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Re: Looking for some help with this gforth program. Thanks!

From Andrew Haley <andrew29@littlepinkcloud.invalid>
Subject Re: Looking for some help with this gforth program. Thanks!
Newsgroups comp.lang.forth
References (8 earlier) <2016May15.123405@mips.complang.tuwien.ac.at> <nh9u7g$cl1$1@dont-email.me> <2016May16.142145@mips.complang.tuwien.ac.at> <2IudnXskFpi2kqfKnZ2dnUU7-fHNnZ2d@supernews.com> <2016May17.143919@mips.complang.tuwien.ac.at>
Message-ID <WbGdnY_WbO-Ep6bKnZ2dnUU7-RfNnZ2d@supernews.com> (permalink)
Date 2016-05-17 10:34 -0500

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Anton Ertl <anton@mips.complang.tuwien.ac.at> wrote:
> Andrew Haley <andrew29@littlepinkcloud.invalid> writes:
>>Anton Ertl <anton@mips.complang.tuwien.ac.at> wrote:

>>> 
>>> A stack machine would avoid that problem, and, if implemented with
>>> comparable technology as the Intel CPUs, would be quite a bit faster
>>> on this kind of code.  Alternatively, one can have a more
>>> sophisticated compiler that keeps stack items in register and avoids
>>> this kind of problem.  In that case the stack machine has no
>>> performance advantage; a stack machine with in-order execution would
>>> be much simpler, but would not benefit from superscalar execution
>>> enabled by out-of-order execution, so I guess the Intel CPU would be
>>> faster, although at a huge cost in CPU complexity.
>>
>>But this advantage fails as soon as you're at a call site: then you
>>have to do the grand shuffle to get all the arguments in the right
>>place and save all of the call-clobbered registers onto the stack.
> 
> No.  In Forth the compiler knows what code a direct call calls, so
> there is no need for a shuffle before or after a direct call.  And of
> course a compiler that makes use of that knowledge will avoid putting
> data that lives across the direct call in a register that is clobbered
> by the callee.

OK, fair enough: you're assuming total visibility of everything.  I'll
grant this is true, and it means that no "ABI" per se is necessary
apart from over e.g. EXECUTE.  (And I'll note that "conventional"
compilers use similar techiniques with inter-procedural optimization
passes.)  However, there is still a problem that the data required
aren't always going to be in the most convenient registers as they
would be when inlining, especially as you're going to be running out
of registers a lot of the time.

I'm curoious: does any Forth compiler do this?

I accept your point about SWAP ROT BLAH not being free.

>>As long as you can inline deeply and there are enough registers to
>>hold temporaries, everything is fine, but deep inlining causes an
>>explosion of complexity.
> 
> Whether you inline deeply, or shallowly, I don't see much difference
> in complexity; there is a difference in code size, however.

There does tends to be an increase in complexity when inlining because
of the increase in size: you usually need more registers and their
live ranges increase, so the complexity of register allocation
increases steeply along with the complexity of the control flow.

>>The best JIT compilers only generate code for commonly-executed paths,
>>and this allows very deep inlining.  A lot of the time the overhead
>>for calls simply goes away.  That would work very well for Forth.
> 
> See! 

!

> The trace-based approach is not what I was thinking of, but is
> another way to get similar results.

Indeed.  The idea is to concentrate the firepower of the compiler on
the best targets; trace compiling is one way to do that.

Andrew.

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Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-11 13:54 -0700
  Re: Looking for some help with this gforth program. Thanks! all2001@spambog.com (Wolfgang Allinger) - 2016-05-11 17:59 -0300
    Re: Looking for some help with this gforth program. Thanks! hughaguilar96@gmail.com - 2016-05-11 19:16 -0700
      Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-11 19:40 -0700
        Re: Looking for some help with this gforth program. Thanks! Paul Rubin <no.email@nospam.invalid> - 2016-05-11 23:22 -0700
          Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-12 00:01 -0700
            Re: Looking for some help with this gforth program. Thanks! hughaguilar96@gmail.com - 2016-05-12 00:08 -0700
              Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-12 12:09 -0700
            Re: Looking for some help with this gforth program. Thanks! rickman <gnuarm@gmail.com> - 2016-05-12 20:48 -0400
              Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-12 18:04 -0700
                Re: Looking for some help with this gforth program. Thanks! rickman <gnuarm@gmail.com> - 2016-05-12 21:21 -0400
                Re: Looking for some help with this gforth program. Thanks! Cecil Bayona <cbayona@cbayona.com> - 2016-05-12 20:27 -0500
                Re: Looking for some help with this gforth program. Thanks! Paul Rubin <no.email@nospam.invalid> - 2016-05-12 18:46 -0700
                Re: Looking for some help with this gforth program. Thanks! Cecil Bayona <cbayona@cbayona.com> - 2016-05-12 23:28 -0500
                Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-13 00:52 -0700
                Re: Looking for some help with this gforth program. Thanks! Pablo Hugo Reda <pabloreda@gmail.com> - 2016-05-13 04:07 -0700
                Re: Looking for some help with this gforth program. Thanks! rickman <gnuarm@gmail.com> - 2016-05-14 00:42 -0400
                Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-14 00:05 -0700
                Re: Looking for some help with this gforth program. Thanks! rickman <gnuarm@gmail.com> - 2016-05-15 00:10 -0400
                Re: Looking for some help with this gforth program. Thanks! anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-05-15 10:34 +0000
                Re: Looking for some help with this gforth program. Thanks! rickman <gnuarm@gmail.com> - 2016-05-15 09:43 -0400
                Re: Looking for some help with this gforth program. Thanks! anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-05-16 12:21 +0000
                Re: Looking for some help with this gforth program. Thanks! hughaguilar96@gmail.com - 2016-05-16 07:38 -0700
                Re: Looking for some help with this gforth program. Thanks! anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-05-16 14:56 +0000
                Re: Looking for some help with this gforth program. Thanks! rickman <gnuarm@gmail.com> - 2016-05-16 12:07 -0400
                Re: Looking for some help with this gforth program. Thanks! Paul Rubin <no.email@nospam.invalid> - 2016-05-16 09:18 -0700
                Re: Looking for some help with this gforth program. Thanks! Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-05-16 13:19 -0500
                Re: Looking for some help with this gforth program. Thanks! anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-05-17 12:39 +0000
                Re: Looking for some help with this gforth program. Thanks! Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-05-17 10:34 -0500
                Re: Looking for some help with this gforth program. Thanks! anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-05-17 15:54 +0000
                Re: Looking for some help with this gforth program. Thanks! mhx@iae.nl - 2016-05-17 12:44 -0700
                Re: Looking for some help with this gforth program. Thanks! hughaguilar96@gmail.com - 2016-05-15 11:03 -0700
                Re: Looking for some help with this gforth program. Thanks! rickman <gnuarm@gmail.com> - 2016-05-15 21:56 -0400
                Re: Looking for some help with this gforth program. Thanks! Paul Rubin <no.email@nospam.invalid> - 2016-05-15 19:02 -0700
                Re: Looking for some help with this gforth program. Thanks! hughaguilar96@gmail.com - 2016-05-15 20:03 -0700
                Re: Looking for some help with this gforth program. Thanks! rickman <gnuarm@gmail.com> - 2016-05-16 02:13 -0400
                Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-16 00:37 -0700
                Re: Looking for some help with this gforth program. Thanks! anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-05-16 13:41 +0000
                Re: Looking for some help with this gforth program. Thanks! Bernd Paysan <bernd.paysan@gmx.de> - 2016-05-16 21:42 +0000
                Re: Looking for some help with this gforth program. Thanks! hughaguilar96@gmail.com - 2016-05-16 16:23 -0700
                Re: Looking for some help with this gforth program. Thanks! Paul Rubin <no.email@nospam.invalid> - 2016-05-16 16:41 -0700
                Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-16 20:32 -0700
                Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-16 20:47 -0700
                Re: Looking for some help with this gforth program. Thanks! anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-05-17 06:32 +0000
                Re: Looking for some help with this gforth program. Thanks! Paul Rubin <no.email@nospam.invalid> - 2016-05-17 07:56 -0700
                Re: Looking for some help with this gforth program. Thanks! Bernd Paysan <bernd.paysan@gmx.de> - 2016-05-17 23:05 +0000
                Re: Looking for some help with this gforth program. Thanks! Paul Rubin <no.email@nospam.invalid> - 2016-05-17 21:16 -0700
                Re: Looking for some help with this gforth program. Thanks! Bernd Paysan <bernd.paysan@gmx.de> - 2016-06-04 22:44 +0000
                Re: Looking for some help with this gforth program. Thanks! anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-05-17 13:42 +0000
                Re: Looking for some help with this gforth program. Thanks! Bernd Paysan <bernd.paysan@gmx.de> - 2016-05-17 22:31 +0000
                Re: Looking for some help with this gforth program. Thanks! anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2016-05-18 16:43 +0000
                Re: Looking for some help with this gforth program. Thanks! Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-05-16 10:38 -0500
                Re: Looking for some help with this gforth program. Thanks! Paul Rubin <no.email@nospam.invalid> - 2016-05-16 10:10 -0700
                Re: Looking for some help with this gforth program. Thanks! Cecil Bayona <cbayona@cbayona.com> - 2016-05-16 12:29 -0500
                Re: Looking for some help with this gforth program. Thanks! Cecil Bayona <cbayona@cbayona.com> - 2016-05-16 12:34 -0500
                Re: Looking for some help with this gforth program. Thanks! Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-05-16 13:27 -0500
                Re: Looking for some help with this gforth program. Thanks! Paul Rubin <no.email@nospam.invalid> - 2016-05-17 16:11 -0700
                Re: Looking for some help with this gforth program. Thanks! Andrew Haley <andrew29@littlepinkcloud.invalid> - 2016-05-18 04:31 -0500
                Re: Looking for some help with this gforth program. Thanks! Albert van der Horst <albert@cherry.spenarnc.xs4all.nl> - 2016-05-16 18:46 +0000
                Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-14 00:07 -0700
                Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-14 00:20 -0700
                Re: Looking for some help with this gforth program. Thanks! Paul Rubin <no.email@nospam.invalid> - 2016-05-14 01:23 -0700
                Re: Looking for some help with this gforth program. Thanks! rickman <gnuarm@gmail.com> - 2016-05-15 00:13 -0400
                Re: Looking for some help with this gforth program. Thanks! Paul Rubin <no.email@nospam.invalid> - 2016-05-14 21:55 -0700
  Re: Looking for some help with this gforth program. Thanks! Paul Rubin <no.email@nospam.invalid> - 2016-05-11 17:08 -0700
    Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-11 17:40 -0700
      Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-11 18:54 -0700
        Re: Looking for some help with this gforth program. Thanks! Doug Hoffman <glidedog@gmail.com> - 2016-05-13 06:55 -0400
          Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-13 11:07 -0700
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            Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-13 20:57 -0700
            Re: Looking for some help with this gforth program. Thanks! Doug Hoffman <glidedog@gmail.com> - 2016-05-14 05:54 -0400
              Re: Looking for some help with this gforth program. Thanks! hughaguilar96@gmail.com - 2016-05-14 15:20 -0700
                Re: Looking for some help with this gforth program. Thanks! Doug Hoffman <glidedog@gmail.com> - 2016-05-15 05:45 -0400
                Re: Looking for some help with this gforth program. Thanks! hughaguilar96@gmail.com - 2016-05-15 11:21 -0700
                Re: Looking for some help with this gforth program. Thanks! hughaguilar96@gmail.com - 2016-05-15 11:39 -0700
    Re: Looking for some help with this gforth program. Thanks! hughaguilar96@gmail.com - 2016-05-11 20:45 -0700
      Re: Looking for some help with this gforth program. Thanks! hughaguilar96@gmail.com - 2016-05-11 23:05 -0700
        Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-11 23:15 -0700
          Re: Looking for some help with this gforth program. Thanks! rickman <gnuarm@gmail.com> - 2016-05-12 22:34 -0400
      Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-11 23:11 -0700
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    Re: Looking for some help with this gforth program. Thanks! murphy.darin@gmail.com - 2016-05-12 16:20 -0700
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