[llvm] [DAG] Add funnel-shift matchers to SDPatternMatch (Fixes #185880) (PR #186593)

[Vedant Neve via llvm-commits]

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0bVdnt wrote:

`matchShiftOr` calls `m_ConstInt`, but the overload is declared later in the header. Defining matchShiftOr inline at that earlier point caused a lookup-order issue, so I kept it out-of-line after the m_ConstInt declarations. If you prefer the inline form, I can add a forward declaration for the required m_ConstInt overload and switch to that.

https://github.com/llvm/llvm-project/pull/186593