[PATCH] D109354: [LoopBoundSplit] Check the start value of split cond AddRec

Wed Sep 8 11:42:36 PDT 2021

jaykang10 added a comment.

Sorry... I was wrong again...

>From the attached test to this patch, the AddRecSCEV of the split condition is `{%qqq,+,2}<nw><%for.body>` and the BoundSCEV is `%qqq`. The split condition `%.not9 = icmp ult i16 %t2, %qqq` is `false` at all iterations. In this case, we should not generate the pre-loop which has `true` split condition...

I am not sure there are passes to remove this conditional branch which has constant condition potentially at all iterations. For now, I will try to recognize this case and skip the transformation.

I have thought of the problem too complicated... I am sorry for wrong patch again... If you feel something wrong, please let me know.

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  https://reviews.llvm.org/D109354/new/

https://reviews.llvm.org/D109354