gcm.cpp revision 5776:de6a9e811145
1/* 2 * Copyright (c) 1997, 2013, 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 "libadt/vectset.hpp" 27#include "memory/allocation.inline.hpp" 28#include "opto/block.hpp" 29#include "opto/c2compiler.hpp" 30#include "opto/callnode.hpp" 31#include "opto/cfgnode.hpp" 32#include "opto/machnode.hpp" 33#include "opto/opcodes.hpp" 34#include "opto/phaseX.hpp" 35#include "opto/rootnode.hpp" 36#include "opto/runtime.hpp" 37#include "runtime/deoptimization.hpp" 38#ifdef TARGET_ARCH_MODEL_x86_32 39# include "adfiles/ad_x86_32.hpp" 40#endif 41#ifdef TARGET_ARCH_MODEL_x86_64 42# include "adfiles/ad_x86_64.hpp" 43#endif 44#ifdef TARGET_ARCH_MODEL_sparc 45# include "adfiles/ad_sparc.hpp" 46#endif 47#ifdef TARGET_ARCH_MODEL_zero 48# include "adfiles/ad_zero.hpp" 49#endif 50#ifdef TARGET_ARCH_MODEL_arm 51# include "adfiles/ad_arm.hpp" 52#endif 53#ifdef TARGET_ARCH_MODEL_ppc 54# include "adfiles/ad_ppc.hpp" 55#endif 56 57// Portions of code courtesy of Clifford Click 58 59// Optimization - Graph Style 60 61// To avoid float value underflow 62#define MIN_BLOCK_FREQUENCY 1.e-35f 63 64//----------------------------schedule_node_into_block------------------------- 65// Insert node n into block b. Look for projections of n and make sure they 66// are in b also. 67void PhaseCFG::schedule_node_into_block( Node *n, Block *b ) { 68 // Set basic block of n, Add n to b, 69 map_node_to_block(n, b); 70 b->add_inst(n); 71 72 // After Matching, nearly any old Node may have projections trailing it. 73 // These are usually machine-dependent flags. In any case, they might 74 // float to another block below this one. Move them up. 75 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { 76 Node* use = n->fast_out(i); 77 if (use->is_Proj()) { 78 Block* buse = get_block_for_node(use); 79 if (buse != b) { // In wrong block? 80 if (buse != NULL) { 81 buse->find_remove(use); // Remove from wrong block 82 } 83 map_node_to_block(use, b); 84 b->add_inst(use); 85 } 86 } 87 } 88} 89 90//----------------------------replace_block_proj_ctrl------------------------- 91// Nodes that have is_block_proj() nodes as their control need to use 92// the appropriate Region for their actual block as their control since 93// the projection will be in a predecessor block. 94void PhaseCFG::replace_block_proj_ctrl( Node *n ) { 95 const Node *in0 = n->in(0); 96 assert(in0 != NULL, "Only control-dependent"); 97 const Node *p = in0->is_block_proj(); 98 if (p != NULL && p != n) { // Control from a block projection? 99 assert(!n->pinned() || n->is_MachConstantBase(), "only pinned MachConstantBase node is expected here"); 100 // Find trailing Region 101 Block *pb = get_block_for_node(in0); // Block-projection already has basic block 102 uint j = 0; 103 if (pb->_num_succs != 1) { // More then 1 successor? 104 // Search for successor 105 uint max = pb->number_of_nodes(); 106 assert( max > 1, "" ); 107 uint start = max - pb->_num_succs; 108 // Find which output path belongs to projection 109 for (j = start; j < max; j++) { 110 if( pb->get_node(j) == in0 ) 111 break; 112 } 113 assert( j < max, "must find" ); 114 // Change control to match head of successor basic block 115 j -= start; 116 } 117 n->set_req(0, pb->_succs[j]->head()); 118 } 119} 120 121 122//------------------------------schedule_pinned_nodes-------------------------- 123// Set the basic block for Nodes pinned into blocks 124void PhaseCFG::schedule_pinned_nodes(VectorSet &visited) { 125 // Allocate node stack of size C->unique()+8 to avoid frequent realloc 126 GrowableArray <Node *> spstack(C->unique() + 8); 127 spstack.push(_root); 128 while (spstack.is_nonempty()) { 129 Node* node = spstack.pop(); 130 if (!visited.test_set(node->_idx)) { // Test node and flag it as visited 131 if (node->pinned() && !has_block(node)) { // Pinned? Nail it down! 132 assert(node->in(0), "pinned Node must have Control"); 133 // Before setting block replace block_proj control edge 134 replace_block_proj_ctrl(node); 135 Node* input = node->in(0); 136 while (!input->is_block_start()) { 137 input = input->in(0); 138 } 139 Block* block = get_block_for_node(input); // Basic block of controlling input 140 schedule_node_into_block(node, block); 141 } 142 143 // process all inputs that are non NULL 144 for (int i = node->req() - 1; i >= 0; --i) { 145 if (node->in(i) != NULL) { 146 spstack.push(node->in(i)); 147 } 148 } 149 } 150 } 151} 152 153#ifdef ASSERT 154// Assert that new input b2 is dominated by all previous inputs. 155// Check this by by seeing that it is dominated by b1, the deepest 156// input observed until b2. 157static void assert_dom(Block* b1, Block* b2, Node* n, const PhaseCFG* cfg) { 158 if (b1 == NULL) return; 159 assert(b1->_dom_depth < b2->_dom_depth, "sanity"); 160 Block* tmp = b2; 161 while (tmp != b1 && tmp != NULL) { 162 tmp = tmp->_idom; 163 } 164 if (tmp != b1) { 165 // Detected an unschedulable graph. Print some nice stuff and die. 166 tty->print_cr("!!! Unschedulable graph !!!"); 167 for (uint j=0; j<n->len(); j++) { // For all inputs 168 Node* inn = n->in(j); // Get input 169 if (inn == NULL) continue; // Ignore NULL, missing inputs 170 Block* inb = cfg->get_block_for_node(inn); 171 tty->print("B%d idom=B%d depth=%2d ",inb->_pre_order, 172 inb->_idom ? inb->_idom->_pre_order : 0, inb->_dom_depth); 173 inn->dump(); 174 } 175 tty->print("Failing node: "); 176 n->dump(); 177 assert(false, "unscheduable graph"); 178 } 179} 180#endif 181 182static Block* find_deepest_input(Node* n, const PhaseCFG* cfg) { 183 // Find the last input dominated by all other inputs. 184 Block* deepb = NULL; // Deepest block so far 185 int deepb_dom_depth = 0; 186 for (uint k = 0; k < n->len(); k++) { // For all inputs 187 Node* inn = n->in(k); // Get input 188 if (inn == NULL) continue; // Ignore NULL, missing inputs 189 Block* inb = cfg->get_block_for_node(inn); 190 assert(inb != NULL, "must already have scheduled this input"); 191 if (deepb_dom_depth < (int) inb->_dom_depth) { 192 // The new inb must be dominated by the previous deepb. 193 // The various inputs must be linearly ordered in the dom 194 // tree, or else there will not be a unique deepest block. 195 DEBUG_ONLY(assert_dom(deepb, inb, n, cfg)); 196 deepb = inb; // Save deepest block 197 deepb_dom_depth = deepb->_dom_depth; 198 } 199 } 200 assert(deepb != NULL, "must be at least one input to n"); 201 return deepb; 202} 203 204 205//------------------------------schedule_early--------------------------------- 206// Find the earliest Block any instruction can be placed in. Some instructions 207// are pinned into Blocks. Unpinned instructions can appear in last block in 208// which all their inputs occur. 209bool PhaseCFG::schedule_early(VectorSet &visited, Node_List &roots) { 210 // Allocate stack with enough space to avoid frequent realloc 211 Node_Stack nstack(roots.Size() + 8); 212 // _root will be processed among C->top() inputs 213 roots.push(C->top()); 214 visited.set(C->top()->_idx); 215 216 while (roots.size() != 0) { 217 // Use local variables nstack_top_n & nstack_top_i to cache values 218 // on stack's top. 219 Node* parent_node = roots.pop(); 220 uint input_index = 0; 221 222 while (true) { 223 if (input_index == 0) { 224 // Fixup some control. Constants without control get attached 225 // to root and nodes that use is_block_proj() nodes should be attached 226 // to the region that starts their block. 227 const Node* control_input = parent_node->in(0); 228 if (control_input != NULL) { 229 replace_block_proj_ctrl(parent_node); 230 } else { 231 // Is a constant with NO inputs? 232 if (parent_node->req() == 1) { 233 parent_node->set_req(0, _root); 234 } 235 } 236 } 237 238 // First, visit all inputs and force them to get a block. If an 239 // input is already in a block we quit following inputs (to avoid 240 // cycles). Instead we put that Node on a worklist to be handled 241 // later (since IT'S inputs may not have a block yet). 242 243 // Assume all n's inputs will be processed 244 bool done = true; 245 246 while (input_index < parent_node->len()) { 247 Node* in = parent_node->in(input_index++); 248 if (in == NULL) { 249 continue; 250 } 251 252 int is_visited = visited.test_set(in->_idx); 253 if (!has_block(in)) { 254 if (is_visited) { 255 return false; 256 } 257 // Save parent node and next input's index. 258 nstack.push(parent_node, input_index); 259 // Process current input now. 260 parent_node = in; 261 input_index = 0; 262 // Not all n's inputs processed. 263 done = false; 264 break; 265 } else if (!is_visited) { 266 // Visit this guy later, using worklist 267 roots.push(in); 268 } 269 } 270 271 if (done) { 272 // All of n's inputs have been processed, complete post-processing. 273 274 // Some instructions are pinned into a block. These include Region, 275 // Phi, Start, Return, and other control-dependent instructions and 276 // any projections which depend on them. 277 if (!parent_node->pinned()) { 278 // Set earliest legal block. 279 Block* earliest_block = find_deepest_input(parent_node, this); 280 map_node_to_block(parent_node, earliest_block); 281 } else { 282 assert(get_block_for_node(parent_node) == get_block_for_node(parent_node->in(0)), "Pinned Node should be at the same block as its control edge"); 283 } 284 285 if (nstack.is_empty()) { 286 // Finished all nodes on stack. 287 // Process next node on the worklist 'roots'. 288 break; 289 } 290 // Get saved parent node and next input's index. 291 parent_node = nstack.node(); 292 input_index = nstack.index(); 293 nstack.pop(); 294 } 295 } 296 } 297 return true; 298} 299 300//------------------------------dom_lca---------------------------------------- 301// Find least common ancestor in dominator tree 302// LCA is a current notion of LCA, to be raised above 'this'. 303// As a convenient boundary condition, return 'this' if LCA is NULL. 304// Find the LCA of those two nodes. 305Block* Block::dom_lca(Block* LCA) { 306 if (LCA == NULL || LCA == this) return this; 307 308 Block* anc = this; 309 while (anc->_dom_depth > LCA->_dom_depth) 310 anc = anc->_idom; // Walk up till anc is as high as LCA 311 312 while (LCA->_dom_depth > anc->_dom_depth) 313 LCA = LCA->_idom; // Walk up till LCA is as high as anc 314 315 while (LCA != anc) { // Walk both up till they are the same 316 LCA = LCA->_idom; 317 anc = anc->_idom; 318 } 319 320 return LCA; 321} 322 323//--------------------------raise_LCA_above_use-------------------------------- 324// We are placing a definition, and have been given a def->use edge. 325// The definition must dominate the use, so move the LCA upward in the 326// dominator tree to dominate the use. If the use is a phi, adjust 327// the LCA only with the phi input paths which actually use this def. 328static Block* raise_LCA_above_use(Block* LCA, Node* use, Node* def, const PhaseCFG* cfg) { 329 Block* buse = cfg->get_block_for_node(use); 330 if (buse == NULL) return LCA; // Unused killing Projs have no use block 331 if (!use->is_Phi()) return buse->dom_lca(LCA); 332 uint pmax = use->req(); // Number of Phi inputs 333 // Why does not this loop just break after finding the matching input to 334 // the Phi? Well...it's like this. I do not have true def-use/use-def 335 // chains. Means I cannot distinguish, from the def-use direction, which 336 // of many use-defs lead from the same use to the same def. That is, this 337 // Phi might have several uses of the same def. Each use appears in a 338 // different predecessor block. But when I enter here, I cannot distinguish 339 // which use-def edge I should find the predecessor block for. So I find 340 // them all. Means I do a little extra work if a Phi uses the same value 341 // more than once. 342 for (uint j=1; j<pmax; j++) { // For all inputs 343 if (use->in(j) == def) { // Found matching input? 344 Block* pred = cfg->get_block_for_node(buse->pred(j)); 345 LCA = pred->dom_lca(LCA); 346 } 347 } 348 return LCA; 349} 350 351//----------------------------raise_LCA_above_marks---------------------------- 352// Return a new LCA that dominates LCA and any of its marked predecessors. 353// Search all my parents up to 'early' (exclusive), looking for predecessors 354// which are marked with the given index. Return the LCA (in the dom tree) 355// of all marked blocks. If there are none marked, return the original 356// LCA. 357static Block* raise_LCA_above_marks(Block* LCA, node_idx_t mark, Block* early, const PhaseCFG* cfg) { 358 Block_List worklist; 359 worklist.push(LCA); 360 while (worklist.size() > 0) { 361 Block* mid = worklist.pop(); 362 if (mid == early) continue; // stop searching here 363 364 // Test and set the visited bit. 365 if (mid->raise_LCA_visited() == mark) continue; // already visited 366 367 // Don't process the current LCA, otherwise the search may terminate early 368 if (mid != LCA && mid->raise_LCA_mark() == mark) { 369 // Raise the LCA. 370 LCA = mid->dom_lca(LCA); 371 if (LCA == early) break; // stop searching everywhere 372 assert(early->dominates(LCA), "early is high enough"); 373 // Resume searching at that point, skipping intermediate levels. 374 worklist.push(LCA); 375 if (LCA == mid) 376 continue; // Don't mark as visited to avoid early termination. 377 } else { 378 // Keep searching through this block's predecessors. 379 for (uint j = 1, jmax = mid->num_preds(); j < jmax; j++) { 380 Block* mid_parent = cfg->get_block_for_node(mid->pred(j)); 381 worklist.push(mid_parent); 382 } 383 } 384 mid->set_raise_LCA_visited(mark); 385 } 386 return LCA; 387} 388 389//--------------------------memory_early_block-------------------------------- 390// This is a variation of find_deepest_input, the heart of schedule_early. 391// Find the "early" block for a load, if we considered only memory and 392// address inputs, that is, if other data inputs were ignored. 393// 394// Because a subset of edges are considered, the resulting block will 395// be earlier (at a shallower dom_depth) than the true schedule_early 396// point of the node. We compute this earlier block as a more permissive 397// site for anti-dependency insertion, but only if subsume_loads is enabled. 398static Block* memory_early_block(Node* load, Block* early, const PhaseCFG* cfg) { 399 Node* base; 400 Node* index; 401 Node* store = load->in(MemNode::Memory); 402 load->as_Mach()->memory_inputs(base, index); 403 404 assert(base != NodeSentinel && index != NodeSentinel, 405 "unexpected base/index inputs"); 406 407 Node* mem_inputs[4]; 408 int mem_inputs_length = 0; 409 if (base != NULL) mem_inputs[mem_inputs_length++] = base; 410 if (index != NULL) mem_inputs[mem_inputs_length++] = index; 411 if (store != NULL) mem_inputs[mem_inputs_length++] = store; 412 413 // In the comparision below, add one to account for the control input, 414 // which may be null, but always takes up a spot in the in array. 415 if (mem_inputs_length + 1 < (int) load->req()) { 416 // This "load" has more inputs than just the memory, base and index inputs. 417 // For purposes of checking anti-dependences, we need to start 418 // from the early block of only the address portion of the instruction, 419 // and ignore other blocks that may have factored into the wider 420 // schedule_early calculation. 421 if (load->in(0) != NULL) mem_inputs[mem_inputs_length++] = load->in(0); 422 423 Block* deepb = NULL; // Deepest block so far 424 int deepb_dom_depth = 0; 425 for (int i = 0; i < mem_inputs_length; i++) { 426 Block* inb = cfg->get_block_for_node(mem_inputs[i]); 427 if (deepb_dom_depth < (int) inb->_dom_depth) { 428 // The new inb must be dominated by the previous deepb. 429 // The various inputs must be linearly ordered in the dom 430 // tree, or else there will not be a unique deepest block. 431 DEBUG_ONLY(assert_dom(deepb, inb, load, cfg)); 432 deepb = inb; // Save deepest block 433 deepb_dom_depth = deepb->_dom_depth; 434 } 435 } 436 early = deepb; 437 } 438 439 return early; 440} 441 442//--------------------------insert_anti_dependences--------------------------- 443// A load may need to witness memory that nearby stores can overwrite. 444// For each nearby store, either insert an "anti-dependence" edge 445// from the load to the store, or else move LCA upward to force the 446// load to (eventually) be scheduled in a block above the store. 447// 448// Do not add edges to stores on distinct control-flow paths; 449// only add edges to stores which might interfere. 450// 451// Return the (updated) LCA. There will not be any possibly interfering 452// store between the load's "early block" and the updated LCA. 453// Any stores in the updated LCA will have new precedence edges 454// back to the load. The caller is expected to schedule the load 455// in the LCA, in which case the precedence edges will make LCM 456// preserve anti-dependences. The caller may also hoist the load 457// above the LCA, if it is not the early block. 458Block* PhaseCFG::insert_anti_dependences(Block* LCA, Node* load, bool verify) { 459 assert(load->needs_anti_dependence_check(), "must be a load of some sort"); 460 assert(LCA != NULL, ""); 461 DEBUG_ONLY(Block* LCA_orig = LCA); 462 463 // Compute the alias index. Loads and stores with different alias indices 464 // do not need anti-dependence edges. 465 uint load_alias_idx = C->get_alias_index(load->adr_type()); 466#ifdef ASSERT 467 if (load_alias_idx == Compile::AliasIdxBot && C->AliasLevel() > 0 && 468 (PrintOpto || VerifyAliases || 469 PrintMiscellaneous && (WizardMode || Verbose))) { 470 // Load nodes should not consume all of memory. 471 // Reporting a bottom type indicates a bug in adlc. 472 // If some particular type of node validly consumes all of memory, 473 // sharpen the preceding "if" to exclude it, so we can catch bugs here. 474 tty->print_cr("*** Possible Anti-Dependence Bug: Load consumes all of memory."); 475 load->dump(2); 476 if (VerifyAliases) assert(load_alias_idx != Compile::AliasIdxBot, ""); 477 } 478#endif 479 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrComp), 480 "String compare is only known 'load' that does not conflict with any stores"); 481 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrEquals), 482 "String equals is a 'load' that does not conflict with any stores"); 483 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_StrIndexOf), 484 "String indexOf is a 'load' that does not conflict with any stores"); 485 assert(load_alias_idx || (load->is_Mach() && load->as_Mach()->ideal_Opcode() == Op_AryEq), 486 "Arrays equals is a 'load' that do not conflict with any stores"); 487 488 if (!C->alias_type(load_alias_idx)->is_rewritable()) { 489 // It is impossible to spoil this load by putting stores before it, 490 // because we know that the stores will never update the value 491 // which 'load' must witness. 492 return LCA; 493 } 494 495 node_idx_t load_index = load->_idx; 496 497 // Note the earliest legal placement of 'load', as determined by 498 // by the unique point in the dom tree where all memory effects 499 // and other inputs are first available. (Computed by schedule_early.) 500 // For normal loads, 'early' is the shallowest place (dom graph wise) 501 // to look for anti-deps between this load and any store. 502 Block* early = get_block_for_node(load); 503 504 // If we are subsuming loads, compute an "early" block that only considers 505 // memory or address inputs. This block may be different than the 506 // schedule_early block in that it could be at an even shallower depth in the 507 // dominator tree, and allow for a broader discovery of anti-dependences. 508 if (C->subsume_loads()) { 509 early = memory_early_block(load, early, this); 510 } 511 512 ResourceArea *area = Thread::current()->resource_area(); 513 Node_List worklist_mem(area); // prior memory state to store 514 Node_List worklist_store(area); // possible-def to explore 515 Node_List worklist_visited(area); // visited mergemem nodes 516 Node_List non_early_stores(area); // all relevant stores outside of early 517 bool must_raise_LCA = false; 518 519#ifdef TRACK_PHI_INPUTS 520 // %%% This extra checking fails because MergeMem nodes are not GVNed. 521 // Provide "phi_inputs" to check if every input to a PhiNode is from the 522 // original memory state. This indicates a PhiNode for which should not 523 // prevent the load from sinking. For such a block, set_raise_LCA_mark 524 // may be overly conservative. 525 // Mechanism: count inputs seen for each Phi encountered in worklist_store. 526 DEBUG_ONLY(GrowableArray<uint> phi_inputs(area, C->unique(),0,0)); 527#endif 528 529 // 'load' uses some memory state; look for users of the same state. 530 // Recurse through MergeMem nodes to the stores that use them. 531 532 // Each of these stores is a possible definition of memory 533 // that 'load' needs to use. We need to force 'load' 534 // to occur before each such store. When the store is in 535 // the same block as 'load', we insert an anti-dependence 536 // edge load->store. 537 538 // The relevant stores "nearby" the load consist of a tree rooted 539 // at initial_mem, with internal nodes of type MergeMem. 540 // Therefore, the branches visited by the worklist are of this form: 541 // initial_mem -> (MergeMem ->)* store 542 // The anti-dependence constraints apply only to the fringe of this tree. 543 544 Node* initial_mem = load->in(MemNode::Memory); 545 worklist_store.push(initial_mem); 546 worklist_visited.push(initial_mem); 547 worklist_mem.push(NULL); 548 while (worklist_store.size() > 0) { 549 // Examine a nearby store to see if it might interfere with our load. 550 Node* mem = worklist_mem.pop(); 551 Node* store = worklist_store.pop(); 552 uint op = store->Opcode(); 553 554 // MergeMems do not directly have anti-deps. 555 // Treat them as internal nodes in a forward tree of memory states, 556 // the leaves of which are each a 'possible-def'. 557 if (store == initial_mem // root (exclusive) of tree we are searching 558 || op == Op_MergeMem // internal node of tree we are searching 559 ) { 560 mem = store; // It's not a possibly interfering store. 561 if (store == initial_mem) 562 initial_mem = NULL; // only process initial memory once 563 564 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { 565 store = mem->fast_out(i); 566 if (store->is_MergeMem()) { 567 // Be sure we don't get into combinatorial problems. 568 // (Allow phis to be repeated; they can merge two relevant states.) 569 uint j = worklist_visited.size(); 570 for (; j > 0; j--) { 571 if (worklist_visited.at(j-1) == store) break; 572 } 573 if (j > 0) continue; // already on work list; do not repeat 574 worklist_visited.push(store); 575 } 576 worklist_mem.push(mem); 577 worklist_store.push(store); 578 } 579 continue; 580 } 581 582 if (op == Op_MachProj || op == Op_Catch) continue; 583 if (store->needs_anti_dependence_check()) continue; // not really a store 584 585 // Compute the alias index. Loads and stores with different alias 586 // indices do not need anti-dependence edges. Wide MemBar's are 587 // anti-dependent on everything (except immutable memories). 588 const TypePtr* adr_type = store->adr_type(); 589 if (!C->can_alias(adr_type, load_alias_idx)) continue; 590 591 // Most slow-path runtime calls do NOT modify Java memory, but 592 // they can block and so write Raw memory. 593 if (store->is_Mach()) { 594 MachNode* mstore = store->as_Mach(); 595 if (load_alias_idx != Compile::AliasIdxRaw) { 596 // Check for call into the runtime using the Java calling 597 // convention (and from there into a wrapper); it has no 598 // _method. Can't do this optimization for Native calls because 599 // they CAN write to Java memory. 600 if (mstore->ideal_Opcode() == Op_CallStaticJava) { 601 assert(mstore->is_MachSafePoint(), ""); 602 MachSafePointNode* ms = (MachSafePointNode*) mstore; 603 assert(ms->is_MachCallJava(), ""); 604 MachCallJavaNode* mcj = (MachCallJavaNode*) ms; 605 if (mcj->_method == NULL) { 606 // These runtime calls do not write to Java visible memory 607 // (other than Raw) and so do not require anti-dependence edges. 608 continue; 609 } 610 } 611 // Same for SafePoints: they read/write Raw but only read otherwise. 612 // This is basically a workaround for SafePoints only defining control 613 // instead of control + memory. 614 if (mstore->ideal_Opcode() == Op_SafePoint) 615 continue; 616 } else { 617 // Some raw memory, such as the load of "top" at an allocation, 618 // can be control dependent on the previous safepoint. See 619 // comments in GraphKit::allocate_heap() about control input. 620 // Inserting an anti-dep between such a safepoint and a use 621 // creates a cycle, and will cause a subsequent failure in 622 // local scheduling. (BugId 4919904) 623 // (%%% How can a control input be a safepoint and not a projection??) 624 if (mstore->ideal_Opcode() == Op_SafePoint && load->in(0) == mstore) 625 continue; 626 } 627 } 628 629 // Identify a block that the current load must be above, 630 // or else observe that 'store' is all the way up in the 631 // earliest legal block for 'load'. In the latter case, 632 // immediately insert an anti-dependence edge. 633 Block* store_block = get_block_for_node(store); 634 assert(store_block != NULL, "unused killing projections skipped above"); 635 636 if (store->is_Phi()) { 637 // 'load' uses memory which is one (or more) of the Phi's inputs. 638 // It must be scheduled not before the Phi, but rather before 639 // each of the relevant Phi inputs. 640 // 641 // Instead of finding the LCA of all inputs to a Phi that match 'mem', 642 // we mark each corresponding predecessor block and do a combined 643 // hoisting operation later (raise_LCA_above_marks). 644 // 645 // Do not assert(store_block != early, "Phi merging memory after access") 646 // PhiNode may be at start of block 'early' with backedge to 'early' 647 DEBUG_ONLY(bool found_match = false); 648 for (uint j = PhiNode::Input, jmax = store->req(); j < jmax; j++) { 649 if (store->in(j) == mem) { // Found matching input? 650 DEBUG_ONLY(found_match = true); 651 Block* pred_block = get_block_for_node(store_block->pred(j)); 652 if (pred_block != early) { 653 // If any predecessor of the Phi matches the load's "early block", 654 // we do not need a precedence edge between the Phi and 'load' 655 // since the load will be forced into a block preceding the Phi. 656 pred_block->set_raise_LCA_mark(load_index); 657 assert(!LCA_orig->dominates(pred_block) || 658 early->dominates(pred_block), "early is high enough"); 659 must_raise_LCA = true; 660 } else { 661 // anti-dependent upon PHI pinned below 'early', no edge needed 662 LCA = early; // but can not schedule below 'early' 663 } 664 } 665 } 666 assert(found_match, "no worklist bug"); 667#ifdef TRACK_PHI_INPUTS 668#ifdef ASSERT 669 // This assert asks about correct handling of PhiNodes, which may not 670 // have all input edges directly from 'mem'. See BugId 4621264 671 int num_mem_inputs = phi_inputs.at_grow(store->_idx,0) + 1; 672 // Increment by exactly one even if there are multiple copies of 'mem' 673 // coming into the phi, because we will run this block several times 674 // if there are several copies of 'mem'. (That's how DU iterators work.) 675 phi_inputs.at_put(store->_idx, num_mem_inputs); 676 assert(PhiNode::Input + num_mem_inputs < store->req(), 677 "Expect at least one phi input will not be from original memory state"); 678#endif //ASSERT 679#endif //TRACK_PHI_INPUTS 680 } else if (store_block != early) { 681 // 'store' is between the current LCA and earliest possible block. 682 // Label its block, and decide later on how to raise the LCA 683 // to include the effect on LCA of this store. 684 // If this store's block gets chosen as the raised LCA, we 685 // will find him on the non_early_stores list and stick him 686 // with a precedence edge. 687 // (But, don't bother if LCA is already raised all the way.) 688 if (LCA != early) { 689 store_block->set_raise_LCA_mark(load_index); 690 must_raise_LCA = true; 691 non_early_stores.push(store); 692 } 693 } else { 694 // Found a possibly-interfering store in the load's 'early' block. 695 // This means 'load' cannot sink at all in the dominator tree. 696 // Add an anti-dep edge, and squeeze 'load' into the highest 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 LCA = early; 704 // This turns off the process of gathering non_early_stores. 705 } 706 } 707 // (Worklist is now empty; all nearby stores have been visited.) 708 709 // Finished if 'load' must be scheduled in its 'early' block. 710 // If we found any stores there, they have already been given 711 // precedence edges. 712 if (LCA == early) return LCA; 713 714 // We get here only if there are no possibly-interfering stores 715 // in the load's 'early' block. Move LCA up above all predecessors 716 // which contain stores we have noted. 717 // 718 // The raised LCA block can be a home to such interfering stores, 719 // but its predecessors must not contain any such stores. 720 // 721 // The raised LCA will be a lower bound for placing the load, 722 // preventing the load from sinking past any block containing 723 // a store that may invalidate the memory state required by 'load'. 724 if (must_raise_LCA) 725 LCA = raise_LCA_above_marks(LCA, load->_idx, early, this); 726 if (LCA == early) return LCA; 727 728 // Insert anti-dependence edges from 'load' to each store 729 // in the non-early LCA block. 730 // Mine the non_early_stores list for such stores. 731 if (LCA->raise_LCA_mark() == load_index) { 732 while (non_early_stores.size() > 0) { 733 Node* store = non_early_stores.pop(); 734 Block* store_block = get_block_for_node(store); 735 if (store_block == LCA) { 736 // add anti_dependence from store to load in its own block 737 assert(store != load->in(0), "dependence cycle found"); 738 if (verify) { 739 assert(store->find_edge(load) != -1, "missing precedence edge"); 740 } else { 741 store->add_prec(load); 742 } 743 } else { 744 assert(store_block->raise_LCA_mark() == load_index, "block was marked"); 745 // Any other stores we found must be either inside the new LCA 746 // or else outside the original LCA. In the latter case, they 747 // did not interfere with any use of 'load'. 748 assert(LCA->dominates(store_block) 749 || !LCA_orig->dominates(store_block), "no stray stores"); 750 } 751 } 752 } 753 754 // Return the highest block containing stores; any stores 755 // within that block have been given anti-dependence edges. 756 return LCA; 757} 758 759// This class is used to iterate backwards over the nodes in the graph. 760 761class Node_Backward_Iterator { 762 763private: 764 Node_Backward_Iterator(); 765 766public: 767 // Constructor for the iterator 768 Node_Backward_Iterator(Node *root, VectorSet &visited, Node_List &stack, PhaseCFG &cfg); 769 770 // Postincrement operator to iterate over the nodes 771 Node *next(); 772 773private: 774 VectorSet &_visited; 775 Node_List &_stack; 776 PhaseCFG &_cfg; 777}; 778 779// Constructor for the Node_Backward_Iterator 780Node_Backward_Iterator::Node_Backward_Iterator( Node *root, VectorSet &visited, Node_List &stack, PhaseCFG &cfg) 781 : _visited(visited), _stack(stack), _cfg(cfg) { 782 // The stack should contain exactly the root 783 stack.clear(); 784 stack.push(root); 785 786 // Clear the visited bits 787 visited.Clear(); 788} 789 790// Iterator for the Node_Backward_Iterator 791Node *Node_Backward_Iterator::next() { 792 793 // If the _stack is empty, then just return NULL: finished. 794 if ( !_stack.size() ) 795 return NULL; 796 797 // '_stack' is emulating a real _stack. The 'visit-all-users' loop has been 798 // made stateless, so I do not need to record the index 'i' on my _stack. 799 // Instead I visit all users each time, scanning for unvisited users. 800 // I visit unvisited not-anti-dependence users first, then anti-dependent 801 // children next. 802 Node *self = _stack.pop(); 803 804 // I cycle here when I am entering a deeper level of recursion. 805 // The key variable 'self' was set prior to jumping here. 806 while( 1 ) { 807 808 _visited.set(self->_idx); 809 810 // Now schedule all uses as late as possible. 811 const Node* src = self->is_Proj() ? self->in(0) : self; 812 uint src_rpo = _cfg.get_block_for_node(src)->_rpo; 813 814 // Schedule all nodes in a post-order visit 815 Node *unvisited = NULL; // Unvisited anti-dependent Node, if any 816 817 // Scan for unvisited nodes 818 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) { 819 // For all uses, schedule late 820 Node* n = self->fast_out(i); // Use 821 822 // Skip already visited children 823 if ( _visited.test(n->_idx) ) 824 continue; 825 826 // do not traverse backward control edges 827 Node *use = n->is_Proj() ? n->in(0) : n; 828 uint use_rpo = _cfg.get_block_for_node(use)->_rpo; 829 830 if ( use_rpo < src_rpo ) 831 continue; 832 833 // Phi nodes always precede uses in a basic block 834 if ( use_rpo == src_rpo && use->is_Phi() ) 835 continue; 836 837 unvisited = n; // Found unvisited 838 839 // Check for possible-anti-dependent 840 if( !n->needs_anti_dependence_check() ) 841 break; // Not visited, not anti-dep; schedule it NOW 842 } 843 844 // Did I find an unvisited not-anti-dependent Node? 845 if ( !unvisited ) 846 break; // All done with children; post-visit 'self' 847 848 // Visit the unvisited Node. Contains the obvious push to 849 // indicate I'm entering a deeper level of recursion. I push the 850 // old state onto the _stack and set a new state and loop (recurse). 851 _stack.push(self); 852 self = unvisited; 853 } // End recursion loop 854 855 return self; 856} 857 858//------------------------------ComputeLatenciesBackwards---------------------- 859// Compute the latency of all the instructions. 860void PhaseCFG::compute_latencies_backwards(VectorSet &visited, Node_List &stack) { 861#ifndef PRODUCT 862 if (trace_opto_pipelining()) 863 tty->print("\n#---- ComputeLatenciesBackwards ----\n"); 864#endif 865 866 Node_Backward_Iterator iter((Node *)_root, visited, stack, *this); 867 Node *n; 868 869 // Walk over all the nodes from last to first 870 while (n = iter.next()) { 871 // Set the latency for the definitions of this instruction 872 partial_latency_of_defs(n); 873 } 874} // end ComputeLatenciesBackwards 875 876//------------------------------partial_latency_of_defs------------------------ 877// Compute the latency impact of this node on all defs. This computes 878// a number that increases as we approach the beginning of the routine. 879void PhaseCFG::partial_latency_of_defs(Node *n) { 880 // Set the latency for this instruction 881#ifndef PRODUCT 882 if (trace_opto_pipelining()) { 883 tty->print("# latency_to_inputs: node_latency[%d] = %d for node", n->_idx, get_latency_for_node(n)); 884 dump(); 885 } 886#endif 887 888 if (n->is_Proj()) { 889 n = n->in(0); 890 } 891 892 if (n->is_Root()) { 893 return; 894 } 895 896 uint nlen = n->len(); 897 uint use_latency = get_latency_for_node(n); 898 uint use_pre_order = get_block_for_node(n)->_pre_order; 899 900 for (uint j = 0; j < nlen; j++) { 901 Node *def = n->in(j); 902 903 if (!def || def == n) { 904 continue; 905 } 906 907 // Walk backwards thru projections 908 if (def->is_Proj()) { 909 def = def->in(0); 910 } 911 912#ifndef PRODUCT 913 if (trace_opto_pipelining()) { 914 tty->print("# in(%2d): ", j); 915 def->dump(); 916 } 917#endif 918 919 // If the defining block is not known, assume it is ok 920 Block *def_block = get_block_for_node(def); 921 uint def_pre_order = def_block ? def_block->_pre_order : 0; 922 923 if ((use_pre_order < def_pre_order) || (use_pre_order == def_pre_order && n->is_Phi())) { 924 continue; 925 } 926 927 uint delta_latency = n->latency(j); 928 uint current_latency = delta_latency + use_latency; 929 930 if (get_latency_for_node(def) < current_latency) { 931 set_latency_for_node(def, current_latency); 932 } 933 934#ifndef PRODUCT 935 if (trace_opto_pipelining()) { 936 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, node_latency[%d] = %d", use_latency, j, delta_latency, current_latency, def->_idx, get_latency_for_node(def)); 937 } 938#endif 939 } 940} 941 942//------------------------------latency_from_use------------------------------- 943// Compute the latency of a specific use 944int PhaseCFG::latency_from_use(Node *n, const Node *def, Node *use) { 945 // If self-reference, return no latency 946 if (use == n || use->is_Root()) { 947 return 0; 948 } 949 950 uint def_pre_order = get_block_for_node(def)->_pre_order; 951 uint latency = 0; 952 953 // If the use is not a projection, then it is simple... 954 if (!use->is_Proj()) { 955#ifndef PRODUCT 956 if (trace_opto_pipelining()) { 957 tty->print("# out(): "); 958 use->dump(); 959 } 960#endif 961 962 uint use_pre_order = get_block_for_node(use)->_pre_order; 963 964 if (use_pre_order < def_pre_order) 965 return 0; 966 967 if (use_pre_order == def_pre_order && use->is_Phi()) 968 return 0; 969 970 uint nlen = use->len(); 971 uint nl = get_latency_for_node(use); 972 973 for ( uint j=0; j<nlen; j++ ) { 974 if (use->in(j) == n) { 975 // Change this if we want local latencies 976 uint ul = use->latency(j); 977 uint l = ul + nl; 978 if (latency < l) latency = l; 979#ifndef PRODUCT 980 if (trace_opto_pipelining()) { 981 tty->print_cr("# %d + edge_latency(%d) == %d -> %d, latency = %d", 982 nl, j, ul, l, latency); 983 } 984#endif 985 } 986 } 987 } else { 988 // This is a projection, just grab the latency of the use(s) 989 for (DUIterator_Fast jmax, j = use->fast_outs(jmax); j < jmax; j++) { 990 uint l = latency_from_use(use, def, use->fast_out(j)); 991 if (latency < l) latency = l; 992 } 993 } 994 995 return latency; 996} 997 998//------------------------------latency_from_uses------------------------------ 999// Compute the latency of this instruction relative to all of it's uses. 1000// This computes a number that increases as we approach the beginning of the 1001// routine. 1002void PhaseCFG::latency_from_uses(Node *n) { 1003 // Set the latency for this instruction 1004#ifndef PRODUCT 1005 if (trace_opto_pipelining()) { 1006 tty->print("# latency_from_outputs: node_latency[%d] = %d for node", n->_idx, get_latency_for_node(n)); 1007 dump(); 1008 } 1009#endif 1010 uint latency=0; 1011 const Node *def = n->is_Proj() ? n->in(0): n; 1012 1013 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { 1014 uint l = latency_from_use(n, def, n->fast_out(i)); 1015 1016 if (latency < l) latency = l; 1017 } 1018 1019 set_latency_for_node(n, latency); 1020} 1021 1022//------------------------------hoist_to_cheaper_block------------------------- 1023// Pick a block for node self, between early and LCA, that is a cheaper 1024// alternative to LCA. 1025Block* PhaseCFG::hoist_to_cheaper_block(Block* LCA, Block* early, Node* self) { 1026 const double delta = 1+PROB_UNLIKELY_MAG(4); 1027 Block* least = LCA; 1028 double least_freq = least->_freq; 1029 uint target = get_latency_for_node(self); 1030 uint start_latency = get_latency_for_node(LCA->head()); 1031 uint end_latency = get_latency_for_node(LCA->get_node(LCA->end_idx())); 1032 bool in_latency = (target <= start_latency); 1033 const Block* root_block = get_block_for_node(_root); 1034 1035 // Turn off latency scheduling if scheduling is just plain off 1036 if (!C->do_scheduling()) 1037 in_latency = true; 1038 1039 // Do not hoist (to cover latency) instructions which target a 1040 // single register. Hoisting stretches the live range of the 1041 // single register and may force spilling. 1042 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL; 1043 if (mach && mach->out_RegMask().is_bound1() && mach->out_RegMask().is_NotEmpty()) 1044 in_latency = true; 1045 1046#ifndef PRODUCT 1047 if (trace_opto_pipelining()) { 1048 tty->print("# Find cheaper block for latency %d: ", get_latency_for_node(self)); 1049 self->dump(); 1050 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g", 1051 LCA->_pre_order, 1052 LCA->head()->_idx, 1053 start_latency, 1054 LCA->get_node(LCA->end_idx())->_idx, 1055 end_latency, 1056 least_freq); 1057 } 1058#endif 1059 1060 int cand_cnt = 0; // number of candidates tried 1061 1062 // Walk up the dominator tree from LCA (Lowest common ancestor) to 1063 // the earliest legal location. Capture the least execution frequency. 1064 while (LCA != early) { 1065 LCA = LCA->_idom; // Follow up the dominator tree 1066 1067 if (LCA == NULL) { 1068 // Bailout without retry 1069 C->record_method_not_compilable("late schedule failed: LCA == NULL"); 1070 return least; 1071 } 1072 1073 // Don't hoist machine instructions to the root basic block 1074 if (mach && LCA == root_block) 1075 break; 1076 1077 uint start_lat = get_latency_for_node(LCA->head()); 1078 uint end_idx = LCA->end_idx(); 1079 uint end_lat = get_latency_for_node(LCA->get_node(end_idx)); 1080 double LCA_freq = LCA->_freq; 1081#ifndef PRODUCT 1082 if (trace_opto_pipelining()) { 1083 tty->print_cr("# B%d: start latency for [%4d]=%d, end latency for [%4d]=%d, freq=%g", 1084 LCA->_pre_order, LCA->head()->_idx, start_lat, end_idx, end_lat, LCA_freq); 1085 } 1086#endif 1087 cand_cnt++; 1088 if (LCA_freq < least_freq || // Better Frequency 1089 (StressGCM && Compile::randomized_select(cand_cnt)) || // Should be randomly accepted in stress mode 1090 (!StressGCM && // Otherwise, choose with latency 1091 !in_latency && // No block containing latency 1092 LCA_freq < least_freq * delta && // No worse frequency 1093 target >= end_lat && // within latency range 1094 !self->is_iteratively_computed() ) // But don't hoist IV increments 1095 // because they may end up above other uses of their phi forcing 1096 // their result register to be different from their input. 1097 ) { 1098 least = LCA; // Found cheaper block 1099 least_freq = LCA_freq; 1100 start_latency = start_lat; 1101 end_latency = end_lat; 1102 if (target <= start_lat) 1103 in_latency = true; 1104 } 1105 } 1106 1107#ifndef PRODUCT 1108 if (trace_opto_pipelining()) { 1109 tty->print_cr("# Choose block B%d with start latency=%d and freq=%g", 1110 least->_pre_order, start_latency, least_freq); 1111 } 1112#endif 1113 1114 // See if the latency needs to be updated 1115 if (target < end_latency) { 1116#ifndef PRODUCT 1117 if (trace_opto_pipelining()) { 1118 tty->print_cr("# Change latency for [%4d] from %d to %d", self->_idx, target, end_latency); 1119 } 1120#endif 1121 set_latency_for_node(self, end_latency); 1122 partial_latency_of_defs(self); 1123 } 1124 1125 return least; 1126} 1127 1128 1129//------------------------------schedule_late----------------------------------- 1130// Now schedule all codes as LATE as possible. This is the LCA in the 1131// dominator tree of all USES of a value. Pick the block with the least 1132// loop nesting depth that is lowest in the dominator tree. 1133extern const char must_clone[]; 1134void PhaseCFG::schedule_late(VectorSet &visited, Node_List &stack) { 1135#ifndef PRODUCT 1136 if (trace_opto_pipelining()) 1137 tty->print("\n#---- schedule_late ----\n"); 1138#endif 1139 1140 Node_Backward_Iterator iter((Node *)_root, visited, stack, *this); 1141 Node *self; 1142 1143 // Walk over all the nodes from last to first 1144 while (self = iter.next()) { 1145 Block* early = get_block_for_node(self); // Earliest legal placement 1146 1147 if (self->is_top()) { 1148 // Top node goes in bb #2 with other constants. 1149 // It must be special-cased, because it has no out edges. 1150 early->add_inst(self); 1151 continue; 1152 } 1153 1154 // No uses, just terminate 1155 if (self->outcnt() == 0) { 1156 assert(self->is_MachProj(), "sanity"); 1157 continue; // Must be a dead machine projection 1158 } 1159 1160 // If node is pinned in the block, then no scheduling can be done. 1161 if( self->pinned() ) // Pinned in block? 1162 continue; 1163 1164 MachNode* mach = self->is_Mach() ? self->as_Mach() : NULL; 1165 if (mach) { 1166 switch (mach->ideal_Opcode()) { 1167 case Op_CreateEx: 1168 // Don't move exception creation 1169 early->add_inst(self); 1170 continue; 1171 break; 1172 case Op_CheckCastPP: 1173 // Don't move CheckCastPP nodes away from their input, if the input 1174 // is a rawptr (5071820). 1175 Node *def = self->in(1); 1176 if (def != NULL && def->bottom_type()->base() == Type::RawPtr) { 1177 early->add_inst(self); 1178#ifdef ASSERT 1179 _raw_oops.push(def); 1180#endif 1181 continue; 1182 } 1183 break; 1184 } 1185 } 1186 1187 // Gather LCA of all uses 1188 Block *LCA = NULL; 1189 { 1190 for (DUIterator_Fast imax, i = self->fast_outs(imax); i < imax; i++) { 1191 // For all uses, find LCA 1192 Node* use = self->fast_out(i); 1193 LCA = raise_LCA_above_use(LCA, use, self, this); 1194 } 1195 } // (Hide defs of imax, i from rest of block.) 1196 1197 // Place temps in the block of their use. This isn't a 1198 // requirement for correctness but it reduces useless 1199 // interference between temps and other nodes. 1200 if (mach != NULL && mach->is_MachTemp()) { 1201 map_node_to_block(self, LCA); 1202 LCA->add_inst(self); 1203 continue; 1204 } 1205 1206 // Check if 'self' could be anti-dependent on memory 1207 if (self->needs_anti_dependence_check()) { 1208 // Hoist LCA above possible-defs and insert anti-dependences to 1209 // defs in new LCA block. 1210 LCA = insert_anti_dependences(LCA, self); 1211 } 1212 1213 if (early->_dom_depth > LCA->_dom_depth) { 1214 // Somehow the LCA has moved above the earliest legal point. 1215 // (One way this can happen is via memory_early_block.) 1216 if (C->subsume_loads() == true && !C->failing()) { 1217 // Retry with subsume_loads == false 1218 // If this is the first failure, the sentinel string will "stick" 1219 // to the Compile object, and the C2Compiler will see it and retry. 1220 C->record_failure(C2Compiler::retry_no_subsuming_loads()); 1221 } else { 1222 // Bailout without retry when (early->_dom_depth > LCA->_dom_depth) 1223 C->record_method_not_compilable("late schedule failed: incorrect graph"); 1224 } 1225 return; 1226 } 1227 1228 // If there is no opportunity to hoist, then we're done. 1229 // In stress mode, try to hoist even the single operations. 1230 bool try_to_hoist = StressGCM || (LCA != early); 1231 1232 // Must clone guys stay next to use; no hoisting allowed. 1233 // Also cannot hoist guys that alter memory or are otherwise not 1234 // allocatable (hoisting can make a value live longer, leading to 1235 // anti and output dependency problems which are normally resolved 1236 // by the register allocator giving everyone a different register). 1237 if (mach != NULL && must_clone[mach->ideal_Opcode()]) 1238 try_to_hoist = false; 1239 1240 Block* late = NULL; 1241 if (try_to_hoist) { 1242 // Now find the block with the least execution frequency. 1243 // Start at the latest schedule and work up to the earliest schedule 1244 // in the dominator tree. Thus the Node will dominate all its uses. 1245 late = hoist_to_cheaper_block(LCA, early, self); 1246 } else { 1247 // Just use the LCA of the uses. 1248 late = LCA; 1249 } 1250 1251 // Put the node into target block 1252 schedule_node_into_block(self, late); 1253 1254#ifdef ASSERT 1255 if (self->needs_anti_dependence_check()) { 1256 // since precedence edges are only inserted when we're sure they 1257 // are needed make sure that after placement in a block we don't 1258 // need any new precedence edges. 1259 verify_anti_dependences(late, self); 1260 } 1261#endif 1262 } // Loop until all nodes have been visited 1263 1264} // end ScheduleLate 1265 1266//------------------------------GlobalCodeMotion------------------------------- 1267void PhaseCFG::global_code_motion() { 1268 ResourceMark rm; 1269 1270#ifndef PRODUCT 1271 if (trace_opto_pipelining()) { 1272 tty->print("\n---- Start GlobalCodeMotion ----\n"); 1273 } 1274#endif 1275 1276 // Initialize the node to block mapping for things on the proj_list 1277 for (uint i = 0; i < _matcher.number_of_projections(); i++) { 1278 unmap_node_from_block(_matcher.get_projection(i)); 1279 } 1280 1281 // Set the basic block for Nodes pinned into blocks 1282 Arena* arena = Thread::current()->resource_area(); 1283 VectorSet visited(arena); 1284 schedule_pinned_nodes(visited); 1285 1286 // Find the earliest Block any instruction can be placed in. Some 1287 // instructions are pinned into Blocks. Unpinned instructions can 1288 // appear in last block in which all their inputs occur. 1289 visited.Clear(); 1290 Node_List stack(arena); 1291 // Pre-grow the list 1292 stack.map((C->unique() >> 1) + 16, NULL); 1293 if (!schedule_early(visited, stack)) { 1294 // Bailout without retry 1295 C->record_method_not_compilable("early schedule failed"); 1296 return; 1297 } 1298 1299 // Build Def-Use edges. 1300 // Compute the latency information (via backwards walk) for all the 1301 // instructions in the graph 1302 _node_latency = new GrowableArray<uint>(); // resource_area allocation 1303 1304 if (C->do_scheduling()) { 1305 compute_latencies_backwards(visited, stack); 1306 } 1307 1308 // Now schedule all codes as LATE as possible. This is the LCA in the 1309 // dominator tree of all USES of a value. Pick the block with the least 1310 // loop nesting depth that is lowest in the dominator tree. 1311 // ( visited.Clear() called in schedule_late()->Node_Backward_Iterator() ) 1312 schedule_late(visited, stack); 1313 if (C->failing()) { 1314 // schedule_late fails only when graph is incorrect. 1315 assert(!VerifyGraphEdges, "verification should have failed"); 1316 return; 1317 } 1318 1319#ifndef PRODUCT 1320 if (trace_opto_pipelining()) { 1321 tty->print("\n---- Detect implicit null checks ----\n"); 1322 } 1323#endif 1324 1325 // Detect implicit-null-check opportunities. Basically, find NULL checks 1326 // with suitable memory ops nearby. Use the memory op to do the NULL check. 1327 // I can generate a memory op if there is not one nearby. 1328 if (C->is_method_compilation()) { 1329 // Don't do it for natives, adapters, or runtime stubs 1330 int allowed_reasons = 0; 1331 // ...and don't do it when there have been too many traps, globally. 1332 for (int reason = (int)Deoptimization::Reason_none+1; 1333 reason < Compile::trapHistLength; reason++) { 1334 assert(reason < BitsPerInt, "recode bit map"); 1335 if (!C->too_many_traps((Deoptimization::DeoptReason) reason)) 1336 allowed_reasons |= nth_bit(reason); 1337 } 1338 // By reversing the loop direction we get a very minor gain on mpegaudio. 1339 // Feel free to revert to a forward loop for clarity. 1340 // for( int i=0; i < (int)matcher._null_check_tests.size(); i+=2 ) { 1341 for (int i = _matcher._null_check_tests.size() - 2; i >= 0; i -= 2) { 1342 Node* proj = _matcher._null_check_tests[i]; 1343 Node* val = _matcher._null_check_tests[i + 1]; 1344 Block* block = get_block_for_node(proj); 1345 implicit_null_check(block, proj, val, allowed_reasons); 1346 // The implicit_null_check will only perform the transformation 1347 // if the null branch is truly uncommon, *and* it leads to an 1348 // uncommon trap. Combined with the too_many_traps guards 1349 // above, this prevents SEGV storms reported in 6366351, 1350 // by recompiling offending methods without this optimization. 1351 } 1352 } 1353 1354#ifndef PRODUCT 1355 if (trace_opto_pipelining()) { 1356 tty->print("\n---- Start Local Scheduling ----\n"); 1357 } 1358#endif 1359 1360 // Schedule locally. Right now a simple topological sort. 1361 // Later, do a real latency aware scheduler. 1362 GrowableArray<int> ready_cnt(C->unique(), C->unique(), -1); 1363 visited.Clear(); 1364 for (uint i = 0; i < number_of_blocks(); i++) { 1365 Block* block = get_block(i); 1366 if (!schedule_local(block, ready_cnt, visited)) { 1367 if (!C->failure_reason_is(C2Compiler::retry_no_subsuming_loads())) { 1368 C->record_method_not_compilable("local schedule failed"); 1369 } 1370 return; 1371 } 1372 } 1373 1374 // If we inserted any instructions between a Call and his CatchNode, 1375 // clone the instructions on all paths below the Catch. 1376 for (uint i = 0; i < number_of_blocks(); i++) { 1377 Block* block = get_block(i); 1378 call_catch_cleanup(block); 1379 } 1380 1381#ifndef PRODUCT 1382 if (trace_opto_pipelining()) { 1383 tty->print("\n---- After GlobalCodeMotion ----\n"); 1384 for (uint i = 0; i < number_of_blocks(); i++) { 1385 Block* block = get_block(i); 1386 block->dump(); 1387 } 1388 } 1389#endif 1390 // Dead. 1391 _node_latency = (GrowableArray<uint> *)0xdeadbeef; 1392} 1393 1394bool PhaseCFG::do_global_code_motion() { 1395 1396 build_dominator_tree(); 1397 if (C->failing()) { 1398 return false; 1399 } 1400 1401 NOT_PRODUCT( C->verify_graph_edges(); ) 1402 1403 estimate_block_frequency(); 1404 1405 global_code_motion(); 1406 1407 if (C->failing()) { 1408 return false; 1409 } 1410 1411 return true; 1412} 1413 1414//------------------------------Estimate_Block_Frequency----------------------- 1415// Estimate block frequencies based on IfNode probabilities. 1416void PhaseCFG::estimate_block_frequency() { 1417 1418 // Force conditional branches leading to uncommon traps to be unlikely, 1419 // not because we get to the uncommon_trap with less relative frequency, 1420 // but because an uncommon_trap typically causes a deopt, so we only get 1421 // there once. 1422 if (C->do_freq_based_layout()) { 1423 Block_List worklist; 1424 Block* root_blk = get_block(0); 1425 for (uint i = 1; i < root_blk->num_preds(); i++) { 1426 Block *pb = get_block_for_node(root_blk->pred(i)); 1427 if (pb->has_uncommon_code()) { 1428 worklist.push(pb); 1429 } 1430 } 1431 while (worklist.size() > 0) { 1432 Block* uct = worklist.pop(); 1433 if (uct == get_root_block()) { 1434 continue; 1435 } 1436 for (uint i = 1; i < uct->num_preds(); i++) { 1437 Block *pb = get_block_for_node(uct->pred(i)); 1438 if (pb->_num_succs == 1) { 1439 worklist.push(pb); 1440 } else if (pb->num_fall_throughs() == 2) { 1441 pb->update_uncommon_branch(uct); 1442 } 1443 } 1444 } 1445 } 1446 1447 // Create the loop tree and calculate loop depth. 1448 _root_loop = create_loop_tree(); 1449 _root_loop->compute_loop_depth(0); 1450 1451 // Compute block frequency of each block, relative to a single loop entry. 1452 _root_loop->compute_freq(); 1453 1454 // Adjust all frequencies to be relative to a single method entry 1455 _root_loop->_freq = 1.0; 1456 _root_loop->scale_freq(); 1457 1458 // Save outmost loop frequency for LRG frequency threshold 1459 _outer_loop_frequency = _root_loop->outer_loop_freq(); 1460 1461 // force paths ending at uncommon traps to be infrequent 1462 if (!C->do_freq_based_layout()) { 1463 Block_List worklist; 1464 Block* root_blk = get_block(0); 1465 for (uint i = 1; i < root_blk->num_preds(); i++) { 1466 Block *pb = get_block_for_node(root_blk->pred(i)); 1467 if (pb->has_uncommon_code()) { 1468 worklist.push(pb); 1469 } 1470 } 1471 while (worklist.size() > 0) { 1472 Block* uct = worklist.pop(); 1473 uct->_freq = PROB_MIN; 1474 for (uint i = 1; i < uct->num_preds(); i++) { 1475 Block *pb = get_block_for_node(uct->pred(i)); 1476 if (pb->_num_succs == 1 && pb->_freq > PROB_MIN) { 1477 worklist.push(pb); 1478 } 1479 } 1480 } 1481 } 1482 1483#ifdef ASSERT 1484 for (uint i = 0; i < number_of_blocks(); i++) { 1485 Block* b = get_block(i); 1486 assert(b->_freq >= MIN_BLOCK_FREQUENCY, "Register Allocator requires meaningful block frequency"); 1487 } 1488#endif 1489 1490#ifndef PRODUCT 1491 if (PrintCFGBlockFreq) { 1492 tty->print_cr("CFG Block Frequencies"); 1493 _root_loop->dump_tree(); 1494 if (Verbose) { 1495 tty->print_cr("PhaseCFG dump"); 1496 dump(); 1497 tty->print_cr("Node dump"); 1498 _root->dump(99999); 1499 } 1500 } 1501#endif 1502} 1503 1504//----------------------------create_loop_tree-------------------------------- 1505// Create a loop tree from the CFG 1506CFGLoop* PhaseCFG::create_loop_tree() { 1507 1508#ifdef ASSERT 1509 assert(get_block(0) == get_root_block(), "first block should be root block"); 1510 for (uint i = 0; i < number_of_blocks(); i++) { 1511 Block* block = get_block(i); 1512 // Check that _loop field are clear...we could clear them if not. 1513 assert(block->_loop == NULL, "clear _loop expected"); 1514 // Sanity check that the RPO numbering is reflected in the _blocks array. 1515 // It doesn't have to be for the loop tree to be built, but if it is not, 1516 // then the blocks have been reordered since dom graph building...which 1517 // may question the RPO numbering 1518 assert(block->_rpo == i, "unexpected reverse post order number"); 1519 } 1520#endif 1521 1522 int idct = 0; 1523 CFGLoop* root_loop = new CFGLoop(idct++); 1524 1525 Block_List worklist; 1526 1527 // Assign blocks to loops 1528 for(uint i = number_of_blocks() - 1; i > 0; i-- ) { // skip Root block 1529 Block* block = get_block(i); 1530 1531 if (block->head()->is_Loop()) { 1532 Block* loop_head = block; 1533 assert(loop_head->num_preds() - 1 == 2, "loop must have 2 predecessors"); 1534 Node* tail_n = loop_head->pred(LoopNode::LoopBackControl); 1535 Block* tail = get_block_for_node(tail_n); 1536 1537 // Defensively filter out Loop nodes for non-single-entry loops. 1538 // For all reasonable loops, the head occurs before the tail in RPO. 1539 if (i <= tail->_rpo) { 1540 1541 // The tail and (recursive) predecessors of the tail 1542 // are made members of a new loop. 1543 1544 assert(worklist.size() == 0, "nonempty worklist"); 1545 CFGLoop* nloop = new CFGLoop(idct++); 1546 assert(loop_head->_loop == NULL, "just checking"); 1547 loop_head->_loop = nloop; 1548 // Add to nloop so push_pred() will skip over inner loops 1549 nloop->add_member(loop_head); 1550 nloop->push_pred(loop_head, LoopNode::LoopBackControl, worklist, this); 1551 1552 while (worklist.size() > 0) { 1553 Block* member = worklist.pop(); 1554 if (member != loop_head) { 1555 for (uint j = 1; j < member->num_preds(); j++) { 1556 nloop->push_pred(member, j, worklist, this); 1557 } 1558 } 1559 } 1560 } 1561 } 1562 } 1563 1564 // Create a member list for each loop consisting 1565 // of both blocks and (immediate child) loops. 1566 for (uint i = 0; i < number_of_blocks(); i++) { 1567 Block* block = get_block(i); 1568 CFGLoop* lp = block->_loop; 1569 if (lp == NULL) { 1570 // Not assigned to a loop. Add it to the method's pseudo loop. 1571 block->_loop = root_loop; 1572 lp = root_loop; 1573 } 1574 if (lp == root_loop || block != lp->head()) { // loop heads are already members 1575 lp->add_member(block); 1576 } 1577 if (lp != root_loop) { 1578 if (lp->parent() == NULL) { 1579 // Not a nested loop. Make it a child of the method's pseudo loop. 1580 root_loop->add_nested_loop(lp); 1581 } 1582 if (block == lp->head()) { 1583 // Add nested loop to member list of parent loop. 1584 lp->parent()->add_member(lp); 1585 } 1586 } 1587 } 1588 1589 return root_loop; 1590} 1591 1592//------------------------------push_pred-------------------------------------- 1593void CFGLoop::push_pred(Block* blk, int i, Block_List& worklist, PhaseCFG* cfg) { 1594 Node* pred_n = blk->pred(i); 1595 Block* pred = cfg->get_block_for_node(pred_n); 1596 CFGLoop *pred_loop = pred->_loop; 1597 if (pred_loop == NULL) { 1598 // Filter out blocks for non-single-entry loops. 1599 // For all reasonable loops, the head occurs before the tail in RPO. 1600 if (pred->_rpo > head()->_rpo) { 1601 pred->_loop = this; 1602 worklist.push(pred); 1603 } 1604 } else if (pred_loop != this) { 1605 // Nested loop. 1606 while (pred_loop->_parent != NULL && pred_loop->_parent != this) { 1607 pred_loop = pred_loop->_parent; 1608 } 1609 // Make pred's loop be a child 1610 if (pred_loop->_parent == NULL) { 1611 add_nested_loop(pred_loop); 1612 // Continue with loop entry predecessor. 1613 Block* pred_head = pred_loop->head(); 1614 assert(pred_head->num_preds() - 1 == 2, "loop must have 2 predecessors"); 1615 assert(pred_head != head(), "loop head in only one loop"); 1616 push_pred(pred_head, LoopNode::EntryControl, worklist, cfg); 1617 } else { 1618 assert(pred_loop->_parent == this && _parent == NULL, "just checking"); 1619 } 1620 } 1621} 1622 1623//------------------------------add_nested_loop-------------------------------- 1624// Make cl a child of the current loop in the loop tree. 1625void CFGLoop::add_nested_loop(CFGLoop* cl) { 1626 assert(_parent == NULL, "no parent yet"); 1627 assert(cl != this, "not my own parent"); 1628 cl->_parent = this; 1629 CFGLoop* ch = _child; 1630 if (ch == NULL) { 1631 _child = cl; 1632 } else { 1633 while (ch->_sibling != NULL) { ch = ch->_sibling; } 1634 ch->_sibling = cl; 1635 } 1636} 1637 1638//------------------------------compute_loop_depth----------------------------- 1639// Store the loop depth in each CFGLoop object. 1640// Recursively walk the children to do the same for them. 1641void CFGLoop::compute_loop_depth(int depth) { 1642 _depth = depth; 1643 CFGLoop* ch = _child; 1644 while (ch != NULL) { 1645 ch->compute_loop_depth(depth + 1); 1646 ch = ch->_sibling; 1647 } 1648} 1649 1650//------------------------------compute_freq----------------------------------- 1651// Compute the frequency of each block and loop, relative to a single entry 1652// into the dominating loop head. 1653void CFGLoop::compute_freq() { 1654 // Bottom up traversal of loop tree (visit inner loops first.) 1655 // Set loop head frequency to 1.0, then transitively 1656 // compute frequency for all successors in the loop, 1657 // as well as for each exit edge. Inner loops are 1658 // treated as single blocks with loop exit targets 1659 // as the successor blocks. 1660 1661 // Nested loops first 1662 CFGLoop* ch = _child; 1663 while (ch != NULL) { 1664 ch->compute_freq(); 1665 ch = ch->_sibling; 1666 } 1667 assert (_members.length() > 0, "no empty loops"); 1668 Block* hd = head(); 1669 hd->_freq = 1.0f; 1670 for (int i = 0; i < _members.length(); i++) { 1671 CFGElement* s = _members.at(i); 1672 float freq = s->_freq; 1673 if (s->is_block()) { 1674 Block* b = s->as_Block(); 1675 for (uint j = 0; j < b->_num_succs; j++) { 1676 Block* sb = b->_succs[j]; 1677 update_succ_freq(sb, freq * b->succ_prob(j)); 1678 } 1679 } else { 1680 CFGLoop* lp = s->as_CFGLoop(); 1681 assert(lp->_parent == this, "immediate child"); 1682 for (int k = 0; k < lp->_exits.length(); k++) { 1683 Block* eb = lp->_exits.at(k).get_target(); 1684 float prob = lp->_exits.at(k).get_prob(); 1685 update_succ_freq(eb, freq * prob); 1686 } 1687 } 1688 } 1689 1690 // For all loops other than the outer, "method" loop, 1691 // sum and normalize the exit probability. The "method" loop 1692 // should keep the initial exit probability of 1, so that 1693 // inner blocks do not get erroneously scaled. 1694 if (_depth != 0) { 1695 // Total the exit probabilities for this loop. 1696 float exits_sum = 0.0f; 1697 for (int i = 0; i < _exits.length(); i++) { 1698 exits_sum += _exits.at(i).get_prob(); 1699 } 1700 1701 // Normalize the exit probabilities. Until now, the 1702 // probabilities estimate the possibility of exit per 1703 // a single loop iteration; afterward, they estimate 1704 // the probability of exit per loop entry. 1705 for (int i = 0; i < _exits.length(); i++) { 1706 Block* et = _exits.at(i).get_target(); 1707 float new_prob = 0.0f; 1708 if (_exits.at(i).get_prob() > 0.0f) { 1709 new_prob = _exits.at(i).get_prob() / exits_sum; 1710 } 1711 BlockProbPair bpp(et, new_prob); 1712 _exits.at_put(i, bpp); 1713 } 1714 1715 // Save the total, but guard against unreasonable probability, 1716 // as the value is used to estimate the loop trip count. 1717 // An infinite trip count would blur relative block 1718 // frequencies. 1719 if (exits_sum > 1.0f) exits_sum = 1.0; 1720 if (exits_sum < PROB_MIN) exits_sum = PROB_MIN; 1721 _exit_prob = exits_sum; 1722 } 1723} 1724 1725//------------------------------succ_prob------------------------------------- 1726// Determine the probability of reaching successor 'i' from the receiver block. 1727float Block::succ_prob(uint i) { 1728 int eidx = end_idx(); 1729 Node *n = get_node(eidx); // Get ending Node 1730 1731 int op = n->Opcode(); 1732 if (n->is_Mach()) { 1733 if (n->is_MachNullCheck()) { 1734 // Can only reach here if called after lcm. The original Op_If is gone, 1735 // so we attempt to infer the probability from one or both of the 1736 // successor blocks. 1737 assert(_num_succs == 2, "expecting 2 successors of a null check"); 1738 // If either successor has only one predecessor, then the 1739 // probability estimate can be derived using the 1740 // relative frequency of the successor and this block. 1741 if (_succs[i]->num_preds() == 2) { 1742 return _succs[i]->_freq / _freq; 1743 } else if (_succs[1-i]->num_preds() == 2) { 1744 return 1 - (_succs[1-i]->_freq / _freq); 1745 } else { 1746 // Estimate using both successor frequencies 1747 float freq = _succs[i]->_freq; 1748 return freq / (freq + _succs[1-i]->_freq); 1749 } 1750 } 1751 op = n->as_Mach()->ideal_Opcode(); 1752 } 1753 1754 1755 // Switch on branch type 1756 switch( op ) { 1757 case Op_CountedLoopEnd: 1758 case Op_If: { 1759 assert (i < 2, "just checking"); 1760 // Conditionals pass on only part of their frequency 1761 float prob = n->as_MachIf()->_prob; 1762 assert(prob >= 0.0 && prob <= 1.0, "out of range probability"); 1763 // If succ[i] is the FALSE branch, invert path info 1764 if( get_node(i + eidx + 1)->Opcode() == Op_IfFalse ) { 1765 return 1.0f - prob; // not taken 1766 } else { 1767 return prob; // taken 1768 } 1769 } 1770 1771 case Op_Jump: 1772 // Divide the frequency between all successors evenly 1773 return 1.0f/_num_succs; 1774 1775 case Op_Catch: { 1776 const CatchProjNode *ci = get_node(i + eidx + 1)->as_CatchProj(); 1777 if (ci->_con == CatchProjNode::fall_through_index) { 1778 // Fall-thru path gets the lion's share. 1779 return 1.0f - PROB_UNLIKELY_MAG(5)*_num_succs; 1780 } else { 1781 // Presume exceptional paths are equally unlikely 1782 return PROB_UNLIKELY_MAG(5); 1783 } 1784 } 1785 1786 case Op_Root: 1787 case Op_Goto: 1788 // Pass frequency straight thru to target 1789 return 1.0f; 1790 1791 case Op_NeverBranch: 1792 return 0.0f; 1793 1794 case Op_TailCall: 1795 case Op_TailJump: 1796 case Op_Return: 1797 case Op_Halt: 1798 case Op_Rethrow: 1799 // Do not push out freq to root block 1800 return 0.0f; 1801 1802 default: 1803 ShouldNotReachHere(); 1804 } 1805 1806 return 0.0f; 1807} 1808 1809//------------------------------num_fall_throughs----------------------------- 1810// Return the number of fall-through candidates for a block 1811int Block::num_fall_throughs() { 1812 int eidx = end_idx(); 1813 Node *n = get_node(eidx); // Get ending Node 1814 1815 int op = n->Opcode(); 1816 if (n->is_Mach()) { 1817 if (n->is_MachNullCheck()) { 1818 // In theory, either side can fall-thru, for simplicity sake, 1819 // let's say only the false branch can now. 1820 return 1; 1821 } 1822 op = n->as_Mach()->ideal_Opcode(); 1823 } 1824 1825 // Switch on branch type 1826 switch( op ) { 1827 case Op_CountedLoopEnd: 1828 case Op_If: 1829 return 2; 1830 1831 case Op_Root: 1832 case Op_Goto: 1833 return 1; 1834 1835 case Op_Catch: { 1836 for (uint i = 0; i < _num_succs; i++) { 1837 const CatchProjNode *ci = get_node(i + eidx + 1)->as_CatchProj(); 1838 if (ci->_con == CatchProjNode::fall_through_index) { 1839 return 1; 1840 } 1841 } 1842 return 0; 1843 } 1844 1845 case Op_Jump: 1846 case Op_NeverBranch: 1847 case Op_TailCall: 1848 case Op_TailJump: 1849 case Op_Return: 1850 case Op_Halt: 1851 case Op_Rethrow: 1852 return 0; 1853 1854 default: 1855 ShouldNotReachHere(); 1856 } 1857 1858 return 0; 1859} 1860 1861//------------------------------succ_fall_through----------------------------- 1862// Return true if a specific successor could be fall-through target. 1863bool Block::succ_fall_through(uint i) { 1864 int eidx = end_idx(); 1865 Node *n = get_node(eidx); // Get ending Node 1866 1867 int op = n->Opcode(); 1868 if (n->is_Mach()) { 1869 if (n->is_MachNullCheck()) { 1870 // In theory, either side can fall-thru, for simplicity sake, 1871 // let's say only the false branch can now. 1872 return get_node(i + eidx + 1)->Opcode() == Op_IfFalse; 1873 } 1874 op = n->as_Mach()->ideal_Opcode(); 1875 } 1876 1877 // Switch on branch type 1878 switch( op ) { 1879 case Op_CountedLoopEnd: 1880 case Op_If: 1881 case Op_Root: 1882 case Op_Goto: 1883 return true; 1884 1885 case Op_Catch: { 1886 const CatchProjNode *ci = get_node(i + eidx + 1)->as_CatchProj(); 1887 return ci->_con == CatchProjNode::fall_through_index; 1888 } 1889 1890 case Op_Jump: 1891 case Op_NeverBranch: 1892 case Op_TailCall: 1893 case Op_TailJump: 1894 case Op_Return: 1895 case Op_Halt: 1896 case Op_Rethrow: 1897 return false; 1898 1899 default: 1900 ShouldNotReachHere(); 1901 } 1902 1903 return false; 1904} 1905 1906//------------------------------update_uncommon_branch------------------------ 1907// Update the probability of a two-branch to be uncommon 1908void Block::update_uncommon_branch(Block* ub) { 1909 int eidx = end_idx(); 1910 Node *n = get_node(eidx); // Get ending Node 1911 1912 int op = n->as_Mach()->ideal_Opcode(); 1913 1914 assert(op == Op_CountedLoopEnd || op == Op_If, "must be a If"); 1915 assert(num_fall_throughs() == 2, "must be a two way branch block"); 1916 1917 // Which successor is ub? 1918 uint s; 1919 for (s = 0; s <_num_succs; s++) { 1920 if (_succs[s] == ub) break; 1921 } 1922 assert(s < 2, "uncommon successor must be found"); 1923 1924 // If ub is the true path, make the proability small, else 1925 // ub is the false path, and make the probability large 1926 bool invert = (get_node(s + eidx + 1)->Opcode() == Op_IfFalse); 1927 1928 // Get existing probability 1929 float p = n->as_MachIf()->_prob; 1930 1931 if (invert) p = 1.0 - p; 1932 if (p > PROB_MIN) { 1933 p = PROB_MIN; 1934 } 1935 if (invert) p = 1.0 - p; 1936 1937 n->as_MachIf()->_prob = p; 1938} 1939 1940//------------------------------update_succ_freq------------------------------- 1941// Update the appropriate frequency associated with block 'b', a successor of 1942// a block in this loop. 1943void CFGLoop::update_succ_freq(Block* b, float freq) { 1944 if (b->_loop == this) { 1945 if (b == head()) { 1946 // back branch within the loop 1947 // Do nothing now, the loop carried frequency will be 1948 // adjust later in scale_freq(). 1949 } else { 1950 // simple branch within the loop 1951 b->_freq += freq; 1952 } 1953 } else if (!in_loop_nest(b)) { 1954 // branch is exit from this loop 1955 BlockProbPair bpp(b, freq); 1956 _exits.append(bpp); 1957 } else { 1958 // branch into nested loop 1959 CFGLoop* ch = b->_loop; 1960 ch->_freq += freq; 1961 } 1962} 1963 1964//------------------------------in_loop_nest----------------------------------- 1965// Determine if block b is in the receiver's loop nest. 1966bool CFGLoop::in_loop_nest(Block* b) { 1967 int depth = _depth; 1968 CFGLoop* b_loop = b->_loop; 1969 int b_depth = b_loop->_depth; 1970 if (depth == b_depth) { 1971 return true; 1972 } 1973 while (b_depth > depth) { 1974 b_loop = b_loop->_parent; 1975 b_depth = b_loop->_depth; 1976 } 1977 return b_loop == this; 1978} 1979 1980//------------------------------scale_freq------------------------------------- 1981// Scale frequency of loops and blocks by trip counts from outer loops 1982// Do a top down traversal of loop tree (visit outer loops first.) 1983void CFGLoop::scale_freq() { 1984 float loop_freq = _freq * trip_count(); 1985 _freq = loop_freq; 1986 for (int i = 0; i < _members.length(); i++) { 1987 CFGElement* s = _members.at(i); 1988 float block_freq = s->_freq * loop_freq; 1989 if (g_isnan(block_freq) || block_freq < MIN_BLOCK_FREQUENCY) 1990 block_freq = MIN_BLOCK_FREQUENCY; 1991 s->_freq = block_freq; 1992 } 1993 CFGLoop* ch = _child; 1994 while (ch != NULL) { 1995 ch->scale_freq(); 1996 ch = ch->_sibling; 1997 } 1998} 1999 2000// Frequency of outer loop 2001float CFGLoop::outer_loop_freq() const { 2002 if (_child != NULL) { 2003 return _child->_freq; 2004 } 2005 return _freq; 2006} 2007 2008#ifndef PRODUCT 2009//------------------------------dump_tree-------------------------------------- 2010void CFGLoop::dump_tree() const { 2011 dump(); 2012 if (_child != NULL) _child->dump_tree(); 2013 if (_sibling != NULL) _sibling->dump_tree(); 2014} 2015 2016//------------------------------dump------------------------------------------- 2017void CFGLoop::dump() const { 2018 for (int i = 0; i < _depth; i++) tty->print(" "); 2019 tty->print("%s: %d trip_count: %6.0f freq: %6.0f\n", 2020 _depth == 0 ? "Method" : "Loop", _id, trip_count(), _freq); 2021 for (int i = 0; i < _depth; i++) tty->print(" "); 2022 tty->print(" members:", _id); 2023 int k = 0; 2024 for (int i = 0; i < _members.length(); i++) { 2025 if (k++ >= 6) { 2026 tty->print("\n "); 2027 for (int j = 0; j < _depth+1; j++) tty->print(" "); 2028 k = 0; 2029 } 2030 CFGElement *s = _members.at(i); 2031 if (s->is_block()) { 2032 Block *b = s->as_Block(); 2033 tty->print(" B%d(%6.3f)", b->_pre_order, b->_freq); 2034 } else { 2035 CFGLoop* lp = s->as_CFGLoop(); 2036 tty->print(" L%d(%6.3f)", lp->_id, lp->_freq); 2037 } 2038 } 2039 tty->print("\n"); 2040 for (int i = 0; i < _depth; i++) tty->print(" "); 2041 tty->print(" exits: "); 2042 k = 0; 2043 for (int i = 0; i < _exits.length(); i++) { 2044 if (k++ >= 7) { 2045 tty->print("\n "); 2046 for (int j = 0; j < _depth+1; j++) tty->print(" "); 2047 k = 0; 2048 } 2049 Block *blk = _exits.at(i).get_target(); 2050 float prob = _exits.at(i).get_prob(); 2051 tty->print(" ->%d@%d%%", blk->_pre_order, (int)(prob*100)); 2052 } 2053 tty->print("\n"); 2054} 2055#endif 2056