2 files changed, 22 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/PeepholeOptimizer.cpp b/llvm/lib/CodeGen/PeepholeOptimizer.cpp
index 11acbe687a3..1090550243f 100644
--- a/llvm/lib/CodeGen/PeepholeOptimizer.cpp
+++ b/llvm/lib/CodeGen/PeepholeOptimizer.cpp
@@ -1882,6 +1882,8 @@ ValueTrackerResult ValueTracker::getNextSourceFromCopy() {
     return ValueTrackerResult();
   // Otherwise, we want the whole source.
   const MachineOperand &Src = Def->getOperand(1);
+  if (Src.isUndef())
+    return ValueTrackerResult();
   return ValueTrackerResult(Src.getReg(), Src.getSubReg());
 }
 
@@ -1925,6 +1927,8 @@ ValueTrackerResult ValueTracker::getNextSourceFromBitcast() {
   }
 
   const MachineOperand &Src = Def->getOperand(SrcIdx);
+  if (Src.isUndef())
+    return ValueTrackerResult();
   return ValueTrackerResult(Src.getReg(), Src.getSubReg());
 }
 
@@ -2093,6 +2097,10 @@ ValueTrackerResult ValueTracker::getNextSourceFromPHI() {
   for (unsigned i = 1, e = Def->getNumOperands(); i < e; i += 2) {
     auto &MO = Def->getOperand(i);
     assert(MO.isReg() && "Invalid PHI instruction");
+    // We have no code to deal with undef operands. They shouldn't happen in
+    // normal programs anyway.
+    if (MO.isUndef())
+      return ValueTrackerResult();
     Res.addSource(MO.getReg(), MO.getSubReg());
   }
 
@@ -2149,9 +2157,14 @@ ValueTrackerResult ValueTracker::getNextSource() {
     // If we can still move up in the use-def chain, move to the next
     // definition.
     if (!TargetRegisterInfo::isPhysicalRegister(Reg) && OneRegSrc) {
-      Def = MRI.getVRegDef(Reg);
-      DefIdx = MRI.def_begin(Reg).getOperandNo();
-      DefSubReg = Res.getSrcSubReg(0);
+      MachineRegisterInfo::def_iterator DI = MRI.def_begin(Reg);
+      if (DI != MRI.def_end()) {
+        Def = DI->getParent();
+        DefIdx = DI.getOperandNo();
+        DefSubReg = Res.getSrcSubReg(0);
+      } else {
+        Def = nullptr;
+      }
       return Res;
     }
   }
diff --git a/llvm/lib/CodeGen/TargetInstrInfo.cpp b/llvm/lib/CodeGen/TargetInstrInfo.cpp
index db925f803db..bd90ed5b55b 100644
--- a/llvm/lib/CodeGen/TargetInstrInfo.cpp
+++ b/llvm/lib/CodeGen/TargetInstrInfo.cpp
@@ -1151,6 +1151,8 @@ bool TargetInstrInfo::getRegSequenceInputs(
   for (unsigned OpIdx = 1, EndOpIdx = MI.getNumOperands(); OpIdx != EndOpIdx;
        OpIdx += 2) {
     const MachineOperand &MOReg = MI.getOperand(OpIdx);
+    if (MOReg.isUndef())
+      continue;
     const MachineOperand &MOSubIdx = MI.getOperand(OpIdx + 1);
     assert(MOSubIdx.isImm() &&
            "One of the subindex of the reg_sequence is not an immediate");
@@ -1174,6 +1176,8 @@ bool TargetInstrInfo::getExtractSubregInputs(
   // Def = EXTRACT_SUBREG v0.sub1, sub0.
   assert(DefIdx == 0 && "EXTRACT_SUBREG only has one def");
   const MachineOperand &MOReg = MI.getOperand(1);
+  if (MOReg.isUndef())
+    return false;
   const MachineOperand &MOSubIdx = MI.getOperand(2);
   assert(MOSubIdx.isImm() &&
          "The subindex of the extract_subreg is not an immediate");
@@ -1198,6 +1202,8 @@ bool TargetInstrInfo::getInsertSubregInputs(
   assert(DefIdx == 0 && "INSERT_SUBREG only has one def");
   const MachineOperand &MOBaseReg = MI.getOperand(1);
   const MachineOperand &MOInsertedReg = MI.getOperand(2);
+  if (MOInsertedReg.isUndef())
+    return false;
   const MachineOperand &MOSubIdx = MI.getOperand(3);
   assert(MOSubIdx.isImm() &&
          "One of the subindex of the reg_sequence is not an immediate");