1 /* 2 * Copyright (c) 2002, 2011, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "compiler/oopMap.hpp" 27 #include "opto/addnode.hpp" 28 #include "opto/callnode.hpp" 29 #include "opto/compile.hpp" 30 #include "opto/machnode.hpp" 31 #include "opto/matcher.hpp" 32 #include "opto/phase.hpp" 33 #include "opto/regalloc.hpp" 34 #include "opto/rootnode.hpp" 35 #ifdef TARGET_ARCH_x86 36 # include "vmreg_x86.inline.hpp" 37 #endif 38 #ifdef TARGET_ARCH_sparc 39 # include "vmreg_sparc.inline.hpp" 40 #endif 41 #ifdef TARGET_ARCH_zero 42 # include "vmreg_zero.inline.hpp" 43 #endif 44 #ifdef TARGET_ARCH_arm 45 # include "vmreg_arm.inline.hpp" 46 #endif 47 #ifdef TARGET_ARCH_ppc 48 # include "vmreg_ppc.inline.hpp" 49 #endif 50 51 // The functions in this file builds OopMaps after all scheduling is done. 52 // 53 // OopMaps contain a list of all registers and stack-slots containing oops (so 54 // they can be updated by GC). OopMaps also contain a list of derived-pointer 55 // base-pointer pairs. When the base is moved, the derived pointer moves to 56 // follow it. Finally, any registers holding callee-save values are also 57 // recorded. These might contain oops, but only the caller knows. 58 // 59 // BuildOopMaps implements a simple forward reaching-defs solution. At each 60 // GC point we'll have the reaching-def Nodes. If the reaching Nodes are 61 // typed as pointers (no offset), then they are oops. Pointers+offsets are 62 // derived pointers, and bases can be found from them. Finally, we'll also 63 // track reaching callee-save values. Note that a copy of a callee-save value 64 // "kills" it's source, so that only 1 copy of a callee-save value is alive at 65 // a time. 66 // 67 // We run a simple bitvector liveness pass to help trim out dead oops. Due to 68 // irreducible loops, we can have a reaching def of an oop that only reaches 69 // along one path and no way to know if it's valid or not on the other path. 70 // The bitvectors are quite dense and the liveness pass is fast. 71 // 72 // At GC points, we consult this information to build OopMaps. All reaching 73 // defs typed as oops are added to the OopMap. Only 1 instance of a 74 // callee-save register can be recorded. For derived pointers, we'll have to 75 // find and record the register holding the base. 76 // 77 // The reaching def's is a simple 1-pass worklist approach. I tried a clever 78 // breadth-first approach but it was worse (showed O(n^2) in the 79 // pick-next-block code). 80 // 81 // The relevant data is kept in a struct of arrays (it could just as well be 82 // an array of structs, but the struct-of-arrays is generally a little more 83 // efficient). The arrays are indexed by register number (including 84 // stack-slots as registers) and so is bounded by 200 to 300 elements in 85 // practice. One array will map to a reaching def Node (or NULL for 86 // conflict/dead). The other array will map to a callee-saved register or 87 // OptoReg::Bad for not-callee-saved. 88 89 90 //------------------------------OopFlow---------------------------------------- 91 // Structure to pass around 92 struct OopFlow : public ResourceObj { 93 short *_callees; // Array mapping register to callee-saved 94 Node **_defs; // array mapping register to reaching def 95 // or NULL if dead/conflict 96 // OopFlow structs, when not being actively modified, describe the _end_ of 97 // this block. 98 Block *_b; // Block for this struct 99 OopFlow *_next; // Next free OopFlow 100 // or NULL if dead/conflict 101 Compile* C; 102 103 OopFlow( short *callees, Node **defs, Compile* c ) : _callees(callees), _defs(defs), 104 _b(NULL), _next(NULL), C(c) { } 105 106 // Given reaching-defs for this block start, compute it for this block end 107 void compute_reach( PhaseRegAlloc *regalloc, int max_reg, Dict *safehash ); 108 109 // Merge these two OopFlows into the 'this' pointer. 110 void merge( OopFlow *flow, int max_reg ); 111 112 // Copy a 'flow' over an existing flow 113 void clone( OopFlow *flow, int max_size); 114 115 // Make a new OopFlow from scratch 116 static OopFlow *make( Arena *A, int max_size, Compile* C ); 117 118 // Build an oopmap from the current flow info 119 OopMap *build_oop_map( Node *n, int max_reg, PhaseRegAlloc *regalloc, int* live ); 120 }; 121 122 //------------------------------compute_reach---------------------------------- 123 // Given reaching-defs for this block start, compute it for this block end 124 void OopFlow::compute_reach( PhaseRegAlloc *regalloc, int max_reg, Dict *safehash ) { 125 126 for( uint i=0; i<_b->_nodes.size(); i++ ) { 127 Node *n = _b->_nodes[i]; 128 129 if( n->jvms() ) { // Build an OopMap here? 130 JVMState *jvms = n->jvms(); 131 // no map needed for leaf calls 132 if( n->is_MachSafePoint() && !n->is_MachCallLeaf() ) { 133 int *live = (int*) (*safehash)[n]; 134 assert( live, "must find live" ); 135 n->as_MachSafePoint()->set_oop_map( build_oop_map(n,max_reg,regalloc, live) ); 136 } 137 } 138 139 // Assign new reaching def's. 140 // Note that I padded the _defs and _callees arrays so it's legal 141 // to index at _defs[OptoReg::Bad]. 142 OptoReg::Name first = regalloc->get_reg_first(n); 143 OptoReg::Name second = regalloc->get_reg_second(n); 144 _defs[first] = n; 145 _defs[second] = n; 146 147 // Pass callee-save info around copies 148 int idx = n->is_Copy(); 149 if( idx ) { // Copies move callee-save info 150 OptoReg::Name old_first = regalloc->get_reg_first(n->in(idx)); 151 OptoReg::Name old_second = regalloc->get_reg_second(n->in(idx)); 152 int tmp_first = _callees[old_first]; 153 int tmp_second = _callees[old_second]; 154 _callees[old_first] = OptoReg::Bad; // callee-save is moved, dead in old location 155 _callees[old_second] = OptoReg::Bad; 156 _callees[first] = tmp_first; 157 _callees[second] = tmp_second; 158 } else if( n->is_Phi() ) { // Phis do not mod callee-saves 159 assert( _callees[first] == _callees[regalloc->get_reg_first(n->in(1))], "" ); 160 assert( _callees[second] == _callees[regalloc->get_reg_second(n->in(1))], "" ); 161 assert( _callees[first] == _callees[regalloc->get_reg_first(n->in(n->req()-1))], "" ); 162 assert( _callees[second] == _callees[regalloc->get_reg_second(n->in(n->req()-1))], "" ); 163 } else { 164 _callees[first] = OptoReg::Bad; // No longer holding a callee-save value 165 _callees[second] = OptoReg::Bad; 166 167 // Find base case for callee saves 168 if( n->is_Proj() && n->in(0)->is_Start() ) { 169 if( OptoReg::is_reg(first) && 170 regalloc->_matcher.is_save_on_entry(first) ) 171 _callees[first] = first; 172 if( OptoReg::is_reg(second) && 173 regalloc->_matcher.is_save_on_entry(second) ) 174 _callees[second] = second; 175 } 176 } 177 } 178 } 179 180 //------------------------------merge------------------------------------------ 181 // Merge the given flow into the 'this' flow 182 void OopFlow::merge( OopFlow *flow, int max_reg ) { 183 assert( _b == NULL, "merging into a happy flow" ); 184 assert( flow->_b, "this flow is still alive" ); 185 assert( flow != this, "no self flow" ); 186 187 // Do the merge. If there are any differences, drop to 'bottom' which 188 // is OptoReg::Bad or NULL depending. 189 for( int i=0; i<max_reg; i++ ) { 190 // Merge the callee-save's 191 if( _callees[i] != flow->_callees[i] ) 192 _callees[i] = OptoReg::Bad; 193 // Merge the reaching defs 194 if( _defs[i] != flow->_defs[i] ) 195 _defs[i] = NULL; 196 } 197 198 } 199 200 //------------------------------clone------------------------------------------ 201 void OopFlow::clone( OopFlow *flow, int max_size ) { 202 _b = flow->_b; 203 memcpy( _callees, flow->_callees, sizeof(short)*max_size); 204 memcpy( _defs , flow->_defs , sizeof(Node*)*max_size); 205 } 206 207 //------------------------------make------------------------------------------- 208 OopFlow *OopFlow::make( Arena *A, int max_size, Compile* C ) { 209 short *callees = NEW_ARENA_ARRAY(A,short,max_size+1); 210 Node **defs = NEW_ARENA_ARRAY(A,Node*,max_size+1); 211 debug_only( memset(defs,0,(max_size+1)*sizeof(Node*)) ); 212 OopFlow *flow = new (A) OopFlow(callees+1, defs+1, C); 213 assert( &flow->_callees[OptoReg::Bad] == callees, "Ok to index at OptoReg::Bad" ); 214 assert( &flow->_defs [OptoReg::Bad] == defs , "Ok to index at OptoReg::Bad" ); 215 return flow; 216 } 217 218 //------------------------------bit twiddlers---------------------------------- 219 static int get_live_bit( int *live, int reg ) { 220 return live[reg>>LogBitsPerInt] & (1<<(reg&(BitsPerInt-1))); } 221 static void set_live_bit( int *live, int reg ) { 222 live[reg>>LogBitsPerInt] |= (1<<(reg&(BitsPerInt-1))); } 223 static void clr_live_bit( int *live, int reg ) { 224 live[reg>>LogBitsPerInt] &= ~(1<<(reg&(BitsPerInt-1))); } 225 226 //------------------------------build_oop_map---------------------------------- 227 // Build an oopmap from the current flow info 228 OopMap *OopFlow::build_oop_map( Node *n, int max_reg, PhaseRegAlloc *regalloc, int* live ) { 229 int framesize = regalloc->_framesize; 230 int max_inarg_slot = OptoReg::reg2stack(regalloc->_matcher._new_SP); 231 debug_only( char *dup_check = NEW_RESOURCE_ARRAY(char,OptoReg::stack0()); 232 memset(dup_check,0,OptoReg::stack0()) ); 233 234 OopMap *omap = new OopMap( framesize, max_inarg_slot ); 235 MachCallNode *mcall = n->is_MachCall() ? n->as_MachCall() : NULL; 236 JVMState* jvms = n->jvms(); 237 238 // For all registers do... 239 for( int reg=0; reg<max_reg; reg++ ) { 240 if( get_live_bit(live,reg) == 0 ) 241 continue; // Ignore if not live 242 243 // %%% C2 can use 2 OptoRegs when the physical register is only one 64bit 244 // register in that case we'll get an non-concrete register for the second 245 // half. We only need to tell the map the register once! 246 // 247 // However for the moment we disable this change and leave things as they 248 // were. 249 250 VMReg r = OptoReg::as_VMReg(OptoReg::Name(reg), framesize, max_inarg_slot); 251 252 if (false && r->is_reg() && !r->is_concrete()) { 253 continue; 254 } 255 256 // See if dead (no reaching def). 257 Node *def = _defs[reg]; // Get reaching def 258 assert( def, "since live better have reaching def" ); 259 260 // Classify the reaching def as oop, derived, callee-save, dead, or other 261 const Type *t = def->bottom_type(); 262 if( t->isa_oop_ptr() ) { // Oop or derived? 263 assert( !OptoReg::is_valid(_callees[reg]), "oop can't be callee save" ); 264 #ifdef _LP64 265 // 64-bit pointers record oop-ishness on 2 aligned adjacent registers. 266 // Make sure both are record from the same reaching def, but do not 267 // put both into the oopmap. 268 if( (reg&1) == 1 ) { // High half of oop-pair? 269 assert( _defs[reg-1] == _defs[reg], "both halves from same reaching def" ); 270 continue; // Do not record high parts in oopmap 271 } 272 #endif 273 274 // Check for a legal reg name in the oopMap and bailout if it is not. 275 if (!omap->legal_vm_reg_name(r)) { 276 regalloc->C->record_method_not_compilable("illegal oopMap register name"); 277 continue; 278 } 279 if( t->is_ptr()->_offset == 0 ) { // Not derived? 280 if( mcall ) { 281 // Outgoing argument GC mask responsibility belongs to the callee, 282 // not the caller. Inspect the inputs to the call, to see if 283 // this live-range is one of them. 284 uint cnt = mcall->tf()->domain()->cnt(); 285 uint j; 286 for( j = TypeFunc::Parms; j < cnt; j++) 287 if( mcall->in(j) == def ) 288 break; // reaching def is an argument oop 289 if( j < cnt ) // arg oops dont go in GC map 290 continue; // Continue on to the next register 291 } 292 omap->set_oop(r); 293 } else { // Else it's derived. 294 // Find the base of the derived value. 295 uint i; 296 // Fast, common case, scan 297 for( i = jvms->oopoff(); i < n->req(); i+=2 ) 298 if( n->in(i) == def ) break; // Common case 299 if( i == n->req() ) { // Missed, try a more generous scan 300 // Scan again, but this time peek through copies 301 for( i = jvms->oopoff(); i < n->req(); i+=2 ) { 302 Node *m = n->in(i); // Get initial derived value 303 while( 1 ) { 304 Node *d = def; // Get initial reaching def 305 while( 1 ) { // Follow copies of reaching def to end 306 if( m == d ) goto found; // breaks 3 loops 307 int idx = d->is_Copy(); 308 if( !idx ) break; 309 d = d->in(idx); // Link through copy 310 } 311 int idx = m->is_Copy(); 312 if( !idx ) break; 313 m = m->in(idx); 314 } 315 } 316 guarantee( 0, "must find derived/base pair" ); 317 } 318 found: ; 319 Node *base = n->in(i+1); // Base is other half of pair 320 int breg = regalloc->get_reg_first(base); 321 VMReg b = OptoReg::as_VMReg(OptoReg::Name(breg), framesize, max_inarg_slot); 322 323 // I record liveness at safepoints BEFORE I make the inputs 324 // live. This is because argument oops are NOT live at a 325 // safepoint (or at least they cannot appear in the oopmap). 326 // Thus bases of base/derived pairs might not be in the 327 // liveness data but they need to appear in the oopmap. 328 if( get_live_bit(live,breg) == 0 ) {// Not live? 329 // Flag it, so next derived pointer won't re-insert into oopmap 330 set_live_bit(live,breg); 331 // Already missed our turn? 332 if( breg < reg ) { 333 if (b->is_stack() || b->is_concrete() || true ) { 334 omap->set_oop( b); 335 } 336 } 337 } 338 if (b->is_stack() || b->is_concrete() || true ) { 339 omap->set_derived_oop( r, b); 340 } 341 } 342 343 } else if( t->isa_narrowoop() ) { 344 assert( !OptoReg::is_valid(_callees[reg]), "oop can't be callee save" ); 345 // Check for a legal reg name in the oopMap and bailout if it is not. 346 if (!omap->legal_vm_reg_name(r)) { 347 regalloc->C->record_method_not_compilable("illegal oopMap register name"); 348 continue; 349 } 350 if( mcall ) { 351 // Outgoing argument GC mask responsibility belongs to the callee, 352 // not the caller. Inspect the inputs to the call, to see if 353 // this live-range is one of them. 354 uint cnt = mcall->tf()->domain()->cnt(); 355 uint j; 356 for( j = TypeFunc::Parms; j < cnt; j++) 357 if( mcall->in(j) == def ) 358 break; // reaching def is an argument oop 359 if( j < cnt ) // arg oops dont go in GC map 360 continue; // Continue on to the next register 361 } 362 omap->set_narrowoop(r); 363 } else if( OptoReg::is_valid(_callees[reg])) { // callee-save? 364 // It's a callee-save value 365 assert( dup_check[_callees[reg]]==0, "trying to callee save same reg twice" ); 366 debug_only( dup_check[_callees[reg]]=1; ) 367 VMReg callee = OptoReg::as_VMReg(OptoReg::Name(_callees[reg])); 368 if ( callee->is_concrete() || true ) { 369 omap->set_callee_saved( r, callee); 370 } 371 372 } else { 373 // Other - some reaching non-oop value 374 omap->set_value( r); 375 #ifdef ASSERT 376 if( t->isa_rawptr() && C->cfg()->_raw_oops.member(def) ) { 377 def->dump(); 378 n->dump(); 379 assert(false, "there should be a oop in OopMap instead of a live raw oop at safepoint"); 380 } 381 #endif 382 } 383 384 } 385 386 #ifdef ASSERT 387 /* Nice, Intel-only assert 388 int cnt_callee_saves=0; 389 int reg2 = 0; 390 while (OptoReg::is_reg(reg2)) { 391 if( dup_check[reg2] != 0) cnt_callee_saves++; 392 assert( cnt_callee_saves==3 || cnt_callee_saves==5, "missed some callee-save" ); 393 reg2++; 394 } 395 */ 396 #endif 397 398 #ifdef ASSERT 399 for( OopMapStream oms1(omap, OopMapValue::derived_oop_value); !oms1.is_done(); oms1.next()) { 400 OopMapValue omv1 = oms1.current(); 401 bool found = false; 402 for( OopMapStream oms2(omap,OopMapValue::oop_value); !oms2.is_done(); oms2.next()) { 403 if( omv1.content_reg() == oms2.current().reg() ) { 404 found = true; 405 break; 406 } 407 } 408 assert( found, "derived with no base in oopmap" ); 409 } 410 #endif 411 412 return omap; 413 } 414 415 //------------------------------do_liveness------------------------------------ 416 // Compute backwards liveness on registers 417 static void do_liveness( PhaseRegAlloc *regalloc, PhaseCFG *cfg, Block_List *worklist, int max_reg_ints, Arena *A, Dict *safehash ) { 418 int *live = NEW_ARENA_ARRAY(A, int, (cfg->_num_blocks+1) * max_reg_ints); 419 int *tmp_live = &live[cfg->_num_blocks * max_reg_ints]; 420 Node *root = cfg->C->root(); 421 // On CISC platforms, get the node representing the stack pointer that regalloc 422 // used for spills 423 Node *fp = NodeSentinel; 424 if (UseCISCSpill && root->req() > 1) { 425 fp = root->in(1)->in(TypeFunc::FramePtr); 426 } 427 memset( live, 0, cfg->_num_blocks * (max_reg_ints<<LogBytesPerInt) ); 428 // Push preds onto worklist 429 for( uint i=1; i<root->req(); i++ ) 430 worklist->push(cfg->_bbs[root->in(i)->_idx]); 431 432 // ZKM.jar includes tiny infinite loops which are unreached from below. 433 // If we missed any blocks, we'll retry here after pushing all missed 434 // blocks on the worklist. Normally this outer loop never trips more 435 // than once. 436 while( 1 ) { 437 438 while( worklist->size() ) { // Standard worklist algorithm 439 Block *b = worklist->rpop(); 440 441 // Copy first successor into my tmp_live space 442 int s0num = b->_succs[0]->_pre_order; 443 int *t = &live[s0num*max_reg_ints]; 444 for( int i=0; i<max_reg_ints; i++ ) 445 tmp_live[i] = t[i]; 446 447 // OR in the remaining live registers 448 for( uint j=1; j<b->_num_succs; j++ ) { 449 uint sjnum = b->_succs[j]->_pre_order; 450 int *t = &live[sjnum*max_reg_ints]; 451 for( int i=0; i<max_reg_ints; i++ ) 452 tmp_live[i] |= t[i]; 453 } 454 455 // Now walk tmp_live up the block backwards, computing live 456 for( int k=b->_nodes.size()-1; k>=0; k-- ) { 457 Node *n = b->_nodes[k]; 458 // KILL def'd bits 459 int first = regalloc->get_reg_first(n); 460 int second = regalloc->get_reg_second(n); 461 if( OptoReg::is_valid(first) ) clr_live_bit(tmp_live,first); 462 if( OptoReg::is_valid(second) ) clr_live_bit(tmp_live,second); 463 464 MachNode *m = n->is_Mach() ? n->as_Mach() : NULL; 465 466 // Check if m is potentially a CISC alternate instruction (i.e, possibly 467 // synthesized by RegAlloc from a conventional instruction and a 468 // spilled input) 469 bool is_cisc_alternate = false; 470 if (UseCISCSpill && m) { 471 is_cisc_alternate = m->is_cisc_alternate(); 472 } 473 474 // GEN use'd bits 475 for( uint l=1; l<n->req(); l++ ) { 476 Node *def = n->in(l); 477 assert(def != 0, "input edge required"); 478 int first = regalloc->get_reg_first(def); 479 int second = regalloc->get_reg_second(def); 480 if( OptoReg::is_valid(first) ) set_live_bit(tmp_live,first); 481 if( OptoReg::is_valid(second) ) set_live_bit(tmp_live,second); 482 // If we use the stack pointer in a cisc-alternative instruction, 483 // check for use as a memory operand. Then reconstruct the RegName 484 // for this stack location, and set the appropriate bit in the 485 // live vector 4987749. 486 if (is_cisc_alternate && def == fp) { 487 const TypePtr *adr_type = NULL; 488 intptr_t offset; 489 const Node* base = m->get_base_and_disp(offset, adr_type); 490 if (base == NodeSentinel) { 491 // Machnode has multiple memory inputs. We are unable to reason 492 // with these, but are presuming (with trepidation) that not any of 493 // them are oops. This can be fixed by making get_base_and_disp() 494 // look at a specific input instead of all inputs. 495 assert(!def->bottom_type()->isa_oop_ptr(), "expecting non-oop mem input"); 496 } else if (base != fp || offset == Type::OffsetBot) { 497 // Do nothing: the fp operand is either not from a memory use 498 // (base == NULL) OR the fp is used in a non-memory context 499 // (base is some other register) OR the offset is not constant, 500 // so it is not a stack slot. 501 } else { 502 assert(offset >= 0, "unexpected negative offset"); 503 offset -= (offset % jintSize); // count the whole word 504 int stack_reg = regalloc->offset2reg(offset); 505 if (OptoReg::is_stack(stack_reg)) { 506 set_live_bit(tmp_live, stack_reg); 507 } else { 508 assert(false, "stack_reg not on stack?"); 509 } 510 } 511 } 512 } 513 514 if( n->jvms() ) { // Record liveness at safepoint 515 516 // This placement of this stanza means inputs to calls are 517 // considered live at the callsite's OopMap. Argument oops are 518 // hence live, but NOT included in the oopmap. See cutout in 519 // build_oop_map. Debug oops are live (and in OopMap). 520 int *n_live = NEW_ARENA_ARRAY(A, int, max_reg_ints); 521 for( int l=0; l<max_reg_ints; l++ ) 522 n_live[l] = tmp_live[l]; 523 safehash->Insert(n,n_live); 524 } 525 526 } 527 528 // Now at block top, see if we have any changes. If so, propagate 529 // to prior blocks. 530 int *old_live = &live[b->_pre_order*max_reg_ints]; 531 int l; 532 for( l=0; l<max_reg_ints; l++ ) 533 if( tmp_live[l] != old_live[l] ) 534 break; 535 if( l<max_reg_ints ) { // Change! 536 // Copy in new value 537 for( l=0; l<max_reg_ints; l++ ) 538 old_live[l] = tmp_live[l]; 539 // Push preds onto worklist 540 for( l=1; l<(int)b->num_preds(); l++ ) 541 worklist->push(cfg->_bbs[b->pred(l)->_idx]); 542 } 543 } 544 545 // Scan for any missing safepoints. Happens to infinite loops 546 // ala ZKM.jar 547 uint i; 548 for( i=1; i<cfg->_num_blocks; i++ ) { 549 Block *b = cfg->_blocks[i]; 550 uint j; 551 for( j=1; j<b->_nodes.size(); j++ ) 552 if( b->_nodes[j]->jvms() && 553 (*safehash)[b->_nodes[j]] == NULL ) 554 break; 555 if( j<b->_nodes.size() ) break; 556 } 557 if( i == cfg->_num_blocks ) 558 break; // Got 'em all 559 #ifndef PRODUCT 560 if( PrintOpto && Verbose ) 561 tty->print_cr("retripping live calc"); 562 #endif 563 // Force the issue (expensively): recheck everybody 564 for( i=1; i<cfg->_num_blocks; i++ ) 565 worklist->push(cfg->_blocks[i]); 566 } 567 568 } 569 570 //------------------------------BuildOopMaps----------------------------------- 571 // Collect GC mask info - where are all the OOPs? 572 void Compile::BuildOopMaps() { 573 NOT_PRODUCT( TracePhase t3("bldOopMaps", &_t_buildOopMaps, TimeCompiler); ) 574 // Can't resource-mark because I need to leave all those OopMaps around, 575 // or else I need to resource-mark some arena other than the default. 576 // ResourceMark rm; // Reclaim all OopFlows when done 577 int max_reg = _regalloc->_max_reg; // Current array extent 578 579 Arena *A = Thread::current()->resource_area(); 580 Block_List worklist; // Worklist of pending blocks 581 582 int max_reg_ints = round_to(max_reg, BitsPerInt)>>LogBitsPerInt; 583 Dict *safehash = NULL; // Used for assert only 584 // Compute a backwards liveness per register. Needs a bitarray of 585 // #blocks x (#registers, rounded up to ints) 586 safehash = new Dict(cmpkey,hashkey,A); 587 do_liveness( _regalloc, _cfg, &worklist, max_reg_ints, A, safehash ); 588 OopFlow *free_list = NULL; // Free, unused 589 590 // Array mapping blocks to completed oopflows 591 OopFlow **flows = NEW_ARENA_ARRAY(A, OopFlow*, _cfg->_num_blocks); 592 memset( flows, 0, _cfg->_num_blocks*sizeof(OopFlow*) ); 593 594 595 // Do the first block 'by hand' to prime the worklist 596 Block *entry = _cfg->_blocks[1]; 597 OopFlow *rootflow = OopFlow::make(A,max_reg,this); 598 // Initialize to 'bottom' (not 'top') 599 memset( rootflow->_callees, OptoReg::Bad, max_reg*sizeof(short) ); 600 memset( rootflow->_defs , 0, max_reg*sizeof(Node*) ); 601 flows[entry->_pre_order] = rootflow; 602 603 // Do the first block 'by hand' to prime the worklist 604 rootflow->_b = entry; 605 rootflow->compute_reach( _regalloc, max_reg, safehash ); 606 for( uint i=0; i<entry->_num_succs; i++ ) 607 worklist.push(entry->_succs[i]); 608 609 // Now worklist contains blocks which have some, but perhaps not all, 610 // predecessors visited. 611 while( worklist.size() ) { 612 // Scan for a block with all predecessors visited, or any randoms slob 613 // otherwise. All-preds-visited order allows me to recycle OopFlow 614 // structures rapidly and cut down on the memory footprint. 615 // Note: not all predecessors might be visited yet (must happen for 616 // irreducible loops). This is OK, since every live value must have the 617 // SAME reaching def for the block, so any reaching def is OK. 618 uint i; 619 620 Block *b = worklist.pop(); 621 // Ignore root block 622 if( b == _cfg->_broot ) continue; 623 // Block is already done? Happens if block has several predecessors, 624 // he can get on the worklist more than once. 625 if( flows[b->_pre_order] ) continue; 626 627 // If this block has a visited predecessor AND that predecessor has this 628 // last block as his only undone child, we can move the OopFlow from the 629 // pred to this block. Otherwise we have to grab a new OopFlow. 630 OopFlow *flow = NULL; // Flag for finding optimized flow 631 Block *pred = (Block*)0xdeadbeef; 632 uint j; 633 // Scan this block's preds to find a done predecessor 634 for( j=1; j<b->num_preds(); j++ ) { 635 Block *p = _cfg->_bbs[b->pred(j)->_idx]; 636 OopFlow *p_flow = flows[p->_pre_order]; 637 if( p_flow ) { // Predecessor is done 638 assert( p_flow->_b == p, "cross check" ); 639 pred = p; // Record some predecessor 640 // If all successors of p are done except for 'b', then we can carry 641 // p_flow forward to 'b' without copying, otherwise we have to draw 642 // from the free_list and clone data. 643 uint k; 644 for( k=0; k<p->_num_succs; k++ ) 645 if( !flows[p->_succs[k]->_pre_order] && 646 p->_succs[k] != b ) 647 break; 648 649 // Either carry-forward the now-unused OopFlow for b's use 650 // or draw a new one from the free list 651 if( k==p->_num_succs ) { 652 flow = p_flow; 653 break; // Found an ideal pred, use him 654 } 655 } 656 } 657 658 if( flow ) { 659 // We have an OopFlow that's the last-use of a predecessor. 660 // Carry it forward. 661 } else { // Draw a new OopFlow from the freelist 662 if( !free_list ) 663 free_list = OopFlow::make(A,max_reg,C); 664 flow = free_list; 665 assert( flow->_b == NULL, "oopFlow is not free" ); 666 free_list = flow->_next; 667 flow->_next = NULL; 668 669 // Copy/clone over the data 670 flow->clone(flows[pred->_pre_order], max_reg); 671 } 672 673 // Mark flow for block. Blocks can only be flowed over once, 674 // because after the first time they are guarded from entering 675 // this code again. 676 assert( flow->_b == pred, "have some prior flow" ); 677 flow->_b = NULL; 678 679 // Now push flow forward 680 flows[b->_pre_order] = flow;// Mark flow for this block 681 flow->_b = b; 682 flow->compute_reach( _regalloc, max_reg, safehash ); 683 684 // Now push children onto worklist 685 for( i=0; i<b->_num_succs; i++ ) 686 worklist.push(b->_succs[i]); 687 688 } 689 }