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Re: Preserve pointer types in ivopts

From: Bernd Schmidt <bernds at codesourcery dot com>
To: Zdenek Dvorak <rakdver at iuuk dot mff dot cuni dot cz>
Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>
Date: Fri, 16 Mar 2012 00:03:08 +0100
Subject: Re: Preserve pointer types in ivopts
References: <4F624077.8040103@codesourcery.com> <20120315221206.GA11714@kam.mff.cuni.cz>

On 03/15/2012 11:12 PM, Zdenek Dvorak wrote:

> the reason unsigned integer types are prefered is that possible overflows
> during the computation have defined semantics.  With pointer types, the
> intermediate steps of the computations could have undefined behavior, possibly
> confusing further optimizations.  Is the patch with this regard?

It's trying to use sizetype for pointer offset computations. As far as I
can tell that's supposed to be an unsigned type, so it should be OK. I
think the final POINTER_PLUS_EXPRs we make can't overflow in valid programs.

Bernd

Follow-Ups:
- Re: Preserve pointer types in ivopts
  - From: Jakub Jelinek

References:
- Preserve pointer types in ivopts
  - From: Bernd Schmidt
- Re: Preserve pointer types in ivopts
  - From: Zdenek Dvorak

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