If a split live interval is spilled again, remove the kill marker on its last use.

llvm-svn: 44611

llvm/lib/CodeGen/LiveIntervalAnalysis.cpp

@@ -1165,6 +1165,7 @@ addIntervalsForSpills(const LiveInterval &li,
   // it's also guaranteed to be a single val# / range interval.
   if (vrm.getPreSplitReg(li.reg)) {
     vrm.setIsSplitFromReg(li.reg, 0);
+    vrm.removeKillPoint(li.reg);
     bool DefIsReMat = vrm.isReMaterialized(li.reg);
     Slot = vrm.getStackSlot(li.reg);
     assert(Slot != VirtRegMap::MAX_STACK_SLOT);
@@ -1398,8 +1399,10 @@ addIntervalsForSpills(const LiveInterval &li,
         int UseIdx = LastUse->findRegisterUseOperandIdx(LI->reg);
         assert(UseIdx != -1);
         if (LastUse->getInstrDescriptor()->
-            getOperandConstraint(UseIdx, TOI::TIED_TO) == -1)
+            getOperandConstraint(UseIdx, TOI::TIED_TO) == -1) {
           LastUse->getOperand(UseIdx).setIsKill();
+          vrm.addKillPoint(LI->reg, &LastUse->getOperand(UseIdx));
+        }
       }
       RetNewLIs.push_back(LI);
     }

llvm/lib/CodeGen/VirtRegMap.cpp

@@ -64,7 +64,7 @@ VirtRegMap::VirtRegMap(MachineFunction &mf)
   : TII(*mf.getTarget().getInstrInfo()), MF(mf), 
     Virt2PhysMap(NO_PHYS_REG), Virt2StackSlotMap(NO_STACK_SLOT),
     Virt2ReMatIdMap(NO_STACK_SLOT), Virt2SplitMap(0),
-    ReMatMap(NULL), ReMatId(MAX_STACK_SLOT+1) {
+    Virt2SplitKillMap(NULL), ReMatMap(NULL), ReMatId(MAX_STACK_SLOT+1) {
   grow();
 }
 
@@ -74,6 +74,7 @@ void VirtRegMap::grow() {
   Virt2StackSlotMap.grow(LastVirtReg);
   Virt2ReMatIdMap.grow(LastVirtReg);
   Virt2SplitMap.grow(LastVirtReg);
+  Virt2SplitKillMap.grow(LastVirtReg);
   ReMatMap.grow(LastVirtReg);
 }
 

llvm/lib/CodeGen/VirtRegMap.h

@@ -66,6 +66,10 @@ namespace llvm {
     /// mapping.
     IndexedMap<unsigned, VirtReg2IndexFunctor> Virt2SplitMap;
 
+    /// Virt2SplitKillMap - This is splitted virtual register to its last use
+    /// (kill) mapping.
+    IndexedMap<MachineOperand*> Virt2SplitKillMap;
+
     /// ReMatMap - This is virtual register to re-materialized instruction
     /// mapping. Each virtual register whose definition is going to be
     /// re-materialized has an entry in it.
@@ -210,6 +214,21 @@ namespace llvm {
       ReMatMap[virtReg] = def;
     }
 
+    /// @brief record the last use (kill) of a split virtual register.
+    void addKillPoint(unsigned virtReg, MachineOperand *Op) {
+      Virt2SplitKillMap[virtReg] = Op;
+    }
+
+    /// @brief reset and remove the last use (kill) of a split virtual register.
+    void removeKillPoint(unsigned virtReg) {
+      MachineOperand *MO = Virt2SplitKillMap[virtReg];
+      if (MO) {
+        assert(MO->isKill() && "Split last use is not marked kill?");
+        MO->unsetIsKill();
+        Virt2SplitKillMap[virtReg] = NULL;
+      }
+    }
+
     /// @brief returns true if the specified MachineInstr is a spill point.
     bool isSpillPt(MachineInstr *Pt) const {
       return SpillPt2VirtMap.find(Pt) != SpillPt2VirtMap.end();