Mercurial > hg > truffle
annotate src/share/vm/c1/c1_Optimizer.cpp @ 7666:31540ca73e81
Remove ControlFlowException in SimpleLanguage.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
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date | Fri, 01 Feb 2013 19:53:52 +0100 |
parents | d804e148cff8 |
children | 46f6f063b272 |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1999, 2012, 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" | |
6843 | 32 #include "compiler/compileLog.hpp" |
0 | 33 |
34 define_array(ValueSetArray, ValueSet*); | |
35 define_stack(ValueSetList, ValueSetArray); | |
36 | |
37 | |
38 Optimizer::Optimizer(IR* ir) { | |
39 assert(ir->is_valid(), "IR must be valid"); | |
40 _ir = ir; | |
41 } | |
42 | |
43 class CE_Eliminator: public BlockClosure { | |
44 private: | |
45 IR* _hir; | |
46 int _cee_count; // the number of CEs successfully eliminated | |
1899 | 47 int _ifop_count; // the number of IfOps successfully simplified |
0 | 48 int _has_substitution; |
49 | |
50 public: | |
1899 | 51 CE_Eliminator(IR* hir) : _cee_count(0), _ifop_count(0), _hir(hir) { |
0 | 52 _has_substitution = false; |
53 _hir->iterate_preorder(this); | |
54 if (_has_substitution) { | |
1899 | 55 // substituted some ifops/phis, so resolve the substitution |
0 | 56 SubstitutionResolver sr(_hir); |
57 } | |
6843 | 58 |
59 CompileLog* log = _hir->compilation()->log(); | |
60 if (log != NULL) | |
61 log->set_context("optimize name='cee'"); | |
0 | 62 } |
6843 | 63 |
64 ~CE_Eliminator() { | |
65 CompileLog* log = _hir->compilation()->log(); | |
66 if (log != NULL) | |
67 log->clear_context(); // skip marker if nothing was printed | |
68 } | |
69 | |
0 | 70 int cee_count() const { return _cee_count; } |
1899 | 71 int ifop_count() const { return _ifop_count; } |
0 | 72 |
73 void adjust_exception_edges(BlockBegin* block, BlockBegin* sux) { | |
74 int e = sux->number_of_exception_handlers(); | |
75 for (int i = 0; i < e; i++) { | |
76 BlockBegin* xhandler = sux->exception_handler_at(i); | |
77 block->add_exception_handler(xhandler); | |
78 | |
79 assert(xhandler->is_predecessor(sux), "missing predecessor"); | |
80 if (sux->number_of_preds() == 0) { | |
81 // sux is disconnected from graph so disconnect from exception handlers | |
82 xhandler->remove_predecessor(sux); | |
83 } | |
84 if (!xhandler->is_predecessor(block)) { | |
85 xhandler->add_predecessor(block); | |
86 } | |
87 } | |
88 } | |
89 | |
1899 | 90 virtual void block_do(BlockBegin* block); |
91 | |
92 private: | |
93 Value make_ifop(Value x, Instruction::Condition cond, Value y, Value tval, Value fval); | |
94 }; | |
0 | 95 |
1899 | 96 void CE_Eliminator::block_do(BlockBegin* block) { |
97 // 1) find conditional expression | |
98 // check if block ends with an If | |
99 If* if_ = block->end()->as_If(); | |
100 if (if_ == NULL) return; | |
0 | 101 |
1899 | 102 // check if If works on int or object types |
103 // (we cannot handle If's working on long, float or doubles yet, | |
104 // since IfOp doesn't support them - these If's show up if cmp | |
105 // operations followed by If's are eliminated) | |
106 ValueType* if_type = if_->x()->type(); | |
107 if (!if_type->is_int() && !if_type->is_object()) return; | |
0 | 108 |
1899 | 109 BlockBegin* t_block = if_->tsux(); |
110 BlockBegin* f_block = if_->fsux(); | |
111 Instruction* t_cur = t_block->next(); | |
112 Instruction* f_cur = f_block->next(); | |
0 | 113 |
1899 | 114 // one Constant may be present between BlockBegin and BlockEnd |
115 Value t_const = NULL; | |
116 Value f_const = NULL; | |
117 if (t_cur->as_Constant() != NULL && !t_cur->can_trap()) { | |
118 t_const = t_cur; | |
119 t_cur = t_cur->next(); | |
120 } | |
121 if (f_cur->as_Constant() != NULL && !f_cur->can_trap()) { | |
122 f_const = f_cur; | |
123 f_cur = f_cur->next(); | |
124 } | |
0 | 125 |
1899 | 126 // check if both branches end with a goto |
127 Goto* t_goto = t_cur->as_Goto(); | |
128 if (t_goto == NULL) return; | |
129 Goto* f_goto = f_cur->as_Goto(); | |
130 if (f_goto == NULL) return; | |
0 | 131 |
1899 | 132 // check if both gotos merge into the same block |
133 BlockBegin* sux = t_goto->default_sux(); | |
134 if (sux != f_goto->default_sux()) return; | |
0 | 135 |
1899 | 136 // check if at least one word was pushed on sux_state |
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137 // inlining depths must match |
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138 ValueStack* if_state = if_->state(); |
1899 | 139 ValueStack* sux_state = sux->state(); |
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140 if (if_state->scope()->level() > sux_state->scope()->level()) { |
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141 while (sux_state->scope() != if_state->scope()) { |
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142 if_state = if_state->caller_state(); |
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143 assert(if_state != NULL, "states do not match up"); |
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144 } |
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145 } else if (if_state->scope()->level() < sux_state->scope()->level()) { |
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146 while (sux_state->scope() != if_state->scope()) { |
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147 sux_state = sux_state->caller_state(); |
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148 assert(sux_state != NULL, "states do not match up"); |
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149 } |
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150 } |
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151 |
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152 if (sux_state->stack_size() <= if_state->stack_size()) return; |
0 | 153 |
1899 | 154 // check if phi function is present at end of successor stack and that |
155 // only this phi was pushed on the stack | |
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156 Value sux_phi = sux_state->stack_at(if_state->stack_size()); |
1899 | 157 if (sux_phi == NULL || sux_phi->as_Phi() == NULL || sux_phi->as_Phi()->block() != sux) return; |
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158 if (sux_phi->type()->size() != sux_state->stack_size() - if_state->stack_size()) return; |
0 | 159 |
1899 | 160 // get the values that were pushed in the true- and false-branch |
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161 Value t_value = t_goto->state()->stack_at(if_state->stack_size()); |
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162 Value f_value = f_goto->state()->stack_at(if_state->stack_size()); |
1899 | 163 |
164 // backend does not support floats | |
165 assert(t_value->type()->base() == f_value->type()->base(), "incompatible types"); | |
166 if (t_value->type()->is_float_kind()) return; | |
0 | 167 |
1899 | 168 // check that successor has no other phi functions but sux_phi |
169 // this can happen when t_block or f_block contained additonal stores to local variables | |
170 // that are no longer represented by explicit instructions | |
171 for_each_phi_fun(sux, phi, | |
172 if (phi != sux_phi) return; | |
173 ); | |
174 // true and false blocks can't have phis | |
175 for_each_phi_fun(t_block, phi, return; ); | |
176 for_each_phi_fun(f_block, phi, return; ); | |
177 | |
178 // 2) substitute conditional expression | |
179 // with an IfOp followed by a Goto | |
180 // cut if_ away and get node before | |
181 Instruction* cur_end = if_->prev(block); | |
0 | 182 |
1899 | 183 // append constants of true- and false-block if necessary |
184 // clone constants because original block must not be destroyed | |
185 assert((t_value != f_const && f_value != t_const) || t_const == f_const, "mismatch"); | |
186 if (t_value == t_const) { | |
187 t_value = new Constant(t_const->type()); | |
188 NOT_PRODUCT(t_value->set_printable_bci(if_->printable_bci())); | |
189 cur_end = cur_end->set_next(t_value); | |
190 } | |
191 if (f_value == f_const) { | |
192 f_value = new Constant(f_const->type()); | |
193 NOT_PRODUCT(f_value->set_printable_bci(if_->printable_bci())); | |
194 cur_end = cur_end->set_next(f_value); | |
195 } | |
0 | 196 |
1899 | 197 Value result = make_ifop(if_->x(), if_->cond(), if_->y(), t_value, f_value); |
198 assert(result != NULL, "make_ifop must return a non-null instruction"); | |
199 if (!result->is_linked() && result->can_be_linked()) { | |
1819 | 200 NOT_PRODUCT(result->set_printable_bci(if_->printable_bci())); |
201 cur_end = cur_end->set_next(result); | |
1899 | 202 } |
0 | 203 |
1899 | 204 // append Goto to successor |
205 ValueStack* state_before = if_->is_safepoint() ? if_->state_before() : NULL; | |
206 Goto* goto_ = new Goto(sux, state_before, if_->is_safepoint() || t_goto->is_safepoint() || f_goto->is_safepoint()); | |
207 | |
208 // prepare state for Goto | |
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209 ValueStack* goto_state = if_state; |
1899 | 210 goto_state = goto_state->copy(ValueStack::StateAfter, goto_state->bci()); |
211 goto_state->push(result->type(), result); | |
212 assert(goto_state->is_same(sux_state), "states must match now"); | |
213 goto_->set_state(goto_state); | |
214 | |
215 cur_end = cur_end->set_next(goto_, goto_state->bci()); | |
216 | |
217 // Adjust control flow graph | |
218 BlockBegin::disconnect_edge(block, t_block); | |
219 BlockBegin::disconnect_edge(block, f_block); | |
220 if (t_block->number_of_preds() == 0) { | |
221 BlockBegin::disconnect_edge(t_block, sux); | |
222 } | |
223 adjust_exception_edges(block, t_block); | |
224 if (f_block->number_of_preds() == 0) { | |
225 BlockBegin::disconnect_edge(f_block, sux); | |
226 } | |
227 adjust_exception_edges(block, f_block); | |
228 | |
229 // update block end | |
230 block->set_end(goto_); | |
231 | |
232 // substitute the phi if possible | |
233 if (sux_phi->as_Phi()->operand_count() == 1) { | |
234 assert(sux_phi->as_Phi()->operand_at(0) == result, "screwed up phi"); | |
235 sux_phi->set_subst(result); | |
236 _has_substitution = true; | |
237 } | |
238 | |
239 // 3) successfully eliminated a conditional expression | |
240 _cee_count++; | |
241 if (PrintCEE) { | |
242 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()); | |
243 tty->print_cr("%d. IfOp in B%d", ifop_count(), block->block_id()); | |
244 } | |
0 | 245 |
1899 | 246 _hir->verify(); |
247 } | |
248 | |
249 Value CE_Eliminator::make_ifop(Value x, Instruction::Condition cond, Value y, Value tval, Value fval) { | |
250 if (!OptimizeIfOps) { | |
251 return new IfOp(x, cond, y, tval, fval); | |
252 } | |
253 | |
254 tval = tval->subst(); | |
255 fval = fval->subst(); | |
256 if (tval == fval) { | |
257 _ifop_count++; | |
258 return tval; | |
259 } | |
260 | |
261 x = x->subst(); | |
262 y = y->subst(); | |
263 | |
264 Constant* y_const = y->as_Constant(); | |
265 if (y_const != NULL) { | |
266 IfOp* x_ifop = x->as_IfOp(); | |
267 if (x_ifop != NULL) { // x is an ifop, y is a constant | |
268 Constant* x_tval_const = x_ifop->tval()->subst()->as_Constant(); | |
269 Constant* x_fval_const = x_ifop->fval()->subst()->as_Constant(); | |
0 | 270 |
1899 | 271 if (x_tval_const != NULL && x_fval_const != NULL) { |
272 Instruction::Condition x_ifop_cond = x_ifop->cond(); | |
273 | |
274 Constant::CompareResult t_compare_res = x_tval_const->compare(cond, y_const); | |
275 Constant::CompareResult f_compare_res = x_fval_const->compare(cond, y_const); | |
276 | |
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277 // not_comparable here is a valid return in case we're comparing unloaded oop constants |
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278 if (t_compare_res != Constant::not_comparable && f_compare_res != Constant::not_comparable) { |
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279 Value new_tval = t_compare_res == Constant::cond_true ? tval : fval; |
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280 Value new_fval = f_compare_res == Constant::cond_true ? tval : fval; |
0 | 281 |
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282 _ifop_count++; |
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283 if (new_tval == new_fval) { |
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284 return new_tval; |
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285 } else { |
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286 return new IfOp(x_ifop->x(), x_ifop_cond, x_ifop->y(), new_tval, new_fval); |
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287 } |
1899 | 288 } |
289 } | |
290 } else { | |
291 Constant* x_const = x->as_Constant(); | |
292 if (x_const != NULL) { // x and y are constants | |
293 Constant::CompareResult x_compare_res = x_const->compare(cond, y_const); | |
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294 // not_comparable here is a valid return in case we're comparing unloaded oop constants |
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295 if (x_compare_res != Constant::not_comparable) { |
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296 _ifop_count++; |
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297 return x_compare_res == Constant::cond_true ? tval : fval; |
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298 } |
1899 | 299 } |
0 | 300 } |
301 } | |
1899 | 302 return new IfOp(x, cond, y, tval, fval); |
303 } | |
0 | 304 |
305 void Optimizer::eliminate_conditional_expressions() { | |
306 // find conditional expressions & replace them with IfOps | |
307 CE_Eliminator ce(ir()); | |
308 } | |
309 | |
310 class BlockMerger: public BlockClosure { | |
311 private: | |
312 IR* _hir; | |
313 int _merge_count; // the number of block pairs successfully merged | |
314 | |
315 public: | |
316 BlockMerger(IR* hir) | |
317 : _hir(hir) | |
318 , _merge_count(0) | |
319 { | |
320 _hir->iterate_preorder(this); | |
6843 | 321 CompileLog* log = _hir->compilation()->log(); |
322 if (log != NULL) | |
323 log->set_context("optimize name='eliminate_blocks'"); | |
324 } | |
325 | |
326 ~BlockMerger() { | |
327 CompileLog* log = _hir->compilation()->log(); | |
328 if (log != NULL) | |
329 log->clear_context(); // skip marker if nothing was printed | |
0 | 330 } |
331 | |
332 bool try_merge(BlockBegin* block) { | |
333 BlockEnd* end = block->end(); | |
334 if (end->as_Goto() != NULL) { | |
335 assert(end->number_of_sux() == 1, "end must have exactly one successor"); | |
336 // Note: It would be sufficient to check for the number of successors (= 1) | |
337 // in order to decide if this block can be merged potentially. That | |
338 // would then also include switch statements w/ only a default case. | |
339 // However, in that case we would need to make sure the switch tag | |
340 // expression is executed if it can produce observable side effects. | |
341 // We should probably have the canonicalizer simplifying such switch | |
342 // statements and then we are sure we don't miss these merge opportunities | |
343 // here (was bug - gri 7/7/99). | |
344 BlockBegin* sux = end->default_sux(); | |
345 if (sux->number_of_preds() == 1 && !sux->is_entry_block() && !end->is_safepoint()) { | |
346 // merge the two blocks | |
347 | |
348 #ifdef ASSERT | |
349 // verify that state at the end of block and at the beginning of sux are equal | |
350 // no phi functions must be present at beginning of sux | |
351 ValueStack* sux_state = sux->state(); | |
352 ValueStack* end_state = end->state(); | |
1819 | 353 |
354 assert(end_state->scope() == sux_state->scope(), "scopes must match"); | |
0 | 355 assert(end_state->stack_size() == sux_state->stack_size(), "stack not equal"); |
356 assert(end_state->locals_size() == sux_state->locals_size(), "locals not equal"); | |
357 | |
358 int index; | |
359 Value sux_value; | |
360 for_each_stack_value(sux_state, index, sux_value) { | |
361 assert(sux_value == end_state->stack_at(index), "stack not equal"); | |
362 } | |
363 for_each_local_value(sux_state, index, sux_value) { | |
364 assert(sux_value == end_state->local_at(index), "locals not equal"); | |
365 } | |
366 assert(sux_state->caller_state() == end_state->caller_state(), "caller not equal"); | |
367 #endif | |
368 | |
369 // find instruction before end & append first instruction of sux block | |
370 Instruction* prev = end->prev(block); | |
371 Instruction* next = sux->next(); | |
372 assert(prev->as_BlockEnd() == NULL, "must not be a BlockEnd"); | |
1819 | 373 prev->set_next(next); |
0 | 374 sux->disconnect_from_graph(); |
375 block->set_end(sux->end()); | |
376 // add exception handlers of deleted block, if any | |
377 for (int k = 0; k < sux->number_of_exception_handlers(); k++) { | |
378 BlockBegin* xhandler = sux->exception_handler_at(k); | |
379 block->add_exception_handler(xhandler); | |
380 | |
381 // also substitute predecessor of exception handler | |
382 assert(xhandler->is_predecessor(sux), "missing predecessor"); | |
383 xhandler->remove_predecessor(sux); | |
384 if (!xhandler->is_predecessor(block)) { | |
385 xhandler->add_predecessor(block); | |
386 } | |
387 } | |
388 | |
389 // debugging output | |
390 _merge_count++; | |
391 if (PrintBlockElimination) { | |
392 tty->print_cr("%d. merged B%d & B%d (stack size = %d)", | |
393 _merge_count, block->block_id(), sux->block_id(), sux->state()->stack_size()); | |
394 } | |
395 | |
396 _hir->verify(); | |
397 | |
398 If* if_ = block->end()->as_If(); | |
399 if (if_) { | |
400 IfOp* ifop = if_->x()->as_IfOp(); | |
401 Constant* con = if_->y()->as_Constant(); | |
402 bool swapped = false; | |
403 if (!con || !ifop) { | |
404 ifop = if_->y()->as_IfOp(); | |
405 con = if_->x()->as_Constant(); | |
406 swapped = true; | |
407 } | |
408 if (con && ifop) { | |
409 Constant* tval = ifop->tval()->as_Constant(); | |
410 Constant* fval = ifop->fval()->as_Constant(); | |
411 if (tval && fval) { | |
412 // Find the instruction before if_, starting with ifop. | |
413 // When if_ and ifop are not in the same block, prev | |
414 // becomes NULL In such (rare) cases it is not | |
415 // profitable to perform the optimization. | |
416 Value prev = ifop; | |
417 while (prev != NULL && prev->next() != if_) { | |
418 prev = prev->next(); | |
419 } | |
420 | |
421 if (prev != NULL) { | |
422 Instruction::Condition cond = if_->cond(); | |
423 BlockBegin* tsux = if_->tsux(); | |
424 BlockBegin* fsux = if_->fsux(); | |
425 if (swapped) { | |
426 cond = Instruction::mirror(cond); | |
427 } | |
428 | |
429 BlockBegin* tblock = tval->compare(cond, con, tsux, fsux); | |
430 BlockBegin* fblock = fval->compare(cond, con, tsux, fsux); | |
431 if (tblock != fblock && !if_->is_safepoint()) { | |
432 If* newif = new If(ifop->x(), ifop->cond(), false, ifop->y(), | |
433 tblock, fblock, if_->state_before(), if_->is_safepoint()); | |
434 newif->set_state(if_->state()->copy()); | |
435 | |
436 assert(prev->next() == if_, "must be guaranteed by above search"); | |
1819 | 437 NOT_PRODUCT(newif->set_printable_bci(if_->printable_bci())); |
438 prev->set_next(newif); | |
0 | 439 block->set_end(newif); |
440 | |
441 _merge_count++; | |
442 if (PrintBlockElimination) { | |
443 tty->print_cr("%d. replaced If and IfOp at end of B%d with single If", _merge_count, block->block_id()); | |
444 } | |
445 | |
446 _hir->verify(); | |
447 } | |
448 } | |
449 } | |
450 } | |
451 } | |
452 | |
453 return true; | |
454 } | |
455 } | |
456 return false; | |
457 } | |
458 | |
459 virtual void block_do(BlockBegin* block) { | |
460 _hir->verify(); | |
461 // repeat since the same block may merge again | |
462 while (try_merge(block)) { | |
463 _hir->verify(); | |
464 } | |
465 } | |
466 }; | |
467 | |
468 | |
469 void Optimizer::eliminate_blocks() { | |
470 // merge blocks if possible | |
471 BlockMerger bm(ir()); | |
472 } | |
473 | |
474 | |
475 class NullCheckEliminator; | |
476 class NullCheckVisitor: public InstructionVisitor { | |
477 private: | |
478 NullCheckEliminator* _nce; | |
479 NullCheckEliminator* nce() { return _nce; } | |
480 | |
481 public: | |
482 NullCheckVisitor() {} | |
483 | |
484 void set_eliminator(NullCheckEliminator* nce) { _nce = nce; } | |
485 | |
486 void do_Phi (Phi* x); | |
487 void do_Local (Local* x); | |
488 void do_Constant (Constant* x); | |
489 void do_LoadField (LoadField* x); | |
490 void do_StoreField (StoreField* x); | |
491 void do_ArrayLength (ArrayLength* x); | |
492 void do_LoadIndexed (LoadIndexed* x); | |
493 void do_StoreIndexed (StoreIndexed* x); | |
494 void do_NegateOp (NegateOp* x); | |
495 void do_ArithmeticOp (ArithmeticOp* x); | |
496 void do_ShiftOp (ShiftOp* x); | |
497 void do_LogicOp (LogicOp* x); | |
498 void do_CompareOp (CompareOp* x); | |
499 void do_IfOp (IfOp* x); | |
500 void do_Convert (Convert* x); | |
501 void do_NullCheck (NullCheck* x); | |
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502 void do_TypeCast (TypeCast* x); |
0 | 503 void do_Invoke (Invoke* x); |
504 void do_NewInstance (NewInstance* x); | |
505 void do_NewTypeArray (NewTypeArray* x); | |
506 void do_NewObjectArray (NewObjectArray* x); | |
507 void do_NewMultiArray (NewMultiArray* x); | |
508 void do_CheckCast (CheckCast* x); | |
509 void do_InstanceOf (InstanceOf* x); | |
510 void do_MonitorEnter (MonitorEnter* x); | |
511 void do_MonitorExit (MonitorExit* x); | |
512 void do_Intrinsic (Intrinsic* x); | |
513 void do_BlockBegin (BlockBegin* x); | |
514 void do_Goto (Goto* x); | |
515 void do_If (If* x); | |
516 void do_IfInstanceOf (IfInstanceOf* x); | |
517 void do_TableSwitch (TableSwitch* x); | |
518 void do_LookupSwitch (LookupSwitch* x); | |
519 void do_Return (Return* x); | |
520 void do_Throw (Throw* x); | |
521 void do_Base (Base* x); | |
522 void do_OsrEntry (OsrEntry* x); | |
523 void do_ExceptionObject(ExceptionObject* x); | |
524 void do_RoundFP (RoundFP* x); | |
525 void do_UnsafeGetRaw (UnsafeGetRaw* x); | |
526 void do_UnsafePutRaw (UnsafePutRaw* x); | |
527 void do_UnsafeGetObject(UnsafeGetObject* x); | |
528 void do_UnsafePutObject(UnsafePutObject* x); | |
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529 void do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x); |
0 | 530 void do_UnsafePrefetchRead (UnsafePrefetchRead* x); |
531 void do_UnsafePrefetchWrite(UnsafePrefetchWrite* x); | |
532 void do_ProfileCall (ProfileCall* x); | |
1783 | 533 void do_ProfileInvoke (ProfileInvoke* x); |
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534 void do_RuntimeCall (RuntimeCall* x); |
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535 void do_MemBar (MemBar* x); |
0 | 536 }; |
537 | |
538 | |
539 // Because of a static contained within (for the purpose of iteration | |
540 // over instructions), it is only valid to have one of these active at | |
541 // a time | |
1584 | 542 class NullCheckEliminator: public ValueVisitor { |
0 | 543 private: |
544 Optimizer* _opt; | |
545 | |
546 ValueSet* _visitable_instructions; // Visit each instruction only once per basic block | |
547 BlockList* _work_list; // Basic blocks to visit | |
548 | |
549 bool visitable(Value x) { | |
550 assert(_visitable_instructions != NULL, "check"); | |
551 return _visitable_instructions->contains(x); | |
552 } | |
553 void mark_visited(Value x) { | |
554 assert(_visitable_instructions != NULL, "check"); | |
555 _visitable_instructions->remove(x); | |
556 } | |
557 void mark_visitable(Value x) { | |
558 assert(_visitable_instructions != NULL, "check"); | |
559 _visitable_instructions->put(x); | |
560 } | |
561 void clear_visitable_state() { | |
562 assert(_visitable_instructions != NULL, "check"); | |
563 _visitable_instructions->clear(); | |
564 } | |
565 | |
566 ValueSet* _set; // current state, propagated to subsequent BlockBegins | |
567 ValueSetList _block_states; // BlockBegin null-check states for all processed blocks | |
568 NullCheckVisitor _visitor; | |
569 NullCheck* _last_explicit_null_check; | |
570 | |
571 bool set_contains(Value x) { assert(_set != NULL, "check"); return _set->contains(x); } | |
572 void set_put (Value x) { assert(_set != NULL, "check"); _set->put(x); } | |
573 void set_remove (Value x) { assert(_set != NULL, "check"); _set->remove(x); } | |
574 | |
575 BlockList* work_list() { return _work_list; } | |
576 | |
577 void iterate_all(); | |
578 void iterate_one(BlockBegin* block); | |
579 | |
580 ValueSet* state() { return _set; } | |
581 void set_state_from (ValueSet* state) { _set->set_from(state); } | |
582 ValueSet* state_for (BlockBegin* block) { return _block_states[block->block_id()]; } | |
583 void set_state_for (BlockBegin* block, ValueSet* stack) { _block_states[block->block_id()] = stack; } | |
584 // Returns true if caused a change in the block's state. | |
585 bool merge_state_for(BlockBegin* block, | |
586 ValueSet* incoming_state); | |
587 | |
588 public: | |
589 // constructor | |
590 NullCheckEliminator(Optimizer* opt) | |
591 : _opt(opt) | |
592 , _set(new ValueSet()) | |
593 , _last_explicit_null_check(NULL) | |
594 , _block_states(BlockBegin::number_of_blocks(), NULL) | |
595 , _work_list(new BlockList()) { | |
596 _visitable_instructions = new ValueSet(); | |
597 _visitor.set_eliminator(this); | |
6843 | 598 CompileLog* log = _opt->ir()->compilation()->log(); |
599 if (log != NULL) | |
600 log->set_context("optimize name='null_check_elimination'"); | |
601 } | |
602 | |
603 ~NullCheckEliminator() { | |
604 CompileLog* log = _opt->ir()->compilation()->log(); | |
605 if (log != NULL) | |
606 log->clear_context(); // skip marker if nothing was printed | |
0 | 607 } |
608 | |
609 Optimizer* opt() { return _opt; } | |
610 IR* ir () { return opt()->ir(); } | |
611 | |
612 // Process a graph | |
613 void iterate(BlockBegin* root); | |
614 | |
1584 | 615 void visit(Value* f); |
616 | |
0 | 617 // In some situations (like NullCheck(x); getfield(x)) the debug |
618 // information from the explicit NullCheck can be used to populate | |
619 // the getfield, even if the two instructions are in different | |
620 // scopes; this allows implicit null checks to be used but the | |
621 // correct exception information to be generated. We must clear the | |
622 // last-traversed NullCheck when we reach a potentially-exception- | |
623 // throwing instruction, as well as in some other cases. | |
624 void set_last_explicit_null_check(NullCheck* check) { _last_explicit_null_check = check; } | |
625 NullCheck* last_explicit_null_check() { return _last_explicit_null_check; } | |
626 Value last_explicit_null_check_obj() { return (_last_explicit_null_check | |
627 ? _last_explicit_null_check->obj() | |
628 : NULL); } | |
629 NullCheck* consume_last_explicit_null_check() { | |
630 _last_explicit_null_check->unpin(Instruction::PinExplicitNullCheck); | |
631 _last_explicit_null_check->set_can_trap(false); | |
632 return _last_explicit_null_check; | |
633 } | |
634 void clear_last_explicit_null_check() { _last_explicit_null_check = NULL; } | |
635 | |
636 // Handlers for relevant instructions | |
637 // (separated out from NullCheckVisitor for clarity) | |
638 | |
639 // The basic contract is that these must leave the instruction in | |
640 // the desired state; must not assume anything about the state of | |
641 // the instruction. We make multiple passes over some basic blocks | |
642 // and the last pass is the only one whose result is valid. | |
643 void handle_AccessField (AccessField* x); | |
644 void handle_ArrayLength (ArrayLength* x); | |
645 void handle_LoadIndexed (LoadIndexed* x); | |
646 void handle_StoreIndexed (StoreIndexed* x); | |
647 void handle_NullCheck (NullCheck* x); | |
648 void handle_Invoke (Invoke* x); | |
649 void handle_NewInstance (NewInstance* x); | |
650 void handle_NewArray (NewArray* x); | |
651 void handle_AccessMonitor (AccessMonitor* x); | |
652 void handle_Intrinsic (Intrinsic* x); | |
653 void handle_ExceptionObject (ExceptionObject* x); | |
654 void handle_Phi (Phi* x); | |
655 }; | |
656 | |
657 | |
658 // NEEDS_CLEANUP | |
659 // There may be other instructions which need to clear the last | |
660 // explicit null check. Anything across which we can not hoist the | |
661 // debug information for a NullCheck instruction must clear it. It | |
662 // might be safer to pattern match "NullCheck ; {AccessField, | |
663 // ArrayLength, LoadIndexed}" but it is more easily structured this way. | |
664 // Should test to see performance hit of clearing it for all handlers | |
665 // with empty bodies below. If it is negligible then we should leave | |
666 // that in for safety, otherwise should think more about it. | |
667 void NullCheckVisitor::do_Phi (Phi* x) { nce()->handle_Phi(x); } | |
668 void NullCheckVisitor::do_Local (Local* x) {} | |
669 void NullCheckVisitor::do_Constant (Constant* x) { /* FIXME: handle object constants */ } | |
670 void NullCheckVisitor::do_LoadField (LoadField* x) { nce()->handle_AccessField(x); } | |
671 void NullCheckVisitor::do_StoreField (StoreField* x) { nce()->handle_AccessField(x); } | |
672 void NullCheckVisitor::do_ArrayLength (ArrayLength* x) { nce()->handle_ArrayLength(x); } | |
673 void NullCheckVisitor::do_LoadIndexed (LoadIndexed* x) { nce()->handle_LoadIndexed(x); } | |
674 void NullCheckVisitor::do_StoreIndexed (StoreIndexed* x) { nce()->handle_StoreIndexed(x); } | |
675 void NullCheckVisitor::do_NegateOp (NegateOp* x) {} | |
676 void NullCheckVisitor::do_ArithmeticOp (ArithmeticOp* x) { if (x->can_trap()) nce()->clear_last_explicit_null_check(); } | |
677 void NullCheckVisitor::do_ShiftOp (ShiftOp* x) {} | |
678 void NullCheckVisitor::do_LogicOp (LogicOp* x) {} | |
679 void NullCheckVisitor::do_CompareOp (CompareOp* x) {} | |
680 void NullCheckVisitor::do_IfOp (IfOp* x) {} | |
681 void NullCheckVisitor::do_Convert (Convert* x) {} | |
682 void NullCheckVisitor::do_NullCheck (NullCheck* x) { nce()->handle_NullCheck(x); } | |
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683 void NullCheckVisitor::do_TypeCast (TypeCast* x) {} |
0 | 684 void NullCheckVisitor::do_Invoke (Invoke* x) { nce()->handle_Invoke(x); } |
685 void NullCheckVisitor::do_NewInstance (NewInstance* x) { nce()->handle_NewInstance(x); } | |
686 void NullCheckVisitor::do_NewTypeArray (NewTypeArray* x) { nce()->handle_NewArray(x); } | |
687 void NullCheckVisitor::do_NewObjectArray (NewObjectArray* x) { nce()->handle_NewArray(x); } | |
688 void NullCheckVisitor::do_NewMultiArray (NewMultiArray* x) { nce()->handle_NewArray(x); } | |
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689 void NullCheckVisitor::do_CheckCast (CheckCast* x) { nce()->clear_last_explicit_null_check(); } |
0 | 690 void NullCheckVisitor::do_InstanceOf (InstanceOf* x) {} |
691 void NullCheckVisitor::do_MonitorEnter (MonitorEnter* x) { nce()->handle_AccessMonitor(x); } | |
692 void NullCheckVisitor::do_MonitorExit (MonitorExit* x) { nce()->handle_AccessMonitor(x); } | |
2446 | 693 void NullCheckVisitor::do_Intrinsic (Intrinsic* x) { nce()->handle_Intrinsic(x); } |
0 | 694 void NullCheckVisitor::do_BlockBegin (BlockBegin* x) {} |
695 void NullCheckVisitor::do_Goto (Goto* x) {} | |
696 void NullCheckVisitor::do_If (If* x) {} | |
697 void NullCheckVisitor::do_IfInstanceOf (IfInstanceOf* x) {} | |
698 void NullCheckVisitor::do_TableSwitch (TableSwitch* x) {} | |
699 void NullCheckVisitor::do_LookupSwitch (LookupSwitch* x) {} | |
700 void NullCheckVisitor::do_Return (Return* x) {} | |
701 void NullCheckVisitor::do_Throw (Throw* x) { nce()->clear_last_explicit_null_check(); } | |
702 void NullCheckVisitor::do_Base (Base* x) {} | |
703 void NullCheckVisitor::do_OsrEntry (OsrEntry* x) {} | |
704 void NullCheckVisitor::do_ExceptionObject(ExceptionObject* x) { nce()->handle_ExceptionObject(x); } | |
705 void NullCheckVisitor::do_RoundFP (RoundFP* x) {} | |
706 void NullCheckVisitor::do_UnsafeGetRaw (UnsafeGetRaw* x) {} | |
707 void NullCheckVisitor::do_UnsafePutRaw (UnsafePutRaw* x) {} | |
708 void NullCheckVisitor::do_UnsafeGetObject(UnsafeGetObject* x) {} | |
709 void NullCheckVisitor::do_UnsafePutObject(UnsafePutObject* x) {} | |
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710 void NullCheckVisitor::do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x) {} |
0 | 711 void NullCheckVisitor::do_UnsafePrefetchRead (UnsafePrefetchRead* x) {} |
712 void NullCheckVisitor::do_UnsafePrefetchWrite(UnsafePrefetchWrite* x) {} | |
713 void NullCheckVisitor::do_ProfileCall (ProfileCall* x) { nce()->clear_last_explicit_null_check(); } | |
1783 | 714 void NullCheckVisitor::do_ProfileInvoke (ProfileInvoke* x) {} |
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715 void NullCheckVisitor::do_RuntimeCall (RuntimeCall* x) {} |
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716 void NullCheckVisitor::do_MemBar (MemBar* x) {} |
0 | 717 |
718 | |
1584 | 719 void NullCheckEliminator::visit(Value* p) { |
0 | 720 assert(*p != NULL, "should not find NULL instructions"); |
1584 | 721 if (visitable(*p)) { |
722 mark_visited(*p); | |
723 (*p)->visit(&_visitor); | |
0 | 724 } |
725 } | |
726 | |
727 bool NullCheckEliminator::merge_state_for(BlockBegin* block, ValueSet* incoming_state) { | |
728 ValueSet* state = state_for(block); | |
729 if (state == NULL) { | |
730 state = incoming_state->copy(); | |
731 set_state_for(block, state); | |
732 return true; | |
733 } else { | |
734 bool changed = state->set_intersect(incoming_state); | |
735 if (PrintNullCheckElimination && changed) { | |
736 tty->print_cr("Block %d's null check state changed", block->block_id()); | |
737 } | |
738 return changed; | |
739 } | |
740 } | |
741 | |
742 | |
743 void NullCheckEliminator::iterate_all() { | |
744 while (work_list()->length() > 0) { | |
745 iterate_one(work_list()->pop()); | |
746 } | |
747 } | |
748 | |
749 | |
750 void NullCheckEliminator::iterate_one(BlockBegin* block) { | |
751 clear_visitable_state(); | |
752 // clear out an old explicit null checks | |
753 set_last_explicit_null_check(NULL); | |
754 | |
755 if (PrintNullCheckElimination) { | |
756 tty->print_cr(" ...iterating block %d in null check elimination for %s::%s%s", | |
757 block->block_id(), | |
758 ir()->method()->holder()->name()->as_utf8(), | |
759 ir()->method()->name()->as_utf8(), | |
760 ir()->method()->signature()->as_symbol()->as_utf8()); | |
761 } | |
762 | |
763 // Create new state if none present (only happens at root) | |
764 if (state_for(block) == NULL) { | |
765 ValueSet* tmp_state = new ValueSet(); | |
766 set_state_for(block, tmp_state); | |
767 // Initial state is that local 0 (receiver) is non-null for | |
768 // non-static methods | |
769 ValueStack* stack = block->state(); | |
770 IRScope* scope = stack->scope(); | |
771 ciMethod* method = scope->method(); | |
772 if (!method->is_static()) { | |
773 Local* local0 = stack->local_at(0)->as_Local(); | |
774 assert(local0 != NULL, "must be"); | |
775 assert(local0->type() == objectType, "invalid type of receiver"); | |
776 | |
777 if (local0 != NULL) { | |
778 // Local 0 is used in this scope | |
779 tmp_state->put(local0); | |
780 if (PrintNullCheckElimination) { | |
781 tty->print_cr("Local 0 (value %d) proven non-null upon entry", local0->id()); | |
782 } | |
783 } | |
784 } | |
785 } | |
786 | |
787 // Must copy block's state to avoid mutating it during iteration | |
788 // through the block -- otherwise "not-null" states can accidentally | |
789 // propagate "up" through the block during processing of backward | |
790 // branches and algorithm is incorrect (and does not converge) | |
791 set_state_from(state_for(block)); | |
792 | |
793 // allow visiting of Phis belonging to this block | |
794 for_each_phi_fun(block, phi, | |
795 mark_visitable(phi); | |
796 ); | |
797 | |
798 BlockEnd* e = block->end(); | |
799 assert(e != NULL, "incomplete graph"); | |
800 int i; | |
801 | |
802 // Propagate the state before this block into the exception | |
803 // handlers. They aren't true successors since we aren't guaranteed | |
804 // to execute the whole block before executing them. Also putting | |
805 // them on first seems to help reduce the amount of iteration to | |
806 // reach a fixed point. | |
807 for (i = 0; i < block->number_of_exception_handlers(); i++) { | |
808 BlockBegin* next = block->exception_handler_at(i); | |
809 if (merge_state_for(next, state())) { | |
810 if (!work_list()->contains(next)) { | |
811 work_list()->push(next); | |
812 } | |
813 } | |
814 } | |
815 | |
816 // Iterate through block, updating state. | |
817 for (Instruction* instr = block; instr != NULL; instr = instr->next()) { | |
818 // Mark instructions in this block as visitable as they are seen | |
819 // in the instruction list. This keeps the iteration from | |
820 // visiting instructions which are references in other blocks or | |
821 // visiting instructions more than once. | |
822 mark_visitable(instr); | |
1819 | 823 if (instr->is_pinned() || instr->can_trap() || (instr->as_NullCheck() != NULL)) { |
0 | 824 mark_visited(instr); |
1584 | 825 instr->input_values_do(this); |
0 | 826 instr->visit(&_visitor); |
827 } | |
828 } | |
829 | |
830 // Propagate state to successors if necessary | |
831 for (i = 0; i < e->number_of_sux(); i++) { | |
832 BlockBegin* next = e->sux_at(i); | |
833 if (merge_state_for(next, state())) { | |
834 if (!work_list()->contains(next)) { | |
835 work_list()->push(next); | |
836 } | |
837 } | |
838 } | |
839 } | |
840 | |
841 | |
842 void NullCheckEliminator::iterate(BlockBegin* block) { | |
843 work_list()->push(block); | |
844 iterate_all(); | |
845 } | |
846 | |
847 void NullCheckEliminator::handle_AccessField(AccessField* x) { | |
848 if (x->is_static()) { | |
849 if (x->as_LoadField() != NULL) { | |
850 // If the field is a non-null static final object field (as is | |
851 // often the case for sun.misc.Unsafe), put this LoadField into | |
852 // the non-null map | |
853 ciField* field = x->field(); | |
854 if (field->is_constant()) { | |
855 ciConstant field_val = field->constant_value(); | |
856 BasicType field_type = field_val.basic_type(); | |
857 if (field_type == T_OBJECT || field_type == T_ARRAY) { | |
858 ciObject* obj_val = field_val.as_object(); | |
859 if (!obj_val->is_null_object()) { | |
860 if (PrintNullCheckElimination) { | |
861 tty->print_cr("AccessField %d proven non-null by static final non-null oop check", | |
862 x->id()); | |
863 } | |
864 set_put(x); | |
865 } | |
866 } | |
867 } | |
868 } | |
869 // Be conservative | |
870 clear_last_explicit_null_check(); | |
871 return; | |
872 } | |
873 | |
874 Value obj = x->obj(); | |
875 if (set_contains(obj)) { | |
876 // Value is non-null => update AccessField | |
877 if (last_explicit_null_check_obj() == obj && !x->needs_patching()) { | |
878 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
879 x->set_needs_null_check(true); | |
880 if (PrintNullCheckElimination) { | |
881 tty->print_cr("Folded NullCheck %d into AccessField %d's null check for value %d", | |
882 x->explicit_null_check()->id(), x->id(), obj->id()); | |
883 } | |
884 } else { | |
885 x->set_explicit_null_check(NULL); | |
886 x->set_needs_null_check(false); | |
887 if (PrintNullCheckElimination) { | |
888 tty->print_cr("Eliminated AccessField %d's null check for value %d", x->id(), obj->id()); | |
889 } | |
890 } | |
891 } else { | |
892 set_put(obj); | |
893 if (PrintNullCheckElimination) { | |
894 tty->print_cr("AccessField %d of value %d proves value to be non-null", x->id(), obj->id()); | |
895 } | |
896 // Ensure previous passes do not cause wrong state | |
897 x->set_needs_null_check(true); | |
898 x->set_explicit_null_check(NULL); | |
899 } | |
900 clear_last_explicit_null_check(); | |
901 } | |
902 | |
903 | |
904 void NullCheckEliminator::handle_ArrayLength(ArrayLength* x) { | |
905 Value array = x->array(); | |
906 if (set_contains(array)) { | |
907 // Value is non-null => update AccessArray | |
908 if (last_explicit_null_check_obj() == array) { | |
909 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
910 x->set_needs_null_check(true); | |
911 if (PrintNullCheckElimination) { | |
912 tty->print_cr("Folded NullCheck %d into ArrayLength %d's null check for value %d", | |
913 x->explicit_null_check()->id(), x->id(), array->id()); | |
914 } | |
915 } else { | |
916 x->set_explicit_null_check(NULL); | |
917 x->set_needs_null_check(false); | |
918 if (PrintNullCheckElimination) { | |
919 tty->print_cr("Eliminated ArrayLength %d's null check for value %d", x->id(), array->id()); | |
920 } | |
921 } | |
922 } else { | |
923 set_put(array); | |
924 if (PrintNullCheckElimination) { | |
925 tty->print_cr("ArrayLength %d of value %d proves value to be non-null", x->id(), array->id()); | |
926 } | |
927 // Ensure previous passes do not cause wrong state | |
928 x->set_needs_null_check(true); | |
929 x->set_explicit_null_check(NULL); | |
930 } | |
931 clear_last_explicit_null_check(); | |
932 } | |
933 | |
934 | |
935 void NullCheckEliminator::handle_LoadIndexed(LoadIndexed* x) { | |
936 Value array = x->array(); | |
937 if (set_contains(array)) { | |
938 // Value is non-null => update AccessArray | |
939 if (last_explicit_null_check_obj() == array) { | |
940 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
941 x->set_needs_null_check(true); | |
942 if (PrintNullCheckElimination) { | |
943 tty->print_cr("Folded NullCheck %d into LoadIndexed %d's null check for value %d", | |
944 x->explicit_null_check()->id(), x->id(), array->id()); | |
945 } | |
946 } else { | |
947 x->set_explicit_null_check(NULL); | |
948 x->set_needs_null_check(false); | |
949 if (PrintNullCheckElimination) { | |
950 tty->print_cr("Eliminated LoadIndexed %d's null check for value %d", x->id(), array->id()); | |
951 } | |
952 } | |
953 } else { | |
954 set_put(array); | |
955 if (PrintNullCheckElimination) { | |
956 tty->print_cr("LoadIndexed %d of value %d proves value to be non-null", x->id(), array->id()); | |
957 } | |
958 // Ensure previous passes do not cause wrong state | |
959 x->set_needs_null_check(true); | |
960 x->set_explicit_null_check(NULL); | |
961 } | |
962 clear_last_explicit_null_check(); | |
963 } | |
964 | |
965 | |
966 void NullCheckEliminator::handle_StoreIndexed(StoreIndexed* x) { | |
967 Value array = x->array(); | |
968 if (set_contains(array)) { | |
969 // Value is non-null => update AccessArray | |
970 if (PrintNullCheckElimination) { | |
971 tty->print_cr("Eliminated StoreIndexed %d's null check for value %d", x->id(), array->id()); | |
972 } | |
973 x->set_needs_null_check(false); | |
974 } else { | |
975 set_put(array); | |
976 if (PrintNullCheckElimination) { | |
977 tty->print_cr("StoreIndexed %d of value %d proves value to be non-null", x->id(), array->id()); | |
978 } | |
979 // Ensure previous passes do not cause wrong state | |
980 x->set_needs_null_check(true); | |
981 } | |
982 clear_last_explicit_null_check(); | |
983 } | |
984 | |
985 | |
986 void NullCheckEliminator::handle_NullCheck(NullCheck* x) { | |
987 Value obj = x->obj(); | |
988 if (set_contains(obj)) { | |
989 // Already proven to be non-null => this NullCheck is useless | |
990 if (PrintNullCheckElimination) { | |
991 tty->print_cr("Eliminated NullCheck %d for value %d", x->id(), obj->id()); | |
992 } | |
993 // Don't unpin since that may shrink obj's live range and make it unavailable for debug info. | |
994 // The code generator won't emit LIR for a NullCheck that cannot trap. | |
995 x->set_can_trap(false); | |
996 } else { | |
997 // May be null => add to map and set last explicit NullCheck | |
998 x->set_can_trap(true); | |
999 // make sure it's pinned if it can trap | |
1000 x->pin(Instruction::PinExplicitNullCheck); | |
1001 set_put(obj); | |
1002 set_last_explicit_null_check(x); | |
1003 if (PrintNullCheckElimination) { | |
1004 tty->print_cr("NullCheck %d of value %d proves value to be non-null", x->id(), obj->id()); | |
1005 } | |
1006 } | |
1007 } | |
1008 | |
1009 | |
1010 void NullCheckEliminator::handle_Invoke(Invoke* x) { | |
1011 if (!x->has_receiver()) { | |
1012 // Be conservative | |
1013 clear_last_explicit_null_check(); | |
1014 return; | |
1015 } | |
1016 | |
1017 Value recv = x->receiver(); | |
1018 if (!set_contains(recv)) { | |
1019 set_put(recv); | |
1020 if (PrintNullCheckElimination) { | |
1021 tty->print_cr("Invoke %d of value %d proves value to be non-null", x->id(), recv->id()); | |
1022 } | |
1023 } | |
1024 clear_last_explicit_null_check(); | |
1025 } | |
1026 | |
1027 | |
1028 void NullCheckEliminator::handle_NewInstance(NewInstance* x) { | |
1029 set_put(x); | |
1030 if (PrintNullCheckElimination) { | |
1031 tty->print_cr("NewInstance %d is non-null", x->id()); | |
1032 } | |
1033 } | |
1034 | |
1035 | |
1036 void NullCheckEliminator::handle_NewArray(NewArray* x) { | |
1037 set_put(x); | |
1038 if (PrintNullCheckElimination) { | |
1039 tty->print_cr("NewArray %d is non-null", x->id()); | |
1040 } | |
1041 } | |
1042 | |
1043 | |
1044 void NullCheckEliminator::handle_ExceptionObject(ExceptionObject* x) { | |
1045 set_put(x); | |
1046 if (PrintNullCheckElimination) { | |
1047 tty->print_cr("ExceptionObject %d is non-null", x->id()); | |
1048 } | |
1049 } | |
1050 | |
1051 | |
1052 void NullCheckEliminator::handle_AccessMonitor(AccessMonitor* x) { | |
1053 Value obj = x->obj(); | |
1054 if (set_contains(obj)) { | |
1055 // Value is non-null => update AccessMonitor | |
1056 if (PrintNullCheckElimination) { | |
1057 tty->print_cr("Eliminated AccessMonitor %d's null check for value %d", x->id(), obj->id()); | |
1058 } | |
1059 x->set_needs_null_check(false); | |
1060 } else { | |
1061 set_put(obj); | |
1062 if (PrintNullCheckElimination) { | |
1063 tty->print_cr("AccessMonitor %d of value %d proves value to be non-null", x->id(), obj->id()); | |
1064 } | |
1065 // Ensure previous passes do not cause wrong state | |
1066 x->set_needs_null_check(true); | |
1067 } | |
1068 clear_last_explicit_null_check(); | |
1069 } | |
1070 | |
1071 | |
1072 void NullCheckEliminator::handle_Intrinsic(Intrinsic* x) { | |
1073 if (!x->has_receiver()) { | |
2446 | 1074 if (x->id() == vmIntrinsics::_arraycopy) { |
1075 for (int i = 0; i < x->number_of_arguments(); i++) { | |
1076 x->set_arg_needs_null_check(i, !set_contains(x->argument_at(i))); | |
1077 } | |
1078 } | |
1079 | |
0 | 1080 // Be conservative |
1081 clear_last_explicit_null_check(); | |
1082 return; | |
1083 } | |
1084 | |
1085 Value recv = x->receiver(); | |
1086 if (set_contains(recv)) { | |
1087 // Value is non-null => update Intrinsic | |
1088 if (PrintNullCheckElimination) { | |
1089 tty->print_cr("Eliminated Intrinsic %d's null check for value %d", x->id(), recv->id()); | |
1090 } | |
1091 x->set_needs_null_check(false); | |
1092 } else { | |
1093 set_put(recv); | |
1094 if (PrintNullCheckElimination) { | |
1095 tty->print_cr("Intrinsic %d of value %d proves value to be non-null", x->id(), recv->id()); | |
1096 } | |
1097 // Ensure previous passes do not cause wrong state | |
1098 x->set_needs_null_check(true); | |
1099 } | |
1100 clear_last_explicit_null_check(); | |
1101 } | |
1102 | |
1103 | |
1104 void NullCheckEliminator::handle_Phi(Phi* x) { | |
1105 int i; | |
1106 bool all_non_null = true; | |
1107 if (x->is_illegal()) { | |
1108 all_non_null = false; | |
1109 } else { | |
1110 for (i = 0; i < x->operand_count(); i++) { | |
1111 Value input = x->operand_at(i); | |
1112 if (!set_contains(input)) { | |
1113 all_non_null = false; | |
1114 } | |
1115 } | |
1116 } | |
1117 | |
1118 if (all_non_null) { | |
1119 // Value is non-null => update Phi | |
1120 if (PrintNullCheckElimination) { | |
1121 tty->print_cr("Eliminated Phi %d's null check for phifun because all inputs are non-null", x->id()); | |
1122 } | |
1123 x->set_needs_null_check(false); | |
1124 } else if (set_contains(x)) { | |
1125 set_remove(x); | |
1126 } | |
1127 } | |
1128 | |
1129 | |
1130 void Optimizer::eliminate_null_checks() { | |
1131 ResourceMark rm; | |
1132 | |
1133 NullCheckEliminator nce(this); | |
1134 | |
1135 if (PrintNullCheckElimination) { | |
1136 tty->print_cr("Starting null check elimination for method %s::%s%s", | |
1137 ir()->method()->holder()->name()->as_utf8(), | |
1138 ir()->method()->name()->as_utf8(), | |
1139 ir()->method()->signature()->as_symbol()->as_utf8()); | |
1140 } | |
1141 | |
1142 // Apply to graph | |
1143 nce.iterate(ir()->start()); | |
1144 | |
1145 // walk over the graph looking for exception | |
1146 // handlers and iterate over them as well | |
1147 int nblocks = BlockBegin::number_of_blocks(); | |
1148 BlockList blocks(nblocks); | |
1149 boolArray visited_block(nblocks, false); | |
1150 | |
1151 blocks.push(ir()->start()); | |
1152 visited_block[ir()->start()->block_id()] = true; | |
1153 for (int i = 0; i < blocks.length(); i++) { | |
1154 BlockBegin* b = blocks[i]; | |
1155 // exception handlers need to be treated as additional roots | |
1156 for (int e = b->number_of_exception_handlers(); e-- > 0; ) { | |
1157 BlockBegin* excp = b->exception_handler_at(e); | |
1158 int id = excp->block_id(); | |
1159 if (!visited_block[id]) { | |
1160 blocks.push(excp); | |
1161 visited_block[id] = true; | |
1162 nce.iterate(excp); | |
1163 } | |
1164 } | |
1165 // traverse successors | |
1166 BlockEnd *end = b->end(); | |
1167 for (int s = end->number_of_sux(); s-- > 0; ) { | |
1168 BlockBegin* next = end->sux_at(s); | |
1169 int id = next->block_id(); | |
1170 if (!visited_block[id]) { | |
1171 blocks.push(next); | |
1172 visited_block[id] = true; | |
1173 } | |
1174 } | |
1175 } | |
1176 | |
1177 | |
1178 if (PrintNullCheckElimination) { | |
1179 tty->print_cr("Done with null check elimination for method %s::%s%s", | |
1180 ir()->method()->holder()->name()->as_utf8(), | |
1181 ir()->method()->name()->as_utf8(), | |
1182 ir()->method()->signature()->as_symbol()->as_utf8()); | |
1183 } | |
1184 } |