Re: [PR68432 01/22][ARM] Remove operand dependency from "type" attribute

[Bernd Schmidt <bschmidt at redhat dot com>]

On 11/25/2015 01:21 PM, Richard Sandiford wrote:
> -	  (plus:SI (match_operand:SI 0 "s_register_operand" "l,  r")
> -		   (match_operand:SI 1 "arm_add_operand"    "lPv,rIL"))
> +	  (plus:SI (match_operand:SI 0 "s_register_operand" "l,l, r,r")
> +		   (match_operand:SI 1 "arm_add_operand"    "l,Pv,r,IL"))

I'll leave it to ARM maintainers to approve or reject, but I want to 
point out one thing: IMO this sort of thing is better written as 
"l,lPv,r,rIL", allowing a larger set of inputs for the later 
alternatives while still returning the more specific earlier one if it 
matches. I don't know whether LRA takes advantage of that, but it could 
help reload, and any post-reload pass might look at the current 
alternative for a given insn to see whether it can be replaced by a 
register.


Bernd