Re: Help with "unable to generate reloads for" atomic_exchangesi

[William Tambe <tambewilliam@xxxxxxxxx>]

On Tue, Sep 24, 2019 at 10:52 AM Segher Boessenkool
<segher@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Tue, Sep 24, 2019 at 04:31:49AM -0500, William Tambe wrote:
> > I have defined atomic_exchangesi as follow in the machine description:
> >
> > (define_insn "atomic_exchangesi"
> >  [(set (match_operand:SI 0 "register_operand" "=r,r")
> >        (match_operand:SI 1 "memory_operand" "+B,W"))
> >   (set (match_dup 1)
> >        (unspec:SI
> >         [(match_operand:SI 2 "register_operand" "0,0")
> >          (match_operand:SI 3 "const_int_operand")]
> >         0))]
> >  ""
> >  "@
> >   ...
> >   ...")
>
> Don't use "+", just use matching constraints, like the "0" you already
> have, but then "1"?  Like
>
> (define_insn "atomic_exchangesi"
>  [(set (match_operand:SI 0 "register_operand" "=r,r")
>        (match_operand:SI 1 "memory_operand" "B,W"))
>   (set (match_operand:SI 2 "memory_operand" "=1,1")
>        (unspec:SI
>         [(match_operand:SI 3 "register_operand" "0,0")
>          (match_operand:SI 4 "const_int_operand")]
>         0))]
>
Per https://gcc.gnu.org/onlinedocs/gccint/Standard-Names.html ,
atomic_exchangesi only has 4 operands instead of 5 operands as it is
the case in your example.

I did try the following, but I get "repeated operand number 1"

(define_insn "atomic_exchangesi"
 [(set (match_operand:SI 0 "register_operand" "=r,r")
       (match_operand:SI 1 "memory_operand" "B,W"))
  (set (match_operand:SI 1 "memory_operand" "=1,1")
       (unspec:SI
        [(match_operand:SI 2 "register_operand" "0,0")
         (match_operand:SI 3 "const_int_operand")]
        0))]
 ""
 "@
  ...
  ...")

Any other suggestions that I could try ?

>
> Segher