https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92180
--- Comment #4 from Segher Boessenkool <segher at gcc dot gnu.org> --- For x86 it may be because targetm.class_likely_spilled_p is true for ax, and then indeed cant_combine_insn_p is true. See r53531, the mail thread for that patch starts at https://gcc.gnu.org/ml/gcc-patches/2002-05/msg01216.html .
