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Date: Wed, 18 May 2011 10:10:00 -0000
From: Zdenek Dvorak <rakdver@kam.mff.cuni.cz>
To: Tom de Vries <vries@codesourcery.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH, PR45098, 3/10]
Message-ID: <20110518072620.GA18720@kam.mff.cuni.cz>
References: <4DD21F6E.4050308@codesourcery.com> <4DD220C1.7000405@codesourcery.com>
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Hi,

> 2011-05-05  Tom de Vries  <tom@codesourcery.com>
> 
> 	PR target/45098
> 	* tree-ssa-loop-ivopts.c (computation_cost): Prevent cost of 0.

this looks strange.  Something like

  cost = seq_cost (seq, speed);
  if (MEM_P (rslt))
    the current code;
  else
    cost += rtx_cost (rslt, SET, speed));

would make more sense to me (if I understand correctly what you are
trying to achieve).

Zdenek

> Index: gcc/tree-ssa-loop-ivopts.c
> ===================================================================
> --- gcc/tree-ssa-loop-ivopts.c	(revision 173380)
> +++ gcc/tree-ssa-loop-ivopts.c	(working copy)
> @@ -2862,7 +2862,9 @@ computation_cost (tree expr, bool speed)
>    default_rtl_profile ();
>    node->frequency = real_frequency;
>  
> -  cost = seq_cost (seq, speed);
> +  cost = (seq != NULL_RTX
> +          ? seq_cost (seq, speed)
> +          : (unsigned)rtx_cost (rslt, SET, speed));
>    if (MEM_P (rslt))
>      cost += address_cost (XEXP (rslt, 0), TYPE_MODE (type),
>  			  TYPE_ADDR_SPACE (type), speed);