When using the "interrupt_save_fp" function attribute, which includes floating point status registers among the register context that is saved and restored, a debug line is generated that thwarts the assembler.

epwm_register_write.s:329:9: error: invalid register in register list
.save {fpscr, fpexc}

This happens when -save-temps is used, where the compiler will dump a generated assembly file and then assemble that file.  

-S can also be used to dump the generated assembly, though this is not compiled.