Mercurial > hg > graal-compiler
annotate src/share/vm/opto/loopTransform.cpp @ 1722:effb55808a18
Merge
author | johnc |
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date | Wed, 18 Aug 2010 17:44:33 -0400 |
parents | 6027dddc26c6 |
children | d6f45b55c972 |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved. |
0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
25 #include "incls/_precompiled.incl" | |
26 #include "incls/_loopTransform.cpp.incl" | |
27 | |
28 //------------------------------is_loop_exit----------------------------------- | |
29 // Given an IfNode, return the loop-exiting projection or NULL if both | |
30 // arms remain in the loop. | |
31 Node *IdealLoopTree::is_loop_exit(Node *iff) const { | |
32 if( iff->outcnt() != 2 ) return NULL; // Ignore partially dead tests | |
33 PhaseIdealLoop *phase = _phase; | |
34 // Test is an IfNode, has 2 projections. If BOTH are in the loop | |
35 // we need loop unswitching instead of peeling. | |
36 if( !is_member(phase->get_loop( iff->raw_out(0) )) ) | |
37 return iff->raw_out(0); | |
38 if( !is_member(phase->get_loop( iff->raw_out(1) )) ) | |
39 return iff->raw_out(1); | |
40 return NULL; | |
41 } | |
42 | |
43 | |
44 //============================================================================= | |
45 | |
46 | |
47 //------------------------------record_for_igvn---------------------------- | |
48 // Put loop body on igvn work list | |
49 void IdealLoopTree::record_for_igvn() { | |
50 for( uint i = 0; i < _body.size(); i++ ) { | |
51 Node *n = _body.at(i); | |
52 _phase->_igvn._worklist.push(n); | |
53 } | |
54 } | |
55 | |
56 //------------------------------compute_profile_trip_cnt---------------------------- | |
57 // Compute loop trip count from profile data as | |
58 // (backedge_count + loop_exit_count) / loop_exit_count | |
59 void IdealLoopTree::compute_profile_trip_cnt( PhaseIdealLoop *phase ) { | |
60 if (!_head->is_CountedLoop()) { | |
61 return; | |
62 } | |
63 CountedLoopNode* head = _head->as_CountedLoop(); | |
64 if (head->profile_trip_cnt() != COUNT_UNKNOWN) { | |
65 return; // Already computed | |
66 } | |
67 float trip_cnt = (float)max_jint; // default is big | |
68 | |
69 Node* back = head->in(LoopNode::LoopBackControl); | |
70 while (back != head) { | |
71 if ((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) && | |
72 back->in(0) && | |
73 back->in(0)->is_If() && | |
74 back->in(0)->as_If()->_fcnt != COUNT_UNKNOWN && | |
75 back->in(0)->as_If()->_prob != PROB_UNKNOWN) { | |
76 break; | |
77 } | |
78 back = phase->idom(back); | |
79 } | |
80 if (back != head) { | |
81 assert((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) && | |
82 back->in(0), "if-projection exists"); | |
83 IfNode* back_if = back->in(0)->as_If(); | |
84 float loop_back_cnt = back_if->_fcnt * back_if->_prob; | |
85 | |
86 // Now compute a loop exit count | |
87 float loop_exit_cnt = 0.0f; | |
88 for( uint i = 0; i < _body.size(); i++ ) { | |
89 Node *n = _body[i]; | |
90 if( n->is_If() ) { | |
91 IfNode *iff = n->as_If(); | |
92 if( iff->_fcnt != COUNT_UNKNOWN && iff->_prob != PROB_UNKNOWN ) { | |
93 Node *exit = is_loop_exit(iff); | |
94 if( exit ) { | |
95 float exit_prob = iff->_prob; | |
96 if (exit->Opcode() == Op_IfFalse) exit_prob = 1.0 - exit_prob; | |
97 if (exit_prob > PROB_MIN) { | |
98 float exit_cnt = iff->_fcnt * exit_prob; | |
99 loop_exit_cnt += exit_cnt; | |
100 } | |
101 } | |
102 } | |
103 } | |
104 } | |
105 if (loop_exit_cnt > 0.0f) { | |
106 trip_cnt = (loop_back_cnt + loop_exit_cnt) / loop_exit_cnt; | |
107 } else { | |
108 // No exit count so use | |
109 trip_cnt = loop_back_cnt; | |
110 } | |
111 } | |
112 #ifndef PRODUCT | |
113 if (TraceProfileTripCount) { | |
114 tty->print_cr("compute_profile_trip_cnt lp: %d cnt: %f\n", head->_idx, trip_cnt); | |
115 } | |
116 #endif | |
117 head->set_profile_trip_cnt(trip_cnt); | |
118 } | |
119 | |
120 //---------------------is_invariant_addition----------------------------- | |
121 // Return nonzero index of invariant operand for an Add or Sub | |
605 | 122 // of (nonconstant) invariant and variant values. Helper for reassociate_invariants. |
0 | 123 int IdealLoopTree::is_invariant_addition(Node* n, PhaseIdealLoop *phase) { |
124 int op = n->Opcode(); | |
125 if (op == Op_AddI || op == Op_SubI) { | |
126 bool in1_invar = this->is_invariant(n->in(1)); | |
127 bool in2_invar = this->is_invariant(n->in(2)); | |
128 if (in1_invar && !in2_invar) return 1; | |
129 if (!in1_invar && in2_invar) return 2; | |
130 } | |
131 return 0; | |
132 } | |
133 | |
134 //---------------------reassociate_add_sub----------------------------- | |
135 // Reassociate invariant add and subtract expressions: | |
136 // | |
137 // inv1 + (x + inv2) => ( inv1 + inv2) + x | |
138 // (x + inv2) + inv1 => ( inv1 + inv2) + x | |
139 // inv1 + (x - inv2) => ( inv1 - inv2) + x | |
140 // inv1 - (inv2 - x) => ( inv1 - inv2) + x | |
141 // (x + inv2) - inv1 => (-inv1 + inv2) + x | |
142 // (x - inv2) + inv1 => ( inv1 - inv2) + x | |
143 // (x - inv2) - inv1 => (-inv1 - inv2) + x | |
144 // inv1 + (inv2 - x) => ( inv1 + inv2) - x | |
145 // inv1 - (x - inv2) => ( inv1 + inv2) - x | |
146 // (inv2 - x) + inv1 => ( inv1 + inv2) - x | |
147 // (inv2 - x) - inv1 => (-inv1 + inv2) - x | |
148 // inv1 - (x + inv2) => ( inv1 - inv2) - x | |
149 // | |
150 Node* IdealLoopTree::reassociate_add_sub(Node* n1, PhaseIdealLoop *phase) { | |
151 if (!n1->is_Add() && !n1->is_Sub() || n1->outcnt() == 0) return NULL; | |
152 if (is_invariant(n1)) return NULL; | |
153 int inv1_idx = is_invariant_addition(n1, phase); | |
154 if (!inv1_idx) return NULL; | |
155 // Don't mess with add of constant (igvn moves them to expression tree root.) | |
156 if (n1->is_Add() && n1->in(2)->is_Con()) return NULL; | |
157 Node* inv1 = n1->in(inv1_idx); | |
158 Node* n2 = n1->in(3 - inv1_idx); | |
159 int inv2_idx = is_invariant_addition(n2, phase); | |
160 if (!inv2_idx) return NULL; | |
161 Node* x = n2->in(3 - inv2_idx); | |
162 Node* inv2 = n2->in(inv2_idx); | |
163 | |
164 bool neg_x = n2->is_Sub() && inv2_idx == 1; | |
165 bool neg_inv2 = n2->is_Sub() && inv2_idx == 2; | |
166 bool neg_inv1 = n1->is_Sub() && inv1_idx == 2; | |
167 if (n1->is_Sub() && inv1_idx == 1) { | |
168 neg_x = !neg_x; | |
169 neg_inv2 = !neg_inv2; | |
170 } | |
171 Node* inv1_c = phase->get_ctrl(inv1); | |
172 Node* inv2_c = phase->get_ctrl(inv2); | |
173 Node* n_inv1; | |
174 if (neg_inv1) { | |
175 Node *zero = phase->_igvn.intcon(0); | |
176 phase->set_ctrl(zero, phase->C->root()); | |
177 n_inv1 = new (phase->C, 3) SubINode(zero, inv1); | |
178 phase->register_new_node(n_inv1, inv1_c); | |
179 } else { | |
180 n_inv1 = inv1; | |
181 } | |
182 Node* inv; | |
183 if (neg_inv2) { | |
184 inv = new (phase->C, 3) SubINode(n_inv1, inv2); | |
185 } else { | |
186 inv = new (phase->C, 3) AddINode(n_inv1, inv2); | |
187 } | |
188 phase->register_new_node(inv, phase->get_early_ctrl(inv)); | |
189 | |
190 Node* addx; | |
191 if (neg_x) { | |
192 addx = new (phase->C, 3) SubINode(inv, x); | |
193 } else { | |
194 addx = new (phase->C, 3) AddINode(x, inv); | |
195 } | |
196 phase->register_new_node(addx, phase->get_ctrl(x)); | |
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197 phase->_igvn.replace_node(n1, addx); |
0 | 198 return addx; |
199 } | |
200 | |
201 //---------------------reassociate_invariants----------------------------- | |
202 // Reassociate invariant expressions: | |
203 void IdealLoopTree::reassociate_invariants(PhaseIdealLoop *phase) { | |
204 for (int i = _body.size() - 1; i >= 0; i--) { | |
205 Node *n = _body.at(i); | |
206 for (int j = 0; j < 5; j++) { | |
207 Node* nn = reassociate_add_sub(n, phase); | |
208 if (nn == NULL) break; | |
209 n = nn; // again | |
210 }; | |
211 } | |
212 } | |
213 | |
214 //------------------------------policy_peeling--------------------------------- | |
215 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can | |
216 // make some loop-invariant test (usually a null-check) happen before the loop. | |
217 bool IdealLoopTree::policy_peeling( PhaseIdealLoop *phase ) const { | |
218 Node *test = ((IdealLoopTree*)this)->tail(); | |
219 int body_size = ((IdealLoopTree*)this)->_body.size(); | |
220 int uniq = phase->C->unique(); | |
221 // Peeling does loop cloning which can result in O(N^2) node construction | |
222 if( body_size > 255 /* Prevent overflow for large body_size */ | |
223 || (body_size * body_size + uniq > MaxNodeLimit) ) { | |
224 return false; // too large to safely clone | |
225 } | |
226 while( test != _head ) { // Scan till run off top of loop | |
227 if( test->is_If() ) { // Test? | |
228 Node *ctrl = phase->get_ctrl(test->in(1)); | |
229 if (ctrl->is_top()) | |
230 return false; // Found dead test on live IF? No peeling! | |
231 // Standard IF only has one input value to check for loop invariance | |
232 assert( test->Opcode() == Op_If || test->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added"); | |
233 // Condition is not a member of this loop? | |
234 if( !is_member(phase->get_loop(ctrl)) && | |
235 is_loop_exit(test) ) | |
236 return true; // Found reason to peel! | |
237 } | |
238 // Walk up dominators to loop _head looking for test which is | |
239 // executed on every path thru loop. | |
240 test = phase->idom(test); | |
241 } | |
242 return false; | |
243 } | |
244 | |
245 //------------------------------peeled_dom_test_elim--------------------------- | |
246 // If we got the effect of peeling, either by actually peeling or by making | |
247 // a pre-loop which must execute at least once, we can remove all | |
248 // loop-invariant dominated tests in the main body. | |
249 void PhaseIdealLoop::peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ) { | |
250 bool progress = true; | |
251 while( progress ) { | |
252 progress = false; // Reset for next iteration | |
253 Node *prev = loop->_head->in(LoopNode::LoopBackControl);//loop->tail(); | |
254 Node *test = prev->in(0); | |
255 while( test != loop->_head ) { // Scan till run off top of loop | |
256 | |
257 int p_op = prev->Opcode(); | |
258 if( (p_op == Op_IfFalse || p_op == Op_IfTrue) && | |
259 test->is_If() && // Test? | |
260 !test->in(1)->is_Con() && // And not already obvious? | |
261 // Condition is not a member of this loop? | |
262 !loop->is_member(get_loop(get_ctrl(test->in(1))))){ | |
263 // Walk loop body looking for instances of this test | |
264 for( uint i = 0; i < loop->_body.size(); i++ ) { | |
265 Node *n = loop->_body.at(i); | |
266 if( n->is_If() && n->in(1) == test->in(1) /*&& n != loop->tail()->in(0)*/ ) { | |
267 // IfNode was dominated by version in peeled loop body | |
268 progress = true; | |
269 dominated_by( old_new[prev->_idx], n ); | |
270 } | |
271 } | |
272 } | |
273 prev = test; | |
274 test = idom(test); | |
275 } // End of scan tests in loop | |
276 | |
277 } // End of while( progress ) | |
278 } | |
279 | |
280 //------------------------------do_peeling------------------------------------- | |
281 // Peel the first iteration of the given loop. | |
282 // Step 1: Clone the loop body. The clone becomes the peeled iteration. | |
283 // The pre-loop illegally has 2 control users (old & new loops). | |
284 // Step 2: Make the old-loop fall-in edges point to the peeled iteration. | |
285 // Do this by making the old-loop fall-in edges act as if they came | |
286 // around the loopback from the prior iteration (follow the old-loop | |
287 // backedges) and then map to the new peeled iteration. This leaves | |
288 // the pre-loop with only 1 user (the new peeled iteration), but the | |
289 // peeled-loop backedge has 2 users. | |
290 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the | |
291 // extra backedge user. | |
292 void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) { | |
293 | |
294 C->set_major_progress(); | |
295 // Peeling a 'main' loop in a pre/main/post situation obfuscates the | |
296 // 'pre' loop from the main and the 'pre' can no longer have it's | |
297 // iterations adjusted. Therefore, we need to declare this loop as | |
298 // no longer a 'main' loop; it will need new pre and post loops before | |
299 // we can do further RCE. | |
300 Node *h = loop->_head; | |
301 if( h->is_CountedLoop() ) { | |
302 CountedLoopNode *cl = h->as_CountedLoop(); | |
303 assert(cl->trip_count() > 0, "peeling a fully unrolled loop"); | |
304 cl->set_trip_count(cl->trip_count() - 1); | |
305 if( cl->is_main_loop() ) { | |
306 cl->set_normal_loop(); | |
307 #ifndef PRODUCT | |
308 if( PrintOpto && VerifyLoopOptimizations ) { | |
309 tty->print("Peeling a 'main' loop; resetting to 'normal' "); | |
310 loop->dump_head(); | |
311 } | |
312 #endif | |
313 } | |
314 } | |
315 | |
316 // Step 1: Clone the loop body. The clone becomes the peeled iteration. | |
317 // The pre-loop illegally has 2 control users (old & new loops). | |
318 clone_loop( loop, old_new, dom_depth(loop->_head) ); | |
319 | |
320 | |
321 // Step 2: Make the old-loop fall-in edges point to the peeled iteration. | |
322 // Do this by making the old-loop fall-in edges act as if they came | |
323 // around the loopback from the prior iteration (follow the old-loop | |
324 // backedges) and then map to the new peeled iteration. This leaves | |
325 // the pre-loop with only 1 user (the new peeled iteration), but the | |
326 // peeled-loop backedge has 2 users. | |
327 for (DUIterator_Fast jmax, j = loop->_head->fast_outs(jmax); j < jmax; j++) { | |
328 Node* old = loop->_head->fast_out(j); | |
329 if( old->in(0) == loop->_head && old->req() == 3 && | |
330 (old->is_Loop() || old->is_Phi()) ) { | |
331 Node *new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx]; | |
332 if( !new_exit_value ) // Backedge value is ALSO loop invariant? | |
333 // Then loop body backedge value remains the same. | |
334 new_exit_value = old->in(LoopNode::LoopBackControl); | |
335 _igvn.hash_delete(old); | |
336 old->set_req(LoopNode::EntryControl, new_exit_value); | |
337 } | |
338 } | |
339 | |
340 | |
341 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the | |
342 // extra backedge user. | |
343 Node *nnn = old_new[loop->_head->_idx]; | |
344 _igvn.hash_delete(nnn); | |
345 nnn->set_req(LoopNode::LoopBackControl, C->top()); | |
346 for (DUIterator_Fast j2max, j2 = nnn->fast_outs(j2max); j2 < j2max; j2++) { | |
347 Node* use = nnn->fast_out(j2); | |
348 if( use->in(0) == nnn && use->req() == 3 && use->is_Phi() ) { | |
349 _igvn.hash_delete(use); | |
350 use->set_req(LoopNode::LoopBackControl, C->top()); | |
351 } | |
352 } | |
353 | |
354 | |
355 // Step 4: Correct dom-depth info. Set to loop-head depth. | |
356 int dd = dom_depth(loop->_head); | |
357 set_idom(loop->_head, loop->_head->in(1), dd); | |
358 for (uint j3 = 0; j3 < loop->_body.size(); j3++) { | |
359 Node *old = loop->_body.at(j3); | |
360 Node *nnn = old_new[old->_idx]; | |
361 if (!has_ctrl(nnn)) | |
362 set_idom(nnn, idom(nnn), dd-1); | |
363 // While we're at it, remove any SafePoints from the peeled code | |
364 if( old->Opcode() == Op_SafePoint ) { | |
365 Node *nnn = old_new[old->_idx]; | |
366 lazy_replace(nnn,nnn->in(TypeFunc::Control)); | |
367 } | |
368 } | |
369 | |
370 // Now force out all loop-invariant dominating tests. The optimizer | |
371 // finds some, but we _know_ they are all useless. | |
372 peeled_dom_test_elim(loop,old_new); | |
373 | |
374 loop->record_for_igvn(); | |
375 } | |
376 | |
377 //------------------------------policy_maximally_unroll------------------------ | |
378 // Return exact loop trip count, or 0 if not maximally unrolling | |
379 bool IdealLoopTree::policy_maximally_unroll( PhaseIdealLoop *phase ) const { | |
380 CountedLoopNode *cl = _head->as_CountedLoop(); | |
381 assert( cl->is_normal_loop(), "" ); | |
382 | |
383 Node *init_n = cl->init_trip(); | |
384 Node *limit_n = cl->limit(); | |
385 | |
386 // Non-constant bounds | |
387 if( init_n == NULL || !init_n->is_Con() || | |
388 limit_n == NULL || !limit_n->is_Con() || | |
389 // protect against stride not being a constant | |
390 !cl->stride_is_con() ) { | |
391 return false; | |
392 } | |
393 int init = init_n->get_int(); | |
394 int limit = limit_n->get_int(); | |
395 int span = limit - init; | |
396 int stride = cl->stride_con(); | |
397 | |
398 if (init >= limit || stride > span) { | |
399 // return a false (no maximally unroll) and the regular unroll/peel | |
400 // route will make a small mess which CCP will fold away. | |
401 return false; | |
402 } | |
403 uint trip_count = span/stride; // trip_count can be greater than 2 Gig. | |
404 assert( (int)trip_count*stride == span, "must divide evenly" ); | |
405 | |
406 // Real policy: if we maximally unroll, does it get too big? | |
407 // Allow the unrolled mess to get larger than standard loop | |
408 // size. After all, it will no longer be a loop. | |
409 uint body_size = _body.size(); | |
410 uint unroll_limit = (uint)LoopUnrollLimit * 4; | |
411 assert( (intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits"); | |
412 cl->set_trip_count(trip_count); | |
413 if( trip_count <= unroll_limit && body_size <= unroll_limit ) { | |
414 uint new_body_size = body_size * trip_count; | |
415 if (new_body_size <= unroll_limit && | |
416 body_size == new_body_size / trip_count && | |
417 // Unrolling can result in a large amount of node construction | |
418 new_body_size < MaxNodeLimit - phase->C->unique()) { | |
419 return true; // maximally unroll | |
420 } | |
421 } | |
422 | |
423 return false; // Do not maximally unroll | |
424 } | |
425 | |
426 | |
427 //------------------------------policy_unroll---------------------------------- | |
428 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if | |
429 // the loop is a CountedLoop and the body is small enough. | |
430 bool IdealLoopTree::policy_unroll( PhaseIdealLoop *phase ) const { | |
431 | |
432 CountedLoopNode *cl = _head->as_CountedLoop(); | |
433 assert( cl->is_normal_loop() || cl->is_main_loop(), "" ); | |
434 | |
435 // protect against stride not being a constant | |
436 if( !cl->stride_is_con() ) return false; | |
437 | |
438 // protect against over-unrolling | |
439 if( cl->trip_count() <= 1 ) return false; | |
440 | |
441 int future_unroll_ct = cl->unrolled_count() * 2; | |
442 | |
443 // Don't unroll if the next round of unrolling would push us | |
444 // over the expected trip count of the loop. One is subtracted | |
445 // from the expected trip count because the pre-loop normally | |
446 // executes 1 iteration. | |
447 if (UnrollLimitForProfileCheck > 0 && | |
448 cl->profile_trip_cnt() != COUNT_UNKNOWN && | |
449 future_unroll_ct > UnrollLimitForProfileCheck && | |
450 (float)future_unroll_ct > cl->profile_trip_cnt() - 1.0) { | |
451 return false; | |
452 } | |
453 | |
454 // When unroll count is greater than LoopUnrollMin, don't unroll if: | |
455 // the residual iterations are more than 10% of the trip count | |
456 // and rounds of "unroll,optimize" are not making significant progress | |
457 // Progress defined as current size less than 20% larger than previous size. | |
458 if (UseSuperWord && cl->node_count_before_unroll() > 0 && | |
459 future_unroll_ct > LoopUnrollMin && | |
460 (future_unroll_ct - 1) * 10.0 > cl->profile_trip_cnt() && | |
461 1.2 * cl->node_count_before_unroll() < (double)_body.size()) { | |
462 return false; | |
463 } | |
464 | |
465 Node *init_n = cl->init_trip(); | |
466 Node *limit_n = cl->limit(); | |
467 // Non-constant bounds. | |
468 // Protect against over-unrolling when init or/and limit are not constant | |
469 // (so that trip_count's init value is maxint) but iv range is known. | |
470 if( init_n == NULL || !init_n->is_Con() || | |
471 limit_n == NULL || !limit_n->is_Con() ) { | |
472 Node* phi = cl->phi(); | |
473 if( phi != NULL ) { | |
474 assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi."); | |
475 const TypeInt* iv_type = phase->_igvn.type(phi)->is_int(); | |
476 int next_stride = cl->stride_con() * 2; // stride after this unroll | |
477 if( next_stride > 0 ) { | |
478 if( iv_type->_lo + next_stride <= iv_type->_lo || // overflow | |
479 iv_type->_lo + next_stride > iv_type->_hi ) { | |
480 return false; // over-unrolling | |
481 } | |
482 } else if( next_stride < 0 ) { | |
483 if( iv_type->_hi + next_stride >= iv_type->_hi || // overflow | |
484 iv_type->_hi + next_stride < iv_type->_lo ) { | |
485 return false; // over-unrolling | |
486 } | |
487 } | |
488 } | |
489 } | |
490 | |
491 // Adjust body_size to determine if we unroll or not | |
492 uint body_size = _body.size(); | |
493 // Key test to unroll CaffeineMark's Logic test | |
494 int xors_in_loop = 0; | |
495 // Also count ModL, DivL and MulL which expand mightly | |
496 for( uint k = 0; k < _body.size(); k++ ) { | |
497 switch( _body.at(k)->Opcode() ) { | |
498 case Op_XorI: xors_in_loop++; break; // CaffeineMark's Logic test | |
499 case Op_ModL: body_size += 30; break; | |
500 case Op_DivL: body_size += 30; break; | |
501 case Op_MulL: body_size += 10; break; | |
502 } | |
503 } | |
504 | |
505 // Check for being too big | |
506 if( body_size > (uint)LoopUnrollLimit ) { | |
507 if( xors_in_loop >= 4 && body_size < (uint)LoopUnrollLimit*4) return true; | |
508 // Normal case: loop too big | |
509 return false; | |
510 } | |
511 | |
512 // Check for stride being a small enough constant | |
513 if( abs(cl->stride_con()) > (1<<3) ) return false; | |
514 | |
515 // Unroll once! (Each trip will soon do double iterations) | |
516 return true; | |
517 } | |
518 | |
519 //------------------------------policy_align----------------------------------- | |
520 // Return TRUE or FALSE if the loop should be cache-line aligned. Gather the | |
521 // expression that does the alignment. Note that only one array base can be | |
605 | 522 // aligned in a loop (unless the VM guarantees mutual alignment). Note that |
0 | 523 // if we vectorize short memory ops into longer memory ops, we may want to |
524 // increase alignment. | |
525 bool IdealLoopTree::policy_align( PhaseIdealLoop *phase ) const { | |
526 return false; | |
527 } | |
528 | |
529 //------------------------------policy_range_check----------------------------- | |
530 // Return TRUE or FALSE if the loop should be range-check-eliminated. | |
531 // Actually we do iteration-splitting, a more powerful form of RCE. | |
532 bool IdealLoopTree::policy_range_check( PhaseIdealLoop *phase ) const { | |
533 if( !RangeCheckElimination ) return false; | |
534 | |
535 CountedLoopNode *cl = _head->as_CountedLoop(); | |
536 // If we unrolled with no intention of doing RCE and we later | |
537 // changed our minds, we got no pre-loop. Either we need to | |
538 // make a new pre-loop, or we gotta disallow RCE. | |
539 if( cl->is_main_no_pre_loop() ) return false; // Disallowed for now. | |
540 Node *trip_counter = cl->phi(); | |
541 | |
542 // Check loop body for tests of trip-counter plus loop-invariant vs | |
543 // loop-invariant. | |
544 for( uint i = 0; i < _body.size(); i++ ) { | |
545 Node *iff = _body[i]; | |
546 if( iff->Opcode() == Op_If ) { // Test? | |
547 | |
548 // Comparing trip+off vs limit | |
549 Node *bol = iff->in(1); | |
550 if( bol->req() != 2 ) continue; // dead constant test | |
1172 | 551 if (!bol->is_Bool()) { |
552 assert(UseLoopPredicate && bol->Opcode() == Op_Conv2B, "predicate check only"); | |
553 continue; | |
554 } | |
0 | 555 Node *cmp = bol->in(1); |
556 | |
557 Node *rc_exp = cmp->in(1); | |
558 Node *limit = cmp->in(2); | |
559 | |
560 Node *limit_c = phase->get_ctrl(limit); | |
561 if( limit_c == phase->C->top() ) | |
562 return false; // Found dead test on live IF? No RCE! | |
563 if( is_member(phase->get_loop(limit_c) ) ) { | |
564 // Compare might have operands swapped; commute them | |
565 rc_exp = cmp->in(2); | |
566 limit = cmp->in(1); | |
567 limit_c = phase->get_ctrl(limit); | |
568 if( is_member(phase->get_loop(limit_c) ) ) | |
569 continue; // Both inputs are loop varying; cannot RCE | |
570 } | |
571 | |
572 if (!phase->is_scaled_iv_plus_offset(rc_exp, trip_counter, NULL, NULL)) { | |
573 continue; | |
574 } | |
575 // Yeah! Found a test like 'trip+off vs limit' | |
576 // Test is an IfNode, has 2 projections. If BOTH are in the loop | |
577 // we need loop unswitching instead of iteration splitting. | |
578 if( is_loop_exit(iff) ) | |
579 return true; // Found reason to split iterations | |
580 } // End of is IF | |
581 } | |
582 | |
583 return false; | |
584 } | |
585 | |
586 //------------------------------policy_peel_only------------------------------- | |
587 // Return TRUE or FALSE if the loop should NEVER be RCE'd or aligned. Useful | |
588 // for unrolling loops with NO array accesses. | |
589 bool IdealLoopTree::policy_peel_only( PhaseIdealLoop *phase ) const { | |
590 | |
591 for( uint i = 0; i < _body.size(); i++ ) | |
592 if( _body[i]->is_Mem() ) | |
593 return false; | |
594 | |
595 // No memory accesses at all! | |
596 return true; | |
597 } | |
598 | |
599 //------------------------------clone_up_backedge_goo-------------------------- | |
600 // If Node n lives in the back_ctrl block and cannot float, we clone a private | |
601 // version of n in preheader_ctrl block and return that, otherwise return n. | |
602 Node *PhaseIdealLoop::clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n ) { | |
603 if( get_ctrl(n) != back_ctrl ) return n; | |
604 | |
605 Node *x = NULL; // If required, a clone of 'n' | |
606 // Check for 'n' being pinned in the backedge. | |
607 if( n->in(0) && n->in(0) == back_ctrl ) { | |
608 x = n->clone(); // Clone a copy of 'n' to preheader | |
609 x->set_req( 0, preheader_ctrl ); // Fix x's control input to preheader | |
610 } | |
611 | |
612 // Recursive fixup any other input edges into x. | |
613 // If there are no changes we can just return 'n', otherwise | |
614 // we need to clone a private copy and change it. | |
615 for( uint i = 1; i < n->req(); i++ ) { | |
616 Node *g = clone_up_backedge_goo( back_ctrl, preheader_ctrl, n->in(i) ); | |
617 if( g != n->in(i) ) { | |
618 if( !x ) | |
619 x = n->clone(); | |
620 x->set_req(i, g); | |
621 } | |
622 } | |
623 if( x ) { // x can legally float to pre-header location | |
624 register_new_node( x, preheader_ctrl ); | |
625 return x; | |
626 } else { // raise n to cover LCA of uses | |
627 set_ctrl( n, find_non_split_ctrl(back_ctrl->in(0)) ); | |
628 } | |
629 return n; | |
630 } | |
631 | |
632 //------------------------------insert_pre_post_loops-------------------------- | |
633 // Insert pre and post loops. If peel_only is set, the pre-loop can not have | |
634 // more iterations added. It acts as a 'peel' only, no lower-bound RCE, no | |
635 // alignment. Useful to unroll loops that do no array accesses. | |
636 void PhaseIdealLoop::insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ) { | |
637 | |
638 C->set_major_progress(); | |
639 | |
640 // Find common pieces of the loop being guarded with pre & post loops | |
641 CountedLoopNode *main_head = loop->_head->as_CountedLoop(); | |
642 assert( main_head->is_normal_loop(), "" ); | |
643 CountedLoopEndNode *main_end = main_head->loopexit(); | |
644 assert( main_end->outcnt() == 2, "1 true, 1 false path only" ); | |
645 uint dd_main_head = dom_depth(main_head); | |
646 uint max = main_head->outcnt(); | |
647 | |
648 Node *pre_header= main_head->in(LoopNode::EntryControl); | |
649 Node *init = main_head->init_trip(); | |
650 Node *incr = main_end ->incr(); | |
651 Node *limit = main_end ->limit(); | |
652 Node *stride = main_end ->stride(); | |
653 Node *cmp = main_end ->cmp_node(); | |
654 BoolTest::mask b_test = main_end->test_trip(); | |
655 | |
656 // Need only 1 user of 'bol' because I will be hacking the loop bounds. | |
657 Node *bol = main_end->in(CountedLoopEndNode::TestValue); | |
658 if( bol->outcnt() != 1 ) { | |
659 bol = bol->clone(); | |
660 register_new_node(bol,main_end->in(CountedLoopEndNode::TestControl)); | |
661 _igvn.hash_delete(main_end); | |
662 main_end->set_req(CountedLoopEndNode::TestValue, bol); | |
663 } | |
664 // Need only 1 user of 'cmp' because I will be hacking the loop bounds. | |
665 if( cmp->outcnt() != 1 ) { | |
666 cmp = cmp->clone(); | |
667 register_new_node(cmp,main_end->in(CountedLoopEndNode::TestControl)); | |
668 _igvn.hash_delete(bol); | |
669 bol->set_req(1, cmp); | |
670 } | |
671 | |
672 //------------------------------ | |
673 // Step A: Create Post-Loop. | |
674 Node* main_exit = main_end->proj_out(false); | |
675 assert( main_exit->Opcode() == Op_IfFalse, "" ); | |
676 int dd_main_exit = dom_depth(main_exit); | |
677 | |
678 // Step A1: Clone the loop body. The clone becomes the post-loop. The main | |
679 // loop pre-header illegally has 2 control users (old & new loops). | |
680 clone_loop( loop, old_new, dd_main_exit ); | |
681 assert( old_new[main_end ->_idx]->Opcode() == Op_CountedLoopEnd, "" ); | |
682 CountedLoopNode *post_head = old_new[main_head->_idx]->as_CountedLoop(); | |
683 post_head->set_post_loop(main_head); | |
684 | |
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685 // Reduce the post-loop trip count. |
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686 CountedLoopEndNode* post_end = old_new[main_end ->_idx]->as_CountedLoopEnd(); |
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687 post_end->_prob = PROB_FAIR; |
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688 |
0 | 689 // Build the main-loop normal exit. |
690 IfFalseNode *new_main_exit = new (C, 1) IfFalseNode(main_end); | |
691 _igvn.register_new_node_with_optimizer( new_main_exit ); | |
692 set_idom(new_main_exit, main_end, dd_main_exit ); | |
693 set_loop(new_main_exit, loop->_parent); | |
694 | |
695 // Step A2: Build a zero-trip guard for the post-loop. After leaving the | |
696 // main-loop, the post-loop may not execute at all. We 'opaque' the incr | |
697 // (the main-loop trip-counter exit value) because we will be changing | |
698 // the exit value (via unrolling) so we cannot constant-fold away the zero | |
699 // trip guard until all unrolling is done. | |
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700 Node *zer_opaq = new (C, 2) Opaque1Node(C, incr); |
0 | 701 Node *zer_cmp = new (C, 3) CmpINode( zer_opaq, limit ); |
702 Node *zer_bol = new (C, 2) BoolNode( zer_cmp, b_test ); | |
703 register_new_node( zer_opaq, new_main_exit ); | |
704 register_new_node( zer_cmp , new_main_exit ); | |
705 register_new_node( zer_bol , new_main_exit ); | |
706 | |
707 // Build the IfNode | |
708 IfNode *zer_iff = new (C, 2) IfNode( new_main_exit, zer_bol, PROB_FAIR, COUNT_UNKNOWN ); | |
709 _igvn.register_new_node_with_optimizer( zer_iff ); | |
710 set_idom(zer_iff, new_main_exit, dd_main_exit); | |
711 set_loop(zer_iff, loop->_parent); | |
712 | |
713 // Plug in the false-path, taken if we need to skip post-loop | |
714 _igvn.hash_delete( main_exit ); | |
715 main_exit->set_req(0, zer_iff); | |
716 _igvn._worklist.push(main_exit); | |
717 set_idom(main_exit, zer_iff, dd_main_exit); | |
718 set_idom(main_exit->unique_out(), zer_iff, dd_main_exit); | |
719 // Make the true-path, must enter the post loop | |
720 Node *zer_taken = new (C, 1) IfTrueNode( zer_iff ); | |
721 _igvn.register_new_node_with_optimizer( zer_taken ); | |
722 set_idom(zer_taken, zer_iff, dd_main_exit); | |
723 set_loop(zer_taken, loop->_parent); | |
724 // Plug in the true path | |
725 _igvn.hash_delete( post_head ); | |
726 post_head->set_req(LoopNode::EntryControl, zer_taken); | |
727 set_idom(post_head, zer_taken, dd_main_exit); | |
728 | |
729 // Step A3: Make the fall-in values to the post-loop come from the | |
730 // fall-out values of the main-loop. | |
731 for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) { | |
732 Node* main_phi = main_head->fast_out(i); | |
733 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() >0 ) { | |
734 Node *post_phi = old_new[main_phi->_idx]; | |
735 Node *fallmain = clone_up_backedge_goo(main_head->back_control(), | |
736 post_head->init_control(), | |
737 main_phi->in(LoopNode::LoopBackControl)); | |
738 _igvn.hash_delete(post_phi); | |
739 post_phi->set_req( LoopNode::EntryControl, fallmain ); | |
740 } | |
741 } | |
742 | |
743 // Update local caches for next stanza | |
744 main_exit = new_main_exit; | |
745 | |
746 | |
747 //------------------------------ | |
748 // Step B: Create Pre-Loop. | |
749 | |
750 // Step B1: Clone the loop body. The clone becomes the pre-loop. The main | |
751 // loop pre-header illegally has 2 control users (old & new loops). | |
752 clone_loop( loop, old_new, dd_main_head ); | |
753 CountedLoopNode* pre_head = old_new[main_head->_idx]->as_CountedLoop(); | |
754 CountedLoopEndNode* pre_end = old_new[main_end ->_idx]->as_CountedLoopEnd(); | |
755 pre_head->set_pre_loop(main_head); | |
756 Node *pre_incr = old_new[incr->_idx]; | |
757 | |
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758 // Reduce the pre-loop trip count. |
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759 pre_end->_prob = PROB_FAIR; |
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760 |
0 | 761 // Find the pre-loop normal exit. |
762 Node* pre_exit = pre_end->proj_out(false); | |
763 assert( pre_exit->Opcode() == Op_IfFalse, "" ); | |
764 IfFalseNode *new_pre_exit = new (C, 1) IfFalseNode(pre_end); | |
765 _igvn.register_new_node_with_optimizer( new_pre_exit ); | |
766 set_idom(new_pre_exit, pre_end, dd_main_head); | |
767 set_loop(new_pre_exit, loop->_parent); | |
768 | |
769 // Step B2: Build a zero-trip guard for the main-loop. After leaving the | |
770 // pre-loop, the main-loop may not execute at all. Later in life this | |
771 // zero-trip guard will become the minimum-trip guard when we unroll | |
772 // the main-loop. | |
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773 Node *min_opaq = new (C, 2) Opaque1Node(C, limit); |
0 | 774 Node *min_cmp = new (C, 3) CmpINode( pre_incr, min_opaq ); |
775 Node *min_bol = new (C, 2) BoolNode( min_cmp, b_test ); | |
776 register_new_node( min_opaq, new_pre_exit ); | |
777 register_new_node( min_cmp , new_pre_exit ); | |
778 register_new_node( min_bol , new_pre_exit ); | |
779 | |
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780 // Build the IfNode (assume the main-loop is executed always). |
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781 IfNode *min_iff = new (C, 2) IfNode( new_pre_exit, min_bol, PROB_ALWAYS, COUNT_UNKNOWN ); |
0 | 782 _igvn.register_new_node_with_optimizer( min_iff ); |
783 set_idom(min_iff, new_pre_exit, dd_main_head); | |
784 set_loop(min_iff, loop->_parent); | |
785 | |
786 // Plug in the false-path, taken if we need to skip main-loop | |
787 _igvn.hash_delete( pre_exit ); | |
788 pre_exit->set_req(0, min_iff); | |
789 set_idom(pre_exit, min_iff, dd_main_head); | |
790 set_idom(pre_exit->unique_out(), min_iff, dd_main_head); | |
791 // Make the true-path, must enter the main loop | |
792 Node *min_taken = new (C, 1) IfTrueNode( min_iff ); | |
793 _igvn.register_new_node_with_optimizer( min_taken ); | |
794 set_idom(min_taken, min_iff, dd_main_head); | |
795 set_loop(min_taken, loop->_parent); | |
796 // Plug in the true path | |
797 _igvn.hash_delete( main_head ); | |
798 main_head->set_req(LoopNode::EntryControl, min_taken); | |
799 set_idom(main_head, min_taken, dd_main_head); | |
800 | |
801 // Step B3: Make the fall-in values to the main-loop come from the | |
802 // fall-out values of the pre-loop. | |
803 for (DUIterator_Fast i2max, i2 = main_head->fast_outs(i2max); i2 < i2max; i2++) { | |
804 Node* main_phi = main_head->fast_out(i2); | |
805 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0 ) { | |
806 Node *pre_phi = old_new[main_phi->_idx]; | |
807 Node *fallpre = clone_up_backedge_goo(pre_head->back_control(), | |
808 main_head->init_control(), | |
809 pre_phi->in(LoopNode::LoopBackControl)); | |
810 _igvn.hash_delete(main_phi); | |
811 main_phi->set_req( LoopNode::EntryControl, fallpre ); | |
812 } | |
813 } | |
814 | |
815 // Step B4: Shorten the pre-loop to run only 1 iteration (for now). | |
816 // RCE and alignment may change this later. | |
817 Node *cmp_end = pre_end->cmp_node(); | |
818 assert( cmp_end->in(2) == limit, "" ); | |
819 Node *pre_limit = new (C, 3) AddINode( init, stride ); | |
820 | |
821 // Save the original loop limit in this Opaque1 node for | |
822 // use by range check elimination. | |
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823 Node *pre_opaq = new (C, 3) Opaque1Node(C, pre_limit, limit); |
0 | 824 |
825 register_new_node( pre_limit, pre_head->in(0) ); | |
826 register_new_node( pre_opaq , pre_head->in(0) ); | |
827 | |
828 // Since no other users of pre-loop compare, I can hack limit directly | |
829 assert( cmp_end->outcnt() == 1, "no other users" ); | |
830 _igvn.hash_delete(cmp_end); | |
831 cmp_end->set_req(2, peel_only ? pre_limit : pre_opaq); | |
832 | |
833 // Special case for not-equal loop bounds: | |
834 // Change pre loop test, main loop test, and the | |
835 // main loop guard test to use lt or gt depending on stride | |
836 // direction: | |
837 // positive stride use < | |
838 // negative stride use > | |
839 | |
840 if (pre_end->in(CountedLoopEndNode::TestValue)->as_Bool()->_test._test == BoolTest::ne) { | |
841 | |
842 BoolTest::mask new_test = (main_end->stride_con() > 0) ? BoolTest::lt : BoolTest::gt; | |
843 // Modify pre loop end condition | |
844 Node* pre_bol = pre_end->in(CountedLoopEndNode::TestValue)->as_Bool(); | |
845 BoolNode* new_bol0 = new (C, 2) BoolNode(pre_bol->in(1), new_test); | |
846 register_new_node( new_bol0, pre_head->in(0) ); | |
847 _igvn.hash_delete(pre_end); | |
848 pre_end->set_req(CountedLoopEndNode::TestValue, new_bol0); | |
849 // Modify main loop guard condition | |
850 assert(min_iff->in(CountedLoopEndNode::TestValue) == min_bol, "guard okay"); | |
851 BoolNode* new_bol1 = new (C, 2) BoolNode(min_bol->in(1), new_test); | |
852 register_new_node( new_bol1, new_pre_exit ); | |
853 _igvn.hash_delete(min_iff); | |
854 min_iff->set_req(CountedLoopEndNode::TestValue, new_bol1); | |
855 // Modify main loop end condition | |
856 BoolNode* main_bol = main_end->in(CountedLoopEndNode::TestValue)->as_Bool(); | |
857 BoolNode* new_bol2 = new (C, 2) BoolNode(main_bol->in(1), new_test); | |
858 register_new_node( new_bol2, main_end->in(CountedLoopEndNode::TestControl) ); | |
859 _igvn.hash_delete(main_end); | |
860 main_end->set_req(CountedLoopEndNode::TestValue, new_bol2); | |
861 } | |
862 | |
863 // Flag main loop | |
864 main_head->set_main_loop(); | |
865 if( peel_only ) main_head->set_main_no_pre_loop(); | |
866 | |
867 // It's difficult to be precise about the trip-counts | |
868 // for the pre/post loops. They are usually very short, | |
869 // so guess that 4 trips is a reasonable value. | |
870 post_head->set_profile_trip_cnt(4.0); | |
871 pre_head->set_profile_trip_cnt(4.0); | |
872 | |
873 // Now force out all loop-invariant dominating tests. The optimizer | |
874 // finds some, but we _know_ they are all useless. | |
875 peeled_dom_test_elim(loop,old_new); | |
876 } | |
877 | |
878 //------------------------------is_invariant----------------------------- | |
879 // Return true if n is invariant | |
880 bool IdealLoopTree::is_invariant(Node* n) const { | |
1172 | 881 Node *n_c = _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n; |
0 | 882 if (n_c->is_top()) return false; |
883 return !is_member(_phase->get_loop(n_c)); | |
884 } | |
885 | |
886 | |
887 //------------------------------do_unroll-------------------------------------- | |
888 // Unroll the loop body one step - make each trip do 2 iterations. | |
889 void PhaseIdealLoop::do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ) { | |
890 assert( LoopUnrollLimit, "" ); | |
891 #ifndef PRODUCT | |
892 if( PrintOpto && VerifyLoopOptimizations ) { | |
893 tty->print("Unrolling "); | |
894 loop->dump_head(); | |
895 } | |
896 #endif | |
897 CountedLoopNode *loop_head = loop->_head->as_CountedLoop(); | |
898 CountedLoopEndNode *loop_end = loop_head->loopexit(); | |
899 assert( loop_end, "" ); | |
900 | |
901 // Remember loop node count before unrolling to detect | |
902 // if rounds of unroll,optimize are making progress | |
903 loop_head->set_node_count_before_unroll(loop->_body.size()); | |
904 | |
905 Node *ctrl = loop_head->in(LoopNode::EntryControl); | |
906 Node *limit = loop_head->limit(); | |
907 Node *init = loop_head->init_trip(); | |
908 Node *strid = loop_head->stride(); | |
909 | |
910 Node *opaq = NULL; | |
911 if( adjust_min_trip ) { // If not maximally unrolling, need adjustment | |
912 assert( loop_head->is_main_loop(), "" ); | |
913 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" ); | |
914 Node *iff = ctrl->in(0); | |
915 assert( iff->Opcode() == Op_If, "" ); | |
916 Node *bol = iff->in(1); | |
917 assert( bol->Opcode() == Op_Bool, "" ); | |
918 Node *cmp = bol->in(1); | |
919 assert( cmp->Opcode() == Op_CmpI, "" ); | |
920 opaq = cmp->in(2); | |
921 // Occasionally it's possible for a pre-loop Opaque1 node to be | |
922 // optimized away and then another round of loop opts attempted. | |
923 // We can not optimize this particular loop in that case. | |
924 if( opaq->Opcode() != Op_Opaque1 ) | |
925 return; // Cannot find pre-loop! Bail out! | |
926 } | |
927 | |
928 C->set_major_progress(); | |
929 | |
930 // Adjust max trip count. The trip count is intentionally rounded | |
931 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll, | |
932 // the main, unrolled, part of the loop will never execute as it is protected | |
933 // by the min-trip test. See bug 4834191 for a case where we over-unrolled | |
934 // and later determined that part of the unrolled loop was dead. | |
935 loop_head->set_trip_count(loop_head->trip_count() / 2); | |
936 | |
937 // Double the count of original iterations in the unrolled loop body. | |
938 loop_head->double_unrolled_count(); | |
939 | |
940 // ----------- | |
941 // Step 2: Cut back the trip counter for an unroll amount of 2. | |
942 // Loop will normally trip (limit - init)/stride_con. Since it's a | |
943 // CountedLoop this is exact (stride divides limit-init exactly). | |
944 // We are going to double the loop body, so we want to knock off any | |
945 // odd iteration: (trip_cnt & ~1). Then back compute a new limit. | |
946 Node *span = new (C, 3) SubINode( limit, init ); | |
947 register_new_node( span, ctrl ); | |
948 Node *trip = new (C, 3) DivINode( 0, span, strid ); | |
949 register_new_node( trip, ctrl ); | |
950 Node *mtwo = _igvn.intcon(-2); | |
951 set_ctrl(mtwo, C->root()); | |
952 Node *rond = new (C, 3) AndINode( trip, mtwo ); | |
953 register_new_node( rond, ctrl ); | |
954 Node *spn2 = new (C, 3) MulINode( rond, strid ); | |
955 register_new_node( spn2, ctrl ); | |
956 Node *lim2 = new (C, 3) AddINode( spn2, init ); | |
957 register_new_node( lim2, ctrl ); | |
958 | |
959 // Hammer in the new limit | |
960 Node *ctrl2 = loop_end->in(0); | |
961 Node *cmp2 = new (C, 3) CmpINode( loop_head->incr(), lim2 ); | |
962 register_new_node( cmp2, ctrl2 ); | |
963 Node *bol2 = new (C, 2) BoolNode( cmp2, loop_end->test_trip() ); | |
964 register_new_node( bol2, ctrl2 ); | |
965 _igvn.hash_delete(loop_end); | |
966 loop_end->set_req(CountedLoopEndNode::TestValue, bol2); | |
967 | |
968 // Step 3: Find the min-trip test guaranteed before a 'main' loop. | |
969 // Make it a 1-trip test (means at least 2 trips). | |
970 if( adjust_min_trip ) { | |
971 // Guard test uses an 'opaque' node which is not shared. Hence I | |
972 // can edit it's inputs directly. Hammer in the new limit for the | |
973 // minimum-trip guard. | |
974 assert( opaq->outcnt() == 1, "" ); | |
975 _igvn.hash_delete(opaq); | |
976 opaq->set_req(1, lim2); | |
977 } | |
978 | |
979 // --------- | |
980 // Step 4: Clone the loop body. Move it inside the loop. This loop body | |
981 // represents the odd iterations; since the loop trips an even number of | |
982 // times its backedge is never taken. Kill the backedge. | |
983 uint dd = dom_depth(loop_head); | |
984 clone_loop( loop, old_new, dd ); | |
985 | |
986 // Make backedges of the clone equal to backedges of the original. | |
987 // Make the fall-in from the original come from the fall-out of the clone. | |
988 for (DUIterator_Fast jmax, j = loop_head->fast_outs(jmax); j < jmax; j++) { | |
989 Node* phi = loop_head->fast_out(j); | |
990 if( phi->is_Phi() && phi->in(0) == loop_head && phi->outcnt() > 0 ) { | |
991 Node *newphi = old_new[phi->_idx]; | |
992 _igvn.hash_delete( phi ); | |
993 _igvn.hash_delete( newphi ); | |
994 | |
995 phi ->set_req(LoopNode:: EntryControl, newphi->in(LoopNode::LoopBackControl)); | |
996 newphi->set_req(LoopNode::LoopBackControl, phi ->in(LoopNode::LoopBackControl)); | |
997 phi ->set_req(LoopNode::LoopBackControl, C->top()); | |
998 } | |
999 } | |
1000 Node *clone_head = old_new[loop_head->_idx]; | |
1001 _igvn.hash_delete( clone_head ); | |
1002 loop_head ->set_req(LoopNode:: EntryControl, clone_head->in(LoopNode::LoopBackControl)); | |
1003 clone_head->set_req(LoopNode::LoopBackControl, loop_head ->in(LoopNode::LoopBackControl)); | |
1004 loop_head ->set_req(LoopNode::LoopBackControl, C->top()); | |
1005 loop->_head = clone_head; // New loop header | |
1006 | |
1007 set_idom(loop_head, loop_head ->in(LoopNode::EntryControl), dd); | |
1008 set_idom(clone_head, clone_head->in(LoopNode::EntryControl), dd); | |
1009 | |
1010 // Kill the clone's backedge | |
1011 Node *newcle = old_new[loop_end->_idx]; | |
1012 _igvn.hash_delete( newcle ); | |
1013 Node *one = _igvn.intcon(1); | |
1014 set_ctrl(one, C->root()); | |
1015 newcle->set_req(1, one); | |
1016 // Force clone into same loop body | |
1017 uint max = loop->_body.size(); | |
1018 for( uint k = 0; k < max; k++ ) { | |
1019 Node *old = loop->_body.at(k); | |
1020 Node *nnn = old_new[old->_idx]; | |
1021 loop->_body.push(nnn); | |
1022 if (!has_ctrl(old)) | |
1023 set_loop(nnn, loop); | |
1024 } | |
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1026 loop->record_for_igvn(); |
0 | 1027 } |
1028 | |
1029 //------------------------------do_maximally_unroll---------------------------- | |
1030 | |
1031 void PhaseIdealLoop::do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ) { | |
1032 CountedLoopNode *cl = loop->_head->as_CountedLoop(); | |
1033 assert( cl->trip_count() > 0, ""); | |
1034 | |
1035 // If loop is tripping an odd number of times, peel odd iteration | |
1036 if( (cl->trip_count() & 1) == 1 ) { | |
1037 do_peeling( loop, old_new ); | |
1038 } | |
1039 | |
1040 // Now its tripping an even number of times remaining. Double loop body. | |
1041 // Do not adjust pre-guards; they are not needed and do not exist. | |
1042 if( cl->trip_count() > 0 ) { | |
1043 do_unroll( loop, old_new, false ); | |
1044 } | |
1045 } | |
1046 | |
1047 //------------------------------dominates_backedge--------------------------------- | |
1048 // Returns true if ctrl is executed on every complete iteration | |
1049 bool IdealLoopTree::dominates_backedge(Node* ctrl) { | |
1050 assert(ctrl->is_CFG(), "must be control"); | |
1051 Node* backedge = _head->as_Loop()->in(LoopNode::LoopBackControl); | |
1052 return _phase->dom_lca_internal(ctrl, backedge) == ctrl; | |
1053 } | |
1054 | |
1055 //------------------------------add_constraint--------------------------------- | |
1056 // Constrain the main loop iterations so the condition: | |
1057 // scale_con * I + offset < limit | |
1058 // always holds true. That is, either increase the number of iterations in | |
1059 // the pre-loop or the post-loop until the condition holds true in the main | |
1060 // loop. Stride, scale, offset and limit are all loop invariant. Further, | |
1061 // stride and scale are constants (offset and limit often are). | |
1062 void PhaseIdealLoop::add_constraint( int stride_con, int scale_con, Node *offset, Node *limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit ) { | |
1063 | |
1064 // Compute "I :: (limit-offset)/scale_con" | |
1065 Node *con = new (C, 3) SubINode( limit, offset ); | |
1066 register_new_node( con, pre_ctrl ); | |
1067 Node *scale = _igvn.intcon(scale_con); | |
1068 set_ctrl(scale, C->root()); | |
1069 Node *X = new (C, 3) DivINode( 0, con, scale ); | |
1070 register_new_node( X, pre_ctrl ); | |
1071 | |
1072 // For positive stride, the pre-loop limit always uses a MAX function | |
1073 // and the main loop a MIN function. For negative stride these are | |
1074 // reversed. | |
1075 | |
1076 // Also for positive stride*scale the affine function is increasing, so the | |
1077 // pre-loop must check for underflow and the post-loop for overflow. | |
1078 // Negative stride*scale reverses this; pre-loop checks for overflow and | |
1079 // post-loop for underflow. | |
1080 if( stride_con*scale_con > 0 ) { | |
1081 // Compute I < (limit-offset)/scale_con | |
1082 // Adjust main-loop last iteration to be MIN/MAX(main_loop,X) | |
1083 *main_limit = (stride_con > 0) | |
1084 ? (Node*)(new (C, 3) MinINode( *main_limit, X )) | |
1085 : (Node*)(new (C, 3) MaxINode( *main_limit, X )); | |
1086 register_new_node( *main_limit, pre_ctrl ); | |
1087 | |
1088 } else { | |
1089 // Compute (limit-offset)/scale_con + SGN(-scale_con) <= I | |
1090 // Add the negation of the main-loop constraint to the pre-loop. | |
1091 // See footnote [++] below for a derivation of the limit expression. | |
1092 Node *incr = _igvn.intcon(scale_con > 0 ? -1 : 1); | |
1093 set_ctrl(incr, C->root()); | |
1094 Node *adj = new (C, 3) AddINode( X, incr ); | |
1095 register_new_node( adj, pre_ctrl ); | |
1096 *pre_limit = (scale_con > 0) | |
1097 ? (Node*)new (C, 3) MinINode( *pre_limit, adj ) | |
1098 : (Node*)new (C, 3) MaxINode( *pre_limit, adj ); | |
1099 register_new_node( *pre_limit, pre_ctrl ); | |
1100 | |
1101 // [++] Here's the algebra that justifies the pre-loop limit expression: | |
1102 // | |
1103 // NOT( scale_con * I + offset < limit ) | |
1104 // == | |
1105 // scale_con * I + offset >= limit | |
1106 // == | |
1107 // SGN(scale_con) * I >= (limit-offset)/|scale_con| | |
1108 // == | |
1109 // (limit-offset)/|scale_con| <= I * SGN(scale_con) | |
1110 // == | |
1111 // (limit-offset)/|scale_con|-1 < I * SGN(scale_con) | |
1112 // == | |
1113 // ( if (scale_con > 0) /*common case*/ | |
1114 // (limit-offset)/scale_con - 1 < I | |
1115 // else | |
1116 // (limit-offset)/scale_con + 1 > I | |
1117 // ) | |
1118 // ( if (scale_con > 0) /*common case*/ | |
1119 // (limit-offset)/scale_con + SGN(-scale_con) < I | |
1120 // else | |
1121 // (limit-offset)/scale_con + SGN(-scale_con) > I | |
1122 } | |
1123 } | |
1124 | |
1125 | |
1126 //------------------------------is_scaled_iv--------------------------------- | |
1127 // Return true if exp is a constant times an induction var | |
1128 bool PhaseIdealLoop::is_scaled_iv(Node* exp, Node* iv, int* p_scale) { | |
1129 if (exp == iv) { | |
1130 if (p_scale != NULL) { | |
1131 *p_scale = 1; | |
1132 } | |
1133 return true; | |
1134 } | |
1135 int opc = exp->Opcode(); | |
1136 if (opc == Op_MulI) { | |
1137 if (exp->in(1) == iv && exp->in(2)->is_Con()) { | |
1138 if (p_scale != NULL) { | |
1139 *p_scale = exp->in(2)->get_int(); | |
1140 } | |
1141 return true; | |
1142 } | |
1143 if (exp->in(2) == iv && exp->in(1)->is_Con()) { | |
1144 if (p_scale != NULL) { | |
1145 *p_scale = exp->in(1)->get_int(); | |
1146 } | |
1147 return true; | |
1148 } | |
1149 } else if (opc == Op_LShiftI) { | |
1150 if (exp->in(1) == iv && exp->in(2)->is_Con()) { | |
1151 if (p_scale != NULL) { | |
1152 *p_scale = 1 << exp->in(2)->get_int(); | |
1153 } | |
1154 return true; | |
1155 } | |
1156 } | |
1157 return false; | |
1158 } | |
1159 | |
1160 //-----------------------------is_scaled_iv_plus_offset------------------------------ | |
1161 // Return true if exp is a simple induction variable expression: k1*iv + (invar + k2) | |
1162 bool PhaseIdealLoop::is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth) { | |
1163 if (is_scaled_iv(exp, iv, p_scale)) { | |
1164 if (p_offset != NULL) { | |
1165 Node *zero = _igvn.intcon(0); | |
1166 set_ctrl(zero, C->root()); | |
1167 *p_offset = zero; | |
1168 } | |
1169 return true; | |
1170 } | |
1171 int opc = exp->Opcode(); | |
1172 if (opc == Op_AddI) { | |
1173 if (is_scaled_iv(exp->in(1), iv, p_scale)) { | |
1174 if (p_offset != NULL) { | |
1175 *p_offset = exp->in(2); | |
1176 } | |
1177 return true; | |
1178 } | |
1179 if (exp->in(2)->is_Con()) { | |
1180 Node* offset2 = NULL; | |
1181 if (depth < 2 && | |
1182 is_scaled_iv_plus_offset(exp->in(1), iv, p_scale, | |
1183 p_offset != NULL ? &offset2 : NULL, depth+1)) { | |
1184 if (p_offset != NULL) { | |
1185 Node *ctrl_off2 = get_ctrl(offset2); | |
1186 Node* offset = new (C, 3) AddINode(offset2, exp->in(2)); | |
1187 register_new_node(offset, ctrl_off2); | |
1188 *p_offset = offset; | |
1189 } | |
1190 return true; | |
1191 } | |
1192 } | |
1193 } else if (opc == Op_SubI) { | |
1194 if (is_scaled_iv(exp->in(1), iv, p_scale)) { | |
1195 if (p_offset != NULL) { | |
1196 Node *zero = _igvn.intcon(0); | |
1197 set_ctrl(zero, C->root()); | |
1198 Node *ctrl_off = get_ctrl(exp->in(2)); | |
1199 Node* offset = new (C, 3) SubINode(zero, exp->in(2)); | |
1200 register_new_node(offset, ctrl_off); | |
1201 *p_offset = offset; | |
1202 } | |
1203 return true; | |
1204 } | |
1205 if (is_scaled_iv(exp->in(2), iv, p_scale)) { | |
1206 if (p_offset != NULL) { | |
1207 *p_scale *= -1; | |
1208 *p_offset = exp->in(1); | |
1209 } | |
1210 return true; | |
1211 } | |
1212 } | |
1213 return false; | |
1214 } | |
1215 | |
1216 //------------------------------do_range_check--------------------------------- | |
1217 // Eliminate range-checks and other trip-counter vs loop-invariant tests. | |
1218 void PhaseIdealLoop::do_range_check( IdealLoopTree *loop, Node_List &old_new ) { | |
1219 #ifndef PRODUCT | |
1220 if( PrintOpto && VerifyLoopOptimizations ) { | |
1221 tty->print("Range Check Elimination "); | |
1222 loop->dump_head(); | |
1223 } | |
1224 #endif | |
1225 assert( RangeCheckElimination, "" ); | |
1226 CountedLoopNode *cl = loop->_head->as_CountedLoop(); | |
1227 assert( cl->is_main_loop(), "" ); | |
1228 | |
1229 // Find the trip counter; we are iteration splitting based on it | |
1230 Node *trip_counter = cl->phi(); | |
1231 // Find the main loop limit; we will trim it's iterations | |
1232 // to not ever trip end tests | |
1233 Node *main_limit = cl->limit(); | |
1234 // Find the pre-loop limit; we will expand it's iterations to | |
1235 // not ever trip low tests. | |
1236 Node *ctrl = cl->in(LoopNode::EntryControl); | |
1237 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" ); | |
1238 Node *iffm = ctrl->in(0); | |
1239 assert( iffm->Opcode() == Op_If, "" ); | |
1240 Node *p_f = iffm->in(0); | |
1241 assert( p_f->Opcode() == Op_IfFalse, "" ); | |
1242 CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd(); | |
1243 assert( pre_end->loopnode()->is_pre_loop(), "" ); | |
1244 Node *pre_opaq1 = pre_end->limit(); | |
1245 // Occasionally it's possible for a pre-loop Opaque1 node to be | |
1246 // optimized away and then another round of loop opts attempted. | |
1247 // We can not optimize this particular loop in that case. | |
1248 if( pre_opaq1->Opcode() != Op_Opaque1 ) | |
1249 return; | |
1250 Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1; | |
1251 Node *pre_limit = pre_opaq->in(1); | |
1252 | |
1253 // Where do we put new limit calculations | |
1254 Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl); | |
1255 | |
1256 // Ensure the original loop limit is available from the | |
1257 // pre-loop Opaque1 node. | |
1258 Node *orig_limit = pre_opaq->original_loop_limit(); | |
1259 if( orig_limit == NULL || _igvn.type(orig_limit) == Type::TOP ) | |
1260 return; | |
1261 | |
1262 // Need to find the main-loop zero-trip guard | |
1263 Node *bolzm = iffm->in(1); | |
1264 assert( bolzm->Opcode() == Op_Bool, "" ); | |
1265 Node *cmpzm = bolzm->in(1); | |
1266 assert( cmpzm->is_Cmp(), "" ); | |
1267 Node *opqzm = cmpzm->in(2); | |
1268 if( opqzm->Opcode() != Op_Opaque1 ) | |
1269 return; | |
1270 assert( opqzm->in(1) == main_limit, "do not understand situation" ); | |
1271 | |
1272 // Must know if its a count-up or count-down loop | |
1273 | |
1274 // protect against stride not being a constant | |
1275 if ( !cl->stride_is_con() ) { | |
1276 return; | |
1277 } | |
1278 int stride_con = cl->stride_con(); | |
1279 Node *zero = _igvn.intcon(0); | |
1280 Node *one = _igvn.intcon(1); | |
1281 set_ctrl(zero, C->root()); | |
1282 set_ctrl(one, C->root()); | |
1283 | |
1284 // Range checks that do not dominate the loop backedge (ie. | |
1285 // conditionally executed) can lengthen the pre loop limit beyond | |
1286 // the original loop limit. To prevent this, the pre limit is | |
1287 // (for stride > 0) MINed with the original loop limit (MAXed | |
1288 // stride < 0) when some range_check (rc) is conditionally | |
1289 // executed. | |
1290 bool conditional_rc = false; | |
1291 | |
1292 // Check loop body for tests of trip-counter plus loop-invariant vs | |
1293 // loop-invariant. | |
1294 for( uint i = 0; i < loop->_body.size(); i++ ) { | |
1295 Node *iff = loop->_body[i]; | |
1296 if( iff->Opcode() == Op_If ) { // Test? | |
1297 | |
1298 // Test is an IfNode, has 2 projections. If BOTH are in the loop | |
1299 // we need loop unswitching instead of iteration splitting. | |
1300 Node *exit = loop->is_loop_exit(iff); | |
1301 if( !exit ) continue; | |
1302 int flip = (exit->Opcode() == Op_IfTrue) ? 1 : 0; | |
1303 | |
1304 // Get boolean condition to test | |
1305 Node *i1 = iff->in(1); | |
1306 if( !i1->is_Bool() ) continue; | |
1307 BoolNode *bol = i1->as_Bool(); | |
1308 BoolTest b_test = bol->_test; | |
1309 // Flip sense of test if exit condition is flipped | |
1310 if( flip ) | |
1311 b_test = b_test.negate(); | |
1312 | |
1313 // Get compare | |
1314 Node *cmp = bol->in(1); | |
1315 | |
1316 // Look for trip_counter + offset vs limit | |
1317 Node *rc_exp = cmp->in(1); | |
1318 Node *limit = cmp->in(2); | |
1319 jint scale_con= 1; // Assume trip counter not scaled | |
1320 | |
1321 Node *limit_c = get_ctrl(limit); | |
1322 if( loop->is_member(get_loop(limit_c) ) ) { | |
1323 // Compare might have operands swapped; commute them | |
1324 b_test = b_test.commute(); | |
1325 rc_exp = cmp->in(2); | |
1326 limit = cmp->in(1); | |
1327 limit_c = get_ctrl(limit); | |
1328 if( loop->is_member(get_loop(limit_c) ) ) | |
1329 continue; // Both inputs are loop varying; cannot RCE | |
1330 } | |
1331 // Here we know 'limit' is loop invariant | |
1332 | |
1333 // 'limit' maybe pinned below the zero trip test (probably from a | |
1334 // previous round of rce), in which case, it can't be used in the | |
1335 // zero trip test expression which must occur before the zero test's if. | |
1336 if( limit_c == ctrl ) { | |
1337 continue; // Don't rce this check but continue looking for other candidates. | |
1338 } | |
1339 | |
1340 // Check for scaled induction variable plus an offset | |
1341 Node *offset = NULL; | |
1342 | |
1343 if (!is_scaled_iv_plus_offset(rc_exp, trip_counter, &scale_con, &offset)) { | |
1344 continue; | |
1345 } | |
1346 | |
1347 Node *offset_c = get_ctrl(offset); | |
1348 if( loop->is_member( get_loop(offset_c) ) ) | |
1349 continue; // Offset is not really loop invariant | |
1350 // Here we know 'offset' is loop invariant. | |
1351 | |
1352 // As above for the 'limit', the 'offset' maybe pinned below the | |
1353 // zero trip test. | |
1354 if( offset_c == ctrl ) { | |
1355 continue; // Don't rce this check but continue looking for other candidates. | |
1356 } | |
1357 | |
1358 // At this point we have the expression as: | |
1359 // scale_con * trip_counter + offset :: limit | |
1360 // where scale_con, offset and limit are loop invariant. Trip_counter | |
1361 // monotonically increases by stride_con, a constant. Both (or either) | |
1362 // stride_con and scale_con can be negative which will flip about the | |
1363 // sense of the test. | |
1364 | |
1365 // Adjust pre and main loop limits to guard the correct iteration set | |
1366 if( cmp->Opcode() == Op_CmpU ) {// Unsigned compare is really 2 tests | |
1367 if( b_test._test == BoolTest::lt ) { // Range checks always use lt | |
1368 // The overflow limit: scale*I+offset < limit | |
1369 add_constraint( stride_con, scale_con, offset, limit, pre_ctrl, &pre_limit, &main_limit ); | |
1370 // The underflow limit: 0 <= scale*I+offset. | |
1371 // Some math yields: -scale*I-(offset+1) < 0 | |
1372 Node *plus_one = new (C, 3) AddINode( offset, one ); | |
1373 register_new_node( plus_one, pre_ctrl ); | |
1374 Node *neg_offset = new (C, 3) SubINode( zero, plus_one ); | |
1375 register_new_node( neg_offset, pre_ctrl ); | |
1376 add_constraint( stride_con, -scale_con, neg_offset, zero, pre_ctrl, &pre_limit, &main_limit ); | |
1377 if (!conditional_rc) { | |
1378 conditional_rc = !loop->dominates_backedge(iff); | |
1379 } | |
1380 } else { | |
1381 #ifndef PRODUCT | |
1382 if( PrintOpto ) | |
1383 tty->print_cr("missed RCE opportunity"); | |
1384 #endif | |
1385 continue; // In release mode, ignore it | |
1386 } | |
1387 } else { // Otherwise work on normal compares | |
1388 switch( b_test._test ) { | |
1389 case BoolTest::ge: // Convert X >= Y to -X <= -Y | |
1390 scale_con = -scale_con; | |
1391 offset = new (C, 3) SubINode( zero, offset ); | |
1392 register_new_node( offset, pre_ctrl ); | |
1393 limit = new (C, 3) SubINode( zero, limit ); | |
1394 register_new_node( limit, pre_ctrl ); | |
1395 // Fall into LE case | |
1396 case BoolTest::le: // Convert X <= Y to X < Y+1 | |
1397 limit = new (C, 3) AddINode( limit, one ); | |
1398 register_new_node( limit, pre_ctrl ); | |
1399 // Fall into LT case | |
1400 case BoolTest::lt: | |
1401 add_constraint( stride_con, scale_con, offset, limit, pre_ctrl, &pre_limit, &main_limit ); | |
1402 if (!conditional_rc) { | |
1403 conditional_rc = !loop->dominates_backedge(iff); | |
1404 } | |
1405 break; | |
1406 default: | |
1407 #ifndef PRODUCT | |
1408 if( PrintOpto ) | |
1409 tty->print_cr("missed RCE opportunity"); | |
1410 #endif | |
1411 continue; // Unhandled case | |
1412 } | |
1413 } | |
1414 | |
1415 // Kill the eliminated test | |
1416 C->set_major_progress(); | |
1417 Node *kill_con = _igvn.intcon( 1-flip ); | |
1418 set_ctrl(kill_con, C->root()); | |
1419 _igvn.hash_delete(iff); | |
1420 iff->set_req(1, kill_con); | |
1421 _igvn._worklist.push(iff); | |
1422 // Find surviving projection | |
1423 assert(iff->is_If(), ""); | |
1424 ProjNode* dp = ((IfNode*)iff)->proj_out(1-flip); | |
1425 // Find loads off the surviving projection; remove their control edge | |
1426 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) { | |
1427 Node* cd = dp->fast_out(i); // Control-dependent node | |
1428 if( cd->is_Load() ) { // Loads can now float around in the loop | |
1429 _igvn.hash_delete(cd); | |
1430 // Allow the load to float around in the loop, or before it | |
1431 // but NOT before the pre-loop. | |
1432 cd->set_req(0, ctrl); // ctrl, not NULL | |
1433 _igvn._worklist.push(cd); | |
1434 --i; | |
1435 --imax; | |
1436 } | |
1437 } | |
1438 | |
1439 } // End of is IF | |
1440 | |
1441 } | |
1442 | |
1443 // Update loop limits | |
1444 if (conditional_rc) { | |
1445 pre_limit = (stride_con > 0) ? (Node*)new (C,3) MinINode(pre_limit, orig_limit) | |
1446 : (Node*)new (C,3) MaxINode(pre_limit, orig_limit); | |
1447 register_new_node(pre_limit, pre_ctrl); | |
1448 } | |
1449 _igvn.hash_delete(pre_opaq); | |
1450 pre_opaq->set_req(1, pre_limit); | |
1451 | |
1452 // Note:: we are making the main loop limit no longer precise; | |
1453 // need to round up based on stride. | |
1454 if( stride_con != 1 && stride_con != -1 ) { // Cutout for common case | |
1455 // "Standard" round-up logic: ([main_limit-init+(y-1)]/y)*y+init | |
1456 // Hopefully, compiler will optimize for powers of 2. | |
1457 Node *ctrl = get_ctrl(main_limit); | |
1458 Node *stride = cl->stride(); | |
1459 Node *init = cl->init_trip(); | |
1460 Node *span = new (C, 3) SubINode(main_limit,init); | |
1461 register_new_node(span,ctrl); | |
1462 Node *rndup = _igvn.intcon(stride_con + ((stride_con>0)?-1:1)); | |
1463 Node *add = new (C, 3) AddINode(span,rndup); | |
1464 register_new_node(add,ctrl); | |
1465 Node *div = new (C, 3) DivINode(0,add,stride); | |
1466 register_new_node(div,ctrl); | |
1467 Node *mul = new (C, 3) MulINode(div,stride); | |
1468 register_new_node(mul,ctrl); | |
1469 Node *newlim = new (C, 3) AddINode(mul,init); | |
1470 register_new_node(newlim,ctrl); | |
1471 main_limit = newlim; | |
1472 } | |
1473 | |
1474 Node *main_cle = cl->loopexit(); | |
1475 Node *main_bol = main_cle->in(1); | |
1476 // Hacking loop bounds; need private copies of exit test | |
1477 if( main_bol->outcnt() > 1 ) {// BoolNode shared? | |
1478 _igvn.hash_delete(main_cle); | |
1479 main_bol = main_bol->clone();// Clone a private BoolNode | |
1480 register_new_node( main_bol, main_cle->in(0) ); | |
1481 main_cle->set_req(1,main_bol); | |
1482 } | |
1483 Node *main_cmp = main_bol->in(1); | |
1484 if( main_cmp->outcnt() > 1 ) { // CmpNode shared? | |
1485 _igvn.hash_delete(main_bol); | |
1486 main_cmp = main_cmp->clone();// Clone a private CmpNode | |
1487 register_new_node( main_cmp, main_cle->in(0) ); | |
1488 main_bol->set_req(1,main_cmp); | |
1489 } | |
1490 // Hack the now-private loop bounds | |
1491 _igvn.hash_delete(main_cmp); | |
1492 main_cmp->set_req(2, main_limit); | |
1493 _igvn._worklist.push(main_cmp); | |
1494 // The OpaqueNode is unshared by design | |
1495 _igvn.hash_delete(opqzm); | |
1496 assert( opqzm->outcnt() == 1, "cannot hack shared node" ); | |
1497 opqzm->set_req(1,main_limit); | |
1498 _igvn._worklist.push(opqzm); | |
1499 } | |
1500 | |
1501 //------------------------------DCE_loop_body---------------------------------- | |
1502 // Remove simplistic dead code from loop body | |
1503 void IdealLoopTree::DCE_loop_body() { | |
1504 for( uint i = 0; i < _body.size(); i++ ) | |
1505 if( _body.at(i)->outcnt() == 0 ) | |
1506 _body.map( i--, _body.pop() ); | |
1507 } | |
1508 | |
1509 | |
1510 //------------------------------adjust_loop_exit_prob-------------------------- | |
1511 // Look for loop-exit tests with the 50/50 (or worse) guesses from the parsing stage. | |
1512 // Replace with a 1-in-10 exit guess. | |
1513 void IdealLoopTree::adjust_loop_exit_prob( PhaseIdealLoop *phase ) { | |
1514 Node *test = tail(); | |
1515 while( test != _head ) { | |
1516 uint top = test->Opcode(); | |
1517 if( top == Op_IfTrue || top == Op_IfFalse ) { | |
1518 int test_con = ((ProjNode*)test)->_con; | |
1519 assert(top == (uint)(test_con? Op_IfTrue: Op_IfFalse), "sanity"); | |
1520 IfNode *iff = test->in(0)->as_If(); | |
1521 if( iff->outcnt() == 2 ) { // Ignore dead tests | |
1522 Node *bol = iff->in(1); | |
1523 if( bol && bol->req() > 1 && bol->in(1) && | |
1524 ((bol->in(1)->Opcode() == Op_StorePConditional ) || | |
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1525 (bol->in(1)->Opcode() == Op_StoreIConditional ) || |
0 | 1526 (bol->in(1)->Opcode() == Op_StoreLConditional ) || |
1527 (bol->in(1)->Opcode() == Op_CompareAndSwapI ) || | |
1528 (bol->in(1)->Opcode() == Op_CompareAndSwapL ) || | |
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1529 (bol->in(1)->Opcode() == Op_CompareAndSwapP ) || |
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1530 (bol->in(1)->Opcode() == Op_CompareAndSwapN ))) |
0 | 1531 return; // Allocation loops RARELY take backedge |
1532 // Find the OTHER exit path from the IF | |
1533 Node* ex = iff->proj_out(1-test_con); | |
1534 float p = iff->_prob; | |
1535 if( !phase->is_member( this, ex ) && iff->_fcnt == COUNT_UNKNOWN ) { | |
1536 if( top == Op_IfTrue ) { | |
1537 if( p < (PROB_FAIR + PROB_UNLIKELY_MAG(3))) { | |
1538 iff->_prob = PROB_STATIC_FREQUENT; | |
1539 } | |
1540 } else { | |
1541 if( p > (PROB_FAIR - PROB_UNLIKELY_MAG(3))) { | |
1542 iff->_prob = PROB_STATIC_INFREQUENT; | |
1543 } | |
1544 } | |
1545 } | |
1546 } | |
1547 } | |
1548 test = phase->idom(test); | |
1549 } | |
1550 } | |
1551 | |
1552 | |
1553 //------------------------------policy_do_remove_empty_loop-------------------- | |
1554 // Micro-benchmark spamming. Policy is to always remove empty loops. | |
1555 // The 'DO' part is to replace the trip counter with the value it will | |
1556 // have on the last iteration. This will break the loop. | |
1557 bool IdealLoopTree::policy_do_remove_empty_loop( PhaseIdealLoop *phase ) { | |
1558 // Minimum size must be empty loop | |
1559 if( _body.size() > 7/*number of nodes in an empty loop*/ ) return false; | |
1560 | |
1561 if( !_head->is_CountedLoop() ) return false; // Dead loop | |
1562 CountedLoopNode *cl = _head->as_CountedLoop(); | |
1563 if( !cl->loopexit() ) return false; // Malformed loop | |
1564 if( !phase->is_member(this,phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue)) ) ) | |
1565 return false; // Infinite loop | |
1566 #ifndef PRODUCT | |
1567 if( PrintOpto ) | |
1568 tty->print_cr("Removing empty loop"); | |
1569 #endif | |
1570 #ifdef ASSERT | |
1571 // Ensure only one phi which is the iv. | |
1572 Node* iv = NULL; | |
1573 for (DUIterator_Fast imax, i = cl->fast_outs(imax); i < imax; i++) { | |
1574 Node* n = cl->fast_out(i); | |
1575 if (n->Opcode() == Op_Phi) { | |
1576 assert(iv == NULL, "Too many phis" ); | |
1577 iv = n; | |
1578 } | |
1579 } | |
1580 assert(iv == cl->phi(), "Wrong phi" ); | |
1581 #endif | |
1582 // Replace the phi at loop head with the final value of the last | |
1583 // iteration. Then the CountedLoopEnd will collapse (backedge never | |
1584 // taken) and all loop-invariant uses of the exit values will be correct. | |
1585 Node *phi = cl->phi(); | |
1586 Node *final = new (phase->C, 3) SubINode( cl->limit(), cl->stride() ); | |
1587 phase->register_new_node(final,cl->in(LoopNode::EntryControl)); | |
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1588 phase->_igvn.replace_node(phi,final); |
0 | 1589 phase->C->set_major_progress(); |
1590 return true; | |
1591 } | |
1592 | |
1593 | |
1594 //============================================================================= | |
1595 //------------------------------iteration_split_impl--------------------------- | |
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1596 bool IdealLoopTree::iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ) { |
0 | 1597 // Check and remove empty loops (spam micro-benchmarks) |
1598 if( policy_do_remove_empty_loop(phase) ) | |
1172 | 1599 return true; // Here we removed an empty loop |
0 | 1600 |
1601 bool should_peel = policy_peeling(phase); // Should we peel? | |
1602 | |
1603 bool should_unswitch = policy_unswitching(phase); | |
1604 | |
1605 // Non-counted loops may be peeled; exactly 1 iteration is peeled. | |
1606 // This removes loop-invariant tests (usually null checks). | |
1607 if( !_head->is_CountedLoop() ) { // Non-counted loop | |
1608 if (PartialPeelLoop && phase->partial_peel(this, old_new)) { | |
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1609 // Partial peel succeeded so terminate this round of loop opts |
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1610 return false; |
0 | 1611 } |
1612 if( should_peel ) { // Should we peel? | |
1613 #ifndef PRODUCT | |
1614 if (PrintOpto) tty->print_cr("should_peel"); | |
1615 #endif | |
1616 phase->do_peeling(this,old_new); | |
1617 } else if( should_unswitch ) { | |
1618 phase->do_unswitching(this, old_new); | |
1619 } | |
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1620 return true; |
0 | 1621 } |
1622 CountedLoopNode *cl = _head->as_CountedLoop(); | |
1623 | |
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1624 if( !cl->loopexit() ) return true; // Ignore various kinds of broken loops |
0 | 1625 |
1626 // Do nothing special to pre- and post- loops | |
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1627 if( cl->is_pre_loop() || cl->is_post_loop() ) return true; |
0 | 1628 |
1629 // Compute loop trip count from profile data | |
1630 compute_profile_trip_cnt(phase); | |
1631 | |
1632 // Before attempting fancy unrolling, RCE or alignment, see if we want | |
1633 // to completely unroll this loop or do loop unswitching. | |
1634 if( cl->is_normal_loop() ) { | |
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1635 if (should_unswitch) { |
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1636 phase->do_unswitching(this, old_new); |
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1637 return true; |
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1638 } |
0 | 1639 bool should_maximally_unroll = policy_maximally_unroll(phase); |
1640 if( should_maximally_unroll ) { | |
1641 // Here we did some unrolling and peeling. Eventually we will | |
1642 // completely unroll this loop and it will no longer be a loop. | |
1643 phase->do_maximally_unroll(this,old_new); | |
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1644 return true; |
0 | 1645 } |
1646 } | |
1647 | |
1648 | |
1649 // Counted loops may be peeled, may need some iterations run up | |
1650 // front for RCE, and may want to align loop refs to a cache | |
1651 // line. Thus we clone a full loop up front whose trip count is | |
1652 // at least 1 (if peeling), but may be several more. | |
1653 | |
1654 // The main loop will start cache-line aligned with at least 1 | |
1655 // iteration of the unrolled body (zero-trip test required) and | |
1656 // will have some range checks removed. | |
1657 | |
1658 // A post-loop will finish any odd iterations (leftover after | |
1659 // unrolling), plus any needed for RCE purposes. | |
1660 | |
1661 bool should_unroll = policy_unroll(phase); | |
1662 | |
1663 bool should_rce = policy_range_check(phase); | |
1664 | |
1665 bool should_align = policy_align(phase); | |
1666 | |
1667 // If not RCE'ing (iteration splitting) or Aligning, then we do not | |
1668 // need a pre-loop. We may still need to peel an initial iteration but | |
1669 // we will not be needing an unknown number of pre-iterations. | |
1670 // | |
1671 // Basically, if may_rce_align reports FALSE first time through, | |
1672 // we will not be able to later do RCE or Aligning on this loop. | |
1673 bool may_rce_align = !policy_peel_only(phase) || should_rce || should_align; | |
1674 | |
1675 // If we have any of these conditions (RCE, alignment, unrolling) met, then | |
1676 // we switch to the pre-/main-/post-loop model. This model also covers | |
1677 // peeling. | |
1678 if( should_rce || should_align || should_unroll ) { | |
1679 if( cl->is_normal_loop() ) // Convert to 'pre/main/post' loops | |
1680 phase->insert_pre_post_loops(this,old_new, !may_rce_align); | |
1681 | |
1682 // Adjust the pre- and main-loop limits to let the pre and post loops run | |
1683 // with full checks, but the main-loop with no checks. Remove said | |
1684 // checks from the main body. | |
1685 if( should_rce ) | |
1686 phase->do_range_check(this,old_new); | |
1687 | |
1688 // Double loop body for unrolling. Adjust the minimum-trip test (will do | |
1689 // twice as many iterations as before) and the main body limit (only do | |
1690 // an even number of trips). If we are peeling, we might enable some RCE | |
1691 // and we'd rather unroll the post-RCE'd loop SO... do not unroll if | |
1692 // peeling. | |
1172 | 1693 if( should_unroll && !should_peel ) |
1694 phase->do_unroll(this,old_new, true); | |
0 | 1695 |
1696 // Adjust the pre-loop limits to align the main body | |
1697 // iterations. | |
1698 if( should_align ) | |
1699 Unimplemented(); | |
1700 | |
1701 } else { // Else we have an unchanged counted loop | |
1702 if( should_peel ) // Might want to peel but do nothing else | |
1703 phase->do_peeling(this,old_new); | |
1704 } | |
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1705 return true; |
0 | 1706 } |
1707 | |
1708 | |
1709 //============================================================================= | |
1710 //------------------------------iteration_split-------------------------------- | |
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1711 bool IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new ) { |
0 | 1712 // Recursively iteration split nested loops |
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1713 if( _child && !_child->iteration_split( phase, old_new )) |
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1714 return false; |
0 | 1715 |
1716 // Clean out prior deadwood | |
1717 DCE_loop_body(); | |
1718 | |
1719 | |
1720 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage. | |
1721 // Replace with a 1-in-10 exit guess. | |
1722 if( _parent /*not the root loop*/ && | |
1723 !_irreducible && | |
1724 // Also ignore the occasional dead backedge | |
1725 !tail()->is_top() ) { | |
1726 adjust_loop_exit_prob(phase); | |
1727 } | |
1728 | |
1729 | |
1730 // Gate unrolling, RCE and peeling efforts. | |
1731 if( !_child && // If not an inner loop, do not split | |
1732 !_irreducible && | |
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1733 _allow_optimizations && |
0 | 1734 !tail()->is_top() ) { // Also ignore the occasional dead backedge |
1735 if (!_has_call) { | |
1172 | 1736 if (!iteration_split_impl( phase, old_new )) { |
1737 return false; | |
1738 } | |
0 | 1739 } else if (policy_unswitching(phase)) { |
1740 phase->do_unswitching(this, old_new); | |
1741 } | |
1742 } | |
1743 | |
1744 // Minor offset re-organization to remove loop-fallout uses of | |
1745 // trip counter. | |
1746 if( _head->is_CountedLoop() ) phase->reorg_offsets( this ); | |
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1747 if( _next && !_next->iteration_split( phase, old_new )) |
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1748 return false; |
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1749 return true; |
0 | 1750 } |
1172 | 1751 |
1752 //-------------------------------is_uncommon_trap_proj---------------------------- | |
1753 // Return true if proj is the form of "proj->[region->..]call_uct" | |
1754 bool PhaseIdealLoop::is_uncommon_trap_proj(ProjNode* proj, bool must_reason_predicate) { | |
1755 int path_limit = 10; | |
1756 assert(proj, "invalid argument"); | |
1757 Node* out = proj; | |
1758 for (int ct = 0; ct < path_limit; ct++) { | |
1759 out = out->unique_ctrl_out(); | |
1760 if (out == NULL || out->is_Root() || out->is_Start()) | |
1761 return false; | |
1762 if (out->is_CallStaticJava()) { | |
1763 int req = out->as_CallStaticJava()->uncommon_trap_request(); | |
1764 if (req != 0) { | |
1765 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(req); | |
1766 if (!must_reason_predicate || reason == Deoptimization::Reason_predicate){ | |
1767 return true; | |
1768 } | |
1769 } | |
1770 return false; // don't do further after call | |
1771 } | |
1772 } | |
1773 return false; | |
1774 } | |
1775 | |
1776 //-------------------------------is_uncommon_trap_if_pattern------------------------- | |
1777 // Return true for "if(test)-> proj -> ... | |
1778 // | | |
1779 // V | |
1780 // other_proj->[region->..]call_uct" | |
1781 // | |
1782 // "must_reason_predicate" means the uct reason must be Reason_predicate | |
1783 bool PhaseIdealLoop::is_uncommon_trap_if_pattern(ProjNode *proj, bool must_reason_predicate) { | |
1784 Node *in0 = proj->in(0); | |
1785 if (!in0->is_If()) return false; | |
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1786 // Variation of a dead If node. |
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1787 if (in0->outcnt() < 2) return false; |
1172 | 1788 IfNode* iff = in0->as_If(); |
1789 | |
1790 // we need "If(Conv2B(Opaque1(...)))" pattern for must_reason_predicate | |
1791 if (must_reason_predicate) { | |
1792 if (iff->in(1)->Opcode() != Op_Conv2B || | |
1793 iff->in(1)->in(1)->Opcode() != Op_Opaque1) { | |
1794 return false; | |
1795 } | |
1796 } | |
1797 | |
1798 ProjNode* other_proj = iff->proj_out(1-proj->_con)->as_Proj(); | |
1799 return is_uncommon_trap_proj(other_proj, must_reason_predicate); | |
1800 } | |
1801 | |
1802 //------------------------------create_new_if_for_predicate------------------------ | |
1803 // create a new if above the uct_if_pattern for the predicate to be promoted. | |
1804 // | |
1805 // before after | |
1806 // ---------- ---------- | |
1807 // ctrl ctrl | |
1808 // | | | |
1809 // | | | |
1810 // v v | |
1811 // iff new_iff | |
1812 // / \ / \ | |
1813 // / \ / \ | |
1814 // v v v v | |
1815 // uncommon_proj cont_proj if_uct if_cont | |
1816 // \ | | | | | |
1817 // \ | | | | | |
1818 // v v v | v | |
1819 // rgn loop | iff | |
1820 // | | / \ | |
1821 // | | / \ | |
1822 // v | v v | |
1823 // uncommon_trap | uncommon_proj cont_proj | |
1824 // \ \ | | | |
1825 // \ \ | | | |
1826 // v v v v | |
1827 // rgn loop | |
1828 // | | |
1829 // | | |
1830 // v | |
1831 // uncommon_trap | |
1832 // | |
1833 // | |
1834 // We will create a region to guard the uct call if there is no one there. | |
1835 // The true projecttion (if_cont) of the new_iff is returned. | |
1836 ProjNode* PhaseIdealLoop::create_new_if_for_predicate(ProjNode* cont_proj) { | |
1837 assert(is_uncommon_trap_if_pattern(cont_proj, true), "must be a uct if pattern!"); | |
1838 IfNode* iff = cont_proj->in(0)->as_If(); | |
1839 | |
1840 ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con); | |
1841 Node *rgn = uncommon_proj->unique_ctrl_out(); | |
1842 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct"); | |
1843 | |
1844 if (!rgn->is_Region()) { // create a region to guard the call | |
1845 assert(rgn->is_Call(), "must be call uct"); | |
1846 CallNode* call = rgn->as_Call(); | |
1847 rgn = new (C, 1) RegionNode(1); | |
1848 _igvn.set_type(rgn, rgn->bottom_type()); | |
1849 rgn->add_req(uncommon_proj); | |
1850 set_idom(rgn, idom(uncommon_proj), dom_depth(uncommon_proj)+1); | |
1851 _igvn.hash_delete(call); | |
1852 call->set_req(0, rgn); | |
1853 } | |
1854 | |
1855 // Create new_iff | |
1856 uint iffdd = dom_depth(iff); | |
1857 IdealLoopTree* lp = get_loop(iff); | |
1858 IfNode *new_iff = new (C, 2) IfNode(iff->in(0), NULL, iff->_prob, iff->_fcnt); | |
1859 register_node(new_iff, lp, idom(iff), iffdd); | |
1860 Node *if_cont = new (C, 1) IfTrueNode(new_iff); | |
1861 Node *if_uct = new (C, 1) IfFalseNode(new_iff); | |
1862 if (cont_proj->is_IfFalse()) { | |
1863 // Swap | |
1864 Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp; | |
1865 } | |
1866 register_node(if_cont, lp, new_iff, iffdd); | |
1867 register_node(if_uct, get_loop(rgn), new_iff, iffdd); | |
1868 | |
1869 // if_cont to iff | |
1870 _igvn.hash_delete(iff); | |
1871 iff->set_req(0, if_cont); | |
1872 set_idom(iff, if_cont, dom_depth(iff)); | |
1873 | |
1874 // if_uct to rgn | |
1875 _igvn.hash_delete(rgn); | |
1876 rgn->add_req(if_uct); | |
1877 Node* ridom = idom(rgn); | |
1878 Node* nrdom = dom_lca(ridom, new_iff); | |
1879 set_idom(rgn, nrdom, dom_depth(rgn)); | |
1880 | |
1881 // rgn must have no phis | |
1882 assert(!rgn->as_Region()->has_phi(), "region must have no phis"); | |
1883 | |
1884 return if_cont->as_Proj(); | |
1885 } | |
1886 | |
1887 //------------------------------find_predicate_insertion_point-------------------------- | |
1888 // Find a good location to insert a predicate | |
1889 ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c) { | |
1890 if (start_c == C->root() || !start_c->is_Proj()) | |
1891 return NULL; | |
1892 if (is_uncommon_trap_if_pattern(start_c->as_Proj(), true/*Reason_Predicate*/)) { | |
1893 return start_c->as_Proj(); | |
1894 } | |
1895 return NULL; | |
1896 } | |
1897 | |
1898 //------------------------------Invariance----------------------------------- | |
1899 // Helper class for loop_predication_impl to compute invariance on the fly and | |
1900 // clone invariants. | |
1901 class Invariance : public StackObj { | |
1902 VectorSet _visited, _invariant; | |
1903 Node_Stack _stack; | |
1904 VectorSet _clone_visited; | |
1905 Node_List _old_new; // map of old to new (clone) | |
1906 IdealLoopTree* _lpt; | |
1907 PhaseIdealLoop* _phase; | |
1908 | |
1909 // Helper function to set up the invariance for invariance computation | |
1910 // If n is a known invariant, set up directly. Otherwise, look up the | |
1911 // the possibility to push n onto the stack for further processing. | |
1912 void visit(Node* use, Node* n) { | |
1913 if (_lpt->is_invariant(n)) { // known invariant | |
1914 _invariant.set(n->_idx); | |
1915 } else if (!n->is_CFG()) { | |
1916 Node *n_ctrl = _phase->ctrl_or_self(n); | |
1917 Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG | |
1918 if (_phase->is_dominator(n_ctrl, u_ctrl)) { | |
1919 _stack.push(n, n->in(0) == NULL ? 1 : 0); | |
1920 } | |
1921 } | |
1922 } | |
1923 | |
1924 // Compute invariance for "the_node" and (possibly) all its inputs recursively | |
1925 // on the fly | |
1926 void compute_invariance(Node* n) { | |
1927 assert(_visited.test(n->_idx), "must be"); | |
1928 visit(n, n); | |
1929 while (_stack.is_nonempty()) { | |
1930 Node* n = _stack.node(); | |
1931 uint idx = _stack.index(); | |
1932 if (idx == n->req()) { // all inputs are processed | |
1933 _stack.pop(); | |
1934 // n is invariant if it's inputs are all invariant | |
1935 bool all_inputs_invariant = true; | |
1936 for (uint i = 0; i < n->req(); i++) { | |
1937 Node* in = n->in(i); | |
1938 if (in == NULL) continue; | |
1939 assert(_visited.test(in->_idx), "must have visited input"); | |
1940 if (!_invariant.test(in->_idx)) { // bad guy | |
1941 all_inputs_invariant = false; | |
1942 break; | |
1943 } | |
1944 } | |
1945 if (all_inputs_invariant) { | |
1946 _invariant.set(n->_idx); // I am a invariant too | |
1947 } | |
1948 } else { // process next input | |
1949 _stack.set_index(idx + 1); | |
1950 Node* m = n->in(idx); | |
1951 if (m != NULL && !_visited.test_set(m->_idx)) { | |
1952 visit(n, m); | |
1953 } | |
1954 } | |
1955 } | |
1956 } | |
1957 | |
1958 // Helper function to set up _old_new map for clone_nodes. | |
1959 // If n is a known invariant, set up directly ("clone" of n == n). | |
1960 // Otherwise, push n onto the stack for real cloning. | |
1961 void clone_visit(Node* n) { | |
1962 assert(_invariant.test(n->_idx), "must be invariant"); | |
1963 if (_lpt->is_invariant(n)) { // known invariant | |
1964 _old_new.map(n->_idx, n); | |
1965 } else{ // to be cloned | |
1966 assert (!n->is_CFG(), "should not see CFG here"); | |
1967 _stack.push(n, n->in(0) == NULL ? 1 : 0); | |
1968 } | |
1969 } | |
1970 | |
1971 // Clone "n" and (possibly) all its inputs recursively | |
1972 void clone_nodes(Node* n, Node* ctrl) { | |
1973 clone_visit(n); | |
1974 while (_stack.is_nonempty()) { | |
1975 Node* n = _stack.node(); | |
1976 uint idx = _stack.index(); | |
1977 if (idx == n->req()) { // all inputs processed, clone n! | |
1978 _stack.pop(); | |
1979 // clone invariant node | |
1980 Node* n_cl = n->clone(); | |
1981 _old_new.map(n->_idx, n_cl); | |
1982 _phase->register_new_node(n_cl, ctrl); | |
1983 for (uint i = 0; i < n->req(); i++) { | |
1984 Node* in = n_cl->in(i); | |
1985 if (in == NULL) continue; | |
1986 n_cl->set_req(i, _old_new[in->_idx]); | |
1987 } | |
1988 } else { // process next input | |
1989 _stack.set_index(idx + 1); | |
1990 Node* m = n->in(idx); | |
1991 if (m != NULL && !_clone_visited.test_set(m->_idx)) { | |
1992 clone_visit(m); // visit the input | |
1993 } | |
1994 } | |
1995 } | |
1996 } | |
1997 | |
1998 public: | |
1999 Invariance(Arena* area, IdealLoopTree* lpt) : | |
2000 _lpt(lpt), _phase(lpt->_phase), | |
2001 _visited(area), _invariant(area), _stack(area, 10 /* guess */), | |
2002 _clone_visited(area), _old_new(area) | |
2003 {} | |
2004 | |
2005 // Map old to n for invariance computation and clone | |
2006 void map_ctrl(Node* old, Node* n) { | |
2007 assert(old->is_CFG() && n->is_CFG(), "must be"); | |
2008 _old_new.map(old->_idx, n); // "clone" of old is n | |
2009 _invariant.set(old->_idx); // old is invariant | |
2010 _clone_visited.set(old->_idx); | |
2011 } | |
2012 | |
2013 // Driver function to compute invariance | |
2014 bool is_invariant(Node* n) { | |
2015 if (!_visited.test_set(n->_idx)) | |
2016 compute_invariance(n); | |
2017 return (_invariant.test(n->_idx) != 0); | |
2018 } | |
2019 | |
2020 // Driver function to clone invariant | |
2021 Node* clone(Node* n, Node* ctrl) { | |
2022 assert(ctrl->is_CFG(), "must be"); | |
2023 assert(_invariant.test(n->_idx), "must be an invariant"); | |
2024 if (!_clone_visited.test(n->_idx)) | |
2025 clone_nodes(n, ctrl); | |
2026 return _old_new[n->_idx]; | |
2027 } | |
2028 }; | |
2029 | |
2030 //------------------------------is_range_check_if ----------------------------------- | |
2031 // Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format | |
2032 // Note: this function is particularly designed for loop predication. We require load_range | |
2033 // and offset to be loop invariant computed on the fly by "invar" | |
2034 bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const { | |
2035 if (!is_loop_exit(iff)) { | |
2036 return false; | |
2037 } | |
2038 if (!iff->in(1)->is_Bool()) { | |
2039 return false; | |
2040 } | |
2041 const BoolNode *bol = iff->in(1)->as_Bool(); | |
2042 if (bol->_test._test != BoolTest::lt) { | |
2043 return false; | |
2044 } | |
2045 if (!bol->in(1)->is_Cmp()) { | |
2046 return false; | |
2047 } | |
2048 const CmpNode *cmp = bol->in(1)->as_Cmp(); | |
2049 if (cmp->Opcode() != Op_CmpU ) { | |
2050 return false; | |
2051 } | |
2052 if (cmp->in(2)->Opcode() != Op_LoadRange) { | |
2053 return false; | |
2054 } | |
2055 LoadRangeNode* lr = (LoadRangeNode*)cmp->in(2); | |
2056 if (!invar.is_invariant(lr)) { // loadRange must be invariant | |
2057 return false; | |
2058 } | |
2059 Node *iv = _head->as_CountedLoop()->phi(); | |
2060 int scale = 0; | |
2061 Node *offset = NULL; | |
2062 if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) { | |
2063 return false; | |
2064 } | |
2065 if(offset && !invar.is_invariant(offset)) { // offset must be invariant | |
2066 return false; | |
2067 } | |
2068 return true; | |
2069 } | |
2070 | |
2071 //------------------------------rc_predicate----------------------------------- | |
2072 // Create a range check predicate | |
2073 // | |
2074 // for (i = init; i < limit; i += stride) { | |
2075 // a[scale*i+offset] | |
2076 // } | |
2077 // | |
2078 // Compute max(scale*i + offset) for init <= i < limit and build the predicate | |
2079 // as "max(scale*i + offset) u< a.length". | |
2080 // | |
2081 // There are two cases for max(scale*i + offset): | |
2082 // (1) stride*scale > 0 | |
2083 // max(scale*i + offset) = scale*(limit-stride) + offset | |
2084 // (2) stride*scale < 0 | |
2085 // max(scale*i + offset) = scale*init + offset | |
2086 BoolNode* PhaseIdealLoop::rc_predicate(Node* ctrl, | |
2087 int scale, Node* offset, | |
2088 Node* init, Node* limit, Node* stride, | |
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2089 Node* range, bool upper) { |
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2090 DEBUG_ONLY(ttyLocker ttyl); |
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2091 if (TraceLoopPredicate) tty->print("rc_predicate "); |
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2092 |
1172 | 2093 Node* max_idx_expr = init; |
2094 int stride_con = stride->get_int(); | |
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2095 if ((stride_con > 0) == (scale > 0) == upper) { |
1172 | 2096 max_idx_expr = new (C, 3) SubINode(limit, stride); |
2097 register_new_node(max_idx_expr, ctrl); | |
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2098 if (TraceLoopPredicate) tty->print("(limit - stride) "); |
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2099 } else { |
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2100 if (TraceLoopPredicate) tty->print("init "); |
1172 | 2101 } |
2102 | |
2103 if (scale != 1) { | |
2104 ConNode* con_scale = _igvn.intcon(scale); | |
2105 max_idx_expr = new (C, 3) MulINode(max_idx_expr, con_scale); | |
2106 register_new_node(max_idx_expr, ctrl); | |
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2107 if (TraceLoopPredicate) tty->print("* %d ", scale); |
1172 | 2108 } |
2109 | |
2110 if (offset && (!offset->is_Con() || offset->get_int() != 0)){ | |
2111 max_idx_expr = new (C, 3) AddINode(max_idx_expr, offset); | |
2112 register_new_node(max_idx_expr, ctrl); | |
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2113 if (TraceLoopPredicate) |
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2114 if (offset->is_Con()) tty->print("+ %d ", offset->get_int()); |
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2115 else tty->print("+ offset "); |
1172 | 2116 } |
2117 | |
2118 CmpUNode* cmp = new (C, 3) CmpUNode(max_idx_expr, range); | |
2119 register_new_node(cmp, ctrl); | |
2120 BoolNode* bol = new (C, 2) BoolNode(cmp, BoolTest::lt); | |
2121 register_new_node(bol, ctrl); | |
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2122 |
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2123 if (TraceLoopPredicate) tty->print_cr("<u range"); |
1172 | 2124 return bol; |
2125 } | |
2126 | |
2127 //------------------------------ loop_predication_impl-------------------------- | |
2128 // Insert loop predicates for null checks and range checks | |
2129 bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) { | |
2130 if (!UseLoopPredicate) return false; | |
2131 | |
1275 | 2132 if (!loop->_head->is_Loop()) { |
2133 // Could be a simple region when irreducible loops are present. | |
2134 return false; | |
2135 } | |
2136 | |
2137 CountedLoopNode *cl = NULL; | |
2138 if (loop->_head->is_CountedLoop()) { | |
2139 cl = loop->_head->as_CountedLoop(); | |
2140 // do nothing for iteration-splitted loops | |
2141 if (!cl->is_normal_loop()) return false; | |
2142 } | |
2143 | |
1172 | 2144 // Too many traps seen? |
2145 bool tmt = C->too_many_traps(C->method(), 0, Deoptimization::Reason_predicate); | |
2146 int tc = C->trap_count(Deoptimization::Reason_predicate); | |
2147 if (tmt || tc > 0) { | |
2148 if (TraceLoopPredicate) { | |
2149 tty->print_cr("too many predicate traps: %d", tc); | |
2150 C->method()->print(); // which method has too many predicate traps | |
2151 tty->print_cr(""); | |
2152 } | |
2153 return false; | |
2154 } | |
2155 | |
2156 LoopNode *lpn = loop->_head->as_Loop(); | |
2157 Node* entry = lpn->in(LoopNode::EntryControl); | |
2158 | |
2159 ProjNode *predicate_proj = find_predicate_insertion_point(entry); | |
2160 if (!predicate_proj){ | |
2161 #ifndef PRODUCT | |
2162 if (TraceLoopPredicate) { | |
2163 tty->print("missing predicate:"); | |
2164 loop->dump_head(); | |
2165 } | |
2166 #endif | |
2167 return false; | |
2168 } | |
2169 | |
2170 ConNode* zero = _igvn.intcon(0); | |
2171 set_ctrl(zero, C->root()); | |
2172 Node *cond_false = new (C, 2) Conv2BNode(zero); | |
2173 register_new_node(cond_false, C->root()); | |
2174 ConNode* one = _igvn.intcon(1); | |
2175 set_ctrl(one, C->root()); | |
2176 Node *cond_true = new (C, 2) Conv2BNode(one); | |
2177 register_new_node(cond_true, C->root()); | |
2178 | |
2179 ResourceArea *area = Thread::current()->resource_area(); | |
2180 Invariance invar(area, loop); | |
2181 | |
2182 // Create list of if-projs such that a newer proj dominates all older | |
2183 // projs in the list, and they all dominate loop->tail() | |
2184 Node_List if_proj_list(area); | |
2185 LoopNode *head = loop->_head->as_Loop(); | |
2186 Node *current_proj = loop->tail(); //start from tail | |
2187 while ( current_proj != head ) { | |
2188 if (loop == get_loop(current_proj) && // still in the loop ? | |
2189 current_proj->is_Proj() && // is a projection ? | |
2190 current_proj->in(0)->Opcode() == Op_If) { // is a if projection ? | |
2191 if_proj_list.push(current_proj); | |
2192 } | |
2193 current_proj = idom(current_proj); | |
2194 } | |
2195 | |
2196 bool hoisted = false; // true if at least one proj is promoted | |
2197 while (if_proj_list.size() > 0) { | |
2198 // Following are changed to nonnull when a predicate can be hoisted | |
2199 ProjNode* new_predicate_proj = NULL; | |
2200 | |
2201 ProjNode* proj = if_proj_list.pop()->as_Proj(); | |
2202 IfNode* iff = proj->in(0)->as_If(); | |
2203 | |
2204 if (!is_uncommon_trap_if_pattern(proj)) { | |
2205 if (loop->is_loop_exit(iff)) { | |
2206 // stop processing the remaining projs in the list because the execution of them | |
2207 // depends on the condition of "iff" (iff->in(1)). | |
2208 break; | |
2209 } else { | |
2210 // Both arms are inside the loop. There are two cases: | |
2211 // (1) there is one backward branch. In this case, any remaining proj | |
2212 // in the if_proj list post-dominates "iff". So, the condition of "iff" | |
2213 // does not determine the execution the remining projs directly, and we | |
2214 // can safely continue. | |
2215 // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj" | |
2216 // does not dominate loop->tail(), so it can not be in the if_proj list. | |
2217 continue; | |
2218 } | |
2219 } | |
2220 | |
2221 Node* test = iff->in(1); | |
2222 if (!test->is_Bool()){ //Conv2B, ... | |
2223 continue; | |
2224 } | |
2225 BoolNode* bol = test->as_Bool(); | |
2226 if (invar.is_invariant(bol)) { | |
2227 // Invariant test | |
2228 new_predicate_proj = create_new_if_for_predicate(predicate_proj); | |
2229 Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0); | |
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2230 BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool(); |
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2231 |
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2232 // Negate test if necessary |
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2233 bool negated = false; |
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2234 if (proj->_con != predicate_proj->_con) { |
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|
2235 new_predicate_bol = new (C, 2) BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate()); |
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|
2236 register_new_node(new_predicate_bol, ctrl); |
c047da02984c
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|
2237 negated = true; |
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|
2238 } |
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|
2239 IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If(); |
c047da02984c
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|
2240 _igvn.hash_delete(new_predicate_iff); |
c047da02984c
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|
2241 new_predicate_iff->set_req(1, new_predicate_bol); |
c047da02984c
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|
2242 if (TraceLoopPredicate) tty->print_cr("invariant if%s: %d", negated ? " negated" : "", new_predicate_iff->_idx); |
c047da02984c
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|
2243 |
1172 | 2244 } else if (cl != NULL && loop->is_range_check_if(iff, this, invar)) { |
1303
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|
2245 assert(proj->_con == predicate_proj->_con, "must match"); |
c047da02984c
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|
2246 |
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|
2247 // Range check for counted loops |
1172 | 2248 const Node* cmp = bol->in(1)->as_Cmp(); |
2249 Node* idx = cmp->in(1); | |
2250 assert(!invar.is_invariant(idx), "index is variant"); | |
2251 assert(cmp->in(2)->Opcode() == Op_LoadRange, "must be"); | |
1303
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|
2252 Node* ld_rng = cmp->in(2); // LoadRangeNode |
1172 | 2253 assert(invar.is_invariant(ld_rng), "load range must be invariant"); |
2254 int scale = 1; | |
2255 Node* offset = zero; | |
2256 bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset); | |
2257 assert(ok, "must be index expression"); | |
1303
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|
2258 |
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|
2259 Node* init = cl->init_trip(); |
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|
2260 Node* limit = cl->limit(); |
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|
2261 Node* stride = cl->stride(); |
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|
2262 |
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|
2263 // Build if's for the upper and lower bound tests. The |
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|
2264 // lower_bound test will dominate the upper bound test and all |
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|
2265 // cloned or created nodes will use the lower bound test as |
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|
2266 // their declared control. |
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|
2267 ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj); |
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|
2268 ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj); |
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2269 assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate"); |
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2270 Node *ctrl = lower_bound_proj->in(0)->as_If()->in(0); |
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|
2271 |
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|
2272 // Perform cloning to keep Invariance state correct since the |
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|
2273 // late schedule will place invariant things in the loop. |
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|
2274 ld_rng = invar.clone(ld_rng, ctrl); |
1172 | 2275 if (offset && offset != zero) { |
2276 assert(invar.is_invariant(offset), "offset must be loop invariant"); | |
2277 offset = invar.clone(offset, ctrl); | |
2278 } | |
1303
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|
2279 |
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|
2280 // Test the lower bound |
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2281 Node* lower_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, ld_rng, false); |
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2282 IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If(); |
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|
2283 _igvn.hash_delete(lower_bound_iff); |
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|
2284 lower_bound_iff->set_req(1, lower_bound_bol); |
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|
2285 if (TraceLoopPredicate) tty->print_cr("lower bound check if: %d", lower_bound_iff->_idx); |
1172 | 2286 |
1303
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|
2287 // Test the upper bound |
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2288 Node* upper_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, ld_rng, true); |
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|
2289 IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If(); |
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|
2290 _igvn.hash_delete(upper_bound_iff); |
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|
2291 upper_bound_iff->set_req(1, upper_bound_bol); |
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|
2292 if (TraceLoopPredicate) tty->print_cr("upper bound check if: %d", lower_bound_iff->_idx); |
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|
2293 |
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|
2294 // Fall through into rest of the clean up code which will move |
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|
2295 // any dependent nodes onto the upper bound test. |
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|
2296 new_predicate_proj = upper_bound_proj; |
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|
2297 } else { |
1172 | 2298 // The other proj of the "iff" is a uncommon trap projection, and we can assume |
2299 // the other proj will not be executed ("executed" means uct raised). | |
2300 continue; | |
1303
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|
2301 } |
1172 | 2302 |
1303
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|
2303 // Success - attach condition (new_predicate_bol) to predicate if |
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|
2304 invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate |
1172 | 2305 |
1303
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|
2306 // Eliminate the old if in the loop body |
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|
2307 _igvn.hash_delete(iff); |
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|
2308 iff->set_req(1, proj->is_IfFalse() ? cond_false : cond_true); |
1172 | 2309 |
1303
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|
2310 Node* ctrl = new_predicate_proj; // new control |
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|
2311 ProjNode* dp = proj; // old control |
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|
2312 assert(get_loop(dp) == loop, "guaranteed at the time of collecting proj"); |
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|
2313 // Find nodes (depends only on the test) off the surviving projection; |
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|
2314 // move them outside the loop with the control of proj_clone |
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2315 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) { |
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|
2316 Node* cd = dp->fast_out(i); // Control-dependent node |
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|
2317 if (cd->depends_only_on_test()) { |
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|
2318 assert(cd->in(0) == dp, ""); |
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|
2319 _igvn.hash_delete(cd); |
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|
2320 cd->set_req(0, ctrl); // ctrl, not NULL |
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|
2321 set_early_ctrl(cd); |
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|
2322 _igvn._worklist.push(cd); |
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|
2323 IdealLoopTree *new_loop = get_loop(get_ctrl(cd)); |
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|
2324 if (new_loop != loop) { |
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|
2325 if (!loop->_child) loop->_body.yank(cd); |
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|
2326 if (!new_loop->_child ) new_loop->_body.push(cd); |
1172 | 2327 } |
1303
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|
2328 --i; |
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|
2329 --imax; |
1172 | 2330 } |
1303
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|
2331 } |
1172 | 2332 |
1303
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|
2333 hoisted = true; |
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|
2334 C->set_major_progress(); |
1172 | 2335 } // end while |
2336 | |
2337 #ifndef PRODUCT | |
1303
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|
2338 // report that the loop predication has been actually performed |
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2339 // for this loop |
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2340 if (TraceLoopPredicate && hoisted) { |
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|
2341 tty->print("Loop Predication Performed:"); |
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|
2342 loop->dump_head(); |
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|
2343 } |
1172 | 2344 #endif |
2345 | |
2346 return hoisted; | |
2347 } | |
2348 | |
2349 //------------------------------loop_predication-------------------------------- | |
2350 // driver routine for loop predication optimization | |
2351 bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) { | |
2352 bool hoisted = false; | |
2353 // Recursively promote predicates | |
2354 if ( _child ) { | |
2355 hoisted = _child->loop_predication( phase); | |
2356 } | |
2357 | |
2358 // self | |
2359 if (!_irreducible && !tail()->is_top()) { | |
2360 hoisted |= phase->loop_predication_impl(this); | |
2361 } | |
2362 | |
2363 if ( _next ) { //sibling | |
2364 hoisted |= _next->loop_predication( phase); | |
2365 } | |
2366 | |
2367 return hoisted; | |
2368 } |