RFR: 8262891: Compiler implementation for Pattern Matching for switch (Preview) [v5]

[Evgeny Mandrikov]

On Thu, 27 May 2021 18:19:38 GMT, Rémi Forax <forax at openjdk.org> wrote:

>  in your example, there is no guard so no backward goto

@forax btw this example is not about switch pattern matching - it is about already existing string switch, where indy not involed �� 


  void example(java.lang.String);
    descriptor: (Ljava/lang/String;)V
    flags: (0x0000)
    Code:
      stack=2, locals=4, args_size=2
         0: aload_1
         1: astore_2
         2: iconst_m1
         3: istore_3
         4: aload_2
         5: invokevirtual #7                  // Method java/lang/String.hashCode:()I
         8: lookupswitch  { // 1
                      97: 28
                 default: 39
            }
        28: aload_2
        29: ldc           #13                 // String a
        31: invokevirtual #15                 // Method java/lang/String.equals:(Ljava/lang/Object;)Z
        34: ifeq          39
        37: iconst_0
        38: istore_3
        39: iload_3
        40: lookupswitch  { // 1
                       0: 60
                 default: 68
            }
        60: getstatic     #19                 // Field java/lang/System.out:Ljava/io/PrintStream;
        63: ldc           #13                 // String a
        65: invokevirtual #25                 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
        68: return
      LineNumberTable:
        line 3: 0
        line 5: 60
        line 7: 68
      StackMapTable: number_of_entries = 5
        frame_type = 253 /* append */
          offset_delta = 4
          locals = [ class java/lang/String, int ]
        frame_type = 23 /* same */
        frame_type = 10 /* same */
        frame_type = 20 /* same */
        frame_type = 249 /* chop */
          offset_delta = 7

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PR: https://git.openjdk.java.net/jdk/pull/3863