[Bug java/21722] New: gcj miscompiles accesses to static final vars with indirect dispatch

[Bug java/21722] New: gcj miscompiles accesses to static final vars with indirect dispatch

[matz at suse dot de]

Below I attached a tarball which contains two packages with one class each. 
B.java defines a static final String initilized to "foo", and A.java 
tries to call the 'equals' method on that object (and another string). 
This actually is reduced from trang.  The problem happens when this is 
compiled like the doit.sh script does.  I.e. first creating the .class files 
and then compiling both .class files at once into one object file with 
-findirect-dispatch. 
 
The generated program will segfault.  The segfault happens because 
the generated code for A.main() accesses the ->vtable member of the global 
object '_ZN1b1B3FOOE' (== b::B::FOO) directly (if I read the .t03.generic dump 
correctly).  But it is defined like so in the assembler: 
_ZN1b1B3FOOE: 
        .long   _Utf1 
        .section        .rodata.jutf8.10 
 
I.e. the first (and only) member of that symbol actually is the UTF-8 
string itself, not a pointer to the vtable.  But the code trying to resolve 
the address of the 'equals' method assumes so, and hence calls some random 
address. 
 
Note that this is not the same as the usual -findirect-dispatch only supports 
compiling from .class problem.  This is the case here.

-- 
           Summary: gcj miscompiles accesses to static final vars with
                    indirect dispatch
           Product: gcc
           Version: 4.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: java
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: matz at suse dot de
                CC: gcc-bugs at gcc dot gnu dot org,java-prs at gcc dot gnu
                    dot org
GCC target triplet: i686-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21722

[Bug java/21722] gcj miscompiles accesses to static final vars with indirect dispatch

[matz at suse dot de]

------- Additional Comments From matz at suse dot de  2005-05-23 16:52 -------
Created an attachment (id=8953)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=8953&action=view)
tarball showing the problem


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21722

[Bug java/21722] gcj miscompiles accesses to static final vars with indirect dispatch

[skh at suse dot de]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |skh at suse dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21722

[Bug java/21722] gcj miscompiles accesses to static final vars with indirect dispatch

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-23 16:59 -------
Related to PR 1259.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
  BugsThisDependsOn|                            |1259


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21722

[Bug java/21722] gcj miscompiles accesses to static final vars with indirect dispatch

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-23 18:03 -------
Confirmed, I don't get a seg fault but a NPE (NullPointerException) instead.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-05-23 18:03:47
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21722

[Bug java/21722] gcj miscompiles accesses to static final vars with indirect dispatch

[tromey at gcc dot gnu dot org]

------- Additional Comments From tromey at gcc dot gnu dot org  2005-06-01 20:30 -------
Interestingly, if I compile the two .class files separately
and then link the results, it works.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21722

[Bug java/21722] gcj miscompiles accesses to static final vars with indirect dispatch

[matz at suse dot de]

------- Additional Comments From matz at suse dot de  2005-06-01 20:59 -------
Yes.  I think this is because the compiler needs to see the definition and the use site 
to exhibit this bug.  Without the def it will correctly emit the code walking the table 
to get to the member. 

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21722

[Bug java/21722] gcj miscompiles accesses to static final vars with indirect dispatch

[tromey at gcc dot gnu dot org]

------- Additional Comments From tromey at gcc dot gnu dot org  2005-06-01 21:36 -------
I'm testing a patch.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |tromey at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2005-05-23 18:03:47         |2005-06-01 21:36:08
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21722

[Bug java/21722] gcj miscompiles accesses to static final vars with indirect dispatch

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-06-03 04:06 -------
Subject: Bug 21722

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	tromey@gcc.gnu.org	2005-06-03 04:06:19

Modified files:
	gcc/java       : ChangeLog class.c 

Log message:
	PR java/21722:
	* class.c (build_static_field_ref): Don't fold constant fields if
	current class is from a .class file and we're using indirect
	dispatch.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/java/ChangeLog.diff?cvsroot=gcc&r1=1.1621&r2=1.1622
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/java/class.c.diff?cvsroot=gcc&r1=1.230&r2=1.231



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21722

[Bug java/21722] gcj miscompiles accesses to static final vars with indirect dispatch

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2005-06-03 04:06 -------
Subject: Bug 21722

CVSROOT:	/cvs/gcc
Module name:	gcc
Branch: 	gcc-4_0-branch
Changes by:	tromey@gcc.gnu.org	2005-06-03 04:05:53

Modified files:
	gcc/java       : ChangeLog class.c 

Log message:
	PR java/21722:
	* class.c (build_static_field_ref): Don't fold constant fields if
	current class is from a .class file and we're using indirect
	dispatch.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/java/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.1556.2.22&r2=1.1556.2.23
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/java/class.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.220.8.2&r2=1.220.8.3



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21722

[Bug java/21722] gcj miscompiles accesses to static final vars with indirect dispatch

[tromey at gcc dot gnu dot org]

------- Additional Comments From tromey at gcc dot gnu dot org  2005-06-03 04:12 -------
I've checked in the fix for this.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.0.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21722

[Bug java/21722] gcj miscompiles accesses to static final vars with indirect dispatch

[tromey at gcc dot gnu dot org]

------- Additional Comments From tromey at gcc dot gnu dot org  2005-06-03 05:34 -------
Forgot to mark as fixed earlier.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21722