[clang] [clang] constexpr built-in reduce `or` and `xor` function. (PR #116976)

[Simon Pilgrim via cfe-commits]

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@@ -732,6 +732,10 @@ at the end to the next power of 2.
 
 These reductions support both fixed-sized and scalable vector types.
 
+The reduction intrinsics, including ``__builtin_reduce_add``,
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RKSimon wrote:

"integer reduction intrinsics"?

https://github.com/llvm/llvm-project/pull/116976