block.hpp revision 1472:c18cbe5936b8
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// Optimization - Graph Style 26 27class Block; 28class CFGLoop; 29class MachCallNode; 30class Matcher; 31class RootNode; 32class VectorSet; 33struct Tarjan; 34 35//------------------------------Block_Array------------------------------------ 36// Map dense integer indices to Blocks. Uses classic doubling-array trick. 37// Abstractly provides an infinite array of Block*'s, initialized to NULL. 38// Note that the constructor just zeros things, and since I use Arena 39// allocation I do not need a destructor to reclaim storage. 40class Block_Array : public ResourceObj { 41 uint _size; // allocated size, as opposed to formal limit 42 debug_only(uint _limit;) // limit to formal domain 43protected: 44 Block **_blocks; 45 void grow( uint i ); // Grow array node to fit 46 47public: 48 Arena *_arena; // Arena to allocate in 49 50 Block_Array(Arena *a) : _arena(a), _size(OptoBlockListSize) { 51 debug_only(_limit=0); 52 _blocks = NEW_ARENA_ARRAY( a, Block *, OptoBlockListSize ); 53 for( int i = 0; i < OptoBlockListSize; i++ ) { 54 _blocks[i] = NULL; 55 } 56 } 57 Block *lookup( uint i ) const // Lookup, or NULL for not mapped 58 { return (i<Max()) ? _blocks[i] : (Block*)NULL; } 59 Block *operator[] ( uint i ) const // Lookup, or assert for not mapped 60 { assert( i < Max(), "oob" ); return _blocks[i]; } 61 // Extend the mapping: index i maps to Block *n. 62 void map( uint i, Block *n ) { if( i>=Max() ) grow(i); _blocks[i] = n; } 63 uint Max() const { debug_only(return _limit); return _size; } 64}; 65 66 67class Block_List : public Block_Array { 68public: 69 uint _cnt; 70 Block_List() : Block_Array(Thread::current()->resource_area()), _cnt(0) {} 71 void push( Block *b ) { map(_cnt++,b); } 72 Block *pop() { return _blocks[--_cnt]; } 73 Block *rpop() { Block *b = _blocks[0]; _blocks[0]=_blocks[--_cnt]; return b;} 74 void remove( uint i ); 75 void insert( uint i, Block *n ); 76 uint size() const { return _cnt; } 77 void reset() { _cnt = 0; } 78 void print(); 79}; 80 81 82class CFGElement : public ResourceObj { 83 public: 84 float _freq; // Execution frequency (estimate) 85 86 CFGElement() : _freq(0.0f) {} 87 virtual bool is_block() { return false; } 88 virtual bool is_loop() { return false; } 89 Block* as_Block() { assert(is_block(), "must be block"); return (Block*)this; } 90 CFGLoop* as_CFGLoop() { assert(is_loop(), "must be loop"); return (CFGLoop*)this; } 91}; 92 93//------------------------------Block------------------------------------------ 94// This class defines a Basic Block. 95// Basic blocks are used during the output routines, and are not used during 96// any optimization pass. They are created late in the game. 97class Block : public CFGElement { 98 public: 99 // Nodes in this block, in order 100 Node_List _nodes; 101 102 // Basic blocks have a Node which defines Control for all Nodes pinned in 103 // this block. This Node is a RegionNode. Exception-causing Nodes 104 // (division, subroutines) and Phi functions are always pinned. Later, 105 // every Node will get pinned to some block. 106 Node *head() const { return _nodes[0]; } 107 108 // CAUTION: num_preds() is ONE based, so that predecessor numbers match 109 // input edges to Regions and Phis. 110 uint num_preds() const { return head()->req(); } 111 Node *pred(uint i) const { return head()->in(i); } 112 113 // Array of successor blocks, same size as projs array 114 Block_Array _succs; 115 116 // Basic blocks have some number of Nodes which split control to all 117 // following blocks. These Nodes are always Projections. The field in 118 // the Projection and the block-ending Node determine which Block follows. 119 uint _num_succs; 120 121 // Basic blocks also carry all sorts of good old fashioned DFS information 122 // used to find loops, loop nesting depth, dominators, etc. 123 uint _pre_order; // Pre-order DFS number 124 125 // Dominator tree 126 uint _dom_depth; // Depth in dominator tree for fast LCA 127 Block* _idom; // Immediate dominator block 128 129 CFGLoop *_loop; // Loop to which this block belongs 130 uint _rpo; // Number in reverse post order walk 131 132 virtual bool is_block() { return true; } 133 float succ_prob(uint i); // return probability of i'th successor 134 int num_fall_throughs(); // How many fall-through candidate this block has 135 void update_uncommon_branch(Block* un); // Lower branch prob to uncommon code 136 bool succ_fall_through(uint i); // Is successor "i" is a fall-through candidate 137 Block* lone_fall_through(); // Return lone fall-through Block or null 138 139 Block* dom_lca(Block* that); // Compute LCA in dominator tree. 140#ifdef ASSERT 141 bool dominates(Block* that) { 142 int dom_diff = this->_dom_depth - that->_dom_depth; 143 if (dom_diff > 0) return false; 144 for (; dom_diff < 0; dom_diff++) that = that->_idom; 145 return this == that; 146 } 147#endif 148 149 // Report the alignment required by this block. Must be a power of 2. 150 // The previous block will insert nops to get this alignment. 151 uint code_alignment(); 152 uint compute_loop_alignment(); 153 154 // BLOCK_FREQUENCY is a sentinel to mark uses of constant block frequencies. 155 // It is currently also used to scale such frequencies relative to 156 // FreqCountInvocations relative to the old value of 1500. 157#define BLOCK_FREQUENCY(f) ((f * (float) 1500) / FreqCountInvocations) 158 159 // Register Pressure (estimate) for Splitting heuristic 160 uint _reg_pressure; 161 uint _ihrp_index; 162 uint _freg_pressure; 163 uint _fhrp_index; 164 165 // Mark and visited bits for an LCA calculation in insert_anti_dependences. 166 // Since they hold unique node indexes, they do not need reinitialization. 167 node_idx_t _raise_LCA_mark; 168 void set_raise_LCA_mark(node_idx_t x) { _raise_LCA_mark = x; } 169 node_idx_t raise_LCA_mark() const { return _raise_LCA_mark; } 170 node_idx_t _raise_LCA_visited; 171 void set_raise_LCA_visited(node_idx_t x) { _raise_LCA_visited = x; } 172 node_idx_t raise_LCA_visited() const { return _raise_LCA_visited; } 173 174 // Estimated size in bytes of first instructions in a loop. 175 uint _first_inst_size; 176 uint first_inst_size() const { return _first_inst_size; } 177 void set_first_inst_size(uint s) { _first_inst_size = s; } 178 179 // Compute the size of first instructions in this block. 180 uint compute_first_inst_size(uint& sum_size, uint inst_cnt, PhaseRegAlloc* ra); 181 182 // Compute alignment padding if the block needs it. 183 // Align a loop if loop's padding is less or equal to padding limit 184 // or the size of first instructions in the loop > padding. 185 uint alignment_padding(int current_offset) { 186 int block_alignment = code_alignment(); 187 int max_pad = block_alignment-relocInfo::addr_unit(); 188 if( max_pad > 0 ) { 189 assert(is_power_of_2(max_pad+relocInfo::addr_unit()), ""); 190 int current_alignment = current_offset & max_pad; 191 if( current_alignment != 0 ) { 192 uint padding = (block_alignment-current_alignment) & max_pad; 193 if( has_loop_alignment() && 194 padding > (uint)MaxLoopPad && 195 first_inst_size() <= padding ) { 196 return 0; 197 } 198 return padding; 199 } 200 } 201 return 0; 202 } 203 204 // Connector blocks. Connector blocks are basic blocks devoid of 205 // instructions, but may have relevant non-instruction Nodes, such as 206 // Phis or MergeMems. Such blocks are discovered and marked during the 207 // RemoveEmpty phase, and elided during Output. 208 bool _connector; 209 void set_connector() { _connector = true; } 210 bool is_connector() const { return _connector; }; 211 212 // Loop_alignment will be set for blocks which are at the top of loops. 213 // The block layout pass may rotate loops such that the loop head may not 214 // be the sequentially first block of the loop encountered in the linear 215 // list of blocks. If the layout pass is not run, loop alignment is set 216 // for each block which is the head of a loop. 217 uint _loop_alignment; 218 void set_loop_alignment(Block *loop_top) { 219 uint new_alignment = loop_top->compute_loop_alignment(); 220 if (new_alignment > _loop_alignment) { 221 _loop_alignment = new_alignment; 222 } 223 } 224 uint loop_alignment() const { return _loop_alignment; } 225 bool has_loop_alignment() const { return loop_alignment() > 0; } 226 227 // Create a new Block with given head Node. 228 // Creates the (empty) predecessor arrays. 229 Block( Arena *a, Node *headnode ) 230 : CFGElement(), 231 _nodes(a), 232 _succs(a), 233 _num_succs(0), 234 _pre_order(0), 235 _idom(0), 236 _loop(NULL), 237 _reg_pressure(0), 238 _ihrp_index(1), 239 _freg_pressure(0), 240 _fhrp_index(1), 241 _raise_LCA_mark(0), 242 _raise_LCA_visited(0), 243 _first_inst_size(999999), 244 _connector(false), 245 _loop_alignment(0) { 246 _nodes.push(headnode); 247 } 248 249 // Index of 'end' Node 250 uint end_idx() const { 251 // %%%%% add a proj after every goto 252 // so (last->is_block_proj() != last) always, then simplify this code 253 // This will not give correct end_idx for block 0 when it only contains root. 254 int last_idx = _nodes.size() - 1; 255 Node *last = _nodes[last_idx]; 256 assert(last->is_block_proj() == last || last->is_block_proj() == _nodes[last_idx - _num_succs], ""); 257 return (last->is_block_proj() == last) ? last_idx : (last_idx - _num_succs); 258 } 259 260 // Basic blocks have a Node which ends them. This Node determines which 261 // basic block follows this one in the program flow. This Node is either an 262 // IfNode, a GotoNode, a JmpNode, or a ReturnNode. 263 Node *end() const { return _nodes[end_idx()]; } 264 265 // Add an instruction to an existing block. It must go after the head 266 // instruction and before the end instruction. 267 void add_inst( Node *n ) { _nodes.insert(end_idx(),n); } 268 // Find node in block 269 uint find_node( const Node *n ) const; 270 // Find and remove n from block list 271 void find_remove( const Node *n ); 272 273 // Schedule a call next in the block 274 uint sched_call(Matcher &matcher, Block_Array &bbs, uint node_cnt, Node_List &worklist, int *ready_cnt, MachCallNode *mcall, VectorSet &next_call); 275 276 // Perform basic-block local scheduling 277 Node *select(PhaseCFG *cfg, Node_List &worklist, int *ready_cnt, VectorSet &next_call, uint sched_slot); 278 void set_next_call( Node *n, VectorSet &next_call, Block_Array &bbs ); 279 void needed_for_next_call(Node *this_call, VectorSet &next_call, Block_Array &bbs); 280 bool schedule_local(PhaseCFG *cfg, Matcher &m, int *ready_cnt, VectorSet &next_call); 281 // Cleanup if any code lands between a Call and his Catch 282 void call_catch_cleanup(Block_Array &bbs); 283 // Detect implicit-null-check opportunities. Basically, find NULL checks 284 // with suitable memory ops nearby. Use the memory op to do the NULL check. 285 // I can generate a memory op if there is not one nearby. 286 void implicit_null_check(PhaseCFG *cfg, Node *proj, Node *val, int allowed_reasons); 287 288 // Return the empty status of a block 289 enum { not_empty, empty_with_goto, completely_empty }; 290 int is_Empty() const; 291 292 // Forward through connectors 293 Block* non_connector() { 294 Block* s = this; 295 while (s->is_connector()) { 296 s = s->_succs[0]; 297 } 298 return s; 299 } 300 301 // Return true if b is a successor of this block 302 bool has_successor(Block* b) const { 303 for (uint i = 0; i < _num_succs; i++ ) { 304 if (non_connector_successor(i) == b) { 305 return true; 306 } 307 } 308 return false; 309 } 310 311 // Successor block, after forwarding through connectors 312 Block* non_connector_successor(int i) const { 313 return _succs[i]->non_connector(); 314 } 315 316 // Examine block's code shape to predict if it is not commonly executed. 317 bool has_uncommon_code() const; 318 319 // Use frequency calculations and code shape to predict if the block 320 // is uncommon. 321 bool is_uncommon( Block_Array &bbs ) const; 322 323#ifndef PRODUCT 324 // Debugging print of basic block 325 void dump_bidx(const Block* orig) const; 326 void dump_pred(const Block_Array *bbs, Block* orig) const; 327 void dump_head( const Block_Array *bbs ) const; 328 void dump( ) const; 329 void dump( const Block_Array *bbs ) const; 330#endif 331}; 332 333 334//------------------------------PhaseCFG--------------------------------------- 335// Build an array of Basic Block pointers, one per Node. 336class PhaseCFG : public Phase { 337 private: 338 // Build a proper looking cfg. Return count of basic blocks 339 uint build_cfg(); 340 341 // Perform DFS search. 342 // Setup 'vertex' as DFS to vertex mapping. 343 // Setup 'semi' as vertex to DFS mapping. 344 // Set 'parent' to DFS parent. 345 uint DFS( Tarjan *tarjan ); 346 347 // Helper function to insert a node into a block 348 void schedule_node_into_block( Node *n, Block *b ); 349 350 void replace_block_proj_ctrl( Node *n ); 351 352 // Set the basic block for pinned Nodes 353 void schedule_pinned_nodes( VectorSet &visited ); 354 355 // I'll need a few machine-specific GotoNodes. Clone from this one. 356 MachNode *_goto; 357 358 Block* insert_anti_dependences(Block* LCA, Node* load, bool verify = false); 359 void verify_anti_dependences(Block* LCA, Node* load) { 360 assert(LCA == _bbs[load->_idx], "should already be scheduled"); 361 insert_anti_dependences(LCA, load, true); 362 } 363 364 public: 365 PhaseCFG( Arena *a, RootNode *r, Matcher &m ); 366 367 uint _num_blocks; // Count of basic blocks 368 Block_List _blocks; // List of basic blocks 369 RootNode *_root; // Root of whole program 370 Block_Array _bbs; // Map Nodes to owning Basic Block 371 Block *_broot; // Basic block of root 372 uint _rpo_ctr; 373 CFGLoop* _root_loop; 374 float _outer_loop_freq; // Outmost loop frequency 375 376 // Per node latency estimation, valid only during GCM 377 GrowableArray<uint> _node_latency; 378 379#ifndef PRODUCT 380 bool _trace_opto_pipelining; // tracing flag 381#endif 382 383#ifdef ASSERT 384 Unique_Node_List _raw_oops; 385#endif 386 387 // Build dominators 388 void Dominators(); 389 390 // Estimate block frequencies based on IfNode probabilities 391 void Estimate_Block_Frequency(); 392 393 // Global Code Motion. See Click's PLDI95 paper. Place Nodes in specific 394 // basic blocks; i.e. _bbs now maps _idx for all Nodes to some Block. 395 void GlobalCodeMotion( Matcher &m, uint unique, Node_List &proj_list ); 396 397 // Compute the (backwards) latency of a node from the uses 398 void latency_from_uses(Node *n); 399 400 // Compute the (backwards) latency of a node from a single use 401 int latency_from_use(Node *n, const Node *def, Node *use); 402 403 // Compute the (backwards) latency of a node from the uses of this instruction 404 void partial_latency_of_defs(Node *n); 405 406 // Schedule Nodes early in their basic blocks. 407 bool schedule_early(VectorSet &visited, Node_List &roots); 408 409 // For each node, find the latest block it can be scheduled into 410 // and then select the cheapest block between the latest and earliest 411 // block to place the node. 412 void schedule_late(VectorSet &visited, Node_List &stack); 413 414 // Pick a block between early and late that is a cheaper alternative 415 // to late. Helper for schedule_late. 416 Block* hoist_to_cheaper_block(Block* LCA, Block* early, Node* self); 417 418 // Compute the instruction global latency with a backwards walk 419 void ComputeLatenciesBackwards(VectorSet &visited, Node_List &stack); 420 421 // Set loop alignment 422 void set_loop_alignment(); 423 424 // Remove empty basic blocks 425 void remove_empty(); 426 void fixup_flow(); 427 bool move_to_next(Block* bx, uint b_index); 428 void move_to_end(Block* bx, uint b_index); 429 void insert_goto_at(uint block_no, uint succ_no); 430 431 // Check for NeverBranch at block end. This needs to become a GOTO to the 432 // true target. NeverBranch are treated as a conditional branch that always 433 // goes the same direction for most of the optimizer and are used to give a 434 // fake exit path to infinite loops. At this late stage they need to turn 435 // into Goto's so that when you enter the infinite loop you indeed hang. 436 void convert_NeverBranch_to_Goto(Block *b); 437 438 CFGLoop* create_loop_tree(); 439 440 // Insert a node into a block, and update the _bbs 441 void insert( Block *b, uint idx, Node *n ) { 442 b->_nodes.insert( idx, n ); 443 _bbs.map( n->_idx, b ); 444 } 445 446#ifndef PRODUCT 447 bool trace_opto_pipelining() const { return _trace_opto_pipelining; } 448 449 // Debugging print of CFG 450 void dump( ) const; // CFG only 451 void _dump_cfg( const Node *end, VectorSet &visited ) const; 452 void verify() const; 453 void dump_headers(); 454#else 455 bool trace_opto_pipelining() const { return false; } 456#endif 457}; 458 459 460//------------------------------UnionFind-------------------------------------- 461// Map Block indices to a block-index for a cfg-cover. 462// Array lookup in the optimized case. 463class UnionFind : public ResourceObj { 464 uint _cnt, _max; 465 uint* _indices; 466 ReallocMark _nesting; // assertion check for reallocations 467public: 468 UnionFind( uint max ); 469 void reset( uint max ); // Reset to identity map for [0..max] 470 471 uint lookup( uint nidx ) const { 472 return _indices[nidx]; 473 } 474 uint operator[] (uint nidx) const { return lookup(nidx); } 475 476 void map( uint from_idx, uint to_idx ) { 477 assert( from_idx < _cnt, "oob" ); 478 _indices[from_idx] = to_idx; 479 } 480 void extend( uint from_idx, uint to_idx ); 481 482 uint Size() const { return _cnt; } 483 484 uint Find( uint idx ) { 485 assert( idx < 65536, "Must fit into uint"); 486 uint uf_idx = lookup(idx); 487 return (uf_idx == idx) ? uf_idx : Find_compress(idx); 488 } 489 uint Find_compress( uint idx ); 490 uint Find_const( uint idx ) const; 491 void Union( uint idx1, uint idx2 ); 492 493}; 494 495//----------------------------BlockProbPair--------------------------- 496// Ordered pair of Node*. 497class BlockProbPair VALUE_OBJ_CLASS_SPEC { 498protected: 499 Block* _target; // block target 500 float _prob; // probability of edge to block 501public: 502 BlockProbPair() : _target(NULL), _prob(0.0) {} 503 BlockProbPair(Block* b, float p) : _target(b), _prob(p) {} 504 505 Block* get_target() const { return _target; } 506 float get_prob() const { return _prob; } 507}; 508 509//------------------------------CFGLoop------------------------------------------- 510class CFGLoop : public CFGElement { 511 int _id; 512 int _depth; 513 CFGLoop *_parent; // root of loop tree is the method level "pseudo" loop, it's parent is null 514 CFGLoop *_sibling; // null terminated list 515 CFGLoop *_child; // first child, use child's sibling to visit all immediately nested loops 516 GrowableArray<CFGElement*> _members; // list of members of loop 517 GrowableArray<BlockProbPair> _exits; // list of successor blocks and their probabilities 518 float _exit_prob; // probability any loop exit is taken on a single loop iteration 519 void update_succ_freq(Block* b, float freq); 520 521 public: 522 CFGLoop(int id) : 523 CFGElement(), 524 _id(id), 525 _depth(0), 526 _parent(NULL), 527 _sibling(NULL), 528 _child(NULL), 529 _exit_prob(1.0f) {} 530 CFGLoop* parent() { return _parent; } 531 void push_pred(Block* blk, int i, Block_List& worklist, Block_Array& node_to_blk); 532 void add_member(CFGElement *s) { _members.push(s); } 533 void add_nested_loop(CFGLoop* cl); 534 Block* head() { 535 assert(_members.at(0)->is_block(), "head must be a block"); 536 Block* hd = _members.at(0)->as_Block(); 537 assert(hd->_loop == this, "just checking"); 538 assert(hd->head()->is_Loop(), "must begin with loop head node"); 539 return hd; 540 } 541 Block* backedge_block(); // Return the block on the backedge of the loop (else NULL) 542 void compute_loop_depth(int depth); 543 void compute_freq(); // compute frequency with loop assuming head freq 1.0f 544 void scale_freq(); // scale frequency by loop trip count (including outer loops) 545 float outer_loop_freq() const; // frequency of outer loop 546 bool in_loop_nest(Block* b); 547 float trip_count() const { return 1.0f / _exit_prob; } 548 virtual bool is_loop() { return true; } 549 int id() { return _id; } 550 551#ifndef PRODUCT 552 void dump( ) const; 553 void dump_tree() const; 554#endif 555}; 556 557 558//----------------------------------CFGEdge------------------------------------ 559// A edge between two basic blocks that will be embodied by a branch or a 560// fall-through. 561class CFGEdge : public ResourceObj { 562 private: 563 Block * _from; // Source basic block 564 Block * _to; // Destination basic block 565 float _freq; // Execution frequency (estimate) 566 int _state; 567 bool _infrequent; 568 int _from_pct; 569 int _to_pct; 570 571 // Private accessors 572 int from_pct() const { return _from_pct; } 573 int to_pct() const { return _to_pct; } 574 int from_infrequent() const { return from_pct() < BlockLayoutMinDiamondPercentage; } 575 int to_infrequent() const { return to_pct() < BlockLayoutMinDiamondPercentage; } 576 577 public: 578 enum { 579 open, // initial edge state; unprocessed 580 connected, // edge used to connect two traces together 581 interior // edge is interior to trace (could be backedge) 582 }; 583 584 CFGEdge(Block *from, Block *to, float freq, int from_pct, int to_pct) : 585 _from(from), _to(to), _freq(freq), 586 _from_pct(from_pct), _to_pct(to_pct), _state(open) { 587 _infrequent = from_infrequent() || to_infrequent(); 588 } 589 590 float freq() const { return _freq; } 591 Block* from() const { return _from; } 592 Block* to () const { return _to; } 593 int infrequent() const { return _infrequent; } 594 int state() const { return _state; } 595 596 void set_state(int state) { _state = state; } 597 598#ifndef PRODUCT 599 void dump( ) const; 600#endif 601}; 602 603 604//-----------------------------------Trace------------------------------------- 605// An ordered list of basic blocks. 606class Trace : public ResourceObj { 607 private: 608 uint _id; // Unique Trace id (derived from initial block) 609 Block ** _next_list; // Array mapping index to next block 610 Block ** _prev_list; // Array mapping index to previous block 611 Block * _first; // First block in the trace 612 Block * _last; // Last block in the trace 613 614 // Return the block that follows "b" in the trace. 615 Block * next(Block *b) const { return _next_list[b->_pre_order]; } 616 void set_next(Block *b, Block *n) const { _next_list[b->_pre_order] = n; } 617 618 // Return the block that precedes "b" in the trace. 619 Block * prev(Block *b) const { return _prev_list[b->_pre_order]; } 620 void set_prev(Block *b, Block *p) const { _prev_list[b->_pre_order] = p; } 621 622 // We've discovered a loop in this trace. Reset last to be "b", and first as 623 // the block following "b 624 void break_loop_after(Block *b) { 625 _last = b; 626 _first = next(b); 627 set_prev(_first, NULL); 628 set_next(_last, NULL); 629 } 630 631 public: 632 633 Trace(Block *b, Block **next_list, Block **prev_list) : 634 _first(b), 635 _last(b), 636 _next_list(next_list), 637 _prev_list(prev_list), 638 _id(b->_pre_order) { 639 set_next(b, NULL); 640 set_prev(b, NULL); 641 }; 642 643 // Return the id number 644 uint id() const { return _id; } 645 void set_id(uint id) { _id = id; } 646 647 // Return the first block in the trace 648 Block * first_block() const { return _first; } 649 650 // Return the last block in the trace 651 Block * last_block() const { return _last; } 652 653 // Insert a trace in the middle of this one after b 654 void insert_after(Block *b, Trace *tr) { 655 set_next(tr->last_block(), next(b)); 656 if (next(b) != NULL) { 657 set_prev(next(b), tr->last_block()); 658 } 659 660 set_next(b, tr->first_block()); 661 set_prev(tr->first_block(), b); 662 663 if (b == _last) { 664 _last = tr->last_block(); 665 } 666 } 667 668 void insert_before(Block *b, Trace *tr) { 669 Block *p = prev(b); 670 assert(p != NULL, "use append instead"); 671 insert_after(p, tr); 672 } 673 674 // Append another trace to this one. 675 void append(Trace *tr) { 676 insert_after(_last, tr); 677 } 678 679 // Append a block at the end of this trace 680 void append(Block *b) { 681 set_next(_last, b); 682 set_prev(b, _last); 683 _last = b; 684 } 685 686 // Adjust the the blocks in this trace 687 void fixup_blocks(PhaseCFG &cfg); 688 bool backedge(CFGEdge *e); 689 690#ifndef PRODUCT 691 void dump( ) const; 692#endif 693}; 694 695//------------------------------PhaseBlockLayout------------------------------- 696// Rearrange blocks into some canonical order, based on edges and their frequencies 697class PhaseBlockLayout : public Phase { 698 PhaseCFG &_cfg; // Control flow graph 699 700 GrowableArray<CFGEdge *> *edges; 701 Trace **traces; 702 Block **next; 703 Block **prev; 704 UnionFind *uf; 705 706 // Given a block, find its encompassing Trace 707 Trace * trace(Block *b) { 708 return traces[uf->Find_compress(b->_pre_order)]; 709 } 710 public: 711 PhaseBlockLayout(PhaseCFG &cfg); 712 713 void find_edges(); 714 void grow_traces(); 715 void merge_traces(bool loose_connections); 716 void reorder_traces(int count); 717 void union_traces(Trace* from, Trace* to); 718}; 719