RFR (S) 8176580: [ppc, s390] CRC32C: wrong checksum result in some cases

[Zoltán Majó]

Hi Lutz,


I can sponsor the change once it's reviewed.

Best regards,


Zoltan


On 03/14/2017 09:16 AM, Schmidt, Lutz wrote:
>
> Dear all,
>
> may I kindly request reviews for my small bugfix? And somebody 
> volunteering as a sponsor would be welcome as well.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8176580 
> <https://bugs.openjdk.java.net/browse/JDK-8176580>
>
> Webrev: http://cr.openjdk.java.net/~lucy/webrevs/8176580/ 
> <http://cr.openjdk.java.net/%7Elucy/webrevs/8176580/>
>
> Almost two weeks ago, I had contributed CRC32C intrinsic 
> implementations for ppc and s390. The arguments passed to the 
> intrinsics differ slightly from those passed to the CRC32 intrinsics. 
> Instead of passing the byte array length directly, it has to be 
> calculated from the offset and the end index values.
>
> This difference was not accounted for in 
> templateInterpreterGenerator_{ppc|s390}.cpp as well as in 
> c1_LIRGenerator_{ppc|s390}.cpp. The fix just adds the missing 
> subtraction, and adjusts some comments. For the bug to become visible, 
> it is necessary to calculate a CRC32C checksum from a byte array being 
> accessed with a non-zero offset. The call to the intrinsic has to 
> originate from the interpreter or from a c1-compiled method.
>
> This change is “platform only”. No changes to shared code.
>
> Thank you!
>
> Lutz
>