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Wojciech Daniło

2012-Nov-20 23:46 UTC

[LLVMdev] Python Backend

Hi!
I'm trying to write LLVM Python Backend (to generate Python code out of
LLVM IR)
I'm still learning LLVM and for now it is very hard to me to even create
simple taksk. I want you to ask 3 questions:

----------------------------------------------------------------------------------
1)
 I want to base on some existing code to learn how it was build. I wanted
to base on CBackend (which is no longer available from LLVM 3.0 up) and of
course it does not compile with LLVM 3.2 - giving a lot of errors:
(the code is taken from source of LLVM 3.0 and put into
$LLVMSRC/projects/<copy of sample project>/lib/Target/CBackend - I hope
this is good method to do it)
http://pastebin.com/dkbJWpgP
Does anybody have this example working under LLVM3.2? I have found on some
old mailing lists that CBackend was never working as  it should but it was
working for some simple examples - I'm looking for somethingl ike that in
LLVM 3.2.
If not, what is the best minimal example I can base onto writing my backend?

----------------------------------------------------------------------------------
2)
Maybe this question I will answer myself by analising some examples you'll
provide as answer to the first question, but maybe it will worth asking it
now.
So I want to know when to generate a class in Python. So far I know, that
in LLVM there are no classes, only functions, but when using the online
LLVM generator I can see, that when generating IR from C++ code, the
"class" keyword is stored inside of name (or something like name) of
function:

#include <stdio.h>
#include <stdlib.h>
class X{
public:
void f();
};
void X::f() { printf("inside f");}
int main() {  X x;  x.f();}

translates into:

[...]
define void @_ZN1X1fEv(%class.X* nocapture %this) nounwind uwtable align 2 {
  %1 = tail call i32 (i8*, ...)* @printf(i8* getelementptr inbounds
([9 x i8]* @.str, i64 0, i64 0))
  ret void
}

[...]


How can I access it inside of my function Pass to get know if it was
class or not?


----------------------------------------------------------------------------------

3)

Is there any manual that will help me discover all these advanced LLVM
features needed to write such backend? I have read LLVM Kaleidoscope
tutorials, some LLVM tutorials from IBM and lot of articles, but I
still feel that I have not knowledge enough.


Thank you :)
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Rafael Espíndola

2012-Nov-20 23:56 UTC

head link

[LLVMdev] Python Backend

On 20 November 2012 18:46, Wojciech Daniło <wojtek.danilo.ml at gmail.com>
wrote:> Hi!
> I'm trying to write LLVM Python Backend (to generate Python code out of
LLVM
> IR)
> I'm still learning LLVM and for now it is very hard to me to even
create
> simple taksk. I want you to ask 3 questions:
>
>
----------------------------------------------------------------------------------
> 1)
>  I want to base on some existing code to learn how it was build. I wanted
to
> base on CBackend (which is no longer available from LLVM 3.0 up) and of
> course it does not compile with LLVM 3.2 - giving a lot of errors:
> (the code is taken from source of LLVM 3.0 and put into
You might want to look at lib/Target/NVPTX/ for something that uses
the common codegen infrastructure.
> $LLVMSRC/projects/<copy of sample project>/lib/Target/CBackend - I
hope this
> is good method to do it)
> http://pastebin.com/dkbJWpgP
> Does anybody have this example working under LLVM3.2? I have found on some
> old mailing lists that CBackend was never working as  it should but it was
> working for some simple examples - I'm looking for somethingl ike that
in
> LLVM 3.2.
> If not, what is the best minimal example I can base onto writing my
backend?
>
>
----------------------------------------------------------------------------------
> 2)
> Maybe this question I will answer myself by analising some examples
you'll
> provide as answer to the first question, but maybe it will worth asking it
> now.
> So I want to know when to generate a class in Python. So far I know, that
in
> LLVM there are no classes, only functions, but when using the online LLVM
> generator I can see, that when generating IR from C++ code, the
"class"
> keyword is stored inside of name (or something like name) of function:
>
> #include <stdio.h>
> #include <stdlib.h>
> class X{
> public:
> void f();
> };
> void X::f() { printf("inside f");}
> int main() {  X x;  x.f();}
>
> translates into:
>
> [...]
>
> define void @_ZN1X1fEv(%class.X* nocapture %this) nounwind uwtable align 2
{
>   %1 = tail call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([9 x
> i8]* @.str, i64 0, i64 0))
>   ret void
> }
>
> [...]
>
>
> How can I access it inside of my function Pass to get know if it was class
> or not?
>
>
>
>
----------------------------------------------------------------------------------
>
> 3)
>
> Is there any manual that will help me discover all these advanced LLVM
> features needed to write such backend? I have read LLVM Kaleidoscope
> tutorials, some LLVM tutorials from IBM and lot of articles, but I still
> feel that I have not knowledge enough.
>
>
> Thank you :)
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

Eli Bendersky

2012-Nov-20 23:56 UTC

head link

[LLVMdev] Python Backend

>
----------------------------------------------------------------------------------
> 2)
> Maybe this question I will answer myself by analising some examples
you'll
> provide as answer to the first question, but maybe it will worth asking it
> now.
> So I want to know when to generate a class in Python. So far I know, that
in
> LLVM there are no classes, only functions, but when using the online LLVM
> generator I can see, that when generating IR from C++ code, the
"class"
> keyword is stored inside of name (or something like name) of function:
>
> #include <stdio.h>
> #include <stdlib.h>
> class X{
> public:
> void f();
> };
> void X::f() { printf("inside f");}
> int main() {  X x;  x.f();}
>
> translates into:
>
> [...]
>
> define void @_ZN1X1fEv(%class.X* nocapture %this) nounwind uwtable align 2
{
>   %1 = tail call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([9 x
> i8]* @.str, i64 0, i64 0))
>   ret void
> }
>
> [...]
>
>
> How can I access it inside of my function Pass to get know if it was class
> or not?
Why do you need to deconstruct C++ classes to generate Python code
from LLVM IR? What will you gain from that?
> 3)
>
> Is there any manual that will help me discover all these advanced LLVM
> features needed to write such backend? I have read LLVM Kaleidoscope
> tutorials, some LLVM tutorials from IBM and lot of articles, but I still
> feel that I have not knowledge enough.
I hope you ran into http://llvm.org/docs/WritingAnLLVMBackend.html

Eli

Wojciech Daniło

2012-Nov-21 00:10 UTC

head link

[LLVMdev] Python Backend

I will take a look into NVPTX.

I don't want to deconstruct C++ classes to generate Python code - I want to
generate Python backend :)
Its purpose is to be able to generate Python code from LLVM IR code (not
C++ code! - C++ code is needed for me only to get a sample IR code).

I want to write my custom compiler in the future and I want to be able to
output Python code from it (of course not only Python code - I want to be
able to output IR or bytecode also), so I though that writing Python
Backend (as a function pass) is the best solution. Am I wrong?

2012/11/21 Eli Bendersky <eliben at google.com>
> >
>
----------------------------------------------------------------------------------
> > 2)
> > Maybe this question I will answer myself by analising some examples
> you'll
> > provide as answer to the first question, but maybe it will worth
asking
> it
> > now.
> > So I want to know when to generate a class in Python. So far I know,
> that in
> > LLVM there are no classes, only functions, but when using the online
LLVM
> > generator I can see, that when generating IR from C++ code, the
"class"
> > keyword is stored inside of name (or something like name) of function:
> >
> > #include <stdio.h>
> > #include <stdlib.h>
> > class X{
> > public:
> > void f();
> > };
> > void X::f() { printf("inside f");}
> > int main() {  X x;  x.f();}
> >
> > translates into:
> >
> > [...]
> >
> > define void @_ZN1X1fEv(%class.X* nocapture %this) nounwind uwtable
align
> 2 {
> >   %1 = tail call i32 (i8*, ...)* @printf(i8* getelementptr inbounds
([9 x
> > i8]* @.str, i64 0, i64 0))
> >   ret void
> > }
> >
> > [...]
> >
> >
> > How can I access it inside of my function Pass to get know if it was
> class
> > or not?
>
> Why do you need to deconstruct C++ classes to generate Python code
> from LLVM IR? What will you gain from that?
>
> > 3)
> >
> > Is there any manual that will help me discover all these advanced LLVM
> > features needed to write such backend? I have read LLVM Kaleidoscope
> > tutorials, some LLVM tutorials from IBM and lot of articles, but I
still
> > feel that I have not knowledge enough.
>
> I hope you ran into http://llvm.org/docs/WritingAnLLVMBackend.html
>
> Eli
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