[llvm] [LLVM] Move libcall <-> intrinsic association into libcall tablegen (PR #204029)

[Matt Arsenault via llvm-commits]

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@@ -117,6 +122,19 @@ struct RuntimeLibcallsInfo {
     return ImplToLibcall[Impl];
   }
 
+  /// Return the runtime libcall that the floating-point math intrinsic \p ID
+  /// operating on type \p Ty may be lowered to, or RTLIB::UNKNOWN_LIBCALL if
+  /// there is no such mapping.
+  ///
+  /// \p Ty must be the floating-point operand type, which is not always the
+  /// intrinsic's primary/overloaded type. E.g. lround/llround/lrint/llrint are
+  /// overloaded on the integer result, powi on the integer exponent, and
+  /// frexp/modf/sincos return an aggregate. For these, pass the floating-point
+  /// argument type (e.g. the type of operand 0), not the intrinsic's return
+  /// type.
+  LLVM_ABI static RTLIB::Libcall getLibcallForIntrinsic(Intrinsic::ID ID,
+                                                        Type *Ty);
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arsenm wrote:

This should take the complete FunctionType for the call signature 

https://github.com/llvm/llvm-project/pull/204029