[llvm] [AMDGPU] Enable vectorization of i8 values. (PR #134934)

[Gheorghe-Teodor Bercea via llvm-commits]

doru1004 wrote:

> If we are going to have a custom cost model for memory instructions we should probably add a test to test/Analysis/CostModel/AMDGPU

Also added.

https://github.com/llvm/llvm-project/pull/134934