RFR(xs): 8078666: JVM fastdebug build compiled with GCC 5 asserts with "widen increases"

[Vladimir Kozlov]

Looks reasonable. I will test it and push to hs-comp/hotspot.

Thanks,
Vladimir

On 4/29/15 12:56 AM, Severin Gehwolf wrote:
> Hi,
>
> Adding hotspot-dev for wider audience. IMHO hotspot should not rely on
> undefined behaviour (overflow on signed int/long is undefined) and this
> should get fixed.
>
> --Severin
>
> On Mon, 2015-04-27 at 16:18 +0200, Severin Gehwolf wrote:
>> Hi,
>>
>> Could somebody please review and sponsor the following patch?
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8078666
>> Webrev: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8078666/webrev.02/
>>
>> We've discovered this issue in Fedora where we were seeing a strange
>> memory leak issue of an OpenJDK build with GCC 5. More info in the bug.
>>
>> As it turns out, current hotspot relies on undefined behaviour in
>> normalize_int_widen()/normalize_long_widen() where an integer overflow
>> can occur on some inputs.
>>
>> The fix is to do the math on the unsigned type where overflows are well
>> defined.
>>
>> Thanks,
>> Severin
>>
>>
>>
>
>
>