RFR: 8262891: Compiler implementation for Pattern Matching for switch (Preview) [v4]

[Rémi Forax]

On Tue, 25 May 2021 12:20:02 GMT, Jan Lahoda <jlahoda at openjdk.org> wrote:

> Thanks Evgeny, I'll take a look.
> 
> @forax, do you mean why there is "0" in:
> 11: invokedynamic #13, 0
> ?

Not this one, the one on the stack.

7: iconst_0   <---- this zero
8: istore_3
9: aload_2
10: iload_3
11: invokedynamic #13, 0 // InvokeDynamic
#0:typeSwitch:(Ljava/lang/Object;I)I

Why the descriptor is (Ljava/lang/Object;I)I instead of (Ljava/lang/Object;)I,
what is the semantics associated to that integer ?

> The "0" is an artifact of how invokedynamic is represented in the classfile (invokedynamic, 2 bytes of constant pool reference, byte 0, byte 0) - javap shows the value of the first zero byte. That is probably not needed anymore, but there is nothing special in this patch, I think - all invokedynamic calls look like this, AFAIK.

I know that a little to well, i'm one of the guys behind the design of indy :)

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