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List:       dailydave
Subject:    Re: [Dailydave] Getting Old.
From:       Tiago Assumpcao <module () whatever ! org ! ar>
Date:       2004-08-12 19:25:32
Message-ID: 411BC42C.9040102 () whatever ! org ! ar
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Dave Aitel wrote:

> Basically, you have to write a gnu-compatable assembler entirely in 
> Python. I have one for X86 which was quite difficult due to variable 
> length opcodes, but it's not nearly has difficult ( I think ) on 
> something like SPARC/MIPS/PPC, etc.
>
> -dave
>
>
>

Hi!

 From this point of view, I think the main problems are three:

- The problem of variable lengh encodings, like on x86 instruction set 
architecture, is
really annoying!

- On ISA's using static scheduling ILP, which directly affect the 
programmer/compiler
engineer (eg. classic MIPS and EPIC), you may have the great pain in the 
ass of -- at
least -- treating the data-hazards.
However, most VLIW are fixed-length encoding, which would aliviate the pain.

- ABI compatibility; as an example: there are 4 ABI's (that I know) for 
MIPS based
boards: o32 (Irix >=5.3/Linux), n64 (Irix >=6.0), n32 (Irix >=6.2) and 
EABI (embeddeds
with MIPS16 ISA).
Of course you could generate only o32 for MIPS, but yet every 
architecture compatibility
addition would mean not only code but another binary compatibility too.


At the end, I think it's all about a tradeoff: would one really care 
about having SuperH
compatible code generator? Would you need to use compression with a 
CodePack?
However, a SPARC assembler would be really interesting to exist in the 
MOSDEF
framework.

Thanks god I just became 23! But this hung over (beer, not tequila!) I'm 
on today makes
me feel like I am 90. Wish I had some fresh mango juice right now, 
however I only have
coconut watter...


Cheers.


PD.: Does current MOSDEF take care of most used x86 SIMD extensions? How 
about
the x87 FPU? I remember noir's getPC for i386 using the x87 FPU's 
environment (BTW
why have they kept the stack-based FPU?). That would interesting IMHO.

PD2.: Will Hoglund give out the 3com ASIC's ISA mentioned on Exploiting 
Software? ;-D

-- 
Tiago Rezende Assumpcao - module  whatever org ar
7D9A A6BA 8275 964E EF47 EE5A 7AFF C759 B578 ACAA

http://whatever.org.ar/~module



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