Integrated: 8332111: [BACKOUT] A way to align already compiled methods with compiler directives

[Evgeny Astigeevich]

On Mon, 13 May 2024 13:03:26 GMT, Evgeny Astigeevich <eastigeevich at openjdk.org> wrote:

> Backout of [JDK-8309271](https://bugs.openjdk.org/browse/JDK-8309271) which has known bugs, possible bugs and performance issues. REDO work is tracked by [JDK-8331749](https://bugs.openjdk.org/browse/JDK-8331749).
> 
> Found bugs:
> - When refreshing `CompilerDirectivesAddDCmd::execute` will call `DirectivesStack::hasMatchingDirectives(mh, true)` which only considers the compiler directive which is on the top of the directives stack. As more than one directive can be added, `CompilerDirectivesAddDCmd::execute` will not behave as expected.
> - A Java method with old directives might be in the compilation queue. A request to recompile it with new directives will be ignored.
> 
> There are other concerns: bugs and performance issues.
> 
> Possible bugs:
> - `has_matching_directives` might not be cleared. A nmethod might get into the unloading state before `CodeCache::recompile_marked_directives_matches`. If the nmethod has been used to mark a Java method and it is the only nmethod, there will be no nmethod in CodeCache to reach the Java method to clear the mark.
> - A Java method might have been compiled with new directives before `CodeCache::recompile_marked_directives_matches`. `CodeCache::recompile_marked_directives_matches` will recompile it again.
> - JIT compiler might be compiling a Java method with old directives. A request to recompile it with new directives will be ignored.
> 
> Performance issues:
> - Usually directives are updated for a small number of Java methods. If CodeCache has thousands of nmethods, `CodeCache::recompile_marked_directives_matches` will be traversing nmethods most of which don't need recompilation.
> 
> The backout is not clean because of removal of `CompiledMethod`.
> 
> Tested with release and fastdebug builds: tier1  and tier2 passed.

This pull request has now been integrated.

Changeset: 1a944478
Author:    Evgeny Astigeevich <eastigeevich at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/1a944478a26a766f5a573a1236b642d8e7b0685c
Stats:     380 lines in 15 files changed: 3 ins; 347 del; 30 mod

8332111: [BACKOUT] A way to align already compiled methods with compiler directives

Reviewed-by: shade, kvn

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PR: https://git.openjdk.org/jdk/pull/19215