llvm dev - Jun 2010 - [LLVMdev] For clarifying the "<Result>" in Instructions

Hi all, 

In the language specifications, many instructions have this form:

  <result> = ...
  
So, where is "<result>" defined? Is it an integral part of an
instruction?
Consider the "getelementptr" instruction: 

  <result> = getelementptr <pty>* <ptrval>{, <ty>
<idx>}*

How is the "<result>" represented? 

Best, 
Xiaolong

Yes, it's an integral part of the Instruction.  You can change it by
providing a name when you create the instruction.

Reid

On Thu, Jun 10, 2010 at 8:34 AM, Xiaolong Tang <xiaolong.snake at
gmail.com> wrote:
> Hi all,
>
> In the language specifications, many instructions have this form:
>
>  <result> = ...
>
> So, where is "<result>" defined? Is it an integral part of
an instruction?
> Consider the "getelementptr" instruction:
>
>  <result> = getelementptr <pty>* <ptrval>{, <ty>
<idx>}*
>
> How is the "<result>" represented?
>
> Best,
> Xiaolong
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

Hello Reid, 

Thanks. 
> Yes, it's an integral part of the Instruction.  You can change it by
> providing a name when you create the instruction.
Following your hint, can I understand in this following way?
 
The name (denoted by "<result>") is actually a referrer to the
instruction .
Consider this instruction: 
  %this_addr = alloca %struct.String*             ; <%struct.String**>
[#uses=4]
Here "%this_addr" (which is not a argument) is actually a string. 
Am I right? 

And this name is recorded in the symbol table of a module.  In case that an
instruction does not have a name, what then happens? I mean, will the
symbol table contains an entry for it?

Thanks, 

Best, 
Xiaolong
 
> On Thu, Jun 10, 2010 at 8:34 AM, Xiaolong Tang <xiaolong.snake at
gmail.com> wrote:
> >
> > In the language specifications, many instructions have this form:
> >
> >  <result> = ...
> >
> > So, where is "<result>" defined? Is it an integral
part of an instruction?
> > Consider the "getelementptr" instruction:
> >
> >  <result> = getelementptr <pty>* <ptrval>{,
<ty> <idx>}*
> >
> > How is the "<result>" represented?