RFR: 8288534: Out of bound errors for memory segment access mentions wrong values [v2]

[Paul Sandoz]

On Thu, 16 Jun 2022 12:16:19 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> While playing with the API, I've realized that some of the out of bound error messgaes come out incorrectly.
>> 
>> This is because the bound check is performed as follows (to avoid overflow):
>> 
>> 
>> Objects.checkIndex(offset, this.length - length + 1);
>> 
>> 
>> So, if out-of-bounds access is detected, the resulting exception mentions the values of the first and second parameter, respectively - but since the second parameter is the result of a subtraction, it doesn't make sense.
>> 
>> The solution is not to use `Objects.checkIndex` directly, but, instead, drop down one level, and pass our own "IOOB formatter":
>> 
>> 
>> Preconditions.checkIndex(offset, this.length - length + 1, this);
>> 
>> 
>> Note that, in order to recover the correct values, the formatter needs to know the segment size - so I made `AbstractMemorySegment` act as a formatter (so we don't need to allocate in such a hot path).
>> 
>> The fix seems to bring back the desired messages - but I would like some confirmation that doing this won't disrupt intrinsification of the `checkIndex` method.
>
> Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add @ForceInline on AbstractLayout::byteSize

Marked as reviewed by psandoz (Reviewer).

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PR: https://git.openjdk.org/jdk19/pull/24