[PATCH] D112696: CycleInfo: Introduce cycles as a generalization of loops

[Sameer Sahasrabuddhe via Phabricator via llvm-commits]

sameerds added inline comments.


================
Comment at: llvm/docs/CycleTerminology.rst:29
+   --- Thus, the header of the cycle is implementation-defined.)
+4. The *root cycle* consists of all basic blocks of a function. Its
+   header is the entry block of the function.
----------------
ruiling wrote:
> Why do we need this `root cycle`? All the blocks of a function mostly do not even form a strongly connected region. And this is quite different from the way LoopInfo works.
> Why do we need this `root cycle`? All the blocks of a function mostly do not even form a strongly connected region. And this is quite different from the way LoopInfo works.

I should copy a comment from GenericCycleInfo class to this spec. Essentially, the "root" is a placeholder cycle that allows CycleInfo to be treated as a single tree. Then we can use GraphTraits as follows (see `validateTree()` in GenericCycleImpl.h):

```
for (const CycleT *cycle : depth_first(getRoot())) { ... }
```



Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D112696/new/

https://reviews.llvm.org/D112696