Assumption that "VectorizedValue" will always be an Instruction is not correct.

Assumption that "VectorizedValue" will always be an Instruction is not correct.
It can be a constant or a vector argument.

ex :

define i32 @hadd(<4 x i32> %a) #0 {
entry:
  %vecext = extractelement <4 x i32> %a, i32 0
  %vecext1 = extractelement <4 x i32> %a, i32 1
  %add = add i32 %vecext, %vecext1
  %vecext2 = extractelement <4 x i32> %a, i32 2
  %add3 = add i32 %add, %vecext2
  %vecext4 = extractelement <4 x i32> %a, i32 3
  %add5 = add i32 %add3, %vecext4
  ret i32 %add5
}

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225517 91177308-0d34-0410-b5e6-96231b3b80d8