https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97715
--- Comment #5 from qinzhao at gcc dot gnu.org --- (In reply to H.J. Lu from comment #2) > (In reply to qinzhao from comment #1) > > for -fzero-call-used-regs=all, when zeroing st/mm registers under x87 exit > > mode, However, command line option force no 80387 mode, the following insn > > generated to zero st registers is not recognized: > > > > (insn 27 67 28 2 (set (reg:XF 8 st) > > (const_double:XF 0.0 [0x0.0p+0])) "zero-scratch-regs-10.c":8:1 -1 > > (nil)) > > You should avoid zeroing fixed registers. fixed registers should already be excluded from zeroing. are ST registers considered FIXED registers when -mno-80387 is specified?
