Re: Portable Assembly

From	David Brown <david.brown@hesbynett.no>
Newsgroups	comp.arch.embedded
Subject	Re: Portable Assembly
Date	2017-06-05 18:10 +0200
Organization	A noiseless patient Spider
Message-ID	<oh3vim$npl$1@dont-email.me> (permalink)
References	<ogckfb$qcb$1@dont-email.me> <op.y07n39ubj0diun@thanatos.lan> <oh3qeq$7lt$1@news2.open-news-network.org>

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On 05/06/17 16:39, Mike Perkins wrote:
> On 02/06/2017 16:03, Boudewijn Dijkstra wrote:
>> Op Sat, 27 May 2017 21:39:36 +0200 schreef rickman <gnuarm@gmail.com>:
>>> Someone in another group is thinking of using a portable assembler to
>>> write code for an app that would be ported to a number of different
>>> embedded processors including custom processors in FPGAs.  I'm
>>> wondering how useful this will be in writing code that will require
>>> few changes across CPU ISAs and manufacturers.
>>>
>>> I am aware that there are many aspects of porting between CPUs that is
>>> assembly language independent, like writing to Flash memory.  I'm more
>>> interested in the issues involved in trying to use a universal
>>> assembler to write portable code in general.  I'm wondering if it
>>> restricts the instructions you can use or if it works more like a
>>> compiler where a single instruction translates to multiple target
>>> instructions when there is no one instruction suitable.
>>>
>>> Or do I misunderstand how a portable assembler works?  Does it require
>>> a specific assembly language source format for each target just like
>>> using the standard assembler for the target?
>>
>> LLVM has a pretty generic intermediate assembler language, though I'm
>> not sure if it's meant for actually writing code in.
>>
>> http://llvm.org/docs/LangRef.html#instruction-reference
> 
> Interesting, but its not obvious who the audience is. Why would anyone 
> want to learn another language that is not in common use or aligned to 
> any specific CPU?

The LLVM "assembly" is intended as an intermediary language.  Front-end 
tools like clang (a C, C++ and Objective-C compiler) generate LLVM 
assembly.  Middle-end tools like optimisers and linkers "play" with it. 
and back-end tools translate it into target-specific assembly.  Each 
level can do a wide variety of optimisations.  The aim is that the whole 
LLVM system can be more modular and more easily ported to new 
architectures and new languages than a traditional multi-language 
multi-target compiler (such as gcc).  So LLVM assembly is not an 
assembly language you would learn or code in - it's the glue holding the 
whole system together.

> 
>> Another portable assembly language is Java Bytecode, though it assumes a
>> 32-bit machine.
> 
> I've been watching this thread for some time. My first impression was 
> why not just write in C? So far that impression hasn't changed. Despite 
> the odd line of CPU specific assembler code for those occasions that 
> require it, C is still perhaps the most portable code you can write?
> 

Well, yes - of course C is the sensible option here.  Depending on the 
exact type of code and the targets, Ada, C++, and Forth might also be 
viable options.  But since there is no such thing as "portable 
assembly", it's a poor choice :-)  However, the thread has lead to some 
interesting discussions, IMHO.

Thread

Portable Assembly rickman <gnuarm@gmail.com> - 2017-05-27 15:39 -0400
  Re: Portable Assembly Grant Edwards <invalid@invalid.invalid> - 2017-05-27 21:05 +0000
    Re: Portable Assembly Mel Wilson <mwilson@the-wire.com> - 2017-05-27 21:29 +0000
    Re: Portable Assembly upsidedown@downunder.com - 2017-05-28 00:36 +0300
      Re: Portable Assembly Grant Edwards <invalid@invalid.invalid> - 2017-05-27 21:56 +0000
        Re: Portable Assembly Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2017-05-28 14:36 +0200
      Re: Portable Assembly David Brown <david.brown@hesbynett.no> - 2017-05-29 09:53 +0200
  Re: Portable Assembly Les Cargill <lcargill99@comcast.com> - 2017-05-27 16:17 -0500
    Re: Portable Assembly Dimiter_Popoff <dp@tgi-sci.com> - 2017-05-28 00:31 +0300
      Re: Portable Assembly Theo Markettos <theom+news@chiark.greenend.org.uk> - 2017-05-27 22:52 +0100
        Re: Portable Assembly Grant Edwards <invalid@invalid.invalid> - 2017-05-27 21:58 +0000
          Re: Portable Assembly upsidedown@downunder.com - 2017-05-28 07:37 +0300
            Re: Portable Assembly rickman <gnuarm@gmail.com> - 2017-05-28 01:28 -0400
            Re: Portable Assembly Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-05-28 07:33 +0100
              Re: Portable Assembly rickman <gnuarm@gmail.com> - 2017-05-28 03:22 -0400
                Re: Portable Assembly Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-05-28 08:49 +0100
                Re: Portable Assembly upsidedown@downunder.com - 2017-05-28 15:03 +0300
          Re: Portable Assembly Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-05-28 12:26 +0300
        Re: Portable Assembly Dimiter_Popoff <dp@tgi-sci.com> - 2017-05-28 01:04 +0300
        Re: Portable Assembly David Brown <david.brown@hesbynett.no> - 2017-05-29 10:43 +0200
          Re: Portable Assembly Anssi Saari <as@sci.fi> - 2017-05-31 10:19 +0300
            Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-05-31 01:49 -0700
            Re: Portable Assembly Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-05-31 15:56 +0300
        Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-05-29 02:33 -0700
          Re: Portable Assembly upsidedown@downunder.com - 2017-05-29 23:46 +0300
            Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-05-29 13:54 -0700
      Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-05-27 15:52 -0700
        Re: Portable Assembly Dimiter_Popoff <dp@tgi-sci.com> - 2017-05-28 02:14 +0300
          Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-05-27 17:14 -0700
            Re: Portable Assembly Dimiter_Popoff <dp@tgi-sci.com> - 2017-05-28 03:38 +0300
              Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-05-27 18:42 -0700
      Re: Portable Assembly Stefan Reuther <stefan.news@arcor.de> - 2017-05-28 18:45 +0200
        Re: Portable Assembly Dimiter_Popoff <dp@tgi-sci.com> - 2017-05-28 20:47 +0300
          Re: Portable Assembly Stefan Reuther <stefan.news@arcor.de> - 2017-05-29 18:43 +0200
            Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-05-29 10:23 -0700
            Re: Portable Assembly "Boudewijn Dijkstra" <sp4mtr4p.boudewijn@indes.com> - 2017-05-30 16:31 +0200
        Re: Portable Assembly Grant Edwards <invalid@invalid.invalid> - 2017-05-29 01:59 +0000
          Re: Portable Assembly Dimiter_Popoff <dp@tgi-sci.com> - 2017-05-29 05:21 +0300
      Re: Portable Assembly Les Cargill <lcargill99@comcast.com> - 2017-05-28 22:04 -0500
        Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-05-29 02:57 -0700
      Re: Portable Assembly David Brown <david.brown@hesbynett.no> - 2017-05-29 11:00 +0200
        Re: Portable Assembly Dimiter_Popoff <dp@tgi-sci.com> - 2017-05-29 15:08 +0300
          Re: Portable Assembly David Brown <david.brown@hesbynett.no> - 2017-05-29 15:06 +0200
            Re: Portable Assembly Dimiter_Popoff <dp@tgi-sci.com> - 2017-05-29 20:02 +0300
              Re: Portable Assembly David Brown <david.brown@hesbynett.no> - 2017-05-29 23:13 +0200
                Re: Portable Assembly Dimiter_Popoff <dp@tgi-sci.com> - 2017-05-30 16:53 +0300
                Re: Portable Assembly David Brown <david.brown@hesbynett.no> - 2017-05-31 11:36 +0200
                Re: Portable Assembly Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-01 22:43 +0300
                Re: Portable Assembly David Brown <david.brown@hesbynett.no> - 2017-06-02 13:27 +0200
          Re: Portable Assembly Grant Edwards <invalid@invalid.invalid> - 2017-05-29 13:48 +0000
    Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-05-27 15:46 -0700
    Re: Portable Assembly Tim Wescott <tim@seemywebsite.really> - 2017-05-28 23:59 -0500
  Re: Portable Assembly Dimiter_Popoff <dp@tgi-sci.com> - 2017-05-28 00:23 +0300
  Re: Portable Assembly jim.brakefield@ieee.org - 2017-05-27 16:54 -0700
  Re: Portable Assembly Walter Banks <walter@bytecraft.com> - 2017-05-29 17:23 -0400
  Re: Portable Assembly "Boudewijn Dijkstra" <sp4mtr4p.boudewijn@indes.com> - 2017-06-02 17:03 +0200
    Re: Portable Assembly Mike Perkins <spam@spam.com> - 2017-06-05 15:39 +0100
      Re: Portable Assembly David Brown <david.brown@hesbynett.no> - 2017-06-05 18:10 +0200
      Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-06-05 09:10 -0700
        Re: Portable Assembly George Neuner <gneuner2@comcast.net> - 2017-06-06 00:24 -0400
          Re: Portable Assembly David Brown <david.brown@hesbynett.no> - 2017-06-06 11:05 +0200
          Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-06-06 07:03 -0700
            Re: Portable Assembly David Brown <david.brown@hesbynett.no> - 2017-06-06 16:58 +0200
              Re: Portable Assembly Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-06-06 21:26 +0300
            Re: Portable Assembly George Neuner <gneuner2@comcast.net> - 2017-06-06 16:42 -0400
              Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-06-06 23:16 -0700
                Re: Portable Assembly George Neuner <gneuner2@comcast.net> - 2017-06-08 06:38 -0400
                Re: Portable Assembly Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-08 15:58 +0300
                Re: Portable Assembly upsidedown@downunder.com - 2017-06-08 21:34 +0300
                Re: Portable Assembly Les Cargill <lcargill99@comcast.com> - 2017-06-10 15:27 -0500
                Re: Portable Assembly Les Cargill <lcargill99@comcast.com> - 2017-06-10 15:23 -0500
                Re: Portable Assembly Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-08 14:50 +0100
                Re: Portable Assembly Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-06-08 17:38 +0300
                Re: Portable Assembly Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-08 16:37 +0100
                Re: Portable Assembly George Neuner <gneuner2@comcast.net> - 2017-06-09 14:14 -0400
                Re: Portable Assembly Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-06-09 22:25 +0100
                Re: Portable Assembly Clifford Heath <no.spam@please.net> - 2017-06-10 09:54 +1000
                Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-06-09 00:06 -0700
                Re: Portable Assembly George Neuner <gneuner2@comcast.net> - 2017-06-09 22:14 -0400
                Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-06-09 22:50 -0700
                Re: Portable Assembly George Neuner <gneuner2@comcast.net> - 2017-06-10 21:01 -0400
                Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-06-11 00:39 -0700
                Re: Portable Assembly George Neuner <gneuner2@comcast.net> - 2017-06-12 23:27 -0400
                Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-06-12 22:42 -0700
                Re: Portable Assembly Ed Prochak <edprochak@gmail.com> - 2017-06-13 14:24 -0700
                Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-06-13 21:57 -0700
                Re: Portable Assembly Reinhardt Behm <rbehm@hushmail.com> - 2017-06-14 13:26 +0800
                Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-06-13 23:58 -0700
                Re: Portable Assembly Ed Prochak <edprochak@gmail.com> - 2017-06-19 06:48 -0700
                Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-06-19 16:45 -0700
                Re: Portable Assembly Ed Prochak <edprochak@gmail.com> - 2017-06-20 15:07 -0700
                Re: Portable Assembly Don Y <blockedofcourse@foo.invalid> - 2017-06-21 07:37 -0700
              Re: Portable Assembly David Brown <david.brown@hesbynett.no> - 2017-06-07 09:20 +0200
          Re: Portable Assembly Niklas Holsti <niklas.holsti@tidorum.invalid> - 2017-06-07 00:30 +0300
            Re: Portable Assembly George Neuner <gneuner2@comcast.net> - 2017-06-07 02:02 -0400

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