1 /* 2 * Copyright (c) 1999, 2012, 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/callnode.hpp" 28 #include "opto/loopnode.hpp" 29 #include "opto/movenode.hpp" 30 31 32 //------------------------------split_thru_region------------------------------ 33 // Split Node 'n' through merge point. 34 Node *PhaseIdealLoop::split_thru_region( Node *n, Node *region ) { 35 assert(n->Opcode() != Op_ShenandoahWriteBarrier, "not with write barriers"); 36 uint wins = 0; 37 assert( n->is_CFG(), "" ); 38 assert( region->is_Region(), "" ); 39 Node *r = new RegionNode( region->req() ); 40 IdealLoopTree *loop = get_loop( n ); 41 for( uint i = 1; i < region->req(); i++ ) { 42 Node *x = n->clone(); 43 Node *in0 = n->in(0); 44 if( in0->in(0) == region ) x->set_req( 0, in0->in(i) ); 45 for( uint j = 1; j < n->req(); j++ ) { 46 Node *in = n->in(j); 47 if( get_ctrl(in) == region ) 48 x->set_req( j, in->in(i) ); 49 } 50 _igvn.register_new_node_with_optimizer(x); 51 set_loop(x, loop); 52 set_idom(x, x->in(0), dom_depth(x->in(0))+1); 53 r->init_req(i, x); 54 } 55 56 // Record region 57 r->set_req(0,region); // Not a TRUE RegionNode 58 _igvn.register_new_node_with_optimizer(r); 59 set_loop(r, loop); 60 if( !loop->_child ) 61 loop->_body.push(r); 62 return r; 63 } 64 65 //------------------------------split_up--------------------------------------- 66 // Split block-local op up through the phis to empty the current block 67 bool PhaseIdealLoop::split_up( Node *n, Node *blk1, Node *blk2 ) { 68 if( n->is_CFG() ) { 69 assert( n->in(0) != blk1, "Lousy candidate for split-if" ); 70 return false; 71 } 72 if( get_ctrl(n) != blk1 && get_ctrl(n) != blk2 ) 73 return false; // Not block local 74 if( n->is_Phi() ) return false; // Local PHIs are expected 75 76 // Recursively split-up inputs 77 uint first_input = n->Opcode() == Op_ShenandoahWBMemProj ? 0 : 1; 78 for (uint i = first_input; i < n->req(); i++) { 79 if( split_up( n->in(i), blk1, blk2 ) ) { 80 // Got split recursively and self went dead? 81 if (n->outcnt() == 0) 82 _igvn.remove_dead_node(n); 83 return true; 84 } 85 } 86 87 // Check for needing to clone-up a compare. Can't do that, it forces 88 // another (nested) split-if transform. Instead, clone it "down". 89 if( n->is_Cmp() ) { 90 assert(get_ctrl(n) == blk2 || get_ctrl(n) == blk1, "must be in block with IF"); 91 // Check for simple Cmp/Bool/CMove which we can clone-up. Cmp/Bool/CMove 92 // sequence can have no other users and it must all reside in the split-if 93 // block. Non-simple Cmp/Bool/CMove sequences are 'cloned-down' below - 94 // private, per-use versions of the Cmp and Bool are made. These sink to 95 // the CMove block. If the CMove is in the split-if block, then in the 96 // next iteration this will become a simple Cmp/Bool/CMove set to clone-up. 97 Node *bol, *cmov; 98 if( !(n->outcnt() == 1 && n->unique_out()->is_Bool() && 99 (bol = n->unique_out()->as_Bool()) && 100 (get_ctrl(bol) == blk1 || 101 get_ctrl(bol) == blk2) && 102 bol->outcnt() == 1 && 103 bol->unique_out()->is_CMove() && 104 (cmov = bol->unique_out()->as_CMove()) && 105 (get_ctrl(cmov) == blk1 || 106 get_ctrl(cmov) == blk2) ) ) { 107 108 // Must clone down 109 #ifndef PRODUCT 110 if( PrintOpto && VerifyLoopOptimizations ) { 111 tty->print("Cloning down: "); 112 n->dump(); 113 } 114 #endif 115 // Clone down any block-local BoolNode uses of this CmpNode 116 for (DUIterator i = n->outs(); n->has_out(i); i++) { 117 Node* bol = n->out(i); 118 assert( bol->is_Bool(), "" ); 119 if (bol->outcnt() == 1) { 120 Node* use = bol->unique_out(); 121 Node *use_c = use->is_If() ? use->in(0) : get_ctrl(use); 122 if (use_c == blk1 || use_c == blk2) { 123 continue; 124 } 125 } 126 if (get_ctrl(bol) == blk1 || get_ctrl(bol) == blk2) { 127 // Recursively sink any BoolNode 128 #ifndef PRODUCT 129 if( PrintOpto && VerifyLoopOptimizations ) { 130 tty->print("Cloning down: "); 131 bol->dump(); 132 } 133 #endif 134 for (DUIterator_Last jmin, j = bol->last_outs(jmin); j >= jmin; --j) { 135 // Uses are either IfNodes or CMoves 136 Node* iff = bol->last_out(j); 137 assert( iff->in(1) == bol, "" ); 138 // Get control block of either the CMove or the If input 139 Node *iff_ctrl = iff->is_If() ? iff->in(0) : get_ctrl(iff); 140 Node *x = bol->clone(); 141 register_new_node(x, iff_ctrl); 142 _igvn.replace_input_of(iff, 1, x); 143 } 144 _igvn.remove_dead_node( bol ); 145 --i; 146 } 147 } 148 // Clone down this CmpNode 149 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; --j) { 150 Node* bol = n->last_out(j); 151 assert( bol->in(1) == n, "" ); 152 Node *x = n->clone(); 153 register_new_node(x, get_ctrl(bol)); 154 _igvn.replace_input_of(bol, 1, x); 155 } 156 _igvn.remove_dead_node( n ); 157 158 return true; 159 } 160 } 161 162 // See if splitting-up a Store. Any anti-dep loads must go up as 163 // well. An anti-dep load might be in the wrong block, because in 164 // this particular layout/schedule we ignored anti-deps and allow 165 // memory to be alive twice. This only works if we do the same 166 // operations on anti-dep loads as we do their killing stores. 167 if( n->is_Store() && n->in(MemNode::Memory)->in(0) == n->in(0) ) { 168 // Get store's memory slice 169 int alias_idx = C->get_alias_index(_igvn.type(n->in(MemNode::Address))->is_ptr()); 170 171 // Get memory-phi anti-dep loads will be using 172 Node *memphi = n->in(MemNode::Memory); 173 assert( memphi->is_Phi(), "" ); 174 // Hoist any anti-dep load to the splitting block; 175 // it will then "split-up". 176 for (DUIterator_Fast imax,i = memphi->fast_outs(imax); i < imax; i++) { 177 Node *load = memphi->fast_out(i); 178 if( load->is_Load() && alias_idx == C->get_alias_index(_igvn.type(load->in(MemNode::Address))->is_ptr()) ) 179 set_ctrl(load,blk1); 180 } 181 } 182 183 // Found some other Node; must clone it up 184 #ifndef PRODUCT 185 if( PrintOpto && VerifyLoopOptimizations ) { 186 tty->print("Cloning up: "); 187 n->dump(); 188 } 189 #endif 190 191 // ConvI2L may have type information on it which becomes invalid if 192 // it moves up in the graph so change any clones so widen the type 193 // to TypeLong::INT when pushing it up. 194 const Type* rtype = NULL; 195 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::INT) { 196 rtype = TypeLong::INT; 197 } 198 199 // Now actually split-up this guy. One copy per control path merging. 200 Node *phi = PhiNode::make_blank(blk1, n); 201 for( uint j = 1; j < blk1->req(); j++ ) { 202 Node *x = n->clone(); 203 // Widen the type of the ConvI2L when pushing up. 204 if (rtype != NULL) x->as_Type()->set_type(rtype); 205 if( n->in(0) && n->in(0) == blk1 ) 206 x->set_req( 0, blk1->in(j) ); 207 for( uint i = 1; i < n->req(); i++ ) { 208 Node *m = n->in(i); 209 if( get_ctrl(m) == blk1 ) { 210 assert( m->in(0) == blk1, "" ); 211 x->set_req( i, m->in(j) ); 212 } 213 } 214 register_new_node( x, blk1->in(j) ); 215 phi->init_req( j, x ); 216 } 217 // Announce phi to optimizer 218 register_new_node(phi, blk1); 219 220 // Remove cloned-up value from optimizer; use phi instead 221 split_mem_thru_phi(n, blk1, phi); 222 _igvn.replace_node( n, phi ); 223 224 // (There used to be a self-recursive call to split_up() here, 225 // but it is not needed. All necessary forward walking is done 226 // by do_split_if() below.) 227 228 return true; 229 } 230 231 //------------------------------register_new_node------------------------------ 232 void PhaseIdealLoop::register_new_node( Node *n, Node *blk ) { 233 assert(!n->is_CFG(), "must be data node"); 234 _igvn.register_new_node_with_optimizer(n); 235 set_ctrl(n, blk); 236 IdealLoopTree *loop = get_loop(blk); 237 if( !loop->_child ) 238 loop->_body.push(n); 239 } 240 241 //------------------------------small_cache------------------------------------ 242 struct small_cache : public Dict { 243 244 small_cache() : Dict( cmpkey, hashptr ) {} 245 Node *probe( Node *use_blk ) { return (Node*)((*this)[use_blk]); } 246 void lru_insert( Node *use_blk, Node *new_def ) { Insert(use_blk,new_def); } 247 }; 248 249 //------------------------------spinup----------------------------------------- 250 // "Spin up" the dominator tree, starting at the use site and stopping when we 251 // find the post-dominating point. 252 253 // We must be at the merge point which post-dominates 'new_false' and 254 // 'new_true'. Figure out which edges into the RegionNode eventually lead up 255 // to false and which to true. Put in a PhiNode to merge values; plug in 256 // the appropriate false-arm or true-arm values. If some path leads to the 257 // original IF, then insert a Phi recursively. 258 Node *PhaseIdealLoop::spinup( Node *iff_dom, Node *new_false, Node *new_true, Node *use_blk, Node *def, small_cache *cache ) { 259 if (use_blk->is_top()) // Handle dead uses 260 return use_blk; 261 Node *prior_n = (Node*)0xdeadbeef; 262 Node *n = use_blk; // Get path input 263 assert( use_blk != iff_dom, "" ); 264 // Here's the "spinup" the dominator tree loop. Do a cache-check 265 // along the way, in case we've come this way before. 266 while( n != iff_dom ) { // Found post-dominating point? 267 prior_n = n; 268 n = idom(n); // Search higher 269 Node *s = cache->probe( prior_n ); // Check cache 270 if( s ) return s; // Cache hit! 271 } 272 273 Node *phi_post; 274 if( prior_n == new_false || prior_n == new_true ) { 275 phi_post = def->clone(); 276 phi_post->set_req(0, prior_n ); 277 register_new_node(phi_post, prior_n); 278 } else { 279 // This method handles both control uses (looking for Regions) or data 280 // uses (looking for Phis). If looking for a control use, then we need 281 // to insert a Region instead of a Phi; however Regions always exist 282 // previously (the hash_find_insert below would always hit) so we can 283 // return the existing Region. 284 if( def->is_CFG() ) { 285 phi_post = prior_n; // If looking for CFG, return prior 286 } else { 287 assert( def->is_Phi(), "" ); 288 assert( prior_n->is_Region(), "must be a post-dominating merge point" ); 289 290 // Need a Phi here 291 phi_post = PhiNode::make_blank(prior_n, def); 292 // Search for both true and false on all paths till find one. 293 for( uint i = 1; i < phi_post->req(); i++ ) // For all paths 294 phi_post->init_req( i, spinup( iff_dom, new_false, new_true, prior_n->in(i), def, cache ) ); 295 Node *t = _igvn.hash_find_insert(phi_post); 296 if( t ) { // See if we already have this one 297 // phi_post will not be used, so kill it 298 _igvn.remove_dead_node(phi_post); 299 phi_post->destruct(); 300 phi_post = t; 301 } else { 302 register_new_node( phi_post, prior_n ); 303 } 304 } 305 } 306 307 // Update cache everywhere 308 prior_n = (Node*)0xdeadbeef; // Reset IDOM walk 309 n = use_blk; // Get path input 310 // Spin-up the idom tree again, basically doing path-compression. 311 // Insert cache entries along the way, so that if we ever hit this 312 // point in the IDOM tree again we'll stop immediately on a cache hit. 313 while( n != iff_dom ) { // Found post-dominating point? 314 prior_n = n; 315 n = idom(n); // Search higher 316 cache->lru_insert( prior_n, phi_post ); // Fill cache 317 } // End of while not gone high enough 318 319 return phi_post; 320 } 321 322 //------------------------------find_use_block--------------------------------- 323 // Find the block a USE is in. Normally USE's are in the same block as the 324 // using instruction. For Phi-USE's, the USE is in the predecessor block 325 // along the corresponding path. 326 Node *PhaseIdealLoop::find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ) { 327 // CFG uses are their own block 328 if( use->is_CFG() ) 329 return use; 330 331 if( use->is_Phi() ) { // Phi uses in prior block 332 // Grab the first Phi use; there may be many. 333 // Each will be handled as a separate iteration of 334 // the "while( phi->outcnt() )" loop. 335 uint j; 336 for( j = 1; j < use->req(); j++ ) 337 if( use->in(j) == def ) 338 break; 339 assert( j < use->req(), "def should be among use's inputs" ); 340 return use->in(0)->in(j); 341 } 342 // Normal (non-phi) use 343 Node *use_blk = get_ctrl(use); 344 // Some uses are directly attached to the old (and going away) 345 // false and true branches. 346 if( use_blk == old_false ) { 347 use_blk = new_false; 348 set_ctrl(use, new_false); 349 } 350 if( use_blk == old_true ) { 351 use_blk = new_true; 352 set_ctrl(use, new_true); 353 } 354 355 if (use_blk == NULL) { // He's dead, Jim 356 _igvn.replace_node(use, C->top()); 357 } 358 359 return use_blk; 360 } 361 362 //------------------------------handle_use------------------------------------- 363 // Handle uses of the merge point. Basically, split-if makes the merge point 364 // go away so all uses of the merge point must go away as well. Most block 365 // local uses have already been split-up, through the merge point. Uses from 366 // far below the merge point can't always be split up (e.g., phi-uses are 367 // pinned) and it makes too much stuff live. Instead we use a path-based 368 // solution to move uses down. 369 // 370 // If the use is along the pre-split-CFG true branch, then the new use will 371 // be from the post-split-CFG true merge point. Vice-versa for the false 372 // path. Some uses will be along both paths; then we sink the use to the 373 // post-dominating location; we may need to insert a Phi there. 374 void PhaseIdealLoop::handle_use( Node *use, Node *def, small_cache *cache, Node *region_dom, Node *new_false, Node *new_true, Node *old_false, Node *old_true ) { 375 376 Node *use_blk = find_use_block(use,def,old_false,new_false,old_true,new_true); 377 if( !use_blk ) return; // He's dead, Jim 378 379 // Walk up the dominator tree until I hit either the old IfFalse, the old 380 // IfTrue or the old If. Insert Phis where needed. 381 Node *new_def = spinup( region_dom, new_false, new_true, use_blk, def, cache ); 382 383 // Found where this USE goes. Re-point him. 384 uint i; 385 for( i = 0; i < use->req(); i++ ) 386 if( use->in(i) == def ) 387 break; 388 assert( i < use->req(), "def should be among use's inputs" ); 389 _igvn.replace_input_of(use, i, new_def); 390 } 391 392 //------------------------------do_split_if------------------------------------ 393 // Found an If getting its condition-code input from a Phi in the same block. 394 // Split thru the Region. 395 void PhaseIdealLoop::do_split_if( Node *iff ) { 396 #ifndef PRODUCT 397 if( PrintOpto && VerifyLoopOptimizations ) 398 tty->print_cr("Split-if"); 399 if (TraceLoopOpts) { 400 tty->print_cr("SplitIf"); 401 } 402 #endif 403 C->set_major_progress(); 404 Node *region = iff->in(0); 405 Node *region_dom = idom(region); 406 407 // We are going to clone this test (and the control flow with it) up through 408 // the incoming merge point. We need to empty the current basic block. 409 // Clone any instructions which must be in this block up through the merge 410 // point. 411 DUIterator i, j; 412 bool progress = true; 413 while (progress) { 414 progress = false; 415 for (i = region->outs(); region->has_out(i); i++) { 416 Node* n = region->out(i); 417 if( n == region ) continue; 418 // The IF to be split is OK. 419 if( n == iff ) continue; 420 if( !n->is_Phi() ) { // Found pinned memory op or such 421 if (split_up(n, region, iff)) { 422 i = region->refresh_out_pos(i); 423 progress = true; 424 } 425 continue; 426 } 427 assert( n->in(0) == region, "" ); 428 429 // Recursively split up all users of a Phi 430 for (j = n->outs(); n->has_out(j); j++) { 431 Node* m = n->out(j); 432 // If m is dead, throw it away, and declare progress 433 if (_nodes[m->_idx] == NULL) { 434 _igvn.remove_dead_node(m); 435 // fall through 436 } 437 else if (m != iff && split_up(m, region, iff)) { 438 // fall through 439 } else { 440 continue; 441 } 442 // Something unpredictable changed. 443 // Tell the iterators to refresh themselves, and rerun the loop. 444 i = region->refresh_out_pos(i); 445 j = region->refresh_out_pos(j); 446 progress = true; 447 } 448 } 449 } 450 451 // Now we have no instructions in the block containing the IF. 452 // Split the IF. 453 Node *new_iff = split_thru_region( iff, region ); 454 455 // Replace both uses of 'new_iff' with Regions merging True/False 456 // paths. This makes 'new_iff' go dead. 457 Node *old_false, *old_true; 458 Node *new_false, *new_true; 459 for (DUIterator_Last j2min, j2 = iff->last_outs(j2min); j2 >= j2min; --j2) { 460 Node *ifp = iff->last_out(j2); 461 assert( ifp->Opcode() == Op_IfFalse || ifp->Opcode() == Op_IfTrue, "" ); 462 ifp->set_req(0, new_iff); 463 Node *ifpx = split_thru_region( ifp, region ); 464 465 // Replace 'If' projection of a Region with a Region of 466 // 'If' projections. 467 ifpx->set_req(0, ifpx); // A TRUE RegionNode 468 469 // Setup dominator info 470 set_idom(ifpx, region_dom, dom_depth(region_dom) + 1); 471 472 // Check for splitting loop tails 473 if( get_loop(iff)->tail() == ifp ) 474 get_loop(iff)->_tail = ifpx; 475 476 // Replace in the graph with lazy-update mechanism 477 new_iff->set_req(0, new_iff); // hook self so it does not go dead 478 lazy_replace_proj( ifp, ifpx ); 479 new_iff->set_req(0, region); 480 481 // Record bits for later xforms 482 if( ifp->Opcode() == Op_IfFalse ) { 483 old_false = ifp; 484 new_false = ifpx; 485 } else { 486 old_true = ifp; 487 new_true = ifpx; 488 } 489 } 490 _igvn.remove_dead_node(new_iff); 491 // Lazy replace IDOM info with the region's dominator 492 lazy_replace( iff, region_dom ); 493 494 // Now make the original merge point go dead, by handling all its uses. 495 small_cache region_cache; 496 // Preload some control flow in region-cache 497 region_cache.lru_insert( new_false, new_false ); 498 region_cache.lru_insert( new_true , new_true ); 499 // Now handle all uses of the splitting block 500 for (DUIterator k = region->outs(); region->has_out(k); k++) { 501 Node* phi = region->out(k); 502 if (!phi->in(0)) { // Dead phi? Remove it 503 _igvn.remove_dead_node(phi); 504 } else if (phi == region) { // Found the self-reference 505 continue; // No roll-back of DUIterator 506 } else if (phi->is_Phi()) { // Expected common case: Phi hanging off of Region 507 assert(phi->in(0) == region, "Inconsistent graph"); 508 // Need a per-def cache. Phi represents a def, so make a cache 509 small_cache phi_cache; 510 511 // Inspect all Phi uses to make the Phi go dead 512 for (DUIterator_Last lmin, l = phi->last_outs(lmin); l >= lmin; --l) { 513 Node* use = phi->last_out(l); 514 // Compute the new DEF for this USE. New DEF depends on the path 515 // taken from the original DEF to the USE. The new DEF may be some 516 // collection of PHI's merging values from different paths. The Phis 517 // inserted depend only on the location of the USE. We use a 518 // 2-element cache to handle multiple uses from the same block. 519 handle_use(use, phi, &phi_cache, region_dom, new_false, new_true, old_false, old_true); 520 } // End of while phi has uses 521 // Remove the dead Phi 522 _igvn.remove_dead_node( phi ); 523 } else { 524 assert(phi->in(0) == region, "Inconsistent graph"); 525 // Random memory op guarded by Region. Compute new DEF for USE. 526 handle_use(phi, region, ®ion_cache, region_dom, new_false, new_true, old_false, old_true); 527 } 528 // Every path above deletes a use of the region, except for the region 529 // self-cycle (which is needed by handle_use calling find_use_block 530 // calling get_ctrl calling get_ctrl_no_update looking for dead 531 // regions). So roll back the DUIterator innards. 532 --k; 533 } // End of while merge point has phis 534 535 assert(region->outcnt() == 1, "Only self reference should remain"); // Just Self on the Region 536 region->set_req(0, NULL); // Break the self-cycle 537 538 // Any leftover bits in the splitting block must not have depended on local 539 // Phi inputs (these have already been split-up). Hence it's safe to hoist 540 // these guys to the dominating point. 541 lazy_replace( region, region_dom ); 542 #ifndef PRODUCT 543 if( VerifyLoopOptimizations ) verify(); 544 #endif 545 }