[Bug rtl-optimization/64010] [msp430-elf] struct function dereference clobbers parameter passed to function

[pab at pabigot dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64010

--- Comment #6 from Peter A. Bigot <pab at pabigot dot com> ---
The alternative patch (using find_reg_fusage) does fix the problem in my
reproducing test case and in a real application.  Thank you.