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RE: [PATCH 3/4][AArch64] Add CCMP to rtx costs


ping

> -----Original Message-----
> From: Wilco Dijkstra [mailto:Wilco.Dijkstra@arm.com]
> Sent: 13 November 2015 16:03
> To: 'gcc-patches@gcc.gnu.org'
> Subject: [PATCH 3/4][AArch64] Add CCMP to rtx costs
> 
> This patch adds support for rtx costing of CCMP. The cost is the same as int/FP compare, however comparisons with zero get a slightly
> larger cost. This means we prefer emitting compares with zero so they can be merged with ALU operations.
> 
> OK for commit?
> 
> ChangeLog:
> 2015-11-13  Wilco Dijkstra  <wdijkstr@arm.com>
> 
> 	* gcc/config/aarch64/aarch64.c (aarch64_if_then_else_costs):
> 	Add support for CCMP costing.
> 
> ---
>  gcc/config/aarch64/aarch64.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
> index a224982..b789841 100644
> --- a/gcc/config/aarch64/aarch64.c
> +++ b/gcc/config/aarch64/aarch64.c
> @@ -5638,6 +5638,26 @@ aarch64_if_then_else_costs (rtx op0, rtx op1, rtx op2, int *cost, bool speed)
>      }
>    else if (GET_MODE_CLASS (GET_MODE (inner)) == MODE_CC)
>      {
> +      /* CCMP.  */
> +      if ((GET_CODE (op1) == COMPARE) && CONST_INT_P (op2))
> +	{
> +	  /* Increase cost of CCMP reg, 0, imm, CC to prefer CMP reg, 0.  */
> +	  if (XEXP (op1, 1) == const0_rtx)
> +	    *cost += 1;
> +	  if (speed)
> +	    {
> +	      machine_mode mode = GET_MODE (XEXP (op1, 0));
> +	      const struct cpu_cost_table *extra_cost
> +		= aarch64_tune_params.insn_extra_cost;
> +
> +	      if (GET_MODE_CLASS (mode) == MODE_INT)
> +		*cost += extra_cost->alu.arith;
> +	      else
> +		*cost += extra_cost->fp[mode == DFmode].compare;
> +	    }
> +	  return true;
> +	}
> +
>        /* It's a conditional operation based on the status flags,
>  	 so it must be some flavor of CSEL.  */
> 
> --
> 1.9.1


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