RFR: 8300002: Performance regression caused by non-inlined hot methods due to post call noop instructions [v2]

[Erik Österlund]

On Fri, 13 Jan 2023 19:28:00 GMT, Sergey Kuksenko <skuksenko at openjdk.org> wrote:

> > As an alternative way to count nops, have you considered iterating over relocations and counting `post_call_nop_Reolcation`s then multiplying the count by `NativePostCallNop::instruction_size`? (So far, there's no `NativePostCallNop::instruction_size` declared on aarch64 and ppc, but that's the common pattern in nativeInst_*.hpp.)
> 
> 
> 
> It was my first draft which I didn't show here.
> 
> I just thought that the current way is more generic and doesn't have dependency on relocation size. In the future (if needed), such inline heuristic may be expanded by excluding some other instructions.
> 
> 

I agree with you. In fact I think we might want to do this route for generational ZGC as well. We don't want our different barriers to cause different inlining decisions. But if we go down that route, perhaps the name of the exclusion tool should be more generic?

-------------

PR: https://git.openjdk.org/jdk/pull/11958