llvm dev - Mar 2013 - [LLVMdev] dragon egg + llvm for fortran to c translation

hi!

I would like to know if it is feasible to use the dragon egg gcc plugin 
to automatically convert fortran code to c. Having found that it is 
possible to output llvm byte code back to c (at least something like 
this gave me this impression/hope: llc -march=c -o test.c) I am hoping 
to use dragon egg to generate the byte code from fortran 90 which than 
output to c.
Does this seem feasible at all? How much in terms of variable names 
etc. could be retained in this manner?

thanks for any suggestions or comments
    Philipp

Hi Philipp,
> I would like to know if it is feasible to use the dragon egg gcc plugin to
> automatically convert fortran code to c. Having found that it is possible
to
> output llvm byte code back to c (at least something like this gave me this
> impression/hope: llc -march=c -o test.c) I am hoping to use dragon egg to
> generate the byte code from fortran 90 which than output to c.
> Does this seem feasible at all? How much in terms of variable names etc.
could
> be retained in this manner?
some people have already been doing this.  There were some minor issues but on
the whole it seems it worked OK.  The big problem is that LLVM's C backend
has
been removed, so you would have to use an old version of LLVM (or help out with
bringing the C backend back to life).

Ciao, Duncan.

Philipp Schwaha <philipp at schwaha.net> writes:
> I would like to know if it is feasible to use the dragon egg gcc
> plugin to automatically convert fortran code to c. Having found that
> it is possible to output llvm byte code back to c (at least something
> like this gave me this impression/hope: llc -march=c -o test.c) I am
> hoping to use dragon egg to generate the byte code from fortran 90
> which than output to c.
The C backend was removed from LLVM some time ago, so your llc recipe
won't work with a recent or development version. Some people showed
interest on resurrecting the C backend but so far it didn't materialize.
> Does this seem feasible at all?
Feasible? yes. Practical? I don't think so. But that depends on your
specific goals, of course.
> How much in terms of variable names
> etc. could be retained in this manner?
I don't think that the resulting C code would be pleasant to read, and
most of the original Fortran names (except perhaps for function names)
would be lost.

DragonEgg only converts GCC's IR to LLVM IR. And -march=c is C backend. We
used it for a while last year, but its support has been dropped several
months ago. There are people, who are still using it privately, as far as I
know.

- D.

2013/3/1 Philipp Schwaha <philipp at schwaha.net>
> hi!
>
> I would like to know if it is feasible to use the dragon egg gcc plugin to
> automatically convert fortran code to c. Having found that it is possible
> to output llvm byte code back to c (at least something like this gave me
> this impression/hope: llc -march=c -o test.c) I am hoping to use dragon egg
> to generate the byte code from fortran 90 which than output to c.
> Does this seem feasible at all? How much in terms of variable names etc.
> could be retained in this manner?
>
> thanks for any suggestions or comments
>    Philipp
> ______________________________**_________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>
http://lists.cs.uiuc.edu/**mailman/listinfo/llvmdev<http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev>
>
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Thank you for your reply Dmitry!

It would not be too great a deal, if I need to use previous versions as
long as it would get the desired results :)
Would the code from the IR be portable to different C compilers? I
guess the resulting C code will not have too much resemblance to the input?

cheers
	Philipp

On 03/01/2013 05:02 PM, Dmitry Mikushin wrote:
> DragonEgg only converts GCC's IR to LLVM IR. And -march=c is C backend.
> We used it for a while last year, but its support has been dropped
> several months ago. There are people, who are still using it privately,
> as far as I know.
> 
> - D.
> 
> 2013/3/1 Philipp Schwaha <philipp at schwaha.net <mailto:philipp at
schwaha.net>>
> 
>     hi!
> 
>     I would like to know if it is feasible to use the dragon egg gcc
>     plugin to automatically convert fortran code to c. Having found that
>     it is possible to output llvm byte code back to c (at least
>     something like this gave me this impression/hope: llc -march=c -o
>     test.c) I am hoping to use dragon egg to generate the byte code from
>     fortran 90 which than output to c.
>     Does this seem feasible at all? How much in terms of variable names
>     etc. could be retained in this manner?
> 
>     thanks for any suggestions or comments
>        Philipp
>     _________________________________________________
>     LLVM Developers mailing list
>     LLVMdev at cs.uiuc.edu <mailto:LLVMdev at cs.uiuc.edu>        
>     http://llvm.cs.uiuc.edu
>     http://lists.cs.uiuc.edu/__mailman/listinfo/llvmdev
>     <http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev>
> 
>

Hello all,

I have played a little bit with the lli interpreter - realising that not 
all of the intrinsic functions have been implemented.
Digging a bit deeper I have prepared a small patch to extend the 
intrinsinc lowering capability.
As of now only llvm.umul.with.overflow is added - in order to verify if 
I have got the point ... comments welcome.

The second change is more a question ...
Is there a reason for the interpreter to omit the new line after its  
"About to interpret: " debug message ?
In my opinion the output arrangement is better with adding line breaks 
after every instruction - rather than printing them endlessly.

Finally since I'm not sure the modification as such is fine - I was also 
not sure wheter llvm-commits at cs.uiuc.edu would have been the better list.
Choosen llvmdev as I included questions ...

/Andreas
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