[Bug java/38827] gcj emitting incorrect code

[pinskia at gmail dot com]

------- Comment #1 from pinskia at gmail dot com  2009-01-13 19:22 -------
Subject: Re:   New: gcj emitting incorrect code



On Jan 13, 2009, at 8:03 AM, "tschwinge at gcc dot gnu dot org"
<gcc-bugzilla@gcc.gnu.org 
 > wrote:

> I originally found this problem when trying to compile a Java  
> package written
> by the Universität Stuttgart's institute IKR.  I was using Debian's  
> gcj
> package, version 4.3.2-2, but can likewise reproduce this using SVN  
> trunk, as
> well as Debian's 4.2.4-4 package.
>
> I completely reduced the test case to the following:
>
>    public class Bug_Class
>    {
>    }
>
>    public interface Bug_Interface
>    {
>    }
>
>    public class Bug
>    {
>        public <X extends Bug_Class & Bug_Interface> Bug(X x)
>        {
>            set(x);
>        }
>
>        public void set(Bug_Interface x)
>        {
>        }
>    }
>
> Directly compiling this will fail as follows:
>
>    $ ~/GCC/trunk.build.64.install/bin/gcj -c Bug.java
>    Bug.java: In class 'Bug':
>    Bug.java: In constructor '(Bug_Class)':
>    In file included from <built-in>:3:
>    Bug.java:3: error: verification failed at PC=9: incompatible type  
> on stack
>
> gcj is able to emit a class file, but that one is considered non- 
> verifying by
> the BCEL verifier:

This sounds like a bug in the eclispe source to bytecode compiler  
which gcj uses now.




>
>
>    [...]
>    Pass 3b, method number 0 ['public void <init>(Bug_Class arg1)
> [Signature(<E:LBug_Class;:LBug_Interface;>(TE;)V)]']:
>    VERIFIED_REJECTED
>    Constraint violated in method 'public void <init>(Bug_Class arg1)
> [Signature(<E:LBug_Class;:LBug_Interface;>(TE;)V)]':
>    Instruction INVOKEVIRTUAL constraint violated: Expecting a  
> 'Bug_Interface'
> but found a 'Bug_Class' on the stack (which is not assignment  
> compatible).
>    InstructionHandle:    6: invokevirtual[182](3) 13
>    [...]
>
> What Sun's javac does differently (as per class-file disassembly  
> inspection) is
> emitting a checkcast against class Bug_Interface before calling  
> invokevirtual.
>
>
> -- 
>           Summary: gcj emitting incorrect code
>           Product: gcc
>           Version: 4.3.2
>            Status: UNCONFIRMED
>          Severity: normal
>          Priority: P3
>         Component: java
>        AssignedTo: unassigned at gcc dot gnu dot org
>        ReportedBy: tschwinge at gcc dot gnu dot org
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38827
>


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38827