1 /*
2 * Copyright 1998-2006 Sun Microsystems, Inc. All Rights Reserved.
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 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 #include "incls/_precompiled.incl"
26 #include "incls/_ifg.cpp.incl"
27
28 #define EXACT_PRESSURE 1
29
30 //=============================================================================
31 //------------------------------IFG--------------------------------------------
32 PhaseIFG::PhaseIFG( Arena *arena ) : Phase(Interference_Graph), _arena(arena) {
33 }
34
35 //------------------------------init-------------------------------------------
36 void PhaseIFG::init( uint maxlrg ) {
37 _maxlrg = maxlrg;
38 _yanked = new (_arena) VectorSet(_arena);
39 _is_square = false;
40 // Make uninitialized adjacency lists
41 _adjs = (IndexSet*)_arena->Amalloc(sizeof(IndexSet)*maxlrg);
42 // Also make empty live range structures
43 _lrgs = (LRG *)_arena->Amalloc( maxlrg * sizeof(LRG) );
44 memset(_lrgs,0,sizeof(LRG)*maxlrg);
45 // Init all to empty
46 for( uint i = 0; i < maxlrg; i++ ) {
47 _adjs[i].initialize(maxlrg);
48 _lrgs[i].Set_All();
49 }
50 }
51
52 //------------------------------add--------------------------------------------
53 // Add edge between vertices a & b. These are sorted (triangular matrix),
54 // then the smaller number is inserted in the larger numbered array.
55 int PhaseIFG::add_edge( uint a, uint b ) {
56 lrgs(a).invalid_degree();
57 lrgs(b).invalid_degree();
58 // Sort a and b, so that a is bigger
59 assert( !_is_square, "only on triangular" );
60 if( a < b ) { uint tmp = a; a = b; b = tmp; }
61 return _adjs[a].insert( b );
62 }
63
64 //------------------------------add_vector-------------------------------------
65 // Add an edge between 'a' and everything in the vector.
66 void PhaseIFG::add_vector( uint a, IndexSet *vec ) {
67 // IFG is triangular, so do the inserts where 'a' < 'b'.
68 assert( !_is_square, "only on triangular" );
69 IndexSet *adjs_a = &_adjs[a];
70 if( !vec->count() ) return;
71
72 IndexSetIterator elements(vec);
73 uint neighbor;
74 while ((neighbor = elements.next()) != 0) {
75 add_edge( a, neighbor );
76 }
77 }
78
79 //------------------------------test-------------------------------------------
80 // Is there an edge between a and b?
81 int PhaseIFG::test_edge( uint a, uint b ) const {
82 // Sort a and b, so that a is larger
83 assert( !_is_square, "only on triangular" );
84 if( a < b ) { uint tmp = a; a = b; b = tmp; }
85 return _adjs[a].member(b);
86 }
87
88 //------------------------------SquareUp---------------------------------------
89 // Convert triangular matrix to square matrix
90 void PhaseIFG::SquareUp() {
91 assert( !_is_square, "only on triangular" );
92
93 // Simple transpose
94 for( uint i = 0; i < _maxlrg; i++ ) {
95 IndexSetIterator elements(&_adjs[i]);
96 uint datum;
97 while ((datum = elements.next()) != 0) {
98 _adjs[datum].insert( i );
99 }
100 }
101 _is_square = true;
102 }
103
104 //------------------------------Compute_Effective_Degree-----------------------
105 // Compute effective degree in bulk
106 void PhaseIFG::Compute_Effective_Degree() {
107 assert( _is_square, "only on square" );
108
109 for( uint i = 0; i < _maxlrg; i++ )
110 lrgs(i).set_degree(effective_degree(i));
111 }
112
113 //------------------------------test_edge_sq-----------------------------------
114 int PhaseIFG::test_edge_sq( uint a, uint b ) const {
115 assert( _is_square, "only on square" );
116 // Swap, so that 'a' has the lesser count. Then binary search is on
117 // the smaller of a's list and b's list.
118 if( neighbor_cnt(a) > neighbor_cnt(b) ) { uint tmp = a; a = b; b = tmp; }
119 //return _adjs[a].unordered_member(b);
120 return _adjs[a].member(b);
121 }
122
123 //------------------------------Union------------------------------------------
124 // Union edges of B into A
125 void PhaseIFG::Union( uint a, uint b ) {
126 assert( _is_square, "only on square" );
127 IndexSet *A = &_adjs[a];
128 IndexSetIterator b_elements(&_adjs[b]);
129 uint datum;
130 while ((datum = b_elements.next()) != 0) {
131 if(A->insert(datum)) {
132 _adjs[datum].insert(a);
133 lrgs(a).invalid_degree();
134 lrgs(datum).invalid_degree();
135 }
136 }
137 }
138
139 //------------------------------remove_node------------------------------------
140 // Yank a Node and all connected edges from the IFG. Return a
141 // list of neighbors (edges) yanked.
142 IndexSet *PhaseIFG::remove_node( uint a ) {
143 assert( _is_square, "only on square" );
144 assert( !_yanked->test(a), "" );
145 _yanked->set(a);
146
147 // I remove the LRG from all neighbors.
148 IndexSetIterator elements(&_adjs[a]);
149 LRG &lrg_a = lrgs(a);
150 uint datum;
151 while ((datum = elements.next()) != 0) {
152 _adjs[datum].remove(a);
153 lrgs(datum).inc_degree( -lrg_a.compute_degree(lrgs(datum)) );
154 }
155 return neighbors(a);
156 }
157
158 //------------------------------re_insert--------------------------------------
159 // Re-insert a yanked Node.
160 void PhaseIFG::re_insert( uint a ) {
161 assert( _is_square, "only on square" );
162 assert( _yanked->test(a), "" );
163 (*_yanked) >>= a;
164
165 IndexSetIterator elements(&_adjs[a]);
166 uint datum;
167 while ((datum = elements.next()) != 0) {
168 _adjs[datum].insert(a);
169 lrgs(datum).invalid_degree();
170 }
171 }
172
173 //------------------------------compute_degree---------------------------------
174 // Compute the degree between 2 live ranges. If both live ranges are
175 // aligned-adjacent powers-of-2 then we use the MAX size. If either is
176 // mis-aligned (or for Fat-Projections, not-adjacent) then we have to
177 // MULTIPLY the sizes. Inspect Brigg's thesis on register pairs to see why
178 // this is so.
179 int LRG::compute_degree( LRG &l ) const {
180 int tmp;
181 int num_regs = _num_regs;
182 int nregs = l.num_regs();
183 tmp = (_fat_proj || l._fat_proj) // either is a fat-proj?
184 ? (num_regs * nregs) // then use product
185 : MAX2(num_regs,nregs); // else use max
186 return tmp;
187 }
188
189 //------------------------------effective_degree-------------------------------
190 // Compute effective degree for this live range. If both live ranges are
191 // aligned-adjacent powers-of-2 then we use the MAX size. If either is
192 // mis-aligned (or for Fat-Projections, not-adjacent) then we have to
193 // MULTIPLY the sizes. Inspect Brigg's thesis on register pairs to see why
194 // this is so.
195 int PhaseIFG::effective_degree( uint lidx ) const {
196 int eff = 0;
197 int num_regs = lrgs(lidx).num_regs();
198 int fat_proj = lrgs(lidx)._fat_proj;
199 IndexSet *s = neighbors(lidx);
200 IndexSetIterator elements(s);
201 uint nidx;
202 while((nidx = elements.next()) != 0) {
203 LRG &lrgn = lrgs(nidx);
204 int nregs = lrgn.num_regs();
205 eff += (fat_proj || lrgn._fat_proj) // either is a fat-proj?
206 ? (num_regs * nregs) // then use product
207 : MAX2(num_regs,nregs); // else use max
208 }
209 return eff;
210 }
211
212
213 #ifndef PRODUCT
214 //------------------------------dump-------------------------------------------
215 void PhaseIFG::dump() const {
216 tty->print_cr("-- Interference Graph --%s--",
217 _is_square ? "square" : "triangular" );
218 if( _is_square ) {
219 for( uint i = 0; i < _maxlrg; i++ ) {
220 tty->print( (*_yanked)[i] ? "XX " : " ");
221 tty->print("L%d: { ",i);
222 IndexSetIterator elements(&_adjs[i]);
223 uint datum;
224 while ((datum = elements.next()) != 0) {
225 tty->print("L%d ", datum);
226 }
227 tty->print_cr("}");
228
229 }
230 return;
231 }
232
233 // Triangular
234 for( uint i = 0; i < _maxlrg; i++ ) {
235 uint j;
236 tty->print( (*_yanked)[i] ? "XX " : " ");
237 tty->print("L%d: { ",i);
238 for( j = _maxlrg; j > i; j-- )
239 if( test_edge(j - 1,i) ) {
240 tty->print("L%d ",j - 1);
241 }
242 tty->print("| ");
243 IndexSetIterator elements(&_adjs[i]);
244 uint datum;
245 while ((datum = elements.next()) != 0) {
246 tty->print("L%d ", datum);
247 }
248 tty->print("}\n");
249 }
250 tty->print("\n");
251 }
252
253 //------------------------------stats------------------------------------------
254 void PhaseIFG::stats() const {
255 ResourceMark rm;
256 int *h_cnt = NEW_RESOURCE_ARRAY(int,_maxlrg*2);
257 memset( h_cnt, 0, sizeof(int)*_maxlrg*2 );
258 uint i;
259 for( i = 0; i < _maxlrg; i++ ) {
260 h_cnt[neighbor_cnt(i)]++;
261 }
262 tty->print_cr("--Histogram of counts--");
263 for( i = 0; i < _maxlrg*2; i++ )
264 if( h_cnt[i] )
265 tty->print("%d/%d ",i,h_cnt[i]);
266 tty->print_cr("");
267 }
268
269 //------------------------------verify-----------------------------------------
270 void PhaseIFG::verify( const PhaseChaitin *pc ) const {
271 // IFG is square, sorted and no need for Find
272 for( uint i = 0; i < _maxlrg; i++ ) {
273 assert(!((*_yanked)[i]) || !neighbor_cnt(i), "Is removed completely" );
274 IndexSet *set = &_adjs[i];
275 IndexSetIterator elements(set);
276 uint idx;
277 uint last = 0;
278 while ((idx = elements.next()) != 0) {
279 assert( idx != i, "Must have empty diagonal");
280 assert( pc->Find_const(idx) == idx, "Must not need Find" );
281 assert( _adjs[idx].member(i), "IFG not square" );
282 assert( !(*_yanked)[idx], "No yanked neighbors" );
283 assert( last < idx, "not sorted increasing");
284 last = idx;
285 }
286 assert( !lrgs(i)._degree_valid ||
287 effective_degree(i) == lrgs(i).degree(), "degree is valid but wrong" );
288 }
289 }
290 #endif
291
292 //------------------------------interfere_with_live----------------------------
293 // Interfere this register with everything currently live. Use the RegMasks
294 // to trim the set of possible interferences. Return a count of register-only
295 // inteferences as an estimate of register pressure.
296 void PhaseChaitin::interfere_with_live( uint r, IndexSet *liveout ) {
297 uint retval = 0;
298 // Interfere with everything live.
299 const RegMask &rm = lrgs(r).mask();
300 // Check for interference by checking overlap of regmasks.
301 // Only interfere if acceptable register masks overlap.
302 IndexSetIterator elements(liveout);
303 uint l;
304 while( (l = elements.next()) != 0 )
305 if( rm.overlap( lrgs(l).mask() ) )
306 _ifg->add_edge( r, l );
307 }
308
309 //------------------------------build_ifg_virtual------------------------------
310 // Actually build the interference graph. Uses virtual registers only, no
311 // physical register masks. This allows me to be very aggressive when
312 // coalescing copies. Some of this aggressiveness will have to be undone
313 // later, but I'd rather get all the copies I can now (since unremoved copies
314 // at this point can end up in bad places). Copies I re-insert later I have
315 // more opportunity to insert them in low-frequency locations.
316 void PhaseChaitin::build_ifg_virtual( ) {
317
318 // For all blocks (in any order) do...
319 for( uint i=0; i<_cfg._num_blocks; i++ ) {
320 Block *b = _cfg._blocks[i];
321 IndexSet *liveout = _live->live(b);
322
323 // The IFG is built by a single reverse pass over each basic block.
324 // Starting with the known live-out set, we remove things that get
325 // defined and add things that become live (essentially executing one
326 // pass of a standard LIVE analysis). Just before a Node defines a value
327 // (and removes it from the live-ness set) that value is certainly live.
328 // The defined value interferes with everything currently live. The
329 // value is then removed from the live-ness set and it's inputs are
330 // added to the live-ness set.
331 for( uint j = b->end_idx() + 1; j > 1; j-- ) {
332 Node *n = b->_nodes[j-1];
333
334 // Get value being defined
335 uint r = n2lidx(n);
336
337 // Some special values do not allocate
338 if( r ) {
339
340 // Remove from live-out set
341 liveout->remove(r);
342
343 // Copies do not define a new value and so do not interfere.
344 // Remove the copies source from the liveout set before interfering.
345 uint idx = n->is_Copy();
346 if( idx ) liveout->remove( n2lidx(n->in(idx)) );
347
348 // Interfere with everything live
349 interfere_with_live( r, liveout );
350 }
351
352 // Make all inputs live
353 if( !n->is_Phi() ) { // Phi function uses come from prior block
354 for( uint k = 1; k < n->req(); k++ )
355 liveout->insert( n2lidx(n->in(k)) );
356 }
357
358 // 2-address instructions always have the defined value live
359 // on entry to the instruction, even though it is being defined
360 // by the instruction. We pretend a virtual copy sits just prior
361 // to the instruction and kills the src-def'd register.
362 // In other words, for 2-address instructions the defined value
363 // interferes with all inputs.
364 uint idx;
365 if( n->is_Mach() && (idx = n->as_Mach()->two_adr()) ) {
366 const MachNode *mach = n->as_Mach();
367 // Sometimes my 2-address ADDs are commuted in a bad way.
368 // We generally want the USE-DEF register to refer to the
369 // loop-varying quantity, to avoid a copy.
370 uint op = mach->ideal_Opcode();
371 // Check that mach->num_opnds() == 3 to ensure instruction is
372 // not subsuming constants, effectively excludes addI_cin_imm
373 // Can NOT swap for instructions like addI_cin_imm since it
374 // is adding zero to yhi + carry and the second ideal-input
375 // points to the result of adding low-halves.
376 // Checking req() and num_opnds() does NOT distinguish addI_cout from addI_cout_imm
377 if( (op == Op_AddI && mach->req() == 3 && mach->num_opnds() == 3) &&
378 n->in(1)->bottom_type()->base() == Type::Int &&
379 // See if the ADD is involved in a tight data loop the wrong way
380 n->in(2)->is_Phi() &&
381 n->in(2)->in(2) == n ) {
382 Node *tmp = n->in(1);
383 n->set_req( 1, n->in(2) );
384 n->set_req( 2, tmp );
385 }
386 // Defined value interferes with all inputs
387 uint lidx = n2lidx(n->in(idx));
388 for( uint k = 1; k < n->req(); k++ ) {
389 uint kidx = n2lidx(n->in(k));
390 if( kidx != lidx )
391 _ifg->add_edge( r, kidx );
392 }
393 }
394 } // End of forall instructions in block
395 } // End of forall blocks
396 }
397
398 //------------------------------count_int_pressure-----------------------------
399 uint PhaseChaitin::count_int_pressure( IndexSet *liveout ) {
400 IndexSetIterator elements(liveout);
401 uint lidx;
402 uint cnt = 0;
403 while ((lidx = elements.next()) != 0) {
404 if( lrgs(lidx).mask().is_UP() &&
405 lrgs(lidx).mask_size() &&
406 !lrgs(lidx)._is_float &&
407 lrgs(lidx).mask().overlap(*Matcher::idealreg2regmask[Op_RegI]) )
408 cnt += lrgs(lidx).reg_pressure();
409 }
410 return cnt;
411 }
412
413 //------------------------------count_float_pressure---------------------------
414 uint PhaseChaitin::count_float_pressure( IndexSet *liveout ) {
415 IndexSetIterator elements(liveout);
416 uint lidx;
417 uint cnt = 0;
418 while ((lidx = elements.next()) != 0) {
419 if( lrgs(lidx).mask().is_UP() &&
420 lrgs(lidx).mask_size() &&
421 lrgs(lidx)._is_float )
422 cnt += lrgs(lidx).reg_pressure();
423 }
424 return cnt;
425 }
426
427 //------------------------------lower_pressure---------------------------------
428 // Adjust register pressure down by 1. Capture last hi-to-low transition,
429 static void lower_pressure( LRG *lrg, uint where, Block *b, uint *pressure, uint *hrp_index ) {
430 if( lrg->mask().is_UP() && lrg->mask_size() ) {
431 if( lrg->_is_float ) {
432 pressure[1] -= lrg->reg_pressure();
433 if( pressure[1] == (uint)FLOATPRESSURE ) {
434 hrp_index[1] = where;
435 #ifdef EXACT_PRESSURE
436 if( pressure[1] > b->_freg_pressure )
437 b->_freg_pressure = pressure[1]+1;
438 #else
439 b->_freg_pressure = (uint)FLOATPRESSURE+1;
440 #endif
441 }
442 } else if( lrg->mask().overlap(*Matcher::idealreg2regmask[Op_RegI]) ) {
443 pressure[0] -= lrg->reg_pressure();
444 if( pressure[0] == (uint)INTPRESSURE ) {
445 hrp_index[0] = where;
446 #ifdef EXACT_PRESSURE
447 if( pressure[0] > b->_reg_pressure )
448 b->_reg_pressure = pressure[0]+1;
449 #else
450 b->_reg_pressure = (uint)INTPRESSURE+1;
451 #endif
452 }
453 }
454 }
455 }
456
457 //------------------------------build_ifg_physical-----------------------------
458 // Build the interference graph using physical registers when available.
459 // That is, if 2 live ranges are simultaneously alive but in their acceptable
460 // register sets do not overlap, then they do not interfere.
461 uint PhaseChaitin::build_ifg_physical( ResourceArea *a ) {
462 NOT_PRODUCT( Compile::TracePhase t3("buildIFG", &_t_buildIFGphysical, TimeCompiler); )
463
464 uint spill_reg = LRG::SPILL_REG;
465 uint must_spill = 0;
466
467 // For all blocks (in any order) do...
468 for( uint i = 0; i < _cfg._num_blocks; i++ ) {
469 Block *b = _cfg._blocks[i];
470 // Clone (rather than smash in place) the liveout info, so it is alive
471 // for the "collect_gc_info" phase later.
472 IndexSet liveout(_live->live(b));
473 uint last_inst = b->end_idx();
474 // Compute last phi index
475 uint last_phi;
476 for( last_phi = 1; last_phi < last_inst; last_phi++ )
477 if( !b->_nodes[last_phi]->is_Phi() )
478 break;
479
480 // Reset block's register pressure values for each ifg construction
481 uint pressure[2], hrp_index[2];
482 pressure[0] = pressure[1] = 0;
483 hrp_index[0] = hrp_index[1] = last_inst+1;
484 b->_reg_pressure = b->_freg_pressure = 0;
485 // Liveout things are presumed live for the whole block. We accumulate
486 // 'area' accordingly. If they get killed in the block, we'll subtract
487 // the unused part of the block from the area.
488 int inst_count = last_inst - last_phi;
489 double cost = (inst_count <= 0) ? 0.0 : b->_freq * double(inst_count);
490 assert(cost >= 0.0, "negative spill cost" );
491 IndexSetIterator elements(&liveout);
492 uint lidx;
493 while ((lidx = elements.next()) != 0) {
494 LRG &lrg = lrgs(lidx);
495 lrg._area += cost;
496 // Compute initial register pressure
497 if( lrg.mask().is_UP() && lrg.mask_size() ) {
498 if( lrg._is_float ) { // Count float pressure
499 pressure[1] += lrg.reg_pressure();
500 #ifdef EXACT_PRESSURE
501 if( pressure[1] > b->_freg_pressure )
502 b->_freg_pressure = pressure[1];
503 #endif
504 // Count int pressure, but do not count the SP, flags
505 } else if( lrgs(lidx).mask().overlap(*Matcher::idealreg2regmask[Op_RegI]) ) {
506 pressure[0] += lrg.reg_pressure();
507 #ifdef EXACT_PRESSURE
508 if( pressure[0] > b->_reg_pressure )
509 b->_reg_pressure = pressure[0];
510 #endif
511 }
512 }
513 }
514 assert( pressure[0] == count_int_pressure (&liveout), "" );
515 assert( pressure[1] == count_float_pressure(&liveout), "" );
516
517 // The IFG is built by a single reverse pass over each basic block.
518 // Starting with the known live-out set, we remove things that get
519 // defined and add things that become live (essentially executing one
520 // pass of a standard LIVE analysis). Just before a Node defines a value
521 // (and removes it from the live-ness set) that value is certainly live.
522 // The defined value interferes with everything currently live. The
523 // value is then removed from the live-ness set and it's inputs are added
524 // to the live-ness set.
525 uint j;
526 for( j = last_inst + 1; j > 1; j-- ) {
527 Node *n = b->_nodes[j - 1];
528
529 // Get value being defined
530 uint r = n2lidx(n);
531
532 // Some special values do not allocate
533 if( r ) {
534 // A DEF normally costs block frequency; rematerialized values are
535 // removed from the DEF sight, so LOWER costs here.
536 lrgs(r)._cost += n->rematerialize() ? 0 : b->_freq;
537
538 // If it is not live, then this instruction is dead. Probably caused
539 // by spilling and rematerialization. Who cares why, yank this baby.
540 if( !liveout.member(r) && n->Opcode() != Op_SafePoint ) {
541 Node *def = n->in(0);
542 if( !n->is_Proj() ||
543 // Could also be a flags-projection of a dead ADD or such.
544 (n2lidx(def) && !liveout.member(n2lidx(def)) ) ) {
545 b->_nodes.remove(j - 1);
546 if( lrgs(r)._def == n ) lrgs(r)._def = 0;
547 n->disconnect_inputs(NULL);
548 _cfg._bbs.map(n->_idx,NULL);
549 n->replace_by(C->top());
550 // Since yanking a Node from block, high pressure moves up one
551 hrp_index[0]--;
552 hrp_index[1]--;
553 continue;
554 }
555
556 // Fat-projections kill many registers which cannot be used to
557 // hold live ranges.
558 if( lrgs(r)._fat_proj ) {
559 // Count the int-only registers
560 RegMask itmp = lrgs(r).mask();
561 itmp.AND(*Matcher::idealreg2regmask[Op_RegI]);
562 int iregs = itmp.Size();
563 #ifdef EXACT_PRESSURE
564 if( pressure[0]+iregs > b->_reg_pressure )
565 b->_reg_pressure = pressure[0]+iregs;
566 #endif
567 if( pressure[0] <= (uint)INTPRESSURE &&
568 pressure[0]+iregs > (uint)INTPRESSURE ) {
569 #ifndef EXACT_PRESSURE
570 b->_reg_pressure = (uint)INTPRESSURE+1;
571 #endif
572 hrp_index[0] = j-1;
573 }
574 // Count the float-only registers
575 RegMask ftmp = lrgs(r).mask();
576 ftmp.AND(*Matcher::idealreg2regmask[Op_RegD]);
577 int fregs = ftmp.Size();
578 #ifdef EXACT_PRESSURE
579 if( pressure[1]+fregs > b->_freg_pressure )
580 b->_freg_pressure = pressure[1]+fregs;
581 #endif
582 if( pressure[1] <= (uint)FLOATPRESSURE &&
583 pressure[1]+fregs > (uint)FLOATPRESSURE ) {
584 #ifndef EXACT_PRESSURE
585 b->_freg_pressure = (uint)FLOATPRESSURE+1;
586 #endif
587 hrp_index[1] = j-1;
588 }
589 }
590
591 } else { // Else it is live
592 // A DEF also ends 'area' partway through the block.
593 lrgs(r)._area -= cost;
594 assert(!(lrgs(r)._area < 0.0), "negative spill area" );
595
596 // Insure high score for immediate-use spill copies so they get a color
597 if( n->is_SpillCopy()
598 && lrgs(r).is_singledef() // MultiDef live range can still split
599 && n->outcnt() == 1 // and use must be in this block
600 && _cfg._bbs[n->unique_out()->_idx] == b ) {
601 // All single-use MachSpillCopy(s) that immediately precede their
602 // use must color early. If a longer live range steals their
603 // color, the spill copy will split and may push another spill copy
604 // further away resulting in an infinite spill-split-retry cycle.
605 // Assigning a zero area results in a high score() and a good
606 // location in the simplify list.
607 //
608
609 Node *single_use = n->unique_out();
610 assert( b->find_node(single_use) >= j, "Use must be later in block");
611 // Use can be earlier in block if it is a Phi, but then I should be a MultiDef
612
613 // Find first non SpillCopy 'm' that follows the current instruction
614 // (j - 1) is index for current instruction 'n'
615 Node *m = n;
616 for( uint i = j; i <= last_inst && m->is_SpillCopy(); ++i ) { m = b->_nodes[i]; }
617 if( m == single_use ) {
618 lrgs(r)._area = 0.0;
619 }
620 }
621
622 // Remove from live-out set
623 if( liveout.remove(r) ) {
624 // Adjust register pressure.
625 // Capture last hi-to-lo pressure transition
626 lower_pressure( &lrgs(r), j-1, b, pressure, hrp_index );
627 assert( pressure[0] == count_int_pressure (&liveout), "" );
628 assert( pressure[1] == count_float_pressure(&liveout), "" );
629 }
630
631 // Copies do not define a new value and so do not interfere.
632 // Remove the copies source from the liveout set before interfering.
633 uint idx = n->is_Copy();
634 if( idx ) {
635 uint x = n2lidx(n->in(idx));
636 if( liveout.remove( x ) ) {
637 lrgs(x)._area -= cost;
638 // Adjust register pressure.
639 lower_pressure( &lrgs(x), j-1, b, pressure, hrp_index );
640 assert( pressure[0] == count_int_pressure (&liveout), "" );
641 assert( pressure[1] == count_float_pressure(&liveout), "" );
642 }
643 }
644 } // End of if live or not
645
646 // Interfere with everything live. If the defined value must
647 // go in a particular register, just remove that register from
648 // all conflicting parties and avoid the interference.
649
650 // Make exclusions for rematerializable defs. Since rematerializable
651 // DEFs are not bound but the live range is, some uses must be bound.
652 // If we spill live range 'r', it can rematerialize at each use site
653 // according to its bindings.
654 const RegMask &rmask = lrgs(r).mask();
655 if( lrgs(r).is_bound() && !(n->rematerialize()) && rmask.is_NotEmpty() ) {
656 // Smear odd bits; leave only aligned pairs of bits.
657 RegMask r2mask = rmask;
658 r2mask.SmearToPairs();
659 // Check for common case
660 int r_size = lrgs(r).num_regs();
661 OptoReg::Name r_reg = (r_size == 1) ? rmask.find_first_elem() : OptoReg::Physical;
662
663 IndexSetIterator elements(&liveout);
664 uint l;
665 while ((l = elements.next()) != 0) {
666 LRG &lrg = lrgs(l);
667 // If 'l' must spill already, do not further hack his bits.
668 // He'll get some interferences and be forced to spill later.
669 if( lrg._must_spill ) continue;
670 // Remove bound register(s) from 'l's choices
671 RegMask old = lrg.mask();
672 uint old_size = lrg.mask_size();
673 // Remove the bits from LRG 'r' from LRG 'l' so 'l' no
674 // longer interferes with 'r'. If 'l' requires aligned
675 // adjacent pairs, subtract out bit pairs.
676 if( lrg.num_regs() == 2 && !lrg._fat_proj ) {
677 lrg.SUBTRACT( r2mask );
678 lrg.compute_set_mask_size();
679 } else if( r_size != 1 ) {
680 lrg.SUBTRACT( rmask );
681 lrg.compute_set_mask_size();
682 } else { // Common case: size 1 bound removal
683 if( lrg.mask().Member(r_reg) ) {
684 lrg.Remove(r_reg);
685 lrg.set_mask_size(lrg.mask().is_AllStack() ? 65535:old_size-1);
686 }
687 }
688 // If 'l' goes completely dry, it must spill.
689 if( lrg.not_free() ) {
690 // Give 'l' some kind of reasonable mask, so he picks up
691 // interferences (and will spill later).
692 lrg.set_mask( old );
693 lrg.set_mask_size(old_size);
694 must_spill++;
695 lrg._must_spill = 1;
696 lrg.set_reg(OptoReg::Name(LRG::SPILL_REG));
697 }
698 }
699 } // End of if bound
700
701 // Now interference with everything that is live and has
702 // compatible register sets.
703 interfere_with_live(r,&liveout);
704
705 } // End of if normal register-allocated value
706
707 // Area remaining in the block
708 inst_count--;
709 cost = (inst_count <= 0) ? 0.0 : b->_freq * double(inst_count);
710
711 // Make all inputs live
712 if( !n->is_Phi() ) { // Phi function uses come from prior block
713 JVMState* jvms = n->jvms();
714 uint debug_start = jvms ? jvms->debug_start() : 999999;
715 // Start loop at 1 (skip control edge) for most Nodes.
716 // SCMemProj's might be the sole use of a StoreLConditional.
717 // While StoreLConditionals set memory (the SCMemProj use)
718 // they also def flags; if that flag def is unused the
719 // allocator sees a flag-setting instruction with no use of
720 // the flags and assumes it's dead. This keeps the (useless)
721 // flag-setting behavior alive while also keeping the (useful)
722 // memory update effect.
723 for( uint k = ((n->Opcode() == Op_SCMemProj) ? 0:1); k < n->req(); k++ ) {
724 Node *def = n->in(k);
725 uint x = n2lidx(def);
726 if( !x ) continue;
727 LRG &lrg = lrgs(x);
728 // No use-side cost for spilling debug info
729 if( k < debug_start )
730 // A USE costs twice block frequency (once for the Load, once
731 // for a Load-delay). Rematerialized uses only cost once.
732 lrg._cost += (def->rematerialize() ? b->_freq : (b->_freq + b->_freq));
733 // It is live now
734 if( liveout.insert( x ) ) {
735 // Newly live things assumed live from here to top of block
736 lrg._area += cost;
737 // Adjust register pressure
738 if( lrg.mask().is_UP() && lrg.mask_size() ) {
739 if( lrg._is_float ) {
740 pressure[1] += lrg.reg_pressure();
741 #ifdef EXACT_PRESSURE
742 if( pressure[1] > b->_freg_pressure )
743 b->_freg_pressure = pressure[1];
744 #endif
745 } else if( lrg.mask().overlap(*Matcher::idealreg2regmask[Op_RegI]) ) {
746 pressure[0] += lrg.reg_pressure();
747 #ifdef EXACT_PRESSURE
748 if( pressure[0] > b->_reg_pressure )
749 b->_reg_pressure = pressure[0];
750 #endif
751 }
752 }
753 assert( pressure[0] == count_int_pressure (&liveout), "" );
754 assert( pressure[1] == count_float_pressure(&liveout), "" );
755 }
756 assert(!(lrg._area < 0.0), "negative spill area" );
757 }
758 }
759 } // End of reverse pass over all instructions in block
760
761 // If we run off the top of the block with high pressure and
762 // never see a hi-to-low pressure transition, just record that
763 // the whole block is high pressure.
764 if( pressure[0] > (uint)INTPRESSURE ) {
765 hrp_index[0] = 0;
766 #ifdef EXACT_PRESSURE
767 if( pressure[0] > b->_reg_pressure )
768 b->_reg_pressure = pressure[0];
769 #else
770 b->_reg_pressure = (uint)INTPRESSURE+1;
771 #endif
772 }
773 if( pressure[1] > (uint)FLOATPRESSURE ) {
774 hrp_index[1] = 0;
775 #ifdef EXACT_PRESSURE
776 if( pressure[1] > b->_freg_pressure )
777 b->_freg_pressure = pressure[1];
778 #else
779 b->_freg_pressure = (uint)FLOATPRESSURE+1;
780 #endif
781 }
782
783 // Compute high pressure indice; avoid landing in the middle of projnodes
784 j = hrp_index[0];
785 if( j < b->_nodes.size() && j < b->end_idx()+1 ) {
786 Node *cur = b->_nodes[j];
787 while( cur->is_Proj() || (cur->is_MachNullCheck()) || cur->is_Catch() ) {
788 j--;
789 cur = b->_nodes[j];
790 }
791 }
792 b->_ihrp_index = j;
793 j = hrp_index[1];
794 if( j < b->_nodes.size() && j < b->end_idx()+1 ) {
795 Node *cur = b->_nodes[j];
796 while( cur->is_Proj() || (cur->is_MachNullCheck()) || cur->is_Catch() ) {
797 j--;
798 cur = b->_nodes[j];
799 }
800 }
801 b->_fhrp_index = j;
802
803 #ifndef PRODUCT
804 // Gather Register Pressure Statistics
805 if( PrintOptoStatistics ) {
806 if( b->_reg_pressure > (uint)INTPRESSURE || b->_freg_pressure > (uint)FLOATPRESSURE )
807 _high_pressure++;
808 else
809 _low_pressure++;
810 }
811 #endif
812 } // End of for all blocks
813
814 return must_spill;
815 }