This PR fixes an [issue I pointed out in regards to incorrect GEP indices](https://github.com/llvm/llvm-project/pull/149093#discussion_r2748266079) introduced by PR #149093. Changes: - Updated the pointer offset calculation in `VectorCombine::shrinkLoadForShuffles` so that the offset is now multiplied by the element size (`ElemSize`) when computing the new pointer for loads - Updated the GEP indices in `llvm/test/Transforms/VectorCombine/load-shufflevector.ll` for the correct byte offsets