[1] RFR (S) 8179019: Correct range checks for command-line options ArraycopySrcPrefetchDistance and ArraycopyDstPrefetchDistance

[Zoltán Majó]

P.S.: Sorry for the error in the subject: I suggest this change for JDK 
10 (and not 1.0).

On 04/24/2017 05:20 PM, Zoltán Majó wrote:
> Hi,
>
>
> please review the following fix for 8179019.
> https://bugs.openjdk.java.net/browse/JDK-8179019
> http://cr.openjdk.java.net/~zmajo/8179019/webrev.00/
>
> Currently, the HotSpot allows Arraycopy{Src|Dst}PrefetchDistance only 
> one value. Before JDK-8078554, values in the interval [0, 4096] were 
> allowed (without explicit checking, though).
>
> This change extends the set of values allowed to the interval [0, 
> 4031]. We need the high bound 4032 (instead of 4096) because of [1]: 
> the largest value of offset is 64, so 4031 + 64 = 4095 is the maximum 
> that fits into the signed range of 13 bits. The change also includes 
> suggestions by Vladimir K [2] to avoid using too large immediate values.
>
> I tested the change manually with some values from both ends of the 
> range and also with JPRT (incl. the currently disabled 
> TestOptionsWithRanges.java test).
>
> Thank you!
>
> Best regards,
>
>
> Zoltan
>
> [1] 
> http://hg.openjdk.java.net/jdk10/hs/hotspot/file/1617b39a1ae4/src/cpu/sparc/vm/stubGenerator_sparc.cpp#l2128
> [2] 
> https://bugs.openjdk.java.net/browse/JDK-8179019?focusedCommentId=14071776&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14071776
>