RFR: 8247666: Support Lambda proxy classes in static CDS archive [v5]

[Mandy Chung]

On Wed, 14 Oct 2020 16:24:47 GMT, Calvin Cheung <ccheung at openjdk.org> wrote:

>>>  `@lambda-proxy: LambHello run ()Ljava/lang/Runnable; ()V 6 LambHello lambda$main$0 ()V ()V`
>> 
>> Can you explain the format?
>
> `@lambda-proxy LambHello run ()Ljava/lang/Runnable; ()V REF_invokeStatic LambHello lambda$main$0 ()V ()V`
> means
> `@lambda-proxy <classname> <intf-method-name> <intf-method-sig> <bsm-arg0> <bsm-arg1a> <bsm-arg1b>  <bsm-arg1c> 
> <bsm-arg1d> <bsm-arg2>`
> It is a symbolic representation of a invoke dynamic constant pool entry.
> public class LambHello {
>     public static void main(String[] args) {
>         doit(() -> {
>             System.out.println("Hello from Lambda");
>         });
>     }
>     static void doit(Runnable t) {
>         t.run();
>     }
> }
> 
> An invoke dynamic constant pool of the above program is:
> ` -   7 : InvokeDynamic : bootstrap_method_index=43 name_and_type_index=8 arguments={50, 51, 50}`
> Other constant pool entries related to the above are:
>  -   8 : NameAndType : name_index=9 signature_index=10
>  -   9 : Utf8 : 'run'
>  -  10 : Utf8 : '()Ljava/lang/Runnable;'
> 
>  -  50 : MethodType : signature_index=6
>  -  51 : MethodHandle : ref_kind=6 ref_index=52
>  -  52 : Method : klass_index=12 name_and_type_index=53
>  -  53 : NameAndType : name_index=39 signature_index=6
> 
>  -   6 : Utf8 : '()V'
>  -  12 : Class : 'LambHello' {0x0000000800c10040}
>  -  39 : Utf8 : 'lambda$main$0'
> The info included in the class list are:
>     <classname>                  = LambHello
>     <intf-method-name>     = run
>     <intf-method-sig>         = ()Ljava/lang/Runnable;
>     <bsm-arg0>                   = ()V
>     <bsm-arg1a>                  = REF_invokeStatic
>     <bsm-arg1b>                  = LambHello
>     <bsm-arg1c>                  = lambda$main$0
>     <bsm-arg1d>                  = ()V
>     <bsm-arg2>                   = ()V

Since the class list file is not intended for users to edit/modify but rather a configuration file given
when -Xshare:dump is used, the format of `@lambda-proxy` entry is internal implementation details and so it's fine.

BTW:  for the method handle reference kind, does the entry have the value (e.g. 6) or the name ("REF_invokeStatic")?
I see both formats are described in your different replies.

> @lambda-proxy: LambHello run ()Ljava/lang/Runnable; ()V 6 LambHello lambda$main$0 ()V ()V
or
> @lambda-proxy LambHello run ()Ljava/lang/Runnable; ()V REF_invokeStatic LambHello lambda$main$0 ()V ()V

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PR: https://git.openjdk.java.net/jdk/pull/364