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

[Sergey Kuksenko]

On Thu, 12 Jan 2023 18:11:22 GMT, Vladimir Ivanov <vlivanov 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.

> BTW I'm curious why there's no relocation registered on PPC while both x86 and aarch64 have it.

I don't know the answer.

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