Re: [myhdl-list] Next Python to VHDL generator by using LLVM

[Christopher F. <chr...@gm...>]

>>
>> On 1/15/2013 11:45 AM, David Blubaugh wrote:
>>>
>>> To All,
>>>
>>> I was wondering if someone has looked in the use of the LLVM to be able to generate full featured python into synthesizable VHDL with simulation support of course ??
>>>
>>> I STRONGLY BELIEVE YOU GUYS NEED TO LOOK AT LLVM for greatly enhancing MyHDL to support a greater domain of the python language to support synthesizable designs and testbench support.
>>>
>>> David Blubaugh
>>>
>>
>> I completely disagree this is *not* something the MyHDL
>> group should be interested in.  There would be no benefit
>> for the MyHDL folks to look at this.
>>
>> In addition, other than a buzz word you didn't provide
>> any technical arguments why this would be desirable.
>>
>> Regards,
>> Chris
>>
>
> The reason as to why this needs to be looked at is that if you want to support higher level functionality of the python language to support synthesizable HDL designs the current method is to to use a subset of the python language.  What I am talking about is the possibility of extending MyHDL capabilities of supporting ALL if not most of the higher level functionality of the python language to support advanced designs in synthesizable HDLs.  Take a look at Trident C programmingl language with LLVM support.  It supported close to 98 percent of C functionality for directed and efficient synthesizable HDL design.
>
> Please take a look at the following link:
>
> http://trident.sourceforge.net/
>
> This is for the C language but I wonder if an equivalent system could not be developed by using python as the central controlling programming language instead of C.  LLVM stands for low level virtual machine language that allows the expression of one language, this case python, to be implemented on an entirely different architecture (FPGAS instead of a von-neumann architecture).
>
> Any feedback or questions is more than appreciated !!!
>
> David


I am familiar with trident, have actually used it.  I am
familiar with LLVM (barely).  The state of trident is that
it was used for a particular set of cases/experiments.  It
would be difficult to use it other than experiments and
investigation.

I don't believe trident has been touched in years.  I am not
an LLVM expert but I think LLVM fits better if you are trying
to kludge C-family of code into something rather than something
like Python.  At one point, I thought Uladen-Swallow Python
(US-Python) would win out over pypy, well that appears to have
played out and US-Python was the loser.  I don't know for sure
but I believe US-Python didn't succeed because of limitations
in LLVM.  I also (gut guess) don't think LLVM is ideal as
an intermediate format for representing hardware.

I believe LLVM is great for languages like C/C++ and resulted
in cleaner C* compilers (e.g. clang).  But I don't think it is
a cure all fit all.  I am commenting out of my league about this
C compiler stuff, I only know the little I have read here and
there.

If someone where really interested in this LLVM -> HDL it
won't be the MyHDL folks.  The MyHDL folks are interested
in describing hardware in Python in the manner Jan D. has
outlined.  Which may or many not include some HLS as it
grows.  If you want a magic Python -> intermediate
format -> hardware, I don't think it overlaps with the
efforts/goals of MyHDL.  What you would want to do is get
your LLVM->HDL working (use the trident framework, which
by the way is in java) and when someone completes the
Python->LLVM you will be set, but again, I don't think it
is something that is of interest to the majority of MyHDL users.

I believe, if MyHDL incorporates HLS it will be in the same
elaboration/generator (HDL) description as exists now.  I
believe this really fits what you would want for hardware
description.  Instead of trying to convert a ton of Python
code, ugh that would be a mess with or without an LLVM.
I think you are under estimating what a Python to LLVM
and LLVM to HDL would take and overestimating what LLVM
provides.

Regards,
Chris