[clang] let Neon builtin function accept a const variable (PR #144625)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

I think something like your patch solves the original testcase from #139033.  (Actually, it crashes in codegen, but that's an easy fix.)  And I thought you wanted specifically that...?

Your new testcase will never work; the NEON intrinsic is specifically specified to only allow operands which produce an immediate encoding.  For a shift with a variable amount, you want something like `vshlq_s64(a.vect_s64, vdupq_n_s64(mc));`.

https://github.com/llvm/llvm-project/pull/144625