1 /* 2 * Copyright (c) 1997, 2009, 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 // Portions of code courtesy of Clifford Click 26 27 // Optimization - Graph Style 28 29 #include "incls/_precompiled.incl" 30 #include "incls/_gcm.cpp.incl" 31 32 // To avoid float value underflow 33 #define MIN_BLOCK_FREQUENCY 1.e-35f 34 35 //----------------------------schedule_node_into_block------------------------- 36 // Insert node n into block b. Look for projections of n and make sure they 37 // are in b also. 38 void PhaseCFG::schedule_node_into_block( Node *n, Block *b ) { 39 // Set basic block of n, Add n to b, 40 _bbs.map(n->_idx, b); 41 b->add_inst(n); 42 43 // After Matching, nearly any old Node may have projections trailing it. 44 // These are usually machine-dependent flags. In any case, they might 45 // float to another block below this one. Move them up. 46 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { 47 Node* use = n->fast_out(i); 48 if (use->is_Proj()) { 49 Block* buse = _bbs[use->_idx]; 50 if (buse != b) { // In wrong block? 51 if (buse != NULL) 52 buse->find_remove(use); // Remove from wrong block 53 _bbs.map(use->_idx, b); // Re-insert in this block 54 b->add_inst(use); 55 } 56 } 57 } 58 } 59 60 //----------------------------replace_block_proj_ctrl------------------------- 61 // Nodes that have is_block_proj() nodes as their control need to use 62 // the appropriate Region for their actual block as their control since 63 // the projection will be in a predecessor block. 64 void PhaseCFG::replace_block_proj_ctrl( Node *n ) { 65 const Node *in0 = n->in(0); 66 assert(in0 != NULL, "Only control-dependent"); 67 const Node *p = in0->is_block_proj(); 68 if (p != NULL && p != n) { // Control from a block projection? 69 assert(!n->pinned() || n->is_SafePointScalarObject(), "only SafePointScalarObject pinned node is expected here"); 70 // Find trailing Region 71 Block *pb = _bbs[in0->_idx]; // Block-projection already has basic block 72 uint j = 0; 73 if (pb->_num_succs != 1) { // More then 1 successor? 74 // Search for successor 75 uint max = pb->_nodes.size(); 76 assert( max > 1, "" ); 77 uint start = max - pb->_num_succs; 78 // Find which output path belongs to projection 79 for (j = start; j < max; j++) { 80 if( pb->_nodes[j] == in0 ) 81 break; 82 } 83 assert( j < max, "must find" ); 84 // Change control to match head of successor basic block 85 j -= start; 86 } 87 n->set_req(0, pb->_succs[j]->head()); 88 } 89 } 90 91 92 //------------------------------schedule_pinned_nodes-------------------------- 93 // Set the basic block for Nodes pinned into blocks 94 void PhaseCFG::schedule_pinned_nodes( VectorSet &visited ) { 95 // Allocate node stack of size C->unique()+8 to avoid frequent realloc 96 GrowableArray <Node *> spstack(C->unique()+8); 97 spstack.push(_root); 98 while ( spstack.is_nonempty() ) { 99 Node *n = spstack.pop(); 100 if( !visited.test_set(n->_idx) ) { // Test node and flag it as visited 101 if( n->pinned() && !_bbs.lookup(n->_idx) ) { // Pinned? Nail it down! 102 assert( n->in(0), "pinned Node must have Control" ); 103 // Before setting block replace block_proj control edge 104 replace_block_proj_ctrl(n); 105 Node *input = n->in(0); 106 while( !input->is_block_start() ) 107 input = input->in(0); 108 Block *b = _bbs[input->_idx]; // Basic block of controlling input 109 schedule_node_into_block(n, b); 110 } 111 for( int i = n->req() - 1; i >= 0; --i ) { // For all inputs 112 if( n->in(i) != NULL ) 113 spstack.push(n->in(i)); 114 } 115 } 116 } 117 } 118 119 #ifdef ASSERT 120 // Assert that new input b2 is dominated by all previous inputs. 121 // Check this by by seeing that it is dominated by b1, the deepest 122 // input observed until b2. 123 static void assert_dom(Block* b1, Block* b2, Node* n, Block_Array &bbs) { 124 if (b1 == NULL) return; 125 assert(b1->_dom_depth < b2->_dom_depth, "sanity"); 126 Block* tmp = b2; 127 while (tmp != b1 && tmp != NULL) { 128 tmp = tmp->_idom; 129 } 130 if (tmp != b1) { 131 // Detected an unschedulable graph. Print some nice stuff and die. 132 tty->print_cr("!!! Unschedulable graph !!!"); 133 for (uint j=0; j<n->len(); j++) { // For all inputs 134 Node* inn = n->in(j); // Get input 135 if (inn == NULL) continue; // Ignore NULL, missing inputs 136 Block* inb = bbs[inn->_idx]; 137 tty->print("B%d idom=B%d depth=%2d ",inb->_pre_order, 138 inb->_idom ? inb->_idom->_pre_order : 0, inb->_dom_depth); 139 inn->dump(); 140 } 141 tty->print("Failing node: "); 142 n->dump(); 143 assert(false, "unscheduable graph"); 144 } 145 } 146 #endif 147 148 static Block* find_deepest_input(Node* n, Block_Array &bbs) { 149 // Find the last input dominated by all other inputs. 150 Block* deepb = NULL; // Deepest block so far 151 int deepb_dom_depth = 0; 152 for (uint k = 0; k < n->len(); k++) { // For all inputs 153 Node* inn = n->in(k); // Get input 154 if (inn == NULL) continue; // Ignore NULL, missing inputs 155 Block* inb = bbs[inn->_idx]; 156 assert(inb != NULL, "must already have scheduled this input"); 157 if (deepb_dom_depth < (int) inb->_dom_depth) { 158 // The new inb must be dominated by the previous deepb. 159 // The various inputs must be linearly ordered in the dom 160 // tree, or else there will not be a unique deepest block. 161 DEBUG_ONLY(assert_dom(deepb, inb, n, bbs)); 162 deepb = inb; // Save deepest block 163 deepb_dom_depth = deepb->_dom_depth; 164 } 165 } 166 assert(deepb != NULL, "must be at least one input to n"); 167 return deepb; 168 } 169 170 171 //------------------------------schedule_early--------------------------------- 172 // Find the earliest Block any instruction can be placed in. Some instructions 173 // are pinned into Blocks. Unpinned instructions can appear in last block in 174 // which all their inputs occur. 175 bool PhaseCFG::schedule_early(VectorSet &visited, Node_List &roots) { 176 // Allocate stack with enough space to avoid frequent realloc 177 Node_Stack nstack(roots.Size() + 8); // (unique >> 1) + 24 from Java2D stats 178 // roots.push(_root); _root will be processed among C->top() inputs 179 roots.push(C->top()); 180 visited.set(C->top()->_idx); 181 182 while (roots.size() != 0) { 183 // Use local variables nstack_top_n & nstack_top_i to cache values 184 // on stack's top. 185 Node *nstack_top_n = roots.pop(); 186 uint nstack_top_i = 0; 187 //while_nstack_nonempty: 188 while (true) { 189 // Get parent node and next input's index from stack's top. 190 Node *n = nstack_top_n; 191 uint i = nstack_top_i; 192 193 if (i == 0) { 194 // Fixup some control. Constants without control get attached 195 // to root and nodes that use is_block_proj() nodes should be attached 196 // to the region that starts their block. 197 const Node *in0 = n->in(0); 198 if (in0 != NULL) { // Control-dependent? 199 replace_block_proj_ctrl(n); 200 } else { // n->in(0) == NULL 201 if (n->req() == 1) { // This guy is a constant with NO inputs? 202 n->set_req(0, _root); 203 } 204 } 205 } 206 207 // First, visit all inputs and force them to get a block. If an 208 // input is already in a block we quit following inputs (to avoid 209 // cycles). Instead we put that Node on a worklist to be handled 210 // later (since IT'S inputs may not have a block yet). 211 bool done = true; // Assume all n's inputs will be processed 212 while (i < n->len()) { // For all inputs 213 Node *in = n->in(i); // Get input 214 ++i; 215 if (in == NULL) continue; // Ignore NULL, missing inputs 216 int is_visited = visited.test_set(in->_idx); 217 if (!_bbs.lookup(in->_idx)) { // Missing block selection? 218 if (is_visited) { 219 // assert( !visited.test(in->_idx), "did not schedule early" ); 220 return false; 221 } 222 nstack.push(n, i); // Save parent node and next input's index. 223 nstack_top_n = in; // Process current input now. 224 nstack_top_i = 0; 225 done = false; // Not all n's inputs processed. 226 break; // continue while_nstack_nonempty; 227 } else if (!is_visited) { // Input not yet visited? 228 roots.push(in); // Visit this guy later, using worklist 229 } 230 } 231 if (done) { 232 // All of n's inputs have been processed, complete post-processing. 233 234 // Some instructions are pinned into a block. These include Region, 235 // Phi, Start, Return, and other control-dependent instructions and 236 // any projections which depend on them. 237 if (!n->pinned()) { 238 // Set earliest legal block. 239 _bbs.map(n->_idx, find_deepest_input(n, _bbs)); 240 } else { 241 assert(_bbs[n->_idx] == _bbs[n->in(0)->_idx], "Pinned Node should be at the same block as its control edge"); 242 } 243 244 if (nstack.is_empty()) { 245 // Finished all nodes on stack. 246 // Process next node on the worklist 'roots'. 247 break; 248 } 249 // Get saved parent node and next input's index. 250 nstack_top_n = nstack.node(); 251 nstack_top_i = nstack.index(); 252 nstack.pop(); 253 } // if (done) 254 } // while (true) 255 } // while (roots.size() != 0) 256 return true; 257 } 258 259 //------------------------------dom_lca---------------------------------------- 260 // Find least common ancestor in dominator tree 261 // LCA is a current notion of LCA, to be raised above 'this'. 262 // As a convenient boundary condition, return 'this' if LCA is NULL. 263 // Find the LCA of those two nodes. 264 Block* Block::dom_lca(Block* LCA) { 265 if (LCA == NULL || LCA == this) return this; 266 267 Block* anc = this; 268 while (anc->_dom_depth > LCA->_dom_depth) 269 anc = anc->_idom; // Walk up till anc is as high as LCA 270 271 while (LCA->_dom_depth > anc->_dom_depth) 272 LCA = LCA->_idom; // Walk up till LCA is as high as anc 273 274 while (LCA != anc) { // Walk both up till they are the same 275 LCA = LCA->_idom; 276 anc = anc->_idom; 277 } 278 279 return LCA; 280 } 281 282 //--------------------------raise_LCA_above_use-------------------------------- 283 // We are placing a definition, and have been given a def->use edge. 284 // The definition must dominate the use, so move the LCA upward in the 285 // dominator tree to dominate the use. If the use is a phi, adjust 286 // the LCA only with the phi input paths which actually use this def. 287 static Block* raise_LCA_above_use(Block* LCA, Node* use, Node* def, Block_Array &bbs) { 288 Block* buse = bbs[use->_idx]; 289 if (buse == NULL) return LCA; // Unused killing Projs have no use block 290 if (!use->is_Phi()) return buse->dom_lca(LCA); 291 uint pmax = use->req(); // Number of Phi inputs 292 // Why does not this loop just break after finding the matching input to 293 // the Phi? Well...it's like this. I do not have true def-use/use-def 294 // chains. Means I cannot distinguish, from the def-use direction, which 295 // of many use-defs lead from the same use to the same def. That is, this 296 // Phi might have several uses of the same def. Each use appears in a 297 // different predecessor block. But when I enter here, I cannot distinguish 298 // which use-def edge I should find the predecessor block for. So I find 299 // them all. Means I do a little extra work if a Phi uses the same value 300 // more than once. 301 for (uint j=1; j<pmax; j++) { // For all inputs 302 if (use->in(j) == def) { // Found matching input? 303 Block* pred = bbs[buse->pred(j)->_idx]; 304 LCA = pred->dom_lca(LCA); 305 } 306 } 307 return LCA; 308 } 309 310 //----------------------------raise_LCA_above_marks---------------------------- 311 // Return a new LCA that dominates LCA and any of its marked predecessors. 312 // Search all my parents up to 'early' (exclusive), looking for predecessors 313 // which are marked with the given index. Return the LCA (in the dom tree) 314 // of all marked blocks. If there are none marked, return the original 315 // LCA. 316 static Block* raise_LCA_above_marks(Block* LCA, node_idx_t mark, 317 Block* early, Block_Array &bbs) { 318 Block_List worklist; 319 worklist.push(LCA); 320 while (worklist.size() > 0) { 321 Block* mid = worklist.pop(); 322 if (mid == early) continue; // stop searching here 323 324 // Test and set the visited bit. 325 if (mid->raise_LCA_visited() == mark) continue; // already visited 326 327 // Don't process the current LCA, otherwise the search may terminate early 328 if (mid != LCA && mid->raise_LCA_mark() == mark) { 329 // Raise the LCA. 330 LCA = mid->dom_lca(LCA); 331 if (LCA == early) break; // stop searching everywhere 332 assert(early->dominates(LCA), "early is high enough"); 333 // Resume searching at that point, skipping intermediate levels. 334 worklist.push(LCA); 335 if (LCA == mid) 336 continue; // Don't mark as visited to avoid early termination. 337 } else { 338 // Keep searching through this block's predecessors. 339 for (uint j = 1, jmax = mid->num_preds(); j < jmax; j++) { 340 Block* mid_parent = bbs[ mid->pred(j)->_idx ]; 341 worklist.push(mid_parent); 342 } 343 } 344 mid->set_raise_LCA_visited(mark); 345 } 346 return LCA; 347 } 348 349 //--------------------------memory_early_block-------------------------------- 350 // This is a variation of find_deepest_input, the heart of schedule_early. 351 // Find the "early" block for a load, if we considered only memory and 352 // address inputs, that is, if other data inputs were ignored. 353 // 354 // Because a subset of edges are considered, the resulting block will 355 // be earlier (at a shallower dom_depth) than the true schedule_early 356 // point of the node. We compute this earlier block as a more permissive 357 // site for anti-dependency insertion, but only if subsume_loads is enabled. 358 static Block* memory_early_block(Node* load, Block* early, Block_Array &bbs) { 359 Node* base; 360 Node* index; 361 Node* store = load->in(MemNode::Memory); 362 load->as_Mach()->memory_inputs(base, index); 363 364 assert(base != NodeSentinel && index != NodeSentinel, 365 "unexpected base/index inputs"); 366 367 Node* mem_inputs[4]; 368 int mem_inputs_length = 0; 369 if (base != NULL) mem_inputs[mem_inputs_length++] = base; 370 if (index != NULL) mem_inputs[mem_inputs_length++] = index; 371 if (store != NULL) mem_inputs[mem_inputs_length++] = store; 372 373 // In the comparision below, add one to account for the control input, 374 // which may be null, but always takes up a spot in the in array. 375 if (mem_inputs_length + 1 < (int) load->req()) { 376 // This "load" has more inputs than just the memory, base and index inputs. 377 // For purposes of checking anti-dependences, we need to start 378 // from the early block of only the address portion of the instruction, 379 // and ignore other blocks that may have factored into the wider 380 // schedule_early calculation. 381 if (load->in(0) != NULL) mem_inputs[mem_inputs_length++] = load->in(0); 382 383 Block* deepb = NULL; // Deepest block so far 384 int deepb_dom_depth = 0; 385 for (int i = 0; i < mem_inputs_length; i++) { 386 Block* inb = bbs[mem_inputs[i]->_idx]; 387 if (deepb_dom_depth < (int) inb->_dom_depth) { 388 // The new inb must be dominated by the previous deepb. 389 // The various inputs must be linearly ordered in the dom 390 // tree, or else there will not be a unique deepest block. 391 DEBUG_ONLY(assert_dom(deepb, inb, load, bbs)); 392 deepb = inb; // Save deepest block 393 deepb_dom_depth = deepb->_dom_depth; 394 } 395 } 396 early = deepb; 397 } 398 399 return early; 400 } 401 402 //--------------------------insert_anti_dependences--------------------------- 403 // A load may need to witness memory that nearby stores can overwrite. 404 // For each nearby store, either insert an "anti-dependence" edge 405 // from the load to the store, or else move LCA upward to force the 406 // load to (eventually) be scheduled in a block above the store. 407 // 408 // Do not add edges to stores on distinct control-flow paths; 409 // only add edges to stores which might interfere. 410 // 411 // Return the (updated) LCA. There will not be any possibly interfering 412 // store between the load's "early block" and the updated LCA. 413 // Any stores in the updated LCA will have new precedence edges 414 // back to the load. The caller is expected to schedule the load 415 // in the LCA, in which case the precedence edges will make LCM 416 // preserve anti-dependences. The caller may also hoist the load 417 // above the LCA, if it is not the early block. 418 Block* PhaseCFG::insert_anti_dependences(Block* LCA, Node* load, bool verify) { 419 assert(load->needs_anti_dependence_check(), "must be a load of some sort"); 420 assert(LCA != NULL, ""); 421 DEBUG_ONLY(Block* LCA_orig = LCA); 422 423 // Compute the alias index. Loads and stores with different alias indices 424 // do not need anti-dependence edges. 425 uint load_alias_idx = C->get_alias_index(load->adr_type()); 426 #ifdef ASSERT 427 if (load_alias_idx == Compile::AliasIdxBot && C->AliasLevel() > 0 && 428 (PrintOpto || VerifyAliases || 429 PrintMiscellaneous && (WizardMode || Verbose))) { 430 // Load nodes should not consume all of memory. 431 // Reporting a bottom type indicates a bug in adlc. 432 // If some particular type of node validly consumes all of memory, 433 // sharpen the preceding "if" to exclude it, so we can catch bugs here. 434 tty->print_cr("*** Possible Anti-Dependence Bug: Load consumes all of memory."); 435 load->dump(2); 436 if (VerifyAliases) assert(load_alias_idx != Compile::AliasIdxBot, ""); 437 } 438 #endif 439 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrComp), 440 "String compare is only known 'load' that does not conflict with any stores"); 441 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrEquals), 442 "String equals is a 'load' that does not conflict with any stores"); 443 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrIndexOf), 444 "String indexOf is a 'load' that does not conflict with any stores"); 445 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_AryEq), 446 "Arrays equals is a 'load' that do not conflict with any stores"); 447 448 if (!C->alias_type(load_alias_idx)->is_rewritable()) { 449 // It is impossible to spoil this load by putting stores before it, 450 // because we know that the stores will never update the value 451 // which 'load' must witness. 452 return LCA; 453 } 454 455 node_idx_t load_index = load->_idx; 456 457 // Note the earliest legal placement of 'load', as determined by 458 // by the unique point in the dom tree where all memory effects 459 // and other inputs are first available. (Computed by schedule_early.) 460 // For normal loads, 'early' is the shallowest place (dom graph wise) 461 // to look for anti-deps between this load and any store. 462 Block* early = _bbs[load_index]; 463 464 // If we are subsuming loads, compute an "early" block that only considers 465 // memory or address inputs. This block may be different than the 466 // schedule_early block in that it could be at an even shallower depth in the 467 // dominator tree, and allow for a broader discovery of anti-dependences. 468 if (C->subsume_loads()) { 469 early = memory_early_block(load, early, _bbs); 470 } 471 472 ResourceArea *area = Thread::current()->resource_area(); 473 Node_List worklist_mem(area); // prior memory state to store 474 Node_List worklist_store(area); // possible-def to explore 475 Node_List worklist_visited(area); // visited mergemem nodes 476 Node_List non_early_stores(area); // all relevant stores outside of early 477 bool must_raise_LCA = false; 478 479 #ifdef TRACK_PHI_INPUTS 480 // %%% This extra checking fails because MergeMem nodes are not GVNed. 481 // Provide "phi_inputs" to check if every input to a PhiNode is from the 482 // original memory state. This indicates a PhiNode for which should not 483 // prevent the load from sinking. For such a block, set_raise_LCA_mark 484 // may be overly conservative. 485 // Mechanism: count inputs seen for each Phi encountered in worklist_store. 486 DEBUG_ONLY(GrowableArray<uint> phi_inputs(area, C->unique(),0,0)); 487 #endif 488 489 // 'load' uses some memory state; look for users of the same state. 490 // Recurse through MergeMem nodes to the stores that use them. 491 492 // Each of these stores is a possible definition of memory 493 // that 'load' needs to use. We need to force 'load' 494 // to occur before each such store. When the store is in 495 // the same block as 'load', we insert an anti-dependence 496 // edge load->store. 497 498 // The relevant stores "nearby" the load consist of a tree rooted 499 // at initial_mem, with internal nodes of type MergeMem. 500 // Therefore, the branches visited by the worklist are of this form: 501 // initial_mem -> (MergeMem ->)* store 502 // The anti-dependence constraints apply only to the fringe of this tree. 503 504 Node* initial_mem = load->in(MemNode::Memory); 505 worklist_store.push(initial_mem); 506 worklist_visited.push(initial_mem); 507 worklist_mem.push(NULL); 508 while (worklist_store.size() > 0) { 509 // Examine a nearby store to see if it might interfere with our load. 510 Node* mem = worklist_mem.pop(); 511 Node* store = worklist_store.pop(); 512 uint op = store->Opcode(); 513 514 // MergeMems do not directly have anti-deps. 515 // Treat them as internal nodes in a forward tree of memory states, 516 // the leaves of which are each a 'possible-def'. 517 if (store == initial_mem // root (exclusive) of tree we are searching 518 || op == Op_MergeMem // internal node of tree we are searching 519 ) { 520 mem = store; // It's not a possibly interfering store. 521 if (store == initial_mem) 522 initial_mem = NULL; // only process initial memory once 523 524 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { 525 store = mem->fast_out(i); 526 if (store->is_MergeMem()) { 527 // Be sure we don't get into combinatorial problems. 528 // (Allow phis to be repeated; they can merge two relevant states.) 529 uint j = worklist_visited.size(); 530 for (; j > 0; j--) { 531 if (worklist_visited.at(j-1) == store) break; 532 } 533 if (j > 0) continue; // already on work list; do not repeat 534 worklist_visited.push(store); 535 } 536 worklist_mem.push(mem); 537 worklist_store.push(store); 538 } 539 continue; 540 } 541 542 if (op == Op_MachProj || op == Op_Catch) continue; 543 if (store->needs_anti_dependence_check()) continue; // not really a store 544 545 // Compute the alias index. Loads and stores with different alias 546 // indices do not need anti-dependence edges. Wide MemBar's are 547 // anti-dependent on everything (except immutable memories). 548 const TypePtr* adr_type = store->adr_type(); 549 if (!C->can_alias(adr_type, load_alias_idx)) continue; 550 551 // Most slow-path runtime calls do NOT modify Java memory, but 552 // they can block and so write Raw memory. 553 if (store->is_Mach()) { 554 MachNode* mstore = store->as_Mach(); 555 if (load_alias_idx != Compile::AliasIdxRaw) { 556 // Check for call into the runtime using the Java calling 557 // convention (and from there into a wrapper); it has no 558 // _method. Can't do this optimization for Native calls because 559 // they CAN write to Java memory. 560 if (mstore->ideal_Opcode() == Op_CallStaticJava) { 561 assert(mstore->is_MachSafePoint(), ""); 562 MachSafePointNode* ms = (MachSafePointNode*) mstore; 563 assert(ms->is_MachCallJava(), ""); 564 MachCallJavaNode* mcj = (MachCallJavaNode*) ms; 565 if (mcj->_method == NULL) { 566 // These runtime calls do not write to Java visible memory 567 // (other than Raw) and so do not require anti-dependence edges. 568 continue; 569 } 570 } 571 // Same for SafePoints: they read/write Raw but only read otherwise. 572 // This is basically a workaround for SafePoints only defining control 573 // instead of control + memory. 574 if (mstore->ideal_Opcode() == Op_SafePoint) 575 continue; 576 } else { 577 // Some raw memory, such as the load of "top" at an allocation, 578 // can be control dependent on the previous safepoint. See 579 // comments in GraphKit::allocate_heap() about control input. 580 // Inserting an anti-dep between such a safepoint and a use 581 // creates a cycle, and will cause a subsequent failure in 582 // local scheduling. (BugId 4919904) 583 // (%%% How can a control input be a safepoint and not a projection??) 584 if (mstore->ideal_Opcode() == Op_SafePoint && load->in(0) == mstore) 585 continue; 586 } 587 } 588 589 // Identify a block that the current load must be above, 590 // or else observe that 'store' is all the way up in the 591 // earliest legal block for 'load'. In the latter case, 592 // immediately insert an anti-dependence edge. 593 Block* store_block = _bbs[store->_idx]; 594 assert(store_block != NULL, "unused killing projections skipped above"); 595 596 if (store->is_Phi()) { 597 // 'load' uses memory which is one (or more) of the Phi's inputs. 598 // It must be scheduled not before the Phi, but rather before 599 // each of the relevant Phi inputs. 600 // 601 // Instead of finding the LCA of all inputs to a Phi that match 'mem', 602 // we mark each corresponding predecessor block and do a combined 603 // hoisting operation later (raise_LCA_above_marks). 604 // 605 // Do not assert(store_block != early, "Phi merging memory after access") 606 // PhiNode may be at start of block 'early' with backedge to 'early' 607 DEBUG_ONLY(bool found_match = false); 608 for (uint j = PhiNode::Input, jmax = store->req(); j < jmax; j++) { 609 if (store->in(j) == mem) { // Found matching input? 610 DEBUG_ONLY(found_match = true); 611 Block* pred_block = _bbs[store_block->pred(j)->_idx]; 612 if (pred_block != early) { 613 // If any predecessor of the Phi matches the load's "early block", 614 // we do not need a precedence edge between the Phi and 'load' 615 // since the load will be forced into a block preceding the Phi. 616 pred_block->set_raise_LCA_mark(load_index); 617 assert(!LCA_orig->dominates(pred_block) || 618 early->dominates(pred_block), "early is high enough"); 619 must_raise_LCA = true; 620 } else { 621 // anti-dependent upon PHI pinned below 'early', no edge needed 622 LCA = early; // but can not schedule below 'early' 623 } 624 } 625 } 626 assert(found_match, "no worklist bug"); 627 #ifdef TRACK_PHI_INPUTS 628 #ifdef ASSERT 629 // This assert asks about correct handling of PhiNodes, which may not 630 // have all input edges directly from 'mem'. See BugId 4621264 631 int num_mem_inputs = phi_inputs.at_grow(store->_idx,0) + 1; 632 // Increment by exactly one even if there are multiple copies of 'mem' 633 // coming into the phi, because we will run this block several times 634 // if there are several copies of 'mem'. (That's how DU iterators work.) 635 phi_inputs.at_put(store->_idx, num_mem_inputs); 636 assert(PhiNode::Input + num_mem_inputs < store->req(), 637 "Expect at least one phi input will not be from original memory state"); 638 #endif //ASSERT 639 #endif //TRACK_PHI_INPUTS 640 } else if (store_block != early) { 641 // 'store' is between the current LCA and earliest possible block. 642 // Label its block, and decide later on how to raise the LCA 643 // to include the effect on LCA of this store. 644 // If this store's block gets chosen as the raised LCA, we 645 // will find him on the non_early_stores list and stick him 646 // with a precedence edge. 647 // (But, don't bother if LCA is already raised all the way.) 648 if (LCA != early) { 649 store_block->set_raise_LCA_mark(load_index); 650 must_raise_LCA = true; 651 non_early_stores.push(store); 652 } 653 } else { 654 // Found a possibly-interfering store in the load's 'early' block. 655 // This means 'load' cannot sink at all in the dominator tree. 656 // Add an anti-dep edge, and squeeze 'load' into the highest block. 657 assert(store != load->in(0), "dependence cycle found"); 658 if (verify) { 659 assert(store->find_edge(load) != -1, "missing precedence edge"); 660 } else { 661 store->add_prec(load); 662 } 663 LCA = early; 664 // This turns off the process of gathering non_early_stores. 665 } 666 } 667 // (Worklist is now empty; all nearby stores have been visited.) 668 669 // Finished if 'load' must be scheduled in its 'early' block. 670 // If we found any stores there, they have already been given 671 // precedence edges. 672 if (LCA == early) return LCA; 673 674 // We get here only if there are no possibly-interfering stores 675 // in the load's 'early' block. Move LCA up above all predecessors 676 // which contain stores we have noted. 677 // 678 // The raised LCA block can be a home to such interfering stores, 679 // but its predecessors must not contain any such stores. 680 // 681 // The raised LCA will be a lower bound for placing the load, 682 // preventing the load from sinking past any block containing 683 // a store that may invalidate the memory state required by 'load'. 684 if (must_raise_LCA) 685 LCA = raise_LCA_above_marks(LCA, load->_idx, early, _bbs); 686 if (LCA == early) return LCA; 687 688 // Insert anti-dependence edges from 'load' to each store 689 // in the non-early LCA block. 690 // Mine the non_early_stores list for such stores. 691 if (LCA->raise_LCA_mark() == load_index) { 692 while (non_early_stores.size() > 0) { 693 Node* store = non_early_stores.pop(); 694 Block* store_block = _bbs[store->_idx]; 695 if (store_block == LCA) { 696 // add anti_dependence from store to load in its own block 697 assert(store != load->in(0), "dependence cycle found"); 698 if (verify) { 699 assert(store->find_edge(load) != -1, "missing precedence edge"); 700 } else { 701 store->add_prec(load); 702 } 703 } else { 704 assert(store_block->raise_LCA_mark() == load_index, "block was marked"); 705 // Any other stores we found must be either inside the new LCA 706 // or else outside the original LCA. In the latter case, they 707 // did not interfere with any use of 'load'. 708 assert(LCA->dominates(store_block) 709 || !LCA_orig->dominates(store_block), "no stray stores"); 710 } 711 } 712 } 713 714 // Return the highest block containing stores; any stores 715 // within that block have been given anti-dependence edges. 716 return LCA; 717 } 718 719 // This class is used to iterate backwards over the nodes in the graph. 720 721 class Node_Backward_Iterator { 722 723 private: 724 Node_Backward_Iterator(); 725 726 public: 727 // Constructor for the iterator 728 Node_Backward_Iterator(Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs); 729 730 // Postincrement operator to iterate over the nodes 731 Node *next(); 732 733 private: 734 VectorSet &_visited; 735 Node_List &_stack; 736 Block_Array &_bbs; 737 }; 738 739 // Constructor for the Node_Backward_Iterator 740 Node_Backward_Iterator::Node_Backward_Iterator( Node *root, VectorSet &visited, Node_List &stack, Block_Array &bbs ) 741 : _visited(visited), _stack(stack), _bbs(bbs) { 742 // The stack should contain exactly the root 743 stack.clear(); 744 stack.push(root); 745 746 // Clear the visited bits 747 visited.Clear(); 748 } 749 750 // Iterator for the Node_Backward_Iterator 751 Node *Node_Backward_Iterator::next() { 752 753 // If the _stack is empty, then just return NULL: finished. 754 if ( !_stack.size() ) 755 return NULL; 756 757 // '_stack' is emulating a real _stack. The 'visit-all-users' loop has been 758 // made stateless, so I do not need to record the index 'i' on my _stack. 759 // Instead I visit all users each time, scanning for unvisited users. 760 // I visit unvisited not-anti-dependence users first, then anti-dependent 761 // children next. 762 Node *self = _stack.pop(); 763 764 // I cycle here when I am entering a deeper level of recursion. 765 // The key variable 'self' was set prior to jumping here. 766 while( 1 ) { 767 768 _visited.set(self->_idx); 769 770 // Now schedule all uses as late as possible. 771 uint src = self->is_Proj() ? self->in(0)->_idx : self->_idx; 772 uint src_rpo = _bbs[src]->_rpo; 773 774 // Schedule all nodes in a post-order visit 775 Node *unvisited = NULL; // Unvisited anti-dependent Node, if any 776 777 // Scan for unvisited nodes 778 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) { 779 // For all uses, schedule late 780 Node* n = self->fast_out(i); // Use 781 782 // Skip already visited children 783 if ( _visited.test(n->_idx) ) 784 continue; 785 786 // do not traverse backward control edges 787 Node *use = n->is_Proj() ? n->in(0) : n; 788 uint use_rpo = _bbs[use->_idx]->_rpo; 789 790 if ( use_rpo < src_rpo ) 791 continue; 792 793 // Phi nodes always precede uses in a basic block 794 if ( use_rpo == src_rpo && use->is_Phi() ) 795 continue; 796 797 unvisited = n; // Found unvisited 798 799 // Check for possible-anti-dependent 800 if( !n->needs_anti_dependence_check() ) 801 break; // Not visited, not anti-dep; schedule it NOW 802 } 803 804 // Did I find an unvisited not-anti-dependent Node? 805 if ( !unvisited ) 806 break; // All done with children; post-visit 'self' 807 808 // Visit the unvisited Node. Contains the obvious push to 809 // indicate I'm entering a deeper level of recursion. I push the 810 // old state onto the _stack and set a new state and loop (recurse). 811 _stack.push(self); 812 self = unvisited; 813 } // End recursion loop 814 815 return self; 816 } 817 818 //------------------------------ComputeLatenciesBackwards---------------------- 819 // Compute the latency of all the instructions. 820 void PhaseCFG::ComputeLatenciesBackwards(VectorSet &visited, Node_List &stack) { 821 #ifndef PRODUCT 822 if (trace_opto_pipelining()) 823 tty->print("\n#---- ComputeLatenciesBackwards ----\n"); 824 #endif 825 826 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs); 827 Node *n; 828 829 // Walk over all the nodes from last to first 830 while (n = iter.next()) { 831 // Set the latency for the definitions of this instruction 832 partial_latency_of_defs(n); 833 } 834 } // end ComputeLatenciesBackwards 835 836 //------------------------------partial_latency_of_defs------------------------ 837 // Compute the latency impact of this node on all defs. This computes 838 // a number that increases as we approach the beginning of the routine. 839 void PhaseCFG::partial_latency_of_defs(Node *n) { 840 // Set the latency for this instruction 841 #ifndef PRODUCT 842 if (trace_opto_pipelining()) { 843 tty->print("# latency_to_inputs: node_latency[%d] = %d for node", 844 n->_idx, _node_latency->at_grow(n->_idx)); 845 dump(); 846 } 847 #endif 848 849 if (n->is_Proj()) 850 n = n->in(0); 851 852 if (n->is_Root()) 853 return; 854 855 uint nlen = n->len(); 856 uint use_latency = _node_latency->at_grow(n->_idx); 857 uint use_pre_order = _bbs[n->_idx]->_pre_order; 858 859 for ( uint j=0; j<nlen; j++ ) { 860 Node *def = n->in(j); 861 862 if (!def || def == n) 863 continue; 864 865 // Walk backwards thru projections 866 if (def->is_Proj()) 867 def = def->in(0); 868 869 #ifndef PRODUCT 870 if (trace_opto_pipelining()) { 871 tty->print("# in(%2d): ", j); 872 def->dump(); 873 } 874 #endif 875 876 // If the defining block is not known, assume it is ok 877 Block *def_block = _bbs[def->_idx]; 878 uint def_pre_order = def_block ? def_block->_pre_order : 0; 879 880 if ( (use_pre_order < def_pre_order) || 881 (use_pre_order == def_pre_order && n->is_Phi()) ) 882 continue; 883 884 uint delta_latency = n->latency(j); 885 uint current_latency = delta_latency + use_latency; 886 887 if (_node_latency->at_grow(def->_idx) < current_latency) { 888 _node_latency->at_put_grow(def->_idx, current_latency); 889 } 890 891 #ifndef PRODUCT 892 if (trace_opto_pipelining()) { 893 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, node_latency[%d] = %d", 894 use_latency, j, delta_latency, current_latency, def->_idx, 895 _node_latency->at_grow(def->_idx)); 896 } 897 #endif 898 } 899 } 900 901 //------------------------------latency_from_use------------------------------- 902 // Compute the latency of a specific use 903 int PhaseCFG::latency_from_use(Node *n, const Node *def, Node *use) { 904 // If self-reference, return no latency 905 if (use == n || use->is_Root()) 906 return 0; 907 908 uint def_pre_order = _bbs[def->_idx]->_pre_order; 909 uint latency = 0; 910 911 // If the use is not a projection, then it is simple... 912 if (!use->is_Proj()) { 913 #ifndef PRODUCT 914 if (trace_opto_pipelining()) { 915 tty->print("# out(): "); 916 use->dump(); 917 } 918 #endif 919 920 uint use_pre_order = _bbs[use->_idx]->_pre_order; 921 922 if (use_pre_order < def_pre_order) 923 return 0; 924 925 if (use_pre_order == def_pre_order && use->is_Phi()) 926 return 0; 927 928 uint nlen = use->len(); 929 uint nl = _node_latency->at_grow(use->_idx); 930 931 for ( uint j=0; j<nlen; j++ ) { 932 if (use->in(j) == n) { 933 // Change this if we want local latencies 934 uint ul = use->latency(j); 935 uint l = ul + nl; 936 if (latency < l) latency = l; 937 #ifndef PRODUCT 938 if (trace_opto_pipelining()) { 939 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, latency = %d", 940 nl, j, ul, l, latency); 941 } 942 #endif 943 } 944 } 945 } else { 946 // This is a projection, just grab the latency of the use(s) 947 for (DUIterator_Fast jmax, j = use->fast_outs(jmax); j < jmax; j++) { 948 uint l = latency_from_use(use, def, use->fast_out(j)); 949 if (latency < l) latency = l; 950 } 951 } 952 953 return latency; 954 } 955 956 //------------------------------latency_from_uses------------------------------ 957 // Compute the latency of this instruction relative to all of it's uses. 958 // This computes a number that increases as we approach the beginning of the 959 // routine. 960 void PhaseCFG::latency_from_uses(Node *n) { 961 // Set the latency for this instruction 962 #ifndef PRODUCT 963 if (trace_opto_pipelining()) { 964 tty->print("# latency_from_outputs: node_latency[%d] = %d for node", 965 n->_idx, _node_latency->at_grow(n->_idx)); 966 dump(); 967 } 968 #endif 969 uint latency=0; 970 const Node *def = n->is_Proj() ? n->in(0): n; 971 972 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { 973 uint l = latency_from_use(n, def, n->fast_out(i)); 974 975 if (latency < l) latency = l; 976 } 977 978 _node_latency->at_put_grow(n->_idx, latency); 979 } 980 981 //------------------------------hoist_to_cheaper_block------------------------- 982 // Pick a block for node self, between early and LCA, that is a cheaper 983 // alternative to LCA. 984 Block* PhaseCFG::hoist_to_cheaper_block(Block* LCA, Block* early, Node* self) { 985 const double delta = 1+PROB_UNLIKELY_MAG(4); 986 Block* least = LCA; 987 double least_freq = least->_freq; 988 uint target = _node_latency->at_grow(self->_idx); 989 uint start_latency = _node_latency->at_grow(LCA->_nodes[0]->_idx); 990 uint end_latency = _node_latency->at_grow(LCA->_nodes[LCA->end_idx()]->_idx); 991 bool in_latency = (target <= start_latency); 992 const Block* root_block = _bbs[_root->_idx]; 993 994 // Turn off latency scheduling if scheduling is just plain off 995 if (!C->do_scheduling()) 996 in_latency = true; 997 998 // Do not hoist (to cover latency) instructions which target a 999 // single register. Hoisting stretches the live range of the 1000 // single register and may force spilling. 1001 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL; 1002 if (mach && mach->out_RegMask().is_bound1() && mach->out_RegMask().is_NotEmpty()) 1003 in_latency = true; 1004 1005 #ifndef PRODUCT 1006 if (trace_opto_pipelining()) { 1007 tty->print("# Find cheaper block for latency %d: ", 1008 _node_latency->at_grow(self->_idx)); 1009 self->dump(); 1010 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g", 1011 LCA->_pre_order, 1012 LCA->_nodes[0]->_idx, 1013 start_latency, 1014 LCA->_nodes[LCA->end_idx()]->_idx, 1015 end_latency, 1016 least_freq); 1017 } 1018 #endif 1019 1020 // Walk up the dominator tree from LCA (Lowest common ancestor) to 1021 // the earliest legal location. Capture the least execution frequency. 1022 while (LCA != early) { 1023 LCA = LCA->_idom; // Follow up the dominator tree 1024 1025 if (LCA == NULL) { 1026 // Bailout without retry 1027 C->record_method_not_compilable("late schedule failed: LCA == NULL"); 1028 return least; 1029 } 1030 1031 // Don't hoist machine instructions to the root basic block 1032 if (mach && LCA == root_block) 1033 break; 1034 1035 uint start_lat = _node_latency->at_grow(LCA->_nodes[0]->_idx); 1036 uint end_idx = LCA->end_idx(); 1037 uint end_lat = _node_latency->at_grow(LCA->_nodes[end_idx]->_idx); 1038 double LCA_freq = LCA->_freq; 1039 #ifndef PRODUCT 1040 if (trace_opto_pipelining()) { 1041 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g", 1042 LCA->_pre_order, LCA->_nodes[0]->_idx, start_lat, end_idx, end_lat, LCA_freq); 1043 } 1044 #endif 1045 if (LCA_freq < least_freq || // Better Frequency 1046 ( !in_latency && // No block containing latency 1047 LCA_freq < least_freq * delta && // No worse frequency 1048 target >= end_lat && // within latency range 1049 !self->is_iteratively_computed() ) // But don't hoist IV increments 1050 // because they may end up above other uses of their phi forcing 1051 // their result register to be different from their input. 1052 ) { 1053 least = LCA; // Found cheaper block 1054 least_freq = LCA_freq; 1055 start_latency = start_lat; 1056 end_latency = end_lat; 1057 if (target <= start_lat) 1058 in_latency = true; 1059 } 1060 } 1061 1062 #ifndef PRODUCT 1063 if (trace_opto_pipelining()) { 1064 tty->print_cr("# Choose block B%d with start latency=%d and freq=%g", 1065 least->_pre_order, start_latency, least_freq); 1066 } 1067 #endif 1068 1069 // See if the latency needs to be updated 1070 if (target < end_latency) { 1071 #ifndef PRODUCT 1072 if (trace_opto_pipelining()) { 1073 tty->print_cr("# Change latency for [%4d] from %d to %d", self->_idx, target, end_latency); 1074 } 1075 #endif 1076 _node_latency->at_put_grow(self->_idx, end_latency); 1077 partial_latency_of_defs(self); 1078 } 1079 1080 return least; 1081 } 1082 1083 1084 //------------------------------schedule_late----------------------------------- 1085 // Now schedule all codes as LATE as possible. This is the LCA in the 1086 // dominator tree of all USES of a value. Pick the block with the least 1087 // loop nesting depth that is lowest in the dominator tree. 1088 extern const char must_clone[]; 1089 void PhaseCFG::schedule_late(VectorSet &visited, Node_List &stack) { 1090 #ifndef PRODUCT 1091 if (trace_opto_pipelining()) 1092 tty->print("\n#---- schedule_late ----\n"); 1093 #endif 1094 1095 Node_Backward_Iterator iter((Node *)_root, visited, stack, _bbs); 1096 Node *self; 1097 1098 // Walk over all the nodes from last to first 1099 while (self = iter.next()) { 1100 Block* early = _bbs[self->_idx]; // Earliest legal placement 1101 1102 if (self->is_top()) { 1103 // Top node goes in bb #2 with other constants. 1104 // It must be special-cased, because it has no out edges. 1105 early->add_inst(self); 1106 continue; 1107 } 1108 1109 // No uses, just terminate 1110 if (self->outcnt() == 0) { 1111 assert(self->Opcode() == Op_MachProj, "sanity"); 1112 continue; // Must be a dead machine projection 1113 } 1114 1115 // If node is pinned in the block, then no scheduling can be done. 1116 if( self->pinned() ) // Pinned in block? 1117 continue; 1118 1119 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL; 1120 if (mach) { 1121 switch (mach->ideal_Opcode()) { 1122 case Op_CreateEx: 1123 // Don't move exception creation 1124 early->add_inst(self); 1125 continue; 1126 break; 1127 case Op_CheckCastPP: 1128 // Don't move CheckCastPP nodes away from their input, if the input 1129 // is a rawptr (5071820). 1130 Node *def = self->in(1); 1131 if (def != NULL && def->bottom_type()->base() == Type::RawPtr) { 1132 early->add_inst(self); 1133 #ifdef ASSERT 1134 _raw_oops.push(def); 1135 #endif 1136 continue; 1137 } 1138 break; 1139 } 1140 } 1141 1142 // Gather LCA of all uses 1143 Block *LCA = NULL; 1144 { 1145 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) { 1146 // For all uses, find LCA 1147 Node* use = self->fast_out(i); 1148 LCA = raise_LCA_above_use(LCA, use, self, _bbs); 1149 } 1150 } // (Hide defs of imax, i from rest of block.) 1151 1152 // Place temps in the block of their use. This isn't a 1153 // requirement for correctness but it reduces useless 1154 // interference between temps and other nodes. 1155 if (mach != NULL && mach->is_MachTemp()) { 1156 _bbs.map(self->_idx, LCA); 1157 LCA->add_inst(self); 1158 continue; 1159 } 1160 1161 // Check if 'self' could be anti-dependent on memory 1162 if (self->needs_anti_dependence_check()) { 1163 // Hoist LCA above possible-defs and insert anti-dependences to 1164 // defs in new LCA block. 1165 LCA = insert_anti_dependences(LCA, self); 1166 } 1167 1168 if (early->_dom_depth > LCA->_dom_depth) { 1169 // Somehow the LCA has moved above the earliest legal point. 1170 // (One way this can happen is via memory_early_block.) 1171 if (C->subsume_loads() == true && !C->failing()) { 1172 // Retry with subsume_loads == false 1173 // If this is the first failure, the sentinel string will "stick" 1174 // to the Compile object, and the C2Compiler will see it and retry. 1175 C->record_failure(C2Compiler::retry_no_subsuming_loads()); 1176 } else { 1177 // Bailout without retry when (early->_dom_depth > LCA->_dom_depth) 1178 C->record_method_not_compilable("late schedule failed: incorrect graph"); 1179 } 1180 return; 1181 } 1182 1183 // If there is no opportunity to hoist, then we're done. 1184 bool try_to_hoist = (LCA != early); 1185 1186 // Must clone guys stay next to use; no hoisting allowed. 1187 // Also cannot hoist guys that alter memory or are otherwise not 1188 // allocatable (hoisting can make a value live longer, leading to 1189 // anti and output dependency problems which are normally resolved 1190 // by the register allocator giving everyone a different register). 1191 if (mach != NULL && must_clone[mach->ideal_Opcode()]) 1192 try_to_hoist = false; 1193 1194 Block* late = NULL; 1195 if (try_to_hoist) { 1196 // Now find the block with the least execution frequency. 1197 // Start at the latest schedule and work up to the earliest schedule 1198 // in the dominator tree. Thus the Node will dominate all its uses. 1199 late = hoist_to_cheaper_block(LCA, early, self); 1200 } else { 1201 // Just use the LCA of the uses. 1202 late = LCA; 1203 } 1204 1205 // Put the node into target block 1206 schedule_node_into_block(self, late); 1207 1208 #ifdef ASSERT 1209 if (self->needs_anti_dependence_check()) { 1210 // since precedence edges are only inserted when we're sure they 1211 // are needed make sure that after placement in a block we don't 1212 // need any new precedence edges. 1213 verify_anti_dependences(late, self); 1214 } 1215 #endif 1216 } // Loop until all nodes have been visited 1217 1218 } // end ScheduleLate 1219 1220 //------------------------------GlobalCodeMotion------------------------------- 1221 void PhaseCFG::GlobalCodeMotion( Matcher &matcher, uint unique, Node_List &proj_list ) { 1222 ResourceMark rm; 1223 1224 #ifndef PRODUCT 1225 if (trace_opto_pipelining()) { 1226 tty->print("\n---- Start GlobalCodeMotion ----\n"); 1227 } 1228 #endif 1229 1230 // Initialize the bbs.map for things on the proj_list 1231 uint i; 1232 for( i=0; i < proj_list.size(); i++ ) 1233 _bbs.map(proj_list[i]->_idx, NULL); 1234 1235 // Set the basic block for Nodes pinned into blocks 1236 Arena *a = Thread::current()->resource_area(); 1237 VectorSet visited(a); 1238 schedule_pinned_nodes( visited ); 1239 1240 // Find the earliest Block any instruction can be placed in. Some 1241 // instructions are pinned into Blocks. Unpinned instructions can 1242 // appear in last block in which all their inputs occur. 1243 visited.Clear(); 1244 Node_List stack(a); 1245 stack.map( (unique >> 1) + 16, NULL); // Pre-grow the list 1246 if (!schedule_early(visited, stack)) { 1247 // Bailout without retry 1248 C->record_method_not_compilable("early schedule failed"); 1249 return; 1250 } 1251 1252 // Build Def-Use edges. 1253 proj_list.push(_root); // Add real root as another root 1254 proj_list.pop(); 1255 1256 // Compute the latency information (via backwards walk) for all the 1257 // instructions in the graph 1258 _node_latency = new GrowableArray<uint>(); // resource_area allocation 1259 1260 if( C->do_scheduling() ) 1261 ComputeLatenciesBackwards(visited, stack); 1262 1263 // Now schedule all codes as LATE as possible. This is the LCA in the 1264 // dominator tree of all USES of a value. Pick the block with the least 1265 // loop nesting depth that is lowest in the dominator tree. 1266 // ( visited.Clear() called in schedule_late()->Node_Backward_Iterator() ) 1267 schedule_late(visited, stack); 1268 if( C->failing() ) { 1269 // schedule_late fails only when graph is incorrect. 1270 assert(!VerifyGraphEdges, "verification should have failed"); 1271 return; 1272 } 1273 1274 unique = C->unique(); 1275 1276 #ifndef PRODUCT 1277 if (trace_opto_pipelining()) { 1278 tty->print("\n---- Detect implicit null checks ----\n"); 1279 } 1280 #endif 1281 1282 // Detect implicit-null-check opportunities. Basically, find NULL checks 1283 // with suitable memory ops nearby. Use the memory op to do the NULL check. 1284 // I can generate a memory op if there is not one nearby. 1285 if (C->is_method_compilation()) { 1286 // Don't do it for natives, adapters, or runtime stubs 1287 int allowed_reasons = 0; 1288 // ...and don't do it when there have been too many traps, globally. 1289 for (int reason = (int)Deoptimization::Reason_none+1; 1290 reason < Compile::trapHistLength; reason++) { 1291 assert(reason < BitsPerInt, "recode bit map"); 1292 if (!C->too_many_traps((Deoptimization::DeoptReason) reason)) 1293 allowed_reasons |= nth_bit(reason); 1294 } 1295 // By reversing the loop direction we get a very minor gain on mpegaudio. 1296 // Feel free to revert to a forward loop for clarity. 1297 // for( int i=0; i < (int)matcher._null_check_tests.size(); i+=2 ) { 1298 for( int i= matcher._null_check_tests.size()-2; i>=0; i-=2 ) { 1299 Node *proj = matcher._null_check_tests[i ]; 1300 Node *val = matcher._null_check_tests[i+1]; 1301 _bbs[proj->_idx]->implicit_null_check(this, proj, val, allowed_reasons); 1302 // The implicit_null_check will only perform the transformation 1303 // if the null branch is truly uncommon, *and* it leads to an 1304 // uncommon trap. Combined with the too_many_traps guards 1305 // above, this prevents SEGV storms reported in 6366351, 1306 // by recompiling offending methods without this optimization. 1307 } 1308 } 1309 1310 #ifndef PRODUCT 1311 if (trace_opto_pipelining()) { 1312 tty->print("\n---- Start Local Scheduling ----\n"); 1313 } 1314 #endif 1315 1316 // Schedule locally. Right now a simple topological sort. 1317 // Later, do a real latency aware scheduler. 1318 int *ready_cnt = NEW_RESOURCE_ARRAY(int,C->unique()); 1319 memset( ready_cnt, -1, C->unique() * sizeof(int) ); 1320 visited.Clear(); 1321 for (i = 0; i < _num_blocks; i++) { 1322 if (!_blocks[i]->schedule_local(this, matcher, ready_cnt, visited)) { 1323 if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) { 1324 C->record_method_not_compilable("local schedule failed"); 1325 } 1326 return; 1327 } 1328 } 1329 1330 // If we inserted any instructions between a Call and his CatchNode, 1331 // clone the instructions on all paths below the Catch. 1332 for( i=0; i < _num_blocks; i++ ) 1333 _blocks[i]->call_catch_cleanup(_bbs); 1334 1335 #ifndef PRODUCT 1336 if (trace_opto_pipelining()) { 1337 tty->print("\n---- After GlobalCodeMotion ----\n"); 1338 for (uint i = 0; i < _num_blocks; i++) { 1339 _blocks[i]->dump(); 1340 } 1341 } 1342 #endif 1343 // Dead. 1344 _node_latency = (GrowableArray<uint> *)0xdeadbeef; 1345 } 1346 1347 1348 //------------------------------Estimate_Block_Frequency----------------------- 1349 // Estimate block frequencies based on IfNode probabilities. 1350 void PhaseCFG::Estimate_Block_Frequency() { 1351 1352 // Force conditional branches leading to uncommon traps to be unlikely, 1353 // not because we get to the uncommon_trap with less relative frequency, 1354 // but because an uncommon_trap typically causes a deopt, so we only get 1355 // there once. 1356 if (C->do_freq_based_layout()) { 1357 Block_List worklist; 1358 Block* root_blk = _blocks[0]; 1359 for (uint i = 1; i < root_blk->num_preds(); i++) { 1360 Block *pb = _bbs[root_blk->pred(i)->_idx]; 1361 if (pb->has_uncommon_code()) { 1362 worklist.push(pb); 1363 } 1364 } 1365 while (worklist.size() > 0) { 1366 Block* uct = worklist.pop(); 1367 if (uct == _broot) continue; 1368 for (uint i = 1; i < uct->num_preds(); i++) { 1369 Block *pb = _bbs[uct->pred(i)->_idx]; 1370 if (pb->_num_succs == 1) { 1371 worklist.push(pb); 1372 } else if (pb->num_fall_throughs() == 2) { 1373 pb->update_uncommon_branch(uct); 1374 } 1375 } 1376 } 1377 } 1378 1379 // Create the loop tree and calculate loop depth. 1380 _root_loop = create_loop_tree(); 1381 _root_loop->compute_loop_depth(0); 1382 1383 // Compute block frequency of each block, relative to a single loop entry. 1384 _root_loop->compute_freq(); 1385 1386 // Adjust all frequencies to be relative to a single method entry 1387 _root_loop->_freq = 1.0; 1388 _root_loop->scale_freq(); 1389 1390 // Save outmost loop frequency for LRG frequency threshold 1391 _outer_loop_freq = _root_loop->outer_loop_freq(); 1392 1393 // force paths ending at uncommon traps to be infrequent 1394 if (!C->do_freq_based_layout()) { 1395 Block_List worklist; 1396 Block* root_blk = _blocks[0]; 1397 for (uint i = 1; i < root_blk->num_preds(); i++) { 1398 Block *pb = _bbs[root_blk->pred(i)->_idx]; 1399 if (pb->has_uncommon_code()) { 1400 worklist.push(pb); 1401 } 1402 } 1403 while (worklist.size() > 0) { 1404 Block* uct = worklist.pop(); 1405 uct->_freq = PROB_MIN; 1406 for (uint i = 1; i < uct->num_preds(); i++) { 1407 Block *pb = _bbs[uct->pred(i)->_idx]; 1408 if (pb->_num_succs == 1 && pb->_freq > PROB_MIN) { 1409 worklist.push(pb); 1410 } 1411 } 1412 } 1413 } 1414 1415 #ifdef ASSERT 1416 for (uint i = 0; i < _num_blocks; i++ ) { 1417 Block *b = _blocks[i]; 1418 assert(b->_freq >= MIN_BLOCK_FREQUENCY, "Register Allocator requires meaningful block frequency"); 1419 } 1420 #endif 1421 1422 #ifndef PRODUCT 1423 if (PrintCFGBlockFreq) { 1424 tty->print_cr("CFG Block Frequencies"); 1425 _root_loop->dump_tree(); 1426 if (Verbose) { 1427 tty->print_cr("PhaseCFG dump"); 1428 dump(); 1429 tty->print_cr("Node dump"); 1430 _root->dump(99999); 1431 } 1432 } 1433 #endif 1434 } 1435 1436 //----------------------------create_loop_tree-------------------------------- 1437 // Create a loop tree from the CFG 1438 CFGLoop* PhaseCFG::create_loop_tree() { 1439 1440 #ifdef ASSERT 1441 assert( _blocks[0] == _broot, "" ); 1442 for (uint i = 0; i < _num_blocks; i++ ) { 1443 Block *b = _blocks[i]; 1444 // Check that _loop field are clear...we could clear them if not. 1445 assert(b->_loop == NULL, "clear _loop expected"); 1446 // Sanity check that the RPO numbering is reflected in the _blocks array. 1447 // It doesn't have to be for the loop tree to be built, but if it is not, 1448 // then the blocks have been reordered since dom graph building...which 1449 // may question the RPO numbering 1450 assert(b->_rpo == i, "unexpected reverse post order number"); 1451 } 1452 #endif 1453 1454 int idct = 0; 1455 CFGLoop* root_loop = new CFGLoop(idct++); 1456 1457 Block_List worklist; 1458 1459 // Assign blocks to loops 1460 for(uint i = _num_blocks - 1; i > 0; i-- ) { // skip Root block 1461 Block *b = _blocks[i]; 1462 1463 if (b->head()->is_Loop()) { 1464 Block* loop_head = b; 1465 assert(loop_head->num_preds() - 1 == 2, "loop must have 2 predecessors"); 1466 Node* tail_n = loop_head->pred(LoopNode::LoopBackControl); 1467 Block* tail = _bbs[tail_n->_idx]; 1468 1469 // Defensively filter out Loop nodes for non-single-entry loops. 1470 // For all reasonable loops, the head occurs before the tail in RPO. 1471 if (i <= tail->_rpo) { 1472 1473 // The tail and (recursive) predecessors of the tail 1474 // are made members of a new loop. 1475 1476 assert(worklist.size() == 0, "nonempty worklist"); 1477 CFGLoop* nloop = new CFGLoop(idct++); 1478 assert(loop_head->_loop == NULL, "just checking"); 1479 loop_head->_loop = nloop; 1480 // Add to nloop so push_pred() will skip over inner loops 1481 nloop->add_member(loop_head); 1482 nloop->push_pred(loop_head, LoopNode::LoopBackControl, worklist, _bbs); 1483 1484 while (worklist.size() > 0) { 1485 Block* member = worklist.pop(); 1486 if (member != loop_head) { 1487 for (uint j = 1; j < member->num_preds(); j++) { 1488 nloop->push_pred(member, j, worklist, _bbs); 1489 } 1490 } 1491 } 1492 } 1493 } 1494 } 1495 1496 // Create a member list for each loop consisting 1497 // of both blocks and (immediate child) loops. 1498 for (uint i = 0; i < _num_blocks; i++) { 1499 Block *b = _blocks[i]; 1500 CFGLoop* lp = b->_loop; 1501 if (lp == NULL) { 1502 // Not assigned to a loop. Add it to the method's pseudo loop. 1503 b->_loop = root_loop; 1504 lp = root_loop; 1505 } 1506 if (lp == root_loop || b != lp->head()) { // loop heads are already members 1507 lp->add_member(b); 1508 } 1509 if (lp != root_loop) { 1510 if (lp->parent() == NULL) { 1511 // Not a nested loop. Make it a child of the method's pseudo loop. 1512 root_loop->add_nested_loop(lp); 1513 } 1514 if (b == lp->head()) { 1515 // Add nested loop to member list of parent loop. 1516 lp->parent()->add_member(lp); 1517 } 1518 } 1519 } 1520 1521 return root_loop; 1522 } 1523 1524 //------------------------------push_pred-------------------------------------- 1525 void CFGLoop::push_pred(Block* blk, int i, Block_List& worklist, Block_Array& node_to_blk) { 1526 Node* pred_n = blk->pred(i); 1527 Block* pred = node_to_blk[pred_n->_idx]; 1528 CFGLoop *pred_loop = pred->_loop; 1529 if (pred_loop == NULL) { 1530 // Filter out blocks for non-single-entry loops. 1531 // For all reasonable loops, the head occurs before the tail in RPO. 1532 if (pred->_rpo > head()->_rpo) { 1533 pred->_loop = this; 1534 worklist.push(pred); 1535 } 1536 } else if (pred_loop != this) { 1537 // Nested loop. 1538 while (pred_loop->_parent != NULL && pred_loop->_parent != this) { 1539 pred_loop = pred_loop->_parent; 1540 } 1541 // Make pred's loop be a child 1542 if (pred_loop->_parent == NULL) { 1543 add_nested_loop(pred_loop); 1544 // Continue with loop entry predecessor. 1545 Block* pred_head = pred_loop->head(); 1546 assert(pred_head->num_preds() - 1 == 2, "loop must have 2 predecessors"); 1547 assert(pred_head != head(), "loop head in only one loop"); 1548 push_pred(pred_head, LoopNode::EntryControl, worklist, node_to_blk); 1549 } else { 1550 assert(pred_loop->_parent == this && _parent == NULL, "just checking"); 1551 } 1552 } 1553 } 1554 1555 //------------------------------add_nested_loop-------------------------------- 1556 // Make cl a child of the current loop in the loop tree. 1557 void CFGLoop::add_nested_loop(CFGLoop* cl) { 1558 assert(_parent == NULL, "no parent yet"); 1559 assert(cl != this, "not my own parent"); 1560 cl->_parent = this; 1561 CFGLoop* ch = _child; 1562 if (ch == NULL) { 1563 _child = cl; 1564 } else { 1565 while (ch->_sibling != NULL) { ch = ch->_sibling; } 1566 ch->_sibling = cl; 1567 } 1568 } 1569 1570 //------------------------------compute_loop_depth----------------------------- 1571 // Store the loop depth in each CFGLoop object. 1572 // Recursively walk the children to do the same for them. 1573 void CFGLoop::compute_loop_depth(int depth) { 1574 _depth = depth; 1575 CFGLoop* ch = _child; 1576 while (ch != NULL) { 1577 ch->compute_loop_depth(depth + 1); 1578 ch = ch->_sibling; 1579 } 1580 } 1581 1582 //------------------------------compute_freq----------------------------------- 1583 // Compute the frequency of each block and loop, relative to a single entry 1584 // into the dominating loop head. 1585 void CFGLoop::compute_freq() { 1586 // Bottom up traversal of loop tree (visit inner loops first.) 1587 // Set loop head frequency to 1.0, then transitively 1588 // compute frequency for all successors in the loop, 1589 // as well as for each exit edge. Inner loops are 1590 // treated as single blocks with loop exit targets 1591 // as the successor blocks. 1592 1593 // Nested loops first 1594 CFGLoop* ch = _child; 1595 while (ch != NULL) { 1596 ch->compute_freq(); 1597 ch = ch->_sibling; 1598 } 1599 assert (_members.length() > 0, "no empty loops"); 1600 Block* hd = head(); 1601 hd->_freq = 1.0f; 1602 for (int i = 0; i < _members.length(); i++) { 1603 CFGElement* s = _members.at(i); 1604 float freq = s->_freq; 1605 if (s->is_block()) { 1606 Block* b = s->as_Block(); 1607 for (uint j = 0; j < b->_num_succs; j++) { 1608 Block* sb = b->_succs[j]; 1609 update_succ_freq(sb, freq * b->succ_prob(j)); 1610 } 1611 } else { 1612 CFGLoop* lp = s->as_CFGLoop(); 1613 assert(lp->_parent == this, "immediate child"); 1614 for (int k = 0; k < lp->_exits.length(); k++) { 1615 Block* eb = lp->_exits.at(k).get_target(); 1616 float prob = lp->_exits.at(k).get_prob(); 1617 update_succ_freq(eb, freq * prob); 1618 } 1619 } 1620 } 1621 1622 // For all loops other than the outer, "method" loop, 1623 // sum and normalize the exit probability. The "method" loop 1624 // should keep the initial exit probability of 1, so that 1625 // inner blocks do not get erroneously scaled. 1626 if (_depth != 0) { 1627 // Total the exit probabilities for this loop. 1628 float exits_sum = 0.0f; 1629 for (int i = 0; i < _exits.length(); i++) { 1630 exits_sum += _exits.at(i).get_prob(); 1631 } 1632 1633 // Normalize the exit probabilities. Until now, the 1634 // probabilities estimate the possibility of exit per 1635 // a single loop iteration; afterward, they estimate 1636 // the probability of exit per loop entry. 1637 for (int i = 0; i < _exits.length(); i++) { 1638 Block* et = _exits.at(i).get_target(); 1639 float new_prob = 0.0f; 1640 if (_exits.at(i).get_prob() > 0.0f) { 1641 new_prob = _exits.at(i).get_prob() / exits_sum; 1642 } 1643 BlockProbPair bpp(et, new_prob); 1644 _exits.at_put(i, bpp); 1645 } 1646 1647 // Save the total, but guard against unreasonable probability, 1648 // as the value is used to estimate the loop trip count. 1649 // An infinite trip count would blur relative block 1650 // frequencies. 1651 if (exits_sum > 1.0f) exits_sum = 1.0; 1652 if (exits_sum < PROB_MIN) exits_sum = PROB_MIN; 1653 _exit_prob = exits_sum; 1654 } 1655 } 1656 1657 //------------------------------succ_prob------------------------------------- 1658 // Determine the probability of reaching successor 'i' from the receiver block. 1659 float Block::succ_prob(uint i) { 1660 int eidx = end_idx(); 1661 Node *n = _nodes[eidx]; // Get ending Node 1662 1663 int op = n->Opcode(); 1664 if (n->is_Mach()) { 1665 if (n->is_MachNullCheck()) { 1666 // Can only reach here if called after lcm. The original Op_If is gone, 1667 // so we attempt to infer the probability from one or both of the 1668 // successor blocks. 1669 assert(_num_succs == 2, "expecting 2 successors of a null check"); 1670 // If either successor has only one predecessor, then the 1671 // probability estimate can be derived using the 1672 // relative frequency of the successor and this block. 1673 if (_succs[i]->num_preds() == 2) { 1674 return _succs[i]->_freq / _freq; 1675 } else if (_succs[1-i]->num_preds() == 2) { 1676 return 1 - (_succs[1-i]->_freq / _freq); 1677 } else { 1678 // Estimate using both successor frequencies 1679 float freq = _succs[i]->_freq; 1680 return freq / (freq + _succs[1-i]->_freq); 1681 } 1682 } 1683 op = n->as_Mach()->ideal_Opcode(); 1684 } 1685 1686 1687 // Switch on branch type 1688 switch( op ) { 1689 case Op_CountedLoopEnd: 1690 case Op_If: { 1691 assert (i < 2, "just checking"); 1692 // Conditionals pass on only part of their frequency 1693 float prob = n->as_MachIf()->_prob; 1694 assert(prob >= 0.0 && prob <= 1.0, "out of range probability"); 1695 // If succ[i] is the FALSE branch, invert path info 1696 if( _nodes[i + eidx + 1]->Opcode() == Op_IfFalse ) { 1697 return 1.0f - prob; // not taken 1698 } else { 1699 return prob; // taken 1700 } 1701 } 1702 1703 case Op_Jump: 1704 // Divide the frequency between all successors evenly 1705 return 1.0f/_num_succs; 1706 1707 case Op_Catch: { 1708 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj(); 1709 if (ci->_con == CatchProjNode::fall_through_index) { 1710 // Fall-thru path gets the lion's share. 1711 return 1.0f - PROB_UNLIKELY_MAG(5)*_num_succs; 1712 } else { 1713 // Presume exceptional paths are equally unlikely 1714 return PROB_UNLIKELY_MAG(5); 1715 } 1716 } 1717 1718 case Op_Root: 1719 case Op_Goto: 1720 // Pass frequency straight thru to target 1721 return 1.0f; 1722 1723 case Op_NeverBranch: 1724 return 0.0f; 1725 1726 case Op_TailCall: 1727 case Op_TailJump: 1728 case Op_Return: 1729 case Op_Halt: 1730 case Op_Rethrow: 1731 // Do not push out freq to root block 1732 return 0.0f; 1733 1734 default: 1735 ShouldNotReachHere(); 1736 } 1737 1738 return 0.0f; 1739 } 1740 1741 //------------------------------num_fall_throughs----------------------------- 1742 // Return the number of fall-through candidates for a block 1743 int Block::num_fall_throughs() { 1744 int eidx = end_idx(); 1745 Node *n = _nodes[eidx]; // Get ending Node 1746 1747 int op = n->Opcode(); 1748 if (n->is_Mach()) { 1749 if (n->is_MachNullCheck()) { 1750 // In theory, either side can fall-thru, for simplicity sake, 1751 // let's say only the false branch can now. 1752 return 1; 1753 } 1754 op = n->as_Mach()->ideal_Opcode(); 1755 } 1756 1757 // Switch on branch type 1758 switch( op ) { 1759 case Op_CountedLoopEnd: 1760 case Op_If: 1761 return 2; 1762 1763 case Op_Root: 1764 case Op_Goto: 1765 return 1; 1766 1767 case Op_Catch: { 1768 for (uint i = 0; i < _num_succs; i++) { 1769 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj(); 1770 if (ci->_con == CatchProjNode::fall_through_index) { 1771 return 1; 1772 } 1773 } 1774 return 0; 1775 } 1776 1777 case Op_Jump: 1778 case Op_NeverBranch: 1779 case Op_TailCall: 1780 case Op_TailJump: 1781 case Op_Return: 1782 case Op_Halt: 1783 case Op_Rethrow: 1784 return 0; 1785 1786 default: 1787 ShouldNotReachHere(); 1788 } 1789 1790 return 0; 1791 } 1792 1793 //------------------------------succ_fall_through----------------------------- 1794 // Return true if a specific successor could be fall-through target. 1795 bool Block::succ_fall_through(uint i) { 1796 int eidx = end_idx(); 1797 Node *n = _nodes[eidx]; // Get ending Node 1798 1799 int op = n->Opcode(); 1800 if (n->is_Mach()) { 1801 if (n->is_MachNullCheck()) { 1802 // In theory, either side can fall-thru, for simplicity sake, 1803 // let's say only the false branch can now. 1804 return _nodes[i + eidx + 1]->Opcode() == Op_IfFalse; 1805 } 1806 op = n->as_Mach()->ideal_Opcode(); 1807 } 1808 1809 // Switch on branch type 1810 switch( op ) { 1811 case Op_CountedLoopEnd: 1812 case Op_If: 1813 case Op_Root: 1814 case Op_Goto: 1815 return true; 1816 1817 case Op_Catch: { 1818 const CatchProjNode *ci = _nodes[i + eidx + 1]->as_CatchProj(); 1819 return ci->_con == CatchProjNode::fall_through_index; 1820 } 1821 1822 case Op_Jump: 1823 case Op_NeverBranch: 1824 case Op_TailCall: 1825 case Op_TailJump: 1826 case Op_Return: 1827 case Op_Halt: 1828 case Op_Rethrow: 1829 return false; 1830 1831 default: 1832 ShouldNotReachHere(); 1833 } 1834 1835 return false; 1836 } 1837 1838 //------------------------------update_uncommon_branch------------------------ 1839 // Update the probability of a two-branch to be uncommon 1840 void Block::update_uncommon_branch(Block* ub) { 1841 int eidx = end_idx(); 1842 Node *n = _nodes[eidx]; // Get ending Node 1843 1844 int op = n->as_Mach()->ideal_Opcode(); 1845 1846 assert(op == Op_CountedLoopEnd || op == Op_If, "must be a If"); 1847 assert(num_fall_throughs() == 2, "must be a two way branch block"); 1848 1849 // Which successor is ub? 1850 uint s; 1851 for (s = 0; s <_num_succs; s++) { 1852 if (_succs[s] == ub) break; 1853 } 1854 assert(s < 2, "uncommon successor must be found"); 1855 1856 // If ub is the true path, make the proability small, else 1857 // ub is the false path, and make the probability large 1858 bool invert = (_nodes[s + eidx + 1]->Opcode() == Op_IfFalse); 1859 1860 // Get existing probability 1861 float p = n->as_MachIf()->_prob; 1862 1863 if (invert) p = 1.0 - p; 1864 if (p > PROB_MIN) { 1865 p = PROB_MIN; 1866 } 1867 if (invert) p = 1.0 - p; 1868 1869 n->as_MachIf()->_prob = p; 1870 } 1871 1872 //------------------------------update_succ_freq------------------------------- 1873 // Update the appropriate frequency associated with block 'b', a successor of 1874 // a block in this loop. 1875 void CFGLoop::update_succ_freq(Block* b, float freq) { 1876 if (b->_loop == this) { 1877 if (b == head()) { 1878 // back branch within the loop 1879 // Do nothing now, the loop carried frequency will be 1880 // adjust later in scale_freq(). 1881 } else { 1882 // simple branch within the loop 1883 b->_freq += freq; 1884 } 1885 } else if (!in_loop_nest(b)) { 1886 // branch is exit from this loop 1887 BlockProbPair bpp(b, freq); 1888 _exits.append(bpp); 1889 } else { 1890 // branch into nested loop 1891 CFGLoop* ch = b->_loop; 1892 ch->_freq += freq; 1893 } 1894 } 1895 1896 //------------------------------in_loop_nest----------------------------------- 1897 // Determine if block b is in the receiver's loop nest. 1898 bool CFGLoop::in_loop_nest(Block* b) { 1899 int depth = _depth; 1900 CFGLoop* b_loop = b->_loop; 1901 int b_depth = b_loop->_depth; 1902 if (depth == b_depth) { 1903 return true; 1904 } 1905 while (b_depth > depth) { 1906 b_loop = b_loop->_parent; 1907 b_depth = b_loop->_depth; 1908 } 1909 return b_loop == this; 1910 } 1911 1912 //------------------------------scale_freq------------------------------------- 1913 // Scale frequency of loops and blocks by trip counts from outer loops 1914 // Do a top down traversal of loop tree (visit outer loops first.) 1915 void CFGLoop::scale_freq() { 1916 float loop_freq = _freq * trip_count(); 1917 _freq = loop_freq; 1918 for (int i = 0; i < _members.length(); i++) { 1919 CFGElement* s = _members.at(i); 1920 float block_freq = s->_freq * loop_freq; 1921 if (g_isnan(block_freq) || block_freq < MIN_BLOCK_FREQUENCY) 1922 block_freq = MIN_BLOCK_FREQUENCY; 1923 s->_freq = block_freq; 1924 } 1925 CFGLoop* ch = _child; 1926 while (ch != NULL) { 1927 ch->scale_freq(); 1928 ch = ch->_sibling; 1929 } 1930 } 1931 1932 // Frequency of outer loop 1933 float CFGLoop::outer_loop_freq() const { 1934 if (_child != NULL) { 1935 return _child->_freq; 1936 } 1937 return _freq; 1938 } 1939 1940 #ifndef PRODUCT 1941 //------------------------------dump_tree-------------------------------------- 1942 void CFGLoop::dump_tree() const { 1943 dump(); 1944 if (_child != NULL) _child->dump_tree(); 1945 if (_sibling != NULL) _sibling->dump_tree(); 1946 } 1947 1948 //------------------------------dump------------------------------------------- 1949 void CFGLoop::dump() const { 1950 for (int i = 0; i < _depth; i++) tty->print(" "); 1951 tty->print("%s: %d trip_count: %6.0f freq: %6.0f\n", 1952 _depth == 0 ? "Method" : "Loop", _id, trip_count(), _freq); 1953 for (int i = 0; i < _depth; i++) tty->print(" "); 1954 tty->print(" members:", _id); 1955 int k = 0; 1956 for (int i = 0; i < _members.length(); i++) { 1957 if (k++ >= 6) { 1958 tty->print("\n "); 1959 for (int j = 0; j < _depth+1; j++) tty->print(" "); 1960 k = 0; 1961 } 1962 CFGElement *s = _members.at(i); 1963 if (s->is_block()) { 1964 Block *b = s->as_Block(); 1965 tty->print(" B%d(%6.3f)", b->_pre_order, b->_freq); 1966 } else { 1967 CFGLoop* lp = s->as_CFGLoop(); 1968 tty->print(" L%d(%6.3f)", lp->_id, lp->_freq); 1969 } 1970 } 1971 tty->print("\n"); 1972 for (int i = 0; i < _depth; i++) tty->print(" "); 1973 tty->print(" exits: "); 1974 k = 0; 1975 for (int i = 0; i < _exits.length(); i++) { 1976 if (k++ >= 7) { 1977 tty->print("\n "); 1978 for (int j = 0; j < _depth+1; j++) tty->print(" "); 1979 k = 0; 1980 } 1981 Block *blk = _exits.at(i).get_target(); 1982 float prob = _exits.at(i).get_prob(); 1983 tty->print(" ->%d@%d%%", blk->_pre_order, (int)(prob*100)); 1984 } 1985 tty->print("\n"); 1986 } 1987 #endif