[15] RFR(S): 8241909: Remove useless code cache lookup in frame::patch_pc

[Tobias Hartmann]

Vladimir, Dean, thanks for the review!

Best regards,
Tobias

On 31.03.20 21:36, Dean Long wrote:
> +1
> 
> dl
> 
> On 3/31/20 10:42 AM, Vladimir Kozlov wrote:
>> Good.
>>
>> thanks,
>> Vladimir
>>
>> On 3/31/20 1:45 AM, Tobias Hartmann wrote:
>>> Hi,
>>>
>>> please review the following patch:
>>> https://bugs.openjdk.java.net/browse/JDK-8241909
>>> http://cr.openjdk.java.net/~thartmann/8241909/webrev.00/
>>>
>>> The code cache lookup in frame::patch_pc [1] is useless because the method is only called from
>>> frame::deoptimize and vframeArrayElement::unpack_on_stack where pc is always part of _cb.
>>>
>>> If the method is called from frame::deoptimize [2], pc is either _cb->deopt_mh_handler_begin() or
>>> _cb->deopt_handler_begin(). Both are part of _cb.
>>>
>>> If the method is called from vframeArrayElement::unpack_on_stack [3], _frame is an interpreter frame
>>> and therefore _frame._cb is the interpreter buffer blob. pc is only set in this method and always
>>> points to an interpreter entry which is part of the interpreter buffer blob.
>>>
>>> Thanks,
>>> Tobias
>>>
>>> [1] http://hg.openjdk.java.net/jdk/jdk/file/ee44884f3ab8/src/hotspot/cpu/x86/frame_x86.cpp#l265
>>> [2] http://hg.openjdk.java.net/jdk/jdk/file/ee44884f3ab8/src/hotspot/share/runtime/frame.cpp#l287
>>> [3]
>>> http://hg.openjdk.java.net/jdk/jdk/file/ee44884f3ab8/src/hotspot/share/runtime/vframeArray.cpp#l303
>>>
>