[clang] [Clang] Add __builtin_vectorelements to get number of elements in vector (PR #69010)

[Lawrence Benson via cfe-commits]

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+// RUN: %clang_cc1 -O1 -triple aarch64 -target-feature +neon %s -emit-llvm -o - | FileCheck --check-prefixes=CHECK,NEON %s
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lawben wrote:

Done.

https://github.com/llvm/llvm-project/pull/69010