https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59533
--- Comment #7 from Oleg Endo <olegendo at gcc dot gnu.org> ---
If a shll is followed by a cbranch:
unsigned int
test_09_0 (int x, unsigned int y, unsigned int z)
{
return ~(x >> 31) ? y : z;
}
shll r4
bf .L4
mov r6,r5
.L4:
rts
mov r5,r0
it's better to use cmp/pz and invert the branch condition.
Combine is looking for the following pattern:
Failed to match this instruction:
(set (pc)
(if_then_else (ge (reg:SI 4 r4 [ x ])
(const_int 0 [0]))
(label_ref:SI 17)
(pc)))
One option could be adding a pattern like:
(define_insn_and_split "*cbranch"
[(set (pc)
(if_then_else (match_operand 0 "treg_set_expr")
(label_ref (match_operand 1))
(pc)))
(clobber (reg:SI T_REG))]
