Baffled asks: what does post_call_nop() do?

[Andrew Haley]

I'm seeing this in one of my Scoped benchmarks:

  5.30%    0x00007f0f811f0080:   mov    rsi,QWORD PTR [rsp]
           0x00007f0f811f0084:   nop
           0x00007f0f811f0085:   nop
           0x00007f0f811f0086:   nop
           0x00007f0f811f0087:   call   0x00007f0f8111f520           ; ImmutableOopMap {[0]=Oop [64]=Oop [72]=Oop [80]=Oop [88]=Oop }
                                                                     ;*invokevirtual consume {reexecute=0 rethrow=0 return_oop=0}
                                                                     ; - org.sample.generated.ThreadLocalTest_getSC_jmhTest::getSC_avgt_jmhStub at 22 (line 239)
                                                                     ;   {optimized virtual_call}
 71.87%    0x00007f0f811f008c:   nop    DWORD PTR [rax+rax*1+0x0]    ;*invokevirtual consume {reexecute=0 rethrow=0 return_oop=0}
                                                                     ; - org.sample.generated.ThreadLocalTest_getSC_jmhTest::getSC_avgt_jmhStub at 22 (line 239)
          ;; B16: #	out( B11 B17 ) <- in( B15 )  Freq: 64789.4
           0x00007f0f811f0094:   mov    r10,QWORD PTR [rsp+0x40]
           0x00007f0f811f0099:   movzx  r10d,BYTE PTR [r10+0x94]     ;*invokestatic scopedCache {reexecute=0 rethrow=0 return_oop=0}
                                                                     ; - java.lang.Scoped::getObject at 6 (line 76)
                                                                     ; - java.lang.MyVariable_1::get at 5

So, about 72% of my total runtime is being accounted against post_call_nop() !

Is there any reason why this isn't just a bogus result? I'm not
actually using Fibers or anything like them.

-- 
Andrew Haley  (he/him)
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
https://keybase.io/andrewhaley
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