Mercurial > hg > truffle
annotate src/share/vm/opto/block.cpp @ 3518:0ffcce571d09
Remove a Sysout debug message
author | Gilles Duboscq <gilles.duboscq@oracle.com> |
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date | Tue, 09 Aug 2011 13:48:46 +0200 |
parents | f95d63e2154a |
children | c7b60b601eb4 |
rev | line source |
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0 | 1 /* |
1972 | 2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. 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 * | |
1552
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "libadt/vectset.hpp" | |
27 #include "memory/allocation.inline.hpp" | |
28 #include "opto/block.hpp" | |
29 #include "opto/cfgnode.hpp" | |
30 #include "opto/chaitin.hpp" | |
31 #include "opto/loopnode.hpp" | |
32 #include "opto/machnode.hpp" | |
33 #include "opto/matcher.hpp" | |
34 #include "opto/opcodes.hpp" | |
35 #include "opto/rootnode.hpp" | |
36 #include "utilities/copy.hpp" | |
0 | 37 |
1972 | 38 // Optimization - Graph Style |
0 | 39 |
40 | |
41 //----------------------------------------------------------------------------- | |
42 void Block_Array::grow( uint i ) { | |
43 assert(i >= Max(), "must be an overflow"); | |
44 debug_only(_limit = i+1); | |
45 if( i < _size ) return; | |
46 if( !_size ) { | |
47 _size = 1; | |
48 _blocks = (Block**)_arena->Amalloc( _size * sizeof(Block*) ); | |
49 _blocks[0] = NULL; | |
50 } | |
51 uint old = _size; | |
52 while( i >= _size ) _size <<= 1; // Double to fit | |
53 _blocks = (Block**)_arena->Arealloc( _blocks, old*sizeof(Block*),_size*sizeof(Block*)); | |
54 Copy::zero_to_bytes( &_blocks[old], (_size-old)*sizeof(Block*) ); | |
55 } | |
56 | |
57 //============================================================================= | |
58 void Block_List::remove(uint i) { | |
59 assert(i < _cnt, "index out of bounds"); | |
60 Copy::conjoint_words_to_lower((HeapWord*)&_blocks[i+1], (HeapWord*)&_blocks[i], ((_cnt-i-1)*sizeof(Block*))); | |
61 pop(); // shrink list by one block | |
62 } | |
63 | |
64 void Block_List::insert(uint i, Block *b) { | |
65 push(b); // grow list by one block | |
66 Copy::conjoint_words_to_higher((HeapWord*)&_blocks[i], (HeapWord*)&_blocks[i+1], ((_cnt-i-1)*sizeof(Block*))); | |
67 _blocks[i] = b; | |
68 } | |
69 | |
418 | 70 #ifndef PRODUCT |
71 void Block_List::print() { | |
72 for (uint i=0; i < size(); i++) { | |
73 tty->print("B%d ", _blocks[i]->_pre_order); | |
74 } | |
75 tty->print("size = %d\n", size()); | |
76 } | |
77 #endif | |
0 | 78 |
79 //============================================================================= | |
80 | |
81 uint Block::code_alignment() { | |
82 // Check for Root block | |
83 if( _pre_order == 0 ) return CodeEntryAlignment; | |
84 // Check for Start block | |
85 if( _pre_order == 1 ) return InteriorEntryAlignment; | |
86 // Check for loop alignment | |
418 | 87 if (has_loop_alignment()) return loop_alignment(); |
88 | |
89 return 1; // no particular alignment | |
90 } | |
91 | |
92 uint Block::compute_loop_alignment() { | |
0 | 93 Node *h = head(); |
94 if( h->is_Loop() && h->as_Loop()->is_inner_loop() ) { | |
95 // Pre- and post-loops have low trip count so do not bother with | |
96 // NOPs for align loop head. The constants are hidden from tuning | |
97 // but only because my "divide by 4" heuristic surely gets nearly | |
98 // all possible gain (a "do not align at all" heuristic has a | |
99 // chance of getting a really tiny gain). | |
100 if( h->is_CountedLoop() && (h->as_CountedLoop()->is_pre_loop() || | |
101 h->as_CountedLoop()->is_post_loop()) ) | |
102 return (OptoLoopAlignment > 4) ? (OptoLoopAlignment>>2) : 1; | |
103 // Loops with low backedge frequency should not be aligned. | |
104 Node *n = h->in(LoopNode::LoopBackControl)->in(0); | |
105 if( n->is_MachIf() && n->as_MachIf()->_prob < 0.01 ) { | |
106 return 1; // Loop does not loop, more often than not! | |
107 } | |
108 return OptoLoopAlignment; // Otherwise align loop head | |
109 } | |
418 | 110 |
0 | 111 return 1; // no particular alignment |
112 } | |
113 | |
114 //----------------------------------------------------------------------------- | |
115 // Compute the size of first 'inst_cnt' instructions in this block. | |
116 // Return the number of instructions left to compute if the block has | |
418 | 117 // less then 'inst_cnt' instructions. Stop, and return 0 if sum_size |
118 // exceeds OptoLoopAlignment. | |
0 | 119 uint Block::compute_first_inst_size(uint& sum_size, uint inst_cnt, |
120 PhaseRegAlloc* ra) { | |
121 uint last_inst = _nodes.size(); | |
122 for( uint j = 0; j < last_inst && inst_cnt > 0; j++ ) { | |
123 uint inst_size = _nodes[j]->size(ra); | |
124 if( inst_size > 0 ) { | |
125 inst_cnt--; | |
126 uint sz = sum_size + inst_size; | |
127 if( sz <= (uint)OptoLoopAlignment ) { | |
128 // Compute size of instructions which fit into fetch buffer only | |
129 // since all inst_cnt instructions will not fit even if we align them. | |
130 sum_size = sz; | |
131 } else { | |
132 return 0; | |
133 } | |
134 } | |
135 } | |
136 return inst_cnt; | |
137 } | |
138 | |
139 //----------------------------------------------------------------------------- | |
140 uint Block::find_node( const Node *n ) const { | |
141 for( uint i = 0; i < _nodes.size(); i++ ) { | |
142 if( _nodes[i] == n ) | |
143 return i; | |
144 } | |
145 ShouldNotReachHere(); | |
146 return 0; | |
147 } | |
148 | |
149 // Find and remove n from block list | |
150 void Block::find_remove( const Node *n ) { | |
151 _nodes.remove(find_node(n)); | |
152 } | |
153 | |
154 //------------------------------is_Empty--------------------------------------- | |
155 // Return empty status of a block. Empty blocks contain only the head, other | |
156 // ideal nodes, and an optional trailing goto. | |
157 int Block::is_Empty() const { | |
158 | |
159 // Root or start block is not considered empty | |
160 if (head()->is_Root() || head()->is_Start()) { | |
161 return not_empty; | |
162 } | |
163 | |
164 int success_result = completely_empty; | |
165 int end_idx = _nodes.size()-1; | |
166 | |
167 // Check for ending goto | |
168 if ((end_idx > 0) && (_nodes[end_idx]->is_Goto())) { | |
169 success_result = empty_with_goto; | |
170 end_idx--; | |
171 } | |
172 | |
173 // Unreachable blocks are considered empty | |
174 if (num_preds() <= 1) { | |
175 return success_result; | |
176 } | |
177 | |
178 // Ideal nodes are allowable in empty blocks: skip them Only MachNodes | |
179 // turn directly into code, because only MachNodes have non-trivial | |
180 // emit() functions. | |
181 while ((end_idx > 0) && !_nodes[end_idx]->is_Mach()) { | |
182 end_idx--; | |
183 } | |
184 | |
185 // No room for any interesting instructions? | |
186 if (end_idx == 0) { | |
187 return success_result; | |
188 } | |
189 | |
190 return not_empty; | |
191 } | |
192 | |
193 //------------------------------has_uncommon_code------------------------------ | |
605 | 194 // Return true if the block's code implies that it is likely to be |
0 | 195 // executed infrequently. Check to see if the block ends in a Halt or |
196 // a low probability call. | |
197 bool Block::has_uncommon_code() const { | |
198 Node* en = end(); | |
199 | |
200 if (en->is_Goto()) | |
201 en = en->in(0); | |
202 if (en->is_Catch()) | |
203 en = en->in(0); | |
204 if (en->is_Proj() && en->in(0)->is_MachCall()) { | |
205 MachCallNode* call = en->in(0)->as_MachCall(); | |
206 if (call->cnt() != COUNT_UNKNOWN && call->cnt() <= PROB_UNLIKELY_MAG(4)) { | |
207 // This is true for slow-path stubs like new_{instance,array}, | |
208 // slow_arraycopy, complete_monitor_locking, uncommon_trap. | |
209 // The magic number corresponds to the probability of an uncommon_trap, | |
210 // even though it is a count not a probability. | |
211 return true; | |
212 } | |
213 } | |
214 | |
215 int op = en->is_Mach() ? en->as_Mach()->ideal_Opcode() : en->Opcode(); | |
216 return op == Op_Halt; | |
217 } | |
218 | |
219 //------------------------------is_uncommon------------------------------------ | |
220 // True if block is low enough frequency or guarded by a test which | |
221 // mostly does not go here. | |
222 bool Block::is_uncommon( Block_Array &bbs ) const { | |
223 // Initial blocks must never be moved, so are never uncommon. | |
224 if (head()->is_Root() || head()->is_Start()) return false; | |
225 | |
226 // Check for way-low freq | |
227 if( _freq < BLOCK_FREQUENCY(0.00001f) ) return true; | |
228 | |
229 // Look for code shape indicating uncommon_trap or slow path | |
230 if (has_uncommon_code()) return true; | |
231 | |
232 const float epsilon = 0.05f; | |
233 const float guard_factor = PROB_UNLIKELY_MAG(4) / (1.f - epsilon); | |
234 uint uncommon_preds = 0; | |
235 uint freq_preds = 0; | |
236 uint uncommon_for_freq_preds = 0; | |
237 | |
238 for( uint i=1; i<num_preds(); i++ ) { | |
239 Block* guard = bbs[pred(i)->_idx]; | |
240 // Check to see if this block follows its guard 1 time out of 10000 | |
241 // or less. | |
242 // | |
243 // See list of magnitude-4 unlikely probabilities in cfgnode.hpp which | |
244 // we intend to be "uncommon", such as slow-path TLE allocation, | |
245 // predicted call failure, and uncommon trap triggers. | |
246 // | |
247 // Use an epsilon value of 5% to allow for variability in frequency | |
248 // predictions and floating point calculations. The net effect is | |
249 // that guard_factor is set to 9500. | |
250 // | |
251 // Ignore low-frequency blocks. | |
252 // The next check is (guard->_freq < 1.e-5 * 9500.). | |
253 if(guard->_freq*BLOCK_FREQUENCY(guard_factor) < BLOCK_FREQUENCY(0.00001f)) { | |
254 uncommon_preds++; | |
255 } else { | |
256 freq_preds++; | |
257 if( _freq < guard->_freq * guard_factor ) { | |
258 uncommon_for_freq_preds++; | |
259 } | |
260 } | |
261 } | |
262 if( num_preds() > 1 && | |
263 // The block is uncommon if all preds are uncommon or | |
264 (uncommon_preds == (num_preds()-1) || | |
265 // it is uncommon for all frequent preds. | |
266 uncommon_for_freq_preds == freq_preds) ) { | |
267 return true; | |
268 } | |
269 return false; | |
270 } | |
271 | |
272 //------------------------------dump------------------------------------------- | |
273 #ifndef PRODUCT | |
274 void Block::dump_bidx(const Block* orig) const { | |
275 if (_pre_order) tty->print("B%d",_pre_order); | |
276 else tty->print("N%d", head()->_idx); | |
277 | |
278 if (Verbose && orig != this) { | |
279 // Dump the original block's idx | |
280 tty->print(" ("); | |
281 orig->dump_bidx(orig); | |
282 tty->print(")"); | |
283 } | |
284 } | |
285 | |
286 void Block::dump_pred(const Block_Array *bbs, Block* orig) const { | |
287 if (is_connector()) { | |
288 for (uint i=1; i<num_preds(); i++) { | |
289 Block *p = ((*bbs)[pred(i)->_idx]); | |
290 p->dump_pred(bbs, orig); | |
291 } | |
292 } else { | |
293 dump_bidx(orig); | |
294 tty->print(" "); | |
295 } | |
296 } | |
297 | |
298 void Block::dump_head( const Block_Array *bbs ) const { | |
299 // Print the basic block | |
300 dump_bidx(this); | |
301 tty->print(": #\t"); | |
302 | |
303 // Print the incoming CFG edges and the outgoing CFG edges | |
304 for( uint i=0; i<_num_succs; i++ ) { | |
305 non_connector_successor(i)->dump_bidx(_succs[i]); | |
306 tty->print(" "); | |
307 } | |
308 tty->print("<- "); | |
309 if( head()->is_block_start() ) { | |
310 for (uint i=1; i<num_preds(); i++) { | |
311 Node *s = pred(i); | |
312 if (bbs) { | |
313 Block *p = (*bbs)[s->_idx]; | |
314 p->dump_pred(bbs, p); | |
315 } else { | |
316 while (!s->is_block_start()) | |
317 s = s->in(0); | |
318 tty->print("N%d ", s->_idx ); | |
319 } | |
320 } | |
321 } else | |
322 tty->print("BLOCK HEAD IS JUNK "); | |
323 | |
324 // Print loop, if any | |
325 const Block *bhead = this; // Head of self-loop | |
326 Node *bh = bhead->head(); | |
327 if( bbs && bh->is_Loop() && !head()->is_Root() ) { | |
328 LoopNode *loop = bh->as_Loop(); | |
329 const Block *bx = (*bbs)[loop->in(LoopNode::LoopBackControl)->_idx]; | |
330 while (bx->is_connector()) { | |
331 bx = (*bbs)[bx->pred(1)->_idx]; | |
332 } | |
333 tty->print("\tLoop: B%d-B%d ", bhead->_pre_order, bx->_pre_order); | |
334 // Dump any loop-specific bits, especially for CountedLoops. | |
335 loop->dump_spec(tty); | |
418 | 336 } else if (has_loop_alignment()) { |
337 tty->print(" top-of-loop"); | |
0 | 338 } |
339 tty->print(" Freq: %g",_freq); | |
340 if( Verbose || WizardMode ) { | |
341 tty->print(" IDom: %d/#%d", _idom ? _idom->_pre_order : 0, _dom_depth); | |
342 tty->print(" RegPressure: %d",_reg_pressure); | |
343 tty->print(" IHRP Index: %d",_ihrp_index); | |
344 tty->print(" FRegPressure: %d",_freg_pressure); | |
345 tty->print(" FHRP Index: %d",_fhrp_index); | |
346 } | |
347 tty->print_cr(""); | |
348 } | |
349 | |
350 void Block::dump() const { dump(0); } | |
351 | |
352 void Block::dump( const Block_Array *bbs ) const { | |
353 dump_head(bbs); | |
354 uint cnt = _nodes.size(); | |
355 for( uint i=0; i<cnt; i++ ) | |
356 _nodes[i]->dump(); | |
357 tty->print("\n"); | |
358 } | |
359 #endif | |
360 | |
361 //============================================================================= | |
362 //------------------------------PhaseCFG--------------------------------------- | |
363 PhaseCFG::PhaseCFG( Arena *a, RootNode *r, Matcher &m ) : | |
364 Phase(CFG), | |
365 _bbs(a), | |
1685 | 366 _root(r), |
367 _node_latency(NULL) | |
0 | 368 #ifndef PRODUCT |
369 , _trace_opto_pipelining(TraceOptoPipelining || C->method_has_option("TraceOptoPipelining")) | |
370 #endif | |
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371 #ifdef ASSERT |
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372 , _raw_oops(a) |
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373 #endif |
0 | 374 { |
375 ResourceMark rm; | |
376 // I'll need a few machine-specific GotoNodes. Make an Ideal GotoNode, | |
377 // then Match it into a machine-specific Node. Then clone the machine | |
378 // Node on demand. | |
379 Node *x = new (C, 1) GotoNode(NULL); | |
380 x->init_req(0, x); | |
381 _goto = m.match_tree(x); | |
382 assert(_goto != NULL, ""); | |
383 _goto->set_req(0,_goto); | |
384 | |
385 // Build the CFG in Reverse Post Order | |
386 _num_blocks = build_cfg(); | |
387 _broot = _bbs[_root->_idx]; | |
388 } | |
389 | |
390 //------------------------------build_cfg-------------------------------------- | |
391 // Build a proper looking CFG. Make every block begin with either a StartNode | |
392 // or a RegionNode. Make every block end with either a Goto, If or Return. | |
393 // The RootNode both starts and ends it's own block. Do this with a recursive | |
394 // backwards walk over the control edges. | |
395 uint PhaseCFG::build_cfg() { | |
396 Arena *a = Thread::current()->resource_area(); | |
397 VectorSet visited(a); | |
398 | |
399 // Allocate stack with enough space to avoid frequent realloc | |
400 Node_Stack nstack(a, C->unique() >> 1); | |
401 nstack.push(_root, 0); | |
402 uint sum = 0; // Counter for blocks | |
403 | |
404 while (nstack.is_nonempty()) { | |
405 // node and in's index from stack's top | |
406 // 'np' is _root (see above) or RegionNode, StartNode: we push on stack | |
407 // only nodes which point to the start of basic block (see below). | |
408 Node *np = nstack.node(); | |
409 // idx > 0, except for the first node (_root) pushed on stack | |
410 // at the beginning when idx == 0. | |
411 // We will use the condition (idx == 0) later to end the build. | |
412 uint idx = nstack.index(); | |
413 Node *proj = np->in(idx); | |
414 const Node *x = proj->is_block_proj(); | |
415 // Does the block end with a proper block-ending Node? One of Return, | |
416 // If or Goto? (This check should be done for visited nodes also). | |
417 if (x == NULL) { // Does not end right... | |
418 Node *g = _goto->clone(); // Force it to end in a Goto | |
419 g->set_req(0, proj); | |
420 np->set_req(idx, g); | |
421 x = proj = g; | |
422 } | |
423 if (!visited.test_set(x->_idx)) { // Visit this block once | |
424 // Skip any control-pinned middle'in stuff | |
425 Node *p = proj; | |
426 do { | |
427 proj = p; // Update pointer to last Control | |
428 p = p->in(0); // Move control forward | |
429 } while( !p->is_block_proj() && | |
430 !p->is_block_start() ); | |
431 // Make the block begin with one of Region or StartNode. | |
432 if( !p->is_block_start() ) { | |
433 RegionNode *r = new (C, 2) RegionNode( 2 ); | |
434 r->init_req(1, p); // Insert RegionNode in the way | |
435 proj->set_req(0, r); // Insert RegionNode in the way | |
436 p = r; | |
437 } | |
438 // 'p' now points to the start of this basic block | |
439 | |
440 // Put self in array of basic blocks | |
441 Block *bb = new (_bbs._arena) Block(_bbs._arena,p); | |
442 _bbs.map(p->_idx,bb); | |
443 _bbs.map(x->_idx,bb); | |
444 if( x != p ) // Only for root is x == p | |
445 bb->_nodes.push((Node*)x); | |
446 | |
447 // Now handle predecessors | |
448 ++sum; // Count 1 for self block | |
449 uint cnt = bb->num_preds(); | |
450 for (int i = (cnt - 1); i > 0; i-- ) { // For all predecessors | |
451 Node *prevproj = p->in(i); // Get prior input | |
452 assert( !prevproj->is_Con(), "dead input not removed" ); | |
453 // Check to see if p->in(i) is a "control-dependent" CFG edge - | |
454 // i.e., it splits at the source (via an IF or SWITCH) and merges | |
455 // at the destination (via a many-input Region). | |
456 // This breaks critical edges. The RegionNode to start the block | |
457 // will be added when <p,i> is pulled off the node stack | |
458 if ( cnt > 2 ) { // Merging many things? | |
459 assert( prevproj== bb->pred(i),""); | |
460 if(prevproj->is_block_proj() != prevproj) { // Control-dependent edge? | |
461 // Force a block on the control-dependent edge | |
462 Node *g = _goto->clone(); // Force it to end in a Goto | |
463 g->set_req(0,prevproj); | |
464 p->set_req(i,g); | |
465 } | |
466 } | |
467 nstack.push(p, i); // 'p' is RegionNode or StartNode | |
468 } | |
469 } else { // Post-processing visited nodes | |
470 nstack.pop(); // remove node from stack | |
471 // Check if it the fist node pushed on stack at the beginning. | |
472 if (idx == 0) break; // end of the build | |
473 // Find predecessor basic block | |
474 Block *pb = _bbs[x->_idx]; | |
475 // Insert into nodes array, if not already there | |
476 if( !_bbs.lookup(proj->_idx) ) { | |
477 assert( x != proj, "" ); | |
478 // Map basic block of projection | |
479 _bbs.map(proj->_idx,pb); | |
480 pb->_nodes.push(proj); | |
481 } | |
482 // Insert self as a child of my predecessor block | |
483 pb->_succs.map(pb->_num_succs++, _bbs[np->_idx]); | |
484 assert( pb->_nodes[ pb->_nodes.size() - pb->_num_succs ]->is_block_proj(), | |
485 "too many control users, not a CFG?" ); | |
486 } | |
487 } | |
488 // Return number of basic blocks for all children and self | |
489 return sum; | |
490 } | |
491 | |
492 //------------------------------insert_goto_at--------------------------------- | |
493 // Inserts a goto & corresponding basic block between | |
494 // block[block_no] and its succ_no'th successor block | |
495 void PhaseCFG::insert_goto_at(uint block_no, uint succ_no) { | |
496 // get block with block_no | |
497 assert(block_no < _num_blocks, "illegal block number"); | |
498 Block* in = _blocks[block_no]; | |
499 // get successor block succ_no | |
500 assert(succ_no < in->_num_succs, "illegal successor number"); | |
501 Block* out = in->_succs[succ_no]; | |
308 | 502 // Compute frequency of the new block. Do this before inserting |
503 // new block in case succ_prob() needs to infer the probability from | |
504 // surrounding blocks. | |
505 float freq = in->_freq * in->succ_prob(succ_no); | |
0 | 506 // get ProjNode corresponding to the succ_no'th successor of the in block |
507 ProjNode* proj = in->_nodes[in->_nodes.size() - in->_num_succs + succ_no]->as_Proj(); | |
508 // create region for basic block | |
509 RegionNode* region = new (C, 2) RegionNode(2); | |
510 region->init_req(1, proj); | |
511 // setup corresponding basic block | |
512 Block* block = new (_bbs._arena) Block(_bbs._arena, region); | |
513 _bbs.map(region->_idx, block); | |
514 C->regalloc()->set_bad(region->_idx); | |
515 // add a goto node | |
516 Node* gto = _goto->clone(); // get a new goto node | |
517 gto->set_req(0, region); | |
518 // add it to the basic block | |
519 block->_nodes.push(gto); | |
520 _bbs.map(gto->_idx, block); | |
521 C->regalloc()->set_bad(gto->_idx); | |
522 // hook up successor block | |
523 block->_succs.map(block->_num_succs++, out); | |
524 // remap successor's predecessors if necessary | |
525 for (uint i = 1; i < out->num_preds(); i++) { | |
526 if (out->pred(i) == proj) out->head()->set_req(i, gto); | |
527 } | |
528 // remap predecessor's successor to new block | |
529 in->_succs.map(succ_no, block); | |
308 | 530 // Set the frequency of the new block |
531 block->_freq = freq; | |
0 | 532 // add new basic block to basic block list |
533 _blocks.insert(block_no + 1, block); | |
534 _num_blocks++; | |
535 } | |
536 | |
537 //------------------------------no_flip_branch--------------------------------- | |
538 // Does this block end in a multiway branch that cannot have the default case | |
539 // flipped for another case? | |
540 static bool no_flip_branch( Block *b ) { | |
541 int branch_idx = b->_nodes.size() - b->_num_succs-1; | |
542 if( branch_idx < 1 ) return false; | |
543 Node *bra = b->_nodes[branch_idx]; | |
418 | 544 if( bra->is_Catch() ) |
545 return true; | |
0 | 546 if( bra->is_Mach() ) { |
418 | 547 if( bra->is_MachNullCheck() ) |
548 return true; | |
0 | 549 int iop = bra->as_Mach()->ideal_Opcode(); |
550 if( iop == Op_FastLock || iop == Op_FastUnlock ) | |
551 return true; | |
552 } | |
553 return false; | |
554 } | |
555 | |
556 //------------------------------convert_NeverBranch_to_Goto-------------------- | |
557 // Check for NeverBranch at block end. This needs to become a GOTO to the | |
558 // true target. NeverBranch are treated as a conditional branch that always | |
559 // goes the same direction for most of the optimizer and are used to give a | |
560 // fake exit path to infinite loops. At this late stage they need to turn | |
561 // into Goto's so that when you enter the infinite loop you indeed hang. | |
562 void PhaseCFG::convert_NeverBranch_to_Goto(Block *b) { | |
563 // Find true target | |
564 int end_idx = b->end_idx(); | |
565 int idx = b->_nodes[end_idx+1]->as_Proj()->_con; | |
566 Block *succ = b->_succs[idx]; | |
567 Node* gto = _goto->clone(); // get a new goto node | |
568 gto->set_req(0, b->head()); | |
569 Node *bp = b->_nodes[end_idx]; | |
570 b->_nodes.map(end_idx,gto); // Slam over NeverBranch | |
571 _bbs.map(gto->_idx, b); | |
572 C->regalloc()->set_bad(gto->_idx); | |
573 b->_nodes.pop(); // Yank projections | |
574 b->_nodes.pop(); // Yank projections | |
575 b->_succs.map(0,succ); // Map only successor | |
576 b->_num_succs = 1; | |
577 // remap successor's predecessors if necessary | |
578 uint j; | |
579 for( j = 1; j < succ->num_preds(); j++) | |
580 if( succ->pred(j)->in(0) == bp ) | |
581 succ->head()->set_req(j, gto); | |
582 // Kill alternate exit path | |
583 Block *dead = b->_succs[1-idx]; | |
584 for( j = 1; j < dead->num_preds(); j++) | |
585 if( dead->pred(j)->in(0) == bp ) | |
586 break; | |
587 // Scan through block, yanking dead path from | |
588 // all regions and phis. | |
589 dead->head()->del_req(j); | |
590 for( int k = 1; dead->_nodes[k]->is_Phi(); k++ ) | |
591 dead->_nodes[k]->del_req(j); | |
592 } | |
593 | |
418 | 594 //------------------------------move_to_next----------------------------------- |
0 | 595 // Helper function to move block bx to the slot following b_index. Return |
596 // true if the move is successful, otherwise false | |
418 | 597 bool PhaseCFG::move_to_next(Block* bx, uint b_index) { |
0 | 598 if (bx == NULL) return false; |
599 | |
600 // Return false if bx is already scheduled. | |
601 uint bx_index = bx->_pre_order; | |
602 if ((bx_index <= b_index) && (_blocks[bx_index] == bx)) { | |
603 return false; | |
604 } | |
605 | |
606 // Find the current index of block bx on the block list | |
607 bx_index = b_index + 1; | |
608 while( bx_index < _num_blocks && _blocks[bx_index] != bx ) bx_index++; | |
609 assert(_blocks[bx_index] == bx, "block not found"); | |
610 | |
611 // If the previous block conditionally falls into bx, return false, | |
612 // because moving bx will create an extra jump. | |
613 for(uint k = 1; k < bx->num_preds(); k++ ) { | |
614 Block* pred = _bbs[bx->pred(k)->_idx]; | |
615 if (pred == _blocks[bx_index-1]) { | |
616 if (pred->_num_succs != 1) { | |
617 return false; | |
618 } | |
619 } | |
620 } | |
621 | |
622 // Reinsert bx just past block 'b' | |
623 _blocks.remove(bx_index); | |
624 _blocks.insert(b_index + 1, bx); | |
625 return true; | |
626 } | |
627 | |
418 | 628 //------------------------------move_to_end------------------------------------ |
0 | 629 // Move empty and uncommon blocks to the end. |
418 | 630 void PhaseCFG::move_to_end(Block *b, uint i) { |
0 | 631 int e = b->is_Empty(); |
632 if (e != Block::not_empty) { | |
633 if (e == Block::empty_with_goto) { | |
634 // Remove the goto, but leave the block. | |
635 b->_nodes.pop(); | |
636 } | |
637 // Mark this block as a connector block, which will cause it to be | |
638 // ignored in certain functions such as non_connector_successor(). | |
639 b->set_connector(); | |
640 } | |
641 // Move the empty block to the end, and don't recheck. | |
642 _blocks.remove(i); | |
643 _blocks.push(b); | |
644 } | |
645 | |
418 | 646 //---------------------------set_loop_alignment-------------------------------- |
647 // Set loop alignment for every block | |
648 void PhaseCFG::set_loop_alignment() { | |
649 uint last = _num_blocks; | |
650 assert( _blocks[0] == _broot, "" ); | |
651 | |
652 for (uint i = 1; i < last; i++ ) { | |
653 Block *b = _blocks[i]; | |
654 if (b->head()->is_Loop()) { | |
655 b->set_loop_alignment(b); | |
656 } | |
657 } | |
658 } | |
659 | |
660 //-----------------------------remove_empty------------------------------------ | |
661 // Make empty basic blocks to be "connector" blocks, Move uncommon blocks | |
662 // to the end. | |
663 void PhaseCFG::remove_empty() { | |
0 | 664 // Move uncommon blocks to the end |
665 uint last = _num_blocks; | |
666 assert( _blocks[0] == _broot, "" ); | |
418 | 667 |
668 for (uint i = 1; i < last; i++) { | |
0 | 669 Block *b = _blocks[i]; |
418 | 670 if (b->is_connector()) break; |
0 | 671 |
672 // Check for NeverBranch at block end. This needs to become a GOTO to the | |
673 // true target. NeverBranch are treated as a conditional branch that | |
674 // always goes the same direction for most of the optimizer and are used | |
675 // to give a fake exit path to infinite loops. At this late stage they | |
676 // need to turn into Goto's so that when you enter the infinite loop you | |
677 // indeed hang. | |
678 if( b->_nodes[b->end_idx()]->Opcode() == Op_NeverBranch ) | |
679 convert_NeverBranch_to_Goto(b); | |
680 | |
681 // Look for uncommon blocks and move to end. | |
418 | 682 if (!C->do_freq_based_layout()) { |
683 if( b->is_uncommon(_bbs) ) { | |
684 move_to_end(b, i); | |
685 last--; // No longer check for being uncommon! | |
686 if( no_flip_branch(b) ) { // Fall-thru case must follow? | |
687 b = _blocks[i]; // Find the fall-thru block | |
688 move_to_end(b, i); | |
689 last--; | |
690 } | |
691 i--; // backup block counter post-increment | |
0 | 692 } |
693 } | |
694 } | |
695 | |
418 | 696 // Move empty blocks to the end |
0 | 697 last = _num_blocks; |
418 | 698 for (uint i = 1; i < last; i++) { |
0 | 699 Block *b = _blocks[i]; |
418 | 700 if (b->is_Empty() != Block::not_empty) { |
701 move_to_end(b, i); | |
702 last--; | |
703 i--; | |
0 | 704 } |
705 } // End of for all blocks | |
418 | 706 } |
0 | 707 |
418 | 708 //-----------------------------fixup_flow-------------------------------------- |
709 // Fix up the final control flow for basic blocks. | |
710 void PhaseCFG::fixup_flow() { | |
0 | 711 // Fixup final control flow for the blocks. Remove jump-to-next |
712 // block. If neither arm of a IF follows the conditional branch, we | |
713 // have to add a second jump after the conditional. We place the | |
714 // TRUE branch target in succs[0] for both GOTOs and IFs. | |
418 | 715 for (uint i=0; i < _num_blocks; i++) { |
0 | 716 Block *b = _blocks[i]; |
717 b->_pre_order = i; // turn pre-order into block-index | |
718 | |
719 // Connector blocks need no further processing. | |
720 if (b->is_connector()) { | |
721 assert((i+1) == _num_blocks || _blocks[i+1]->is_connector(), | |
722 "All connector blocks should sink to the end"); | |
723 continue; | |
724 } | |
725 assert(b->is_Empty() != Block::completely_empty, | |
726 "Empty blocks should be connectors"); | |
727 | |
728 Block *bnext = (i < _num_blocks-1) ? _blocks[i+1] : NULL; | |
729 Block *bs0 = b->non_connector_successor(0); | |
730 | |
731 // Check for multi-way branches where I cannot negate the test to | |
732 // exchange the true and false targets. | |
733 if( no_flip_branch( b ) ) { | |
734 // Find fall through case - if must fall into its target | |
735 int branch_idx = b->_nodes.size() - b->_num_succs; | |
736 for (uint j2 = 0; j2 < b->_num_succs; j2++) { | |
737 const ProjNode* p = b->_nodes[branch_idx + j2]->as_Proj(); | |
738 if (p->_con == 0) { | |
739 // successor j2 is fall through case | |
740 if (b->non_connector_successor(j2) != bnext) { | |
741 // but it is not the next block => insert a goto | |
742 insert_goto_at(i, j2); | |
743 } | |
744 // Put taken branch in slot 0 | |
745 if( j2 == 0 && b->_num_succs == 2) { | |
746 // Flip targets in succs map | |
747 Block *tbs0 = b->_succs[0]; | |
748 Block *tbs1 = b->_succs[1]; | |
749 b->_succs.map( 0, tbs1 ); | |
750 b->_succs.map( 1, tbs0 ); | |
751 } | |
752 break; | |
753 } | |
754 } | |
755 // Remove all CatchProjs | |
418 | 756 for (uint j1 = 0; j1 < b->_num_succs; j1++) b->_nodes.pop(); |
0 | 757 |
758 } else if (b->_num_succs == 1) { | |
759 // Block ends in a Goto? | |
760 if (bnext == bs0) { | |
761 // We fall into next block; remove the Goto | |
762 b->_nodes.pop(); | |
763 } | |
764 | |
765 } else if( b->_num_succs == 2 ) { // Block ends in a If? | |
766 // Get opcode of 1st projection (matches _succs[0]) | |
767 // Note: Since this basic block has 2 exits, the last 2 nodes must | |
768 // be projections (in any order), the 3rd last node must be | |
769 // the IfNode (we have excluded other 2-way exits such as | |
770 // CatchNodes already). | |
771 MachNode *iff = b->_nodes[b->_nodes.size()-3]->as_Mach(); | |
772 ProjNode *proj0 = b->_nodes[b->_nodes.size()-2]->as_Proj(); | |
773 ProjNode *proj1 = b->_nodes[b->_nodes.size()-1]->as_Proj(); | |
774 | |
775 // Assert that proj0 and succs[0] match up. Similarly for proj1 and succs[1]. | |
776 assert(proj0->raw_out(0) == b->_succs[0]->head(), "Mismatch successor 0"); | |
777 assert(proj1->raw_out(0) == b->_succs[1]->head(), "Mismatch successor 1"); | |
778 | |
779 Block *bs1 = b->non_connector_successor(1); | |
780 | |
781 // Check for neither successor block following the current | |
782 // block ending in a conditional. If so, move one of the | |
783 // successors after the current one, provided that the | |
784 // successor was previously unscheduled, but moveable | |
785 // (i.e., all paths to it involve a branch). | |
418 | 786 if( !C->do_freq_based_layout() && bnext != bs0 && bnext != bs1 ) { |
0 | 787 // Choose the more common successor based on the probability |
788 // of the conditional branch. | |
789 Block *bx = bs0; | |
790 Block *by = bs1; | |
791 | |
792 // _prob is the probability of taking the true path. Make | |
793 // p the probability of taking successor #1. | |
794 float p = iff->as_MachIf()->_prob; | |
795 if( proj0->Opcode() == Op_IfTrue ) { | |
796 p = 1.0 - p; | |
797 } | |
798 | |
799 // Prefer successor #1 if p > 0.5 | |
800 if (p > PROB_FAIR) { | |
801 bx = bs1; | |
802 by = bs0; | |
803 } | |
804 | |
805 // Attempt the more common successor first | |
418 | 806 if (move_to_next(bx, i)) { |
0 | 807 bnext = bx; |
418 | 808 } else if (move_to_next(by, i)) { |
0 | 809 bnext = by; |
810 } | |
811 } | |
812 | |
813 // Check for conditional branching the wrong way. Negate | |
814 // conditional, if needed, so it falls into the following block | |
815 // and branches to the not-following block. | |
816 | |
817 // Check for the next block being in succs[0]. We are going to branch | |
818 // to succs[0], so we want the fall-thru case as the next block in | |
819 // succs[1]. | |
820 if (bnext == bs0) { | |
821 // Fall-thru case in succs[0], so flip targets in succs map | |
822 Block *tbs0 = b->_succs[0]; | |
823 Block *tbs1 = b->_succs[1]; | |
824 b->_succs.map( 0, tbs1 ); | |
825 b->_succs.map( 1, tbs0 ); | |
826 // Flip projection for each target | |
827 { ProjNode *tmp = proj0; proj0 = proj1; proj1 = tmp; } | |
828 | |
418 | 829 } else if( bnext != bs1 ) { |
830 // Need a double-branch | |
0 | 831 // The existing conditional branch need not change. |
832 // Add a unconditional branch to the false target. | |
833 // Alas, it must appear in its own block and adding a | |
834 // block this late in the game is complicated. Sigh. | |
835 insert_goto_at(i, 1); | |
836 } | |
837 | |
838 // Make sure we TRUE branch to the target | |
418 | 839 if( proj0->Opcode() == Op_IfFalse ) { |
0 | 840 iff->negate(); |
418 | 841 } |
0 | 842 |
843 b->_nodes.pop(); // Remove IfFalse & IfTrue projections | |
844 b->_nodes.pop(); | |
845 | |
846 } else { | |
847 // Multi-exit block, e.g. a switch statement | |
848 // But we don't need to do anything here | |
849 } | |
850 } // End of for all blocks | |
851 } | |
852 | |
853 | |
854 //------------------------------dump------------------------------------------- | |
855 #ifndef PRODUCT | |
856 void PhaseCFG::_dump_cfg( const Node *end, VectorSet &visited ) const { | |
857 const Node *x = end->is_block_proj(); | |
858 assert( x, "not a CFG" ); | |
859 | |
860 // Do not visit this block again | |
861 if( visited.test_set(x->_idx) ) return; | |
862 | |
863 // Skip through this block | |
864 const Node *p = x; | |
865 do { | |
866 p = p->in(0); // Move control forward | |
867 assert( !p->is_block_proj() || p->is_Root(), "not a CFG" ); | |
868 } while( !p->is_block_start() ); | |
869 | |
870 // Recursively visit | |
871 for( uint i=1; i<p->req(); i++ ) | |
872 _dump_cfg(p->in(i),visited); | |
873 | |
874 // Dump the block | |
875 _bbs[p->_idx]->dump(&_bbs); | |
876 } | |
877 | |
878 void PhaseCFG::dump( ) const { | |
879 tty->print("\n--- CFG --- %d BBs\n",_num_blocks); | |
880 if( _blocks.size() ) { // Did we do basic-block layout? | |
881 for( uint i=0; i<_num_blocks; i++ ) | |
882 _blocks[i]->dump(&_bbs); | |
883 } else { // Else do it with a DFS | |
884 VectorSet visited(_bbs._arena); | |
885 _dump_cfg(_root,visited); | |
886 } | |
887 } | |
888 | |
889 void PhaseCFG::dump_headers() { | |
890 for( uint i = 0; i < _num_blocks; i++ ) { | |
891 if( _blocks[i] == NULL ) continue; | |
892 _blocks[i]->dump_head(&_bbs); | |
893 } | |
894 } | |
895 | |
896 void PhaseCFG::verify( ) const { | |
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897 #ifdef ASSERT |
0 | 898 // Verify sane CFG |
899 for( uint i = 0; i < _num_blocks; i++ ) { | |
900 Block *b = _blocks[i]; | |
901 uint cnt = b->_nodes.size(); | |
902 uint j; | |
903 for( j = 0; j < cnt; j++ ) { | |
904 Node *n = b->_nodes[j]; | |
905 assert( _bbs[n->_idx] == b, "" ); | |
906 if( j >= 1 && n->is_Mach() && | |
907 n->as_Mach()->ideal_Opcode() == Op_CreateEx ) { | |
908 assert( j == 1 || b->_nodes[j-1]->is_Phi(), | |
909 "CreateEx must be first instruction in block" ); | |
910 } | |
911 for( uint k = 0; k < n->req(); k++ ) { | |
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912 Node *def = n->in(k); |
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913 if( def && def != n ) { |
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914 assert( _bbs[def->_idx] || def->is_Con(), |
0 | 915 "must have block; constants for debug info ok" ); |
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916 // Verify that instructions in the block is in correct order. |
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917 // Uses must follow their definition if they are at the same block. |
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918 // Mostly done to check that MachSpillCopy nodes are placed correctly |
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919 // when CreateEx node is moved in build_ifg_physical(). |
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920 if( _bbs[def->_idx] == b && |
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921 !(b->head()->is_Loop() && n->is_Phi()) && |
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922 // See (+++) comment in reg_split.cpp |
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923 !(n->jvms() != NULL && n->jvms()->is_monitor_use(k)) ) { |
893
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924 bool is_loop = false; |
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925 if (n->is_Phi()) { |
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926 for( uint l = 1; l < def->req(); l++ ) { |
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927 if (n == def->in(l)) { |
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928 is_loop = true; |
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929 break; // Some kind of loop |
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930 } |
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931 } |
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932 } |
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933 assert( is_loop || b->find_node(def) < j, "uses must follow definitions" ); |
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934 } |
601
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935 if( def->is_SafePointScalarObject() ) { |
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936 assert(_bbs[def->_idx] == b, "SafePointScalarObject Node should be at the same block as its SafePoint node"); |
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937 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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938 } |
0 | 939 } |
940 } | |
941 } | |
942 | |
943 j = b->end_idx(); | |
944 Node *bp = (Node*)b->_nodes[b->_nodes.size()-1]->is_block_proj(); | |
945 assert( bp, "last instruction must be a block proj" ); | |
946 assert( bp == b->_nodes[j], "wrong number of successors for this block" ); | |
947 if( bp->is_Catch() ) { | |
948 while( b->_nodes[--j]->Opcode() == Op_MachProj ) ; | |
949 assert( b->_nodes[j]->is_Call(), "CatchProj must follow call" ); | |
950 } | |
951 else if( bp->is_Mach() && bp->as_Mach()->ideal_Opcode() == Op_If ) { | |
952 assert( b->_num_succs == 2, "Conditional branch must have two targets"); | |
953 } | |
954 } | |
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955 #endif |
0 | 956 } |
957 #endif | |
958 | |
959 //============================================================================= | |
960 //------------------------------UnionFind-------------------------------------- | |
961 UnionFind::UnionFind( uint max ) : _cnt(max), _max(max), _indices(NEW_RESOURCE_ARRAY(uint,max)) { | |
962 Copy::zero_to_bytes( _indices, sizeof(uint)*max ); | |
963 } | |
964 | |
965 void UnionFind::extend( uint from_idx, uint to_idx ) { | |
966 _nesting.check(); | |
967 if( from_idx >= _max ) { | |
968 uint size = 16; | |
969 while( size <= from_idx ) size <<=1; | |
970 _indices = REALLOC_RESOURCE_ARRAY( uint, _indices, _max, size ); | |
971 _max = size; | |
972 } | |
973 while( _cnt <= from_idx ) _indices[_cnt++] = 0; | |
974 _indices[from_idx] = to_idx; | |
975 } | |
976 | |
977 void UnionFind::reset( uint max ) { | |
978 assert( max <= max_uint, "Must fit within uint" ); | |
979 // Force the Union-Find mapping to be at least this large | |
980 extend(max,0); | |
981 // Initialize to be the ID mapping. | |
418 | 982 for( uint i=0; i<max; i++ ) map(i,i); |
0 | 983 } |
984 | |
985 //------------------------------Find_compress---------------------------------- | |
986 // Straight out of Tarjan's union-find algorithm | |
987 uint UnionFind::Find_compress( uint idx ) { | |
988 uint cur = idx; | |
989 uint next = lookup(cur); | |
990 while( next != cur ) { // Scan chain of equivalences | |
991 assert( next < cur, "always union smaller" ); | |
992 cur = next; // until find a fixed-point | |
993 next = lookup(cur); | |
994 } | |
995 // Core of union-find algorithm: update chain of | |
996 // equivalences to be equal to the root. | |
997 while( idx != next ) { | |
998 uint tmp = lookup(idx); | |
999 map(idx, next); | |
1000 idx = tmp; | |
1001 } | |
1002 return idx; | |
1003 } | |
1004 | |
1005 //------------------------------Find_const------------------------------------- | |
1006 // Like Find above, but no path compress, so bad asymptotic behavior | |
1007 uint UnionFind::Find_const( uint idx ) const { | |
1008 if( idx == 0 ) return idx; // Ignore the zero idx | |
1009 // Off the end? This can happen during debugging dumps | |
1010 // when data structures have not finished being updated. | |
1011 if( idx >= _max ) return idx; | |
1012 uint next = lookup(idx); | |
1013 while( next != idx ) { // Scan chain of equivalences | |
1014 idx = next; // until find a fixed-point | |
1015 next = lookup(idx); | |
1016 } | |
1017 return next; | |
1018 } | |
1019 | |
1020 //------------------------------Union------------------------------------------ | |
1021 // union 2 sets together. | |
1022 void UnionFind::Union( uint idx1, uint idx2 ) { | |
1023 uint src = Find(idx1); | |
1024 uint dst = Find(idx2); | |
1025 assert( src, "" ); | |
1026 assert( dst, "" ); | |
1027 assert( src < _max, "oob" ); | |
1028 assert( dst < _max, "oob" ); | |
1029 assert( src < dst, "always union smaller" ); | |
1030 map(dst,src); | |
1031 } | |
418 | 1032 |
1033 #ifndef PRODUCT | |
1034 static void edge_dump(GrowableArray<CFGEdge *> *edges) { | |
1035 tty->print_cr("---- Edges ----"); | |
1036 for (int i = 0; i < edges->length(); i++) { | |
1037 CFGEdge *e = edges->at(i); | |
1038 if (e != NULL) { | |
1039 edges->at(i)->dump(); | |
1040 } | |
1041 } | |
1042 } | |
1043 | |
1044 static void trace_dump(Trace *traces[], int count) { | |
1045 tty->print_cr("---- Traces ----"); | |
1046 for (int i = 0; i < count; i++) { | |
1047 Trace *tr = traces[i]; | |
1048 if (tr != NULL) { | |
1049 tr->dump(); | |
1050 } | |
1051 } | |
1052 } | |
1053 | |
1054 void Trace::dump( ) const { | |
1055 tty->print_cr("Trace (freq %f)", first_block()->_freq); | |
1056 for (Block *b = first_block(); b != NULL; b = next(b)) { | |
1057 tty->print(" B%d", b->_pre_order); | |
1058 if (b->head()->is_Loop()) { | |
1059 tty->print(" (L%d)", b->compute_loop_alignment()); | |
1060 } | |
1061 if (b->has_loop_alignment()) { | |
1062 tty->print(" (T%d)", b->code_alignment()); | |
1063 } | |
1064 } | |
1065 tty->cr(); | |
1066 } | |
1067 | |
1068 void CFGEdge::dump( ) const { | |
1069 tty->print(" B%d --> B%d Freq: %f out:%3d%% in:%3d%% State: ", | |
1070 from()->_pre_order, to()->_pre_order, freq(), _from_pct, _to_pct); | |
1071 switch(state()) { | |
1072 case connected: | |
1073 tty->print("connected"); | |
1074 break; | |
1075 case open: | |
1076 tty->print("open"); | |
1077 break; | |
1078 case interior: | |
1079 tty->print("interior"); | |
1080 break; | |
1081 } | |
1082 if (infrequent()) { | |
1083 tty->print(" infrequent"); | |
1084 } | |
1085 tty->cr(); | |
1086 } | |
1087 #endif | |
1088 | |
1089 //============================================================================= | |
1090 | |
1091 //------------------------------edge_order------------------------------------- | |
1092 // Comparison function for edges | |
1093 static int edge_order(CFGEdge **e0, CFGEdge **e1) { | |
1094 float freq0 = (*e0)->freq(); | |
1095 float freq1 = (*e1)->freq(); | |
1096 if (freq0 != freq1) { | |
1097 return freq0 > freq1 ? -1 : 1; | |
1098 } | |
1099 | |
1100 int dist0 = (*e0)->to()->_rpo - (*e0)->from()->_rpo; | |
1101 int dist1 = (*e1)->to()->_rpo - (*e1)->from()->_rpo; | |
1102 | |
1103 return dist1 - dist0; | |
1104 } | |
1105 | |
1106 //------------------------------trace_frequency_order-------------------------- | |
1107 // Comparison function for edges | |
1108 static int trace_frequency_order(const void *p0, const void *p1) { | |
1109 Trace *tr0 = *(Trace **) p0; | |
1110 Trace *tr1 = *(Trace **) p1; | |
1111 Block *b0 = tr0->first_block(); | |
1112 Block *b1 = tr1->first_block(); | |
1113 | |
1114 // The trace of connector blocks goes at the end; | |
1115 // we only expect one such trace | |
1116 if (b0->is_connector() != b1->is_connector()) { | |
1117 return b1->is_connector() ? -1 : 1; | |
1118 } | |
1119 | |
1120 // Pull more frequently executed blocks to the beginning | |
1121 float freq0 = b0->_freq; | |
1122 float freq1 = b1->_freq; | |
1123 if (freq0 != freq1) { | |
1124 return freq0 > freq1 ? -1 : 1; | |
1125 } | |
1126 | |
1127 int diff = tr0->first_block()->_rpo - tr1->first_block()->_rpo; | |
1128 | |
1129 return diff; | |
1130 } | |
1131 | |
1132 //------------------------------find_edges------------------------------------- | |
1133 // Find edges of interest, i.e, those which can fall through. Presumes that | |
1134 // edges which don't fall through are of low frequency and can be generally | |
1135 // ignored. Initialize the list of traces. | |
1136 void PhaseBlockLayout::find_edges() | |
1137 { | |
1138 // Walk the blocks, creating edges and Traces | |
1139 uint i; | |
1140 Trace *tr = NULL; | |
1141 for (i = 0; i < _cfg._num_blocks; i++) { | |
1142 Block *b = _cfg._blocks[i]; | |
1143 tr = new Trace(b, next, prev); | |
1144 traces[tr->id()] = tr; | |
1145 | |
1146 // All connector blocks should be at the end of the list | |
1147 if (b->is_connector()) break; | |
1148 | |
1149 // If this block and the next one have a one-to-one successor | |
1150 // predecessor relationship, simply append the next block | |
1151 int nfallthru = b->num_fall_throughs(); | |
1152 while (nfallthru == 1 && | |
1153 b->succ_fall_through(0)) { | |
1154 Block *n = b->_succs[0]; | |
1155 | |
1156 // Skip over single-entry connector blocks, we don't want to | |
1157 // add them to the trace. | |
1158 while (n->is_connector() && n->num_preds() == 1) { | |
1159 n = n->_succs[0]; | |
1160 } | |
1161 | |
1162 // We see a merge point, so stop search for the next block | |
1163 if (n->num_preds() != 1) break; | |
1164 | |
1165 i++; | |
1166 assert(n = _cfg._blocks[i], "expecting next block"); | |
1167 tr->append(n); | |
1168 uf->map(n->_pre_order, tr->id()); | |
1169 traces[n->_pre_order] = NULL; | |
1170 nfallthru = b->num_fall_throughs(); | |
1171 b = n; | |
1172 } | |
1173 | |
1174 if (nfallthru > 0) { | |
1175 // Create a CFGEdge for each outgoing | |
1176 // edge that could be a fall-through. | |
1177 for (uint j = 0; j < b->_num_succs; j++ ) { | |
1178 if (b->succ_fall_through(j)) { | |
1179 Block *target = b->non_connector_successor(j); | |
1180 float freq = b->_freq * b->succ_prob(j); | |
1181 int from_pct = (int) ((100 * freq) / b->_freq); | |
1182 int to_pct = (int) ((100 * freq) / target->_freq); | |
1183 edges->append(new CFGEdge(b, target, freq, from_pct, to_pct)); | |
1184 } | |
1185 } | |
1186 } | |
1187 } | |
1188 | |
1189 // Group connector blocks into one trace | |
1190 for (i++; i < _cfg._num_blocks; i++) { | |
1191 Block *b = _cfg._blocks[i]; | |
1192 assert(b->is_connector(), "connector blocks at the end"); | |
1193 tr->append(b); | |
1194 uf->map(b->_pre_order, tr->id()); | |
1195 traces[b->_pre_order] = NULL; | |
1196 } | |
1197 } | |
1198 | |
1199 //------------------------------union_traces---------------------------------- | |
1200 // Union two traces together in uf, and null out the trace in the list | |
1201 void PhaseBlockLayout::union_traces(Trace* updated_trace, Trace* old_trace) | |
1202 { | |
1203 uint old_id = old_trace->id(); | |
1204 uint updated_id = updated_trace->id(); | |
1205 | |
1206 uint lo_id = updated_id; | |
1207 uint hi_id = old_id; | |
1208 | |
1209 // If from is greater than to, swap values to meet | |
1210 // UnionFind guarantee. | |
1211 if (updated_id > old_id) { | |
1212 lo_id = old_id; | |
1213 hi_id = updated_id; | |
1214 | |
1215 // Fix up the trace ids | |
1216 traces[lo_id] = traces[updated_id]; | |
1217 updated_trace->set_id(lo_id); | |
1218 } | |
1219 | |
1220 // Union the lower with the higher and remove the pointer | |
1221 // to the higher. | |
1222 uf->Union(lo_id, hi_id); | |
1223 traces[hi_id] = NULL; | |
1224 } | |
1225 | |
1226 //------------------------------grow_traces------------------------------------- | |
1227 // Append traces together via the most frequently executed edges | |
1228 void PhaseBlockLayout::grow_traces() | |
1229 { | |
1230 // Order the edges, and drive the growth of Traces via the most | |
1231 // frequently executed edges. | |
1232 edges->sort(edge_order); | |
1233 for (int i = 0; i < edges->length(); i++) { | |
1234 CFGEdge *e = edges->at(i); | |
1235 | |
1236 if (e->state() != CFGEdge::open) continue; | |
1237 | |
1238 Block *src_block = e->from(); | |
1239 Block *targ_block = e->to(); | |
1240 | |
1241 // Don't grow traces along backedges? | |
1242 if (!BlockLayoutRotateLoops) { | |
1243 if (targ_block->_rpo <= src_block->_rpo) { | |
1244 targ_block->set_loop_alignment(targ_block); | |
1245 continue; | |
1246 } | |
1247 } | |
1248 | |
1249 Trace *src_trace = trace(src_block); | |
1250 Trace *targ_trace = trace(targ_block); | |
1251 | |
1252 // If the edge in question can join two traces at their ends, | |
1253 // append one trace to the other. | |
1254 if (src_trace->last_block() == src_block) { | |
1255 if (src_trace == targ_trace) { | |
1256 e->set_state(CFGEdge::interior); | |
1257 if (targ_trace->backedge(e)) { | |
1258 // Reset i to catch any newly eligible edge | |
1259 // (Or we could remember the first "open" edge, and reset there) | |
1260 i = 0; | |
1261 } | |
1262 } else if (targ_trace->first_block() == targ_block) { | |
1263 e->set_state(CFGEdge::connected); | |
1264 src_trace->append(targ_trace); | |
1265 union_traces(src_trace, targ_trace); | |
1266 } | |
1267 } | |
1268 } | |
1269 } | |
1270 | |
1271 //------------------------------merge_traces----------------------------------- | |
1272 // Embed one trace into another, if the fork or join points are sufficiently | |
1273 // balanced. | |
1274 void PhaseBlockLayout::merge_traces(bool fall_thru_only) | |
1275 { | |
1276 // Walk the edge list a another time, looking at unprocessed edges. | |
1277 // Fold in diamonds | |
1278 for (int i = 0; i < edges->length(); i++) { | |
1279 CFGEdge *e = edges->at(i); | |
1280 | |
1281 if (e->state() != CFGEdge::open) continue; | |
1282 if (fall_thru_only) { | |
1283 if (e->infrequent()) continue; | |
1284 } | |
1285 | |
1286 Block *src_block = e->from(); | |
1287 Trace *src_trace = trace(src_block); | |
1288 bool src_at_tail = src_trace->last_block() == src_block; | |
1289 | |
1290 Block *targ_block = e->to(); | |
1291 Trace *targ_trace = trace(targ_block); | |
1292 bool targ_at_start = targ_trace->first_block() == targ_block; | |
1293 | |
1294 if (src_trace == targ_trace) { | |
1295 // This may be a loop, but we can't do much about it. | |
1296 e->set_state(CFGEdge::interior); | |
1297 continue; | |
1298 } | |
1299 | |
1300 if (fall_thru_only) { | |
1301 // If the edge links the middle of two traces, we can't do anything. | |
1302 // Mark the edge and continue. | |
1303 if (!src_at_tail & !targ_at_start) { | |
1304 continue; | |
1305 } | |
1306 | |
1307 // Don't grow traces along backedges? | |
1308 if (!BlockLayoutRotateLoops && (targ_block->_rpo <= src_block->_rpo)) { | |
1309 continue; | |
1310 } | |
1311 | |
1312 // If both ends of the edge are available, why didn't we handle it earlier? | |
1313 assert(src_at_tail ^ targ_at_start, "Should have caught this edge earlier."); | |
1314 | |
1315 if (targ_at_start) { | |
1316 // Insert the "targ" trace in the "src" trace if the insertion point | |
1317 // is a two way branch. | |
1318 // Better profitability check possible, but may not be worth it. | |
1319 // Someday, see if the this "fork" has an associated "join"; | |
1320 // then make a policy on merging this trace at the fork or join. | |
1321 // For example, other things being equal, it may be better to place this | |
1322 // trace at the join point if the "src" trace ends in a two-way, but | |
1323 // the insertion point is one-way. | |
1324 assert(src_block->num_fall_throughs() == 2, "unexpected diamond"); | |
1325 e->set_state(CFGEdge::connected); | |
1326 src_trace->insert_after(src_block, targ_trace); | |
1327 union_traces(src_trace, targ_trace); | |
1328 } else if (src_at_tail) { | |
1329 if (src_trace != trace(_cfg._broot)) { | |
1330 e->set_state(CFGEdge::connected); | |
1331 targ_trace->insert_before(targ_block, src_trace); | |
1332 union_traces(targ_trace, src_trace); | |
1333 } | |
1334 } | |
1335 } else if (e->state() == CFGEdge::open) { | |
1336 // Append traces, even without a fall-thru connection. | |
605 | 1337 // But leave root entry at the beginning of the block list. |
418 | 1338 if (targ_trace != trace(_cfg._broot)) { |
1339 e->set_state(CFGEdge::connected); | |
1340 src_trace->append(targ_trace); | |
1341 union_traces(src_trace, targ_trace); | |
1342 } | |
1343 } | |
1344 } | |
1345 } | |
1346 | |
1347 //----------------------------reorder_traces----------------------------------- | |
1348 // Order the sequence of the traces in some desirable way, and fixup the | |
1349 // jumps at the end of each block. | |
1350 void PhaseBlockLayout::reorder_traces(int count) | |
1351 { | |
1352 ResourceArea *area = Thread::current()->resource_area(); | |
1353 Trace ** new_traces = NEW_ARENA_ARRAY(area, Trace *, count); | |
1354 Block_List worklist; | |
1355 int new_count = 0; | |
1356 | |
1357 // Compact the traces. | |
1358 for (int i = 0; i < count; i++) { | |
1359 Trace *tr = traces[i]; | |
1360 if (tr != NULL) { | |
1361 new_traces[new_count++] = tr; | |
1362 } | |
1363 } | |
1364 | |
1365 // The entry block should be first on the new trace list. | |
1366 Trace *tr = trace(_cfg._broot); | |
1367 assert(tr == new_traces[0], "entry trace misplaced"); | |
1368 | |
1369 // Sort the new trace list by frequency | |
1370 qsort(new_traces + 1, new_count - 1, sizeof(new_traces[0]), trace_frequency_order); | |
1371 | |
1372 // Patch up the successor blocks | |
1373 _cfg._blocks.reset(); | |
1374 _cfg._num_blocks = 0; | |
1375 for (int i = 0; i < new_count; i++) { | |
1376 Trace *tr = new_traces[i]; | |
1377 if (tr != NULL) { | |
1378 tr->fixup_blocks(_cfg); | |
1379 } | |
1380 } | |
1381 } | |
1382 | |
1383 //------------------------------PhaseBlockLayout------------------------------- | |
1384 // Order basic blocks based on frequency | |
1385 PhaseBlockLayout::PhaseBlockLayout(PhaseCFG &cfg) : | |
1386 Phase(BlockLayout), | |
1387 _cfg(cfg) | |
1388 { | |
1389 ResourceMark rm; | |
1390 ResourceArea *area = Thread::current()->resource_area(); | |
1391 | |
1392 // List of traces | |
1393 int size = _cfg._num_blocks + 1; | |
1394 traces = NEW_ARENA_ARRAY(area, Trace *, size); | |
1395 memset(traces, 0, size*sizeof(Trace*)); | |
1396 next = NEW_ARENA_ARRAY(area, Block *, size); | |
1397 memset(next, 0, size*sizeof(Block *)); | |
1398 prev = NEW_ARENA_ARRAY(area, Block *, size); | |
1399 memset(prev , 0, size*sizeof(Block *)); | |
1400 | |
1401 // List of edges | |
1402 edges = new GrowableArray<CFGEdge*>; | |
1403 | |
1404 // Mapping block index --> block_trace | |
1405 uf = new UnionFind(size); | |
1406 uf->reset(size); | |
1407 | |
1408 // Find edges and create traces. | |
1409 find_edges(); | |
1410 | |
1411 // Grow traces at their ends via most frequent edges. | |
1412 grow_traces(); | |
1413 | |
1414 // Merge one trace into another, but only at fall-through points. | |
1415 // This may make diamonds and other related shapes in a trace. | |
1416 merge_traces(true); | |
1417 | |
1418 // Run merge again, allowing two traces to be catenated, even if | |
1419 // one does not fall through into the other. This appends loosely | |
1420 // related traces to be near each other. | |
1421 merge_traces(false); | |
1422 | |
1423 // Re-order all the remaining traces by frequency | |
1424 reorder_traces(size); | |
1425 | |
1426 assert(_cfg._num_blocks >= (uint) (size - 1), "number of blocks can not shrink"); | |
1427 } | |
1428 | |
1429 | |
1430 //------------------------------backedge--------------------------------------- | |
1431 // Edge e completes a loop in a trace. If the target block is head of the | |
1432 // loop, rotate the loop block so that the loop ends in a conditional branch. | |
1433 bool Trace::backedge(CFGEdge *e) { | |
1434 bool loop_rotated = false; | |
1435 Block *src_block = e->from(); | |
1436 Block *targ_block = e->to(); | |
1437 | |
1438 assert(last_block() == src_block, "loop discovery at back branch"); | |
1439 if (first_block() == targ_block) { | |
1440 if (BlockLayoutRotateLoops && last_block()->num_fall_throughs() < 2) { | |
1441 // Find the last block in the trace that has a conditional | |
1442 // branch. | |
1443 Block *b; | |
1444 for (b = last_block(); b != NULL; b = prev(b)) { | |
1445 if (b->num_fall_throughs() == 2) { | |
1446 break; | |
1447 } | |
1448 } | |
1449 | |
1450 if (b != last_block() && b != NULL) { | |
1451 loop_rotated = true; | |
1452 | |
1453 // Rotate the loop by doing two-part linked-list surgery. | |
1454 append(first_block()); | |
1455 break_loop_after(b); | |
1456 } | |
1457 } | |
1458 | |
1459 // Backbranch to the top of a trace | |
605 | 1460 // Scroll forward through the trace from the targ_block. If we find |
418 | 1461 // a loop head before another loop top, use the the loop head alignment. |
1462 for (Block *b = targ_block; b != NULL; b = next(b)) { | |
1463 if (b->has_loop_alignment()) { | |
1464 break; | |
1465 } | |
1466 if (b->head()->is_Loop()) { | |
1467 targ_block = b; | |
1468 break; | |
1469 } | |
1470 } | |
1471 | |
1472 first_block()->set_loop_alignment(targ_block); | |
1473 | |
1474 } else { | |
1475 // Backbranch into the middle of a trace | |
1476 targ_block->set_loop_alignment(targ_block); | |
1477 } | |
1478 | |
1479 return loop_rotated; | |
1480 } | |
1481 | |
1482 //------------------------------fixup_blocks----------------------------------- | |
1483 // push blocks onto the CFG list | |
1484 // ensure that blocks have the correct two-way branch sense | |
1485 void Trace::fixup_blocks(PhaseCFG &cfg) { | |
1486 Block *last = last_block(); | |
1487 for (Block *b = first_block(); b != NULL; b = next(b)) { | |
1488 cfg._blocks.push(b); | |
1489 cfg._num_blocks++; | |
1490 if (!b->is_connector()) { | |
1491 int nfallthru = b->num_fall_throughs(); | |
1492 if (b != last) { | |
1493 if (nfallthru == 2) { | |
1494 // Ensure that the sense of the branch is correct | |
1495 Block *bnext = next(b); | |
1496 Block *bs0 = b->non_connector_successor(0); | |
1497 | |
1498 MachNode *iff = b->_nodes[b->_nodes.size()-3]->as_Mach(); | |
1499 ProjNode *proj0 = b->_nodes[b->_nodes.size()-2]->as_Proj(); | |
1500 ProjNode *proj1 = b->_nodes[b->_nodes.size()-1]->as_Proj(); | |
1501 | |
1502 if (bnext == bs0) { | |
1503 // Fall-thru case in succs[0], should be in succs[1] | |
1504 | |
1505 // Flip targets in _succs map | |
1506 Block *tbs0 = b->_succs[0]; | |
1507 Block *tbs1 = b->_succs[1]; | |
1508 b->_succs.map( 0, tbs1 ); | |
1509 b->_succs.map( 1, tbs0 ); | |
1510 | |
1511 // Flip projections to match targets | |
1512 b->_nodes.map(b->_nodes.size()-2, proj1); | |
1513 b->_nodes.map(b->_nodes.size()-1, proj0); | |
1514 } | |
1515 } | |
1516 } | |
1517 } | |
1518 } | |
1519 } |