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From: mac3n@babbage.UUCP
Newsgroups: comp.lang.c,comp.misc
Subject: Re: 32bit = 16bit x 16bit (Really: Compiler deficiencies)
Message-ID: <120@babbage.acc.virginia.edu>
Date: Tue, 27-Oct-87 14:25:54 EST
Article-I.D.: babbage.120
Posted: Tue Oct 27 14:25:54 1987
Date-Received: Sat, 31-Oct-87 02:21:40 EST
References: <141@kesmai.COM> 7349@alice.UUCP <146MAXHAM@RICE> <593@l.cc.purdue.edu>
Organization: University of Virginia
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Xref: utgpu comp.lang.c:4928 comp.misc:1368

In article <593@l.cc.purdue.edu>, cik@l.cc.purdue.edu (Herman Rubin) writes:
> A general problem with HLL's is that they do not have the necessary
> flexibility to handle situations like this.  I do not know of any language
> which has in its operation list an operation to multiply two 16 bit object
> and get a 32 bit object.

In, e.g., Ada the overloading operators allow one to extend "*" for use
with two "16 bit" objects when the context calls for a "32 bit" object.
Ada is fairly unusual in allowing overload resolution based on context,
a feature that adds considerable complexity to the compiler.

> I know
> of no way to tell the compiler that here is an operation with a given syntax,
> and the compiler should put it in its set of operations.

The usual way to extend the set of operations in a language is with procedures.
Many languages are compatible with machine-language procedures.
Some languages allow inline procedues.  Some even allow inline assembler.

If you really want that much control over the code generated, perhaps you
should write your own compiler.  There are several systems which construct
code generators from a set of instructions and their semantics.  Automatic
code generation generation is still pretty new.

> It is clear that the languages need more flexibility
> and that the gurus who claim that they have the solutions are wrong.

Few Gurus claim that they have the perfect solutions.  Merely adequate.