Re: What is Forth anyway?

From	"Rudy Velthuis" <newsgroups@rvelthuis.de>
Newsgroups	comp.lang.forth
Subject	Re: What is Forth anyway?
Date	2017-06-07 19:26 +0000
Organization	Aioe.org NNTP Server
Message-ID	<xn0kqyf6hawugxy007@nntp.aioe.org> (permalink)
References	(3 earlier) <dfbcca19-d831-4baa-ba2d-f54e57e53ded@googlegroups.com> <xn0kqvbfb93ngqc004@nntp.aioe.org> <8c451582-6995-4325-a0f5-70c797088836@googlegroups.com> <xn0kqvm3u9fxgfp003@nntp.aioe.org> <rJudnfuBpqoW9qvEnZ2dnUU7-YPNnZ2d@supernews.com>

Show all headers | View raw

Andrew Haley wrote:

> Rudy Velthuis <newsgroups@rvelthuis.de> wrote:
> >> > 
> >> > But it also requires quite a lot of stack juggling, which is not
> >> > required with registers. I am not sure if you have the same
> number >> > of memory accesses without a stack, especially if dat can
> be passed >> > in registers directly.
> >> 
> >> Thank you very much, Captain Obvious!
> > 
> > It may be obvious, but it also shows why stack based passing is not
> > so optimal as you claim it to be. It is nice concept, but I doubt it
> > is the most efficient way to pass parameters. After all, it used to
> > be the main way to pass parameters in most other languages too. But
> > these had/have ways to access each of them by name, not just the
> > one(s) on the top of the stack.
> 
> That's all true, but there are disadvantages too.
> 
> If I've already paid for those registers, which require large and
> complex electronics, I probably also have multiple functional units
> and instructions per clock, so I might as well use them all as much as
> possible.  All other things being equal, that is, but they rarely are!
> 
> To translate any programming language into near-optimum code for a
> register machine is a hard problem.  And I'm going to end up with a
> lot of software to do that.

Oh? Why are you going to end up with a lot of software to do that?
Parameter passing is generally governed by ABIs or calling conventions.
There is no need to allocate registers for that.

And parameter passing through a stack is also governed by a certain
order. Why would that be more optimal, especially if you must do extra
work to access anything but the top of the stack and to prevent values
from being consumed? What makes random access to such a stack (like in
older versions of popular programming languages, which use the machine
stack to pass parameters) harder to use?

Sure, you must have a good register allocator to be able to keep as
many values in registers. But how is that different for a stack based
language? Forth stacks are, as far as I know, generally in memory, like
local variables and parameters in other non-stack-based languages, who
also, most of the time, live on a stack (the machine stack).

And yes, I know there are optimizing Forth implementations. But I
assume these have a register allocator too, and don't constantly push
and pop items. That probably means they need "a lot of software" too,
or do they?

So I still don't see why parameter passing, or register allocation is
easier or more optimal in a stack based language.

I personally find random access to values like parameters or local
variables easier to handle than stack juggling. No need for the
constant use of DUP (or ?DUP) or OVER (in other words: copying), etc.
in order to keep a value from being consumed (and lost). Sure, you can
rearrange your  code so that you avoid some of it. But that also
requires extra effort from the programmer.

-- 
Rudy Velthuis        http://www.rvelthuis.de

"I don't care to belong to a club that accepts people like me as
 members." -- Groucho Marx

Thread

What is Forth anyway? Brad Eckert <hwfwguy@gmail.com> - 2017-06-03 20:31 -0700
  Re: What is Forth anyway? lehs <skydda.barnen@gmail.com> - 2017-06-03 23:05 -0700
    Re: What is Forth anyway? Howerd <howerdo@yahoo.co.uk> - 2017-06-04 03:23 -0700
      Re: What is Forth anyway? lehs <skydda.barnen@gmail.com> - 2017-06-04 03:39 -0700
  Re: What is Forth anyway? Howerd <howerdo@yahoo.co.uk> - 2017-06-04 03:17 -0700
    Re: What is Forth anyway? Howerd <howerdo@yahoo.co.uk> - 2017-06-04 03:18 -0700
  What is Forth anyway? Ilya Tarasov <ilya74.tarasov@gmail.com> - 2017-06-04 05:17 -0700
    Re: What is Forth anyway? Howerd <howerdo@yahoo.co.uk> - 2017-06-04 07:13 -0700
    Re: What is Forth anyway? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-06-05 02:38 -0500
  Re: What is Forth anyway? NN <november.nihal@gmail.com> - 2017-06-04 05:27 -0700
  Re: What is Forth anyway? "HAA" <someone@microsoft.com> - 2017-06-04 23:07 +1000
    Re: What is Forth anyway? Alex <alex@rivadpm.com> - 2017-06-04 19:12 +0100
      Re: What is Forth anyway? Howerd <howerdo@yahoo.co.uk> - 2017-06-04 12:55 -0700
        Re: What is Forth anyway? Alex <alex@rivadpm.com> - 2017-06-04 21:41 +0100
        Re: What is Forth anyway? "HAA" <someone@microsoft.com> - 2017-06-05 15:54 +1000
          Re: What is Forth anyway? Howerd <howerdo@yahoo.co.uk> - 2017-06-05 02:05 -0700
      Re: What is Forth anyway? Ilya Tarasov <ilya74.tarasov@gmail.com> - 2017-06-04 17:33 -0700
        Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-05 12:54 +0000
    Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-04 22:14 +0000
      Re: What is Forth anyway? hughaguilar96@gmail.com - 2017-06-04 16:39 -0700
        Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-05 12:44 +0000
          Re: What is Forth anyway? hughaguilar96@gmail.com - 2017-06-05 08:10 -0700
            Re: What is Forth anyway? gavino himself <jackvanc3@gmail.com> - 2017-06-05 10:01 -0700
            Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-05 19:29 +0000
              Re: What is Forth anyway? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-06-06 03:44 -0500
                Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-07 19:26 +0000
                Re: What is Forth anyway? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-06-08 02:06 -0500
                Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-09 17:09 +0000
            Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-05 19:41 +0000
              Re: What is Forth anyway? lehs <skydda.barnen@gmail.com> - 2017-06-06 02:19 -0700
                Re: What is Forth anyway? Alex <alex@rivadpm.com> - 2017-06-06 10:41 +0100
                Re: What is Forth anyway? Ron Aaron <rambamist@gmail.com> - 2017-06-06 12:45 +0300
                Re: What is Forth anyway? Alex <alex@rivadpm.com> - 2017-06-06 11:23 +0100
                Re: What is Forth anyway? Ron Aaron <rambamist@gmail.com> - 2017-06-06 13:30 +0300
                Re: What is Forth anyway? Alex <alex@rivadpm.com> - 2017-06-06 12:55 +0100
                Re: What is Forth anyway? Ron Aaron <rambamist@gmail.com> - 2017-06-06 14:57 +0300
                Re: What is Forth anyway? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-06 13:34 +0000
                Re: What is Forth anyway? Ron Aaron <rambamist@gmail.com> - 2017-06-06 17:07 +0300
                Re: What is Forth anyway? Coos Haak <htrofhc@gmail.com> - 2017-06-06 16:51 +0200
                Re: What is Forth anyway? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-06 16:32 +0000
                Re: What is Forth anyway? Coos Haak <htrofhc@gmail.com> - 2017-06-07 01:37 +0200
                Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-07 19:29 +0000
                Re: What is Forth anyway? Cecil Bayona <cbayona@cbayona.com> - 2017-06-07 14:56 -0500
                Re: What is Forth anyway? Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-06-06 04:48 -0500
                Re: What is Forth anyway? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-06 10:10 +0000
                Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-07 19:28 +0000
                Re: What is Forth anyway? Cecil Bayona <cbayona@cbayona.com> - 2017-06-07 14:54 -0500
                Re: What is Forth anyway? lehs <skydda.barnen@gmail.com> - 2017-06-07 19:42 -0700
                Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-09 17:12 +0000
      Re: What is Forth anyway? Ilya Tarasov <ilya74.tarasov@gmail.com> - 2017-06-04 17:40 -0700
        Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-05 12:51 +0000
          Re: What is Forth anyway? Ilya Tarasov <ilya74.tarasov@gmail.com> - 2017-06-05 17:19 -0700
            Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-07 19:32 +0000
              Re: What is Forth anyway? Ilya Tarasov <ilya74.tarasov@gmail.com> - 2017-06-07 16:50 -0700
                Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-09 17:15 +0000
                Re: What is Forth anyway? Ilya Tarasov <ilya74.tarasov@gmail.com> - 2017-06-09 13:04 -0700
                Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-09 21:27 +0000
          Re: What is Forth anyway? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-06 10:19 +0000
            Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-07 19:38 +0000
              Re: What is Forth anyway? anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2017-06-08 11:52 +0000
                Re: What is Forth anyway? "Rudy Velthuis" <newsgroups@rvelthuis.de> - 2017-06-09 17:23 +0000
  Re: What is Forth anyway? gavino himself <jackvanc3@gmail.com> - 2017-06-05 07:16 -0700
  Re: What is Forth anyway? gavino himself <jackvanc3@gmail.com> - 2017-06-05 07:35 -0700

csiph-web