RFR: 8322294: Cleanup NativePostCallNop [v3]

[Andrew Haley]

On Sat, 23 Dec 2023 23:29:11 GMT, Richard Reingruber <rrich at openjdk.org> wrote:

>> This is a refactoring/cleanup of `NativePostCallNop` that simplifies the ppc64 port (dependent pr https://github.com/openjdk/jdk/pull/17171).
>> 
>> * `frame::get_oop_map()` is moved to shared code
>> 
>> * encoding / decoding details of the oopmap slot and the CodeBlob offset are moved from shared code to the platform dependent implementations of `bool NativePostCallNop::patch(int32_t oopmap_slot, int32_t cb_offset)` and `bool NativePostCallNop::decode(int32_t& oopmap_slot, int32_t& cb_offset)`
>> 
>> The change passed our CI testing. JTReg tests: tier1-4 of hotspot and jdk. All of Langtools and jaxp. SPECjvm2008, SPECjbb2015, Renaissance Suite, and SAP specific tests.
>> All testing was done with fastdebug and release builds on the main platforms and also on Linux/PPC64le and AIX.
>> 
>> EDIT 2023-12-22: Statistics
>> 
>> The statistical numbers were generated with release builds. For riscv64 I used qemu.
>> The variance is high on all platforms. Up to 80% I think. Numbers with fastdebug are also very different.
>> Nevertheless, they are consistent within one run, and I'd expect errors in encoding or decoding to manifest in the numbers.
>> 
>> | test/jdk/java/lang/Thread/virtual/stress/Skynet.java | x86_64: base | x86_64: pr | aarch64: base | aarch64: pr | riscv64: base | riscv64: pr |
>> |------------------------------------------------------|--------------|------------|---------------|-------------|---------------|-------------|
>> | PCN lookup success                                   | 17517455     | 15339681   | 13179049      | 15980253    | 19400110      | 30017193    |
>> | PCN lookup failure                                   | 328164       | 372555     | 237617        | 138164      | 415341        | 586476      |
>> | PCN decode success                                   | 17513991     | 15336485   | 13176061      | 15977651    | 19397398      | 30014226    |
>> | PCN decode failure                                   | 3464         | 3196       | 2988          | 2602        | 2712          | 2967        |
>> | PCN patch success                                    | 2676         | 2465       | 2459          | 2089        | 2214          | 2259        |
>> | PCN patch cb offset failure                          | 0            | 0          | 0             | 0           | 0             | 0           |
>> | PCN patch oopmap slot failure                        | 0            | 0          | 0             | 0           | 0             | 0           |
>> 
>> 
>> | SpecJVM2008 compil...
>
> Richard Reingruber has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add newline

Looks good. I was initially a bit worried it'd restrict the flexibility of ports to use custom encodings, but I don't think that's a problem.

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

Marked as reviewed by aph (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/17150#pullrequestreview-1795553240