RFR: 8334866: Improve Speed of ElfDecoder source search [v5]

[Christian Hagedorn]

On Fri, 24 Oct 2025 17:25:34 GMT, Kerem Kat <krk at openjdk.org> wrote:

>> Kerem Kat has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 15 additional commits since the last revision:
>> 
>>  - Merge branch 'master' into elfdecoder-JDK-8334866
>>  - fix DWARF_LOG_INFO
>>  - Comment on ArangesCache
>>  - Fix secondary sort order and comment
>>  - Remove move ctor of ArangesCache
>>  - Clarify when we can fallback to linear scan, which doesn't seem to allocate on the heap
>>  - Move ArangesCache into DebugAranges, and DebugAranges into DwarfFile
>>  - inline sort
>>  - goto considered harmful
>>  - Use QuickSort::sort instead of qsort
>>  - ... and 5 more: https://git.openjdk.org/jdk/compare/c619b1d3...ae72cae8
>
> src/hotspot/share/utilities/elfFile.cpp line 818:
> 
>> 816:     case CacheHint::VALID:
>> 817:       return _cache.find_compilation_unit_offset(offset_in_library, compilation_unit_offset);
>> 818:     case CacheHint::TRY_LINEAR_SCAN:
> 
> Should we eliminate the fallback?

I'm not sure how often it happens but since we already have it implemented, it does not hurt to keep it for now. We could still come back later if we decide to no longer do a linear scan.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27337#discussion_r2464907296