Adopting JEP 303 (Intrinsics for LDC and INVOKEDYNAMIC) into Amber

[Tagir Valeev]

Hello!

I tried to play with this, but still no success. Fresh build from
constant-folding branch. I tried to compile the following files:

// MH.java

import java.lang.invoke.*;
import java.lang.invoke.Constables.*;
import java.lang.reflect.*;

public class MH {
  private static void test() {
    System.out.println("Hello");
  }


  public static void main(String[] args) throws Throwable {
    final MethodHandle handle = Intrinsics.ldc(
     MethodHandleConstant.ofStatic(ClassConstant.of(MH.class), "test",
MethodTypeConstant.of(Constables.VOID)));
    handle.invokeExact();
  }

}

// VH.java
import java.lang.invoke.*;
import java.lang.invoke.Constables.*;
import java.lang.reflect.*;

public class VH {
  private static volatile int counter;

  private static final VarHandle COUNTER = Intrinsics.ldc(
     VarHandleConstant.ofStaticField(ClassConstant.of(VH.class), "counter",
Constables.INT));

  public static void main(String[] args) {
    System.out.println(COUNTER.getAndAdd(1));
    System.out.println(COUNTER.getAndAdd(1));
  }
}

Building with "javac -XDdoConstantFold=true MH.java" or "javac
-XDdoConstantFold=true VH.java",
javac silently exists without producing .class file or reporting any error.
Tried with -verbose, the output ends like this:

[loading /modules/java.base/java/lang/annotation/RetentionPolicy.class]
[loading /modules/java.base/java/lang/annotation/Target.class]
[loading /modules/java.base/java/lang/annotation/ElementType.class]
[checking VH]
[loading /modules/java.base/java/io/Serializable.class]
[loading /modules/java.base/java/lang/AutoCloseable.class]
[loading /modules/java.base/java/lang/Class.class]
[loading /modules/java.base/java/lang/invoke/Constable.class]
[loading /modules/java.base/java/lang/invoke/Intrinsics.class]
[total 1484ms]

Without  -XDdoConstantFold=true the class file is produced and dies like

Exception in thread "main" java.lang.UnsupportedOperationException: no
reflective access
at java.base/java.lang.invoke.Intrinsics.ldc(Intrinsics.java:42)
at MH.main(MH.java:12)

Which is expected behavior, I guess.

Am I doing something wrong? Could you compile these files on your side?
Sorry if my tries look lame: I'm very new to this.

With best regards,
Tagir Valeev.

On Tue, Apr 18, 2017 at 9:07 AM, Vicente Romero <vicente.romero at oracle.com>
wrote:

> Hi,
>
> Support for JEP 303 has been pushed in the amber repo [1, 2] (branch name
> is 'constant-folding'). The development is mature although there are some
> fresh areas like using reflection for accessing the API methods. Reflection
> is needed as the classes defined in the API see [1] are not available in
> the boot JDK. There is still some ongoing research so some changes to the
> API and the code are to be expected in the near future,
>
> Thanks,
> Vicente
>
>
> [1] http://hg.openjdk.java.net/amber/amber/jdk/rev/2eeb80b82c9c
> [2] http://hg.openjdk.java.net/amber/amber/langtools/rev/7be70b52c760
>
>
> On 04/17/2017 04:22 PM, Brian Goetz wrote:
>
>> JEP 303 (Intrinsics for LDC and INVOKEDYNAMIC) is hereby adopted into
>> Project Amber.
>>
>> A first draft of the API can be found at:
>>
>>     http://cr.openjdk.java.net/~briangoetz/JDK-8178320/webrev/
>>
>> Prototype implementation coming soon.
>>
>>
>>
>