[LLVMdev] Python Backend

[Wojciech Daniło]

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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