Fix test_gather

[ESI-SYD]

Make getStackPointer as interface of the TargetInfo to generalize getSharedMemoryBase in gather op.

[chengjunlu]

The major difference of the lowering gather operation is intel::LLVM::getSharedMemoryBase.
We can make the function LLVM::intel::getStackPointer to be a interface of the TargetInfo.

Can we unify the lowering code to the upstream Triton?

[ESI-SYD]

The major difference of the lowering gather operation is intel::LLVM::getSharedMemoryBase. We can make the function LLVM::intel::getStackPointer to be a interface of the TargetInfo.

Can we unify the lowering code to the upstream Triton?

Changed in e100879

[whitneywhtsang]

Please try to upstream these changes.

[chengjunlu]

LGTM now. It worth for us to upstream the reasonable decoupling changes.

We can clean up the redundant lowering code as long as we use the LinearLayout widely. It help us to save the overhead in mergeing changes to downstream.

[ESI-SYD]

Please try to upstream these changes.

triton-lang/triton#5451