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Re: [PATCH] Adjust variable shift costs for IA MCU


On Thu, Jul 9, 2015 at 8:05 PM, H.J. Lu <hongjiu.lu@intel.com> wrote:
> We reduce code size for IA MCU by adjusting variable shift costs for IA
> MCU.  OK for trunk?

IMO, tuning patches should fall into "obvious" category. I don't have
any data to to do any meaningful review of a cost metric for a new
target.

So, instead of rubberstamping them again and again, these kind of
patches are pre-approved for all non-algorithmic tuning changes for
IAMCU target.

Uros.

> Thanks.
>
>
> H.J.
> ---
>         PR target/66821
>         * config/i386/i386.c (iamcu_cost): Adjust variable shift costs.
> ---
>  gcc/config/i386/i386.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index 85e59a8..e4e505c 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -420,7 +420,7 @@ static const
>  struct processor_costs iamcu_cost = {
>    COSTS_N_INSNS (1),                   /* cost of an add instruction */
>    COSTS_N_INSNS (1) + 1,               /* cost of a lea instruction */
> -  COSTS_N_INSNS (4),                   /* variable shift costs */
> +  COSTS_N_INSNS (1),                   /* variable shift costs */
>    COSTS_N_INSNS (1),                   /* constant shift costs */
>    {COSTS_N_INSNS (11),                 /* cost of starting multiply for QI */
>     COSTS_N_INSNS (11),                 /*                               HI */
> --
> 2.4.3
>


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