[llvm] RuntimeLibcalls: Add function signatures to RTLIB. (PR #226264)

[Matt Arsenault via llvm-commits]

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@@ -462,6 +503,37 @@ RuntimeLibcallsInfo::getFunctionTy(LLVMContext &Ctx, const Triple &TT,
     return {FunctionType::get(Type::getVoidTy(Ctx), ArgTys, false), Attrs};
   }
   default:
+    // Get C-type function signature of the Libcall if provided,
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arsenm wrote:

Move this to a dedicated function? 

https://github.com/llvm/llvm-project/pull/226264