Adopting JEP 303 (Intrinsics for LDC and INVOKEDYNAMIC) into Amber
Brian Goetz
brian.goetz at oracle.com
Fri Apr 21 11:37:51 UTC 2017
Does it work if you get rid of the class literals, and use strings?
On 4/21/2017 1:03 AM, Tagir Valeev wrote:
> Seems that it does not work if I use intermediate variable for
> MethodTypeConstant. Consider the following code:
>
> import java.lang.invoke.*;
> import static java.lang.invoke.Constables.*;
> import static java.lang.invoke.Intrinsics.*;
>
> public class TestConst {
> public static void main(String[] args) throws Throwable {
> MethodTypeConstant mtc = MethodTypeConstant.of(void.class);
> MethodHandleConstant mhc =
> MethodHandleConstant.ofStatic(TestConst.class, "test", mtc);
> MethodHandle mh = Intrinsics.ldc(mhc);
> mh.invokeExact();
> }
>
> static void test() {
> System.out.println("Hello");
> }
> }
>
> It's compiled without errors and ldc intrinsic is generated correctly.
> However for non-intrinsified variables class type is not wrapped into
> ClassConstant:
>
> 0: getstatic #2 // Field
> void.class:Ljava/lang/Class;
> 3: iconst_0
> 4: anewarray #3 // class
> java/lang/invoke/Constables$ClassConstant
> 7: invokestatic #4 // Method
> java/lang/invoke/Constables$MethodTypeConstant.of:(Ljava/lang/invoke/Constables$ClassConstant;[Ljava/lang/invoke/Constables$ClassConstant;)Ljava/lang/invoke/Constables$MethodTypeConstant;
>
> This, of course, results in verification errors:
>
> Exception in thread "main" java.lang.VerifyError: Bad type on operand
> stack
> Exception Details:
> Location:
> TestConst.main([Ljava/lang/String;)V @7: invokestatic
> Reason:
> Type 'java/lang/Class' (current frame, stack[0]) is not assignable
> to 'java/lang/invoke/Constables$ClassConstant'
> Current Frame:
> bci: @7
> flags: { }
> locals: { '[Ljava/lang/String;' }
> stack: { 'java/lang/Class',
> '[Ljava/lang/invoke/Constables$ClassConstant;' }
>
> Probably it would be easier to declare class Class<T> as implements
> Constable<Class<T>> and replace ClassConstant with Constable<Class<?>>
> in method signatures where applicable? Or introduce some intermediate
> interface?
>
> With best regards,
> Tagir Valeev.
>
>
> On Fri, Apr 21, 2017 at 10:47 AM, Tagir Valeev <amaembo at gmail.com
> <mailto:amaembo at gmail.com>> wrote:
>
> Thanks! Works fine for me.
>
> With best regards,
> Tagir Valeev.
>
> On Thu, Apr 20, 2017 at 8:37 PM, Vicente Romero
> <vicente.romero at oracle.com <mailto:vicente.romero at oracle.com>> wrote:
>
> Hi all,
>
> I have just pushed a patch that converts class literals into a
> poly expression. Meaning that now you can pass a class literal
> where a ClassConstant is expected. This will simplify the use
> of the API making the user code less verbose. Taking as an
> example the test case sent by Tagir, it could be now rewritten as:
>
> 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(MH.class, "test",
> MethodTypeConstant.of(void.class)));
> handle.invokeExact();
> }
> }
>
> Thanks,
> Vicente
>
>
>
> On 04/18/2017 11:14 PM, Tagir Valeev wrote:
>> Thank you for the hint! It also seems that
>> ClassConstant.of(MH.class) does not work either and
>> VarHandles are not supported yet. However the following
>> sample finally worked for me:
>>
>>
>> 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("LMH;"),
>> "test", MethodTypeConstant.of(ClassConstant.of("V"))));
>> handle.invokeExact();
>> }
>> }
>>
>> With best regards,
>> Tagir Valeev.
>>
>>
>> On Tue, Apr 18, 2017 at 9:13 PM, Brian Goetz
>> <brian.goetz at oracle.com <mailto:brian.goetz at oracle.com>> wrote:
>>
>> The primitive fields (Constables.VOID and friends) are
>> not yet hooked up; for the time being, replace with
>> ClassConstant.of("V").
>>
>>
>> On 4/18/2017 2:17 AM, Tagir Valeev wrote:
>>
>> 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.Int
>> <http://java.lang.invoke.Int>rinsics.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
>> <mailto: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
>> <http://hg.openjdk.java.net/amber/amber/jdk/rev/2eeb80b82c9c>
>> [2]
>> http://hg.openjdk.java.net/amber/amber/langtools/rev/7be70b52c760
>> <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/
>> <http://cr.openjdk.java.net/%7Ebriangoetz/JDK-8178320/webrev/>
>>
>> Prototype implementation coming soon.
>>
>>
>>
>>
>>
>
>
>
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