[PATCH] D53588: [hot-cold-split] split more than a cold region per function

[Vedant Kumar via Phabricator via llvm-commits]

vsk added a comment.

In https://reviews.llvm.org/D53588#1280639, @hiraditya wrote:

> For splitting more than one cold region, maintaining a DT maybe expensive but we don't have to do that. All we need is to 'color/mark' the blocks which we want to outline. In the next iteration the colored blocks need not be considered. It may be slightly non-trivial in a general case where coloring SEME and reasoning about DT/PDT of blocks which are non-colored. What we can do is in the subsequent iterations we can take a sub-graph which do not intersect anywhere except at entry or exit. This way DT/PDT will still be preserved in the non-intersecting regions. I think jump-threading also works(should work) on similar lines.


I'm prototyping a patch along these lines and will try to share it soon. Outlining non-intersecting sub-graphs is key to the approach. The idea is to build a worklist of all (possibly multiple-entry) outlining regions up front, then extract+outline sub-graphs from each region until the worklist is empty.


https://reviews.llvm.org/D53588