[llvm-dev] ind variable

[Anastasiya Ruzhanskaya via llvm-dev]

The files of this strange pass are described here
http://reviews.legup.org/rLEGUP54ca7c2bb15d84116baf47bce67256d3803720d9  .
I wonderwhy the most uptodate -indvars pass can't do the same.

2017-08-09 14:18 GMT+02:00 Anastasiya Ruzhanskaya <
anastasiya.ruzhanskaya at frtk.ru>:

> Hello,
> I have this piece of code:
> int main() {
>         int m = 0;
> //      int i, j, k;
> //      int N = f()%10;
>         for (int l = 0; l < 1000; l+=4)
>                 printf("%d", l);
>
> I am sure, that llvm is capable to convert this into canonical induction
> variable, but even with O3
> define i32 @main() #0 {
>   br label %2
>
> ; <label>:1                                       ; preds = %2
>   ret i32 0
>
> ; <label>:2                                       ; preds = %0, %2
>   %l.01 = phi i32 [ 0, %0 ], [ %4, %2 ]
>   %3 = tail call i32 (i8*, ...) @printf(i8* nonnull getelementptr inbounds
> ([3 x i8], [3 x i8]* @.str, i64 0, i64 0), i32 %l.01)
>   %4 = add nuw nsw i32 %l.01, 4
>   %5 = icmp slt i32 %4, 1000
>   br i1 %5, label %2, label %1
> }
>
> I have this assembler.
> I know there is indvars2 pass ( it is under llvm license but used only in
> LegUp project - as I understood, surfing the Internet), which is good in
> changing induction variables.
>
> How can I achieve that this cycle will have a canonical indvar?
>
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