Re: [PATCH][ARM] Fix broken shift patterns

[Andrew Stubbs <ams at codesourcery dot com>]

On 06/10/11 16:01, Andrew Stubbs wrote:
>   (define_special_predicate "shift_operator"
>     (and (ior (ior (and (match_code "mult")
>   		      (match_test "power_of_two_operand (XEXP (op, 1), mode)"))
>   		 (and (match_code "rotate")
>   		      (match_test "GET_CODE (XEXP (op, 1)) == CONST_INT
>   				&&  ((unsigned HOST_WIDE_INT) INTVAL (XEXP (op, 1)))<  32")))
> -	    (match_code "ashift,ashiftrt,lshiftrt,rotatert"))
> +	    (and (match_code "ashift,ashiftrt,lshiftrt,rotatert")
> +		 (ior (match_test "GET_CODE (XEXP (op, 1)) == CONST_INT
> +				&&  ((unsigned HOST_WIDE_INT) INTVAL (XEXP (op, 1)))<  32")
> +		      (match_test "REG_P (XEXP (op, 1))"))))
>          (match_test "mode == GET_MODE (op)")))

Oh, I forgot to say, I don't understand why the "rotate" operator is 
special cased?

If I understand it correctly, the effect of the (existing) rotate is 
both to check the constant range, AND to disallow registers as the shift 
amount. This difference has no effect on Thumb, but might cause ARM mode 
some troubles?

Is this likely to be deliberate, or an oversight? I can't see any reason 
in the ARM ARM why this should be the case.

Andrew