[PATCH] D30631: [BPI] Use metadata info before any other heuristics

[Serguei Katkov via Phabricator via llvm-commits]

skatkov added a comment.

Hi Chandler, please take a look at my example from https://reviews.llvm.org/D30633.  The story is the same, profiling in metadata may say us that probability of unreachable block is zero (and it is more accurate than our heuristic) while we override this proflining data with our heuristic value causing the unreachable block is hotter than "normal" exit from the loop.

I tried to generailze the summary and do not use some specific example. I can put an example to the description if you want with the next version of the patch.

In general, to me the metadata is something user of LLVM would like us to follow. I do not see any reason to violate user's choice in this case until it breaks something. If metadata is wrong then user should fix the metadata, no need to fix it on our side.


https://reviews.llvm.org/D30631