RFR(XS): JDK-8068655 frame::safe_for_sender() computes incorrect sender_sp value for interpreted frames

[Frederic Parain]

Hi Dean,

When unextended_sp is not specified, it is set to the sp value.

However, after your question, I realized that my fix was not
correct but worked because the is_interpreted_frame_valid() had
a bug too, it uses sp() where unextended_sp() should be used.

Checking the history of these files, is_interpreted_frame_valid() has
been written before the distinction between raw sp and unextended sp
has been introduced in the frame class. Unfortunately, when
unextended_sp was added, is_interpreted_frame_valid() has not been
updated.

Here's a new webrev where safe_for_sender computes both raw_sp and
unextended_sp, and is_interpreted_frame_valid() checks the frame
size using unextended_sp instead of raw sp.

http://cr.openjdk.java.net/~fparain/8068655/webrev.01/

I also added more comments.

Note that I only modify one test in is_interpreted_frame_valid().
Use of sp() or unextended_sp() could be discussed for each test,
but in their current form they are wrong.

Thanks,

Fred

On 26/01/2015 20:40, Dean Long wrote:
> In sender_for_interpreter_frame(), we set the raw sender_sp but also
> unextended_sp.  Should
> safe_for_sender() be doing the same?
>
> dl
>
> On 1/26/2015 6:40 AM, Frederic Parain wrote:
>> Greetings,
>>
>> Please review this small fix in the frame verification code.
>> The bug report includes a detailed description of the issue.
>>
>> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8068655
>>
>> Webrev:
>> http://cr.openjdk.java.net/~fparain/8068655/webrev.00/
>>
>> Thanks,
>>
>> Fred
>>
>

-- 
Frederic Parain - Oracle
Grenoble Engineering Center - France
Phone: +33 4 76 18 81 17
Email: Frederic.Parain at oracle.com