https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107172
--- Comment #24 from Uroš Bizjak <ubizjak at gmail dot com> --- (In reply to Hongtao.liu from comment #23) > looking at i386.c put_condition_code used by *setcc_qi, it looks like (EQ > (reg:CCCmode FLAG_REG) (const_int 0)) means get carry flag. > Not (LTU: (REG:CCCmode FLAGS_REG) (const_int 0)). > Now I got more confused. CCCmode means that single flag is tested, it uses EQ and NE, so "c" and "nc" suffix is emitted. When CCmode is used, LTU/GEU operation on CCmode flags reg produces "b" and "nb" suffix, which decodes to exactly the same assembly as "c" and "nc" suffixes. However, it looks that somewhere LTU/GEU is also generated with CCCmode flags reg, and some fixup was introduced to put_condition_code to "fix" this inconsistency. If LTU/GEU is valid only for CCmode, then the producers of invalid RTX should be fixed.
