[9] RFR (S): 8172844: Assert fails in deoptimization due to original PC at the end of code section

[Rickard Bäckman]

On 01/19, Vladimir Kozlov wrote:
> Looks good to me too.
> 
> I am wonder if we have other places where we need to use
> insts_contains_inclusive().

Probably. It could also be problematic if we ever did something like
stub_contains(pc). Which would have been true in this case.
I checked the code and we don't have any such cases.

Another solution would be to always insert at least 1 hlt
instruction after a call that isn't supposed to return. 
Or at least always if the call is the last instruction in the last block to be
emitted.

/R

> 
> Thanks,
> Vladimir
> 
> On 1/19/17 5:36 AM, Zoltán Majó wrote:
> >Hi Rickard,
> >
> >
> >On 01/19/2017 02:22 PM, Rickard Bäckman wrote:
> >>Looks good to me.
> >
> >thank you for the review and for the suggestions.
> >
> >>
> >>Some clean up if you don't mind.
> >>
> >>frame_aarch64.inline.hpp:
> >>
> >>85     assert(((CompiledMethod*)_cb)->insts_contains(_pc), "original
> >>PC must be in CompiledMethod");
> >>should use _cb->as_compiled_method() instead of the cast.
> >>
> >>frame_x86.inline.hpp:
> >>same as above.
> >
> >That makes sense. Here is the updated webrev:
> >http://cr.openjdk.java.net/~zmajo/8172844/webrev.01/
> >
> >Thank you!
> >
> >Best regards,
> >
> >
> >Zoltan
> >
> >>
> >>Thanks
> >>/R
> >>
> >>On 01/19, Zoltán Majó wrote:
> >>>Hi,
> >>>
> >>>
> >>>please review the fix for 8172844.
> >>>
> >>>https://bugs.openjdk.java.net/browse/JDK-8172844
> >>>http://cr.openjdk.java.net/~zmajo/8172844/webrev.00/
> >>>
> >>>The assert checking the "original pc" (i.e., the pc that was on the
> >>>stack before the stack location was overwritten to point to the
> >>>deoptimization handler) is too strict. If the last instruction of
> >>>the (to-be-)deoptimized method is a call, the pc will point to the
> >>>instruction following the call. That instruction is outside of the
> >>>code section (as the call is the last instruction in the code
> >>>section).
> >>>
> >>>I suggest we relax the assert to accept the original pc being at the
> >>>end of the code section as well. I tested the change with JPRT and
> >>>locally with the reproducer, the failure did not appear. RBT is in
> >>>progress.
> >>>
> >>>Thank you!
> >>>
> >>>Best regards,
> >>>
> >>>
> >>>Zoltan
> >>>
> >