1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/opto/buildOopMap.cpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,623 @@
1.4 +/*
1.5 + * Copyright 2002-2007 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#include "incls/_precompiled.incl"
1.29 +#include "incls/_buildOopMap.cpp.incl"
1.30 +
1.31 +// The functions in this file builds OopMaps after all scheduling is done.
1.32 +//
1.33 +// OopMaps contain a list of all registers and stack-slots containing oops (so
1.34 +// they can be updated by GC). OopMaps also contain a list of derived-pointer
1.35 +// base-pointer pairs. When the base is moved, the derived pointer moves to
1.36 +// follow it. Finally, any registers holding callee-save values are also
1.37 +// recorded. These might contain oops, but only the caller knows.
1.38 +//
1.39 +// BuildOopMaps implements a simple forward reaching-defs solution. At each
1.40 +// GC point we'll have the reaching-def Nodes. If the reaching Nodes are
1.41 +// typed as pointers (no offset), then they are oops. Pointers+offsets are
1.42 +// derived pointers, and bases can be found from them. Finally, we'll also
1.43 +// track reaching callee-save values. Note that a copy of a callee-save value
1.44 +// "kills" it's source, so that only 1 copy of a callee-save value is alive at
1.45 +// a time.
1.46 +//
1.47 +// We run a simple bitvector liveness pass to help trim out dead oops. Due to
1.48 +// irreducible loops, we can have a reaching def of an oop that only reaches
1.49 +// along one path and no way to know if it's valid or not on the other path.
1.50 +// The bitvectors are quite dense and the liveness pass is fast.
1.51 +//
1.52 +// At GC points, we consult this information to build OopMaps. All reaching
1.53 +// defs typed as oops are added to the OopMap. Only 1 instance of a
1.54 +// callee-save register can be recorded. For derived pointers, we'll have to
1.55 +// find and record the register holding the base.
1.56 +//
1.57 +// The reaching def's is a simple 1-pass worklist approach. I tried a clever
1.58 +// breadth-first approach but it was worse (showed O(n^2) in the
1.59 +// pick-next-block code).
1.60 +//
1.61 +// The relevent data is kept in a struct of arrays (it could just as well be
1.62 +// an array of structs, but the struct-of-arrays is generally a little more
1.63 +// efficient). The arrays are indexed by register number (including
1.64 +// stack-slots as registers) and so is bounded by 200 to 300 elements in
1.65 +// practice. One array will map to a reaching def Node (or NULL for
1.66 +// conflict/dead). The other array will map to a callee-saved register or
1.67 +// OptoReg::Bad for not-callee-saved.
1.68 +
1.69 +
1.70 +//------------------------------OopFlow----------------------------------------
1.71 +// Structure to pass around
1.72 +struct OopFlow : public ResourceObj {
1.73 + short *_callees; // Array mapping register to callee-saved
1.74 + Node **_defs; // array mapping register to reaching def
1.75 + // or NULL if dead/conflict
1.76 + // OopFlow structs, when not being actively modified, describe the _end_ of
1.77 + // this block.
1.78 + Block *_b; // Block for this struct
1.79 + OopFlow *_next; // Next free OopFlow
1.80 +
1.81 + OopFlow( short *callees, Node **defs ) : _callees(callees), _defs(defs),
1.82 + _b(NULL), _next(NULL) { }
1.83 +
1.84 + // Given reaching-defs for this block start, compute it for this block end
1.85 + void compute_reach( PhaseRegAlloc *regalloc, int max_reg, Dict *safehash );
1.86 +
1.87 + // Merge these two OopFlows into the 'this' pointer.
1.88 + void merge( OopFlow *flow, int max_reg );
1.89 +
1.90 + // Copy a 'flow' over an existing flow
1.91 + void clone( OopFlow *flow, int max_size);
1.92 +
1.93 + // Make a new OopFlow from scratch
1.94 + static OopFlow *make( Arena *A, int max_size );
1.95 +
1.96 + // Build an oopmap from the current flow info
1.97 + OopMap *build_oop_map( Node *n, int max_reg, PhaseRegAlloc *regalloc, int* live );
1.98 +};
1.99 +
1.100 +//------------------------------compute_reach----------------------------------
1.101 +// Given reaching-defs for this block start, compute it for this block end
1.102 +void OopFlow::compute_reach( PhaseRegAlloc *regalloc, int max_reg, Dict *safehash ) {
1.103 +
1.104 + for( uint i=0; i<_b->_nodes.size(); i++ ) {
1.105 + Node *n = _b->_nodes[i];
1.106 +
1.107 + if( n->jvms() ) { // Build an OopMap here?
1.108 + JVMState *jvms = n->jvms();
1.109 + // no map needed for leaf calls
1.110 + if( n->is_MachSafePoint() && !n->is_MachCallLeaf() ) {
1.111 + int *live = (int*) (*safehash)[n];
1.112 + assert( live, "must find live" );
1.113 + n->as_MachSafePoint()->set_oop_map( build_oop_map(n,max_reg,regalloc, live) );
1.114 + }
1.115 + }
1.116 +
1.117 + // Assign new reaching def's.
1.118 + // Note that I padded the _defs and _callees arrays so it's legal
1.119 + // to index at _defs[OptoReg::Bad].
1.120 + OptoReg::Name first = regalloc->get_reg_first(n);
1.121 + OptoReg::Name second = regalloc->get_reg_second(n);
1.122 + _defs[first] = n;
1.123 + _defs[second] = n;
1.124 +
1.125 + // Pass callee-save info around copies
1.126 + int idx = n->is_Copy();
1.127 + if( idx ) { // Copies move callee-save info
1.128 + OptoReg::Name old_first = regalloc->get_reg_first(n->in(idx));
1.129 + OptoReg::Name old_second = regalloc->get_reg_second(n->in(idx));
1.130 + int tmp_first = _callees[old_first];
1.131 + int tmp_second = _callees[old_second];
1.132 + _callees[old_first] = OptoReg::Bad; // callee-save is moved, dead in old location
1.133 + _callees[old_second] = OptoReg::Bad;
1.134 + _callees[first] = tmp_first;
1.135 + _callees[second] = tmp_second;
1.136 + } else if( n->is_Phi() ) { // Phis do not mod callee-saves
1.137 + assert( _callees[first] == _callees[regalloc->get_reg_first(n->in(1))], "" );
1.138 + assert( _callees[second] == _callees[regalloc->get_reg_second(n->in(1))], "" );
1.139 + assert( _callees[first] == _callees[regalloc->get_reg_first(n->in(n->req()-1))], "" );
1.140 + assert( _callees[second] == _callees[regalloc->get_reg_second(n->in(n->req()-1))], "" );
1.141 + } else {
1.142 + _callees[first] = OptoReg::Bad; // No longer holding a callee-save value
1.143 + _callees[second] = OptoReg::Bad;
1.144 +
1.145 + // Find base case for callee saves
1.146 + if( n->is_Proj() && n->in(0)->is_Start() ) {
1.147 + if( OptoReg::is_reg(first) &&
1.148 + regalloc->_matcher.is_save_on_entry(first) )
1.149 + _callees[first] = first;
1.150 + if( OptoReg::is_reg(second) &&
1.151 + regalloc->_matcher.is_save_on_entry(second) )
1.152 + _callees[second] = second;
1.153 + }
1.154 + }
1.155 + }
1.156 +}
1.157 +
1.158 +//------------------------------merge------------------------------------------
1.159 +// Merge the given flow into the 'this' flow
1.160 +void OopFlow::merge( OopFlow *flow, int max_reg ) {
1.161 + assert( _b == NULL, "merging into a happy flow" );
1.162 + assert( flow->_b, "this flow is still alive" );
1.163 + assert( flow != this, "no self flow" );
1.164 +
1.165 + // Do the merge. If there are any differences, drop to 'bottom' which
1.166 + // is OptoReg::Bad or NULL depending.
1.167 + for( int i=0; i<max_reg; i++ ) {
1.168 + // Merge the callee-save's
1.169 + if( _callees[i] != flow->_callees[i] )
1.170 + _callees[i] = OptoReg::Bad;
1.171 + // Merge the reaching defs
1.172 + if( _defs[i] != flow->_defs[i] )
1.173 + _defs[i] = NULL;
1.174 + }
1.175 +
1.176 +}
1.177 +
1.178 +//------------------------------clone------------------------------------------
1.179 +void OopFlow::clone( OopFlow *flow, int max_size ) {
1.180 + _b = flow->_b;
1.181 + memcpy( _callees, flow->_callees, sizeof(short)*max_size);
1.182 + memcpy( _defs , flow->_defs , sizeof(Node*)*max_size);
1.183 +}
1.184 +
1.185 +//------------------------------make-------------------------------------------
1.186 +OopFlow *OopFlow::make( Arena *A, int max_size ) {
1.187 + short *callees = NEW_ARENA_ARRAY(A,short,max_size+1);
1.188 + Node **defs = NEW_ARENA_ARRAY(A,Node*,max_size+1);
1.189 + debug_only( memset(defs,0,(max_size+1)*sizeof(Node*)) );
1.190 + OopFlow *flow = new (A) OopFlow(callees+1, defs+1);
1.191 + assert( &flow->_callees[OptoReg::Bad] == callees, "Ok to index at OptoReg::Bad" );
1.192 + assert( &flow->_defs [OptoReg::Bad] == defs , "Ok to index at OptoReg::Bad" );
1.193 + return flow;
1.194 +}
1.195 +
1.196 +//------------------------------bit twiddlers----------------------------------
1.197 +static int get_live_bit( int *live, int reg ) {
1.198 + return live[reg>>LogBitsPerInt] & (1<<(reg&(BitsPerInt-1))); }
1.199 +static void set_live_bit( int *live, int reg ) {
1.200 + live[reg>>LogBitsPerInt] |= (1<<(reg&(BitsPerInt-1))); }
1.201 +static void clr_live_bit( int *live, int reg ) {
1.202 + live[reg>>LogBitsPerInt] &= ~(1<<(reg&(BitsPerInt-1))); }
1.203 +
1.204 +//------------------------------build_oop_map----------------------------------
1.205 +// Build an oopmap from the current flow info
1.206 +OopMap *OopFlow::build_oop_map( Node *n, int max_reg, PhaseRegAlloc *regalloc, int* live ) {
1.207 + int framesize = regalloc->_framesize;
1.208 + int max_inarg_slot = OptoReg::reg2stack(regalloc->_matcher._new_SP);
1.209 + debug_only( char *dup_check = NEW_RESOURCE_ARRAY(char,OptoReg::stack0());
1.210 + memset(dup_check,0,OptoReg::stack0()) );
1.211 +
1.212 + OopMap *omap = new OopMap( framesize, max_inarg_slot );
1.213 + MachCallNode *mcall = n->is_MachCall() ? n->as_MachCall() : NULL;
1.214 + JVMState* jvms = n->jvms();
1.215 +
1.216 + // For all registers do...
1.217 + for( int reg=0; reg<max_reg; reg++ ) {
1.218 + if( get_live_bit(live,reg) == 0 )
1.219 + continue; // Ignore if not live
1.220 +
1.221 + // %%% C2 can use 2 OptoRegs when the physical register is only one 64bit
1.222 + // register in that case we'll get an non-concrete register for the second
1.223 + // half. We only need to tell the map the register once!
1.224 + //
1.225 + // However for the moment we disable this change and leave things as they
1.226 + // were.
1.227 +
1.228 + VMReg r = OptoReg::as_VMReg(OptoReg::Name(reg), framesize, max_inarg_slot);
1.229 +
1.230 + if (false && r->is_reg() && !r->is_concrete()) {
1.231 + continue;
1.232 + }
1.233 +
1.234 + // See if dead (no reaching def).
1.235 + Node *def = _defs[reg]; // Get reaching def
1.236 + assert( def, "since live better have reaching def" );
1.237 +
1.238 + // Classify the reaching def as oop, derived, callee-save, dead, or other
1.239 + const Type *t = def->bottom_type();
1.240 + if( t->isa_oop_ptr() ) { // Oop or derived?
1.241 + assert( !OptoReg::is_valid(_callees[reg]), "oop can't be callee save" );
1.242 +#ifdef _LP64
1.243 + // 64-bit pointers record oop-ishness on 2 aligned adjacent registers.
1.244 + // Make sure both are record from the same reaching def, but do not
1.245 + // put both into the oopmap.
1.246 + if( (reg&1) == 1 ) { // High half of oop-pair?
1.247 + assert( _defs[reg-1] == _defs[reg], "both halves from same reaching def" );
1.248 + continue; // Do not record high parts in oopmap
1.249 + }
1.250 +#endif
1.251 +
1.252 + // Check for a legal reg name in the oopMap and bailout if it is not.
1.253 + if (!omap->legal_vm_reg_name(r)) {
1.254 + regalloc->C->record_method_not_compilable("illegal oopMap register name");
1.255 + continue;
1.256 + }
1.257 + if( t->is_ptr()->_offset == 0 ) { // Not derived?
1.258 + if( mcall ) {
1.259 + // Outgoing argument GC mask responsibility belongs to the callee,
1.260 + // not the caller. Inspect the inputs to the call, to see if
1.261 + // this live-range is one of them.
1.262 + uint cnt = mcall->tf()->domain()->cnt();
1.263 + uint j;
1.264 + for( j = TypeFunc::Parms; j < cnt; j++)
1.265 + if( mcall->in(j) == def )
1.266 + break; // reaching def is an argument oop
1.267 + if( j < cnt ) // arg oops dont go in GC map
1.268 + continue; // Continue on to the next register
1.269 + }
1.270 + omap->set_oop(r);
1.271 + } else { // Else it's derived.
1.272 + // Find the base of the derived value.
1.273 + uint i;
1.274 + // Fast, common case, scan
1.275 + for( i = jvms->oopoff(); i < n->req(); i+=2 )
1.276 + if( n->in(i) == def ) break; // Common case
1.277 + if( i == n->req() ) { // Missed, try a more generous scan
1.278 + // Scan again, but this time peek through copies
1.279 + for( i = jvms->oopoff(); i < n->req(); i+=2 ) {
1.280 + Node *m = n->in(i); // Get initial derived value
1.281 + while( 1 ) {
1.282 + Node *d = def; // Get initial reaching def
1.283 + while( 1 ) { // Follow copies of reaching def to end
1.284 + if( m == d ) goto found; // breaks 3 loops
1.285 + int idx = d->is_Copy();
1.286 + if( !idx ) break;
1.287 + d = d->in(idx); // Link through copy
1.288 + }
1.289 + int idx = m->is_Copy();
1.290 + if( !idx ) break;
1.291 + m = m->in(idx);
1.292 + }
1.293 + }
1.294 + guarantee( 0, "must find derived/base pair" );
1.295 + }
1.296 + found: ;
1.297 + Node *base = n->in(i+1); // Base is other half of pair
1.298 + int breg = regalloc->get_reg_first(base);
1.299 + VMReg b = OptoReg::as_VMReg(OptoReg::Name(breg), framesize, max_inarg_slot);
1.300 +
1.301 + // I record liveness at safepoints BEFORE I make the inputs
1.302 + // live. This is because argument oops are NOT live at a
1.303 + // safepoint (or at least they cannot appear in the oopmap).
1.304 + // Thus bases of base/derived pairs might not be in the
1.305 + // liveness data but they need to appear in the oopmap.
1.306 + if( get_live_bit(live,breg) == 0 ) {// Not live?
1.307 + // Flag it, so next derived pointer won't re-insert into oopmap
1.308 + set_live_bit(live,breg);
1.309 + // Already missed our turn?
1.310 + if( breg < reg ) {
1.311 + if (b->is_stack() || b->is_concrete() || true ) {
1.312 + omap->set_oop( b);
1.313 + }
1.314 + }
1.315 + }
1.316 + if (b->is_stack() || b->is_concrete() || true ) {
1.317 + omap->set_derived_oop( r, b);
1.318 + }
1.319 + }
1.320 +
1.321 + } else if( OptoReg::is_valid(_callees[reg])) { // callee-save?
1.322 + // It's a callee-save value
1.323 + assert( dup_check[_callees[reg]]==0, "trying to callee save same reg twice" );
1.324 + debug_only( dup_check[_callees[reg]]=1; )
1.325 + VMReg callee = OptoReg::as_VMReg(OptoReg::Name(_callees[reg]));
1.326 + if ( callee->is_concrete() || true ) {
1.327 + omap->set_callee_saved( r, callee);
1.328 + }
1.329 +
1.330 + } else {
1.331 + // Other - some reaching non-oop value
1.332 + omap->set_value( r);
1.333 + }
1.334 +
1.335 + }
1.336 +
1.337 +#ifdef ASSERT
1.338 + /* Nice, Intel-only assert
1.339 + int cnt_callee_saves=0;
1.340 + int reg2 = 0;
1.341 + while (OptoReg::is_reg(reg2)) {
1.342 + if( dup_check[reg2] != 0) cnt_callee_saves++;
1.343 + assert( cnt_callee_saves==3 || cnt_callee_saves==5, "missed some callee-save" );
1.344 + reg2++;
1.345 + }
1.346 + */
1.347 +#endif
1.348 +
1.349 + return omap;
1.350 +}
1.351 +
1.352 +//------------------------------do_liveness------------------------------------
1.353 +// Compute backwards liveness on registers
1.354 +static void do_liveness( PhaseRegAlloc *regalloc, PhaseCFG *cfg, Block_List *worklist, int max_reg_ints, Arena *A, Dict *safehash ) {
1.355 + int *live = NEW_ARENA_ARRAY(A, int, (cfg->_num_blocks+1) * max_reg_ints);
1.356 + int *tmp_live = &live[cfg->_num_blocks * max_reg_ints];
1.357 + Node *root = cfg->C->root();
1.358 + // On CISC platforms, get the node representing the stack pointer that regalloc
1.359 + // used for spills
1.360 + Node *fp = NodeSentinel;
1.361 + if (UseCISCSpill && root->req() > 1) {
1.362 + fp = root->in(1)->in(TypeFunc::FramePtr);
1.363 + }
1.364 + memset( live, 0, cfg->_num_blocks * (max_reg_ints<<LogBytesPerInt) );
1.365 + // Push preds onto worklist
1.366 + for( uint i=1; i<root->req(); i++ )
1.367 + worklist->push(cfg->_bbs[root->in(i)->_idx]);
1.368 +
1.369 + // ZKM.jar includes tiny infinite loops which are unreached from below.
1.370 + // If we missed any blocks, we'll retry here after pushing all missed
1.371 + // blocks on the worklist. Normally this outer loop never trips more
1.372 + // than once.
1.373 + while( 1 ) {
1.374 +
1.375 + while( worklist->size() ) { // Standard worklist algorithm
1.376 + Block *b = worklist->rpop();
1.377 +
1.378 + // Copy first successor into my tmp_live space
1.379 + int s0num = b->_succs[0]->_pre_order;
1.380 + int *t = &live[s0num*max_reg_ints];
1.381 + for( int i=0; i<max_reg_ints; i++ )
1.382 + tmp_live[i] = t[i];
1.383 +
1.384 + // OR in the remaining live registers
1.385 + for( uint j=1; j<b->_num_succs; j++ ) {
1.386 + uint sjnum = b->_succs[j]->_pre_order;
1.387 + int *t = &live[sjnum*max_reg_ints];
1.388 + for( int i=0; i<max_reg_ints; i++ )
1.389 + tmp_live[i] |= t[i];
1.390 + }
1.391 +
1.392 + // Now walk tmp_live up the block backwards, computing live
1.393 + for( int k=b->_nodes.size()-1; k>=0; k-- ) {
1.394 + Node *n = b->_nodes[k];
1.395 + // KILL def'd bits
1.396 + int first = regalloc->get_reg_first(n);
1.397 + int second = regalloc->get_reg_second(n);
1.398 + if( OptoReg::is_valid(first) ) clr_live_bit(tmp_live,first);
1.399 + if( OptoReg::is_valid(second) ) clr_live_bit(tmp_live,second);
1.400 +
1.401 + MachNode *m = n->is_Mach() ? n->as_Mach() : NULL;
1.402 +
1.403 + // Check if m is potentially a CISC alternate instruction (i.e, possibly
1.404 + // synthesized by RegAlloc from a conventional instruction and a
1.405 + // spilled input)
1.406 + bool is_cisc_alternate = false;
1.407 + if (UseCISCSpill && m) {
1.408 + is_cisc_alternate = m->is_cisc_alternate();
1.409 + }
1.410 +
1.411 + // GEN use'd bits
1.412 + for( uint l=1; l<n->req(); l++ ) {
1.413 + Node *def = n->in(l);
1.414 + assert(def != 0, "input edge required");
1.415 + int first = regalloc->get_reg_first(def);
1.416 + int second = regalloc->get_reg_second(def);
1.417 + if( OptoReg::is_valid(first) ) set_live_bit(tmp_live,first);
1.418 + if( OptoReg::is_valid(second) ) set_live_bit(tmp_live,second);
1.419 + // If we use the stack pointer in a cisc-alternative instruction,
1.420 + // check for use as a memory operand. Then reconstruct the RegName
1.421 + // for this stack location, and set the appropriate bit in the
1.422 + // live vector 4987749.
1.423 + if (is_cisc_alternate && def == fp) {
1.424 + const TypePtr *adr_type = NULL;
1.425 + intptr_t offset;
1.426 + const Node* base = m->get_base_and_disp(offset, adr_type);
1.427 + if (base == NodeSentinel) {
1.428 + // Machnode has multiple memory inputs. We are unable to reason
1.429 + // with these, but are presuming (with trepidation) that not any of
1.430 + // them are oops. This can be fixed by making get_base_and_disp()
1.431 + // look at a specific input instead of all inputs.
1.432 + assert(!def->bottom_type()->isa_oop_ptr(), "expecting non-oop mem input");
1.433 + } else if (base != fp || offset == Type::OffsetBot) {
1.434 + // Do nothing: the fp operand is either not from a memory use
1.435 + // (base == NULL) OR the fp is used in a non-memory context
1.436 + // (base is some other register) OR the offset is not constant,
1.437 + // so it is not a stack slot.
1.438 + } else {
1.439 + assert(offset >= 0, "unexpected negative offset");
1.440 + offset -= (offset % jintSize); // count the whole word
1.441 + int stack_reg = regalloc->offset2reg(offset);
1.442 + if (OptoReg::is_stack(stack_reg)) {
1.443 + set_live_bit(tmp_live, stack_reg);
1.444 + } else {
1.445 + assert(false, "stack_reg not on stack?");
1.446 + }
1.447 + }
1.448 + }
1.449 + }
1.450 +
1.451 + if( n->jvms() ) { // Record liveness at safepoint
1.452 +
1.453 + // This placement of this stanza means inputs to calls are
1.454 + // considered live at the callsite's OopMap. Argument oops are
1.455 + // hence live, but NOT included in the oopmap. See cutout in
1.456 + // build_oop_map. Debug oops are live (and in OopMap).
1.457 + int *n_live = NEW_ARENA_ARRAY(A, int, max_reg_ints);
1.458 + for( int l=0; l<max_reg_ints; l++ )
1.459 + n_live[l] = tmp_live[l];
1.460 + safehash->Insert(n,n_live);
1.461 + }
1.462 +
1.463 + }
1.464 +
1.465 + // Now at block top, see if we have any changes. If so, propagate
1.466 + // to prior blocks.
1.467 + int *old_live = &live[b->_pre_order*max_reg_ints];
1.468 + int l;
1.469 + for( l=0; l<max_reg_ints; l++ )
1.470 + if( tmp_live[l] != old_live[l] )
1.471 + break;
1.472 + if( l<max_reg_ints ) { // Change!
1.473 + // Copy in new value
1.474 + for( l=0; l<max_reg_ints; l++ )
1.475 + old_live[l] = tmp_live[l];
1.476 + // Push preds onto worklist
1.477 + for( l=1; l<(int)b->num_preds(); l++ )
1.478 + worklist->push(cfg->_bbs[b->pred(l)->_idx]);
1.479 + }
1.480 + }
1.481 +
1.482 + // Scan for any missing safepoints. Happens to infinite loops
1.483 + // ala ZKM.jar
1.484 + uint i;
1.485 + for( i=1; i<cfg->_num_blocks; i++ ) {
1.486 + Block *b = cfg->_blocks[i];
1.487 + uint j;
1.488 + for( j=1; j<b->_nodes.size(); j++ )
1.489 + if( b->_nodes[j]->jvms() &&
1.490 + (*safehash)[b->_nodes[j]] == NULL )
1.491 + break;
1.492 + if( j<b->_nodes.size() ) break;
1.493 + }
1.494 + if( i == cfg->_num_blocks )
1.495 + break; // Got 'em all
1.496 +#ifndef PRODUCT
1.497 + if( PrintOpto && Verbose )
1.498 + tty->print_cr("retripping live calc");
1.499 +#endif
1.500 + // Force the issue (expensively): recheck everybody
1.501 + for( i=1; i<cfg->_num_blocks; i++ )
1.502 + worklist->push(cfg->_blocks[i]);
1.503 + }
1.504 +
1.505 +}
1.506 +
1.507 +//------------------------------BuildOopMaps-----------------------------------
1.508 +// Collect GC mask info - where are all the OOPs?
1.509 +void Compile::BuildOopMaps() {
1.510 + NOT_PRODUCT( TracePhase t3("bldOopMaps", &_t_buildOopMaps, TimeCompiler); )
1.511 + // Can't resource-mark because I need to leave all those OopMaps around,
1.512 + // or else I need to resource-mark some arena other than the default.
1.513 + // ResourceMark rm; // Reclaim all OopFlows when done
1.514 + int max_reg = _regalloc->_max_reg; // Current array extent
1.515 +
1.516 + Arena *A = Thread::current()->resource_area();
1.517 + Block_List worklist; // Worklist of pending blocks
1.518 +
1.519 + int max_reg_ints = round_to(max_reg, BitsPerInt)>>LogBitsPerInt;
1.520 + Dict *safehash = NULL; // Used for assert only
1.521 + // Compute a backwards liveness per register. Needs a bitarray of
1.522 + // #blocks x (#registers, rounded up to ints)
1.523 + safehash = new Dict(cmpkey,hashkey,A);
1.524 + do_liveness( _regalloc, _cfg, &worklist, max_reg_ints, A, safehash );
1.525 + OopFlow *free_list = NULL; // Free, unused
1.526 +
1.527 + // Array mapping blocks to completed oopflows
1.528 + OopFlow **flows = NEW_ARENA_ARRAY(A, OopFlow*, _cfg->_num_blocks);
1.529 + memset( flows, 0, _cfg->_num_blocks*sizeof(OopFlow*) );
1.530 +
1.531 +
1.532 + // Do the first block 'by hand' to prime the worklist
1.533 + Block *entry = _cfg->_blocks[1];
1.534 + OopFlow *rootflow = OopFlow::make(A,max_reg);
1.535 + // Initialize to 'bottom' (not 'top')
1.536 + memset( rootflow->_callees, OptoReg::Bad, max_reg*sizeof(short) );
1.537 + memset( rootflow->_defs , 0, max_reg*sizeof(Node*) );
1.538 + flows[entry->_pre_order] = rootflow;
1.539 +
1.540 + // Do the first block 'by hand' to prime the worklist
1.541 + rootflow->_b = entry;
1.542 + rootflow->compute_reach( _regalloc, max_reg, safehash );
1.543 + for( uint i=0; i<entry->_num_succs; i++ )
1.544 + worklist.push(entry->_succs[i]);
1.545 +
1.546 + // Now worklist contains blocks which have some, but perhaps not all,
1.547 + // predecessors visited.
1.548 + while( worklist.size() ) {
1.549 + // Scan for a block with all predecessors visited, or any randoms slob
1.550 + // otherwise. All-preds-visited order allows me to recycle OopFlow
1.551 + // structures rapidly and cut down on the memory footprint.
1.552 + // Note: not all predecessors might be visited yet (must happen for
1.553 + // irreducible loops). This is OK, since every live value must have the
1.554 + // SAME reaching def for the block, so any reaching def is OK.
1.555 + uint i;
1.556 +
1.557 + Block *b = worklist.pop();
1.558 + // Ignore root block
1.559 + if( b == _cfg->_broot ) continue;
1.560 + // Block is already done? Happens if block has several predecessors,
1.561 + // he can get on the worklist more than once.
1.562 + if( flows[b->_pre_order] ) continue;
1.563 +
1.564 + // If this block has a visited predecessor AND that predecessor has this
1.565 + // last block as his only undone child, we can move the OopFlow from the
1.566 + // pred to this block. Otherwise we have to grab a new OopFlow.
1.567 + OopFlow *flow = NULL; // Flag for finding optimized flow
1.568 + Block *pred = (Block*)0xdeadbeef;
1.569 + uint j;
1.570 + // Scan this block's preds to find a done predecessor
1.571 + for( j=1; j<b->num_preds(); j++ ) {
1.572 + Block *p = _cfg->_bbs[b->pred(j)->_idx];
1.573 + OopFlow *p_flow = flows[p->_pre_order];
1.574 + if( p_flow ) { // Predecessor is done
1.575 + assert( p_flow->_b == p, "cross check" );
1.576 + pred = p; // Record some predecessor
1.577 + // If all successors of p are done except for 'b', then we can carry
1.578 + // p_flow forward to 'b' without copying, otherwise we have to draw
1.579 + // from the free_list and clone data.
1.580 + uint k;
1.581 + for( k=0; k<p->_num_succs; k++ )
1.582 + if( !flows[p->_succs[k]->_pre_order] &&
1.583 + p->_succs[k] != b )
1.584 + break;
1.585 +
1.586 + // Either carry-forward the now-unused OopFlow for b's use
1.587 + // or draw a new one from the free list
1.588 + if( k==p->_num_succs ) {
1.589 + flow = p_flow;
1.590 + break; // Found an ideal pred, use him
1.591 + }
1.592 + }
1.593 + }
1.594 +
1.595 + if( flow ) {
1.596 + // We have an OopFlow that's the last-use of a predecessor.
1.597 + // Carry it forward.
1.598 + } else { // Draw a new OopFlow from the freelist
1.599 + if( !free_list )
1.600 + free_list = OopFlow::make(A,max_reg);
1.601 + flow = free_list;
1.602 + assert( flow->_b == NULL, "oopFlow is not free" );
1.603 + free_list = flow->_next;
1.604 + flow->_next = NULL;
1.605 +
1.606 + // Copy/clone over the data
1.607 + flow->clone(flows[pred->_pre_order], max_reg);
1.608 + }
1.609 +
1.610 + // Mark flow for block. Blocks can only be flowed over once,
1.611 + // because after the first time they are guarded from entering
1.612 + // this code again.
1.613 + assert( flow->_b == pred, "have some prior flow" );
1.614 + flow->_b = NULL;
1.615 +
1.616 + // Now push flow forward
1.617 + flows[b->_pre_order] = flow;// Mark flow for this block
1.618 + flow->_b = b;
1.619 + flow->compute_reach( _regalloc, max_reg, safehash );
1.620 +
1.621 + // Now push children onto worklist
1.622 + for( i=0; i<b->_num_succs; i++ )
1.623 + worklist.push(b->_succs[i]);
1.624 +
1.625 + }
1.626 +}
