RFR (XS) 8215495: Always set isCopy

[David Holmes]

Hi Jc,

On 18/12/2018 8:12 am, JC Beyler wrote:
> Hi David,
> 
> I understand the rationale behind the "If the method does return NULL, 
> then isCopy's value is undefined". But what about 
> the DEFINE_GETSCALARARRAYELEMENTS case?
> 
> It does this:
>    if (len == 0) { \
>      /* Empty array: legal but useless, can't return NULL. \
>       * Return a pointer to something useless. \
>       * Avoid asserts in typeArrayOop. */ \
>      result = (ElementType*)get_bad_address(); \
> 
> Should we at least then put isCopy to JNI_FALSE in that case since it 
> does not return NULL and no exception is raised,

Sure - it's an odd corner case, but better not to leave isCopy 
potentially uninitialized.

Thanks,
David

> Thanks,
> Jc
> 
> 
> On Mon, Dec 17, 2018 at 1:29 PM David Holmes <david.holmes at oracle.com 
> <mailto:david.holmes at oracle.com>> wrote:
> 
>     Hi Jc,
> 
>     On 18/12/2018 3:42 am, JC Beyler wrote:
>      > Hi all,
>      >
>      > Could I get a review for this webrev:
>      >
>      > Webrev: http://cr.openjdk.java.net/~jcbeyler/8215495/webrev.00/
>      > Bug: https://bugs.openjdk.java.net/browse/JDK-8215495
> 
>     isCopy only has to be set if the method executes successfully
> 
>     "If isCopy is not NULL, then *isCopy is set to JNI_TRUE if a copy is
>     made; or it is set to JNI_FALSE if no copy is made."
> 
>     You can only make (or not) a copy if the operation actually
>     succeeds. So
>     before checking isCopy the caller must check for NULL and/or a pending
>     exception.
> 
>     I see no bug here.
> 
>     David
>     -----
> 
>      > Thanks,
>      > Jc
> 
> 
> 
> -- 
> 
> Thanks,
> Jc