1 /* 2 * Copyright (c) 2002, 2010, 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 45 // The functions in this file builds OopMaps after all scheduling is done. 46 // 47 // OopMaps contain a list of all registers and stack-slots containing oops (so 48 // they can be updated by GC). OopMaps also contain a list of derived-pointer 49 // base-pointer pairs. When the base is moved, the derived pointer moves to 50 // follow it. Finally, any registers holding callee-save values are also 51 // recorded. These might contain oops, but only the caller knows. 52 // 53 // BuildOopMaps implements a simple forward reaching-defs solution. At each 54 // GC point we'll have the reaching-def Nodes. If the reaching Nodes are 55 // typed as pointers (no offset), then they are oops. Pointers+offsets are 56 // derived pointers, and bases can be found from them. Finally, we'll also 57 // track reaching callee-save values. Note that a copy of a callee-save value 58 // "kills" it's source, so that only 1 copy of a callee-save value is alive at 59 // a time. 60 // 61 // We run a simple bitvector liveness pass to help trim out dead oops. Due to 62 // irreducible loops, we can have a reaching def of an oop that only reaches 63 // along one path and no way to know if it's valid or not on the other path. 64 // The bitvectors are quite dense and the liveness pass is fast. 65 // 66 // At GC points, we consult this information to build OopMaps. All reaching 67 // defs typed as oops are added to the OopMap. Only 1 instance of a 68 // callee-save register can be recorded. For derived pointers, we'll have to 69 // find and record the register holding the base. 70 // 71 // The reaching def's is a simple 1-pass worklist approach. I tried a clever 72 // breadth-first approach but it was worse (showed O(n^2) in the 73 // pick-next-block code). 74 // 75 // The relevant data is kept in a struct of arrays (it could just as well be 76 // an array of structs, but the struct-of-arrays is generally a little more 77 // efficient). The arrays are indexed by register number (including 78 // stack-slots as registers) and so is bounded by 200 to 300 elements in 79 // practice. One array will map to a reaching def Node (or NULL for 80 // conflict/dead). The other array will map to a callee-saved register or 81 // OptoReg::Bad for not-callee-saved. 82 83 84 //------------------------------OopFlow---------------------------------------- 85 // Structure to pass around 86 struct OopFlow : public ResourceObj { 87 short *_callees; // Array mapping register to callee-saved 88 Node **_defs; // array mapping register to reaching def 89 // or NULL if dead/conflict 90 // OopFlow structs, when not being actively modified, describe the _end_ of 91 // this block. 92 Block *_b; // Block for this struct 93 OopFlow *_next; // Next free OopFlow 94 // or NULL if dead/conflict 95 Compile* C; 96 97 OopFlow( short *callees, Node **defs, Compile* c ) : _callees(callees), _defs(defs), 98 _b(NULL), _next(NULL), C(c) { } 99 100 // Given reaching-defs for this block start, compute it for this block end 101 void compute_reach( PhaseRegAlloc *regalloc, int max_reg, Dict *safehash ); 102 103 // Merge these two OopFlows into the 'this' pointer. 104 void merge( OopFlow *flow, int max_reg ); 105 106 // Copy a 'flow' over an existing flow 107 void clone( OopFlow *flow, int max_size); 108 109 // Make a new OopFlow from scratch 110 static OopFlow *make( Arena *A, int max_size, Compile* C ); 111 112 // Build an oopmap from the current flow info 113 OopMap *build_oop_map( Node *n, int max_reg, PhaseRegAlloc *regalloc, int* live ); 114 }; 115 116 //------------------------------compute_reach---------------------------------- 117 // Given reaching-defs for this block start, compute it for this block end 118 void OopFlow::compute_reach( PhaseRegAlloc *regalloc, int max_reg, Dict *safehash ) { 119 120 for( uint i=0; i<_b->_nodes.size(); i++ ) { 121 Node *n = _b->_nodes[i]; 122 123 if( n->jvms() ) { // Build an OopMap here? 124 JVMState *jvms = n->jvms(); 125 // no map needed for leaf calls 126 if( n->is_MachSafePoint() && !n->is_MachCallLeaf() ) { 127 int *live = (int*) (*safehash)[n]; 128 assert( live, "must find live" ); 129 n->as_MachSafePoint()->set_oop_map( build_oop_map(n,max_reg,regalloc, live) ); 130 } 131 } 132 133 // Assign new reaching def's. 134 // Note that I padded the _defs and _callees arrays so it's legal 135 // to index at _defs[OptoReg::Bad]. 136 OptoReg::Name first = regalloc->get_reg_first(n); 137 OptoReg::Name second = regalloc->get_reg_second(n); 138 _defs[first] = n; 139 _defs[second] = n; 140 141 // Pass callee-save info around copies 142 int idx = n->is_Copy(); 143 if( idx ) { // Copies move callee-save info 144 OptoReg::Name old_first = regalloc->get_reg_first(n->in(idx)); 145 OptoReg::Name old_second = regalloc->get_reg_second(n->in(idx)); 146 int tmp_first = _callees[old_first]; 147 int tmp_second = _callees[old_second]; 148 _callees[old_first] = OptoReg::Bad; // callee-save is moved, dead in old location 149 _callees[old_second] = OptoReg::Bad; 150 _callees[first] = tmp_first; 151 _callees[second] = tmp_second; 152 } else if( n->is_Phi() ) { // Phis do not mod callee-saves 153 assert( _callees[first] == _callees[regalloc->get_reg_first(n->in(1))], "" ); 154 assert( _callees[second] == _callees[regalloc->get_reg_second(n->in(1))], "" ); 155 assert( _callees[first] == _callees[regalloc->get_reg_first(n->in(n->req()-1))], "" ); 156 assert( _callees[second] == _callees[regalloc->get_reg_second(n->in(n->req()-1))], "" ); 157 } else { 158 _callees[first] = OptoReg::Bad; // No longer holding a callee-save value 159 _callees[second] = OptoReg::Bad; 160 161 // Find base case for callee saves 162 if( n->is_Proj() && n->in(0)->is_Start() ) { 163 if( OptoReg::is_reg(first) && 164 regalloc->_matcher.is_save_on_entry(first) ) 165 _callees[first] = first; 166 if( OptoReg::is_reg(second) && 167 regalloc->_matcher.is_save_on_entry(second) ) 168 _callees[second] = second; 169 } 170 } 171 } 172 } 173 174 //------------------------------merge------------------------------------------ 175 // Merge the given flow into the 'this' flow 176 void OopFlow::merge( OopFlow *flow, int max_reg ) { 177 assert( _b == NULL, "merging into a happy flow" ); 178 assert( flow->_b, "this flow is still alive" ); 179 assert( flow != this, "no self flow" ); 180 181 // Do the merge. If there are any differences, drop to 'bottom' which 182 // is OptoReg::Bad or NULL depending. 183 for( int i=0; i<max_reg; i++ ) { 184 // Merge the callee-save's 185 if( _callees[i] != flow->_callees[i] ) 186 _callees[i] = OptoReg::Bad; 187 // Merge the reaching defs 188 if( _defs[i] != flow->_defs[i] ) 189 _defs[i] = NULL; 190 } 191 192 } 193 194 //------------------------------clone------------------------------------------ 195 void OopFlow::clone( OopFlow *flow, int max_size ) { 196 _b = flow->_b; 197 memcpy( _callees, flow->_callees, sizeof(short)*max_size); 198 memcpy( _defs , flow->_defs , sizeof(Node*)*max_size); 199 } 200 201 //------------------------------make------------------------------------------- 202 OopFlow *OopFlow::make( Arena *A, int max_size, Compile* C ) { 203 short *callees = NEW_ARENA_ARRAY(A,short,max_size+1); 204 Node **defs = NEW_ARENA_ARRAY(A,Node*,max_size+1); 205 debug_only( memset(defs,0,(max_size+1)*sizeof(Node*)) ); 206 OopFlow *flow = new (A) OopFlow(callees+1, defs+1, C); 207 assert( &flow->_callees[OptoReg::Bad] == callees, "Ok to index at OptoReg::Bad" ); 208 assert( &flow->_defs [OptoReg::Bad] == defs , "Ok to index at OptoReg::Bad" ); 209 return flow; 210 } 211 212 //------------------------------bit twiddlers---------------------------------- 213 static int get_live_bit( int *live, int reg ) { 214 return live[reg>>LogBitsPerInt] & (1<<(reg&(BitsPerInt-1))); } 215 static void set_live_bit( int *live, int reg ) { 216 live[reg>>LogBitsPerInt] |= (1<<(reg&(BitsPerInt-1))); } 217 static void clr_live_bit( int *live, int reg ) { 218 live[reg>>LogBitsPerInt] &= ~(1<<(reg&(BitsPerInt-1))); } 219 220 //------------------------------build_oop_map---------------------------------- 221 // Build an oopmap from the current flow info 222 OopMap *OopFlow::build_oop_map( Node *n, int max_reg, PhaseRegAlloc *regalloc, int* live ) { 223 int framesize = regalloc->_framesize; 224 int max_inarg_slot = OptoReg::reg2stack(regalloc->_matcher._new_SP); 225 debug_only( char *dup_check = NEW_RESOURCE_ARRAY(char,OptoReg::stack0()); 226 memset(dup_check,0,OptoReg::stack0()) ); 227 228 OopMap *omap = new OopMap( framesize, max_inarg_slot ); 229 MachCallNode *mcall = n->is_MachCall() ? n->as_MachCall() : NULL; 230 JVMState* jvms = n->jvms(); 231 232 // For all registers do... 233 for( int reg=0; reg<max_reg; reg++ ) { 234 if( get_live_bit(live,reg) == 0 ) 235 continue; // Ignore if not live 236 237 // %%% C2 can use 2 OptoRegs when the physical register is only one 64bit 238 // register in that case we'll get an non-concrete register for the second 239 // half. We only need to tell the map the register once! 240 // 241 // However for the moment we disable this change and leave things as they 242 // were. 243 244 VMReg r = OptoReg::as_VMReg(OptoReg::Name(reg), framesize, max_inarg_slot); 245 246 if (false && r->is_reg() && !r->is_concrete()) { 247 continue; 248 } 249 250 // See if dead (no reaching def). 251 Node *def = _defs[reg]; // Get reaching def 252 assert( def, "since live better have reaching def" ); 253 254 // Classify the reaching def as oop, derived, callee-save, dead, or other 255 const Type *t = def->bottom_type(); 256 if( t->isa_oop_ptr() ) { // Oop or derived? 257 assert( !OptoReg::is_valid(_callees[reg]), "oop can't be callee save" ); 258 #ifdef _LP64 259 // 64-bit pointers record oop-ishness on 2 aligned adjacent registers. 260 // Make sure both are record from the same reaching def, but do not 261 // put both into the oopmap. 262 if( (reg&1) == 1 ) { // High half of oop-pair? 263 assert( _defs[reg-1] == _defs[reg], "both halves from same reaching def" ); 264 continue; // Do not record high parts in oopmap 265 } 266 #endif 267 268 // Check for a legal reg name in the oopMap and bailout if it is not. 269 if (!omap->legal_vm_reg_name(r)) { 270 regalloc->C->record_method_not_compilable("illegal oopMap register name"); 271 continue; 272 } 273 if( t->is_ptr()->_offset == 0 ) { // Not derived? 274 if( mcall ) { 275 // Outgoing argument GC mask responsibility belongs to the callee, 276 // not the caller. Inspect the inputs to the call, to see if 277 // this live-range is one of them. 278 uint cnt = mcall->tf()->domain()->cnt(); 279 uint j; 280 for( j = TypeFunc::Parms; j < cnt; j++) 281 if( mcall->in(j) == def ) 282 break; // reaching def is an argument oop 283 if( j < cnt ) // arg oops dont go in GC map 284 continue; // Continue on to the next register 285 } 286 omap->set_oop(r); 287 } else { // Else it's derived. 288 // Find the base of the derived value. 289 uint i; 290 // Fast, common case, scan 291 for( i = jvms->oopoff(); i < n->req(); i+=2 ) 292 if( n->in(i) == def ) break; // Common case 293 if( i == n->req() ) { // Missed, try a more generous scan 294 // Scan again, but this time peek through copies 295 for( i = jvms->oopoff(); i < n->req(); i+=2 ) { 296 Node *m = n->in(i); // Get initial derived value 297 while( 1 ) { 298 Node *d = def; // Get initial reaching def 299 while( 1 ) { // Follow copies of reaching def to end 300 if( m == d ) goto found; // breaks 3 loops 301 int idx = d->is_Copy(); 302 if( !idx ) break; 303 d = d->in(idx); // Link through copy 304 } 305 int idx = m->is_Copy(); 306 if( !idx ) break; 307 m = m->in(idx); 308 } 309 } 310 guarantee( 0, "must find derived/base pair" ); 311 } 312 found: ; 313 Node *base = n->in(i+1); // Base is other half of pair 314 int breg = regalloc->get_reg_first(base); 315 VMReg b = OptoReg::as_VMReg(OptoReg::Name(breg), framesize, max_inarg_slot); 316 317 // I record liveness at safepoints BEFORE I make the inputs 318 // live. This is because argument oops are NOT live at a 319 // safepoint (or at least they cannot appear in the oopmap). 320 // Thus bases of base/derived pairs might not be in the 321 // liveness data but they need to appear in the oopmap. 322 if( get_live_bit(live,breg) == 0 ) {// Not live? 323 // Flag it, so next derived pointer won't re-insert into oopmap 324 set_live_bit(live,breg); 325 // Already missed our turn? 326 if( breg < reg ) { 327 if (b->is_stack() || b->is_concrete() || true ) { 328 omap->set_oop( b); 329 } 330 } 331 } 332 if (b->is_stack() || b->is_concrete() || true ) { 333 omap->set_derived_oop( r, b); 334 } 335 } 336 337 } else if( t->isa_narrowoop() ) { 338 assert( !OptoReg::is_valid(_callees[reg]), "oop can't be callee save" ); 339 // Check for a legal reg name in the oopMap and bailout if it is not. 340 if (!omap->legal_vm_reg_name(r)) { 341 regalloc->C->record_method_not_compilable("illegal oopMap register name"); 342 continue; 343 } 344 if( mcall ) { 345 // Outgoing argument GC mask responsibility belongs to the callee, 346 // not the caller. Inspect the inputs to the call, to see if 347 // this live-range is one of them. 348 uint cnt = mcall->tf()->domain()->cnt(); 349 uint j; 350 for( j = TypeFunc::Parms; j < cnt; j++) 351 if( mcall->in(j) == def ) 352 break; // reaching def is an argument oop 353 if( j < cnt ) // arg oops dont go in GC map 354 continue; // Continue on to the next register 355 } 356 omap->set_narrowoop(r); 357 } else if( OptoReg::is_valid(_callees[reg])) { // callee-save? 358 // It's a callee-save value 359 assert( dup_check[_callees[reg]]==0, "trying to callee save same reg twice" ); 360 debug_only( dup_check[_callees[reg]]=1; ) 361 VMReg callee = OptoReg::as_VMReg(OptoReg::Name(_callees[reg])); 362 if ( callee->is_concrete() || true ) { 363 omap->set_callee_saved( r, callee); 364 } 365 366 } else { 367 // Other - some reaching non-oop value 368 omap->set_value( r); 369 #ifdef ASSERT 370 if( t->isa_rawptr() && C->cfg()->_raw_oops.member(def) ) { 371 def->dump(); 372 n->dump(); 373 assert(false, "there should be a oop in OopMap instead of a live raw oop at safepoint"); 374 } 375 #endif 376 } 377 378 } 379 380 #ifdef ASSERT 381 /* Nice, Intel-only assert 382 int cnt_callee_saves=0; 383 int reg2 = 0; 384 while (OptoReg::is_reg(reg2)) { 385 if( dup_check[reg2] != 0) cnt_callee_saves++; 386 assert( cnt_callee_saves==3 || cnt_callee_saves==5, "missed some callee-save" ); 387 reg2++; 388 } 389 */ 390 #endif 391 392 #ifdef ASSERT 393 for( OopMapStream oms1(omap, OopMapValue::derived_oop_value); !oms1.is_done(); oms1.next()) { 394 OopMapValue omv1 = oms1.current(); 395 bool found = false; 396 for( OopMapStream oms2(omap,OopMapValue::oop_value); !oms2.is_done(); oms2.next()) { 397 if( omv1.content_reg() == oms2.current().reg() ) { 398 found = true; 399 break; 400 } 401 } 402 assert( found, "derived with no base in oopmap" ); 403 } 404 #endif 405 406 return omap; 407 } 408 409 //------------------------------do_liveness------------------------------------ 410 // Compute backwards liveness on registers 411 static void do_liveness( PhaseRegAlloc *regalloc, PhaseCFG *cfg, Block_List *worklist, int max_reg_ints, Arena *A, Dict *safehash ) { 412 int *live = NEW_ARENA_ARRAY(A, int, (cfg->_num_blocks+1) * max_reg_ints); 413 int *tmp_live = &live[cfg->_num_blocks * max_reg_ints]; 414 Node *root = cfg->C->root(); 415 // On CISC platforms, get the node representing the stack pointer that regalloc 416 // used for spills 417 Node *fp = NodeSentinel; 418 if (UseCISCSpill && root->req() > 1) { 419 fp = root->in(1)->in(TypeFunc::FramePtr); 420 } 421 memset( live, 0, cfg->_num_blocks * (max_reg_ints<<LogBytesPerInt) ); 422 // Push preds onto worklist 423 for( uint i=1; i<root->req(); i++ ) 424 worklist->push(cfg->_bbs[root->in(i)->_idx]); 425 426 // ZKM.jar includes tiny infinite loops which are unreached from below. 427 // If we missed any blocks, we'll retry here after pushing all missed 428 // blocks on the worklist. Normally this outer loop never trips more 429 // than once. 430 while( 1 ) { 431 432 while( worklist->size() ) { // Standard worklist algorithm 433 Block *b = worklist->rpop(); 434 435 // Copy first successor into my tmp_live space 436 int s0num = b->_succs[0]->_pre_order; 437 int *t = &live[s0num*max_reg_ints]; 438 for( int i=0; i<max_reg_ints; i++ ) 439 tmp_live[i] = t[i]; 440 441 // OR in the remaining live registers 442 for( uint j=1; j<b->_num_succs; j++ ) { 443 uint sjnum = b->_succs[j]->_pre_order; 444 int *t = &live[sjnum*max_reg_ints]; 445 for( int i=0; i<max_reg_ints; i++ ) 446 tmp_live[i] |= t[i]; 447 } 448 449 // Now walk tmp_live up the block backwards, computing live 450 for( int k=b->_nodes.size()-1; k>=0; k-- ) { 451 Node *n = b->_nodes[k]; 452 // KILL def'd bits 453 int first = regalloc->get_reg_first(n); 454 int second = regalloc->get_reg_second(n); 455 if( OptoReg::is_valid(first) ) clr_live_bit(tmp_live,first); 456 if( OptoReg::is_valid(second) ) clr_live_bit(tmp_live,second); 457 458 MachNode *m = n->is_Mach() ? n->as_Mach() : NULL; 459 460 // Check if m is potentially a CISC alternate instruction (i.e, possibly 461 // synthesized by RegAlloc from a conventional instruction and a 462 // spilled input) 463 bool is_cisc_alternate = false; 464 if (UseCISCSpill && m) { 465 is_cisc_alternate = m->is_cisc_alternate(); 466 } 467 468 // GEN use'd bits 469 for( uint l=1; l<n->req(); l++ ) { 470 Node *def = n->in(l); 471 assert(def != 0, "input edge required"); 472 int first = regalloc->get_reg_first(def); 473 int second = regalloc->get_reg_second(def); 474 if( OptoReg::is_valid(first) ) set_live_bit(tmp_live,first); 475 if( OptoReg::is_valid(second) ) set_live_bit(tmp_live,second); 476 // If we use the stack pointer in a cisc-alternative instruction, 477 // check for use as a memory operand. Then reconstruct the RegName 478 // for this stack location, and set the appropriate bit in the 479 // live vector 4987749. 480 if (is_cisc_alternate && def == fp) { 481 const TypePtr *adr_type = NULL; 482 intptr_t offset; 483 const Node* base = m->get_base_and_disp(offset, adr_type); 484 if (base == NodeSentinel) { 485 // Machnode has multiple memory inputs. We are unable to reason 486 // with these, but are presuming (with trepidation) that not any of 487 // them are oops. This can be fixed by making get_base_and_disp() 488 // look at a specific input instead of all inputs. 489 assert(!def->bottom_type()->isa_oop_ptr(), "expecting non-oop mem input"); 490 } else if (base != fp || offset == Type::OffsetBot) { 491 // Do nothing: the fp operand is either not from a memory use 492 // (base == NULL) OR the fp is used in a non-memory context 493 // (base is some other register) OR the offset is not constant, 494 // so it is not a stack slot. 495 } else { 496 assert(offset >= 0, "unexpected negative offset"); 497 offset -= (offset % jintSize); // count the whole word 498 int stack_reg = regalloc->offset2reg(offset); 499 if (OptoReg::is_stack(stack_reg)) { 500 set_live_bit(tmp_live, stack_reg); 501 } else { 502 assert(false, "stack_reg not on stack?"); 503 } 504 } 505 } 506 } 507 508 if( n->jvms() ) { // Record liveness at safepoint 509 510 // This placement of this stanza means inputs to calls are 511 // considered live at the callsite's OopMap. Argument oops are 512 // hence live, but NOT included in the oopmap. See cutout in 513 // build_oop_map. Debug oops are live (and in OopMap). 514 int *n_live = NEW_ARENA_ARRAY(A, int, max_reg_ints); 515 for( int l=0; l<max_reg_ints; l++ ) 516 n_live[l] = tmp_live[l]; 517 safehash->Insert(n,n_live); 518 } 519 520 } 521 522 // Now at block top, see if we have any changes. If so, propagate 523 // to prior blocks. 524 int *old_live = &live[b->_pre_order*max_reg_ints]; 525 int l; 526 for( l=0; l<max_reg_ints; l++ ) 527 if( tmp_live[l] != old_live[l] ) 528 break; 529 if( l<max_reg_ints ) { // Change! 530 // Copy in new value 531 for( l=0; l<max_reg_ints; l++ ) 532 old_live[l] = tmp_live[l]; 533 // Push preds onto worklist 534 for( l=1; l<(int)b->num_preds(); l++ ) 535 worklist->push(cfg->_bbs[b->pred(l)->_idx]); 536 } 537 } 538 539 // Scan for any missing safepoints. Happens to infinite loops 540 // ala ZKM.jar 541 uint i; 542 for( i=1; i<cfg->_num_blocks; i++ ) { 543 Block *b = cfg->_blocks[i]; 544 uint j; 545 for( j=1; j<b->_nodes.size(); j++ ) 546 if( b->_nodes[j]->jvms() && 547 (*safehash)[b->_nodes[j]] == NULL ) 548 break; 549 if( j<b->_nodes.size() ) break; 550 } 551 if( i == cfg->_num_blocks ) 552 break; // Got 'em all 553 #ifndef PRODUCT 554 if( PrintOpto && Verbose ) 555 tty->print_cr("retripping live calc"); 556 #endif 557 // Force the issue (expensively): recheck everybody 558 for( i=1; i<cfg->_num_blocks; i++ ) 559 worklist->push(cfg->_blocks[i]); 560 } 561 562 } 563 564 //------------------------------BuildOopMaps----------------------------------- 565 // Collect GC mask info - where are all the OOPs? 566 void Compile::BuildOopMaps() { 567 NOT_PRODUCT( TracePhase t3("bldOopMaps", &_t_buildOopMaps, TimeCompiler); ) 568 // Can't resource-mark because I need to leave all those OopMaps around, 569 // or else I need to resource-mark some arena other than the default. 570 // ResourceMark rm; // Reclaim all OopFlows when done 571 int max_reg = _regalloc->_max_reg; // Current array extent 572 573 Arena *A = Thread::current()->resource_area(); 574 Block_List worklist; // Worklist of pending blocks 575 576 int max_reg_ints = round_to(max_reg, BitsPerInt)>>LogBitsPerInt; 577 Dict *safehash = NULL; // Used for assert only 578 // Compute a backwards liveness per register. Needs a bitarray of 579 // #blocks x (#registers, rounded up to ints) 580 safehash = new Dict(cmpkey,hashkey,A); 581 do_liveness( _regalloc, _cfg, &worklist, max_reg_ints, A, safehash ); 582 OopFlow *free_list = NULL; // Free, unused 583 584 // Array mapping blocks to completed oopflows 585 OopFlow **flows = NEW_ARENA_ARRAY(A, OopFlow*, _cfg->_num_blocks); 586 memset( flows, 0, _cfg->_num_blocks*sizeof(OopFlow*) ); 587 588 589 // Do the first block 'by hand' to prime the worklist 590 Block *entry = _cfg->_blocks[1]; 591 OopFlow *rootflow = OopFlow::make(A,max_reg,this); 592 // Initialize to 'bottom' (not 'top') 593 memset( rootflow->_callees, OptoReg::Bad, max_reg*sizeof(short) ); 594 memset( rootflow->_defs , 0, max_reg*sizeof(Node*) ); 595 flows[entry->_pre_order] = rootflow; 596 597 // Do the first block 'by hand' to prime the worklist 598 rootflow->_b = entry; 599 rootflow->compute_reach( _regalloc, max_reg, safehash ); 600 for( uint i=0; i<entry->_num_succs; i++ ) 601 worklist.push(entry->_succs[i]); 602 603 // Now worklist contains blocks which have some, but perhaps not all, 604 // predecessors visited. 605 while( worklist.size() ) { 606 // Scan for a block with all predecessors visited, or any randoms slob 607 // otherwise. All-preds-visited order allows me to recycle OopFlow 608 // structures rapidly and cut down on the memory footprint. 609 // Note: not all predecessors might be visited yet (must happen for 610 // irreducible loops). This is OK, since every live value must have the 611 // SAME reaching def for the block, so any reaching def is OK. 612 uint i; 613 614 Block *b = worklist.pop(); 615 // Ignore root block 616 if( b == _cfg->_broot ) continue; 617 // Block is already done? Happens if block has several predecessors, 618 // he can get on the worklist more than once. 619 if( flows[b->_pre_order] ) continue; 620 621 // If this block has a visited predecessor AND that predecessor has this 622 // last block as his only undone child, we can move the OopFlow from the 623 // pred to this block. Otherwise we have to grab a new OopFlow. 624 OopFlow *flow = NULL; // Flag for finding optimized flow 625 Block *pred = (Block*)0xdeadbeef; 626 uint j; 627 // Scan this block's preds to find a done predecessor 628 for( j=1; j<b->num_preds(); j++ ) { 629 Block *p = _cfg->_bbs[b->pred(j)->_idx]; 630 OopFlow *p_flow = flows[p->_pre_order]; 631 if( p_flow ) { // Predecessor is done 632 assert( p_flow->_b == p, "cross check" ); 633 pred = p; // Record some predecessor 634 // If all successors of p are done except for 'b', then we can carry 635 // p_flow forward to 'b' without copying, otherwise we have to draw 636 // from the free_list and clone data. 637 uint k; 638 for( k=0; k<p->_num_succs; k++ ) 639 if( !flows[p->_succs[k]->_pre_order] && 640 p->_succs[k] != b ) 641 break; 642 643 // Either carry-forward the now-unused OopFlow for b's use 644 // or draw a new one from the free list 645 if( k==p->_num_succs ) { 646 flow = p_flow; 647 break; // Found an ideal pred, use him 648 } 649 } 650 } 651 652 if( flow ) { 653 // We have an OopFlow that's the last-use of a predecessor. 654 // Carry it forward. 655 } else { // Draw a new OopFlow from the freelist 656 if( !free_list ) 657 free_list = OopFlow::make(A,max_reg,C); 658 flow = free_list; 659 assert( flow->_b == NULL, "oopFlow is not free" ); 660 free_list = flow->_next; 661 flow->_next = NULL; 662 663 // Copy/clone over the data 664 flow->clone(flows[pred->_pre_order], max_reg); 665 } 666 667 // Mark flow for block. Blocks can only be flowed over once, 668 // because after the first time they are guarded from entering 669 // this code again. 670 assert( flow->_b == pred, "have some prior flow" ); 671 flow->_b = NULL; 672 673 // Now push flow forward 674 flows[b->_pre_order] = flow;// Mark flow for this block 675 flow->_b = b; 676 flow->compute_reach( _regalloc, max_reg, safehash ); 677 678 // Now push children onto worklist 679 for( i=0; i<b->_num_succs; i++ ) 680 worklist.push(b->_succs[i]); 681 682 } 683 }