Due MCU name for #ifndef statement?

I can't seem to find this information in any conveniently accessible location, was hoping someone on here could help me out.

I'm updating a program to add support for the Due, and I need to do some be able to tell which MCU I'm compiling for. What is the MCU name for the Sam3 on the Due (ie, for an #ifdef statement looking a Mega2560, i would use "AVR_ATmega2560")? Also, where would I find this information more quickly in the future if I wanted to add support for some other hypothetical future chip?

Thank you!

SAM3X8E

Many thanks! That took care of that issue!!