On 24/03/14 17:21, Kyrill Tkachov wrote:
> Hi all,
>
> I noticed that we don't handle simple reg-to-reg arithmetic operations in the
> arm rtx cost functions. We should be adding the cost of alu.arith to the
> costs
> of the operands. This patch does that. Since we don't have any cost tables
> yet
> that have a non-zero value for that field it shouldn't affect code-gen for
> any
> current cores.
>
> Bootstrapped and tested on arm-none-linux-gnueabihf.
>
> Ok for next stage1?
>
> Thanks,
> Kyrill
>
> 2014-03-24 Kyrylo Tkachov <kyrylo.tkac...@arm.com>
>
> * config/arm/arm.c (arm_new_rtx_costs): Handle reg-to-reg PLUS
> and MINUS RTXs.
>
I think the convention for big switch statements like this is to write
* config/arm/arm.c (arm_new_rtx_costs, case PLUS, MINUS): ....
However...
>
> rtx-costs-plus-minus.patch
>
>
> diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
> index bf5d1b2..3102b67 100644
> --- a/gcc/config/arm/arm.c
> +++ b/gcc/config/arm/arm.c
> @@ -9428,6 +9428,14 @@ arm_new_rtx_costs (rtx x, enum rtx_code code, enum
> rtx_code outer_code,
> *cost += rtx_cost (XEXP (x, 1), code, 1, speed_p);
> return true;
> }
> + else if (REG_P (XEXP (x, 0)))
> + {
> + *cost += rtx_cost (XEXP (x, 0), code, 0, speed_p)
> + + rtx_cost (XEXP (x, 1), code, 1, speed_p);
> + if (speed_p)
> + *cost += extra_cost->alu.arith;
> + return true;
> + }
>
This still doesn't handle the case where the first operand is not a
register. Furthermore, the only difference between this and what we had
before is that we now add alu.arith to the overall cost. But we want to
do that anyway.
I think you really just need
else if (speed_p)
*cost += extra_cost.alu_arith;
and then let recursion (return false) handle the cost of non-register
operands (register will always cost as zero).
> return false;
> }
> @@ -9663,6 +9671,14 @@ arm_new_rtx_costs (rtx x, enum rtx_code code, enum
> rtx_code outer_code,
> *cost += rtx_cost (XEXP (x, 0), PLUS, 0, speed_p);
> return true;
> }
> + else if (REG_P (XEXP (x, 1)))
> + {
> + *cost += rtx_cost (XEXP (x, 0), PLUS, 0, speed_p)
> + + rtx_cost (XEXP (x, 1), PLUS, 1, speed_p);
> + if (speed_p)
> + *cost += extra_cost->alu.arith;
> + return true;
> + }
The same here.
> return false;
> }
>
>
R.
