck() != NULL)) { | |
709 mark_visited(instr); | |
1584 | 710 instr->input_values_do(this); |
0 | 711 instr->visit(&_visitor); |
712 } | |
713 } | |
714 | |
715 // Propagate state to successors if necessary | |
716 for (i = 0; i < e->number_of_sux(); i++) { | |
717 BlockBegin* next = e->sux_at(i); | |
718 if (merge_state_for(next, state())) { | |
719 if (!work_list()->contains(next)) { | |
720 work_list()->push(next); | |
721 } | |
722 } | |
723 } | |
724 } | |
725 | |
726 | |
727 void NullCheckEliminator::iterate(BlockBegin* block) { | |
728 work_list()->push(block); | |
729 iterate_all(); | |
730 } | |
731 | |
732 void NullCheckEliminator::handle_AccessField(AccessField* x) { | |
733 if (x->is_static()) { | |
734 if (x->as_LoadField() != NULL) { | |
735 // If the field is a non-null static final object field (as is | |
736 // often the case for sun.misc.Unsafe), put this LoadField into | |
737 // the non-null map | |
738 ciField* field = x->field(); | |
739 if (field->is_constant()) { | |
740 ciConstant field_val = field->constant_value(); | |
741 BasicType field_type = field_val.basic_type(); | |
742 if (field_type == T_OBJECT || field_type == T_ARRAY) { | |
743 ciObject* obj_val = field_val.as_object(); | |
744 if (!obj_val->is_null_object()) { | |
745 if (PrintNullCheckElimination) { | |
746 tty->print_cr("AccessField %d proven non-null by static final non-null oop check", | |
747 x->id()); | |
748 } | |
749 set_put(x); | |
750 } | |
751 } | |
752 } | |
753 } | |
754 // Be conservative | |
755 clear_last_explicit_null_check(); | |
756 return; | |
757 } | |
758 | |
759 Value obj = x->obj(); | |
760 if (set_contains(obj)) { | |
761 // Value is non-null => update AccessField | |
762 if (last_explicit_null_check_obj() == obj && !x->needs_patching()) { | |
763 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
764 x->set_needs_null_check(true); | |
765 if (PrintNullCheckElimination) { | |
766 tty->print_cr("Folded NullCheck %d into AccessField %d's null check for value %d", | |
767 x->explicit_null_check()->id(), x->id(), obj->id()); | |
768 } | |
769 } else { | |
770 x->set_explicit_null_check(NULL); | |
771 x->set_needs_null_check(false); | |
772 if (PrintNullCheckElimination) { | |
773 tty->print_cr("Eliminated AccessField %d's null check for value %d", x->id(), obj->id()); | |
774 } | |
775 } | |
776 } else { | |
777 set_put(obj); | |
778 if (PrintNullCheckElimination) { | |
779 tty->print_cr("AccessField %d of value %d proves value to be non-null", x->id(), obj->id()); | |
780 } | |
781 // Ensure previous passes do not cause wrong state | |
782 x->set_needs_null_check(true); | |
783 x->set_explicit_null_check(NULL); | |
784 } | |
785 clear_last_explicit_null_check(); | |
786 } | |
787 | |
788 | |
789 void NullCheckEliminator::handle_ArrayLength(ArrayLength* x) { | |
790 Value array = x->array(); | |
791 if (set_contains(array)) { | |
792 // Value is non-null => update AccessArray | |
793 if (last_explicit_null_check_obj() == array) { | |
794 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
795 x->set_needs_null_check(true); | |
796 if (PrintNullCheckElimination) { | |
797 tty->print_cr("Folded NullCheck %d into ArrayLength %d's null check for value %d", | |
798 x->explicit_null_check()->id(), x->id(), array->id()); | |
799 } | |
800 } else { | |
801 x->set_explicit_null_check(NULL); | |
802 x->set_needs_null_check(false); | |
803 if (PrintNullCheckElimination) { | |
804 tty->print_cr("Eliminated ArrayLength %d's null check for value %d", x->id(), array->id()); | |
805 } | |
806 } | |
807 } else { | |
808 set_put(array); | |
809 if (PrintNullCheckElimination) { | |
810 tty->print_cr("ArrayLength %d of value %d proves value to be non-null", x->id(), array->id()); | |
811 } | |
812 // Ensure previous passes do not cause wrong state | |
813 x->set_needs_null_check(true); | |
814 x->set_explicit_null_check(NULL); | |
815 } | |
816 clear_last_explicit_null_check(); | |
817 } | |
818 | |
819 | |
820 void NullCheckEliminator::handle_LoadIndexed(LoadIndexed* x) { | |
821 Value array = x->array(); | |
822 if (set_contains(array)) { | |
823 // Value is non-null => update AccessArray | |
824 if (last_explicit_null_check_obj() == array) { | |
825 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
826 x->set_needs_null_check(true); | |
827 if (PrintNullCheckElimination) { | |
828 tty->print_cr("Folded NullCheck %d into LoadIndexed %d's null check for value %d", | |
829 x->explicit_null_check()->id(), x->id(), array->id()); | |
830 } | |
831 } else { | |
832 x->set_explicit_null_check(NULL); | |
833 x->set_needs_null_check(false); | |
834 if (PrintNullCheckElimination) { | |
835 tty->print_cr("Eliminated LoadIndexed %d's null check for value %d", x->id(), array->id()); | |
836 } | |
837 } | |
838 } else { | |
839 set_put(array); | |
840 if (PrintNullCheckElimination) { | |
841 tty->print_cr("LoadIndexed %d of value %d proves value to be non-null", x->id(), array->id()); | |
842 } | |
843 // Ensure previous passes do not cause wrong state | |
844 x->set_needs_null_check(true); | |
845 x->set_explicit_null_check(NULL); | |
846 } | |
847 clear_last_explicit_null_check(); | |
848 } | |
849 | |
850 | |
851 void NullCheckEliminator::handle_StoreIndexed(StoreIndexed* x) { | |
852 Value array = x->array(); | |
853 if (set_contains(array)) { | |
854 // Value is non-null => update AccessArray | |
855 if (PrintNullCheckElimination) { | |
856 tty->print_cr("Eliminated StoreIndexed %d's null check for value %d", x->id(), array->id()); | |
857 } | |
858 x->set_needs_null_check(false); | |
859 } else { | |
860 set_put(array); | |
861 if (PrintNullCheckElimination) { | |
862 tty->print_cr("StoreIndexed %d of value %d proves value to be non-null", x->id(), array->id()); | |
863 } | |
864 // Ensure previous passes do not cause wrong state | |
865 x->set_needs_null_check(true); | |
866 } | |
867 clear_last_explicit_null_check(); | |
868 } | |
869 | |
870 | |
871 void NullCheckEliminator::handle_NullCheck(NullCheck* x) { | |
872 Value obj = x->obj(); | |
873 if (set_contains(obj)) { | |
874 // Already proven to be non-null => this NullCheck is useless | |
875 if (PrintNullCheckElimination) { | |
876 tty->print_cr("Eliminated NullCheck %d for value %d", x->id(), obj->id()); | |
877 } | |
878 // Don't unpin since that may shrink obj's live range and make it unavailable for debug info. | |
879 // The code generator won't emit LIR for a NullCheck that cannot trap. | |
880 x->set_can_trap(false); | |
881 } else { | |
882 // May be null => add to map and set last explicit NullCheck | |
883 x->set_can_trap(true); | |
884 // make sure it's pinned if it can trap | |
885 x->pin(Instruction::PinExplicitNullCheck); | |
886 set_put(obj); | |
887 set_last_explicit_null_check(x); | |
888 if (PrintNullCheckElimination) { | |
889 tty->print_cr("NullCheck %d of value %d proves value to be non-null", x->id(), obj->id()); | |
890 } | |
891 } | |
892 } | |
893 | |
894 | |
895 void NullCheckEliminator::handle_Invoke(Invoke* x) { | |
896 if (!x->has_receiver()) { | |
897 // Be conservative | |
898 clear_last_explicit_null_check(); | |
899 return; | |
900 } | |
901 | |
902 Value recv = x->receiver(); | |
903 if (!set_contains(recv)) { | |
904 set_put(recv); | |
905 if (PrintNullCheckElimination) { | |
906 tty->print_cr("Invoke %d of value %d proves value to be non-null", x->id(), recv->id()); | |
907 } | |
908 } | |
909 clear_last_explicit_null_check(); | |
910 } | |
911 | |
912 | |
913 void NullCheckEliminator::handle_NewInstance(NewInstance* x) { | |
914 set_put(x); | |
915 if (PrintNullCheckElimination) { | |
916 tty->print_cr("NewInstance %d is non-null", x->id()); | |
917 } | |
918 } | |
919 | |
920 | |
921 void NullCheckEliminator::handle_NewArray(NewArray* x) { | |
922 set_put(x); | |
923 if (PrintNullCheckElimination) { | |
924 tty->print_cr("NewArray %d is non-null", x->id()); | |
925 } | |
926 } | |
927 | |
928 | |
929 void NullCheckEliminator::handle_ExceptionObject(ExceptionObject* x) { | |
930 set_put(x); | |
931 if (PrintNullCheckElimination) { | |
932 tty->print_cr("ExceptionObject %d is non-null", x->id()); | |
933 } | |
934 } | |
935 | |
936 | |
937 void NullCheckEliminator::handle_AccessMonitor(AccessMonitor* x) { | |
938 Value obj = x->obj(); | |
939 if (set_contains(obj)) { | |
940 // Value is non-null => update AccessMonitor | |
941 if (PrintNullCheckElimination) { | |
942 tty->print_cr("Eliminated AccessMonitor %d's null check for value %d", x->id(), obj->id()); | |
943 } | |
944 x->set_needs_null_check(false); | |
945 } else { | |
946 set_put(obj); | |
947 if (PrintNullCheckElimination) { | |
948 tty->print_cr("AccessMonitor %d of value %d proves value to be non-null", x->id(), obj->id()); | |
949 } | |
950 // Ensure previous passes do not cause wrong state | |
951 x->set_needs_null_check(true); | |
952 } | |
953 clear_last_explicit_null_check(); | |
954 } | |
955 | |
956 | |
957 void NullCheckEliminator::handle_Intrinsic(Intrinsic* x) { | |
958 if (!x->has_receiver()) { | |
959 // Be conservative | |
960 clear_last_explicit_null_check(); | |
961 return; | |
962 } | |
963 | |
964 Value recv = x->receiver(); | |
965 if (set_contains(recv)) { | |
966 // Value is non-null => update Intrinsic | |
967 if (PrintNullCheckElimination) { | |
968 tty->print_cr("Eliminated Intrinsic %d's null check for value %d", x->id(), recv->id()); | |
969 } | |
970 x->set_needs_null_check(false); | |
971 } else { | |
972 set_put(recv); | |
973 if (PrintNullCheckElimination) { | |
974 tty->print_cr("Intrinsic %d of value %d proves value to be non-null", x->id(), recv->id()); | |
975 } | |
976 // Ensure previous passes do not cause wrong state | |
977 x->set_needs_null_check(true); | |
978 } | |
979 clear_last_explicit_null_check(); | |
980 } | |
981 | |
982 | |
983 void NullCheckEliminator::handle_Phi(Phi* x) { | |
984 int i; | |
985 bool all_non_null = true; | |
986 if (x->is_illegal()) { | |
987 all_non_null = false; | |
988 } else { | |
989 for (i = 0; i < x->operand_count(); i++) { | |
990 Value input = x->operand_at(i); | |
991 if (!set_contains(input)) { | |
992 all_non_null = false; | |
993 } | |
994 } | |
995 } | |
996 | |
997 if (all_non_null) { | |
998 // Value is non-null => update Phi | |
999 if (PrintNullCheckElimination) { | |
1000 tty->print_cr("Eliminated Phi %d's null check for phifun because all inputs are non-null", x->id()); | |
1001 } | |
1002 x->set_needs_null_check(false); | |
1003 } else if (set_contains(x)) { | |
1004 set_remove(x); | |
1005 } | |
1006 } | |
1007 | |
1008 | |
1009 void Optimizer::eliminate_null_checks() { | |
1010 ResourceMark rm; | |
1011 | |
1012 NullCheckEliminator nce(this); | |
1013 | |
1014 if (PrintNullCheckElimination) { | |
1015 tty->print_cr("Starting null check elimination for method %s::%s%s", | |
1016 ir()->method()->holder()->name()->as_utf8(), | |
1017 ir()->method()->name()->as_utf8(), | |
1018 ir()->method()->signature()->as_symbol()->as_utf8()); | |
1019 } | |
1020 | |
1021 // Apply to graph | |
1022 nce.iterate(ir()->start()); | |
1023 | |
1024 // walk over the graph looking for exception | |
1025 // handlers and iterate over them as well | |
1026 int nblocks = BlockBegin::number_of_blocks(); | |
1027 BlockList blocks(nblocks); | |
1028 boolArray visited_block(nblocks, false); | |
1029 | |
1030 blocks.push(ir()->start()); | |
1031 visited_block[ir()->start()->block_id()] = true; | |
1032 for (int i = 0; i < blocks.length(); i++) { | |
1033 BlockBegin* b = blocks[i]; | |
1034 // exception handlers need to be treated as additional roots | |
1035 for (int e = b->number_of_exception_handlers(); e-- > 0; ) { | |
1036 BlockBegin* excp = b->exception_handler_at(e); | |
1037 int id = excp->block_id(); | |
1038 if (!visited_block[id]) { | |
1039 blocks.push(excp); | |
1040 visited_block[id] = true; | |
1041 nce.iterate(excp); | |
1042 } | |
1043 } | |
1044 // traverse successors | |
1045 BlockEnd *end = b->end(); | |
1046 for (int s = end->number_of_sux(); s-- > 0; ) { | |
1047 BlockBegin* next = end->sux_at(s); | |
1048 int id = next->block_id(); | |
1049 if (!visited_block[id]) { | |
1050 blocks.push(next); | |
1051 visited_block[id] = true; | |
1052 } | |
1053 } | |
1054 } | |
1055 | |
1056 | |
1057 if (PrintNullCheckElimination) { | |
1058 tty->print_cr("Done with null check elimination for method %s::%s%s", | |
1059 ir()->method()->holder()->name()->as_utf8(), | |
1060 ir()->method()->name()->as_utf8(), | |
1061 ir()->method()->signature()->as_symbol()->as_utf8()); | |
1062 } | |
1063 } |