[llvm] [llvm-profgen] Add an option to force marking the profile as preinlined (PR #156501)

[Lei Wang via llvm-commits]

wlei-llvm wrote:

> 
> I was thinking about `csspgo-replay-preinline`: https://github.com/llvm/llvm-project/blame/main/llvm/tools/llvm-profgen/CSPreInliner.cpp#L50

I see, thanks for the check! Seems like it's indeed equivalent, IIRC, the `ContextWasInlined` is from the leaf frame's dwarf/probe context so it should be same to the context directly from the length-1 call-stack (`-ignore-stack-samples`).

> 
> I thought we run pre-inliner as long as `csspgo-preinliner` is on, and that flag is on by default and also not affected by whether we ignore stack samples?
> 
> Judging from your change, it seems like we don't run pre-inliner for probe-only (`-ignore-stack-samples`)?

IIRC, csspgo-preinliner is only available in CS mode:  https://github.com/llvm/llvm-project/blob/main/llvm/tools/llvm-profgen/ProfileGenerator.cpp#L1109C7-L1115, so we don't run/have this for `-ignore-stack-samples`. For my previous experiments, I always use the `-ignore-stack-samples` mode because it consumes significantly less memory and running time. 



https://github.com/llvm/llvm-project/pull/156501