RFR: 8237521: Memory Access API fixes for 32-bit

[David Holmes]

On 24/01/2020 12:41 am, Andrew Haley wrote:
> On 1/23/20 10:22 AM, David Holmes wrote:
>> That aside IIRC the overflow check is not ideal here because we already
>> enter undefined behaviour territory inside align_up if we actually
>> overflow.
> 
> How is that possible? size_t is an unsigned type, and unsigned types
> never overflow.

Yes you are right, I was not recalling the rules correctly. So the 
addition to the size_t is guaranteed to wrap and so the < test is valid.

Sorry for the noise on that.

It may still be cleaner if the Java side enforces a maximum of 
Integer.MAX_VALUE for 32-bit.

Thanks,
David

> On a 32-bit box, 0 <= size < 2**32. So -- in theory at
> least -- you could allocate more than 2G.
>