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To: Peter Bergner <bergner@vnet.ibm.com>
Mail-Followup-To: Peter Bergner <bergner@vnet.ibm.com>,gcc-patches@gcc.gnu.org, rsandifo@nildram.co.uk
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] PR35371 GCSE loses track of REG_POINTER attribute
References: <20080225222624.GA26857@vervain.rchland.ibm.com>
From: Richard Sandiford <rsandifo@nildram.co.uk>
Date: Tue, 26 Feb 2008 18:00:00 -0000
In-Reply-To: <20080225222624.GA26857@vervain.rchland.ibm.com> (Peter Bergner's message of "Mon\, 25 Feb 2008 16\:26\:24 -0600")
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Peter Bergner <bergner@vnet.ibm.com> writes:
> Index: gcse.c
> ===================================================================
> --- gcse.c	(revision 132568)
> +++ gcse.c	(working copy)
> @@ -818,6 +818,24 @@ gcse_main (rtx f ATTRIBUTE_UNUSED)
>  
>  /* Misc. utilities.  */
>  
> +/* Create a pseudo reg to copy the result of a reaching expression into.
> +   Be careful to inherit the REG_POINTER attribute.  */
> +
> +static rtx
> +gen_reaching_reg_rtx (rtx x)
> +{
> +  rtx reg;
> +
> +  gcc_assert (REG_P (x));
> +
> +  reg = gen_reg_rtx (GET_MODE (x));
> +
> +  if (REG_POINTER (x))
> +    mark_reg_pointer (reg, REGNO_POINTER_ALIGN (REGNO (x)));
> +
> +  return reg;
> +}
> +

Minor suggestion, but maybe this could go in emit-rtl.c, under a more
generic name?  Given the performance impact of losing pointer info,
it would be nice to have a defined API for creating a register that's
like another.

Richard