RFR: 8357514: Disable AOT caching for runtime stubs

[Ioi Lam]

On Thu, 22 May 2025 03:46:39 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> After [JDK-8354887](https://bugs.openjdk.org/browse/JDK-8354887) was integrated we hit strange failures which looks like memory stomps during our JCK testing of AOT new JEPs:
> 
> # Internal Error (/workspace/open/src/hotspot/share/opto/regmask.hpp:222), pid=4186624, tid=4186658
> # assert(_RM_UP[i] == 0) failed: _hwm too low: 5 regs at: 4
> 
> or
> 
> # Internal Error (/workspace/open/src/hotspot/share/opto/type.cpp:996), pid=2832821, tid=2832868
> # fatal error: meet not symmetric
> 
> or other strange issues during C2 compilation
> 
> After investigating (running tests in loop) I narrowed down the issue to AOT caching of C2 runtime stubs:
> 
> https://github.com/openjdk/jdk/blob/master/src/hotspot/share/opto/output.cpp#L3491
> 
> After internal discussion we decided disable all runtime stubs caching.
> There is no guarantee that we may not have issues with C1 stubs too.
> 
> I propose hard code AOTStubCaching flag to `false` value until the issue is solved.

test/hotspot/jtreg/runtime/cds/appcds/aotCode/AOTCodeFlags.java line 54:

> 52:         Tester t = new Tester();
> 53:         // Run only 2 modes (0 - no AOT code, 1 - AOT adapters) until stubs caching is restored
> 54:         for (int mode = 0; mode < 2; mode++) {

For tracking purposes, please add JDK-8357398 to the comment.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25379#discussion_r2101581623