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Re: [PATCH] Improve cost computations in IVOPTS

From: Eric Botcazou <ebotcazou at adacore dot com>
To: Richard Guenther <richard dot guenther at gmail dot com>
Cc: gcc-patches at gcc dot gnu dot org, Zdenek Dvorak <rakdver at kam dot mff dot cuni dot cz>
Date: Mon, 25 May 2009 13:21:23 +0200
Subject: Re: [PATCH] Improve cost computations in IVOPTS
References: <200905251255.53720.ebotcazou@adacore.com> <84fc9c000905250408t6d2bd42u98297b666b5fe48b@mail.gmail.com>

> There seem to be unrelated changes in the patch, like
>
> -  if (TYPE_PRECISION (utype) != TYPE_PRECISION (ctype))
> +  if (TYPE_PRECISION (utype) < TYPE_PRECISION (ctype))

That's actually a no-op, just before there is:

  if (TYPE_PRECISION (utype) > TYPE_PRECISION (ctype))
    {
      /* We do not have a precision to express the values of use.  */
      return false;
    }

> and
>
> +  STRIP_NOPS (cbase);
> +  ctype = TREE_TYPE (cbase);
>
> are you sure you want to strip sign-changes here?  I am not.
> I would use STRIP_USELESS_TYPE_CONVERSIONS here.

STRIP_NOPS is used throughout the file to compute costs.  And I need this 
additional stripping to expose the "real" ctype.

-- 
Eric Botcazou

References:
- [PATCH] Improve cost computations in IVOPTS
  - From: Eric Botcazou
- Re: [PATCH] Improve cost computations in IVOPTS
  - From: Richard Guenther

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