Help with "unable to generate reloads for" atomic_exchangesi

[Segher Boessenkool]

On Tue, Sep 24, 2019 at 11:33:56AM -0500, William Tambe wrote:
> On Tue, Sep 24, 2019 at 10:52 AM Segher Boessenkool
> <segher@kernel.crashing.org> wrote:
> > 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.

Yeah.  So do a define_expand for atomic_exchangesi that has only the four
operands, and which expands to your actual machine pattern, which then is
a separate define_insn?


Segher