[llvm] [X86] Fix `FastISel` crash on `GEP` with a constant index wider than `64` bits (PR #223432)

[Akash Manna via llvm-commits]

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akash-manna-sky wrote:

I think no. That path is gated by `canFoldAddIntoGEP`, which only matches an add whose type is the same width as the pointer, so the constant is at most 64 bits.

https://github.com/llvm/llvm-project/pull/223432