[Bug tree-optimization/58195] Missed optimization opportunity when returning a conditional

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58195

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
For aarch64 we could also solve this at the rtl level by simplifying:
(if_then_else:SI (ne (reg:SI 108 [ inputD.4415 ])
            (const_int 0 [0]))
        (neg:SI (reg:SI 108 [ inputD.4415 ]))
        (const_int 0 [0]))

into:
(neg:SI (reg:SI 108 [ inputD.4415 ]))


Trying 2, 38 -> 17:
    2: r104:SI=r108:SI
      REG_DEAD r108:SI
   38: cc:CC=cmp(r104:SI,0)
   17: x0:SI={(cc:CC!=0)?-r104:SI:0}
      REG_DEAD cc:CC
      REG_DEAD r104:SI
Failed to match this instruction:
(set (reg/i:SI 0 x0)
    (if_then_else:SI (ne (reg:SI 108 [ inputD.4415 ])
            (const_int 0 [0]))
        (neg:SI (reg:SI 108 [ inputD.4415 ]))
        (const_int 0 [0])))

I am going to implement that first and then implement the phiopt change.