llvm dev - Apr 2010 - [LLVMdev] How to get the left-hand operand of an instruction?

Hi,

I am a new novice of LLVM, and I want know how to get the left-hand operand
of an instruction?

For example:
how to get the %temp2 operand in the next instruction:

%temp2 = malloc i8, i32 %n


Thanks a lot!

Best Regards!
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Hi Qiuping yi,
> I am a new novice of LLVM, and I want know how to get the left-hand
> operand of an instruction?
>
> For example:
> how to get the %temp2 operand in the next instruction:
>
> %temp2 = malloc i8, i32 %n
there is no left-hand side, temp2 is just a name for the instruction.
Since the LLVM IR is in SSA form, registers have exactly one definition,
and thus there is no point in distinguishing between a register and the
instruction that defines it.  In short, whenever you would like to make
use of "%temp2", just use the instruction ("malloc i8, i32
%n") directly.

Ciao,

Duncan.

Yes, Duncan is right. You can use ("malloc i8, i32 %n") as a value
to mark its uses.

   cheers,

   Liu Jian
----
email to: gjk.liu at gmail.com


On Tue, Apr 6, 2010 at 5:03 PM, Duncan Sands <baldrick at free.fr> wrote:
> Hi Qiuping yi,
>
> > I am a new novice of LLVM, and I want know how to get the left-hand
> > operand of an instruction?
> >
> > For example:
> > how to get the %temp2 operand in the next instruction:
> >
> > %temp2 = malloc i8, i32 %n
>
> there is no left-hand side, temp2 is just a name for the instruction.
> Since the LLVM IR is in SSA form, registers have exactly one definition,
> and thus there is no point in distinguishing between a register and the
> instruction that defines it.  In short, whenever you would like to make
> use of "%temp2", just use the instruction ("malloc i8, i32
%n") directly.
>
> Ciao,
>
> Duncan.
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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Hi  Duncan,

I have catched your reply and solved the problem. Thank you for the
elaborate reply.


Best Regards!



2010/4/6 Duncan Sands <baldrick at free.fr>
> Hi increaseing, please ask on the list rather than writing to me directly.
> That way others can answer, and the discussion is archived for the benefit
> of people with the same question in the future.
>
> Best wishes,
>
> Duncan.
>
>  I have another question:
>> If I want to catch the point pointing to an allocated regin using
malloc
>> and its length(for example, x.p and n in the next statement), what
>> should I do?
>> x.p = malloc(n);
>> Thank you very much!
>> Best Regards!
>>
>>
>> 2010/4/6 Duncan Sands <baldrick at free.fr <mailto:baldrick at
free.fr>>
>>
>>
>>    Hi Qiuping yi,
>>
>>     > I am a new novice of LLVM, and I want know how to get the
left-hand
>>     > operand of an instruction?
>>     >
>>     > For example:
>>     > how to get the %temp2 operand in the next instruction:
>>     >
>>     > %temp2 = malloc i8, i32 %n
>>
>>    there is no left-hand side, temp2 is just a name for the
instruction.
>>    Since the LLVM IR is in SSA form, registers have exactly one
>> definition,
>>    and thus there is no point in distinguishing between a register and
the
>>    instruction that defines it.  In short, whenever you would like to
make
>>    use of "%temp2", just use the instruction ("malloc
i8, i32 %n")
>>    directly.
>>
>>    Ciao,
>>
>>    Duncan.
>>    _______________________________________________
>>    LLVM Developers mailing list
>>    LLVMdev at cs.uiuc.edu <mailto:LLVMdev at cs.uiuc.edu>
>>    http://llvm.cs.uiuc.edu <http://llvm.cs.uiuc.edu/>
>>
>>    http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>
>>
>
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