[LV] Replace unreachable by folding into else with assert (NFC).

Simplify code as suggested post-commit in
#110576.

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -2795,14 +2795,14 @@ void InnerLoopVectorizer::fixupIVUsers(PHINode *OrigPhi,
         Escape = B.CreateSub(EndValue, Step);
       else if (EndValue->getType()->isPointerTy())
         Escape = B.CreatePtrAdd(EndValue, B.CreateNeg(Step));
-      else if (EndValue->getType()->isFloatingPointTy()) {
+      else {
+        assert(EndValue->getType()->isFloatingPointTy() &&
+               "Unexpected induction type");
         Escape = B.CreateBinOp(II.getInductionBinOp()->getOpcode() ==
                                        Instruction::FAdd
                                    ? Instruction::FSub
                                    : Instruction::FAdd,
                                EndValue, Step);
-      } else {
-        llvm_unreachable("all possible induction types must be handled");
       }
       Escape->setName("ind.escape");
       MissingVals[UI] = Escape;