+/* Potential ways that a function can return a value of a given type. */
+enum return_value_convention
+{
+ /* Where the return value has been squeezed into one or more
+ registers. */
+ RETURN_VALUE_REGISTER_CONVENTION,
+ /* Commonly known as the "struct return convention". The caller
+ passes an additional hidden first parameter to the caller. That
+ parameter contains the address at which the value being returned
+ should be stored. While typically, and historically, used for
+ large structs, this is convention is applied to values of many
+ different types. */
+ RETURN_VALUE_STRUCT_CONVENTION,
+ /* Like the "struct return convention" above, but where the ABI
+ guarantees that the called function stores the address at which
+ the value being returned is stored in a well-defined location,
+ such as a register or memory slot in the stack frame. Don't use
+ this if the ABI doesn't explicitly guarantees this. */
+ RETURN_VALUE_ABI_RETURNS_ADDRESS,
+ /* Like the "struct return convention" above, but where the ABI
+ guarantees that the address at which the value being returned is
+ stored will be available in a well-defined location, such as a
+ register or memory slot in the stack frame. Don't use this if
+ the ABI doesn't explicitly guarantees this. */
+ RETURN_VALUE_ABI_PRESERVES_ADDRESS,
+};
+