Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: Notesfiles $Revision: 1.6.2.16 $; site ima.UUCP
Path: utzoo!decvax!ima!compilers
From: compilers@ima.UUCP
Newsgroups: mod.compilers
Subject: Re: Successful compilers for segment
Message-ID: <136300053@ima.UUCP>
Date: Mon, 13-Jan-86 15:38:00 EST
Article-I.D.: ima.136300053
Posted: Mon Jan 13 15:38:00 1986
Date-Received: Tue, 14-Jan-86 03:43:32 EST
Lines: 31
Approved: compilers@ima.uucp
Nf-ID: #N:ima:136300053:000:1401
Nf-From: ima!compilers    Jan 13 15:38:00 1986


[from ihnp4!ho95e!wcs]

In article <136300045@ima.UUCP> you write:
>[from Davidsen <harvard!rochester!steinmetz!davidsen>]
>In article <136300020@ima.UUCP> compilers@ima.UUCP writes:
>>....
>>You cannot produce a 'good' compiler for a segmented architecture for a
>>language that has unbridled pointers, such as C.  C comes with the built-in
>>assumption that addresses are mappable onto the integers.
>
>Not so! X3J11 has carefully stated that there is no guarantee that integers
>can hold any pointer value, or that any pointer value except (void *) and
>(char *) can hold the address of another data type without data loss. In K&R

I think you're misreading the original statement.  When the author wrote:
	"addresses are mappable onto the integers"
it could been talking about assigning pointers to ints, but was
probably talking about mapping the space of valid addresses onto the
mathematical set {1, 2, 3, 4, ...}, presumably 1:1 with a contiguous
subset of the integers - in other words, 
	"The memory of the machine looks like one long array, not
	 a bunch of little pieces"
which is untrue on segmented machines.
-- 
# Bill Stewart, AT&T Bell Labs 2G-202, Holmdel NJ
1-201-949-0705 ihnp4!ho95c!wcs
[I suspect that a piecewise continuous mapping would be sufficient.  In any
case, I'd rather drop this topic unless somebody from X3J11 or dmr has
something definitive to say.  -John]
--------