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

[stefan@franke.ms]

> -----Ursprüngliche Nachricht-----
> Von: gcc-help-owner@gcc.gnu.org <gcc-help-owner@gcc.gnu.org> Im
> Auftrag von William Tambe
> Gesendet: Dienstag, 24. September 2019 18:34
> An: Segher Boessenkool <segher@kernel.crashing.org>
> Cc: gcc-help <gcc-help@gcc.gnu.org>
> Betreff: Re: Help with "unable to generate reloads for" atomic_exchangesi
> 
> On Tue, Sep 24, 2019 at 10:52 AM Segher Boessenkool
> <segher@kernel.crashing.org> 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


I'm also a noob, but I'd try:

(define_insn "atomic_exchangesi"
 [(set (match_operand:SI 0 "register_operand" "=r,r")
       (match_dup 2))
  (set (match_operand:SI 2 "memory_operand" "=B,W")
       (unspec:SI
        [(match_dup 0)
         (match_operand:SI 4 "const_int_operand")]
        0))]
 ""
 "@
  ...
  ...")

And if this still does not work, don't use match_dup, define 5 operands (0..4) and add a condition to force equality of 1==2 and 0==3:

(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" "=B,W")
       (unspec:SI
        [(match_operand:SI 3 "register_operand" "=r,r")
         (match_operand:SI 4 "const_int_operand")]
        0))]
 "operands[0] == operands[3] && operands[1] == operands[2]"
 "@
  ...
  ...")

...
Bebbo