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

[Matt Arsenault via llvm-commits]

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@@ -56,6 +56,35 @@ def SMEABI_PreserveMost_From_X0 : LibcallCallingConv<[{CallingConv::AArch64_SME_
 def SMEABI_PreserveMost_From_X1 : LibcallCallingConv<[{CallingConv::AArch64_SME_ABI_Support_Routines_PreserveMost_From_X1}]>;
 def SMEABI_PreserveMost_From_X2 : LibcallCallingConv<[{CallingConv::AArch64_SME_ABI_Support_Routines_PreserveMost_From_X2}]>;
 
+
+// Return type or argument type of library calls.
+class FuncArgType {
+  string Name = NAME;
+}
+
+// Recognized types of library call arguments and return types.
+def NoneType : FuncArgType; // dummy
+def Void : FuncArgType;
+def Bool : FuncArgType;     // 8 bits on all targets
+def Int16 : FuncArgType;
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arsenm wrote:

We do want to be able to distinguish signed and unsigned arguments. A number of places are hardcoding which operations are signed and it's often buggy 

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