Mercurial > hg > truffle
annotate src/share/vm/opto/split_if.cpp @ 10408:836a62f43af9
Merge with http://hg.openjdk.java.net/hsx/hsx25/hotspot/
| author | Doug Simon <doug.simon@oracle.com> |
|---|---|
| date | Wed, 19 Jun 2013 10:45:56 +0200 |
| parents | b9a9ed0f8eeb |
| children |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 1999, 2012, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #include "precompiled.hpp" |
| 26 #include "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(), "" ); | |
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38 Node *r = new (C) RegionNode( region->req() ); |
| 0 | 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); | |
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140 _igvn.replace_input_of(iff, 1, x); |
| 0 | 141 } |
| 142 _igvn.remove_dead_node( bol ); | |
| 143 --i; | |
| 144 } | |
| 145 } | |
| 146 // Clone down this CmpNode | |
| 147 for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; --j) { | |
| 148 Node* bol = n->last_out(j); | |
| 149 assert( bol->in(1) == n, "" ); | |
| 150 Node *x = n->clone(); | |
| 151 register_new_node(x, get_ctrl(bol)); | |
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152 _igvn.replace_input_of(bol, 1, x); |
| 0 | 153 } |
| 154 _igvn.remove_dead_node( n ); | |
| 155 | |
| 156 return true; | |
| 157 } | |
| 158 } | |
| 159 | |
| 160 // See if splitting-up a Store. Any anti-dep loads must go up as | |
| 161 // well. An anti-dep load might be in the wrong block, because in | |
| 162 // this particular layout/schedule we ignored anti-deps and allow | |
| 163 // memory to be alive twice. This only works if we do the same | |
| 164 // operations on anti-dep loads as we do their killing stores. | |
| 165 if( n->is_Store() && n->in(MemNode::Memory)->in(0) == n->in(0) ) { | |
| 166 // Get store's memory slice | |
| 167 int alias_idx = C->get_alias_index(_igvn.type(n->in(MemNode::Address))->is_ptr()); | |
| 168 | |
| 169 // Get memory-phi anti-dep loads will be using | |
| 170 Node *memphi = n->in(MemNode::Memory); | |
| 171 assert( memphi->is_Phi(), "" ); | |
| 172 // Hoist any anti-dep load to the splitting block; | |
| 173 // it will then "split-up". | |
| 174 for (DUIterator_Fast imax,i = memphi->fast_outs(imax); i < imax; i++) { | |
| 175 Node *load = memphi->fast_out(i); | |
| 176 if( load->is_Load() && alias_idx == C->get_alias_index(_igvn.type(load->in(MemNode::Address))->is_ptr()) ) | |
| 177 set_ctrl(load,blk1); | |
| 178 } | |
| 179 } | |
| 180 | |
| 181 // Found some other Node; must clone it up | |
| 182 #ifndef PRODUCT | |
| 183 if( PrintOpto && VerifyLoopOptimizations ) { | |
| 184 tty->print("Cloning up: "); | |
| 185 n->dump(); | |
| 186 } | |
| 187 #endif | |
| 188 | |
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189 // ConvI2L may have type information on it which becomes invalid if |
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190 // it moves up in the graph so change any clones so widen the type |
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191 // to TypeLong::INT when pushing it up. |
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192 const Type* rtype = NULL; |
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193 if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::INT) { |
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194 rtype = TypeLong::INT; |
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195 } |
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196 |
| 0 | 197 // Now actually split-up this guy. One copy per control path merging. |
| 198 Node *phi = PhiNode::make_blank(blk1, n); | |
| 199 for( uint j = 1; j < blk1->req(); j++ ) { | |
| 200 Node *x = n->clone(); | |
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201 // Widen the type of the ConvI2L when pushing up. |
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202 if (rtype != NULL) x->as_Type()->set_type(rtype); |
| 0 | 203 if( n->in(0) && n->in(0) == blk1 ) |
| 204 x->set_req( 0, blk1->in(j) ); | |
| 205 for( uint i = 1; i < n->req(); i++ ) { | |
| 206 Node *m = n->in(i); | |
| 207 if( get_ctrl(m) == blk1 ) { | |
| 208 assert( m->in(0) == blk1, "" ); | |
| 209 x->set_req( i, m->in(j) ); | |
| 210 } | |
| 211 } | |
| 212 register_new_node( x, blk1->in(j) ); | |
| 213 phi->init_req( j, x ); | |
| 214 } | |
| 215 // Announce phi to optimizer | |
| 216 register_new_node(phi, blk1); | |
| 217 | |
| 218 // Remove cloned-up value from optimizer; use phi instead | |
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219 _igvn.replace_node( n, phi ); |
| 0 | 220 |
| 221 // (There used to be a self-recursive call to split_up() here, | |
| 222 // but it is not needed. All necessary forward walking is done | |
| 223 // by do_split_if() below.) | |
| 224 | |
| 225 return true; | |
| 226 } | |
| 227 | |
| 228 //------------------------------register_new_node------------------------------ | |
| 229 void PhaseIdealLoop::register_new_node( Node *n, Node *blk ) { | |
| 1172 | 230 assert(!n->is_CFG(), "must be data node"); |
| 0 | 231 _igvn.register_new_node_with_optimizer(n); |
| 232 set_ctrl(n, blk); | |
| 233 IdealLoopTree *loop = get_loop(blk); | |
| 234 if( !loop->_child ) | |
| 235 loop->_body.push(n); | |
| 236 } | |
| 237 | |
| 238 //------------------------------small_cache------------------------------------ | |
| 239 struct small_cache : public Dict { | |
| 240 | |
| 241 small_cache() : Dict( cmpkey, hashptr ) {} | |
| 242 Node *probe( Node *use_blk ) { return (Node*)((*this)[use_blk]); } | |
| 243 void lru_insert( Node *use_blk, Node *new_def ) { Insert(use_blk,new_def); } | |
| 244 }; | |
| 245 | |
| 246 //------------------------------spinup----------------------------------------- | |
| 247 // "Spin up" the dominator tree, starting at the use site and stopping when we | |
| 248 // find the post-dominating point. | |
| 249 | |
| 250 // We must be at the merge point which post-dominates 'new_false' and | |
| 251 // 'new_true'. Figure out which edges into the RegionNode eventually lead up | |
| 252 // to false and which to true. Put in a PhiNode to merge values; plug in | |
| 253 // the appropriate false-arm or true-arm values. If some path leads to the | |
| 254 // original IF, then insert a Phi recursively. | |
| 255 Node *PhaseIdealLoop::spinup( Node *iff_dom, Node *new_false, Node *new_true, Node *use_blk, Node *def, small_cache *cache ) { | |
| 256 if (use_blk->is_top()) // Handle dead uses | |
| 257 return use_blk; | |
| 258 Node *prior_n = (Node*)0xdeadbeef; | |
| 259 Node *n = use_blk; // Get path input | |
| 260 assert( use_blk != iff_dom, "" ); | |
| 261 // Here's the "spinup" the dominator tree loop. Do a cache-check | |
| 262 // along the way, in case we've come this way before. | |
| 263 while( n != iff_dom ) { // Found post-dominating point? | |
| 264 prior_n = n; | |
| 265 n = idom(n); // Search higher | |
| 266 Node *s = cache->probe( prior_n ); // Check cache | |
| 267 if( s ) return s; // Cache hit! | |
| 268 } | |
| 269 | |
| 270 Node *phi_post; | |
| 271 if( prior_n == new_false || prior_n == new_true ) { | |
| 272 phi_post = def->clone(); | |
| 273 phi_post->set_req(0, prior_n ); | |
| 274 register_new_node(phi_post, prior_n); | |
| 275 } else { | |
| 276 // This method handles both control uses (looking for Regions) or data | |
| 277 // uses (looking for Phis). If looking for a control use, then we need | |
| 278 // to insert a Region instead of a Phi; however Regions always exist | |
| 279 // previously (the hash_find_insert below would always hit) so we can | |
| 280 // return the existing Region. | |
| 281 if( def->is_CFG() ) { | |
| 282 phi_post = prior_n; // If looking for CFG, return prior | |
| 283 } else { | |
| 284 assert( def->is_Phi(), "" ); | |
| 285 assert( prior_n->is_Region(), "must be a post-dominating merge point" ); | |
| 286 | |
| 287 // Need a Phi here | |
| 288 phi_post = PhiNode::make_blank(prior_n, def); | |
| 289 // Search for both true and false on all paths till find one. | |
| 290 for( uint i = 1; i < phi_post->req(); i++ ) // For all paths | |
| 291 phi_post->init_req( i, spinup( iff_dom, new_false, new_true, prior_n->in(i), def, cache ) ); | |
| 292 Node *t = _igvn.hash_find_insert(phi_post); | |
| 293 if( t ) { // See if we already have this one | |
| 294 // phi_post will not be used, so kill it | |
| 295 _igvn.remove_dead_node(phi_post); | |
| 296 phi_post->destruct(); | |
| 297 phi_post = t; | |
| 298 } else { | |
| 299 register_new_node( phi_post, prior_n ); | |
| 300 } | |
| 301 } | |
| 302 } | |
| 303 | |
| 304 // Update cache everywhere | |
| 305 prior_n = (Node*)0xdeadbeef; // Reset IDOM walk | |
| 306 n = use_blk; // Get path input | |
| 307 // Spin-up the idom tree again, basically doing path-compression. | |
| 308 // Insert cache entries along the way, so that if we ever hit this | |
| 309 // point in the IDOM tree again we'll stop immediately on a cache hit. | |
| 310 while( n != iff_dom ) { // Found post-dominating point? | |
| 311 prior_n = n; | |
| 312 n = idom(n); // Search higher | |
| 313 cache->lru_insert( prior_n, phi_post ); // Fill cache | |
| 314 } // End of while not gone high enough | |
| 315 | |
| 316 return phi_post; | |
| 317 } | |
| 318 | |
| 319 //------------------------------find_use_block--------------------------------- | |
| 320 // Find the block a USE is in. Normally USE's are in the same block as the | |
| 321 // using instruction. For Phi-USE's, the USE is in the predecessor block | |
| 322 // along the corresponding path. | |
| 323 Node *PhaseIdealLoop::find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true ) { | |
| 324 // CFG uses are their own block | |
| 325 if( use->is_CFG() ) | |
| 326 return use; | |
| 327 | |
| 328 if( use->is_Phi() ) { // Phi uses in prior block | |
| 329 // Grab the first Phi use; there may be many. | |
| 605 | 330 // Each will be handled as a separate iteration of |
| 0 | 331 // the "while( phi->outcnt() )" loop. |
| 332 uint j; | |
| 333 for( j = 1; j < use->req(); j++ ) | |
| 334 if( use->in(j) == def ) | |
| 335 break; | |
| 336 assert( j < use->req(), "def should be among use's inputs" ); | |
| 337 return use->in(0)->in(j); | |
| 338 } | |
| 339 // Normal (non-phi) use | |
| 340 Node *use_blk = get_ctrl(use); | |
| 341 // Some uses are directly attached to the old (and going away) | |
| 342 // false and true branches. | |
| 343 if( use_blk == old_false ) { | |
| 344 use_blk = new_false; | |
| 345 set_ctrl(use, new_false); | |
| 346 } | |
| 347 if( use_blk == old_true ) { | |
| 348 use_blk = new_true; | |
| 349 set_ctrl(use, new_true); | |
| 350 } | |
| 351 | |
| 352 if (use_blk == NULL) { // He's dead, Jim | |
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353 _igvn.replace_node(use, C->top()); |
| 0 | 354 } |
| 355 | |
| 356 return use_blk; | |
| 357 } | |
| 358 | |
| 359 //------------------------------handle_use------------------------------------- | |
| 360 // Handle uses of the merge point. Basically, split-if makes the merge point | |
| 361 // go away so all uses of the merge point must go away as well. Most block | |
| 362 // local uses have already been split-up, through the merge point. Uses from | |
| 363 // far below the merge point can't always be split up (e.g., phi-uses are | |
| 364 // pinned) and it makes too much stuff live. Instead we use a path-based | |
| 365 // solution to move uses down. | |
| 366 // | |
| 367 // If the use is along the pre-split-CFG true branch, then the new use will | |
| 368 // be from the post-split-CFG true merge point. Vice-versa for the false | |
| 369 // path. Some uses will be along both paths; then we sink the use to the | |
| 370 // post-dominating location; we may need to insert a Phi there. | |
| 371 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 ) { | |
| 372 | |
| 373 Node *use_blk = find_use_block(use,def,old_false,new_false,old_true,new_true); | |
| 374 if( !use_blk ) return; // He's dead, Jim | |
| 375 | |
| 376 // Walk up the dominator tree until I hit either the old IfFalse, the old | |
| 377 // IfTrue or the old If. Insert Phis where needed. | |
| 378 Node *new_def = spinup( region_dom, new_false, new_true, use_blk, def, cache ); | |
| 379 | |
| 380 // Found where this USE goes. Re-point him. | |
| 381 uint i; | |
| 382 for( i = 0; i < use->req(); i++ ) | |
| 383 if( use->in(i) == def ) | |
| 384 break; | |
| 385 assert( i < use->req(), "def should be among use's inputs" ); | |
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386 _igvn.replace_input_of(use, i, new_def); |
| 0 | 387 } |
| 388 | |
| 389 //------------------------------do_split_if------------------------------------ | |
| 390 // Found an If getting its condition-code input from a Phi in the same block. | |
| 391 // Split thru the Region. | |
| 392 void PhaseIdealLoop::do_split_if( Node *iff ) { | |
| 393 #ifndef PRODUCT | |
| 394 if( PrintOpto && VerifyLoopOptimizations ) | |
| 395 tty->print_cr("Split-if"); | |
| 2445 | 396 if (TraceLoopOpts) { |
| 397 tty->print_cr("SplitIf"); | |
| 398 } | |
| 0 | 399 #endif |
| 400 C->set_major_progress(); | |
| 401 Node *region = iff->in(0); | |
| 402 Node *region_dom = idom(region); | |
| 403 | |
| 404 // We are going to clone this test (and the control flow with it) up through | |
| 405 // the incoming merge point. We need to empty the current basic block. | |
| 406 // Clone any instructions which must be in this block up through the merge | |
| 407 // point. | |
| 408 DUIterator i, j; | |
| 409 bool progress = true; | |
| 410 while (progress) { | |
| 411 progress = false; | |
| 412 for (i = region->outs(); region->has_out(i); i++) { | |
| 413 Node* n = region->out(i); | |
| 414 if( n == region ) continue; | |
| 415 // The IF to be split is OK. | |
| 416 if( n == iff ) continue; | |
| 417 if( !n->is_Phi() ) { // Found pinned memory op or such | |
| 418 if (split_up(n, region, iff)) { | |
| 419 i = region->refresh_out_pos(i); | |
| 420 progress = true; | |
| 421 } | |
| 422 continue; | |
| 423 } | |
| 424 assert( n->in(0) == region, "" ); | |
| 425 | |
| 426 // Recursively split up all users of a Phi | |
| 427 for (j = n->outs(); n->has_out(j); j++) { | |
| 428 Node* m = n->out(j); | |
| 429 // If m is dead, throw it away, and declare progress | |
| 430 if (_nodes[m->_idx] == NULL) { | |
| 431 _igvn.remove_dead_node(m); | |
| 432 // fall through | |
| 433 } | |
| 434 else if (m != iff && split_up(m, region, iff)) { | |
| 435 // fall through | |
| 436 } else { | |
| 437 continue; | |
| 438 } | |
| 439 // Something unpredictable changed. | |
| 440 // Tell the iterators to refresh themselves, and rerun the loop. | |
| 441 i = region->refresh_out_pos(i); | |
| 442 j = region->refresh_out_pos(j); | |
| 443 progress = true; | |
| 444 } | |
| 445 } | |
| 446 } | |
| 447 | |
| 448 // Now we have no instructions in the block containing the IF. | |
| 449 // Split the IF. | |
| 450 Node *new_iff = split_thru_region( iff, region ); | |
| 451 | |
| 452 // Replace both uses of 'new_iff' with Regions merging True/False | |
| 453 // paths. This makes 'new_iff' go dead. | |
| 454 Node *old_false, *old_true; | |
| 455 Node *new_false, *new_true; | |
| 456 for (DUIterator_Last j2min, j2 = iff->last_outs(j2min); j2 >= j2min; --j2) { | |
| 457 Node *ifp = iff->last_out(j2); | |
| 458 assert( ifp->Opcode() == Op_IfFalse || ifp->Opcode() == Op_IfTrue, "" ); | |
| 459 ifp->set_req(0, new_iff); | |
| 460 Node *ifpx = split_thru_region( ifp, region ); | |
| 461 | |
| 462 // Replace 'If' projection of a Region with a Region of | |
| 463 // 'If' projections. | |
| 464 ifpx->set_req(0, ifpx); // A TRUE RegionNode | |
| 465 | |
| 466 // Setup dominator info | |
| 467 set_idom(ifpx, region_dom, dom_depth(region_dom) + 1); | |
| 468 | |
| 469 // Check for splitting loop tails | |
| 470 if( get_loop(iff)->tail() == ifp ) | |
| 471 get_loop(iff)->_tail = ifpx; | |
| 472 | |
| 473 // Replace in the graph with lazy-update mechanism | |
| 474 new_iff->set_req(0, new_iff); // hook self so it does not go dead | |
| 475 lazy_replace_proj( ifp, ifpx ); | |
| 476 new_iff->set_req(0, region); | |
| 477 | |
| 478 // Record bits for later xforms | |
| 479 if( ifp->Opcode() == Op_IfFalse ) { | |
| 480 old_false = ifp; | |
| 481 new_false = ifpx; | |
| 482 } else { | |
| 483 old_true = ifp; | |
| 484 new_true = ifpx; | |
| 485 } | |
| 486 } | |
| 487 _igvn.remove_dead_node(new_iff); | |
| 488 // Lazy replace IDOM info with the region's dominator | |
| 489 lazy_replace( iff, region_dom ); | |
| 490 | |
| 491 // Now make the original merge point go dead, by handling all its uses. | |
| 492 small_cache region_cache; | |
| 493 // Preload some control flow in region-cache | |
| 494 region_cache.lru_insert( new_false, new_false ); | |
| 495 region_cache.lru_insert( new_true , new_true ); | |
| 496 // Now handle all uses of the splitting block | |
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497 for (DUIterator k = region->outs(); region->has_out(k); k++) { |
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498 Node* phi = region->out(k); |
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499 if (!phi->in(0)) { // Dead phi? Remove it |
| 0 | 500 _igvn.remove_dead_node(phi); |
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501 } else if (phi == region) { // Found the self-reference |
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502 continue; // No roll-back of DUIterator |
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503 } else if (phi->is_Phi()) { // Expected common case: Phi hanging off of Region |
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504 assert(phi->in(0) == region, "Inconsistent graph"); |
| 0 | 505 // Need a per-def cache. Phi represents a def, so make a cache |
| 506 small_cache phi_cache; | |
| 507 | |
| 508 // Inspect all Phi uses to make the Phi go dead | |
| 509 for (DUIterator_Last lmin, l = phi->last_outs(lmin); l >= lmin; --l) { | |
| 510 Node* use = phi->last_out(l); | |
| 511 // Compute the new DEF for this USE. New DEF depends on the path | |
| 512 // taken from the original DEF to the USE. The new DEF may be some | |
| 513 // collection of PHI's merging values from different paths. The Phis | |
| 514 // inserted depend only on the location of the USE. We use a | |
| 515 // 2-element cache to handle multiple uses from the same block. | |
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516 handle_use(use, phi, &phi_cache, region_dom, new_false, new_true, old_false, old_true); |
| 0 | 517 } // End of while phi has uses |
| 518 // Remove the dead Phi | |
| 519 _igvn.remove_dead_node( phi ); | |
| 520 } else { | |
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521 assert(phi->in(0) == region, "Inconsistent graph"); |
| 0 | 522 // Random memory op guarded by Region. Compute new DEF for USE. |
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523 handle_use(phi, region, ®ion_cache, region_dom, new_false, new_true, old_false, old_true); |
| 0 | 524 } |
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525 // Every path above deletes a use of the region, except for the region |
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526 // self-cycle (which is needed by handle_use calling find_use_block |
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527 // calling get_ctrl calling get_ctrl_no_update looking for dead |
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528 // regions). So roll back the DUIterator innards. |
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529 --k; |
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530 } // End of while merge point has phis |
| 0 | 531 |
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532 assert(region->outcnt() == 1, "Only self reference should remain"); // Just Self on the Region |
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533 region->set_req(0, NULL); // Break the self-cycle |
| 0 | 534 |
| 535 // Any leftover bits in the splitting block must not have depended on local | |
| 536 // Phi inputs (these have already been split-up). Hence it's safe to hoist | |
| 537 // these guys to the dominating point. | |
| 538 lazy_replace( region, region_dom ); | |
| 539 #ifndef PRODUCT | |
| 540 if( VerifyLoopOptimizations ) verify(); | |
| 541 #endif | |
| 542 } |