https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101885
--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
For instructions that inherently set a condition code register, the
@code{compare} operator is always written as the first RTL expression of
the @code{parallel} instruction pattern. For example,
@smallexample
(define_insn ""
[(set (reg:CCZ FLAGS_REG)
(compare:CCZ
(plus:SI
(match_operand:SI 1 "register_operand" "%r")
(match_operand:SI 2 "register_operand" "r"))
(const_int 0)))
(set (match_operand:SI 0 "register_operand" "=r")
(plus:SI (match_dup 1) (match_dup 2)))]
""
"addl %0, %1, %2")
@end smallexample
see the
https://gcc.gnu.org/pipermail/gcc-patches/2017-May/thread.html#474080
thread.
