[9] RFR (M): 8037209: Improvements and cleanups to bytecode assembly for lambda forms (original) (raw)

Paul Sandoz paul.sandoz at oracle.com
Fri Mar 14 15:53:01 UTC 2014

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On Mar 14, 2014, at 2:17 PM, Vladimir Ivanov <vladimir.x.ivanov at oracle.com> wrote:

Paul,

You are looking at the other fix (8037210). The correct link is [1].

Doh! crossed webrevs, thanks.

Just had a quick look, this looks like a really nice improvement to the array setter/getter support, definitely simplified. IIUC the mh.viewAsType will now handle the appropriate casting. I believe it might reduce the "ceremony" for array setter/getter MHs [1].

I see there is a PROFILE_LEVEL option, by default set to 0, that results in casts not being emitted:

           if (VerifyType.isNullConversion(Object.class, pclass, false)) {

```
               if (PROFILE_LEVEL > 0)
```

                   emitReferenceCast(Object.class, arg);

```
               return;
```
```
           }
```

...

       mv.visitLdcInsn(constantPlaceholder(cls));

       mv.visitTypeInsn(Opcodes.CHECKCAST, CLS);

```
       mv.visitInsn(Opcodes.SWAP);
```

       mv.visitMethodInsn(Opcodes.INVOKESTATIC, MHI, "castReference", CLL_SIG, false);

       if (Object[].class.isAssignableFrom(cls))

           mv.visitTypeInsn(Opcodes.CHECKCAST, OBJARY);

```
       else if (PROFILE_LEVEL > 0)
```

           mv.visitTypeInsn(Opcodes.CHECKCAST, OBJ);

Can you explain a bit the rational for that?

Paul.

[1] Below is an inlining trace for an array getter MH in the current code i obtained a few weeks ago when investigating CAS-based MHs for arrays:

Inlining _isInstance on constant Class java/lang/Class Inlining _isInstance on constant Class [Ljava/lang/Object; Inlining _isInstance on constant Class [Ljava/lang/String; Inlining _isInstance on constant Class java/lang/String @ 12 unsafe.ArrayMHTest::get_mh_orig (19 bytes) inline (hot) @ 12 java.lang.invoke.LambdaForm$MH/924874137::invokeExact_MT (15 bytes) inline (hot) @ 2 java.lang.invoke.Invokers::checkExactType (30 bytes) inline (hot) @ 11 java.lang.invoke.MethodHandle::type (5 bytes) accessor @ 11 java.lang.invoke.LambdaForm$MH/1980556943::convert (21 bytes) inline (hot) @ 7 java.lang.invoke.LambdaForm$MH/1892887290::getElement (20 bytes) inline (hot) @ 16 java.lang.invoke.LambdaForm$MH/816943783::convert (37 bytes) inline (hot) @ 6 java.lang.invoke.LambdaForm$BMH/1350345087::reinvoke (26 bytes) inline (hot) @ 12 java.lang.invoke.BoundMethodHandle$Species_LL::reinvokerTarget (8 bytes) inline (hot) @ 22 java.lang.invoke.LambdaForm$DMH/1162873666::invokeStatic_LL_L (15 bytes) inline (hot) @ 1 java.lang.invoke.DirectMethodHandle::internalMemberName (8 bytes) inline (hot) @ 11 sun.invoke.util.ValueConversions::castReference (20 bytes) inline (hot) @ 6 java.lang.Class::isInstance (0 bytes) (intrinsic) @ 17 java.lang.invoke.LambdaForm$BMH/1350345087::reinvoke (26 bytes) inline (hot) @ 12 java.lang.invoke.BoundMethodHandle$Species_LL::reinvokerTarget (8 bytes) inline (hot) @ 22 java.lang.invoke.LambdaForm$DMH/1162873666::invokeStatic_LL_L (15 bytes) inline (hot) @ 1 java.lang.invoke.DirectMethodHandle::internalMemberName (8 bytes) inline (hot) @ 11 sun.invoke.util.ValueConversions::castReference (20 bytes) inline (hot) @ 6 java.lang.Class::isInstance (0 bytes) (intrinsic) @ 33 java.lang.invoke.MethodHandleImpl$ArrayAccessor::getElementL (10 bytes) inline (hot) @ 2 java.lang.Class::cast (27 bytes) inline (hot) @ 6 java.lang.Class::isInstance (0 bytes) (intrinsic) @ 17 java.lang.invoke.LambdaForm$MH/91466391::convert (23 bytes) inline (hot) @ 6 java.lang.invoke.LambdaForm$BMH/1350345087::reinvoke (26 bytes) inline (hot) @ 12 java.lang.invoke.BoundMethodHandle$Species_LL::reinvokerTarget (8 bytes) inline (hot) @ 22 java.lang.invoke.LambdaForm$DMH/1162873666::invokeStatic_LL_L (15 bytes) inline (hot) @ 1 java.lang.invoke.DirectMethodHandle::internalMemberName (8 bytes) inline (hot) @ 11 sun.invoke.util.ValueConversions::castReference (20 bytes) inline (hot) @ 6 java.lang.Class::isInstance (0 bytes) (intrinsic) @ 19 java.lang.invoke.LambdaForm$MH/349834280::identity (10 bytes) inline (hot) @ 6 java.lang.invoke.LambdaForm$DMH/1357006072::invokeStatic_L_L (14 bytes) inline (hot) @ 1 java.lang.invoke.DirectMethodHandle::internalMemberName (8 bytes) inline (hot) @ 10 sun.invoke.util.ValueConversions::identity (2 bytes) inline (hot)

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