For the Renesas Super-H processor, GDB provides these commands:
set sh calling-convention convention
Set the calling-convention used when calling functions from GDB. Allowed values are ‘gcc’, which is the default setting, and ‘renesas’. With the ‘gcc’ setting, functions are called using the GCC calling convention. If the DWARF-2 information of the called function specifies that the function follows the Renesas calling convention, the function is called using the Renesas calling convention. If the calling convention is set to ‘renesas’, the Renesas calling convention is always used, regardless of the DWARF-2 information. This can be used to override the default of ‘gcc’ if debug information is missing, or the compiler does not emit the DWARF-2 calling convention entry for a function.
show sh calling-convention
Show the current calling convention setting.