Re: How to write shift and add pattern?

[Mohamed Shafi <shafitvm@gmail.com>]

2009/11/6 Richard Henderson <rth@redhat.com>:
> On 11/06/2009 05:29 AM, Mohamed Shafi wrote:
>>
>>     The target that i am working on has 1&  2 bit shift-add patterns.
>> GCC is not generating shift-add patterns when the shift count is 1. It
>> is currently generating add operations. What should be done to
>> generate shift-add pattern instead of add-add pattern?
>
> I'm not sure.  You may have to resort to matching
>
>  (set (match_operand 0 "register_operand" "")
>       (plus (plus (match_operand 1 "register_operand" "")
>                   (match_dup 1))
>             (match_operand 2 "register_operand" ""))))
>
> But you should debug make_compound_operation first to
> figure out what's going on for your port, because it's
> working for x86_64:
>
>        long foo(long a, long b) { return a*2 + b; }
>
>        leaq    (%rsi,%rdi,2), %rax     # 8     *lea_2_rex64
>        ret                             # 26    return_internal
>
>
> r~
>

   I have fixed this. The culprit was the cost factor. I added the
case in targetm.rtx_costs and now it works properly. But i am having
issues with the reload.

Regards,
Shafi