RegAllocPBQP.cpp revision 0b8c9a80f20772c3793201ab5b251d3520b9cea3 
1//===------ RegAllocPBQP.cpp ---- PBQP Register Allocator -------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file contains a Partitioned Boolean Quadratic Programming (PBQP) based
11// register allocator for LLVM. This allocator works by constructing a PBQP
12// problem representing the register allocation problem under consideration,
13// solving this using a PBQP solver, and mapping the solution back to a
14// register assignment. If any variables are selected for spilling then spill
15// code is inserted and the process repeated.
16//
17// The PBQP solver (pbqp.c) provided for this allocator uses a heuristic tuned
18// for register allocation. For more information on PBQP for register
19// allocation, see the following papers:
20//
21//   (1) Hames, L. and Scholz, B. 2006. Nearly optimal register allocation with
22//   PBQP. In Proceedings of the 7th Joint Modular Languages Conference
23//   (JMLC'06). LNCS, vol. 4228. Springer, New York, NY, USA. 346-361.
24//
25//   (2) Scholz, B., Eckstein, E. 2002. Register allocation for irregular
26//   architectures. In Proceedings of the Joint Conference on Languages,
27//   Compilers and Tools for Embedded Systems (LCTES'02), ACM Press, New York,
28//   NY, USA, 139-148.
29//
30//===----------------------------------------------------------------------===//
31
32#define DEBUG_TYPE "regalloc"
33
34#include "llvm/CodeGen/RegAllocPBQP.h"
35#include "RegisterCoalescer.h"
36#include "Spiller.h"
37#include "llvm/Analysis/AliasAnalysis.h"
38#include "llvm/CodeGen/CalcSpillWeights.h"
39#include "llvm/CodeGen/LiveIntervalAnalysis.h"
40#include "llvm/CodeGen/LiveRangeEdit.h"
41#include "llvm/CodeGen/LiveStackAnalysis.h"
42#include "llvm/CodeGen/MachineDominators.h"
43#include "llvm/CodeGen/MachineFunctionPass.h"
44#include "llvm/CodeGen/MachineLoopInfo.h"
45#include "llvm/CodeGen/MachineRegisterInfo.h"
46#include "llvm/CodeGen/PBQP/Graph.h"
47#include "llvm/CodeGen/PBQP/HeuristicSolver.h"
48#include "llvm/CodeGen/PBQP/Heuristics/Briggs.h"
49#include "llvm/CodeGen/RegAllocRegistry.h"
50#include "llvm/CodeGen/VirtRegMap.h"
51#include "llvm/IR/Module.h"
52#include "llvm/Support/Debug.h"
53#include "llvm/Support/raw_ostream.h"
54#include "llvm/Target/TargetInstrInfo.h"
55#include "llvm/Target/TargetMachine.h"
56#include <limits>
57#include <memory>
58#include <set>
59#include <sstream>
60#include <vector>
61
62using namespace llvm;
63
64static RegisterRegAlloc
65registerPBQPRepAlloc("pbqp", "PBQP register allocator",
66                       createDefaultPBQPRegisterAllocator);
67
68static cl::opt<bool>
69pbqpCoalescing("pbqp-coalescing",
70                cl::desc("Attempt coalescing during PBQP register allocation."),
71                cl::init(false), cl::Hidden);
72
73#ifndef NDEBUG
74static cl::opt<bool>
75pbqpDumpGraphs("pbqp-dump-graphs",
76               cl::desc("Dump graphs for each function/round in the compilation unit."),
77               cl::init(false), cl::Hidden);
78#endif
79
80namespace {
81
82///
83/// PBQP based allocators solve the register allocation problem by mapping
84/// register allocation problems to Partitioned Boolean Quadratic
85/// Programming problems.
86class RegAllocPBQP : public MachineFunctionPass {
87public:
88
89  static char ID;
90
91  /// Construct a PBQP register allocator.
92  RegAllocPBQP(std::auto_ptr<PBQPBuilder> b, char *cPassID=0)
93      : MachineFunctionPass(ID), builder(b), customPassID(cPassID) {
94    initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
95    initializeLiveIntervalsPass(*PassRegistry::getPassRegistry());
96    initializeCalculateSpillWeightsPass(*PassRegistry::getPassRegistry());
97    initializeLiveStacksPass(*PassRegistry::getPassRegistry());
98    initializeMachineLoopInfoPass(*PassRegistry::getPassRegistry());
99    initializeVirtRegMapPass(*PassRegistry::getPassRegistry());
100  }
101
102  /// Return the pass name.
103  virtual const char* getPassName() const {
104    return "PBQP Register Allocator";
105  }
106
107  /// PBQP analysis usage.
108  virtual void getAnalysisUsage(AnalysisUsage &au) const;
109
110  /// Perform register allocation
111  virtual bool runOnMachineFunction(MachineFunction &MF);
112
113private:
114
115  typedef std::map<const LiveInterval*, unsigned> LI2NodeMap;
116  typedef std::vector<const LiveInterval*> Node2LIMap;
117  typedef std::vector<unsigned> AllowedSet;
118  typedef std::vector<AllowedSet> AllowedSetMap;
119  typedef std::pair<unsigned, unsigned> RegPair;
120  typedef std::map<RegPair, PBQP::PBQPNum> CoalesceMap;
121  typedef std::set<unsigned> RegSet;
122
123
124  std::auto_ptr<PBQPBuilder> builder;
125
126  char *customPassID;
127
128  MachineFunction *mf;
129  const TargetMachine *tm;
130  const TargetRegisterInfo *tri;
131  const TargetInstrInfo *tii;
132  const MachineLoopInfo *loopInfo;
133  MachineRegisterInfo *mri;
134
135  std::auto_ptr<Spiller> spiller;
136  LiveIntervals *lis;
137  LiveStacks *lss;
138  VirtRegMap *vrm;
139
140  RegSet vregsToAlloc, emptyIntervalVRegs;
141
142  /// \brief Finds the initial set of vreg intervals to allocate.
143  void findVRegIntervalsToAlloc();
144
145  /// \brief Given a solved PBQP problem maps this solution back to a register
146  /// assignment.
147  bool mapPBQPToRegAlloc(const PBQPRAProblem &problem,
148                         const PBQP::Solution &solution);
149
150  /// \brief Postprocessing before final spilling. Sets basic block "live in"
151  /// variables.
152  void finalizeAlloc() const;
153
154};
155
156char RegAllocPBQP::ID = 0;
157
158} // End anonymous namespace.
159
160unsigned PBQPRAProblem::getVRegForNode(PBQP::Graph::ConstNodeItr node) const {
161  Node2VReg::const_iterator vregItr = node2VReg.find(node);
162  assert(vregItr != node2VReg.end() && "No vreg for node.");
163  return vregItr->second;
164}
165
166PBQP::Graph::NodeItr PBQPRAProblem::getNodeForVReg(unsigned vreg) const {
167  VReg2Node::const_iterator nodeItr = vreg2Node.find(vreg);
168  assert(nodeItr != vreg2Node.end() && "No node for vreg.");
169  return nodeItr->second;
170
171}
172
173const PBQPRAProblem::AllowedSet&
174  PBQPRAProblem::getAllowedSet(unsigned vreg) const {
175  AllowedSetMap::const_iterator allowedSetItr = allowedSets.find(vreg);
176  assert(allowedSetItr != allowedSets.end() && "No pregs for vreg.");
177  const AllowedSet &allowedSet = allowedSetItr->second;
178  return allowedSet;
179}
180
181unsigned PBQPRAProblem::getPRegForOption(unsigned vreg, unsigned option) const {
182  assert(isPRegOption(vreg, option) && "Not a preg option.");
183
184  const AllowedSet& allowedSet = getAllowedSet(vreg);
185  assert(option <= allowedSet.size() && "Option outside allowed set.");
186  return allowedSet[option - 1];
187}
188
189std::auto_ptr<PBQPRAProblem> PBQPBuilder::build(MachineFunction *mf,
190                                                const LiveIntervals *lis,
191                                                const MachineLoopInfo *loopInfo,
192                                                const RegSet &vregs) {
193
194  LiveIntervals *LIS = const_cast<LiveIntervals*>(lis);
195  MachineRegisterInfo *mri = &mf->getRegInfo();
196  const TargetRegisterInfo *tri = mf->getTarget().getRegisterInfo();
197
198  std::auto_ptr<PBQPRAProblem> p(new PBQPRAProblem());
199  PBQP::Graph &g = p->getGraph();
200  RegSet pregs;
201
202  // Collect the set of preg intervals, record that they're used in the MF.
203  for (unsigned Reg = 1, e = tri->getNumRegs(); Reg != e; ++Reg) {
204    if (mri->def_empty(Reg))
205      continue;
206    pregs.insert(Reg);
207    mri->setPhysRegUsed(Reg);
208  }
209
210  // Iterate over vregs.
211  for (RegSet::const_iterator vregItr = vregs.begin(), vregEnd = vregs.end();
212       vregItr != vregEnd; ++vregItr) {
213    unsigned vreg = *vregItr;
214    const TargetRegisterClass *trc = mri->getRegClass(vreg);
215    LiveInterval *vregLI = &LIS->getInterval(vreg);
216
217    // Record any overlaps with regmask operands.
218    BitVector regMaskOverlaps;
219    LIS->checkRegMaskInterference(*vregLI, regMaskOverlaps);
220
221    // Compute an initial allowed set for the current vreg.
222    typedef std::vector<unsigned> VRAllowed;
223    VRAllowed vrAllowed;
224    ArrayRef<uint16_t> rawOrder = trc->getRawAllocationOrder(*mf);
225    for (unsigned i = 0; i != rawOrder.size(); ++i) {
226      unsigned preg = rawOrder[i];
227      if (mri->isReserved(preg))
228        continue;
229
230      // vregLI crosses a regmask operand that clobbers preg.
231      if (!regMaskOverlaps.empty() && !regMaskOverlaps.test(preg))
232        continue;
233
234      // vregLI overlaps fixed regunit interference.
235      bool Interference = false;
236      for (MCRegUnitIterator Units(preg, tri); Units.isValid(); ++Units) {
237        if (vregLI->overlaps(LIS->getRegUnit(*Units))) {
238          Interference = true;
239          break;
240        }
241      }
242      if (Interference)
243        continue;
244
245      // preg is usable for this virtual register.
246      vrAllowed.push_back(preg);
247    }
248
249    // Construct the node.
250    PBQP::Graph::NodeItr node =
251      g.addNode(PBQP::Vector(vrAllowed.size() + 1, 0));
252
253    // Record the mapping and allowed set in the problem.
254    p->recordVReg(vreg, node, vrAllowed.begin(), vrAllowed.end());
255
256    PBQP::PBQPNum spillCost = (vregLI->weight != 0.0) ?
257        vregLI->weight : std::numeric_limits<PBQP::PBQPNum>::min();
258
259    addSpillCosts(g.getNodeCosts(node), spillCost);
260  }
261
262  for (RegSet::const_iterator vr1Itr = vregs.begin(), vrEnd = vregs.end();
263         vr1Itr != vrEnd; ++vr1Itr) {
264    unsigned vr1 = *vr1Itr;
265    const LiveInterval &l1 = lis->getInterval(vr1);
266    const PBQPRAProblem::AllowedSet &vr1Allowed = p->getAllowedSet(vr1);
267
268    for (RegSet::const_iterator vr2Itr = llvm::next(vr1Itr);
269         vr2Itr != vrEnd; ++vr2Itr) {
270      unsigned vr2 = *vr2Itr;
271      const LiveInterval &l2 = lis->getInterval(vr2);
272      const PBQPRAProblem::AllowedSet &vr2Allowed = p->getAllowedSet(vr2);
273
274      assert(!l2.empty() && "Empty interval in vreg set?");
275      if (l1.overlaps(l2)) {
276        PBQP::Graph::EdgeItr edge =
277          g.addEdge(p->getNodeForVReg(vr1), p->getNodeForVReg(vr2),
278                    PBQP::Matrix(vr1Allowed.size()+1, vr2Allowed.size()+1, 0));
279
280        addInterferenceCosts(g.getEdgeCosts(edge), vr1Allowed, vr2Allowed, tri);
281      }
282    }
283  }
284
285  return p;
286}
287
288void PBQPBuilder::addSpillCosts(PBQP::Vector &costVec,
289                                PBQP::PBQPNum spillCost) {
290  costVec[0] = spillCost;
291}
292
293void PBQPBuilder::addInterferenceCosts(
294                                    PBQP::Matrix &costMat,
295                                    const PBQPRAProblem::AllowedSet &vr1Allowed,
296                                    const PBQPRAProblem::AllowedSet &vr2Allowed,
297                                    const TargetRegisterInfo *tri) {
298  assert(costMat.getRows() == vr1Allowed.size() + 1 && "Matrix height mismatch.");
299  assert(costMat.getCols() == vr2Allowed.size() + 1 && "Matrix width mismatch.");
300
301  for (unsigned i = 0; i != vr1Allowed.size(); ++i) {
302    unsigned preg1 = vr1Allowed[i];
303
304    for (unsigned j = 0; j != vr2Allowed.size(); ++j) {
305      unsigned preg2 = vr2Allowed[j];
306
307      if (tri->regsOverlap(preg1, preg2)) {
308        costMat[i + 1][j + 1] = std::numeric_limits<PBQP::PBQPNum>::infinity();
309      }
310    }
311  }
312}
313
314std::auto_ptr<PBQPRAProblem> PBQPBuilderWithCoalescing::build(
315                                                MachineFunction *mf,
316                                                const LiveIntervals *lis,
317                                                const MachineLoopInfo *loopInfo,
318                                                const RegSet &vregs) {
319
320  std::auto_ptr<PBQPRAProblem> p = PBQPBuilder::build(mf, lis, loopInfo, vregs);
321  PBQP::Graph &g = p->getGraph();
322
323  const TargetMachine &tm = mf->getTarget();
324  CoalescerPair cp(*tm.getRegisterInfo());
325
326  // Scan the machine function and add a coalescing cost whenever CoalescerPair
327  // gives the Ok.
328  for (MachineFunction::const_iterator mbbItr = mf->begin(),
329                                       mbbEnd = mf->end();
330       mbbItr != mbbEnd; ++mbbItr) {
331    const MachineBasicBlock *mbb = &*mbbItr;
332
333    for (MachineBasicBlock::const_iterator miItr = mbb->begin(),
334                                           miEnd = mbb->end();
335         miItr != miEnd; ++miItr) {
336      const MachineInstr *mi = &*miItr;
337
338      if (!cp.setRegisters(mi)) {
339        continue; // Not coalescable.
340      }
341
342      if (cp.getSrcReg() == cp.getDstReg()) {
343        continue; // Already coalesced.
344      }
345
346      unsigned dst = cp.getDstReg(),
347               src = cp.getSrcReg();
348
349      const float copyFactor = 0.5; // Cost of copy relative to load. Current
350      // value plucked randomly out of the air.
351
352      PBQP::PBQPNum cBenefit =
353        copyFactor * LiveIntervals::getSpillWeight(false, true,
354                                                   loopInfo->getLoopDepth(mbb));
355
356      if (cp.isPhys()) {
357        if (!mf->getRegInfo().isAllocatable(dst)) {
358          continue;
359        }
360
361        const PBQPRAProblem::AllowedSet &allowed = p->getAllowedSet(src);
362        unsigned pregOpt = 0;
363        while (pregOpt < allowed.size() && allowed[pregOpt] != dst) {
364          ++pregOpt;
365        }
366        if (pregOpt < allowed.size()) {
367          ++pregOpt; // +1 to account for spill option.
368          PBQP::Graph::NodeItr node = p->getNodeForVReg(src);
369          addPhysRegCoalesce(g.getNodeCosts(node), pregOpt, cBenefit);
370        }
371      } else {
372        const PBQPRAProblem::AllowedSet *allowed1 = &p->getAllowedSet(dst);
373        const PBQPRAProblem::AllowedSet *allowed2 = &p->getAllowedSet(src);
374        PBQP::Graph::NodeItr node1 = p->getNodeForVReg(dst);
375        PBQP::Graph::NodeItr node2 = p->getNodeForVReg(src);
376        PBQP::Graph::EdgeItr edge = g.findEdge(node1, node2);
377        if (edge == g.edgesEnd()) {
378          edge = g.addEdge(node1, node2, PBQP::Matrix(allowed1->size() + 1,
379                                                      allowed2->size() + 1,
380                                                      0));
381        } else {
382          if (g.getEdgeNode1(edge) == node2) {
383            std::swap(node1, node2);
384            std::swap(allowed1, allowed2);
385          }
386        }
387
388        addVirtRegCoalesce(g.getEdgeCosts(edge), *allowed1, *allowed2,
389                           cBenefit);
390      }
391    }
392  }
393
394  return p;
395}
396
397void PBQPBuilderWithCoalescing::addPhysRegCoalesce(PBQP::Vector &costVec,
398                                                   unsigned pregOption,
399                                                   PBQP::PBQPNum benefit) {
400  costVec[pregOption] += -benefit;
401}
402
403void PBQPBuilderWithCoalescing::addVirtRegCoalesce(
404                                    PBQP::Matrix &costMat,
405                                    const PBQPRAProblem::AllowedSet &vr1Allowed,
406                                    const PBQPRAProblem::AllowedSet &vr2Allowed,
407                                    PBQP::PBQPNum benefit) {
408
409  assert(costMat.getRows() == vr1Allowed.size() + 1 && "Size mismatch.");
410  assert(costMat.getCols() == vr2Allowed.size() + 1 && "Size mismatch.");
411
412  for (unsigned i = 0; i != vr1Allowed.size(); ++i) {
413    unsigned preg1 = vr1Allowed[i];
414    for (unsigned j = 0; j != vr2Allowed.size(); ++j) {
415      unsigned preg2 = vr2Allowed[j];
416
417      if (preg1 == preg2) {
418        costMat[i + 1][j + 1] += -benefit;
419      }
420    }
421  }
422}
423
424
425void RegAllocPBQP::getAnalysisUsage(AnalysisUsage &au) const {
426  au.setPreservesCFG();
427  au.addRequired<AliasAnalysis>();
428  au.addPreserved<AliasAnalysis>();
429  au.addRequired<SlotIndexes>();
430  au.addPreserved<SlotIndexes>();
431  au.addRequired<LiveIntervals>();
432  au.addPreserved<LiveIntervals>();
433  //au.addRequiredID(SplitCriticalEdgesID);
434  if (customPassID)
435    au.addRequiredID(*customPassID);
436  au.addRequired<CalculateSpillWeights>();
437  au.addRequired<LiveStacks>();
438  au.addPreserved<LiveStacks>();
439  au.addRequired<MachineDominatorTree>();
440  au.addPreserved<MachineDominatorTree>();
441  au.addRequired<MachineLoopInfo>();
442  au.addPreserved<MachineLoopInfo>();
443  au.addRequired<VirtRegMap>();
444  au.addPreserved<VirtRegMap>();
445  MachineFunctionPass::getAnalysisUsage(au);
446}
447
448void RegAllocPBQP::findVRegIntervalsToAlloc() {
449
450  // Iterate over all live ranges.
451  for (unsigned i = 0, e = mri->getNumVirtRegs(); i != e; ++i) {
452    unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
453    if (mri->reg_nodbg_empty(Reg))
454      continue;
455    LiveInterval *li = &lis->getInterval(Reg);
456
457    // If this live interval is non-empty we will use pbqp to allocate it.
458    // Empty intervals we allocate in a simple post-processing stage in
459    // finalizeAlloc.
460    if (!li->empty()) {
461      vregsToAlloc.insert(li->reg);
462    } else {
463      emptyIntervalVRegs.insert(li->reg);
464    }
465  }
466}
467
468bool RegAllocPBQP::mapPBQPToRegAlloc(const PBQPRAProblem &problem,
469                                     const PBQP::Solution &solution) {
470  // Set to true if we have any spills
471  bool anotherRoundNeeded = false;
472
473  // Clear the existing allocation.
474  vrm->clearAllVirt();
475
476  const PBQP::Graph &g = problem.getGraph();
477  // Iterate over the nodes mapping the PBQP solution to a register
478  // assignment.
479  for (PBQP::Graph::ConstNodeItr node = g.nodesBegin(),
480                                 nodeEnd = g.nodesEnd();
481       node != nodeEnd; ++node) {
482    unsigned vreg = problem.getVRegForNode(node);
483    unsigned alloc = solution.getSelection(node);
484
485    if (problem.isPRegOption(vreg, alloc)) {
486      unsigned preg = problem.getPRegForOption(vreg, alloc);
487      DEBUG(dbgs() << "VREG " << PrintReg(vreg, tri) << " -> "
488            << tri->getName(preg) << "\n");
489      assert(preg != 0 && "Invalid preg selected.");
490      vrm->assignVirt2Phys(vreg, preg);
491    } else if (problem.isSpillOption(vreg, alloc)) {
492      vregsToAlloc.erase(vreg);
493      SmallVector<LiveInterval*, 8> newSpills;
494      LiveRangeEdit LRE(&lis->getInterval(vreg), newSpills, *mf, *lis, vrm);
495      spiller->spill(LRE);
496
497      DEBUG(dbgs() << "VREG " << PrintReg(vreg, tri) << " -> SPILLED (Cost: "
498                   << LRE.getParent().weight << ", New vregs: ");
499
500      // Copy any newly inserted live intervals into the list of regs to
501      // allocate.
502      for (LiveRangeEdit::iterator itr = LRE.begin(), end = LRE.end();
503           itr != end; ++itr) {
504        assert(!(*itr)->empty() && "Empty spill range.");
505        DEBUG(dbgs() << PrintReg((*itr)->reg, tri) << " ");
506        vregsToAlloc.insert((*itr)->reg);
507      }
508
509      DEBUG(dbgs() << ")\n");
510
511      // We need another round if spill intervals were added.
512      anotherRoundNeeded |= !LRE.empty();
513    } else {
514      llvm_unreachable("Unknown allocation option.");
515    }
516  }
517
518  return !anotherRoundNeeded;
519}
520
521
522void RegAllocPBQP::finalizeAlloc() const {
523  // First allocate registers for the empty intervals.
524  for (RegSet::const_iterator
525         itr = emptyIntervalVRegs.begin(), end = emptyIntervalVRegs.end();
526         itr != end; ++itr) {
527    LiveInterval *li = &lis->getInterval(*itr);
528
529    unsigned physReg = mri->getSimpleHint(li->reg);
530
531    if (physReg == 0) {
532      const TargetRegisterClass *liRC = mri->getRegClass(li->reg);
533      physReg = liRC->getRawAllocationOrder(*mf).front();
534    }
535
536    vrm->assignVirt2Phys(li->reg, physReg);
537  }
538}
539
540bool RegAllocPBQP::runOnMachineFunction(MachineFunction &MF) {
541
542  mf = &MF;
543  tm = &mf->getTarget();
544  tri = tm->getRegisterInfo();
545  tii = tm->getInstrInfo();
546  mri = &mf->getRegInfo();
547
548  lis = &getAnalysis<LiveIntervals>();
549  lss = &getAnalysis<LiveStacks>();
550  loopInfo = &getAnalysis<MachineLoopInfo>();
551
552  vrm = &getAnalysis<VirtRegMap>();
553  spiller.reset(createInlineSpiller(*this, MF, *vrm));
554
555  mri->freezeReservedRegs(MF);
556
557  DEBUG(dbgs() << "PBQP Register Allocating for " << mf->getName() << "\n");
558
559  // Allocator main loop:
560  //
561  // * Map current regalloc problem to a PBQP problem
562  // * Solve the PBQP problem
563  // * Map the solution back to a register allocation
564  // * Spill if necessary
565  //
566  // This process is continued till no more spills are generated.
567
568  // Find the vreg intervals in need of allocation.
569  findVRegIntervalsToAlloc();
570
571#ifndef NDEBUG
572  const Function* func = mf->getFunction();
573  std::string fqn =
574    func->getParent()->getModuleIdentifier() + "." +
575    func->getName().str();
576#endif
577
578  // If there are non-empty intervals allocate them using pbqp.
579  if (!vregsToAlloc.empty()) {
580
581    bool pbqpAllocComplete = false;
582    unsigned round = 0;
583
584    while (!pbqpAllocComplete) {
585      DEBUG(dbgs() << "  PBQP Regalloc round " << round << ":\n");
586
587      std::auto_ptr<PBQPRAProblem> problem =
588        builder->build(mf, lis, loopInfo, vregsToAlloc);
589
590#ifndef NDEBUG
591      if (pbqpDumpGraphs) {
592        std::ostringstream rs;
593        rs << round;
594        std::string graphFileName(fqn + "." + rs.str() + ".pbqpgraph");
595        std::string tmp;
596        raw_fd_ostream os(graphFileName.c_str(), tmp);
597        DEBUG(dbgs() << "Dumping graph for round " << round << " to \""
598              << graphFileName << "\"\n");
599        problem->getGraph().dump(os);
600      }
601#endif
602
603      PBQP::Solution solution =
604        PBQP::HeuristicSolver<PBQP::Heuristics::Briggs>::solve(
605          problem->getGraph());
606
607      pbqpAllocComplete = mapPBQPToRegAlloc(*problem, solution);
608
609      ++round;
610    }
611  }
612
613  // Finalise allocation, allocate empty ranges.
614  finalizeAlloc();
615  vregsToAlloc.clear();
616  emptyIntervalVRegs.clear();
617
618  DEBUG(dbgs() << "Post alloc VirtRegMap:\n" << *vrm << "\n");
619
620  return true;
621}
622
623FunctionPass* llvm::createPBQPRegisterAllocator(
624                                           std::auto_ptr<PBQPBuilder> builder,
625                                           char *customPassID) {
626  return new RegAllocPBQP(builder, customPassID);
627}
628
629FunctionPass* llvm::createDefaultPBQPRegisterAllocator() {
630  if (pbqpCoalescing) {
631    return createPBQPRegisterAllocator(
632             std::auto_ptr<PBQPBuilder>(new PBQPBuilderWithCoalescing()));
633  } // else
634  return createPBQPRegisterAllocator(
635           std::auto_ptr<PBQPBuilder>(new PBQPBuilder()));
636}
637
638#undef DEBUG_TYPE
639