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Re: [RFA/ARM] Revert r183011: Cortex-A15 branch costs


On 21/02/12 16:28, Matthew Gretton-Dann wrote:
> The attached patch reverts revision 183011, which changed the branch
> cost heuristics for Cortex-A15.
> 
> This is because further benchmarking shows that there are significant
> regressions on some benchmarks which outweigh other performance gains.
> 
> OK?
> 

OK.

We really need to sort out some of the f/e cost calculations to get this
right... :-(

R.

> Thanks,
> 
> Matt
> 
> gcc/ChangeLog:
> 
> 2012-02-21  Matthew Gretton-Dann  <matthew.gretton-dann@arm.com>
> 
> 	Revert r183011
> 	* config/arm/arm-cores.def (cortex-a15): Use generic Cortex tuning
> 	parameters.
> 	* config/arm/arm.c (arm_cortex_a15_tune): Remove.
> 
> 
> 1-RFA-ARM-Revert-r183011-Cortex-A15-branch-costs.txt
> 
> 
> diff --git a/gcc/config/arm/arm-cores.def b/gcc/config/arm/arm-cores.def
> index b0bd172..80609e0 100644
> --- a/gcc/config/arm/arm-cores.def
> +++ b/gcc/config/arm/arm-cores.def
> @@ -129,7 +129,7 @@ ARM_CORE("cortex-a5",	  cortexa5,	7A,				 FL_LDSCHED, cortex_a5)
>  ARM_CORE("cortex-a7",	  cortexa7,	7A,				 FL_LDSCHED | FL_THUMB_DIV | FL_ARM_DIV, cortex)
>  ARM_CORE("cortex-a8",	  cortexa8,	7A,				 FL_LDSCHED, cortex)
>  ARM_CORE("cortex-a9",	  cortexa9,	7A,				 FL_LDSCHED, cortex_a9)
> -ARM_CORE("cortex-a15",	  cortexa15,	7A,				 FL_LDSCHED | FL_THUMB_DIV | FL_ARM_DIV, cortex_a15)
> +ARM_CORE("cortex-a15",	  cortexa15,	7A,				 FL_LDSCHED | FL_THUMB_DIV | FL_ARM_DIV, cortex)
>  ARM_CORE("cortex-r4",	  cortexr4,	7R,				 FL_LDSCHED, cortex)
>  ARM_CORE("cortex-r4f",	  cortexr4f,	7R,				 FL_LDSCHED, cortex)
>  ARM_CORE("cortex-r5",	  cortexr5,	7R,				 FL_LDSCHED | FL_ARM_DIV, cortex)
> diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
> index 4a94145..3ef3d19 100644
> --- a/gcc/config/arm/arm.c
> +++ b/gcc/config/arm/arm.c
> @@ -968,17 +968,6 @@ const struct tune_params arm_cortex_a9_tune =
>    arm_default_branch_cost
>  };
>  
> -const struct tune_params arm_cortex_a15_tune =
> -{
> -  arm_9e_rtx_costs,
> -  NULL,
> -  1,						/* Constant limit.  */
> -  1,						/* Max cond insns.  */
> -  ARM_PREFETCH_NOT_BENEFICIAL,			/* TODO: Calculate correct values.  */
> -  false,					/* Prefer constant pool.  */
> -  arm_cortex_a5_branch_cost
> -};
> -
>  const struct tune_params arm_fa726te_tune =
>  {
>    arm_9e_rtx_costs,



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