Vector permutation support for x86

[Richard Henderson]

> -;; Note the instruction does not allow the value being added to be a memory
> -;; operation.  However by pretending via the nonimmediate_operand predicate
> -;; that it does and splitting it later allows the following to be recognized:
> -;;	a[i] = b[i] * c[i] + d[i];
>  (define_insn "xop_pmacsww"
>    [(set (match_operand:V8HI 0 "register_operand" "=x")
>          (plus:V8HI
>  	 (mult:V8HI
> -	  (match_operand:V8HI 1 "register_operand" "%x")
> +	  (match_operand:V8HI 1 "nonimmediate_operand" "%x")
>  	  (match_operand:V8HI 2 "nonimmediate_operand" "xm"))
> -	 (match_operand:V8HI 3 "register_operand" "x")))]
> +	 (match_operand:V8HI 3 "nonimmediate_operand" "x")))]

I think the comment is still valuable, minus the subclause about 
splitting.  Because otherwise I would question the use of 
nonimmediate_operand in op3.

However, I do not believe that the same applies to any of the
non-multiply-add patterns.  E.g.

>  (define_insn "xop_pperm"
>    [(set (match_operand:V16QI 0 "register_operand" "=x,x")
>  	(unspec:V16QI
> -	  [(match_operand:V16QI 1 "register_operand" "x,x")
> +	  [(match_operand:V16QI 1 "nonimmediate_operand" "x,x")

There's really no reason to accept a memory operand here, AFAICS.
Similarly with all of the patterns that follow.


r~