[llvm] [AMDGPU] llvm.prefetch documentation for gfx1250. NFC (PR #157949)

[Shilei Tian via llvm-commits]

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@@ -1455,7 +1455,6 @@ The AMDGPU backend implements the following LLVM IR intrinsics.
                                                    Returns a pair for the swapped registers. The first element of the return corresponds
                                                    to the swapped element of the first argument.
 
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shiltian wrote:

hmm, why was this line removed?

https://github.com/llvm/llvm-project/pull/157949