Mercurial > hg > truffle
annotate src/share/vm/opto/block.cpp @ 12027:bcc4f6f54d83
8022993: Convert MAX_UNROLL constant to LoopMaxUnroll C2 flag
Summary: Replace MAX_UNROLL constant with new C2 LoopMaxUnroll flag.
Reviewed-by: roland
author | kvn |
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date | Wed, 14 Aug 2013 10:21:26 -0700 |
parents | d1034bd8cefc |
children | adb9a7d94cb5 |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1997, 2012, 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 * | |
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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 | |
3851 | 83 if (_pre_order == 0) return CodeEntryAlignment; |
0 | 84 // Check for Start block |
3851 | 85 if (_pre_order == 1) return InteriorEntryAlignment; |
0 | 86 // Check for loop alignment |
3851 | 87 if (has_loop_alignment()) return loop_alignment(); |
418 | 88 |
3851 | 89 return relocInfo::addr_unit(); // no particular alignment |
418 | 90 } |
91 | |
92 uint Block::compute_loop_alignment() { | |
0 | 93 Node *h = head(); |
3851 | 94 int unit_sz = relocInfo::addr_unit(); |
95 if (h->is_Loop() && h->as_Loop()->is_inner_loop()) { | |
0 | 96 // Pre- and post-loops have low trip count so do not bother with |
97 // NOPs for align loop head. The constants are hidden from tuning | |
98 // but only because my "divide by 4" heuristic surely gets nearly | |
99 // all possible gain (a "do not align at all" heuristic has a | |
100 // chance of getting a really tiny gain). | |
3851 | 101 if (h->is_CountedLoop() && (h->as_CountedLoop()->is_pre_loop() || |
102 h->as_CountedLoop()->is_post_loop())) { | |
103 return (OptoLoopAlignment > 4*unit_sz) ? (OptoLoopAlignment>>2) : unit_sz; | |
104 } | |
0 | 105 // Loops with low backedge frequency should not be aligned. |
106 Node *n = h->in(LoopNode::LoopBackControl)->in(0); | |
3851 | 107 if (n->is_MachIf() && n->as_MachIf()->_prob < 0.01) { |
108 return unit_sz; // Loop does not loop, more often than not! | |
0 | 109 } |
110 return OptoLoopAlignment; // Otherwise align loop head | |
111 } | |
418 | 112 |
3851 | 113 return unit_sz; // no particular alignment |
0 | 114 } |
115 | |
116 //----------------------------------------------------------------------------- | |
117 // Compute the size of first 'inst_cnt' instructions in this block. | |
118 // Return the number of instructions left to compute if the block has | |
418 | 119 // less then 'inst_cnt' instructions. Stop, and return 0 if sum_size |
120 // exceeds OptoLoopAlignment. | |
0 | 121 uint Block::compute_first_inst_size(uint& sum_size, uint inst_cnt, |
122 PhaseRegAlloc* ra) { | |
123 uint last_inst = _nodes.size(); | |
124 for( uint j = 0; j < last_inst && inst_cnt > 0; j++ ) { | |
125 uint inst_size = _nodes[j]->size(ra); | |
126 if( inst_size > 0 ) { | |
127 inst_cnt--; | |
128 uint sz = sum_size + inst_size; | |
129 if( sz <= (uint)OptoLoopAlignment ) { | |
130 // Compute size of instructions which fit into fetch buffer only | |
131 // since all inst_cnt instructions will not fit even if we align them. | |
132 sum_size = sz; | |
133 } else { | |
134 return 0; | |
135 } | |
136 } | |
137 } | |
138 return inst_cnt; | |
139 } | |
140 | |
141 //----------------------------------------------------------------------------- | |
142 uint Block::find_node( const Node *n ) const { | |
143 for( uint i = 0; i < _nodes.size(); i++ ) { | |
144 if( _nodes[i] == n ) | |
145 return i; | |
146 } | |
147 ShouldNotReachHere(); | |
148 return 0; | |
149 } | |
150 | |
151 // Find and remove n from block list | |
152 void Block::find_remove( const Node *n ) { | |
153 _nodes.remove(find_node(n)); | |
154 } | |
155 | |
156 //------------------------------is_Empty--------------------------------------- | |
157 // Return empty status of a block. Empty blocks contain only the head, other | |
158 // ideal nodes, and an optional trailing goto. | |
159 int Block::is_Empty() const { | |
160 | |
161 // Root or start block is not considered empty | |
162 if (head()->is_Root() || head()->is_Start()) { | |
163 return not_empty; | |
164 } | |
165 | |
166 int success_result = completely_empty; | |
167 int end_idx = _nodes.size()-1; | |
168 | |
169 // Check for ending goto | |
3842 | 170 if ((end_idx > 0) && (_nodes[end_idx]->is_MachGoto())) { |
0 | 171 success_result = empty_with_goto; |
172 end_idx--; | |
173 } | |
174 | |
175 // Unreachable blocks are considered empty | |
176 if (num_preds() <= 1) { | |
177 return success_result; | |
178 } | |
179 | |
180 // Ideal nodes are allowable in empty blocks: skip them Only MachNodes | |
181 // turn directly into code, because only MachNodes have non-trivial | |
182 // emit() functions. | |
183 while ((end_idx > 0) && !_nodes[end_idx]->is_Mach()) { | |
184 end_idx--; | |
185 } | |
186 | |
187 // No room for any interesting instructions? | |
188 if (end_idx == 0) { | |
189 return success_result; | |
190 } | |
191 | |
192 return not_empty; | |
193 } | |
194 | |
195 //------------------------------has_uncommon_code------------------------------ | |
605 | 196 // Return true if the block's code implies that it is likely to be |
0 | 197 // executed infrequently. Check to see if the block ends in a Halt or |
198 // a low probability call. | |
199 bool Block::has_uncommon_code() const { | |
200 Node* en = end(); | |
201 | |
3842 | 202 if (en->is_MachGoto()) |
0 | 203 en = en->in(0); |
204 if (en->is_Catch()) | |
205 en = en->in(0); | |
3842 | 206 if (en->is_MachProj() && en->in(0)->is_MachCall()) { |
0 | 207 MachCallNode* call = en->in(0)->as_MachCall(); |
208 if (call->cnt() != COUNT_UNKNOWN && call->cnt() <= PROB_UNLIKELY_MAG(4)) { | |
209 // This is true for slow-path stubs like new_{instance,array}, | |
210 // slow_arraycopy, complete_monitor_locking, uncommon_trap. | |
211 // The magic number corresponds to the probability of an uncommon_trap, | |
212 // even though it is a count not a probability. | |
213 return true; | |
214 } | |
215 } | |
216 | |
217 int op = en->is_Mach() ? en->as_Mach()->ideal_Opcode() : en->Opcode(); | |
218 return op == Op_Halt; | |
219 } | |
220 | |
221 //------------------------------is_uncommon------------------------------------ | |
222 // True if block is low enough frequency or guarded by a test which | |
223 // mostly does not go here. | |
12023 | 224 bool Block::is_uncommon(PhaseCFG* cfg) const { |
0 | 225 // Initial blocks must never be moved, so are never uncommon. |
226 if (head()->is_Root() || head()->is_Start()) return false; | |
227 | |
228 // Check for way-low freq | |
229 if( _freq < BLOCK_FREQUENCY(0.00001f) ) return true; | |
230 | |
231 // Look for code shape indicating uncommon_trap or slow path | |
232 if (has_uncommon_code()) return true; | |
233 | |
234 const float epsilon = 0.05f; | |
235 const float guard_factor = PROB_UNLIKELY_MAG(4) / (1.f - epsilon); | |
236 uint uncommon_preds = 0; | |
237 uint freq_preds = 0; | |
238 uint uncommon_for_freq_preds = 0; | |
239 | |
240 for( uint i=1; i<num_preds(); i++ ) { | |
12023 | 241 Block* guard = cfg->get_block_for_node(pred(i)); |
0 | 242 // Check to see if this block follows its guard 1 time out of 10000 |
243 // or less. | |
244 // | |
245 // See list of magnitude-4 unlikely probabilities in cfgnode.hpp which | |
246 // we intend to be "uncommon", such as slow-path TLE allocation, | |
247 // predicted call failure, and uncommon trap triggers. | |
248 // | |
249 // Use an epsilon value of 5% to allow for variability in frequency | |
250 // predictions and floating point calculations. The net effect is | |
251 // that guard_factor is set to 9500. | |
252 // | |
253 // Ignore low-frequency blocks. | |
254 // The next check is (guard->_freq < 1.e-5 * 9500.). | |
255 if(guard->_freq*BLOCK_FREQUENCY(guard_factor) < BLOCK_FREQUENCY(0.00001f)) { | |
256 uncommon_preds++; | |
257 } else { | |
258 freq_preds++; | |
259 if( _freq < guard->_freq * guard_factor ) { | |
260 uncommon_for_freq_preds++; | |
261 } | |
262 } | |
263 } | |
264 if( num_preds() > 1 && | |
265 // The block is uncommon if all preds are uncommon or | |
266 (uncommon_preds == (num_preds()-1) || | |
267 // it is uncommon for all frequent preds. | |
268 uncommon_for_freq_preds == freq_preds) ) { | |
269 return true; | |
270 } | |
271 return false; | |
272 } | |
273 | |
274 //------------------------------dump------------------------------------------- | |
275 #ifndef PRODUCT | |
3851 | 276 void Block::dump_bidx(const Block* orig, outputStream* st) const { |
277 if (_pre_order) st->print("B%d",_pre_order); | |
278 else st->print("N%d", head()->_idx); | |
0 | 279 |
280 if (Verbose && orig != this) { | |
281 // Dump the original block's idx | |
3851 | 282 st->print(" ("); |
283 orig->dump_bidx(orig, st); | |
284 st->print(")"); | |
0 | 285 } |
286 } | |
287 | |
12023 | 288 void Block::dump_pred(const PhaseCFG* cfg, Block* orig, outputStream* st) const { |
0 | 289 if (is_connector()) { |
290 for (uint i=1; i<num_preds(); i++) { | |
12023 | 291 Block *p = cfg->get_block_for_node(pred(i)); |
292 p->dump_pred(cfg, orig, st); | |
0 | 293 } |
294 } else { | |
3851 | 295 dump_bidx(orig, st); |
296 st->print(" "); | |
0 | 297 } |
298 } | |
299 | |
12023 | 300 void Block::dump_head(const PhaseCFG* cfg, outputStream* st) const { |
0 | 301 // Print the basic block |
3851 | 302 dump_bidx(this, st); |
303 st->print(": #\t"); | |
0 | 304 |
305 // Print the incoming CFG edges and the outgoing CFG edges | |
306 for( uint i=0; i<_num_succs; i++ ) { | |
3851 | 307 non_connector_successor(i)->dump_bidx(_succs[i], st); |
308 st->print(" "); | |
0 | 309 } |
3851 | 310 st->print("<- "); |
0 | 311 if( head()->is_block_start() ) { |
312 for (uint i=1; i<num_preds(); i++) { | |
313 Node *s = pred(i); | |
12023 | 314 if (cfg != NULL) { |
315 Block *p = cfg->get_block_for_node(s); | |
316 p->dump_pred(cfg, p, st); | |
0 | 317 } else { |
318 while (!s->is_block_start()) | |
319 s = s->in(0); | |
3851 | 320 st->print("N%d ", s->_idx ); |
0 | 321 } |
322 } | |
12023 | 323 } else { |
3851 | 324 st->print("BLOCK HEAD IS JUNK "); |
12023 | 325 } |
0 | 326 |
327 // Print loop, if any | |
328 const Block *bhead = this; // Head of self-loop | |
329 Node *bh = bhead->head(); | |
12023 | 330 |
331 if ((cfg != NULL) && bh->is_Loop() && !head()->is_Root()) { | |
0 | 332 LoopNode *loop = bh->as_Loop(); |
12023 | 333 const Block *bx = cfg->get_block_for_node(loop->in(LoopNode::LoopBackControl)); |
0 | 334 while (bx->is_connector()) { |
12023 | 335 bx = cfg->get_block_for_node(bx->pred(1)); |
0 | 336 } |
3851 | 337 st->print("\tLoop: B%d-B%d ", bhead->_pre_order, bx->_pre_order); |
0 | 338 // Dump any loop-specific bits, especially for CountedLoops. |
3851 | 339 loop->dump_spec(st); |
418 | 340 } else if (has_loop_alignment()) { |
3851 | 341 st->print(" top-of-loop"); |
0 | 342 } |
3851 | 343 st->print(" Freq: %g",_freq); |
0 | 344 if( Verbose || WizardMode ) { |
3851 | 345 st->print(" IDom: %d/#%d", _idom ? _idom->_pre_order : 0, _dom_depth); |
346 st->print(" RegPressure: %d",_reg_pressure); | |
347 st->print(" IHRP Index: %d",_ihrp_index); | |
348 st->print(" FRegPressure: %d",_freg_pressure); | |
349 st->print(" FHRP Index: %d",_fhrp_index); | |
0 | 350 } |
3851 | 351 st->print_cr(""); |
0 | 352 } |
353 | |
12023 | 354 void Block::dump() const { |
355 dump(NULL); | |
356 } | |
0 | 357 |
12023 | 358 void Block::dump(const PhaseCFG* cfg) const { |
359 dump_head(cfg); | |
360 for (uint i=0; i< _nodes.size(); i++) { | |
0 | 361 _nodes[i]->dump(); |
12023 | 362 } |
0 | 363 tty->print("\n"); |
364 } | |
365 #endif | |
366 | |
367 //============================================================================= | |
368 //------------------------------PhaseCFG--------------------------------------- | |
12023 | 369 PhaseCFG::PhaseCFG(Arena* arena, RootNode* root, Matcher& matcher) |
370 : Phase(CFG) | |
371 , _block_arena(arena) | |
372 , _node_to_block_mapping(arena) | |
373 , _root(root) | |
374 , _node_latency(NULL) | |
0 | 375 #ifndef PRODUCT |
12023 | 376 , _trace_opto_pipelining(TraceOptoPipelining || C->method_has_option("TraceOptoPipelining")) |
0 | 377 #endif |
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378 #ifdef ASSERT |
12023 | 379 , _raw_oops(arena) |
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380 #endif |
0 | 381 { |
382 ResourceMark rm; | |
383 // I'll need a few machine-specific GotoNodes. Make an Ideal GotoNode, | |
384 // then Match it into a machine-specific Node. Then clone the machine | |
385 // Node on demand. | |
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386 Node *x = new (C) GotoNode(NULL); |
0 | 387 x->init_req(0, x); |
12023 | 388 _goto = matcher.match_tree(x); |
0 | 389 assert(_goto != NULL, ""); |
390 _goto->set_req(0,_goto); | |
391 | |
392 // Build the CFG in Reverse Post Order | |
393 _num_blocks = build_cfg(); | |
12023 | 394 _broot = get_block_for_node(_root); |
0 | 395 } |
396 | |
397 //------------------------------build_cfg-------------------------------------- | |
398 // Build a proper looking CFG. Make every block begin with either a StartNode | |
399 // or a RegionNode. Make every block end with either a Goto, If or Return. | |
400 // The RootNode both starts and ends it's own block. Do this with a recursive | |
401 // backwards walk over the control edges. | |
402 uint PhaseCFG::build_cfg() { | |
403 Arena *a = Thread::current()->resource_area(); | |
404 VectorSet visited(a); | |
405 | |
406 // Allocate stack with enough space to avoid frequent realloc | |
407 Node_Stack nstack(a, C->unique() >> 1); | |
408 nstack.push(_root, 0); | |
409 uint sum = 0; // Counter for blocks | |
410 | |
411 while (nstack.is_nonempty()) { | |
412 // node and in's index from stack's top | |
413 // 'np' is _root (see above) or RegionNode, StartNode: we push on stack | |
414 // only nodes which point to the start of basic block (see below). | |
415 Node *np = nstack.node(); | |
416 // idx > 0, except for the first node (_root) pushed on stack | |
417 // at the beginning when idx == 0. | |
418 // We will use the condition (idx == 0) later to end the build. | |
419 uint idx = nstack.index(); | |
420 Node *proj = np->in(idx); | |
421 const Node *x = proj->is_block_proj(); | |
422 // Does the block end with a proper block-ending Node? One of Return, | |
423 // If or Goto? (This check should be done for visited nodes also). | |
424 if (x == NULL) { // Does not end right... | |
425 Node *g = _goto->clone(); // Force it to end in a Goto | |
426 g->set_req(0, proj); | |
427 np->set_req(idx, g); | |
428 x = proj = g; | |
429 } | |
430 if (!visited.test_set(x->_idx)) { // Visit this block once | |
431 // Skip any control-pinned middle'in stuff | |
432 Node *p = proj; | |
433 do { | |
434 proj = p; // Update pointer to last Control | |
435 p = p->in(0); // Move control forward | |
436 } while( !p->is_block_proj() && | |
437 !p->is_block_start() ); | |
438 // Make the block begin with one of Region or StartNode. | |
439 if( !p->is_block_start() ) { | |
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440 RegionNode *r = new (C) RegionNode( 2 ); |
0 | 441 r->init_req(1, p); // Insert RegionNode in the way |
442 proj->set_req(0, r); // Insert RegionNode in the way | |
443 p = r; | |
444 } | |
445 // 'p' now points to the start of this basic block | |
446 | |
447 // Put self in array of basic blocks | |
12023 | 448 Block *bb = new (_block_arena) Block(_block_arena, p); |
449 map_node_to_block(p, bb); | |
450 map_node_to_block(x, bb); | |
3851 | 451 if( x != p ) { // Only for root is x == p |
0 | 452 bb->_nodes.push((Node*)x); |
3851 | 453 } |
0 | 454 // Now handle predecessors |
455 ++sum; // Count 1 for self block | |
456 uint cnt = bb->num_preds(); | |
457 for (int i = (cnt - 1); i > 0; i-- ) { // For all predecessors | |
458 Node *prevproj = p->in(i); // Get prior input | |
459 assert( !prevproj->is_Con(), "dead input not removed" ); | |
460 // Check to see if p->in(i) is a "control-dependent" CFG edge - | |
461 // i.e., it splits at the source (via an IF or SWITCH) and merges | |
462 // at the destination (via a many-input Region). | |
463 // This breaks critical edges. The RegionNode to start the block | |
464 // will be added when <p,i> is pulled off the node stack | |
465 if ( cnt > 2 ) { // Merging many things? | |
466 assert( prevproj== bb->pred(i),""); | |
467 if(prevproj->is_block_proj() != prevproj) { // Control-dependent edge? | |
468 // Force a block on the control-dependent edge | |
469 Node *g = _goto->clone(); // Force it to end in a Goto | |
470 g->set_req(0,prevproj); | |
471 p->set_req(i,g); | |
472 } | |
473 } | |
474 nstack.push(p, i); // 'p' is RegionNode or StartNode | |
475 } | |
476 } else { // Post-processing visited nodes | |
477 nstack.pop(); // remove node from stack | |
478 // Check if it the fist node pushed on stack at the beginning. | |
479 if (idx == 0) break; // end of the build | |
480 // Find predecessor basic block | |
12023 | 481 Block *pb = get_block_for_node(x); |
0 | 482 // Insert into nodes array, if not already there |
12023 | 483 if (!has_block(proj)) { |
0 | 484 assert( x != proj, "" ); |
485 // Map basic block of projection | |
12023 | 486 map_node_to_block(proj, pb); |
0 | 487 pb->_nodes.push(proj); |
488 } | |
489 // Insert self as a child of my predecessor block | |
12023 | 490 pb->_succs.map(pb->_num_succs++, get_block_for_node(np)); |
0 | 491 assert( pb->_nodes[ pb->_nodes.size() - pb->_num_succs ]->is_block_proj(), |
492 "too many control users, not a CFG?" ); | |
493 } | |
494 } | |
495 // Return number of basic blocks for all children and self | |
496 return sum; | |
497 } | |
498 | |
499 //------------------------------insert_goto_at--------------------------------- | |
500 // Inserts a goto & corresponding basic block between | |
501 // block[block_no] and its succ_no'th successor block | |
502 void PhaseCFG::insert_goto_at(uint block_no, uint succ_no) { | |
503 // get block with block_no | |
504 assert(block_no < _num_blocks, "illegal block number"); | |
505 Block* in = _blocks[block_no]; | |
506 // get successor block succ_no | |
507 assert(succ_no < in->_num_succs, "illegal successor number"); | |
508 Block* out = in->_succs[succ_no]; | |
308 | 509 // Compute frequency of the new block. Do this before inserting |
510 // new block in case succ_prob() needs to infer the probability from | |
511 // surrounding blocks. | |
512 float freq = in->_freq * in->succ_prob(succ_no); | |
0 | 513 // get ProjNode corresponding to the succ_no'th successor of the in block |
514 ProjNode* proj = in->_nodes[in->_nodes.size() - in->_num_succs + succ_no]->as_Proj(); | |
515 // create region for basic block | |
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516 RegionNode* region = new (C) RegionNode(2); |
0 | 517 region->init_req(1, proj); |
518 // setup corresponding basic block | |
12023 | 519 Block* block = new (_block_arena) Block(_block_arena, region); |
520 map_node_to_block(region, block); | |
0 | 521 C->regalloc()->set_bad(region->_idx); |
522 // add a goto node | |
523 Node* gto = _goto->clone(); // get a new goto node | |
524 gto->set_req(0, region); | |
525 // add it to the basic block | |
526 block->_nodes.push(gto); | |
12023 | 527 map_node_to_block(gto, block); |
0 | 528 C->regalloc()->set_bad(gto->_idx); |
529 // hook up successor block | |
530 block->_succs.map(block->_num_succs++, out); | |
531 // remap successor's predecessors if necessary | |
532 for (uint i = 1; i < out->num_preds(); i++) { | |
533 if (out->pred(i) == proj) out->head()->set_req(i, gto); | |
534 } | |
535 // remap predecessor's successor to new block | |
536 in->_succs.map(succ_no, block); | |
308 | 537 // Set the frequency of the new block |
538 block->_freq = freq; | |
0 | 539 // add new basic block to basic block list |
540 _blocks.insert(block_no + 1, block); | |
541 _num_blocks++; | |
542 } | |
543 | |
544 //------------------------------no_flip_branch--------------------------------- | |
545 // Does this block end in a multiway branch that cannot have the default case | |
546 // flipped for another case? | |
547 static bool no_flip_branch( Block *b ) { | |
548 int branch_idx = b->_nodes.size() - b->_num_succs-1; | |
549 if( branch_idx < 1 ) return false; | |
550 Node *bra = b->_nodes[branch_idx]; | |
418 | 551 if( bra->is_Catch() ) |
552 return true; | |
0 | 553 if( bra->is_Mach() ) { |
418 | 554 if( bra->is_MachNullCheck() ) |
555 return true; | |
0 | 556 int iop = bra->as_Mach()->ideal_Opcode(); |
557 if( iop == Op_FastLock || iop == Op_FastUnlock ) | |
558 return true; | |
559 } | |
560 return false; | |
561 } | |
562 | |
563 //------------------------------convert_NeverBranch_to_Goto-------------------- | |
564 // Check for NeverBranch at block end. This needs to become a GOTO to the | |
565 // true target. NeverBranch are treated as a conditional branch that always | |
566 // goes the same direction for most of the optimizer and are used to give a | |
567 // fake exit path to infinite loops. At this late stage they need to turn | |
568 // into Goto's so that when you enter the infinite loop you indeed hang. | |
569 void PhaseCFG::convert_NeverBranch_to_Goto(Block *b) { | |
570 // Find true target | |
571 int end_idx = b->end_idx(); | |
572 int idx = b->_nodes[end_idx+1]->as_Proj()->_con; | |
573 Block *succ = b->_succs[idx]; | |
574 Node* gto = _goto->clone(); // get a new goto node | |
575 gto->set_req(0, b->head()); | |
576 Node *bp = b->_nodes[end_idx]; | |
577 b->_nodes.map(end_idx,gto); // Slam over NeverBranch | |
12023 | 578 map_node_to_block(gto, b); |
0 | 579 C->regalloc()->set_bad(gto->_idx); |
580 b->_nodes.pop(); // Yank projections | |
581 b->_nodes.pop(); // Yank projections | |
582 b->_succs.map(0,succ); // Map only successor | |
583 b->_num_succs = 1; | |
584 // remap successor's predecessors if necessary | |
585 uint j; | |
586 for( j = 1; j < succ->num_preds(); j++) | |
587 if( succ->pred(j)->in(0) == bp ) | |
588 succ->head()->set_req(j, gto); | |
589 // Kill alternate exit path | |
590 Block *dead = b->_succs[1-idx]; | |
591 for( j = 1; j < dead->num_preds(); j++) | |
592 if( dead->pred(j)->in(0) == bp ) | |
593 break; | |
594 // Scan through block, yanking dead path from | |
595 // all regions and phis. | |
596 dead->head()->del_req(j); | |
597 for( int k = 1; dead->_nodes[k]->is_Phi(); k++ ) | |
598 dead->_nodes[k]->del_req(j); | |
599 } | |
600 | |
418 | 601 //------------------------------move_to_next----------------------------------- |
0 | 602 // Helper function to move block bx to the slot following b_index. Return |
603 // true if the move is successful, otherwise false | |
418 | 604 bool PhaseCFG::move_to_next(Block* bx, uint b_index) { |
0 | 605 if (bx == NULL) return false; |
606 | |
607 // Return false if bx is already scheduled. | |
608 uint bx_index = bx->_pre_order; | |
609 if ((bx_index <= b_index) && (_blocks[bx_index] == bx)) { | |
610 return false; | |
611 } | |
612 | |
613 // Find the current index of block bx on the block list | |
614 bx_index = b_index + 1; | |
615 while( bx_index < _num_blocks && _blocks[bx_index] != bx ) bx_index++; | |
616 assert(_blocks[bx_index] == bx, "block not found"); | |
617 | |
618 // If the previous block conditionally falls into bx, return false, | |
619 // because moving bx will create an extra jump. | |
620 for(uint k = 1; k < bx->num_preds(); k++ ) { | |
12023 | 621 Block* pred = get_block_for_node(bx->pred(k)); |
0 | 622 if (pred == _blocks[bx_index-1]) { |
623 if (pred->_num_succs != 1) { | |
624 return false; | |
625 } | |
626 } | |
627 } | |
628 | |
629 // Reinsert bx just past block 'b' | |
630 _blocks.remove(bx_index); | |
631 _blocks.insert(b_index + 1, bx); | |
632 return true; | |
633 } | |
634 | |
418 | 635 //------------------------------move_to_end------------------------------------ |
0 | 636 // Move empty and uncommon blocks to the end. |
418 | 637 void PhaseCFG::move_to_end(Block *b, uint i) { |
0 | 638 int e = b->is_Empty(); |
639 if (e != Block::not_empty) { | |
640 if (e == Block::empty_with_goto) { | |
641 // Remove the goto, but leave the block. | |
642 b->_nodes.pop(); | |
643 } | |
644 // Mark this block as a connector block, which will cause it to be | |
645 // ignored in certain functions such as non_connector_successor(). | |
646 b->set_connector(); | |
647 } | |
648 // Move the empty block to the end, and don't recheck. | |
649 _blocks.remove(i); | |
650 _blocks.push(b); | |
651 } | |
652 | |
418 | 653 //---------------------------set_loop_alignment-------------------------------- |
654 // Set loop alignment for every block | |
655 void PhaseCFG::set_loop_alignment() { | |
656 uint last = _num_blocks; | |
657 assert( _blocks[0] == _broot, "" ); | |
658 | |
659 for (uint i = 1; i < last; i++ ) { | |
660 Block *b = _blocks[i]; | |
661 if (b->head()->is_Loop()) { | |
662 b->set_loop_alignment(b); | |
663 } | |
664 } | |
665 } | |
666 | |
667 //-----------------------------remove_empty------------------------------------ | |
668 // Make empty basic blocks to be "connector" blocks, Move uncommon blocks | |
669 // to the end. | |
670 void PhaseCFG::remove_empty() { | |
0 | 671 // Move uncommon blocks to the end |
672 uint last = _num_blocks; | |
673 assert( _blocks[0] == _broot, "" ); | |
418 | 674 |
675 for (uint i = 1; i < last; i++) { | |
0 | 676 Block *b = _blocks[i]; |
418 | 677 if (b->is_connector()) break; |
0 | 678 |
679 // Check for NeverBranch at block end. This needs to become a GOTO to the | |
680 // true target. NeverBranch are treated as a conditional branch that | |
681 // always goes the same direction for most of the optimizer and are used | |
682 // to give a fake exit path to infinite loops. At this late stage they | |
683 // need to turn into Goto's so that when you enter the infinite loop you | |
684 // indeed hang. | |
685 if( b->_nodes[b->end_idx()]->Opcode() == Op_NeverBranch ) | |
686 convert_NeverBranch_to_Goto(b); | |
687 | |
688 // Look for uncommon blocks and move to end. | |
418 | 689 if (!C->do_freq_based_layout()) { |
12023 | 690 if (b->is_uncommon(this)) { |
418 | 691 move_to_end(b, i); |
692 last--; // No longer check for being uncommon! | |
693 if( no_flip_branch(b) ) { // Fall-thru case must follow? | |
694 b = _blocks[i]; // Find the fall-thru block | |
695 move_to_end(b, i); | |
696 last--; | |
697 } | |
698 i--; // backup block counter post-increment | |
0 | 699 } |
700 } | |
701 } | |
702 | |
418 | 703 // Move empty blocks to the end |
0 | 704 last = _num_blocks; |
418 | 705 for (uint i = 1; i < last; i++) { |
0 | 706 Block *b = _blocks[i]; |
418 | 707 if (b->is_Empty() != Block::not_empty) { |
708 move_to_end(b, i); | |
709 last--; | |
710 i--; | |
0 | 711 } |
712 } // End of for all blocks | |
418 | 713 } |
0 | 714 |
418 | 715 //-----------------------------fixup_flow-------------------------------------- |
716 // Fix up the final control flow for basic blocks. | |
717 void PhaseCFG::fixup_flow() { | |
0 | 718 // Fixup final control flow for the blocks. Remove jump-to-next |
719 // block. If neither arm of a IF follows the conditional branch, we | |
720 // have to add a second jump after the conditional. We place the | |
721 // TRUE branch target in succs[0] for both GOTOs and IFs. | |
418 | 722 for (uint i=0; i < _num_blocks; i++) { |
0 | 723 Block *b = _blocks[i]; |
724 b->_pre_order = i; // turn pre-order into block-index | |
725 | |
726 // Connector blocks need no further processing. | |
727 if (b->is_connector()) { | |
728 assert((i+1) == _num_blocks || _blocks[i+1]->is_connector(), | |
729 "All connector blocks should sink to the end"); | |
730 continue; | |
731 } | |
732 assert(b->is_Empty() != Block::completely_empty, | |
733 "Empty blocks should be connectors"); | |
734 | |
735 Block *bnext = (i < _num_blocks-1) ? _blocks[i+1] : NULL; | |
736 Block *bs0 = b->non_connector_successor(0); | |
737 | |
738 // Check for multi-way branches where I cannot negate the test to | |
739 // exchange the true and false targets. | |
740 if( no_flip_branch( b ) ) { | |
741 // Find fall through case - if must fall into its target | |
742 int branch_idx = b->_nodes.size() - b->_num_succs; | |
743 for (uint j2 = 0; j2 < b->_num_succs; j2++) { | |
744 const ProjNode* p = b->_nodes[branch_idx + j2]->as_Proj(); | |
745 if (p->_con == 0) { | |
746 // successor j2 is fall through case | |
747 if (b->non_connector_successor(j2) != bnext) { | |
748 // but it is not the next block => insert a goto | |
749 insert_goto_at(i, j2); | |
750 } | |
751 // Put taken branch in slot 0 | |
752 if( j2 == 0 && b->_num_succs == 2) { | |
753 // Flip targets in succs map | |
754 Block *tbs0 = b->_succs[0]; | |
755 Block *tbs1 = b->_succs[1]; | |
756 b->_succs.map( 0, tbs1 ); | |
757 b->_succs.map( 1, tbs0 ); | |
758 } | |
759 break; | |
760 } | |
761 } | |
762 // Remove all CatchProjs | |
418 | 763 for (uint j1 = 0; j1 < b->_num_succs; j1++) b->_nodes.pop(); |
0 | 764 |
765 } else if (b->_num_succs == 1) { | |
766 // Block ends in a Goto? | |
767 if (bnext == bs0) { | |
768 // We fall into next block; remove the Goto | |
769 b->_nodes.pop(); | |
770 } | |
771 | |
772 } else if( b->_num_succs == 2 ) { // Block ends in a If? | |
773 // Get opcode of 1st projection (matches _succs[0]) | |
774 // Note: Since this basic block has 2 exits, the last 2 nodes must | |
775 // be projections (in any order), the 3rd last node must be | |
776 // the IfNode (we have excluded other 2-way exits such as | |
777 // CatchNodes already). | |
778 MachNode *iff = b->_nodes[b->_nodes.size()-3]->as_Mach(); | |
779 ProjNode *proj0 = b->_nodes[b->_nodes.size()-2]->as_Proj(); | |
780 ProjNode *proj1 = b->_nodes[b->_nodes.size()-1]->as_Proj(); | |
781 | |
782 // Assert that proj0 and succs[0] match up. Similarly for proj1 and succs[1]. | |
783 assert(proj0->raw_out(0) == b->_succs[0]->head(), "Mismatch successor 0"); | |
784 assert(proj1->raw_out(0) == b->_succs[1]->head(), "Mismatch successor 1"); | |
785 | |
786 Block *bs1 = b->non_connector_successor(1); | |
787 | |
788 // Check for neither successor block following the current | |
789 // block ending in a conditional. If so, move one of the | |
790 // successors after the current one, provided that the | |
791 // successor was previously unscheduled, but moveable | |
792 // (i.e., all paths to it involve a branch). | |
418 | 793 if( !C->do_freq_based_layout() && bnext != bs0 && bnext != bs1 ) { |
0 | 794 // Choose the more common successor based on the probability |
795 // of the conditional branch. | |
796 Block *bx = bs0; | |
797 Block *by = bs1; | |
798 | |
799 // _prob is the probability of taking the true path. Make | |
800 // p the probability of taking successor #1. | |
801 float p = iff->as_MachIf()->_prob; | |
802 if( proj0->Opcode() == Op_IfTrue ) { | |
803 p = 1.0 - p; | |
804 } | |
805 | |
806 // Prefer successor #1 if p > 0.5 | |
807 if (p > PROB_FAIR) { | |
808 bx = bs1; | |
809 by = bs0; | |
810 } | |
811 | |
812 // Attempt the more common successor first | |
418 | 813 if (move_to_next(bx, i)) { |
0 | 814 bnext = bx; |
418 | 815 } else if (move_to_next(by, i)) { |
0 | 816 bnext = by; |
817 } | |
818 } | |
819 | |
820 // Check for conditional branching the wrong way. Negate | |
821 // conditional, if needed, so it falls into the following block | |
822 // and branches to the not-following block. | |
823 | |
824 // Check for the next block being in succs[0]. We are going to branch | |
825 // to succs[0], so we want the fall-thru case as the next block in | |
826 // succs[1]. | |
827 if (bnext == bs0) { | |
828 // Fall-thru case in succs[0], so flip targets in succs map | |
829 Block *tbs0 = b->_succs[0]; | |
830 Block *tbs1 = b->_succs[1]; | |
831 b->_succs.map( 0, tbs1 ); | |
832 b->_succs.map( 1, tbs0 ); | |
833 // Flip projection for each target | |
834 { ProjNode *tmp = proj0; proj0 = proj1; proj1 = tmp; } | |
835 | |
418 | 836 } else if( bnext != bs1 ) { |
837 // Need a double-branch | |
0 | 838 // The existing conditional branch need not change. |
839 // Add a unconditional branch to the false target. | |
840 // Alas, it must appear in its own block and adding a | |
841 // block this late in the game is complicated. Sigh. | |
842 insert_goto_at(i, 1); | |
843 } | |
844 | |
845 // Make sure we TRUE branch to the target | |
418 | 846 if( proj0->Opcode() == Op_IfFalse ) { |
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847 iff->as_MachIf()->negate(); |
418 | 848 } |
0 | 849 |
850 b->_nodes.pop(); // Remove IfFalse & IfTrue projections | |
851 b->_nodes.pop(); | |
852 | |
853 } else { | |
854 // Multi-exit block, e.g. a switch statement | |
855 // But we don't need to do anything here | |
856 } | |
857 } // End of for all blocks | |
858 } | |
859 | |
860 | |
861 //------------------------------dump------------------------------------------- | |
862 #ifndef PRODUCT | |
863 void PhaseCFG::_dump_cfg( const Node *end, VectorSet &visited ) const { | |
864 const Node *x = end->is_block_proj(); | |
865 assert( x, "not a CFG" ); | |
866 | |
867 // Do not visit this block again | |
868 if( visited.test_set(x->_idx) ) return; | |
869 | |
870 // Skip through this block | |
871 const Node *p = x; | |
872 do { | |
873 p = p->in(0); // Move control forward | |
874 assert( !p->is_block_proj() || p->is_Root(), "not a CFG" ); | |
875 } while( !p->is_block_start() ); | |
876 | |
877 // Recursively visit | |
12023 | 878 for (uint i = 1; i < p->req(); i++) { |
879 _dump_cfg(p->in(i), visited); | |
880 } | |
0 | 881 |
882 // Dump the block | |
12023 | 883 get_block_for_node(p)->dump(this); |
0 | 884 } |
885 | |
886 void PhaseCFG::dump( ) const { | |
887 tty->print("\n--- CFG --- %d BBs\n",_num_blocks); | |
12023 | 888 if (_blocks.size()) { // Did we do basic-block layout? |
889 for (uint i = 0; i < _num_blocks; i++) { | |
890 _blocks[i]->dump(this); | |
891 } | |
0 | 892 } else { // Else do it with a DFS |
12023 | 893 VectorSet visited(_block_arena); |
0 | 894 _dump_cfg(_root,visited); |
895 } | |
896 } | |
897 | |
898 void PhaseCFG::dump_headers() { | |
899 for( uint i = 0; i < _num_blocks; i++ ) { | |
12023 | 900 if (_blocks[i]) { |
901 _blocks[i]->dump_head(this); | |
902 } | |
0 | 903 } |
904 } | |
905 | |
906 void PhaseCFG::verify( ) const { | |
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907 #ifdef ASSERT |
0 | 908 // Verify sane CFG |
4115 | 909 for (uint i = 0; i < _num_blocks; i++) { |
0 | 910 Block *b = _blocks[i]; |
911 uint cnt = b->_nodes.size(); | |
912 uint j; | |
4115 | 913 for (j = 0; j < cnt; j++) { |
0 | 914 Node *n = b->_nodes[j]; |
12023 | 915 assert(get_block_for_node(n) == b, ""); |
4115 | 916 if (j >= 1 && n->is_Mach() && |
917 n->as_Mach()->ideal_Opcode() == Op_CreateEx) { | |
918 assert(j == 1 || b->_nodes[j-1]->is_Phi(), | |
919 "CreateEx must be first instruction in block"); | |
0 | 920 } |
4115 | 921 for (uint k = 0; k < n->req(); k++) { |
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922 Node *def = n->in(k); |
4115 | 923 if (def && def != n) { |
12023 | 924 assert(get_block_for_node(def) || def->is_Con(), "must have block; constants for debug info ok"); |
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925 // Verify that instructions in the block is in correct order. |
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926 // Uses must follow their definition if they are at the same block. |
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927 // Mostly done to check that MachSpillCopy nodes are placed correctly |
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928 // when CreateEx node is moved in build_ifg_physical(). |
12023 | 929 if (get_block_for_node(def) == b && |
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930 !(b->head()->is_Loop() && n->is_Phi()) && |
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931 // See (+++) comment in reg_split.cpp |
4115 | 932 !(n->jvms() != NULL && n->jvms()->is_monitor_use(k))) { |
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933 bool is_loop = false; |
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934 if (n->is_Phi()) { |
4115 | 935 for (uint l = 1; l < def->req(); l++) { |
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936 if (n == def->in(l)) { |
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937 is_loop = true; |
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938 break; // Some kind of loop |
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939 } |
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940 } |
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941 } |
4115 | 942 assert(is_loop || b->find_node(def) < j, "uses must follow definitions"); |
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943 } |
0 | 944 } |
945 } | |
946 } | |
947 | |
948 j = b->end_idx(); | |
949 Node *bp = (Node*)b->_nodes[b->_nodes.size()-1]->is_block_proj(); | |
950 assert( bp, "last instruction must be a block proj" ); | |
951 assert( bp == b->_nodes[j], "wrong number of successors for this block" ); | |
4115 | 952 if (bp->is_Catch()) { |
953 while (b->_nodes[--j]->is_MachProj()) ; | |
954 assert(b->_nodes[j]->is_MachCall(), "CatchProj must follow call"); | |
955 } else if (bp->is_Mach() && bp->as_Mach()->ideal_Opcode() == Op_If) { | |
956 assert(b->_num_succs == 2, "Conditional branch must have two targets"); | |
0 | 957 } |
958 } | |
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959 #endif |
0 | 960 } |
961 #endif | |
962 | |
963 //============================================================================= | |
964 //------------------------------UnionFind-------------------------------------- | |
965 UnionFind::UnionFind( uint max ) : _cnt(max), _max(max), _indices(NEW_RESOURCE_ARRAY(uint,max)) { | |
966 Copy::zero_to_bytes( _indices, sizeof(uint)*max ); | |
967 } | |
968 | |
969 void UnionFind::extend( uint from_idx, uint to_idx ) { | |
970 _nesting.check(); | |
971 if( from_idx >= _max ) { | |
972 uint size = 16; | |
973 while( size <= from_idx ) size <<=1; | |
974 _indices = REALLOC_RESOURCE_ARRAY( uint, _indices, _max, size ); | |
975 _max = size; | |
976 } | |
977 while( _cnt <= from_idx ) _indices[_cnt++] = 0; | |
978 _indices[from_idx] = to_idx; | |
979 } | |
980 | |
981 void UnionFind::reset( uint max ) { | |
982 assert( max <= max_uint, "Must fit within uint" ); | |
983 // Force the Union-Find mapping to be at least this large | |
984 extend(max,0); | |
985 // Initialize to be the ID mapping. | |
418 | 986 for( uint i=0; i<max; i++ ) map(i,i); |
0 | 987 } |
988 | |
989 //------------------------------Find_compress---------------------------------- | |
990 // Straight out of Tarjan's union-find algorithm | |
991 uint UnionFind::Find_compress( uint idx ) { | |
992 uint cur = idx; | |
993 uint next = lookup(cur); | |
994 while( next != cur ) { // Scan chain of equivalences | |
995 assert( next < cur, "always union smaller" ); | |
996 cur = next; // until find a fixed-point | |
997 next = lookup(cur); | |
998 } | |
999 // Core of union-find algorithm: update chain of | |
1000 // equivalences to be equal to the root. | |
1001 while( idx != next ) { | |
1002 uint tmp = lookup(idx); | |
1003 map(idx, next); | |
1004 idx = tmp; | |
1005 } | |
1006 return idx; | |
1007 } | |
1008 | |
1009 //------------------------------Find_const------------------------------------- | |
1010 // Like Find above, but no path compress, so bad asymptotic behavior | |
1011 uint UnionFind::Find_const( uint idx ) const { | |
1012 if( idx == 0 ) return idx; // Ignore the zero idx | |
1013 // Off the end? This can happen during debugging dumps | |
1014 // when data structures have not finished being updated. | |
1015 if( idx >= _max ) return idx; | |
1016 uint next = lookup(idx); | |
1017 while( next != idx ) { // Scan chain of equivalences | |
1018 idx = next; // until find a fixed-point | |
1019 next = lookup(idx); | |
1020 } | |
1021 return next; | |
1022 } | |
1023 | |
1024 //------------------------------Union------------------------------------------ | |
1025 // union 2 sets together. | |
1026 void UnionFind::Union( uint idx1, uint idx2 ) { | |
1027 uint src = Find(idx1); | |
1028 uint dst = Find(idx2); | |
1029 assert( src, "" ); | |
1030 assert( dst, "" ); | |
1031 assert( src < _max, "oob" ); | |
1032 assert( dst < _max, "oob" ); | |
1033 assert( src < dst, "always union smaller" ); | |
1034 map(dst,src); | |
1035 } | |
418 | 1036 |
1037 #ifndef PRODUCT | |
1038 void Trace::dump( ) const { | |
1039 tty->print_cr("Trace (freq %f)", first_block()->_freq); | |
1040 for (Block *b = first_block(); b != NULL; b = next(b)) { | |
1041 tty->print(" B%d", b->_pre_order); | |
1042 if (b->head()->is_Loop()) { | |
1043 tty->print(" (L%d)", b->compute_loop_alignment()); | |
1044 } | |
1045 if (b->has_loop_alignment()) { | |
1046 tty->print(" (T%d)", b->code_alignment()); | |
1047 } | |
1048 } | |
1049 tty->cr(); | |
1050 } | |
1051 | |
1052 void CFGEdge::dump( ) const { | |
1053 tty->print(" B%d --> B%d Freq: %f out:%3d%% in:%3d%% State: ", | |
1054 from()->_pre_order, to()->_pre_order, freq(), _from_pct, _to_pct); | |
1055 switch(state()) { | |
1056 case connected: | |
1057 tty->print("connected"); | |
1058 break; | |
1059 case open: | |
1060 tty->print("open"); | |
1061 break; | |
1062 case interior: | |
1063 tty->print("interior"); | |
1064 break; | |
1065 } | |
1066 if (infrequent()) { | |
1067 tty->print(" infrequent"); | |
1068 } | |
1069 tty->cr(); | |
1070 } | |
1071 #endif | |
1072 | |
1073 //============================================================================= | |
1074 | |
1075 //------------------------------edge_order------------------------------------- | |
1076 // Comparison function for edges | |
1077 static int edge_order(CFGEdge **e0, CFGEdge **e1) { | |
1078 float freq0 = (*e0)->freq(); | |
1079 float freq1 = (*e1)->freq(); | |
1080 if (freq0 != freq1) { | |
1081 return freq0 > freq1 ? -1 : 1; | |
1082 } | |
1083 | |
1084 int dist0 = (*e0)->to()->_rpo - (*e0)->from()->_rpo; | |
1085 int dist1 = (*e1)->to()->_rpo - (*e1)->from()->_rpo; | |
1086 | |
1087 return dist1 - dist0; | |
1088 } | |
1089 | |
1090 //------------------------------trace_frequency_order-------------------------- | |
1091 // Comparison function for edges | |
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1092 extern "C" int trace_frequency_order(const void *p0, const void *p1) { |
418 | 1093 Trace *tr0 = *(Trace **) p0; |
1094 Trace *tr1 = *(Trace **) p1; | |
1095 Block *b0 = tr0->first_block(); | |
1096 Block *b1 = tr1->first_block(); | |
1097 | |
1098 // The trace of connector blocks goes at the end; | |
1099 // we only expect one such trace | |
1100 if (b0->is_connector() != b1->is_connector()) { | |
1101 return b1->is_connector() ? -1 : 1; | |
1102 } | |
1103 | |
1104 // Pull more frequently executed blocks to the beginning | |
1105 float freq0 = b0->_freq; | |
1106 float freq1 = b1->_freq; | |
1107 if (freq0 != freq1) { | |
1108 return freq0 > freq1 ? -1 : 1; | |
1109 } | |
1110 | |
1111 int diff = tr0->first_block()->_rpo - tr1->first_block()->_rpo; | |
1112 | |
1113 return diff; | |
1114 } | |
1115 | |
1116 //------------------------------find_edges------------------------------------- | |
1117 // Find edges of interest, i.e, those which can fall through. Presumes that | |
1118 // edges which don't fall through are of low frequency and can be generally | |
1119 // ignored. Initialize the list of traces. | |
1120 void PhaseBlockLayout::find_edges() | |
1121 { | |
1122 // Walk the blocks, creating edges and Traces | |
1123 uint i; | |
1124 Trace *tr = NULL; | |
1125 for (i = 0; i < _cfg._num_blocks; i++) { | |
1126 Block *b = _cfg._blocks[i]; | |
1127 tr = new Trace(b, next, prev); | |
1128 traces[tr->id()] = tr; | |
1129 | |
1130 // All connector blocks should be at the end of the list | |
1131 if (b->is_connector()) break; | |
1132 | |
1133 // If this block and the next one have a one-to-one successor | |
1134 // predecessor relationship, simply append the next block | |
1135 int nfallthru = b->num_fall_throughs(); | |
1136 while (nfallthru == 1 && | |
1137 b->succ_fall_through(0)) { | |
1138 Block *n = b->_succs[0]; | |
1139 | |
1140 // Skip over single-entry connector blocks, we don't want to | |
1141 // add them to the trace. | |
1142 while (n->is_connector() && n->num_preds() == 1) { | |
1143 n = n->_succs[0]; | |
1144 } | |
1145 | |
1146 // We see a merge point, so stop search for the next block | |
1147 if (n->num_preds() != 1) break; | |
1148 | |
1149 i++; | |
1150 assert(n = _cfg._blocks[i], "expecting next block"); | |
1151 tr->append(n); | |
1152 uf->map(n->_pre_order, tr->id()); | |
1153 traces[n->_pre_order] = NULL; | |
1154 nfallthru = b->num_fall_throughs(); | |
1155 b = n; | |
1156 } | |
1157 | |
1158 if (nfallthru > 0) { | |
1159 // Create a CFGEdge for each outgoing | |
1160 // edge that could be a fall-through. | |
1161 for (uint j = 0; j < b->_num_succs; j++ ) { | |
1162 if (b->succ_fall_through(j)) { | |
1163 Block *target = b->non_connector_successor(j); | |
1164 float freq = b->_freq * b->succ_prob(j); | |
1165 int from_pct = (int) ((100 * freq) / b->_freq); | |
1166 int to_pct = (int) ((100 * freq) / target->_freq); | |
1167 edges->append(new CFGEdge(b, target, freq, from_pct, to_pct)); | |
1168 } | |
1169 } | |
1170 } | |
1171 } | |
1172 | |
1173 // Group connector blocks into one trace | |
1174 for (i++; i < _cfg._num_blocks; i++) { | |
1175 Block *b = _cfg._blocks[i]; | |
1176 assert(b->is_connector(), "connector blocks at the end"); | |
1177 tr->append(b); | |
1178 uf->map(b->_pre_order, tr->id()); | |
1179 traces[b->_pre_order] = NULL; | |
1180 } | |
1181 } | |
1182 | |
1183 //------------------------------union_traces---------------------------------- | |
1184 // Union two traces together in uf, and null out the trace in the list | |
1185 void PhaseBlockLayout::union_traces(Trace* updated_trace, Trace* old_trace) | |
1186 { | |
1187 uint old_id = old_trace->id(); | |
1188 uint updated_id = updated_trace->id(); | |
1189 | |
1190 uint lo_id = updated_id; | |
1191 uint hi_id = old_id; | |
1192 | |
1193 // If from is greater than to, swap values to meet | |
1194 // UnionFind guarantee. | |
1195 if (updated_id > old_id) { | |
1196 lo_id = old_id; | |
1197 hi_id = updated_id; | |
1198 | |
1199 // Fix up the trace ids | |
1200 traces[lo_id] = traces[updated_id]; | |
1201 updated_trace->set_id(lo_id); | |
1202 } | |
1203 | |
1204 // Union the lower with the higher and remove the pointer | |
1205 // to the higher. | |
1206 uf->Union(lo_id, hi_id); | |
1207 traces[hi_id] = NULL; | |
1208 } | |
1209 | |
1210 //------------------------------grow_traces------------------------------------- | |
1211 // Append traces together via the most frequently executed edges | |
1212 void PhaseBlockLayout::grow_traces() | |
1213 { | |
1214 // Order the edges, and drive the growth of Traces via the most | |
1215 // frequently executed edges. | |
1216 edges->sort(edge_order); | |
1217 for (int i = 0; i < edges->length(); i++) { | |
1218 CFGEdge *e = edges->at(i); | |
1219 | |
1220 if (e->state() != CFGEdge::open) continue; | |
1221 | |
1222 Block *src_block = e->from(); | |
1223 Block *targ_block = e->to(); | |
1224 | |
1225 // Don't grow traces along backedges? | |
1226 if (!BlockLayoutRotateLoops) { | |
1227 if (targ_block->_rpo <= src_block->_rpo) { | |
1228 targ_block->set_loop_alignment(targ_block); | |
1229 continue; | |
1230 } | |
1231 } | |
1232 | |
1233 Trace *src_trace = trace(src_block); | |
1234 Trace *targ_trace = trace(targ_block); | |
1235 | |
1236 // If the edge in question can join two traces at their ends, | |
1237 // append one trace to the other. | |
1238 if (src_trace->last_block() == src_block) { | |
1239 if (src_trace == targ_trace) { | |
1240 e->set_state(CFGEdge::interior); | |
1241 if (targ_trace->backedge(e)) { | |
1242 // Reset i to catch any newly eligible edge | |
1243 // (Or we could remember the first "open" edge, and reset there) | |
1244 i = 0; | |
1245 } | |
1246 } else if (targ_trace->first_block() == targ_block) { | |
1247 e->set_state(CFGEdge::connected); | |
1248 src_trace->append(targ_trace); | |
1249 union_traces(src_trace, targ_trace); | |
1250 } | |
1251 } | |
1252 } | |
1253 } | |
1254 | |
1255 //------------------------------merge_traces----------------------------------- | |
1256 // Embed one trace into another, if the fork or join points are sufficiently | |
1257 // balanced. | |
1258 void PhaseBlockLayout::merge_traces(bool fall_thru_only) | |
1259 { | |
1260 // Walk the edge list a another time, looking at unprocessed edges. | |
1261 // Fold in diamonds | |
1262 for (int i = 0; i < edges->length(); i++) { | |
1263 CFGEdge *e = edges->at(i); | |
1264 | |
1265 if (e->state() != CFGEdge::open) continue; | |
1266 if (fall_thru_only) { | |
1267 if (e->infrequent()) continue; | |
1268 } | |
1269 | |
1270 Block *src_block = e->from(); | |
1271 Trace *src_trace = trace(src_block); | |
1272 bool src_at_tail = src_trace->last_block() == src_block; | |
1273 | |
1274 Block *targ_block = e->to(); | |
1275 Trace *targ_trace = trace(targ_block); | |
1276 bool targ_at_start = targ_trace->first_block() == targ_block; | |
1277 | |
1278 if (src_trace == targ_trace) { | |
1279 // This may be a loop, but we can't do much about it. | |
1280 e->set_state(CFGEdge::interior); | |
1281 continue; | |
1282 } | |
1283 | |
1284 if (fall_thru_only) { | |
1285 // If the edge links the middle of two traces, we can't do anything. | |
1286 // Mark the edge and continue. | |
1287 if (!src_at_tail & !targ_at_start) { | |
1288 continue; | |
1289 } | |
1290 | |
1291 // Don't grow traces along backedges? | |
1292 if (!BlockLayoutRotateLoops && (targ_block->_rpo <= src_block->_rpo)) { | |
1293 continue; | |
1294 } | |
1295 | |
1296 // If both ends of the edge are available, why didn't we handle it earlier? | |
1297 assert(src_at_tail ^ targ_at_start, "Should have caught this edge earlier."); | |
1298 | |
1299 if (targ_at_start) { | |
1300 // Insert the "targ" trace in the "src" trace if the insertion point | |
1301 // is a two way branch. | |
1302 // Better profitability check possible, but may not be worth it. | |
1303 // Someday, see if the this "fork" has an associated "join"; | |
1304 // then make a policy on merging this trace at the fork or join. | |
1305 // For example, other things being equal, it may be better to place this | |
1306 // trace at the join point if the "src" trace ends in a two-way, but | |
1307 // the insertion point is one-way. | |
1308 assert(src_block->num_fall_throughs() == 2, "unexpected diamond"); | |
1309 e->set_state(CFGEdge::connected); | |
1310 src_trace->insert_after(src_block, targ_trace); | |
1311 union_traces(src_trace, targ_trace); | |
1312 } else if (src_at_tail) { | |
1313 if (src_trace != trace(_cfg._broot)) { | |
1314 e->set_state(CFGEdge::connected); | |
1315 targ_trace->insert_before(targ_block, src_trace); | |
1316 union_traces(targ_trace, src_trace); | |
1317 } | |
1318 } | |
1319 } else if (e->state() == CFGEdge::open) { | |
1320 // Append traces, even without a fall-thru connection. | |
605 | 1321 // But leave root entry at the beginning of the block list. |
418 | 1322 if (targ_trace != trace(_cfg._broot)) { |
1323 e->set_state(CFGEdge::connected); | |
1324 src_trace->append(targ_trace); | |
1325 union_traces(src_trace, targ_trace); | |
1326 } | |
1327 } | |
1328 } | |
1329 } | |
1330 | |
1331 //----------------------------reorder_traces----------------------------------- | |
1332 // Order the sequence of the traces in some desirable way, and fixup the | |
1333 // jumps at the end of each block. | |
1334 void PhaseBlockLayout::reorder_traces(int count) | |
1335 { | |
1336 ResourceArea *area = Thread::current()->resource_area(); | |
1337 Trace ** new_traces = NEW_ARENA_ARRAY(area, Trace *, count); | |
1338 Block_List worklist; | |
1339 int new_count = 0; | |
1340 | |
1341 // Compact the traces. | |
1342 for (int i = 0; i < count; i++) { | |
1343 Trace *tr = traces[i]; | |
1344 if (tr != NULL) { | |
1345 new_traces[new_count++] = tr; | |
1346 } | |
1347 } | |
1348 | |
1349 // The entry block should be first on the new trace list. | |
1350 Trace *tr = trace(_cfg._broot); | |
1351 assert(tr == new_traces[0], "entry trace misplaced"); | |
1352 | |
1353 // Sort the new trace list by frequency | |
1354 qsort(new_traces + 1, new_count - 1, sizeof(new_traces[0]), trace_frequency_order); | |
1355 | |
1356 // Patch up the successor blocks | |
1357 _cfg._blocks.reset(); | |
1358 _cfg._num_blocks = 0; | |
1359 for (int i = 0; i < new_count; i++) { | |
1360 Trace *tr = new_traces[i]; | |
1361 if (tr != NULL) { | |
1362 tr->fixup_blocks(_cfg); | |
1363 } | |
1364 } | |
1365 } | |
1366 | |
1367 //------------------------------PhaseBlockLayout------------------------------- | |
1368 // Order basic blocks based on frequency | |
1369 PhaseBlockLayout::PhaseBlockLayout(PhaseCFG &cfg) : | |
1370 Phase(BlockLayout), | |
1371 _cfg(cfg) | |
1372 { | |
1373 ResourceMark rm; | |
1374 ResourceArea *area = Thread::current()->resource_area(); | |
1375 | |
1376 // List of traces | |
1377 int size = _cfg._num_blocks + 1; | |
1378 traces = NEW_ARENA_ARRAY(area, Trace *, size); | |
1379 memset(traces, 0, size*sizeof(Trace*)); | |
1380 next = NEW_ARENA_ARRAY(area, Block *, size); | |
1381 memset(next, 0, size*sizeof(Block *)); | |
1382 prev = NEW_ARENA_ARRAY(area, Block *, size); | |
1383 memset(prev , 0, size*sizeof(Block *)); | |
1384 | |
1385 // List of edges | |
1386 edges = new GrowableArray<CFGEdge*>; | |
1387 | |
1388 // Mapping block index --> block_trace | |
1389 uf = new UnionFind(size); | |
1390 uf->reset(size); | |
1391 | |
1392 // Find edges and create traces. | |
1393 find_edges(); | |
1394 | |
1395 // Grow traces at their ends via most frequent edges. | |
1396 grow_traces(); | |
1397 | |
1398 // Merge one trace into another, but only at fall-through points. | |
1399 // This may make diamonds and other related shapes in a trace. | |
1400 merge_traces(true); | |
1401 | |
1402 // Run merge again, allowing two traces to be catenated, even if | |
1403 // one does not fall through into the other. This appends loosely | |
1404 // related traces to be near each other. | |
1405 merge_traces(false); | |
1406 | |
1407 // Re-order all the remaining traces by frequency | |
1408 reorder_traces(size); | |
1409 | |
1410 assert(_cfg._num_blocks >= (uint) (size - 1), "number of blocks can not shrink"); | |
1411 } | |
1412 | |
1413 | |
1414 //------------------------------backedge--------------------------------------- | |
1415 // Edge e completes a loop in a trace. If the target block is head of the | |
1416 // loop, rotate the loop block so that the loop ends in a conditional branch. | |
1417 bool Trace::backedge(CFGEdge *e) { | |
1418 bool loop_rotated = false; | |
1419 Block *src_block = e->from(); | |
1420 Block *targ_block = e->to(); | |
1421 | |
1422 assert(last_block() == src_block, "loop discovery at back branch"); | |
1423 if (first_block() == targ_block) { | |
1424 if (BlockLayoutRotateLoops && last_block()->num_fall_throughs() < 2) { | |
1425 // Find the last block in the trace that has a conditional | |
1426 // branch. | |
1427 Block *b; | |
1428 for (b = last_block(); b != NULL; b = prev(b)) { | |
1429 if (b->num_fall_throughs() == 2) { | |
1430 break; | |
1431 } | |
1432 } | |
1433 | |
1434 if (b != last_block() && b != NULL) { | |
1435 loop_rotated = true; | |
1436 | |
1437 // Rotate the loop by doing two-part linked-list surgery. | |
1438 append(first_block()); | |
1439 break_loop_after(b); | |
1440 } | |
1441 } | |
1442 | |
1443 // Backbranch to the top of a trace | |
605 | 1444 // Scroll forward through the trace from the targ_block. If we find |
418 | 1445 // a loop head before another loop top, use the the loop head alignment. |
1446 for (Block *b = targ_block; b != NULL; b = next(b)) { | |
1447 if (b->has_loop_alignment()) { | |
1448 break; | |
1449 } | |
1450 if (b->head()->is_Loop()) { | |
1451 targ_block = b; | |
1452 break; | |
1453 } | |
1454 } | |
1455 | |
1456 first_block()->set_loop_alignment(targ_block); | |
1457 | |
1458 } else { | |
1459 // Backbranch into the middle of a trace | |
1460 targ_block->set_loop_alignment(targ_block); | |
1461 } | |
1462 | |
1463 return loop_rotated; | |
1464 } | |
1465 | |
1466 //------------------------------fixup_blocks----------------------------------- | |
1467 // push blocks onto the CFG list | |
1468 // ensure that blocks have the correct two-way branch sense | |
1469 void Trace::fixup_blocks(PhaseCFG &cfg) { | |
1470 Block *last = last_block(); | |
1471 for (Block *b = first_block(); b != NULL; b = next(b)) { | |
1472 cfg._blocks.push(b); | |
1473 cfg._num_blocks++; | |
1474 if (!b->is_connector()) { | |
1475 int nfallthru = b->num_fall_throughs(); | |
1476 if (b != last) { | |
1477 if (nfallthru == 2) { | |
1478 // Ensure that the sense of the branch is correct | |
1479 Block *bnext = next(b); | |
1480 Block *bs0 = b->non_connector_successor(0); | |
1481 | |
1482 MachNode *iff = b->_nodes[b->_nodes.size()-3]->as_Mach(); | |
1483 ProjNode *proj0 = b->_nodes[b->_nodes.size()-2]->as_Proj(); | |
1484 ProjNode *proj1 = b->_nodes[b->_nodes.size()-1]->as_Proj(); | |
1485 | |
1486 if (bnext == bs0) { | |
1487 // Fall-thru case in succs[0], should be in succs[1] | |
1488 | |
1489 // Flip targets in _succs map | |
1490 Block *tbs0 = b->_succs[0]; | |
1491 Block *tbs1 = b->_succs[1]; | |
1492 b->_succs.map( 0, tbs1 ); | |
1493 b->_succs.map( 1, tbs0 ); | |
1494 | |
1495 // Flip projections to match targets | |
1496 b->_nodes.map(b->_nodes.size()-2, proj1); | |
1497 b->_nodes.map(b->_nodes.size()-1, proj0); | |
1498 } | |
1499 } | |
1500 } | |
1501 } | |
1502 } | |
1503 } |