[JDK8] RFR (XS): JSR292: IncompatibleClassChangeError in LambdaForm for CharSequence.toString() method handle type converter

[Vladimir Ivanov]

http://cr.openjdk.java.net/~vlivanov/8031502/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8031502

InvokeBytecodeGenerator can produce incorrect bytecode for a LambdaForm 
when invoking a method from Object declared in an interface.

The problem is the following:
   (1) java.lang.CharSequence interface declares abstract method "String 
toString()";

   (2) after 8014013 fix, VM resolves 
CharSequence::toString()/invokeInterface to 
CharSequence::toString()/invokeVirtual;

   (3) during LambdaForm compilation, CharSequence is considered 
statically invocable (see 
InvokeBytecodeGenerator::isStaticallyInvocable) and invokevirtual for 
CharSequence::toString() is issued, which is wrong (invokevirtual throws 
ICCE if it references an interface);

The fix is straightforward: during LambdaForm compilation, switch back 
from invokevirtual to invokeinterface instruction when invoking a method 
on an interface.

The fix is targeted for 8. Will be also integrated into 9.

Testing: regression test, jdk/test/java/lang/invoke, vm.mlvm.testlist, 
nashorn, jruby.

Thanks!

Best regards,
Vladimir Ivanov