Mercurial > hg > truffle
annotate src/share/vm/opto/loopnode.cpp @ 952:ace8397c8563
6876276: assert(!is_visited,"visit only once")
Summary: schedule the superword loads based on dependence constraints
Reviewed-by: kvn, never
author | cfang |
---|---|
date | Mon, 31 Aug 2009 08:31:45 -0700 |
parents | 046932b72aa2 |
children | 8b22f86d1740 |
rev | line source |
---|---|
0 | 1 /* |
579 | 2 * Copyright 1998-2009 Sun Microsystems, Inc. All Rights Reserved. |
0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 #include "incls/_precompiled.incl" | |
26 #include "incls/_loopnode.cpp.incl" | |
27 | |
28 //============================================================================= | |
29 //------------------------------is_loop_iv------------------------------------- | |
30 // Determine if a node is Counted loop induction variable. | |
31 // The method is declared in node.hpp. | |
32 const Node* Node::is_loop_iv() const { | |
33 if (this->is_Phi() && !this->as_Phi()->is_copy() && | |
34 this->as_Phi()->region()->is_CountedLoop() && | |
35 this->as_Phi()->region()->as_CountedLoop()->phi() == this) { | |
36 return this; | |
37 } else { | |
38 return NULL; | |
39 } | |
40 } | |
41 | |
42 //============================================================================= | |
43 //------------------------------dump_spec-------------------------------------- | |
44 // Dump special per-node info | |
45 #ifndef PRODUCT | |
46 void LoopNode::dump_spec(outputStream *st) const { | |
47 if( is_inner_loop () ) st->print( "inner " ); | |
48 if( is_partial_peel_loop () ) st->print( "partial_peel " ); | |
49 if( partial_peel_has_failed () ) st->print( "partial_peel_failed " ); | |
50 } | |
51 #endif | |
52 | |
53 //------------------------------get_early_ctrl--------------------------------- | |
54 // Compute earliest legal control | |
55 Node *PhaseIdealLoop::get_early_ctrl( Node *n ) { | |
56 assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" ); | |
57 uint i; | |
58 Node *early; | |
59 if( n->in(0) ) { | |
60 early = n->in(0); | |
61 if( !early->is_CFG() ) // Might be a non-CFG multi-def | |
62 early = get_ctrl(early); // So treat input as a straight data input | |
63 i = 1; | |
64 } else { | |
65 early = get_ctrl(n->in(1)); | |
66 i = 2; | |
67 } | |
68 uint e_d = dom_depth(early); | |
69 assert( early, "" ); | |
70 for( ; i < n->req(); i++ ) { | |
71 Node *cin = get_ctrl(n->in(i)); | |
72 assert( cin, "" ); | |
73 // Keep deepest dominator depth | |
74 uint c_d = dom_depth(cin); | |
75 if( c_d > e_d ) { // Deeper guy? | |
76 early = cin; // Keep deepest found so far | |
77 e_d = c_d; | |
78 } else if( c_d == e_d && // Same depth? | |
79 early != cin ) { // If not equal, must use slower algorithm | |
80 // If same depth but not equal, one _must_ dominate the other | |
81 // and we want the deeper (i.e., dominated) guy. | |
82 Node *n1 = early; | |
83 Node *n2 = cin; | |
84 while( 1 ) { | |
85 n1 = idom(n1); // Walk up until break cycle | |
86 n2 = idom(n2); | |
87 if( n1 == cin || // Walked early up to cin | |
88 dom_depth(n2) < c_d ) | |
89 break; // early is deeper; keep him | |
90 if( n2 == early || // Walked cin up to early | |
91 dom_depth(n1) < c_d ) { | |
92 early = cin; // cin is deeper; keep him | |
93 break; | |
94 } | |
95 } | |
96 e_d = dom_depth(early); // Reset depth register cache | |
97 } | |
98 } | |
99 | |
100 // Return earliest legal location | |
101 assert(early == find_non_split_ctrl(early), "unexpected early control"); | |
102 | |
103 return early; | |
104 } | |
105 | |
106 //------------------------------set_early_ctrl--------------------------------- | |
107 // Set earliest legal control | |
108 void PhaseIdealLoop::set_early_ctrl( Node *n ) { | |
109 Node *early = get_early_ctrl(n); | |
110 | |
111 // Record earliest legal location | |
112 set_ctrl(n, early); | |
113 } | |
114 | |
115 //------------------------------set_subtree_ctrl------------------------------- | |
116 // set missing _ctrl entries on new nodes | |
117 void PhaseIdealLoop::set_subtree_ctrl( Node *n ) { | |
118 // Already set? Get out. | |
119 if( _nodes[n->_idx] ) return; | |
120 // Recursively set _nodes array to indicate where the Node goes | |
121 uint i; | |
122 for( i = 0; i < n->req(); ++i ) { | |
123 Node *m = n->in(i); | |
124 if( m && m != C->root() ) | |
125 set_subtree_ctrl( m ); | |
126 } | |
127 | |
128 // Fixup self | |
129 set_early_ctrl( n ); | |
130 } | |
131 | |
132 //------------------------------is_counted_loop-------------------------------- | |
133 Node *PhaseIdealLoop::is_counted_loop( Node *x, IdealLoopTree *loop ) { | |
134 PhaseGVN *gvn = &_igvn; | |
135 | |
136 // Counted loop head must be a good RegionNode with only 3 not NULL | |
137 // control input edges: Self, Entry, LoopBack. | |
138 if ( x->in(LoopNode::Self) == NULL || x->req() != 3 ) | |
139 return NULL; | |
140 | |
141 Node *init_control = x->in(LoopNode::EntryControl); | |
142 Node *back_control = x->in(LoopNode::LoopBackControl); | |
143 if( init_control == NULL || back_control == NULL ) // Partially dead | |
144 return NULL; | |
145 // Must also check for TOP when looking for a dead loop | |
146 if( init_control->is_top() || back_control->is_top() ) | |
147 return NULL; | |
148 | |
149 // Allow funny placement of Safepoint | |
150 if( back_control->Opcode() == Op_SafePoint ) | |
151 back_control = back_control->in(TypeFunc::Control); | |
152 | |
153 // Controlling test for loop | |
154 Node *iftrue = back_control; | |
155 uint iftrue_op = iftrue->Opcode(); | |
156 if( iftrue_op != Op_IfTrue && | |
157 iftrue_op != Op_IfFalse ) | |
158 // I have a weird back-control. Probably the loop-exit test is in | |
159 // the middle of the loop and I am looking at some trailing control-flow | |
160 // merge point. To fix this I would have to partially peel the loop. | |
161 return NULL; // Obscure back-control | |
162 | |
163 // Get boolean guarding loop-back test | |
164 Node *iff = iftrue->in(0); | |
165 if( get_loop(iff) != loop || !iff->in(1)->is_Bool() ) return NULL; | |
166 BoolNode *test = iff->in(1)->as_Bool(); | |
167 BoolTest::mask bt = test->_test._test; | |
168 float cl_prob = iff->as_If()->_prob; | |
169 if( iftrue_op == Op_IfFalse ) { | |
170 bt = BoolTest(bt).negate(); | |
171 cl_prob = 1.0 - cl_prob; | |
172 } | |
173 // Get backedge compare | |
174 Node *cmp = test->in(1); | |
175 int cmp_op = cmp->Opcode(); | |
176 if( cmp_op != Op_CmpI ) | |
177 return NULL; // Avoid pointer & float compares | |
178 | |
179 // Find the trip-counter increment & limit. Limit must be loop invariant. | |
180 Node *incr = cmp->in(1); | |
181 Node *limit = cmp->in(2); | |
182 | |
183 // --------- | |
184 // need 'loop()' test to tell if limit is loop invariant | |
185 // --------- | |
186 | |
187 if( !is_member( loop, get_ctrl(incr) ) ) { // Swapped trip counter and limit? | |
188 Node *tmp = incr; // Then reverse order into the CmpI | |
189 incr = limit; | |
190 limit = tmp; | |
191 bt = BoolTest(bt).commute(); // And commute the exit test | |
192 } | |
193 if( is_member( loop, get_ctrl(limit) ) ) // Limit must loop-invariant | |
194 return NULL; | |
195 | |
196 // Trip-counter increment must be commutative & associative. | |
197 uint incr_op = incr->Opcode(); | |
198 if( incr_op == Op_Phi && incr->req() == 3 ) { | |
199 incr = incr->in(2); // Assume incr is on backedge of Phi | |
200 incr_op = incr->Opcode(); | |
201 } | |
202 Node* trunc1 = NULL; | |
203 Node* trunc2 = NULL; | |
204 const TypeInt* iv_trunc_t = NULL; | |
205 if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) { | |
206 return NULL; // Funny increment opcode | |
207 } | |
208 | |
209 // Get merge point | |
210 Node *xphi = incr->in(1); | |
211 Node *stride = incr->in(2); | |
212 if( !stride->is_Con() ) { // Oops, swap these | |
213 if( !xphi->is_Con() ) // Is the other guy a constant? | |
214 return NULL; // Nope, unknown stride, bail out | |
215 Node *tmp = xphi; // 'incr' is commutative, so ok to swap | |
216 xphi = stride; | |
217 stride = tmp; | |
218 } | |
219 //if( loop(xphi) != l) return NULL;// Merge point is in inner loop?? | |
220 if( !xphi->is_Phi() ) return NULL; // Too much math on the trip counter | |
221 PhiNode *phi = xphi->as_Phi(); | |
222 | |
223 // Stride must be constant | |
224 const Type *stride_t = stride->bottom_type(); | |
225 int stride_con = stride_t->is_int()->get_con(); | |
226 assert( stride_con, "missed some peephole opt" ); | |
227 | |
228 // Phi must be of loop header; backedge must wrap to increment | |
229 if( phi->region() != x ) return NULL; | |
230 if( trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr || | |
231 trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1 ) { | |
232 return NULL; | |
233 } | |
234 Node *init_trip = phi->in(LoopNode::EntryControl); | |
235 //if (!init_trip->is_Con()) return NULL; // avoid rolling over MAXINT/MININT | |
236 | |
237 // If iv trunc type is smaller than int, check for possible wrap. | |
238 if (!TypeInt::INT->higher_equal(iv_trunc_t)) { | |
239 assert(trunc1 != NULL, "must have found some truncation"); | |
240 | |
241 // Get a better type for the phi (filtered thru if's) | |
242 const TypeInt* phi_ft = filtered_type(phi); | |
243 | |
244 // Can iv take on a value that will wrap? | |
245 // | |
246 // Ensure iv's limit is not within "stride" of the wrap value. | |
247 // | |
248 // Example for "short" type | |
249 // Truncation ensures value is in the range -32768..32767 (iv_trunc_t) | |
250 // If the stride is +10, then the last value of the induction | |
251 // variable before the increment (phi_ft->_hi) must be | |
252 // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to | |
253 // ensure no truncation occurs after the increment. | |
254 | |
255 if (stride_con > 0) { | |
256 if (iv_trunc_t->_hi - phi_ft->_hi < stride_con || | |
257 iv_trunc_t->_lo > phi_ft->_lo) { | |
258 return NULL; // truncation may occur | |
259 } | |
260 } else if (stride_con < 0) { | |
261 if (iv_trunc_t->_lo - phi_ft->_lo > stride_con || | |
262 iv_trunc_t->_hi < phi_ft->_hi) { | |
263 return NULL; // truncation may occur | |
264 } | |
265 } | |
266 // No possibility of wrap so truncation can be discarded | |
267 // Promote iv type to Int | |
268 } else { | |
269 assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int"); | |
270 } | |
271 | |
272 // ================================================= | |
273 // ---- SUCCESS! Found A Trip-Counted Loop! ----- | |
274 // | |
275 // Canonicalize the condition on the test. If we can exactly determine | |
276 // the trip-counter exit value, then set limit to that value and use | |
605 | 277 // a '!=' test. Otherwise use condition '<' for count-up loops and |
0 | 278 // '>' for count-down loops. If the condition is inverted and we will |
279 // be rolling through MININT to MAXINT, then bail out. | |
280 | |
281 C->print_method("Before CountedLoop", 3); | |
282 | |
283 // Check for SafePoint on backedge and remove | |
284 Node *sfpt = x->in(LoopNode::LoopBackControl); | |
285 if( sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) { | |
286 lazy_replace( sfpt, iftrue ); | |
287 loop->_tail = iftrue; | |
288 } | |
289 | |
290 | |
291 // If compare points to incr, we are ok. Otherwise the compare | |
292 // can directly point to the phi; in this case adjust the compare so that | |
605 | 293 // it points to the incr by adjusting the limit. |
0 | 294 if( cmp->in(1) == phi || cmp->in(2) == phi ) |
295 limit = gvn->transform(new (C, 3) AddINode(limit,stride)); | |
296 | |
297 // trip-count for +-tive stride should be: (limit - init_trip + stride - 1)/stride. | |
298 // Final value for iterator should be: trip_count * stride + init_trip. | |
299 const Type *limit_t = limit->bottom_type(); | |
300 const Type *init_t = init_trip->bottom_type(); | |
301 Node *one_p = gvn->intcon( 1); | |
302 Node *one_m = gvn->intcon(-1); | |
303 | |
304 Node *trip_count = NULL; | |
305 Node *hook = new (C, 6) Node(6); | |
306 switch( bt ) { | |
307 case BoolTest::eq: | |
308 return NULL; // Bail out, but this loop trips at most twice! | |
309 case BoolTest::ne: // Ahh, the case we desire | |
310 if( stride_con == 1 ) | |
311 trip_count = gvn->transform(new (C, 3) SubINode(limit,init_trip)); | |
312 else if( stride_con == -1 ) | |
313 trip_count = gvn->transform(new (C, 3) SubINode(init_trip,limit)); | |
314 else | |
315 return NULL; // Odd stride; must prove we hit limit exactly | |
316 set_subtree_ctrl( trip_count ); | |
317 //_loop.map(trip_count->_idx,loop(limit)); | |
318 break; | |
319 case BoolTest::le: // Maybe convert to '<' case | |
320 limit = gvn->transform(new (C, 3) AddINode(limit,one_p)); | |
321 set_subtree_ctrl( limit ); | |
322 hook->init_req(4, limit); | |
323 | |
324 bt = BoolTest::lt; | |
325 // Make the new limit be in the same loop nest as the old limit | |
326 //_loop.map(limit->_idx,limit_loop); | |
327 // Fall into next case | |
328 case BoolTest::lt: { // Maybe convert to '!=' case | |
329 if( stride_con < 0 ) return NULL; // Count down loop rolls through MAXINT | |
330 Node *range = gvn->transform(new (C, 3) SubINode(limit,init_trip)); | |
331 set_subtree_ctrl( range ); | |
332 hook->init_req(0, range); | |
333 | |
334 Node *bias = gvn->transform(new (C, 3) AddINode(range,stride)); | |
335 set_subtree_ctrl( bias ); | |
336 hook->init_req(1, bias); | |
337 | |
338 Node *bias1 = gvn->transform(new (C, 3) AddINode(bias,one_m)); | |
339 set_subtree_ctrl( bias1 ); | |
340 hook->init_req(2, bias1); | |
341 | |
342 trip_count = gvn->transform(new (C, 3) DivINode(0,bias1,stride)); | |
343 set_subtree_ctrl( trip_count ); | |
344 hook->init_req(3, trip_count); | |
345 break; | |
346 } | |
347 | |
348 case BoolTest::ge: // Maybe convert to '>' case | |
349 limit = gvn->transform(new (C, 3) AddINode(limit,one_m)); | |
350 set_subtree_ctrl( limit ); | |
351 hook->init_req(4 ,limit); | |
352 | |
353 bt = BoolTest::gt; | |
354 // Make the new limit be in the same loop nest as the old limit | |
355 //_loop.map(limit->_idx,limit_loop); | |
356 // Fall into next case | |
357 case BoolTest::gt: { // Maybe convert to '!=' case | |
358 if( stride_con > 0 ) return NULL; // count up loop rolls through MININT | |
359 Node *range = gvn->transform(new (C, 3) SubINode(limit,init_trip)); | |
360 set_subtree_ctrl( range ); | |
361 hook->init_req(0, range); | |
362 | |
363 Node *bias = gvn->transform(new (C, 3) AddINode(range,stride)); | |
364 set_subtree_ctrl( bias ); | |
365 hook->init_req(1, bias); | |
366 | |
367 Node *bias1 = gvn->transform(new (C, 3) AddINode(bias,one_p)); | |
368 set_subtree_ctrl( bias1 ); | |
369 hook->init_req(2, bias1); | |
370 | |
371 trip_count = gvn->transform(new (C, 3) DivINode(0,bias1,stride)); | |
372 set_subtree_ctrl( trip_count ); | |
373 hook->init_req(3, trip_count); | |
374 break; | |
375 } | |
376 } | |
377 | |
378 Node *span = gvn->transform(new (C, 3) MulINode(trip_count,stride)); | |
379 set_subtree_ctrl( span ); | |
380 hook->init_req(5, span); | |
381 | |
382 limit = gvn->transform(new (C, 3) AddINode(span,init_trip)); | |
383 set_subtree_ctrl( limit ); | |
384 | |
385 // Build a canonical trip test. | |
386 // Clone code, as old values may be in use. | |
387 incr = incr->clone(); | |
388 incr->set_req(1,phi); | |
389 incr->set_req(2,stride); | |
390 incr = _igvn.register_new_node_with_optimizer(incr); | |
391 set_early_ctrl( incr ); | |
392 _igvn.hash_delete(phi); | |
393 phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn ); | |
394 | |
395 // If phi type is more restrictive than Int, raise to | |
396 // Int to prevent (almost) infinite recursion in igvn | |
397 // which can only handle integer types for constants or minint..maxint. | |
398 if (!TypeInt::INT->higher_equal(phi->bottom_type())) { | |
399 Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT); | |
400 nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl)); | |
401 nphi = _igvn.register_new_node_with_optimizer(nphi); | |
402 set_ctrl(nphi, get_ctrl(phi)); | |
403 _igvn.subsume_node(phi, nphi); | |
404 phi = nphi->as_Phi(); | |
405 } | |
406 cmp = cmp->clone(); | |
407 cmp->set_req(1,incr); | |
408 cmp->set_req(2,limit); | |
409 cmp = _igvn.register_new_node_with_optimizer(cmp); | |
410 set_ctrl(cmp, iff->in(0)); | |
411 | |
412 Node *tmp = test->clone(); | |
413 assert( tmp->is_Bool(), "" ); | |
414 test = (BoolNode*)tmp; | |
415 (*(BoolTest*)&test->_test)._test = bt; //BoolTest::ne; | |
416 test->set_req(1,cmp); | |
417 _igvn.register_new_node_with_optimizer(test); | |
418 set_ctrl(test, iff->in(0)); | |
419 // If the exit test is dead, STOP! | |
420 if( test == NULL ) return NULL; | |
421 _igvn.hash_delete(iff); | |
422 iff->set_req_X( 1, test, &_igvn ); | |
423 | |
424 // Replace the old IfNode with a new LoopEndNode | |
425 Node *lex = _igvn.register_new_node_with_optimizer(new (C, 2) CountedLoopEndNode( iff->in(0), iff->in(1), cl_prob, iff->as_If()->_fcnt )); | |
426 IfNode *le = lex->as_If(); | |
427 uint dd = dom_depth(iff); | |
428 set_idom(le, le->in(0), dd); // Update dominance for loop exit | |
429 set_loop(le, loop); | |
430 | |
431 // Get the loop-exit control | |
432 Node *if_f = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue)); | |
433 | |
434 // Need to swap loop-exit and loop-back control? | |
435 if( iftrue_op == Op_IfFalse ) { | |
436 Node *ift2=_igvn.register_new_node_with_optimizer(new (C, 1) IfTrueNode (le)); | |
437 Node *iff2=_igvn.register_new_node_with_optimizer(new (C, 1) IfFalseNode(le)); | |
438 | |
439 loop->_tail = back_control = ift2; | |
440 set_loop(ift2, loop); | |
441 set_loop(iff2, get_loop(if_f)); | |
442 | |
443 // Lazy update of 'get_ctrl' mechanism. | |
444 lazy_replace_proj( if_f , iff2 ); | |
445 lazy_replace_proj( iftrue, ift2 ); | |
446 | |
447 // Swap names | |
448 if_f = iff2; | |
449 iftrue = ift2; | |
450 } else { | |
451 _igvn.hash_delete(if_f ); | |
452 _igvn.hash_delete(iftrue); | |
453 if_f ->set_req_X( 0, le, &_igvn ); | |
454 iftrue->set_req_X( 0, le, &_igvn ); | |
455 } | |
456 | |
457 set_idom(iftrue, le, dd+1); | |
458 set_idom(if_f, le, dd+1); | |
459 | |
460 // Now setup a new CountedLoopNode to replace the existing LoopNode | |
461 CountedLoopNode *l = new (C, 3) CountedLoopNode(init_control, back_control); | |
462 // The following assert is approximately true, and defines the intention | |
463 // of can_be_counted_loop. It fails, however, because phase->type | |
464 // is not yet initialized for this loop and its parts. | |
465 //assert(l->can_be_counted_loop(this), "sanity"); | |
466 _igvn.register_new_node_with_optimizer(l); | |
467 set_loop(l, loop); | |
468 loop->_head = l; | |
469 // Fix all data nodes placed at the old loop head. | |
470 // Uses the lazy-update mechanism of 'get_ctrl'. | |
471 lazy_replace( x, l ); | |
472 set_idom(l, init_control, dom_depth(x)); | |
473 | |
605 | 474 // Check for immediately preceding SafePoint and remove |
0 | 475 Node *sfpt2 = le->in(0); |
476 if( sfpt2->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt2)) | |
477 lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control)); | |
478 | |
479 // Free up intermediate goo | |
480 _igvn.remove_dead_node(hook); | |
481 | |
482 C->print_method("After CountedLoop", 3); | |
483 | |
484 // Return trip counter | |
485 return trip_count; | |
486 } | |
487 | |
488 | |
489 //------------------------------Ideal------------------------------------------ | |
490 // Return a node which is more "ideal" than the current node. | |
491 // Attempt to convert into a counted-loop. | |
492 Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) { | |
493 if (!can_be_counted_loop(phase)) { | |
494 phase->C->set_major_progress(); | |
495 } | |
496 return RegionNode::Ideal(phase, can_reshape); | |
497 } | |
498 | |
499 | |
500 //============================================================================= | |
501 //------------------------------Ideal------------------------------------------ | |
502 // Return a node which is more "ideal" than the current node. | |
503 // Attempt to convert into a counted-loop. | |
504 Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) { | |
505 return RegionNode::Ideal(phase, can_reshape); | |
506 } | |
507 | |
508 //------------------------------dump_spec-------------------------------------- | |
509 // Dump special per-node info | |
510 #ifndef PRODUCT | |
511 void CountedLoopNode::dump_spec(outputStream *st) const { | |
512 LoopNode::dump_spec(st); | |
513 if( stride_is_con() ) { | |
514 st->print("stride: %d ",stride_con()); | |
515 } else { | |
516 st->print("stride: not constant "); | |
517 } | |
518 if( is_pre_loop () ) st->print("pre of N%d" , _main_idx ); | |
519 if( is_main_loop() ) st->print("main of N%d", _idx ); | |
520 if( is_post_loop() ) st->print("post of N%d", _main_idx ); | |
521 } | |
522 #endif | |
523 | |
524 //============================================================================= | |
525 int CountedLoopEndNode::stride_con() const { | |
526 return stride()->bottom_type()->is_int()->get_con(); | |
527 } | |
528 | |
529 | |
530 //----------------------match_incr_with_optional_truncation-------------------- | |
531 // Match increment with optional truncation: | |
532 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16 | |
533 // Return NULL for failure. Success returns the increment node. | |
534 Node* CountedLoopNode::match_incr_with_optional_truncation( | |
535 Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) { | |
536 // Quick cutouts: | |
537 if (expr == NULL || expr->req() != 3) return false; | |
538 | |
539 Node *t1 = NULL; | |
540 Node *t2 = NULL; | |
541 const TypeInt* trunc_t = TypeInt::INT; | |
542 Node* n1 = expr; | |
543 int n1op = n1->Opcode(); | |
544 | |
545 // Try to strip (n1 & M) or (n1 << N >> N) from n1. | |
546 if (n1op == Op_AndI && | |
547 n1->in(2)->is_Con() && | |
548 n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) { | |
549 // %%% This check should match any mask of 2**K-1. | |
550 t1 = n1; | |
551 n1 = t1->in(1); | |
552 n1op = n1->Opcode(); | |
553 trunc_t = TypeInt::CHAR; | |
554 } else if (n1op == Op_RShiftI && | |
555 n1->in(1) != NULL && | |
556 n1->in(1)->Opcode() == Op_LShiftI && | |
557 n1->in(2) == n1->in(1)->in(2) && | |
558 n1->in(2)->is_Con()) { | |
559 jint shift = n1->in(2)->bottom_type()->is_int()->get_con(); | |
560 // %%% This check should match any shift in [1..31]. | |
561 if (shift == 16 || shift == 8) { | |
562 t1 = n1; | |
563 t2 = t1->in(1); | |
564 n1 = t2->in(1); | |
565 n1op = n1->Opcode(); | |
566 if (shift == 16) { | |
567 trunc_t = TypeInt::SHORT; | |
568 } else if (shift == 8) { | |
569 trunc_t = TypeInt::BYTE; | |
570 } | |
571 } | |
572 } | |
573 | |
574 // If (maybe after stripping) it is an AddI, we won: | |
575 if (n1op == Op_AddI) { | |
576 *trunc1 = t1; | |
577 *trunc2 = t2; | |
578 *trunc_type = trunc_t; | |
579 return n1; | |
580 } | |
581 | |
582 // failed | |
583 return NULL; | |
584 } | |
585 | |
586 | |
587 //------------------------------filtered_type-------------------------------- | |
588 // Return a type based on condition control flow | |
589 // A successful return will be a type that is restricted due | |
590 // to a series of dominating if-tests, such as: | |
591 // if (i < 10) { | |
592 // if (i > 0) { | |
593 // here: "i" type is [1..10) | |
594 // } | |
595 // } | |
596 // or a control flow merge | |
597 // if (i < 10) { | |
598 // do { | |
599 // phi( , ) -- at top of loop type is [min_int..10) | |
600 // i = ? | |
601 // } while ( i < 10) | |
602 // | |
603 const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) { | |
604 assert(n && n->bottom_type()->is_int(), "must be int"); | |
605 const TypeInt* filtered_t = NULL; | |
606 if (!n->is_Phi()) { | |
607 assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control"); | |
608 filtered_t = filtered_type_from_dominators(n, n_ctrl); | |
609 | |
610 } else { | |
611 Node* phi = n->as_Phi(); | |
612 Node* region = phi->in(0); | |
613 assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region"); | |
614 if (region && region != C->top()) { | |
615 for (uint i = 1; i < phi->req(); i++) { | |
616 Node* val = phi->in(i); | |
617 Node* use_c = region->in(i); | |
618 const TypeInt* val_t = filtered_type_from_dominators(val, use_c); | |
619 if (val_t != NULL) { | |
620 if (filtered_t == NULL) { | |
621 filtered_t = val_t; | |
622 } else { | |
623 filtered_t = filtered_t->meet(val_t)->is_int(); | |
624 } | |
625 } | |
626 } | |
627 } | |
628 } | |
629 const TypeInt* n_t = _igvn.type(n)->is_int(); | |
630 if (filtered_t != NULL) { | |
631 n_t = n_t->join(filtered_t)->is_int(); | |
632 } | |
633 return n_t; | |
634 } | |
635 | |
636 | |
637 //------------------------------filtered_type_from_dominators-------------------------------- | |
638 // Return a possibly more restrictive type for val based on condition control flow of dominators | |
639 const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) { | |
640 if (val->is_Con()) { | |
641 return val->bottom_type()->is_int(); | |
642 } | |
643 uint if_limit = 10; // Max number of dominating if's visited | |
644 const TypeInt* rtn_t = NULL; | |
645 | |
646 if (use_ctrl && use_ctrl != C->top()) { | |
647 Node* val_ctrl = get_ctrl(val); | |
648 uint val_dom_depth = dom_depth(val_ctrl); | |
649 Node* pred = use_ctrl; | |
650 uint if_cnt = 0; | |
651 while (if_cnt < if_limit) { | |
652 if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) { | |
653 if_cnt++; | |
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654 const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred); |
0 | 655 if (if_t != NULL) { |
656 if (rtn_t == NULL) { | |
657 rtn_t = if_t; | |
658 } else { | |
659 rtn_t = rtn_t->join(if_t)->is_int(); | |
660 } | |
661 } | |
662 } | |
663 pred = idom(pred); | |
664 if (pred == NULL || pred == C->top()) { | |
665 break; | |
666 } | |
667 // Stop if going beyond definition block of val | |
668 if (dom_depth(pred) < val_dom_depth) { | |
669 break; | |
670 } | |
671 } | |
672 } | |
673 return rtn_t; | |
674 } | |
675 | |
676 | |
677 //------------------------------dump_spec-------------------------------------- | |
678 // Dump special per-node info | |
679 #ifndef PRODUCT | |
680 void CountedLoopEndNode::dump_spec(outputStream *st) const { | |
681 if( in(TestValue)->is_Bool() ) { | |
682 BoolTest bt( test_trip()); // Added this for g++. | |
683 | |
684 st->print("["); | |
685 bt.dump_on(st); | |
686 st->print("]"); | |
687 } | |
688 st->print(" "); | |
689 IfNode::dump_spec(st); | |
690 } | |
691 #endif | |
692 | |
693 //============================================================================= | |
694 //------------------------------is_member-------------------------------------- | |
695 // Is 'l' a member of 'this'? | |
696 int IdealLoopTree::is_member( const IdealLoopTree *l ) const { | |
697 while( l->_nest > _nest ) l = l->_parent; | |
698 return l == this; | |
699 } | |
700 | |
701 //------------------------------set_nest--------------------------------------- | |
702 // Set loop tree nesting depth. Accumulate _has_call bits. | |
703 int IdealLoopTree::set_nest( uint depth ) { | |
704 _nest = depth; | |
705 int bits = _has_call; | |
706 if( _child ) bits |= _child->set_nest(depth+1); | |
707 if( bits ) _has_call = 1; | |
708 if( _next ) bits |= _next ->set_nest(depth ); | |
709 return bits; | |
710 } | |
711 | |
712 //------------------------------split_fall_in---------------------------------- | |
713 // Split out multiple fall-in edges from the loop header. Move them to a | |
714 // private RegionNode before the loop. This becomes the loop landing pad. | |
715 void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) { | |
716 PhaseIterGVN &igvn = phase->_igvn; | |
717 uint i; | |
718 | |
719 // Make a new RegionNode to be the landing pad. | |
720 Node *landing_pad = new (phase->C, fall_in_cnt+1) RegionNode( fall_in_cnt+1 ); | |
721 phase->set_loop(landing_pad,_parent); | |
722 // Gather all the fall-in control paths into the landing pad | |
723 uint icnt = fall_in_cnt; | |
724 uint oreq = _head->req(); | |
725 for( i = oreq-1; i>0; i-- ) | |
726 if( !phase->is_member( this, _head->in(i) ) ) | |
727 landing_pad->set_req(icnt--,_head->in(i)); | |
728 | |
729 // Peel off PhiNode edges as well | |
730 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) { | |
731 Node *oj = _head->fast_out(j); | |
732 if( oj->is_Phi() ) { | |
733 PhiNode* old_phi = oj->as_Phi(); | |
734 assert( old_phi->region() == _head, "" ); | |
735 igvn.hash_delete(old_phi); // Yank from hash before hacking edges | |
736 Node *p = PhiNode::make_blank(landing_pad, old_phi); | |
737 uint icnt = fall_in_cnt; | |
738 for( i = oreq-1; i>0; i-- ) { | |
739 if( !phase->is_member( this, _head->in(i) ) ) { | |
740 p->init_req(icnt--, old_phi->in(i)); | |
741 // Go ahead and clean out old edges from old phi | |
742 old_phi->del_req(i); | |
743 } | |
744 } | |
745 // Search for CSE's here, because ZKM.jar does a lot of | |
746 // loop hackery and we need to be a little incremental | |
747 // with the CSE to avoid O(N^2) node blow-up. | |
748 Node *p2 = igvn.hash_find_insert(p); // Look for a CSE | |
749 if( p2 ) { // Found CSE | |
750 p->destruct(); // Recover useless new node | |
751 p = p2; // Use old node | |
752 } else { | |
753 igvn.register_new_node_with_optimizer(p, old_phi); | |
754 } | |
755 // Make old Phi refer to new Phi. | |
756 old_phi->add_req(p); | |
757 // Check for the special case of making the old phi useless and | |
758 // disappear it. In JavaGrande I have a case where this useless | |
759 // Phi is the loop limit and prevents recognizing a CountedLoop | |
760 // which in turn prevents removing an empty loop. | |
761 Node *id_old_phi = old_phi->Identity( &igvn ); | |
762 if( id_old_phi != old_phi ) { // Found a simple identity? | |
763 // Note that I cannot call 'subsume_node' here, because | |
764 // that will yank the edge from old_phi to the Region and | |
765 // I'm mid-iteration over the Region's uses. | |
766 for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) { | |
767 Node* use = old_phi->last_out(i); | |
768 igvn.hash_delete(use); | |
769 igvn._worklist.push(use); | |
770 uint uses_found = 0; | |
771 for (uint j = 0; j < use->len(); j++) { | |
772 if (use->in(j) == old_phi) { | |
773 if (j < use->req()) use->set_req (j, id_old_phi); | |
774 else use->set_prec(j, id_old_phi); | |
775 uses_found++; | |
776 } | |
777 } | |
778 i -= uses_found; // we deleted 1 or more copies of this edge | |
779 } | |
780 } | |
781 igvn._worklist.push(old_phi); | |
782 } | |
783 } | |
784 // Finally clean out the fall-in edges from the RegionNode | |
785 for( i = oreq-1; i>0; i-- ) { | |
786 if( !phase->is_member( this, _head->in(i) ) ) { | |
787 _head->del_req(i); | |
788 } | |
789 } | |
790 // Transform landing pad | |
791 igvn.register_new_node_with_optimizer(landing_pad, _head); | |
792 // Insert landing pad into the header | |
793 _head->add_req(landing_pad); | |
794 } | |
795 | |
796 //------------------------------split_outer_loop------------------------------- | |
797 // Split out the outermost loop from this shared header. | |
798 void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) { | |
799 PhaseIterGVN &igvn = phase->_igvn; | |
800 | |
801 // Find index of outermost loop; it should also be my tail. | |
802 uint outer_idx = 1; | |
803 while( _head->in(outer_idx) != _tail ) outer_idx++; | |
804 | |
805 // Make a LoopNode for the outermost loop. | |
806 Node *ctl = _head->in(LoopNode::EntryControl); | |
807 Node *outer = new (phase->C, 3) LoopNode( ctl, _head->in(outer_idx) ); | |
808 outer = igvn.register_new_node_with_optimizer(outer, _head); | |
809 phase->set_created_loop_node(); | |
810 // Outermost loop falls into '_head' loop | |
811 _head->set_req(LoopNode::EntryControl, outer); | |
812 _head->del_req(outer_idx); | |
813 // Split all the Phis up between '_head' loop and 'outer' loop. | |
814 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) { | |
815 Node *out = _head->fast_out(j); | |
816 if( out->is_Phi() ) { | |
817 PhiNode *old_phi = out->as_Phi(); | |
818 assert( old_phi->region() == _head, "" ); | |
819 Node *phi = PhiNode::make_blank(outer, old_phi); | |
820 phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl)); | |
821 phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx)); | |
822 phi = igvn.register_new_node_with_optimizer(phi, old_phi); | |
823 // Make old Phi point to new Phi on the fall-in path | |
824 igvn.hash_delete(old_phi); | |
825 old_phi->set_req(LoopNode::EntryControl, phi); | |
826 old_phi->del_req(outer_idx); | |
827 igvn._worklist.push(old_phi); | |
828 } | |
829 } | |
830 | |
831 // Use the new loop head instead of the old shared one | |
832 _head = outer; | |
833 phase->set_loop(_head, this); | |
834 } | |
835 | |
836 //------------------------------fix_parent------------------------------------- | |
837 static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) { | |
838 loop->_parent = parent; | |
839 if( loop->_child ) fix_parent( loop->_child, loop ); | |
840 if( loop->_next ) fix_parent( loop->_next , parent ); | |
841 } | |
842 | |
843 //------------------------------estimate_path_freq----------------------------- | |
844 static float estimate_path_freq( Node *n ) { | |
845 // Try to extract some path frequency info | |
846 IfNode *iff; | |
847 for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests | |
848 uint nop = n->Opcode(); | |
849 if( nop == Op_SafePoint ) { // Skip any safepoint | |
850 n = n->in(0); | |
851 continue; | |
852 } | |
853 if( nop == Op_CatchProj ) { // Get count from a prior call | |
854 // Assume call does not always throw exceptions: means the call-site | |
855 // count is also the frequency of the fall-through path. | |
856 assert( n->is_CatchProj(), "" ); | |
857 if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index ) | |
858 return 0.0f; // Assume call exception path is rare | |
859 Node *call = n->in(0)->in(0)->in(0); | |
860 assert( call->is_Call(), "expect a call here" ); | |
861 const JVMState *jvms = ((CallNode*)call)->jvms(); | |
862 ciMethodData* methodData = jvms->method()->method_data(); | |
863 if (!methodData->is_mature()) return 0.0f; // No call-site data | |
864 ciProfileData* data = methodData->bci_to_data(jvms->bci()); | |
865 if ((data == NULL) || !data->is_CounterData()) { | |
866 // no call profile available, try call's control input | |
867 n = n->in(0); | |
868 continue; | |
869 } | |
870 return data->as_CounterData()->count()/FreqCountInvocations; | |
871 } | |
872 // See if there's a gating IF test | |
873 Node *n_c = n->in(0); | |
874 if( !n_c->is_If() ) break; // No estimate available | |
875 iff = n_c->as_If(); | |
876 if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count? | |
877 // Compute how much count comes on this path | |
878 return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt; | |
879 // Have no count info. Skip dull uncommon-trap like branches. | |
880 if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) || | |
881 (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) ) | |
882 break; | |
883 // Skip through never-taken branch; look for a real loop exit. | |
884 n = iff->in(0); | |
885 } | |
886 return 0.0f; // No estimate available | |
887 } | |
888 | |
889 //------------------------------merge_many_backedges--------------------------- | |
890 // Merge all the backedges from the shared header into a private Region. | |
891 // Feed that region as the one backedge to this loop. | |
892 void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) { | |
893 uint i; | |
894 | |
895 // Scan for the top 2 hottest backedges | |
896 float hotcnt = 0.0f; | |
897 float warmcnt = 0.0f; | |
898 uint hot_idx = 0; | |
899 // Loop starts at 2 because slot 1 is the fall-in path | |
900 for( i = 2; i < _head->req(); i++ ) { | |
901 float cnt = estimate_path_freq(_head->in(i)); | |
902 if( cnt > hotcnt ) { // Grab hottest path | |
903 warmcnt = hotcnt; | |
904 hotcnt = cnt; | |
905 hot_idx = i; | |
906 } else if( cnt > warmcnt ) { // And 2nd hottest path | |
907 warmcnt = cnt; | |
908 } | |
909 } | |
910 | |
911 // See if the hottest backedge is worthy of being an inner loop | |
912 // by being much hotter than the next hottest backedge. | |
913 if( hotcnt <= 0.0001 || | |
914 hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge | |
915 | |
916 // Peel out the backedges into a private merge point; peel | |
917 // them all except optionally hot_idx. | |
918 PhaseIterGVN &igvn = phase->_igvn; | |
919 | |
920 Node *hot_tail = NULL; | |
921 // Make a Region for the merge point | |
922 Node *r = new (phase->C, 1) RegionNode(1); | |
923 for( i = 2; i < _head->req(); i++ ) { | |
924 if( i != hot_idx ) | |
925 r->add_req( _head->in(i) ); | |
926 else hot_tail = _head->in(i); | |
927 } | |
928 igvn.register_new_node_with_optimizer(r, _head); | |
929 // Plug region into end of loop _head, followed by hot_tail | |
930 while( _head->req() > 3 ) _head->del_req( _head->req()-1 ); | |
931 _head->set_req(2, r); | |
932 if( hot_idx ) _head->add_req(hot_tail); | |
933 | |
934 // Split all the Phis up between '_head' loop and the Region 'r' | |
935 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) { | |
936 Node *out = _head->fast_out(j); | |
937 if( out->is_Phi() ) { | |
938 PhiNode* n = out->as_Phi(); | |
939 igvn.hash_delete(n); // Delete from hash before hacking edges | |
940 Node *hot_phi = NULL; | |
941 Node *phi = new (phase->C, r->req()) PhiNode(r, n->type(), n->adr_type()); | |
942 // Check all inputs for the ones to peel out | |
943 uint j = 1; | |
944 for( uint i = 2; i < n->req(); i++ ) { | |
945 if( i != hot_idx ) | |
946 phi->set_req( j++, n->in(i) ); | |
947 else hot_phi = n->in(i); | |
948 } | |
949 // Register the phi but do not transform until whole place transforms | |
950 igvn.register_new_node_with_optimizer(phi, n); | |
951 // Add the merge phi to the old Phi | |
952 while( n->req() > 3 ) n->del_req( n->req()-1 ); | |
953 n->set_req(2, phi); | |
954 if( hot_idx ) n->add_req(hot_phi); | |
955 } | |
956 } | |
957 | |
958 | |
959 // Insert a new IdealLoopTree inserted below me. Turn it into a clone | |
960 // of self loop tree. Turn self into a loop headed by _head and with | |
961 // tail being the new merge point. | |
962 IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail ); | |
963 phase->set_loop(_tail,ilt); // Adjust tail | |
964 _tail = r; // Self's tail is new merge point | |
965 phase->set_loop(r,this); | |
966 ilt->_child = _child; // New guy has my children | |
967 _child = ilt; // Self has new guy as only child | |
968 ilt->_parent = this; // new guy has self for parent | |
969 ilt->_nest = _nest; // Same nesting depth (for now) | |
970 | |
971 // Starting with 'ilt', look for child loop trees using the same shared | |
972 // header. Flatten these out; they will no longer be loops in the end. | |
973 IdealLoopTree **pilt = &_child; | |
974 while( ilt ) { | |
975 if( ilt->_head == _head ) { | |
976 uint i; | |
977 for( i = 2; i < _head->req(); i++ ) | |
978 if( _head->in(i) == ilt->_tail ) | |
979 break; // Still a loop | |
980 if( i == _head->req() ) { // No longer a loop | |
981 // Flatten ilt. Hang ilt's "_next" list from the end of | |
982 // ilt's '_child' list. Move the ilt's _child up to replace ilt. | |
983 IdealLoopTree **cp = &ilt->_child; | |
984 while( *cp ) cp = &(*cp)->_next; // Find end of child list | |
985 *cp = ilt->_next; // Hang next list at end of child list | |
986 *pilt = ilt->_child; // Move child up to replace ilt | |
987 ilt->_head = NULL; // Flag as a loop UNIONED into parent | |
988 ilt = ilt->_child; // Repeat using new ilt | |
989 continue; // do not advance over ilt->_child | |
990 } | |
991 assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" ); | |
992 phase->set_loop(_head,ilt); | |
993 } | |
994 pilt = &ilt->_child; // Advance to next | |
995 ilt = *pilt; | |
996 } | |
997 | |
998 if( _child ) fix_parent( _child, this ); | |
999 } | |
1000 | |
1001 //------------------------------beautify_loops--------------------------------- | |
1002 // Split shared headers and insert loop landing pads. | |
1003 // Insert a LoopNode to replace the RegionNode. | |
1004 // Return TRUE if loop tree is structurally changed. | |
1005 bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) { | |
1006 bool result = false; | |
1007 // Cache parts in locals for easy | |
1008 PhaseIterGVN &igvn = phase->_igvn; | |
1009 | |
1010 phase->C->print_method("Before beautify loops", 3); | |
1011 | |
1012 igvn.hash_delete(_head); // Yank from hash before hacking edges | |
1013 | |
1014 // Check for multiple fall-in paths. Peel off a landing pad if need be. | |
1015 int fall_in_cnt = 0; | |
1016 for( uint i = 1; i < _head->req(); i++ ) | |
1017 if( !phase->is_member( this, _head->in(i) ) ) | |
1018 fall_in_cnt++; | |
1019 assert( fall_in_cnt, "at least 1 fall-in path" ); | |
1020 if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins | |
1021 split_fall_in( phase, fall_in_cnt ); | |
1022 | |
1023 // Swap inputs to the _head and all Phis to move the fall-in edge to | |
1024 // the left. | |
1025 fall_in_cnt = 1; | |
1026 while( phase->is_member( this, _head->in(fall_in_cnt) ) ) | |
1027 fall_in_cnt++; | |
1028 if( fall_in_cnt > 1 ) { | |
1029 // Since I am just swapping inputs I do not need to update def-use info | |
1030 Node *tmp = _head->in(1); | |
1031 _head->set_req( 1, _head->in(fall_in_cnt) ); | |
1032 _head->set_req( fall_in_cnt, tmp ); | |
1033 // Swap also all Phis | |
1034 for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) { | |
1035 Node* phi = _head->fast_out(i); | |
1036 if( phi->is_Phi() ) { | |
1037 igvn.hash_delete(phi); // Yank from hash before hacking edges | |
1038 tmp = phi->in(1); | |
1039 phi->set_req( 1, phi->in(fall_in_cnt) ); | |
1040 phi->set_req( fall_in_cnt, tmp ); | |
1041 } | |
1042 } | |
1043 } | |
1044 assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" ); | |
1045 assert( phase->is_member( this, _head->in(2) ), "right edge is loop" ); | |
1046 | |
1047 // If I am a shared header (multiple backedges), peel off the many | |
1048 // backedges into a private merge point and use the merge point as | |
1049 // the one true backedge. | |
1050 if( _head->req() > 3 ) { | |
1051 // Merge the many backedges into a single backedge. | |
1052 merge_many_backedges( phase ); | |
1053 result = true; | |
1054 } | |
1055 | |
1056 // If I am a shared header (multiple backedges), peel off myself loop. | |
1057 // I better be the outermost loop. | |
1058 if( _head->req() > 3 ) { | |
1059 split_outer_loop( phase ); | |
1060 result = true; | |
1061 | |
1062 } else if( !_head->is_Loop() && !_irreducible ) { | |
1063 // Make a new LoopNode to replace the old loop head | |
1064 Node *l = new (phase->C, 3) LoopNode( _head->in(1), _head->in(2) ); | |
1065 l = igvn.register_new_node_with_optimizer(l, _head); | |
1066 phase->set_created_loop_node(); | |
1067 // Go ahead and replace _head | |
1068 phase->_igvn.subsume_node( _head, l ); | |
1069 _head = l; | |
1070 phase->set_loop(_head, this); | |
1071 for (DUIterator_Fast imax, i = l->fast_outs(imax); i < imax; i++) | |
1072 phase->_igvn.add_users_to_worklist(l->fast_out(i)); | |
1073 } | |
1074 | |
1075 // Now recursively beautify nested loops | |
1076 if( _child ) result |= _child->beautify_loops( phase ); | |
1077 if( _next ) result |= _next ->beautify_loops( phase ); | |
1078 return result; | |
1079 } | |
1080 | |
1081 //------------------------------allpaths_check_safepts---------------------------- | |
1082 // Allpaths backwards scan from loop tail, terminating each path at first safepoint | |
1083 // encountered. Helper for check_safepts. | |
1084 void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) { | |
1085 assert(stack.size() == 0, "empty stack"); | |
1086 stack.push(_tail); | |
1087 visited.Clear(); | |
1088 visited.set(_tail->_idx); | |
1089 while (stack.size() > 0) { | |
1090 Node* n = stack.pop(); | |
1091 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) { | |
1092 // Terminate this path | |
1093 } else if (n->Opcode() == Op_SafePoint) { | |
1094 if (_phase->get_loop(n) != this) { | |
1095 if (_required_safept == NULL) _required_safept = new Node_List(); | |
1096 _required_safept->push(n); // save the one closest to the tail | |
1097 } | |
1098 // Terminate this path | |
1099 } else { | |
1100 uint start = n->is_Region() ? 1 : 0; | |
1101 uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1; | |
1102 for (uint i = start; i < end; i++) { | |
1103 Node* in = n->in(i); | |
1104 assert(in->is_CFG(), "must be"); | |
1105 if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) { | |
1106 stack.push(in); | |
1107 } | |
1108 } | |
1109 } | |
1110 } | |
1111 } | |
1112 | |
1113 //------------------------------check_safepts---------------------------- | |
1114 // Given dominators, try to find loops with calls that must always be | |
1115 // executed (call dominates loop tail). These loops do not need non-call | |
1116 // safepoints (ncsfpt). | |
1117 // | |
1118 // A complication is that a safepoint in a inner loop may be needed | |
1119 // by an outer loop. In the following, the inner loop sees it has a | |
1120 // call (block 3) on every path from the head (block 2) to the | |
1121 // backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint) | |
1122 // in block 2, _but_ this leaves the outer loop without a safepoint. | |
1123 // | |
1124 // entry 0 | |
1125 // | | |
1126 // v | |
1127 // outer 1,2 +->1 | |
1128 // | | | |
1129 // | v | |
1130 // | 2<---+ ncsfpt in 2 | |
1131 // |_/|\ | | |
1132 // | v | | |
1133 // inner 2,3 / 3 | call in 3 | |
1134 // / | | | |
1135 // v +--+ | |
1136 // exit 4 | |
1137 // | |
1138 // | |
1139 // This method creates a list (_required_safept) of ncsfpt nodes that must | |
1140 // be protected is created for each loop. When a ncsfpt maybe deleted, it | |
1141 // is first looked for in the lists for the outer loops of the current loop. | |
1142 // | |
1143 // The insights into the problem: | |
1144 // A) counted loops are okay | |
1145 // B) innermost loops are okay (only an inner loop can delete | |
1146 // a ncsfpt needed by an outer loop) | |
1147 // C) a loop is immune from an inner loop deleting a safepoint | |
1148 // if the loop has a call on the idom-path | |
1149 // D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the | |
1150 // idom-path that is not in a nested loop | |
1151 // E) otherwise, an ncsfpt on the idom-path that is nested in an inner | |
1152 // loop needs to be prevented from deletion by an inner loop | |
1153 // | |
1154 // There are two analyses: | |
1155 // 1) The first, and cheaper one, scans the loop body from | |
1156 // tail to head following the idom (immediate dominator) | |
1157 // chain, looking for the cases (C,D,E) above. | |
1158 // Since inner loops are scanned before outer loops, there is summary | |
1159 // information about inner loops. Inner loops can be skipped over | |
1160 // when the tail of an inner loop is encountered. | |
1161 // | |
1162 // 2) The second, invoked if the first fails to find a call or ncsfpt on | |
1163 // the idom path (which is rare), scans all predecessor control paths | |
1164 // from the tail to the head, terminating a path when a call or sfpt | |
1165 // is encountered, to find the ncsfpt's that are closest to the tail. | |
1166 // | |
1167 void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) { | |
1168 // Bottom up traversal | |
1169 IdealLoopTree* ch = _child; | |
1170 while (ch != NULL) { | |
1171 ch->check_safepts(visited, stack); | |
1172 ch = ch->_next; | |
1173 } | |
1174 | |
1175 if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) { | |
1176 bool has_call = false; // call on dom-path | |
1177 bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth | |
1178 Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth | |
1179 // Scan the dom-path nodes from tail to head | |
1180 for (Node* n = tail(); n != _head; n = _phase->idom(n)) { | |
1181 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) { | |
1182 has_call = true; | |
1183 _has_sfpt = 1; // Then no need for a safept! | |
1184 break; | |
1185 } else if (n->Opcode() == Op_SafePoint) { | |
1186 if (_phase->get_loop(n) == this) { | |
1187 has_local_ncsfpt = true; | |
1188 break; | |
1189 } | |
1190 if (nonlocal_ncsfpt == NULL) { | |
1191 nonlocal_ncsfpt = n; // save the one closest to the tail | |
1192 } | |
1193 } else { | |
1194 IdealLoopTree* nlpt = _phase->get_loop(n); | |
1195 if (this != nlpt) { | |
1196 // If at an inner loop tail, see if the inner loop has already | |
1197 // recorded seeing a call on the dom-path (and stop.) If not, | |
1198 // jump to the head of the inner loop. | |
1199 assert(is_member(nlpt), "nested loop"); | |
1200 Node* tail = nlpt->_tail; | |
1201 if (tail->in(0)->is_If()) tail = tail->in(0); | |
1202 if (n == tail) { | |
1203 // If inner loop has call on dom-path, so does outer loop | |
1204 if (nlpt->_has_sfpt) { | |
1205 has_call = true; | |
1206 _has_sfpt = 1; | |
1207 break; | |
1208 } | |
1209 // Skip to head of inner loop | |
1210 assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head"); | |
1211 n = nlpt->_head; | |
1212 } | |
1213 } | |
1214 } | |
1215 } | |
1216 // Record safept's that this loop needs preserved when an | |
1217 // inner loop attempts to delete it's safepoints. | |
1218 if (_child != NULL && !has_call && !has_local_ncsfpt) { | |
1219 if (nonlocal_ncsfpt != NULL) { | |
1220 if (_required_safept == NULL) _required_safept = new Node_List(); | |
1221 _required_safept->push(nonlocal_ncsfpt); | |
1222 } else { | |
1223 // Failed to find a suitable safept on the dom-path. Now use | |
1224 // an all paths walk from tail to head, looking for safepoints to preserve. | |
1225 allpaths_check_safepts(visited, stack); | |
1226 } | |
1227 } | |
1228 } | |
1229 } | |
1230 | |
1231 //---------------------------is_deleteable_safept---------------------------- | |
1232 // Is safept not required by an outer loop? | |
1233 bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) { | |
1234 assert(sfpt->Opcode() == Op_SafePoint, ""); | |
1235 IdealLoopTree* lp = get_loop(sfpt)->_parent; | |
1236 while (lp != NULL) { | |
1237 Node_List* sfpts = lp->_required_safept; | |
1238 if (sfpts != NULL) { | |
1239 for (uint i = 0; i < sfpts->size(); i++) { | |
1240 if (sfpt == sfpts->at(i)) | |
1241 return false; | |
1242 } | |
1243 } | |
1244 lp = lp->_parent; | |
1245 } | |
1246 return true; | |
1247 } | |
1248 | |
1249 //------------------------------counted_loop----------------------------------- | |
1250 // Convert to counted loops where possible | |
1251 void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) { | |
1252 | |
1253 // For grins, set the inner-loop flag here | |
1254 if( !_child ) { | |
1255 if( _head->is_Loop() ) _head->as_Loop()->set_inner_loop(); | |
1256 } | |
1257 | |
1258 if( _head->is_CountedLoop() || | |
1259 phase->is_counted_loop( _head, this ) ) { | |
1260 _has_sfpt = 1; // Indicate we do not need a safepoint here | |
1261 | |
1262 // Look for a safepoint to remove | |
1263 for (Node* n = tail(); n != _head; n = phase->idom(n)) | |
1264 if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this && | |
1265 phase->is_deleteable_safept(n)) | |
1266 phase->lazy_replace(n,n->in(TypeFunc::Control)); | |
1267 | |
1268 CountedLoopNode *cl = _head->as_CountedLoop(); | |
1269 Node *incr = cl->incr(); | |
1270 if( !incr ) return; // Dead loop? | |
1271 Node *init = cl->init_trip(); | |
1272 Node *phi = cl->phi(); | |
1273 // protect against stride not being a constant | |
1274 if( !cl->stride_is_con() ) return; | |
1275 int stride_con = cl->stride_con(); | |
1276 | |
1277 // Look for induction variables | |
1278 | |
1279 // Visit all children, looking for Phis | |
1280 for (DUIterator i = cl->outs(); cl->has_out(i); i++) { | |
1281 Node *out = cl->out(i); | |
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1282 if (!out->is_Phi() || out == phi) continue; // Looking for other phis |
0 | 1283 PhiNode* phi2 = out->as_Phi(); |
1284 Node *incr2 = phi2->in( LoopNode::LoopBackControl ); | |
1285 // Look for induction variables of the form: X += constant | |
1286 if( phi2->region() != _head || | |
1287 incr2->req() != 3 || | |
1288 incr2->in(1) != phi2 || | |
1289 incr2 == incr || | |
1290 incr2->Opcode() != Op_AddI || | |
1291 !incr2->in(2)->is_Con() ) | |
1292 continue; | |
1293 | |
1294 // Check for parallel induction variable (parallel to trip counter) | |
1295 // via an affine function. In particular, count-down loops with | |
1296 // count-up array indices are common. We only RCE references off | |
1297 // the trip-counter, so we need to convert all these to trip-counter | |
1298 // expressions. | |
1299 Node *init2 = phi2->in( LoopNode::EntryControl ); | |
1300 int stride_con2 = incr2->in(2)->get_int(); | |
1301 | |
1302 // The general case here gets a little tricky. We want to find the | |
1303 // GCD of all possible parallel IV's and make a new IV using this | |
1304 // GCD for the loop. Then all possible IVs are simple multiples of | |
1305 // the GCD. In practice, this will cover very few extra loops. | |
1306 // Instead we require 'stride_con2' to be a multiple of 'stride_con', | |
1307 // where +/-1 is the common case, but other integer multiples are | |
1308 // also easy to handle. | |
1309 int ratio_con = stride_con2/stride_con; | |
1310 | |
1311 if( ratio_con * stride_con == stride_con2 ) { // Check for exact | |
1312 // Convert to using the trip counter. The parallel induction | |
1313 // variable differs from the trip counter by a loop-invariant | |
1314 // amount, the difference between their respective initial values. | |
1315 // It is scaled by the 'ratio_con'. | |
1316 Compile* C = phase->C; | |
1317 Node* ratio = phase->_igvn.intcon(ratio_con); | |
1318 phase->set_ctrl(ratio, C->root()); | |
1319 Node* ratio_init = new (C, 3) MulINode(init, ratio); | |
1320 phase->_igvn.register_new_node_with_optimizer(ratio_init, init); | |
1321 phase->set_early_ctrl(ratio_init); | |
1322 Node* diff = new (C, 3) SubINode(init2, ratio_init); | |
1323 phase->_igvn.register_new_node_with_optimizer(diff, init2); | |
1324 phase->set_early_ctrl(diff); | |
1325 Node* ratio_idx = new (C, 3) MulINode(phi, ratio); | |
1326 phase->_igvn.register_new_node_with_optimizer(ratio_idx, phi); | |
1327 phase->set_ctrl(ratio_idx, cl); | |
1328 Node* add = new (C, 3) AddINode(ratio_idx, diff); | |
1329 phase->_igvn.register_new_node_with_optimizer(add); | |
1330 phase->set_ctrl(add, cl); | |
1331 phase->_igvn.hash_delete( phi2 ); | |
1332 phase->_igvn.subsume_node( phi2, add ); | |
1333 // Sometimes an induction variable is unused | |
1334 if (add->outcnt() == 0) { | |
1335 phase->_igvn.remove_dead_node(add); | |
1336 } | |
1337 --i; // deleted this phi; rescan starting with next position | |
1338 continue; | |
1339 } | |
1340 } | |
1341 } else if (_parent != NULL && !_irreducible) { | |
1342 // Not a counted loop. | |
1343 // Look for a safepoint on the idom-path to remove, preserving the first one | |
1344 bool found = false; | |
1345 Node* n = tail(); | |
1346 for (; n != _head && !found; n = phase->idom(n)) { | |
1347 if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this) | |
1348 found = true; // Found one | |
1349 } | |
1350 // Skip past it and delete the others | |
1351 for (; n != _head; n = phase->idom(n)) { | |
1352 if (n->Opcode() == Op_SafePoint && phase->get_loop(n) == this && | |
1353 phase->is_deleteable_safept(n)) | |
1354 phase->lazy_replace(n,n->in(TypeFunc::Control)); | |
1355 } | |
1356 } | |
1357 | |
1358 // Recursively | |
1359 if( _child ) _child->counted_loop( phase ); | |
1360 if( _next ) _next ->counted_loop( phase ); | |
1361 } | |
1362 | |
1363 #ifndef PRODUCT | |
1364 //------------------------------dump_head-------------------------------------- | |
1365 // Dump 1 liner for loop header info | |
1366 void IdealLoopTree::dump_head( ) const { | |
1367 for( uint i=0; i<_nest; i++ ) | |
1368 tty->print(" "); | |
1369 tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx); | |
1370 if( _irreducible ) tty->print(" IRREDUCIBLE"); | |
1371 if( _head->is_CountedLoop() ) { | |
1372 CountedLoopNode *cl = _head->as_CountedLoop(); | |
1373 tty->print(" counted"); | |
1374 if( cl->is_pre_loop () ) tty->print(" pre" ); | |
1375 if( cl->is_main_loop() ) tty->print(" main"); | |
1376 if( cl->is_post_loop() ) tty->print(" post"); | |
1377 } | |
1378 tty->cr(); | |
1379 } | |
1380 | |
1381 //------------------------------dump------------------------------------------- | |
1382 // Dump loops by loop tree | |
1383 void IdealLoopTree::dump( ) const { | |
1384 dump_head(); | |
1385 if( _child ) _child->dump(); | |
1386 if( _next ) _next ->dump(); | |
1387 } | |
1388 | |
1389 #endif | |
1390 | |
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1391 static void log_loop_tree(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) { |
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1392 if (loop == root) { |
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1393 if (loop->_child != NULL) { |
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1394 log->begin_head("loop_tree"); |
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1395 log->end_head(); |
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1396 if( loop->_child ) log_loop_tree(root, loop->_child, log); |
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1397 log->tail("loop_tree"); |
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1398 assert(loop->_next == NULL, "what?"); |
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1399 } |
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1400 } else { |
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1401 Node* head = loop->_head; |
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1402 log->begin_head("loop"); |
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1403 log->print(" idx='%d' ", head->_idx); |
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1404 if (loop->_irreducible) log->print("irreducible='1' "); |
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1405 if (head->is_Loop()) { |
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1406 if (head->as_Loop()->is_inner_loop()) log->print("inner_loop='1' "); |
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1407 if (head->as_Loop()->is_partial_peel_loop()) log->print("partial_peel_loop='1' "); |
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1408 } |
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1409 if (head->is_CountedLoop()) { |
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1410 CountedLoopNode* cl = head->as_CountedLoop(); |
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1411 if (cl->is_pre_loop()) log->print("pre_loop='%d' ", cl->main_idx()); |
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1412 if (cl->is_main_loop()) log->print("main_loop='%d' ", cl->_idx); |
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1413 if (cl->is_post_loop()) log->print("post_loop='%d' ", cl->main_idx()); |
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1414 } |
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1415 log->end_head(); |
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1416 if( loop->_child ) log_loop_tree(root, loop->_child, log); |
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1417 log->tail("loop"); |
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1418 if( loop->_next ) log_loop_tree(root, loop->_next, log); |
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1419 } |
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1420 } |
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1421 |
0 | 1422 //============================================================================= |
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1423 //----------------------------build_and_optimize------------------------------- |
0 | 1424 // Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to |
1425 // its corresponding LoopNode. If 'optimize' is true, do some loop cleanups. | |
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1426 void PhaseIdealLoop::build_and_optimize(bool do_split_ifs) { |
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1427 int old_progress = C->major_progress(); |
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1428 |
0 | 1429 // Reset major-progress flag for the driver's heuristics |
1430 C->clear_major_progress(); | |
1431 | |
1432 #ifndef PRODUCT | |
1433 // Capture for later assert | |
1434 uint unique = C->unique(); | |
1435 _loop_invokes++; | |
1436 _loop_work += unique; | |
1437 #endif | |
1438 | |
1439 // True if the method has at least 1 irreducible loop | |
1440 _has_irreducible_loops = false; | |
1441 | |
1442 _created_loop_node = false; | |
1443 | |
1444 Arena *a = Thread::current()->resource_area(); | |
1445 VectorSet visited(a); | |
1446 // Pre-grow the mapping from Nodes to IdealLoopTrees. | |
1447 _nodes.map(C->unique(), NULL); | |
1448 memset(_nodes.adr(), 0, wordSize * C->unique()); | |
1449 | |
1450 // Pre-build the top-level outermost loop tree entry | |
1451 _ltree_root = new IdealLoopTree( this, C->root(), C->root() ); | |
1452 // Do not need a safepoint at the top level | |
1453 _ltree_root->_has_sfpt = 1; | |
1454 | |
1455 // Empty pre-order array | |
1456 allocate_preorders(); | |
1457 | |
1458 // Build a loop tree on the fly. Build a mapping from CFG nodes to | |
1459 // IdealLoopTree entries. Data nodes are NOT walked. | |
1460 build_loop_tree(); | |
1461 // Check for bailout, and return | |
1462 if (C->failing()) { | |
1463 return; | |
1464 } | |
1465 | |
1466 // No loops after all | |
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1467 if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false); |
0 | 1468 |
1469 // There should always be an outer loop containing the Root and Return nodes. | |
1470 // If not, we have a degenerate empty program. Bail out in this case. | |
1471 if (!has_node(C->root())) { | |
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1472 if (!_verify_only) { |
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1473 C->clear_major_progress(); |
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1474 C->record_method_not_compilable("empty program detected during loop optimization"); |
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1475 } |
0 | 1476 return; |
1477 } | |
1478 | |
1479 // Nothing to do, so get out | |
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1480 if( !C->has_loops() && !do_split_ifs && !_verify_me && !_verify_only ) { |
0 | 1481 _igvn.optimize(); // Cleanup NeverBranches |
1482 return; | |
1483 } | |
1484 | |
1485 // Set loop nesting depth | |
1486 _ltree_root->set_nest( 0 ); | |
1487 | |
1488 // Split shared headers and insert loop landing pads. | |
1489 // Do not bother doing this on the Root loop of course. | |
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1490 if( !_verify_me && !_verify_only && _ltree_root->_child ) { |
0 | 1491 if( _ltree_root->_child->beautify_loops( this ) ) { |
1492 // Re-build loop tree! | |
1493 _ltree_root->_child = NULL; | |
1494 _nodes.clear(); | |
1495 reallocate_preorders(); | |
1496 build_loop_tree(); | |
1497 // Check for bailout, and return | |
1498 if (C->failing()) { | |
1499 return; | |
1500 } | |
1501 // Reset loop nesting depth | |
1502 _ltree_root->set_nest( 0 ); | |
222 | 1503 |
1504 C->print_method("After beautify loops", 3); | |
0 | 1505 } |
1506 } | |
1507 | |
1508 // Build Dominators for elision of NULL checks & loop finding. | |
1509 // Since nodes do not have a slot for immediate dominator, make | |
605 | 1510 // a persistent side array for that info indexed on node->_idx. |
0 | 1511 _idom_size = C->unique(); |
1512 _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size ); | |
1513 _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size ); | |
1514 _dom_stk = NULL; // Allocated on demand in recompute_dom_depth | |
1515 memset( _dom_depth, 0, _idom_size * sizeof(uint) ); | |
1516 | |
1517 Dominators(); | |
1518 | |
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1519 if (!_verify_only) { |
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1520 // As a side effect, Dominators removed any unreachable CFG paths |
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1521 // into RegionNodes. It doesn't do this test against Root, so |
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1522 // we do it here. |
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1523 for( uint i = 1; i < C->root()->req(); i++ ) { |
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1524 if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root? |
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1525 _igvn.hash_delete(C->root()); |
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1526 C->root()->del_req(i); |
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1527 _igvn._worklist.push(C->root()); |
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1528 i--; // Rerun same iteration on compressed edges |
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1529 } |
0 | 1530 } |
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1531 |
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1532 // Given dominators, try to find inner loops with calls that must |
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1533 // always be executed (call dominates loop tail). These loops do |
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1534 // not need a separate safepoint. |
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1535 Node_List cisstack(a); |
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1536 _ltree_root->check_safepts(visited, cisstack); |
0 | 1537 } |
1538 | |
1539 // Walk the DATA nodes and place into loops. Find earliest control | |
1540 // node. For CFG nodes, the _nodes array starts out and remains | |
1541 // holding the associated IdealLoopTree pointer. For DATA nodes, the | |
1542 // _nodes array holds the earliest legal controlling CFG node. | |
1543 | |
1544 // Allocate stack with enough space to avoid frequent realloc | |
1545 int stack_size = (C->unique() >> 1) + 16; // (unique>>1)+16 from Java2D stats | |
1546 Node_Stack nstack( a, stack_size ); | |
1547 | |
1548 visited.Clear(); | |
1549 Node_List worklist(a); | |
1550 // Don't need C->root() on worklist since | |
1551 // it will be processed among C->top() inputs | |
1552 worklist.push( C->top() ); | |
1553 visited.set( C->top()->_idx ); // Set C->top() as visited now | |
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1554 build_loop_early( visited, worklist, nstack ); |
0 | 1555 |
1556 // Given early legal placement, try finding counted loops. This placement | |
1557 // is good enough to discover most loop invariants. | |
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1558 if( !_verify_me && !_verify_only ) |
0 | 1559 _ltree_root->counted_loop( this ); |
1560 | |
1561 // Find latest loop placement. Find ideal loop placement. | |
1562 visited.Clear(); | |
1563 init_dom_lca_tags(); | |
1564 // Need C->root() on worklist when processing outs | |
1565 worklist.push( C->root() ); | |
1566 NOT_PRODUCT( C->verify_graph_edges(); ) | |
1567 worklist.push( C->top() ); | |
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1568 build_loop_late( visited, worklist, nstack ); |
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1569 |
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1570 if (_verify_only) { |
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1571 // restore major progress flag |
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1572 for (int i = 0; i < old_progress; i++) |
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1573 C->set_major_progress(); |
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1574 assert(C->unique() == unique, "verification mode made Nodes? ? ?"); |
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1575 assert(_igvn._worklist.size() == 0, "shouldn't push anything"); |
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1576 return; |
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1577 } |
0 | 1578 |
1579 // clear out the dead code | |
1580 while(_deadlist.size()) { | |
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1581 _igvn.remove_globally_dead_node(_deadlist.pop()); |
0 | 1582 } |
1583 | |
1584 #ifndef PRODUCT | |
1585 C->verify_graph_edges(); | |
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1586 if( _verify_me ) { // Nested verify pass? |
0 | 1587 // Check to see if the verify mode is broken |
1588 assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?"); | |
1589 return; | |
1590 } | |
1591 if( VerifyLoopOptimizations ) verify(); | |
1592 #endif | |
1593 | |
1594 if (ReassociateInvariants) { | |
1595 // Reassociate invariants and prep for split_thru_phi | |
1596 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { | |
1597 IdealLoopTree* lpt = iter.current(); | |
1598 if (!lpt->is_counted() || !lpt->is_inner()) continue; | |
1599 | |
1600 lpt->reassociate_invariants(this); | |
1601 | |
1602 // Because RCE opportunities can be masked by split_thru_phi, | |
1603 // look for RCE candidates and inhibit split_thru_phi | |
1604 // on just their loop-phi's for this pass of loop opts | |
1605 if( SplitIfBlocks && do_split_ifs ) { | |
1606 if (lpt->policy_range_check(this)) { | |
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1607 lpt->_rce_candidate = 1; // = true |
0 | 1608 } |
1609 } | |
1610 } | |
1611 } | |
1612 | |
1613 // Check for aggressive application of split-if and other transforms | |
1614 // that require basic-block info (like cloning through Phi's) | |
1615 if( SplitIfBlocks && do_split_ifs ) { | |
1616 visited.Clear(); | |
1617 split_if_with_blocks( visited, nstack ); | |
1618 NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); ); | |
1619 } | |
1620 | |
1621 // Perform iteration-splitting on inner loops. Split iterations to avoid | |
1622 // range checks or one-shot null checks. | |
1623 | |
1624 // If split-if's didn't hack the graph too bad (no CFG changes) | |
1625 // then do loop opts. | |
1626 if( C->has_loops() && !C->major_progress() ) { | |
1627 memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) ); | |
1628 _ltree_root->_child->iteration_split( this, worklist ); | |
1629 // No verify after peeling! GCM has hoisted code out of the loop. | |
1630 // After peeling, the hoisted code could sink inside the peeled area. | |
1631 // The peeling code does not try to recompute the best location for | |
1632 // all the code before the peeled area, so the verify pass will always | |
1633 // complain about it. | |
1634 } | |
1635 // Do verify graph edges in any case | |
1636 NOT_PRODUCT( C->verify_graph_edges(); ); | |
1637 | |
1638 if( !do_split_ifs ) { | |
1639 // We saw major progress in Split-If to get here. We forced a | |
1640 // pass with unrolling and not split-if, however more split-if's | |
1641 // might make progress. If the unrolling didn't make progress | |
1642 // then the major-progress flag got cleared and we won't try | |
1643 // another round of Split-If. In particular the ever-common | |
1644 // instance-of/check-cast pattern requires at least 2 rounds of | |
1645 // Split-If to clear out. | |
1646 C->set_major_progress(); | |
1647 } | |
1648 | |
1649 // Repeat loop optimizations if new loops were seen | |
1650 if (created_loop_node()) { | |
1651 C->set_major_progress(); | |
1652 } | |
1653 | |
1654 // Convert scalar to superword operations | |
1655 | |
1656 if (UseSuperWord && C->has_loops() && !C->major_progress()) { | |
1657 // SuperWord transform | |
1658 SuperWord sw(this); | |
1659 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { | |
1660 IdealLoopTree* lpt = iter.current(); | |
1661 if (lpt->is_counted()) { | |
1662 sw.transform_loop(lpt); | |
1663 } | |
1664 } | |
1665 } | |
1666 | |
1667 // Cleanup any modified bits | |
1668 _igvn.optimize(); | |
1669 | |
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1670 // disable assert until issue with split_flow_path is resolved (6742111) |
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1671 // assert(!_has_irreducible_loops || C->parsed_irreducible_loop() || C->is_osr_compilation(), |
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1672 // "shouldn't introduce irreducible loops"); |
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1673 |
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1674 if (C->log() != NULL) { |
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1675 log_loop_tree(_ltree_root, _ltree_root, C->log()); |
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1676 } |
0 | 1677 } |
1678 | |
1679 #ifndef PRODUCT | |
1680 //------------------------------print_statistics------------------------------- | |
1681 int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes | |
1682 int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique | |
1683 void PhaseIdealLoop::print_statistics() { | |
1684 tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work); | |
1685 } | |
1686 | |
1687 //------------------------------verify----------------------------------------- | |
1688 // Build a verify-only PhaseIdealLoop, and see that it agrees with me. | |
1689 static int fail; // debug only, so its multi-thread dont care | |
1690 void PhaseIdealLoop::verify() const { | |
1691 int old_progress = C->major_progress(); | |
1692 ResourceMark rm; | |
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1693 PhaseIdealLoop loop_verify( _igvn, this ); |
0 | 1694 VectorSet visited(Thread::current()->resource_area()); |
1695 | |
1696 fail = 0; | |
1697 verify_compare( C->root(), &loop_verify, visited ); | |
1698 assert( fail == 0, "verify loops failed" ); | |
1699 // Verify loop structure is the same | |
1700 _ltree_root->verify_tree(loop_verify._ltree_root, NULL); | |
1701 // Reset major-progress. It was cleared by creating a verify version of | |
1702 // PhaseIdealLoop. | |
1703 for( int i=0; i<old_progress; i++ ) | |
1704 C->set_major_progress(); | |
1705 } | |
1706 | |
1707 //------------------------------verify_compare--------------------------------- | |
1708 // Make sure me and the given PhaseIdealLoop agree on key data structures | |
1709 void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const { | |
1710 if( !n ) return; | |
1711 if( visited.test_set( n->_idx ) ) return; | |
1712 if( !_nodes[n->_idx] ) { // Unreachable | |
1713 assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" ); | |
1714 return; | |
1715 } | |
1716 | |
1717 uint i; | |
1718 for( i = 0; i < n->req(); i++ ) | |
1719 verify_compare( n->in(i), loop_verify, visited ); | |
1720 | |
1721 // Check the '_nodes' block/loop structure | |
1722 i = n->_idx; | |
1723 if( has_ctrl(n) ) { // We have control; verify has loop or ctrl | |
1724 if( _nodes[i] != loop_verify->_nodes[i] && | |
1725 get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) { | |
1726 tty->print("Mismatched control setting for: "); | |
1727 n->dump(); | |
1728 if( fail++ > 10 ) return; | |
1729 Node *c = get_ctrl_no_update(n); | |
1730 tty->print("We have it as: "); | |
1731 if( c->in(0) ) c->dump(); | |
1732 else tty->print_cr("N%d",c->_idx); | |
1733 tty->print("Verify thinks: "); | |
1734 if( loop_verify->has_ctrl(n) ) | |
1735 loop_verify->get_ctrl_no_update(n)->dump(); | |
1736 else | |
1737 loop_verify->get_loop_idx(n)->dump(); | |
1738 tty->cr(); | |
1739 } | |
1740 } else { // We have a loop | |
1741 IdealLoopTree *us = get_loop_idx(n); | |
1742 if( loop_verify->has_ctrl(n) ) { | |
1743 tty->print("Mismatched loop setting for: "); | |
1744 n->dump(); | |
1745 if( fail++ > 10 ) return; | |
1746 tty->print("We have it as: "); | |
1747 us->dump(); | |
1748 tty->print("Verify thinks: "); | |
1749 loop_verify->get_ctrl_no_update(n)->dump(); | |
1750 tty->cr(); | |
1751 } else if (!C->major_progress()) { | |
1752 // Loop selection can be messed up if we did a major progress | |
1753 // operation, like split-if. Do not verify in that case. | |
1754 IdealLoopTree *them = loop_verify->get_loop_idx(n); | |
1755 if( us->_head != them->_head || us->_tail != them->_tail ) { | |
1756 tty->print("Unequals loops for: "); | |
1757 n->dump(); | |
1758 if( fail++ > 10 ) return; | |
1759 tty->print("We have it as: "); | |
1760 us->dump(); | |
1761 tty->print("Verify thinks: "); | |
1762 them->dump(); | |
1763 tty->cr(); | |
1764 } | |
1765 } | |
1766 } | |
1767 | |
1768 // Check for immediate dominators being equal | |
1769 if( i >= _idom_size ) { | |
1770 if( !n->is_CFG() ) return; | |
1771 tty->print("CFG Node with no idom: "); | |
1772 n->dump(); | |
1773 return; | |
1774 } | |
1775 if( !n->is_CFG() ) return; | |
1776 if( n == C->root() ) return; // No IDOM here | |
1777 | |
1778 assert(n->_idx == i, "sanity"); | |
1779 Node *id = idom_no_update(n); | |
1780 if( id != loop_verify->idom_no_update(n) ) { | |
1781 tty->print("Unequals idoms for: "); | |
1782 n->dump(); | |
1783 if( fail++ > 10 ) return; | |
1784 tty->print("We have it as: "); | |
1785 id->dump(); | |
1786 tty->print("Verify thinks: "); | |
1787 loop_verify->idom_no_update(n)->dump(); | |
1788 tty->cr(); | |
1789 } | |
1790 | |
1791 } | |
1792 | |
1793 //------------------------------verify_tree------------------------------------ | |
1794 // Verify that tree structures match. Because the CFG can change, siblings | |
1795 // within the loop tree can be reordered. We attempt to deal with that by | |
1796 // reordering the verify's loop tree if possible. | |
1797 void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const { | |
1798 assert( _parent == parent, "Badly formed loop tree" ); | |
1799 | |
1800 // Siblings not in same order? Attempt to re-order. | |
1801 if( _head != loop->_head ) { | |
1802 // Find _next pointer to update | |
1803 IdealLoopTree **pp = &loop->_parent->_child; | |
1804 while( *pp != loop ) | |
1805 pp = &((*pp)->_next); | |
1806 // Find proper sibling to be next | |
1807 IdealLoopTree **nn = &loop->_next; | |
1808 while( (*nn) && (*nn)->_head != _head ) | |
1809 nn = &((*nn)->_next); | |
1810 | |
1811 // Check for no match. | |
1812 if( !(*nn) ) { | |
1813 // Annoyingly, irreducible loops can pick different headers | |
1814 // after a major_progress operation, so the rest of the loop | |
1815 // tree cannot be matched. | |
1816 if (_irreducible && Compile::current()->major_progress()) return; | |
1817 assert( 0, "failed to match loop tree" ); | |
1818 } | |
1819 | |
1820 // Move (*nn) to (*pp) | |
1821 IdealLoopTree *hit = *nn; | |
1822 *nn = hit->_next; | |
1823 hit->_next = loop; | |
1824 *pp = loop; | |
1825 loop = hit; | |
1826 // Now try again to verify | |
1827 } | |
1828 | |
1829 assert( _head == loop->_head , "mismatched loop head" ); | |
1830 Node *tail = _tail; // Inline a non-updating version of | |
1831 while( !tail->in(0) ) // the 'tail()' call. | |
1832 tail = tail->in(1); | |
1833 assert( tail == loop->_tail, "mismatched loop tail" ); | |
1834 | |
1835 // Counted loops that are guarded should be able to find their guards | |
1836 if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) { | |
1837 CountedLoopNode *cl = _head->as_CountedLoop(); | |
1838 Node *init = cl->init_trip(); | |
1839 Node *ctrl = cl->in(LoopNode::EntryControl); | |
1840 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" ); | |
1841 Node *iff = ctrl->in(0); | |
1842 assert( iff->Opcode() == Op_If, "" ); | |
1843 Node *bol = iff->in(1); | |
1844 assert( bol->Opcode() == Op_Bool, "" ); | |
1845 Node *cmp = bol->in(1); | |
1846 assert( cmp->Opcode() == Op_CmpI, "" ); | |
1847 Node *add = cmp->in(1); | |
1848 Node *opaq; | |
1849 if( add->Opcode() == Op_Opaque1 ) { | |
1850 opaq = add; | |
1851 } else { | |
1852 assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" ); | |
1853 assert( add == init, "" ); | |
1854 opaq = cmp->in(2); | |
1855 } | |
1856 assert( opaq->Opcode() == Op_Opaque1, "" ); | |
1857 | |
1858 } | |
1859 | |
1860 if (_child != NULL) _child->verify_tree(loop->_child, this); | |
1861 if (_next != NULL) _next ->verify_tree(loop->_next, parent); | |
1862 // Innermost loops need to verify loop bodies, | |
1863 // but only if no 'major_progress' | |
1864 int fail = 0; | |
1865 if (!Compile::current()->major_progress() && _child == NULL) { | |
1866 for( uint i = 0; i < _body.size(); i++ ) { | |
1867 Node *n = _body.at(i); | |
1868 if (n->outcnt() == 0) continue; // Ignore dead | |
1869 uint j; | |
1870 for( j = 0; j < loop->_body.size(); j++ ) | |
1871 if( loop->_body.at(j) == n ) | |
1872 break; | |
1873 if( j == loop->_body.size() ) { // Not found in loop body | |
1874 // Last ditch effort to avoid assertion: Its possible that we | |
1875 // have some users (so outcnt not zero) but are still dead. | |
1876 // Try to find from root. | |
1877 if (Compile::current()->root()->find(n->_idx)) { | |
1878 fail++; | |
1879 tty->print("We have that verify does not: "); | |
1880 n->dump(); | |
1881 } | |
1882 } | |
1883 } | |
1884 for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) { | |
1885 Node *n = loop->_body.at(i2); | |
1886 if (n->outcnt() == 0) continue; // Ignore dead | |
1887 uint j; | |
1888 for( j = 0; j < _body.size(); j++ ) | |
1889 if( _body.at(j) == n ) | |
1890 break; | |
1891 if( j == _body.size() ) { // Not found in loop body | |
1892 // Last ditch effort to avoid assertion: Its possible that we | |
1893 // have some users (so outcnt not zero) but are still dead. | |
1894 // Try to find from root. | |
1895 if (Compile::current()->root()->find(n->_idx)) { | |
1896 fail++; | |
1897 tty->print("Verify has that we do not: "); | |
1898 n->dump(); | |
1899 } | |
1900 } | |
1901 } | |
1902 assert( !fail, "loop body mismatch" ); | |
1903 } | |
1904 } | |
1905 | |
1906 #endif | |
1907 | |
1908 //------------------------------set_idom--------------------------------------- | |
1909 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) { | |
1910 uint idx = d->_idx; | |
1911 if (idx >= _idom_size) { | |
1912 uint newsize = _idom_size<<1; | |
1913 while( idx >= newsize ) { | |
1914 newsize <<= 1; | |
1915 } | |
1916 _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize); | |
1917 _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize); | |
1918 memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) ); | |
1919 _idom_size = newsize; | |
1920 } | |
1921 _idom[idx] = n; | |
1922 _dom_depth[idx] = dom_depth; | |
1923 } | |
1924 | |
1925 //------------------------------recompute_dom_depth--------------------------------------- | |
1926 // The dominator tree is constructed with only parent pointers. | |
1927 // This recomputes the depth in the tree by first tagging all | |
1928 // nodes as "no depth yet" marker. The next pass then runs up | |
1929 // the dom tree from each node marked "no depth yet", and computes | |
1930 // the depth on the way back down. | |
1931 void PhaseIdealLoop::recompute_dom_depth() { | |
1932 uint no_depth_marker = C->unique(); | |
1933 uint i; | |
1934 // Initialize depth to "no depth yet" | |
1935 for (i = 0; i < _idom_size; i++) { | |
1936 if (_dom_depth[i] > 0 && _idom[i] != NULL) { | |
1937 _dom_depth[i] = no_depth_marker; | |
1938 } | |
1939 } | |
1940 if (_dom_stk == NULL) { | |
1941 uint init_size = C->unique() / 100; // Guess that 1/100 is a reasonable initial size. | |
1942 if (init_size < 10) init_size = 10; | |
1943 _dom_stk = new (C->node_arena()) GrowableArray<uint>(C->node_arena(), init_size, 0, 0); | |
1944 } | |
1945 // Compute new depth for each node. | |
1946 for (i = 0; i < _idom_size; i++) { | |
1947 uint j = i; | |
1948 // Run up the dom tree to find a node with a depth | |
1949 while (_dom_depth[j] == no_depth_marker) { | |
1950 _dom_stk->push(j); | |
1951 j = _idom[j]->_idx; | |
1952 } | |
1953 // Compute the depth on the way back down this tree branch | |
1954 uint dd = _dom_depth[j] + 1; | |
1955 while (_dom_stk->length() > 0) { | |
1956 uint j = _dom_stk->pop(); | |
1957 _dom_depth[j] = dd; | |
1958 dd++; | |
1959 } | |
1960 } | |
1961 } | |
1962 | |
1963 //------------------------------sort------------------------------------------- | |
1964 // Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the | |
1965 // loop tree, not the root. | |
1966 IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) { | |
1967 if( !innermost ) return loop; // New innermost loop | |
1968 | |
1969 int loop_preorder = get_preorder(loop->_head); // Cache pre-order number | |
1970 assert( loop_preorder, "not yet post-walked loop" ); | |
1971 IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer | |
1972 IdealLoopTree *l = *pp; // Do I go before or after 'l'? | |
1973 | |
1974 // Insert at start of list | |
1975 while( l ) { // Insertion sort based on pre-order | |
1976 if( l == loop ) return innermost; // Already on list! | |
1977 int l_preorder = get_preorder(l->_head); // Cache pre-order number | |
1978 assert( l_preorder, "not yet post-walked l" ); | |
1979 // Check header pre-order number to figure proper nesting | |
1980 if( loop_preorder > l_preorder ) | |
1981 break; // End of insertion | |
1982 // If headers tie (e.g., shared headers) check tail pre-order numbers. | |
1983 // Since I split shared headers, you'd think this could not happen. | |
1984 // BUT: I must first do the preorder numbering before I can discover I | |
1985 // have shared headers, so the split headers all get the same preorder | |
1986 // number as the RegionNode they split from. | |
1987 if( loop_preorder == l_preorder && | |
1988 get_preorder(loop->_tail) < get_preorder(l->_tail) ) | |
1989 break; // Also check for shared headers (same pre#) | |
1990 pp = &l->_parent; // Chain up list | |
1991 l = *pp; | |
1992 } | |
1993 // Link into list | |
1994 // Point predecessor to me | |
1995 *pp = loop; | |
1996 // Point me to successor | |
1997 IdealLoopTree *p = loop->_parent; | |
1998 loop->_parent = l; // Point me to successor | |
1999 if( p ) sort( p, innermost ); // Insert my parents into list as well | |
2000 return innermost; | |
2001 } | |
2002 | |
2003 //------------------------------build_loop_tree-------------------------------- | |
2004 // I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit | |
2005 // bits. The _nodes[] array is mapped by Node index and holds a NULL for | |
2006 // not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the | |
2007 // tightest enclosing IdealLoopTree for post-walked. | |
2008 // | |
2009 // During my forward walk I do a short 1-layer lookahead to see if I can find | |
2010 // a loop backedge with that doesn't have any work on the backedge. This | |
2011 // helps me construct nested loops with shared headers better. | |
2012 // | |
2013 // Once I've done the forward recursion, I do the post-work. For each child | |
2014 // I check to see if there is a backedge. Backedges define a loop! I | |
2015 // insert an IdealLoopTree at the target of the backedge. | |
2016 // | |
2017 // During the post-work I also check to see if I have several children | |
2018 // belonging to different loops. If so, then this Node is a decision point | |
2019 // where control flow can choose to change loop nests. It is at this | |
2020 // decision point where I can figure out how loops are nested. At this | |
2021 // time I can properly order the different loop nests from my children. | |
2022 // Note that there may not be any backedges at the decision point! | |
2023 // | |
2024 // Since the decision point can be far removed from the backedges, I can't | |
2025 // order my loops at the time I discover them. Thus at the decision point | |
2026 // I need to inspect loop header pre-order numbers to properly nest my | |
2027 // loops. This means I need to sort my childrens' loops by pre-order. | |
2028 // The sort is of size number-of-control-children, which generally limits | |
2029 // it to size 2 (i.e., I just choose between my 2 target loops). | |
2030 void PhaseIdealLoop::build_loop_tree() { | |
2031 // Allocate stack of size C->unique()/2 to avoid frequent realloc | |
2032 GrowableArray <Node *> bltstack(C->unique() >> 1); | |
2033 Node *n = C->root(); | |
2034 bltstack.push(n); | |
2035 int pre_order = 1; | |
2036 int stack_size; | |
2037 | |
2038 while ( ( stack_size = bltstack.length() ) != 0 ) { | |
2039 n = bltstack.top(); // Leave node on stack | |
2040 if ( !is_visited(n) ) { | |
2041 // ---- Pre-pass Work ---- | |
2042 // Pre-walked but not post-walked nodes need a pre_order number. | |
2043 | |
2044 set_preorder_visited( n, pre_order ); // set as visited | |
2045 | |
2046 // ---- Scan over children ---- | |
2047 // Scan first over control projections that lead to loop headers. | |
2048 // This helps us find inner-to-outer loops with shared headers better. | |
2049 | |
2050 // Scan children's children for loop headers. | |
2051 for ( int i = n->outcnt() - 1; i >= 0; --i ) { | |
2052 Node* m = n->raw_out(i); // Child | |
2053 if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children | |
2054 // Scan over children's children to find loop | |
2055 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { | |
2056 Node* l = m->fast_out(j); | |
2057 if( is_visited(l) && // Been visited? | |
2058 !is_postvisited(l) && // But not post-visited | |
2059 get_preorder(l) < pre_order ) { // And smaller pre-order | |
2060 // Found! Scan the DFS down this path before doing other paths | |
2061 bltstack.push(m); | |
2062 break; | |
2063 } | |
2064 } | |
2065 } | |
2066 } | |
2067 pre_order++; | |
2068 } | |
2069 else if ( !is_postvisited(n) ) { | |
2070 // Note: build_loop_tree_impl() adds out edges on rare occasions, | |
2071 // such as com.sun.rsasign.am::a. | |
2072 // For non-recursive version, first, process current children. | |
2073 // On next iteration, check if additional children were added. | |
2074 for ( int k = n->outcnt() - 1; k >= 0; --k ) { | |
2075 Node* u = n->raw_out(k); | |
2076 if ( u->is_CFG() && !is_visited(u) ) { | |
2077 bltstack.push(u); | |
2078 } | |
2079 } | |
2080 if ( bltstack.length() == stack_size ) { | |
2081 // There were no additional children, post visit node now | |
2082 (void)bltstack.pop(); // Remove node from stack | |
2083 pre_order = build_loop_tree_impl( n, pre_order ); | |
2084 // Check for bailout | |
2085 if (C->failing()) { | |
2086 return; | |
2087 } | |
2088 // Check to grow _preorders[] array for the case when | |
2089 // build_loop_tree_impl() adds new nodes. | |
2090 check_grow_preorders(); | |
2091 } | |
2092 } | |
2093 else { | |
2094 (void)bltstack.pop(); // Remove post-visited node from stack | |
2095 } | |
2096 } | |
2097 } | |
2098 | |
2099 //------------------------------build_loop_tree_impl--------------------------- | |
2100 int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) { | |
2101 // ---- Post-pass Work ---- | |
2102 // Pre-walked but not post-walked nodes need a pre_order number. | |
2103 | |
2104 // Tightest enclosing loop for this Node | |
2105 IdealLoopTree *innermost = NULL; | |
2106 | |
2107 // For all children, see if any edge is a backedge. If so, make a loop | |
2108 // for it. Then find the tightest enclosing loop for the self Node. | |
2109 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) { | |
2110 Node* m = n->fast_out(i); // Child | |
2111 if( n == m ) continue; // Ignore control self-cycles | |
2112 if( !m->is_CFG() ) continue;// Ignore non-CFG edges | |
2113 | |
2114 IdealLoopTree *l; // Child's loop | |
2115 if( !is_postvisited(m) ) { // Child visited but not post-visited? | |
2116 // Found a backedge | |
2117 assert( get_preorder(m) < pre_order, "should be backedge" ); | |
2118 // Check for the RootNode, which is already a LoopNode and is allowed | |
2119 // to have multiple "backedges". | |
2120 if( m == C->root()) { // Found the root? | |
2121 l = _ltree_root; // Root is the outermost LoopNode | |
2122 } else { // Else found a nested loop | |
2123 // Insert a LoopNode to mark this loop. | |
2124 l = new IdealLoopTree(this, m, n); | |
2125 } // End of Else found a nested loop | |
2126 if( !has_loop(m) ) // If 'm' does not already have a loop set | |
2127 set_loop(m, l); // Set loop header to loop now | |
2128 | |
2129 } else { // Else not a nested loop | |
2130 if( !_nodes[m->_idx] ) continue; // Dead code has no loop | |
2131 l = get_loop(m); // Get previously determined loop | |
2132 // If successor is header of a loop (nest), move up-loop till it | |
2133 // is a member of some outer enclosing loop. Since there are no | |
2134 // shared headers (I've split them already) I only need to go up | |
2135 // at most 1 level. | |
2136 while( l && l->_head == m ) // Successor heads loop? | |
2137 l = l->_parent; // Move up 1 for me | |
2138 // If this loop is not properly parented, then this loop | |
2139 // has no exit path out, i.e. its an infinite loop. | |
2140 if( !l ) { | |
2141 // Make loop "reachable" from root so the CFG is reachable. Basically | |
2142 // insert a bogus loop exit that is never taken. 'm', the loop head, | |
2143 // points to 'n', one (of possibly many) fall-in paths. There may be | |
2144 // many backedges as well. | |
2145 | |
2146 // Here I set the loop to be the root loop. I could have, after | |
2147 // inserting a bogus loop exit, restarted the recursion and found my | |
2148 // new loop exit. This would make the infinite loop a first-class | |
2149 // loop and it would then get properly optimized. What's the use of | |
2150 // optimizing an infinite loop? | |
2151 l = _ltree_root; // Oops, found infinite loop | |
2152 | |
921
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2153 if (!_verify_only) { |
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2154 // Insert the NeverBranch between 'm' and it's control user. |
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2155 NeverBranchNode *iff = new (C, 1) NeverBranchNode( m ); |
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2156 _igvn.register_new_node_with_optimizer(iff); |
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2157 set_loop(iff, l); |
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2158 Node *if_t = new (C, 1) CProjNode( iff, 0 ); |
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2159 _igvn.register_new_node_with_optimizer(if_t); |
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2160 set_loop(if_t, l); |
0 | 2161 |
921
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2162 Node* cfg = NULL; // Find the One True Control User of m |
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2163 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) { |
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2164 Node* x = m->fast_out(j); |
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2165 if (x->is_CFG() && x != m && x != iff) |
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2166 { cfg = x; break; } |
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2167 } |
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2168 assert(cfg != NULL, "must find the control user of m"); |
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2169 uint k = 0; // Probably cfg->in(0) |
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2170 while( cfg->in(k) != m ) k++; // But check incase cfg is a Region |
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2171 cfg->set_req( k, if_t ); // Now point to NeverBranch |
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2172 |
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2173 // Now create the never-taken loop exit |
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2174 Node *if_f = new (C, 1) CProjNode( iff, 1 ); |
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2175 _igvn.register_new_node_with_optimizer(if_f); |
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2176 set_loop(if_f, l); |
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2177 // Find frame ptr for Halt. Relies on the optimizer |
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2178 // V-N'ing. Easier and quicker than searching through |
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2179 // the program structure. |
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2180 Node *frame = new (C, 1) ParmNode( C->start(), TypeFunc::FramePtr ); |
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2181 _igvn.register_new_node_with_optimizer(frame); |
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2182 // Halt & Catch Fire |
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2183 Node *halt = new (C, TypeFunc::Parms) HaltNode( if_f, frame ); |
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2184 _igvn.register_new_node_with_optimizer(halt); |
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2185 set_loop(halt, l); |
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2186 C->root()->add_req(halt); |
0 | 2187 } |
2188 set_loop(C->root(), _ltree_root); | |
2189 } | |
2190 } | |
2191 // Weeny check for irreducible. This child was already visited (this | |
2192 // IS the post-work phase). Is this child's loop header post-visited | |
2193 // as well? If so, then I found another entry into the loop. | |
921
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2194 if (!_verify_only) { |
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2195 while( is_postvisited(l->_head) ) { |
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2196 // found irreducible |
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2197 l->_irreducible = 1; // = true |
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2198 l = l->_parent; |
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2199 _has_irreducible_loops = true; |
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2200 // Check for bad CFG here to prevent crash, and bailout of compile |
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2201 if (l == NULL) { |
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2202 C->record_method_not_compilable("unhandled CFG detected during loop optimization"); |
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2203 return pre_order; |
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2204 } |
0 | 2205 } |
2206 } | |
2207 | |
2208 // This Node might be a decision point for loops. It is only if | |
2209 // it's children belong to several different loops. The sort call | |
2210 // does a trivial amount of work if there is only 1 child or all | |
2211 // children belong to the same loop. If however, the children | |
2212 // belong to different loops, the sort call will properly set the | |
2213 // _parent pointers to show how the loops nest. | |
2214 // | |
2215 // In any case, it returns the tightest enclosing loop. | |
2216 innermost = sort( l, innermost ); | |
2217 } | |
2218 | |
2219 // Def-use info will have some dead stuff; dead stuff will have no | |
2220 // loop decided on. | |
2221 | |
2222 // Am I a loop header? If so fix up my parent's child and next ptrs. | |
2223 if( innermost && innermost->_head == n ) { | |
2224 assert( get_loop(n) == innermost, "" ); | |
2225 IdealLoopTree *p = innermost->_parent; | |
2226 IdealLoopTree *l = innermost; | |
2227 while( p && l->_head == n ) { | |
2228 l->_next = p->_child; // Put self on parents 'next child' | |
2229 p->_child = l; // Make self as first child of parent | |
2230 l = p; // Now walk up the parent chain | |
2231 p = l->_parent; | |
2232 } | |
2233 } else { | |
2234 // Note that it is possible for a LoopNode to reach here, if the | |
2235 // backedge has been made unreachable (hence the LoopNode no longer | |
2236 // denotes a Loop, and will eventually be removed). | |
2237 | |
2238 // Record tightest enclosing loop for self. Mark as post-visited. | |
2239 set_loop(n, innermost); | |
2240 // Also record has_call flag early on | |
2241 if( innermost ) { | |
2242 if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) { | |
2243 // Do not count uncommon calls | |
2244 if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) { | |
2245 Node *iff = n->in(0)->in(0); | |
2246 if( !iff->is_If() || | |
2247 (n->in(0)->Opcode() == Op_IfFalse && | |
2248 (1.0 - iff->as_If()->_prob) >= 0.01) || | |
2249 (iff->as_If()->_prob >= 0.01) ) | |
2250 innermost->_has_call = 1; | |
2251 } | |
39
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2252 } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) { |
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2253 // Disable loop optimizations if the loop has a scalar replaceable |
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2254 // allocation. This disabling may cause a potential performance lost |
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2255 // if the allocation is not eliminated for some reason. |
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2256 innermost->_allow_optimizations = false; |
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2257 innermost->_has_call = 1; // = true |
0 | 2258 } |
2259 } | |
2260 } | |
2261 | |
2262 // Flag as post-visited now | |
2263 set_postvisited(n); | |
2264 return pre_order; | |
2265 } | |
2266 | |
2267 | |
2268 //------------------------------build_loop_early------------------------------- | |
2269 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping. | |
2270 // First pass computes the earliest controlling node possible. This is the | |
2271 // controlling input with the deepest dominating depth. | |
921
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2272 void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) { |
0 | 2273 while (worklist.size() != 0) { |
2274 // Use local variables nstack_top_n & nstack_top_i to cache values | |
2275 // on nstack's top. | |
2276 Node *nstack_top_n = worklist.pop(); | |
2277 uint nstack_top_i = 0; | |
2278 //while_nstack_nonempty: | |
2279 while (true) { | |
2280 // Get parent node and next input's index from stack's top. | |
2281 Node *n = nstack_top_n; | |
2282 uint i = nstack_top_i; | |
2283 uint cnt = n->req(); // Count of inputs | |
2284 if (i == 0) { // Pre-process the node. | |
2285 if( has_node(n) && // Have either loop or control already? | |
2286 !has_ctrl(n) ) { // Have loop picked out already? | |
2287 // During "merge_many_backedges" we fold up several nested loops | |
2288 // into a single loop. This makes the members of the original | |
2289 // loop bodies pointing to dead loops; they need to move up | |
2290 // to the new UNION'd larger loop. I set the _head field of these | |
2291 // dead loops to NULL and the _parent field points to the owning | |
2292 // loop. Shades of UNION-FIND algorithm. | |
2293 IdealLoopTree *ilt; | |
2294 while( !(ilt = get_loop(n))->_head ) { | |
2295 // Normally I would use a set_loop here. But in this one special | |
2296 // case, it is legal (and expected) to change what loop a Node | |
2297 // belongs to. | |
2298 _nodes.map(n->_idx, (Node*)(ilt->_parent) ); | |
2299 } | |
2300 // Remove safepoints ONLY if I've already seen I don't need one. | |
2301 // (the old code here would yank a 2nd safepoint after seeing a | |
2302 // first one, even though the 1st did not dominate in the loop body | |
2303 // and thus could be avoided indefinitely) | |
921
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2304 if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint && |
0 | 2305 is_deleteable_safept(n)) { |
2306 Node *in = n->in(TypeFunc::Control); | |
2307 lazy_replace(n,in); // Pull safepoint now | |
2308 // Carry on with the recursion "as if" we are walking | |
2309 // only the control input | |
2310 if( !visited.test_set( in->_idx ) ) { | |
2311 worklist.push(in); // Visit this guy later, using worklist | |
2312 } | |
2313 // Get next node from nstack: | |
2314 // - skip n's inputs processing by setting i > cnt; | |
2315 // - we also will not call set_early_ctrl(n) since | |
2316 // has_node(n) == true (see the condition above). | |
2317 i = cnt + 1; | |
2318 } | |
2319 } | |
2320 } // if (i == 0) | |
2321 | |
2322 // Visit all inputs | |
2323 bool done = true; // Assume all n's inputs will be processed | |
2324 while (i < cnt) { | |
2325 Node *in = n->in(i); | |
2326 ++i; | |
2327 if (in == NULL) continue; | |
2328 if (in->pinned() && !in->is_CFG()) | |
2329 set_ctrl(in, in->in(0)); | |
2330 int is_visited = visited.test_set( in->_idx ); | |
2331 if (!has_node(in)) { // No controlling input yet? | |
2332 assert( !in->is_CFG(), "CFG Node with no controlling input?" ); | |
2333 assert( !is_visited, "visit only once" ); | |
2334 nstack.push(n, i); // Save parent node and next input's index. | |
2335 nstack_top_n = in; // Process current input now. | |
2336 nstack_top_i = 0; | |
2337 done = false; // Not all n's inputs processed. | |
2338 break; // continue while_nstack_nonempty; | |
2339 } else if (!is_visited) { | |
2340 // This guy has a location picked out for him, but has not yet | |
2341 // been visited. Happens to all CFG nodes, for instance. | |
2342 // Visit him using the worklist instead of recursion, to break | |
2343 // cycles. Since he has a location already we do not need to | |
2344 // find his location before proceeding with the current Node. | |
2345 worklist.push(in); // Visit this guy later, using worklist | |
2346 } | |
2347 } | |
2348 if (done) { | |
2349 // All of n's inputs have been processed, complete post-processing. | |
2350 | |
605 | 2351 // Compute earliest point this Node can go. |
0 | 2352 // CFG, Phi, pinned nodes already know their controlling input. |
2353 if (!has_node(n)) { | |
2354 // Record earliest legal location | |
2355 set_early_ctrl( n ); | |
2356 } | |
2357 if (nstack.is_empty()) { | |
2358 // Finished all nodes on stack. | |
2359 // Process next node on the worklist. | |
2360 break; | |
2361 } | |
2362 // Get saved parent node and next input's index. | |
2363 nstack_top_n = nstack.node(); | |
2364 nstack_top_i = nstack.index(); | |
2365 nstack.pop(); | |
2366 } | |
2367 } // while (true) | |
2368 } | |
2369 } | |
2370 | |
2371 //------------------------------dom_lca_internal-------------------------------- | |
2372 // Pair-wise LCA | |
2373 Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const { | |
2374 if( !n1 ) return n2; // Handle NULL original LCA | |
2375 assert( n1->is_CFG(), "" ); | |
2376 assert( n2->is_CFG(), "" ); | |
2377 // find LCA of all uses | |
2378 uint d1 = dom_depth(n1); | |
2379 uint d2 = dom_depth(n2); | |
2380 while (n1 != n2) { | |
2381 if (d1 > d2) { | |
2382 n1 = idom(n1); | |
2383 d1 = dom_depth(n1); | |
2384 } else if (d1 < d2) { | |
2385 n2 = idom(n2); | |
2386 d2 = dom_depth(n2); | |
2387 } else { | |
2388 // Here d1 == d2. Due to edits of the dominator-tree, sections | |
2389 // of the tree might have the same depth. These sections have | |
2390 // to be searched more carefully. | |
2391 | |
2392 // Scan up all the n1's with equal depth, looking for n2. | |
2393 Node *t1 = idom(n1); | |
2394 while (dom_depth(t1) == d1) { | |
2395 if (t1 == n2) return n2; | |
2396 t1 = idom(t1); | |
2397 } | |
2398 // Scan up all the n2's with equal depth, looking for n1. | |
2399 Node *t2 = idom(n2); | |
2400 while (dom_depth(t2) == d2) { | |
2401 if (t2 == n1) return n1; | |
2402 t2 = idom(t2); | |
2403 } | |
2404 // Move up to a new dominator-depth value as well as up the dom-tree. | |
2405 n1 = t1; | |
2406 n2 = t2; | |
2407 d1 = dom_depth(n1); | |
2408 d2 = dom_depth(n2); | |
2409 } | |
2410 } | |
2411 return n1; | |
2412 } | |
2413 | |
2414 //------------------------------compute_idom----------------------------------- | |
2415 // Locally compute IDOM using dom_lca call. Correct only if the incoming | |
2416 // IDOMs are correct. | |
2417 Node *PhaseIdealLoop::compute_idom( Node *region ) const { | |
2418 assert( region->is_Region(), "" ); | |
2419 Node *LCA = NULL; | |
2420 for( uint i = 1; i < region->req(); i++ ) { | |
2421 if( region->in(i) != C->top() ) | |
2422 LCA = dom_lca( LCA, region->in(i) ); | |
2423 } | |
2424 return LCA; | |
2425 } | |
2426 | |
921
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2427 bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) { |
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2428 bool had_error = false; |
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2429 #ifdef ASSERT |
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2430 if (early != C->root()) { |
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2431 // Make sure that there's a dominance path from use to LCA |
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2432 Node* d = use; |
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2433 while (d != LCA) { |
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2434 d = idom(d); |
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2435 if (d == C->root()) { |
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2436 tty->print_cr("*** Use %d isn't dominated by def %s", use->_idx, n->_idx); |
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2437 n->dump(); |
046932b72aa2
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2438 use->dump(); |
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2439 had_error = true; |
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2440 break; |
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|
2441 } |
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|
2442 } |
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2443 } |
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2444 #endif |
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2445 return had_error; |
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2446 } |
0 | 2447 |
921
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2448 |
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2449 Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) { |
0 | 2450 // Compute LCA over list of uses |
921
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2451 bool had_error = false; |
0 | 2452 Node *LCA = NULL; |
2453 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) { | |
2454 Node* c = n->fast_out(i); | |
2455 if (_nodes[c->_idx] == NULL) | |
2456 continue; // Skip the occasional dead node | |
2457 if( c->is_Phi() ) { // For Phis, we must land above on the path | |
2458 for( uint j=1; j<c->req(); j++ ) {// For all inputs | |
2459 if( c->in(j) == n ) { // Found matching input? | |
2460 Node *use = c->in(0)->in(j); | |
921
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2461 if (_verify_only && use->is_top()) continue; |
0 | 2462 LCA = dom_lca_for_get_late_ctrl( LCA, use, n ); |
921
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2463 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error; |
0 | 2464 } |
2465 } | |
2466 } else { | |
2467 // For CFG data-users, use is in the block just prior | |
2468 Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0); | |
2469 LCA = dom_lca_for_get_late_ctrl( LCA, use, n ); | |
921
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2470 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error; |
0 | 2471 } |
2472 } | |
921
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2473 assert(!had_error, "bad dominance"); |
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2474 return LCA; |
046932b72aa2
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2475 } |
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2476 |
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2477 //------------------------------get_late_ctrl---------------------------------- |
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2478 // Compute latest legal control. |
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2479 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) { |
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2480 assert(early != NULL, "early control should not be NULL"); |
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2481 |
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2482 Node* LCA = compute_lca_of_uses(n, early); |
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2483 #ifdef ASSERT |
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2484 if (LCA == C->root() && LCA != early) { |
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2485 // def doesn't dominate uses so print some useful debugging output |
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2486 compute_lca_of_uses(n, early, true); |
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2487 } |
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2488 #endif |
0 | 2489 |
2490 // if this is a load, check for anti-dependent stores | |
2491 // We use a conservative algorithm to identify potential interfering | |
2492 // instructions and for rescheduling the load. The users of the memory | |
2493 // input of this load are examined. Any use which is not a load and is | |
2494 // dominated by early is considered a potentially interfering store. | |
2495 // This can produce false positives. | |
2496 if (n->is_Load() && LCA != early) { | |
2497 Node_List worklist; | |
2498 | |
2499 Node *mem = n->in(MemNode::Memory); | |
2500 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) { | |
2501 Node* s = mem->fast_out(i); | |
2502 worklist.push(s); | |
2503 } | |
2504 while(worklist.size() != 0 && LCA != early) { | |
2505 Node* s = worklist.pop(); | |
2506 if (s->is_Load()) { | |
2507 continue; | |
2508 } else if (s->is_MergeMem()) { | |
2509 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) { | |
2510 Node* s1 = s->fast_out(i); | |
2511 worklist.push(s1); | |
2512 } | |
2513 } else { | |
2514 Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0); | |
2515 assert(sctrl != NULL || s->outcnt() == 0, "must have control"); | |
2516 if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) { | |
2517 LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n); | |
2518 } | |
2519 } | |
2520 } | |
2521 } | |
2522 | |
2523 assert(LCA == find_non_split_ctrl(LCA), "unexpected late control"); | |
2524 return LCA; | |
2525 } | |
2526 | |
2527 // true if CFG node d dominates CFG node n | |
2528 bool PhaseIdealLoop::is_dominator(Node *d, Node *n) { | |
2529 if (d == n) | |
2530 return true; | |
2531 assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes"); | |
2532 uint dd = dom_depth(d); | |
2533 while (dom_depth(n) >= dd) { | |
2534 if (n == d) | |
2535 return true; | |
2536 n = idom(n); | |
2537 } | |
2538 return false; | |
2539 } | |
2540 | |
2541 //------------------------------dom_lca_for_get_late_ctrl_internal------------- | |
2542 // Pair-wise LCA with tags. | |
2543 // Tag each index with the node 'tag' currently being processed | |
2544 // before advancing up the dominator chain using idom(). | |
2545 // Later calls that find a match to 'tag' know that this path has already | |
2546 // been considered in the current LCA (which is input 'n1' by convention). | |
2547 // Since get_late_ctrl() is only called once for each node, the tag array | |
2548 // does not need to be cleared between calls to get_late_ctrl(). | |
2549 // Algorithm trades a larger constant factor for better asymptotic behavior | |
2550 // | |
2551 Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) { | |
2552 uint d1 = dom_depth(n1); | |
2553 uint d2 = dom_depth(n2); | |
2554 | |
2555 do { | |
2556 if (d1 > d2) { | |
2557 // current lca is deeper than n2 | |
2558 _dom_lca_tags.map(n1->_idx, tag); | |
2559 n1 = idom(n1); | |
2560 d1 = dom_depth(n1); | |
2561 } else if (d1 < d2) { | |
2562 // n2 is deeper than current lca | |
2563 Node *memo = _dom_lca_tags[n2->_idx]; | |
2564 if( memo == tag ) { | |
2565 return n1; // Return the current LCA | |
2566 } | |
2567 _dom_lca_tags.map(n2->_idx, tag); | |
2568 n2 = idom(n2); | |
2569 d2 = dom_depth(n2); | |
2570 } else { | |
2571 // Here d1 == d2. Due to edits of the dominator-tree, sections | |
2572 // of the tree might have the same depth. These sections have | |
2573 // to be searched more carefully. | |
2574 | |
2575 // Scan up all the n1's with equal depth, looking for n2. | |
2576 _dom_lca_tags.map(n1->_idx, tag); | |
2577 Node *t1 = idom(n1); | |
2578 while (dom_depth(t1) == d1) { | |
2579 if (t1 == n2) return n2; | |
2580 _dom_lca_tags.map(t1->_idx, tag); | |
2581 t1 = idom(t1); | |
2582 } | |
2583 // Scan up all the n2's with equal depth, looking for n1. | |
2584 _dom_lca_tags.map(n2->_idx, tag); | |
2585 Node *t2 = idom(n2); | |
2586 while (dom_depth(t2) == d2) { | |
2587 if (t2 == n1) return n1; | |
2588 _dom_lca_tags.map(t2->_idx, tag); | |
2589 t2 = idom(t2); | |
2590 } | |
2591 // Move up to a new dominator-depth value as well as up the dom-tree. | |
2592 n1 = t1; | |
2593 n2 = t2; | |
2594 d1 = dom_depth(n1); | |
2595 d2 = dom_depth(n2); | |
2596 } | |
2597 } while (n1 != n2); | |
2598 return n1; | |
2599 } | |
2600 | |
2601 //------------------------------init_dom_lca_tags------------------------------ | |
2602 // Tag could be a node's integer index, 32bits instead of 64bits in some cases | |
2603 // Intended use does not involve any growth for the array, so it could | |
2604 // be of fixed size. | |
2605 void PhaseIdealLoop::init_dom_lca_tags() { | |
2606 uint limit = C->unique() + 1; | |
2607 _dom_lca_tags.map( limit, NULL ); | |
2608 #ifdef ASSERT | |
2609 for( uint i = 0; i < limit; ++i ) { | |
2610 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer"); | |
2611 } | |
2612 #endif // ASSERT | |
2613 } | |
2614 | |
2615 //------------------------------clear_dom_lca_tags------------------------------ | |
2616 // Tag could be a node's integer index, 32bits instead of 64bits in some cases | |
2617 // Intended use does not involve any growth for the array, so it could | |
2618 // be of fixed size. | |
2619 void PhaseIdealLoop::clear_dom_lca_tags() { | |
2620 uint limit = C->unique() + 1; | |
2621 _dom_lca_tags.map( limit, NULL ); | |
2622 _dom_lca_tags.clear(); | |
2623 #ifdef ASSERT | |
2624 for( uint i = 0; i < limit; ++i ) { | |
2625 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer"); | |
2626 } | |
2627 #endif // ASSERT | |
2628 } | |
2629 | |
2630 //------------------------------build_loop_late-------------------------------- | |
2631 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping. | |
2632 // Second pass finds latest legal placement, and ideal loop placement. | |
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2633 void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) { |
0 | 2634 while (worklist.size() != 0) { |
2635 Node *n = worklist.pop(); | |
2636 // Only visit once | |
2637 if (visited.test_set(n->_idx)) continue; | |
2638 uint cnt = n->outcnt(); | |
2639 uint i = 0; | |
2640 while (true) { | |
2641 assert( _nodes[n->_idx], "no dead nodes" ); | |
2642 // Visit all children | |
2643 if (i < cnt) { | |
2644 Node* use = n->raw_out(i); | |
2645 ++i; | |
2646 // Check for dead uses. Aggressively prune such junk. It might be | |
2647 // dead in the global sense, but still have local uses so I cannot | |
2648 // easily call 'remove_dead_node'. | |
2649 if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead? | |
2650 // Due to cycles, we might not hit the same fixed point in the verify | |
2651 // pass as we do in the regular pass. Instead, visit such phis as | |
2652 // simple uses of the loop head. | |
2653 if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) { | |
2654 if( !visited.test(use->_idx) ) | |
2655 worklist.push(use); | |
2656 } else if( !visited.test_set(use->_idx) ) { | |
2657 nstack.push(n, i); // Save parent and next use's index. | |
2658 n = use; // Process all children of current use. | |
2659 cnt = use->outcnt(); | |
2660 i = 0; | |
2661 } | |
2662 } else { | |
2663 // Do not visit around the backedge of loops via data edges. | |
2664 // push dead code onto a worklist | |
2665 _deadlist.push(use); | |
2666 } | |
2667 } else { | |
2668 // All of n's children have been processed, complete post-processing. | |
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2669 build_loop_late_post(n); |
0 | 2670 if (nstack.is_empty()) { |
2671 // Finished all nodes on stack. | |
2672 // Process next node on the worklist. | |
2673 break; | |
2674 } | |
2675 // Get saved parent node and next use's index. Visit the rest of uses. | |
2676 n = nstack.node(); | |
2677 cnt = n->outcnt(); | |
2678 i = nstack.index(); | |
2679 nstack.pop(); | |
2680 } | |
2681 } | |
2682 } | |
2683 } | |
2684 | |
2685 //------------------------------build_loop_late_post--------------------------- | |
2686 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping. | |
2687 // Second pass finds latest legal placement, and ideal loop placement. | |
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2688 void PhaseIdealLoop::build_loop_late_post( Node *n ) { |
0 | 2689 |
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2690 if (n->req() == 2 && n->Opcode() == Op_ConvI2L && !C->major_progress() && !_verify_only) { |
0 | 2691 _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops. |
2692 } | |
2693 | |
2694 // CFG and pinned nodes already handled | |
2695 if( n->in(0) ) { | |
2696 if( n->in(0)->is_top() ) return; // Dead? | |
2697 | |
2698 // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads | |
2699 // _must_ be pinned (they have to observe their control edge of course). | |
2700 // Unlike Stores (which modify an unallocable resource, the memory | |
2701 // state), Mods/Loads can float around. So free them up. | |
2702 bool pinned = true; | |
2703 switch( n->Opcode() ) { | |
2704 case Op_DivI: | |
2705 case Op_DivF: | |
2706 case Op_DivD: | |
2707 case Op_ModI: | |
2708 case Op_ModF: | |
2709 case Op_ModD: | |
2710 case Op_LoadB: // Same with Loads; they can sink | |
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2711 case Op_LoadUS: // during loop optimizations. |
0 | 2712 case Op_LoadD: |
2713 case Op_LoadF: | |
2714 case Op_LoadI: | |
2715 case Op_LoadKlass: | |
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2716 case Op_LoadNKlass: |
0 | 2717 case Op_LoadL: |
2718 case Op_LoadS: | |
2719 case Op_LoadP: | |
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2720 case Op_LoadN: |
0 | 2721 case Op_LoadRange: |
2722 case Op_LoadD_unaligned: | |
2723 case Op_LoadL_unaligned: | |
2724 case Op_StrComp: // Does a bunch of load-like effects | |
681 | 2725 case Op_StrEquals: |
2726 case Op_StrIndexOf: | |
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2727 case Op_AryEq: |
0 | 2728 pinned = false; |
2729 } | |
2730 if( pinned ) { | |
605 | 2731 IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n)); |
2732 if( !chosen_loop->_child ) // Inner loop? | |
2733 chosen_loop->_body.push(n); // Collect inner loops | |
0 | 2734 return; |
2735 } | |
2736 } else { // No slot zero | |
2737 if( n->is_CFG() ) { // CFG with no slot 0 is dead | |
2738 _nodes.map(n->_idx,0); // No block setting, it's globally dead | |
2739 return; | |
2740 } | |
2741 assert(!n->is_CFG() || n->outcnt() == 0, ""); | |
2742 } | |
2743 | |
2744 // Do I have a "safe range" I can select over? | |
2745 Node *early = get_ctrl(n);// Early location already computed | |
2746 | |
2747 // Compute latest point this Node can go | |
2748 Node *LCA = get_late_ctrl( n, early ); | |
2749 // LCA is NULL due to uses being dead | |
2750 if( LCA == NULL ) { | |
2751 #ifdef ASSERT | |
2752 for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) { | |
2753 assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead"); | |
2754 } | |
2755 #endif | |
2756 _nodes.map(n->_idx, 0); // This node is useless | |
2757 _deadlist.push(n); | |
2758 return; | |
2759 } | |
2760 assert(LCA != NULL && !LCA->is_top(), "no dead nodes"); | |
2761 | |
2762 Node *legal = LCA; // Walk 'legal' up the IDOM chain | |
2763 Node *least = legal; // Best legal position so far | |
2764 while( early != legal ) { // While not at earliest legal | |
2765 // Find least loop nesting depth | |
2766 legal = idom(legal); // Bump up the IDOM tree | |
2767 // Check for lower nesting depth | |
2768 if( get_loop(legal)->_nest < get_loop(least)->_nest ) | |
2769 least = legal; | |
2770 } | |
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2771 assert(early == legal || legal != C->root(), "bad dominance of inputs"); |
0 | 2772 |
2773 // Try not to place code on a loop entry projection | |
2774 // which can inhibit range check elimination. | |
2775 if (least != early) { | |
2776 Node* ctrl_out = least->unique_ctrl_out(); | |
2777 if (ctrl_out && ctrl_out->is_CountedLoop() && | |
2778 least == ctrl_out->in(LoopNode::EntryControl)) { | |
2779 Node* least_dom = idom(least); | |
2780 if (get_loop(least_dom)->is_member(get_loop(least))) { | |
2781 least = least_dom; | |
2782 } | |
2783 } | |
2784 } | |
2785 | |
2786 #ifdef ASSERT | |
2787 // If verifying, verify that 'verify_me' has a legal location | |
2788 // and choose it as our location. | |
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2789 if( _verify_me ) { |
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2790 Node *v_ctrl = _verify_me->get_ctrl_no_update(n); |
0 | 2791 Node *legal = LCA; |
2792 while( early != legal ) { // While not at earliest legal | |
2793 if( legal == v_ctrl ) break; // Check for prior good location | |
2794 legal = idom(legal) ;// Bump up the IDOM tree | |
2795 } | |
2796 // Check for prior good location | |
2797 if( legal == v_ctrl ) least = legal; // Keep prior if found | |
2798 } | |
2799 #endif | |
2800 | |
2801 // Assign discovered "here or above" point | |
2802 least = find_non_split_ctrl(least); | |
2803 set_ctrl(n, least); | |
2804 | |
2805 // Collect inner loop bodies | |
605 | 2806 IdealLoopTree *chosen_loop = get_loop(least); |
2807 if( !chosen_loop->_child ) // Inner loop? | |
2808 chosen_loop->_body.push(n);// Collect inner loops | |
0 | 2809 } |
2810 | |
2811 #ifndef PRODUCT | |
2812 //------------------------------dump------------------------------------------- | |
2813 void PhaseIdealLoop::dump( ) const { | |
2814 ResourceMark rm; | |
2815 Arena* arena = Thread::current()->resource_area(); | |
2816 Node_Stack stack(arena, C->unique() >> 2); | |
2817 Node_List rpo_list; | |
2818 VectorSet visited(arena); | |
2819 visited.set(C->top()->_idx); | |
2820 rpo( C->root(), stack, visited, rpo_list ); | |
2821 // Dump root loop indexed by last element in PO order | |
2822 dump( _ltree_root, rpo_list.size(), rpo_list ); | |
2823 } | |
2824 | |
2825 void PhaseIdealLoop::dump( IdealLoopTree *loop, uint idx, Node_List &rpo_list ) const { | |
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2826 loop->dump_head(); |
0 | 2827 |
2828 // Now scan for CFG nodes in the same loop | |
2829 for( uint j=idx; j > 0; j-- ) { | |
2830 Node *n = rpo_list[j-1]; | |
2831 if( !_nodes[n->_idx] ) // Skip dead nodes | |
2832 continue; | |
2833 if( get_loop(n) != loop ) { // Wrong loop nest | |
2834 if( get_loop(n)->_head == n && // Found nested loop? | |
2835 get_loop(n)->_parent == loop ) | |
2836 dump(get_loop(n),rpo_list.size(),rpo_list); // Print it nested-ly | |
2837 continue; | |
2838 } | |
2839 | |
2840 // Dump controlling node | |
2841 for( uint x = 0; x < loop->_nest; x++ ) | |
2842 tty->print(" "); | |
2843 tty->print("C"); | |
2844 if( n == C->root() ) { | |
2845 n->dump(); | |
2846 } else { | |
2847 Node* cached_idom = idom_no_update(n); | |
2848 Node *computed_idom = n->in(0); | |
2849 if( n->is_Region() ) { | |
2850 computed_idom = compute_idom(n); | |
2851 // computed_idom() will return n->in(0) when idom(n) is an IfNode (or | |
2852 // any MultiBranch ctrl node), so apply a similar transform to | |
2853 // the cached idom returned from idom_no_update. | |
2854 cached_idom = find_non_split_ctrl(cached_idom); | |
2855 } | |
2856 tty->print(" ID:%d",computed_idom->_idx); | |
2857 n->dump(); | |
2858 if( cached_idom != computed_idom ) { | |
2859 tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d", | |
2860 computed_idom->_idx, cached_idom->_idx); | |
2861 } | |
2862 } | |
2863 // Dump nodes it controls | |
2864 for( uint k = 0; k < _nodes.Size(); k++ ) { | |
2865 // (k < C->unique() && get_ctrl(find(k)) == n) | |
2866 if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) { | |
2867 Node *m = C->root()->find(k); | |
2868 if( m && m->outcnt() > 0 ) { | |
2869 if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) { | |
2870 tty->print_cr("*** BROKEN CTRL ACCESSOR! _nodes[k] is %p, ctrl is %p", | |
2871 _nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL); | |
2872 } | |
2873 for( uint j = 0; j < loop->_nest; j++ ) | |
2874 tty->print(" "); | |
2875 tty->print(" "); | |
2876 m->dump(); | |
2877 } | |
2878 } | |
2879 } | |
2880 } | |
2881 } | |
2882 | |
2883 // Collect a R-P-O for the whole CFG. | |
2884 // Result list is in post-order (scan backwards for RPO) | |
2885 void PhaseIdealLoop::rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const { | |
2886 stk.push(start, 0); | |
2887 visited.set(start->_idx); | |
2888 | |
2889 while (stk.is_nonempty()) { | |
2890 Node* m = stk.node(); | |
2891 uint idx = stk.index(); | |
2892 if (idx < m->outcnt()) { | |
2893 stk.set_index(idx + 1); | |
2894 Node* n = m->raw_out(idx); | |
2895 if (n->is_CFG() && !visited.test_set(n->_idx)) { | |
2896 stk.push(n, 0); | |
2897 } | |
2898 } else { | |
2899 rpo_list.push(m); | |
2900 stk.pop(); | |
2901 } | |
2902 } | |
2903 } | |
2904 #endif | |
2905 | |
2906 | |
2907 //============================================================================= | |
2908 //------------------------------LoopTreeIterator----------------------------------- | |
2909 | |
2910 // Advance to next loop tree using a preorder, left-to-right traversal. | |
2911 void LoopTreeIterator::next() { | |
2912 assert(!done(), "must not be done."); | |
2913 if (_curnt->_child != NULL) { | |
2914 _curnt = _curnt->_child; | |
2915 } else if (_curnt->_next != NULL) { | |
2916 _curnt = _curnt->_next; | |
2917 } else { | |
2918 while (_curnt != _root && _curnt->_next == NULL) { | |
2919 _curnt = _curnt->_parent; | |
2920 } | |
2921 if (_curnt == _root) { | |
2922 _curnt = NULL; | |
2923 assert(done(), "must be done."); | |
2924 } else { | |
2925 assert(_curnt->_next != NULL, "must be more to do"); | |
2926 _curnt = _curnt->_next; | |
2927 } | |
2928 } | |
2929 } |