Mercurial > hg > graal-compiler
annotate src/share/vm/opto/loopTransform.cpp @ 2142:8012aa3ccede
4926272: methodOopDesc::method_from_bcp is unsafe
Reviewed-by: coleenp, jrose, kvn, dcubed
author | never |
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date | Thu, 13 Jan 2011 22:15:41 -0800 |
parents | f95d63e2154a |
children | 9dc311b8473e |
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 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "compiler/compileLog.hpp" | |
27 #include "memory/allocation.inline.hpp" | |
28 #include "opto/addnode.hpp" | |
29 #include "opto/callnode.hpp" | |
30 #include "opto/connode.hpp" | |
31 #include "opto/divnode.hpp" | |
32 #include "opto/loopnode.hpp" | |
33 #include "opto/mulnode.hpp" | |
34 #include "opto/rootnode.hpp" | |
35 #include "opto/runtime.hpp" | |
36 #include "opto/subnode.hpp" | |
0 | 37 |
38 //------------------------------is_loop_exit----------------------------------- | |
39 // Given an IfNode, return the loop-exiting projection or NULL if both | |
40 // arms remain in the loop. | |
41 Node *IdealLoopTree::is_loop_exit(Node *iff) const { | |
42 if( iff->outcnt() != 2 ) return NULL; // Ignore partially dead tests | |
43 PhaseIdealLoop *phase = _phase; | |
44 // Test is an IfNode, has 2 projections. If BOTH are in the loop | |
45 // we need loop unswitching instead of peeling. | |
46 if( !is_member(phase->get_loop( iff->raw_out(0) )) ) | |
47 return iff->raw_out(0); | |
48 if( !is_member(phase->get_loop( iff->raw_out(1) )) ) | |
49 return iff->raw_out(1); | |
50 return NULL; | |
51 } | |
52 | |
53 | |
54 //============================================================================= | |
55 | |
56 | |
57 //------------------------------record_for_igvn---------------------------- | |
58 // Put loop body on igvn work list | |
59 void IdealLoopTree::record_for_igvn() { | |
60 for( uint i = 0; i < _body.size(); i++ ) { | |
61 Node *n = _body.at(i); | |
62 _phase->_igvn._worklist.push(n); | |
63 } | |
64 } | |
65 | |
66 //------------------------------compute_profile_trip_cnt---------------------------- | |
67 // Compute loop trip count from profile data as | |
68 // (backedge_count + loop_exit_count) / loop_exit_count | |
69 void IdealLoopTree::compute_profile_trip_cnt( PhaseIdealLoop *phase ) { | |
70 if (!_head->is_CountedLoop()) { | |
71 return; | |
72 } | |
73 CountedLoopNode* head = _head->as_CountedLoop(); | |
74 if (head->profile_trip_cnt() != COUNT_UNKNOWN) { | |
75 return; // Already computed | |
76 } | |
77 float trip_cnt = (float)max_jint; // default is big | |
78 | |
79 Node* back = head->in(LoopNode::LoopBackControl); | |
80 while (back != head) { | |
81 if ((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) && | |
82 back->in(0) && | |
83 back->in(0)->is_If() && | |
84 back->in(0)->as_If()->_fcnt != COUNT_UNKNOWN && | |
85 back->in(0)->as_If()->_prob != PROB_UNKNOWN) { | |
86 break; | |
87 } | |
88 back = phase->idom(back); | |
89 } | |
90 if (back != head) { | |
91 assert((back->Opcode() == Op_IfTrue || back->Opcode() == Op_IfFalse) && | |
92 back->in(0), "if-projection exists"); | |
93 IfNode* back_if = back->in(0)->as_If(); | |
94 float loop_back_cnt = back_if->_fcnt * back_if->_prob; | |
95 | |
96 // Now compute a loop exit count | |
97 float loop_exit_cnt = 0.0f; | |
98 for( uint i = 0; i < _body.size(); i++ ) { | |
99 Node *n = _body[i]; | |
100 if( n->is_If() ) { | |
101 IfNode *iff = n->as_If(); | |
102 if( iff->_fcnt != COUNT_UNKNOWN && iff->_prob != PROB_UNKNOWN ) { | |
103 Node *exit = is_loop_exit(iff); | |
104 if( exit ) { | |
105 float exit_prob = iff->_prob; | |
106 if (exit->Opcode() == Op_IfFalse) exit_prob = 1.0 - exit_prob; | |
107 if (exit_prob > PROB_MIN) { | |
108 float exit_cnt = iff->_fcnt * exit_prob; | |
109 loop_exit_cnt += exit_cnt; | |
110 } | |
111 } | |
112 } | |
113 } | |
114 } | |
115 if (loop_exit_cnt > 0.0f) { | |
116 trip_cnt = (loop_back_cnt + loop_exit_cnt) / loop_exit_cnt; | |
117 } else { | |
118 // No exit count so use | |
119 trip_cnt = loop_back_cnt; | |
120 } | |
121 } | |
122 #ifndef PRODUCT | |
123 if (TraceProfileTripCount) { | |
124 tty->print_cr("compute_profile_trip_cnt lp: %d cnt: %f\n", head->_idx, trip_cnt); | |
125 } | |
126 #endif | |
127 head->set_profile_trip_cnt(trip_cnt); | |
128 } | |
129 | |
130 //---------------------is_invariant_addition----------------------------- | |
131 // Return nonzero index of invariant operand for an Add or Sub | |
605 | 132 // of (nonconstant) invariant and variant values. Helper for reassociate_invariants. |
0 | 133 int IdealLoopTree::is_invariant_addition(Node* n, PhaseIdealLoop *phase) { |
134 int op = n->Opcode(); | |
135 if (op == Op_AddI || op == Op_SubI) { | |
136 bool in1_invar = this->is_invariant(n->in(1)); | |
137 bool in2_invar = this->is_invariant(n->in(2)); | |
138 if (in1_invar && !in2_invar) return 1; | |
139 if (!in1_invar && in2_invar) return 2; | |
140 } | |
141 return 0; | |
142 } | |
143 | |
144 //---------------------reassociate_add_sub----------------------------- | |
145 // Reassociate invariant add and subtract expressions: | |
146 // | |
147 // inv1 + (x + inv2) => ( inv1 + inv2) + x | |
148 // (x + inv2) + inv1 => ( inv1 + inv2) + x | |
149 // inv1 + (x - inv2) => ( inv1 - inv2) + x | |
150 // inv1 - (inv2 - x) => ( inv1 - inv2) + x | |
151 // (x + inv2) - inv1 => (-inv1 + inv2) + x | |
152 // (x - inv2) + inv1 => ( inv1 - inv2) + x | |
153 // (x - inv2) - inv1 => (-inv1 - inv2) + x | |
154 // inv1 + (inv2 - x) => ( inv1 + inv2) - x | |
155 // inv1 - (x - inv2) => ( inv1 + inv2) - x | |
156 // (inv2 - x) + inv1 => ( inv1 + inv2) - x | |
157 // (inv2 - x) - inv1 => (-inv1 + inv2) - x | |
158 // inv1 - (x + inv2) => ( inv1 - inv2) - x | |
159 // | |
160 Node* IdealLoopTree::reassociate_add_sub(Node* n1, PhaseIdealLoop *phase) { | |
161 if (!n1->is_Add() && !n1->is_Sub() || n1->outcnt() == 0) return NULL; | |
162 if (is_invariant(n1)) return NULL; | |
163 int inv1_idx = is_invariant_addition(n1, phase); | |
164 if (!inv1_idx) return NULL; | |
165 // Don't mess with add of constant (igvn moves them to expression tree root.) | |
166 if (n1->is_Add() && n1->in(2)->is_Con()) return NULL; | |
167 Node* inv1 = n1->in(inv1_idx); | |
168 Node* n2 = n1->in(3 - inv1_idx); | |
169 int inv2_idx = is_invariant_addition(n2, phase); | |
170 if (!inv2_idx) return NULL; | |
171 Node* x = n2->in(3 - inv2_idx); | |
172 Node* inv2 = n2->in(inv2_idx); | |
173 | |
174 bool neg_x = n2->is_Sub() && inv2_idx == 1; | |
175 bool neg_inv2 = n2->is_Sub() && inv2_idx == 2; | |
176 bool neg_inv1 = n1->is_Sub() && inv1_idx == 2; | |
177 if (n1->is_Sub() && inv1_idx == 1) { | |
178 neg_x = !neg_x; | |
179 neg_inv2 = !neg_inv2; | |
180 } | |
181 Node* inv1_c = phase->get_ctrl(inv1); | |
182 Node* inv2_c = phase->get_ctrl(inv2); | |
183 Node* n_inv1; | |
184 if (neg_inv1) { | |
185 Node *zero = phase->_igvn.intcon(0); | |
186 phase->set_ctrl(zero, phase->C->root()); | |
187 n_inv1 = new (phase->C, 3) SubINode(zero, inv1); | |
188 phase->register_new_node(n_inv1, inv1_c); | |
189 } else { | |
190 n_inv1 = inv1; | |
191 } | |
192 Node* inv; | |
193 if (neg_inv2) { | |
194 inv = new (phase->C, 3) SubINode(n_inv1, inv2); | |
195 } else { | |
196 inv = new (phase->C, 3) AddINode(n_inv1, inv2); | |
197 } | |
198 phase->register_new_node(inv, phase->get_early_ctrl(inv)); | |
199 | |
200 Node* addx; | |
201 if (neg_x) { | |
202 addx = new (phase->C, 3) SubINode(inv, x); | |
203 } else { | |
204 addx = new (phase->C, 3) AddINode(x, inv); | |
205 } | |
206 phase->register_new_node(addx, phase->get_ctrl(x)); | |
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207 phase->_igvn.replace_node(n1, addx); |
0 | 208 return addx; |
209 } | |
210 | |
211 //---------------------reassociate_invariants----------------------------- | |
212 // Reassociate invariant expressions: | |
213 void IdealLoopTree::reassociate_invariants(PhaseIdealLoop *phase) { | |
214 for (int i = _body.size() - 1; i >= 0; i--) { | |
215 Node *n = _body.at(i); | |
216 for (int j = 0; j < 5; j++) { | |
217 Node* nn = reassociate_add_sub(n, phase); | |
218 if (nn == NULL) break; | |
219 n = nn; // again | |
220 }; | |
221 } | |
222 } | |
223 | |
224 //------------------------------policy_peeling--------------------------------- | |
225 // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can | |
226 // make some loop-invariant test (usually a null-check) happen before the loop. | |
227 bool IdealLoopTree::policy_peeling( PhaseIdealLoop *phase ) const { | |
228 Node *test = ((IdealLoopTree*)this)->tail(); | |
229 int body_size = ((IdealLoopTree*)this)->_body.size(); | |
230 int uniq = phase->C->unique(); | |
231 // Peeling does loop cloning which can result in O(N^2) node construction | |
232 if( body_size > 255 /* Prevent overflow for large body_size */ | |
233 || (body_size * body_size + uniq > MaxNodeLimit) ) { | |
234 return false; // too large to safely clone | |
235 } | |
236 while( test != _head ) { // Scan till run off top of loop | |
237 if( test->is_If() ) { // Test? | |
238 Node *ctrl = phase->get_ctrl(test->in(1)); | |
239 if (ctrl->is_top()) | |
240 return false; // Found dead test on live IF? No peeling! | |
241 // Standard IF only has one input value to check for loop invariance | |
242 assert( test->Opcode() == Op_If || test->Opcode() == Op_CountedLoopEnd, "Check this code when new subtype is added"); | |
243 // Condition is not a member of this loop? | |
244 if( !is_member(phase->get_loop(ctrl)) && | |
245 is_loop_exit(test) ) | |
246 return true; // Found reason to peel! | |
247 } | |
248 // Walk up dominators to loop _head looking for test which is | |
249 // executed on every path thru loop. | |
250 test = phase->idom(test); | |
251 } | |
252 return false; | |
253 } | |
254 | |
255 //------------------------------peeled_dom_test_elim--------------------------- | |
256 // If we got the effect of peeling, either by actually peeling or by making | |
257 // a pre-loop which must execute at least once, we can remove all | |
258 // loop-invariant dominated tests in the main body. | |
259 void PhaseIdealLoop::peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new ) { | |
260 bool progress = true; | |
261 while( progress ) { | |
262 progress = false; // Reset for next iteration | |
263 Node *prev = loop->_head->in(LoopNode::LoopBackControl);//loop->tail(); | |
264 Node *test = prev->in(0); | |
265 while( test != loop->_head ) { // Scan till run off top of loop | |
266 | |
267 int p_op = prev->Opcode(); | |
268 if( (p_op == Op_IfFalse || p_op == Op_IfTrue) && | |
269 test->is_If() && // Test? | |
270 !test->in(1)->is_Con() && // And not already obvious? | |
271 // Condition is not a member of this loop? | |
272 !loop->is_member(get_loop(get_ctrl(test->in(1))))){ | |
273 // Walk loop body looking for instances of this test | |
274 for( uint i = 0; i < loop->_body.size(); i++ ) { | |
275 Node *n = loop->_body.at(i); | |
276 if( n->is_If() && n->in(1) == test->in(1) /*&& n != loop->tail()->in(0)*/ ) { | |
277 // IfNode was dominated by version in peeled loop body | |
278 progress = true; | |
279 dominated_by( old_new[prev->_idx], n ); | |
280 } | |
281 } | |
282 } | |
283 prev = test; | |
284 test = idom(test); | |
285 } // End of scan tests in loop | |
286 | |
287 } // End of while( progress ) | |
288 } | |
289 | |
290 //------------------------------do_peeling------------------------------------- | |
291 // Peel the first iteration of the given loop. | |
292 // Step 1: Clone the loop body. The clone becomes the peeled iteration. | |
293 // The pre-loop illegally has 2 control users (old & new loops). | |
294 // Step 2: Make the old-loop fall-in edges point to the peeled iteration. | |
295 // Do this by making the old-loop fall-in edges act as if they came | |
296 // around the loopback from the prior iteration (follow the old-loop | |
297 // backedges) and then map to the new peeled iteration. This leaves | |
298 // the pre-loop with only 1 user (the new peeled iteration), but the | |
299 // peeled-loop backedge has 2 users. | |
300 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the | |
301 // extra backedge user. | |
302 void PhaseIdealLoop::do_peeling( IdealLoopTree *loop, Node_List &old_new ) { | |
303 | |
304 C->set_major_progress(); | |
305 // Peeling a 'main' loop in a pre/main/post situation obfuscates the | |
306 // 'pre' loop from the main and the 'pre' can no longer have it's | |
307 // iterations adjusted. Therefore, we need to declare this loop as | |
308 // no longer a 'main' loop; it will need new pre and post loops before | |
309 // we can do further RCE. | |
310 Node *h = loop->_head; | |
311 if( h->is_CountedLoop() ) { | |
312 CountedLoopNode *cl = h->as_CountedLoop(); | |
313 assert(cl->trip_count() > 0, "peeling a fully unrolled loop"); | |
314 cl->set_trip_count(cl->trip_count() - 1); | |
315 if( cl->is_main_loop() ) { | |
316 cl->set_normal_loop(); | |
317 #ifndef PRODUCT | |
318 if( PrintOpto && VerifyLoopOptimizations ) { | |
319 tty->print("Peeling a 'main' loop; resetting to 'normal' "); | |
320 loop->dump_head(); | |
321 } | |
322 #endif | |
323 } | |
324 } | |
325 | |
326 // Step 1: Clone the loop body. The clone becomes the peeled iteration. | |
327 // The pre-loop illegally has 2 control users (old & new loops). | |
328 clone_loop( loop, old_new, dom_depth(loop->_head) ); | |
329 | |
330 | |
331 // Step 2: Make the old-loop fall-in edges point to the peeled iteration. | |
332 // Do this by making the old-loop fall-in edges act as if they came | |
333 // around the loopback from the prior iteration (follow the old-loop | |
334 // backedges) and then map to the new peeled iteration. This leaves | |
335 // the pre-loop with only 1 user (the new peeled iteration), but the | |
336 // peeled-loop backedge has 2 users. | |
337 for (DUIterator_Fast jmax, j = loop->_head->fast_outs(jmax); j < jmax; j++) { | |
338 Node* old = loop->_head->fast_out(j); | |
339 if( old->in(0) == loop->_head && old->req() == 3 && | |
340 (old->is_Loop() || old->is_Phi()) ) { | |
341 Node *new_exit_value = old_new[old->in(LoopNode::LoopBackControl)->_idx]; | |
342 if( !new_exit_value ) // Backedge value is ALSO loop invariant? | |
343 // Then loop body backedge value remains the same. | |
344 new_exit_value = old->in(LoopNode::LoopBackControl); | |
345 _igvn.hash_delete(old); | |
346 old->set_req(LoopNode::EntryControl, new_exit_value); | |
347 } | |
348 } | |
349 | |
350 | |
351 // Step 3: Cut the backedge on the clone (so its not a loop) and remove the | |
352 // extra backedge user. | |
353 Node *nnn = old_new[loop->_head->_idx]; | |
354 _igvn.hash_delete(nnn); | |
355 nnn->set_req(LoopNode::LoopBackControl, C->top()); | |
356 for (DUIterator_Fast j2max, j2 = nnn->fast_outs(j2max); j2 < j2max; j2++) { | |
357 Node* use = nnn->fast_out(j2); | |
358 if( use->in(0) == nnn && use->req() == 3 && use->is_Phi() ) { | |
359 _igvn.hash_delete(use); | |
360 use->set_req(LoopNode::LoopBackControl, C->top()); | |
361 } | |
362 } | |
363 | |
364 | |
365 // Step 4: Correct dom-depth info. Set to loop-head depth. | |
366 int dd = dom_depth(loop->_head); | |
367 set_idom(loop->_head, loop->_head->in(1), dd); | |
368 for (uint j3 = 0; j3 < loop->_body.size(); j3++) { | |
369 Node *old = loop->_body.at(j3); | |
370 Node *nnn = old_new[old->_idx]; | |
371 if (!has_ctrl(nnn)) | |
372 set_idom(nnn, idom(nnn), dd-1); | |
373 // While we're at it, remove any SafePoints from the peeled code | |
374 if( old->Opcode() == Op_SafePoint ) { | |
375 Node *nnn = old_new[old->_idx]; | |
376 lazy_replace(nnn,nnn->in(TypeFunc::Control)); | |
377 } | |
378 } | |
379 | |
380 // Now force out all loop-invariant dominating tests. The optimizer | |
381 // finds some, but we _know_ they are all useless. | |
382 peeled_dom_test_elim(loop,old_new); | |
383 | |
384 loop->record_for_igvn(); | |
385 } | |
386 | |
387 //------------------------------policy_maximally_unroll------------------------ | |
388 // Return exact loop trip count, or 0 if not maximally unrolling | |
389 bool IdealLoopTree::policy_maximally_unroll( PhaseIdealLoop *phase ) const { | |
390 CountedLoopNode *cl = _head->as_CountedLoop(); | |
391 assert( cl->is_normal_loop(), "" ); | |
392 | |
393 Node *init_n = cl->init_trip(); | |
394 Node *limit_n = cl->limit(); | |
395 | |
396 // Non-constant bounds | |
397 if( init_n == NULL || !init_n->is_Con() || | |
398 limit_n == NULL || !limit_n->is_Con() || | |
399 // protect against stride not being a constant | |
400 !cl->stride_is_con() ) { | |
401 return false; | |
402 } | |
403 int init = init_n->get_int(); | |
404 int limit = limit_n->get_int(); | |
405 int span = limit - init; | |
406 int stride = cl->stride_con(); | |
407 | |
408 if (init >= limit || stride > span) { | |
409 // return a false (no maximally unroll) and the regular unroll/peel | |
410 // route will make a small mess which CCP will fold away. | |
411 return false; | |
412 } | |
413 uint trip_count = span/stride; // trip_count can be greater than 2 Gig. | |
414 assert( (int)trip_count*stride == span, "must divide evenly" ); | |
415 | |
416 // Real policy: if we maximally unroll, does it get too big? | |
417 // Allow the unrolled mess to get larger than standard loop | |
418 // size. After all, it will no longer be a loop. | |
419 uint body_size = _body.size(); | |
420 uint unroll_limit = (uint)LoopUnrollLimit * 4; | |
421 assert( (intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits"); | |
422 cl->set_trip_count(trip_count); | |
423 if( trip_count <= unroll_limit && body_size <= unroll_limit ) { | |
424 uint new_body_size = body_size * trip_count; | |
425 if (new_body_size <= unroll_limit && | |
426 body_size == new_body_size / trip_count && | |
427 // Unrolling can result in a large amount of node construction | |
428 new_body_size < MaxNodeLimit - phase->C->unique()) { | |
429 return true; // maximally unroll | |
430 } | |
431 } | |
432 | |
433 return false; // Do not maximally unroll | |
434 } | |
435 | |
436 | |
437 //------------------------------policy_unroll---------------------------------- | |
438 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if | |
439 // the loop is a CountedLoop and the body is small enough. | |
440 bool IdealLoopTree::policy_unroll( PhaseIdealLoop *phase ) const { | |
441 | |
442 CountedLoopNode *cl = _head->as_CountedLoop(); | |
443 assert( cl->is_normal_loop() || cl->is_main_loop(), "" ); | |
444 | |
445 // protect against stride not being a constant | |
446 if( !cl->stride_is_con() ) return false; | |
447 | |
448 // protect against over-unrolling | |
449 if( cl->trip_count() <= 1 ) return false; | |
450 | |
451 int future_unroll_ct = cl->unrolled_count() * 2; | |
452 | |
453 // Don't unroll if the next round of unrolling would push us | |
454 // over the expected trip count of the loop. One is subtracted | |
455 // from the expected trip count because the pre-loop normally | |
456 // executes 1 iteration. | |
457 if (UnrollLimitForProfileCheck > 0 && | |
458 cl->profile_trip_cnt() != COUNT_UNKNOWN && | |
459 future_unroll_ct > UnrollLimitForProfileCheck && | |
460 (float)future_unroll_ct > cl->profile_trip_cnt() - 1.0) { | |
461 return false; | |
462 } | |
463 | |
464 // When unroll count is greater than LoopUnrollMin, don't unroll if: | |
465 // the residual iterations are more than 10% of the trip count | |
466 // and rounds of "unroll,optimize" are not making significant progress | |
467 // Progress defined as current size less than 20% larger than previous size. | |
468 if (UseSuperWord && cl->node_count_before_unroll() > 0 && | |
469 future_unroll_ct > LoopUnrollMin && | |
470 (future_unroll_ct - 1) * 10.0 > cl->profile_trip_cnt() && | |
471 1.2 * cl->node_count_before_unroll() < (double)_body.size()) { | |
472 return false; | |
473 } | |
474 | |
475 Node *init_n = cl->init_trip(); | |
476 Node *limit_n = cl->limit(); | |
477 // Non-constant bounds. | |
478 // Protect against over-unrolling when init or/and limit are not constant | |
479 // (so that trip_count's init value is maxint) but iv range is known. | |
480 if( init_n == NULL || !init_n->is_Con() || | |
481 limit_n == NULL || !limit_n->is_Con() ) { | |
482 Node* phi = cl->phi(); | |
483 if( phi != NULL ) { | |
484 assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi."); | |
485 const TypeInt* iv_type = phase->_igvn.type(phi)->is_int(); | |
486 int next_stride = cl->stride_con() * 2; // stride after this unroll | |
487 if( next_stride > 0 ) { | |
488 if( iv_type->_lo + next_stride <= iv_type->_lo || // overflow | |
489 iv_type->_lo + next_stride > iv_type->_hi ) { | |
490 return false; // over-unrolling | |
491 } | |
492 } else if( next_stride < 0 ) { | |
493 if( iv_type->_hi + next_stride >= iv_type->_hi || // overflow | |
494 iv_type->_hi + next_stride < iv_type->_lo ) { | |
495 return false; // over-unrolling | |
496 } | |
497 } | |
498 } | |
499 } | |
500 | |
501 // Adjust body_size to determine if we unroll or not | |
502 uint body_size = _body.size(); | |
503 // Key test to unroll CaffeineMark's Logic test | |
504 int xors_in_loop = 0; | |
505 // Also count ModL, DivL and MulL which expand mightly | |
506 for( uint k = 0; k < _body.size(); k++ ) { | |
507 switch( _body.at(k)->Opcode() ) { | |
508 case Op_XorI: xors_in_loop++; break; // CaffeineMark's Logic test | |
509 case Op_ModL: body_size += 30; break; | |
510 case Op_DivL: body_size += 30; break; | |
511 case Op_MulL: body_size += 10; break; | |
512 } | |
513 } | |
514 | |
515 // Check for being too big | |
516 if( body_size > (uint)LoopUnrollLimit ) { | |
517 if( xors_in_loop >= 4 && body_size < (uint)LoopUnrollLimit*4) return true; | |
518 // Normal case: loop too big | |
519 return false; | |
520 } | |
521 | |
522 // Check for stride being a small enough constant | |
523 if( abs(cl->stride_con()) > (1<<3) ) return false; | |
524 | |
525 // Unroll once! (Each trip will soon do double iterations) | |
526 return true; | |
527 } | |
528 | |
529 //------------------------------policy_align----------------------------------- | |
530 // Return TRUE or FALSE if the loop should be cache-line aligned. Gather the | |
531 // expression that does the alignment. Note that only one array base can be | |
605 | 532 // aligned in a loop (unless the VM guarantees mutual alignment). Note that |
0 | 533 // if we vectorize short memory ops into longer memory ops, we may want to |
534 // increase alignment. | |
535 bool IdealLoopTree::policy_align( PhaseIdealLoop *phase ) const { | |
536 return false; | |
537 } | |
538 | |
539 //------------------------------policy_range_check----------------------------- | |
540 // Return TRUE or FALSE if the loop should be range-check-eliminated. | |
541 // Actually we do iteration-splitting, a more powerful form of RCE. | |
542 bool IdealLoopTree::policy_range_check( PhaseIdealLoop *phase ) const { | |
543 if( !RangeCheckElimination ) return false; | |
544 | |
545 CountedLoopNode *cl = _head->as_CountedLoop(); | |
546 // If we unrolled with no intention of doing RCE and we later | |
547 // changed our minds, we got no pre-loop. Either we need to | |
548 // make a new pre-loop, or we gotta disallow RCE. | |
549 if( cl->is_main_no_pre_loop() ) return false; // Disallowed for now. | |
550 Node *trip_counter = cl->phi(); | |
551 | |
552 // Check loop body for tests of trip-counter plus loop-invariant vs | |
553 // loop-invariant. | |
554 for( uint i = 0; i < _body.size(); i++ ) { | |
555 Node *iff = _body[i]; | |
556 if( iff->Opcode() == Op_If ) { // Test? | |
557 | |
558 // Comparing trip+off vs limit | |
559 Node *bol = iff->in(1); | |
560 if( bol->req() != 2 ) continue; // dead constant test | |
1172 | 561 if (!bol->is_Bool()) { |
562 assert(UseLoopPredicate && bol->Opcode() == Op_Conv2B, "predicate check only"); | |
563 continue; | |
564 } | |
0 | 565 Node *cmp = bol->in(1); |
566 | |
567 Node *rc_exp = cmp->in(1); | |
568 Node *limit = cmp->in(2); | |
569 | |
570 Node *limit_c = phase->get_ctrl(limit); | |
571 if( limit_c == phase->C->top() ) | |
572 return false; // Found dead test on live IF? No RCE! | |
573 if( is_member(phase->get_loop(limit_c) ) ) { | |
574 // Compare might have operands swapped; commute them | |
575 rc_exp = cmp->in(2); | |
576 limit = cmp->in(1); | |
577 limit_c = phase->get_ctrl(limit); | |
578 if( is_member(phase->get_loop(limit_c) ) ) | |
579 continue; // Both inputs are loop varying; cannot RCE | |
580 } | |
581 | |
582 if (!phase->is_scaled_iv_plus_offset(rc_exp, trip_counter, NULL, NULL)) { | |
583 continue; | |
584 } | |
585 // Yeah! Found a test like 'trip+off vs limit' | |
586 // Test is an IfNode, has 2 projections. If BOTH are in the loop | |
587 // we need loop unswitching instead of iteration splitting. | |
588 if( is_loop_exit(iff) ) | |
589 return true; // Found reason to split iterations | |
590 } // End of is IF | |
591 } | |
592 | |
593 return false; | |
594 } | |
595 | |
596 //------------------------------policy_peel_only------------------------------- | |
597 // Return TRUE or FALSE if the loop should NEVER be RCE'd or aligned. Useful | |
598 // for unrolling loops with NO array accesses. | |
599 bool IdealLoopTree::policy_peel_only( PhaseIdealLoop *phase ) const { | |
600 | |
601 for( uint i = 0; i < _body.size(); i++ ) | |
602 if( _body[i]->is_Mem() ) | |
603 return false; | |
604 | |
605 // No memory accesses at all! | |
606 return true; | |
607 } | |
608 | |
609 //------------------------------clone_up_backedge_goo-------------------------- | |
610 // If Node n lives in the back_ctrl block and cannot float, we clone a private | |
611 // version of n in preheader_ctrl block and return that, otherwise return n. | |
612 Node *PhaseIdealLoop::clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n ) { | |
613 if( get_ctrl(n) != back_ctrl ) return n; | |
614 | |
615 Node *x = NULL; // If required, a clone of 'n' | |
616 // Check for 'n' being pinned in the backedge. | |
617 if( n->in(0) && n->in(0) == back_ctrl ) { | |
618 x = n->clone(); // Clone a copy of 'n' to preheader | |
619 x->set_req( 0, preheader_ctrl ); // Fix x's control input to preheader | |
620 } | |
621 | |
622 // Recursive fixup any other input edges into x. | |
623 // If there are no changes we can just return 'n', otherwise | |
624 // we need to clone a private copy and change it. | |
625 for( uint i = 1; i < n->req(); i++ ) { | |
626 Node *g = clone_up_backedge_goo( back_ctrl, preheader_ctrl, n->in(i) ); | |
627 if( g != n->in(i) ) { | |
628 if( !x ) | |
629 x = n->clone(); | |
630 x->set_req(i, g); | |
631 } | |
632 } | |
633 if( x ) { // x can legally float to pre-header location | |
634 register_new_node( x, preheader_ctrl ); | |
635 return x; | |
636 } else { // raise n to cover LCA of uses | |
637 set_ctrl( n, find_non_split_ctrl(back_ctrl->in(0)) ); | |
638 } | |
639 return n; | |
640 } | |
641 | |
642 //------------------------------insert_pre_post_loops-------------------------- | |
643 // Insert pre and post loops. If peel_only is set, the pre-loop can not have | |
644 // more iterations added. It acts as a 'peel' only, no lower-bound RCE, no | |
645 // alignment. Useful to unroll loops that do no array accesses. | |
646 void PhaseIdealLoop::insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only ) { | |
647 | |
648 C->set_major_progress(); | |
649 | |
650 // Find common pieces of the loop being guarded with pre & post loops | |
651 CountedLoopNode *main_head = loop->_head->as_CountedLoop(); | |
652 assert( main_head->is_normal_loop(), "" ); | |
653 CountedLoopEndNode *main_end = main_head->loopexit(); | |
654 assert( main_end->outcnt() == 2, "1 true, 1 false path only" ); | |
655 uint dd_main_head = dom_depth(main_head); | |
656 uint max = main_head->outcnt(); | |
657 | |
658 Node *pre_header= main_head->in(LoopNode::EntryControl); | |
659 Node *init = main_head->init_trip(); | |
660 Node *incr = main_end ->incr(); | |
661 Node *limit = main_end ->limit(); | |
662 Node *stride = main_end ->stride(); | |
663 Node *cmp = main_end ->cmp_node(); | |
664 BoolTest::mask b_test = main_end->test_trip(); | |
665 | |
666 // Need only 1 user of 'bol' because I will be hacking the loop bounds. | |
667 Node *bol = main_end->in(CountedLoopEndNode::TestValue); | |
668 if( bol->outcnt() != 1 ) { | |
669 bol = bol->clone(); | |
670 register_new_node(bol,main_end->in(CountedLoopEndNode::TestControl)); | |
671 _igvn.hash_delete(main_end); | |
672 main_end->set_req(CountedLoopEndNode::TestValue, bol); | |
673 } | |
674 // Need only 1 user of 'cmp' because I will be hacking the loop bounds. | |
675 if( cmp->outcnt() != 1 ) { | |
676 cmp = cmp->clone(); | |
677 register_new_node(cmp,main_end->in(CountedLoopEndNode::TestControl)); | |
678 _igvn.hash_delete(bol); | |
679 bol->set_req(1, cmp); | |
680 } | |
681 | |
682 //------------------------------ | |
683 // Step A: Create Post-Loop. | |
684 Node* main_exit = main_end->proj_out(false); | |
685 assert( main_exit->Opcode() == Op_IfFalse, "" ); | |
686 int dd_main_exit = dom_depth(main_exit); | |
687 | |
688 // Step A1: Clone the loop body. The clone becomes the post-loop. The main | |
689 // loop pre-header illegally has 2 control users (old & new loops). | |
690 clone_loop( loop, old_new, dd_main_exit ); | |
691 assert( old_new[main_end ->_idx]->Opcode() == Op_CountedLoopEnd, "" ); | |
692 CountedLoopNode *post_head = old_new[main_head->_idx]->as_CountedLoop(); | |
693 post_head->set_post_loop(main_head); | |
694 | |
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695 // Reduce the post-loop trip count. |
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696 CountedLoopEndNode* post_end = old_new[main_end ->_idx]->as_CountedLoopEnd(); |
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697 post_end->_prob = PROB_FAIR; |
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698 |
0 | 699 // Build the main-loop normal exit. |
700 IfFalseNode *new_main_exit = new (C, 1) IfFalseNode(main_end); | |
701 _igvn.register_new_node_with_optimizer( new_main_exit ); | |
702 set_idom(new_main_exit, main_end, dd_main_exit ); | |
703 set_loop(new_main_exit, loop->_parent); | |
704 | |
705 // Step A2: Build a zero-trip guard for the post-loop. After leaving the | |
706 // main-loop, the post-loop may not execute at all. We 'opaque' the incr | |
707 // (the main-loop trip-counter exit value) because we will be changing | |
708 // the exit value (via unrolling) so we cannot constant-fold away the zero | |
709 // trip guard until all unrolling is done. | |
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710 Node *zer_opaq = new (C, 2) Opaque1Node(C, incr); |
0 | 711 Node *zer_cmp = new (C, 3) CmpINode( zer_opaq, limit ); |
712 Node *zer_bol = new (C, 2) BoolNode( zer_cmp, b_test ); | |
713 register_new_node( zer_opaq, new_main_exit ); | |
714 register_new_node( zer_cmp , new_main_exit ); | |
715 register_new_node( zer_bol , new_main_exit ); | |
716 | |
717 // Build the IfNode | |
718 IfNode *zer_iff = new (C, 2) IfNode( new_main_exit, zer_bol, PROB_FAIR, COUNT_UNKNOWN ); | |
719 _igvn.register_new_node_with_optimizer( zer_iff ); | |
720 set_idom(zer_iff, new_main_exit, dd_main_exit); | |
721 set_loop(zer_iff, loop->_parent); | |
722 | |
723 // Plug in the false-path, taken if we need to skip post-loop | |
724 _igvn.hash_delete( main_exit ); | |
725 main_exit->set_req(0, zer_iff); | |
726 _igvn._worklist.push(main_exit); | |
727 set_idom(main_exit, zer_iff, dd_main_exit); | |
728 set_idom(main_exit->unique_out(), zer_iff, dd_main_exit); | |
729 // Make the true-path, must enter the post loop | |
730 Node *zer_taken = new (C, 1) IfTrueNode( zer_iff ); | |
731 _igvn.register_new_node_with_optimizer( zer_taken ); | |
732 set_idom(zer_taken, zer_iff, dd_main_exit); | |
733 set_loop(zer_taken, loop->_parent); | |
734 // Plug in the true path | |
735 _igvn.hash_delete( post_head ); | |
736 post_head->set_req(LoopNode::EntryControl, zer_taken); | |
737 set_idom(post_head, zer_taken, dd_main_exit); | |
738 | |
739 // Step A3: Make the fall-in values to the post-loop come from the | |
740 // fall-out values of the main-loop. | |
741 for (DUIterator_Fast imax, i = main_head->fast_outs(imax); i < imax; i++) { | |
742 Node* main_phi = main_head->fast_out(i); | |
743 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() >0 ) { | |
744 Node *post_phi = old_new[main_phi->_idx]; | |
745 Node *fallmain = clone_up_backedge_goo(main_head->back_control(), | |
746 post_head->init_control(), | |
747 main_phi->in(LoopNode::LoopBackControl)); | |
748 _igvn.hash_delete(post_phi); | |
749 post_phi->set_req( LoopNode::EntryControl, fallmain ); | |
750 } | |
751 } | |
752 | |
753 // Update local caches for next stanza | |
754 main_exit = new_main_exit; | |
755 | |
756 | |
757 //------------------------------ | |
758 // Step B: Create Pre-Loop. | |
759 | |
760 // Step B1: Clone the loop body. The clone becomes the pre-loop. The main | |
761 // loop pre-header illegally has 2 control users (old & new loops). | |
762 clone_loop( loop, old_new, dd_main_head ); | |
763 CountedLoopNode* pre_head = old_new[main_head->_idx]->as_CountedLoop(); | |
764 CountedLoopEndNode* pre_end = old_new[main_end ->_idx]->as_CountedLoopEnd(); | |
765 pre_head->set_pre_loop(main_head); | |
766 Node *pre_incr = old_new[incr->_idx]; | |
767 | |
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768 // Reduce the pre-loop trip count. |
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769 pre_end->_prob = PROB_FAIR; |
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770 |
0 | 771 // Find the pre-loop normal exit. |
772 Node* pre_exit = pre_end->proj_out(false); | |
773 assert( pre_exit->Opcode() == Op_IfFalse, "" ); | |
774 IfFalseNode *new_pre_exit = new (C, 1) IfFalseNode(pre_end); | |
775 _igvn.register_new_node_with_optimizer( new_pre_exit ); | |
776 set_idom(new_pre_exit, pre_end, dd_main_head); | |
777 set_loop(new_pre_exit, loop->_parent); | |
778 | |
779 // Step B2: Build a zero-trip guard for the main-loop. After leaving the | |
780 // pre-loop, the main-loop may not execute at all. Later in life this | |
781 // zero-trip guard will become the minimum-trip guard when we unroll | |
782 // the main-loop. | |
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783 Node *min_opaq = new (C, 2) Opaque1Node(C, limit); |
0 | 784 Node *min_cmp = new (C, 3) CmpINode( pre_incr, min_opaq ); |
785 Node *min_bol = new (C, 2) BoolNode( min_cmp, b_test ); | |
786 register_new_node( min_opaq, new_pre_exit ); | |
787 register_new_node( min_cmp , new_pre_exit ); | |
788 register_new_node( min_bol , new_pre_exit ); | |
789 | |
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790 // Build the IfNode (assume the main-loop is executed always). |
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791 IfNode *min_iff = new (C, 2) IfNode( new_pre_exit, min_bol, PROB_ALWAYS, COUNT_UNKNOWN ); |
0 | 792 _igvn.register_new_node_with_optimizer( min_iff ); |
793 set_idom(min_iff, new_pre_exit, dd_main_head); | |
794 set_loop(min_iff, loop->_parent); | |
795 | |
796 // Plug in the false-path, taken if we need to skip main-loop | |
797 _igvn.hash_delete( pre_exit ); | |
798 pre_exit->set_req(0, min_iff); | |
799 set_idom(pre_exit, min_iff, dd_main_head); | |
800 set_idom(pre_exit->unique_out(), min_iff, dd_main_head); | |
801 // Make the true-path, must enter the main loop | |
802 Node *min_taken = new (C, 1) IfTrueNode( min_iff ); | |
803 _igvn.register_new_node_with_optimizer( min_taken ); | |
804 set_idom(min_taken, min_iff, dd_main_head); | |
805 set_loop(min_taken, loop->_parent); | |
806 // Plug in the true path | |
807 _igvn.hash_delete( main_head ); | |
808 main_head->set_req(LoopNode::EntryControl, min_taken); | |
809 set_idom(main_head, min_taken, dd_main_head); | |
810 | |
811 // Step B3: Make the fall-in values to the main-loop come from the | |
812 // fall-out values of the pre-loop. | |
813 for (DUIterator_Fast i2max, i2 = main_head->fast_outs(i2max); i2 < i2max; i2++) { | |
814 Node* main_phi = main_head->fast_out(i2); | |
815 if( main_phi->is_Phi() && main_phi->in(0) == main_head && main_phi->outcnt() > 0 ) { | |
816 Node *pre_phi = old_new[main_phi->_idx]; | |
817 Node *fallpre = clone_up_backedge_goo(pre_head->back_control(), | |
818 main_head->init_control(), | |
819 pre_phi->in(LoopNode::LoopBackControl)); | |
820 _igvn.hash_delete(main_phi); | |
821 main_phi->set_req( LoopNode::EntryControl, fallpre ); | |
822 } | |
823 } | |
824 | |
825 // Step B4: Shorten the pre-loop to run only 1 iteration (for now). | |
826 // RCE and alignment may change this later. | |
827 Node *cmp_end = pre_end->cmp_node(); | |
828 assert( cmp_end->in(2) == limit, "" ); | |
829 Node *pre_limit = new (C, 3) AddINode( init, stride ); | |
830 | |
831 // Save the original loop limit in this Opaque1 node for | |
832 // use by range check elimination. | |
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833 Node *pre_opaq = new (C, 3) Opaque1Node(C, pre_limit, limit); |
0 | 834 |
835 register_new_node( pre_limit, pre_head->in(0) ); | |
836 register_new_node( pre_opaq , pre_head->in(0) ); | |
837 | |
838 // Since no other users of pre-loop compare, I can hack limit directly | |
839 assert( cmp_end->outcnt() == 1, "no other users" ); | |
840 _igvn.hash_delete(cmp_end); | |
841 cmp_end->set_req(2, peel_only ? pre_limit : pre_opaq); | |
842 | |
843 // Special case for not-equal loop bounds: | |
844 // Change pre loop test, main loop test, and the | |
845 // main loop guard test to use lt or gt depending on stride | |
846 // direction: | |
847 // positive stride use < | |
848 // negative stride use > | |
849 | |
850 if (pre_end->in(CountedLoopEndNode::TestValue)->as_Bool()->_test._test == BoolTest::ne) { | |
851 | |
852 BoolTest::mask new_test = (main_end->stride_con() > 0) ? BoolTest::lt : BoolTest::gt; | |
853 // Modify pre loop end condition | |
854 Node* pre_bol = pre_end->in(CountedLoopEndNode::TestValue)->as_Bool(); | |
855 BoolNode* new_bol0 = new (C, 2) BoolNode(pre_bol->in(1), new_test); | |
856 register_new_node( new_bol0, pre_head->in(0) ); | |
857 _igvn.hash_delete(pre_end); | |
858 pre_end->set_req(CountedLoopEndNode::TestValue, new_bol0); | |
859 // Modify main loop guard condition | |
860 assert(min_iff->in(CountedLoopEndNode::TestValue) == min_bol, "guard okay"); | |
861 BoolNode* new_bol1 = new (C, 2) BoolNode(min_bol->in(1), new_test); | |
862 register_new_node( new_bol1, new_pre_exit ); | |
863 _igvn.hash_delete(min_iff); | |
864 min_iff->set_req(CountedLoopEndNode::TestValue, new_bol1); | |
865 // Modify main loop end condition | |
866 BoolNode* main_bol = main_end->in(CountedLoopEndNode::TestValue)->as_Bool(); | |
867 BoolNode* new_bol2 = new (C, 2) BoolNode(main_bol->in(1), new_test); | |
868 register_new_node( new_bol2, main_end->in(CountedLoopEndNode::TestControl) ); | |
869 _igvn.hash_delete(main_end); | |
870 main_end->set_req(CountedLoopEndNode::TestValue, new_bol2); | |
871 } | |
872 | |
873 // Flag main loop | |
874 main_head->set_main_loop(); | |
875 if( peel_only ) main_head->set_main_no_pre_loop(); | |
876 | |
877 // It's difficult to be precise about the trip-counts | |
878 // for the pre/post loops. They are usually very short, | |
879 // so guess that 4 trips is a reasonable value. | |
880 post_head->set_profile_trip_cnt(4.0); | |
881 pre_head->set_profile_trip_cnt(4.0); | |
882 | |
883 // Now force out all loop-invariant dominating tests. The optimizer | |
884 // finds some, but we _know_ they are all useless. | |
885 peeled_dom_test_elim(loop,old_new); | |
886 } | |
887 | |
888 //------------------------------is_invariant----------------------------- | |
889 // Return true if n is invariant | |
890 bool IdealLoopTree::is_invariant(Node* n) const { | |
1172 | 891 Node *n_c = _phase->has_ctrl(n) ? _phase->get_ctrl(n) : n; |
0 | 892 if (n_c->is_top()) return false; |
893 return !is_member(_phase->get_loop(n_c)); | |
894 } | |
895 | |
896 | |
897 //------------------------------do_unroll-------------------------------------- | |
898 // Unroll the loop body one step - make each trip do 2 iterations. | |
899 void PhaseIdealLoop::do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip ) { | |
900 assert( LoopUnrollLimit, "" ); | |
901 #ifndef PRODUCT | |
902 if( PrintOpto && VerifyLoopOptimizations ) { | |
903 tty->print("Unrolling "); | |
904 loop->dump_head(); | |
905 } | |
906 #endif | |
907 CountedLoopNode *loop_head = loop->_head->as_CountedLoop(); | |
908 CountedLoopEndNode *loop_end = loop_head->loopexit(); | |
909 assert( loop_end, "" ); | |
910 | |
911 // Remember loop node count before unrolling to detect | |
912 // if rounds of unroll,optimize are making progress | |
913 loop_head->set_node_count_before_unroll(loop->_body.size()); | |
914 | |
915 Node *ctrl = loop_head->in(LoopNode::EntryControl); | |
916 Node *limit = loop_head->limit(); | |
917 Node *init = loop_head->init_trip(); | |
918 Node *strid = loop_head->stride(); | |
919 | |
920 Node *opaq = NULL; | |
921 if( adjust_min_trip ) { // If not maximally unrolling, need adjustment | |
922 assert( loop_head->is_main_loop(), "" ); | |
923 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" ); | |
924 Node *iff = ctrl->in(0); | |
925 assert( iff->Opcode() == Op_If, "" ); | |
926 Node *bol = iff->in(1); | |
927 assert( bol->Opcode() == Op_Bool, "" ); | |
928 Node *cmp = bol->in(1); | |
929 assert( cmp->Opcode() == Op_CmpI, "" ); | |
930 opaq = cmp->in(2); | |
931 // Occasionally it's possible for a pre-loop Opaque1 node to be | |
932 // optimized away and then another round of loop opts attempted. | |
933 // We can not optimize this particular loop in that case. | |
934 if( opaq->Opcode() != Op_Opaque1 ) | |
935 return; // Cannot find pre-loop! Bail out! | |
936 } | |
937 | |
938 C->set_major_progress(); | |
939 | |
940 // Adjust max trip count. The trip count is intentionally rounded | |
941 // down here (e.g. 15-> 7-> 3-> 1) because if we unwittingly over-unroll, | |
942 // the main, unrolled, part of the loop will never execute as it is protected | |
943 // by the min-trip test. See bug 4834191 for a case where we over-unrolled | |
944 // and later determined that part of the unrolled loop was dead. | |
945 loop_head->set_trip_count(loop_head->trip_count() / 2); | |
946 | |
947 // Double the count of original iterations in the unrolled loop body. | |
948 loop_head->double_unrolled_count(); | |
949 | |
950 // ----------- | |
951 // Step 2: Cut back the trip counter for an unroll amount of 2. | |
952 // Loop will normally trip (limit - init)/stride_con. Since it's a | |
953 // CountedLoop this is exact (stride divides limit-init exactly). | |
954 // We are going to double the loop body, so we want to knock off any | |
955 // odd iteration: (trip_cnt & ~1). Then back compute a new limit. | |
956 Node *span = new (C, 3) SubINode( limit, init ); | |
957 register_new_node( span, ctrl ); | |
958 Node *trip = new (C, 3) DivINode( 0, span, strid ); | |
959 register_new_node( trip, ctrl ); | |
960 Node *mtwo = _igvn.intcon(-2); | |
961 set_ctrl(mtwo, C->root()); | |
962 Node *rond = new (C, 3) AndINode( trip, mtwo ); | |
963 register_new_node( rond, ctrl ); | |
964 Node *spn2 = new (C, 3) MulINode( rond, strid ); | |
965 register_new_node( spn2, ctrl ); | |
966 Node *lim2 = new (C, 3) AddINode( spn2, init ); | |
967 register_new_node( lim2, ctrl ); | |
968 | |
969 // Hammer in the new limit | |
970 Node *ctrl2 = loop_end->in(0); | |
971 Node *cmp2 = new (C, 3) CmpINode( loop_head->incr(), lim2 ); | |
972 register_new_node( cmp2, ctrl2 ); | |
973 Node *bol2 = new (C, 2) BoolNode( cmp2, loop_end->test_trip() ); | |
974 register_new_node( bol2, ctrl2 ); | |
975 _igvn.hash_delete(loop_end); | |
976 loop_end->set_req(CountedLoopEndNode::TestValue, bol2); | |
977 | |
978 // Step 3: Find the min-trip test guaranteed before a 'main' loop. | |
979 // Make it a 1-trip test (means at least 2 trips). | |
980 if( adjust_min_trip ) { | |
981 // Guard test uses an 'opaque' node which is not shared. Hence I | |
982 // can edit it's inputs directly. Hammer in the new limit for the | |
983 // minimum-trip guard. | |
984 assert( opaq->outcnt() == 1, "" ); | |
985 _igvn.hash_delete(opaq); | |
986 opaq->set_req(1, lim2); | |
987 } | |
988 | |
989 // --------- | |
990 // Step 4: Clone the loop body. Move it inside the loop. This loop body | |
991 // represents the odd iterations; since the loop trips an even number of | |
992 // times its backedge is never taken. Kill the backedge. | |
993 uint dd = dom_depth(loop_head); | |
994 clone_loop( loop, old_new, dd ); | |
995 | |
996 // Make backedges of the clone equal to backedges of the original. | |
997 // Make the fall-in from the original come from the fall-out of the clone. | |
998 for (DUIterator_Fast jmax, j = loop_head->fast_outs(jmax); j < jmax; j++) { | |
999 Node* phi = loop_head->fast_out(j); | |
1000 if( phi->is_Phi() && phi->in(0) == loop_head && phi->outcnt() > 0 ) { | |
1001 Node *newphi = old_new[phi->_idx]; | |
1002 _igvn.hash_delete( phi ); | |
1003 _igvn.hash_delete( newphi ); | |
1004 | |
1005 phi ->set_req(LoopNode:: EntryControl, newphi->in(LoopNode::LoopBackControl)); | |
1006 newphi->set_req(LoopNode::LoopBackControl, phi ->in(LoopNode::LoopBackControl)); | |
1007 phi ->set_req(LoopNode::LoopBackControl, C->top()); | |
1008 } | |
1009 } | |
1010 Node *clone_head = old_new[loop_head->_idx]; | |
1011 _igvn.hash_delete( clone_head ); | |
1012 loop_head ->set_req(LoopNode:: EntryControl, clone_head->in(LoopNode::LoopBackControl)); | |
1013 clone_head->set_req(LoopNode::LoopBackControl, loop_head ->in(LoopNode::LoopBackControl)); | |
1014 loop_head ->set_req(LoopNode::LoopBackControl, C->top()); | |
1015 loop->_head = clone_head; // New loop header | |
1016 | |
1017 set_idom(loop_head, loop_head ->in(LoopNode::EntryControl), dd); | |
1018 set_idom(clone_head, clone_head->in(LoopNode::EntryControl), dd); | |
1019 | |
1020 // Kill the clone's backedge | |
1021 Node *newcle = old_new[loop_end->_idx]; | |
1022 _igvn.hash_delete( newcle ); | |
1023 Node *one = _igvn.intcon(1); | |
1024 set_ctrl(one, C->root()); | |
1025 newcle->set_req(1, one); | |
1026 // Force clone into same loop body | |
1027 uint max = loop->_body.size(); | |
1028 for( uint k = 0; k < max; k++ ) { | |
1029 Node *old = loop->_body.at(k); | |
1030 Node *nnn = old_new[old->_idx]; | |
1031 loop->_body.push(nnn); | |
1032 if (!has_ctrl(old)) | |
1033 set_loop(nnn, loop); | |
1034 } | |
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1036 loop->record_for_igvn(); |
0 | 1037 } |
1038 | |
1039 //------------------------------do_maximally_unroll---------------------------- | |
1040 | |
1041 void PhaseIdealLoop::do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new ) { | |
1042 CountedLoopNode *cl = loop->_head->as_CountedLoop(); | |
1043 assert( cl->trip_count() > 0, ""); | |
1044 | |
1045 // If loop is tripping an odd number of times, peel odd iteration | |
1046 if( (cl->trip_count() & 1) == 1 ) { | |
1047 do_peeling( loop, old_new ); | |
1048 } | |
1049 | |
1050 // Now its tripping an even number of times remaining. Double loop body. | |
1051 // Do not adjust pre-guards; they are not needed and do not exist. | |
1052 if( cl->trip_count() > 0 ) { | |
1053 do_unroll( loop, old_new, false ); | |
1054 } | |
1055 } | |
1056 | |
1057 //------------------------------dominates_backedge--------------------------------- | |
1058 // Returns true if ctrl is executed on every complete iteration | |
1059 bool IdealLoopTree::dominates_backedge(Node* ctrl) { | |
1060 assert(ctrl->is_CFG(), "must be control"); | |
1061 Node* backedge = _head->as_Loop()->in(LoopNode::LoopBackControl); | |
1062 return _phase->dom_lca_internal(ctrl, backedge) == ctrl; | |
1063 } | |
1064 | |
1065 //------------------------------add_constraint--------------------------------- | |
1066 // Constrain the main loop iterations so the condition: | |
1067 // scale_con * I + offset < limit | |
1068 // always holds true. That is, either increase the number of iterations in | |
1069 // the pre-loop or the post-loop until the condition holds true in the main | |
1070 // loop. Stride, scale, offset and limit are all loop invariant. Further, | |
1071 // stride and scale are constants (offset and limit often are). | |
1072 void PhaseIdealLoop::add_constraint( int stride_con, int scale_con, Node *offset, Node *limit, Node *pre_ctrl, Node **pre_limit, Node **main_limit ) { | |
1073 | |
1074 // Compute "I :: (limit-offset)/scale_con" | |
1075 Node *con = new (C, 3) SubINode( limit, offset ); | |
1076 register_new_node( con, pre_ctrl ); | |
1077 Node *scale = _igvn.intcon(scale_con); | |
1078 set_ctrl(scale, C->root()); | |
1079 Node *X = new (C, 3) DivINode( 0, con, scale ); | |
1080 register_new_node( X, pre_ctrl ); | |
1081 | |
1082 // For positive stride, the pre-loop limit always uses a MAX function | |
1083 // and the main loop a MIN function. For negative stride these are | |
1084 // reversed. | |
1085 | |
1086 // Also for positive stride*scale the affine function is increasing, so the | |
1087 // pre-loop must check for underflow and the post-loop for overflow. | |
1088 // Negative stride*scale reverses this; pre-loop checks for overflow and | |
1089 // post-loop for underflow. | |
1090 if( stride_con*scale_con > 0 ) { | |
1091 // Compute I < (limit-offset)/scale_con | |
1092 // Adjust main-loop last iteration to be MIN/MAX(main_loop,X) | |
1093 *main_limit = (stride_con > 0) | |
1094 ? (Node*)(new (C, 3) MinINode( *main_limit, X )) | |
1095 : (Node*)(new (C, 3) MaxINode( *main_limit, X )); | |
1096 register_new_node( *main_limit, pre_ctrl ); | |
1097 | |
1098 } else { | |
1099 // Compute (limit-offset)/scale_con + SGN(-scale_con) <= I | |
1100 // Add the negation of the main-loop constraint to the pre-loop. | |
1101 // See footnote [++] below for a derivation of the limit expression. | |
1102 Node *incr = _igvn.intcon(scale_con > 0 ? -1 : 1); | |
1103 set_ctrl(incr, C->root()); | |
1104 Node *adj = new (C, 3) AddINode( X, incr ); | |
1105 register_new_node( adj, pre_ctrl ); | |
1106 *pre_limit = (scale_con > 0) | |
1107 ? (Node*)new (C, 3) MinINode( *pre_limit, adj ) | |
1108 : (Node*)new (C, 3) MaxINode( *pre_limit, adj ); | |
1109 register_new_node( *pre_limit, pre_ctrl ); | |
1110 | |
1111 // [++] Here's the algebra that justifies the pre-loop limit expression: | |
1112 // | |
1113 // NOT( scale_con * I + offset < limit ) | |
1114 // == | |
1115 // scale_con * I + offset >= limit | |
1116 // == | |
1117 // SGN(scale_con) * I >= (limit-offset)/|scale_con| | |
1118 // == | |
1119 // (limit-offset)/|scale_con| <= I * SGN(scale_con) | |
1120 // == | |
1121 // (limit-offset)/|scale_con|-1 < I * SGN(scale_con) | |
1122 // == | |
1123 // ( if (scale_con > 0) /*common case*/ | |
1124 // (limit-offset)/scale_con - 1 < I | |
1125 // else | |
1126 // (limit-offset)/scale_con + 1 > I | |
1127 // ) | |
1128 // ( if (scale_con > 0) /*common case*/ | |
1129 // (limit-offset)/scale_con + SGN(-scale_con) < I | |
1130 // else | |
1131 // (limit-offset)/scale_con + SGN(-scale_con) > I | |
1132 } | |
1133 } | |
1134 | |
1135 | |
1136 //------------------------------is_scaled_iv--------------------------------- | |
1137 // Return true if exp is a constant times an induction var | |
1138 bool PhaseIdealLoop::is_scaled_iv(Node* exp, Node* iv, int* p_scale) { | |
1139 if (exp == iv) { | |
1140 if (p_scale != NULL) { | |
1141 *p_scale = 1; | |
1142 } | |
1143 return true; | |
1144 } | |
1145 int opc = exp->Opcode(); | |
1146 if (opc == Op_MulI) { | |
1147 if (exp->in(1) == iv && exp->in(2)->is_Con()) { | |
1148 if (p_scale != NULL) { | |
1149 *p_scale = exp->in(2)->get_int(); | |
1150 } | |
1151 return true; | |
1152 } | |
1153 if (exp->in(2) == iv && exp->in(1)->is_Con()) { | |
1154 if (p_scale != NULL) { | |
1155 *p_scale = exp->in(1)->get_int(); | |
1156 } | |
1157 return true; | |
1158 } | |
1159 } else if (opc == Op_LShiftI) { | |
1160 if (exp->in(1) == iv && exp->in(2)->is_Con()) { | |
1161 if (p_scale != NULL) { | |
1162 *p_scale = 1 << exp->in(2)->get_int(); | |
1163 } | |
1164 return true; | |
1165 } | |
1166 } | |
1167 return false; | |
1168 } | |
1169 | |
1170 //-----------------------------is_scaled_iv_plus_offset------------------------------ | |
1171 // Return true if exp is a simple induction variable expression: k1*iv + (invar + k2) | |
1172 bool PhaseIdealLoop::is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset, int depth) { | |
1173 if (is_scaled_iv(exp, iv, p_scale)) { | |
1174 if (p_offset != NULL) { | |
1175 Node *zero = _igvn.intcon(0); | |
1176 set_ctrl(zero, C->root()); | |
1177 *p_offset = zero; | |
1178 } | |
1179 return true; | |
1180 } | |
1181 int opc = exp->Opcode(); | |
1182 if (opc == Op_AddI) { | |
1183 if (is_scaled_iv(exp->in(1), iv, p_scale)) { | |
1184 if (p_offset != NULL) { | |
1185 *p_offset = exp->in(2); | |
1186 } | |
1187 return true; | |
1188 } | |
1189 if (exp->in(2)->is_Con()) { | |
1190 Node* offset2 = NULL; | |
1191 if (depth < 2 && | |
1192 is_scaled_iv_plus_offset(exp->in(1), iv, p_scale, | |
1193 p_offset != NULL ? &offset2 : NULL, depth+1)) { | |
1194 if (p_offset != NULL) { | |
1195 Node *ctrl_off2 = get_ctrl(offset2); | |
1196 Node* offset = new (C, 3) AddINode(offset2, exp->in(2)); | |
1197 register_new_node(offset, ctrl_off2); | |
1198 *p_offset = offset; | |
1199 } | |
1200 return true; | |
1201 } | |
1202 } | |
1203 } else if (opc == Op_SubI) { | |
1204 if (is_scaled_iv(exp->in(1), iv, p_scale)) { | |
1205 if (p_offset != NULL) { | |
1206 Node *zero = _igvn.intcon(0); | |
1207 set_ctrl(zero, C->root()); | |
1208 Node *ctrl_off = get_ctrl(exp->in(2)); | |
1209 Node* offset = new (C, 3) SubINode(zero, exp->in(2)); | |
1210 register_new_node(offset, ctrl_off); | |
1211 *p_offset = offset; | |
1212 } | |
1213 return true; | |
1214 } | |
1215 if (is_scaled_iv(exp->in(2), iv, p_scale)) { | |
1216 if (p_offset != NULL) { | |
1217 *p_scale *= -1; | |
1218 *p_offset = exp->in(1); | |
1219 } | |
1220 return true; | |
1221 } | |
1222 } | |
1223 return false; | |
1224 } | |
1225 | |
1226 //------------------------------do_range_check--------------------------------- | |
1227 // Eliminate range-checks and other trip-counter vs loop-invariant tests. | |
1228 void PhaseIdealLoop::do_range_check( IdealLoopTree *loop, Node_List &old_new ) { | |
1229 #ifndef PRODUCT | |
1230 if( PrintOpto && VerifyLoopOptimizations ) { | |
1231 tty->print("Range Check Elimination "); | |
1232 loop->dump_head(); | |
1233 } | |
1234 #endif | |
1235 assert( RangeCheckElimination, "" ); | |
1236 CountedLoopNode *cl = loop->_head->as_CountedLoop(); | |
1237 assert( cl->is_main_loop(), "" ); | |
1238 | |
1239 // Find the trip counter; we are iteration splitting based on it | |
1240 Node *trip_counter = cl->phi(); | |
1241 // Find the main loop limit; we will trim it's iterations | |
1242 // to not ever trip end tests | |
1243 Node *main_limit = cl->limit(); | |
1244 // Find the pre-loop limit; we will expand it's iterations to | |
1245 // not ever trip low tests. | |
1246 Node *ctrl = cl->in(LoopNode::EntryControl); | |
1247 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" ); | |
1248 Node *iffm = ctrl->in(0); | |
1249 assert( iffm->Opcode() == Op_If, "" ); | |
1250 Node *p_f = iffm->in(0); | |
1251 assert( p_f->Opcode() == Op_IfFalse, "" ); | |
1252 CountedLoopEndNode *pre_end = p_f->in(0)->as_CountedLoopEnd(); | |
1253 assert( pre_end->loopnode()->is_pre_loop(), "" ); | |
1254 Node *pre_opaq1 = pre_end->limit(); | |
1255 // Occasionally it's possible for a pre-loop Opaque1 node to be | |
1256 // optimized away and then another round of loop opts attempted. | |
1257 // We can not optimize this particular loop in that case. | |
1258 if( pre_opaq1->Opcode() != Op_Opaque1 ) | |
1259 return; | |
1260 Opaque1Node *pre_opaq = (Opaque1Node*)pre_opaq1; | |
1261 Node *pre_limit = pre_opaq->in(1); | |
1262 | |
1263 // Where do we put new limit calculations | |
1264 Node *pre_ctrl = pre_end->loopnode()->in(LoopNode::EntryControl); | |
1265 | |
1266 // Ensure the original loop limit is available from the | |
1267 // pre-loop Opaque1 node. | |
1268 Node *orig_limit = pre_opaq->original_loop_limit(); | |
1269 if( orig_limit == NULL || _igvn.type(orig_limit) == Type::TOP ) | |
1270 return; | |
1271 | |
1272 // Need to find the main-loop zero-trip guard | |
1273 Node *bolzm = iffm->in(1); | |
1274 assert( bolzm->Opcode() == Op_Bool, "" ); | |
1275 Node *cmpzm = bolzm->in(1); | |
1276 assert( cmpzm->is_Cmp(), "" ); | |
1277 Node *opqzm = cmpzm->in(2); | |
1278 if( opqzm->Opcode() != Op_Opaque1 ) | |
1279 return; | |
1280 assert( opqzm->in(1) == main_limit, "do not understand situation" ); | |
1281 | |
1282 // Must know if its a count-up or count-down loop | |
1283 | |
1284 // protect against stride not being a constant | |
1285 if ( !cl->stride_is_con() ) { | |
1286 return; | |
1287 } | |
1288 int stride_con = cl->stride_con(); | |
1289 Node *zero = _igvn.intcon(0); | |
1290 Node *one = _igvn.intcon(1); | |
1291 set_ctrl(zero, C->root()); | |
1292 set_ctrl(one, C->root()); | |
1293 | |
1294 // Range checks that do not dominate the loop backedge (ie. | |
1295 // conditionally executed) can lengthen the pre loop limit beyond | |
1296 // the original loop limit. To prevent this, the pre limit is | |
1297 // (for stride > 0) MINed with the original loop limit (MAXed | |
1298 // stride < 0) when some range_check (rc) is conditionally | |
1299 // executed. | |
1300 bool conditional_rc = false; | |
1301 | |
1302 // Check loop body for tests of trip-counter plus loop-invariant vs | |
1303 // loop-invariant. | |
1304 for( uint i = 0; i < loop->_body.size(); i++ ) { | |
1305 Node *iff = loop->_body[i]; | |
1306 if( iff->Opcode() == Op_If ) { // Test? | |
1307 | |
1308 // Test is an IfNode, has 2 projections. If BOTH are in the loop | |
1309 // we need loop unswitching instead of iteration splitting. | |
1310 Node *exit = loop->is_loop_exit(iff); | |
1311 if( !exit ) continue; | |
1312 int flip = (exit->Opcode() == Op_IfTrue) ? 1 : 0; | |
1313 | |
1314 // Get boolean condition to test | |
1315 Node *i1 = iff->in(1); | |
1316 if( !i1->is_Bool() ) continue; | |
1317 BoolNode *bol = i1->as_Bool(); | |
1318 BoolTest b_test = bol->_test; | |
1319 // Flip sense of test if exit condition is flipped | |
1320 if( flip ) | |
1321 b_test = b_test.negate(); | |
1322 | |
1323 // Get compare | |
1324 Node *cmp = bol->in(1); | |
1325 | |
1326 // Look for trip_counter + offset vs limit | |
1327 Node *rc_exp = cmp->in(1); | |
1328 Node *limit = cmp->in(2); | |
1329 jint scale_con= 1; // Assume trip counter not scaled | |
1330 | |
1331 Node *limit_c = get_ctrl(limit); | |
1332 if( loop->is_member(get_loop(limit_c) ) ) { | |
1333 // Compare might have operands swapped; commute them | |
1334 b_test = b_test.commute(); | |
1335 rc_exp = cmp->in(2); | |
1336 limit = cmp->in(1); | |
1337 limit_c = get_ctrl(limit); | |
1338 if( loop->is_member(get_loop(limit_c) ) ) | |
1339 continue; // Both inputs are loop varying; cannot RCE | |
1340 } | |
1341 // Here we know 'limit' is loop invariant | |
1342 | |
1343 // 'limit' maybe pinned below the zero trip test (probably from a | |
1344 // previous round of rce), in which case, it can't be used in the | |
1345 // zero trip test expression which must occur before the zero test's if. | |
1346 if( limit_c == ctrl ) { | |
1347 continue; // Don't rce this check but continue looking for other candidates. | |
1348 } | |
1349 | |
1350 // Check for scaled induction variable plus an offset | |
1351 Node *offset = NULL; | |
1352 | |
1353 if (!is_scaled_iv_plus_offset(rc_exp, trip_counter, &scale_con, &offset)) { | |
1354 continue; | |
1355 } | |
1356 | |
1357 Node *offset_c = get_ctrl(offset); | |
1358 if( loop->is_member( get_loop(offset_c) ) ) | |
1359 continue; // Offset is not really loop invariant | |
1360 // Here we know 'offset' is loop invariant. | |
1361 | |
1362 // As above for the 'limit', the 'offset' maybe pinned below the | |
1363 // zero trip test. | |
1364 if( offset_c == ctrl ) { | |
1365 continue; // Don't rce this check but continue looking for other candidates. | |
1366 } | |
1367 | |
1368 // At this point we have the expression as: | |
1369 // scale_con * trip_counter + offset :: limit | |
1370 // where scale_con, offset and limit are loop invariant. Trip_counter | |
1371 // monotonically increases by stride_con, a constant. Both (or either) | |
1372 // stride_con and scale_con can be negative which will flip about the | |
1373 // sense of the test. | |
1374 | |
1375 // Adjust pre and main loop limits to guard the correct iteration set | |
1376 if( cmp->Opcode() == Op_CmpU ) {// Unsigned compare is really 2 tests | |
1377 if( b_test._test == BoolTest::lt ) { // Range checks always use lt | |
1378 // The overflow limit: scale*I+offset < limit | |
1379 add_constraint( stride_con, scale_con, offset, limit, pre_ctrl, &pre_limit, &main_limit ); | |
1380 // The underflow limit: 0 <= scale*I+offset. | |
1381 // Some math yields: -scale*I-(offset+1) < 0 | |
1382 Node *plus_one = new (C, 3) AddINode( offset, one ); | |
1383 register_new_node( plus_one, pre_ctrl ); | |
1384 Node *neg_offset = new (C, 3) SubINode( zero, plus_one ); | |
1385 register_new_node( neg_offset, pre_ctrl ); | |
1386 add_constraint( stride_con, -scale_con, neg_offset, zero, pre_ctrl, &pre_limit, &main_limit ); | |
1387 if (!conditional_rc) { | |
1388 conditional_rc = !loop->dominates_backedge(iff); | |
1389 } | |
1390 } else { | |
1391 #ifndef PRODUCT | |
1392 if( PrintOpto ) | |
1393 tty->print_cr("missed RCE opportunity"); | |
1394 #endif | |
1395 continue; // In release mode, ignore it | |
1396 } | |
1397 } else { // Otherwise work on normal compares | |
1398 switch( b_test._test ) { | |
1399 case BoolTest::ge: // Convert X >= Y to -X <= -Y | |
1400 scale_con = -scale_con; | |
1401 offset = new (C, 3) SubINode( zero, offset ); | |
1402 register_new_node( offset, pre_ctrl ); | |
1403 limit = new (C, 3) SubINode( zero, limit ); | |
1404 register_new_node( limit, pre_ctrl ); | |
1405 // Fall into LE case | |
1406 case BoolTest::le: // Convert X <= Y to X < Y+1 | |
1407 limit = new (C, 3) AddINode( limit, one ); | |
1408 register_new_node( limit, pre_ctrl ); | |
1409 // Fall into LT case | |
1410 case BoolTest::lt: | |
1411 add_constraint( stride_con, scale_con, offset, limit, pre_ctrl, &pre_limit, &main_limit ); | |
1412 if (!conditional_rc) { | |
1413 conditional_rc = !loop->dominates_backedge(iff); | |
1414 } | |
1415 break; | |
1416 default: | |
1417 #ifndef PRODUCT | |
1418 if( PrintOpto ) | |
1419 tty->print_cr("missed RCE opportunity"); | |
1420 #endif | |
1421 continue; // Unhandled case | |
1422 } | |
1423 } | |
1424 | |
1425 // Kill the eliminated test | |
1426 C->set_major_progress(); | |
1427 Node *kill_con = _igvn.intcon( 1-flip ); | |
1428 set_ctrl(kill_con, C->root()); | |
1429 _igvn.hash_delete(iff); | |
1430 iff->set_req(1, kill_con); | |
1431 _igvn._worklist.push(iff); | |
1432 // Find surviving projection | |
1433 assert(iff->is_If(), ""); | |
1434 ProjNode* dp = ((IfNode*)iff)->proj_out(1-flip); | |
1435 // Find loads off the surviving projection; remove their control edge | |
1436 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) { | |
1437 Node* cd = dp->fast_out(i); // Control-dependent node | |
1438 if( cd->is_Load() ) { // Loads can now float around in the loop | |
1439 _igvn.hash_delete(cd); | |
1440 // Allow the load to float around in the loop, or before it | |
1441 // but NOT before the pre-loop. | |
1442 cd->set_req(0, ctrl); // ctrl, not NULL | |
1443 _igvn._worklist.push(cd); | |
1444 --i; | |
1445 --imax; | |
1446 } | |
1447 } | |
1448 | |
1449 } // End of is IF | |
1450 | |
1451 } | |
1452 | |
1453 // Update loop limits | |
1454 if (conditional_rc) { | |
1455 pre_limit = (stride_con > 0) ? (Node*)new (C,3) MinINode(pre_limit, orig_limit) | |
1456 : (Node*)new (C,3) MaxINode(pre_limit, orig_limit); | |
1457 register_new_node(pre_limit, pre_ctrl); | |
1458 } | |
1459 _igvn.hash_delete(pre_opaq); | |
1460 pre_opaq->set_req(1, pre_limit); | |
1461 | |
1462 // Note:: we are making the main loop limit no longer precise; | |
1463 // need to round up based on stride. | |
1464 if( stride_con != 1 && stride_con != -1 ) { // Cutout for common case | |
1465 // "Standard" round-up logic: ([main_limit-init+(y-1)]/y)*y+init | |
1466 // Hopefully, compiler will optimize for powers of 2. | |
1467 Node *ctrl = get_ctrl(main_limit); | |
1468 Node *stride = cl->stride(); | |
1469 Node *init = cl->init_trip(); | |
1470 Node *span = new (C, 3) SubINode(main_limit,init); | |
1471 register_new_node(span,ctrl); | |
1472 Node *rndup = _igvn.intcon(stride_con + ((stride_con>0)?-1:1)); | |
1473 Node *add = new (C, 3) AddINode(span,rndup); | |
1474 register_new_node(add,ctrl); | |
1475 Node *div = new (C, 3) DivINode(0,add,stride); | |
1476 register_new_node(div,ctrl); | |
1477 Node *mul = new (C, 3) MulINode(div,stride); | |
1478 register_new_node(mul,ctrl); | |
1479 Node *newlim = new (C, 3) AddINode(mul,init); | |
1480 register_new_node(newlim,ctrl); | |
1481 main_limit = newlim; | |
1482 } | |
1483 | |
1484 Node *main_cle = cl->loopexit(); | |
1485 Node *main_bol = main_cle->in(1); | |
1486 // Hacking loop bounds; need private copies of exit test | |
1487 if( main_bol->outcnt() > 1 ) {// BoolNode shared? | |
1488 _igvn.hash_delete(main_cle); | |
1489 main_bol = main_bol->clone();// Clone a private BoolNode | |
1490 register_new_node( main_bol, main_cle->in(0) ); | |
1491 main_cle->set_req(1,main_bol); | |
1492 } | |
1493 Node *main_cmp = main_bol->in(1); | |
1494 if( main_cmp->outcnt() > 1 ) { // CmpNode shared? | |
1495 _igvn.hash_delete(main_bol); | |
1496 main_cmp = main_cmp->clone();// Clone a private CmpNode | |
1497 register_new_node( main_cmp, main_cle->in(0) ); | |
1498 main_bol->set_req(1,main_cmp); | |
1499 } | |
1500 // Hack the now-private loop bounds | |
1501 _igvn.hash_delete(main_cmp); | |
1502 main_cmp->set_req(2, main_limit); | |
1503 _igvn._worklist.push(main_cmp); | |
1504 // The OpaqueNode is unshared by design | |
1505 _igvn.hash_delete(opqzm); | |
1506 assert( opqzm->outcnt() == 1, "cannot hack shared node" ); | |
1507 opqzm->set_req(1,main_limit); | |
1508 _igvn._worklist.push(opqzm); | |
1509 } | |
1510 | |
1511 //------------------------------DCE_loop_body---------------------------------- | |
1512 // Remove simplistic dead code from loop body | |
1513 void IdealLoopTree::DCE_loop_body() { | |
1514 for( uint i = 0; i < _body.size(); i++ ) | |
1515 if( _body.at(i)->outcnt() == 0 ) | |
1516 _body.map( i--, _body.pop() ); | |
1517 } | |
1518 | |
1519 | |
1520 //------------------------------adjust_loop_exit_prob-------------------------- | |
1521 // Look for loop-exit tests with the 50/50 (or worse) guesses from the parsing stage. | |
1522 // Replace with a 1-in-10 exit guess. | |
1523 void IdealLoopTree::adjust_loop_exit_prob( PhaseIdealLoop *phase ) { | |
1524 Node *test = tail(); | |
1525 while( test != _head ) { | |
1526 uint top = test->Opcode(); | |
1527 if( top == Op_IfTrue || top == Op_IfFalse ) { | |
1528 int test_con = ((ProjNode*)test)->_con; | |
1529 assert(top == (uint)(test_con? Op_IfTrue: Op_IfFalse), "sanity"); | |
1530 IfNode *iff = test->in(0)->as_If(); | |
1531 if( iff->outcnt() == 2 ) { // Ignore dead tests | |
1532 Node *bol = iff->in(1); | |
1533 if( bol && bol->req() > 1 && bol->in(1) && | |
1534 ((bol->in(1)->Opcode() == Op_StorePConditional ) || | |
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1535 (bol->in(1)->Opcode() == Op_StoreIConditional ) || |
0 | 1536 (bol->in(1)->Opcode() == Op_StoreLConditional ) || |
1537 (bol->in(1)->Opcode() == Op_CompareAndSwapI ) || | |
1538 (bol->in(1)->Opcode() == Op_CompareAndSwapL ) || | |
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1539 (bol->in(1)->Opcode() == Op_CompareAndSwapP ) || |
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1540 (bol->in(1)->Opcode() == Op_CompareAndSwapN ))) |
0 | 1541 return; // Allocation loops RARELY take backedge |
1542 // Find the OTHER exit path from the IF | |
1543 Node* ex = iff->proj_out(1-test_con); | |
1544 float p = iff->_prob; | |
1545 if( !phase->is_member( this, ex ) && iff->_fcnt == COUNT_UNKNOWN ) { | |
1546 if( top == Op_IfTrue ) { | |
1547 if( p < (PROB_FAIR + PROB_UNLIKELY_MAG(3))) { | |
1548 iff->_prob = PROB_STATIC_FREQUENT; | |
1549 } | |
1550 } else { | |
1551 if( p > (PROB_FAIR - PROB_UNLIKELY_MAG(3))) { | |
1552 iff->_prob = PROB_STATIC_INFREQUENT; | |
1553 } | |
1554 } | |
1555 } | |
1556 } | |
1557 } | |
1558 test = phase->idom(test); | |
1559 } | |
1560 } | |
1561 | |
1562 | |
1563 //------------------------------policy_do_remove_empty_loop-------------------- | |
1564 // Micro-benchmark spamming. Policy is to always remove empty loops. | |
1565 // The 'DO' part is to replace the trip counter with the value it will | |
1566 // have on the last iteration. This will break the loop. | |
1567 bool IdealLoopTree::policy_do_remove_empty_loop( PhaseIdealLoop *phase ) { | |
1568 // Minimum size must be empty loop | |
1569 if( _body.size() > 7/*number of nodes in an empty loop*/ ) return false; | |
1570 | |
1571 if( !_head->is_CountedLoop() ) return false; // Dead loop | |
1572 CountedLoopNode *cl = _head->as_CountedLoop(); | |
1573 if( !cl->loopexit() ) return false; // Malformed loop | |
1574 if( !phase->is_member(this,phase->get_ctrl(cl->loopexit()->in(CountedLoopEndNode::TestValue)) ) ) | |
1575 return false; // Infinite loop | |
1576 #ifndef PRODUCT | |
1577 if( PrintOpto ) | |
1578 tty->print_cr("Removing empty loop"); | |
1579 #endif | |
1580 #ifdef ASSERT | |
1581 // Ensure only one phi which is the iv. | |
1582 Node* iv = NULL; | |
1583 for (DUIterator_Fast imax, i = cl->fast_outs(imax); i < imax; i++) { | |
1584 Node* n = cl->fast_out(i); | |
1585 if (n->Opcode() == Op_Phi) { | |
1586 assert(iv == NULL, "Too many phis" ); | |
1587 iv = n; | |
1588 } | |
1589 } | |
1590 assert(iv == cl->phi(), "Wrong phi" ); | |
1591 #endif | |
1592 // Replace the phi at loop head with the final value of the last | |
1593 // iteration. Then the CountedLoopEnd will collapse (backedge never | |
1594 // taken) and all loop-invariant uses of the exit values will be correct. | |
1595 Node *phi = cl->phi(); | |
1596 Node *final = new (phase->C, 3) SubINode( cl->limit(), cl->stride() ); | |
1597 phase->register_new_node(final,cl->in(LoopNode::EntryControl)); | |
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1598 phase->_igvn.replace_node(phi,final); |
0 | 1599 phase->C->set_major_progress(); |
1600 return true; | |
1601 } | |
1602 | |
1603 | |
1604 //============================================================================= | |
1605 //------------------------------iteration_split_impl--------------------------- | |
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1606 bool IdealLoopTree::iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new ) { |
0 | 1607 // Check and remove empty loops (spam micro-benchmarks) |
1608 if( policy_do_remove_empty_loop(phase) ) | |
1172 | 1609 return true; // Here we removed an empty loop |
0 | 1610 |
1611 bool should_peel = policy_peeling(phase); // Should we peel? | |
1612 | |
1613 bool should_unswitch = policy_unswitching(phase); | |
1614 | |
1615 // Non-counted loops may be peeled; exactly 1 iteration is peeled. | |
1616 // This removes loop-invariant tests (usually null checks). | |
1617 if( !_head->is_CountedLoop() ) { // Non-counted loop | |
1618 if (PartialPeelLoop && phase->partial_peel(this, old_new)) { | |
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1619 // Partial peel succeeded so terminate this round of loop opts |
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1620 return false; |
0 | 1621 } |
1622 if( should_peel ) { // Should we peel? | |
1623 #ifndef PRODUCT | |
1624 if (PrintOpto) tty->print_cr("should_peel"); | |
1625 #endif | |
1626 phase->do_peeling(this,old_new); | |
1627 } else if( should_unswitch ) { | |
1628 phase->do_unswitching(this, old_new); | |
1629 } | |
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1630 return true; |
0 | 1631 } |
1632 CountedLoopNode *cl = _head->as_CountedLoop(); | |
1633 | |
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1634 if( !cl->loopexit() ) return true; // Ignore various kinds of broken loops |
0 | 1635 |
1636 // Do nothing special to pre- and post- loops | |
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1637 if( cl->is_pre_loop() || cl->is_post_loop() ) return true; |
0 | 1638 |
1639 // Compute loop trip count from profile data | |
1640 compute_profile_trip_cnt(phase); | |
1641 | |
1642 // Before attempting fancy unrolling, RCE or alignment, see if we want | |
1643 // to completely unroll this loop or do loop unswitching. | |
1644 if( cl->is_normal_loop() ) { | |
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1645 if (should_unswitch) { |
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1646 phase->do_unswitching(this, old_new); |
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1647 return true; |
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1648 } |
0 | 1649 bool should_maximally_unroll = policy_maximally_unroll(phase); |
1650 if( should_maximally_unroll ) { | |
1651 // Here we did some unrolling and peeling. Eventually we will | |
1652 // completely unroll this loop and it will no longer be a loop. | |
1653 phase->do_maximally_unroll(this,old_new); | |
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1654 return true; |
0 | 1655 } |
1656 } | |
1657 | |
1658 | |
1659 // Counted loops may be peeled, may need some iterations run up | |
1660 // front for RCE, and may want to align loop refs to a cache | |
1661 // line. Thus we clone a full loop up front whose trip count is | |
1662 // at least 1 (if peeling), but may be several more. | |
1663 | |
1664 // The main loop will start cache-line aligned with at least 1 | |
1665 // iteration of the unrolled body (zero-trip test required) and | |
1666 // will have some range checks removed. | |
1667 | |
1668 // A post-loop will finish any odd iterations (leftover after | |
1669 // unrolling), plus any needed for RCE purposes. | |
1670 | |
1671 bool should_unroll = policy_unroll(phase); | |
1672 | |
1673 bool should_rce = policy_range_check(phase); | |
1674 | |
1675 bool should_align = policy_align(phase); | |
1676 | |
1677 // If not RCE'ing (iteration splitting) or Aligning, then we do not | |
1678 // need a pre-loop. We may still need to peel an initial iteration but | |
1679 // we will not be needing an unknown number of pre-iterations. | |
1680 // | |
1681 // Basically, if may_rce_align reports FALSE first time through, | |
1682 // we will not be able to later do RCE or Aligning on this loop. | |
1683 bool may_rce_align = !policy_peel_only(phase) || should_rce || should_align; | |
1684 | |
1685 // If we have any of these conditions (RCE, alignment, unrolling) met, then | |
1686 // we switch to the pre-/main-/post-loop model. This model also covers | |
1687 // peeling. | |
1688 if( should_rce || should_align || should_unroll ) { | |
1689 if( cl->is_normal_loop() ) // Convert to 'pre/main/post' loops | |
1690 phase->insert_pre_post_loops(this,old_new, !may_rce_align); | |
1691 | |
1692 // Adjust the pre- and main-loop limits to let the pre and post loops run | |
1693 // with full checks, but the main-loop with no checks. Remove said | |
1694 // checks from the main body. | |
1695 if( should_rce ) | |
1696 phase->do_range_check(this,old_new); | |
1697 | |
1698 // Double loop body for unrolling. Adjust the minimum-trip test (will do | |
1699 // twice as many iterations as before) and the main body limit (only do | |
1700 // an even number of trips). If we are peeling, we might enable some RCE | |
1701 // and we'd rather unroll the post-RCE'd loop SO... do not unroll if | |
1702 // peeling. | |
1172 | 1703 if( should_unroll && !should_peel ) |
1704 phase->do_unroll(this,old_new, true); | |
0 | 1705 |
1706 // Adjust the pre-loop limits to align the main body | |
1707 // iterations. | |
1708 if( should_align ) | |
1709 Unimplemented(); | |
1710 | |
1711 } else { // Else we have an unchanged counted loop | |
1712 if( should_peel ) // Might want to peel but do nothing else | |
1713 phase->do_peeling(this,old_new); | |
1714 } | |
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1715 return true; |
0 | 1716 } |
1717 | |
1718 | |
1719 //============================================================================= | |
1720 //------------------------------iteration_split-------------------------------- | |
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1721 bool IdealLoopTree::iteration_split( PhaseIdealLoop *phase, Node_List &old_new ) { |
0 | 1722 // Recursively iteration split nested loops |
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1723 if( _child && !_child->iteration_split( phase, old_new )) |
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1724 return false; |
0 | 1725 |
1726 // Clean out prior deadwood | |
1727 DCE_loop_body(); | |
1728 | |
1729 | |
1730 // Look for loop-exit tests with my 50/50 guesses from the Parsing stage. | |
1731 // Replace with a 1-in-10 exit guess. | |
1732 if( _parent /*not the root loop*/ && | |
1733 !_irreducible && | |
1734 // Also ignore the occasional dead backedge | |
1735 !tail()->is_top() ) { | |
1736 adjust_loop_exit_prob(phase); | |
1737 } | |
1738 | |
1739 | |
1740 // Gate unrolling, RCE and peeling efforts. | |
1741 if( !_child && // If not an inner loop, do not split | |
1742 !_irreducible && | |
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1743 _allow_optimizations && |
0 | 1744 !tail()->is_top() ) { // Also ignore the occasional dead backedge |
1745 if (!_has_call) { | |
1172 | 1746 if (!iteration_split_impl( phase, old_new )) { |
1747 return false; | |
1748 } | |
0 | 1749 } else if (policy_unswitching(phase)) { |
1750 phase->do_unswitching(this, old_new); | |
1751 } | |
1752 } | |
1753 | |
1754 // Minor offset re-organization to remove loop-fallout uses of | |
1755 // trip counter. | |
1756 if( _head->is_CountedLoop() ) phase->reorg_offsets( this ); | |
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1757 if( _next && !_next->iteration_split( phase, old_new )) |
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1758 return false; |
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1759 return true; |
0 | 1760 } |
1172 | 1761 |
1762 //-------------------------------is_uncommon_trap_proj---------------------------- | |
1763 // Return true if proj is the form of "proj->[region->..]call_uct" | |
1764 bool PhaseIdealLoop::is_uncommon_trap_proj(ProjNode* proj, bool must_reason_predicate) { | |
1765 int path_limit = 10; | |
1766 assert(proj, "invalid argument"); | |
1767 Node* out = proj; | |
1768 for (int ct = 0; ct < path_limit; ct++) { | |
1769 out = out->unique_ctrl_out(); | |
1770 if (out == NULL || out->is_Root() || out->is_Start()) | |
1771 return false; | |
1772 if (out->is_CallStaticJava()) { | |
1773 int req = out->as_CallStaticJava()->uncommon_trap_request(); | |
1774 if (req != 0) { | |
1775 Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(req); | |
1776 if (!must_reason_predicate || reason == Deoptimization::Reason_predicate){ | |
1777 return true; | |
1778 } | |
1779 } | |
1780 return false; // don't do further after call | |
1781 } | |
1782 } | |
1783 return false; | |
1784 } | |
1785 | |
1786 //-------------------------------is_uncommon_trap_if_pattern------------------------- | |
1787 // Return true for "if(test)-> proj -> ... | |
1788 // | | |
1789 // V | |
1790 // other_proj->[region->..]call_uct" | |
1791 // | |
1792 // "must_reason_predicate" means the uct reason must be Reason_predicate | |
1793 bool PhaseIdealLoop::is_uncommon_trap_if_pattern(ProjNode *proj, bool must_reason_predicate) { | |
1794 Node *in0 = proj->in(0); | |
1795 if (!in0->is_If()) return false; | |
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1796 // Variation of a dead If node. |
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1797 if (in0->outcnt() < 2) return false; |
1172 | 1798 IfNode* iff = in0->as_If(); |
1799 | |
1800 // we need "If(Conv2B(Opaque1(...)))" pattern for must_reason_predicate | |
1801 if (must_reason_predicate) { | |
1802 if (iff->in(1)->Opcode() != Op_Conv2B || | |
1803 iff->in(1)->in(1)->Opcode() != Op_Opaque1) { | |
1804 return false; | |
1805 } | |
1806 } | |
1807 | |
1808 ProjNode* other_proj = iff->proj_out(1-proj->_con)->as_Proj(); | |
1809 return is_uncommon_trap_proj(other_proj, must_reason_predicate); | |
1810 } | |
1811 | |
1812 //------------------------------create_new_if_for_predicate------------------------ | |
1813 // create a new if above the uct_if_pattern for the predicate to be promoted. | |
1814 // | |
1815 // before after | |
1816 // ---------- ---------- | |
1817 // ctrl ctrl | |
1818 // | | | |
1819 // | | | |
1820 // v v | |
1821 // iff new_iff | |
1822 // / \ / \ | |
1823 // / \ / \ | |
1824 // v v v v | |
1825 // uncommon_proj cont_proj if_uct if_cont | |
1826 // \ | | | | | |
1827 // \ | | | | | |
1828 // v v v | v | |
1829 // rgn loop | iff | |
1830 // | | / \ | |
1831 // | | / \ | |
1832 // v | v v | |
1833 // uncommon_trap | uncommon_proj cont_proj | |
1834 // \ \ | | | |
1835 // \ \ | | | |
1836 // v v v v | |
1837 // rgn loop | |
1838 // | | |
1839 // | | |
1840 // v | |
1841 // uncommon_trap | |
1842 // | |
1843 // | |
1844 // We will create a region to guard the uct call if there is no one there. | |
1845 // The true projecttion (if_cont) of the new_iff is returned. | |
1846 ProjNode* PhaseIdealLoop::create_new_if_for_predicate(ProjNode* cont_proj) { | |
1847 assert(is_uncommon_trap_if_pattern(cont_proj, true), "must be a uct if pattern!"); | |
1848 IfNode* iff = cont_proj->in(0)->as_If(); | |
1849 | |
1850 ProjNode *uncommon_proj = iff->proj_out(1 - cont_proj->_con); | |
1851 Node *rgn = uncommon_proj->unique_ctrl_out(); | |
1852 assert(rgn->is_Region() || rgn->is_Call(), "must be a region or call uct"); | |
1853 | |
1854 if (!rgn->is_Region()) { // create a region to guard the call | |
1855 assert(rgn->is_Call(), "must be call uct"); | |
1856 CallNode* call = rgn->as_Call(); | |
1857 rgn = new (C, 1) RegionNode(1); | |
1858 _igvn.set_type(rgn, rgn->bottom_type()); | |
1859 rgn->add_req(uncommon_proj); | |
1860 set_idom(rgn, idom(uncommon_proj), dom_depth(uncommon_proj)+1); | |
1861 _igvn.hash_delete(call); | |
1862 call->set_req(0, rgn); | |
1863 } | |
1864 | |
1865 // Create new_iff | |
1866 uint iffdd = dom_depth(iff); | |
1867 IdealLoopTree* lp = get_loop(iff); | |
1868 IfNode *new_iff = new (C, 2) IfNode(iff->in(0), NULL, iff->_prob, iff->_fcnt); | |
1869 register_node(new_iff, lp, idom(iff), iffdd); | |
1870 Node *if_cont = new (C, 1) IfTrueNode(new_iff); | |
1871 Node *if_uct = new (C, 1) IfFalseNode(new_iff); | |
1872 if (cont_proj->is_IfFalse()) { | |
1873 // Swap | |
1874 Node* tmp = if_uct; if_uct = if_cont; if_cont = tmp; | |
1875 } | |
1876 register_node(if_cont, lp, new_iff, iffdd); | |
1877 register_node(if_uct, get_loop(rgn), new_iff, iffdd); | |
1878 | |
1879 // if_cont to iff | |
1880 _igvn.hash_delete(iff); | |
1881 iff->set_req(0, if_cont); | |
1882 set_idom(iff, if_cont, dom_depth(iff)); | |
1883 | |
1884 // if_uct to rgn | |
1885 _igvn.hash_delete(rgn); | |
1886 rgn->add_req(if_uct); | |
1887 Node* ridom = idom(rgn); | |
1888 Node* nrdom = dom_lca(ridom, new_iff); | |
1889 set_idom(rgn, nrdom, dom_depth(rgn)); | |
1890 | |
1891 // rgn must have no phis | |
1892 assert(!rgn->as_Region()->has_phi(), "region must have no phis"); | |
1893 | |
1894 return if_cont->as_Proj(); | |
1895 } | |
1896 | |
1897 //------------------------------find_predicate_insertion_point-------------------------- | |
1898 // Find a good location to insert a predicate | |
1899 ProjNode* PhaseIdealLoop::find_predicate_insertion_point(Node* start_c) { | |
1900 if (start_c == C->root() || !start_c->is_Proj()) | |
1901 return NULL; | |
1902 if (is_uncommon_trap_if_pattern(start_c->as_Proj(), true/*Reason_Predicate*/)) { | |
1903 return start_c->as_Proj(); | |
1904 } | |
1905 return NULL; | |
1906 } | |
1907 | |
1908 //------------------------------Invariance----------------------------------- | |
1909 // Helper class for loop_predication_impl to compute invariance on the fly and | |
1910 // clone invariants. | |
1911 class Invariance : public StackObj { | |
1912 VectorSet _visited, _invariant; | |
1913 Node_Stack _stack; | |
1914 VectorSet _clone_visited; | |
1915 Node_List _old_new; // map of old to new (clone) | |
1916 IdealLoopTree* _lpt; | |
1917 PhaseIdealLoop* _phase; | |
1918 | |
1919 // Helper function to set up the invariance for invariance computation | |
1920 // If n is a known invariant, set up directly. Otherwise, look up the | |
1921 // the possibility to push n onto the stack for further processing. | |
1922 void visit(Node* use, Node* n) { | |
1923 if (_lpt->is_invariant(n)) { // known invariant | |
1924 _invariant.set(n->_idx); | |
1925 } else if (!n->is_CFG()) { | |
1926 Node *n_ctrl = _phase->ctrl_or_self(n); | |
1927 Node *u_ctrl = _phase->ctrl_or_self(use); // self if use is a CFG | |
1928 if (_phase->is_dominator(n_ctrl, u_ctrl)) { | |
1929 _stack.push(n, n->in(0) == NULL ? 1 : 0); | |
1930 } | |
1931 } | |
1932 } | |
1933 | |
1934 // Compute invariance for "the_node" and (possibly) all its inputs recursively | |
1935 // on the fly | |
1936 void compute_invariance(Node* n) { | |
1937 assert(_visited.test(n->_idx), "must be"); | |
1938 visit(n, n); | |
1939 while (_stack.is_nonempty()) { | |
1940 Node* n = _stack.node(); | |
1941 uint idx = _stack.index(); | |
1942 if (idx == n->req()) { // all inputs are processed | |
1943 _stack.pop(); | |
1944 // n is invariant if it's inputs are all invariant | |
1945 bool all_inputs_invariant = true; | |
1946 for (uint i = 0; i < n->req(); i++) { | |
1947 Node* in = n->in(i); | |
1948 if (in == NULL) continue; | |
1949 assert(_visited.test(in->_idx), "must have visited input"); | |
1950 if (!_invariant.test(in->_idx)) { // bad guy | |
1951 all_inputs_invariant = false; | |
1952 break; | |
1953 } | |
1954 } | |
1955 if (all_inputs_invariant) { | |
1956 _invariant.set(n->_idx); // I am a invariant too | |
1957 } | |
1958 } else { // process next input | |
1959 _stack.set_index(idx + 1); | |
1960 Node* m = n->in(idx); | |
1961 if (m != NULL && !_visited.test_set(m->_idx)) { | |
1962 visit(n, m); | |
1963 } | |
1964 } | |
1965 } | |
1966 } | |
1967 | |
1968 // Helper function to set up _old_new map for clone_nodes. | |
1969 // If n is a known invariant, set up directly ("clone" of n == n). | |
1970 // Otherwise, push n onto the stack for real cloning. | |
1971 void clone_visit(Node* n) { | |
1972 assert(_invariant.test(n->_idx), "must be invariant"); | |
1973 if (_lpt->is_invariant(n)) { // known invariant | |
1974 _old_new.map(n->_idx, n); | |
1975 } else{ // to be cloned | |
1976 assert (!n->is_CFG(), "should not see CFG here"); | |
1977 _stack.push(n, n->in(0) == NULL ? 1 : 0); | |
1978 } | |
1979 } | |
1980 | |
1981 // Clone "n" and (possibly) all its inputs recursively | |
1982 void clone_nodes(Node* n, Node* ctrl) { | |
1983 clone_visit(n); | |
1984 while (_stack.is_nonempty()) { | |
1985 Node* n = _stack.node(); | |
1986 uint idx = _stack.index(); | |
1987 if (idx == n->req()) { // all inputs processed, clone n! | |
1988 _stack.pop(); | |
1989 // clone invariant node | |
1990 Node* n_cl = n->clone(); | |
1991 _old_new.map(n->_idx, n_cl); | |
1992 _phase->register_new_node(n_cl, ctrl); | |
1993 for (uint i = 0; i < n->req(); i++) { | |
1994 Node* in = n_cl->in(i); | |
1995 if (in == NULL) continue; | |
1996 n_cl->set_req(i, _old_new[in->_idx]); | |
1997 } | |
1998 } else { // process next input | |
1999 _stack.set_index(idx + 1); | |
2000 Node* m = n->in(idx); | |
2001 if (m != NULL && !_clone_visited.test_set(m->_idx)) { | |
2002 clone_visit(m); // visit the input | |
2003 } | |
2004 } | |
2005 } | |
2006 } | |
2007 | |
2008 public: | |
2009 Invariance(Arena* area, IdealLoopTree* lpt) : | |
2010 _lpt(lpt), _phase(lpt->_phase), | |
2011 _visited(area), _invariant(area), _stack(area, 10 /* guess */), | |
2012 _clone_visited(area), _old_new(area) | |
2013 {} | |
2014 | |
2015 // Map old to n for invariance computation and clone | |
2016 void map_ctrl(Node* old, Node* n) { | |
2017 assert(old->is_CFG() && n->is_CFG(), "must be"); | |
2018 _old_new.map(old->_idx, n); // "clone" of old is n | |
2019 _invariant.set(old->_idx); // old is invariant | |
2020 _clone_visited.set(old->_idx); | |
2021 } | |
2022 | |
2023 // Driver function to compute invariance | |
2024 bool is_invariant(Node* n) { | |
2025 if (!_visited.test_set(n->_idx)) | |
2026 compute_invariance(n); | |
2027 return (_invariant.test(n->_idx) != 0); | |
2028 } | |
2029 | |
2030 // Driver function to clone invariant | |
2031 Node* clone(Node* n, Node* ctrl) { | |
2032 assert(ctrl->is_CFG(), "must be"); | |
2033 assert(_invariant.test(n->_idx), "must be an invariant"); | |
2034 if (!_clone_visited.test(n->_idx)) | |
2035 clone_nodes(n, ctrl); | |
2036 return _old_new[n->_idx]; | |
2037 } | |
2038 }; | |
2039 | |
2040 //------------------------------is_range_check_if ----------------------------------- | |
2041 // Returns true if the predicate of iff is in "scale*iv + offset u< load_range(ptr)" format | |
2042 // Note: this function is particularly designed for loop predication. We require load_range | |
2043 // and offset to be loop invariant computed on the fly by "invar" | |
2044 bool IdealLoopTree::is_range_check_if(IfNode *iff, PhaseIdealLoop *phase, Invariance& invar) const { | |
2045 if (!is_loop_exit(iff)) { | |
2046 return false; | |
2047 } | |
2048 if (!iff->in(1)->is_Bool()) { | |
2049 return false; | |
2050 } | |
2051 const BoolNode *bol = iff->in(1)->as_Bool(); | |
2052 if (bol->_test._test != BoolTest::lt) { | |
2053 return false; | |
2054 } | |
2055 if (!bol->in(1)->is_Cmp()) { | |
2056 return false; | |
2057 } | |
2058 const CmpNode *cmp = bol->in(1)->as_Cmp(); | |
2059 if (cmp->Opcode() != Op_CmpU ) { | |
2060 return false; | |
2061 } | |
1763 | 2062 Node* range = cmp->in(2); |
2063 if (range->Opcode() != Op_LoadRange) { | |
2064 const TypeInt* tint = phase->_igvn.type(range)->isa_int(); | |
2065 if (!OptimizeFill || tint == NULL || tint->empty() || tint->_lo < 0) { | |
2066 // Allow predication on positive values that aren't LoadRanges. | |
2067 // This allows optimization of loops where the length of the | |
2068 // array is a known value and doesn't need to be loaded back | |
2069 // from the array. | |
2070 return false; | |
2071 } | |
1172 | 2072 } |
1763 | 2073 if (!invar.is_invariant(range)) { |
1172 | 2074 return false; |
2075 } | |
2076 Node *iv = _head->as_CountedLoop()->phi(); | |
2077 int scale = 0; | |
2078 Node *offset = NULL; | |
2079 if (!phase->is_scaled_iv_plus_offset(cmp->in(1), iv, &scale, &offset)) { | |
2080 return false; | |
2081 } | |
2082 if(offset && !invar.is_invariant(offset)) { // offset must be invariant | |
2083 return false; | |
2084 } | |
2085 return true; | |
2086 } | |
2087 | |
2088 //------------------------------rc_predicate----------------------------------- | |
2089 // Create a range check predicate | |
2090 // | |
2091 // for (i = init; i < limit; i += stride) { | |
2092 // a[scale*i+offset] | |
2093 // } | |
2094 // | |
2095 // Compute max(scale*i + offset) for init <= i < limit and build the predicate | |
2096 // as "max(scale*i + offset) u< a.length". | |
2097 // | |
2098 // There are two cases for max(scale*i + offset): | |
2099 // (1) stride*scale > 0 | |
2100 // max(scale*i + offset) = scale*(limit-stride) + offset | |
2101 // (2) stride*scale < 0 | |
2102 // max(scale*i + offset) = scale*init + offset | |
2103 BoolNode* PhaseIdealLoop::rc_predicate(Node* ctrl, | |
2104 int scale, Node* offset, | |
2105 Node* init, Node* limit, Node* stride, | |
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2106 Node* range, bool upper) { |
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2107 DEBUG_ONLY(ttyLocker ttyl); |
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2108 if (TraceLoopPredicate) tty->print("rc_predicate "); |
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2109 |
1172 | 2110 Node* max_idx_expr = init; |
2111 int stride_con = stride->get_int(); | |
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2112 if ((stride_con > 0) == (scale > 0) == upper) { |
1172 | 2113 max_idx_expr = new (C, 3) SubINode(limit, stride); |
2114 register_new_node(max_idx_expr, ctrl); | |
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2115 if (TraceLoopPredicate) tty->print("(limit - stride) "); |
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2116 } else { |
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2117 if (TraceLoopPredicate) tty->print("init "); |
1172 | 2118 } |
2119 | |
2120 if (scale != 1) { | |
2121 ConNode* con_scale = _igvn.intcon(scale); | |
2122 max_idx_expr = new (C, 3) MulINode(max_idx_expr, con_scale); | |
2123 register_new_node(max_idx_expr, ctrl); | |
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2124 if (TraceLoopPredicate) tty->print("* %d ", scale); |
1172 | 2125 } |
2126 | |
2127 if (offset && (!offset->is_Con() || offset->get_int() != 0)){ | |
2128 max_idx_expr = new (C, 3) AddINode(max_idx_expr, offset); | |
2129 register_new_node(max_idx_expr, ctrl); | |
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2130 if (TraceLoopPredicate) |
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2131 if (offset->is_Con()) tty->print("+ %d ", offset->get_int()); |
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2132 else tty->print("+ offset "); |
1172 | 2133 } |
2134 | |
2135 CmpUNode* cmp = new (C, 3) CmpUNode(max_idx_expr, range); | |
2136 register_new_node(cmp, ctrl); | |
2137 BoolNode* bol = new (C, 2) BoolNode(cmp, BoolTest::lt); | |
2138 register_new_node(bol, ctrl); | |
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2139 |
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2140 if (TraceLoopPredicate) tty->print_cr("<u range"); |
1172 | 2141 return bol; |
2142 } | |
2143 | |
2144 //------------------------------ loop_predication_impl-------------------------- | |
2145 // Insert loop predicates for null checks and range checks | |
2146 bool PhaseIdealLoop::loop_predication_impl(IdealLoopTree *loop) { | |
2147 if (!UseLoopPredicate) return false; | |
2148 | |
1275 | 2149 if (!loop->_head->is_Loop()) { |
2150 // Could be a simple region when irreducible loops are present. | |
2151 return false; | |
2152 } | |
2153 | |
2154 CountedLoopNode *cl = NULL; | |
2155 if (loop->_head->is_CountedLoop()) { | |
2156 cl = loop->_head->as_CountedLoop(); | |
2157 // do nothing for iteration-splitted loops | |
2158 if (!cl->is_normal_loop()) return false; | |
2159 } | |
2160 | |
1172 | 2161 // Too many traps seen? |
2162 bool tmt = C->too_many_traps(C->method(), 0, Deoptimization::Reason_predicate); | |
2163 int tc = C->trap_count(Deoptimization::Reason_predicate); | |
2164 if (tmt || tc > 0) { | |
2165 if (TraceLoopPredicate) { | |
2166 tty->print_cr("too many predicate traps: %d", tc); | |
2167 C->method()->print(); // which method has too many predicate traps | |
2168 tty->print_cr(""); | |
2169 } | |
2170 return false; | |
2171 } | |
2172 | |
2173 LoopNode *lpn = loop->_head->as_Loop(); | |
2174 Node* entry = lpn->in(LoopNode::EntryControl); | |
2175 | |
2176 ProjNode *predicate_proj = find_predicate_insertion_point(entry); | |
2177 if (!predicate_proj){ | |
2178 #ifndef PRODUCT | |
2179 if (TraceLoopPredicate) { | |
2180 tty->print("missing predicate:"); | |
2181 loop->dump_head(); | |
2182 } | |
2183 #endif | |
2184 return false; | |
2185 } | |
2186 | |
2187 ConNode* zero = _igvn.intcon(0); | |
2188 set_ctrl(zero, C->root()); | |
2189 Node *cond_false = new (C, 2) Conv2BNode(zero); | |
2190 register_new_node(cond_false, C->root()); | |
2191 ConNode* one = _igvn.intcon(1); | |
2192 set_ctrl(one, C->root()); | |
2193 Node *cond_true = new (C, 2) Conv2BNode(one); | |
2194 register_new_node(cond_true, C->root()); | |
2195 | |
2196 ResourceArea *area = Thread::current()->resource_area(); | |
2197 Invariance invar(area, loop); | |
2198 | |
2199 // Create list of if-projs such that a newer proj dominates all older | |
2200 // projs in the list, and they all dominate loop->tail() | |
2201 Node_List if_proj_list(area); | |
2202 LoopNode *head = loop->_head->as_Loop(); | |
2203 Node *current_proj = loop->tail(); //start from tail | |
2204 while ( current_proj != head ) { | |
2205 if (loop == get_loop(current_proj) && // still in the loop ? | |
2206 current_proj->is_Proj() && // is a projection ? | |
2207 current_proj->in(0)->Opcode() == Op_If) { // is a if projection ? | |
2208 if_proj_list.push(current_proj); | |
2209 } | |
2210 current_proj = idom(current_proj); | |
2211 } | |
2212 | |
2213 bool hoisted = false; // true if at least one proj is promoted | |
2214 while (if_proj_list.size() > 0) { | |
2215 // Following are changed to nonnull when a predicate can be hoisted | |
2216 ProjNode* new_predicate_proj = NULL; | |
2217 | |
2218 ProjNode* proj = if_proj_list.pop()->as_Proj(); | |
2219 IfNode* iff = proj->in(0)->as_If(); | |
2220 | |
2221 if (!is_uncommon_trap_if_pattern(proj)) { | |
2222 if (loop->is_loop_exit(iff)) { | |
2223 // stop processing the remaining projs in the list because the execution of them | |
2224 // depends on the condition of "iff" (iff->in(1)). | |
2225 break; | |
2226 } else { | |
2227 // Both arms are inside the loop. There are two cases: | |
2228 // (1) there is one backward branch. In this case, any remaining proj | |
2229 // in the if_proj list post-dominates "iff". So, the condition of "iff" | |
2230 // does not determine the execution the remining projs directly, and we | |
2231 // can safely continue. | |
2232 // (2) both arms are forwarded, i.e. a diamond shape. In this case, "proj" | |
2233 // does not dominate loop->tail(), so it can not be in the if_proj list. | |
2234 continue; | |
2235 } | |
2236 } | |
2237 | |
2238 Node* test = iff->in(1); | |
2239 if (!test->is_Bool()){ //Conv2B, ... | |
2240 continue; | |
2241 } | |
2242 BoolNode* bol = test->as_Bool(); | |
2243 if (invar.is_invariant(bol)) { | |
2244 // Invariant test | |
2245 new_predicate_proj = create_new_if_for_predicate(predicate_proj); | |
2246 Node* ctrl = new_predicate_proj->in(0)->as_If()->in(0); | |
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2247 BoolNode* new_predicate_bol = invar.clone(bol, ctrl)->as_Bool(); |
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2248 |
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|
2249 // Negate test if necessary |
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|
2250 bool negated = false; |
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2251 if (proj->_con != predicate_proj->_con) { |
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|
2252 new_predicate_bol = new (C, 2) BoolNode(new_predicate_bol->in(1), new_predicate_bol->_test.negate()); |
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|
2253 register_new_node(new_predicate_bol, ctrl); |
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|
2254 negated = true; |
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2255 } |
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2256 IfNode* new_predicate_iff = new_predicate_proj->in(0)->as_If(); |
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2257 _igvn.hash_delete(new_predicate_iff); |
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2258 new_predicate_iff->set_req(1, new_predicate_bol); |
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2259 if (TraceLoopPredicate) tty->print_cr("invariant if%s: %d", negated ? " negated" : "", new_predicate_iff->_idx); |
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2260 |
1172 | 2261 } else if (cl != NULL && loop->is_range_check_if(iff, this, invar)) { |
1303
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2262 assert(proj->_con == predicate_proj->_con, "must match"); |
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2263 |
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2264 // Range check for counted loops |
1172 | 2265 const Node* cmp = bol->in(1)->as_Cmp(); |
2266 Node* idx = cmp->in(1); | |
2267 assert(!invar.is_invariant(idx), "index is variant"); | |
1763 | 2268 assert(cmp->in(2)->Opcode() == Op_LoadRange || OptimizeFill, "must be"); |
2269 Node* rng = cmp->in(2); | |
2270 assert(invar.is_invariant(rng), "range must be invariant"); | |
1172 | 2271 int scale = 1; |
2272 Node* offset = zero; | |
2273 bool ok = is_scaled_iv_plus_offset(idx, cl->phi(), &scale, &offset); | |
2274 assert(ok, "must be index expression"); | |
1303
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2275 |
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2276 Node* init = cl->init_trip(); |
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2277 Node* limit = cl->limit(); |
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2278 Node* stride = cl->stride(); |
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2279 |
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2280 // Build if's for the upper and lower bound tests. The |
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2281 // lower_bound test will dominate the upper bound test and all |
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2282 // cloned or created nodes will use the lower bound test as |
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2283 // their declared control. |
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2284 ProjNode* lower_bound_proj = create_new_if_for_predicate(predicate_proj); |
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2285 ProjNode* upper_bound_proj = create_new_if_for_predicate(predicate_proj); |
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2286 assert(upper_bound_proj->in(0)->as_If()->in(0) == lower_bound_proj, "should dominate"); |
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2287 Node *ctrl = lower_bound_proj->in(0)->as_If()->in(0); |
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2288 |
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2289 // Perform cloning to keep Invariance state correct since the |
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2290 // late schedule will place invariant things in the loop. |
1763 | 2291 rng = invar.clone(rng, ctrl); |
1172 | 2292 if (offset && offset != zero) { |
2293 assert(invar.is_invariant(offset), "offset must be loop invariant"); | |
2294 offset = invar.clone(offset, ctrl); | |
2295 } | |
1303
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2296 |
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2297 // Test the lower bound |
1763 | 2298 Node* lower_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, rng, false); |
1303
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2299 IfNode* lower_bound_iff = lower_bound_proj->in(0)->as_If(); |
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2300 _igvn.hash_delete(lower_bound_iff); |
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2301 lower_bound_iff->set_req(1, lower_bound_bol); |
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2302 if (TraceLoopPredicate) tty->print_cr("lower bound check if: %d", lower_bound_iff->_idx); |
1172 | 2303 |
1303
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2304 // Test the upper bound |
1763 | 2305 Node* upper_bound_bol = rc_predicate(ctrl, scale, offset, init, limit, stride, rng, true); |
1303
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2306 IfNode* upper_bound_iff = upper_bound_proj->in(0)->as_If(); |
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2307 _igvn.hash_delete(upper_bound_iff); |
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2308 upper_bound_iff->set_req(1, upper_bound_bol); |
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2309 if (TraceLoopPredicate) tty->print_cr("upper bound check if: %d", lower_bound_iff->_idx); |
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2310 |
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2311 // Fall through into rest of the clean up code which will move |
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2312 // any dependent nodes onto the upper bound test. |
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2313 new_predicate_proj = upper_bound_proj; |
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2314 } else { |
1172 | 2315 // The other proj of the "iff" is a uncommon trap projection, and we can assume |
2316 // the other proj will not be executed ("executed" means uct raised). | |
2317 continue; | |
1303
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2318 } |
1172 | 2319 |
1303
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2320 // Success - attach condition (new_predicate_bol) to predicate if |
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2321 invar.map_ctrl(proj, new_predicate_proj); // so that invariance test can be appropriate |
1172 | 2322 |
1303
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2323 // Eliminate the old if in the loop body |
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2324 _igvn.hash_delete(iff); |
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2325 iff->set_req(1, proj->is_IfFalse() ? cond_false : cond_true); |
1172 | 2326 |
1303
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2327 Node* ctrl = new_predicate_proj; // new control |
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2328 ProjNode* dp = proj; // old control |
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2329 assert(get_loop(dp) == loop, "guaranteed at the time of collecting proj"); |
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2330 // Find nodes (depends only on the test) off the surviving projection; |
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2331 // move them outside the loop with the control of proj_clone |
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2332 for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) { |
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2333 Node* cd = dp->fast_out(i); // Control-dependent node |
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2334 if (cd->depends_only_on_test()) { |
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2335 assert(cd->in(0) == dp, ""); |
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2336 _igvn.hash_delete(cd); |
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2337 cd->set_req(0, ctrl); // ctrl, not NULL |
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2338 set_early_ctrl(cd); |
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2339 _igvn._worklist.push(cd); |
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2340 IdealLoopTree *new_loop = get_loop(get_ctrl(cd)); |
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2341 if (new_loop != loop) { |
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2342 if (!loop->_child) loop->_body.yank(cd); |
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2343 if (!new_loop->_child ) new_loop->_body.push(cd); |
1172 | 2344 } |
1303
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2345 --i; |
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2346 --imax; |
1172 | 2347 } |
1303
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2348 } |
1172 | 2349 |
1303
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2350 hoisted = true; |
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2351 C->set_major_progress(); |
1172 | 2352 } // end while |
2353 | |
2354 #ifndef PRODUCT | |
1303
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2355 // report that the loop predication has been actually performed |
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2356 // for this loop |
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2357 if (TraceLoopPredicate && hoisted) { |
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2358 tty->print("Loop Predication Performed:"); |
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2359 loop->dump_head(); |
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2360 } |
1172 | 2361 #endif |
2362 | |
2363 return hoisted; | |
2364 } | |
2365 | |
2366 //------------------------------loop_predication-------------------------------- | |
2367 // driver routine for loop predication optimization | |
2368 bool IdealLoopTree::loop_predication( PhaseIdealLoop *phase) { | |
2369 bool hoisted = false; | |
2370 // Recursively promote predicates | |
2371 if ( _child ) { | |
2372 hoisted = _child->loop_predication( phase); | |
2373 } | |
2374 | |
2375 // self | |
2376 if (!_irreducible && !tail()->is_top()) { | |
2377 hoisted |= phase->loop_predication_impl(this); | |
2378 } | |
2379 | |
2380 if ( _next ) { //sibling | |
2381 hoisted |= _next->loop_predication( phase); | |
2382 } | |
2383 | |
2384 return hoisted; | |
2385 } | |
1763 | 2386 |
2387 | |
2388 // Process all the loops in the loop tree and replace any fill | |
2389 // patterns with an intrisc version. | |
2390 bool PhaseIdealLoop::do_intrinsify_fill() { | |
2391 bool changed = false; | |
2392 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) { | |
2393 IdealLoopTree* lpt = iter.current(); | |
2394 changed |= intrinsify_fill(lpt); | |
2395 } | |
2396 return changed; | |
2397 } | |
2398 | |
2399 | |
2400 // Examine an inner loop looking for a a single store of an invariant | |
2401 // value in a unit stride loop, | |
2402 bool PhaseIdealLoop::match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value, | |
2403 Node*& shift, Node*& con) { | |
2404 const char* msg = NULL; | |
2405 Node* msg_node = NULL; | |
2406 | |
2407 store_value = NULL; | |
2408 con = NULL; | |
2409 shift = NULL; | |
2410 | |
2411 // Process the loop looking for stores. If there are multiple | |
2412 // stores or extra control flow give at this point. | |
2413 CountedLoopNode* head = lpt->_head->as_CountedLoop(); | |
2414 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) { | |
2415 Node* n = lpt->_body.at(i); | |
2416 if (n->outcnt() == 0) continue; // Ignore dead | |
2417 if (n->is_Store()) { | |
2418 if (store != NULL) { | |
2419 msg = "multiple stores"; | |
2420 break; | |
2421 } | |
2422 int opc = n->Opcode(); | |
2423 if (opc == Op_StoreP || opc == Op_StoreN || opc == Op_StoreCM) { | |
2424 msg = "oop fills not handled"; | |
2425 break; | |
2426 } | |
2427 Node* value = n->in(MemNode::ValueIn); | |
2428 if (!lpt->is_invariant(value)) { | |
2429 msg = "variant store value"; | |
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2430 } else if (!_igvn.type(n->in(MemNode::Address))->isa_aryptr()) { |
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2431 msg = "not array address"; |
1763 | 2432 } |
2433 store = n; | |
2434 store_value = value; | |
2435 } else if (n->is_If() && n != head->loopexit()) { | |
2436 msg = "extra control flow"; | |
2437 msg_node = n; | |
2438 } | |
2439 } | |
2440 | |
2441 if (store == NULL) { | |
2442 // No store in loop | |
2443 return false; | |
2444 } | |
2445 | |
2446 if (msg == NULL && head->stride_con() != 1) { | |
2447 // could handle negative strides too | |
2448 if (head->stride_con() < 0) { | |
2449 msg = "negative stride"; | |
2450 } else { | |
2451 msg = "non-unit stride"; | |
2452 } | |
2453 } | |
2454 | |
2455 if (msg == NULL && !store->in(MemNode::Address)->is_AddP()) { | |
2456 msg = "can't handle store address"; | |
2457 msg_node = store->in(MemNode::Address); | |
2458 } | |
2459 | |
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2460 if (msg == NULL && |
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2461 (!store->in(MemNode::Memory)->is_Phi() || |
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2462 store->in(MemNode::Memory)->in(LoopNode::LoopBackControl) != store)) { |
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2463 msg = "store memory isn't proper phi"; |
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2464 msg_node = store->in(MemNode::Memory); |
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2465 } |
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2466 |
1763 | 2467 // Make sure there is an appropriate fill routine |
2468 BasicType t = store->as_Mem()->memory_type(); | |
2469 const char* fill_name; | |
2470 if (msg == NULL && | |
2471 StubRoutines::select_fill_function(t, false, fill_name) == NULL) { | |
2472 msg = "unsupported store"; | |
2473 msg_node = store; | |
2474 } | |
2475 | |
2476 if (msg != NULL) { | |
2477 #ifndef PRODUCT | |
2478 if (TraceOptimizeFill) { | |
2479 tty->print_cr("not fill intrinsic candidate: %s", msg); | |
2480 if (msg_node != NULL) msg_node->dump(); | |
2481 } | |
2482 #endif | |
2483 return false; | |
2484 } | |
2485 | |
2486 // Make sure the address expression can be handled. It should be | |
2487 // head->phi * elsize + con. head->phi might have a ConvI2L. | |
2488 Node* elements[4]; | |
2489 Node* conv = NULL; | |
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2490 bool found_index = false; |
1763 | 2491 int count = store->in(MemNode::Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements)); |
2492 for (int e = 0; e < count; e++) { | |
2493 Node* n = elements[e]; | |
2494 if (n->is_Con() && con == NULL) { | |
2495 con = n; | |
2496 } else if (n->Opcode() == Op_LShiftX && shift == NULL) { | |
2497 Node* value = n->in(1); | |
2498 #ifdef _LP64 | |
2499 if (value->Opcode() == Op_ConvI2L) { | |
2500 conv = value; | |
2501 value = value->in(1); | |
2502 } | |
2503 #endif | |
2504 if (value != head->phi()) { | |
2505 msg = "unhandled shift in address"; | |
2506 } else { | |
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2507 found_index = true; |
1763 | 2508 shift = n; |
2509 assert(type2aelembytes(store->as_Mem()->memory_type(), true) == 1 << shift->in(2)->get_int(), "scale should match"); | |
2510 } | |
2511 } else if (n->Opcode() == Op_ConvI2L && conv == NULL) { | |
2512 if (n->in(1) == head->phi()) { | |
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2513 found_index = true; |
1763 | 2514 conv = n; |
2515 } else { | |
2516 msg = "unhandled input to ConvI2L"; | |
2517 } | |
2518 } else if (n == head->phi()) { | |
2519 // no shift, check below for allowed cases | |
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2520 found_index = true; |
1763 | 2521 } else { |
2522 msg = "unhandled node in address"; | |
2523 msg_node = n; | |
2524 } | |
2525 } | |
2526 | |
2527 if (count == -1) { | |
2528 msg = "malformed address expression"; | |
2529 msg_node = store; | |
2530 } | |
2531 | |
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2532 if (!found_index) { |
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2533 msg = "missing use of index"; |
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2534 } |
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2535 |
1763 | 2536 // byte sized items won't have a shift |
2537 if (msg == NULL && shift == NULL && t != T_BYTE && t != T_BOOLEAN) { | |
2538 msg = "can't find shift"; | |
2539 msg_node = store; | |
2540 } | |
2541 | |
2542 if (msg != NULL) { | |
2543 #ifndef PRODUCT | |
2544 if (TraceOptimizeFill) { | |
2545 tty->print_cr("not fill intrinsic: %s", msg); | |
2546 if (msg_node != NULL) msg_node->dump(); | |
2547 } | |
2548 #endif | |
2549 return false; | |
2550 } | |
2551 | |
2552 // No make sure all the other nodes in the loop can be handled | |
2553 VectorSet ok(Thread::current()->resource_area()); | |
2554 | |
2555 // store related values are ok | |
2556 ok.set(store->_idx); | |
2557 ok.set(store->in(MemNode::Memory)->_idx); | |
2558 | |
2559 // Loop structure is ok | |
2560 ok.set(head->_idx); | |
2561 ok.set(head->loopexit()->_idx); | |
2562 ok.set(head->phi()->_idx); | |
2563 ok.set(head->incr()->_idx); | |
2564 ok.set(head->loopexit()->cmp_node()->_idx); | |
2565 ok.set(head->loopexit()->in(1)->_idx); | |
2566 | |
2567 // Address elements are ok | |
2568 if (con) ok.set(con->_idx); | |
2569 if (shift) ok.set(shift->_idx); | |
2570 if (conv) ok.set(conv->_idx); | |
2571 | |
2572 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) { | |
2573 Node* n = lpt->_body.at(i); | |
2574 if (n->outcnt() == 0) continue; // Ignore dead | |
2575 if (ok.test(n->_idx)) continue; | |
2576 // Backedge projection is ok | |
2577 if (n->is_IfTrue() && n->in(0) == head->loopexit()) continue; | |
2578 if (!n->is_AddP()) { | |
2579 msg = "unhandled node"; | |
2580 msg_node = n; | |
2581 break; | |
2582 } | |
2583 } | |
2584 | |
2585 // Make sure no unexpected values are used outside the loop | |
2586 for (uint i = 0; msg == NULL && i < lpt->_body.size(); i++) { | |
2587 Node* n = lpt->_body.at(i); | |
2588 // These values can be replaced with other nodes if they are used | |
2589 // outside the loop. | |
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2590 if (n == store || n == head->loopexit() || n == head->incr() || n == store->in(MemNode::Memory)) continue; |
1763 | 2591 for (SimpleDUIterator iter(n); iter.has_next(); iter.next()) { |
2592 Node* use = iter.get(); | |
2593 if (!lpt->_body.contains(use)) { | |
2594 msg = "node is used outside loop"; | |
2595 // lpt->_body.dump(); | |
2596 msg_node = n; | |
2597 break; | |
2598 } | |
2599 } | |
2600 } | |
2601 | |
2602 #ifdef ASSERT | |
2603 if (TraceOptimizeFill) { | |
2604 if (msg != NULL) { | |
2605 tty->print_cr("no fill intrinsic: %s", msg); | |
2606 if (msg_node != NULL) msg_node->dump(); | |
2607 } else { | |
2608 tty->print_cr("fill intrinsic for:"); | |
2609 } | |
2610 store->dump(); | |
2611 if (Verbose) { | |
2612 lpt->_body.dump(); | |
2613 } | |
2614 } | |
2615 #endif | |
2616 | |
2617 return msg == NULL; | |
2618 } | |
2619 | |
2620 | |
2621 | |
2622 bool PhaseIdealLoop::intrinsify_fill(IdealLoopTree* lpt) { | |
2623 // Only for counted inner loops | |
2624 if (!lpt->is_counted() || !lpt->is_inner()) { | |
2625 return false; | |
2626 } | |
2627 | |
2628 // Must have constant stride | |
2629 CountedLoopNode* head = lpt->_head->as_CountedLoop(); | |
2630 if (!head->stride_is_con() || !head->is_normal_loop()) { | |
2631 return false; | |
2632 } | |
2633 | |
2634 // Check that the body only contains a store of a loop invariant | |
2635 // value that is indexed by the loop phi. | |
2636 Node* store = NULL; | |
2637 Node* store_value = NULL; | |
2638 Node* shift = NULL; | |
2639 Node* offset = NULL; | |
2640 if (!match_fill_loop(lpt, store, store_value, shift, offset)) { | |
2641 return false; | |
2642 } | |
2643 | |
2644 // Now replace the whole loop body by a call to a fill routine that | |
2645 // covers the same region as the loop. | |
2646 Node* base = store->in(MemNode::Address)->as_AddP()->in(AddPNode::Base); | |
2647 | |
2648 // Build an expression for the beginning of the copy region | |
2649 Node* index = head->init_trip(); | |
2650 #ifdef _LP64 | |
2651 index = new (C, 2) ConvI2LNode(index); | |
2652 _igvn.register_new_node_with_optimizer(index); | |
2653 #endif | |
2654 if (shift != NULL) { | |
2655 // byte arrays don't require a shift but others do. | |
2656 index = new (C, 3) LShiftXNode(index, shift->in(2)); | |
2657 _igvn.register_new_node_with_optimizer(index); | |
2658 } | |
2659 index = new (C, 4) AddPNode(base, base, index); | |
2660 _igvn.register_new_node_with_optimizer(index); | |
2661 Node* from = new (C, 4) AddPNode(base, index, offset); | |
2662 _igvn.register_new_node_with_optimizer(from); | |
2663 // Compute the number of elements to copy | |
2664 Node* len = new (C, 3) SubINode(head->limit(), head->init_trip()); | |
2665 _igvn.register_new_node_with_optimizer(len); | |
2666 | |
2667 BasicType t = store->as_Mem()->memory_type(); | |
2668 bool aligned = false; | |
2669 if (offset != NULL && head->init_trip()->is_Con()) { | |
2670 int element_size = type2aelembytes(t); | |
2671 aligned = (offset->find_intptr_t_type()->get_con() + head->init_trip()->get_int() * element_size) % HeapWordSize == 0; | |
2672 } | |
2673 | |
2674 // Build a call to the fill routine | |
2675 const char* fill_name; | |
2676 address fill = StubRoutines::select_fill_function(t, aligned, fill_name); | |
2677 assert(fill != NULL, "what?"); | |
2678 | |
2679 // Convert float/double to int/long for fill routines | |
2680 if (t == T_FLOAT) { | |
2681 store_value = new (C, 2) MoveF2INode(store_value); | |
2682 _igvn.register_new_node_with_optimizer(store_value); | |
2683 } else if (t == T_DOUBLE) { | |
2684 store_value = new (C, 2) MoveD2LNode(store_value); | |
2685 _igvn.register_new_node_with_optimizer(store_value); | |
2686 } | |
2687 | |
2688 Node* mem_phi = store->in(MemNode::Memory); | |
2689 Node* result_ctrl; | |
2690 Node* result_mem; | |
2691 const TypeFunc* call_type = OptoRuntime::array_fill_Type(); | |
2692 int size = call_type->domain()->cnt(); | |
2693 CallLeafNode *call = new (C, size) CallLeafNoFPNode(call_type, fill, | |
2694 fill_name, TypeAryPtr::get_array_body_type(t)); | |
2695 call->init_req(TypeFunc::Parms+0, from); | |
2696 call->init_req(TypeFunc::Parms+1, store_value); | |
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2697 #ifdef _LP64 |
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2698 len = new (C, 2) ConvI2LNode(len); |
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2699 _igvn.register_new_node_with_optimizer(len); |
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2700 #endif |
1763 | 2701 call->init_req(TypeFunc::Parms+2, len); |
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2702 #ifdef _LP64 |
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2703 call->init_req(TypeFunc::Parms+3, C->top()); |
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2704 #endif |
1763 | 2705 call->init_req( TypeFunc::Control, head->init_control()); |
2706 call->init_req( TypeFunc::I_O , C->top() ) ; // does no i/o | |
2707 call->init_req( TypeFunc::Memory , mem_phi->in(LoopNode::EntryControl) ); | |
2708 call->init_req( TypeFunc::ReturnAdr, C->start()->proj_out(TypeFunc::ReturnAdr) ); | |
2709 call->init_req( TypeFunc::FramePtr, C->start()->proj_out(TypeFunc::FramePtr) ); | |
2710 _igvn.register_new_node_with_optimizer(call); | |
2711 result_ctrl = new (C, 1) ProjNode(call,TypeFunc::Control); | |
2712 _igvn.register_new_node_with_optimizer(result_ctrl); | |
2713 result_mem = new (C, 1) ProjNode(call,TypeFunc::Memory); | |
2714 _igvn.register_new_node_with_optimizer(result_mem); | |
2715 | |
2716 // If this fill is tightly coupled to an allocation and overwrites | |
2717 // the whole body, allow it to take over the zeroing. | |
2718 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, this); | |
2719 if (alloc != NULL && alloc->is_AllocateArray()) { | |
2720 Node* length = alloc->as_AllocateArray()->Ideal_length(); | |
2721 if (head->limit() == length && | |
2722 head->init_trip() == _igvn.intcon(0)) { | |
2723 if (TraceOptimizeFill) { | |
2724 tty->print_cr("Eliminated zeroing in allocation"); | |
2725 } | |
2726 alloc->maybe_set_complete(&_igvn); | |
2727 } else { | |
2728 #ifdef ASSERT | |
2729 if (TraceOptimizeFill) { | |
2730 tty->print_cr("filling array but bounds don't match"); | |
2731 alloc->dump(); | |
2732 head->init_trip()->dump(); | |
2733 head->limit()->dump(); | |
2734 length->dump(); | |
2735 } | |
2736 #endif | |
2737 } | |
2738 } | |
2739 | |
2740 // Redirect the old control and memory edges that are outside the loop. | |
2741 Node* exit = head->loopexit()->proj_out(0); | |
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2742 // Sometimes the memory phi of the head is used as the outgoing |
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2743 // state of the loop. It's safe in this case to replace it with the |
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2744 // result_mem. |
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2745 _igvn.replace_node(store->in(MemNode::Memory), result_mem); |
1763 | 2746 _igvn.replace_node(exit, result_ctrl); |
2747 _igvn.replace_node(store, result_mem); | |
2748 // Any uses the increment outside of the loop become the loop limit. | |
2749 _igvn.replace_node(head->incr(), head->limit()); | |
2750 | |
2751 // Disconnect the head from the loop. | |
2752 for (uint i = 0; i < lpt->_body.size(); i++) { | |
2753 Node* n = lpt->_body.at(i); | |
2754 _igvn.replace_node(n, C->top()); | |
2755 } | |
2756 | |
2757 return true; | |
2758 } |