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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Alan Modra <amodra@gmail.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH 3/8] [RS6000] rs6000_rtx_costs tidy AND
Date: Mon, 25 Jan 2021 16:37:21 -0600	[thread overview]
Message-ID: <20210125223721.GA30983@gate.crashing.org> (raw)
In-Reply-To: <20201007225800.9536-4-amodra@gmail.com>

Hi!

On Thu, Oct 08, 2020 at 09:27:55AM +1030, Alan Modra wrote:
> 	* config/rs6000/rs6000.c (rs6000_rtx_costs): Tidy AND code.
> 	Don't avoid recursion on const_int shift count.
> 
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index e870ba0039a..bc5e51aa5ce 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -21253,6 +21253,7 @@ static bool
>  rs6000_rtx_costs (rtx x, machine_mode mode, int outer_code,
>  		  int opno ATTRIBUTE_UNUSED, int *total, bool speed)
>  {
> +  rtx right;

Please declare things where you first use them.

>    int code = GET_CODE (x);
>  
>    switch (code)
> @@ -21430,7 +21431,9 @@ rs6000_rtx_costs (rtx x, machine_mode mode, int outer_code,
>        return false;
>  
>      case AND:
> -      if (CONST_INT_P (XEXP (x, 1)))
> +      *total = COSTS_N_INSNS (1);
> +      right = XEXP (x, 1);
> +      if (CONST_INT_P (right))
>  	{
>  	  rtx left = XEXP (x, 0);
>  	  rtx_code left_code = GET_CODE (left);
> @@ -21439,17 +21442,13 @@ rs6000_rtx_costs (rtx x, machine_mode mode, int outer_code,
>  	  if ((left_code == ROTATE
>  	       || left_code == ASHIFT
>  	       || left_code == LSHIFTRT)
> -	      && rs6000_is_valid_shift_mask (XEXP (x, 1), left, mode))
> +	      && rs6000_is_valid_shift_mask (right, left, mode))

You could have left all this intact, it is just distraction from the
rest of the patch (nothing changed here).  Except you set *total.

>  	    {
> -	      *total = rtx_cost (XEXP (left, 0), mode, left_code, 0, speed);
> -	      if (!CONST_INT_P (XEXP (left, 1)))
> -		*total += rtx_cost (XEXP (left, 1), SImode, left_code, 1, speed);
> -	      *total += COSTS_N_INSNS (1);
> +	      *total += rtx_cost (XEXP (left, 0), mode, left_code, 0, speed);
> +	      *total += rtx_cost (XEXP (left, 1), SImode, left_code, 1, speed);
>  	      return true;
>  	    }
>  	}
> -
> -      *total = COSTS_N_INSNS (1);
>        return false;

I still do not see what this improves, I only see possible obvious
regressions :-(


Segher

  parent reply	other threads:[~2021-01-25 22:38 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-07 22:57 [PATCH 0/8] [RS6000] rs6000_rtx_costs V2 Alan Modra
2020-10-07 22:57 ` [PATCH 1/8] [RS6000] rs6000_rtx_costs comment Alan Modra
2020-10-14 20:08   ` Segher Boessenkool
2020-10-07 22:57 ` [PATCH 2/8] [RS6000] rs6000_rtx_costs for AND Alan Modra
2020-10-20 18:55   ` Segher Boessenkool
2020-10-21  2:57     ` Alan Modra
2020-10-21 20:29       ` Segher Boessenkool
2020-10-21 22:11         ` Alan Modra
2020-10-22 13:29           ` Segher Boessenkool
2020-10-23 23:18           ` Hans-Peter Nilsson
2020-10-24  1:04             ` Alan Modra
2020-10-07 22:57 ` [PATCH 3/8] [RS6000] rs6000_rtx_costs tidy AND Alan Modra
     [not found]   ` <20210112033157.GA26219@bubble.grove.modra.org>
2021-01-21 23:09     ` Alan Modra
2021-01-25 22:37   ` Segher Boessenkool [this message]
2021-02-01  2:06     ` Alan Modra
2020-10-07 22:57 ` [PATCH 4/8] [RS6000] rs6000_rtx_costs tidy break/return Alan Modra
     [not found]   ` <20210112033209.GB26219@bubble.grove.modra.org>
2021-01-21 23:09     ` Alan Modra
2021-01-25 22:40   ` Segher Boessenkool
2020-10-07 22:57 ` [PATCH 5/8] [RS6000] rs6000_rtx_costs cost IOR Alan Modra
     [not found]   ` <20210112033218.GC26219@bubble.grove.modra.org>
2021-01-21 23:10     ` Alan Modra
2021-01-25 22:51   ` Segher Boessenkool
2021-02-01  2:13     ` Alan Modra
2020-10-07 22:57 ` [PATCH 6/8] [RS6000] rs6000_rtx_costs multi-insn constants Alan Modra
2020-10-07 22:57 ` [PATCH 7/8] [RS6000] rs6000_rtx_costs reduce cost for SETs Alan Modra
2020-10-08 18:19   ` will schmidt
     [not found]   ` <20210112033227.GD26219@bubble.grove.modra.org>
2021-01-21 23:10     ` Alan Modra
2020-10-07 22:58 ` [PATCH 8/8] [RS6000] rs6000_rtx_costs for !speed Alan Modra
     [not found]   ` <20210112033236.GE26219@bubble.grove.modra.org>
2021-01-21 23:11     ` Alan Modra
2020-12-05  9:12 ` [PATCH 0/8] [RS6000] rs6000_rtx_costs V2 Alan Modra
2021-01-11 21:42   ` Alan Modra

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