[llvm] [RISCV] Improve performCONCAT_VECTORCombine stride matching (PR #68726)

[Michael Maitland via llvm-commits]

michaelmaitland wrote:

> LGTM. Just leaving a note here that I think we'll fail to detect sequences of pointers that are a mixture of (base + index) and (add LastPtr, constStride), because the latter will be an SDValue and not a int64_t. But it sounds like an unlikely pattern to show up and I doubt its worth the complexity

My guess is that if BaseIndexOffset couldn't resolve to a match, then we would have no way to compare a constant to a non-constant anyway.

https://github.com/llvm/llvm-project/pull/68726