[PATCH] D75024: [SCCIterator] Check if a SCC is a natural loop.

Sun Feb 23 12:07:21 PST 2020

baziotis added a comment.

In D75024#1888381 <https://reviews.llvm.org/D75024#1888381>, @Meinersbur wrote:

> "ADT" stands for "Abstract Data Type". This use case is rather concrete. Unfortunately, LoopInfo ignores non-natural loops, but it would be the place for this.

So, a function that gets an SCC and decides if it's a loop, alright.

> IIUC, there will be an SCC only for an topmost loop including all its nested loop. Its not possible using SCCIterator to match a non-topmost loops.

Hmm, that's bizarre. Won't the SCCIterator go through all the SCCs? That is, let's say we have a topmost loop with blocks: A, B, C. And blocks B, C also form a loop.
Won't we get a separate SCC for A, B, C and B, C?

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https://reviews.llvm.org/D75024