1 /* 2 * Copyright (c) 2006, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "memory/allocation.inline.hpp" 27 #include "opto/connode.hpp" 28 #include "opto/convertnode.hpp" 29 #include "opto/loopnode.hpp" 30 #include "opto/opaquenode.hpp" 31 #include "opto/rootnode.hpp" 32 33 //================= Loop Unswitching ===================== 34 // 35 // orig: transformed: 36 // if (invariant-test) then 37 // predicate predicate 38 // loop loop 39 // stmt1 stmt1 40 // if (invariant-test) then stmt2 41 // stmt2 stmt4 42 // else endloop 43 // stmt3 else 44 // endif predicate [clone] 45 // stmt4 loop [clone] 46 // endloop stmt1 [clone] 47 // stmt3 48 // stmt4 [clone] 49 // endloop 50 // endif 51 // 52 // Note: the "else" clause may be empty 53 54 //------------------------------policy_unswitching----------------------------- 55 // Return TRUE or FALSE if the loop should be unswitched 56 // (ie. clone loop with an invariant test that does not exit the loop) 57 bool IdealLoopTree::policy_unswitching( PhaseIdealLoop *phase ) const { 58 if (!LoopUnswitching) { 59 return false; 60 } 61 if (!_head->is_Loop()) { 62 return false; 63 } 64 65 // If nodes are depleted, some transform has miscalculated its needs. 66 assert(!phase->exceeding_node_budget(), "sanity"); 67 68 // check for vectorized loops, any unswitching was already applied 69 if (_head->is_CountedLoop() && _head->as_CountedLoop()->is_unroll_only()) { 70 return false; 71 } 72 73 LoopNode* head = _head->as_Loop(); 74 if (head->unswitch_count() + 1 > head->unswitch_max()) { 75 return false; 76 } 77 if (phase->find_unswitching_candidate(this) == NULL) { 78 return false; 79 } 80 81 // Too speculative if running low on nodes. 82 return phase->may_require_nodes(est_loop_clone_sz(2)); 83 } 84 85 //------------------------------find_unswitching_candidate----------------------------- 86 // Find candidate "if" for unswitching 87 IfNode* PhaseIdealLoop::find_unswitching_candidate(const IdealLoopTree *loop) const { 88 89 // Find first invariant test that doesn't exit the loop 90 LoopNode *head = loop->_head->as_Loop(); 91 IfNode* unswitch_iff = NULL; 92 Node* n = head->in(LoopNode::LoopBackControl); 93 while (n != head) { 94 Node* n_dom = idom(n); 95 if (n->is_Region()) { 96 if (n_dom->is_If()) { 97 IfNode* iff = n_dom->as_If(); 98 if (iff->in(1)->is_Bool()) { 99 BoolNode* bol = iff->in(1)->as_Bool(); 100 if (bol->in(1)->is_Cmp()) { 101 // If condition is invariant and not a loop exit, 102 // then found reason to unswitch. 103 if (loop->is_invariant(bol) && !loop->is_loop_exit(iff)) { 104 unswitch_iff = iff; 105 } 106 } 107 } 108 } 109 } 110 n = n_dom; 111 } 112 return unswitch_iff; 113 } 114 115 //------------------------------do_unswitching----------------------------- 116 // Clone loop with an invariant test (that does not exit) and 117 // insert a clone of the test that selects which version to 118 // execute. 119 void PhaseIdealLoop::do_unswitching(IdealLoopTree *loop, Node_List &old_new) { 120 121 // Find first invariant test that doesn't exit the loop 122 LoopNode *head = loop->_head->as_Loop(); 123 124 IfNode* unswitch_iff = find_unswitching_candidate((const IdealLoopTree *)loop); 125 assert(unswitch_iff != NULL, "should be at least one"); 126 127 #ifndef PRODUCT 128 if (TraceLoopOpts) { 129 tty->print("Unswitch %d ", head->unswitch_count()+1); 130 loop->dump_head(); 131 } 132 #endif 133 134 // Need to revert back to normal loop 135 if (head->is_CountedLoop() && !head->as_CountedLoop()->is_normal_loop()) { 136 head->as_CountedLoop()->set_normal_loop(); 137 } 138 139 ProjNode* proj_true = create_slow_version_of_loop(loop, old_new, unswitch_iff->Opcode(), CloneIncludesStripMined); 140 141 #ifdef ASSERT 142 Node* uniqc = proj_true->unique_ctrl_out(); 143 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl); 144 Node* predicate = find_predicate(entry); 145 if (predicate != NULL) { 146 entry = skip_loop_predicates(entry); 147 } 148 if (predicate != NULL && UseLoopPredicate) { 149 // We may have two predicates, find first. 150 Node* n = find_predicate(entry); 151 if (n != NULL) { 152 predicate = n; 153 entry = skip_loop_predicates(entry); 154 } 155 } 156 if (predicate != NULL && UseProfiledLoopPredicate) { 157 entry = find_predicate(entry); 158 if (entry != NULL) predicate = entry; 159 } 160 if (predicate != NULL) predicate = predicate->in(0); 161 assert(proj_true->is_IfTrue() && 162 (predicate == NULL && uniqc == head && !head->is_strip_mined() || 163 predicate == NULL && uniqc == head->in(LoopNode::EntryControl) && head->is_strip_mined() || 164 predicate != NULL && uniqc == predicate), "by construction"); 165 #endif 166 // Increment unswitch count 167 LoopNode* head_clone = old_new[head->_idx]->as_Loop(); 168 int nct = head->unswitch_count() + 1; 169 head->set_unswitch_count(nct); 170 head_clone->set_unswitch_count(nct); 171 172 // Add test to new "if" outside of loop 173 IfNode* invar_iff = proj_true->in(0)->as_If(); 174 Node* invar_iff_c = invar_iff->in(0); 175 BoolNode* bol = unswitch_iff->in(1)->as_Bool(); 176 invar_iff->set_req(1, bol); 177 invar_iff->_prob = unswitch_iff->_prob; 178 179 ProjNode* proj_false = invar_iff->proj_out(0)->as_Proj(); 180 181 // Hoist invariant casts out of each loop to the appropriate 182 // control projection. 183 184 Node_List worklist; 185 186 for (DUIterator_Fast imax, i = unswitch_iff->fast_outs(imax); i < imax; i++) { 187 ProjNode* proj= unswitch_iff->fast_out(i)->as_Proj(); 188 // Copy to a worklist for easier manipulation 189 for (DUIterator_Fast jmax, j = proj->fast_outs(jmax); j < jmax; j++) { 190 Node* use = proj->fast_out(j); 191 if (use->Opcode() == Op_CheckCastPP && loop->is_invariant(use->in(1))) { 192 worklist.push(use); 193 } 194 } 195 ProjNode* invar_proj = invar_iff->proj_out(proj->_con)->as_Proj(); 196 while (worklist.size() > 0) { 197 Node* use = worklist.pop(); 198 Node* nuse = use->clone(); 199 nuse->set_req(0, invar_proj); 200 _igvn.replace_input_of(use, 1, nuse); 201 register_new_node(nuse, invar_proj); 202 // Same for the clone 203 Node* use_clone = old_new[use->_idx]; 204 _igvn.replace_input_of(use_clone, 1, nuse); 205 } 206 } 207 208 // Hardwire the control paths in the loops into if(true) and if(false) 209 _igvn.rehash_node_delayed(unswitch_iff); 210 short_circuit_if(unswitch_iff, proj_true); 211 212 IfNode* unswitch_iff_clone = old_new[unswitch_iff->_idx]->as_If(); 213 _igvn.rehash_node_delayed(unswitch_iff_clone); 214 short_circuit_if(unswitch_iff_clone, proj_false); 215 216 // Reoptimize loops 217 loop->record_for_igvn(); 218 for(int i = loop->_body.size() - 1; i >= 0 ; i--) { 219 Node *n = loop->_body[i]; 220 Node *n_clone = old_new[n->_idx]; 221 _igvn._worklist.push(n_clone); 222 } 223 224 #ifndef PRODUCT 225 if (TraceLoopUnswitching) { 226 tty->print_cr("Loop unswitching orig: %d @ %d new: %d @ %d", 227 head->_idx, unswitch_iff->_idx, 228 old_new[head->_idx]->_idx, unswitch_iff_clone->_idx); 229 } 230 #endif 231 232 C->set_major_progress(); 233 } 234 235 //-------------------------create_slow_version_of_loop------------------------ 236 // Create a slow version of the loop by cloning the loop 237 // and inserting an if to select fast-slow versions. 238 // Return control projection of the entry to the fast version. 239 ProjNode* PhaseIdealLoop::create_slow_version_of_loop(IdealLoopTree *loop, 240 Node_List &old_new, 241 int opcode, 242 CloneLoopMode mode) { 243 LoopNode* head = loop->_head->as_Loop(); 244 bool counted_loop = head->is_CountedLoop(); 245 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl); 246 _igvn.rehash_node_delayed(entry); 247 IdealLoopTree* outer_loop = loop->_parent; 248 249 head->verify_strip_mined(1); 250 251 Node *cont = _igvn.intcon(1); 252 set_ctrl(cont, C->root()); 253 Node* opq = new Opaque1Node(C, cont); 254 register_node(opq, outer_loop, entry, dom_depth(entry)); 255 Node *bol = new Conv2BNode(opq); 256 register_node(bol, outer_loop, entry, dom_depth(entry)); 257 IfNode* iff = (opcode == Op_RangeCheck) ? new RangeCheckNode(entry, bol, PROB_MAX, COUNT_UNKNOWN) : 258 new IfNode(entry, bol, PROB_MAX, COUNT_UNKNOWN); 259 register_node(iff, outer_loop, entry, dom_depth(entry)); 260 ProjNode* iffast = new IfTrueNode(iff); 261 register_node(iffast, outer_loop, iff, dom_depth(iff)); 262 ProjNode* ifslow = new IfFalseNode(iff); 263 register_node(ifslow, outer_loop, iff, dom_depth(iff)); 264 265 // Clone the loop body. The clone becomes the fast loop. The 266 // original pre-header will (illegally) have 3 control users 267 // (old & new loops & new if). 268 clone_loop(loop, old_new, dom_depth(head->skip_strip_mined()), mode, iff); 269 assert(old_new[head->_idx]->is_Loop(), "" ); 270 271 // Fast (true) control 272 Node* iffast_pred = clone_loop_predicates(entry, iffast, !counted_loop); 273 274 // Slow (false) control 275 Node* ifslow_pred = clone_loop_predicates(entry, ifslow, !counted_loop); 276 277 Node* l = head->skip_strip_mined(); 278 _igvn.replace_input_of(l, LoopNode::EntryControl, iffast_pred); 279 set_idom(l, iffast_pred, dom_depth(l)); 280 LoopNode* slow_l = old_new[head->_idx]->as_Loop()->skip_strip_mined(); 281 _igvn.replace_input_of(slow_l, LoopNode::EntryControl, ifslow_pred); 282 set_idom(slow_l, ifslow_pred, dom_depth(l)); 283 284 recompute_dom_depth(); 285 286 return iffast; 287 } 288 289 LoopNode* PhaseIdealLoop::create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk) { 290 Node_List old_new; 291 LoopNode* head = loop->_head->as_Loop(); 292 bool counted_loop = head->is_CountedLoop(); 293 Node* entry = head->skip_strip_mined()->in(LoopNode::EntryControl); 294 _igvn.rehash_node_delayed(entry); 295 IdealLoopTree* outer_loop = head->is_strip_mined() ? loop->_parent->_parent : loop->_parent; 296 297 ConINode* const_1 = _igvn.intcon(1); 298 set_ctrl(const_1, C->root()); 299 IfNode* iff = new IfNode(entry, const_1, PROB_MAX, COUNT_UNKNOWN); 300 register_node(iff, outer_loop, entry, dom_depth(entry)); 301 ProjNode* iffast = new IfTrueNode(iff); 302 register_node(iffast, outer_loop, iff, dom_depth(iff)); 303 ProjNode* ifslow = new IfFalseNode(iff); 304 register_node(ifslow, outer_loop, iff, dom_depth(iff)); 305 306 // Clone the loop body. The clone becomes the fast loop. The 307 // original pre-header will (illegally) have 3 control users 308 // (old & new loops & new if). 309 clone_loop(loop, old_new, dom_depth(head), CloneIncludesStripMined, iff); 310 assert(old_new[head->_idx]->is_Loop(), "" ); 311 312 LoopNode* slow_head = old_new[head->_idx]->as_Loop(); 313 314 #ifndef PRODUCT 315 if (TraceLoopOpts) { 316 tty->print_cr("PhaseIdealLoop::create_reserve_version_of_loop:"); 317 tty->print("\t iff = %d, ", iff->_idx); iff->dump(); 318 tty->print("\t iffast = %d, ", iffast->_idx); iffast->dump(); 319 tty->print("\t ifslow = %d, ", ifslow->_idx); ifslow->dump(); 320 tty->print("\t before replace_input_of: head = %d, ", head->_idx); head->dump(); 321 tty->print("\t before replace_input_of: slow_head = %d, ", slow_head->_idx); slow_head->dump(); 322 } 323 #endif 324 325 // Fast (true) control 326 _igvn.replace_input_of(head->skip_strip_mined(), LoopNode::EntryControl, iffast); 327 // Slow (false) control 328 _igvn.replace_input_of(slow_head->skip_strip_mined(), LoopNode::EntryControl, ifslow); 329 330 recompute_dom_depth(); 331 332 lk->set_iff(iff); 333 334 #ifndef PRODUCT 335 if (TraceLoopOpts ) { 336 tty->print("\t after replace_input_of: head = %d, ", head->_idx); head->dump(); 337 tty->print("\t after replace_input_of: slow_head = %d, ", slow_head->_idx); slow_head->dump(); 338 } 339 #endif 340 341 return slow_head->as_Loop(); 342 } 343 344 CountedLoopReserveKit::CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active = true) : 345 _phase(phase), 346 _lpt(loop), 347 _lp(NULL), 348 _iff(NULL), 349 _lp_reserved(NULL), 350 _has_reserved(false), 351 _use_new(false), 352 _active(active) 353 { 354 create_reserve(); 355 }; 356 357 CountedLoopReserveKit::~CountedLoopReserveKit() { 358 if (!_active) { 359 return; 360 } 361 362 if (_has_reserved && !_use_new) { 363 // intcon(0)->iff-node reverts CF to the reserved copy 364 ConINode* const_0 = _phase->_igvn.intcon(0); 365 _phase->set_ctrl(const_0, _phase->C->root()); 366 _iff->set_req(1, const_0); 367 368 #ifndef PRODUCT 369 if (TraceLoopOpts) { 370 tty->print_cr("CountedLoopReserveKit::~CountedLoopReserveKit()"); 371 tty->print("\t discard loop %d and revert to the reserved loop clone %d: ", _lp->_idx, _lp_reserved->_idx); 372 _lp_reserved->dump(); 373 } 374 #endif 375 } 376 } 377 378 bool CountedLoopReserveKit::create_reserve() { 379 if (!_active) { 380 return false; 381 } 382 383 if(!_lpt->_head->is_CountedLoop()) { 384 if (TraceLoopOpts) { 385 tty->print_cr("CountedLoopReserveKit::create_reserve: %d not counted loop", _lpt->_head->_idx); 386 } 387 return false; 388 } 389 CountedLoopNode *cl = _lpt->_head->as_CountedLoop(); 390 if (!cl->is_valid_counted_loop()) { 391 if (TraceLoopOpts) { 392 tty->print_cr("CountedLoopReserveKit::create_reserve: %d not valid counted loop", cl->_idx); 393 } 394 return false; // skip malformed counted loop 395 } 396 if (!cl->is_main_loop()) { 397 bool loop_not_canonical = true; 398 if (cl->is_post_loop() && (cl->slp_max_unroll() > 0)) { 399 loop_not_canonical = false; 400 } 401 // only reject some loop forms 402 if (loop_not_canonical) { 403 if (TraceLoopOpts) { 404 tty->print_cr("CountedLoopReserveKit::create_reserve: %d not canonical loop", cl->_idx); 405 } 406 return false; // skip normal, pre, and post (conditionally) loops 407 } 408 } 409 410 _lp = _lpt->_head->as_Loop(); 411 _lp_reserved = _phase->create_reserve_version_of_loop(_lpt, this); 412 413 if (!_lp_reserved->is_CountedLoop()) { 414 return false; 415 } 416 417 Node* ifslow_pred = _lp_reserved->skip_strip_mined()->in(LoopNode::EntryControl); 418 419 if (!ifslow_pred->is_IfFalse()) { 420 return false; 421 } 422 423 Node* iff = ifslow_pred->in(0); 424 if (!iff->is_If() || iff != _iff) { 425 return false; 426 } 427 428 if (iff->in(1)->Opcode() != Op_ConI) { 429 return false; 430 } 431 432 return _has_reserved = true; 433 } --- EOF ---