Hi Suwa-san, On Thu, Sep 11, 2025 at 1:48 PM Takayuki 'January June' Suwa <jjsuwa_sys3...@yahoo.co.jp> wrote: > > If the Floating-Point Coprocessor option is configured and there are no > floating-point coprocessor instructions in the function, the unused > floating-point registers (f0 thru f15) can be good targets for spilling > address (integer) registers. > > For reference, the ISA manual says that [RW]FR machine instructions have > non-arithmetic behavior and do not raise floating-point exceptions.
They don't raise floating-point exceptions, but they would still raise the "coprocessor disabled" exception if the FP coprocessor is disabled. Also all the conditions that you mentioned may be satisfied in the linux kernel code, yet it shouldn't clobber the FP registers. -- Thanks. -- Max
