[llvm-branch-commits] [llvm] [BOLT][PAC] Warn about synchronous unwind tables (PR #165227)

[Gergely Bálint via llvm-branch-commits]

bgergely0 wrote:

As the related issue states:

> Example: when applying BOLT to llama.cpp, this is seen in the logs: Ignored 1633 functions (99.03%) because of CFI inconsistencies. The huge % of ignored functions makes BOLT useless in such cases.

I think the double-digit territory is a good boundary to start emitting this warning. After all, we don't check/don't know if this is the reason for the errors, but the higher the percentage the more likely that this is the issue. Low-percentage issues can be from older compiler versions emitting CFIs incorrectly (as I've seen while testing the work).

So the 10% is a "magic constant" and is up for discussion, I think it is a reasonable value to start emitting warnings. 

https://github.com/llvm/llvm-project/pull/165227