Removed the older style (in-allocator) problem construction system from the PBQP allocator. Problem construction is now done exclusively with the new builders.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115502 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 628 deletions

diff --git a/lib/CodeGen/RegAllocPBQP.cpp b/lib/CodeGen/RegAllocPBQP.cpp
index a45ead8..6907321 100644
--- a/lib/CodeGen/RegAllocPBQP.cpp
+++ b/lib/CodeGen/RegAllocPBQP.cpp
@@ -68,12 +68,6 @@ pbqpCoalescing("pbqp-coalescing",
                 cl::init(false), cl::Hidden);
 
 static cl::opt<bool>
-pbqpBuilder("pbqp-builder",
-             cl::desc("Use new builder system."),
-             cl::init(true), cl::Hidden);
-
-
-static cl::opt<bool>
 pbqpPreSplitting("pbqp-pre-splitting",
                  cl::desc("Pre-split before PBQP register allocation."),
                  cl::init(false), cl::Hidden);
@@ -129,76 +123,17 @@ private:
   LiveStacks *lss;
   VirtRegMap *vrm;
 
-  LI2NodeMap li2Node;
-  Node2LIMap node2LI;
-  AllowedSetMap allowedSets;
   RegSet vregsToAlloc, emptyIntervalVRegs;
-  NodeVector problemNodes;
-
-
-  /// Builds a PBQP cost vector.
-  template <typename RegContainer>
-  PBQP::Vector buildCostVector(unsigned vReg,
-                               const RegContainer &allowed,
-                               const CoalesceMap &cealesces,
-                               PBQP::PBQPNum spillCost) const;
-
-  /// \brief Builds a PBQP interference matrix.
-  ///
-  /// @return Either a pointer to a non-zero PBQP matrix representing the
-  ///         allocation option costs, or a null pointer for a zero matrix.
-  ///
-  /// Expects allowed sets for two interfering LiveIntervals. These allowed
-  /// sets should contain only allocable registers from the LiveInterval's
-  /// register class, with any interfering pre-colored registers removed.
-  template <typename RegContainer>
-  PBQP::Matrix* buildInterferenceMatrix(const RegContainer &allowed1,
-                                        const RegContainer &allowed2) const;
-
-  ///
-  /// Expects allowed sets for two potentially coalescable LiveIntervals,
-  /// and an estimated benefit due to coalescing. The allowed sets should
-  /// contain only allocable registers from the LiveInterval's register
-  /// classes, with any interfering pre-colored registers removed.
-  template <typename RegContainer>
-  PBQP::Matrix* buildCoalescingMatrix(const RegContainer &allowed1,
-                                      const RegContainer &allowed2,
-                                      PBQP::PBQPNum cBenefit) const;
-
-  /// \brief Finds coalescing opportunities and returns them as a map.
-  ///
-  /// Any entries in the map are guaranteed coalescable, even if their
-  /// corresponding live intervals overlap.
-  CoalesceMap findCoalesces();
 
   /// \brief Finds the initial set of vreg intervals to allocate.
   void findVRegIntervalsToAlloc();
 
-  /// \brief Constructs a PBQP problem representation of the register
-  /// allocation problem for this function.
-  ///
-  /// Old Construction Process - this functionality has been subsumed
-  /// by PBQPBuilder. This function will only be hanging around for a little
-  /// while until the new system has been fully tested.
-  /// 
-  /// @return a PBQP solver object for the register allocation problem.
-  PBQP::Graph constructPBQPProblemOld();
-
   /// \brief Adds a stack interval if the given live interval has been
   /// spilled. Used to support stack slot coloring.
   void addStackInterval(const LiveInterval *spilled,MachineRegisterInfo* mri);
 
   /// \brief Given a solved PBQP problem maps this solution back to a register
   /// assignment.
-  ///
-  /// Old Construction Process - this functionality has been subsumed
-  /// by PBQPBuilder. This function will only be hanging around for a little
-  /// while until the new system has been fully tested.
-  /// 
-  bool mapPBQPToRegAllocOld(const PBQP::Solution &solution);
-
-  /// \brief Given a solved PBQP problem maps this solution back to a register
-  /// assignment.
   bool mapPBQPToRegAlloc(const PBQPRAProblem &problem,
                          const PBQP::Solution &solution);
 
@@ -510,306 +445,6 @@ void RegAllocPBQP::getAnalysisUsage(AnalysisUsage &au) const {
   MachineFunctionPass::getAnalysisUsage(au);
 }
 
-template <typename RegContainer>
-PBQP::Vector RegAllocPBQP::buildCostVector(unsigned vReg,
-                                           const RegContainer &allowed,
-                                           const CoalesceMap &coalesces,
-                                           PBQP::PBQPNum spillCost) const {
-
-  typedef typename RegContainer::const_iterator AllowedItr;
-
-  // Allocate vector. Additional element (0th) used for spill option
-  PBQP::Vector v(allowed.size() + 1, 0);
-
-  v[0] = spillCost;
-
-  // Iterate over the allowed registers inserting coalesce benefits if there
-  // are any.
-  unsigned ai = 0;
-  for (AllowedItr itr = allowed.begin(), end = allowed.end();
-       itr != end; ++itr, ++ai) {
-
-    unsigned pReg = *itr;
-
-    CoalesceMap::const_iterator cmItr =
-      coalesces.find(RegPair(vReg, pReg));
-
-    // No coalesce - on to the next preg.
-    if (cmItr == coalesces.end())
-      continue;
-
-    // We have a coalesce - insert the benefit.
-    v[ai + 1] = -cmItr->second;
-  }
-
-  return v;
-}
-
-template <typename RegContainer>
-PBQP::Matrix* RegAllocPBQP::buildInterferenceMatrix(
-      const RegContainer &allowed1, const RegContainer &allowed2) const {
-
-  typedef typename RegContainer::const_iterator RegContainerIterator;
-
-  // Construct a PBQP matrix representing the cost of allocation options. The
-  // rows and columns correspond to the allocation options for the two live
-  // intervals.  Elements will be infinite where corresponding registers alias,
-  // since we cannot allocate aliasing registers to interfering live intervals.
-  // All other elements (non-aliasing combinations) will have zero cost. Note
-  // that the spill option (element 0,0) has zero cost, since we can allocate
-  // both intervals to memory safely (the cost for each individual allocation
-  // to memory is accounted for by the cost vectors for each live interval).
-  PBQP::Matrix *m =
-    new PBQP::Matrix(allowed1.size() + 1, allowed2.size() + 1, 0);
-
-  // Assume this is a zero matrix until proven otherwise.  Zero matrices occur
-  // between interfering live ranges with non-overlapping register sets (e.g.
-  // non-overlapping reg classes, or disjoint sets of allowed regs within the
-  // same class). The term "overlapping" is used advisedly: sets which do not
-  // intersect, but contain registers which alias, will have non-zero matrices.
-  // We optimize zero matrices away to improve solver speed.
-  bool isZeroMatrix = true;
-
-
-  // Row index. Starts at 1, since the 0th row is for the spill option, which
-  // is always zero.
-  unsigned ri = 1;
-
-  // Iterate over allowed sets, insert infinities where required.
-  for (RegContainerIterator a1Itr = allowed1.begin(), a1End = allowed1.end();
-       a1Itr != a1End; ++a1Itr) {
-
-    // Column index, starts at 1 as for row index.
-    unsigned ci = 1;
-    unsigned reg1 = *a1Itr;
-
-    for (RegContainerIterator a2Itr = allowed2.begin(), a2End = allowed2.end();
-         a2Itr != a2End; ++a2Itr) {
-
-      unsigned reg2 = *a2Itr;
-
-      // If the row/column regs are identical or alias insert an infinity.
-      if (tri->regsOverlap(reg1, reg2)) {
-        (*m)[ri][ci] = std::numeric_limits<PBQP::PBQPNum>::infinity();
-        isZeroMatrix = false;
-      }
-
-      ++ci;
-    }
-
-    ++ri;
-  }
-
-  // If this turns out to be a zero matrix...
-  if (isZeroMatrix) {
-    // free it and return null.
-    delete m;
-    return 0;
-  }
-
-  // ...otherwise return the cost matrix.
-  return m;
-}
-
-template <typename RegContainer>
-PBQP::Matrix* RegAllocPBQP::buildCoalescingMatrix(
-      const RegContainer &allowed1, const RegContainer &allowed2,
-      PBQP::PBQPNum cBenefit) const {
-
-  typedef typename RegContainer::const_iterator RegContainerIterator;
-
-  // Construct a PBQP Matrix representing the benefits of coalescing. As with
-  // interference matrices the rows and columns represent allowed registers
-  // for the LiveIntervals which are (potentially) to be coalesced. The amount
-  // -cBenefit will be placed in any element representing the same register
-  // for both intervals.
-  PBQP::Matrix *m =
-    new PBQP::Matrix(allowed1.size() + 1, allowed2.size() + 1, 0);
-
-  // Reset costs to zero.
-  m->reset(0);
-
-  // Assume the matrix is zero till proven otherwise. Zero matrices will be
-  // optimized away as in the interference case.
-  bool isZeroMatrix = true;
-
-  // Row index. Starts at 1, since the 0th row is for the spill option, which
-  // is always zero.
-  unsigned ri = 1;
-
-  // Iterate over the allowed sets, insert coalescing benefits where
-  // appropriate.
-  for (RegContainerIterator a1Itr = allowed1.begin(), a1End = allowed1.end();
-       a1Itr != a1End; ++a1Itr) {
-
-    // Column index, starts at 1 as for row index.
-    unsigned ci = 1;
-    unsigned reg1 = *a1Itr;
-
-    for (RegContainerIterator a2Itr = allowed2.begin(), a2End = allowed2.end();
-         a2Itr != a2End; ++a2Itr) {
-
-      // If the row and column represent the same register insert a beneficial
-      // cost to preference this allocation - it would allow us to eliminate a
-      // move instruction.
-      if (reg1 == *a2Itr) {
-        (*m)[ri][ci] = -cBenefit;
-        isZeroMatrix = false;
-      }
-
-      ++ci;
-    }
-
-    ++ri;
-  }
-
-  // If this turns out to be a zero matrix...
-  if (isZeroMatrix) {
-    // ...free it and return null.
-    delete m;
-    return 0;
-  }
-
-  return m;
-}
-
-RegAllocPBQP::CoalesceMap RegAllocPBQP::findCoalesces() {
-
-  typedef MachineFunction::const_iterator MFIterator;
-  typedef MachineBasicBlock::const_iterator MBBIterator;
-  typedef LiveInterval::const_vni_iterator VNIIterator;
-
-  CoalesceMap coalescesFound;
-
-  // To find coalesces we need to iterate over the function looking for
-  // copy instructions.
-  for (MFIterator bbItr = mf->begin(), bbEnd = mf->end();
-       bbItr != bbEnd; ++bbItr) {
-
-    const MachineBasicBlock *mbb = &*bbItr;
-
-    for (MBBIterator iItr = mbb->begin(), iEnd = mbb->end();
-         iItr != iEnd; ++iItr) {
-
-      const MachineInstr *instr = &*iItr;
-
-      // If this isn't a copy then continue to the next instruction.
-      if (!instr->isCopy())
-        continue;
-
-      unsigned srcReg = instr->getOperand(1).getReg();
-      unsigned dstReg = instr->getOperand(0).getReg();
-
-      // If the registers are already the same our job is nice and easy.
-      if (dstReg == srcReg)
-        continue;
-
-      bool srcRegIsPhysical = TargetRegisterInfo::isPhysicalRegister(srcReg),
-           dstRegIsPhysical = TargetRegisterInfo::isPhysicalRegister(dstReg);
-
-      // If both registers are physical then we can't coalesce.
-      if (srcRegIsPhysical && dstRegIsPhysical)
-        continue;
-
-      // If it's a copy that includes two virtual register but the source and
-      // destination classes differ then we can't coalesce.
-      if (!srcRegIsPhysical && !dstRegIsPhysical &&
-          mri->getRegClass(srcReg) != mri->getRegClass(dstReg))
-        continue;
-
-      // If one is physical and one is virtual, check that the physical is
-      // allocatable in the class of the virtual.
-      if (srcRegIsPhysical && !dstRegIsPhysical) {
-        const TargetRegisterClass *dstRegClass = mri->getRegClass(dstReg);
-        if (std::find(dstRegClass->allocation_order_begin(*mf),
-                      dstRegClass->allocation_order_end(*mf), srcReg) ==
-            dstRegClass->allocation_order_end(*mf))
-          continue;
-      }
-      if (!srcRegIsPhysical && dstRegIsPhysical) {
-        const TargetRegisterClass *srcRegClass = mri->getRegClass(srcReg);
-        if (std::find(srcRegClass->allocation_order_begin(*mf),
-                      srcRegClass->allocation_order_end(*mf), dstReg) ==
-            srcRegClass->allocation_order_end(*mf))
-          continue;
-      }
-
-      // If we've made it here we have a copy with compatible register classes.
-      // We can probably coalesce, but we need to consider overlap.
-      const LiveInterval *srcLI = &lis->getInterval(srcReg),
-                         *dstLI = &lis->getInterval(dstReg);
-
-      if (srcLI->overlaps(*dstLI)) {
-        // Even in the case of an overlap we might still be able to coalesce,
-        // but we need to make sure that no definition of either range occurs
-        // while the other range is live.
-
-        // Otherwise start by assuming we're ok.
-        bool badDef = false;
-
-        // Test all defs of the source range.
-        for (VNIIterator
-               vniItr = srcLI->vni_begin(), vniEnd = srcLI->vni_end();
-               vniItr != vniEnd; ++vniItr) {
-
-          // If we find a poorly defined def we err on the side of caution.
-          if (!(*vniItr)->def.isValid()) {
-            badDef = true;
-            break;
-          }
-
-          // If we find a def that kills the coalescing opportunity then
-          // record it and break from the loop.
-          if (dstLI->liveAt((*vniItr)->def)) {
-            badDef = true;
-            break;
-          }
-        }
-
-        // If we have a bad def give up, continue to the next instruction.
-        if (badDef)
-          continue;
-
-        // Otherwise test definitions of the destination range.
-        for (VNIIterator
-               vniItr = dstLI->vni_begin(), vniEnd = dstLI->vni_end();
-               vniItr != vniEnd; ++vniItr) {
-
-          // We want to make sure we skip the copy instruction itself.
-          if ((*vniItr)->getCopy() == instr)
-            continue;
-
-          if (!(*vniItr)->def.isValid()) {
-            badDef = true;
-            break;
-          }
-
-          if (srcLI->liveAt((*vniItr)->def)) {
-            badDef = true;
-            break;
-          }
-        }
-
-        // As before a bad def we give up and continue to the next instr.
-        if (badDef)
-          continue;
-      }
-
-      // If we make it to here then either the ranges didn't overlap, or they
-      // did, but none of their definitions would prevent us from coalescing.
-      // We're good to go with the coalesce.
-
-      float cBenefit = std::pow(10.0f, (float)loopInfo->getLoopDepth(mbb)) / 5.0;
-
-      coalescesFound[RegPair(srcReg, dstReg)] = cBenefit;
-      coalescesFound[RegPair(dstReg, srcReg)] = cBenefit;
-    }
-
-  }
-
-  return coalescesFound;
-}
-
 void RegAllocPBQP::findVRegIntervalsToAlloc() {
 
   // Iterate over all live ranges.
@@ -834,171 +469,6 @@ void RegAllocPBQP::findVRegIntervalsToAlloc() {
   }
 }
 
-PBQP::Graph RegAllocPBQP::constructPBQPProblemOld() {
-
-  typedef std::vector<const LiveInterval*> LIVector;
-  typedef std::vector<unsigned> RegVector;
-
-  // This will store the physical intervals for easy reference.
-  LIVector physIntervals;
-
-  // Start by clearing the old node <-> live interval mappings & allowed sets
-  li2Node.clear();
-  node2LI.clear();
-  allowedSets.clear();
-
-  // Populate physIntervals, update preg use:
-  for (LiveIntervals::iterator itr = lis->begin(), end = lis->end();
-       itr != end; ++itr) {
-
-    if (TargetRegisterInfo::isPhysicalRegister(itr->first)) {
-      physIntervals.push_back(itr->second);
-      mri->setPhysRegUsed(itr->second->reg);
-    }
-  }
-
-  // Iterate over vreg intervals, construct live interval <-> node number
-  //  mappings.
-  for (RegSet::const_iterator itr = vregsToAlloc.begin(),
-                              end = vregsToAlloc.end();
-       itr != end; ++itr) {
-    const LiveInterval *li = &lis->getInterval(*itr);
-
-    li2Node[li] = node2LI.size();
-    node2LI.push_back(li);
-  }
-
-  // Get the set of potential coalesces.
-  CoalesceMap coalesces;
-
-  if (pbqpCoalescing) {
-    coalesces = findCoalesces();
-  }
-
-  // Construct a PBQP solver for this problem
-  PBQP::Graph problem;
-  problemNodes.resize(vregsToAlloc.size());
-
-  // Resize allowedSets container appropriately.
-  allowedSets.resize(vregsToAlloc.size());
-
-  BitVector ReservedRegs = tri->getReservedRegs(*mf);
-
-  // Iterate over virtual register intervals to compute allowed sets...
-  for (unsigned node = 0; node < node2LI.size(); ++node) {
-
-    // Grab pointers to the interval and its register class.
-    const LiveInterval *li = node2LI[node];
-    const TargetRegisterClass *liRC = mri->getRegClass(li->reg);
-
-    // Start by assuming all allocable registers in the class are allowed...
-    RegVector liAllowed;
-    TargetRegisterClass::iterator aob = liRC->allocation_order_begin(*mf);
-    TargetRegisterClass::iterator aoe = liRC->allocation_order_end(*mf);
-    for (TargetRegisterClass::iterator it = aob; it != aoe; ++it)
-      if (!ReservedRegs.test(*it))
-        liAllowed.push_back(*it);
-
-    // Eliminate the physical registers which overlap with this range, along
-    // with all their aliases.
-    for (LIVector::iterator pItr = physIntervals.begin(),
-       pEnd = physIntervals.end(); pItr != pEnd; ++pItr) {
-
-      if (!li->overlaps(**pItr))
-        continue;
-
-      unsigned pReg = (*pItr)->reg;
-
-      // If we get here then the live intervals overlap, but we're still ok
-      // if they're coalescable.
-      if (coalesces.find(RegPair(li->reg, pReg)) != coalesces.end()) {
-        DEBUG(dbgs() << "CoalescingOverride: (" << li->reg << ", " << pReg << ")\n");
-        continue;
-      }
-
-      // If we get here then we have a genuine exclusion.
-
-      // Remove the overlapping reg...
-      RegVector::iterator eraseItr =
-        std::find(liAllowed.begin(), liAllowed.end(), pReg);
-
-      if (eraseItr != liAllowed.end())
-        liAllowed.erase(eraseItr);
-
-      const unsigned *aliasItr = tri->getAliasSet(pReg);
-
-      if (aliasItr != 0) {
-        // ...and its aliases.
-        for (; *aliasItr != 0; ++aliasItr) {
-          RegVector::iterator eraseItr =
-            std::find(liAllowed.begin(), liAllowed.end(), *aliasItr);
-
-          if (eraseItr != liAllowed.end()) {
-            liAllowed.erase(eraseItr);
-          }
-        }
-      }
-    }
-
-    // Copy the allowed set into a member vector for use when constructing cost
-    // vectors & matrices, and mapping PBQP solutions back to assignments.
-    allowedSets[node] = AllowedSet(liAllowed.begin(), liAllowed.end());
-
-    // Set the spill cost to the interval weight, or epsilon if the
-    // interval weight is zero
-    PBQP::PBQPNum spillCost = (li->weight != 0.0) ?
-        li->weight : std::numeric_limits<PBQP::PBQPNum>::min();
-
-    // Build a cost vector for this interval.
-    problemNodes[node] =
-      problem.addNode(
-        buildCostVector(li->reg, allowedSets[node], coalesces, spillCost));
-
-  }
-
-
-  // Now add the cost matrices...
-  for (unsigned node1 = 0; node1 < node2LI.size(); ++node1) {
-    const LiveInterval *li = node2LI[node1];
-
-    // Test for live range overlaps and insert interference matrices.
-    for (unsigned node2 = node1 + 1; node2 < node2LI.size(); ++node2) {
-      const LiveInterval *li2 = node2LI[node2];
-
-      CoalesceMap::const_iterator cmItr =
-        coalesces.find(RegPair(li->reg, li2->reg));
-
-      PBQP::Matrix *m = 0;
-
-      if (cmItr != coalesces.end()) {
-        m = buildCoalescingMatrix(allowedSets[node1], allowedSets[node2],
-                                  cmItr->second);
-      }
-      else if (li->overlaps(*li2)) {
-        m = buildInterferenceMatrix(allowedSets[node1], allowedSets[node2]);
-      }
-
-      if (m != 0) {
-        problem.addEdge(problemNodes[node1],
-                        problemNodes[node2],
-                        *m);
-
-        delete m;
-      }
-    }
-  }
-
-  assert(problem.getNumNodes() == allowedSets.size());
-/*
-  std::cerr << "Allocating for " << problem.getNumNodes() << " nodes, "
-            << problem.getNumEdges() << " edges.\n";
-
-  problem.printDot(std::cerr);
-*/
-  // We're done, PBQP problem constructed - return it.
-  return problem;
-}
-
 void RegAllocPBQP::addStackInterval(const LiveInterval *spilled,
                                     MachineRegisterInfo* mri) {
   int stackSlot = vrm->getStackSlot(spilled->reg);
@@ -1020,77 +490,6 @@ void RegAllocPBQP::addStackInterval(const LiveInterval *spilled,
   stackInterval.MergeRangesInAsValue(rhsInterval, vni);
 }
 
-bool RegAllocPBQP::mapPBQPToRegAllocOld(const PBQP::Solution &solution) {
-
-  // Set to true if we have any spills
-  bool anotherRoundNeeded = false;
-
-  // Clear the existing allocation.
-  vrm->clearAllVirt();
-
-  // Iterate over the nodes mapping the PBQP solution to a register assignment.
-  for (unsigned node = 0; node < node2LI.size(); ++node) {
-    unsigned virtReg = node2LI[node]->reg,
-             allocSelection = solution.getSelection(problemNodes[node]);
-
-
-    // If the PBQP solution is non-zero it's a physical register...
-    if (allocSelection != 0) {
-      // Get the physical reg, subtracting 1 to account for the spill option.
-      unsigned physReg = allowedSets[node][allocSelection - 1];
-
-      DEBUG(dbgs() << "VREG " << virtReg << " -> "
-            << tri->getName(physReg) << " (Option: " << allocSelection << ")\n");
-
-      assert(physReg != 0);
-
-      // Add to the virt reg map and update the used phys regs.
-      vrm->assignVirt2Phys(virtReg, physReg);
-    }
-    // ...Otherwise it's a spill.
-    else {
-
-      // Make sure we ignore this virtual reg on the next round
-      // of allocation
-      vregsToAlloc.erase(virtReg);
-
-      // Insert spill ranges for this live range
-      const LiveInterval *spillInterval = node2LI[node];
-      double oldSpillWeight = spillInterval->weight;
-      SmallVector<LiveInterval*, 8> spillIs;
-      rmf->rememberUseDefs(spillInterval);
-      std::vector<LiveInterval*> newSpills =
-        lis->addIntervalsForSpills(*spillInterval, spillIs, loopInfo, *vrm);
-      addStackInterval(spillInterval, mri);
-      rmf->rememberSpills(spillInterval, newSpills);
-
-      (void) oldSpillWeight;
-      DEBUG(dbgs() << "VREG " << virtReg << " -> SPILLED (Option: 0, Cost: "
-                   << oldSpillWeight << ", New vregs: ");
-
-      // Copy any newly inserted live intervals into the list of regs to
-      // allocate.
-      for (std::vector<LiveInterval*>::const_iterator
-           itr = newSpills.begin(), end = newSpills.end();
-           itr != end; ++itr) {
-
-        assert(!(*itr)->empty() && "Empty spill range.");
-
-        DEBUG(dbgs() << (*itr)->reg << " ");
-
-        vregsToAlloc.insert((*itr)->reg);
-      }
-
-      DEBUG(dbgs() << ")\n");
-
-      // We need another round if spill intervals were added.
-      anotherRoundNeeded |= !newSpills.empty();
-    }
-  }
-
-  return !anotherRoundNeeded;
-}
-
 bool RegAllocPBQP::mapPBQPToRegAlloc(const PBQPRAProblem &problem,
                                      const PBQP::Solution &solution) {
   // Set to true if we have any spills
@@ -1255,32 +654,18 @@ bool RegAllocPBQP::runOnMachineFunction(MachineFunction &MF) {
     bool pbqpAllocComplete = false;
     unsigned round = 0;
 
-    if (!pbqpBuilder) {
-      while (!pbqpAllocComplete) {
-        DEBUG(dbgs() << "  PBQP Regalloc round " << round << ":\n");
+    while (!pbqpAllocComplete) {
+      DEBUG(dbgs() << "  PBQP Regalloc round " << round << ":\n");
 
-        PBQP::Graph problem = constructPBQPProblemOld();
-        PBQP::Solution solution =
-          PBQP::HeuristicSolver<PBQP::Heuristics::Briggs>::solve(problem);
+      std::auto_ptr<PBQPRAProblem> problem =
+        builder->build(mf, lis, loopInfo, vregsToAlloc);
+      PBQP::Solution solution =
+        PBQP::HeuristicSolver<PBQP::Heuristics::Briggs>::solve(
+          problem->getGraph());
 
-        pbqpAllocComplete = mapPBQPToRegAllocOld(solution);
+      pbqpAllocComplete = mapPBQPToRegAlloc(*problem, solution);
 
-        ++round;
-      }
-    } else {
-      while (!pbqpAllocComplete) {
-        DEBUG(dbgs() << "  PBQP Regalloc round " << round << ":\n");
-
-        std::auto_ptr<PBQPRAProblem> problem =
-          builder->build(mf, lis, loopInfo, vregsToAlloc);
-        PBQP::Solution solution =
-          PBQP::HeuristicSolver<PBQP::Heuristics::Briggs>::solve(
-            problem->getGraph());
-
-        pbqpAllocComplete = mapPBQPToRegAlloc(*problem, solution);
-
-        ++round;
-      }
+      ++round;
     }
   }
 
@@ -1291,10 +676,6 @@ bool RegAllocPBQP::runOnMachineFunction(MachineFunction &MF) {
 
   vregsToAlloc.clear();
   emptyIntervalVRegs.clear();
-  li2Node.clear();
-  node2LI.clear();
-  allowedSets.clear();
-  problemNodes.clear();
 
   DEBUG(dbgs() << "Post alloc VirtRegMap:\n" << *vrm << "\n");