[clang] [CIR][AArch64] Implement vqshrun_n NEON builtin (PR #195080)

[Jiahao Guo via cfe-commits]

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E00N777 wrote:

Thanks for your contribution!

- However, I only see three intrinsics in the linked documentation:
https://arm-software.github.io/acle/neon_intrinsics/advsimd.html#vector-saturating-shift-right-and-narrow
Could you please add tests for the others?

- Also, all these migrated tests should be deleted from the original test file.

https://github.com/llvm/llvm-project/pull/195080