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Re: Bug in loop optimize (invalid postinc to preinc transformation)
- To: davek-ml at ntlworld dot com (Dave Korn)
- Subject: Re: Bug in loop optimize (invalid postinc to preinc transformation)
- From: Tim Hollebeek <tim at hollebeek dot com>
- Date: Fri, 29 Dec 2000 05:11:53 -0500 (EST)
- Cc: tim at hollebeek dot com (Tim Hollebeek), geoffk at geoffk dot org (Geoff Keating), aoliva at redhat dot com (Alexandre Oliva), kenner at vlsi1 dot ultra dot nyu dot edu, gcc at gcc dot gnu dot org (gcc), dewar at gnat dot com (Robert Dewar)
Dave Korn writes ...
>
> ----- Original Message -----
> From: "Tim Hollebeek" <tim@hollebeek.com>
> Sent: Thursday, December 28, 2000 11:42 PM
>
> > If pointers are implementation as unsigned offsets into a flat memory
s/implementation/implemented/
> > model, one of two things is true:
>
> Nope. Pointers are abstract types. The mere fact that the underlying
> implementation uses what are effectively 32 bit unsigned ints (which isn't
> even the case on segmented architectures) isn't relevant.
Read "If ..." as "Assuming ...". So "Nope" isn't really a possible
response. I intentionally restricted my post to an ISO C compiler on
a particular type of architecture and that implements pointers in a
particular way, in an attempt to point out that *even if* pointers are
(essentially) unsigned integers, the standard is written in such a way
that wrapping *still* isn't relevant.
Sorry if that wasn't clear.
(discussion of the abstract semantics deleted; you're preaching to the
choir here)