RFR: 8357258: x86: Improve receiver type profiling reliability [v5]

Aleksey Shipilev shade at openjdk.org
Wed Nov 26 15:55:38 UTC 2025


> See the bug for discussion what issues current machinery has. 
> 
> This PR executes the plan outlined in the bug:
>  1. Common the receiver type profiling code in interpreter and C1
>  2. Rewrite receiver type profiling code to only do atomic receiver slot installations
>  3. Trim `C1OptimizeVirtualCallProfiling` to only claim slots when receiver is installed 
> 
> This PR does _not_ do atomic counter updates themselves, as it may have much wider performance implications, including regressions. This PR should be at least performance neutral.
> 
> Additional testing:
>   - [x] Linux x86_64 server fastdebug, `compiler/`
>   - [x] Linux x86_64 server fastdebug, `all`

Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 15 commits:

 - Merge branch 'master' into JDK-8357258-x86-c1-optimize-virt-calls
 - Tighten up some more
 - Offset is always rscratch1, no need to save it
 - Grossly simplify register shuffling
 - More asserts
 - More comment touchups
 - Inline code comments
 - Mention the updater in ReceiverTypeData
 - type_profile -> profile_receiver_type
 - Stylistic: remove redundant assert
 - ... and 5 more: https://git.openjdk.org/jdk/compare/c028369d...c441209a

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

Changes: https://git.openjdk.org/jdk/pull/25305/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25305&range=04
  Stats: 383 lines in 8 files changed: 167 ins; 197 del; 19 mod
  Patch: https://git.openjdk.org/jdk/pull/25305.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25305/head:pull/25305

PR: https://git.openjdk.org/jdk/pull/25305


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