[Polly] [ScopInliner] [WIP] Teach ScopInliner to inline not-fully-scop'd functions.

[bollu]

Summary

Relax the constraints that ScopInliner looks for. Also allow it to pick up
functions whose *unique child* of the entry block is a Scop.

TODO: Look into why this crashes on COSMO.

[bollu]

• Use LegacyInlinerBase as the starting point for our inliner pass.
• Cache inlining results because polyhedral analysis is expensive.

[bollu]

• [Diff fix] Upload correct arc diff.

[bollu]

lib/Transform/ScopInliner.cpp

90

Not sure what polly convention is on this: I create a lambda and immediately evaluate it so I can mark the outer variable as const. It's a nice way to split off coherent sub-checks IMO.

97

Same immediately-invoke-lambda pattern used here.

[singam-sanjay]

lib/Transform/ScopInliner.cpp

89

"Whether a child of the top-level region contains a SCoP" ?

92

You're just checking for one of the children of the TopLevelRegion to be a SCoP ? How is it fine for one of the children to not be a SCoP ?

[philip.pfaffe]

As far as I can tell, you're only looking at ValidRegions here, thus you are ignoring second-to-top-level regions that are not scoppable. What if those regions have sideeffects?