[LLVMdev] Simple question

[Joey Gouly]

You can't. You have to use the value 12 directly.


On 16 March 2013 00:18, James Courtier-Dutton <james.dutton at gmail.com>wrote:

>
> On Mar 15, 2013 10:53 PM, "Óscar Fuentes" <ofv at wanadoo.es> wrote:
> >
> > James Courtier-Dutton <james.dutton at gmail.com> writes:
> >
> > > I think this is a very simple question, and it must just be missing
> something.
> > >
> > > I am looking for find out how to assign a constant integer value to
> > > the variable in llvm ir.
> > >
> > > The following returns 12, and %var2 = 12.
> > > ; ModuleID = 't.c'
> > > target datalayout =
> > >
> "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
> > > target triple = "x86_64-pc-linux-gnu"
> > >
> > > define i32 @test() nounwind readnone {
> > >   %var1 = xor i32 0, 0
> > >   %var2 = add i32 %var1, 12
> > >   ret i32 %var2
> > > }
> > >
> > > Why can't I do?:
> > > ; ModuleID = 't.c'
> > > target datalayout =
> > >
> "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
> > > target triple = "x86_64-pc-linux-gnu"
> > >
> > > define i32 @test() nounwind readnone {
> > >   %var2 = 12
> > >   ret i32 %var2
> > > }
> > >
> > > What is the simplest way to make %var2 = 12   ?
> >
> > To add to the other response, it is important to note that your %var1,
> > %var2 above are not variables at all, because they can't be reassigned
> > (i.e. they can't appear again on the left hand of a %varX = ...
> > expression.) They are just names for the values corresponding to the
> > instructions.
> >
>
> Ok, maybe i asked the wrong question.
> Instead of using the value 12 all the way through the llvm ir text file.
> How do i use %friendlyName instead?
> I.e. The equivalent of something like
> #define FriendlyName  12
> in C
>
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