RFR: 8202978: Incorrect tmp register passed to MacroAssembler::load_mirror()

[coleen.phillimore at oracle.com]

Yes, this looks good.  I'm glad that works out.
thanks,
Coleen

On 5/16/18 4:22 AM, Per Liden wrote:
> On 05/16/2018 08:58 AM, Per Liden wrote:
>> On 05/15/2018 10:25 PM, coleen.phillimore at oracle.com wrote:
>>>
>>> Hi Per,
>>
>> Hi Coleen,
>>
>>>
>>> It's calling a static native function so might not be totally 
>>> performance neutral.
>>> It looks like rax is scratch there.  Can you try that?   Sorry I 
>>> didn't figure out that r11 is rscratch2.
>>
>> I looks like you're right, rax seems to be used as scratch here. I'll 
>> run some tests with that and get back.
>
> Ok, changed to rax and ran it through testing without finding any 
> problems.
>
> Updated webrev: http://cr.openjdk.java.net/~pliden/8202978/webrev.1
>
> /Per
>
>>
>> Thanks!
>>
>> /Per
>>
>>>
>>> Thanks,
>>> Coleen
>>>
>>> On 5/11/18 8:48 AM, Per Liden wrote:
>>>> On 05/11/2018 02:32 PM, Vladimir Kozlov wrote:
>>>>> Looks good.
>>>>
>>>> Thanks Vladimir!
>>>>
>>>>> Is this new code? Should we backport it otherwise?
>>>>
>>>> Yes, this is new code, i.e. it's not in JDK 10 or older. Also, it 
>>>> just so happens that this bug doesn't affect the existing GC, only 
>>>> GCs which do load barriers (like ZGC), which is why it hasn't been 
>>>> caught before.
>>>>
>>>> /Per
>>>>
>>>>>
>>>>> Thanks,
>>>>> Vladimir K
>>>>>
>>>>> On 5/11/18 1:31 AM, Per Liden wrote:
>>>>>> On x86, MacroAssembler::load_mirror() defaults to using rscratch2 
>>>>>> as tmp register, unless something else is specified. In 
>>>>>> TemplateInterpreterGenerator::generate_native_entry() we call 
>>>>>> load_mirror(), but the rscratch2 register is already in use in 
>>>>>> this context, which obviously leads to problems. This is not a 
>>>>>> performance critical path, so we should just pass noreg as the 
>>>>>> tmp register.
>>>>>>
>>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8202978
>>>>>> Webrev: http://cr.openjdk.java.net/~pliden/8202978/webrev.0
>>>>>>
>>>>>> Testing: passes hs-tier{1,2}
>>>>>>
>>>>>> /Per
>>>