RFR(XS): 8144852: Corrupted oop in nmethod

[Dean Long]

[adding hotspot-runtime-dev]

On 12/11/2015 3:49 AM, Vladimir Ivanov wrote:
> Dean, thanks for taking care of it.
>
> Can oopDesc::print_value_on and print_value_on_maybe_null be enhanced 
> instead to handle non_oop_word case (in addition to NULL case)?
>

I thought of that, but didn't want to add 
print_value_on_maybe_null_or_non_oop :-)

If you feel strongly about that, then I should probably get input from 
runtime too, since I think they own that code.

> Also, the following is slightly misleading since metadata pointers 
> aren't oops:
>  void nmethod::print_recorded_metadata() {
> +    if (m == (Metadata*)Universe::non_oop_word()) {
> +      tty->print("non-oop word");
>

Would "non-metadata word" be better?

dl

> Best regards,
> Vladimir Ivanov
>
> On 12/11/15 6:36 AM, Dean Long wrote:
>> https://bugs.openjdk.java.net/browse/JDK-8144852
>> http://cr.openjdk.java.net/~dlong//8144852/webrev/
>>
>> The fix for [1] introduced new functions nmethod::print_recorded_oops
>> and nmethod::print_recorded_metadata that print all oop and metadata
>> values in an nmethod.  Currently NULL values are handled OK, but
>> Universe::non_oop_word values cause a crash.
>>
>> (This bug is marked confidential because it was reported against one of
>> our closed ports.)
>>
>> dl
>>
>> [1]     JDK-8072008: Emit direct call instead of linkTo* for recursive
>> indy/MH.invoke* calls