Auto-compute live intervals on demand.

When new virtual registers are created during splitting/spilling, defer
creation of the live interval until we need to use the live interval.

Along with the recent commits to notify LiveRangeEdit when new virtual
registers are created, this makes it possible for functions like
TargetInstrInfo::loadRegFromStackSlot() and
TargetInstrInfo::storeRegToStackSlot() to create multiple virtual
registers as part of the process of generating loads/stores for
different register classes, and then have the live intervals for those
new registers computed when they are needed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188437 91177308-0d34-0410-b5e6-96231b3b80d8

9 files changed, 145 insertions, 101 deletions

diff --git a/include/llvm/CodeGen/LiveIntervalAnalysis.h b/include/llvm/CodeGen/LiveIntervalAnalysis.h
index ffb07a5487..d134781cfc 100644
--- a/include/llvm/CodeGen/LiveIntervalAnalysis.h
+++ b/include/llvm/CodeGen/LiveIntervalAnalysis.h
@@ -103,9 +103,10 @@ namespace llvm {
     static float getSpillWeight(bool isDef, bool isUse, BlockFrequency freq);
 
     LiveInterval &getInterval(unsigned Reg) {
-      LiveInterval *LI = VirtRegIntervals[Reg];
-      assert(LI && "Interval does not exist for virtual register");
-      return *LI;
+      if (hasInterval(Reg))
+        return *VirtRegIntervals[Reg];
+      else
+        return createAndComputeVirtRegInterval(Reg);
     }
 
     const LiveInterval &getInterval(unsigned Reg) const {
@@ -117,12 +118,17 @@ namespace llvm {
     }
 
     // Interval creation.
-    LiveInterval &getOrCreateInterval(unsigned Reg) {
-      if (!hasInterval(Reg)) {
-        VirtRegIntervals.grow(Reg);
-        VirtRegIntervals[Reg] = createInterval(Reg);
-      }
-      return getInterval(Reg);
+    LiveInterval &createEmptyInterval(unsigned Reg) {
+      assert(!hasInterval(Reg) && "Interval already exists!");
+      VirtRegIntervals.grow(Reg);
+      VirtRegIntervals[Reg] = createInterval(Reg);
+      return *VirtRegIntervals[Reg];
+    }
+
+    LiveInterval &createAndComputeVirtRegInterval(unsigned Reg) {
+      LiveInterval &LI = createEmptyInterval(Reg);
+      computeVirtRegInterval(&LI);
+      return LI;
     }
 
     // Interval removal.
@@ -225,6 +231,12 @@ namespace llvm {
       return Indexes->insertMachineInstrInMaps(MI);
     }
 
+    void InsertMachineInstrRangeInMaps(MachineBasicBlock::iterator B,
+                                       MachineBasicBlock::iterator E) {
+      for (MachineBasicBlock::iterator I = B; I != E; ++I)
+        Indexes->insertMachineInstrInMaps(I);
+    }
+
     void RemoveMachineInstrFromMaps(MachineInstr *MI) {
       Indexes->removeMachineInstrFromMaps(MI);
     }
diff --git a/include/llvm/CodeGen/LiveRangeEdit.h b/include/llvm/CodeGen/LiveRangeEdit.h
index 43a956605a..7edf67cc24 100644
--- a/include/llvm/CodeGen/LiveRangeEdit.h
+++ b/include/llvm/CodeGen/LiveRangeEdit.h
@@ -144,12 +144,19 @@ public:
     return makeArrayRef(NewRegs).slice(FirstNew);
   }
 
+  /// createEmptyIntervalFrom - Create a new empty interval based on OldReg.
+  LiveInterval &createEmptyIntervalFrom(unsigned OldReg);
+
   /// createFrom - Create a new virtual register based on OldReg.
-  LiveInterval &createFrom(unsigned OldReg);
+  unsigned createFrom(unsigned OldReg);
 
   /// create - Create a new register with the same class and original slot as
   /// parent.
-  LiveInterval &create() {
+  LiveInterval &createEmptyInterval() {
+    return createEmptyIntervalFrom(getReg());
+  }
+
+  unsigned create() {
     return createFrom(getReg());
   }
 
diff --git a/lib/CodeGen/InlineSpiller.cpp b/lib/CodeGen/InlineSpiller.cpp
index 8910652c40..d5f300f9aa 100644
--- a/lib/CodeGen/InlineSpiller.cpp
+++ b/lib/CodeGen/InlineSpiller.cpp
@@ -179,10 +179,8 @@ private:
   bool coalesceStackAccess(MachineInstr *MI, unsigned Reg);
   bool foldMemoryOperand(ArrayRef<std::pair<MachineInstr*, unsigned> >,
                          MachineInstr *LoadMI = 0);
-  void insertReload(LiveInterval &NewLI, SlotIndex,
-                    MachineBasicBlock::iterator MI);
-  void insertSpill(LiveInterval &NewLI, const LiveInterval &OldLI,
-                   SlotIndex, MachineBasicBlock::iterator MI);
+  void insertReload(unsigned VReg, SlotIndex, MachineBasicBlock::iterator MI);
+  void insertSpill(unsigned VReg, bool isKill, MachineBasicBlock::iterator MI);
 
   void spillAroundUses(unsigned Reg);
   void spillAll();
@@ -885,12 +883,12 @@ bool InlineSpiller::reMaterializeFor(LiveInterval &VirtReg,
   }
 
   // Alocate a new register for the remat.
-  LiveInterval &NewLI = Edit->createFrom(Original);
-  NewLI.markNotSpillable();
+  unsigned NewVReg = Edit->createFrom(Original);
 
   // Finally we can rematerialize OrigMI before MI.
-  SlotIndex DefIdx = Edit->rematerializeAt(*MI->getParent(), MI, NewLI.reg, RM,
+  SlotIndex DefIdx = Edit->rematerializeAt(*MI->getParent(), MI, NewVReg, RM,
                                            TRI);
+  (void)DefIdx;
   DEBUG(dbgs() << "\tremat:  " << DefIdx << '\t'
                << *LIS.getInstructionFromIndex(DefIdx));
 
@@ -898,15 +896,12 @@ bool InlineSpiller::reMaterializeFor(LiveInterval &VirtReg,
   for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
     MachineOperand &MO = MI->getOperand(Ops[i].second);
     if (MO.isReg() && MO.isUse() && MO.getReg() == VirtReg.reg) {
-      MO.setReg(NewLI.reg);
+      MO.setReg(NewVReg);
       MO.setIsKill();
     }
   }
-  DEBUG(dbgs() << "\t        " << UseIdx << '\t' << *MI);
+  DEBUG(dbgs() << "\t        " << UseIdx << '\t' << *MI << '\n');
 
-  VNInfo *DefVNI = NewLI.getNextValue(DefIdx, LIS.getVNInfoAllocator());
-  NewLI.addRange(LiveRange(DefIdx, UseIdx.getRegSlot(), DefVNI));
-  DEBUG(dbgs() << "\tinterval: " << NewLI << '\n');
   ++NumRemats;
   return true;
 }
@@ -1009,6 +1004,40 @@ bool InlineSpiller::coalesceStackAccess(MachineInstr *MI, unsigned Reg) {
   return true;
 }
 
+#if !defined(NDEBUG)
+// Dump the range of instructions from B to E with their slot indexes.
+static void dumpMachineInstrRangeWithSlotIndex(MachineBasicBlock::iterator B,
+                                               MachineBasicBlock::iterator E,
+                                               LiveIntervals const &LIS,
+                                               const char *const header,
+                                               unsigned VReg =0) {
+  char NextLine = '\n';
+  char SlotIndent = '\t';
+
+  if (llvm::next(B) == E) {
+    NextLine = ' ';
+    SlotIndent = ' ';
+  }
+
+  dbgs() << '\t' << header << ": " << NextLine;
+
+  for (MachineBasicBlock::iterator I = B; I != E; ++I) {
+    SlotIndex Idx = LIS.getInstructionIndex(I).getRegSlot();
+
+    // If a register was passed in and this instruction has it as a
+    // destination that is marked as an early clobber, print the
+    // early-clobber slot index.
+    if (VReg) {
+      MachineOperand *MO = I->findRegisterDefOperand(VReg);
+      if (MO && MO->isEarlyClobber())
+        Idx = Idx.getRegSlot(true);
+    }
+
+    dbgs() << SlotIndent << Idx << '\t' << *I;
+  }
+}
+#endif
+
 /// foldMemoryOperand - Try folding stack slot references in Ops into their
 /// instructions.
 ///
@@ -1049,6 +1078,8 @@ foldMemoryOperand(ArrayRef<std::pair<MachineInstr*, unsigned> > Ops,
       FoldOps.push_back(Idx);
   }
 
+  MachineInstrSpan MIS(MI);
+
   MachineInstr *FoldMI =
                 LoadMI ? TII.foldMemoryOperand(MI, FoldOps, LoadMI)
                        : TII.foldMemoryOperand(MI, FoldOps, StackSlot);
@@ -1082,9 +1113,17 @@ foldMemoryOperand(ArrayRef<std::pair<MachineInstr*, unsigned> > Ops,
       }
     }
   }
+
   LIS.ReplaceMachineInstrInMaps(MI, FoldMI);
   MI->eraseFromParent();
 
+  // Insert any new instructions other than FoldMI into the LIS maps.
+  assert(!MIS.empty() && "Unexpected empty span of instructions!");
+  for (MachineBasicBlock::iterator MII = MIS.begin(), End = MIS.end();
+       MII != End; ++MII)
+    if (&*MII != FoldMI)
+      LIS.InsertMachineInstrInMaps(&*MII);
+
   // TII.foldMemoryOperand may have left some implicit operands on the
   // instruction.  Strip them.
   if (ImpReg)
@@ -1096,8 +1135,9 @@ foldMemoryOperand(ArrayRef<std::pair<MachineInstr*, unsigned> > Ops,
         FoldMI->RemoveOperand(i - 1);
     }
 
-  DEBUG(dbgs() << "\tfolded:  " << LIS.getInstructionIndex(FoldMI) << '\t'
-               << *FoldMI);
+  DEBUG(dumpMachineInstrRangeWithSlotIndex(MIS.begin(), MIS.end(), LIS,
+                                           "folded"));
+
   if (!WasCopy)
     ++NumFolded;
   else if (Ops.front().second == 0)
@@ -1107,36 +1147,35 @@ foldMemoryOperand(ArrayRef<std::pair<MachineInstr*, unsigned> > Ops,
   return true;
 }
 
-/// insertReload - Insert a reload of NewLI.reg before MI.
-void InlineSpiller::insertReload(LiveInterval &NewLI,
+void InlineSpiller::insertReload(unsigned NewVReg,
                                  SlotIndex Idx,
                                  MachineBasicBlock::iterator MI) {
   MachineBasicBlock &MBB = *MI->getParent();
-  TII.loadRegFromStackSlot(MBB, MI, NewLI.reg, StackSlot,
-                           MRI.getRegClass(NewLI.reg), &TRI);
-  --MI; // Point to load instruction.
-  SlotIndex LoadIdx = LIS.InsertMachineInstrInMaps(MI).getRegSlot();
-  // Some (out-of-tree) targets have EC reload instructions.
-  if (MachineOperand *MO = MI->findRegisterDefOperand(NewLI.reg))
-    if (MO->isEarlyClobber())
-      LoadIdx = LoadIdx.getRegSlot(true);
-  DEBUG(dbgs() << "\treload:  " << LoadIdx << '\t' << *MI);
-  VNInfo *LoadVNI = NewLI.getNextValue(LoadIdx, LIS.getVNInfoAllocator());
-  NewLI.addRange(LiveRange(LoadIdx, Idx, LoadVNI));
+
+  MachineInstrSpan MIS(MI);
+  TII.loadRegFromStackSlot(MBB, MI, NewVReg, StackSlot,
+                           MRI.getRegClass(NewVReg), &TRI);
+
+  LIS.InsertMachineInstrRangeInMaps(MIS.begin(), MI);
+
+  DEBUG(dumpMachineInstrRangeWithSlotIndex(MIS.begin(), MI, LIS, "reload",
+                                           NewVReg));
   ++NumReloads;
 }
 
-/// insertSpill - Insert a spill of NewLI.reg after MI.
-void InlineSpiller::insertSpill(LiveInterval &NewLI, const LiveInterval &OldLI,
-                                SlotIndex Idx, MachineBasicBlock::iterator MI) {
+/// insertSpill - Insert a spill of NewVReg after MI.
+void InlineSpiller::insertSpill(unsigned NewVReg, bool isKill,
+                                 MachineBasicBlock::iterator MI) {
   MachineBasicBlock &MBB = *MI->getParent();
-  TII.storeRegToStackSlot(MBB, ++MI, NewLI.reg, true, StackSlot,
-                          MRI.getRegClass(NewLI.reg), &TRI);
-  --MI; // Point to store instruction.
-  SlotIndex StoreIdx = LIS.InsertMachineInstrInMaps(MI).getRegSlot();
-  DEBUG(dbgs() << "\tspilled: " << StoreIdx << '\t' << *MI);
-  VNInfo *StoreVNI = NewLI.getNextValue(Idx, LIS.getVNInfoAllocator());
-  NewLI.addRange(LiveRange(Idx, StoreIdx, StoreVNI));
+
+  MachineInstrSpan MIS(MI);
+  TII.storeRegToStackSlot(MBB, llvm::next(MI), NewVReg, isKill, StackSlot,
+                          MRI.getRegClass(NewVReg), &TRI);
+
+  LIS.InsertMachineInstrRangeInMaps(llvm::next(MI), MIS.end());
+
+  DEBUG(dumpMachineInstrRangeWithSlotIndex(llvm::next(MI), MIS.end(), LIS,
+                                           "spill"));
   ++NumSpills;
 }
 
@@ -1212,19 +1251,18 @@ void InlineSpiller::spillAroundUses(unsigned Reg) {
     if (foldMemoryOperand(Ops))
       continue;
 
-    // Allocate interval around instruction.
+    // Create a new virtual register for spill/fill.
     // FIXME: Infer regclass from instruction alone.
-    LiveInterval &NewLI = Edit->createFrom(Reg);
-    NewLI.markNotSpillable();
+    unsigned NewVReg = Edit->createFrom(Reg);
 
     if (RI.Reads)
-      insertReload(NewLI, Idx, MI);
+      insertReload(NewVReg, Idx, MI);
 
     // Rewrite instruction operands.
     bool hasLiveDef = false;
     for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
       MachineOperand &MO = Ops[i].first->getOperand(Ops[i].second);
-      MO.setReg(NewLI.reg);
+      MO.setReg(NewVReg);
       if (MO.isUse()) {
         if (!Ops[i].first->isRegTiedToDefOperand(Ops[i].second))
           MO.setIsKill();
@@ -1233,21 +1271,12 @@ void InlineSpiller::spillAroundUses(unsigned Reg) {
           hasLiveDef = true;
       }
     }
-    DEBUG(dbgs() << "\trewrite: " << Idx << '\t' << *MI);
+    DEBUG(dbgs() << "\trewrite: " << Idx << '\t' << *MI << '\n');
 
     // FIXME: Use a second vreg if instruction has no tied ops.
-    if (RI.Writes) {
+    if (RI.Writes)
       if (hasLiveDef)
-        insertSpill(NewLI, OldLI, Idx, MI);
-      else {
-        // This instruction defines a dead value.  We don't need to spill it,
-        // but do create a live range for the dead value.
-        VNInfo *VNI = NewLI.getNextValue(Idx, LIS.getVNInfoAllocator());
-        NewLI.addRange(LiveRange(Idx, Idx.getDeadSlot(), VNI));
-      }
-    }
-
-    DEBUG(dbgs() << "\tinterval: " << NewLI << '\n');
+        insertSpill(NewVReg, true, MI);
   }
 }
 
@@ -1309,7 +1338,7 @@ void InlineSpiller::spill(LiveRangeEdit &edit) {
   DEBUG(dbgs() << "Inline spilling "
                << MRI.getRegClass(edit.getReg())->getName()
                << ':' << PrintReg(edit.getReg()) << ' ' << edit.getParent()
-               << "\nFrom original " << LIS.getInterval(Original) << '\n');
+               << "\nFrom original " << PrintReg(Original) << '\n');
   assert(edit.getParent().isSpillable() &&
          "Attempting to spill already spilled value.");
   assert(DeadDefs.empty() && "Previous spill didn't remove dead defs");
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index c0fc477fe6..886c7f1cc5 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -190,9 +190,7 @@ void LiveIntervals::computeVirtRegs() {
     unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
     if (MRI->reg_nodbg_empty(Reg))
       continue;
-    LiveInterval *LI = createInterval(Reg);
-    VirtRegIntervals[Reg] = LI;
-    computeVirtRegInterval(LI);
+    createAndComputeVirtRegInterval(Reg);
   }
 }
 
@@ -627,7 +625,7 @@ LiveIntervals::getSpillWeight(bool isDef, bool isUse, BlockFrequency freq) {
 
 LiveRange LiveIntervals::addLiveRangeToEndOfBlock(unsigned reg,
                                                   MachineInstr* startInst) {
-  LiveInterval& Interval = getOrCreateInterval(reg);
+  LiveInterval& Interval = createEmptyInterval(reg);
   VNInfo* VN = Interval.getNextValue(
     SlotIndex(getInstructionIndex(startInst).getRegSlot()),
     getVNInfoAllocator());
@@ -1074,8 +1072,7 @@ LiveIntervals::repairIntervalsInRange(MachineBasicBlock *MBB,
       if (MOI->isReg() &&
           TargetRegisterInfo::isVirtualRegister(MOI->getReg()) &&
           !hasInterval(MOI->getReg())) {
-        LiveInterval &LI = getOrCreateInterval(MOI->getReg());
-        computeVirtRegInterval(&LI);
+        createAndComputeVirtRegInterval(MOI->getReg());
       }
     }
   }
diff --git a/lib/CodeGen/LiveRangeEdit.cpp b/lib/CodeGen/LiveRangeEdit.cpp
index 04f92adefd..ca64729ab9 100644
--- a/lib/CodeGen/LiveRangeEdit.cpp
+++ b/lib/CodeGen/LiveRangeEdit.cpp
@@ -30,15 +30,23 @@ STATISTIC(NumFracRanges,     "Number of live ranges fractured by DCE");
 
 void LiveRangeEdit::Delegate::anchor() { }
 
-LiveInterval &LiveRangeEdit::createFrom(unsigned OldReg) {
+LiveInterval &LiveRangeEdit::createEmptyIntervalFrom(unsigned OldReg) {
   unsigned VReg = MRI.createVirtualRegister(MRI.getRegClass(OldReg));
   if (VRM) {
     VRM->setIsSplitFromReg(VReg, VRM->getOriginal(OldReg));
   }
-  LiveInterval &LI = LIS.getOrCreateInterval(VReg);
+  LiveInterval &LI = LIS.createEmptyInterval(VReg);
   return LI;
 }
 
+unsigned LiveRangeEdit::createFrom(unsigned OldReg) {
+  unsigned VReg = MRI.createVirtualRegister(MRI.getRegClass(OldReg));
+  if (VRM) {
+    VRM->setIsSplitFromReg(VReg, VRM->getOriginal(OldReg));
+  }
+  return VReg;
+}
+
 bool LiveRangeEdit::checkRematerializable(VNInfo *VNI,
                                           const MachineInstr *DefMI,
                                           AliasAnalysis *aa) {
@@ -368,7 +376,7 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
     DEBUG(dbgs() << NumComp << " components: " << *LI << '\n');
     SmallVector<LiveInterval*, 8> Dups(1, LI);
     for (unsigned i = 1; i != NumComp; ++i) {
-      Dups.push_back(&createFrom(LI->reg));
+      Dups.push_back(&createEmptyIntervalFrom(LI->reg));
       // If LI is an original interval that hasn't been split yet, make the new
       // intervals their own originals instead of referring to LI. The original
       // interval must contain all the split products, and LI doesn't.
diff --git a/lib/CodeGen/PHIElimination.cpp b/lib/CodeGen/PHIElimination.cpp
index bf23ecac4d..e6ffb714aa 100644
--- a/lib/CodeGen/PHIElimination.cpp
+++ b/lib/CodeGen/PHIElimination.cpp
@@ -313,7 +313,7 @@ void PHIElimination::LowerPHINode(MachineBasicBlock &MBB,
     if (IncomingReg) {
       // Add the region from the beginning of MBB to the copy instruction to
       // IncomingReg's live interval.
-      LiveInterval &IncomingLI = LIS->getOrCreateInterval(IncomingReg);
+      LiveInterval &IncomingLI = LIS->createEmptyInterval(IncomingReg);
       VNInfo *IncomingVNI = IncomingLI.getVNInfoAt(MBBStartIndex);
       if (!IncomingVNI)
         IncomingVNI = IncomingLI.getNextValue(MBBStartIndex,
diff --git a/lib/CodeGen/Spiller.cpp b/lib/CodeGen/Spiller.cpp
index 209792fd40..d72c596a84 100644
--- a/lib/CodeGen/Spiller.cpp
+++ b/lib/CodeGen/Spiller.cpp
@@ -115,15 +115,14 @@ protected:
         indices.push_back(i);
       }
 
-      // Create a new vreg & interval for this instr.
-      LiveInterval *newLI = &LRE.create();
-      newLI->weight = HUGE_VALF;
+      // Create a new virtual register for the load and/or store.
+      unsigned NewVReg = LRE.create();
 
       // Update the reg operands & kill flags.
       for (unsigned i = 0; i < indices.size(); ++i) {
         unsigned mopIdx = indices[i];
         MachineOperand &mop = mi->getOperand(mopIdx);
-        mop.setReg(newLI->reg);
+        mop.setReg(NewVReg);
         if (mop.isUse() && !mi->isRegTiedToDefOperand(mopIdx)) {
           mop.setIsKill(true);
         }
@@ -133,28 +132,20 @@ protected:
       // Insert reload if necessary.
       MachineBasicBlock::iterator miItr(mi);
       if (hasUse) {
-        tii->loadRegFromStackSlot(*mi->getParent(), miItr, newLI->reg, ss, trc,
+        MachineInstrSpan MIS(miItr);
+
+        tii->loadRegFromStackSlot(*mi->getParent(), miItr, NewVReg, ss, trc,
                                   tri);
-        MachineInstr *loadInstr(prior(miItr));
-        SlotIndex loadIndex =
-          lis->InsertMachineInstrInMaps(loadInstr).getRegSlot();
-        SlotIndex endIndex = loadIndex.getNextIndex();
-        VNInfo *loadVNI =
-          newLI->getNextValue(loadIndex, lis->getVNInfoAllocator());
-        newLI->addRange(LiveRange(loadIndex, endIndex, loadVNI));
+        lis->InsertMachineInstrRangeInMaps(MIS.begin(), miItr);
       }
 
       // Insert store if necessary.
       if (hasDef) {
-        tii->storeRegToStackSlot(*mi->getParent(), llvm::next(miItr),newLI->reg,
+        MachineInstrSpan MIS(miItr);
+
+        tii->storeRegToStackSlot(*mi->getParent(), llvm::next(miItr), NewVReg,
                                  true, ss, trc, tri);
-        MachineInstr *storeInstr(llvm::next(miItr));
-        SlotIndex storeIndex =
-          lis->InsertMachineInstrInMaps(storeInstr).getRegSlot();
-        SlotIndex beginIndex = storeIndex.getPrevIndex();
-        VNInfo *storeVNI =
-          newLI->getNextValue(beginIndex, lis->getVNInfoAllocator());
-        newLI->addRange(LiveRange(beginIndex, storeIndex, storeVNI));
+        lis->InsertMachineInstrRangeInMaps(llvm::next(miItr), MIS.end());
       }
     }
   }
diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index c10fee20e8..be1bfa0d6a 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -463,11 +463,11 @@ VNInfo *SplitEditor::defFromParent(unsigned RegIdx,
 unsigned SplitEditor::openIntv() {
   // Create the complement as index 0.
   if (Edit->empty())
-    Edit->create();
+    Edit->createEmptyInterval();
 
   // Create the open interval.
   OpenIdx = Edit->size();
-  Edit->create();
+  Edit->createEmptyInterval();
   return OpenIdx;
 }
 
@@ -1116,7 +1116,7 @@ void SplitEditor::finish(SmallVectorImpl<unsigned> *LRMap) {
     SmallVector<LiveInterval*, 8> dups;
     dups.push_back(li);
     for (unsigned j = 1; j != NumComp; ++j)
-      dups.push_back(&Edit->create());
+      dups.push_back(&Edit->createEmptyInterval());
     ConEQ.Distribute(&dups[0], MRI);
     // The new intervals all map back to i.
     if (LRMap)
diff --git a/lib/CodeGen/StrongPHIElimination.cpp b/lib/CodeGen/StrongPHIElimination.cpp
index b337c53933..d8b287f737 100644
--- a/lib/CodeGen/StrongPHIElimination.cpp
+++ b/lib/CodeGen/StrongPHIElimination.cpp
@@ -772,7 +772,7 @@ void StrongPHIElimination::InsertCopiesForPHI(MachineInstr *PHI,
 
   // Add the region from the beginning of MBB to the copy instruction to
   // CopyReg's live interval, and give the VNInfo the phidef flag.
-  LiveInterval &CopyLI = LI->getOrCreateInterval(CopyReg);
+  LiveInterval &CopyLI = LI->createEmptyInterval(CopyReg);
   SlotIndex MBBStartIndex = LI->getMBBStartIdx(MBB);
   SlotIndex DestCopyIndex = LI->getInstructionIndex(CopyInstr);
   VNInfo *CopyVNI = CopyLI.getNextValue(MBBStartIndex,
@@ -783,7 +783,7 @@ void StrongPHIElimination::InsertCopiesForPHI(MachineInstr *PHI,
 
   // Adjust DestReg's live interval to adjust for its new definition at
   // CopyInstr.
-  LiveInterval &DestLI = LI->getOrCreateInterval(DestReg);
+  LiveInterval &DestLI = LI->createEmptyInterval(DestReg);
   SlotIndex PHIIndex = LI->getInstructionIndex(PHI);
   DestLI.removeRange(PHIIndex.getRegSlot(), DestCopyIndex.getRegSlot());