Mercurial > hg > truffle
annotate src/share/vm/opto/split_if.cpp @ 6027:8a2e5a6a19a4
7143490: G1: Remove HeapRegion::_top_at_conc_mark_count
Summary: Removed the HeapRegion::_top_at_conc_mark_count field. It is no longer needed as a result of the changes for 6888336 and 7127706. Refactored the closures that finalize and verify the liveness counting data so that common functionality was placed into a base class.
Reviewed-by: brutisso, tonyp
author | johnc |
---|---|
date | Wed, 25 Apr 2012 10:23:12 -0700 |
parents | 8805f8c1e23e |
children | 5e990493719e |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1999, 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 "memory/allocation.inline.hpp" | |
27 #include "opto/callnode.hpp" | |
28 #include "opto/connode.hpp" | |
29 #include "opto/loopnode.hpp" | |
0 | 30 |
31 | |
32 //------------------------------split_thru_region------------------------------ | |
33 // Split Node 'n' through merge point. | |
34 Node *PhaseIdealLoop::split_thru_region( Node *n, Node *region ) { | |
35 uint wins = 0; | |
36 assert( n->is_CFG(), "" ); | |
37 assert( region->is_Region(), "" ); | |
38 Node *r = new (C, region->req()) RegionNode( region->req() ); | |
39 IdealLoopTree *loop = get_loop( n ); | |
40 for( uint i = 1; i < region->req(); i++ ) { | |
41 Node *x = n->clone(); | |
42 Node *in0 = n->in(0); | |
43 if( in0->in(0) == region ) x->set_req( 0, in0->in(i) ); | |
44 for( uint j = 1; j < n->req(); j++ ) { | |
45 Node *in = n->in(j); | |
46 if( get_ctrl(in) == region ) | |
47 x->set_req( j, in->in(i) ); | |
48 } | |
49 _igvn.register_new_node_with_optimizer(x); | |
50 set_loop(x, loop); | |
51 set_idom(x, x->in(0), dom_depth(x->in(0))+1); | |
52 r->init_req(i, x); | |
53 } | |
54 | |
55 // Record region | |
56 r->set_req(0,region); // Not a TRUE RegionNode | |
57 _igvn.register_new_node_with_optimizer(r); | |
58 set_loop(r, loop); | |
59 if( !loop->_child ) | |
60 loop->_body.push(r); | |
61 return r; | |
62 } | |
63 | |
64 //------------------------------split_up--------------------------------------- | |
65 // Split block-local op up through the phis to empty the current block | |
66 bool PhaseIdealLoop::split_up( Node *n, Node *blk1, Node *blk2 ) { | |
67 if( n->is_CFG() ) { | |
68 assert( n->in(0) != blk1, "Lousy candidate for split-if" ); | |
69 return false; | |
70 } | |
71 if( get_ctrl(n) != blk1 && get_ctrl(n) != blk2 ) | |
72 return false; // Not block local | |
73 if( n->is_Phi() ) return false; // Local PHIs are expected | |
74 | |
75 // Recursively split-up inputs | |
76 for (uint i = 1; i < n->req(); i++) { | |
77 if( split_up( n->in(i), blk1, blk2 ) ) { | |
78 // Got split recursively and self went dead? | |
79 if (n->outcnt() == 0) | |
80 _igvn.remove_dead_node(n); | |
81 return true; | |
82 } | |
83 } | |
84 | |
85 // Check for needing to clone-up a compare. Can't do that, it forces | |
86 // another (nested) split-if transform. Instead, clone it "down". | |
87 if( n->is_Cmp() ) { | |
88 assert(get_ctrl(n) == blk2 || get_ctrl(n) == blk1, "must be in block with IF"); | |
89 // Check for simple Cmp/Bool/CMove which we can clone-up. Cmp/Bool/CMove | |
90 // sequence can have no other users and it must all reside in the split-if | |
91 // block. Non-simple Cmp/Bool/CMove sequences are 'cloned-down' below - | |
92 // private, per-use versions of the Cmp and Bool are made. These sink to | |
93 // the CMove block. If the CMove is in the split-if block, then in the | |
94 // next iteration this will become a simple Cmp/Bool/CMove set to clone-up. | |
95 Node *bol, *cmov; | |
96 if( !(n->outcnt() == 1 && n->unique_out()->is_Bool() && | |
97 (bol = n->unique_out()->as_Bool()) && | |
98 (get_ctrl(bol) == blk1 || | |
99 get_ctrl(bol) == blk2) && | |
100 bol->outcnt() == 1 && | |
101 bol->unique_out()->is_CMove() && | |
102 (cmov = bol->unique_out()->as_CMove()) && | |
103 (get_ctrl(cmov) == blk1 || | |
104 get_ctrl(cmov) == blk2) ) ) { | |
105 | |
106 // Must clone down | |
107 #ifndef PRODUCT | |
108 if( PrintOpto && VerifyLoopOptimizations ) { | |
109 tty->print("Cloning down: "); | |
110 n->dump(); | |
111 } | |
112 #endif | |
113 // Clone down any block-local BoolNode uses of this CmpNode | |
114 for (DUIterator i = n->outs(); n->has_out(i); i++) { | |
115 Node* bol = n->out(i); | |
116 assert( bol->is_Bool(), "" ); | |
117 if (bol->outcnt() == 1) { | |
118 Node* use = bol->unique_out(); | |
119 Node *use_c = use->is_If() ? use->in(0) : get_ctrl(use); | |
120 if (use_c == blk1 || use_c == blk2) { | |
121 continue; | |
122 } | |
123 } | |
124 if (get_ctrl(bol) == blk1 || get_ctrl(bol) == blk2) { | |
125 // Recursively sink any BoolNode | |
126 #ifndef PRODUCT | |
127 if( PrintOpto && VerifyLoopOptimizations ) { | |
128 tty->print("Cloning down: "); | |
129 bol->dump(); | |
130 } | |
131 #endif | |
132 for (DUIterator_Last jmin, j = bol->last_outs(jmin); j >= jmin; --j) { | |
133 // Uses are either IfNodes or CMoves | |
134 Node* iff = bol->last_out(j); | |
135 assert( iff->in(1) == bol, "" ); | |
136 // Get control block of either the CMove or the If input | |
137 Node *iff_ctrl = iff->is_If() ? iff->in(0) : get_ctrl(iff); | |
138 Node *x = bol->clone(); | |
139 register_new_node(x, iff_ctrl); | |
140 _igvn.hash_delete(iff); | |
141 iff->set_req(1, x); | |
142 _igvn._worklist.push(iff); | |
143 } | |
144 _igvn.remove_dead_node( bol ); | |
145 --i; | |
146 } | |
147 } | |
148 // Clone down this CmpNode | |
149 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; --j) { | |
150 Node* bol = n->last_out(j); | |
151 assert( bol->in(1) == n, "" ); | |
152 Node *x = n->clone(); | |
153 register_new_node(x, get_ctrl(bol)); | |
154 _igvn.hash_delete(bol); | |
155 bol->set_req(1, x); | |
156 _igvn._worklist.push(bol); | |
157 } | |
158 _igvn.remove_dead_node( n ); | |
159 | |
160 return true; | |
161 } | |
162 } | |
163 | |
164 // See if splitting-up a Store. Any anti-dep loads must go up as | |
165 // well. An anti-dep load might be in the wrong block, because in | |
166 // this particular layout/schedule we ignored anti-deps and allow | |
167 // memory to be alive twice. This only works if we do the same | |
168 // operations on anti-dep loads as we do their killing stores. | |
169 if( n->is_Store() && n->in(MemNode::Memory)->in(0) == n->in(0) ) { | |
170 // Get store's memory slice | |
171 int alias_idx = C->get_alias_index(_igvn.type(n->in(MemNode::Address))->is_ptr()); | |
172 | |
173 // Get memory-phi anti-dep loads will be using | |
174 Node *memphi = n->in(MemNode::Memory); | |
175 assert( memphi->is_Phi(), "" ); | |
176 // Hoist any anti-dep load to the splitting block; | |
177 // it will then "split-up". | |
178 for (DUIterator_Fast imax,i = memphi->fast_outs(imax); i < imax; i++) { | |
179 Node *load = memphi->fast_out(i); | |
180 if( load->is_Load() && alias_idx == C->get_alias_index(_igvn.type(load->in(MemNode::Address))->is_ptr()) ) | |
181 set_ctrl(load,blk1); | |
182 } | |
183 } | |
184 | |
185 // Found some other Node; must clone it up | |
186 #ifndef PRODUCT | |
187 if( PrintOpto && VerifyLoopOptimizations ) { | |
188 tty->print("Cloning up: "); | |
189 n->dump(); | |
190 } | |
191 #endif | |
192 | |
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193 // ConvI2L may have type information on it which becomes invalid if |
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194 // it moves up in the graph so change any clones so widen the type |
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195 // to TypeLong::INT when pushing it up. |
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196 const Type* rtype = NULL; |
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197 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::INT) { |
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198 rtype = TypeLong::INT; |
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199 } |
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200 |
0 | 201 // Now actually split-up this guy. One copy per control path merging. |
202 Node *phi = PhiNode::make_blank(blk1, n); | |
203 for( uint j = 1; j < blk1->req(); j++ ) { | |
204 Node *x = n->clone(); | |
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205 // Widen the type of the ConvI2L when pushing up. |
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206 if (rtype != NULL) x->as_Type()->set_type(rtype); |
0 | 207 if( n->in(0) && n->in(0) == blk1 ) |
208 x->set_req( 0, blk1->in(j) ); | |
209 for( uint i = 1; i < n->req(); i++ ) { | |
210 Node *m = n->in(i); | |
211 if( get_ctrl(m) == blk1 ) { | |
212 assert( m->in(0) == blk1, "" ); | |
213 x->set_req( i, m->in(j) ); | |
214 } | |
215 } | |
216 register_new_node( x, blk1->in(j) ); | |
217 phi->init_req( j, x ); | |
218 } | |
219 // Announce phi to optimizer | |
220 register_new_node(phi, blk1); | |
221 | |
222 // Remove cloned-up value from optimizer; use phi instead | |
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223 _igvn.replace_node( n, phi ); |
0 | 224 |
225 // (There used to be a self-recursive call to split_up() here, | |
226 // but it is not needed. All necessary forward walking is done | |
227 // by do_split_if() below.) | |
228 | |
229 return true; | |
230 } | |
231 | |
232 //------------------------------register_new_node------------------------------ | |
233 void PhaseIdealLoop::register_new_node( Node *n, Node *blk ) { | |
1172 | 234 assert(!n->is_CFG(), "must be data node"); |
0 | 235 _igvn.register_new_node_with_optimizer(n); |
236 set_ctrl(n, blk); | |
237 IdealLoopTree *loop = get_loop(blk); | |
238 if( !loop->_child ) | |
239 loop->_body.push(n); | |
240 } | |
241 | |
242 //------------------------------small_cache------------------------------------ | |
243 struct small_cache : public Dict { | |
244 | |
245 small_cache() : Dict( cmpkey, hashptr ) {} | |
246 Node *probe( Node *use_blk ) { return (Node*)((*this)[use_blk]); } | |
247 void lru_insert( Node *use_blk, Node *new_def ) { Insert(use_blk,new_def); } | |
248 }; | |
249 | |
250 //------------------------------spinup----------------------------------------- | |
251 // "Spin up" the dominator tree, starting at the use site and stopping when we | |
252 // find the post-dominating point. | |
253 | |
254 // We must be at the merge point which post-dominates 'new_false' and | |
255 // 'new_true'. Figure out which edges into the RegionNode eventually lead up | |
256 // to false and which to true. Put in a PhiNode to merge values; plug in | |
257 // the appropriate false-arm or true-arm values. If some path leads to the | |
258 // original IF, then insert a Phi recursively. | |
259 Node *PhaseIdealLoop::spinup( Node *iff_dom, Node *new_false, Node *new_true, Node *use_blk, Node *def, small_cache *cache ) { | |
260 if (use_blk->is_top()) // Handle dead uses | |
261 return use_blk; | |
262 Node *prior_n = (Node*)0xdeadbeef; | |
263 Node *n = use_blk; // Get path input | |
264 assert( use_blk != iff_dom, "" ); | |
265 // Here's the "spinup" the dominator tree loop. Do a cache-check | |
266 // along the way, in case we've come this way before. | |
267 while( n != iff_dom ) { // Found post-dominating point? | |
268 prior_n = n; | |
269 n = idom(n); // Search higher | |
270 Node *s = cache->probe( prior_n ); // Check cache | |
271 if( s ) return s; // Cache hit! | |
272 } | |
273 | |
274 Node *phi_post; | |
275 if( prior_n == new_false || prior_n == new_true ) { | |
276 phi_post = def->clone(); | |
277 phi_post->set_req(0, prior_n ); | |
278 register_new_node(phi_post, prior_n); | |
279 } else { | |
280 // This method handles both control uses (looking for Regions) or data | |
281 // uses (looking for Phis). If looking for a control use, then we need | |
282 // to insert a Region instead of a Phi; however Regions always exist | |
283 // previously (the hash_find_insert below would always hit) so we can | |
284 // return the existing Region. | |
285 if( def->is_CFG() ) { | |
286 phi_post = prior_n; // If looking for CFG, return prior | |
287 } else { | |
288 assert( def->is_Phi(), "" ); | |
289 assert( prior_n->is_Region(), "must be a post-dominating merge point" ); | |
290 | |
291 // Need a Phi here | |
292 phi_post = PhiNode::make_blank(prior_n, def); | |
293 // Search for both true and false on all paths till find one. | |
294 for( uint i = 1; i < phi_post->req(); i++ ) // For all paths | |
295 phi_post->init_req( i, spinup( iff_dom, new_false, new_true, prior_n->in(i), def, cache ) ); | |
296 Node *t = _igvn.hash_find_insert(phi_post); | |
297 if( t ) { // See if we already have this one | |
298 // phi_post will not be used, so kill it | |
299 _igvn.remove_dead_node(phi_post); | |
300 phi_post->destruct(); | |
301 phi_post = t; | |
302 } else { | |
303 register_new_node( phi_post, prior_n ); | |
304 } | |
305 } | |
306 } | |
307 | |
308 // Update cache everywhere | |
309 prior_n = (Node*)0xdeadbeef; // Reset IDOM walk | |
310 n = use_blk; // Get path input | |
311 // Spin-up the idom tree again, basically doing path-compression. | |
312 // Insert cache entries along the way, so that if we ever hit this | |
313 // point in the IDOM tree again we'll stop immediately on a cache hit. | |
314 while( n != iff_dom ) { // Found post-dominating point? | |
315 prior_n = n; | |
316 n = idom(n); // Search higher | |
317 cache->lru_insert( prior_n, phi_post ); // Fill cache | |
318 } // End of while not gone high enough | |
319 | |
320 return phi_post; | |
321 } | |
322 | |
323 //------------------------------find_use_block--------------------------------- | |
324 // Find the block a USE is in. Normally USE's are in the same block as the | |
325 // using instruction. For Phi-USE's, the USE is in the predecessor block | |
326 // along the corresponding path. | |
327 Node *PhaseIdealLoop::find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ) { | |
328 // CFG uses are their own block | |
329 if( use->is_CFG() ) | |
330 return use; | |
331 | |
332 if( use->is_Phi() ) { // Phi uses in prior block | |
333 // Grab the first Phi use; there may be many. | |
605 | 334 // Each will be handled as a separate iteration of |
0 | 335 // the "while( phi->outcnt() )" loop. |
336 uint j; | |
337 for( j = 1; j < use->req(); j++ ) | |
338 if( use->in(j) == def ) | |
339 break; | |
340 assert( j < use->req(), "def should be among use's inputs" ); | |
341 return use->in(0)->in(j); | |
342 } | |
343 // Normal (non-phi) use | |
344 Node *use_blk = get_ctrl(use); | |
345 // Some uses are directly attached to the old (and going away) | |
346 // false and true branches. | |
347 if( use_blk == old_false ) { | |
348 use_blk = new_false; | |
349 set_ctrl(use, new_false); | |
350 } | |
351 if( use_blk == old_true ) { | |
352 use_blk = new_true; | |
353 set_ctrl(use, new_true); | |
354 } | |
355 | |
356 if (use_blk == NULL) { // He's dead, Jim | |
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357 _igvn.replace_node(use, C->top()); |
0 | 358 } |
359 | |
360 return use_blk; | |
361 } | |
362 | |
363 //------------------------------handle_use------------------------------------- | |
364 // Handle uses of the merge point. Basically, split-if makes the merge point | |
365 // go away so all uses of the merge point must go away as well. Most block | |
366 // local uses have already been split-up, through the merge point. Uses from | |
367 // far below the merge point can't always be split up (e.g., phi-uses are | |
368 // pinned) and it makes too much stuff live. Instead we use a path-based | |
369 // solution to move uses down. | |
370 // | |
371 // If the use is along the pre-split-CFG true branch, then the new use will | |
372 // be from the post-split-CFG true merge point. Vice-versa for the false | |
373 // path. Some uses will be along both paths; then we sink the use to the | |
374 // post-dominating location; we may need to insert a Phi there. | |
375 void PhaseIdealLoop::handle_use( Node *use, Node *def, small_cache *cache, Node *region_dom, Node *new_false, Node *new_true, Node *old_false, Node *old_true ) { | |
376 | |
377 Node *use_blk = find_use_block(use,def,old_false,new_false,old_true,new_true); | |
378 if( !use_blk ) return; // He's dead, Jim | |
379 | |
380 // Walk up the dominator tree until I hit either the old IfFalse, the old | |
381 // IfTrue or the old If. Insert Phis where needed. | |
382 Node *new_def = spinup( region_dom, new_false, new_true, use_blk, def, cache ); | |
383 | |
384 // Found where this USE goes. Re-point him. | |
385 uint i; | |
386 for( i = 0; i < use->req(); i++ ) | |
387 if( use->in(i) == def ) | |
388 break; | |
389 assert( i < use->req(), "def should be among use's inputs" ); | |
390 _igvn.hash_delete(use); | |
391 use->set_req(i, new_def); | |
392 _igvn._worklist.push(use); | |
393 } | |
394 | |
395 //------------------------------do_split_if------------------------------------ | |
396 // Found an If getting its condition-code input from a Phi in the same block. | |
397 // Split thru the Region. | |
398 void PhaseIdealLoop::do_split_if( Node *iff ) { | |
399 #ifndef PRODUCT | |
400 if( PrintOpto && VerifyLoopOptimizations ) | |
401 tty->print_cr("Split-if"); | |
2445 | 402 if (TraceLoopOpts) { |
403 tty->print_cr("SplitIf"); | |
404 } | |
0 | 405 #endif |
406 C->set_major_progress(); | |
407 Node *region = iff->in(0); | |
408 Node *region_dom = idom(region); | |
409 | |
410 // We are going to clone this test (and the control flow with it) up through | |
411 // the incoming merge point. We need to empty the current basic block. | |
412 // Clone any instructions which must be in this block up through the merge | |
413 // point. | |
414 DUIterator i, j; | |
415 bool progress = true; | |
416 while (progress) { | |
417 progress = false; | |
418 for (i = region->outs(); region->has_out(i); i++) { | |
419 Node* n = region->out(i); | |
420 if( n == region ) continue; | |
421 // The IF to be split is OK. | |
422 if( n == iff ) continue; | |
423 if( !n->is_Phi() ) { // Found pinned memory op or such | |
424 if (split_up(n, region, iff)) { | |
425 i = region->refresh_out_pos(i); | |
426 progress = true; | |
427 } | |
428 continue; | |
429 } | |
430 assert( n->in(0) == region, "" ); | |
431 | |
432 // Recursively split up all users of a Phi | |
433 for (j = n->outs(); n->has_out(j); j++) { | |
434 Node* m = n->out(j); | |
435 // If m is dead, throw it away, and declare progress | |
436 if (_nodes[m->_idx] == NULL) { | |
437 _igvn.remove_dead_node(m); | |
438 // fall through | |
439 } | |
440 else if (m != iff && split_up(m, region, iff)) { | |
441 // fall through | |
442 } else { | |
443 continue; | |
444 } | |
445 // Something unpredictable changed. | |
446 // Tell the iterators to refresh themselves, and rerun the loop. | |
447 i = region->refresh_out_pos(i); | |
448 j = region->refresh_out_pos(j); | |
449 progress = true; | |
450 } | |
451 } | |
452 } | |
453 | |
454 // Now we have no instructions in the block containing the IF. | |
455 // Split the IF. | |
456 Node *new_iff = split_thru_region( iff, region ); | |
457 | |
458 // Replace both uses of 'new_iff' with Regions merging True/False | |
459 // paths. This makes 'new_iff' go dead. | |
460 Node *old_false, *old_true; | |
461 Node *new_false, *new_true; | |
462 for (DUIterator_Last j2min, j2 = iff->last_outs(j2min); j2 >= j2min; --j2) { | |
463 Node *ifp = iff->last_out(j2); | |
464 assert( ifp->Opcode() == Op_IfFalse || ifp->Opcode() == Op_IfTrue, "" ); | |
465 ifp->set_req(0, new_iff); | |
466 Node *ifpx = split_thru_region( ifp, region ); | |
467 | |
468 // Replace 'If' projection of a Region with a Region of | |
469 // 'If' projections. | |
470 ifpx->set_req(0, ifpx); // A TRUE RegionNode | |
471 | |
472 // Setup dominator info | |
473 set_idom(ifpx, region_dom, dom_depth(region_dom) + 1); | |
474 | |
475 // Check for splitting loop tails | |
476 if( get_loop(iff)->tail() == ifp ) | |
477 get_loop(iff)->_tail = ifpx; | |
478 | |
479 // Replace in the graph with lazy-update mechanism | |
480 new_iff->set_req(0, new_iff); // hook self so it does not go dead | |
481 lazy_replace_proj( ifp, ifpx ); | |
482 new_iff->set_req(0, region); | |
483 | |
484 // Record bits for later xforms | |
485 if( ifp->Opcode() == Op_IfFalse ) { | |
486 old_false = ifp; | |
487 new_false = ifpx; | |
488 } else { | |
489 old_true = ifp; | |
490 new_true = ifpx; | |
491 } | |
492 } | |
493 _igvn.remove_dead_node(new_iff); | |
494 // Lazy replace IDOM info with the region's dominator | |
495 lazy_replace( iff, region_dom ); | |
496 | |
497 // Now make the original merge point go dead, by handling all its uses. | |
498 small_cache region_cache; | |
499 // Preload some control flow in region-cache | |
500 region_cache.lru_insert( new_false, new_false ); | |
501 region_cache.lru_insert( new_true , new_true ); | |
502 // Now handle all uses of the splitting block | |
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503 for (DUIterator k = region->outs(); region->has_out(k); k++) { |
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504 Node* phi = region->out(k); |
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505 if (!phi->in(0)) { // Dead phi? Remove it |
0 | 506 _igvn.remove_dead_node(phi); |
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507 } else if (phi == region) { // Found the self-reference |
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508 continue; // No roll-back of DUIterator |
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509 } else if (phi->is_Phi()) { // Expected common case: Phi hanging off of Region |
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510 assert(phi->in(0) == region, "Inconsistent graph"); |
0 | 511 // Need a per-def cache. Phi represents a def, so make a cache |
512 small_cache phi_cache; | |
513 | |
514 // Inspect all Phi uses to make the Phi go dead | |
515 for (DUIterator_Last lmin, l = phi->last_outs(lmin); l >= lmin; --l) { | |
516 Node* use = phi->last_out(l); | |
517 // Compute the new DEF for this USE. New DEF depends on the path | |
518 // taken from the original DEF to the USE. The new DEF may be some | |
519 // collection of PHI's merging values from different paths. The Phis | |
520 // inserted depend only on the location of the USE. We use a | |
521 // 2-element cache to handle multiple uses from the same block. | |
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522 handle_use(use, phi, &phi_cache, region_dom, new_false, new_true, old_false, old_true); |
0 | 523 } // End of while phi has uses |
524 // Remove the dead Phi | |
525 _igvn.remove_dead_node( phi ); | |
526 } else { | |
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527 assert(phi->in(0) == region, "Inconsistent graph"); |
0 | 528 // Random memory op guarded by Region. Compute new DEF for USE. |
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529 handle_use(phi, region, ®ion_cache, region_dom, new_false, new_true, old_false, old_true); |
0 | 530 } |
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531 // Every path above deletes a use of the region, except for the region |
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532 // self-cycle (which is needed by handle_use calling find_use_block |
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533 // calling get_ctrl calling get_ctrl_no_update looking for dead |
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534 // regions). So roll back the DUIterator innards. |
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535 --k; |
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536 } // End of while merge point has phis |
0 | 537 |
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538 assert(region->outcnt() == 1, "Only self reference should remain"); // Just Self on the Region |
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539 region->set_req(0, NULL); // Break the self-cycle |
0 | 540 |
541 // Any leftover bits in the splitting block must not have depended on local | |
542 // Phi inputs (these have already been split-up). Hence it's safe to hoist | |
543 // these guys to the dominating point. | |
544 lazy_replace( region, region_dom ); | |
545 #ifndef PRODUCT | |
546 if( VerifyLoopOptimizations ) verify(); | |
547 #endif | |
548 } |