[llvm] [SelectionDAG][RISCV] Avoid store merging across function calls (PR #130430)

[Mikhail R. Gadelha via llvm-commits]

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mikhailramalho wrote:

I added the test case to this PR, instead of pushing to main first, since this PR doesn't change the case where scalars are merged

https://github.com/llvm/llvm-project/pull/130430