Index: llvm/lib/Analysis/ValueTracking.cpp
===================================================================
--- llvm/lib/Analysis/ValueTracking.cpp
+++ llvm/lib/Analysis/ValueTracking.cpp
@@ -2513,14 +2513,15 @@
   return isKnownNonZero(V, DemandedElts, Depth, Q);
 }
 
-/// If the pair of operators are the same invertible function of a single
-/// operand return the index of that operand.  Otherwise, return None.  An
-/// invertible function is one that is 1-to-1 and maps every input value
-/// to exactly one output value.  This is equivalent to saying that Op1
-/// and Op2 are equal exactly when the specified pair of operands are equal,
-/// (except that Op1 and Op2 may be poison more often.)
-static Optional<unsigned> getInvertibleOperand(const Operator *Op1,
-                                               const Operator *Op2) {
+/// If the pair of operators are the same invertible function of a single pair
+/// of operands, return the respective operand numbers of said pair.
+/// Otherwise, return None.  An invertible function is one that is 1-to-1 and
+/// maps every input value to exactly one output value.  This is equivalent to
+/// saying that Op1 and Op2 are equal exactly when the specified pair of
+/// operands are equal, (except that Op1 and Op2 may be poison more often.)
+static Optional<std::pair<unsigned, unsigned>>
+getInvertibleOperand(const Operator *Op1,
+                     const Operator *Op2) {
   if (Op1->getOpcode() != Op2->getOpcode())
     return None;
 
@@ -2530,9 +2531,9 @@
   case Instruction::Add:
   case Instruction::Sub:
     if (Op1->getOperand(0) == Op2->getOperand(0))
-      return 1;
+      return std::make_pair(1U, 1U);
     if (Op1->getOperand(1) == Op2->getOperand(1))
-      return 0;
+      return std::make_pair(0U, 0U);
     break;
   case Instruction::Mul: {
     // invertible if A * B == (A * B) mod 2^N where A, and B are integers
@@ -2548,7 +2549,7 @@
     if (Op1->getOperand(1) == Op2->getOperand(1) &&
         isa<ConstantInt>(Op1->getOperand(1)) &&
         !cast<ConstantInt>(Op1->getOperand(1))->isZero())
-      return 0;
+      return std::make_pair(0U, 0U);
     break;
   }
   case Instruction::Shl: {
@@ -2561,7 +2562,7 @@
       break;
 
     if (Op1->getOperand(1) == Op2->getOperand(1))
-      return 0;
+      return std::make_pair(0U, 0U);
     break;
   }
   case Instruction::AShr:
@@ -2572,13 +2573,13 @@
       break;
 
     if (Op1->getOperand(1) == Op2->getOperand(1))
-      return 0;
+      return std::make_pair(0U, 0U);
     break;
   }
   case Instruction::SExt:
   case Instruction::ZExt:
     if (Op1->getOperand(0)->getType() == Op2->getOperand(0)->getType())
-      return 0;
+      return std::make_pair(0U, 0U);
     break;
   case Instruction::PHI: {
     const PHINode *PN1 = cast<PHINode>(Op1);
@@ -2596,18 +2597,16 @@
         !matchSimpleRecurrence(PN2, BO2, Start2, Step2))
       break;
 
-    Optional<unsigned> Idx = getInvertibleOperand(cast<Operator>(BO1),
-                                                  cast<Operator>(BO2));
-    if (!Idx || *Idx != 0)
+    Optional<std::pair<unsigned,unsigned>> Idx =
+      getInvertibleOperand(cast<Operator>(BO1), cast<Operator>(BO2));
+    if (!Idx || Idx->first != 0 || Idx->second != 0)
       break;
-    assert(BO1->getOperand(*Idx) == PN1 && BO2->getOperand(*Idx) == PN2);
+    assert(BO1->getOperand(Idx->first) == PN1 &&
+           BO2->getOperand(Idx->second) == PN2);
 
-    // Phi operands might not be in the same order.  TODO: generalize
-    // interface to return pair of operands.
-    if (PN1->getOperand(0) == BO1 && PN2->getOperand(0) == BO2)
-      return 1;
-    if (PN1->getOperand(1) == BO1 && PN2->getOperand(1) == BO2)
-      return 0;
+    // Phi operands might not be in the same order.
+    return std::make_pair(PN1->getOperand(0) == BO1 ? 1U : 0U,
+                          PN2->getOperand(0) == BO2 ? 1U : 0U);
   }
   }
   return None;
@@ -2704,10 +2703,9 @@
   auto *O1 = dyn_cast<Operator>(V1);
   auto *O2 = dyn_cast<Operator>(V2);
   if (O1 && O2 && O1->getOpcode() == O2->getOpcode()) {
-    if (Optional<unsigned> Opt = getInvertibleOperand(O1, O2)) {
-      unsigned Idx = *Opt;
-      return isKnownNonEqual(O1->getOperand(Idx), O2->getOperand(Idx),
-                             Depth + 1, Q);
+    if (auto Opt = getInvertibleOperand(O1, O2)) {
+      return isKnownNonEqual(O1->getOperand(Opt->first),
+                             O2->getOperand(Opt->second), Depth + 1, Q);
     }
     if (const PHINode *PN1 = dyn_cast<PHINode>(V1)) {
       const PHINode *PN2 = cast<PHINode>(V2);
Index: llvm/test/Analysis/ValueTracking/known-non-equal.ll
===================================================================
--- llvm/test/Analysis/ValueTracking/known-non-equal.ll
+++ llvm/test/Analysis/ValueTracking/known-non-equal.ll
@@ -810,8 +810,7 @@
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i64 [[IV_NEXT]], 10
 ; CHECK-NEXT:    br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
 ; CHECK:       exit:
-; CHECK-NEXT:    [[RES:%.*]] = icmp eq i8 [[A_IV]], [[B_IV]]
-; CHECK-NEXT:    ret i1 [[RES]]
+; CHECK-NEXT:    ret i1 false
 ;
 entry:
   %B = add i8 %A, 1
@@ -845,8 +844,7 @@
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i64 [[IV_NEXT]], 10
 ; CHECK-NEXT:    br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
 ; CHECK:       exit:
-; CHECK-NEXT:    [[RES:%.*]] = icmp eq i8 [[A_IV]], [[B_IV]]
-; CHECK-NEXT:    ret i1 [[RES]]
+; CHECK-NEXT:    ret i1 false
 ;
 entry:
   %B = add i8 %A, 1