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

[Vladimir Kozlov]

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
>