VPVectorPointer for part 0 is just the pointer operand. Simplify it
after unrolling. This removes a large number of redundant GEPs with
index 0.
PR: https://github.com/llvm/llvm-project/pull/149735
This put the onus on the caller to ensure the result type is big enough.
In the unlikely event a cropped result is required then explicitly
truncate a safe value.
Vectorizing of fminimumnum and fminimumnum have not support yet. Let's
add the testcase for it now, and we will update the testcase when we
support it.
