<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">I found the problem, and it is not specific to the backport per se: there are several places where `==` is used to compare `ClassDesc` instances, particularly in the stack map generator. This usually works on JDK 24 or later, but fails on 23 or earlier. The critical clue was when I accidentally ran the backport version of the test on JDK 24 and it passed - telling me that the problem was a JDK behavioral difference.</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Dec 12, 2024 at 1:42 PM David Lloyd <<a href="mailto:david.lloyd@redhat.com" target="_blank">david.lloyd@redhat.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">Hmm. I will try to come up with a more concise reproducer. Maybe it's a problem with my class hierarchy resolver, or some other configuration that I have locally.</div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif"><br></div><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">BTW the example class is from io.smallrye.reactive:mutiny:2.6.2, sorry I failed to specify that. Thanks for looking into it, I'll see if I can make a minimal reproducer.</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Dec 12, 2024 at 1:32 PM Chen Liang <<a href="mailto:chen.l.liang@oracle.com" target="_blank">chen.l.liang@oracle.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>




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Hmm, couldn't reproduce with a local JDK mainline build (25) and the latest smallrye mutiny 2.7.0. (It also appears from bci that your example is an older version of mutiny). I changed the class java/util/ServiceLoader to Dummy in jshell and cannot reproduce
 this issue; cannot reproduce with stack maps recomputation either. Here's the javap output of the transformed results.</div>
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  static {};</div>
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    descriptor: ()V</div>
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    flags: (0x0008) ACC_STATIC</div>
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    Code:</div>
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      stack=2, locals=3, args_size=0</div>
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         0: ldc_w         #304                // String mutiny.disableCallBackDecorators</div>
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         3: invokestatic  #306                // Method java/lang/Boolean.getBoolean:(Ljava/lang/String;)Z</div>
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         6: putstatic     #203                // Field DISABLE_CALLBACK_DECORATORS:Z</div>
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         9: ldc_w         #312                // class io/smallrye/mutiny/infrastructure/ExecutorConfiguration</div>
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        12: invokestatic  #561                // Method Dummy.load:(Ljava/lang/Class;)Ljava/util/ServiceLoader;</div>
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        15: astore_0</div>
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        16: aload_0</div>
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        17: invokevirtual #212                // Method java/util/ServiceLoader.iterator:()Ljava/util/Iterator;</div>
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        20: astore_1</div>
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        21: aload_1</div>
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        22: invokeinterface #216,  1          // InterfaceMethod java/util/Iterator.hasNext:()Z</div>
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        27: ifeq          61</div>
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        30: aload_1</div>
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        31: invokeinterface #221,  1          // InterfaceMethod java/util/Iterator.next:()Ljava/lang/Object;</div>
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        36: checkcast     #312                // class io/smallrye/mutiny/infrastructure/ExecutorConfiguration</div>
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        39: astore_2</div>
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        40: aload_2</div>
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        41: invokeinterface #314,  1          // InterfaceMethod io/smallrye/mutiny/infrastructure/ExecutorConfiguration.getDefaultWorkerExecutor:()Ljava/util/concurrent/Executor;</div>
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        46: ldc_w         #318                // String executor</div>
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        49: invokestatic  #167                // Method io/smallrye/mutiny/helpers/ParameterValidation.nonNull:(Ljava/lang/Object;Ljava/lang/String;)Ljava/lang/Object;</div>
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        52: checkcast     #320                // class java/util/concurrent/Executor</div>
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        55: invokestatic  #32                 // Method setDefaultExecutor:(Ljava/util/concurrent/Executor;)V</div>
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        58: goto          64</div>
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        61: invokestatic  #322                // Method setDefaultExecutor:()V</div>
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        64: invokestatic  #324                // Method reload:()V</div>
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        67: invokestatic  #327                // Method resetCanCallerThreadBeBlockedSupplier:()V</div>
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        70: getstatic     #241                // Field io/smallrye/mutiny/infrastructure/Infrastructure$PrintAndDumpThrowableConsumer.INSTANCE:Lio/smallrye/mutiny/infrastructure/Infrastructure$PrintAndDumpThrowableConsumer;</div>
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        73: putstatic     #155                // Field droppedExceptionHandler:Ljava/util/function/Consumer;</div>
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        76: getstatic     #271                // Field io/smallrye/mutiny/infrastructure/Infrastructure$PrintOperatorEventOperatorLogger.INSTANCE:Lio/smallrye/mutiny/infrastructure/Infrastructure$PrintOperatorEventOperatorLogger;</div>
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        79: putstatic     #260                // Field operatorLogger:Lio/smallrye/mutiny/infrastructure/Infrastructure$OperatorLogger;</div>
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        82: sipush        128</div>
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        85: putstatic     #16                 // Field multiOverflowDefaultBufferSize:I</div>
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        88: bipush        32</div>
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        90: putstatic     #20                 // Field bufferSizeXs:I</div>
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        93: sipush        256</div>
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        96: putstatic     #23                 // Field bufferSizeS:I</div>
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        99: return</div>
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      LocalVariableTable:</div>
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        Start  Length  Slot  Name   Signature</div>
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           40      18     2  next   Lio/smallrye/mutiny/infrastructure/ExecutorConfiguration;</div>
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           16      54     0 executorLoader   Ljava/util/ServiceLoader;</div>
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           21      49     1 iterator   Ljava/util/Iterator;</div>
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      LocalVariableTypeTable:</div>
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        Start  Length  Slot  Name   Signature</div>
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           16      54     0 executorLoader   Ljava/util/ServiceLoader<Lio/smallrye/mutiny/infrastructure/ExecutorConfiguration;>;</div>
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           21      49     1 iterator   Ljava/util/Iterator<Lio/smallrye/mutiny/infrastructure/ExecutorConfiguration;>;</div>
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      LineNumberTable:</div>
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        line 39: 0</div>
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        line 42: 9</div>
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        line 47: 58</div>
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        line 48: 61</div>
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      StackMapTable: number_of_entries = 2</div>
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        frame_type = 253 /* append */</div>
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          offset_delta = 61</div>
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          locals = [ class java/util/ServiceLoader, class java/util/Iterator ]</div>
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        frame_type = 2 /* same */</div>
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Regards, Chen</div>
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</div></blockquote></div><div><br clear="all"></div><div><br></div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature"><div dir="ltr">- DML • he/him<br></div></div>
</blockquote></div><div><br clear="all"></div><div><br></div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature"><div dir="ltr">- DML • he/him<br></div></div>