RFR(T): 8249875: GCC 10 warnings -Wtype-limits with JFR code

[Yasumasa Suenaga]

Thanks Markus!

Yasumasa


On 2020/07/23 3:59, Markus Gronlund wrote:
> Looks good.
> 
> Thanks
> Markus
> 
> -----Original Message-----
> From: Yasumasa Suenaga <suenaga at oss.nttdata.com>
> Sent: den 22 juli 2020 16:46
> To: hotspot-jfr-dev at openjdk.java.net
> Subject: RFR(T): 8249875: GCC 10 warnings -Wtype-limits with JFR code
> 
> Hi all,
> 
> Please review this issue:
> 
>     JBS: https://bugs.openjdk.java.net/browse/JDK-8249875
>     webrev: http://cr.openjdk.java.net/~ysuenaga/JDK-8249875/webrev.00/
> 
> I saw some warnings in JFR code when I tried to build OpenJDK with GCC 10.1.1 on Fedora 32:
> 
> ```
> /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/jfr/utilities/jfrHashtable.hpp:86:14: warning: comparison of unsigned expression in '>= 0' is always true [-Wtype-limits]
>      86 | assert(h >= 0 && h < _table_size, "Illegal hash value");
>         | ~~^~~~
> ```
> 
> ```
> /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/jfr/utilities/jfrDoublyLinkedList.hpp:138:17: warning: comparison of unsigned expression in '>= 0' is always true [-Wtype-limits]
>     138 | assert(_count >= 0, "invariant"); ```
> 
> Both `h` and `_cound` are unsigned type, so we can remove them.
> I think this is trivial change.
> 
> 
> Thanks,
> 
> Yasumasa
>