James Greenhalgh <james.greenha...@arm.com> writes:
> If the output control string starts with a @samp{@@}, then it is actually
> a series of templates, each on a separate line. (Blank lines and
> leading spaces and tabs are ignored.) The templates correspond to the
> -pattern's constraint alternatives (@pxref{Multi-Alternative}). For example,
> -if a target machine has a two-address add instruction @samp{addr} to add
> -into a register and another @samp{addm} to add a register to memory, you
> -might write this pattern:
> +pattern's constraint alternatives (@pxref{Multi-Alternative}).
> +
> +For example, if a target machine has a two-address add instruction
> +@samp{addreg} to add into a register and another @samp{addmem} to add
> +a register to memory, this pattern could be used to describe the
> +instructions.
>
> @smallexample
> (define_insn "addsi3"
> [(set (match_operand:SI 0 "general_operand" "=r,m")
> (plus:SI (match_operand:SI 1 "general_operand" "0,0")
> - (match_operand:SI 2 "general_operand" "g,r")))]
> + (match_operand:SI 2 "general_operand" "r,r")))]
> ""
> "@@
> - addr %2,%0
> - addm %2,%0")
> + addreg %2,%0
> + addmem %2,%0")
> @end smallexample
While there, I think we should tighten the predicates to
nonimmediate_operand for operands 0 and 1 and -- given the
new constraints -- register_operand for operand 2.
Thanks,
Richard
