Re: Re: Re: Unexpected InternalName format on Enum classes

Thanks a lot for your help Eugene and Rémi, I've now a clear understanding
of what happens !
----------------------------------------
Freddy Mallet
www.SonarSource.org
www.SonarSource.com
http://twitter.com/FreddyMallet
----------------------------------------


On Thu, Jul 22, 2010 at 9:26 PM, Rémi Forax <[email protected]> wrote:

>  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]> <[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 (seehttp://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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