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Groups > comp.lang.forth > #36468

Re: Static Single Assignment form to Stack allocation

From "Alex McDonald" <blog@rivadpm.com>
Newsgroups comp.lang.forth
Subject Re: Static Single Assignment form to Stack allocation
Date 2015-02-11 09:35 +0000
Organization A noiseless patient Spider
Message-ID <mbf7ol$ltu$1@dont-email.me> (permalink)
References (6 earlier) <DKWdneKJys_1IEvJnZ2dnUU7-KmdnZ2d@supernews.com> <c07a6c9f-c0a2-4e08-b6c3-d9f0f7251223@googlegroups.com> <op.xtu77xp2v6dtjm@localhost> <ZYudnU7c6fCBOkfJnZ2dnUU7-LGdnZ2d@supernews.com> <855de363-e01a-44fb-b8cb-afcae56af8cb@googlegroups.com>

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on 11/02/2015 08:35:22, Mark Wills wrote:
> On Wednesday, 11 February 2015 00:49:34 UTC, Elizabeth D. Rather
> > wrote:
>> That's the implication. A thoroughly unnecessary complication, IMO,
> > wrote:
>> since the issues arise extremely rarely and are easy to handle once
> > wrote:
>> noticed. IMO this is only a big flap because some people don't
> > wrote:
>> understand that it's only in existence during compilation and doesn't
> > wrote:
>> "intermingle" with user data during the *execution* of a program.
> > wrote:
>>
> > wrote:
>> Cheers,
> > wrote:
>> Elizabeth
> wrote:
> 
> The restriction on passing data into a colon def is fleeting, yes.
> As you say, it's an issue that would occur relatively rarely.
> However the restriction on return stack usage within DO loops is
> a restriction that could be alleviated altogether with the adoption
> of a (permanent, not temporary) control-flow stack. Had it been
> adopted, it would have rendered issues such as accessing locals inside
> loops much simpler. The locals would go on the return stack and vanish
> when the definition went out of scope. Loop frames would go on the
> control flow stack. Accessing locals within DO loops would not require
> tracking the location of the locals on the return stack, since they
> wouldn't move regardless of how deeply a loop(s) are nested.

You're confusing compile time with run time. This has been a consistent
theme in discussions about the placement of the control flow stack; Rod
Pemberton suffers from this confusion too.

At *run time* DO is allowed to have loop parameters on the return stack.
There aren't a huge number of places to put such parameters at *run
time*. We can't use the data stack; it would block. We can't use fixed
variables; our code will become impossible. We could use another stack,
but then *at run time* anywhere we had a DO LOOP we'd require a data
stack, a return stack and a loop parameters stack. 

At *compile time* we have two issues.

1) We have a set of *compile time* DO parameters. They can be on the
control flow stack or they can be buried temporarily in the code we're
generating for DO (normally in the branch pointers). There may be none --
the standard doesn't say and it doesn't care. It just says that there's
this thing called DO-SYS and it's on the control flow stack at *compile
time*.

Many Forth compilers choose to use the control stack route as the space
in the generated code may not be ebough; it's certainly a problem in my
Forth. The control stack only exists at *compile time* but if implemented
on the data stack (to avoid having 3 stacks) then it blocks *compile
time* use of values on the stack.

2) This MAY not work in ANS: ... >R DO R@ ... The reason is that at
*compile time* we have to account for the *run time* loop parameters on
the data stack. It is possible to calculate, but in complicates R@ and
makes R> very difficult indeed. Locals may also appear on the stack at
*run time*. They too can be accounted for at *compile time* but is again
adds significant overhead to the *compile time* action of R@, and R> will
normally be far too hard.

> 
> It's far too late now, of course. The horse bolted decades ago.
> 

Which horse? The *compile time* horse or the *run time* horse?

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Static Single Assignment form to Stack allocation Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-02-05 20:01 -0800
  Re: Static Single Assignment form to Stack allocation Paul Rubin <no.email@nospam.invalid> - 2015-02-05 21:00 -0800
    Re: Static Single Assignment form to Stack allocation "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-06 02:15 -0500
      Re: Static Single Assignment form to Stack allocation Paul Rubin <no.email@nospam.invalid> - 2015-02-06 12:07 -0800
        Re: Static Single Assignment form to Stack allocation Jan Coombs <Jan-54 <jenfhaomndgfwutc@murmic.plus.com>> - 2015-02-08 22:38 +0000
          Re: Static Single Assignment form to Stack allocation Paul Rubin <no.email@nospam.invalid> - 2015-02-08 14:55 -0800
            Re: Static Single Assignment form to Stack allocation Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-02-08 19:59 -0800
  Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-06 13:15 +0000
  Re: Static Single Assignment form to Stack allocation anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-02-06 13:22 +0000
    Re: Static Single Assignment form to Stack allocation Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-02-06 11:16 -0800
      Re: Static Single Assignment form to Stack allocation Paul Rubin <no.email@nospam.invalid> - 2015-02-06 12:05 -0800
      Re: Static Single Assignment form to Stack allocation hughaguilar96@gmail.com - 2015-02-06 16:44 -0800
        Re: Static Single Assignment form to Stack allocation "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-06 23:41 -0500
      Re: Static Single Assignment form to Stack allocation "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-06 23:41 -0500
        Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-07 19:22 +0000
          Re: Static Single Assignment form to Stack allocation Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-02-07 13:09 -0800
            Re: Static Single Assignment form to Stack allocation "Elizabeth D. Rather" <erather@forth.com> - 2015-02-07 11:25 -1000
              Re: Static Single Assignment form to Stack allocation Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-02-07 14:09 -0800
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-07 22:32 +0000
                Re: Static Single Assignment form to Stack allocation Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-02-07 14:51 -0800
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-08 00:04 +0000
                Re: Static Single Assignment form to Stack allocation Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-02-07 17:03 -0800
                Re: Static Single Assignment form to Stack allocation "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-07 21:04 -0500
                Re: Static Single Assignment form to Stack allocation "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-07 21:10 -0500
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-08 10:57 +0000
                Re: Static Single Assignment form to Stack allocation "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-07 21:05 -0500
            Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-07 22:24 +0000
          Re: Static Single Assignment form to Stack allocation "Elizabeth D. Rather" <erather@forth.com> - 2015-02-07 11:21 -1000
          Re: Static Single Assignment form to Stack allocation "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-07 20:11 -0500
            Re: Static Single Assignment form to Stack allocation "Elizabeth D. Rather" <erather@forth.com> - 2015-02-07 15:35 -1000
              Re: Static Single Assignment form to Stack allocation "Elizabeth D. Rather" <erather@forth.com> - 2015-02-07 16:52 -1000
                Re: Static Single Assignment form to Stack allocation hughaguilar96@gmail.com - 2015-02-08 10:21 -0800
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-08 20:09 +0000
                Re: Static Single Assignment form to Stack allocation "Elizabeth D. Rather" <erather@forth.com> - 2015-02-08 17:15 -1000
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-09 12:00 +0000
                Re: Static Single Assignment form to Stack allocation albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-02-09 13:05 +0000
                Re: Static Single Assignment form to Stack allocation "HAA" <someone@microsoft.com> - 2015-02-10 16:01 +1100
                Re: Static Single Assignment form to Stack allocation "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-09 02:35 -0500
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-09 12:03 +0000
              Re: Static Single Assignment form to Stack allocation hughaguilar96@gmail.com - 2015-02-08 10:13 -0800
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-08 20:21 +0000
                Re: Static Single Assignment form to Stack allocation hughaguilar96@gmail.com - 2015-02-09 22:49 -0800
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-10 12:12 +0000
                Re: Static Single Assignment form to Stack allocation albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-02-10 12:54 +0000
                Re: Static Single Assignment form to Stack allocation Mark Wills <markwills1970@gmail.com> - 2015-02-10 06:30 -0800
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-10 14:53 +0000
                Re: Static Single Assignment form to Stack allocation "Elizabeth D. Rather" <erather@forth.com> - 2015-02-10 08:20 -1000
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-10 14:33 +0000
                Re: Static Single Assignment form to Stack allocation albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-02-10 19:09 +0000
                Control-flow stack (was: Static Single Assignment ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-02-10 14:29 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) "Alex McDonald" <blog@rivadpm.com> - 2015-02-10 15:49 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-02-10 17:56 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) "Alex McDonald" <blog@rivadpm.com> - 2015-02-10 20:53 +0000
                Re: Control-flow stack "Elizabeth D. Rather" <erather@forth.com> - 2015-02-10 13:08 -1000
                Re: Control-flow stack awegel@arcor.de (Alexander Wegel) - 2015-02-11 03:15 +0100
                Re: Control-flow stack hughaguilar96@gmail.com - 2015-02-10 18:47 -0800
                Re: Control-flow stack Unknown <dog@gmail.com> - 2015-02-17 07:13 +0000
                Re: Control-flow stack anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-02-11 17:59 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-02-11 01:30 -0800
                Re: Control-flow stack (was: Static Single Assignment ...) "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-10 18:43 -0500
                Re: Control-flow stack (was: Static Single Assignment ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-02-11 17:46 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) "Alex McDonald" <blog@rivadpm.com> - 2015-02-11 22:39 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) "Alex McDonald" <blog@rivadpm.com> - 2015-02-11 22:42 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-02-12 09:52 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) "Alex McDonald" <blog@rivadpm.com> - 2015-02-12 10:28 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) hughaguilar96@gmail.com - 2015-02-11 20:23 -0800
                Re: Control-flow stack (was: Static Single Assignment ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-02-12 07:21 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) hughaguilar96@gmail.com - 2015-02-12 18:33 -0800
                Re: Control-flow stack awegel@arcor.de (Alexander Wegel) - 2015-02-13 04:46 +0100
                Re: Control-flow stack "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-13 06:48 -0500
                Re: Control-flow stack awegel@arcor.de (Alexander Wegel) - 2015-02-13 13:40 +0100
                Re: Control-flow stack albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-02-13 15:49 +0000
                Re: Control-flow stack awegel@arcor.de (Alexander Wegel) - 2015-02-14 03:47 +0100
                Re: Control-flow stack anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-02-13 16:09 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-02-13 15:20 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) hughaguilar96@gmail.com - 2015-02-13 21:31 -0800
                Re: Control-flow stack awegel@arcor.de (Alexander Wegel) - 2015-02-14 03:47 +0100
                Re: Control-flow stack (was: Static Single Assignment ...) hughaguilar96@gmail.com - 2015-02-14 19:22 -0800
                Re: Control-flow stack (was: Static Single Assignment ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-02-15 11:09 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) hughaguilar96@gmail.com - 2015-02-15 16:57 -0800
                Re: Control-flow stack (was: Static Single Assignment ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-02-16 14:41 +0000
                Re: Control-flow stack (was: Static Single Assignment ...) hughaguilar96@gmail.com - 2015-02-16 18:43 -0800
                Re: Control-flow stack Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-02-10 22:04 +0000
                Re: Control-flow stack Harold <hzrabbie@gmail.com> - 2015-02-10 16:58 -0800
                Re: Control-flow stack Bernd Paysan <bernd.paysan@gmx.de> - 2015-02-11 02:51 +0100
                Re: Control-flow stack albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-02-11 11:34 +0000
                Re: Control-flow stack Harold <hzrabbie@gmail.com> - 2015-02-11 08:17 -0800
                Re: Control-flow stack "Elizabeth D. Rather" <erather@forth.com> - 2015-02-10 16:37 -1000
                Re: Control-flow stack hughaguilar96@gmail.com - 2015-02-10 18:57 -0800
                Re: Static Single Assignment form to Stack allocation "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-10 18:44 -0500
                Re: Static Single Assignment form to Stack allocation "Elizabeth D. Rather" <erather@forth.com> - 2015-02-10 14:49 -1000
                Re: Static Single Assignment form to Stack allocation hughaguilar96@gmail.com - 2015-02-10 18:16 -0800
                Re: Static Single Assignment form to Stack allocation Mark Wills <markwills1970@gmail.com> - 2015-02-11 00:35 -0800
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-11 09:35 +0000
                Re: Static Single Assignment form to Stack allocation Mark Wills <markwills1970@gmail.com> - 2015-02-11 03:06 -0800
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-11 14:27 +0000
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-11 14:40 +0000
                Re: Static Single Assignment form to Stack allocation "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-12 20:02 -0500
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-13 11:42 +0000
                Re: Static Single Assignment form to Stack allocation "Rod Pemberton" <buzz@notnotnontnooatno.cmm> - 2015-02-13 07:44 -0500
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-13 14:20 +0000
                Re: Static Single Assignment form to Stack allocation "Elizabeth D. Rather" <erather@forth.com> - 2015-02-13 10:32 -1000
                Re: Static Single Assignment form to Stack allocation "Rod Pemberton" <bork@lllljunkqwer.cpm> - 2015-03-29 16:27 -0400
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-03-29 22:46 +0100
                Re: Static Single Assignment form to Stack allocation "Elizabeth D. Rather" <erather@forth.com> - 2015-03-29 15:24 -1000
                Re: Static Single Assignment form to Stack allocation hughaguilar96@gmail.com - 2015-03-30 04:44 -0700
                Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-03-30 15:33 +0100
                Re: Static Single Assignment form to Stack allocation anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-02-11 18:03 +0000
                Re: Static Single Assignment form to Stack allocation Bernd Paysan <bernd.paysan@gmx.de> - 2015-02-12 00:16 +0100
                Re: Static Single Assignment form to Stack allocation anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-02-12 07:08 +0000
            Re: Static Single Assignment form to Stack allocation "Alex McDonald" <blog@rivadpm.com> - 2015-02-08 10:51 +0000

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