Mercurial > hg > truffle
comparison src/share/vm/c1/c1_Optimizer.cpp @ 0:a61af66fc99e jdk7-b24
Initial load
author | duke |
---|---|
date | Sat, 01 Dec 2007 00:00:00 +0000 |
parents | |
children | 80206b8a9128 |
comparison
equal
deleted
inserted
replaced
-1:000000000000 | 0:a61af66fc99e |
---|---|
1 /* | |
2 * Copyright 1999-2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
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 tsux = if_->fsux(); | |
331 fsux = if_->tsux(); | |
332 } | |
333 | |
334 BlockBegin* tblock = tval->compare(cond, con, tsux, fsux); | |
335 BlockBegin* fblock = fval->compare(cond, con, tsux, fsux); | |
336 if (tblock != fblock && !if_->is_safepoint()) { | |
337 If* newif = new If(ifop->x(), ifop->cond(), false, ifop->y(), | |
338 tblock, fblock, if_->state_before(), if_->is_safepoint()); | |
339 newif->set_state(if_->state()->copy()); | |
340 | |
341 assert(prev->next() == if_, "must be guaranteed by above search"); | |
342 prev->set_next(newif, if_->bci()); | |
343 block->set_end(newif); | |
344 | |
345 _merge_count++; | |
346 if (PrintBlockElimination) { | |
347 tty->print_cr("%d. replaced If and IfOp at end of B%d with single If", _merge_count, block->block_id()); | |
348 } | |
349 | |
350 _hir->verify(); | |
351 } | |
352 } | |
353 } | |
354 } | |
355 } | |
356 | |
357 return true; | |
358 } | |
359 } | |
360 return false; | |
361 } | |
362 | |
363 virtual void block_do(BlockBegin* block) { | |
364 _hir->verify(); | |
365 // repeat since the same block may merge again | |
366 while (try_merge(block)) { | |
367 _hir->verify(); | |
368 } | |
369 } | |
370 }; | |
371 | |
372 | |
373 void Optimizer::eliminate_blocks() { | |
374 // merge blocks if possible | |
375 BlockMerger bm(ir()); | |
376 } | |
377 | |
378 | |
379 class NullCheckEliminator; | |
380 class NullCheckVisitor: public InstructionVisitor { | |
381 private: | |
382 NullCheckEliminator* _nce; | |
383 NullCheckEliminator* nce() { return _nce; } | |
384 | |
385 public: | |
386 NullCheckVisitor() {} | |
387 | |
388 void set_eliminator(NullCheckEliminator* nce) { _nce = nce; } | |
389 | |
390 void do_Phi (Phi* x); | |
391 void do_Local (Local* x); | |
392 void do_Constant (Constant* x); | |
393 void do_LoadField (LoadField* x); | |
394 void do_StoreField (StoreField* x); | |
395 void do_ArrayLength (ArrayLength* x); | |
396 void do_LoadIndexed (LoadIndexed* x); | |
397 void do_StoreIndexed (StoreIndexed* x); | |
398 void do_NegateOp (NegateOp* x); | |
399 void do_ArithmeticOp (ArithmeticOp* x); | |
400 void do_ShiftOp (ShiftOp* x); | |
401 void do_LogicOp (LogicOp* x); | |
402 void do_CompareOp (CompareOp* x); | |
403 void do_IfOp (IfOp* x); | |
404 void do_Convert (Convert* x); | |
405 void do_NullCheck (NullCheck* x); | |
406 void do_Invoke (Invoke* x); | |
407 void do_NewInstance (NewInstance* x); | |
408 void do_NewTypeArray (NewTypeArray* x); | |
409 void do_NewObjectArray (NewObjectArray* x); | |
410 void do_NewMultiArray (NewMultiArray* x); | |
411 void do_CheckCast (CheckCast* x); | |
412 void do_InstanceOf (InstanceOf* x); | |
413 void do_MonitorEnter (MonitorEnter* x); | |
414 void do_MonitorExit (MonitorExit* x); | |
415 void do_Intrinsic (Intrinsic* x); | |
416 void do_BlockBegin (BlockBegin* x); | |
417 void do_Goto (Goto* x); | |
418 void do_If (If* x); | |
419 void do_IfInstanceOf (IfInstanceOf* x); | |
420 void do_TableSwitch (TableSwitch* x); | |
421 void do_LookupSwitch (LookupSwitch* x); | |
422 void do_Return (Return* x); | |
423 void do_Throw (Throw* x); | |
424 void do_Base (Base* x); | |
425 void do_OsrEntry (OsrEntry* x); | |
426 void do_ExceptionObject(ExceptionObject* x); | |
427 void do_RoundFP (RoundFP* x); | |
428 void do_UnsafeGetRaw (UnsafeGetRaw* x); | |
429 void do_UnsafePutRaw (UnsafePutRaw* x); | |
430 void do_UnsafeGetObject(UnsafeGetObject* x); | |
431 void do_UnsafePutObject(UnsafePutObject* x); | |
432 void do_UnsafePrefetchRead (UnsafePrefetchRead* x); | |
433 void do_UnsafePrefetchWrite(UnsafePrefetchWrite* x); | |
434 void do_ProfileCall (ProfileCall* x); | |
435 void do_ProfileCounter (ProfileCounter* x); | |
436 }; | |
437 | |
438 | |
439 // Because of a static contained within (for the purpose of iteration | |
440 // over instructions), it is only valid to have one of these active at | |
441 // a time | |
442 class NullCheckEliminator { | |
443 private: | |
444 static NullCheckEliminator* _static_nce; | |
445 static void do_value(Value* vp); | |
446 | |
447 Optimizer* _opt; | |
448 | |
449 ValueSet* _visitable_instructions; // Visit each instruction only once per basic block | |
450 BlockList* _work_list; // Basic blocks to visit | |
451 | |
452 bool visitable(Value x) { | |
453 assert(_visitable_instructions != NULL, "check"); | |
454 return _visitable_instructions->contains(x); | |
455 } | |
456 void mark_visited(Value x) { | |
457 assert(_visitable_instructions != NULL, "check"); | |
458 _visitable_instructions->remove(x); | |
459 } | |
460 void mark_visitable(Value x) { | |
461 assert(_visitable_instructions != NULL, "check"); | |
462 _visitable_instructions->put(x); | |
463 } | |
464 void clear_visitable_state() { | |
465 assert(_visitable_instructions != NULL, "check"); | |
466 _visitable_instructions->clear(); | |
467 } | |
468 | |
469 ValueSet* _set; // current state, propagated to subsequent BlockBegins | |
470 ValueSetList _block_states; // BlockBegin null-check states for all processed blocks | |
471 NullCheckVisitor _visitor; | |
472 NullCheck* _last_explicit_null_check; | |
473 | |
474 bool set_contains(Value x) { assert(_set != NULL, "check"); return _set->contains(x); } | |
475 void set_put (Value x) { assert(_set != NULL, "check"); _set->put(x); } | |
476 void set_remove (Value x) { assert(_set != NULL, "check"); _set->remove(x); } | |
477 | |
478 BlockList* work_list() { return _work_list; } | |
479 | |
480 void iterate_all(); | |
481 void iterate_one(BlockBegin* block); | |
482 | |
483 ValueSet* state() { return _set; } | |
484 void set_state_from (ValueSet* state) { _set->set_from(state); } | |
485 ValueSet* state_for (BlockBegin* block) { return _block_states[block->block_id()]; } | |
486 void set_state_for (BlockBegin* block, ValueSet* stack) { _block_states[block->block_id()] = stack; } | |
487 // Returns true if caused a change in the block's state. | |
488 bool merge_state_for(BlockBegin* block, | |
489 ValueSet* incoming_state); | |
490 | |
491 public: | |
492 // constructor | |
493 NullCheckEliminator(Optimizer* opt) | |
494 : _opt(opt) | |
495 , _set(new ValueSet()) | |
496 , _last_explicit_null_check(NULL) | |
497 , _block_states(BlockBegin::number_of_blocks(), NULL) | |
498 , _work_list(new BlockList()) { | |
499 _visitable_instructions = new ValueSet(); | |
500 _visitor.set_eliminator(this); | |
501 } | |
502 | |
503 Optimizer* opt() { return _opt; } | |
504 IR* ir () { return opt()->ir(); } | |
505 | |
506 // Process a graph | |
507 void iterate(BlockBegin* root); | |
508 | |
509 // In some situations (like NullCheck(x); getfield(x)) the debug | |
510 // information from the explicit NullCheck can be used to populate | |
511 // the getfield, even if the two instructions are in different | |
512 // scopes; this allows implicit null checks to be used but the | |
513 // correct exception information to be generated. We must clear the | |
514 // last-traversed NullCheck when we reach a potentially-exception- | |
515 // throwing instruction, as well as in some other cases. | |
516 void set_last_explicit_null_check(NullCheck* check) { _last_explicit_null_check = check; } | |
517 NullCheck* last_explicit_null_check() { return _last_explicit_null_check; } | |
518 Value last_explicit_null_check_obj() { return (_last_explicit_null_check | |
519 ? _last_explicit_null_check->obj() | |
520 : NULL); } | |
521 NullCheck* consume_last_explicit_null_check() { | |
522 _last_explicit_null_check->unpin(Instruction::PinExplicitNullCheck); | |
523 _last_explicit_null_check->set_can_trap(false); | |
524 return _last_explicit_null_check; | |
525 } | |
526 void clear_last_explicit_null_check() { _last_explicit_null_check = NULL; } | |
527 | |
528 // Handlers for relevant instructions | |
529 // (separated out from NullCheckVisitor for clarity) | |
530 | |
531 // The basic contract is that these must leave the instruction in | |
532 // the desired state; must not assume anything about the state of | |
533 // the instruction. We make multiple passes over some basic blocks | |
534 // and the last pass is the only one whose result is valid. | |
535 void handle_AccessField (AccessField* x); | |
536 void handle_ArrayLength (ArrayLength* x); | |
537 void handle_LoadIndexed (LoadIndexed* x); | |
538 void handle_StoreIndexed (StoreIndexed* x); | |
539 void handle_NullCheck (NullCheck* x); | |
540 void handle_Invoke (Invoke* x); | |
541 void handle_NewInstance (NewInstance* x); | |
542 void handle_NewArray (NewArray* x); | |
543 void handle_AccessMonitor (AccessMonitor* x); | |
544 void handle_Intrinsic (Intrinsic* x); | |
545 void handle_ExceptionObject (ExceptionObject* x); | |
546 void handle_Phi (Phi* x); | |
547 }; | |
548 | |
549 | |
550 // NEEDS_CLEANUP | |
551 // There may be other instructions which need to clear the last | |
552 // explicit null check. Anything across which we can not hoist the | |
553 // debug information for a NullCheck instruction must clear it. It | |
554 // might be safer to pattern match "NullCheck ; {AccessField, | |
555 // ArrayLength, LoadIndexed}" but it is more easily structured this way. | |
556 // Should test to see performance hit of clearing it for all handlers | |
557 // with empty bodies below. If it is negligible then we should leave | |
558 // that in for safety, otherwise should think more about it. | |
559 void NullCheckVisitor::do_Phi (Phi* x) { nce()->handle_Phi(x); } | |
560 void NullCheckVisitor::do_Local (Local* x) {} | |
561 void NullCheckVisitor::do_Constant (Constant* x) { /* FIXME: handle object constants */ } | |
562 void NullCheckVisitor::do_LoadField (LoadField* x) { nce()->handle_AccessField(x); } | |
563 void NullCheckVisitor::do_StoreField (StoreField* x) { nce()->handle_AccessField(x); } | |
564 void NullCheckVisitor::do_ArrayLength (ArrayLength* x) { nce()->handle_ArrayLength(x); } | |
565 void NullCheckVisitor::do_LoadIndexed (LoadIndexed* x) { nce()->handle_LoadIndexed(x); } | |
566 void NullCheckVisitor::do_StoreIndexed (StoreIndexed* x) { nce()->handle_StoreIndexed(x); } | |
567 void NullCheckVisitor::do_NegateOp (NegateOp* x) {} | |
568 void NullCheckVisitor::do_ArithmeticOp (ArithmeticOp* x) { if (x->can_trap()) nce()->clear_last_explicit_null_check(); } | |
569 void NullCheckVisitor::do_ShiftOp (ShiftOp* x) {} | |
570 void NullCheckVisitor::do_LogicOp (LogicOp* x) {} | |
571 void NullCheckVisitor::do_CompareOp (CompareOp* x) {} | |
572 void NullCheckVisitor::do_IfOp (IfOp* x) {} | |
573 void NullCheckVisitor::do_Convert (Convert* x) {} | |
574 void NullCheckVisitor::do_NullCheck (NullCheck* x) { nce()->handle_NullCheck(x); } | |
575 void NullCheckVisitor::do_Invoke (Invoke* x) { nce()->handle_Invoke(x); } | |
576 void NullCheckVisitor::do_NewInstance (NewInstance* x) { nce()->handle_NewInstance(x); } | |
577 void NullCheckVisitor::do_NewTypeArray (NewTypeArray* x) { nce()->handle_NewArray(x); } | |
578 void NullCheckVisitor::do_NewObjectArray (NewObjectArray* x) { nce()->handle_NewArray(x); } | |
579 void NullCheckVisitor::do_NewMultiArray (NewMultiArray* x) { nce()->handle_NewArray(x); } | |
580 void NullCheckVisitor::do_CheckCast (CheckCast* x) {} | |
581 void NullCheckVisitor::do_InstanceOf (InstanceOf* x) {} | |
582 void NullCheckVisitor::do_MonitorEnter (MonitorEnter* x) { nce()->handle_AccessMonitor(x); } | |
583 void NullCheckVisitor::do_MonitorExit (MonitorExit* x) { nce()->handle_AccessMonitor(x); } | |
584 void NullCheckVisitor::do_Intrinsic (Intrinsic* x) { nce()->clear_last_explicit_null_check(); } | |
585 void NullCheckVisitor::do_BlockBegin (BlockBegin* x) {} | |
586 void NullCheckVisitor::do_Goto (Goto* x) {} | |
587 void NullCheckVisitor::do_If (If* x) {} | |
588 void NullCheckVisitor::do_IfInstanceOf (IfInstanceOf* x) {} | |
589 void NullCheckVisitor::do_TableSwitch (TableSwitch* x) {} | |
590 void NullCheckVisitor::do_LookupSwitch (LookupSwitch* x) {} | |
591 void NullCheckVisitor::do_Return (Return* x) {} | |
592 void NullCheckVisitor::do_Throw (Throw* x) { nce()->clear_last_explicit_null_check(); } | |
593 void NullCheckVisitor::do_Base (Base* x) {} | |
594 void NullCheckVisitor::do_OsrEntry (OsrEntry* x) {} | |
595 void NullCheckVisitor::do_ExceptionObject(ExceptionObject* x) { nce()->handle_ExceptionObject(x); } | |
596 void NullCheckVisitor::do_RoundFP (RoundFP* x) {} | |
597 void NullCheckVisitor::do_UnsafeGetRaw (UnsafeGetRaw* x) {} | |
598 void NullCheckVisitor::do_UnsafePutRaw (UnsafePutRaw* x) {} | |
599 void NullCheckVisitor::do_UnsafeGetObject(UnsafeGetObject* x) {} | |
600 void NullCheckVisitor::do_UnsafePutObject(UnsafePutObject* x) {} | |
601 void NullCheckVisitor::do_UnsafePrefetchRead (UnsafePrefetchRead* x) {} | |
602 void NullCheckVisitor::do_UnsafePrefetchWrite(UnsafePrefetchWrite* x) {} | |
603 void NullCheckVisitor::do_ProfileCall (ProfileCall* x) { nce()->clear_last_explicit_null_check(); } | |
604 void NullCheckVisitor::do_ProfileCounter (ProfileCounter* x) {} | |
605 | |
606 | |
607 NullCheckEliminator* NullCheckEliminator::_static_nce = NULL; | |
608 | |
609 | |
610 void NullCheckEliminator::do_value(Value* p) { | |
611 assert(*p != NULL, "should not find NULL instructions"); | |
612 if (_static_nce->visitable(*p)) { | |
613 _static_nce->mark_visited(*p); | |
614 (*p)->visit(&_static_nce->_visitor); | |
615 } | |
616 } | |
617 | |
618 bool NullCheckEliminator::merge_state_for(BlockBegin* block, ValueSet* incoming_state) { | |
619 ValueSet* state = state_for(block); | |
620 if (state == NULL) { | |
621 state = incoming_state->copy(); | |
622 set_state_for(block, state); | |
623 return true; | |
624 } else { | |
625 bool changed = state->set_intersect(incoming_state); | |
626 if (PrintNullCheckElimination && changed) { | |
627 tty->print_cr("Block %d's null check state changed", block->block_id()); | |
628 } | |
629 return changed; | |
630 } | |
631 } | |
632 | |
633 | |
634 void NullCheckEliminator::iterate_all() { | |
635 while (work_list()->length() > 0) { | |
636 iterate_one(work_list()->pop()); | |
637 } | |
638 } | |
639 | |
640 | |
641 void NullCheckEliminator::iterate_one(BlockBegin* block) { | |
642 _static_nce = this; | |
643 clear_visitable_state(); | |
644 // clear out an old explicit null checks | |
645 set_last_explicit_null_check(NULL); | |
646 | |
647 if (PrintNullCheckElimination) { | |
648 tty->print_cr(" ...iterating block %d in null check elimination for %s::%s%s", | |
649 block->block_id(), | |
650 ir()->method()->holder()->name()->as_utf8(), | |
651 ir()->method()->name()->as_utf8(), | |
652 ir()->method()->signature()->as_symbol()->as_utf8()); | |
653 } | |
654 | |
655 // Create new state if none present (only happens at root) | |
656 if (state_for(block) == NULL) { | |
657 ValueSet* tmp_state = new ValueSet(); | |
658 set_state_for(block, tmp_state); | |
659 // Initial state is that local 0 (receiver) is non-null for | |
660 // non-static methods | |
661 ValueStack* stack = block->state(); | |
662 IRScope* scope = stack->scope(); | |
663 ciMethod* method = scope->method(); | |
664 if (!method->is_static()) { | |
665 Local* local0 = stack->local_at(0)->as_Local(); | |
666 assert(local0 != NULL, "must be"); | |
667 assert(local0->type() == objectType, "invalid type of receiver"); | |
668 | |
669 if (local0 != NULL) { | |
670 // Local 0 is used in this scope | |
671 tmp_state->put(local0); | |
672 if (PrintNullCheckElimination) { | |
673 tty->print_cr("Local 0 (value %d) proven non-null upon entry", local0->id()); | |
674 } | |
675 } | |
676 } | |
677 } | |
678 | |
679 // Must copy block's state to avoid mutating it during iteration | |
680 // through the block -- otherwise "not-null" states can accidentally | |
681 // propagate "up" through the block during processing of backward | |
682 // branches and algorithm is incorrect (and does not converge) | |
683 set_state_from(state_for(block)); | |
684 | |
685 // allow visiting of Phis belonging to this block | |
686 for_each_phi_fun(block, phi, | |
687 mark_visitable(phi); | |
688 ); | |
689 | |
690 BlockEnd* e = block->end(); | |
691 assert(e != NULL, "incomplete graph"); | |
692 int i; | |
693 | |
694 // Propagate the state before this block into the exception | |
695 // handlers. They aren't true successors since we aren't guaranteed | |
696 // to execute the whole block before executing them. Also putting | |
697 // them on first seems to help reduce the amount of iteration to | |
698 // reach a fixed point. | |
699 for (i = 0; i < block->number_of_exception_handlers(); i++) { | |
700 BlockBegin* next = block->exception_handler_at(i); | |
701 if (merge_state_for(next, state())) { | |
702 if (!work_list()->contains(next)) { | |
703 work_list()->push(next); | |
704 } | |
705 } | |
706 } | |
707 | |
708 // Iterate through block, updating state. | |
709 for (Instruction* instr = block; instr != NULL; instr = instr->next()) { | |
710 // Mark instructions in this block as visitable as they are seen | |
711 // in the instruction list. This keeps the iteration from | |
712 // visiting instructions which are references in other blocks or | |
713 // visiting instructions more than once. | |
714 mark_visitable(instr); | |
715 if (instr->is_root() || instr->can_trap() || (instr->as_NullCheck() != NULL)) { | |
716 mark_visited(instr); | |
717 instr->input_values_do(&NullCheckEliminator::do_value); | |
718 instr->visit(&_visitor); | |
719 } | |
720 } | |
721 | |
722 // Propagate state to successors if necessary | |
723 for (i = 0; i < e->number_of_sux(); i++) { | |
724 BlockBegin* next = e->sux_at(i); | |
725 if (merge_state_for(next, state())) { | |
726 if (!work_list()->contains(next)) { | |
727 work_list()->push(next); | |
728 } | |
729 } | |
730 } | |
731 } | |
732 | |
733 | |
734 void NullCheckEliminator::iterate(BlockBegin* block) { | |
735 work_list()->push(block); | |
736 iterate_all(); | |
737 } | |
738 | |
739 void NullCheckEliminator::handle_AccessField(AccessField* x) { | |
740 if (x->is_static()) { | |
741 if (x->as_LoadField() != NULL) { | |
742 // If the field is a non-null static final object field (as is | |
743 // often the case for sun.misc.Unsafe), put this LoadField into | |
744 // the non-null map | |
745 ciField* field = x->field(); | |
746 if (field->is_constant()) { | |
747 ciConstant field_val = field->constant_value(); | |
748 BasicType field_type = field_val.basic_type(); | |
749 if (field_type == T_OBJECT || field_type == T_ARRAY) { | |
750 ciObject* obj_val = field_val.as_object(); | |
751 if (!obj_val->is_null_object()) { | |
752 if (PrintNullCheckElimination) { | |
753 tty->print_cr("AccessField %d proven non-null by static final non-null oop check", | |
754 x->id()); | |
755 } | |
756 set_put(x); | |
757 } | |
758 } | |
759 } | |
760 } | |
761 // Be conservative | |
762 clear_last_explicit_null_check(); | |
763 return; | |
764 } | |
765 | |
766 Value obj = x->obj(); | |
767 if (set_contains(obj)) { | |
768 // Value is non-null => update AccessField | |
769 if (last_explicit_null_check_obj() == obj && !x->needs_patching()) { | |
770 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
771 x->set_needs_null_check(true); | |
772 if (PrintNullCheckElimination) { | |
773 tty->print_cr("Folded NullCheck %d into AccessField %d's null check for value %d", | |
774 x->explicit_null_check()->id(), x->id(), obj->id()); | |
775 } | |
776 } else { | |
777 x->set_explicit_null_check(NULL); | |
778 x->set_needs_null_check(false); | |
779 if (PrintNullCheckElimination) { | |
780 tty->print_cr("Eliminated AccessField %d's null check for value %d", x->id(), obj->id()); | |
781 } | |
782 } | |
783 } else { | |
784 set_put(obj); | |
785 if (PrintNullCheckElimination) { | |
786 tty->print_cr("AccessField %d of value %d proves value to be non-null", x->id(), obj->id()); | |
787 } | |
788 // Ensure previous passes do not cause wrong state | |
789 x->set_needs_null_check(true); | |
790 x->set_explicit_null_check(NULL); | |
791 } | |
792 clear_last_explicit_null_check(); | |
793 } | |
794 | |
795 | |
796 void NullCheckEliminator::handle_ArrayLength(ArrayLength* x) { | |
797 Value array = x->array(); | |
798 if (set_contains(array)) { | |
799 // Value is non-null => update AccessArray | |
800 if (last_explicit_null_check_obj() == array) { | |
801 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
802 x->set_needs_null_check(true); | |
803 if (PrintNullCheckElimination) { | |
804 tty->print_cr("Folded NullCheck %d into ArrayLength %d's null check for value %d", | |
805 x->explicit_null_check()->id(), x->id(), array->id()); | |
806 } | |
807 } else { | |
808 x->set_explicit_null_check(NULL); | |
809 x->set_needs_null_check(false); | |
810 if (PrintNullCheckElimination) { | |
811 tty->print_cr("Eliminated ArrayLength %d's null check for value %d", x->id(), array->id()); | |
812 } | |
813 } | |
814 } else { | |
815 set_put(array); | |
816 if (PrintNullCheckElimination) { | |
817 tty->print_cr("ArrayLength %d of value %d proves value to be non-null", x->id(), array->id()); | |
818 } | |
819 // Ensure previous passes do not cause wrong state | |
820 x->set_needs_null_check(true); | |
821 x->set_explicit_null_check(NULL); | |
822 } | |
823 clear_last_explicit_null_check(); | |
824 } | |
825 | |
826 | |
827 void NullCheckEliminator::handle_LoadIndexed(LoadIndexed* x) { | |
828 Value array = x->array(); | |
829 if (set_contains(array)) { | |
830 // Value is non-null => update AccessArray | |
831 if (last_explicit_null_check_obj() == array) { | |
832 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
833 x->set_needs_null_check(true); | |
834 if (PrintNullCheckElimination) { | |
835 tty->print_cr("Folded NullCheck %d into LoadIndexed %d's null check for value %d", | |
836 x->explicit_null_check()->id(), x->id(), array->id()); | |
837 } | |
838 } else { | |
839 x->set_explicit_null_check(NULL); | |
840 x->set_needs_null_check(false); | |
841 if (PrintNullCheckElimination) { | |
842 tty->print_cr("Eliminated LoadIndexed %d's null check for value %d", x->id(), array->id()); | |
843 } | |
844 } | |
845 } else { | |
846 set_put(array); | |
847 if (PrintNullCheckElimination) { | |
848 tty->print_cr("LoadIndexed %d of value %d proves value to be non-null", x->id(), array->id()); | |
849 } | |
850 // Ensure previous passes do not cause wrong state | |
851 x->set_needs_null_check(true); | |
852 x->set_explicit_null_check(NULL); | |
853 } | |
854 clear_last_explicit_null_check(); | |
855 } | |
856 | |
857 | |
858 void NullCheckEliminator::handle_StoreIndexed(StoreIndexed* x) { | |
859 Value array = x->array(); | |
860 if (set_contains(array)) { | |
861 // Value is non-null => update AccessArray | |
862 if (PrintNullCheckElimination) { | |
863 tty->print_cr("Eliminated StoreIndexed %d's null check for value %d", x->id(), array->id()); | |
864 } | |
865 x->set_needs_null_check(false); | |
866 } else { | |
867 set_put(array); | |
868 if (PrintNullCheckElimination) { | |
869 tty->print_cr("StoreIndexed %d of value %d proves value to be non-null", x->id(), array->id()); | |
870 } | |
871 // Ensure previous passes do not cause wrong state | |
872 x->set_needs_null_check(true); | |
873 } | |
874 clear_last_explicit_null_check(); | |
875 } | |
876 | |
877 | |
878 void NullCheckEliminator::handle_NullCheck(NullCheck* x) { | |
879 Value obj = x->obj(); | |
880 if (set_contains(obj)) { | |
881 // Already proven to be non-null => this NullCheck is useless | |
882 if (PrintNullCheckElimination) { | |
883 tty->print_cr("Eliminated NullCheck %d for value %d", x->id(), obj->id()); | |
884 } | |
885 // Don't unpin since that may shrink obj's live range and make it unavailable for debug info. | |
886 // The code generator won't emit LIR for a NullCheck that cannot trap. | |
887 x->set_can_trap(false); | |
888 } else { | |
889 // May be null => add to map and set last explicit NullCheck | |
890 x->set_can_trap(true); | |
891 // make sure it's pinned if it can trap | |
892 x->pin(Instruction::PinExplicitNullCheck); | |
893 set_put(obj); | |
894 set_last_explicit_null_check(x); | |
895 if (PrintNullCheckElimination) { | |
896 tty->print_cr("NullCheck %d of value %d proves value to be non-null", x->id(), obj->id()); | |
897 } | |
898 } | |
899 } | |
900 | |
901 | |
902 void NullCheckEliminator::handle_Invoke(Invoke* x) { | |
903 if (!x->has_receiver()) { | |
904 // Be conservative | |
905 clear_last_explicit_null_check(); | |
906 return; | |
907 } | |
908 | |
909 Value recv = x->receiver(); | |
910 if (!set_contains(recv)) { | |
911 set_put(recv); | |
912 if (PrintNullCheckElimination) { | |
913 tty->print_cr("Invoke %d of value %d proves value to be non-null", x->id(), recv->id()); | |
914 } | |
915 } | |
916 clear_last_explicit_null_check(); | |
917 } | |
918 | |
919 | |
920 void NullCheckEliminator::handle_NewInstance(NewInstance* x) { | |
921 set_put(x); | |
922 if (PrintNullCheckElimination) { | |
923 tty->print_cr("NewInstance %d is non-null", x->id()); | |
924 } | |
925 } | |
926 | |
927 | |
928 void NullCheckEliminator::handle_NewArray(NewArray* x) { | |
929 set_put(x); | |
930 if (PrintNullCheckElimination) { | |
931 tty->print_cr("NewArray %d is non-null", x->id()); | |
932 } | |
933 } | |
934 | |
935 | |
936 void NullCheckEliminator::handle_ExceptionObject(ExceptionObject* x) { | |
937 set_put(x); | |
938 if (PrintNullCheckElimination) { | |
939 tty->print_cr("ExceptionObject %d is non-null", x->id()); | |
940 } | |
941 } | |
942 | |
943 | |
944 void NullCheckEliminator::handle_AccessMonitor(AccessMonitor* x) { | |
945 Value obj = x->obj(); | |
946 if (set_contains(obj)) { | |
947 // Value is non-null => update AccessMonitor | |
948 if (PrintNullCheckElimination) { | |
949 tty->print_cr("Eliminated AccessMonitor %d's null check for value %d", x->id(), obj->id()); | |
950 } | |
951 x->set_needs_null_check(false); | |
952 } else { | |
953 set_put(obj); | |
954 if (PrintNullCheckElimination) { | |
955 tty->print_cr("AccessMonitor %d of value %d proves value to be non-null", x->id(), obj->id()); | |
956 } | |
957 // Ensure previous passes do not cause wrong state | |
958 x->set_needs_null_check(true); | |
959 } | |
960 clear_last_explicit_null_check(); | |
961 } | |
962 | |
963 | |
964 void NullCheckEliminator::handle_Intrinsic(Intrinsic* x) { | |
965 if (!x->has_receiver()) { | |
966 // Be conservative | |
967 clear_last_explicit_null_check(); | |
968 return; | |
969 } | |
970 | |
971 Value recv = x->receiver(); | |
972 if (set_contains(recv)) { | |
973 // Value is non-null => update Intrinsic | |
974 if (PrintNullCheckElimination) { | |
975 tty->print_cr("Eliminated Intrinsic %d's null check for value %d", x->id(), recv->id()); | |
976 } | |
977 x->set_needs_null_check(false); | |
978 } else { | |
979 set_put(recv); | |
980 if (PrintNullCheckElimination) { | |
981 tty->print_cr("Intrinsic %d of value %d proves value to be non-null", x->id(), recv->id()); | |
982 } | |
983 // Ensure previous passes do not cause wrong state | |
984 x->set_needs_null_check(true); | |
985 } | |
986 clear_last_explicit_null_check(); | |
987 } | |
988 | |
989 | |
990 void NullCheckEliminator::handle_Phi(Phi* x) { | |
991 int i; | |
992 bool all_non_null = true; | |
993 if (x->is_illegal()) { | |
994 all_non_null = false; | |
995 } else { | |
996 for (i = 0; i < x->operand_count(); i++) { | |
997 Value input = x->operand_at(i); | |
998 if (!set_contains(input)) { | |
999 all_non_null = false; | |
1000 } | |
1001 } | |
1002 } | |
1003 | |
1004 if (all_non_null) { | |
1005 // Value is non-null => update Phi | |
1006 if (PrintNullCheckElimination) { | |
1007 tty->print_cr("Eliminated Phi %d's null check for phifun because all inputs are non-null", x->id()); | |
1008 } | |
1009 x->set_needs_null_check(false); | |
1010 } else if (set_contains(x)) { | |
1011 set_remove(x); | |
1012 } | |
1013 } | |
1014 | |
1015 | |
1016 void Optimizer::eliminate_null_checks() { | |
1017 ResourceMark rm; | |
1018 | |
1019 NullCheckEliminator nce(this); | |
1020 | |
1021 if (PrintNullCheckElimination) { | |
1022 tty->print_cr("Starting null check elimination for method %s::%s%s", | |
1023 ir()->method()->holder()->name()->as_utf8(), | |
1024 ir()->method()->name()->as_utf8(), | |
1025 ir()->method()->signature()->as_symbol()->as_utf8()); | |
1026 } | |
1027 | |
1028 // Apply to graph | |
1029 nce.iterate(ir()->start()); | |
1030 | |
1031 // walk over the graph looking for exception | |
1032 // handlers and iterate over them as well | |
1033 int nblocks = BlockBegin::number_of_blocks(); | |
1034 BlockList blocks(nblocks); | |
1035 boolArray visited_block(nblocks, false); | |
1036 | |
1037 blocks.push(ir()->start()); | |
1038 visited_block[ir()->start()->block_id()] = true; | |
1039 for (int i = 0; i < blocks.length(); i++) { | |
1040 BlockBegin* b = blocks[i]; | |
1041 // exception handlers need to be treated as additional roots | |
1042 for (int e = b->number_of_exception_handlers(); e-- > 0; ) { | |
1043 BlockBegin* excp = b->exception_handler_at(e); | |
1044 int id = excp->block_id(); | |
1045 if (!visited_block[id]) { | |
1046 blocks.push(excp); | |
1047 visited_block[id] = true; | |
1048 nce.iterate(excp); | |
1049 } | |
1050 } | |
1051 // traverse successors | |
1052 BlockEnd *end = b->end(); | |
1053 for (int s = end->number_of_sux(); s-- > 0; ) { | |
1054 BlockBegin* next = end->sux_at(s); | |
1055 int id = next->block_id(); | |
1056 if (!visited_block[id]) { | |
1057 blocks.push(next); | |
1058 visited_block[id] = true; | |
1059 } | |
1060 } | |
1061 } | |
1062 | |
1063 | |
1064 if (PrintNullCheckElimination) { | |
1065 tty->print_cr("Done with null check elimination for method %s::%s%s", | |
1066 ir()->method()->holder()->name()->as_utf8(), | |
1067 ir()->method()->name()->as_utf8(), | |
1068 ir()->method()->signature()->as_symbol()->as_utf8()); | |
1069 } | |
1070 } |