llvm dev - May 2009 - [LLVMdev] llvm address of

I'm trying to generate the equivalent of this function dynamically in llvm
(a la http://llvm.org/docs/tutorial/JITTutorial1.html) but after half a day
of searching I still haven't found how to create the equivalent of the &
(address of) operator in the llvm API, more exactly how do I obtain the i8*
from the i32 below

void fn(int x)
{
   another_fn(&x);
}

thanks for any suggestions
Paul
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On 2009-05-24 19:42, Paul Martin wrote:
> I'm trying to generate the equivalent of this function dynamically in
> llvm (a la http://llvm.org/docs/tutorial/JITTutorial1.html) but after
> half a day of searching I still haven't found how to create the
> equivalent of the & (address of) operator in the llvm API, more
> exactly how do I obtain the i8* from the i32 below
>   
> void fn(int x) 
> { 
>    another_fn(&x); 
> } 
>   
You should create a temporary variable on the stack, store the value of
'x' to it,
and use the address of that variable as argument to another_fn.

You can simply run your example on llvm-gcc/clang with -emit-llvm -S,
and you'll see how it can be done.

Best regards,
--Edwin

Thanks Edwin,
I got it

Paul
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2009/5/24 Paul Martin <srucnoc at gmail.com>:
> I'm trying to generate the equivalent of this function dynamically in
llvm
> (a la http://llvm.org/docs/tutorial/JITTutorial1.html) but after half a day
> of searching I still haven't found how to create the equivalent of the
&
> (address of) operator in the llvm API, more exactly how do I obtain the i8*
> from the i32 below
>
> void fn(int x)
> {
>    another_fn(&x);
> }
>
My favourite way is to use http://llvm.org/demo/ , which compiles this

void another_fn(int*);

int fn(int x, int y)
{
   another_fn(&x);
   int z = x + y;
   return z;
}

into this

define i32 @fn(i32 %x, i32 %y) nounwind {
entry:
	%x_addr = alloca i32, align 4		; <i32*> [#uses=3]
	store i32 %x, i32* %x_addr
	call void @another_fn(i32* %x_addr) nounwind
	%0 = load i32* %x_addr, align 4		; <i32> [#uses=1]
	%1 = add i32 %0, %y		; <i32> [#uses=1]
	ret i32 %1
}

declare void @another_fn(i32*)