async-profiler: Unknown Java Frame on JDK-8180450 reproducer

MInimal (benchmark) code to reproduce it using

# JMH version: 1.35
# VM version: JDK 11.0.16.1, OpenJDK 64-Bit Server VM, 11.0.16.1+1

import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.infra.Blackhole;

import java.util.Objects;
import java.util.concurrent.TimeUnit;

@State(Scope.Thread)
@Measurement(iterations = 10, time = 200, timeUnit = TimeUnit.MILLISECONDS)
@Warmup(iterations = 10, time = 200, timeUnit = TimeUnit.MILLISECONDS)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
@Fork(2)
public class RequireNonNullCheckcastScalability {
    public interface InternalContext extends Context {
        // Internal Framework API
        boolean isDuplicated();
    }

    public interface Context {
        // some public API
    }

    public static class DuplicatedContext implements InternalContext {


        @Override
        public boolean isDuplicated() {
            return true;
        }
    }

    public static class NonDuplicatedContext implements InternalContext {

        @Override
        public boolean isDuplicated() {
            return false;
        }
    }

    private Context ctx;

    @Setup
    public void init(Blackhole bh) {
        ctx = new NonDuplicatedContext();
        // let's warm it enough to get it compiled with C2 (by default)
        for (int i = 0; i < 11000; i++) {
            bh.consume(isDuplicated());
        }
        // deopt on warmup
        ctx = new DuplicatedContext();
    }

    private static boolean isDuplicatedContext(Context message) {
        Context actual = Objects.requireNonNull(message);
        return ((InternalContext) actual).isDuplicated();
    }

    @Benchmark
    @Threads(2)
    @CompilerControl(CompilerControl.Mode.DONT_INLINE)
    public boolean isDuplicated() {
        return isDuplicatedContext(ctx);
    }
}

Flamegraph is

Reporting a huge number of unknown Java frames.

perfasm shows that:

....[Hottest Region 1]..............................................................................
c2, level 4, io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicated, version 2, compile id 546 

                   0x00007fc3dc300d44: shl    $0x3,%r10
                   0x00007fc3dc300d48: movabs $0x800000000,%r12
                   0x00007fc3dc300d52: add    %r12,%r10
                   0x00007fc3dc300d55: xor    %r12,%r12
                   0x00007fc3dc300d58: cmp    %r10,%rax
                   0x00007fc3dc300d5b: jne    0x00007fc3d484b080  ;   {runtime_call ic_miss_stub}
                   0x00007fc3dc300d61: data16 xchg %ax,%ax
                   0x00007fc3dc300d64: nopl   0x0(%rax,%rax,1)
                   0x00007fc3dc300d6c: data16 data16 xchg %ax,%ax
                 [Verified Entry Point]
   0.24%           0x00007fc3dc300d70: mov    %eax,-0x14000(%rsp)
   0.36%           0x00007fc3dc300d77: push   %rbp
                   0x00007fc3dc300d78: sub    $0x20,%rsp         ;*synchronization entry
                                                                 ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicated@-1 (line 63)
   0.71%           0x00007fc3dc300d7c: mov    0xc(%rsi),%r11d    ;*getfield ctx {reexecute=0 rethrow=0 return_oop=0}
                                                                 ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicated@1 (line 63)
                   0x00007fc3dc300d80: mov    0x8(%r12,%r11,8),%r10d  ; implicit exception: dispatches to 0x00007fc3dc300e58
   0.44%           0x00007fc3dc300d85: movabs $0x800000000,%rsi
                   0x00007fc3dc300d8f: lea    (%rsi,%r10,8),%rsi
   0.50%           0x00007fc3dc300d93: mov    0x20(%rsi),%r10
   2.87%           0x00007fc3dc300d97: movabs $0x840091818,%rax  ;   {metadata('io/forked/franz/benchmarks/RequireNonNullCheckcastScalability$Context')}
                   0x00007fc3dc300da1: cmp    %rax,%r10
          ╭        0x00007fc3dc300da4: jne    0x00007fc3dc300ddb  ;*checkcast {reexecute=0 rethrow=0 return_oop=0}
          │                                                      ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicatedContext@4 (line 55)
          │                                                      ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicated@4 (line 63)
   0.21%  │   ↗    0x00007fc3dc300da6: movabs $0x840091a18,%rax  ;   {metadata('io/forked/franz/benchmarks/RequireNonNullCheckcastScalability$InternalContext')}
          │   │    0x00007fc3dc300db0: cmp    %rax,%r10
          │╭  │    0x00007fc3dc300db3: jne    0x00007fc3dc300e0c
   0.03%  ││  │ ↗  0x00007fc3dc300db5: lea    (%r12,%r11,8),%rbp  ;*checkcast {reexecute=0 rethrow=0 return_oop=0}
          ││  │ │                                                ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicatedContext@9 (line 56)
          ││  │ │                                                ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicated@4 (line 63)
   0.41%  ││  │ │  0x00007fc3dc300db9: mov    0x8(%rbp),%r11d
   1.66%  ││  │ │  0x00007fc3dc300dbd: cmp    $0x80123c8,%r11d   ;   {metadata('io/forked/franz/benchmarks/RequireNonNullCheckcastScalability$DuplicatedContext')}
          ││╭ │ │  0x00007fc3dc300dc4: jne    0x00007fc3dc300e3c  ;*invokeinterface isDuplicated {reexecute=0 rethrow=0 return_oop=0}
          │││ │ │                                                ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicatedContext@12 (line 56)
          │││ │ │                                                ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicated@4 (line 63)
   0.62%  │││ │ │  0x00007fc3dc300dc6: mov    $0x1,%eax          ;*synchronization entry
          │││ │ │                                                ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicatedContext@-1 (line 55)
          │││ │ │                                                ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicated@4 (line 63)
          │││ │ │  0x00007fc3dc300dcb: add    $0x20,%rsp
          │││ │ │  0x00007fc3dc300dcf: pop    %rbp
   0.77%  │││ │ │  0x00007fc3dc300dd0: mov    0x108(%r15),%r10
          │││ │ │  0x00007fc3dc300dd7: test   %eax,(%r10)        ;   {poll_return}
   2.43%  │││ │ │  0x00007fc3dc300dda: retq   
   0.33%  ↘││ │ │  0x00007fc3dc300ddb: push   %rax
           ││ │ │  0x00007fc3dc300ddc: mov    %rax,%rax
           ││ │ │  0x00007fc3dc300ddf: mov    0x28(%rsi),%rdi
  20.88%   ││ │ │  0x00007fc3dc300de3: mov    (%rdi),%ecx
   1.18%   ││ │ │  0x00007fc3dc300de5: add    $0x8,%rdi
           ││ │ │  0x00007fc3dc300de9: test   %rax,%rax
           ││ │ │  0x00007fc3dc300dec: repnz scas %es:(%rdi),%rax
  11.16%   ││ │ │  0x00007fc3dc300def: pop    %rax
   2.72%   ││╭│ │  0x00007fc3dc300df0: jne    0x00007fc3dc300dfa
           ││││ │  0x00007fc3dc300df6: mov    %rax,0x20(%rsi)
   0.36%   ││↘╰ │  0x00007fc3dc300dfa: je     0x00007fc3dc300da6
           ││   │  0x00007fc3dc300dfc: mov    $0xffffffde,%esi
           ││   │  0x00007fc3dc300e01: mov    %r11d,%ebp
           ││   │  0x00007fc3dc300e04: data16 xchg %ax,%ax
           ││   │  0x00007fc3dc300e07: callq  0x00007fc3d4849e00  ; ImmutableOopMap{rbp=NarrowOop }
           ││   │                                                ;*checkcast {reexecute=0 rethrow=0 return_oop=0}
           ││   │                                                ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicatedContext@4 (line 55)
           ││   │                                                ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicated@4 (line 63)
           ││   │                                                ;   {runtime_call UncommonTrapBlob}
   0.18%   ↘│   │  0x00007fc3dc300e0c: push   %rax
            │   │  0x00007fc3dc300e0d: mov    %rax,%rax
            │   │  0x00007fc3dc300e10: mov    0x28(%rsi),%rdi
  20.08%    │   │  0x00007fc3dc300e14: mov    (%rdi),%ecx
   1.36%    │   │  0x00007fc3dc300e16: add    $0x8,%rdi
            │   │  0x00007fc3dc300e1a: test   %rax,%rax
   0.98%    │   │  0x00007fc3dc300e1d: repnz scas %es:(%rdi),%rax
  10.75%    │   │  0x00007fc3dc300e20: pop    %rax
   3.35%    │  ╭│  0x00007fc3dc300e21: jne    0x00007fc3dc300e2b
            │  ││  0x00007fc3dc300e27: mov    %rax,0x20(%rsi)
   0.44%    │  ↘╰  0x00007fc3dc300e2b: je     0x00007fc3dc300db5
            │      0x00007fc3dc300e2d: mov    $0xffffffde,%esi
            │      0x00007fc3dc300e32: mov    %r11d,%ebp
            │      0x00007fc3dc300e35: xchg   %ax,%ax
            │      0x00007fc3dc300e37: callq  0x00007fc3d4849e00  ; ImmutableOopMap{rbp=NarrowOop }
            │                                                    ;*checkcast {reexecute=0 rethrow=0 return_oop=0}
            │                                                    ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicatedContext@9 (line 56)
            │                                                    ; - io.forked.franz.benchmarks.RequireNonNullCheckcastScalability::isDuplicated@4 (line 63)
            │                                                    ;   {runtime_call UncommonTrapBlob}
            ↘      0x00007fc3dc300e3c: cmp    $0x8012383,%r11d   ;   {metadata('io/forked/franz/benchmarks/RequireNonNullCheckcastScalability$NonDuplicatedContext')}
                   0x00007fc3dc300e43: jne    0x00007fc3dc300e4c
....................................................................................................
  85.02%  <total for region 1>

The most of the cost is (as expected) while interacting with Klass::secondary_super_cache and Klass::secondary_supers (array’s length read), that’s the code injected by https://github.com/openjdk/jdk11/blob/37115c8ea4aff13a8148ee2b8832b20888a5d880/src/hotspot/cpu/x86/macroAssembler_x86.cpp#L5503

How to improve the accuracy of the profiler’s output? Is it AGCT to be blamed instead?

Many thanks!!