[llvm] [SamplePGO] Support -salvage-stale-profile without probes too (PR #86116)

[Lei Wang via llvm-commits]

https://github.com/wlei-llvm approved this pull request.

LGTM, thanks.  Just a friendly heads-up, there is a bug related to callee profile matches, and I'm working on the fix(see #85715), it works for checksum(probe-based) profile. But as Wenlei pointed out,  there is no checksum thing for AutoFDO, so even the user function code is not changed, i,e. the profile is not stale, all functions(after the fix, all callees) will run the "stale" profile matching, and it might not be a no-op(e.g. cold or optimized-out callsite might not show in the profile, hopefully cold callsite are insignificant, but I'm not sure) and might cause negative effect to this perfectly matched case. 

https://github.com/llvm/llvm-project/pull/86116