llvm dev - Jul 2017 - loop canonical variables

Hello,
I need to perform the analysis of loop induction variables. However, as I
understood, directly it is possible to extract only a canonical induction
variable which is only one. If I have multiple induction variables with the
step not one, are there any methods to extract their phi node?

        int a[10];
        int b[10];
        for (int i = 0, j = 1; i < 10, j < 10; i++, j+=2) {
                a[i] = i+1;
                b[j] = j+1;
        }
        printf("%d",(b[1] + a[1]));
        return (b[1] + a[1]);

this is a brief example, I want to track i and j (smth is not initialized
in this code, but it doesn't matter)
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20170725/5f3b4ab0/attachment.html>

There is Loop::getCanonicalInductionVariable()

You may need to run the "-indvars" (IndVarSimplify) pass before it
returns a value. I am not sure it normalizes the step size to 1 in all
cases.

Michael

2017-07-25 18:12 GMT+02:00 Anastasiya Ruzhanskaya via llvm-dev
<llvm-dev at lists.llvm.org>:
> Hello,
> I need to perform the analysis of loop induction variables. However, as I
> understood, directly it is possible to extract only a canonical induction
> variable which is only one. If I have multiple induction variables with the
> step not one, are there any methods to extract their phi node?
>
>         int a[10];
>         int b[10];
>         for (int i = 0, j = 1; i < 10, j < 10; i++, j+=2) {
>                 a[i] = i+1;
>                 b[j] = j+1;
>         }
>         printf("%d",(b[1] + a[1]));
>         return (b[1] + a[1]);
>
> this is a brief example, I want to track i and j (smth is not initialized
in
> this code, but it doesn't matter)
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>

I call this function and it returns only "i" in my example.  Are there
any
ways to return "j" also?

2017-07-25 19:11 GMT+02:00 Michael Kruse <llvmdev at meinersbur.de>:
> There is Loop::getCanonicalInductionVariable()
>
> You may need to run the "-indvars" (IndVarSimplify) pass before
it
> returns a value. I am not sure it normalizes the step size to 1 in all
> cases.
>
> Michael
>
> 2017-07-25 18:12 GMT+02:00 Anastasiya Ruzhanskaya via llvm-dev
> <llvm-dev at lists.llvm.org>:
> > Hello,
> > I need to perform the analysis of loop induction variables. However,
as I
> > understood, directly it is possible to extract only a canonical
induction
> > variable which is only one. If I have multiple induction variables
with
> the
> > step not one, are there any methods to extract their phi node?
> >
> >         int a[10];
> >         int b[10];
> >         for (int i = 0, j = 1; i < 10, j < 10; i++, j+=2) {
> >                 a[i] = i+1;
> >                 b[j] = j+1;
> >         }
> >         printf("%d",(b[1] + a[1]));
> >         return (b[1] + a[1]);
> >
> > this is a brief example, I want to track i and j (smth is not
> initialized in
> > this code, but it doesn't matter)
> >
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20170725/bc99ef42/attachment.html>