Can't remove shufflevector if input might be poison #43530

define <4 x float> @insert_not_undef_shuffle_translate_commute(float %x, <4 x float> %y, <4 x float> %q) {
  %xv = insertelement <4 x float> %q, float %x, i32 2
  %r = shufflevector <4 x float> %y, <4 x float> %xv, <4 x i32> { 0, 6, 2, undef }
  ret <4 x float> %r
}
=>
define <4 x float> @insert_not_undef_shuffle_translate_commute(float %x, <4 x float> %y, <4 x float> %q) {
  %r = insertelement <4 x float> %y, float %x, i32 1
  ret <4 x float> %r
}
Transformation doesn't verify!
ERROR: Target is more poisonous than source

Example:
float %x = poison
<4 x float> %y = < poison, poison, poison, poison >
<4 x float> %q = < poison, poison, poison, poison >

Source:
<4 x float> %xv = < poison, poison, poison, poison >
<4 x float> %r = < poison, poison, poison, undef >

Target:
<4 x float> %r = < poison, poison, poison, poison >
Source value: < poison, poison, poison, undef >
Target value: < poison, poison, poison, poison >