RFR: 8338365: [PPC64, s390] Out-of-bounds array access in secondary_super_cache

[Martin Doerr]

On Thu, 15 Aug 2024 07:59:20 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Port for s390x and PPC for the bug: [JDK-8337958](https://bugs.openjdk.org/browse/JDK-8337958), Out-of-bounds array access in secondary_super_cache
>
> src/hotspot/cpu/s390/macroAssembler_s390.cpp line 3323:
> 
>> 3321: 
>> 3322:   // The bitmap is full to bursting.
>> 3323:   z_cghi(r_array_length, Klass::SECONDARY_SUPERS_BITMAP_FULL - 2);
> 
> Suggestion:
> 
>   z_chi(r_array_length, Klass::SECONDARY_SUPERS_BITMAP_FULL - 2);
> 
> This probably doesn't matter, but it's a 32-bit length.

Correct, chi would be cleaner. cghi works too, because the length is loaded as 32 bit value. (The length is loaded as unsigned 32 bit with zero extend. Not sure if this is ideal, but negative length should not occur AFAIK.)

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PR Review Comment: https://git.openjdk.org/jdk/pull/20578#discussion_r1718162545