Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!sdd.hp.com!hplabs!hpda!hpcuhc!hpcupt3!shankar
From: shankar@hpcupt3.cup.hp.com (Shankar Unni)
Newsgroups: comp.arch
Subject: Re: Compilers and efficiency
Message-ID: <45760011@hpcupt3.cup.hp.com>
Date: 20 Apr 91 04:43:22 GMT
References: <9782@mentor.cc.purdue.edu>
Organization: HP India Software Op., Bangalore
Lines: 18

In comp.arch, robertsw@gtephx.UUCP (Wild Rider) writes:

> 	or, you could do like motorola did when they designed the 030:
> 	dump a couple of unused 020 instructions, i.e., the "callm"
> 	("call module") and the corresponding "rtm" ("return from
> 	module") instructions.  yes, that's correct, you can have an

That's surely an oversimplification. What usually happens is that those
instructions will raise some sort of "unimplemented instruction" (or
so-called "assist") exception, which is different from the run-of-the-mill
"illegal instruction", moving the responsibility for simulating
those instructions to the kernel (or the user program, if you are running
stand-alone embedded programs).  This sort of thing is commonly done with
certain types of floating-point instructions.
-----
Shankar Unni                                   E-Mail:
HP India Software Operation, Bangalore       Internet: shankar@cup.hp.com
Phone : +91-812-261254 x417                      UUCP: ...!hplabs!hpda!shankar