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Re: BITS_PER_UNIT larger than 8 -- word addressing
- From: Michael Eager <eager at eagercon dot com>
- To: Michael Eager <eager at eagercon dot com>
- Cc: "Joseph S. Myers" <joseph at codesourcery dot com>, Ross Ridge <rridge at csclub dot uwaterloo dot ca>, GCC <gcc at gcc dot gnu dot org>
- Date: Fri, 30 Nov 2007 16:56:41 -0800
- Subject: Re: BITS_PER_UNIT larger than 8 -- word addressing
- References: <20071127034635.ABBD773D73@caffeine.csclub.uwaterloo.ca> <474BC7B7.30400@eagercon.com> <Pine.LNX.4.64.0711271523030.10881@digraph.polyomino.org.uk> <474C5B13.201@eagercon.com> <Pine.LNX.4.64.0711271808591.12573@digraph.polyomino.org.uk> <474C61FB.1070903@eagercon.com>
Michael Eager wrote:
Joseph S. Myers wrote:
On Tue, 27 Nov 2007, Michael Eager wrote:
I think that there is a pervasive understanding that SImode is
single precision integer, 32-bits long.
Only among contributors not considering non-8-bit bytes. SImode is 4
times QImode, 4*BITS_PER_UNIT bits, and may not exist (or at least not
be particularly usable, much like the limitations on TImode on 32-bit
targets) with large BITS_PER_UNIT.
I think you just described the majority of contributors. :-)
It may be that my current problem is limited to unwind-dw2.c.
If so, then I may be able to work around it by simply not building it.
There's also __mode__ (__SI__) in include/sys/types.h
where it's used to define _ST_INT32. The comments are
interesting: This is meant to insure that the stat
struct layout doesn't change when sizeof(int) changes,
but forgets that SI not always 32 bits.
--
Michael Eager eager@eagercon.com
1960 Park Blvd., Palo Alto, CA 94306 650-325-8077