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annotate src/share/vm/opto/coalesce.cpp @ 15152:5f75a06505a6
Fix formatting
author | Gilles Duboscq <duboscq@ssw.jku.at> |
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date | Tue, 15 Apr 2014 13:40:43 +0200 |
parents | 4ca6dc0799b6 |
children | 7848fc12602b |
rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1997, 2013, 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/block.hpp" | |
28 #include "opto/cfgnode.hpp" | |
29 #include "opto/chaitin.hpp" | |
30 #include "opto/coalesce.hpp" | |
31 #include "opto/connode.hpp" | |
32 #include "opto/indexSet.hpp" | |
33 #include "opto/machnode.hpp" | |
34 #include "opto/matcher.hpp" | |
35 #include "opto/regmask.hpp" | |
0 | 36 |
37 #ifndef PRODUCT | |
10111 | 38 void PhaseCoalesce::dump(Node *n) const { |
0 | 39 // Being a const function means I cannot use 'Find' |
10111 | 40 uint r = _phc._lrg_map.find(n); |
0 | 41 tty->print("L%d/N%d ",r,n->_idx); |
42 } | |
43 | |
44 void PhaseCoalesce::dump() const { | |
45 // I know I have a block layout now, so I can print blocks in a loop | |
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46 for( uint i=0; i<_phc._cfg.number_of_blocks(); i++ ) { |
0 | 47 uint j; |
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48 Block* b = _phc._cfg.get_block(i); |
0 | 49 // Print a nice block header |
50 tty->print("B%d: ",b->_pre_order); | |
51 for( j=1; j<b->num_preds(); j++ ) | |
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52 tty->print("B%d ", _phc._cfg.get_block_for_node(b->pred(j))->_pre_order); |
0 | 53 tty->print("-> "); |
54 for( j=0; j<b->_num_succs; j++ ) | |
55 tty->print("B%d ",b->_succs[j]->_pre_order); | |
56 tty->print(" IDom: B%d/#%d\n", b->_idom ? b->_idom->_pre_order : 0, b->_dom_depth); | |
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57 uint cnt = b->number_of_nodes(); |
0 | 58 for( j=0; j<cnt; j++ ) { |
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59 Node *n = b->get_node(j); |
0 | 60 dump( n ); |
61 tty->print("\t%s\t",n->Name()); | |
62 | |
63 // Dump the inputs | |
64 uint k; // Exit value of loop | |
65 for( k=0; k<n->req(); k++ ) // For all required inputs | |
66 if( n->in(k) ) dump( n->in(k) ); | |
67 else tty->print("_ "); | |
68 int any_prec = 0; | |
69 for( ; k<n->len(); k++ ) // For all precedence inputs | |
70 if( n->in(k) ) { | |
71 if( !any_prec++ ) tty->print(" |"); | |
72 dump( n->in(k) ); | |
73 } | |
74 | |
75 // Dump node-specific info | |
76 n->dump_spec(tty); | |
77 tty->print("\n"); | |
78 | |
79 } | |
80 tty->print("\n"); | |
81 } | |
82 } | |
83 #endif | |
84 | |
85 // Combine the live ranges def'd by these 2 Nodes. N2 is an input to N1. | |
10111 | 86 void PhaseCoalesce::combine_these_two(Node *n1, Node *n2) { |
87 uint lr1 = _phc._lrg_map.find(n1); | |
88 uint lr2 = _phc._lrg_map.find(n2); | |
0 | 89 if( lr1 != lr2 && // Different live ranges already AND |
90 !_phc._ifg->test_edge_sq( lr1, lr2 ) ) { // Do not interfere | |
91 LRG *lrg1 = &_phc.lrgs(lr1); | |
92 LRG *lrg2 = &_phc.lrgs(lr2); | |
93 // Not an oop->int cast; oop->oop, int->int, AND int->oop are OK. | |
94 | |
95 // Now, why is int->oop OK? We end up declaring a raw-pointer as an oop | |
96 // and in general that's a bad thing. However, int->oop conversions only | |
97 // happen at GC points, so the lifetime of the misclassified raw-pointer | |
98 // is from the CheckCastPP (that converts it to an oop) backwards up | |
99 // through a merge point and into the slow-path call, and around the | |
100 // diamond up to the heap-top check and back down into the slow-path call. | |
101 // The misclassified raw pointer is NOT live across the slow-path call, | |
102 // and so does not appear in any GC info, so the fact that it is | |
103 // misclassified is OK. | |
104 | |
105 if( (lrg1->_is_oop || !lrg2->_is_oop) && // not an oop->int cast AND | |
106 // Compatible final mask | |
107 lrg1->mask().overlap( lrg2->mask() ) ) { | |
108 // Merge larger into smaller. | |
109 if( lr1 > lr2 ) { | |
110 uint tmp = lr1; lr1 = lr2; lr2 = tmp; | |
111 Node *n = n1; n1 = n2; n2 = n; | |
112 LRG *ltmp = lrg1; lrg1 = lrg2; lrg2 = ltmp; | |
113 } | |
114 // Union lr2 into lr1 | |
115 _phc.Union( n1, n2 ); | |
116 if (lrg1->_maxfreq < lrg2->_maxfreq) | |
117 lrg1->_maxfreq = lrg2->_maxfreq; | |
118 // Merge in the IFG | |
119 _phc._ifg->Union( lr1, lr2 ); | |
120 // Combine register restrictions | |
121 lrg1->AND(lrg2->mask()); | |
122 } | |
123 } | |
124 } | |
125 | |
126 // Copy coalescing | |
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127 void PhaseCoalesce::coalesce_driver() { |
0 | 128 verify(); |
129 // Coalesce from high frequency to low | |
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130 for (uint i = 0; i < _phc._cfg.number_of_blocks(); i++) { |
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131 coalesce(_phc._blks[i]); |
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132 } |
0 | 133 } |
134 | |
135 // I am inserting copies to come out of SSA form. In the general case, I am | |
136 // doing a parallel renaming. I'm in the Named world now, so I can't do a | |
137 // general parallel renaming. All the copies now use "names" (live-ranges) | |
138 // to carry values instead of the explicit use-def chains. Suppose I need to | |
139 // insert 2 copies into the same block. They copy L161->L128 and L128->L132. | |
140 // If I insert them in the wrong order then L128 will get clobbered before it | |
141 // can get used by the second copy. This cannot happen in the SSA model; | |
142 // direct use-def chains get me the right value. It DOES happen in the named | |
143 // model so I have to handle the reordering of copies. | |
144 // | |
145 // In general, I need to topo-sort the placed copies to avoid conflicts. | |
146 // Its possible to have a closed cycle of copies (e.g., recirculating the same | |
147 // values around a loop). In this case I need a temp to break the cycle. | |
148 void PhaseAggressiveCoalesce::insert_copy_with_overlap( Block *b, Node *copy, uint dst_name, uint src_name ) { | |
149 | |
150 // Scan backwards for the locations of the last use of the dst_name. | |
151 // I am about to clobber the dst_name, so the copy must be inserted | |
152 // after the last use. Last use is really first-use on a backwards scan. | |
153 uint i = b->end_idx()-1; | |
10111 | 154 while(1) { |
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155 Node *n = b->get_node(i); |
0 | 156 // Check for end of virtual copies; this is also the end of the |
157 // parallel renaming effort. | |
10111 | 158 if (n->_idx < _unique) { |
159 break; | |
160 } | |
0 | 161 uint idx = n->is_Copy(); |
3842 | 162 assert( idx || n->is_Con() || n->is_MachProj(), "Only copies during parallel renaming" ); |
10111 | 163 if (idx && _phc._lrg_map.find(n->in(idx)) == dst_name) { |
164 break; | |
165 } | |
0 | 166 i--; |
167 } | |
168 uint last_use_idx = i; | |
169 | |
170 // Also search for any kill of src_name that exits the block. | |
171 // Since the copy uses src_name, I have to come before any kill. | |
172 uint kill_src_idx = b->end_idx(); | |
173 // There can be only 1 kill that exits any block and that is | |
174 // the last kill. Thus it is the first kill on a backwards scan. | |
175 i = b->end_idx()-1; | |
10111 | 176 while (1) { |
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177 Node *n = b->get_node(i); |
0 | 178 // Check for end of virtual copies; this is also the end of the |
179 // parallel renaming effort. | |
10111 | 180 if (n->_idx < _unique) { |
181 break; | |
182 } | |
3842 | 183 assert( n->is_Copy() || n->is_Con() || n->is_MachProj(), "Only copies during parallel renaming" ); |
10111 | 184 if (_phc._lrg_map.find(n) == src_name) { |
0 | 185 kill_src_idx = i; |
186 break; | |
187 } | |
188 i--; | |
189 } | |
190 // Need a temp? Last use of dst comes after the kill of src? | |
10111 | 191 if (last_use_idx >= kill_src_idx) { |
0 | 192 // Need to break a cycle with a temp |
193 uint idx = copy->is_Copy(); | |
194 Node *tmp = copy->clone(); | |
10111 | 195 uint max_lrg_id = _phc._lrg_map.max_lrg_id(); |
196 _phc.new_lrg(tmp, max_lrg_id); | |
197 _phc._lrg_map.set_max_lrg_id(max_lrg_id + 1); | |
198 | |
0 | 199 // Insert new temp between copy and source |
200 tmp ->set_req(idx,copy->in(idx)); | |
201 copy->set_req(idx,tmp); | |
202 // Save source in temp early, before source is killed | |
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203 b->insert_node(tmp, kill_src_idx); |
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204 _phc._cfg.map_node_to_block(tmp, b); |
0 | 205 last_use_idx++; |
206 } | |
207 | |
208 // Insert just after last use | |
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209 b->insert_node(copy, last_use_idx + 1); |
0 | 210 } |
211 | |
212 void PhaseAggressiveCoalesce::insert_copies( Matcher &matcher ) { | |
213 // We do LRGs compressing and fix a liveout data only here since the other | |
214 // place in Split() is guarded by the assert which we never hit. | |
10111 | 215 _phc._lrg_map.compress_uf_map_for_nodes(); |
0 | 216 // Fix block's liveout data for compressed live ranges. |
10111 | 217 for (uint lrg = 1; lrg < _phc._lrg_map.max_lrg_id(); lrg++) { |
218 uint compressed_lrg = _phc._lrg_map.find(lrg); | |
219 if (lrg != compressed_lrg) { | |
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220 for (uint bidx = 0; bidx < _phc._cfg.number_of_blocks(); bidx++) { |
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221 IndexSet *liveout = _phc._live->live(_phc._cfg.get_block(bidx)); |
10111 | 222 if (liveout->member(lrg)) { |
0 | 223 liveout->remove(lrg); |
224 liveout->insert(compressed_lrg); | |
225 } | |
226 } | |
227 } | |
228 } | |
229 | |
230 // All new nodes added are actual copies to replace virtual copies. | |
231 // Nodes with index less than '_unique' are original, non-virtual Nodes. | |
232 _unique = C->unique(); | |
233 | |
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234 for (uint i = 0; i < _phc._cfg.number_of_blocks(); i++) { |
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235 C->check_node_count(NodeLimitFudgeFactor, "out of nodes in coalesce"); |
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236 if (C->failing()) return; |
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237 Block *b = _phc._cfg.get_block(i); |
0 | 238 uint cnt = b->num_preds(); // Number of inputs to the Phi |
239 | |
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240 for( uint l = 1; l<b->number_of_nodes(); l++ ) { |
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241 Node *n = b->get_node(l); |
0 | 242 |
243 // Do not use removed-copies, use copied value instead | |
244 uint ncnt = n->req(); | |
245 for( uint k = 1; k<ncnt; k++ ) { | |
246 Node *copy = n->in(k); | |
247 uint cidx = copy->is_Copy(); | |
248 if( cidx ) { | |
249 Node *def = copy->in(cidx); | |
10111 | 250 if (_phc._lrg_map.find(copy) == _phc._lrg_map.find(def)) { |
251 n->set_req(k, def); | |
252 } | |
0 | 253 } |
254 } | |
255 | |
256 // Remove any explicit copies that get coalesced. | |
257 uint cidx = n->is_Copy(); | |
258 if( cidx ) { | |
259 Node *def = n->in(cidx); | |
10111 | 260 if (_phc._lrg_map.find(n) == _phc._lrg_map.find(def)) { |
0 | 261 n->replace_by(def); |
262 n->set_req(cidx,NULL); | |
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263 b->remove_node(l); |
0 | 264 l--; |
265 continue; | |
266 } | |
267 } | |
268 | |
10111 | 269 if (n->is_Phi()) { |
0 | 270 // Get the chosen name for the Phi |
10111 | 271 uint phi_name = _phc._lrg_map.find(n); |
0 | 272 // Ignore the pre-allocated specials |
10111 | 273 if (!phi_name) { |
274 continue; | |
275 } | |
0 | 276 // Check for mismatch inputs to Phi |
10111 | 277 for (uint j = 1; j < cnt; j++) { |
0 | 278 Node *m = n->in(j); |
10111 | 279 uint src_name = _phc._lrg_map.find(m); |
280 if (src_name != phi_name) { | |
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281 Block *pred = _phc._cfg.get_block_for_node(b->pred(j)); |
0 | 282 Node *copy; |
283 assert(!m->is_Con() || m->is_Mach(), "all Con must be Mach"); | |
284 // Rematerialize constants instead of copying them | |
285 if( m->is_Mach() && m->as_Mach()->is_Con() && | |
286 m->as_Mach()->rematerialize() ) { | |
287 copy = m->clone(); | |
288 // Insert the copy in the predecessor basic block | |
289 pred->add_inst(copy); | |
290 // Copy any flags as well | |
10111 | 291 _phc.clone_projs(pred, pred->end_idx(), m, copy, _phc._lrg_map); |
0 | 292 } else { |
293 const RegMask *rm = C->matcher()->idealreg2spillmask[m->ideal_reg()]; | |
14909 | 294 copy = new (C) MachSpillCopyNode(m, *rm, *rm); |
0 | 295 // Find a good place to insert. Kinda tricky, use a subroutine |
296 insert_copy_with_overlap(pred,copy,phi_name,src_name); | |
297 } | |
298 // Insert the copy in the use-def chain | |
10111 | 299 n->set_req(j, copy); |
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300 _phc._cfg.map_node_to_block(copy, pred); |
0 | 301 // Extend ("register allocate") the names array for the copy. |
10111 | 302 _phc._lrg_map.extend(copy->_idx, phi_name); |
0 | 303 } // End of if Phi names do not match |
304 } // End of for all inputs to Phi | |
305 } else { // End of if Phi | |
306 | |
307 // Now check for 2-address instructions | |
308 uint idx; | |
309 if( n->is_Mach() && (idx=n->as_Mach()->two_adr()) ) { | |
310 // Get the chosen name for the Node | |
10111 | 311 uint name = _phc._lrg_map.find(n); |
312 assert (name, "no 2-address specials"); | |
0 | 313 // Check for name mis-match on the 2-address input |
314 Node *m = n->in(idx); | |
10111 | 315 if (_phc._lrg_map.find(m) != name) { |
0 | 316 Node *copy; |
317 assert(!m->is_Con() || m->is_Mach(), "all Con must be Mach"); | |
318 // At this point it is unsafe to extend live ranges (6550579). | |
319 // Rematerialize only constants as we do for Phi above. | |
10111 | 320 if(m->is_Mach() && m->as_Mach()->is_Con() && |
321 m->as_Mach()->rematerialize()) { | |
0 | 322 copy = m->clone(); |
323 // Insert the copy in the basic block, just before us | |
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324 b->insert_node(copy, l++); |
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325 l += _phc.clone_projs(b, l, m, copy, _phc._lrg_map); |
0 | 326 } else { |
327 const RegMask *rm = C->matcher()->idealreg2spillmask[m->ideal_reg()]; | |
14909 | 328 copy = new (C) MachSpillCopyNode(m, *rm, *rm); |
0 | 329 // Insert the copy in the basic block, just before us |
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330 b->insert_node(copy, l++); |
0 | 331 } |
332 // Insert the copy in the use-def chain | |
10111 | 333 n->set_req(idx, copy); |
0 | 334 // Extend ("register allocate") the names array for the copy. |
10111 | 335 _phc._lrg_map.extend(copy->_idx, name); |
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336 _phc._cfg.map_node_to_block(copy, b); |
0 | 337 } |
338 | |
339 } // End of is two-adr | |
340 | |
341 // Insert a copy at a debug use for a lrg which has high frequency | |
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342 if (b->_freq < OPTO_DEBUG_SPLIT_FREQ || _phc._cfg.is_uncommon(b)) { |
0 | 343 // Walk the debug inputs to the node and check for lrg freq |
344 JVMState* jvms = n->jvms(); | |
345 uint debug_start = jvms ? jvms->debug_start() : 999999; | |
346 uint debug_end = jvms ? jvms->debug_end() : 999999; | |
347 for(uint inpidx = debug_start; inpidx < debug_end; inpidx++) { | |
348 // Do not split monitors; they are only needed for debug table | |
349 // entries and need no code. | |
10111 | 350 if (jvms->is_monitor_use(inpidx)) { |
351 continue; | |
352 } | |
0 | 353 Node *inp = n->in(inpidx); |
10111 | 354 uint nidx = _phc._lrg_map.live_range_id(inp); |
0 | 355 LRG &lrg = lrgs(nidx); |
356 | |
357 // If this lrg has a high frequency use/def | |
673 | 358 if( lrg._maxfreq >= _phc.high_frequency_lrg() ) { |
0 | 359 // If the live range is also live out of this block (like it |
360 // would be for a fast/slow idiom), the normal spill mechanism | |
361 // does an excellent job. If it is not live out of this block | |
362 // (like it would be for debug info to uncommon trap) splitting | |
363 // the live range now allows a better allocation in the high | |
364 // frequency blocks. | |
365 // Build_IFG_virtual has converted the live sets to | |
366 // live-IN info, not live-OUT info. | |
367 uint k; | |
368 for( k=0; k < b->_num_succs; k++ ) | |
369 if( _phc._live->live(b->_succs[k])->member( nidx ) ) | |
370 break; // Live in to some successor block? | |
371 if( k < b->_num_succs ) | |
372 continue; // Live out; do not pre-split | |
373 // Split the lrg at this use | |
374 const RegMask *rm = C->matcher()->idealreg2spillmask[inp->ideal_reg()]; | |
14909 | 375 Node *copy = new (C) MachSpillCopyNode( inp, *rm, *rm ); |
0 | 376 // Insert the copy in the use-def chain |
377 n->set_req(inpidx, copy ); | |
378 // Insert the copy in the basic block, just before us | |
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379 b->insert_node(copy, l++); |
0 | 380 // Extend ("register allocate") the names array for the copy. |
10111 | 381 uint max_lrg_id = _phc._lrg_map.max_lrg_id(); |
382 _phc.new_lrg(copy, max_lrg_id); | |
383 _phc._lrg_map.set_max_lrg_id(max_lrg_id + 1); | |
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384 _phc._cfg.map_node_to_block(copy, b); |
0 | 385 //tty->print_cr("Split a debug use in Aggressive Coalesce"); |
386 } // End of if high frequency use/def | |
387 } // End of for all debug inputs | |
388 } // End of if low frequency safepoint | |
389 | |
390 } // End of if Phi | |
391 | |
392 } // End of for all instructions | |
393 } // End of for all blocks | |
394 } | |
395 | |
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396 |
0 | 397 // Aggressive (but pessimistic) copy coalescing of a single block |
398 | |
399 // The following coalesce pass represents a single round of aggressive | |
400 // pessimistic coalesce. "Aggressive" means no attempt to preserve | |
401 // colorability when coalescing. This occasionally means more spills, but | |
402 // it also means fewer rounds of coalescing for better code - and that means | |
403 // faster compiles. | |
404 | |
405 // "Pessimistic" means we do not hit the fixed point in one pass (and we are | |
406 // reaching for the least fixed point to boot). This is typically solved | |
407 // with a few more rounds of coalescing, but the compiler must run fast. We | |
408 // could optimistically coalescing everything touching PhiNodes together | |
409 // into one big live range, then check for self-interference. Everywhere | |
410 // the live range interferes with self it would have to be split. Finding | |
411 // the right split points can be done with some heuristics (based on | |
412 // expected frequency of edges in the live range). In short, it's a real | |
413 // research problem and the timeline is too short to allow such research. | |
414 // Further thoughts: (1) build the LR in a pass, (2) find self-interference | |
415 // in another pass, (3) per each self-conflict, split, (4) split by finding | |
416 // the low-cost cut (min-cut) of the LR, (5) edges in the LR are weighted | |
417 // according to the GCM algorithm (or just exec freq on CFG edges). | |
418 | |
419 void PhaseAggressiveCoalesce::coalesce( Block *b ) { | |
420 // Copies are still "virtual" - meaning we have not made them explicitly | |
421 // copies. Instead, Phi functions of successor blocks have mis-matched | |
422 // live-ranges. If I fail to coalesce, I'll have to insert a copy to line | |
423 // up the live-ranges. Check for Phis in successor blocks. | |
424 uint i; | |
425 for( i=0; i<b->_num_succs; i++ ) { | |
426 Block *bs = b->_succs[i]; | |
427 // Find index of 'b' in 'bs' predecessors | |
428 uint j=1; | |
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429 while (_phc._cfg.get_block_for_node(bs->pred(j)) != b) { |
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430 j++; |
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431 } |
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432 |
0 | 433 // Visit all the Phis in successor block |
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434 for( uint k = 1; k<bs->number_of_nodes(); k++ ) { |
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435 Node *n = bs->get_node(k); |
0 | 436 if( !n->is_Phi() ) break; |
437 combine_these_two( n, n->in(j) ); | |
438 } | |
439 } // End of for all successor blocks | |
440 | |
441 | |
442 // Check _this_ block for 2-address instructions and copies. | |
443 uint cnt = b->end_idx(); | |
444 for( i = 1; i<cnt; i++ ) { | |
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445 Node *n = b->get_node(i); |
0 | 446 uint idx; |
447 // 2-address instructions have a virtual Copy matching their input | |
448 // to their output | |
10111 | 449 if (n->is_Mach() && (idx = n->as_Mach()->two_adr())) { |
0 | 450 MachNode *mach = n->as_Mach(); |
10111 | 451 combine_these_two(mach, mach->in(idx)); |
0 | 452 } |
453 } // End of for all instructions in block | |
454 } | |
455 | |
10111 | 456 PhaseConservativeCoalesce::PhaseConservativeCoalesce(PhaseChaitin &chaitin) : PhaseCoalesce(chaitin) { |
457 _ulr.initialize(_phc._lrg_map.max_lrg_id()); | |
0 | 458 } |
459 | |
460 void PhaseConservativeCoalesce::verify() { | |
461 #ifdef ASSERT | |
462 _phc.set_was_low(); | |
463 #endif | |
464 } | |
465 | |
466 void PhaseConservativeCoalesce::union_helper( Node *lr1_node, Node *lr2_node, uint lr1, uint lr2, Node *src_def, Node *dst_copy, Node *src_copy, Block *b, uint bindex ) { | |
467 // Join live ranges. Merge larger into smaller. Union lr2 into lr1 in the | |
468 // union-find tree | |
469 _phc.Union( lr1_node, lr2_node ); | |
470 | |
471 // Single-def live range ONLY if both live ranges are single-def. | |
472 // If both are single def, then src_def powers one live range | |
473 // and def_copy powers the other. After merging, src_def powers | |
474 // the combined live range. | |
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475 lrgs(lr1)._def = (lrgs(lr1).is_multidef() || |
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476 lrgs(lr2).is_multidef() ) |
0 | 477 ? NodeSentinel : src_def; |
478 lrgs(lr2)._def = NULL; // No def for lrg 2 | |
479 lrgs(lr2).Clear(); // Force empty mask for LRG 2 | |
480 //lrgs(lr2)._size = 0; // Live-range 2 goes dead | |
481 lrgs(lr1)._is_oop |= lrgs(lr2)._is_oop; | |
482 lrgs(lr2)._is_oop = 0; // In particular, not an oop for GC info | |
483 | |
484 if (lrgs(lr1)._maxfreq < lrgs(lr2)._maxfreq) | |
485 lrgs(lr1)._maxfreq = lrgs(lr2)._maxfreq; | |
486 | |
487 // Copy original value instead. Intermediate copies go dead, and | |
488 // the dst_copy becomes useless. | |
489 int didx = dst_copy->is_Copy(); | |
490 dst_copy->set_req( didx, src_def ); | |
491 // Add copy to free list | |
492 // _phc.free_spillcopy(b->_nodes[bindex]); | |
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493 assert( b->get_node(bindex) == dst_copy, "" ); |
0 | 494 dst_copy->replace_by( dst_copy->in(didx) ); |
495 dst_copy->set_req( didx, NULL); | |
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496 b->remove_node(bindex); |
0 | 497 if( bindex < b->_ihrp_index ) b->_ihrp_index--; |
498 if( bindex < b->_fhrp_index ) b->_fhrp_index--; | |
499 | |
500 // Stretched lr1; add it to liveness of intermediate blocks | |
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501 Block *b2 = _phc._cfg.get_block_for_node(src_copy); |
0 | 502 while( b != b2 ) { |
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503 b = _phc._cfg.get_block_for_node(b->pred(1)); |
0 | 504 _phc._live->live(b)->insert(lr1); |
505 } | |
506 } | |
507 | |
508 // Factored code from copy_copy that computes extra interferences from | |
509 // lengthening a live range by double-coalescing. | |
510 uint PhaseConservativeCoalesce::compute_separating_interferences(Node *dst_copy, Node *src_copy, Block *b, uint bindex, RegMask &rm, uint reg_degree, uint rm_size, uint lr1, uint lr2 ) { | |
511 | |
512 assert(!lrgs(lr1)._fat_proj, "cannot coalesce fat_proj"); | |
513 assert(!lrgs(lr2)._fat_proj, "cannot coalesce fat_proj"); | |
514 Node *prev_copy = dst_copy->in(dst_copy->is_Copy()); | |
515 Block *b2 = b; | |
516 uint bindex2 = bindex; | |
517 while( 1 ) { | |
518 // Find previous instruction | |
519 bindex2--; // Chain backwards 1 instruction | |
520 while( bindex2 == 0 ) { // At block start, find prior block | |
521 assert( b2->num_preds() == 2, "cannot double coalesce across c-flow" ); | |
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522 b2 = _phc._cfg.get_block_for_node(b2->pred(1)); |
0 | 523 bindex2 = b2->end_idx()-1; |
524 } | |
525 // Get prior instruction | |
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526 assert(bindex2 < b2->number_of_nodes(), "index out of bounds"); |
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527 Node *x = b2->get_node(bindex2); |
0 | 528 if( x == prev_copy ) { // Previous copy in copy chain? |
529 if( prev_copy == src_copy)// Found end of chain and all interferences | |
530 break; // So break out of loop | |
531 // Else work back one in copy chain | |
532 prev_copy = prev_copy->in(prev_copy->is_Copy()); | |
533 } else { // Else collect interferences | |
10111 | 534 uint lidx = _phc._lrg_map.find(x); |
0 | 535 // Found another def of live-range being stretched? |
10111 | 536 if(lidx == lr1) { |
537 return max_juint; | |
538 } | |
539 if(lidx == lr2) { | |
540 return max_juint; | |
541 } | |
0 | 542 |
543 // If we attempt to coalesce across a bound def | |
544 if( lrgs(lidx).is_bound() ) { | |
545 // Do not let the coalesced LRG expect to get the bound color | |
546 rm.SUBTRACT( lrgs(lidx).mask() ); | |
547 // Recompute rm_size | |
548 rm_size = rm.Size(); | |
549 //if( rm._flags ) rm_size += 1000000; | |
550 if( reg_degree >= rm_size ) return max_juint; | |
551 } | |
552 if( rm.overlap(lrgs(lidx).mask()) ) { | |
553 // Insert lidx into union LRG; returns TRUE if actually inserted | |
554 if( _ulr.insert(lidx) ) { | |
555 // Infinite-stack neighbors do not alter colorability, as they | |
556 // can always color to some other color. | |
557 if( !lrgs(lidx).mask().is_AllStack() ) { | |
558 // If this coalesce will make any new neighbor uncolorable, | |
559 // do not coalesce. | |
560 if( lrgs(lidx).just_lo_degree() ) | |
561 return max_juint; | |
562 // Bump our degree | |
563 if( ++reg_degree >= rm_size ) | |
564 return max_juint; | |
565 } // End of if not infinite-stack neighbor | |
566 } // End of if actually inserted | |
567 } // End of if live range overlaps | |
605 | 568 } // End of else collect interferences for 1 node |
569 } // End of while forever, scan back for interferences | |
0 | 570 return reg_degree; |
571 } | |
572 | |
573 void PhaseConservativeCoalesce::update_ifg(uint lr1, uint lr2, IndexSet *n_lr1, IndexSet *n_lr2) { | |
574 // Some original neighbors of lr1 might have gone away | |
575 // because the constrained register mask prevented them. | |
576 // Remove lr1 from such neighbors. | |
577 IndexSetIterator one(n_lr1); | |
578 uint neighbor; | |
579 LRG &lrg1 = lrgs(lr1); | |
580 while ((neighbor = one.next()) != 0) | |
581 if( !_ulr.member(neighbor) ) | |
582 if( _phc._ifg->neighbors(neighbor)->remove(lr1) ) | |
583 lrgs(neighbor).inc_degree( -lrg1.compute_degree(lrgs(neighbor)) ); | |
584 | |
585 | |
586 // lr2 is now called (coalesced into) lr1. | |
587 // Remove lr2 from the IFG. | |
588 IndexSetIterator two(n_lr2); | |
589 LRG &lrg2 = lrgs(lr2); | |
590 while ((neighbor = two.next()) != 0) | |
591 if( _phc._ifg->neighbors(neighbor)->remove(lr2) ) | |
592 lrgs(neighbor).inc_degree( -lrg2.compute_degree(lrgs(neighbor)) ); | |
593 | |
594 // Some neighbors of intermediate copies now interfere with the | |
595 // combined live range. | |
596 IndexSetIterator three(&_ulr); | |
597 while ((neighbor = three.next()) != 0) | |
598 if( _phc._ifg->neighbors(neighbor)->insert(lr1) ) | |
599 lrgs(neighbor).inc_degree( lrg1.compute_degree(lrgs(neighbor)) ); | |
600 } | |
601 | |
602 static void record_bias( const PhaseIFG *ifg, int lr1, int lr2 ) { | |
603 // Tag copy bias here | |
604 if( !ifg->lrgs(lr1)._copy_bias ) | |
605 ifg->lrgs(lr1)._copy_bias = lr2; | |
606 if( !ifg->lrgs(lr2)._copy_bias ) | |
607 ifg->lrgs(lr2)._copy_bias = lr1; | |
608 } | |
609 | |
610 // See if I can coalesce a series of multiple copies together. I need the | |
611 // final dest copy and the original src copy. They can be the same Node. | |
612 // Compute the compatible register masks. | |
10111 | 613 bool PhaseConservativeCoalesce::copy_copy(Node *dst_copy, Node *src_copy, Block *b, uint bindex) { |
0 | 614 |
10111 | 615 if (!dst_copy->is_SpillCopy()) { |
616 return false; | |
617 } | |
618 if (!src_copy->is_SpillCopy()) { | |
619 return false; | |
620 } | |
0 | 621 Node *src_def = src_copy->in(src_copy->is_Copy()); |
10111 | 622 uint lr1 = _phc._lrg_map.find(dst_copy); |
623 uint lr2 = _phc._lrg_map.find(src_def); | |
0 | 624 |
625 // Same live ranges already? | |
10111 | 626 if (lr1 == lr2) { |
627 return false; | |
628 } | |
0 | 629 |
630 // Interfere? | |
10111 | 631 if (_phc._ifg->test_edge_sq(lr1, lr2)) { |
632 return false; | |
633 } | |
0 | 634 |
635 // Not an oop->int cast; oop->oop, int->int, AND int->oop are OK. | |
10111 | 636 if (!lrgs(lr1)._is_oop && lrgs(lr2)._is_oop) { // not an oop->int cast |
0 | 637 return false; |
10111 | 638 } |
0 | 639 |
640 // Coalescing between an aligned live range and a mis-aligned live range? | |
641 // No, no! Alignment changes how we count degree. | |
10111 | 642 if (lrgs(lr1)._fat_proj != lrgs(lr2)._fat_proj) { |
0 | 643 return false; |
10111 | 644 } |
0 | 645 |
646 // Sort; use smaller live-range number | |
647 Node *lr1_node = dst_copy; | |
648 Node *lr2_node = src_def; | |
10111 | 649 if (lr1 > lr2) { |
0 | 650 uint tmp = lr1; lr1 = lr2; lr2 = tmp; |
651 lr1_node = src_def; lr2_node = dst_copy; | |
652 } | |
653 | |
654 // Check for compatibility of the 2 live ranges by | |
655 // intersecting their allowed register sets. | |
656 RegMask rm = lrgs(lr1).mask(); | |
657 rm.AND(lrgs(lr2).mask()); | |
658 // Number of bits free | |
659 uint rm_size = rm.Size(); | |
660 | |
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661 if (UseFPUForSpilling && rm.is_AllStack() ) { |
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662 // Don't coalesce when frequency difference is large |
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663 Block *dst_b = _phc._cfg.get_block_for_node(dst_copy); |
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664 Block *src_def_b = _phc._cfg.get_block_for_node(src_def); |
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665 if (src_def_b->_freq > 10*dst_b->_freq ) |
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666 return false; |
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667 } |
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668 |
0 | 669 // If we can use any stack slot, then effective size is infinite |
670 if( rm.is_AllStack() ) rm_size += 1000000; | |
671 // Incompatible masks, no way to coalesce | |
672 if( rm_size == 0 ) return false; | |
673 | |
674 // Another early bail-out test is when we are double-coalescing and the | |
605 | 675 // 2 copies are separated by some control flow. |
0 | 676 if( dst_copy != src_copy ) { |
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677 Block *src_b = _phc._cfg.get_block_for_node(src_copy); |
0 | 678 Block *b2 = b; |
679 while( b2 != src_b ) { | |
680 if( b2->num_preds() > 2 ){// Found merge-point | |
681 _phc._lost_opp_cflow_coalesce++; | |
682 // extra record_bias commented out because Chris believes it is not | |
683 // productive. Since we can record only 1 bias, we want to choose one | |
684 // that stands a chance of working and this one probably does not. | |
685 //record_bias( _phc._lrgs, lr1, lr2 ); | |
686 return false; // To hard to find all interferences | |
687 } | |
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688 b2 = _phc._cfg.get_block_for_node(b2->pred(1)); |
0 | 689 } |
690 } | |
691 | |
692 // Union the two interference sets together into '_ulr' | |
693 uint reg_degree = _ulr.lrg_union( lr1, lr2, rm_size, _phc._ifg, rm ); | |
694 | |
695 if( reg_degree >= rm_size ) { | |
696 record_bias( _phc._ifg, lr1, lr2 ); | |
697 return false; | |
698 } | |
699 | |
700 // Now I need to compute all the interferences between dst_copy and | |
701 // src_copy. I'm not willing visit the entire interference graph, so | |
702 // I limit my search to things in dst_copy's block or in a straight | |
703 // line of previous blocks. I give up at merge points or when I get | |
704 // more interferences than my degree. I can stop when I find src_copy. | |
705 if( dst_copy != src_copy ) { | |
706 reg_degree = compute_separating_interferences(dst_copy, src_copy, b, bindex, rm, rm_size, reg_degree, lr1, lr2 ); | |
707 if( reg_degree == max_juint ) { | |
708 record_bias( _phc._ifg, lr1, lr2 ); | |
709 return false; | |
710 } | |
711 } // End of if dst_copy & src_copy are different | |
712 | |
713 | |
714 // ---- THE COMBINED LRG IS COLORABLE ---- | |
715 | |
716 // YEAH - Now coalesce this copy away | |
717 assert( lrgs(lr1).num_regs() == lrgs(lr2).num_regs(), "" ); | |
718 | |
719 IndexSet *n_lr1 = _phc._ifg->neighbors(lr1); | |
720 IndexSet *n_lr2 = _phc._ifg->neighbors(lr2); | |
721 | |
722 // Update the interference graph | |
723 update_ifg(lr1, lr2, n_lr1, n_lr2); | |
724 | |
725 _ulr.remove(lr1); | |
726 | |
727 // Uncomment the following code to trace Coalescing in great detail. | |
728 // | |
729 //if (false) { | |
730 // tty->cr(); | |
731 // tty->print_cr("#######################################"); | |
732 // tty->print_cr("union %d and %d", lr1, lr2); | |
733 // n_lr1->dump(); | |
734 // n_lr2->dump(); | |
735 // tty->print_cr("resulting set is"); | |
736 // _ulr.dump(); | |
737 //} | |
738 | |
739 // Replace n_lr1 with the new combined live range. _ulr will use | |
740 // n_lr1's old memory on the next iteration. n_lr2 is cleared to | |
741 // send its internal memory to the free list. | |
742 _ulr.swap(n_lr1); | |
743 _ulr.clear(); | |
744 n_lr2->clear(); | |
745 | |
746 lrgs(lr1).set_degree( _phc._ifg->effective_degree(lr1) ); | |
747 lrgs(lr2).set_degree( 0 ); | |
748 | |
749 // Join live ranges. Merge larger into smaller. Union lr2 into lr1 in the | |
750 // union-find tree | |
751 union_helper( lr1_node, lr2_node, lr1, lr2, src_def, dst_copy, src_copy, b, bindex ); | |
752 // Combine register restrictions | |
753 lrgs(lr1).set_mask(rm); | |
754 lrgs(lr1).compute_set_mask_size(); | |
755 lrgs(lr1)._cost += lrgs(lr2)._cost; | |
756 lrgs(lr1)._area += lrgs(lr2)._area; | |
757 | |
758 // While its uncommon to successfully coalesce live ranges that started out | |
759 // being not-lo-degree, it can happen. In any case the combined coalesced | |
760 // live range better Simplify nicely. | |
761 lrgs(lr1)._was_lo = 1; | |
762 | |
763 // kinda expensive to do all the time | |
764 //tty->print_cr("warning: slow verify happening"); | |
765 //_phc._ifg->verify( &_phc ); | |
766 return true; | |
767 } | |
768 | |
769 // Conservative (but pessimistic) copy coalescing of a single block | |
770 void PhaseConservativeCoalesce::coalesce( Block *b ) { | |
771 // Bail out on infrequent blocks | |
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772 if (_phc._cfg.is_uncommon(b)) { |
0 | 773 return; |
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8022284: Hide internal data structure in PhaseCFG
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774 } |
0 | 775 // Check this block for copies. |
776 for( uint i = 1; i<b->end_idx(); i++ ) { | |
777 // Check for actual copies on inputs. Coalesce a copy into its | |
778 // input if use and copy's input are compatible. | |
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8023691: Create interface for nodes in class Block
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779 Node *copy1 = b->get_node(i); |
0 | 780 uint idx1 = copy1->is_Copy(); |
781 if( !idx1 ) continue; // Not a copy | |
782 | |
783 if( copy_copy(copy1,copy1,b,i) ) { | |
784 i--; // Retry, same location in block | |
785 PhaseChaitin::_conserv_coalesce++; // Collect stats on success | |
786 continue; | |
787 } | |
788 } | |
789 } |