1 /*
2 * Copyright 1997-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // Optimization - Graph Style
26
27 class Block;
28 class CFGLoop;
29 class MachCallNode;
30 class Matcher;
31 class RootNode;
32 class VectorSet;
33 struct 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.
40 class Block_Array : public ResourceObj {
41 uint _size; // allocated size, as opposed to formal limit
42 debug_only(uint _limit;) // limit to formal domain
43 protected:
44 Block **_blocks;
45 void grow( uint i ); // Grow array node to fit
46
47 public:
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
67 class Block_List : public Block_Array {
68 public:
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
82 class 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.
97 class 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.
336 class 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 // Set the basic block for pinned Nodes
351 void schedule_pinned_nodes( VectorSet &visited );
352
353 // I'll need a few machine-specific GotoNodes. Clone from this one.
354 MachNode *_goto;
355
356 Block* insert_anti_dependences(Block* LCA, Node* load, bool verify = false);
357 void verify_anti_dependences(Block* LCA, Node* load) {
358 assert(LCA == _bbs[load->_idx], "should already be scheduled");
359 insert_anti_dependences(LCA, load, true);
360 }
361
362 public:
363 PhaseCFG( Arena *a, RootNode *r, Matcher &m );
364
365 uint _num_blocks; // Count of basic blocks
366 Block_List _blocks; // List of basic blocks
367 RootNode *_root; // Root of whole program
368 Block_Array _bbs; // Map Nodes to owning Basic Block
369 Block *_broot; // Basic block of root
370 uint _rpo_ctr;
371 CFGLoop* _root_loop;
372
373 // Per node latency estimation, valid only during GCM
374 GrowableArray<uint> _node_latency;
375
376 #ifndef PRODUCT
377 bool _trace_opto_pipelining; // tracing flag
378 #endif
379
380 // Build dominators
381 void Dominators();
382
383 // Estimate block frequencies based on IfNode probabilities
384 void Estimate_Block_Frequency();
385
386 // Global Code Motion. See Click's PLDI95 paper. Place Nodes in specific
387 // basic blocks; i.e. _bbs now maps _idx for all Nodes to some Block.
388 void GlobalCodeMotion( Matcher &m, uint unique, Node_List &proj_list );
389
390 // Compute the (backwards) latency of a node from the uses
391 void latency_from_uses(Node *n);
392
393 // Compute the (backwards) latency of a node from a single use
394 int latency_from_use(Node *n, const Node *def, Node *use);
395
396 // Compute the (backwards) latency of a node from the uses of this instruction
397 void partial_latency_of_defs(Node *n);
398
399 // Schedule Nodes early in their basic blocks.
400 bool schedule_early(VectorSet &visited, Node_List &roots);
401
402 // For each node, find the latest block it can be scheduled into
403 // and then select the cheapest block between the latest and earliest
404 // block to place the node.
405 void schedule_late(VectorSet &visited, Node_List &stack);
406
407 // Pick a block between early and late that is a cheaper alternative
408 // to late. Helper for schedule_late.
409 Block* hoist_to_cheaper_block(Block* LCA, Block* early, Node* self);
410
411 // Compute the instruction global latency with a backwards walk
412 void ComputeLatenciesBackwards(VectorSet &visited, Node_List &stack);
413
414 // Set loop alignment
415 void set_loop_alignment();
416
417 // Remove empty basic blocks
418 void remove_empty();
419 void fixup_flow();
420 bool move_to_next(Block* bx, uint b_index);
421 void move_to_end(Block* bx, uint b_index);
422 void insert_goto_at(uint block_no, uint succ_no);
423
424 // Check for NeverBranch at block end. This needs to become a GOTO to the
425 // true target. NeverBranch are treated as a conditional branch that always
426 // goes the same direction for most of the optimizer and are used to give a
427 // fake exit path to infinite loops. At this late stage they need to turn
428 // into Goto's so that when you enter the infinite loop you indeed hang.
429 void convert_NeverBranch_to_Goto(Block *b);
430
431 CFGLoop* create_loop_tree();
432
433 // Insert a node into a block, and update the _bbs
434 void insert( Block *b, uint idx, Node *n ) {
435 b->_nodes.insert( idx, n );
436 _bbs.map( n->_idx, b );
437 }
438
439 #ifndef PRODUCT
440 bool trace_opto_pipelining() const { return _trace_opto_pipelining; }
441
442 // Debugging print of CFG
443 void dump( ) const; // CFG only
444 void _dump_cfg( const Node *end, VectorSet &visited ) const;
445 void verify() const;
446 void dump_headers();
447 #else
448 bool trace_opto_pipelining() const { return false; }
449 #endif
450 };
451
452
453 //------------------------------UnionFind--------------------------------------
454 // Map Block indices to a block-index for a cfg-cover.
455 // Array lookup in the optimized case.
456 class UnionFind : public ResourceObj {
457 uint _cnt, _max;
458 uint* _indices;
459 ReallocMark _nesting; // assertion check for reallocations
460 public:
461 UnionFind( uint max );
462 void reset( uint max ); // Reset to identity map for [0..max]
463
464 uint lookup( uint nidx ) const {
465 return _indices[nidx];
466 }
467 uint operator[] (uint nidx) const { return lookup(nidx); }
468
469 void map( uint from_idx, uint to_idx ) {
470 assert( from_idx < _cnt, "oob" );
471 _indices[from_idx] = to_idx;
472 }
473 void extend( uint from_idx, uint to_idx );
474
475 uint Size() const { return _cnt; }
476
477 uint Find( uint idx ) {
478 assert( idx < 65536, "Must fit into uint");
479 uint uf_idx = lookup(idx);
480 return (uf_idx == idx) ? uf_idx : Find_compress(idx);
481 }
482 uint Find_compress( uint idx );
483 uint Find_const( uint idx ) const;
484 void Union( uint idx1, uint idx2 );
485
486 };
487
488 //----------------------------BlockProbPair---------------------------
489 // Ordered pair of Node*.
490 class BlockProbPair VALUE_OBJ_CLASS_SPEC {
491 protected:
492 Block* _target; // block target
493 float _prob; // probability of edge to block
494 public:
495 BlockProbPair() : _target(NULL), _prob(0.0) {}
496 BlockProbPair(Block* b, float p) : _target(b), _prob(p) {}
497
498 Block* get_target() const { return _target; }
499 float get_prob() const { return _prob; }
500 };
501
502 //------------------------------CFGLoop-------------------------------------------
503 class CFGLoop : public CFGElement {
504 int _id;
505 int _depth;
506 CFGLoop *_parent; // root of loop tree is the method level "pseudo" loop, it's parent is null
507 CFGLoop *_sibling; // null terminated list
508 CFGLoop *_child; // first child, use child's sibling to visit all immediately nested loops
509 GrowableArray<CFGElement*> _members; // list of members of loop
510 GrowableArray<BlockProbPair> _exits; // list of successor blocks and their probabilities
511 float _exit_prob; // probability any loop exit is taken on a single loop iteration
512 void update_succ_freq(Block* b, float freq);
513
514 public:
515 CFGLoop(int id) :
516 CFGElement(),
517 _id(id),
518 _depth(0),
519 _parent(NULL),
520 _sibling(NULL),
521 _child(NULL),
522 _exit_prob(1.0f) {}
523 CFGLoop* parent() { return _parent; }
524 void push_pred(Block* blk, int i, Block_List& worklist, Block_Array& node_to_blk);
525 void add_member(CFGElement *s) { _members.push(s); }
526 void add_nested_loop(CFGLoop* cl);
527 Block* head() {
528 assert(_members.at(0)->is_block(), "head must be a block");
529 Block* hd = _members.at(0)->as_Block();
530 assert(hd->_loop == this, "just checking");
531 assert(hd->head()->is_Loop(), "must begin with loop head node");
532 return hd;
533 }
534 Block* backedge_block(); // Return the block on the backedge of the loop (else NULL)
535 void compute_loop_depth(int depth);
536 void compute_freq(); // compute frequency with loop assuming head freq 1.0f
537 void scale_freq(); // scale frequency by loop trip count (including outer loops)
538 bool in_loop_nest(Block* b);
539 float trip_count() const { return 1.0f / _exit_prob; }
540 virtual bool is_loop() { return true; }
541 int id() { return _id; }
542
543 #ifndef PRODUCT
544 void dump( ) const;
545 void dump_tree() const;
546 #endif
547 };
548
549
550 //----------------------------------CFGEdge------------------------------------
551 // A edge between two basic blocks that will be embodied by a branch or a
552 // fall-through.
553 class CFGEdge : public ResourceObj {
554 private:
555 Block * _from; // Source basic block
556 Block * _to; // Destination basic block
557 float _freq; // Execution frequency (estimate)
558 int _state;
559 bool _infrequent;
560 int _from_pct;
561 int _to_pct;
562
563 // Private accessors
564 int from_pct() const { return _from_pct; }
565 int to_pct() const { return _to_pct; }
566 int from_infrequent() const { return from_pct() < BlockLayoutMinDiamondPercentage; }
567 int to_infrequent() const { return to_pct() < BlockLayoutMinDiamondPercentage; }
568
569 public:
570 enum {
571 open, // initial edge state; unprocessed
572 connected, // edge used to connect two traces together
573 interior // edge is interior to trace (could be backedge)
574 };
575
576 CFGEdge(Block *from, Block *to, float freq, int from_pct, int to_pct) :
577 _from(from), _to(to), _freq(freq),
578 _from_pct(from_pct), _to_pct(to_pct), _state(open) {
579 _infrequent = from_infrequent() || to_infrequent();
580 }
581
582 float freq() const { return _freq; }
583 Block* from() const { return _from; }
584 Block* to () const { return _to; }
585 int infrequent() const { return _infrequent; }
586 int state() const { return _state; }
587
588 void set_state(int state) { _state = state; }
589
590 #ifndef PRODUCT
591 void dump( ) const;
592 #endif
593 };
594
595
596 //-----------------------------------Trace-------------------------------------
597 // An ordered list of basic blocks.
598 class Trace : public ResourceObj {
599 private:
600 uint _id; // Unique Trace id (derived from initial block)
601 Block ** _next_list; // Array mapping index to next block
602 Block ** _prev_list; // Array mapping index to previous block
603 Block * _first; // First block in the trace
604 Block * _last; // Last block in the trace
605
606 // Return the block that follows "b" in the trace.
607 Block * next(Block *b) const { return _next_list[b->_pre_order]; }
608 void set_next(Block *b, Block *n) const { _next_list[b->_pre_order] = n; }
609
610 // Return the block that preceeds "b" in the trace.
611 Block * prev(Block *b) const { return _prev_list[b->_pre_order]; }
612 void set_prev(Block *b, Block *p) const { _prev_list[b->_pre_order] = p; }
613
614 // We've discovered a loop in this trace. Reset last to be "b", and first as
615 // the block following "b
616 void break_loop_after(Block *b) {
617 _last = b;
618 _first = next(b);
619 set_prev(_first, NULL);
620 set_next(_last, NULL);
621 }
622
623 public:
624
625 Trace(Block *b, Block **next_list, Block **prev_list) :
626 _first(b),
627 _last(b),
628 _next_list(next_list),
629 _prev_list(prev_list),
630 _id(b->_pre_order) {
631 set_next(b, NULL);
632 set_prev(b, NULL);
633 };
634
635 // Return the id number
636 uint id() const { return _id; }
637 void set_id(uint id) { _id = id; }
638
639 // Return the first block in the trace
640 Block * first_block() const { return _first; }
641
642 // Return the last block in the trace
643 Block * last_block() const { return _last; }
644
645 // Insert a trace in the middle of this one after b
646 void insert_after(Block *b, Trace *tr) {
647 set_next(tr->last_block(), next(b));
648 if (next(b) != NULL) {
649 set_prev(next(b), tr->last_block());
650 }
651
652 set_next(b, tr->first_block());
653 set_prev(tr->first_block(), b);
654
655 if (b == _last) {
656 _last = tr->last_block();
657 }
658 }
659
660 void insert_before(Block *b, Trace *tr) {
661 Block *p = prev(b);
662 assert(p != NULL, "use append instead");
663 insert_after(p, tr);
664 }
665
666 // Append another trace to this one.
667 void append(Trace *tr) {
668 insert_after(_last, tr);
669 }
670
671 // Append a block at the end of this trace
672 void append(Block *b) {
673 set_next(_last, b);
674 set_prev(b, _last);
675 _last = b;
676 }
677
678 // Adjust the the blocks in this trace
679 void fixup_blocks(PhaseCFG &cfg);
680 bool backedge(CFGEdge *e);
681
682 #ifndef PRODUCT
683 void dump( ) const;
684 #endif
685 };
686
687 //------------------------------PhaseBlockLayout-------------------------------
688 // Rearrange blocks into some canonical order, based on edges and their frequencies
689 class PhaseBlockLayout : public Phase {
690 PhaseCFG &_cfg; // Control flow graph
691
692 GrowableArray<CFGEdge *> *edges;
693 Trace **traces;
694 Block **next;
695 Block **prev;
696 UnionFind *uf;
697
698 // Given a block, find its encompassing Trace
699 Trace * trace(Block *b) {
700 return traces[uf->Find_compress(b->_pre_order)];
701 }
702 public:
703 PhaseBlockLayout(PhaseCFG &cfg);
704
705 void find_edges();
706 void grow_traces();
707 void merge_traces(bool loose_connections);
708 void reorder_traces(int count);
709 void union_traces(Trace* from, Trace* to);
710 };