[llvm] SelectionDAG store merging default implementations are unreasonable #90714 (PR #131424)

[Devesh Yadav via llvm-commits]

Devesh-Yadav10 wrote:

> Though from a very cursory look, I doubt this makes sense. This predicate just checks whether store merging is attempted at all, there are more checks (isTypeLegal, canMergeStoresTo, allowsMemoryAccess) before actually doing the merge. Possibly your target is not handling some of these correctly?

I see your point about additional checks. My concern was that the default implementation allows merging too aggressively, leading to infinite loops when stores are decomposed. Do you think making canMergeStoresTo more conservative would be a better approach?

https://github.com/llvm/llvm-project/pull/131424