[clang] [llvm] [InstCombine] Combine llvm.sin/llvm.cos libcall pairs into llvm.sincos (PR #184760)

[Kito Cheng via cfe-commits]

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kito-cheng wrote:

One issue here we can't put fpmath metadata to sincos, because it return a struct, and verifier will complain that, so I put that on extractvector side for now, but I am not sure if it's best solution.

https://github.com/llvm/llvm-project/pull/184760