[llvm] [LLVM] Add FP instruction intrinsics (PR #193588)

[Matt Arsenault via llvm-commits]

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@@ -30256,6 +30243,618 @@ Semantics:
 This function returns the same values as the libm ``trunc`` functions
 would and handles error conditions in the same way.
 
+.. _fpintrin:
+
+FP Arithmetic Intrinsics
+------------------------
+
+These intrinsics are call-instruction equivalents of the standard
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arsenm wrote:

This should elaborate more on when they should and should not be used 

https://github.com/llvm/llvm-project/pull/193588