1 files changed, 50 insertions, 23 deletions

diff --git a/llvm/lib/CodeGen/LiveRangeEdit.cpp b/llvm/lib/CodeGen/LiveRangeEdit.cpp
index 72eafcd0792..987c2891544 100644
--- a/llvm/lib/CodeGen/LiveRangeEdit.cpp
+++ b/llvm/lib/CodeGen/LiveRangeEdit.cpp
@@ -63,10 +63,13 @@ void LiveRangeEdit::scanRemattable(AliasAnalysis *aa) {
   for (VNInfo *VNI : getParent().valnos) {
     if (VNI->isUnused())
       continue;
-    MachineInstr *DefMI = LIS.getInstructionFromIndex(VNI->def);
+    unsigned Original = VRM->getOriginal(getReg());
+    LiveInterval &OrigLI = LIS.getInterval(Original);
+    VNInfo *OrigVNI = OrigLI.getVNInfoAt(VNI->def);
+    MachineInstr *DefMI = LIS.getInstructionFromIndex(OrigVNI->def);
     if (!DefMI)
       continue;
-    checkRematerializable(VNI, DefMI, aa);
+    checkRematerializable(OrigVNI, DefMI, aa);
   }
   ScannedRemattable = true;
 }
@@ -113,24 +116,18 @@ bool LiveRangeEdit::allUsesAvailableAt(const MachineInstr *OrigMI,
   return true;
 }
 
-bool LiveRangeEdit::canRematerializeAt(Remat &RM,
-                                       SlotIndex UseIdx,
-                                       bool cheapAsAMove) {
+bool LiveRangeEdit::canRematerializeAt(Remat &RM, VNInfo *OrigVNI,
+                                       SlotIndex UseIdx, bool cheapAsAMove) {
   assert(ScannedRemattable && "Call anyRematerializable first");
 
   // Use scanRemattable info.
-  if (!Remattable.count(RM.ParentVNI))
+  if (!Remattable.count(OrigVNI))
     return false;
 
   // No defining instruction provided.
   SlotIndex DefIdx;
-  if (RM.OrigMI)
-    DefIdx = LIS.getInstructionIndex(*RM.OrigMI);
-  else {
-    DefIdx = RM.ParentVNI->def;
-    RM.OrigMI = LIS.getInstructionFromIndex(DefIdx);
-    assert(RM.OrigMI && "No defining instruction for remattable value");
-  }
+  assert(RM.OrigMI && "No defining instruction for remattable value");
+  DefIdx = LIS.getInstructionIndex(*RM.OrigMI);
 
   // If only cheap remats were requested, bail out early.
   if (cheapAsAMove && !TII.isAsCheapAsAMove(RM.OrigMI))
@@ -151,10 +148,12 @@ SlotIndex LiveRangeEdit::rematerializeAt(MachineBasicBlock &MBB,
                                          bool Late) {
   assert(RM.OrigMI && "Invalid remat");
   TII.reMaterialize(MBB, MI, DestReg, 0, RM.OrigMI, tri);
+  // DestReg of the cloned instruction cannot be Dead. Set isDead of DestReg
+  // to false anyway in case the isDead flag of RM.OrigMI's dest register
+  // is true.
+  (*--MI).getOperand(0).setIsDead(false);
   Rematted.insert(RM.ParentVNI);
-  return LIS.getSlotIndexes()
-      ->insertMachineInstrInMaps(*--MI, Late)
-      .getRegSlot();
+  return LIS.getSlotIndexes()->insertMachineInstrInMaps(*MI, Late).getRegSlot();
 }
 
 void LiveRangeEdit::eraseVirtReg(unsigned Reg) {
@@ -261,6 +260,15 @@ void LiveRangeEdit::eliminateDeadDef(MachineInstr *MI, ToShrinkSet &ToShrink) {
   // Collect virtual registers to be erased after MI is gone.
   SmallVector<unsigned, 8> RegsToErase;
   bool ReadsPhysRegs = false;
+  bool isOrigDef = false;
+  unsigned Dest;
+  if (VRM && MI->getOperand(0).isReg()) {
+    Dest = MI->getOperand(0).getReg();
+    unsigned Original = VRM->getOriginal(Dest);
+    LiveInterval &OrigLI = LIS.getInterval(Original);
+    VNInfo *OrigVNI = OrigLI.getVNInfoAt(Idx);
+    isOrigDef = SlotIndex::isSameInstr(OrigVNI->def, Idx);
+  }
 
   // Check for live intervals that may shrink
   for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
@@ -314,11 +322,26 @@ void LiveRangeEdit::eliminateDeadDef(MachineInstr *MI, ToShrinkSet &ToShrink) {
     }
     DEBUG(dbgs() << "Converted physregs to:\t" << *MI);
   } else {
-    if (TheDelegate)
-      TheDelegate->LRE_WillEraseInstruction(MI);
-    LIS.RemoveMachineInstrFromMaps(*MI);
-    MI->eraseFromParent();
-    ++NumDCEDeleted;
+    // If the dest of MI is an original reg, don't delete the inst. Replace
+    // the dest with a new reg, keep the inst for remat of other siblings.
+    // The inst is saved in LiveRangeEdit::DeadRemats and will be deleted
+    // after all the allocations of the func are done.
+    if (isOrigDef) {
+      LiveInterval &NewLI = createEmptyIntervalFrom(Dest);
+      VNInfo *VNI = NewLI.getNextValue(Idx, LIS.getVNInfoAllocator());
+      NewLI.addSegment(LiveInterval::Segment(Idx, Idx.getDeadSlot(), VNI));
+      pop_back();
+      markDeadRemat(MI);
+      const TargetRegisterInfo &TRI = *MRI.getTargetRegisterInfo();
+      MI->substituteRegister(Dest, NewLI.reg, 0, TRI);
+      MI->getOperand(0).setIsDead(true);
+    } else {
+      if (TheDelegate)
+        TheDelegate->LRE_WillEraseInstruction(MI);
+      LIS.RemoveMachineInstrFromMaps(*MI);
+      MI->eraseFromParent();
+      ++NumDCEDeleted;
+    }
   }
 
   // Erase any virtregs that are now empty and unused. There may be <undef>
@@ -332,8 +355,9 @@ void LiveRangeEdit::eliminateDeadDef(MachineInstr *MI, ToShrinkSet &ToShrink) {
   }
 }
 
-void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
-                                      ArrayRef<unsigned> RegsBeingSpilled) {
+void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr *> &Dead,
+                                      ArrayRef<unsigned> RegsBeingSpilled,
+                                      bool NoSplit) {
   ToShrinkSet ToShrink;
 
   for (;;) {
@@ -355,6 +379,9 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
     if (!LIS.shrinkToUses(LI, &Dead))
       continue;
 
+    if (NoSplit)
+      continue;
+
     // Don't create new intervals for a register being spilled.
     // The new intervals would have to be spilled anyway so its not worth it.
     // Also they currently aren't spilled so creating them and not spilling