Mercurial > hg > graal-compiler
annotate src/share/vm/opto/block.cpp @ 1468:e4cd5d2de7e1
Changes to sync with CRI changes.
author | Doug Simon <doug.simon@oracle.com> |
---|---|
date | Fri, 19 Nov 2010 00:26:51 +0100 |
parents | dd0a4e1e219b |
children | c18cbe5936b8 |
rev | line source |
---|---|
0 | 1 /* |
579 | 2 * Copyright 1997-2009 Sun Microsystems, Inc. All Rights Reserved. |
0 | 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 #include "incls/_precompiled.incl" | |
28 #include "incls/_block.cpp.incl" | |
29 | |
30 | |
31 //----------------------------------------------------------------------------- | |
32 void Block_Array::grow( uint i ) { | |
33 assert(i >= Max(), "must be an overflow"); | |
34 debug_only(_limit = i+1); | |
35 if( i < _size ) return; | |
36 if( !_size ) { | |
37 _size = 1; | |
38 _blocks = (Block**)_arena->Amalloc( _size * sizeof(Block*) ); | |
39 _blocks[0] = NULL; | |
40 } | |
41 uint old = _size; | |
42 while( i >= _size ) _size <<= 1; // Double to fit | |
43 _blocks = (Block**)_arena->Arealloc( _blocks, old*sizeof(Block*),_size*sizeof(Block*)); | |
44 Copy::zero_to_bytes( &_blocks[old], (_size-old)*sizeof(Block*) ); | |
45 } | |
46 | |
47 //============================================================================= | |
48 void Block_List::remove(uint i) { | |
49 assert(i < _cnt, "index out of bounds"); | |
50 Copy::conjoint_words_to_lower((HeapWord*)&_blocks[i+1], (HeapWord*)&_blocks[i], ((_cnt-i-1)*sizeof(Block*))); | |
51 pop(); // shrink list by one block | |
52 } | |
53 | |
54 void Block_List::insert(uint i, Block *b) { | |
55 push(b); // grow list by one block | |
56 Copy::conjoint_words_to_higher((HeapWord*)&_blocks[i], (HeapWord*)&_blocks[i+1], ((_cnt-i-1)*sizeof(Block*))); | |
57 _blocks[i] = b; | |
58 } | |
59 | |
418 | 60 #ifndef PRODUCT |
61 void Block_List::print() { | |
62 for (uint i=0; i < size(); i++) { | |
63 tty->print("B%d ", _blocks[i]->_pre_order); | |
64 } | |
65 tty->print("size = %d\n", size()); | |
66 } | |
67 #endif | |
0 | 68 |
69 //============================================================================= | |
70 | |
71 uint Block::code_alignment() { | |
72 // Check for Root block | |
73 if( _pre_order == 0 ) return CodeEntryAlignment; | |
74 // Check for Start block | |
75 if( _pre_order == 1 ) return InteriorEntryAlignment; | |
76 // Check for loop alignment | |
418 | 77 if (has_loop_alignment()) return loop_alignment(); |
78 | |
79 return 1; // no particular alignment | |
80 } | |
81 | |
82 uint Block::compute_loop_alignment() { | |
0 | 83 Node *h = head(); |
84 if( h->is_Loop() && h->as_Loop()->is_inner_loop() ) { | |
85 // Pre- and post-loops have low trip count so do not bother with | |
86 // NOPs for align loop head. The constants are hidden from tuning | |
87 // but only because my "divide by 4" heuristic surely gets nearly | |
88 // all possible gain (a "do not align at all" heuristic has a | |
89 // chance of getting a really tiny gain). | |
90 if( h->is_CountedLoop() && (h->as_CountedLoop()->is_pre_loop() || | |
91 h->as_CountedLoop()->is_post_loop()) ) | |
92 return (OptoLoopAlignment > 4) ? (OptoLoopAlignment>>2) : 1; | |
93 // Loops with low backedge frequency should not be aligned. | |
94 Node *n = h->in(LoopNode::LoopBackControl)->in(0); | |
95 if( n->is_MachIf() && n->as_MachIf()->_prob < 0.01 ) { | |
96 return 1; // Loop does not loop, more often than not! | |
97 } | |
98 return OptoLoopAlignment; // Otherwise align loop head | |
99 } | |
418 | 100 |
0 | 101 return 1; // no particular alignment |
102 } | |
103 | |
104 //----------------------------------------------------------------------------- | |
105 // Compute the size of first 'inst_cnt' instructions in this block. | |
106 // Return the number of instructions left to compute if the block has | |
418 | 107 // less then 'inst_cnt' instructions. Stop, and return 0 if sum_size |
108 // exceeds OptoLoopAlignment. | |
0 | 109 uint Block::compute_first_inst_size(uint& sum_size, uint inst_cnt, |
110 PhaseRegAlloc* ra) { | |
111 uint last_inst = _nodes.size(); | |
112 for( uint j = 0; j < last_inst && inst_cnt > 0; j++ ) { | |
113 uint inst_size = _nodes[j]->size(ra); | |
114 if( inst_size > 0 ) { | |
115 inst_cnt--; | |
116 uint sz = sum_size + inst_size; | |
117 if( sz <= (uint)OptoLoopAlignment ) { | |
118 // Compute size of instructions which fit into fetch buffer only | |
119 // since all inst_cnt instructions will not fit even if we align them. | |
120 sum_size = sz; | |
121 } else { | |
122 return 0; | |
123 } | |
124 } | |
125 } | |
126 return inst_cnt; | |
127 } | |
128 | |
129 //----------------------------------------------------------------------------- | |
130 uint Block::find_node( const Node *n ) const { | |
131 for( uint i = 0; i < _nodes.size(); i++ ) { | |
132 if( _nodes[i] == n ) | |
133 return i; | |
134 } | |
135 ShouldNotReachHere(); | |
136 return 0; | |
137 } | |
138 | |
139 // Find and remove n from block list | |
140 void Block::find_remove( const Node *n ) { | |
141 _nodes.remove(find_node(n)); | |
142 } | |
143 | |
144 //------------------------------is_Empty--------------------------------------- | |
145 // Return empty status of a block. Empty blocks contain only the head, other | |
146 // ideal nodes, and an optional trailing goto. | |
147 int Block::is_Empty() const { | |
148 | |
149 // Root or start block is not considered empty | |
150 if (head()->is_Root() || head()->is_Start()) { | |
151 return not_empty; | |
152 } | |
153 | |
154 int success_result = completely_empty; | |
155 int end_idx = _nodes.size()-1; | |
156 | |
157 // Check for ending goto | |
158 if ((end_idx > 0) && (_nodes[end_idx]->is_Goto())) { | |
159 success_result = empty_with_goto; | |
160 end_idx--; | |
161 } | |
162 | |
163 // Unreachable blocks are considered empty | |
164 if (num_preds() <= 1) { | |
165 return success_result; | |
166 } | |
167 | |
168 // Ideal nodes are allowable in empty blocks: skip them Only MachNodes | |
169 // turn directly into code, because only MachNodes have non-trivial | |
170 // emit() functions. | |
171 while ((end_idx > 0) && !_nodes[end_idx]->is_Mach()) { | |
172 end_idx--; | |
173 } | |
174 | |
175 // No room for any interesting instructions? | |
176 if (end_idx == 0) { | |
177 return success_result; | |
178 } | |
179 | |
180 return not_empty; | |
181 } | |
182 | |
183 //------------------------------has_uncommon_code------------------------------ | |
605 | 184 // Return true if the block's code implies that it is likely to be |
0 | 185 // executed infrequently. Check to see if the block ends in a Halt or |
186 // a low probability call. | |
187 bool Block::has_uncommon_code() const { | |
188 Node* en = end(); | |
189 | |
190 if (en->is_Goto()) | |
191 en = en->in(0); | |
192 if (en->is_Catch()) | |
193 en = en->in(0); | |
194 if (en->is_Proj() && en->in(0)->is_MachCall()) { | |
195 MachCallNode* call = en->in(0)->as_MachCall(); | |
196 if (call->cnt() != COUNT_UNKNOWN && call->cnt() <= PROB_UNLIKELY_MAG(4)) { | |
197 // This is true for slow-path stubs like new_{instance,array}, | |
198 // slow_arraycopy, complete_monitor_locking, uncommon_trap. | |
199 // The magic number corresponds to the probability of an uncommon_trap, | |
200 // even though it is a count not a probability. | |
201 return true; | |
202 } | |
203 } | |
204 | |
205 int op = en->is_Mach() ? en->as_Mach()->ideal_Opcode() : en->Opcode(); | |
206 return op == Op_Halt; | |
207 } | |
208 | |
209 //------------------------------is_uncommon------------------------------------ | |
210 // True if block is low enough frequency or guarded by a test which | |
211 // mostly does not go here. | |
212 bool Block::is_uncommon( Block_Array &bbs ) const { | |
213 // Initial blocks must never be moved, so are never uncommon. | |
214 if (head()->is_Root() || head()->is_Start()) return false; | |
215 | |
216 // Check for way-low freq | |
217 if( _freq < BLOCK_FREQUENCY(0.00001f) ) return true; | |
218 | |
219 // Look for code shape indicating uncommon_trap or slow path | |
220 if (has_uncommon_code()) return true; | |
221 | |
222 const float epsilon = 0.05f; | |
223 const float guard_factor = PROB_UNLIKELY_MAG(4) / (1.f - epsilon); | |
224 uint uncommon_preds = 0; | |
225 uint freq_preds = 0; | |
226 uint uncommon_for_freq_preds = 0; | |
227 | |
228 for( uint i=1; i<num_preds(); i++ ) { | |
229 Block* guard = bbs[pred(i)->_idx]; | |
230 // Check to see if this block follows its guard 1 time out of 10000 | |
231 // or less. | |
232 // | |
233 // See list of magnitude-4 unlikely probabilities in cfgnode.hpp which | |
234 // we intend to be "uncommon", such as slow-path TLE allocation, | |
235 // predicted call failure, and uncommon trap triggers. | |
236 // | |
237 // Use an epsilon value of 5% to allow for variability in frequency | |
238 // predictions and floating point calculations. The net effect is | |
239 // that guard_factor is set to 9500. | |
240 // | |
241 // Ignore low-frequency blocks. | |
242 // The next check is (guard->_freq < 1.e-5 * 9500.). | |
243 if(guard->_freq*BLOCK_FREQUENCY(guard_factor) < BLOCK_FREQUENCY(0.00001f)) { | |
244 uncommon_preds++; | |
245 } else { | |
246 freq_preds++; | |
247 if( _freq < guard->_freq * guard_factor ) { | |
248 uncommon_for_freq_preds++; | |
249 } | |
250 } | |
251 } | |
252 if( num_preds() > 1 && | |
253 // The block is uncommon if all preds are uncommon or | |
254 (uncommon_preds == (num_preds()-1) || | |
255 // it is uncommon for all frequent preds. | |
256 uncommon_for_freq_preds == freq_preds) ) { | |
257 return true; | |
258 } | |
259 return false; | |
260 } | |
261 | |
262 //------------------------------dump------------------------------------------- | |
263 #ifndef PRODUCT | |
264 void Block::dump_bidx(const Block* orig) const { | |
265 if (_pre_order) tty->print("B%d",_pre_order); | |
266 else tty->print("N%d", head()->_idx); | |
267 | |
268 if (Verbose && orig != this) { | |
269 // Dump the original block's idx | |
270 tty->print(" ("); | |
271 orig->dump_bidx(orig); | |
272 tty->print(")"); | |
273 } | |
274 } | |
275 | |
276 void Block::dump_pred(const Block_Array *bbs, Block* orig) const { | |
277 if (is_connector()) { | |
278 for (uint i=1; i<num_preds(); i++) { | |
279 Block *p = ((*bbs)[pred(i)->_idx]); | |
280 p->dump_pred(bbs, orig); | |
281 } | |
282 } else { | |
283 dump_bidx(orig); | |
284 tty->print(" "); | |
285 } | |
286 } | |
287 | |
288 void Block::dump_head( const Block_Array *bbs ) const { | |
289 // Print the basic block | |
290 dump_bidx(this); | |
291 tty->print(": #\t"); | |
292 | |
293 // Print the incoming CFG edges and the outgoing CFG edges | |
294 for( uint i=0; i<_num_succs; i++ ) { | |
295 non_connector_successor(i)->dump_bidx(_succs[i]); | |
296 tty->print(" "); | |
297 } | |
298 tty->print("<- "); | |
299 if( head()->is_block_start() ) { | |
300 for (uint i=1; i<num_preds(); i++) { | |
301 Node *s = pred(i); | |
302 if (bbs) { | |
303 Block *p = (*bbs)[s->_idx]; | |
304 p->dump_pred(bbs, p); | |
305 } else { | |
306 while (!s->is_block_start()) | |
307 s = s->in(0); | |
308 tty->print("N%d ", s->_idx ); | |
309 } | |
310 } | |
311 } else | |
312 tty->print("BLOCK HEAD IS JUNK "); | |
313 | |
314 // Print loop, if any | |
315 const Block *bhead = this; // Head of self-loop | |
316 Node *bh = bhead->head(); | |
317 if( bbs && bh->is_Loop() && !head()->is_Root() ) { | |
318 LoopNode *loop = bh->as_Loop(); | |
319 const Block *bx = (*bbs)[loop->in(LoopNode::LoopBackControl)->_idx]; | |
320 while (bx->is_connector()) { | |
321 bx = (*bbs)[bx->pred(1)->_idx]; | |
322 } | |
323 tty->print("\tLoop: B%d-B%d ", bhead->_pre_order, bx->_pre_order); | |
324 // Dump any loop-specific bits, especially for CountedLoops. | |
325 loop->dump_spec(tty); | |
418 | 326 } else if (has_loop_alignment()) { |
327 tty->print(" top-of-loop"); | |
0 | 328 } |
329 tty->print(" Freq: %g",_freq); | |
330 if( Verbose || WizardMode ) { | |
331 tty->print(" IDom: %d/#%d", _idom ? _idom->_pre_order : 0, _dom_depth); | |
332 tty->print(" RegPressure: %d",_reg_pressure); | |
333 tty->print(" IHRP Index: %d",_ihrp_index); | |
334 tty->print(" FRegPressure: %d",_freg_pressure); | |
335 tty->print(" FHRP Index: %d",_fhrp_index); | |
336 } | |
337 tty->print_cr(""); | |
338 } | |
339 | |
340 void Block::dump() const { dump(0); } | |
341 | |
342 void Block::dump( const Block_Array *bbs ) const { | |
343 dump_head(bbs); | |
344 uint cnt = _nodes.size(); | |
345 for( uint i=0; i<cnt; i++ ) | |
346 _nodes[i]->dump(); | |
347 tty->print("\n"); | |
348 } | |
349 #endif | |
350 | |
351 //============================================================================= | |
352 //------------------------------PhaseCFG--------------------------------------- | |
353 PhaseCFG::PhaseCFG( Arena *a, RootNode *r, Matcher &m ) : | |
354 Phase(CFG), | |
355 _bbs(a), | |
356 _root(r) | |
357 #ifndef PRODUCT | |
358 , _trace_opto_pipelining(TraceOptoPipelining || C->method_has_option("TraceOptoPipelining")) | |
359 #endif | |
833
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360 #ifdef ASSERT |
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361 , _raw_oops(a) |
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362 #endif |
0 | 363 { |
364 ResourceMark rm; | |
365 // I'll need a few machine-specific GotoNodes. Make an Ideal GotoNode, | |
366 // then Match it into a machine-specific Node. Then clone the machine | |
367 // Node on demand. | |
368 Node *x = new (C, 1) GotoNode(NULL); | |
369 x->init_req(0, x); | |
370 _goto = m.match_tree(x); | |
371 assert(_goto != NULL, ""); | |
372 _goto->set_req(0,_goto); | |
373 | |
374 // Build the CFG in Reverse Post Order | |
375 _num_blocks = build_cfg(); | |
376 _broot = _bbs[_root->_idx]; | |
377 } | |
378 | |
379 //------------------------------build_cfg-------------------------------------- | |
380 // Build a proper looking CFG. Make every block begin with either a StartNode | |
381 // or a RegionNode. Make every block end with either a Goto, If or Return. | |
382 // The RootNode both starts and ends it's own block. Do this with a recursive | |
383 // backwards walk over the control edges. | |
384 uint PhaseCFG::build_cfg() { | |
385 Arena *a = Thread::current()->resource_area(); | |
386 VectorSet visited(a); | |
387 | |
388 // Allocate stack with enough space to avoid frequent realloc | |
389 Node_Stack nstack(a, C->unique() >> 1); | |
390 nstack.push(_root, 0); | |
391 uint sum = 0; // Counter for blocks | |
392 | |
393 while (nstack.is_nonempty()) { | |
394 // node and in's index from stack's top | |
395 // 'np' is _root (see above) or RegionNode, StartNode: we push on stack | |
396 // only nodes which point to the start of basic block (see below). | |
397 Node *np = nstack.node(); | |
398 // idx > 0, except for the first node (_root) pushed on stack | |
399 // at the beginning when idx == 0. | |
400 // We will use the condition (idx == 0) later to end the build. | |
401 uint idx = nstack.index(); | |
402 Node *proj = np->in(idx); | |
403 const Node *x = proj->is_block_proj(); | |
404 // Does the block end with a proper block-ending Node? One of Return, | |
405 // If or Goto? (This check should be done for visited nodes also). | |
406 if (x == NULL) { // Does not end right... | |
407 Node *g = _goto->clone(); // Force it to end in a Goto | |
408 g->set_req(0, proj); | |
409 np->set_req(idx, g); | |
410 x = proj = g; | |
411 } | |
412 if (!visited.test_set(x->_idx)) { // Visit this block once | |
413 // Skip any control-pinned middle'in stuff | |
414 Node *p = proj; | |
415 do { | |
416 proj = p; // Update pointer to last Control | |
417 p = p->in(0); // Move control forward | |
418 } while( !p->is_block_proj() && | |
419 !p->is_block_start() ); | |
420 // Make the block begin with one of Region or StartNode. | |
421 if( !p->is_block_start() ) { | |
422 RegionNode *r = new (C, 2) RegionNode( 2 ); | |
423 r->init_req(1, p); // Insert RegionNode in the way | |
424 proj->set_req(0, r); // Insert RegionNode in the way | |
425 p = r; | |
426 } | |
427 // 'p' now points to the start of this basic block | |
428 | |
429 // Put self in array of basic blocks | |
430 Block *bb = new (_bbs._arena) Block(_bbs._arena,p); | |
431 _bbs.map(p->_idx,bb); | |
432 _bbs.map(x->_idx,bb); | |
433 if( x != p ) // Only for root is x == p | |
434 bb->_nodes.push((Node*)x); | |
435 | |
436 // Now handle predecessors | |
437 ++sum; // Count 1 for self block | |
438 uint cnt = bb->num_preds(); | |
439 for (int i = (cnt - 1); i > 0; i-- ) { // For all predecessors | |
440 Node *prevproj = p->in(i); // Get prior input | |
441 assert( !prevproj->is_Con(), "dead input not removed" ); | |
442 // Check to see if p->in(i) is a "control-dependent" CFG edge - | |
443 // i.e., it splits at the source (via an IF or SWITCH) and merges | |
444 // at the destination (via a many-input Region). | |
445 // This breaks critical edges. The RegionNode to start the block | |
446 // will be added when <p,i> is pulled off the node stack | |
447 if ( cnt > 2 ) { // Merging many things? | |
448 assert( prevproj== bb->pred(i),""); | |
449 if(prevproj->is_block_proj() != prevproj) { // Control-dependent edge? | |
450 // Force a block on the control-dependent edge | |
451 Node *g = _goto->clone(); // Force it to end in a Goto | |
452 g->set_req(0,prevproj); | |
453 p->set_req(i,g); | |
454 } | |
455 } | |
456 nstack.push(p, i); // 'p' is RegionNode or StartNode | |
457 } | |
458 } else { // Post-processing visited nodes | |
459 nstack.pop(); // remove node from stack | |
460 // Check if it the fist node pushed on stack at the beginning. | |
461 if (idx == 0) break; // end of the build | |
462 // Find predecessor basic block | |
463 Block *pb = _bbs[x->_idx]; | |
464 // Insert into nodes array, if not already there | |
465 if( !_bbs.lookup(proj->_idx) ) { | |
466 assert( x != proj, "" ); | |
467 // Map basic block of projection | |
468 _bbs.map(proj->_idx,pb); | |
469 pb->_nodes.push(proj); | |
470 } | |
471 // Insert self as a child of my predecessor block | |
472 pb->_succs.map(pb->_num_succs++, _bbs[np->_idx]); | |
473 assert( pb->_nodes[ pb->_nodes.size() - pb->_num_succs ]->is_block_proj(), | |
474 "too many control users, not a CFG?" ); | |
475 } | |
476 } | |
477 // Return number of basic blocks for all children and self | |
478 return sum; | |
479 } | |
480 | |
481 //------------------------------insert_goto_at--------------------------------- | |
482 // Inserts a goto & corresponding basic block between | |
483 // block[block_no] and its succ_no'th successor block | |
484 void PhaseCFG::insert_goto_at(uint block_no, uint succ_no) { | |
485 // get block with block_no | |
486 assert(block_no < _num_blocks, "illegal block number"); | |
487 Block* in = _blocks[block_no]; | |
488 // get successor block succ_no | |
489 assert(succ_no < in->_num_succs, "illegal successor number"); | |
490 Block* out = in->_succs[succ_no]; | |
308 | 491 // Compute frequency of the new block. Do this before inserting |
492 // new block in case succ_prob() needs to infer the probability from | |
493 // surrounding blocks. | |
494 float freq = in->_freq * in->succ_prob(succ_no); | |
0 | 495 // get ProjNode corresponding to the succ_no'th successor of the in block |
496 ProjNode* proj = in->_nodes[in->_nodes.size() - in->_num_succs + succ_no]->as_Proj(); | |
497 // create region for basic block | |
498 RegionNode* region = new (C, 2) RegionNode(2); | |
499 region->init_req(1, proj); | |
500 // setup corresponding basic block | |
501 Block* block = new (_bbs._arena) Block(_bbs._arena, region); | |
502 _bbs.map(region->_idx, block); | |
503 C->regalloc()->set_bad(region->_idx); | |
504 // add a goto node | |
505 Node* gto = _goto->clone(); // get a new goto node | |
506 gto->set_req(0, region); | |
507 // add it to the basic block | |
508 block->_nodes.push(gto); | |
509 _bbs.map(gto->_idx, block); | |
510 C->regalloc()->set_bad(gto->_idx); | |
511 // hook up successor block | |
512 block->_succs.map(block->_num_succs++, out); | |
513 // remap successor's predecessors if necessary | |
514 for (uint i = 1; i < out->num_preds(); i++) { | |
515 if (out->pred(i) == proj) out->head()->set_req(i, gto); | |
516 } | |
517 // remap predecessor's successor to new block | |
518 in->_succs.map(succ_no, block); | |
308 | 519 // Set the frequency of the new block |
520 block->_freq = freq; | |
0 | 521 // add new basic block to basic block list |
522 _blocks.insert(block_no + 1, block); | |
523 _num_blocks++; | |
524 } | |
525 | |
526 //------------------------------no_flip_branch--------------------------------- | |
527 // Does this block end in a multiway branch that cannot have the default case | |
528 // flipped for another case? | |
529 static bool no_flip_branch( Block *b ) { | |
530 int branch_idx = b->_nodes.size() - b->_num_succs-1; | |
531 if( branch_idx < 1 ) return false; | |
532 Node *bra = b->_nodes[branch_idx]; | |
418 | 533 if( bra->is_Catch() ) |
534 return true; | |
0 | 535 if( bra->is_Mach() ) { |
418 | 536 if( bra->is_MachNullCheck() ) |
537 return true; | |
0 | 538 int iop = bra->as_Mach()->ideal_Opcode(); |
539 if( iop == Op_FastLock || iop == Op_FastUnlock ) | |
540 return true; | |
541 } | |
542 return false; | |
543 } | |
544 | |
545 //------------------------------convert_NeverBranch_to_Goto-------------------- | |
546 // Check for NeverBranch at block end. This needs to become a GOTO to the | |
547 // true target. NeverBranch are treated as a conditional branch that always | |
548 // goes the same direction for most of the optimizer and are used to give a | |
549 // fake exit path to infinite loops. At this late stage they need to turn | |
550 // into Goto's so that when you enter the infinite loop you indeed hang. | |
551 void PhaseCFG::convert_NeverBranch_to_Goto(Block *b) { | |
552 // Find true target | |
553 int end_idx = b->end_idx(); | |
554 int idx = b->_nodes[end_idx+1]->as_Proj()->_con; | |
555 Block *succ = b->_succs[idx]; | |
556 Node* gto = _goto->clone(); // get a new goto node | |
557 gto->set_req(0, b->head()); | |
558 Node *bp = b->_nodes[end_idx]; | |
559 b->_nodes.map(end_idx,gto); // Slam over NeverBranch | |
560 _bbs.map(gto->_idx, b); | |
561 C->regalloc()->set_bad(gto->_idx); | |
562 b->_nodes.pop(); // Yank projections | |
563 b->_nodes.pop(); // Yank projections | |
564 b->_succs.map(0,succ); // Map only successor | |
565 b->_num_succs = 1; | |
566 // remap successor's predecessors if necessary | |
567 uint j; | |
568 for( j = 1; j < succ->num_preds(); j++) | |
569 if( succ->pred(j)->in(0) == bp ) | |
570 succ->head()->set_req(j, gto); | |
571 // Kill alternate exit path | |
572 Block *dead = b->_succs[1-idx]; | |
573 for( j = 1; j < dead->num_preds(); j++) | |
574 if( dead->pred(j)->in(0) == bp ) | |
575 break; | |
576 // Scan through block, yanking dead path from | |
577 // all regions and phis. | |
578 dead->head()->del_req(j); | |
579 for( int k = 1; dead->_nodes[k]->is_Phi(); k++ ) | |
580 dead->_nodes[k]->del_req(j); | |
581 } | |
582 | |
418 | 583 //------------------------------move_to_next----------------------------------- |
0 | 584 // Helper function to move block bx to the slot following b_index. Return |
585 // true if the move is successful, otherwise false | |
418 | 586 bool PhaseCFG::move_to_next(Block* bx, uint b_index) { |
0 | 587 if (bx == NULL) return false; |
588 | |
589 // Return false if bx is already scheduled. | |
590 uint bx_index = bx->_pre_order; | |
591 if ((bx_index <= b_index) && (_blocks[bx_index] == bx)) { | |
592 return false; | |
593 } | |
594 | |
595 // Find the current index of block bx on the block list | |
596 bx_index = b_index + 1; | |
597 while( bx_index < _num_blocks && _blocks[bx_index] != bx ) bx_index++; | |
598 assert(_blocks[bx_index] == bx, "block not found"); | |
599 | |
600 // If the previous block conditionally falls into bx, return false, | |
601 // because moving bx will create an extra jump. | |
602 for(uint k = 1; k < bx->num_preds(); k++ ) { | |
603 Block* pred = _bbs[bx->pred(k)->_idx]; | |
604 if (pred == _blocks[bx_index-1]) { | |
605 if (pred->_num_succs != 1) { | |
606 return false; | |
607 } | |
608 } | |
609 } | |
610 | |
611 // Reinsert bx just past block 'b' | |
612 _blocks.remove(bx_index); | |
613 _blocks.insert(b_index + 1, bx); | |
614 return true; | |
615 } | |
616 | |
418 | 617 //------------------------------move_to_end------------------------------------ |
0 | 618 // Move empty and uncommon blocks to the end. |
418 | 619 void PhaseCFG::move_to_end(Block *b, uint i) { |
0 | 620 int e = b->is_Empty(); |
621 if (e != Block::not_empty) { | |
622 if (e == Block::empty_with_goto) { | |
623 // Remove the goto, but leave the block. | |
624 b->_nodes.pop(); | |
625 } | |
626 // Mark this block as a connector block, which will cause it to be | |
627 // ignored in certain functions such as non_connector_successor(). | |
628 b->set_connector(); | |
629 } | |
630 // Move the empty block to the end, and don't recheck. | |
631 _blocks.remove(i); | |
632 _blocks.push(b); | |
633 } | |
634 | |
418 | 635 //---------------------------set_loop_alignment-------------------------------- |
636 // Set loop alignment for every block | |
637 void PhaseCFG::set_loop_alignment() { | |
638 uint last = _num_blocks; | |
639 assert( _blocks[0] == _broot, "" ); | |
640 | |
641 for (uint i = 1; i < last; i++ ) { | |
642 Block *b = _blocks[i]; | |
643 if (b->head()->is_Loop()) { | |
644 b->set_loop_alignment(b); | |
645 } | |
646 } | |
647 } | |
648 | |
649 //-----------------------------remove_empty------------------------------------ | |
650 // Make empty basic blocks to be "connector" blocks, Move uncommon blocks | |
651 // to the end. | |
652 void PhaseCFG::remove_empty() { | |
0 | 653 // Move uncommon blocks to the end |
654 uint last = _num_blocks; | |
655 assert( _blocks[0] == _broot, "" ); | |
418 | 656 |
657 for (uint i = 1; i < last; i++) { | |
0 | 658 Block *b = _blocks[i]; |
418 | 659 if (b->is_connector()) break; |
0 | 660 |
661 // Check for NeverBranch at block end. This needs to become a GOTO to the | |
662 // true target. NeverBranch are treated as a conditional branch that | |
663 // always goes the same direction for most of the optimizer and are used | |
664 // to give a fake exit path to infinite loops. At this late stage they | |
665 // need to turn into Goto's so that when you enter the infinite loop you | |
666 // indeed hang. | |
667 if( b->_nodes[b->end_idx()]->Opcode() == Op_NeverBranch ) | |
668 convert_NeverBranch_to_Goto(b); | |
669 | |
670 // Look for uncommon blocks and move to end. | |
418 | 671 if (!C->do_freq_based_layout()) { |
672 if( b->is_uncommon(_bbs) ) { | |
673 move_to_end(b, i); | |
674 last--; // No longer check for being uncommon! | |
675 if( no_flip_branch(b) ) { // Fall-thru case must follow? | |
676 b = _blocks[i]; // Find the fall-thru block | |
677 move_to_end(b, i); | |
678 last--; | |
679 } | |
680 i--; // backup block counter post-increment | |
0 | 681 } |
682 } | |
683 } | |
684 | |
418 | 685 // Move empty blocks to the end |
0 | 686 last = _num_blocks; |
418 | 687 for (uint i = 1; i < last; i++) { |
0 | 688 Block *b = _blocks[i]; |
418 | 689 if (b->is_Empty() != Block::not_empty) { |
690 move_to_end(b, i); | |
691 last--; | |
692 i--; | |
0 | 693 } |
694 } // End of for all blocks | |
418 | 695 } |
0 | 696 |
418 | 697 //-----------------------------fixup_flow-------------------------------------- |
698 // Fix up the final control flow for basic blocks. | |
699 void PhaseCFG::fixup_flow() { | |
0 | 700 // Fixup final control flow for the blocks. Remove jump-to-next |
701 // block. If neither arm of a IF follows the conditional branch, we | |
702 // have to add a second jump after the conditional. We place the | |
703 // TRUE branch target in succs[0] for both GOTOs and IFs. | |
418 | 704 for (uint i=0; i < _num_blocks; i++) { |
0 | 705 Block *b = _blocks[i]; |
706 b->_pre_order = i; // turn pre-order into block-index | |
707 | |
708 // Connector blocks need no further processing. | |
709 if (b->is_connector()) { | |
710 assert((i+1) == _num_blocks || _blocks[i+1]->is_connector(), | |
711 "All connector blocks should sink to the end"); | |
712 continue; | |
713 } | |
714 assert(b->is_Empty() != Block::completely_empty, | |
715 "Empty blocks should be connectors"); | |
716 | |
717 Block *bnext = (i < _num_blocks-1) ? _blocks[i+1] : NULL; | |
718 Block *bs0 = b->non_connector_successor(0); | |
719 | |
720 // Check for multi-way branches where I cannot negate the test to | |
721 // exchange the true and false targets. | |
722 if( no_flip_branch( b ) ) { | |
723 // Find fall through case - if must fall into its target | |
724 int branch_idx = b->_nodes.size() - b->_num_succs; | |
725 for (uint j2 = 0; j2 < b->_num_succs; j2++) { | |
726 const ProjNode* p = b->_nodes[branch_idx + j2]->as_Proj(); | |
727 if (p->_con == 0) { | |
728 // successor j2 is fall through case | |
729 if (b->non_connector_successor(j2) != bnext) { | |
730 // but it is not the next block => insert a goto | |
731 insert_goto_at(i, j2); | |
732 } | |
733 // Put taken branch in slot 0 | |
734 if( j2 == 0 && b->_num_succs == 2) { | |
735 // Flip targets in succs map | |
736 Block *tbs0 = b->_succs[0]; | |
737 Block *tbs1 = b->_succs[1]; | |
738 b->_succs.map( 0, tbs1 ); | |
739 b->_succs.map( 1, tbs0 ); | |
740 } | |
741 break; | |
742 } | |
743 } | |
744 // Remove all CatchProjs | |
418 | 745 for (uint j1 = 0; j1 < b->_num_succs; j1++) b->_nodes.pop(); |
0 | 746 |
747 } else if (b->_num_succs == 1) { | |
748 // Block ends in a Goto? | |
749 if (bnext == bs0) { | |
750 // We fall into next block; remove the Goto | |
751 b->_nodes.pop(); | |
752 } | |
753 | |
754 } else if( b->_num_succs == 2 ) { // Block ends in a If? | |
755 // Get opcode of 1st projection (matches _succs[0]) | |
756 // Note: Since this basic block has 2 exits, the last 2 nodes must | |
757 // be projections (in any order), the 3rd last node must be | |
758 // the IfNode (we have excluded other 2-way exits such as | |
759 // CatchNodes already). | |
760 MachNode *iff = b->_nodes[b->_nodes.size()-3]->as_Mach(); | |
761 ProjNode *proj0 = b->_nodes[b->_nodes.size()-2]->as_Proj(); | |
762 ProjNode *proj1 = b->_nodes[b->_nodes.size()-1]->as_Proj(); | |
763 | |
764 // Assert that proj0 and succs[0] match up. Similarly for proj1 and succs[1]. | |
765 assert(proj0->raw_out(0) == b->_succs[0]->head(), "Mismatch successor 0"); | |
766 assert(proj1->raw_out(0) == b->_succs[1]->head(), "Mismatch successor 1"); | |
767 | |
768 Block *bs1 = b->non_connector_successor(1); | |
769 | |
770 // Check for neither successor block following the current | |
771 // block ending in a conditional. If so, move one of the | |
772 // successors after the current one, provided that the | |
773 // successor was previously unscheduled, but moveable | |
774 // (i.e., all paths to it involve a branch). | |
418 | 775 if( !C->do_freq_based_layout() && bnext != bs0 && bnext != bs1 ) { |
0 | 776 // Choose the more common successor based on the probability |
777 // of the conditional branch. | |
778 Block *bx = bs0; | |
779 Block *by = bs1; | |
780 | |
781 // _prob is the probability of taking the true path. Make | |
782 // p the probability of taking successor #1. | |
783 float p = iff->as_MachIf()->_prob; | |
784 if( proj0->Opcode() == Op_IfTrue ) { | |
785 p = 1.0 - p; | |
786 } | |
787 | |
788 // Prefer successor #1 if p > 0.5 | |
789 if (p > PROB_FAIR) { | |
790 bx = bs1; | |
791 by = bs0; | |
792 } | |
793 | |
794 // Attempt the more common successor first | |
418 | 795 if (move_to_next(bx, i)) { |
0 | 796 bnext = bx; |
418 | 797 } else if (move_to_next(by, i)) { |
0 | 798 bnext = by; |
799 } | |
800 } | |
801 | |
802 // Check for conditional branching the wrong way. Negate | |
803 // conditional, if needed, so it falls into the following block | |
804 // and branches to the not-following block. | |
805 | |
806 // Check for the next block being in succs[0]. We are going to branch | |
807 // to succs[0], so we want the fall-thru case as the next block in | |
808 // succs[1]. | |
809 if (bnext == bs0) { | |
810 // Fall-thru case in succs[0], so flip targets in succs map | |
811 Block *tbs0 = b->_succs[0]; | |
812 Block *tbs1 = b->_succs[1]; | |
813 b->_succs.map( 0, tbs1 ); | |
814 b->_succs.map( 1, tbs0 ); | |
815 // Flip projection for each target | |
816 { ProjNode *tmp = proj0; proj0 = proj1; proj1 = tmp; } | |
817 | |
418 | 818 } else if( bnext != bs1 ) { |
819 // Need a double-branch | |
0 | 820 // The existing conditional branch need not change. |
821 // Add a unconditional branch to the false target. | |
822 // Alas, it must appear in its own block and adding a | |
823 // block this late in the game is complicated. Sigh. | |
824 insert_goto_at(i, 1); | |
825 } | |
826 | |
827 // Make sure we TRUE branch to the target | |
418 | 828 if( proj0->Opcode() == Op_IfFalse ) { |
0 | 829 iff->negate(); |
418 | 830 } |
0 | 831 |
832 b->_nodes.pop(); // Remove IfFalse & IfTrue projections | |
833 b->_nodes.pop(); | |
834 | |
835 } else { | |
836 // Multi-exit block, e.g. a switch statement | |
837 // But we don't need to do anything here | |
838 } | |
839 } // End of for all blocks | |
840 } | |
841 | |
842 | |
843 //------------------------------dump------------------------------------------- | |
844 #ifndef PRODUCT | |
845 void PhaseCFG::_dump_cfg( const Node *end, VectorSet &visited ) const { | |
846 const Node *x = end->is_block_proj(); | |
847 assert( x, "not a CFG" ); | |
848 | |
849 // Do not visit this block again | |
850 if( visited.test_set(x->_idx) ) return; | |
851 | |
852 // Skip through this block | |
853 const Node *p = x; | |
854 do { | |
855 p = p->in(0); // Move control forward | |
856 assert( !p->is_block_proj() || p->is_Root(), "not a CFG" ); | |
857 } while( !p->is_block_start() ); | |
858 | |
859 // Recursively visit | |
860 for( uint i=1; i<p->req(); i++ ) | |
861 _dump_cfg(p->in(i),visited); | |
862 | |
863 // Dump the block | |
864 _bbs[p->_idx]->dump(&_bbs); | |
865 } | |
866 | |
867 void PhaseCFG::dump( ) const { | |
868 tty->print("\n--- CFG --- %d BBs\n",_num_blocks); | |
869 if( _blocks.size() ) { // Did we do basic-block layout? | |
870 for( uint i=0; i<_num_blocks; i++ ) | |
871 _blocks[i]->dump(&_bbs); | |
872 } else { // Else do it with a DFS | |
873 VectorSet visited(_bbs._arena); | |
874 _dump_cfg(_root,visited); | |
875 } | |
876 } | |
877 | |
878 void PhaseCFG::dump_headers() { | |
879 for( uint i = 0; i < _num_blocks; i++ ) { | |
880 if( _blocks[i] == NULL ) continue; | |
881 _blocks[i]->dump_head(&_bbs); | |
882 } | |
883 } | |
884 | |
885 void PhaseCFG::verify( ) const { | |
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886 #ifdef ASSERT |
0 | 887 // Verify sane CFG |
888 for( uint i = 0; i < _num_blocks; i++ ) { | |
889 Block *b = _blocks[i]; | |
890 uint cnt = b->_nodes.size(); | |
891 uint j; | |
892 for( j = 0; j < cnt; j++ ) { | |
893 Node *n = b->_nodes[j]; | |
894 assert( _bbs[n->_idx] == b, "" ); | |
895 if( j >= 1 && n->is_Mach() && | |
896 n->as_Mach()->ideal_Opcode() == Op_CreateEx ) { | |
897 assert( j == 1 || b->_nodes[j-1]->is_Phi(), | |
898 "CreateEx must be first instruction in block" ); | |
899 } | |
900 for( uint k = 0; k < n->req(); k++ ) { | |
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901 Node *def = n->in(k); |
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902 if( def && def != n ) { |
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903 assert( _bbs[def->_idx] || def->is_Con(), |
0 | 904 "must have block; constants for debug info ok" ); |
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905 // Verify that instructions in the block is in correct order. |
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906 // Uses must follow their definition if they are at the same block. |
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907 // Mostly done to check that MachSpillCopy nodes are placed correctly |
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908 // when CreateEx node is moved in build_ifg_physical(). |
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909 if( _bbs[def->_idx] == b && |
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910 !(b->head()->is_Loop() && n->is_Phi()) && |
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911 // See (+++) comment in reg_split.cpp |
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912 !(n->jvms() != NULL && n->jvms()->is_monitor_use(k)) ) { |
893
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913 bool is_loop = false; |
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914 if (n->is_Phi()) { |
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915 for( uint l = 1; l < def->req(); l++ ) { |
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916 if (n == def->in(l)) { |
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917 is_loop = true; |
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918 break; // Some kind of loop |
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919 } |
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920 } |
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921 } |
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922 assert( is_loop || b->find_node(def) < j, "uses must follow definitions" ); |
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923 } |
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924 if( def->is_SafePointScalarObject() ) { |
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925 assert(_bbs[def->_idx] == b, "SafePointScalarObject Node should be at the same block as its SafePoint node"); |
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926 assert(_bbs[def->_idx] == _bbs[def->in(0)->_idx], "SafePointScalarObject Node should be at the same block as its control edge"); |
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927 } |
0 | 928 } |
929 } | |
930 } | |
931 | |
932 j = b->end_idx(); | |
933 Node *bp = (Node*)b->_nodes[b->_nodes.size()-1]->is_block_proj(); | |
934 assert( bp, "last instruction must be a block proj" ); | |
935 assert( bp == b->_nodes[j], "wrong number of successors for this block" ); | |
936 if( bp->is_Catch() ) { | |
937 while( b->_nodes[--j]->Opcode() == Op_MachProj ) ; | |
938 assert( b->_nodes[j]->is_Call(), "CatchProj must follow call" ); | |
939 } | |
940 else if( bp->is_Mach() && bp->as_Mach()->ideal_Opcode() == Op_If ) { | |
941 assert( b->_num_succs == 2, "Conditional branch must have two targets"); | |
942 } | |
943 } | |
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944 #endif |
0 | 945 } |
946 #endif | |
947 | |
948 //============================================================================= | |
949 //------------------------------UnionFind-------------------------------------- | |
950 UnionFind::UnionFind( uint max ) : _cnt(max), _max(max), _indices(NEW_RESOURCE_ARRAY(uint,max)) { | |
951 Copy::zero_to_bytes( _indices, sizeof(uint)*max ); | |
952 } | |
953 | |
954 void UnionFind::extend( uint from_idx, uint to_idx ) { | |
955 _nesting.check(); | |
956 if( from_idx >= _max ) { | |
957 uint size = 16; | |
958 while( size <= from_idx ) size <<=1; | |
959 _indices = REALLOC_RESOURCE_ARRAY( uint, _indices, _max, size ); | |
960 _max = size; | |
961 } | |
962 while( _cnt <= from_idx ) _indices[_cnt++] = 0; | |
963 _indices[from_idx] = to_idx; | |
964 } | |
965 | |
966 void UnionFind::reset( uint max ) { | |
967 assert( max <= max_uint, "Must fit within uint" ); | |
968 // Force the Union-Find mapping to be at least this large | |
969 extend(max,0); | |
970 // Initialize to be the ID mapping. | |
418 | 971 for( uint i=0; i<max; i++ ) map(i,i); |
0 | 972 } |
973 | |
974 //------------------------------Find_compress---------------------------------- | |
975 // Straight out of Tarjan's union-find algorithm | |
976 uint UnionFind::Find_compress( uint idx ) { | |
977 uint cur = idx; | |
978 uint next = lookup(cur); | |
979 while( next != cur ) { // Scan chain of equivalences | |
980 assert( next < cur, "always union smaller" ); | |
981 cur = next; // until find a fixed-point | |
982 next = lookup(cur); | |
983 } | |
984 // Core of union-find algorithm: update chain of | |
985 // equivalences to be equal to the root. | |
986 while( idx != next ) { | |
987 uint tmp = lookup(idx); | |
988 map(idx, next); | |
989 idx = tmp; | |
990 } | |
991 return idx; | |
992 } | |
993 | |
994 //------------------------------Find_const------------------------------------- | |
995 // Like Find above, but no path compress, so bad asymptotic behavior | |
996 uint UnionFind::Find_const( uint idx ) const { | |
997 if( idx == 0 ) return idx; // Ignore the zero idx | |
998 // Off the end? This can happen during debugging dumps | |
999 // when data structures have not finished being updated. | |
1000 if( idx >= _max ) return idx; | |
1001 uint next = lookup(idx); | |
1002 while( next != idx ) { // Scan chain of equivalences | |
1003 idx = next; // until find a fixed-point | |
1004 next = lookup(idx); | |
1005 } | |
1006 return next; | |
1007 } | |
1008 | |
1009 //------------------------------Union------------------------------------------ | |
1010 // union 2 sets together. | |
1011 void UnionFind::Union( uint idx1, uint idx2 ) { | |
1012 uint src = Find(idx1); | |
1013 uint dst = Find(idx2); | |
1014 assert( src, "" ); | |
1015 assert( dst, "" ); | |
1016 assert( src < _max, "oob" ); | |
1017 assert( dst < _max, "oob" ); | |
1018 assert( src < dst, "always union smaller" ); | |
1019 map(dst,src); | |
1020 } | |
418 | 1021 |
1022 #ifndef PRODUCT | |
1023 static void edge_dump(GrowableArray<CFGEdge *> *edges) { | |
1024 tty->print_cr("---- Edges ----"); | |
1025 for (int i = 0; i < edges->length(); i++) { | |
1026 CFGEdge *e = edges->at(i); | |
1027 if (e != NULL) { | |
1028 edges->at(i)->dump(); | |
1029 } | |
1030 } | |
1031 } | |
1032 | |
1033 static void trace_dump(Trace *traces[], int count) { | |
1034 tty->print_cr("---- Traces ----"); | |
1035 for (int i = 0; i < count; i++) { | |
1036 Trace *tr = traces[i]; | |
1037 if (tr != NULL) { | |
1038 tr->dump(); | |
1039 } | |
1040 } | |
1041 } | |
1042 | |
1043 void Trace::dump( ) const { | |
1044 tty->print_cr("Trace (freq %f)", first_block()->_freq); | |
1045 for (Block *b = first_block(); b != NULL; b = next(b)) { | |
1046 tty->print(" B%d", b->_pre_order); | |
1047 if (b->head()->is_Loop()) { | |
1048 tty->print(" (L%d)", b->compute_loop_alignment()); | |
1049 } | |
1050 if (b->has_loop_alignment()) { | |
1051 tty->print(" (T%d)", b->code_alignment()); | |
1052 } | |
1053 } | |
1054 tty->cr(); | |
1055 } | |
1056 | |
1057 void CFGEdge::dump( ) const { | |
1058 tty->print(" B%d --> B%d Freq: %f out:%3d%% in:%3d%% State: ", | |
1059 from()->_pre_order, to()->_pre_order, freq(), _from_pct, _to_pct); | |
1060 switch(state()) { | |
1061 case connected: | |
1062 tty->print("connected"); | |
1063 break; | |
1064 case open: | |
1065 tty->print("open"); | |
1066 break; | |
1067 case interior: | |
1068 tty->print("interior"); | |
1069 break; | |
1070 } | |
1071 if (infrequent()) { | |
1072 tty->print(" infrequent"); | |
1073 } | |
1074 tty->cr(); | |
1075 } | |
1076 #endif | |
1077 | |
1078 //============================================================================= | |
1079 | |
1080 //------------------------------edge_order------------------------------------- | |
1081 // Comparison function for edges | |
1082 static int edge_order(CFGEdge **e0, CFGEdge **e1) { | |
1083 float freq0 = (*e0)->freq(); | |
1084 float freq1 = (*e1)->freq(); | |
1085 if (freq0 != freq1) { | |
1086 return freq0 > freq1 ? -1 : 1; | |
1087 } | |
1088 | |
1089 int dist0 = (*e0)->to()->_rpo - (*e0)->from()->_rpo; | |
1090 int dist1 = (*e1)->to()->_rpo - (*e1)->from()->_rpo; | |
1091 | |
1092 return dist1 - dist0; | |
1093 } | |
1094 | |
1095 //------------------------------trace_frequency_order-------------------------- | |
1096 // Comparison function for edges | |
1097 static int trace_frequency_order(const void *p0, const void *p1) { | |
1098 Trace *tr0 = *(Trace **) p0; | |
1099 Trace *tr1 = *(Trace **) p1; | |
1100 Block *b0 = tr0->first_block(); | |
1101 Block *b1 = tr1->first_block(); | |
1102 | |
1103 // The trace of connector blocks goes at the end; | |
1104 // we only expect one such trace | |
1105 if (b0->is_connector() != b1->is_connector()) { | |
1106 return b1->is_connector() ? -1 : 1; | |
1107 } | |
1108 | |
1109 // Pull more frequently executed blocks to the beginning | |
1110 float freq0 = b0->_freq; | |
1111 float freq1 = b1->_freq; | |
1112 if (freq0 != freq1) { | |
1113 return freq0 > freq1 ? -1 : 1; | |
1114 } | |
1115 | |
1116 int diff = tr0->first_block()->_rpo - tr1->first_block()->_rpo; | |
1117 | |
1118 return diff; | |
1119 } | |
1120 | |
1121 //------------------------------find_edges------------------------------------- | |
1122 // Find edges of interest, i.e, those which can fall through. Presumes that | |
1123 // edges which don't fall through are of low frequency and can be generally | |
1124 // ignored. Initialize the list of traces. | |
1125 void PhaseBlockLayout::find_edges() | |
1126 { | |
1127 // Walk the blocks, creating edges and Traces | |
1128 uint i; | |
1129 Trace *tr = NULL; | |
1130 for (i = 0; i < _cfg._num_blocks; i++) { | |
1131 Block *b = _cfg._blocks[i]; | |
1132 tr = new Trace(b, next, prev); | |
1133 traces[tr->id()] = tr; | |
1134 | |
1135 // All connector blocks should be at the end of the list | |
1136 if (b->is_connector()) break; | |
1137 | |
1138 // If this block and the next one have a one-to-one successor | |
1139 // predecessor relationship, simply append the next block | |
1140 int nfallthru = b->num_fall_throughs(); | |
1141 while (nfallthru == 1 && | |
1142 b->succ_fall_through(0)) { | |
1143 Block *n = b->_succs[0]; | |
1144 | |
1145 // Skip over single-entry connector blocks, we don't want to | |
1146 // add them to the trace. | |
1147 while (n->is_connector() && n->num_preds() == 1) { | |
1148 n = n->_succs[0]; | |
1149 } | |
1150 | |
1151 // We see a merge point, so stop search for the next block | |
1152 if (n->num_preds() != 1) break; | |
1153 | |
1154 i++; | |
1155 assert(n = _cfg._blocks[i], "expecting next block"); | |
1156 tr->append(n); | |
1157 uf->map(n->_pre_order, tr->id()); | |
1158 traces[n->_pre_order] = NULL; | |
1159 nfallthru = b->num_fall_throughs(); | |
1160 b = n; | |
1161 } | |
1162 | |
1163 if (nfallthru > 0) { | |
1164 // Create a CFGEdge for each outgoing | |
1165 // edge that could be a fall-through. | |
1166 for (uint j = 0; j < b->_num_succs; j++ ) { | |
1167 if (b->succ_fall_through(j)) { | |
1168 Block *target = b->non_connector_successor(j); | |
1169 float freq = b->_freq * b->succ_prob(j); | |
1170 int from_pct = (int) ((100 * freq) / b->_freq); | |
1171 int to_pct = (int) ((100 * freq) / target->_freq); | |
1172 edges->append(new CFGEdge(b, target, freq, from_pct, to_pct)); | |
1173 } | |
1174 } | |
1175 } | |
1176 } | |
1177 | |
1178 // Group connector blocks into one trace | |
1179 for (i++; i < _cfg._num_blocks; i++) { | |
1180 Block *b = _cfg._blocks[i]; | |
1181 assert(b->is_connector(), "connector blocks at the end"); | |
1182 tr->append(b); | |
1183 uf->map(b->_pre_order, tr->id()); | |
1184 traces[b->_pre_order] = NULL; | |
1185 } | |
1186 } | |
1187 | |
1188 //------------------------------union_traces---------------------------------- | |
1189 // Union two traces together in uf, and null out the trace in the list | |
1190 void PhaseBlockLayout::union_traces(Trace* updated_trace, Trace* old_trace) | |
1191 { | |
1192 uint old_id = old_trace->id(); | |
1193 uint updated_id = updated_trace->id(); | |
1194 | |
1195 uint lo_id = updated_id; | |
1196 uint hi_id = old_id; | |
1197 | |
1198 // If from is greater than to, swap values to meet | |
1199 // UnionFind guarantee. | |
1200 if (updated_id > old_id) { | |
1201 lo_id = old_id; | |
1202 hi_id = updated_id; | |
1203 | |
1204 // Fix up the trace ids | |
1205 traces[lo_id] = traces[updated_id]; | |
1206 updated_trace->set_id(lo_id); | |
1207 } | |
1208 | |
1209 // Union the lower with the higher and remove the pointer | |
1210 // to the higher. | |
1211 uf->Union(lo_id, hi_id); | |
1212 traces[hi_id] = NULL; | |
1213 } | |
1214 | |
1215 //------------------------------grow_traces------------------------------------- | |
1216 // Append traces together via the most frequently executed edges | |
1217 void PhaseBlockLayout::grow_traces() | |
1218 { | |
1219 // Order the edges, and drive the growth of Traces via the most | |
1220 // frequently executed edges. | |
1221 edges->sort(edge_order); | |
1222 for (int i = 0; i < edges->length(); i++) { | |
1223 CFGEdge *e = edges->at(i); | |
1224 | |
1225 if (e->state() != CFGEdge::open) continue; | |
1226 | |
1227 Block *src_block = e->from(); | |
1228 Block *targ_block = e->to(); | |
1229 | |
1230 // Don't grow traces along backedges? | |
1231 if (!BlockLayoutRotateLoops) { | |
1232 if (targ_block->_rpo <= src_block->_rpo) { | |
1233 targ_block->set_loop_alignment(targ_block); | |
1234 continue; | |
1235 } | |
1236 } | |
1237 | |
1238 Trace *src_trace = trace(src_block); | |
1239 Trace *targ_trace = trace(targ_block); | |
1240 | |
1241 // If the edge in question can join two traces at their ends, | |
1242 // append one trace to the other. | |
1243 if (src_trace->last_block() == src_block) { | |
1244 if (src_trace == targ_trace) { | |
1245 e->set_state(CFGEdge::interior); | |
1246 if (targ_trace->backedge(e)) { | |
1247 // Reset i to catch any newly eligible edge | |
1248 // (Or we could remember the first "open" edge, and reset there) | |
1249 i = 0; | |
1250 } | |
1251 } else if (targ_trace->first_block() == targ_block) { | |
1252 e->set_state(CFGEdge::connected); | |
1253 src_trace->append(targ_trace); | |
1254 union_traces(src_trace, targ_trace); | |
1255 } | |
1256 } | |
1257 } | |
1258 } | |
1259 | |
1260 //------------------------------merge_traces----------------------------------- | |
1261 // Embed one trace into another, if the fork or join points are sufficiently | |
1262 // balanced. | |
1263 void PhaseBlockLayout::merge_traces(bool fall_thru_only) | |
1264 { | |
1265 // Walk the edge list a another time, looking at unprocessed edges. | |
1266 // Fold in diamonds | |
1267 for (int i = 0; i < edges->length(); i++) { | |
1268 CFGEdge *e = edges->at(i); | |
1269 | |
1270 if (e->state() != CFGEdge::open) continue; | |
1271 if (fall_thru_only) { | |
1272 if (e->infrequent()) continue; | |
1273 } | |
1274 | |
1275 Block *src_block = e->from(); | |
1276 Trace *src_trace = trace(src_block); | |
1277 bool src_at_tail = src_trace->last_block() == src_block; | |
1278 | |
1279 Block *targ_block = e->to(); | |
1280 Trace *targ_trace = trace(targ_block); | |
1281 bool targ_at_start = targ_trace->first_block() == targ_block; | |
1282 | |
1283 if (src_trace == targ_trace) { | |
1284 // This may be a loop, but we can't do much about it. | |
1285 e->set_state(CFGEdge::interior); | |
1286 continue; | |
1287 } | |
1288 | |
1289 if (fall_thru_only) { | |
1290 // If the edge links the middle of two traces, we can't do anything. | |
1291 // Mark the edge and continue. | |
1292 if (!src_at_tail & !targ_at_start) { | |
1293 continue; | |
1294 } | |
1295 | |
1296 // Don't grow traces along backedges? | |
1297 if (!BlockLayoutRotateLoops && (targ_block->_rpo <= src_block->_rpo)) { | |
1298 continue; | |
1299 } | |
1300 | |
1301 // If both ends of the edge are available, why didn't we handle it earlier? | |
1302 assert(src_at_tail ^ targ_at_start, "Should have caught this edge earlier."); | |
1303 | |
1304 if (targ_at_start) { | |
1305 // Insert the "targ" trace in the "src" trace if the insertion point | |
1306 // is a two way branch. | |
1307 // Better profitability check possible, but may not be worth it. | |
1308 // Someday, see if the this "fork" has an associated "join"; | |
1309 // then make a policy on merging this trace at the fork or join. | |
1310 // For example, other things being equal, it may be better to place this | |
1311 // trace at the join point if the "src" trace ends in a two-way, but | |
1312 // the insertion point is one-way. | |
1313 assert(src_block->num_fall_throughs() == 2, "unexpected diamond"); | |
1314 e->set_state(CFGEdge::connected); | |
1315 src_trace->insert_after(src_block, targ_trace); | |
1316 union_traces(src_trace, targ_trace); | |
1317 } else if (src_at_tail) { | |
1318 if (src_trace != trace(_cfg._broot)) { | |
1319 e->set_state(CFGEdge::connected); | |
1320 targ_trace->insert_before(targ_block, src_trace); | |
1321 union_traces(targ_trace, src_trace); | |
1322 } | |
1323 } | |
1324 } else if (e->state() == CFGEdge::open) { | |
1325 // Append traces, even without a fall-thru connection. | |
605 | 1326 // But leave root entry at the beginning of the block list. |
418 | 1327 if (targ_trace != trace(_cfg._broot)) { |
1328 e->set_state(CFGEdge::connected); | |
1329 src_trace->append(targ_trace); | |
1330 union_traces(src_trace, targ_trace); | |
1331 } | |
1332 } | |
1333 } | |
1334 } | |
1335 | |
1336 //----------------------------reorder_traces----------------------------------- | |
1337 // Order the sequence of the traces in some desirable way, and fixup the | |
1338 // jumps at the end of each block. | |
1339 void PhaseBlockLayout::reorder_traces(int count) | |
1340 { | |
1341 ResourceArea *area = Thread::current()->resource_area(); | |
1342 Trace ** new_traces = NEW_ARENA_ARRAY(area, Trace *, count); | |
1343 Block_List worklist; | |
1344 int new_count = 0; | |
1345 | |
1346 // Compact the traces. | |
1347 for (int i = 0; i < count; i++) { | |
1348 Trace *tr = traces[i]; | |
1349 if (tr != NULL) { | |
1350 new_traces[new_count++] = tr; | |
1351 } | |
1352 } | |
1353 | |
1354 // The entry block should be first on the new trace list. | |
1355 Trace *tr = trace(_cfg._broot); | |
1356 assert(tr == new_traces[0], "entry trace misplaced"); | |
1357 | |
1358 // Sort the new trace list by frequency | |
1359 qsort(new_traces + 1, new_count - 1, sizeof(new_traces[0]), trace_frequency_order); | |
1360 | |
1361 // Patch up the successor blocks | |
1362 _cfg._blocks.reset(); | |
1363 _cfg._num_blocks = 0; | |
1364 for (int i = 0; i < new_count; i++) { | |
1365 Trace *tr = new_traces[i]; | |
1366 if (tr != NULL) { | |
1367 tr->fixup_blocks(_cfg); | |
1368 } | |
1369 } | |
1370 } | |
1371 | |
1372 //------------------------------PhaseBlockLayout------------------------------- | |
1373 // Order basic blocks based on frequency | |
1374 PhaseBlockLayout::PhaseBlockLayout(PhaseCFG &cfg) : | |
1375 Phase(BlockLayout), | |
1376 _cfg(cfg) | |
1377 { | |
1378 ResourceMark rm; | |
1379 ResourceArea *area = Thread::current()->resource_area(); | |
1380 | |
1381 // List of traces | |
1382 int size = _cfg._num_blocks + 1; | |
1383 traces = NEW_ARENA_ARRAY(area, Trace *, size); | |
1384 memset(traces, 0, size*sizeof(Trace*)); | |
1385 next = NEW_ARENA_ARRAY(area, Block *, size); | |
1386 memset(next, 0, size*sizeof(Block *)); | |
1387 prev = NEW_ARENA_ARRAY(area, Block *, size); | |
1388 memset(prev , 0, size*sizeof(Block *)); | |
1389 | |
1390 // List of edges | |
1391 edges = new GrowableArray<CFGEdge*>; | |
1392 | |
1393 // Mapping block index --> block_trace | |
1394 uf = new UnionFind(size); | |
1395 uf->reset(size); | |
1396 | |
1397 // Find edges and create traces. | |
1398 find_edges(); | |
1399 | |
1400 // Grow traces at their ends via most frequent edges. | |
1401 grow_traces(); | |
1402 | |
1403 // Merge one trace into another, but only at fall-through points. | |
1404 // This may make diamonds and other related shapes in a trace. | |
1405 merge_traces(true); | |
1406 | |
1407 // Run merge again, allowing two traces to be catenated, even if | |
1408 // one does not fall through into the other. This appends loosely | |
1409 // related traces to be near each other. | |
1410 merge_traces(false); | |
1411 | |
1412 // Re-order all the remaining traces by frequency | |
1413 reorder_traces(size); | |
1414 | |
1415 assert(_cfg._num_blocks >= (uint) (size - 1), "number of blocks can not shrink"); | |
1416 } | |
1417 | |
1418 | |
1419 //------------------------------backedge--------------------------------------- | |
1420 // Edge e completes a loop in a trace. If the target block is head of the | |
1421 // loop, rotate the loop block so that the loop ends in a conditional branch. | |
1422 bool Trace::backedge(CFGEdge *e) { | |
1423 bool loop_rotated = false; | |
1424 Block *src_block = e->from(); | |
1425 Block *targ_block = e->to(); | |
1426 | |
1427 assert(last_block() == src_block, "loop discovery at back branch"); | |
1428 if (first_block() == targ_block) { | |
1429 if (BlockLayoutRotateLoops && last_block()->num_fall_throughs() < 2) { | |
1430 // Find the last block in the trace that has a conditional | |
1431 // branch. | |
1432 Block *b; | |
1433 for (b = last_block(); b != NULL; b = prev(b)) { | |
1434 if (b->num_fall_throughs() == 2) { | |
1435 break; | |
1436 } | |
1437 } | |
1438 | |
1439 if (b != last_block() && b != NULL) { | |
1440 loop_rotated = true; | |
1441 | |
1442 // Rotate the loop by doing two-part linked-list surgery. | |
1443 append(first_block()); | |
1444 break_loop_after(b); | |
1445 } | |
1446 } | |
1447 | |
1448 // Backbranch to the top of a trace | |
605 | 1449 // Scroll forward through the trace from the targ_block. If we find |
418 | 1450 // a loop head before another loop top, use the the loop head alignment. |
1451 for (Block *b = targ_block; b != NULL; b = next(b)) { | |
1452 if (b->has_loop_alignment()) { | |
1453 break; | |
1454 } | |
1455 if (b->head()->is_Loop()) { | |
1456 targ_block = b; | |
1457 break; | |
1458 } | |
1459 } | |
1460 | |
1461 first_block()->set_loop_alignment(targ_block); | |
1462 | |
1463 } else { | |
1464 // Backbranch into the middle of a trace | |
1465 targ_block->set_loop_alignment(targ_block); | |
1466 } | |
1467 | |
1468 return loop_rotated; | |
1469 } | |
1470 | |
1471 //------------------------------fixup_blocks----------------------------------- | |
1472 // push blocks onto the CFG list | |
1473 // ensure that blocks have the correct two-way branch sense | |
1474 void Trace::fixup_blocks(PhaseCFG &cfg) { | |
1475 Block *last = last_block(); | |
1476 for (Block *b = first_block(); b != NULL; b = next(b)) { | |
1477 cfg._blocks.push(b); | |
1478 cfg._num_blocks++; | |
1479 if (!b->is_connector()) { | |
1480 int nfallthru = b->num_fall_throughs(); | |
1481 if (b != last) { | |
1482 if (nfallthru == 2) { | |
1483 // Ensure that the sense of the branch is correct | |
1484 Block *bnext = next(b); | |
1485 Block *bs0 = b->non_connector_successor(0); | |
1486 | |
1487 MachNode *iff = b->_nodes[b->_nodes.size()-3]->as_Mach(); | |
1488 ProjNode *proj0 = b->_nodes[b->_nodes.size()-2]->as_Proj(); | |
1489 ProjNode *proj1 = b->_nodes[b->_nodes.size()-1]->as_Proj(); | |
1490 | |
1491 if (bnext == bs0) { | |
1492 // Fall-thru case in succs[0], should be in succs[1] | |
1493 | |
1494 // Flip targets in _succs map | |
1495 Block *tbs0 = b->_succs[0]; | |
1496 Block *tbs1 = b->_succs[1]; | |
1497 b->_succs.map( 0, tbs1 ); | |
1498 b->_succs.map( 1, tbs0 ); | |
1499 | |
1500 // Flip projections to match targets | |
1501 b->_nodes.map(b->_nodes.size()-2, proj1); | |
1502 b->_nodes.map(b->_nodes.size()-1, proj0); | |
1503 } | |
1504 } | |
1505 } | |
1506 } | |
1507 } | |
1508 } |