1 /*
2 * Copyright (c) 1997, 2019, 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,
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23 */
24
25 #ifndef SHARE_OPTO_BLOCK_HPP
26 #define SHARE_OPTO_BLOCK_HPP
27
28 #include "opto/multnode.hpp"
29 #include "opto/node.hpp"
30 #include "opto/phase.hpp"
31
32 // Optimization - Graph Style
33
34 class Block;
35 class CFGLoop;
36 class MachCallNode;
37 class Matcher;
38 class RootNode;
39 class VectorSet;
40 class PhaseChaitin;
41 struct Tarjan;
42
43 //------------------------------Block_Array------------------------------------
44 // Map dense integer indices to Blocks. Uses classic doubling-array trick.
45 // Abstractly provides an infinite array of Block*'s, initialized to NULL.
46 // Note that the constructor just zeros things, and since I use Arena
47 // allocation I do not need a destructor to reclaim storage.
48 class Block_Array : public ResourceObj {
49 friend class VMStructs;
50 uint _size; // allocated size, as opposed to formal limit
51 debug_only(uint _limit;) // limit to formal domain
52 Arena *_arena; // Arena to allocate in
53 protected:
54 Block **_blocks;
55 void grow( uint i ); // Grow array node to fit
56
57 public:
58 Block_Array(Arena *a) : _size(OptoBlockListSize), _arena(a) {
59 debug_only(_limit=0);
60 _blocks = NEW_ARENA_ARRAY( a, Block *, OptoBlockListSize );
61 for( int i = 0; i < OptoBlockListSize; i++ ) {
62 _blocks[i] = NULL;
63 }
64 }
65 Block *lookup( uint i ) const // Lookup, or NULL for not mapped
66 { return (i<Max()) ? _blocks[i] : (Block*)NULL; }
67 Block *operator[] ( uint i ) const // Lookup, or assert for not mapped
68 { assert( i < Max(), "oob" ); return _blocks[i]; }
69 // Extend the mapping: index i maps to Block *n.
70 void map( uint i, Block *n ) { if( i>=Max() ) grow(i); _blocks[i] = n; }
71 uint Max() const { debug_only(return _limit); return _size; }
72 };
73
74
75 class Block_List : public Block_Array {
76 friend class VMStructs;
77 public:
78 uint _cnt;
79 Block_List() : Block_Array(Thread::current()->resource_area()), _cnt(0) {}
80 void push( Block *b ) { map(_cnt++,b); }
81 Block *pop() { return _blocks[--_cnt]; }
82 Block *rpop() { Block *b = _blocks[0]; _blocks[0]=_blocks[--_cnt]; return b;}
83 void remove( uint i );
84 void insert( uint i, Block *n );
85 uint size() const { return _cnt; }
86 void reset() { _cnt = 0; }
87 void print();
88 };
89
90
91 class CFGElement : public ResourceObj {
92 friend class VMStructs;
93 public:
94 double _freq; // Execution frequency (estimate)
95
96 CFGElement() : _freq(0.0) {}
97 virtual bool is_block() { return false; }
98 virtual bool is_loop() { return false; }
99 Block* as_Block() { assert(is_block(), "must be block"); return (Block*)this; }
100 CFGLoop* as_CFGLoop() { assert(is_loop(), "must be loop"); return (CFGLoop*)this; }
101 };
102
103 //------------------------------Block------------------------------------------
104 // This class defines a Basic Block.
105 // Basic blocks are used during the output routines, and are not used during
106 // any optimization pass. They are created late in the game.
107 class Block : public CFGElement {
108 friend class VMStructs;
109
110 private:
111 // Nodes in this block, in order
112 Node_List _nodes;
113
114 public:
115
116 // Get the node at index 'at_index', if 'at_index' is out of bounds return NULL
117 Node* get_node(uint at_index) const {
118 return _nodes[at_index];
119 }
120
121 // Get the number of nodes in this block
122 uint number_of_nodes() const {
123 return _nodes.size();
124 }
125
126 // Map a node 'node' to index 'to_index' in the block, if the index is out of bounds the size of the node list is increased
127 void map_node(Node* node, uint to_index) {
128 _nodes.map(to_index, node);
129 }
130
131 // Insert a node 'node' at index 'at_index', moving all nodes that are on a higher index one step, if 'at_index' is out of bounds we crash
132 void insert_node(Node* node, uint at_index) {
133 _nodes.insert(at_index, node);
134 }
135
136 // Remove a node at index 'at_index'
137 void remove_node(uint at_index) {
138 _nodes.remove(at_index);
139 }
140
141 // Push a node 'node' onto the node list
142 void push_node(Node* node) {
143 _nodes.push(node);
144 }
145
146 // Pop the last node off the node list
147 Node* pop_node() {
148 return _nodes.pop();
149 }
150
151 // Basic blocks have a Node which defines Control for all Nodes pinned in
152 // this block. This Node is a RegionNode. Exception-causing Nodes
153 // (division, subroutines) and Phi functions are always pinned. Later,
154 // every Node will get pinned to some block.
155 Node *head() const { return get_node(0); }
156
157 // CAUTION: num_preds() is ONE based, so that predecessor numbers match
158 // input edges to Regions and Phis.
159 uint num_preds() const { return head()->req(); }
160 Node *pred(uint i) const { return head()->in(i); }
161
162 // Array of successor blocks, same size as projs array
163 Block_Array _succs;
164
165 // Basic blocks have some number of Nodes which split control to all
166 // following blocks. These Nodes are always Projections. The field in
167 // the Projection and the block-ending Node determine which Block follows.
168 uint _num_succs;
169
170 // Basic blocks also carry all sorts of good old fashioned DFS information
171 // used to find loops, loop nesting depth, dominators, etc.
172 uint _pre_order; // Pre-order DFS number
173
174 // Dominator tree
175 uint _dom_depth; // Depth in dominator tree for fast LCA
176 Block* _idom; // Immediate dominator block
177
178 CFGLoop *_loop; // Loop to which this block belongs
179 uint _rpo; // Number in reverse post order walk
180
181 virtual bool is_block() { return true; }
182 float succ_prob(uint i); // return probability of i'th successor
183 int num_fall_throughs(); // How many fall-through candidate this block has
184 void update_uncommon_branch(Block* un); // Lower branch prob to uncommon code
185 bool succ_fall_through(uint i); // Is successor "i" is a fall-through candidate
186 Block* lone_fall_through(); // Return lone fall-through Block or null
187
188 Block* dom_lca(Block* that); // Compute LCA in dominator tree.
189
190 bool dominates(Block* that) {
191 int dom_diff = this->_dom_depth - that->_dom_depth;
192 if (dom_diff > 0) return false;
193 for (; dom_diff < 0; dom_diff++) that = that->_idom;
194 return this == that;
195 }
196
197 // Report the alignment required by this block. Must be a power of 2.
198 // The previous block will insert nops to get this alignment.
199 uint code_alignment() const;
200 uint compute_loop_alignment();
201
202 // BLOCK_FREQUENCY is a sentinel to mark uses of constant block frequencies.
203 // It is currently also used to scale such frequencies relative to
204 // FreqCountInvocations relative to the old value of 1500.
205 #define BLOCK_FREQUENCY(f) ((f * (double) 1500) / FreqCountInvocations)
206
207 // Register Pressure (estimate) for Splitting heuristic
208 uint _reg_pressure;
209 uint _ihrp_index;
210 uint _freg_pressure;
211 uint _fhrp_index;
212
213 // Mark and visited bits for an LCA calculation in insert_anti_dependences.
214 // Since they hold unique node indexes, they do not need reinitialization.
215 node_idx_t _raise_LCA_mark;
216 void set_raise_LCA_mark(node_idx_t x) { _raise_LCA_mark = x; }
217 node_idx_t raise_LCA_mark() const { return _raise_LCA_mark; }
218 node_idx_t _raise_LCA_visited;
219 void set_raise_LCA_visited(node_idx_t x) { _raise_LCA_visited = x; }
220 node_idx_t raise_LCA_visited() const { return _raise_LCA_visited; }
221
222 // Estimated size in bytes of first instructions in a loop.
223 uint _first_inst_size;
224 uint first_inst_size() const { return _first_inst_size; }
225 void set_first_inst_size(uint s) { _first_inst_size = s; }
226
227 // Compute the size of first instructions in this block.
228 uint compute_first_inst_size(uint& sum_size, uint inst_cnt, PhaseRegAlloc* ra);
229
230 // Compute alignment padding if the block needs it.
231 // Align a loop if loop's padding is less or equal to padding limit
232 // or the size of first instructions in the loop > padding.
233 uint alignment_padding(int current_offset) {
234 int block_alignment = code_alignment();
235 int max_pad = block_alignment-relocInfo::addr_unit();
236 if( max_pad > 0 ) {
237 assert(is_power_of_2(max_pad+relocInfo::addr_unit()), "");
238 int current_alignment = current_offset & max_pad;
239 if( current_alignment != 0 ) {
240 uint padding = (block_alignment-current_alignment) & max_pad;
241 if( has_loop_alignment() &&
242 padding > (uint)MaxLoopPad &&
243 first_inst_size() <= padding ) {
244 return 0;
245 }
246 return padding;
247 }
248 }
249 return 0;
250 }
251
252 // Connector blocks. Connector blocks are basic blocks devoid of
253 // instructions, but may have relevant non-instruction Nodes, such as
254 // Phis or MergeMems. Such blocks are discovered and marked during the
255 // RemoveEmpty phase, and elided during Output.
256 bool _connector;
257 void set_connector() { _connector = true; }
258 bool is_connector() const { return _connector; };
259
260 // Loop_alignment will be set for blocks which are at the top of loops.
261 // The block layout pass may rotate loops such that the loop head may not
262 // be the sequentially first block of the loop encountered in the linear
263 // list of blocks. If the layout pass is not run, loop alignment is set
264 // for each block which is the head of a loop.
265 uint _loop_alignment;
266 void set_loop_alignment(Block *loop_top) {
267 uint new_alignment = loop_top->compute_loop_alignment();
268 if (new_alignment > _loop_alignment) {
269 _loop_alignment = new_alignment;
270 }
271 }
272 uint loop_alignment() const { return _loop_alignment; }
273 bool has_loop_alignment() const { return loop_alignment() > 0; }
274
275 // Create a new Block with given head Node.
276 // Creates the (empty) predecessor arrays.
277 Block( Arena *a, Node *headnode )
278 : CFGElement(),
279 _nodes(a),
280 _succs(a),
281 _num_succs(0),
282 _pre_order(0),
283 _idom(0),
284 _loop(NULL),
285 _reg_pressure(0),
286 _ihrp_index(1),
287 _freg_pressure(0),
288 _fhrp_index(1),
289 _raise_LCA_mark(0),
290 _raise_LCA_visited(0),
291 _first_inst_size(999999),
292 _connector(false),
293 _loop_alignment(0) {
294 _nodes.push(headnode);
295 }
296
297 // Index of 'end' Node
298 uint end_idx() const {
299 // %%%%% add a proj after every goto
300 // so (last->is_block_proj() != last) always, then simplify this code
301 // This will not give correct end_idx for block 0 when it only contains root.
302 int last_idx = _nodes.size() - 1;
303 Node *last = _nodes[last_idx];
304 assert(last->is_block_proj() == last || last->is_block_proj() == _nodes[last_idx - _num_succs], "");
305 return (last->is_block_proj() == last) ? last_idx : (last_idx - _num_succs);
306 }
307
308 // Basic blocks have a Node which ends them. This Node determines which
309 // basic block follows this one in the program flow. This Node is either an
310 // IfNode, a GotoNode, a JmpNode, or a ReturnNode.
311 Node *end() const { return _nodes[end_idx()]; }
312
313 // Add an instruction to an existing block. It must go after the head
314 // instruction and before the end instruction.
315 void add_inst( Node *n ) { insert_node(n, end_idx()); }
316 // Find node in block. Fails if node not in block.
317 uint find_node( const Node *n ) const;
318 // Find and remove n from block list
319 void find_remove( const Node *n );
320 // Check whether the node is in the block.
321 bool contains (const Node *n) const;
322
323 // Return the empty status of a block
324 enum { not_empty, empty_with_goto, completely_empty };
325 int is_Empty() const;
326
327 // Forward through connectors
328 Block* non_connector() {
329 Block* s = this;
330 while (s->is_connector()) {
331 s = s->_succs[0];
332 }
333 return s;
334 }
335
336 // Return true if b is a successor of this block
337 bool has_successor(Block* b) const {
338 for (uint i = 0; i < _num_succs; i++ ) {
339 if (non_connector_successor(i) == b) {
340 return true;
341 }
342 }
343 return false;
344 }
345
346 // Successor block, after forwarding through connectors
347 Block* non_connector_successor(int i) const {
348 return _succs[i]->non_connector();
349 }
350
351 // Examine block's code shape to predict if it is not commonly executed.
352 bool has_uncommon_code() const;
353
354 #ifndef PRODUCT
355 // Debugging print of basic block
356 void dump_bidx(const Block* orig, outputStream* st = tty) const;
357 void dump_pred(const PhaseCFG* cfg, Block* orig, outputStream* st = tty) const;
358 void dump_head(const PhaseCFG* cfg, outputStream* st = tty) const;
359 void dump() const;
360 void dump(const PhaseCFG* cfg) const;
361 #endif
362 };
363
364
365 //------------------------------PhaseCFG---------------------------------------
366 // Build an array of Basic Block pointers, one per Node.
367 class PhaseCFG : public Phase {
368 friend class VMStructs;
369 private:
370 // Root of whole program
371 RootNode* _root;
372
373 // The block containing the root node
374 Block* _root_block;
375
376 // List of basic blocks that are created during CFG creation
377 Block_List _blocks;
378
379 // Count of basic blocks
380 uint _number_of_blocks;
381
382 // Arena for the blocks to be stored in
383 Arena* _block_arena;
384
385 // Info used for scheduling
386 PhaseChaitin* _regalloc;
387
388 // Register pressure heuristic used?
389 bool _scheduling_for_pressure;
390
391 // The matcher for this compilation
392 Matcher& _matcher;
393
394 // Map nodes to owning basic block
395 Block_Array _node_to_block_mapping;
396
397 // Loop from the root
398 CFGLoop* _root_loop;
399
400 // Outmost loop frequency
401 double _outer_loop_frequency;
402
403 // Per node latency estimation, valid only during GCM
404 GrowableArray<uint>* _node_latency;
405
406 // Build a proper looking cfg. Return count of basic blocks
407 uint build_cfg();
408
409 // Build the dominator tree so that we know where we can move instructions
410 void build_dominator_tree();
411
412 // Estimate block frequencies based on IfNode probabilities, so that we know where we want to move instructions
413 void estimate_block_frequency();
414
415 // Global Code Motion. See Click's PLDI95 paper. Place Nodes in specific
416 // basic blocks; i.e. _node_to_block_mapping now maps _idx for all Nodes to some Block.
417 // Move nodes to ensure correctness from GVN and also try to move nodes out of loops.
418 void global_code_motion();
419
420 // Schedule Nodes early in their basic blocks.
421 bool schedule_early(VectorSet &visited, Node_Stack &roots);
422
423 // For each node, find the latest block it can be scheduled into
424 // and then select the cheapest block between the latest and earliest
425 // block to place the node.
426 void schedule_late(VectorSet &visited, Node_Stack &stack);
427
428 // Compute the (backwards) latency of a node from a single use
429 int latency_from_use(Node *n, const Node *def, Node *use);
430
431 // Compute the (backwards) latency of a node from the uses of this instruction
432 void partial_latency_of_defs(Node *n);
433
434 // Compute the instruction global latency with a backwards walk
435 void compute_latencies_backwards(VectorSet &visited, Node_Stack &stack);
436
437 // Pick a block between early and late that is a cheaper alternative
438 // to late. Helper for schedule_late.
439 Block* hoist_to_cheaper_block(Block* LCA, Block* early, Node* self);
440
441 bool schedule_local(Block* block, GrowableArray<int>& ready_cnt, VectorSet& next_call, intptr_t* recacl_pressure_nodes);
442 void set_next_call(Block* block, Node* n, VectorSet& next_call);
443 void needed_for_next_call(Block* block, Node* this_call, VectorSet& next_call);
444
445 // Perform basic-block local scheduling
446 Node* select(Block* block, Node_List& worklist, GrowableArray<int>& ready_cnt, VectorSet& next_call, uint sched_slot,
447 intptr_t* recacl_pressure_nodes);
448 void adjust_register_pressure(Node* n, Block* block, intptr_t *recalc_pressure_nodes, bool finalize_mode);
449
450 // Schedule a call next in the block
451 uint sched_call(Block* block, uint node_cnt, Node_List& worklist, GrowableArray<int>& ready_cnt, MachCallNode* mcall, VectorSet& next_call);
452
453 // Cleanup if any code lands between a Call and his Catch
454 void call_catch_cleanup(Block* block);
455
456 Node* catch_cleanup_find_cloned_def(Block* use_blk, Node* def, Block* def_blk, int n_clone_idx);
457 void catch_cleanup_inter_block(Node *use, Block *use_blk, Node *def, Block *def_blk, int n_clone_idx);
458
459 // Detect implicit-null-check opportunities. Basically, find NULL checks
460 // with suitable memory ops nearby. Use the memory op to do the NULL check.
461 // I can generate a memory op if there is not one nearby.
462 void implicit_null_check(Block* block, Node *proj, Node *val, int allowed_reasons);
463
464 // Perform a Depth First Search (DFS).
465 // Setup 'vertex' as DFS to vertex mapping.
466 // Setup 'semi' as vertex to DFS mapping.
467 // Set 'parent' to DFS parent.
468 uint do_DFS(Tarjan* tarjan, uint rpo_counter);
469
470 // Helper function to insert a node into a block
471 void schedule_node_into_block( Node *n, Block *b );
472
473 void replace_block_proj_ctrl( Node *n );
474
475 // Set the basic block for pinned Nodes
476 void schedule_pinned_nodes( VectorSet &visited );
477
478 // I'll need a few machine-specific GotoNodes. Clone from this one.
479 // Used when building the CFG and creating end nodes for blocks.
480 MachNode* _goto;
481
482 Block* insert_anti_dependences(Block* LCA, Node* load, bool verify = false);
483 void verify_anti_dependences(Block* LCA, Node* load) const {
484 assert(LCA == get_block_for_node(load), "should already be scheduled");
485 const_cast<PhaseCFG*>(this)->insert_anti_dependences(LCA, load, true);
486 }
487
488 bool move_to_next(Block* bx, uint b_index);
489 void move_to_end(Block* bx, uint b_index);
490
491 void insert_goto_at(uint block_no, uint succ_no);
492
493 // Check for NeverBranch at block end. This needs to become a GOTO to the
494 // true target. NeverBranch are treated as a conditional branch that always
495 // goes the same direction for most of the optimizer and are used to give a
496 // fake exit path to infinite loops. At this late stage they need to turn
497 // into Goto's so that when you enter the infinite loop you indeed hang.
498 void convert_NeverBranch_to_Goto(Block *b);
499
500 CFGLoop* create_loop_tree();
501 bool is_dominator(Node* dom_node, Node* node);
502
503 #ifndef PRODUCT
504 bool _trace_opto_pipelining; // tracing flag
505 #endif
506
507 public:
508 PhaseCFG(Arena* arena, RootNode* root, Matcher& matcher);
509
510 void set_latency_for_node(Node* node, int latency) {
511 _node_latency->at_put_grow(node->_idx, latency);
512 }
513
514 uint get_latency_for_node(Node* node) {
515 return _node_latency->at_grow(node->_idx);
516 }
517
518 // Get the outer most frequency
519 double get_outer_loop_frequency() const {
520 return _outer_loop_frequency;
521 }
522
523 // Get the root node of the CFG
524 RootNode* get_root_node() const {
525 return _root;
526 }
527
528 // Get the block of the root node
529 Block* get_root_block() const {
530 return _root_block;
531 }
532
533 // Add a block at a position and moves the later ones one step
534 void add_block_at(uint pos, Block* block) {
535 _blocks.insert(pos, block);
536 _number_of_blocks++;
537 }
538
539 // Adds a block to the top of the block list
540 void add_block(Block* block) {
541 _blocks.push(block);
542 _number_of_blocks++;
543 }
544
545 // Clear the list of blocks
546 void clear_blocks() {
547 _blocks.reset();
548 _number_of_blocks = 0;
549 }
550
551 // Get the block at position pos in _blocks
552 Block* get_block(uint pos) const {
553 return _blocks[pos];
554 }
555
556 // Number of blocks
557 uint number_of_blocks() const {
558 return _number_of_blocks;
559 }
560
561 // set which block this node should reside in
562 void map_node_to_block(const Node* node, Block* block) {
563 _node_to_block_mapping.map(node->_idx, block);
564 }
565
566 // removes the mapping from a node to a block
567 void unmap_node_from_block(const Node* node) {
568 _node_to_block_mapping.map(node->_idx, NULL);
569 }
570
571 // get the block in which this node resides
572 Block* get_block_for_node(const Node* node) const {
573 return _node_to_block_mapping[node->_idx];
574 }
575
576 // does this node reside in a block; return true
577 bool has_block(const Node* node) const {
578 return (_node_to_block_mapping.lookup(node->_idx) != NULL);
579 }
580
581 // Use frequency calculations and code shape to predict if the block
582 // is uncommon.
583 bool is_uncommon(const Block* block);
584
585 #ifdef ASSERT
586 Unique_Node_List _raw_oops;
587 #endif
588
589 // Do global code motion by first building dominator tree and estimate block frequency
590 // Returns true on success
591 bool do_global_code_motion();
592
593 // Compute the (backwards) latency of a node from the uses
594 void latency_from_uses(Node *n);
595
596 // Set loop alignment
597 void set_loop_alignment();
598
599 // Remove empty basic blocks
600 void remove_empty_blocks();
601 Block *fixup_trap_based_check(Node *branch, Block *block, int block_pos, Block *bnext);
602 void fixup_flow();
603
604 // Insert a node into a block at index and map the node to the block
605 void insert(Block *b, uint idx, Node *n) {
606 b->insert_node(n , idx);
607 map_node_to_block(n, b);
608 }
609
610 // Check all nodes and postalloc_expand them if necessary.
611 void postalloc_expand(PhaseRegAlloc* _ra);
612
613 #ifndef PRODUCT
614 bool trace_opto_pipelining() const { return _trace_opto_pipelining; }
615
616 // Debugging print of CFG
617 void dump( ) const; // CFG only
618 void _dump_cfg( const Node *end, VectorSet &visited ) const;
619 void verify() const;
620 void dump_headers();
621 #else
622 bool trace_opto_pipelining() const { return false; }
623 #endif
624 };
625
626
627 //------------------------------UnionFind--------------------------------------
628 // Map Block indices to a block-index for a cfg-cover.
629 // Array lookup in the optimized case.
630 class UnionFind : public ResourceObj {
631 uint _cnt, _max;
632 uint* _indices;
633 ReallocMark _nesting; // assertion check for reallocations
634 public:
635 UnionFind( uint max );
636 void reset( uint max ); // Reset to identity map for [0..max]
637
638 uint lookup( uint nidx ) const {
639 return _indices[nidx];
640 }
641 uint operator[] (uint nidx) const { return lookup(nidx); }
642
643 void map( uint from_idx, uint to_idx ) {
644 assert( from_idx < _cnt, "oob" );
645 _indices[from_idx] = to_idx;
646 }
647 void extend( uint from_idx, uint to_idx );
648
649 uint Size() const { return _cnt; }
650
651 uint Find( uint idx ) {
652 assert( idx < 65536, "Must fit into uint");
653 uint uf_idx = lookup(idx);
654 return (uf_idx == idx) ? uf_idx : Find_compress(idx);
655 }
656 uint Find_compress( uint idx );
657 uint Find_const( uint idx ) const;
658 void Union( uint idx1, uint idx2 );
659
660 };
661
662 //----------------------------BlockProbPair---------------------------
663 // Ordered pair of Node*.
664 class BlockProbPair {
665 protected:
666 Block* _target; // block target
667 double _prob; // probability of edge to block
668 public:
669 BlockProbPair() : _target(NULL), _prob(0.0) {}
670 BlockProbPair(Block* b, double p) : _target(b), _prob(p) {}
671
672 Block* get_target() const { return _target; }
673 double get_prob() const { return _prob; }
674 };
675
676 //------------------------------CFGLoop-------------------------------------------
677 class CFGLoop : public CFGElement {
678 friend class VMStructs;
679 int _id;
680 int _depth;
681 CFGLoop *_parent; // root of loop tree is the method level "pseudo" loop, it's parent is null
682 CFGLoop *_sibling; // null terminated list
683 CFGLoop *_child; // first child, use child's sibling to visit all immediately nested loops
684 GrowableArray<CFGElement*> _members; // list of members of loop
685 GrowableArray<BlockProbPair> _exits; // list of successor blocks and their probabilities
686 double _exit_prob; // probability any loop exit is taken on a single loop iteration
687 void update_succ_freq(Block* b, double freq);
688
689 public:
690 CFGLoop(int id) :
691 CFGElement(),
692 _id(id),
693 _depth(0),
694 _parent(NULL),
695 _sibling(NULL),
696 _child(NULL),
697 _exit_prob(1.0f) {}
698 CFGLoop* parent() { return _parent; }
699 void push_pred(Block* blk, int i, Block_List& worklist, PhaseCFG* cfg);
700 void add_member(CFGElement *s) { _members.push(s); }
701 void add_nested_loop(CFGLoop* cl);
702 Block* head() {
703 assert(_members.at(0)->is_block(), "head must be a block");
704 Block* hd = _members.at(0)->as_Block();
705 assert(hd->_loop == this, "just checking");
706 assert(hd->head()->is_Loop(), "must begin with loop head node");
707 return hd;
708 }
709 Block* backedge_block(); // Return the block on the backedge of the loop (else NULL)
710 void compute_loop_depth(int depth);
711 void compute_freq(); // compute frequency with loop assuming head freq 1.0f
712 void scale_freq(); // scale frequency by loop trip count (including outer loops)
713 double outer_loop_freq() const; // frequency of outer loop
714 bool in_loop_nest(Block* b);
715 double trip_count() const { return 1.0 / _exit_prob; }
716 virtual bool is_loop() { return true; }
717 int id() { return _id; }
718
719 #ifndef PRODUCT
720 void dump( ) const;
721 void dump_tree() const;
722 #endif
723 };
724
725
726 //----------------------------------CFGEdge------------------------------------
727 // A edge between two basic blocks that will be embodied by a branch or a
728 // fall-through.
729 class CFGEdge : public ResourceObj {
730 friend class VMStructs;
731 private:
732 Block * _from; // Source basic block
733 Block * _to; // Destination basic block
734 double _freq; // Execution frequency (estimate)
735 int _state;
736 bool _infrequent;
737 int _from_pct;
738 int _to_pct;
739
740 // Private accessors
741 int from_pct() const { return _from_pct; }
742 int to_pct() const { return _to_pct; }
743 int from_infrequent() const { return from_pct() < BlockLayoutMinDiamondPercentage; }
744 int to_infrequent() const { return to_pct() < BlockLayoutMinDiamondPercentage; }
745
746 public:
747 enum {
748 open, // initial edge state; unprocessed
749 connected, // edge used to connect two traces together
750 interior // edge is interior to trace (could be backedge)
751 };
752
753 CFGEdge(Block *from, Block *to, double freq, int from_pct, int to_pct) :
754 _from(from), _to(to), _freq(freq),
755 _state(open), _from_pct(from_pct), _to_pct(to_pct) {
756 _infrequent = from_infrequent() || to_infrequent();
757 }
758
759 double freq() const { return _freq; }
760 Block* from() const { return _from; }
761 Block* to () const { return _to; }
762 int infrequent() const { return _infrequent; }
763 int state() const { return _state; }
764
765 void set_state(int state) { _state = state; }
766
767 #ifndef PRODUCT
768 void dump( ) const;
769 #endif
770 };
771
772
773 //-----------------------------------Trace-------------------------------------
774 // An ordered list of basic blocks.
775 class Trace : public ResourceObj {
776 private:
777 uint _id; // Unique Trace id (derived from initial block)
778 Block ** _next_list; // Array mapping index to next block
779 Block ** _prev_list; // Array mapping index to previous block
780 Block * _first; // First block in the trace
781 Block * _last; // Last block in the trace
782
783 // Return the block that follows "b" in the trace.
784 Block * next(Block *b) const { return _next_list[b->_pre_order]; }
785 void set_next(Block *b, Block *n) const { _next_list[b->_pre_order] = n; }
786
787 // Return the block that precedes "b" in the trace.
788 Block * prev(Block *b) const { return _prev_list[b->_pre_order]; }
789 void set_prev(Block *b, Block *p) const { _prev_list[b->_pre_order] = p; }
790
791 // We've discovered a loop in this trace. Reset last to be "b", and first as
792 // the block following "b
793 void break_loop_after(Block *b) {
794 _last = b;
795 _first = next(b);
796 set_prev(_first, NULL);
797 set_next(_last, NULL);
798 }
799
800 public:
801
802 Trace(Block *b, Block **next_list, Block **prev_list) :
803 _id(b->_pre_order),
804 _next_list(next_list),
805 _prev_list(prev_list),
806 _first(b),
807 _last(b) {
808 set_next(b, NULL);
809 set_prev(b, NULL);
810 };
811
812 // Return the id number
813 uint id() const { return _id; }
814 void set_id(uint id) { _id = id; }
815
816 // Return the first block in the trace
817 Block * first_block() const { return _first; }
818
819 // Return the last block in the trace
820 Block * last_block() const { return _last; }
821
822 // Insert a trace in the middle of this one after b
823 void insert_after(Block *b, Trace *tr) {
824 set_next(tr->last_block(), next(b));
825 if (next(b) != NULL) {
826 set_prev(next(b), tr->last_block());
827 }
828
829 set_next(b, tr->first_block());
830 set_prev(tr->first_block(), b);
831
832 if (b == _last) {
833 _last = tr->last_block();
834 }
835 }
836
837 void insert_before(Block *b, Trace *tr) {
838 Block *p = prev(b);
839 assert(p != NULL, "use append instead");
840 insert_after(p, tr);
841 }
842
843 // Append another trace to this one.
844 void append(Trace *tr) {
845 insert_after(_last, tr);
846 }
847
848 // Append a block at the end of this trace
849 void append(Block *b) {
850 set_next(_last, b);
851 set_prev(b, _last);
852 _last = b;
853 }
854
855 // Adjust the the blocks in this trace
856 void fixup_blocks(PhaseCFG &cfg);
857 bool backedge(CFGEdge *e);
858
859 #ifndef PRODUCT
860 void dump( ) const;
861 #endif
862 };
863
864 //------------------------------PhaseBlockLayout-------------------------------
865 // Rearrange blocks into some canonical order, based on edges and their frequencies
866 class PhaseBlockLayout : public Phase {
867 friend class VMStructs;
868 PhaseCFG &_cfg; // Control flow graph
869
870 GrowableArray<CFGEdge *> *edges;
871 Trace **traces;
872 Block **next;
873 Block **prev;
874 UnionFind *uf;
875
876 // Given a block, find its encompassing Trace
877 Trace * trace(Block *b) {
878 return traces[uf->Find_compress(b->_pre_order)];
879 }
880 public:
881 PhaseBlockLayout(PhaseCFG &cfg);
882
883 void find_edges();
884 void grow_traces();
885 void merge_traces(bool loose_connections);
886 void reorder_traces(int count);
887 void union_traces(Trace* from, Trace* to);
888 };
889
890 #endif // SHARE_OPTO_BLOCK_HPP