Mercurial > hg > truffle
annotate src/share/vm/c1/c1_Optimizer.cpp @ 3109:3664989976e2
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author | Gilles Duboscq <gilles.duboscq@oracle.com> |
---|---|
date | Fri, 01 Jul 2011 12:57:10 +0200 |
parents | 13bc79b5c9c8 |
children | d4c1fbc3de95 |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1999, 2011, 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "c1/c1_Canonicalizer.hpp" | |
27 #include "c1/c1_Optimizer.hpp" | |
28 #include "c1/c1_ValueMap.hpp" | |
29 #include "c1/c1_ValueSet.hpp" | |
30 #include "c1/c1_ValueStack.hpp" | |
31 #include "utilities/bitMap.inline.hpp" | |
0 | 32 |
33 define_array(ValueSetArray, ValueSet*); | |
34 define_stack(ValueSetList, ValueSetArray); | |
35 | |
36 | |
37 Optimizer::Optimizer(IR* ir) { | |
38 assert(ir->is_valid(), "IR must be valid"); | |
39 _ir = ir; | |
40 } | |
41 | |
42 class CE_Eliminator: public BlockClosure { | |
43 private: | |
44 IR* _hir; | |
45 int _cee_count; // the number of CEs successfully eliminated | |
1899 | 46 int _ifop_count; // the number of IfOps successfully simplified |
0 | 47 int _has_substitution; |
48 | |
49 public: | |
1899 | 50 CE_Eliminator(IR* hir) : _cee_count(0), _ifop_count(0), _hir(hir) { |
0 | 51 _has_substitution = false; |
52 _hir->iterate_preorder(this); | |
53 if (_has_substitution) { | |
1899 | 54 // substituted some ifops/phis, so resolve the substitution |
0 | 55 SubstitutionResolver sr(_hir); |
56 } | |
57 } | |
58 int cee_count() const { return _cee_count; } | |
1899 | 59 int ifop_count() const { return _ifop_count; } |
0 | 60 |
61 void adjust_exception_edges(BlockBegin* block, BlockBegin* sux) { | |
62 int e = sux->number_of_exception_handlers(); | |
63 for (int i = 0; i < e; i++) { | |
64 BlockBegin* xhandler = sux->exception_handler_at(i); | |
65 block->add_exception_handler(xhandler); | |
66 | |
67 assert(xhandler->is_predecessor(sux), "missing predecessor"); | |
68 if (sux->number_of_preds() == 0) { | |
69 // sux is disconnected from graph so disconnect from exception handlers | |
70 xhandler->remove_predecessor(sux); | |
71 } | |
72 if (!xhandler->is_predecessor(block)) { | |
73 xhandler->add_predecessor(block); | |
74 } | |
75 } | |
76 } | |
77 | |
1899 | 78 virtual void block_do(BlockBegin* block); |
79 | |
80 private: | |
81 Value make_ifop(Value x, Instruction::Condition cond, Value y, Value tval, Value fval); | |
82 }; | |
0 | 83 |
1899 | 84 void CE_Eliminator::block_do(BlockBegin* block) { |
85 // 1) find conditional expression | |
86 // check if block ends with an If | |
87 If* if_ = block->end()->as_If(); | |
88 if (if_ == NULL) return; | |
0 | 89 |
1899 | 90 // check if If works on int or object types |
91 // (we cannot handle If's working on long, float or doubles yet, | |
92 // since IfOp doesn't support them - these If's show up if cmp | |
93 // operations followed by If's are eliminated) | |
94 ValueType* if_type = if_->x()->type(); | |
95 if (!if_type->is_int() && !if_type->is_object()) return; | |
0 | 96 |
1899 | 97 BlockBegin* t_block = if_->tsux(); |
98 BlockBegin* f_block = if_->fsux(); | |
99 Instruction* t_cur = t_block->next(); | |
100 Instruction* f_cur = f_block->next(); | |
0 | 101 |
1899 | 102 // one Constant may be present between BlockBegin and BlockEnd |
103 Value t_const = NULL; | |
104 Value f_const = NULL; | |
105 if (t_cur->as_Constant() != NULL && !t_cur->can_trap()) { | |
106 t_const = t_cur; | |
107 t_cur = t_cur->next(); | |
108 } | |
109 if (f_cur->as_Constant() != NULL && !f_cur->can_trap()) { | |
110 f_const = f_cur; | |
111 f_cur = f_cur->next(); | |
112 } | |
0 | 113 |
1899 | 114 // check if both branches end with a goto |
115 Goto* t_goto = t_cur->as_Goto(); | |
116 if (t_goto == NULL) return; | |
117 Goto* f_goto = f_cur->as_Goto(); | |
118 if (f_goto == NULL) return; | |
0 | 119 |
1899 | 120 // check if both gotos merge into the same block |
121 BlockBegin* sux = t_goto->default_sux(); | |
122 if (sux != f_goto->default_sux()) return; | |
0 | 123 |
1899 | 124 // check if at least one word was pushed on sux_state |
125 ValueStack* sux_state = sux->state(); | |
126 if (sux_state->stack_size() <= if_->state()->stack_size()) return; | |
0 | 127 |
1899 | 128 // check if phi function is present at end of successor stack and that |
129 // only this phi was pushed on the stack | |
130 Value sux_phi = sux_state->stack_at(if_->state()->stack_size()); | |
131 if (sux_phi == NULL || sux_phi->as_Phi() == NULL || sux_phi->as_Phi()->block() != sux) return; | |
132 if (sux_phi->type()->size() != sux_state->stack_size() - if_->state()->stack_size()) return; | |
0 | 133 |
1899 | 134 // get the values that were pushed in the true- and false-branch |
135 Value t_value = t_goto->state()->stack_at(if_->state()->stack_size()); | |
136 Value f_value = f_goto->state()->stack_at(if_->state()->stack_size()); | |
137 | |
138 // backend does not support floats | |
139 assert(t_value->type()->base() == f_value->type()->base(), "incompatible types"); | |
140 if (t_value->type()->is_float_kind()) return; | |
0 | 141 |
1899 | 142 // check that successor has no other phi functions but sux_phi |
143 // this can happen when t_block or f_block contained additonal stores to local variables | |
144 // that are no longer represented by explicit instructions | |
145 for_each_phi_fun(sux, phi, | |
146 if (phi != sux_phi) return; | |
147 ); | |
148 // true and false blocks can't have phis | |
149 for_each_phi_fun(t_block, phi, return; ); | |
150 for_each_phi_fun(f_block, phi, return; ); | |
151 | |
152 // 2) substitute conditional expression | |
153 // with an IfOp followed by a Goto | |
154 // cut if_ away and get node before | |
155 Instruction* cur_end = if_->prev(block); | |
0 | 156 |
1899 | 157 // append constants of true- and false-block if necessary |
158 // clone constants because original block must not be destroyed | |
159 assert((t_value != f_const && f_value != t_const) || t_const == f_const, "mismatch"); | |
160 if (t_value == t_const) { | |
161 t_value = new Constant(t_const->type()); | |
162 NOT_PRODUCT(t_value->set_printable_bci(if_->printable_bci())); | |
163 cur_end = cur_end->set_next(t_value); | |
164 } | |
165 if (f_value == f_const) { | |
166 f_value = new Constant(f_const->type()); | |
167 NOT_PRODUCT(f_value->set_printable_bci(if_->printable_bci())); | |
168 cur_end = cur_end->set_next(f_value); | |
169 } | |
0 | 170 |
1899 | 171 Value result = make_ifop(if_->x(), if_->cond(), if_->y(), t_value, f_value); |
172 assert(result != NULL, "make_ifop must return a non-null instruction"); | |
173 if (!result->is_linked() && result->can_be_linked()) { | |
1819 | 174 NOT_PRODUCT(result->set_printable_bci(if_->printable_bci())); |
175 cur_end = cur_end->set_next(result); | |
1899 | 176 } |
0 | 177 |
1899 | 178 // append Goto to successor |
179 ValueStack* state_before = if_->is_safepoint() ? if_->state_before() : NULL; | |
180 Goto* goto_ = new Goto(sux, state_before, if_->is_safepoint() || t_goto->is_safepoint() || f_goto->is_safepoint()); | |
181 | |
182 // prepare state for Goto | |
183 ValueStack* goto_state = if_->state(); | |
184 while (sux_state->scope() != goto_state->scope()) { | |
185 goto_state = goto_state->caller_state(); | |
186 assert(goto_state != NULL, "states do not match up"); | |
187 } | |
188 goto_state = goto_state->copy(ValueStack::StateAfter, goto_state->bci()); | |
189 goto_state->push(result->type(), result); | |
190 assert(goto_state->is_same(sux_state), "states must match now"); | |
191 goto_->set_state(goto_state); | |
192 | |
193 cur_end = cur_end->set_next(goto_, goto_state->bci()); | |
194 | |
195 // Adjust control flow graph | |
196 BlockBegin::disconnect_edge(block, t_block); | |
197 BlockBegin::disconnect_edge(block, f_block); | |
198 if (t_block->number_of_preds() == 0) { | |
199 BlockBegin::disconnect_edge(t_block, sux); | |
200 } | |
201 adjust_exception_edges(block, t_block); | |
202 if (f_block->number_of_preds() == 0) { | |
203 BlockBegin::disconnect_edge(f_block, sux); | |
204 } | |
205 adjust_exception_edges(block, f_block); | |
206 | |
207 // update block end | |
208 block->set_end(goto_); | |
209 | |
210 // substitute the phi if possible | |
211 if (sux_phi->as_Phi()->operand_count() == 1) { | |
212 assert(sux_phi->as_Phi()->operand_at(0) == result, "screwed up phi"); | |
213 sux_phi->set_subst(result); | |
214 _has_substitution = true; | |
215 } | |
216 | |
217 // 3) successfully eliminated a conditional expression | |
218 _cee_count++; | |
219 if (PrintCEE) { | |
220 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()); | |
221 tty->print_cr("%d. IfOp in B%d", ifop_count(), block->block_id()); | |
222 } | |
0 | 223 |
1899 | 224 _hir->verify(); |
225 } | |
226 | |
227 Value CE_Eliminator::make_ifop(Value x, Instruction::Condition cond, Value y, Value tval, Value fval) { | |
228 if (!OptimizeIfOps) { | |
229 return new IfOp(x, cond, y, tval, fval); | |
230 } | |
231 | |
232 tval = tval->subst(); | |
233 fval = fval->subst(); | |
234 if (tval == fval) { | |
235 _ifop_count++; | |
236 return tval; | |
237 } | |
238 | |
239 x = x->subst(); | |
240 y = y->subst(); | |
241 | |
242 Constant* y_const = y->as_Constant(); | |
243 if (y_const != NULL) { | |
244 IfOp* x_ifop = x->as_IfOp(); | |
245 if (x_ifop != NULL) { // x is an ifop, y is a constant | |
246 Constant* x_tval_const = x_ifop->tval()->subst()->as_Constant(); | |
247 Constant* x_fval_const = x_ifop->fval()->subst()->as_Constant(); | |
0 | 248 |
1899 | 249 if (x_tval_const != NULL && x_fval_const != NULL) { |
250 Instruction::Condition x_ifop_cond = x_ifop->cond(); | |
251 | |
252 Constant::CompareResult t_compare_res = x_tval_const->compare(cond, y_const); | |
253 Constant::CompareResult f_compare_res = x_fval_const->compare(cond, y_const); | |
254 | |
255 guarantee(t_compare_res != Constant::not_comparable && f_compare_res != Constant::not_comparable, "incomparable constants in IfOp"); | |
256 | |
257 Value new_tval = t_compare_res == Constant::cond_true ? tval : fval; | |
258 Value new_fval = f_compare_res == Constant::cond_true ? tval : fval; | |
0 | 259 |
1899 | 260 _ifop_count++; |
261 if (new_tval == new_fval) { | |
262 return new_tval; | |
263 } else { | |
264 return new IfOp(x_ifop->x(), x_ifop_cond, x_ifop->y(), new_tval, new_fval); | |
265 } | |
266 } | |
267 } else { | |
268 Constant* x_const = x->as_Constant(); | |
269 if (x_const != NULL) { // x and y are constants | |
270 Constant::CompareResult x_compare_res = x_const->compare(cond, y_const); | |
271 guarantee(x_compare_res != Constant::not_comparable, "incomparable constants in IfOp"); | |
272 | |
273 _ifop_count++; | |
274 return x_compare_res == Constant::cond_true ? tval : fval; | |
275 } | |
0 | 276 } |
277 } | |
1899 | 278 return new IfOp(x, cond, y, tval, fval); |
279 } | |
0 | 280 |
281 void Optimizer::eliminate_conditional_expressions() { | |
282 // find conditional expressions & replace them with IfOps | |
283 CE_Eliminator ce(ir()); | |
284 } | |
285 | |
286 class BlockMerger: public BlockClosure { | |
287 private: | |
288 IR* _hir; | |
289 int _merge_count; // the number of block pairs successfully merged | |
290 | |
291 public: | |
292 BlockMerger(IR* hir) | |
293 : _hir(hir) | |
294 , _merge_count(0) | |
295 { | |
296 _hir->iterate_preorder(this); | |
297 } | |
298 | |
299 bool try_merge(BlockBegin* block) { | |
300 BlockEnd* end = block->end(); | |
301 if (end->as_Goto() != NULL) { | |
302 assert(end->number_of_sux() == 1, "end must have exactly one successor"); | |
303 // Note: It would be sufficient to check for the number of successors (= 1) | |
304 // in order to decide if this block can be merged potentially. That | |
305 // would then also include switch statements w/ only a default case. | |
306 // However, in that case we would need to make sure the switch tag | |
307 // expression is executed if it can produce observable side effects. | |
308 // We should probably have the canonicalizer simplifying such switch | |
309 // statements and then we are sure we don't miss these merge opportunities | |
310 // here (was bug - gri 7/7/99). | |
311 BlockBegin* sux = end->default_sux(); | |
312 if (sux->number_of_preds() == 1 && !sux->is_entry_block() && !end->is_safepoint()) { | |
313 // merge the two blocks | |
314 | |
315 #ifdef ASSERT | |
316 // verify that state at the end of block and at the beginning of sux are equal | |
317 // no phi functions must be present at beginning of sux | |
318 ValueStack* sux_state = sux->state(); | |
319 ValueStack* end_state = end->state(); | |
1819 | 320 |
321 assert(end_state->scope() == sux_state->scope(), "scopes must match"); | |
0 | 322 assert(end_state->stack_size() == sux_state->stack_size(), "stack not equal"); |
323 assert(end_state->locals_size() == sux_state->locals_size(), "locals not equal"); | |
324 | |
325 int index; | |
326 Value sux_value; | |
327 for_each_stack_value(sux_state, index, sux_value) { | |
328 assert(sux_value == end_state->stack_at(index), "stack not equal"); | |
329 } | |
330 for_each_local_value(sux_state, index, sux_value) { | |
331 assert(sux_value == end_state->local_at(index), "locals not equal"); | |
332 } | |
333 assert(sux_state->caller_state() == end_state->caller_state(), "caller not equal"); | |
334 #endif | |
335 | |
336 // find instruction before end & append first instruction of sux block | |
337 Instruction* prev = end->prev(block); | |
338 Instruction* next = sux->next(); | |
339 assert(prev->as_BlockEnd() == NULL, "must not be a BlockEnd"); | |
1819 | 340 prev->set_next(next); |
0 | 341 sux->disconnect_from_graph(); |
342 block->set_end(sux->end()); | |
343 // add exception handlers of deleted block, if any | |
344 for (int k = 0; k < sux->number_of_exception_handlers(); k++) { | |
345 BlockBegin* xhandler = sux->exception_handler_at(k); | |
346 block->add_exception_handler(xhandler); | |
347 | |
348 // also substitute predecessor of exception handler | |
349 assert(xhandler->is_predecessor(sux), "missing predecessor"); | |
350 xhandler->remove_predecessor(sux); | |
351 if (!xhandler->is_predecessor(block)) { | |
352 xhandler->add_predecessor(block); | |
353 } | |
354 } | |
355 | |
356 // debugging output | |
357 _merge_count++; | |
358 if (PrintBlockElimination) { | |
359 tty->print_cr("%d. merged B%d & B%d (stack size = %d)", | |
360 _merge_count, block->block_id(), sux->block_id(), sux->state()->stack_size()); | |
361 } | |
362 | |
363 _hir->verify(); | |
364 | |
365 If* if_ = block->end()->as_If(); | |
366 if (if_) { | |
367 IfOp* ifop = if_->x()->as_IfOp(); | |
368 Constant* con = if_->y()->as_Constant(); | |
369 bool swapped = false; | |
370 if (!con || !ifop) { | |
371 ifop = if_->y()->as_IfOp(); | |
372 con = if_->x()->as_Constant(); | |
373 swapped = true; | |
374 } | |
375 if (con && ifop) { | |
376 Constant* tval = ifop->tval()->as_Constant(); | |
377 Constant* fval = ifop->fval()->as_Constant(); | |
378 if (tval && fval) { | |
379 // Find the instruction before if_, starting with ifop. | |
380 // When if_ and ifop are not in the same block, prev | |
381 // becomes NULL In such (rare) cases it is not | |
382 // profitable to perform the optimization. | |
383 Value prev = ifop; | |
384 while (prev != NULL && prev->next() != if_) { | |
385 prev = prev->next(); | |
386 } | |
387 | |
388 if (prev != NULL) { | |
389 Instruction::Condition cond = if_->cond(); | |
390 BlockBegin* tsux = if_->tsux(); | |
391 BlockBegin* fsux = if_->fsux(); | |
392 if (swapped) { | |
393 cond = Instruction::mirror(cond); | |
394 } | |
395 | |
396 BlockBegin* tblock = tval->compare(cond, con, tsux, fsux); | |
397 BlockBegin* fblock = fval->compare(cond, con, tsux, fsux); | |
398 if (tblock != fblock && !if_->is_safepoint()) { | |
399 If* newif = new If(ifop->x(), ifop->cond(), false, ifop->y(), | |
400 tblock, fblock, if_->state_before(), if_->is_safepoint()); | |
401 newif->set_state(if_->state()->copy()); | |
402 | |
403 assert(prev->next() == if_, "must be guaranteed by above search"); | |
1819 | 404 NOT_PRODUCT(newif->set_printable_bci(if_->printable_bci())); |
405 prev->set_next(newif); | |
0 | 406 block->set_end(newif); |
407 | |
408 _merge_count++; | |
409 if (PrintBlockElimination) { | |
410 tty->print_cr("%d. replaced If and IfOp at end of B%d with single If", _merge_count, block->block_id()); | |
411 } | |
412 | |
413 _hir->verify(); | |
414 } | |
415 } | |
416 } | |
417 } | |
418 } | |
419 | |
420 return true; | |
421 } | |
422 } | |
423 return false; | |
424 } | |
425 | |
426 virtual void block_do(BlockBegin* block) { | |
427 _hir->verify(); | |
428 // repeat since the same block may merge again | |
429 while (try_merge(block)) { | |
430 _hir->verify(); | |
431 } | |
432 } | |
433 }; | |
434 | |
435 | |
436 void Optimizer::eliminate_blocks() { | |
437 // merge blocks if possible | |
438 BlockMerger bm(ir()); | |
439 } | |
440 | |
441 | |
442 class NullCheckEliminator; | |
443 class NullCheckVisitor: public InstructionVisitor { | |
444 private: | |
445 NullCheckEliminator* _nce; | |
446 NullCheckEliminator* nce() { return _nce; } | |
447 | |
448 public: | |
449 NullCheckVisitor() {} | |
450 | |
451 void set_eliminator(NullCheckEliminator* nce) { _nce = nce; } | |
452 | |
453 void do_Phi (Phi* x); | |
454 void do_Local (Local* x); | |
455 void do_Constant (Constant* x); | |
456 void do_LoadField (LoadField* x); | |
457 void do_StoreField (StoreField* x); | |
458 void do_ArrayLength (ArrayLength* x); | |
459 void do_LoadIndexed (LoadIndexed* x); | |
460 void do_StoreIndexed (StoreIndexed* x); | |
461 void do_NegateOp (NegateOp* x); | |
462 void do_ArithmeticOp (ArithmeticOp* x); | |
463 void do_ShiftOp (ShiftOp* x); | |
464 void do_LogicOp (LogicOp* x); | |
465 void do_CompareOp (CompareOp* x); | |
466 void do_IfOp (IfOp* x); | |
467 void do_Convert (Convert* x); | |
468 void do_NullCheck (NullCheck* x); | |
469 void do_Invoke (Invoke* x); | |
470 void do_NewInstance (NewInstance* x); | |
471 void do_NewTypeArray (NewTypeArray* x); | |
472 void do_NewObjectArray (NewObjectArray* x); | |
473 void do_NewMultiArray (NewMultiArray* x); | |
474 void do_CheckCast (CheckCast* x); | |
475 void do_InstanceOf (InstanceOf* x); | |
476 void do_MonitorEnter (MonitorEnter* x); | |
477 void do_MonitorExit (MonitorExit* x); | |
478 void do_Intrinsic (Intrinsic* x); | |
479 void do_BlockBegin (BlockBegin* x); | |
480 void do_Goto (Goto* x); | |
481 void do_If (If* x); | |
482 void do_IfInstanceOf (IfInstanceOf* x); | |
483 void do_TableSwitch (TableSwitch* x); | |
484 void do_LookupSwitch (LookupSwitch* x); | |
485 void do_Return (Return* x); | |
486 void do_Throw (Throw* x); | |
487 void do_Base (Base* x); | |
488 void do_OsrEntry (OsrEntry* x); | |
489 void do_ExceptionObject(ExceptionObject* x); | |
490 void do_RoundFP (RoundFP* x); | |
491 void do_UnsafeGetRaw (UnsafeGetRaw* x); | |
492 void do_UnsafePutRaw (UnsafePutRaw* x); | |
493 void do_UnsafeGetObject(UnsafeGetObject* x); | |
494 void do_UnsafePutObject(UnsafePutObject* x); | |
495 void do_UnsafePrefetchRead (UnsafePrefetchRead* x); | |
496 void do_UnsafePrefetchWrite(UnsafePrefetchWrite* x); | |
497 void do_ProfileCall (ProfileCall* x); | |
1783 | 498 void do_ProfileInvoke (ProfileInvoke* x); |
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403dc4c1d7f5
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499 void do_RuntimeCall (RuntimeCall* x); |
0 | 500 }; |
501 | |
502 | |
503 // Because of a static contained within (for the purpose of iteration | |
504 // over instructions), it is only valid to have one of these active at | |
505 // a time | |
1584 | 506 class NullCheckEliminator: public ValueVisitor { |
0 | 507 private: |
508 Optimizer* _opt; | |
509 | |
510 ValueSet* _visitable_instructions; // Visit each instruction only once per basic block | |
511 BlockList* _work_list; // Basic blocks to visit | |
512 | |
513 bool visitable(Value x) { | |
514 assert(_visitable_instructions != NULL, "check"); | |
515 return _visitable_instructions->contains(x); | |
516 } | |
517 void mark_visited(Value x) { | |
518 assert(_visitable_instructions != NULL, "check"); | |
519 _visitable_instructions->remove(x); | |
520 } | |
521 void mark_visitable(Value x) { | |
522 assert(_visitable_instructions != NULL, "check"); | |
523 _visitable_instructions->put(x); | |
524 } | |
525 void clear_visitable_state() { | |
526 assert(_visitable_instructions != NULL, "check"); | |
527 _visitable_instructions->clear(); | |
528 } | |
529 | |
530 ValueSet* _set; // current state, propagated to subsequent BlockBegins | |
531 ValueSetList _block_states; // BlockBegin null-check states for all processed blocks | |
532 NullCheckVisitor _visitor; | |
533 NullCheck* _last_explicit_null_check; | |
534 | |
535 bool set_contains(Value x) { assert(_set != NULL, "check"); return _set->contains(x); } | |
536 void set_put (Value x) { assert(_set != NULL, "check"); _set->put(x); } | |
537 void set_remove (Value x) { assert(_set != NULL, "check"); _set->remove(x); } | |
538 | |
539 BlockList* work_list() { return _work_list; } | |
540 | |
541 void iterate_all(); | |
542 void iterate_one(BlockBegin* block); | |
543 | |
544 ValueSet* state() { return _set; } | |
545 void set_state_from (ValueSet* state) { _set->set_from(state); } | |
546 ValueSet* state_for (BlockBegin* block) { return _block_states[block->block_id()]; } | |
547 void set_state_for (BlockBegin* block, ValueSet* stack) { _block_states[block->block_id()] = stack; } | |
548 // Returns true if caused a change in the block's state. | |
549 bool merge_state_for(BlockBegin* block, | |
550 ValueSet* incoming_state); | |
551 | |
552 public: | |
553 // constructor | |
554 NullCheckEliminator(Optimizer* opt) | |
555 : _opt(opt) | |
556 , _set(new ValueSet()) | |
557 , _last_explicit_null_check(NULL) | |
558 , _block_states(BlockBegin::number_of_blocks(), NULL) | |
559 , _work_list(new BlockList()) { | |
560 _visitable_instructions = new ValueSet(); | |
561 _visitor.set_eliminator(this); | |
562 } | |
563 | |
564 Optimizer* opt() { return _opt; } | |
565 IR* ir () { return opt()->ir(); } | |
566 | |
567 // Process a graph | |
568 void iterate(BlockBegin* root); | |
569 | |
1584 | 570 void visit(Value* f); |
571 | |
0 | 572 // In some situations (like NullCheck(x); getfield(x)) the debug |
573 // information from the explicit NullCheck can be used to populate | |
574 // the getfield, even if the two instructions are in different | |
575 // scopes; this allows implicit null checks to be used but the | |
576 // correct exception information to be generated. We must clear the | |
577 // last-traversed NullCheck when we reach a potentially-exception- | |
578 // throwing instruction, as well as in some other cases. | |
579 void set_last_explicit_null_check(NullCheck* check) { _last_explicit_null_check = check; } | |
580 NullCheck* last_explicit_null_check() { return _last_explicit_null_check; } | |
581 Value last_explicit_null_check_obj() { return (_last_explicit_null_check | |
582 ? _last_explicit_null_check->obj() | |
583 : NULL); } | |
584 NullCheck* consume_last_explicit_null_check() { | |
585 _last_explicit_null_check->unpin(Instruction::PinExplicitNullCheck); | |
586 _last_explicit_null_check->set_can_trap(false); | |
587 return _last_explicit_null_check; | |
588 } | |
589 void clear_last_explicit_null_check() { _last_explicit_null_check = NULL; } | |
590 | |
591 // Handlers for relevant instructions | |
592 // (separated out from NullCheckVisitor for clarity) | |
593 | |
594 // The basic contract is that these must leave the instruction in | |
595 // the desired state; must not assume anything about the state of | |
596 // the instruction. We make multiple passes over some basic blocks | |
597 // and the last pass is the only one whose result is valid. | |
598 void handle_AccessField (AccessField* x); | |
599 void handle_ArrayLength (ArrayLength* x); | |
600 void handle_LoadIndexed (LoadIndexed* x); | |
601 void handle_StoreIndexed (StoreIndexed* x); | |
602 void handle_NullCheck (NullCheck* x); | |
603 void handle_Invoke (Invoke* x); | |
604 void handle_NewInstance (NewInstance* x); | |
605 void handle_NewArray (NewArray* x); | |
606 void handle_AccessMonitor (AccessMonitor* x); | |
607 void handle_Intrinsic (Intrinsic* x); | |
608 void handle_ExceptionObject (ExceptionObject* x); | |
609 void handle_Phi (Phi* x); | |
610 }; | |
611 | |
612 | |
613 // NEEDS_CLEANUP | |
614 // There may be other instructions which need to clear the last | |
615 // explicit null check. Anything across which we can not hoist the | |
616 // debug information for a NullCheck instruction must clear it. It | |
617 // might be safer to pattern match "NullCheck ; {AccessField, | |
618 // ArrayLength, LoadIndexed}" but it is more easily structured this way. | |
619 // Should test to see performance hit of clearing it for all handlers | |
620 // with empty bodies below. If it is negligible then we should leave | |
621 // that in for safety, otherwise should think more about it. | |
622 void NullCheckVisitor::do_Phi (Phi* x) { nce()->handle_Phi(x); } | |
623 void NullCheckVisitor::do_Local (Local* x) {} | |
624 void NullCheckVisitor::do_Constant (Constant* x) { /* FIXME: handle object constants */ } | |
625 void NullCheckVisitor::do_LoadField (LoadField* x) { nce()->handle_AccessField(x); } | |
626 void NullCheckVisitor::do_StoreField (StoreField* x) { nce()->handle_AccessField(x); } | |
627 void NullCheckVisitor::do_ArrayLength (ArrayLength* x) { nce()->handle_ArrayLength(x); } | |
628 void NullCheckVisitor::do_LoadIndexed (LoadIndexed* x) { nce()->handle_LoadIndexed(x); } | |
629 void NullCheckVisitor::do_StoreIndexed (StoreIndexed* x) { nce()->handle_StoreIndexed(x); } | |
630 void NullCheckVisitor::do_NegateOp (NegateOp* x) {} | |
631 void NullCheckVisitor::do_ArithmeticOp (ArithmeticOp* x) { if (x->can_trap()) nce()->clear_last_explicit_null_check(); } | |
632 void NullCheckVisitor::do_ShiftOp (ShiftOp* x) {} | |
633 void NullCheckVisitor::do_LogicOp (LogicOp* x) {} | |
634 void NullCheckVisitor::do_CompareOp (CompareOp* x) {} | |
635 void NullCheckVisitor::do_IfOp (IfOp* x) {} | |
636 void NullCheckVisitor::do_Convert (Convert* x) {} | |
637 void NullCheckVisitor::do_NullCheck (NullCheck* x) { nce()->handle_NullCheck(x); } | |
638 void NullCheckVisitor::do_Invoke (Invoke* x) { nce()->handle_Invoke(x); } | |
639 void NullCheckVisitor::do_NewInstance (NewInstance* x) { nce()->handle_NewInstance(x); } | |
640 void NullCheckVisitor::do_NewTypeArray (NewTypeArray* x) { nce()->handle_NewArray(x); } | |
641 void NullCheckVisitor::do_NewObjectArray (NewObjectArray* x) { nce()->handle_NewArray(x); } | |
642 void NullCheckVisitor::do_NewMultiArray (NewMultiArray* x) { nce()->handle_NewArray(x); } | |
643 void NullCheckVisitor::do_CheckCast (CheckCast* x) {} | |
644 void NullCheckVisitor::do_InstanceOf (InstanceOf* x) {} | |
645 void NullCheckVisitor::do_MonitorEnter (MonitorEnter* x) { nce()->handle_AccessMonitor(x); } | |
646 void NullCheckVisitor::do_MonitorExit (MonitorExit* x) { nce()->handle_AccessMonitor(x); } | |
2446 | 647 void NullCheckVisitor::do_Intrinsic (Intrinsic* x) { nce()->handle_Intrinsic(x); } |
0 | 648 void NullCheckVisitor::do_BlockBegin (BlockBegin* x) {} |
649 void NullCheckVisitor::do_Goto (Goto* x) {} | |
650 void NullCheckVisitor::do_If (If* x) {} | |
651 void NullCheckVisitor::do_IfInstanceOf (IfInstanceOf* x) {} | |
652 void NullCheckVisitor::do_TableSwitch (TableSwitch* x) {} | |
653 void NullCheckVisitor::do_LookupSwitch (LookupSwitch* x) {} | |
654 void NullCheckVisitor::do_Return (Return* x) {} | |
655 void NullCheckVisitor::do_Throw (Throw* x) { nce()->clear_last_explicit_null_check(); } | |
656 void NullCheckVisitor::do_Base (Base* x) {} | |
657 void NullCheckVisitor::do_OsrEntry (OsrEntry* x) {} | |
658 void NullCheckVisitor::do_ExceptionObject(ExceptionObject* x) { nce()->handle_ExceptionObject(x); } | |
659 void NullCheckVisitor::do_RoundFP (RoundFP* x) {} | |
660 void NullCheckVisitor::do_UnsafeGetRaw (UnsafeGetRaw* x) {} | |
661 void NullCheckVisitor::do_UnsafePutRaw (UnsafePutRaw* x) {} | |
662 void NullCheckVisitor::do_UnsafeGetObject(UnsafeGetObject* x) {} | |
663 void NullCheckVisitor::do_UnsafePutObject(UnsafePutObject* x) {} | |
664 void NullCheckVisitor::do_UnsafePrefetchRead (UnsafePrefetchRead* x) {} | |
665 void NullCheckVisitor::do_UnsafePrefetchWrite(UnsafePrefetchWrite* x) {} | |
666 void NullCheckVisitor::do_ProfileCall (ProfileCall* x) { nce()->clear_last_explicit_null_check(); } | |
1783 | 667 void NullCheckVisitor::do_ProfileInvoke (ProfileInvoke* x) {} |
2166
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668 void NullCheckVisitor::do_RuntimeCall (RuntimeCall* x) {} |
0 | 669 |
670 | |
1584 | 671 void NullCheckEliminator::visit(Value* p) { |
0 | 672 assert(*p != NULL, "should not find NULL instructions"); |
1584 | 673 if (visitable(*p)) { |
674 mark_visited(*p); | |
675 (*p)->visit(&_visitor); | |
0 | 676 } |
677 } | |
678 | |
679 bool NullCheckEliminator::merge_state_for(BlockBegin* block, ValueSet* incoming_state) { | |
680 ValueSet* state = state_for(block); | |
681 if (state == NULL) { | |
682 state = incoming_state->copy(); | |
683 set_state_for(block, state); | |
684 return true; | |
685 } else { | |
686 bool changed = state->set_intersect(incoming_state); | |
687 if (PrintNullCheckElimination && changed) { | |
688 tty->print_cr("Block %d's null check state changed", block->block_id()); | |
689 } | |
690 return changed; | |
691 } | |
692 } | |
693 | |
694 | |
695 void NullCheckEliminator::iterate_all() { | |
696 while (work_list()->length() > 0) { | |
697 iterate_one(work_list()->pop()); | |
698 } | |
699 } | |
700 | |
701 | |
702 void NullCheckEliminator::iterate_one(BlockBegin* block) { | |
703 clear_visitable_state(); | |
704 // clear out an old explicit null checks | |
705 set_last_explicit_null_check(NULL); | |
706 | |
707 if (PrintNullCheckElimination) { | |
708 tty->print_cr(" ...iterating block %d in null check elimination for %s::%s%s", | |
709 block->block_id(), | |
710 ir()->method()->holder()->name()->as_utf8(), | |
711 ir()->method()->name()->as_utf8(), | |
712 ir()->method()->signature()->as_symbol()->as_utf8()); | |
713 } | |
714 | |
715 // Create new state if none present (only happens at root) | |
716 if (state_for(block) == NULL) { | |
717 ValueSet* tmp_state = new ValueSet(); | |
718 set_state_for(block, tmp_state); | |
719 // Initial state is that local 0 (receiver) is non-null for | |
720 // non-static methods | |
721 ValueStack* stack = block->state(); | |
722 IRScope* scope = stack->scope(); | |
723 ciMethod* method = scope->method(); | |
724 if (!method->is_static()) { | |
725 Local* local0 = stack->local_at(0)->as_Local(); | |
726 assert(local0 != NULL, "must be"); | |
727 assert(local0->type() == objectType, "invalid type of receiver"); | |
728 | |
729 if (local0 != NULL) { | |
730 // Local 0 is used in this scope | |
731 tmp_state->put(local0); | |
732 if (PrintNullCheckElimination) { | |
733 tty->print_cr("Local 0 (value %d) proven non-null upon entry", local0->id()); | |
734 } | |
735 } | |
736 } | |
737 } | |
738 | |
739 // Must copy block's state to avoid mutating it during iteration | |
740 // through the block -- otherwise "not-null" states can accidentally | |
741 // propagate "up" through the block during processing of backward | |
742 // branches and algorithm is incorrect (and does not converge) | |
743 set_state_from(state_for(block)); | |
744 | |
745 // allow visiting of Phis belonging to this block | |
746 for_each_phi_fun(block, phi, | |
747 mark_visitable(phi); | |
748 ); | |
749 | |
750 BlockEnd* e = block->end(); | |
751 assert(e != NULL, "incomplete graph"); | |
752 int i; | |
753 | |
754 // Propagate the state before this block into the exception | |
755 // handlers. They aren't true successors since we aren't guaranteed | |
756 // to execute the whole block before executing them. Also putting | |
757 // them on first seems to help reduce the amount of iteration to | |
758 // reach a fixed point. | |
759 for (i = 0; i < block->number_of_exception_handlers(); i++) { | |
760 BlockBegin* next = block->exception_handler_at(i); | |
761 if (merge_state_for(next, state())) { | |
762 if (!work_list()->contains(next)) { | |
763 work_list()->push(next); | |
764 } | |
765 } | |
766 } | |
767 | |
768 // Iterate through block, updating state. | |
769 for (Instruction* instr = block; instr != NULL; instr = instr->next()) { | |
770 // Mark instructions in this block as visitable as they are seen | |
771 // in the instruction list. This keeps the iteration from | |
772 // visiting instructions which are references in other blocks or | |
773 // visiting instructions more than once. | |
774 mark_visitable(instr); | |
1819 | 775 if (instr->is_pinned() || instr->can_trap() || (instr->as_NullCheck() != NULL)) { |
0 | 776 mark_visited(instr); |
1584 | 777 instr->input_values_do(this); |
0 | 778 instr->visit(&_visitor); |
779 } | |
780 } | |
781 | |
782 // Propagate state to successors if necessary | |
783 for (i = 0; i < e->number_of_sux(); i++) { | |
784 BlockBegin* next = e->sux_at(i); | |
785 if (merge_state_for(next, state())) { | |
786 if (!work_list()->contains(next)) { | |
787 work_list()->push(next); | |
788 } | |
789 } | |
790 } | |
791 } | |
792 | |
793 | |
794 void NullCheckEliminator::iterate(BlockBegin* block) { | |
795 work_list()->push(block); | |
796 iterate_all(); | |
797 } | |
798 | |
799 void NullCheckEliminator::handle_AccessField(AccessField* x) { | |
800 if (x->is_static()) { | |
801 if (x->as_LoadField() != NULL) { | |
802 // If the field is a non-null static final object field (as is | |
803 // often the case for sun.misc.Unsafe), put this LoadField into | |
804 // the non-null map | |
805 ciField* field = x->field(); | |
806 if (field->is_constant()) { | |
807 ciConstant field_val = field->constant_value(); | |
808 BasicType field_type = field_val.basic_type(); | |
809 if (field_type == T_OBJECT || field_type == T_ARRAY) { | |
810 ciObject* obj_val = field_val.as_object(); | |
811 if (!obj_val->is_null_object()) { | |
812 if (PrintNullCheckElimination) { | |
813 tty->print_cr("AccessField %d proven non-null by static final non-null oop check", | |
814 x->id()); | |
815 } | |
816 set_put(x); | |
817 } | |
818 } | |
819 } | |
820 } | |
821 // Be conservative | |
822 clear_last_explicit_null_check(); | |
823 return; | |
824 } | |
825 | |
826 Value obj = x->obj(); | |
827 if (set_contains(obj)) { | |
828 // Value is non-null => update AccessField | |
829 if (last_explicit_null_check_obj() == obj && !x->needs_patching()) { | |
830 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
831 x->set_needs_null_check(true); | |
832 if (PrintNullCheckElimination) { | |
833 tty->print_cr("Folded NullCheck %d into AccessField %d's null check for value %d", | |
834 x->explicit_null_check()->id(), x->id(), obj->id()); | |
835 } | |
836 } else { | |
837 x->set_explicit_null_check(NULL); | |
838 x->set_needs_null_check(false); | |
839 if (PrintNullCheckElimination) { | |
840 tty->print_cr("Eliminated AccessField %d's null check for value %d", x->id(), obj->id()); | |
841 } | |
842 } | |
843 } else { | |
844 set_put(obj); | |
845 if (PrintNullCheckElimination) { | |
846 tty->print_cr("AccessField %d of value %d proves value to be non-null", x->id(), obj->id()); | |
847 } | |
848 // Ensure previous passes do not cause wrong state | |
849 x->set_needs_null_check(true); | |
850 x->set_explicit_null_check(NULL); | |
851 } | |
852 clear_last_explicit_null_check(); | |
853 } | |
854 | |
855 | |
856 void NullCheckEliminator::handle_ArrayLength(ArrayLength* x) { | |
857 Value array = x->array(); | |
858 if (set_contains(array)) { | |
859 // Value is non-null => update AccessArray | |
860 if (last_explicit_null_check_obj() == array) { | |
861 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
862 x->set_needs_null_check(true); | |
863 if (PrintNullCheckElimination) { | |
864 tty->print_cr("Folded NullCheck %d into ArrayLength %d's null check for value %d", | |
865 x->explicit_null_check()->id(), x->id(), array->id()); | |
866 } | |
867 } else { | |
868 x->set_explicit_null_check(NULL); | |
869 x->set_needs_null_check(false); | |
870 if (PrintNullCheckElimination) { | |
871 tty->print_cr("Eliminated ArrayLength %d's null check for value %d", x->id(), array->id()); | |
872 } | |
873 } | |
874 } else { | |
875 set_put(array); | |
876 if (PrintNullCheckElimination) { | |
877 tty->print_cr("ArrayLength %d of value %d proves value to be non-null", x->id(), array->id()); | |
878 } | |
879 // Ensure previous passes do not cause wrong state | |
880 x->set_needs_null_check(true); | |
881 x->set_explicit_null_check(NULL); | |
882 } | |
883 clear_last_explicit_null_check(); | |
884 } | |
885 | |
886 | |
887 void NullCheckEliminator::handle_LoadIndexed(LoadIndexed* x) { | |
888 Value array = x->array(); | |
889 if (set_contains(array)) { | |
890 // Value is non-null => update AccessArray | |
891 if (last_explicit_null_check_obj() == array) { | |
892 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
893 x->set_needs_null_check(true); | |
894 if (PrintNullCheckElimination) { | |
895 tty->print_cr("Folded NullCheck %d into LoadIndexed %d's null check for value %d", | |
896 x->explicit_null_check()->id(), x->id(), array->id()); | |
897 } | |
898 } else { | |
899 x->set_explicit_null_check(NULL); | |
900 x->set_needs_null_check(false); | |
901 if (PrintNullCheckElimination) { | |
902 tty->print_cr("Eliminated LoadIndexed %d's null check for value %d", x->id(), array->id()); | |
903 } | |
904 } | |
905 } else { | |
906 set_put(array); | |
907 if (PrintNullCheckElimination) { | |
908 tty->print_cr("LoadIndexed %d of value %d proves value to be non-null", x->id(), array->id()); | |
909 } | |
910 // Ensure previous passes do not cause wrong state | |
911 x->set_needs_null_check(true); | |
912 x->set_explicit_null_check(NULL); | |
913 } | |
914 clear_last_explicit_null_check(); | |
915 } | |
916 | |
917 | |
918 void NullCheckEliminator::handle_StoreIndexed(StoreIndexed* x) { | |
919 Value array = x->array(); | |
920 if (set_contains(array)) { | |
921 // Value is non-null => update AccessArray | |
922 if (PrintNullCheckElimination) { | |
923 tty->print_cr("Eliminated StoreIndexed %d's null check for value %d", x->id(), array->id()); | |
924 } | |
925 x->set_needs_null_check(false); | |
926 } else { | |
927 set_put(array); | |
928 if (PrintNullCheckElimination) { | |
929 tty->print_cr("StoreIndexed %d of value %d proves value to be non-null", x->id(), array->id()); | |
930 } | |
931 // Ensure previous passes do not cause wrong state | |
932 x->set_needs_null_check(true); | |
933 } | |
934 clear_last_explicit_null_check(); | |
935 } | |
936 | |
937 | |
938 void NullCheckEliminator::handle_NullCheck(NullCheck* x) { | |
939 Value obj = x->obj(); | |
940 if (set_contains(obj)) { | |
941 // Already proven to be non-null => this NullCheck is useless | |
942 if (PrintNullCheckElimination) { | |
943 tty->print_cr("Eliminated NullCheck %d for value %d", x->id(), obj->id()); | |
944 } | |
945 // Don't unpin since that may shrink obj's live range and make it unavailable for debug info. | |
946 // The code generator won't emit LIR for a NullCheck that cannot trap. | |
947 x->set_can_trap(false); | |
948 } else { | |
949 // May be null => add to map and set last explicit NullCheck | |
950 x->set_can_trap(true); | |
951 // make sure it's pinned if it can trap | |
952 x->pin(Instruction::PinExplicitNullCheck); | |
953 set_put(obj); | |
954 set_last_explicit_null_check(x); | |
955 if (PrintNullCheckElimination) { | |
956 tty->print_cr("NullCheck %d of value %d proves value to be non-null", x->id(), obj->id()); | |
957 } | |
958 } | |
959 } | |
960 | |
961 | |
962 void NullCheckEliminator::handle_Invoke(Invoke* x) { | |
963 if (!x->has_receiver()) { | |
964 // Be conservative | |
965 clear_last_explicit_null_check(); | |
966 return; | |
967 } | |
968 | |
969 Value recv = x->receiver(); | |
970 if (!set_contains(recv)) { | |
971 set_put(recv); | |
972 if (PrintNullCheckElimination) { | |
973 tty->print_cr("Invoke %d of value %d proves value to be non-null", x->id(), recv->id()); | |
974 } | |
975 } | |
976 clear_last_explicit_null_check(); | |
977 } | |
978 | |
979 | |
980 void NullCheckEliminator::handle_NewInstance(NewInstance* x) { | |
981 set_put(x); | |
982 if (PrintNullCheckElimination) { | |
983 tty->print_cr("NewInstance %d is non-null", x->id()); | |
984 } | |
985 } | |
986 | |
987 | |
988 void NullCheckEliminator::handle_NewArray(NewArray* x) { | |
989 set_put(x); | |
990 if (PrintNullCheckElimination) { | |
991 tty->print_cr("NewArray %d is non-null", x->id()); | |
992 } | |
993 } | |
994 | |
995 | |
996 void NullCheckEliminator::handle_ExceptionObject(ExceptionObject* x) { | |
997 set_put(x); | |
998 if (PrintNullCheckElimination) { | |
999 tty->print_cr("ExceptionObject %d is non-null", x->id()); | |
1000 } | |
1001 } | |
1002 | |
1003 | |
1004 void NullCheckEliminator::handle_AccessMonitor(AccessMonitor* x) { | |
1005 Value obj = x->obj(); | |
1006 if (set_contains(obj)) { | |
1007 // Value is non-null => update AccessMonitor | |
1008 if (PrintNullCheckElimination) { | |
1009 tty->print_cr("Eliminated AccessMonitor %d's null check for value %d", x->id(), obj->id()); | |
1010 } | |
1011 x->set_needs_null_check(false); | |
1012 } else { | |
1013 set_put(obj); | |
1014 if (PrintNullCheckElimination) { | |
1015 tty->print_cr("AccessMonitor %d of value %d proves value to be non-null", x->id(), obj->id()); | |
1016 } | |
1017 // Ensure previous passes do not cause wrong state | |
1018 x->set_needs_null_check(true); | |
1019 } | |
1020 clear_last_explicit_null_check(); | |
1021 } | |
1022 | |
1023 | |
1024 void NullCheckEliminator::handle_Intrinsic(Intrinsic* x) { | |
1025 if (!x->has_receiver()) { | |
2446 | 1026 if (x->id() == vmIntrinsics::_arraycopy) { |
1027 for (int i = 0; i < x->number_of_arguments(); i++) { | |
1028 x->set_arg_needs_null_check(i, !set_contains(x->argument_at(i))); | |
1029 } | |
1030 } | |
1031 | |
0 | 1032 // Be conservative |
1033 clear_last_explicit_null_check(); | |
1034 return; | |
1035 } | |
1036 | |
1037 Value recv = x->receiver(); | |
1038 if (set_contains(recv)) { | |
1039 // Value is non-null => update Intrinsic | |
1040 if (PrintNullCheckElimination) { | |
1041 tty->print_cr("Eliminated Intrinsic %d's null check for value %d", x->id(), recv->id()); | |
1042 } | |
1043 x->set_needs_null_check(false); | |
1044 } else { | |
1045 set_put(recv); | |
1046 if (PrintNullCheckElimination) { | |
1047 tty->print_cr("Intrinsic %d of value %d proves value to be non-null", x->id(), recv->id()); | |
1048 } | |
1049 // Ensure previous passes do not cause wrong state | |
1050 x->set_needs_null_check(true); | |
1051 } | |
1052 clear_last_explicit_null_check(); | |
1053 } | |
1054 | |
1055 | |
1056 void NullCheckEliminator::handle_Phi(Phi* x) { | |
1057 int i; | |
1058 bool all_non_null = true; | |
1059 if (x->is_illegal()) { | |
1060 all_non_null = false; | |
1061 } else { | |
1062 for (i = 0; i < x->operand_count(); i++) { | |
1063 Value input = x->operand_at(i); | |
1064 if (!set_contains(input)) { | |
1065 all_non_null = false; | |
1066 } | |
1067 } | |
1068 } | |
1069 | |
1070 if (all_non_null) { | |
1071 // Value is non-null => update Phi | |
1072 if (PrintNullCheckElimination) { | |
1073 tty->print_cr("Eliminated Phi %d's null check for phifun because all inputs are non-null", x->id()); | |
1074 } | |
1075 x->set_needs_null_check(false); | |
1076 } else if (set_contains(x)) { | |
1077 set_remove(x); | |
1078 } | |
1079 } | |
1080 | |
1081 | |
1082 void Optimizer::eliminate_null_checks() { | |
1083 ResourceMark rm; | |
1084 | |
1085 NullCheckEliminator nce(this); | |
1086 | |
1087 if (PrintNullCheckElimination) { | |
1088 tty->print_cr("Starting null check elimination for method %s::%s%s", | |
1089 ir()->method()->holder()->name()->as_utf8(), | |
1090 ir()->method()->name()->as_utf8(), | |
1091 ir()->method()->signature()->as_symbol()->as_utf8()); | |
1092 } | |
1093 | |
1094 // Apply to graph | |
1095 nce.iterate(ir()->start()); | |
1096 | |
1097 // walk over the graph looking for exception | |
1098 // handlers and iterate over them as well | |
1099 int nblocks = BlockBegin::number_of_blocks(); | |
1100 BlockList blocks(nblocks); | |
1101 boolArray visited_block(nblocks, false); | |
1102 | |
1103 blocks.push(ir()->start()); | |
1104 visited_block[ir()->start()->block_id()] = true; | |
1105 for (int i = 0; i < blocks.length(); i++) { | |
1106 BlockBegin* b = blocks[i]; | |
1107 // exception handlers need to be treated as additional roots | |
1108 for (int e = b->number_of_exception_handlers(); e-- > 0; ) { | |
1109 BlockBegin* excp = b->exception_handler_at(e); | |
1110 int id = excp->block_id(); | |
1111 if (!visited_block[id]) { | |
1112 blocks.push(excp); | |
1113 visited_block[id] = true; | |
1114 nce.iterate(excp); | |
1115 } | |
1116 } | |
1117 // traverse successors | |
1118 BlockEnd *end = b->end(); | |
1119 for (int s = end->number_of_sux(); s-- > 0; ) { | |
1120 BlockBegin* next = end->sux_at(s); | |
1121 int id = next->block_id(); | |
1122 if (!visited_block[id]) { | |
1123 blocks.push(next); | |
1124 visited_block[id] = true; | |
1125 } | |
1126 } | |
1127 } | |
1128 | |
1129 | |
1130 if (PrintNullCheckElimination) { | |
1131 tty->print_cr("Done with null check elimination for method %s::%s%s", | |
1132 ir()->method()->holder()->name()->as_utf8(), | |
1133 ir()->method()->name()->as_utf8(), | |
1134 ir()->method()->signature()->as_symbol()->as_utf8()); | |
1135 } | |
1136 } |