[llvm] [GVN][PGO] Skip GVN if entry BlockFreq is 0 (PR #166336)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 commented:

If this is to fix a compile time regression/issue, could there be some more investigation into what is actually causing it?

This seems like a very band-aid fix that might just paper over any actual issues.

https://github.com/llvm/llvm-project/pull/166336