RFR 8159284: bigapps/Jetty - assert(jfa->last_Java_sp() > sp()) failed with tracing code in use

[Coleen Phillimore]

Fred, Thank you for reviewing this.

On 8/2/16 2:02 PM, Frederic Parain wrote:
> Coleen,
>
> src/cpu/aarch64/vm/frame_aarch64.cpp
>
>   line 116: return entry_frame_is_safe(thread);
>   line 207: return sender.is_entry_frame_safe(thread);
>
>   Method names are different, is it a typo?
>

Yes, it is a typo.  Thank you for catching it.

> src/cpu/sparc/vm/frame_sparc.cpp
>
>   No comments
>
> src/cpu/x86/vm/frame_x86.cpp
>
>   No comments
>
> src/share/vm/runtime/frame.cpp
>
>   No comments
>
> src/share/vm/runtime/frame.hpp
>
>   I would expect the new method name to be is_entry_frame_safe()
>   as most tester methods begin with "is_" but I this is just a
>   personal opinion.

I named it entry_frame_is_safe() because I thought it looked less 
redundant and more distinct in the code fragments where they occurred:

     // Entry frame checks
     if (is_entry_frame()) {
       // an entry frame must have a valid fp.

       if (!fp_safe) return false;

       return entry_frame_is_safe(thread);
     }

is_entry_frame_safe() looks like is_entry_frame() or implies it's a 
"safe" call to is_entry_frame.

I guess it is the standard to start with 'is' for these sorts of 
tests.   How about is_safe_entry_frame() ?

thanks,
Coleen

>
> Fred
>
> On 08/01/2016 07:38 PM, Coleen Phillimore wrote:
>> Summary: Test condition in assert in frame::safe_for_sender() for entry
>> frames and return false.
>>
>> This bug is for a confidential part of the project that needs more
>> robustness checks to verify that frame::sender() can be called.
>>
>> Also refactored into frame::entry_frame_is_safe() because these
>> platforms had the same code for entry frames to determine whether it is
>> still safe to trust this frame to call sender(). These platforms had
>> also the same assert in sender_for_entry_frame() that the sampling code
>> hit.
>>
>> Tested with our nightly tests on all platforms and bigapps/Jetty.
>>
>> open webrev at http://cr.openjdk.java.net/~coleenp/8159284.01/webrev
>>
>> Thanks,
>> Coleen
>>