Infinite Loop in Pattern switch with guarded patterns in JDK 17 ea27/ea36

[Jan Lahoda]

Hi Manoj,


thanks for the report. There is:

https://bugs.openjdk.java.net/browse/JDK-8269141

filled for this.


Thanks,

      Jan


On 24. 06. 21 2:56, Manoj Palat wrote:
> Hi,
> I see an infinite loop with with JDK 17 ea27/ea26 for pattern switch;
> given switch pattern with guarded pattern case:
> public class X {
>   private static void foo(Object o) {
>     switch (o) {
>       case String s1 && s1.length()>1: System.out.println("Guarded"); 
> break;
>       default : System.out.println("Object");
>     }
>   }
>    public static void main(String[] args) {
>     foo(new Object());
>   }
> }
> compiles fine with ea27 (and ea26), but while running gets into an 
> infinite loop.
>
> The disassembled code shows that there is a "goto 9" at 73 (to restart 
> the switch) - I believe that this goto here is an error as switch need 
> not be restarted at default; omitting the generation of this "goto" 
> should remove the infinite loop.
>  private static void foo(java.lang.Object arg0);
>      ...
>      9  aload_1
>     10  iload_2
>     11  invokedynamic 0 typeSwitch(java.lang.Object, int) : int [13]
>     16  lookupswitch default: 65
>           case 0: 36
>     ....
>     65  getstatic java.lang.System.out : java.io.PrintStream [23]
>     68  ldc <String "Object"> [37]
>     70  invokevirtual java.io.PrintStream.println(java.lang.String) : 
> void [31]
>     73  goto 9 <== this is an error
>     76  return
> Thanks,
> Manoj
> PS: Had sent a mail to jdk-dev, but I didn't see it in the list; also 
> raised bug with oracle internal id: 9070727
>
>
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