llvm dev - Oct 2012 - [LLVMdev] How can I find the LHS of the function call when traversing the function call

Hi All,

I am a new member in the group, have been doing some experiments with LLVM
IR.

I am facing issue with de-compiling the following instruction once it is
read,

 %var2  = call i8 @myfuncCall (i2 %var1)

In after I parse the file (lets say using parseIRFiles ).
I can see the instructions,( the function call instruction ), How can I get
the %var2 from the instruction/callInstruction ?

going thru the llvm installations cpp and .h files, it is not clear how do
I get the desired variable.

Thanks in Advance.

regards
Tarique
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On 10/8/2012 6:44 PM, tarique anwer wrote:
>
>   %var2  = call i8 @myfuncCall (i2 %var1)
>
> In after I parse the file (lets say using parseIRFiles ).
> I can see the instructions,( the function call instruction ), How can I
> get the %var2 from the instruction/callInstruction ?
>
> going thru the llvm installations cpp and .h files, it is not clear how
> do I get the desired variable.
The member function getName would return "var2" for it, but %var2 in 
here is a name of the value that is the function call instruction.  In 
general this doesn't have to be the name of the variable from the source 
code.


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Hi Tarique,
> I am a new member in the group, have been doing some experiments with LLVM
IR.
>
> I am facing issue with de-compiling the following instruction once it is
read,
>
>   %var2  = call i8 @myfuncCall (i2 %var1)
>
> In after I parse the file (lets say using parseIRFiles ).
> I can see the instructions,( the function call instruction ), How can I get
the
> %var2 from the instruction/callInstruction ?
%var2 *is* the call instruction.  Since LLVM IR is in SSA form, values like
%var2 are defined once and can't be redefined.  Thus there is no point in
trying to make a distinction between %var2 and the instruction defining it,
which is why LLVM doesn't even try to make a distinction: there is no
variable
%var2, there is only the instruction "call i8 @myfuncCall (i2 %var1)",
and
%var2 is just a name attached to it (use ->getName() on the instruction to
see
this).

Ciao, Duncan.
>
> going thru the llvm installations cpp and .h files, it is not clear how do
I get
> the desired variable.
>
> Thanks in Advance.
>
> regards
> Tarique
>
>
>
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