Mercurial > hg > truffle
annotate src/share/vm/c1/c1_Optimizer.cpp @ 17524:89152779163c
Merge with jdk8-b132
| author | Gilles Duboscq <duboscq@ssw.jku.at> |
|---|---|
| date | Wed, 15 Oct 2014 11:59:32 +0200 |
| parents | 4ca6dc0799b6 |
| children |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 17524 | 2 * Copyright (c) 1999, 2013, 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 | |
| 8860 | 181 Instruction* cur_end = if_->prev(); |
| 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 |
| 8860 | 205 ValueStack* state_before = if_->state_before(); |
| 1899 | 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 | |
| 8860 | 370 Instruction* prev = end->prev(); |
| 0 | 371 Instruction* next = sux->next(); |
| 372 assert(prev->as_BlockEnd() == NULL, "must not be a BlockEnd"); | |
| 1819 | 373 prev->set_next(next); |
| 8860 | 374 prev->fixup_block_pointers(); |
| 0 | 375 sux->disconnect_from_graph(); |
| 376 block->set_end(sux->end()); | |
| 377 // add exception handlers of deleted block, if any | |
| 378 for (int k = 0; k < sux->number_of_exception_handlers(); k++) { | |
| 379 BlockBegin* xhandler = sux->exception_handler_at(k); | |
| 380 block->add_exception_handler(xhandler); | |
| 381 | |
| 382 // also substitute predecessor of exception handler | |
| 383 assert(xhandler->is_predecessor(sux), "missing predecessor"); | |
| 384 xhandler->remove_predecessor(sux); | |
| 385 if (!xhandler->is_predecessor(block)) { | |
| 386 xhandler->add_predecessor(block); | |
| 387 } | |
| 388 } | |
| 389 | |
| 390 // debugging output | |
| 391 _merge_count++; | |
| 392 if (PrintBlockElimination) { | |
| 393 tty->print_cr("%d. merged B%d & B%d (stack size = %d)", | |
| 394 _merge_count, block->block_id(), sux->block_id(), sux->state()->stack_size()); | |
| 395 } | |
| 396 | |
| 397 _hir->verify(); | |
| 398 | |
| 399 If* if_ = block->end()->as_If(); | |
| 400 if (if_) { | |
| 401 IfOp* ifop = if_->x()->as_IfOp(); | |
| 402 Constant* con = if_->y()->as_Constant(); | |
| 403 bool swapped = false; | |
| 404 if (!con || !ifop) { | |
| 405 ifop = if_->y()->as_IfOp(); | |
| 406 con = if_->x()->as_Constant(); | |
| 407 swapped = true; | |
| 408 } | |
| 409 if (con && ifop) { | |
| 410 Constant* tval = ifop->tval()->as_Constant(); | |
| 411 Constant* fval = ifop->fval()->as_Constant(); | |
| 412 if (tval && fval) { | |
| 413 // Find the instruction before if_, starting with ifop. | |
| 414 // When if_ and ifop are not in the same block, prev | |
| 415 // becomes NULL In such (rare) cases it is not | |
| 416 // profitable to perform the optimization. | |
| 417 Value prev = ifop; | |
| 418 while (prev != NULL && prev->next() != if_) { | |
| 419 prev = prev->next(); | |
| 420 } | |
| 421 | |
| 422 if (prev != NULL) { | |
| 423 Instruction::Condition cond = if_->cond(); | |
| 424 BlockBegin* tsux = if_->tsux(); | |
| 425 BlockBegin* fsux = if_->fsux(); | |
| 426 if (swapped) { | |
| 427 cond = Instruction::mirror(cond); | |
| 428 } | |
| 429 | |
| 430 BlockBegin* tblock = tval->compare(cond, con, tsux, fsux); | |
| 431 BlockBegin* fblock = fval->compare(cond, con, tsux, fsux); | |
| 432 if (tblock != fblock && !if_->is_safepoint()) { | |
| 433 If* newif = new If(ifop->x(), ifop->cond(), false, ifop->y(), | |
| 434 tblock, fblock, if_->state_before(), if_->is_safepoint()); | |
| 435 newif->set_state(if_->state()->copy()); | |
| 436 | |
| 437 assert(prev->next() == if_, "must be guaranteed by above search"); | |
| 1819 | 438 NOT_PRODUCT(newif->set_printable_bci(if_->printable_bci())); |
| 439 prev->set_next(newif); | |
| 0 | 440 block->set_end(newif); |
| 441 | |
| 442 _merge_count++; | |
| 443 if (PrintBlockElimination) { | |
| 444 tty->print_cr("%d. replaced If and IfOp at end of B%d with single If", _merge_count, block->block_id()); | |
| 445 } | |
| 446 | |
| 447 _hir->verify(); | |
| 448 } | |
| 449 } | |
| 450 } | |
| 451 } | |
| 452 } | |
| 453 | |
| 454 return true; | |
| 455 } | |
| 456 } | |
| 457 return false; | |
| 458 } | |
| 459 | |
| 460 virtual void block_do(BlockBegin* block) { | |
| 461 _hir->verify(); | |
| 462 // repeat since the same block may merge again | |
| 463 while (try_merge(block)) { | |
| 464 _hir->verify(); | |
| 465 } | |
| 466 } | |
| 467 }; | |
| 468 | |
| 469 | |
| 470 void Optimizer::eliminate_blocks() { | |
| 471 // merge blocks if possible | |
| 472 BlockMerger bm(ir()); | |
| 473 } | |
| 474 | |
| 475 | |
| 476 class NullCheckEliminator; | |
| 477 class NullCheckVisitor: public InstructionVisitor { | |
| 478 private: | |
| 479 NullCheckEliminator* _nce; | |
| 480 NullCheckEliminator* nce() { return _nce; } | |
| 481 | |
| 482 public: | |
| 483 NullCheckVisitor() {} | |
| 484 | |
| 485 void set_eliminator(NullCheckEliminator* nce) { _nce = nce; } | |
| 486 | |
| 487 void do_Phi (Phi* x); | |
| 488 void do_Local (Local* x); | |
| 489 void do_Constant (Constant* x); | |
| 490 void do_LoadField (LoadField* x); | |
| 491 void do_StoreField (StoreField* x); | |
| 492 void do_ArrayLength (ArrayLength* x); | |
| 493 void do_LoadIndexed (LoadIndexed* x); | |
| 494 void do_StoreIndexed (StoreIndexed* x); | |
| 495 void do_NegateOp (NegateOp* x); | |
| 496 void do_ArithmeticOp (ArithmeticOp* x); | |
| 497 void do_ShiftOp (ShiftOp* x); | |
| 498 void do_LogicOp (LogicOp* x); | |
| 499 void do_CompareOp (CompareOp* x); | |
| 500 void do_IfOp (IfOp* x); | |
| 501 void do_Convert (Convert* x); | |
| 502 void do_NullCheck (NullCheck* x); | |
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503 void do_TypeCast (TypeCast* x); |
| 0 | 504 void do_Invoke (Invoke* x); |
| 505 void do_NewInstance (NewInstance* x); | |
| 506 void do_NewTypeArray (NewTypeArray* x); | |
| 507 void do_NewObjectArray (NewObjectArray* x); | |
| 508 void do_NewMultiArray (NewMultiArray* x); | |
| 509 void do_CheckCast (CheckCast* x); | |
| 510 void do_InstanceOf (InstanceOf* x); | |
| 511 void do_MonitorEnter (MonitorEnter* x); | |
| 512 void do_MonitorExit (MonitorExit* x); | |
| 513 void do_Intrinsic (Intrinsic* x); | |
| 514 void do_BlockBegin (BlockBegin* x); | |
| 515 void do_Goto (Goto* x); | |
| 516 void do_If (If* x); | |
| 517 void do_IfInstanceOf (IfInstanceOf* x); | |
| 518 void do_TableSwitch (TableSwitch* x); | |
| 519 void do_LookupSwitch (LookupSwitch* x); | |
| 520 void do_Return (Return* x); | |
| 521 void do_Throw (Throw* x); | |
| 522 void do_Base (Base* x); | |
| 523 void do_OsrEntry (OsrEntry* x); | |
| 524 void do_ExceptionObject(ExceptionObject* x); | |
| 525 void do_RoundFP (RoundFP* x); | |
| 526 void do_UnsafeGetRaw (UnsafeGetRaw* x); | |
| 527 void do_UnsafePutRaw (UnsafePutRaw* x); | |
| 528 void do_UnsafeGetObject(UnsafeGetObject* x); | |
| 529 void do_UnsafePutObject(UnsafePutObject* x); | |
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530 void do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x); |
| 0 | 531 void do_UnsafePrefetchRead (UnsafePrefetchRead* x); |
| 532 void do_UnsafePrefetchWrite(UnsafePrefetchWrite* x); | |
| 533 void do_ProfileCall (ProfileCall* x); | |
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534 void do_ProfileReturnType (ProfileReturnType* x); |
| 1783 | 535 void do_ProfileInvoke (ProfileInvoke* x); |
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536 void do_RuntimeCall (RuntimeCall* x); |
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537 void do_MemBar (MemBar* x); |
| 8860 | 538 void do_RangeCheckPredicate(RangeCheckPredicate* x); |
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539 #ifdef ASSERT |
| 8860 | 540 void do_Assert (Assert* x); |
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541 #endif |
| 0 | 542 }; |
| 543 | |
| 544 | |
| 545 // Because of a static contained within (for the purpose of iteration | |
| 546 // over instructions), it is only valid to have one of these active at | |
| 547 // a time | |
| 1584 | 548 class NullCheckEliminator: public ValueVisitor { |
| 0 | 549 private: |
| 550 Optimizer* _opt; | |
| 551 | |
| 552 ValueSet* _visitable_instructions; // Visit each instruction only once per basic block | |
| 553 BlockList* _work_list; // Basic blocks to visit | |
| 554 | |
| 555 bool visitable(Value x) { | |
| 556 assert(_visitable_instructions != NULL, "check"); | |
| 557 return _visitable_instructions->contains(x); | |
| 558 } | |
| 559 void mark_visited(Value x) { | |
| 560 assert(_visitable_instructions != NULL, "check"); | |
| 561 _visitable_instructions->remove(x); | |
| 562 } | |
| 563 void mark_visitable(Value x) { | |
| 564 assert(_visitable_instructions != NULL, "check"); | |
| 565 _visitable_instructions->put(x); | |
| 566 } | |
| 567 void clear_visitable_state() { | |
| 568 assert(_visitable_instructions != NULL, "check"); | |
| 569 _visitable_instructions->clear(); | |
| 570 } | |
| 571 | |
| 572 ValueSet* _set; // current state, propagated to subsequent BlockBegins | |
| 573 ValueSetList _block_states; // BlockBegin null-check states for all processed blocks | |
| 574 NullCheckVisitor _visitor; | |
| 575 NullCheck* _last_explicit_null_check; | |
| 576 | |
| 577 bool set_contains(Value x) { assert(_set != NULL, "check"); return _set->contains(x); } | |
| 578 void set_put (Value x) { assert(_set != NULL, "check"); _set->put(x); } | |
| 579 void set_remove (Value x) { assert(_set != NULL, "check"); _set->remove(x); } | |
| 580 | |
| 581 BlockList* work_list() { return _work_list; } | |
| 582 | |
| 583 void iterate_all(); | |
| 584 void iterate_one(BlockBegin* block); | |
| 585 | |
| 586 ValueSet* state() { return _set; } | |
| 587 void set_state_from (ValueSet* state) { _set->set_from(state); } | |
| 588 ValueSet* state_for (BlockBegin* block) { return _block_states[block->block_id()]; } | |
| 589 void set_state_for (BlockBegin* block, ValueSet* stack) { _block_states[block->block_id()] = stack; } | |
| 590 // Returns true if caused a change in the block's state. | |
| 591 bool merge_state_for(BlockBegin* block, | |
| 592 ValueSet* incoming_state); | |
| 593 | |
| 594 public: | |
| 595 // constructor | |
| 596 NullCheckEliminator(Optimizer* opt) | |
| 597 : _opt(opt) | |
| 598 , _set(new ValueSet()) | |
| 599 , _last_explicit_null_check(NULL) | |
| 600 , _block_states(BlockBegin::number_of_blocks(), NULL) | |
| 601 , _work_list(new BlockList()) { | |
| 602 _visitable_instructions = new ValueSet(); | |
| 603 _visitor.set_eliminator(this); | |
| 6843 | 604 CompileLog* log = _opt->ir()->compilation()->log(); |
| 605 if (log != NULL) | |
| 606 log->set_context("optimize name='null_check_elimination'"); | |
| 607 } | |
| 608 | |
| 609 ~NullCheckEliminator() { | |
| 610 CompileLog* log = _opt->ir()->compilation()->log(); | |
| 611 if (log != NULL) | |
| 612 log->clear_context(); // skip marker if nothing was printed | |
| 0 | 613 } |
| 614 | |
| 615 Optimizer* opt() { return _opt; } | |
| 616 IR* ir () { return opt()->ir(); } | |
| 617 | |
| 618 // Process a graph | |
| 619 void iterate(BlockBegin* root); | |
| 620 | |
| 1584 | 621 void visit(Value* f); |
| 622 | |
| 0 | 623 // In some situations (like NullCheck(x); getfield(x)) the debug |
| 624 // information from the explicit NullCheck can be used to populate | |
| 625 // the getfield, even if the two instructions are in different | |
| 626 // scopes; this allows implicit null checks to be used but the | |
| 627 // correct exception information to be generated. We must clear the | |
| 628 // last-traversed NullCheck when we reach a potentially-exception- | |
| 629 // throwing instruction, as well as in some other cases. | |
| 630 void set_last_explicit_null_check(NullCheck* check) { _last_explicit_null_check = check; } | |
| 631 NullCheck* last_explicit_null_check() { return _last_explicit_null_check; } | |
| 632 Value last_explicit_null_check_obj() { return (_last_explicit_null_check | |
| 633 ? _last_explicit_null_check->obj() | |
| 634 : NULL); } | |
| 635 NullCheck* consume_last_explicit_null_check() { | |
| 636 _last_explicit_null_check->unpin(Instruction::PinExplicitNullCheck); | |
| 637 _last_explicit_null_check->set_can_trap(false); | |
| 638 return _last_explicit_null_check; | |
| 639 } | |
| 640 void clear_last_explicit_null_check() { _last_explicit_null_check = NULL; } | |
| 641 | |
| 642 // Handlers for relevant instructions | |
| 643 // (separated out from NullCheckVisitor for clarity) | |
| 644 | |
| 645 // The basic contract is that these must leave the instruction in | |
| 646 // the desired state; must not assume anything about the state of | |
| 647 // the instruction. We make multiple passes over some basic blocks | |
| 648 // and the last pass is the only one whose result is valid. | |
| 649 void handle_AccessField (AccessField* x); | |
| 650 void handle_ArrayLength (ArrayLength* x); | |
| 651 void handle_LoadIndexed (LoadIndexed* x); | |
| 652 void handle_StoreIndexed (StoreIndexed* x); | |
| 653 void handle_NullCheck (NullCheck* x); | |
| 654 void handle_Invoke (Invoke* x); | |
| 655 void handle_NewInstance (NewInstance* x); | |
| 656 void handle_NewArray (NewArray* x); | |
| 657 void handle_AccessMonitor (AccessMonitor* x); | |
| 658 void handle_Intrinsic (Intrinsic* x); | |
| 659 void handle_ExceptionObject (ExceptionObject* x); | |
| 660 void handle_Phi (Phi* x); | |
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661 void handle_ProfileCall (ProfileCall* x); |
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662 void handle_ProfileReturnType (ProfileReturnType* x); |
| 0 | 663 }; |
| 664 | |
| 665 | |
| 666 // NEEDS_CLEANUP | |
| 667 // There may be other instructions which need to clear the last | |
| 668 // explicit null check. Anything across which we can not hoist the | |
| 669 // debug information for a NullCheck instruction must clear it. It | |
| 670 // might be safer to pattern match "NullCheck ; {AccessField, | |
| 671 // ArrayLength, LoadIndexed}" but it is more easily structured this way. | |
| 672 // Should test to see performance hit of clearing it for all handlers | |
| 673 // with empty bodies below. If it is negligible then we should leave | |
| 674 // that in for safety, otherwise should think more about it. | |
| 675 void NullCheckVisitor::do_Phi (Phi* x) { nce()->handle_Phi(x); } | |
| 676 void NullCheckVisitor::do_Local (Local* x) {} | |
| 677 void NullCheckVisitor::do_Constant (Constant* x) { /* FIXME: handle object constants */ } | |
| 678 void NullCheckVisitor::do_LoadField (LoadField* x) { nce()->handle_AccessField(x); } | |
| 679 void NullCheckVisitor::do_StoreField (StoreField* x) { nce()->handle_AccessField(x); } | |
| 680 void NullCheckVisitor::do_ArrayLength (ArrayLength* x) { nce()->handle_ArrayLength(x); } | |
| 681 void NullCheckVisitor::do_LoadIndexed (LoadIndexed* x) { nce()->handle_LoadIndexed(x); } | |
| 682 void NullCheckVisitor::do_StoreIndexed (StoreIndexed* x) { nce()->handle_StoreIndexed(x); } | |
| 683 void NullCheckVisitor::do_NegateOp (NegateOp* x) {} | |
| 684 void NullCheckVisitor::do_ArithmeticOp (ArithmeticOp* x) { if (x->can_trap()) nce()->clear_last_explicit_null_check(); } | |
| 685 void NullCheckVisitor::do_ShiftOp (ShiftOp* x) {} | |
| 686 void NullCheckVisitor::do_LogicOp (LogicOp* x) {} | |
| 687 void NullCheckVisitor::do_CompareOp (CompareOp* x) {} | |
| 688 void NullCheckVisitor::do_IfOp (IfOp* x) {} | |
| 689 void NullCheckVisitor::do_Convert (Convert* x) {} | |
| 690 void NullCheckVisitor::do_NullCheck (NullCheck* x) { nce()->handle_NullCheck(x); } | |
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691 void NullCheckVisitor::do_TypeCast (TypeCast* x) {} |
| 0 | 692 void NullCheckVisitor::do_Invoke (Invoke* x) { nce()->handle_Invoke(x); } |
| 693 void NullCheckVisitor::do_NewInstance (NewInstance* x) { nce()->handle_NewInstance(x); } | |
| 694 void NullCheckVisitor::do_NewTypeArray (NewTypeArray* x) { nce()->handle_NewArray(x); } | |
| 695 void NullCheckVisitor::do_NewObjectArray (NewObjectArray* x) { nce()->handle_NewArray(x); } | |
| 696 void NullCheckVisitor::do_NewMultiArray (NewMultiArray* x) { nce()->handle_NewArray(x); } | |
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697 void NullCheckVisitor::do_CheckCast (CheckCast* x) { nce()->clear_last_explicit_null_check(); } |
| 0 | 698 void NullCheckVisitor::do_InstanceOf (InstanceOf* x) {} |
| 699 void NullCheckVisitor::do_MonitorEnter (MonitorEnter* x) { nce()->handle_AccessMonitor(x); } | |
| 700 void NullCheckVisitor::do_MonitorExit (MonitorExit* x) { nce()->handle_AccessMonitor(x); } | |
| 2446 | 701 void NullCheckVisitor::do_Intrinsic (Intrinsic* x) { nce()->handle_Intrinsic(x); } |
| 0 | 702 void NullCheckVisitor::do_BlockBegin (BlockBegin* x) {} |
| 703 void NullCheckVisitor::do_Goto (Goto* x) {} | |
| 704 void NullCheckVisitor::do_If (If* x) {} | |
| 705 void NullCheckVisitor::do_IfInstanceOf (IfInstanceOf* x) {} | |
| 706 void NullCheckVisitor::do_TableSwitch (TableSwitch* x) {} | |
| 707 void NullCheckVisitor::do_LookupSwitch (LookupSwitch* x) {} | |
| 708 void NullCheckVisitor::do_Return (Return* x) {} | |
| 709 void NullCheckVisitor::do_Throw (Throw* x) { nce()->clear_last_explicit_null_check(); } | |
| 710 void NullCheckVisitor::do_Base (Base* x) {} | |
| 711 void NullCheckVisitor::do_OsrEntry (OsrEntry* x) {} | |
| 712 void NullCheckVisitor::do_ExceptionObject(ExceptionObject* x) { nce()->handle_ExceptionObject(x); } | |
| 713 void NullCheckVisitor::do_RoundFP (RoundFP* x) {} | |
| 714 void NullCheckVisitor::do_UnsafeGetRaw (UnsafeGetRaw* x) {} | |
| 715 void NullCheckVisitor::do_UnsafePutRaw (UnsafePutRaw* x) {} | |
| 716 void NullCheckVisitor::do_UnsafeGetObject(UnsafeGetObject* x) {} | |
| 717 void NullCheckVisitor::do_UnsafePutObject(UnsafePutObject* x) {} | |
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718 void NullCheckVisitor::do_UnsafeGetAndSetObject(UnsafeGetAndSetObject* x) {} |
| 0 | 719 void NullCheckVisitor::do_UnsafePrefetchRead (UnsafePrefetchRead* x) {} |
| 720 void NullCheckVisitor::do_UnsafePrefetchWrite(UnsafePrefetchWrite* x) {} | |
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721 void NullCheckVisitor::do_ProfileCall (ProfileCall* x) { nce()->clear_last_explicit_null_check(); |
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722 nce()->handle_ProfileCall(x); } |
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723 void NullCheckVisitor::do_ProfileReturnType (ProfileReturnType* x) { nce()->handle_ProfileReturnType(x); } |
| 1783 | 724 void NullCheckVisitor::do_ProfileInvoke (ProfileInvoke* x) {} |
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725 void NullCheckVisitor::do_RuntimeCall (RuntimeCall* x) {} |
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726 void NullCheckVisitor::do_MemBar (MemBar* x) {} |
| 8860 | 727 void NullCheckVisitor::do_RangeCheckPredicate(RangeCheckPredicate* x) {} |
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728 #ifdef ASSERT |
| 8860 | 729 void NullCheckVisitor::do_Assert (Assert* x) {} |
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730 #endif |
| 0 | 731 |
| 1584 | 732 void NullCheckEliminator::visit(Value* p) { |
| 0 | 733 assert(*p != NULL, "should not find NULL instructions"); |
| 1584 | 734 if (visitable(*p)) { |
| 735 mark_visited(*p); | |
| 736 (*p)->visit(&_visitor); | |
| 0 | 737 } |
| 738 } | |
| 739 | |
| 740 bool NullCheckEliminator::merge_state_for(BlockBegin* block, ValueSet* incoming_state) { | |
| 741 ValueSet* state = state_for(block); | |
| 742 if (state == NULL) { | |
| 743 state = incoming_state->copy(); | |
| 744 set_state_for(block, state); | |
| 745 return true; | |
| 746 } else { | |
| 747 bool changed = state->set_intersect(incoming_state); | |
| 748 if (PrintNullCheckElimination && changed) { | |
| 749 tty->print_cr("Block %d's null check state changed", block->block_id()); | |
| 750 } | |
| 751 return changed; | |
| 752 } | |
| 753 } | |
| 754 | |
| 755 | |
| 756 void NullCheckEliminator::iterate_all() { | |
| 757 while (work_list()->length() > 0) { | |
| 758 iterate_one(work_list()->pop()); | |
| 759 } | |
| 760 } | |
| 761 | |
| 762 | |
| 763 void NullCheckEliminator::iterate_one(BlockBegin* block) { | |
| 764 clear_visitable_state(); | |
| 765 // clear out an old explicit null checks | |
| 766 set_last_explicit_null_check(NULL); | |
| 767 | |
| 768 if (PrintNullCheckElimination) { | |
| 769 tty->print_cr(" ...iterating block %d in null check elimination for %s::%s%s", | |
| 770 block->block_id(), | |
| 771 ir()->method()->holder()->name()->as_utf8(), | |
| 772 ir()->method()->name()->as_utf8(), | |
| 773 ir()->method()->signature()->as_symbol()->as_utf8()); | |
| 774 } | |
| 775 | |
| 776 // Create new state if none present (only happens at root) | |
| 777 if (state_for(block) == NULL) { | |
| 778 ValueSet* tmp_state = new ValueSet(); | |
| 779 set_state_for(block, tmp_state); | |
| 780 // Initial state is that local 0 (receiver) is non-null for | |
| 781 // non-static methods | |
| 782 ValueStack* stack = block->state(); | |
| 783 IRScope* scope = stack->scope(); | |
| 784 ciMethod* method = scope->method(); | |
| 785 if (!method->is_static()) { | |
| 786 Local* local0 = stack->local_at(0)->as_Local(); | |
| 787 assert(local0 != NULL, "must be"); | |
| 788 assert(local0->type() == objectType, "invalid type of receiver"); | |
| 789 | |
| 790 if (local0 != NULL) { | |
| 791 // Local 0 is used in this scope | |
| 792 tmp_state->put(local0); | |
| 793 if (PrintNullCheckElimination) { | |
| 794 tty->print_cr("Local 0 (value %d) proven non-null upon entry", local0->id()); | |
| 795 } | |
| 796 } | |
| 797 } | |
| 798 } | |
| 799 | |
| 800 // Must copy block's state to avoid mutating it during iteration | |
| 801 // through the block -- otherwise "not-null" states can accidentally | |
| 802 // propagate "up" through the block during processing of backward | |
| 803 // branches and algorithm is incorrect (and does not converge) | |
| 804 set_state_from(state_for(block)); | |
| 805 | |
| 806 // allow visiting of Phis belonging to this block | |
| 807 for_each_phi_fun(block, phi, | |
| 808 mark_visitable(phi); | |
| 809 ); | |
| 810 | |
| 811 BlockEnd* e = block->end(); | |
| 812 assert(e != NULL, "incomplete graph"); | |
| 813 int i; | |
| 814 | |
| 815 // Propagate the state before this block into the exception | |
| 816 // handlers. They aren't true successors since we aren't guaranteed | |
| 817 // to execute the whole block before executing them. Also putting | |
| 818 // them on first seems to help reduce the amount of iteration to | |
| 819 // reach a fixed point. | |
| 820 for (i = 0; i < block->number_of_exception_handlers(); i++) { | |
| 821 BlockBegin* next = block->exception_handler_at(i); | |
| 822 if (merge_state_for(next, state())) { | |
| 823 if (!work_list()->contains(next)) { | |
| 824 work_list()->push(next); | |
| 825 } | |
| 826 } | |
| 827 } | |
| 828 | |
| 829 // Iterate through block, updating state. | |
| 830 for (Instruction* instr = block; instr != NULL; instr = instr->next()) { | |
| 831 // Mark instructions in this block as visitable as they are seen | |
| 832 // in the instruction list. This keeps the iteration from | |
| 833 // visiting instructions which are references in other blocks or | |
| 834 // visiting instructions more than once. | |
| 835 mark_visitable(instr); | |
| 1819 | 836 if (instr->is_pinned() || instr->can_trap() || (instr->as_NullCheck() != NULL)) { |
| 0 | 837 mark_visited(instr); |
| 1584 | 838 instr->input_values_do(this); |
| 0 | 839 instr->visit(&_visitor); |
| 840 } | |
| 841 } | |
| 842 | |
| 843 // Propagate state to successors if necessary | |
| 844 for (i = 0; i < e->number_of_sux(); i++) { | |
| 845 BlockBegin* next = e->sux_at(i); | |
| 846 if (merge_state_for(next, state())) { | |
| 847 if (!work_list()->contains(next)) { | |
| 848 work_list()->push(next); | |
| 849 } | |
| 850 } | |
| 851 } | |
| 852 } | |
| 853 | |
| 854 | |
| 855 void NullCheckEliminator::iterate(BlockBegin* block) { | |
| 856 work_list()->push(block); | |
| 857 iterate_all(); | |
| 858 } | |
| 859 | |
| 860 void NullCheckEliminator::handle_AccessField(AccessField* x) { | |
| 861 if (x->is_static()) { | |
| 862 if (x->as_LoadField() != NULL) { | |
| 863 // If the field is a non-null static final object field (as is | |
| 864 // often the case for sun.misc.Unsafe), put this LoadField into | |
| 865 // the non-null map | |
| 866 ciField* field = x->field(); | |
| 867 if (field->is_constant()) { | |
| 868 ciConstant field_val = field->constant_value(); | |
| 869 BasicType field_type = field_val.basic_type(); | |
| 870 if (field_type == T_OBJECT || field_type == T_ARRAY) { | |
| 871 ciObject* obj_val = field_val.as_object(); | |
| 872 if (!obj_val->is_null_object()) { | |
| 873 if (PrintNullCheckElimination) { | |
| 874 tty->print_cr("AccessField %d proven non-null by static final non-null oop check", | |
| 875 x->id()); | |
| 876 } | |
| 877 set_put(x); | |
| 878 } | |
| 879 } | |
| 880 } | |
| 881 } | |
| 882 // Be conservative | |
| 883 clear_last_explicit_null_check(); | |
| 884 return; | |
| 885 } | |
| 886 | |
| 887 Value obj = x->obj(); | |
| 888 if (set_contains(obj)) { | |
| 889 // Value is non-null => update AccessField | |
| 890 if (last_explicit_null_check_obj() == obj && !x->needs_patching()) { | |
| 891 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
| 892 x->set_needs_null_check(true); | |
| 893 if (PrintNullCheckElimination) { | |
| 894 tty->print_cr("Folded NullCheck %d into AccessField %d's null check for value %d", | |
| 895 x->explicit_null_check()->id(), x->id(), obj->id()); | |
| 896 } | |
| 897 } else { | |
| 898 x->set_explicit_null_check(NULL); | |
| 899 x->set_needs_null_check(false); | |
| 900 if (PrintNullCheckElimination) { | |
| 901 tty->print_cr("Eliminated AccessField %d's null check for value %d", x->id(), obj->id()); | |
| 902 } | |
| 903 } | |
| 904 } else { | |
| 905 set_put(obj); | |
| 906 if (PrintNullCheckElimination) { | |
| 907 tty->print_cr("AccessField %d of value %d proves value to be non-null", x->id(), obj->id()); | |
| 908 } | |
| 909 // Ensure previous passes do not cause wrong state | |
| 910 x->set_needs_null_check(true); | |
| 911 x->set_explicit_null_check(NULL); | |
| 912 } | |
| 913 clear_last_explicit_null_check(); | |
| 914 } | |
| 915 | |
| 916 | |
| 917 void NullCheckEliminator::handle_ArrayLength(ArrayLength* x) { | |
| 918 Value array = x->array(); | |
| 919 if (set_contains(array)) { | |
| 920 // Value is non-null => update AccessArray | |
| 921 if (last_explicit_null_check_obj() == array) { | |
| 922 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
| 923 x->set_needs_null_check(true); | |
| 924 if (PrintNullCheckElimination) { | |
| 925 tty->print_cr("Folded NullCheck %d into ArrayLength %d's null check for value %d", | |
| 926 x->explicit_null_check()->id(), x->id(), array->id()); | |
| 927 } | |
| 928 } else { | |
| 929 x->set_explicit_null_check(NULL); | |
| 930 x->set_needs_null_check(false); | |
| 931 if (PrintNullCheckElimination) { | |
| 932 tty->print_cr("Eliminated ArrayLength %d's null check for value %d", x->id(), array->id()); | |
| 933 } | |
| 934 } | |
| 935 } else { | |
| 936 set_put(array); | |
| 937 if (PrintNullCheckElimination) { | |
| 938 tty->print_cr("ArrayLength %d of value %d proves value to be non-null", x->id(), array->id()); | |
| 939 } | |
| 940 // Ensure previous passes do not cause wrong state | |
| 941 x->set_needs_null_check(true); | |
| 942 x->set_explicit_null_check(NULL); | |
| 943 } | |
| 944 clear_last_explicit_null_check(); | |
| 945 } | |
| 946 | |
| 947 | |
| 948 void NullCheckEliminator::handle_LoadIndexed(LoadIndexed* x) { | |
| 949 Value array = x->array(); | |
| 950 if (set_contains(array)) { | |
| 951 // Value is non-null => update AccessArray | |
| 952 if (last_explicit_null_check_obj() == array) { | |
| 953 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
| 954 x->set_needs_null_check(true); | |
| 955 if (PrintNullCheckElimination) { | |
| 956 tty->print_cr("Folded NullCheck %d into LoadIndexed %d's null check for value %d", | |
| 957 x->explicit_null_check()->id(), x->id(), array->id()); | |
| 958 } | |
| 959 } else { | |
| 960 x->set_explicit_null_check(NULL); | |
| 961 x->set_needs_null_check(false); | |
| 962 if (PrintNullCheckElimination) { | |
| 963 tty->print_cr("Eliminated LoadIndexed %d's null check for value %d", x->id(), array->id()); | |
| 964 } | |
| 965 } | |
| 966 } else { | |
| 967 set_put(array); | |
| 968 if (PrintNullCheckElimination) { | |
| 969 tty->print_cr("LoadIndexed %d of value %d proves value to be non-null", x->id(), array->id()); | |
| 970 } | |
| 971 // Ensure previous passes do not cause wrong state | |
| 972 x->set_needs_null_check(true); | |
| 973 x->set_explicit_null_check(NULL); | |
| 974 } | |
| 975 clear_last_explicit_null_check(); | |
| 976 } | |
| 977 | |
| 978 | |
| 979 void NullCheckEliminator::handle_StoreIndexed(StoreIndexed* x) { | |
| 980 Value array = x->array(); | |
| 981 if (set_contains(array)) { | |
| 982 // Value is non-null => update AccessArray | |
| 983 if (PrintNullCheckElimination) { | |
| 984 tty->print_cr("Eliminated StoreIndexed %d's null check for value %d", x->id(), array->id()); | |
| 985 } | |
| 986 x->set_needs_null_check(false); | |
| 987 } else { | |
| 988 set_put(array); | |
| 989 if (PrintNullCheckElimination) { | |
| 990 tty->print_cr("StoreIndexed %d of value %d proves value to be non-null", x->id(), array->id()); | |
| 991 } | |
| 992 // Ensure previous passes do not cause wrong state | |
| 993 x->set_needs_null_check(true); | |
| 994 } | |
| 995 clear_last_explicit_null_check(); | |
| 996 } | |
| 997 | |
| 998 | |
| 999 void NullCheckEliminator::handle_NullCheck(NullCheck* x) { | |
| 1000 Value obj = x->obj(); | |
| 1001 if (set_contains(obj)) { | |
| 1002 // Already proven to be non-null => this NullCheck is useless | |
| 1003 if (PrintNullCheckElimination) { | |
| 1004 tty->print_cr("Eliminated NullCheck %d for value %d", x->id(), obj->id()); | |
| 1005 } | |
| 1006 // Don't unpin since that may shrink obj's live range and make it unavailable for debug info. | |
| 1007 // The code generator won't emit LIR for a NullCheck that cannot trap. | |
| 1008 x->set_can_trap(false); | |
| 1009 } else { | |
| 1010 // May be null => add to map and set last explicit NullCheck | |
| 1011 x->set_can_trap(true); | |
| 1012 // make sure it's pinned if it can trap | |
| 1013 x->pin(Instruction::PinExplicitNullCheck); | |
| 1014 set_put(obj); | |
| 1015 set_last_explicit_null_check(x); | |
| 1016 if (PrintNullCheckElimination) { | |
| 1017 tty->print_cr("NullCheck %d of value %d proves value to be non-null", x->id(), obj->id()); | |
| 1018 } | |
| 1019 } | |
| 1020 } | |
| 1021 | |
| 1022 | |
| 1023 void NullCheckEliminator::handle_Invoke(Invoke* x) { | |
| 1024 if (!x->has_receiver()) { | |
| 1025 // Be conservative | |
| 1026 clear_last_explicit_null_check(); | |
| 1027 return; | |
| 1028 } | |
| 1029 | |
| 1030 Value recv = x->receiver(); | |
| 1031 if (!set_contains(recv)) { | |
| 1032 set_put(recv); | |
| 1033 if (PrintNullCheckElimination) { | |
| 1034 tty->print_cr("Invoke %d of value %d proves value to be non-null", x->id(), recv->id()); | |
| 1035 } | |
| 1036 } | |
| 1037 clear_last_explicit_null_check(); | |
| 1038 } | |
| 1039 | |
| 1040 | |
| 1041 void NullCheckEliminator::handle_NewInstance(NewInstance* x) { | |
| 1042 set_put(x); | |
| 1043 if (PrintNullCheckElimination) { | |
| 1044 tty->print_cr("NewInstance %d is non-null", x->id()); | |
| 1045 } | |
| 1046 } | |
| 1047 | |
| 1048 | |
| 1049 void NullCheckEliminator::handle_NewArray(NewArray* x) { | |
| 1050 set_put(x); | |
| 1051 if (PrintNullCheckElimination) { | |
| 1052 tty->print_cr("NewArray %d is non-null", x->id()); | |
| 1053 } | |
| 1054 } | |
| 1055 | |
| 1056 | |
| 1057 void NullCheckEliminator::handle_ExceptionObject(ExceptionObject* x) { | |
| 1058 set_put(x); | |
| 1059 if (PrintNullCheckElimination) { | |
| 1060 tty->print_cr("ExceptionObject %d is non-null", x->id()); | |
| 1061 } | |
| 1062 } | |
| 1063 | |
| 1064 | |
| 1065 void NullCheckEliminator::handle_AccessMonitor(AccessMonitor* x) { | |
| 1066 Value obj = x->obj(); | |
| 1067 if (set_contains(obj)) { | |
| 1068 // Value is non-null => update AccessMonitor | |
| 1069 if (PrintNullCheckElimination) { | |
| 1070 tty->print_cr("Eliminated AccessMonitor %d's null check for value %d", x->id(), obj->id()); | |
| 1071 } | |
| 1072 x->set_needs_null_check(false); | |
| 1073 } else { | |
| 1074 set_put(obj); | |
| 1075 if (PrintNullCheckElimination) { | |
| 1076 tty->print_cr("AccessMonitor %d of value %d proves value to be non-null", x->id(), obj->id()); | |
| 1077 } | |
| 1078 // Ensure previous passes do not cause wrong state | |
| 1079 x->set_needs_null_check(true); | |
| 1080 } | |
| 1081 clear_last_explicit_null_check(); | |
| 1082 } | |
| 1083 | |
| 1084 | |
| 1085 void NullCheckEliminator::handle_Intrinsic(Intrinsic* x) { | |
| 1086 if (!x->has_receiver()) { | |
| 2446 | 1087 if (x->id() == vmIntrinsics::_arraycopy) { |
| 1088 for (int i = 0; i < x->number_of_arguments(); i++) { | |
| 1089 x->set_arg_needs_null_check(i, !set_contains(x->argument_at(i))); | |
| 1090 } | |
| 1091 } | |
| 1092 | |
| 0 | 1093 // Be conservative |
| 1094 clear_last_explicit_null_check(); | |
| 1095 return; | |
| 1096 } | |
| 1097 | |
| 1098 Value recv = x->receiver(); | |
| 1099 if (set_contains(recv)) { | |
| 1100 // Value is non-null => update Intrinsic | |
| 1101 if (PrintNullCheckElimination) { | |
| 1102 tty->print_cr("Eliminated Intrinsic %d's null check for value %d", x->id(), recv->id()); | |
| 1103 } | |
| 1104 x->set_needs_null_check(false); | |
| 1105 } else { | |
| 1106 set_put(recv); | |
| 1107 if (PrintNullCheckElimination) { | |
| 1108 tty->print_cr("Intrinsic %d of value %d proves value to be non-null", x->id(), recv->id()); | |
| 1109 } | |
| 1110 // Ensure previous passes do not cause wrong state | |
| 1111 x->set_needs_null_check(true); | |
| 1112 } | |
| 1113 clear_last_explicit_null_check(); | |
| 1114 } | |
| 1115 | |
| 1116 | |
| 1117 void NullCheckEliminator::handle_Phi(Phi* x) { | |
| 1118 int i; | |
| 1119 bool all_non_null = true; | |
| 1120 if (x->is_illegal()) { | |
| 1121 all_non_null = false; | |
| 1122 } else { | |
| 1123 for (i = 0; i < x->operand_count(); i++) { | |
| 1124 Value input = x->operand_at(i); | |
| 1125 if (!set_contains(input)) { | |
| 1126 all_non_null = false; | |
| 1127 } | |
| 1128 } | |
| 1129 } | |
| 1130 | |
| 1131 if (all_non_null) { | |
| 1132 // Value is non-null => update Phi | |
| 1133 if (PrintNullCheckElimination) { | |
| 1134 tty->print_cr("Eliminated Phi %d's null check for phifun because all inputs are non-null", x->id()); | |
| 1135 } | |
| 1136 x->set_needs_null_check(false); | |
| 1137 } else if (set_contains(x)) { | |
| 1138 set_remove(x); | |
| 1139 } | |
| 1140 } | |
| 1141 | |
|
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1142 void NullCheckEliminator::handle_ProfileCall(ProfileCall* x) { |
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1143 for (int i = 0; i < x->nb_profiled_args(); i++) { |
|
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1144 x->set_arg_needs_null_check(i, !set_contains(x->profiled_arg_at(i))); |
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1145 } |
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1146 } |
| 0 | 1147 |
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1148 void NullCheckEliminator::handle_ProfileReturnType(ProfileReturnType* x) { |
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1149 x->set_needs_null_check(!set_contains(x->ret())); |
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1150 } |
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1151 |
| 0 | 1152 void Optimizer::eliminate_null_checks() { |
| 1153 ResourceMark rm; | |
| 1154 | |
| 1155 NullCheckEliminator nce(this); | |
| 1156 | |
| 1157 if (PrintNullCheckElimination) { | |
| 1158 tty->print_cr("Starting null check elimination for method %s::%s%s", | |
| 1159 ir()->method()->holder()->name()->as_utf8(), | |
| 1160 ir()->method()->name()->as_utf8(), | |
| 1161 ir()->method()->signature()->as_symbol()->as_utf8()); | |
| 1162 } | |
| 1163 | |
| 1164 // Apply to graph | |
| 1165 nce.iterate(ir()->start()); | |
| 1166 | |
| 1167 // walk over the graph looking for exception | |
| 1168 // handlers and iterate over them as well | |
| 1169 int nblocks = BlockBegin::number_of_blocks(); | |
| 1170 BlockList blocks(nblocks); | |
| 1171 boolArray visited_block(nblocks, false); | |
| 1172 | |
| 1173 blocks.push(ir()->start()); | |
| 1174 visited_block[ir()->start()->block_id()] = true; | |
| 1175 for (int i = 0; i < blocks.length(); i++) { | |
| 1176 BlockBegin* b = blocks[i]; | |
| 1177 // exception handlers need to be treated as additional roots | |
| 1178 for (int e = b->number_of_exception_handlers(); e-- > 0; ) { | |
| 1179 BlockBegin* excp = b->exception_handler_at(e); | |
| 1180 int id = excp->block_id(); | |
| 1181 if (!visited_block[id]) { | |
| 1182 blocks.push(excp); | |
| 1183 visited_block[id] = true; | |
| 1184 nce.iterate(excp); | |
| 1185 } | |
| 1186 } | |
| 1187 // traverse successors | |
| 1188 BlockEnd *end = b->end(); | |
| 1189 for (int s = end->number_of_sux(); s-- > 0; ) { | |
| 1190 BlockBegin* next = end->sux_at(s); | |
| 1191 int id = next->block_id(); | |
| 1192 if (!visited_block[id]) { | |
| 1193 blocks.push(next); | |
| 1194 visited_block[id] = true; | |
| 1195 } | |
| 1196 } | |
| 1197 } | |
| 1198 | |
| 1199 | |
| 1200 if (PrintNullCheckElimination) { | |
| 1201 tty->print_cr("Done with null check elimination for method %s::%s%s", | |
| 1202 ir()->method()->holder()->name()->as_utf8(), | |
| 1203 ir()->method()->name()->as_utf8(), | |
| 1204 ir()->method()->signature()->as_symbol()->as_utf8()); | |
| 1205 } | |
| 1206 } |