Re: Re: Unexpected InternalName format on Enum classes

Le 22/07/2010 15:36, Eugene Kuleshov a écrit :
>    I wonder how did you got such bytecode for values() method... When
> compiled with Java 1.6 it doesn't have clone() and there is an array
> copy is used.
>    

Eclipse ecj uses arraycopy and javac uses clone.
Eclipse compiler does that because instrinsics for clone was
added recently  see http://bugs.sun.com/view_bug.do?bug_id=6428387
Before this fix clone was slower than arraycopy.

Calling clone() on an array is legal, as far as I remember
the support of array.clone was added during one update of 1.4
because jikes (remember, the java compiler written in C++)
was the first to generate this kind of code
(legal from the JVMS point of view).

>    Anyways, your test can be shortened to something like this:
>
> public final class TestClass {
>    public class MyEnum  {
>      MyEnum[] values;
>      public MyEnum[] values() {
>        return values.clone();
>      }
>    }
> }
>
>    The corresponding ASM code for this method look like this:
>
> mv = cw.visitMethod(ACC_PUBLIC, "values",
> "()[Ltest/TestClass$MyEnum;", null, null);
> mv.visitCode();
> mv.visitVarInsn(ALOAD, 0);
> mv.visitFieldInsn(GETFIELD, "test/TestClass$MyEnum", "values",
> "[Ltest/TestClass$MyEnum;");
> mv.visitMethodInsn(INVOKEVIRTUAL, "[Ltest/TestClass$MyEnum;", "clone",
> "()Ljava/lang/Object;");
> mv.visitTypeInsn(CHECKCAST, "[Ltest/TestClass$MyEnum;");
> mv.visitInsn(ARETURN);
> mv.visitMaxs(1, 1);
> mv.visitEnd();
>
>    The owner in INVOKEVIRTUAL is not test/TestClass$MyEnum, but an
> array of test/TestClass$MyEnum, so when trying to get this class you
> need to check if argument is an array and use Type.getElementType() to
> extract the actual array element type. Try something like
>
>    Type t = Type.getType("[[Ltest/TestClass$
>    if(t.getSort()==Type.ARRAY) {
>      System.err.println(t.getElementType().getInternalName());
>    }
>
>    regards,
>    Eugene
>
>
> On Thu, Jul 22, 2010 at 8:14 AM, Freddy Mallet<[email protected]>  wrote:
>    
>> Hi all,
>> I'm one of the developers of the open source Sonar quality platform
>> (www.sonarsource.org) and we use ASM to generate some O.O. metrics and
>> understand the global architecture of a project.
>> I'm currently facing a little issue when analyzing java enumerations (see
>> http://jira.codehaus.org/browse/SONAR-1638). Indeed, the bytecode contains
>> some use of INVOKEVIRTUAL instruction with an unexpected format (at least
>> for me) :
>>
>> INVOKEVIRTUAL [LspecialCases/ClassWithEnum$MyEnum;.clone
>> ()Ljava/lang/Object;
>>
>> In that case, I expect to get :
>>
>> INVOKEVIRTUAL specialCases/ClassWithEnum$MyEnum.clone ()Ljava/lang/Object
>>
>> Indeed, when my implementation of the VisitMethod interface is called back
>> on the method visitMethodInsn(int opcode, String owner, String name, String
>> desc);
>> and in that case the argument "owner" equals to
>> "[LspecialCases/ClassWithEnum$MyEnum;" where I expect to get the internal
>> name "specialCases/ClassWithEnum$MyEnum"
>> Does it means that I need to always check the format of the "owner" argument
>> before doing anything ?
>> Thanks for your help,
>> Freddy
>>      

Rémi

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