The MACR register is guaranteed to have the same value before and after function calls.

This register is also guaranteed to have the same value before and after interrupts.

However, if the -use_mach=not_use compile option is specified (default state in V1.10 or earlier), the compiler generation code does not useNote or manage the MACR register. To use the MACR register, you must manage it voluntarily within the program.