Mercurial > hg > graal-compiler
annotate src/share/vm/c1/c1_Optimizer.cpp @ 1819:f02a8bbe6ed4
6986046: C1 valuestack cleanup
Summary: fixes an historical oddity in C1 with inlining where all of the expression stacks are kept in the topmost ValueStack instead of being in their respective ValueStacks.
Reviewed-by: never
Contributed-by: Christian Wimmer <cwimmer@uci.edu>
| author | roland |
|---|---|
| date | Tue, 29 Dec 2009 19:08:54 +0100 |
| parents | d5d065957597 |
| children | 42a10fc37986 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 1783 | 2 * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
|
1552
c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
trims
parents:
579
diff
changeset
|
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
|
c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
trims
parents:
579
diff
changeset
|
20 * or visit www.oracle.com if you need additional information or have any |
|
c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
trims
parents:
579
diff
changeset
|
21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 25 #include "incls/_precompiled.incl" | |
| 26 #include "incls/_c1_Optimizer.cpp.incl" | |
| 27 | |
| 28 define_array(ValueSetArray, ValueSet*); | |
| 29 define_stack(ValueSetList, ValueSetArray); | |
| 30 | |
| 31 | |
| 32 Optimizer::Optimizer(IR* ir) { | |
| 33 assert(ir->is_valid(), "IR must be valid"); | |
| 34 _ir = ir; | |
| 35 } | |
| 36 | |
| 37 class CE_Eliminator: public BlockClosure { | |
| 38 private: | |
| 39 IR* _hir; | |
| 40 int _cee_count; // the number of CEs successfully eliminated | |
| 41 int _has_substitution; | |
| 42 | |
| 43 public: | |
| 44 CE_Eliminator(IR* hir) : _cee_count(0), _hir(hir) { | |
| 45 _has_substitution = false; | |
| 46 _hir->iterate_preorder(this); | |
| 47 if (_has_substitution) { | |
| 48 // substituted some phis so resolve the substitution | |
| 49 SubstitutionResolver sr(_hir); | |
| 50 } | |
| 51 } | |
| 52 int cee_count() const { return _cee_count; } | |
| 53 | |
| 54 void adjust_exception_edges(BlockBegin* block, BlockBegin* sux) { | |
| 55 int e = sux->number_of_exception_handlers(); | |
| 56 for (int i = 0; i < e; i++) { | |
| 57 BlockBegin* xhandler = sux->exception_handler_at(i); | |
| 58 block->add_exception_handler(xhandler); | |
| 59 | |
| 60 assert(xhandler->is_predecessor(sux), "missing predecessor"); | |
| 61 if (sux->number_of_preds() == 0) { | |
| 62 // sux is disconnected from graph so disconnect from exception handlers | |
| 63 xhandler->remove_predecessor(sux); | |
| 64 } | |
| 65 if (!xhandler->is_predecessor(block)) { | |
| 66 xhandler->add_predecessor(block); | |
| 67 } | |
| 68 } | |
| 69 } | |
| 70 | |
| 71 virtual void block_do(BlockBegin* block) { | |
| 72 // 1) find conditional expression | |
| 73 // check if block ends with an If | |
| 74 If* if_ = block->end()->as_If(); | |
| 75 if (if_ == NULL) return; | |
| 76 | |
| 77 // check if If works on int or object types | |
| 78 // (we cannot handle If's working on long, float or doubles yet, | |
| 79 // since IfOp doesn't support them - these If's show up if cmp | |
| 80 // operations followed by If's are eliminated) | |
| 81 ValueType* if_type = if_->x()->type(); | |
| 82 if (!if_type->is_int() && !if_type->is_object()) return; | |
| 83 | |
| 84 BlockBegin* t_block = if_->tsux(); | |
| 85 BlockBegin* f_block = if_->fsux(); | |
| 86 Instruction* t_cur = t_block->next(); | |
| 87 Instruction* f_cur = f_block->next(); | |
| 88 | |
| 89 // one Constant may be present between BlockBegin and BlockEnd | |
| 90 Value t_const = NULL; | |
| 91 Value f_const = NULL; | |
| 92 if (t_cur->as_Constant() != NULL && !t_cur->can_trap()) { | |
| 93 t_const = t_cur; | |
| 94 t_cur = t_cur->next(); | |
| 95 } | |
| 96 if (f_cur->as_Constant() != NULL && !f_cur->can_trap()) { | |
| 97 f_const = f_cur; | |
| 98 f_cur = f_cur->next(); | |
| 99 } | |
| 100 | |
| 101 // check if both branches end with a goto | |
| 102 Goto* t_goto = t_cur->as_Goto(); | |
| 103 if (t_goto == NULL) return; | |
| 104 Goto* f_goto = f_cur->as_Goto(); | |
| 105 if (f_goto == NULL) return; | |
| 106 | |
| 107 // check if both gotos merge into the same block | |
| 108 BlockBegin* sux = t_goto->default_sux(); | |
| 109 if (sux != f_goto->default_sux()) return; | |
| 110 | |
| 111 // check if at least one word was pushed on sux_state | |
| 112 ValueStack* sux_state = sux->state(); | |
| 113 if (sux_state->stack_size() <= if_->state()->stack_size()) return; | |
| 114 | |
| 115 // check if phi function is present at end of successor stack and that | |
| 116 // only this phi was pushed on the stack | |
| 117 Value sux_phi = sux_state->stack_at(if_->state()->stack_size()); | |
| 118 if (sux_phi == NULL || sux_phi->as_Phi() == NULL || sux_phi->as_Phi()->block() != sux) return; | |
| 119 if (sux_phi->type()->size() != sux_state->stack_size() - if_->state()->stack_size()) return; | |
| 120 | |
| 121 // get the values that were pushed in the true- and false-branch | |
| 122 Value t_value = t_goto->state()->stack_at(if_->state()->stack_size()); | |
| 123 Value f_value = f_goto->state()->stack_at(if_->state()->stack_size()); | |
| 124 | |
| 125 // backend does not support floats | |
| 126 assert(t_value->type()->base() == f_value->type()->base(), "incompatible types"); | |
| 127 if (t_value->type()->is_float_kind()) return; | |
| 128 | |
| 129 // check that successor has no other phi functions but sux_phi | |
| 130 // this can happen when t_block or f_block contained additonal stores to local variables | |
| 131 // that are no longer represented by explicit instructions | |
| 132 for_each_phi_fun(sux, phi, | |
| 133 if (phi != sux_phi) return; | |
| 134 ); | |
| 135 // true and false blocks can't have phis | |
| 136 for_each_phi_fun(t_block, phi, return; ); | |
| 137 for_each_phi_fun(f_block, phi, return; ); | |
| 138 | |
| 139 // 2) substitute conditional expression | |
| 140 // with an IfOp followed by a Goto | |
| 141 // cut if_ away and get node before | |
| 142 Instruction* cur_end = if_->prev(block); | |
| 143 | |
| 144 // append constants of true- and false-block if necessary | |
| 145 // clone constants because original block must not be destroyed | |
| 146 assert((t_value != f_const && f_value != t_const) || t_const == f_const, "mismatch"); | |
| 147 if (t_value == t_const) { | |
| 148 t_value = new Constant(t_const->type()); | |
| 1819 | 149 NOT_PRODUCT(t_value->set_printable_bci(if_->printable_bci())); |
| 150 cur_end = cur_end->set_next(t_value); | |
| 0 | 151 } |
| 152 if (f_value == f_const) { | |
| 153 f_value = new Constant(f_const->type()); | |
| 1819 | 154 NOT_PRODUCT(f_value->set_printable_bci(if_->printable_bci())); |
| 155 cur_end = cur_end->set_next(f_value); | |
| 0 | 156 } |
| 157 | |
| 158 // it is very unlikely that the condition can be statically decided | |
| 159 // (this was checked previously by the Canonicalizer), so always | |
| 160 // append IfOp | |
| 161 Value result = new IfOp(if_->x(), if_->cond(), if_->y(), t_value, f_value); | |
| 1819 | 162 NOT_PRODUCT(result->set_printable_bci(if_->printable_bci())); |
| 163 cur_end = cur_end->set_next(result); | |
| 0 | 164 |
| 165 // append Goto to successor | |
| 166 ValueStack* state_before = if_->is_safepoint() ? if_->state_before() : NULL; | |
| 167 Goto* goto_ = new Goto(sux, state_before, if_->is_safepoint() || t_goto->is_safepoint() || f_goto->is_safepoint()); | |
| 168 | |
| 169 // prepare state for Goto | |
| 170 ValueStack* goto_state = if_->state(); | |
| 171 while (sux_state->scope() != goto_state->scope()) { | |
| 1819 | 172 goto_state = goto_state->caller_state(); |
| 0 | 173 assert(goto_state != NULL, "states do not match up"); |
| 174 } | |
| 1819 | 175 goto_state = goto_state->copy(ValueStack::StateAfter, goto_state->bci()); |
| 0 | 176 goto_state->push(result->type(), result); |
| 1819 | 177 assert(goto_state->is_same(sux_state), "states must match now"); |
| 0 | 178 goto_->set_state(goto_state); |
| 179 | |
| 1819 | 180 cur_end = cur_end->set_next(goto_, goto_state->bci()); |
| 0 | 181 |
| 182 // Adjust control flow graph | |
| 183 BlockBegin::disconnect_edge(block, t_block); | |
| 184 BlockBegin::disconnect_edge(block, f_block); | |
| 185 if (t_block->number_of_preds() == 0) { | |
| 186 BlockBegin::disconnect_edge(t_block, sux); | |
| 187 } | |
| 188 adjust_exception_edges(block, t_block); | |
| 189 if (f_block->number_of_preds() == 0) { | |
| 190 BlockBegin::disconnect_edge(f_block, sux); | |
| 191 } | |
| 192 adjust_exception_edges(block, f_block); | |
| 193 | |
| 194 // update block end | |
| 195 block->set_end(goto_); | |
| 196 | |
| 197 // substitute the phi if possible | |
| 198 if (sux_phi->as_Phi()->operand_count() == 1) { | |
| 199 assert(sux_phi->as_Phi()->operand_at(0) == result, "screwed up phi"); | |
| 200 sux_phi->set_subst(result); | |
| 201 _has_substitution = true; | |
| 202 } | |
| 203 | |
| 204 // 3) successfully eliminated a conditional expression | |
| 205 _cee_count++; | |
| 206 if (PrintCEE) { | |
| 207 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()); | |
| 208 } | |
| 209 | |
| 210 _hir->verify(); | |
| 211 } | |
| 212 }; | |
| 213 | |
| 214 | |
| 215 void Optimizer::eliminate_conditional_expressions() { | |
| 216 // find conditional expressions & replace them with IfOps | |
| 217 CE_Eliminator ce(ir()); | |
| 218 } | |
| 219 | |
| 220 | |
| 221 class BlockMerger: public BlockClosure { | |
| 222 private: | |
| 223 IR* _hir; | |
| 224 int _merge_count; // the number of block pairs successfully merged | |
| 225 | |
| 226 public: | |
| 227 BlockMerger(IR* hir) | |
| 228 : _hir(hir) | |
| 229 , _merge_count(0) | |
| 230 { | |
| 231 _hir->iterate_preorder(this); | |
| 232 } | |
| 233 | |
| 234 bool try_merge(BlockBegin* block) { | |
| 235 BlockEnd* end = block->end(); | |
| 236 if (end->as_Goto() != NULL) { | |
| 237 assert(end->number_of_sux() == 1, "end must have exactly one successor"); | |
| 238 // Note: It would be sufficient to check for the number of successors (= 1) | |
| 239 // in order to decide if this block can be merged potentially. That | |
| 240 // would then also include switch statements w/ only a default case. | |
| 241 // However, in that case we would need to make sure the switch tag | |
| 242 // expression is executed if it can produce observable side effects. | |
| 243 // We should probably have the canonicalizer simplifying such switch | |
| 244 // statements and then we are sure we don't miss these merge opportunities | |
| 245 // here (was bug - gri 7/7/99). | |
| 246 BlockBegin* sux = end->default_sux(); | |
| 247 if (sux->number_of_preds() == 1 && !sux->is_entry_block() && !end->is_safepoint()) { | |
| 248 // merge the two blocks | |
| 249 | |
| 250 #ifdef ASSERT | |
| 251 // verify that state at the end of block and at the beginning of sux are equal | |
| 252 // no phi functions must be present at beginning of sux | |
| 253 ValueStack* sux_state = sux->state(); | |
| 254 ValueStack* end_state = end->state(); | |
| 1819 | 255 |
| 256 assert(end_state->scope() == sux_state->scope(), "scopes must match"); | |
| 0 | 257 assert(end_state->stack_size() == sux_state->stack_size(), "stack not equal"); |
| 258 assert(end_state->locals_size() == sux_state->locals_size(), "locals not equal"); | |
| 259 | |
| 260 int index; | |
| 261 Value sux_value; | |
| 262 for_each_stack_value(sux_state, index, sux_value) { | |
| 263 assert(sux_value == end_state->stack_at(index), "stack not equal"); | |
| 264 } | |
| 265 for_each_local_value(sux_state, index, sux_value) { | |
| 266 assert(sux_value == end_state->local_at(index), "locals not equal"); | |
| 267 } | |
| 268 assert(sux_state->caller_state() == end_state->caller_state(), "caller not equal"); | |
| 269 #endif | |
| 270 | |
| 271 // find instruction before end & append first instruction of sux block | |
| 272 Instruction* prev = end->prev(block); | |
| 273 Instruction* next = sux->next(); | |
| 274 assert(prev->as_BlockEnd() == NULL, "must not be a BlockEnd"); | |
| 1819 | 275 prev->set_next(next); |
| 0 | 276 sux->disconnect_from_graph(); |
| 277 block->set_end(sux->end()); | |
| 278 // add exception handlers of deleted block, if any | |
| 279 for (int k = 0; k < sux->number_of_exception_handlers(); k++) { | |
| 280 BlockBegin* xhandler = sux->exception_handler_at(k); | |
| 281 block->add_exception_handler(xhandler); | |
| 282 | |
| 283 // also substitute predecessor of exception handler | |
| 284 assert(xhandler->is_predecessor(sux), "missing predecessor"); | |
| 285 xhandler->remove_predecessor(sux); | |
| 286 if (!xhandler->is_predecessor(block)) { | |
| 287 xhandler->add_predecessor(block); | |
| 288 } | |
| 289 } | |
| 290 | |
| 291 // debugging output | |
| 292 _merge_count++; | |
| 293 if (PrintBlockElimination) { | |
| 294 tty->print_cr("%d. merged B%d & B%d (stack size = %d)", | |
| 295 _merge_count, block->block_id(), sux->block_id(), sux->state()->stack_size()); | |
| 296 } | |
| 297 | |
| 298 _hir->verify(); | |
| 299 | |
| 300 If* if_ = block->end()->as_If(); | |
| 301 if (if_) { | |
| 302 IfOp* ifop = if_->x()->as_IfOp(); | |
| 303 Constant* con = if_->y()->as_Constant(); | |
| 304 bool swapped = false; | |
| 305 if (!con || !ifop) { | |
| 306 ifop = if_->y()->as_IfOp(); | |
| 307 con = if_->x()->as_Constant(); | |
| 308 swapped = true; | |
| 309 } | |
| 310 if (con && ifop) { | |
| 311 Constant* tval = ifop->tval()->as_Constant(); | |
| 312 Constant* fval = ifop->fval()->as_Constant(); | |
| 313 if (tval && fval) { | |
| 314 // Find the instruction before if_, starting with ifop. | |
| 315 // When if_ and ifop are not in the same block, prev | |
| 316 // becomes NULL In such (rare) cases it is not | |
| 317 // profitable to perform the optimization. | |
| 318 Value prev = ifop; | |
| 319 while (prev != NULL && prev->next() != if_) { | |
| 320 prev = prev->next(); | |
| 321 } | |
| 322 | |
| 323 if (prev != NULL) { | |
| 324 Instruction::Condition cond = if_->cond(); | |
| 325 BlockBegin* tsux = if_->tsux(); | |
| 326 BlockBegin* fsux = if_->fsux(); | |
| 327 if (swapped) { | |
| 328 cond = Instruction::mirror(cond); | |
| 329 } | |
| 330 | |
| 331 BlockBegin* tblock = tval->compare(cond, con, tsux, fsux); | |
| 332 BlockBegin* fblock = fval->compare(cond, con, tsux, fsux); | |
| 333 if (tblock != fblock && !if_->is_safepoint()) { | |
| 334 If* newif = new If(ifop->x(), ifop->cond(), false, ifop->y(), | |
| 335 tblock, fblock, if_->state_before(), if_->is_safepoint()); | |
| 336 newif->set_state(if_->state()->copy()); | |
| 337 | |
| 338 assert(prev->next() == if_, "must be guaranteed by above search"); | |
| 1819 | 339 NOT_PRODUCT(newif->set_printable_bci(if_->printable_bci())); |
| 340 prev->set_next(newif); | |
| 0 | 341 block->set_end(newif); |
| 342 | |
| 343 _merge_count++; | |
| 344 if (PrintBlockElimination) { | |
| 345 tty->print_cr("%d. replaced If and IfOp at end of B%d with single If", _merge_count, block->block_id()); | |
| 346 } | |
| 347 | |
| 348 _hir->verify(); | |
| 349 } | |
| 350 } | |
| 351 } | |
| 352 } | |
| 353 } | |
| 354 | |
| 355 return true; | |
| 356 } | |
| 357 } | |
| 358 return false; | |
| 359 } | |
| 360 | |
| 361 virtual void block_do(BlockBegin* block) { | |
| 362 _hir->verify(); | |
| 363 // repeat since the same block may merge again | |
| 364 while (try_merge(block)) { | |
| 365 _hir->verify(); | |
| 366 } | |
| 367 } | |
| 368 }; | |
| 369 | |
| 370 | |
| 371 void Optimizer::eliminate_blocks() { | |
| 372 // merge blocks if possible | |
| 373 BlockMerger bm(ir()); | |
| 374 } | |
| 375 | |
| 376 | |
| 377 class NullCheckEliminator; | |
| 378 class NullCheckVisitor: public InstructionVisitor { | |
| 379 private: | |
| 380 NullCheckEliminator* _nce; | |
| 381 NullCheckEliminator* nce() { return _nce; } | |
| 382 | |
| 383 public: | |
| 384 NullCheckVisitor() {} | |
| 385 | |
| 386 void set_eliminator(NullCheckEliminator* nce) { _nce = nce; } | |
| 387 | |
| 388 void do_Phi (Phi* x); | |
| 389 void do_Local (Local* x); | |
| 390 void do_Constant (Constant* x); | |
| 391 void do_LoadField (LoadField* x); | |
| 392 void do_StoreField (StoreField* x); | |
| 393 void do_ArrayLength (ArrayLength* x); | |
| 394 void do_LoadIndexed (LoadIndexed* x); | |
| 395 void do_StoreIndexed (StoreIndexed* x); | |
| 396 void do_NegateOp (NegateOp* x); | |
| 397 void do_ArithmeticOp (ArithmeticOp* x); | |
| 398 void do_ShiftOp (ShiftOp* x); | |
| 399 void do_LogicOp (LogicOp* x); | |
| 400 void do_CompareOp (CompareOp* x); | |
| 401 void do_IfOp (IfOp* x); | |
| 402 void do_Convert (Convert* x); | |
| 403 void do_NullCheck (NullCheck* x); | |
| 404 void do_Invoke (Invoke* x); | |
| 405 void do_NewInstance (NewInstance* x); | |
| 406 void do_NewTypeArray (NewTypeArray* x); | |
| 407 void do_NewObjectArray (NewObjectArray* x); | |
| 408 void do_NewMultiArray (NewMultiArray* x); | |
| 409 void do_CheckCast (CheckCast* x); | |
| 410 void do_InstanceOf (InstanceOf* x); | |
| 411 void do_MonitorEnter (MonitorEnter* x); | |
| 412 void do_MonitorExit (MonitorExit* x); | |
| 413 void do_Intrinsic (Intrinsic* x); | |
| 414 void do_BlockBegin (BlockBegin* x); | |
| 415 void do_Goto (Goto* x); | |
| 416 void do_If (If* x); | |
| 417 void do_IfInstanceOf (IfInstanceOf* x); | |
| 418 void do_TableSwitch (TableSwitch* x); | |
| 419 void do_LookupSwitch (LookupSwitch* x); | |
| 420 void do_Return (Return* x); | |
| 421 void do_Throw (Throw* x); | |
| 422 void do_Base (Base* x); | |
| 423 void do_OsrEntry (OsrEntry* x); | |
| 424 void do_ExceptionObject(ExceptionObject* x); | |
| 425 void do_RoundFP (RoundFP* x); | |
| 426 void do_UnsafeGetRaw (UnsafeGetRaw* x); | |
| 427 void do_UnsafePutRaw (UnsafePutRaw* x); | |
| 428 void do_UnsafeGetObject(UnsafeGetObject* x); | |
| 429 void do_UnsafePutObject(UnsafePutObject* x); | |
| 430 void do_UnsafePrefetchRead (UnsafePrefetchRead* x); | |
| 431 void do_UnsafePrefetchWrite(UnsafePrefetchWrite* x); | |
| 432 void do_ProfileCall (ProfileCall* x); | |
| 1783 | 433 void do_ProfileInvoke (ProfileInvoke* x); |
| 0 | 434 }; |
| 435 | |
| 436 | |
| 437 // Because of a static contained within (for the purpose of iteration | |
| 438 // over instructions), it is only valid to have one of these active at | |
| 439 // a time | |
| 1584 | 440 class NullCheckEliminator: public ValueVisitor { |
| 0 | 441 private: |
| 442 Optimizer* _opt; | |
| 443 | |
| 444 ValueSet* _visitable_instructions; // Visit each instruction only once per basic block | |
| 445 BlockList* _work_list; // Basic blocks to visit | |
| 446 | |
| 447 bool visitable(Value x) { | |
| 448 assert(_visitable_instructions != NULL, "check"); | |
| 449 return _visitable_instructions->contains(x); | |
| 450 } | |
| 451 void mark_visited(Value x) { | |
| 452 assert(_visitable_instructions != NULL, "check"); | |
| 453 _visitable_instructions->remove(x); | |
| 454 } | |
| 455 void mark_visitable(Value x) { | |
| 456 assert(_visitable_instructions != NULL, "check"); | |
| 457 _visitable_instructions->put(x); | |
| 458 } | |
| 459 void clear_visitable_state() { | |
| 460 assert(_visitable_instructions != NULL, "check"); | |
| 461 _visitable_instructions->clear(); | |
| 462 } | |
| 463 | |
| 464 ValueSet* _set; // current state, propagated to subsequent BlockBegins | |
| 465 ValueSetList _block_states; // BlockBegin null-check states for all processed blocks | |
| 466 NullCheckVisitor _visitor; | |
| 467 NullCheck* _last_explicit_null_check; | |
| 468 | |
| 469 bool set_contains(Value x) { assert(_set != NULL, "check"); return _set->contains(x); } | |
| 470 void set_put (Value x) { assert(_set != NULL, "check"); _set->put(x); } | |
| 471 void set_remove (Value x) { assert(_set != NULL, "check"); _set->remove(x); } | |
| 472 | |
| 473 BlockList* work_list() { return _work_list; } | |
| 474 | |
| 475 void iterate_all(); | |
| 476 void iterate_one(BlockBegin* block); | |
| 477 | |
| 478 ValueSet* state() { return _set; } | |
| 479 void set_state_from (ValueSet* state) { _set->set_from(state); } | |
| 480 ValueSet* state_for (BlockBegin* block) { return _block_states[block->block_id()]; } | |
| 481 void set_state_for (BlockBegin* block, ValueSet* stack) { _block_states[block->block_id()] = stack; } | |
| 482 // Returns true if caused a change in the block's state. | |
| 483 bool merge_state_for(BlockBegin* block, | |
| 484 ValueSet* incoming_state); | |
| 485 | |
| 486 public: | |
| 487 // constructor | |
| 488 NullCheckEliminator(Optimizer* opt) | |
| 489 : _opt(opt) | |
| 490 , _set(new ValueSet()) | |
| 491 , _last_explicit_null_check(NULL) | |
| 492 , _block_states(BlockBegin::number_of_blocks(), NULL) | |
| 493 , _work_list(new BlockList()) { | |
| 494 _visitable_instructions = new ValueSet(); | |
| 495 _visitor.set_eliminator(this); | |
| 496 } | |
| 497 | |
| 498 Optimizer* opt() { return _opt; } | |
| 499 IR* ir () { return opt()->ir(); } | |
| 500 | |
| 501 // Process a graph | |
| 502 void iterate(BlockBegin* root); | |
| 503 | |
| 1584 | 504 void visit(Value* f); |
| 505 | |
| 0 | 506 // In some situations (like NullCheck(x); getfield(x)) the debug |
| 507 // information from the explicit NullCheck can be used to populate | |
| 508 // the getfield, even if the two instructions are in different | |
| 509 // scopes; this allows implicit null checks to be used but the | |
| 510 // correct exception information to be generated. We must clear the | |
| 511 // last-traversed NullCheck when we reach a potentially-exception- | |
| 512 // throwing instruction, as well as in some other cases. | |
| 513 void set_last_explicit_null_check(NullCheck* check) { _last_explicit_null_check = check; } | |
| 514 NullCheck* last_explicit_null_check() { return _last_explicit_null_check; } | |
| 515 Value last_explicit_null_check_obj() { return (_last_explicit_null_check | |
| 516 ? _last_explicit_null_check->obj() | |
| 517 : NULL); } | |
| 518 NullCheck* consume_last_explicit_null_check() { | |
| 519 _last_explicit_null_check->unpin(Instruction::PinExplicitNullCheck); | |
| 520 _last_explicit_null_check->set_can_trap(false); | |
| 521 return _last_explicit_null_check; | |
| 522 } | |
| 523 void clear_last_explicit_null_check() { _last_explicit_null_check = NULL; } | |
| 524 | |
| 525 // Handlers for relevant instructions | |
| 526 // (separated out from NullCheckVisitor for clarity) | |
| 527 | |
| 528 // The basic contract is that these must leave the instruction in | |
| 529 // the desired state; must not assume anything about the state of | |
| 530 // the instruction. We make multiple passes over some basic blocks | |
| 531 // and the last pass is the only one whose result is valid. | |
| 532 void handle_AccessField (AccessField* x); | |
| 533 void handle_ArrayLength (ArrayLength* x); | |
| 534 void handle_LoadIndexed (LoadIndexed* x); | |
| 535 void handle_StoreIndexed (StoreIndexed* x); | |
| 536 void handle_NullCheck (NullCheck* x); | |
| 537 void handle_Invoke (Invoke* x); | |
| 538 void handle_NewInstance (NewInstance* x); | |
| 539 void handle_NewArray (NewArray* x); | |
| 540 void handle_AccessMonitor (AccessMonitor* x); | |
| 541 void handle_Intrinsic (Intrinsic* x); | |
| 542 void handle_ExceptionObject (ExceptionObject* x); | |
| 543 void handle_Phi (Phi* x); | |
| 544 }; | |
| 545 | |
| 546 | |
| 547 // NEEDS_CLEANUP | |
| 548 // There may be other instructions which need to clear the last | |
| 549 // explicit null check. Anything across which we can not hoist the | |
| 550 // debug information for a NullCheck instruction must clear it. It | |
| 551 // might be safer to pattern match "NullCheck ; {AccessField, | |
| 552 // ArrayLength, LoadIndexed}" but it is more easily structured this way. | |
| 553 // Should test to see performance hit of clearing it for all handlers | |
| 554 // with empty bodies below. If it is negligible then we should leave | |
| 555 // that in for safety, otherwise should think more about it. | |
| 556 void NullCheckVisitor::do_Phi (Phi* x) { nce()->handle_Phi(x); } | |
| 557 void NullCheckVisitor::do_Local (Local* x) {} | |
| 558 void NullCheckVisitor::do_Constant (Constant* x) { /* FIXME: handle object constants */ } | |
| 559 void NullCheckVisitor::do_LoadField (LoadField* x) { nce()->handle_AccessField(x); } | |
| 560 void NullCheckVisitor::do_StoreField (StoreField* x) { nce()->handle_AccessField(x); } | |
| 561 void NullCheckVisitor::do_ArrayLength (ArrayLength* x) { nce()->handle_ArrayLength(x); } | |
| 562 void NullCheckVisitor::do_LoadIndexed (LoadIndexed* x) { nce()->handle_LoadIndexed(x); } | |
| 563 void NullCheckVisitor::do_StoreIndexed (StoreIndexed* x) { nce()->handle_StoreIndexed(x); } | |
| 564 void NullCheckVisitor::do_NegateOp (NegateOp* x) {} | |
| 565 void NullCheckVisitor::do_ArithmeticOp (ArithmeticOp* x) { if (x->can_trap()) nce()->clear_last_explicit_null_check(); } | |
| 566 void NullCheckVisitor::do_ShiftOp (ShiftOp* x) {} | |
| 567 void NullCheckVisitor::do_LogicOp (LogicOp* x) {} | |
| 568 void NullCheckVisitor::do_CompareOp (CompareOp* x) {} | |
| 569 void NullCheckVisitor::do_IfOp (IfOp* x) {} | |
| 570 void NullCheckVisitor::do_Convert (Convert* x) {} | |
| 571 void NullCheckVisitor::do_NullCheck (NullCheck* x) { nce()->handle_NullCheck(x); } | |
| 572 void NullCheckVisitor::do_Invoke (Invoke* x) { nce()->handle_Invoke(x); } | |
| 573 void NullCheckVisitor::do_NewInstance (NewInstance* x) { nce()->handle_NewInstance(x); } | |
| 574 void NullCheckVisitor::do_NewTypeArray (NewTypeArray* x) { nce()->handle_NewArray(x); } | |
| 575 void NullCheckVisitor::do_NewObjectArray (NewObjectArray* x) { nce()->handle_NewArray(x); } | |
| 576 void NullCheckVisitor::do_NewMultiArray (NewMultiArray* x) { nce()->handle_NewArray(x); } | |
| 577 void NullCheckVisitor::do_CheckCast (CheckCast* x) {} | |
| 578 void NullCheckVisitor::do_InstanceOf (InstanceOf* x) {} | |
| 579 void NullCheckVisitor::do_MonitorEnter (MonitorEnter* x) { nce()->handle_AccessMonitor(x); } | |
| 580 void NullCheckVisitor::do_MonitorExit (MonitorExit* x) { nce()->handle_AccessMonitor(x); } | |
| 581 void NullCheckVisitor::do_Intrinsic (Intrinsic* x) { nce()->clear_last_explicit_null_check(); } | |
| 582 void NullCheckVisitor::do_BlockBegin (BlockBegin* x) {} | |
| 583 void NullCheckVisitor::do_Goto (Goto* x) {} | |
| 584 void NullCheckVisitor::do_If (If* x) {} | |
| 585 void NullCheckVisitor::do_IfInstanceOf (IfInstanceOf* x) {} | |
| 586 void NullCheckVisitor::do_TableSwitch (TableSwitch* x) {} | |
| 587 void NullCheckVisitor::do_LookupSwitch (LookupSwitch* x) {} | |
| 588 void NullCheckVisitor::do_Return (Return* x) {} | |
| 589 void NullCheckVisitor::do_Throw (Throw* x) { nce()->clear_last_explicit_null_check(); } | |
| 590 void NullCheckVisitor::do_Base (Base* x) {} | |
| 591 void NullCheckVisitor::do_OsrEntry (OsrEntry* x) {} | |
| 592 void NullCheckVisitor::do_ExceptionObject(ExceptionObject* x) { nce()->handle_ExceptionObject(x); } | |
| 593 void NullCheckVisitor::do_RoundFP (RoundFP* x) {} | |
| 594 void NullCheckVisitor::do_UnsafeGetRaw (UnsafeGetRaw* x) {} | |
| 595 void NullCheckVisitor::do_UnsafePutRaw (UnsafePutRaw* x) {} | |
| 596 void NullCheckVisitor::do_UnsafeGetObject(UnsafeGetObject* x) {} | |
| 597 void NullCheckVisitor::do_UnsafePutObject(UnsafePutObject* x) {} | |
| 598 void NullCheckVisitor::do_UnsafePrefetchRead (UnsafePrefetchRead* x) {} | |
| 599 void NullCheckVisitor::do_UnsafePrefetchWrite(UnsafePrefetchWrite* x) {} | |
| 600 void NullCheckVisitor::do_ProfileCall (ProfileCall* x) { nce()->clear_last_explicit_null_check(); } | |
| 1783 | 601 void NullCheckVisitor::do_ProfileInvoke (ProfileInvoke* x) {} |
| 0 | 602 |
| 603 | |
| 1584 | 604 void NullCheckEliminator::visit(Value* p) { |
| 0 | 605 assert(*p != NULL, "should not find NULL instructions"); |
| 1584 | 606 if (visitable(*p)) { |
| 607 mark_visited(*p); | |
| 608 (*p)->visit(&_visitor); | |
| 0 | 609 } |
| 610 } | |
| 611 | |
| 612 bool NullCheckEliminator::merge_state_for(BlockBegin* block, ValueSet* incoming_state) { | |
| 613 ValueSet* state = state_for(block); | |
| 614 if (state == NULL) { | |
| 615 state = incoming_state->copy(); | |
| 616 set_state_for(block, state); | |
| 617 return true; | |
| 618 } else { | |
| 619 bool changed = state->set_intersect(incoming_state); | |
| 620 if (PrintNullCheckElimination && changed) { | |
| 621 tty->print_cr("Block %d's null check state changed", block->block_id()); | |
| 622 } | |
| 623 return changed; | |
| 624 } | |
| 625 } | |
| 626 | |
| 627 | |
| 628 void NullCheckEliminator::iterate_all() { | |
| 629 while (work_list()->length() > 0) { | |
| 630 iterate_one(work_list()->pop()); | |
| 631 } | |
| 632 } | |
| 633 | |
| 634 | |
| 635 void NullCheckEliminator::iterate_one(BlockBegin* block) { | |
| 636 clear_visitable_state(); | |
| 637 // clear out an old explicit null checks | |
| 638 set_last_explicit_null_check(NULL); | |
| 639 | |
| 640 if (PrintNullCheckElimination) { | |
| 641 tty->print_cr(" ...iterating block %d in null check elimination for %s::%s%s", | |
| 642 block->block_id(), | |
| 643 ir()->method()->holder()->name()->as_utf8(), | |
| 644 ir()->method()->name()->as_utf8(), | |
| 645 ir()->method()->signature()->as_symbol()->as_utf8()); | |
| 646 } | |
| 647 | |
| 648 // Create new state if none present (only happens at root) | |
| 649 if (state_for(block) == NULL) { | |
| 650 ValueSet* tmp_state = new ValueSet(); | |
| 651 set_state_for(block, tmp_state); | |
| 652 // Initial state is that local 0 (receiver) is non-null for | |
| 653 // non-static methods | |
| 654 ValueStack* stack = block->state(); | |
| 655 IRScope* scope = stack->scope(); | |
| 656 ciMethod* method = scope->method(); | |
| 657 if (!method->is_static()) { | |
| 658 Local* local0 = stack->local_at(0)->as_Local(); | |
| 659 assert(local0 != NULL, "must be"); | |
| 660 assert(local0->type() == objectType, "invalid type of receiver"); | |
| 661 | |
| 662 if (local0 != NULL) { | |
| 663 // Local 0 is used in this scope | |
| 664 tmp_state->put(local0); | |
| 665 if (PrintNullCheckElimination) { | |
| 666 tty->print_cr("Local 0 (value %d) proven non-null upon entry", local0->id()); | |
| 667 } | |
| 668 } | |
| 669 } | |
| 670 } | |
| 671 | |
| 672 // Must copy block's state to avoid mutating it during iteration | |
| 673 // through the block -- otherwise "not-null" states can accidentally | |
| 674 // propagate "up" through the block during processing of backward | |
| 675 // branches and algorithm is incorrect (and does not converge) | |
| 676 set_state_from(state_for(block)); | |
| 677 | |
| 678 // allow visiting of Phis belonging to this block | |
| 679 for_each_phi_fun(block, phi, | |
| 680 mark_visitable(phi); | |
| 681 ); | |
| 682 | |
| 683 BlockEnd* e = block->end(); | |
| 684 assert(e != NULL, "incomplete graph"); | |
| 685 int i; | |
| 686 | |
| 687 // Propagate the state before this block into the exception | |
| 688 // handlers. They aren't true successors since we aren't guaranteed | |
| 689 // to execute the whole block before executing them. Also putting | |
| 690 // them on first seems to help reduce the amount of iteration to | |
| 691 // reach a fixed point. | |
| 692 for (i = 0; i < block->number_of_exception_handlers(); i++) { | |
| 693 BlockBegin* next = block->exception_handler_at(i); | |
| 694 if (merge_state_for(next, state())) { | |
| 695 if (!work_list()->contains(next)) { | |
| 696 work_list()->push(next); | |
| 697 } | |
| 698 } | |
| 699 } | |
| 700 | |
| 701 // Iterate through block, updating state. | |
| 702 for (Instruction* instr = block; instr != NULL; instr = instr->next()) { | |
| 703 // Mark instructions in this block as visitable as they are seen | |
| 704 // in the instruction list. This keeps the iteration from | |
| 705 // visiting instructions which are references in other blocks or | |
| 706 // visiting instructions more than once. | |
| 707 mark_visitable(instr); | |
| 1819 | 708 if (instr->is_pinned() || instr->can_trap() || (instr->as_NullCheck() != NULL)) { |
| 0 | 709 mark_visited(instr); |
| 1584 | 710 instr->input_values_do(this); |
| 0 | 711 instr->visit(&_visitor); |
| 712 } | |
| 713 } | |
| 714 | |
| 715 // Propagate state to successors if necessary | |
| 716 for (i = 0; i < e->number_of_sux(); i++) { | |
| 717 BlockBegin* next = e->sux_at(i); | |
| 718 if (merge_state_for(next, state())) { | |
| 719 if (!work_list()->contains(next)) { | |
| 720 work_list()->push(next); | |
| 721 } | |
| 722 } | |
| 723 } | |
| 724 } | |
| 725 | |
| 726 | |
| 727 void NullCheckEliminator::iterate(BlockBegin* block) { | |
| 728 work_list()->push(block); | |
| 729 iterate_all(); | |
| 730 } | |
| 731 | |
| 732 void NullCheckEliminator::handle_AccessField(AccessField* x) { | |
| 733 if (x->is_static()) { | |
| 734 if (x->as_LoadField() != NULL) { | |
| 735 // If the field is a non-null static final object field (as is | |
| 736 // often the case for sun.misc.Unsafe), put this LoadField into | |
| 737 // the non-null map | |
| 738 ciField* field = x->field(); | |
| 739 if (field->is_constant()) { | |
| 740 ciConstant field_val = field->constant_value(); | |
| 741 BasicType field_type = field_val.basic_type(); | |
| 742 if (field_type == T_OBJECT || field_type == T_ARRAY) { | |
| 743 ciObject* obj_val = field_val.as_object(); | |
| 744 if (!obj_val->is_null_object()) { | |
| 745 if (PrintNullCheckElimination) { | |
| 746 tty->print_cr("AccessField %d proven non-null by static final non-null oop check", | |
| 747 x->id()); | |
| 748 } | |
| 749 set_put(x); | |
| 750 } | |
| 751 } | |
| 752 } | |
| 753 } | |
| 754 // Be conservative | |
| 755 clear_last_explicit_null_check(); | |
| 756 return; | |
| 757 } | |
| 758 | |
| 759 Value obj = x->obj(); | |
| 760 if (set_contains(obj)) { | |
| 761 // Value is non-null => update AccessField | |
| 762 if (last_explicit_null_check_obj() == obj && !x->needs_patching()) { | |
| 763 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
| 764 x->set_needs_null_check(true); | |
| 765 if (PrintNullCheckElimination) { | |
| 766 tty->print_cr("Folded NullCheck %d into AccessField %d's null check for value %d", | |
| 767 x->explicit_null_check()->id(), x->id(), obj->id()); | |
| 768 } | |
| 769 } else { | |
| 770 x->set_explicit_null_check(NULL); | |
| 771 x->set_needs_null_check(false); | |
| 772 if (PrintNullCheckElimination) { | |
| 773 tty->print_cr("Eliminated AccessField %d's null check for value %d", x->id(), obj->id()); | |
| 774 } | |
| 775 } | |
| 776 } else { | |
| 777 set_put(obj); | |
| 778 if (PrintNullCheckElimination) { | |
| 779 tty->print_cr("AccessField %d of value %d proves value to be non-null", x->id(), obj->id()); | |
| 780 } | |
| 781 // Ensure previous passes do not cause wrong state | |
| 782 x->set_needs_null_check(true); | |
| 783 x->set_explicit_null_check(NULL); | |
| 784 } | |
| 785 clear_last_explicit_null_check(); | |
| 786 } | |
| 787 | |
| 788 | |
| 789 void NullCheckEliminator::handle_ArrayLength(ArrayLength* x) { | |
| 790 Value array = x->array(); | |
| 791 if (set_contains(array)) { | |
| 792 // Value is non-null => update AccessArray | |
| 793 if (last_explicit_null_check_obj() == array) { | |
| 794 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
| 795 x->set_needs_null_check(true); | |
| 796 if (PrintNullCheckElimination) { | |
| 797 tty->print_cr("Folded NullCheck %d into ArrayLength %d's null check for value %d", | |
| 798 x->explicit_null_check()->id(), x->id(), array->id()); | |
| 799 } | |
| 800 } else { | |
| 801 x->set_explicit_null_check(NULL); | |
| 802 x->set_needs_null_check(false); | |
| 803 if (PrintNullCheckElimination) { | |
| 804 tty->print_cr("Eliminated ArrayLength %d's null check for value %d", x->id(), array->id()); | |
| 805 } | |
| 806 } | |
| 807 } else { | |
| 808 set_put(array); | |
| 809 if (PrintNullCheckElimination) { | |
| 810 tty->print_cr("ArrayLength %d of value %d proves value to be non-null", x->id(), array->id()); | |
| 811 } | |
| 812 // Ensure previous passes do not cause wrong state | |
| 813 x->set_needs_null_check(true); | |
| 814 x->set_explicit_null_check(NULL); | |
| 815 } | |
| 816 clear_last_explicit_null_check(); | |
| 817 } | |
| 818 | |
| 819 | |
| 820 void NullCheckEliminator::handle_LoadIndexed(LoadIndexed* x) { | |
| 821 Value array = x->array(); | |
| 822 if (set_contains(array)) { | |
| 823 // Value is non-null => update AccessArray | |
| 824 if (last_explicit_null_check_obj() == array) { | |
| 825 x->set_explicit_null_check(consume_last_explicit_null_check()); | |
| 826 x->set_needs_null_check(true); | |
| 827 if (PrintNullCheckElimination) { | |
| 828 tty->print_cr("Folded NullCheck %d into LoadIndexed %d's null check for value %d", | |
| 829 x->explicit_null_check()->id(), x->id(), array->id()); | |
| 830 } | |
| 831 } else { | |
| 832 x->set_explicit_null_check(NULL); | |
| 833 x->set_needs_null_check(false); | |
| 834 if (PrintNullCheckElimination) { | |
| 835 tty->print_cr("Eliminated LoadIndexed %d's null check for value %d", x->id(), array->id()); | |
| 836 } | |
| 837 } | |
| 838 } else { | |
| 839 set_put(array); | |
| 840 if (PrintNullCheckElimination) { | |
| 841 tty->print_cr("LoadIndexed %d of value %d proves value to be non-null", x->id(), array->id()); | |
| 842 } | |
| 843 // Ensure previous passes do not cause wrong state | |
| 844 x->set_needs_null_check(true); | |
| 845 x->set_explicit_null_check(NULL); | |
| 846 } | |
| 847 clear_last_explicit_null_check(); | |
| 848 } | |
| 849 | |
| 850 | |
| 851 void NullCheckEliminator::handle_StoreIndexed(StoreIndexed* x) { | |
| 852 Value array = x->array(); | |
| 853 if (set_contains(array)) { | |
| 854 // Value is non-null => update AccessArray | |
| 855 if (PrintNullCheckElimination) { | |
| 856 tty->print_cr("Eliminated StoreIndexed %d's null check for value %d", x->id(), array->id()); | |
| 857 } | |
| 858 x->set_needs_null_check(false); | |
| 859 } else { | |
| 860 set_put(array); | |
| 861 if (PrintNullCheckElimination) { | |
| 862 tty->print_cr("StoreIndexed %d of value %d proves value to be non-null", x->id(), array->id()); | |
| 863 } | |
| 864 // Ensure previous passes do not cause wrong state | |
| 865 x->set_needs_null_check(true); | |
| 866 } | |
| 867 clear_last_explicit_null_check(); | |
| 868 } | |
| 869 | |
| 870 | |
| 871 void NullCheckEliminator::handle_NullCheck(NullCheck* x) { | |
| 872 Value obj = x->obj(); | |
| 873 if (set_contains(obj)) { | |
| 874 // Already proven to be non-null => this NullCheck is useless | |
| 875 if (PrintNullCheckElimination) { | |
| 876 tty->print_cr("Eliminated NullCheck %d for value %d", x->id(), obj->id()); | |
| 877 } | |
| 878 // Don't unpin since that may shrink obj's live range and make it unavailable for debug info. | |
| 879 // The code generator won't emit LIR for a NullCheck that cannot trap. | |
| 880 x->set_can_trap(false); | |
| 881 } else { | |
| 882 // May be null => add to map and set last explicit NullCheck | |
| 883 x->set_can_trap(true); | |
| 884 // make sure it's pinned if it can trap | |
| 885 x->pin(Instruction::PinExplicitNullCheck); | |
| 886 set_put(obj); | |
| 887 set_last_explicit_null_check(x); | |
| 888 if (PrintNullCheckElimination) { | |
| 889 tty->print_cr("NullCheck %d of value %d proves value to be non-null", x->id(), obj->id()); | |
| 890 } | |
| 891 } | |
| 892 } | |
| 893 | |
| 894 | |
| 895 void NullCheckEliminator::handle_Invoke(Invoke* x) { | |
| 896 if (!x->has_receiver()) { | |
| 897 // Be conservative | |
| 898 clear_last_explicit_null_check(); | |
| 899 return; | |
| 900 } | |
| 901 | |
| 902 Value recv = x->receiver(); | |
| 903 if (!set_contains(recv)) { | |
| 904 set_put(recv); | |
| 905 if (PrintNullCheckElimination) { | |
| 906 tty->print_cr("Invoke %d of value %d proves value to be non-null", x->id(), recv->id()); | |
| 907 } | |
| 908 } | |
| 909 clear_last_explicit_null_check(); | |
| 910 } | |
| 911 | |
| 912 | |
| 913 void NullCheckEliminator::handle_NewInstance(NewInstance* x) { | |
| 914 set_put(x); | |
| 915 if (PrintNullCheckElimination) { | |
| 916 tty->print_cr("NewInstance %d is non-null", x->id()); | |
| 917 } | |
| 918 } | |
| 919 | |
| 920 | |
| 921 void NullCheckEliminator::handle_NewArray(NewArray* x) { | |
| 922 set_put(x); | |
| 923 if (PrintNullCheckElimination) { | |
| 924 tty->print_cr("NewArray %d is non-null", x->id()); | |
| 925 } | |
| 926 } | |
| 927 | |
| 928 | |
| 929 void NullCheckEliminator::handle_ExceptionObject(ExceptionObject* x) { | |
| 930 set_put(x); | |
| 931 if (PrintNullCheckElimination) { | |
| 932 tty->print_cr("ExceptionObject %d is non-null", x->id()); | |
| 933 } | |
| 934 } | |
| 935 | |
| 936 | |
| 937 void NullCheckEliminator::handle_AccessMonitor(AccessMonitor* x) { | |
| 938 Value obj = x->obj(); | |
| 939 if (set_contains(obj)) { | |
| 940 // Value is non-null => update AccessMonitor | |
| 941 if (PrintNullCheckElimination) { | |
| 942 tty->print_cr("Eliminated AccessMonitor %d's null check for value %d", x->id(), obj->id()); | |
| 943 } | |
| 944 x->set_needs_null_check(false); | |
| 945 } else { | |
| 946 set_put(obj); | |
| 947 if (PrintNullCheckElimination) { | |
| 948 tty->print_cr("AccessMonitor %d of value %d proves value to be non-null", x->id(), obj->id()); | |
| 949 } | |
| 950 // Ensure previous passes do not cause wrong state | |
| 951 x->set_needs_null_check(true); | |
| 952 } | |
| 953 clear_last_explicit_null_check(); | |
| 954 } | |
| 955 | |
| 956 | |
| 957 void NullCheckEliminator::handle_Intrinsic(Intrinsic* x) { | |
| 958 if (!x->has_receiver()) { | |
| 959 // Be conservative | |
| 960 clear_last_explicit_null_check(); | |
| 961 return; | |
| 962 } | |
| 963 | |
| 964 Value recv = x->receiver(); | |
| 965 if (set_contains(recv)) { | |
| 966 // Value is non-null => update Intrinsic | |
| 967 if (PrintNullCheckElimination) { | |
| 968 tty->print_cr("Eliminated Intrinsic %d's null check for value %d", x->id(), recv->id()); | |
| 969 } | |
| 970 x->set_needs_null_check(false); | |
| 971 } else { | |
| 972 set_put(recv); | |
| 973 if (PrintNullCheckElimination) { | |
| 974 tty->print_cr("Intrinsic %d of value %d proves value to be non-null", x->id(), recv->id()); | |
| 975 } | |
| 976 // Ensure previous passes do not cause wrong state | |
| 977 x->set_needs_null_check(true); | |
| 978 } | |
| 979 clear_last_explicit_null_check(); | |
| 980 } | |
| 981 | |
| 982 | |
| 983 void NullCheckEliminator::handle_Phi(Phi* x) { | |
| 984 int i; | |
| 985 bool all_non_null = true; | |
| 986 if (x->is_illegal()) { | |
| 987 all_non_null = false; | |
| 988 } else { | |
| 989 for (i = 0; i < x->operand_count(); i++) { | |
| 990 Value input = x->operand_at(i); | |
| 991 if (!set_contains(input)) { | |
| 992 all_non_null = false; | |
| 993 } | |
| 994 } | |
| 995 } | |
| 996 | |
| 997 if (all_non_null) { | |
| 998 // Value is non-null => update Phi | |
| 999 if (PrintNullCheckElimination) { | |
| 1000 tty->print_cr("Eliminated Phi %d's null check for phifun because all inputs are non-null", x->id()); | |
| 1001 } | |
| 1002 x->set_needs_null_check(false); | |
| 1003 } else if (set_contains(x)) { | |
| 1004 set_remove(x); | |
| 1005 } | |
| 1006 } | |
| 1007 | |
| 1008 | |
| 1009 void Optimizer::eliminate_null_checks() { | |
| 1010 ResourceMark rm; | |
| 1011 | |
| 1012 NullCheckEliminator nce(this); | |
| 1013 | |
| 1014 if (PrintNullCheckElimination) { | |
| 1015 tty->print_cr("Starting null check elimination for method %s::%s%s", | |
| 1016 ir()->method()->holder()->name()->as_utf8(), | |
| 1017 ir()->method()->name()->as_utf8(), | |
| 1018 ir()->method()->signature()->as_symbol()->as_utf8()); | |
| 1019 } | |
| 1020 | |
| 1021 // Apply to graph | |
| 1022 nce.iterate(ir()->start()); | |
| 1023 | |
| 1024 // walk over the graph looking for exception | |
| 1025 // handlers and iterate over them as well | |
| 1026 int nblocks = BlockBegin::number_of_blocks(); | |
| 1027 BlockList blocks(nblocks); | |
| 1028 boolArray visited_block(nblocks, false); | |
| 1029 | |
| 1030 blocks.push(ir()->start()); | |
| 1031 visited_block[ir()->start()->block_id()] = true; | |
| 1032 for (int i = 0; i < blocks.length(); i++) { | |
| 1033 BlockBegin* b = blocks[i]; | |
| 1034 // exception handlers need to be treated as additional roots | |
| 1035 for (int e = b->number_of_exception_handlers(); e-- > 0; ) { | |
| 1036 BlockBegin* excp = b->exception_handler_at(e); | |
| 1037 int id = excp->block_id(); | |
| 1038 if (!visited_block[id]) { | |
| 1039 blocks.push(excp); | |
| 1040 visited_block[id] = true; | |
| 1041 nce.iterate(excp); | |
| 1042 } | |
| 1043 } | |
| 1044 // traverse successors | |
| 1045 BlockEnd *end = b->end(); | |
| 1046 for (int s = end->number_of_sux(); s-- > 0; ) { | |
| 1047 BlockBegin* next = end->sux_at(s); | |
| 1048 int id = next->block_id(); | |
| 1049 if (!visited_block[id]) { | |
| 1050 blocks.push(next); | |
| 1051 visited_block[id] = true; | |
| 1052 } | |
| 1053 } | |
| 1054 } | |
| 1055 | |
| 1056 | |
| 1057 if (PrintNullCheckElimination) { | |
| 1058 tty->print_cr("Done with null check elimination for method %s::%s%s", | |
| 1059 ir()->method()->holder()->name()->as_utf8(), | |
| 1060 ir()->method()->name()->as_utf8(), | |
| 1061 ir()->method()->signature()->as_symbol()->as_utf8()); | |
| 1062 } | |
| 1063 } |