java/1113: Bad array or type conversion bug when compiling bytecode

[mdw at cs dot berkeley dot edu]

>Number:         1113
>Category:       java
>Synopsis:       Bad array or type conversion bug when compiling bytecode
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    apbianco
>State:          closed
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Dec 20 12:06:08 PST 2000
>Closed-Date:    Tue Mar 07 19:13:58 PST 2000
>Last-Modified:  Tue Mar  7 19:16:00 PST 2000
>Originator:     Matt Welsh <mdw@cs.berkeley.edu>
>Release:        gcc 2.95.2
>Organization:
>Environment:
Linux x86 Red Hat 6.0
>Description:
Apparently there is a bug in either array references or type
conversion which occurs only when compiling Java bytecode,
and varies depending on the level of optimization used. In 
this example, code compiled with -O2 exhibits the bug, but
-O does not. 

The code which exhibits this bug is rather simple; it is a
routine which takes a 'short' and writes two bytes of the
short into a byte array (it is part of a hand-coded 
serialization routine). Note the use of a loop to do the
array reference as well as the ugly type-casting; I realize
that this is not beautiful code but it does show the bug
in a simple test case.
>How-To-Repeat:
Compile the given test program with 'javac' or 'jikes' to
bytecode. Compile with gcj 2.95.2 with:
'gcj -O2 --main=PutShort -o PutShort PutShort.class'
Then run 'PutShort'. 

The program calls 'put_short' in a loop to write the
values 0..50 to a byte array containing 100 bytes, and
then prints out the contents of the byte array. Correct
output should be the hex values for the shorts 0..50 in
sequence; incorrect output is usually random bytes.
>Fix:
Apply the patch...

1999-11-28  Anthony Green  <green@cygnus.com>

	* decl.c (find_local_variable): Reuse single slot decls when
	appropriate.

>Release-Note:
I think pr107-patch should be revised like
pr107-patch-revised indicates.
>Audit-Trail:

Formerly PR gcj/107

State-Changed-From-To: open->feedback
State-Changed-By: green
State-Changed-When: Sun Nov 28 10:28:22 1999
State-Changed-Why:
    
    I've attached a patch.  Please try it and let me know if
    it works for you.

From: green@cygnus.com
To: apbianco@cygnus.com, bryce@albatross.co.nz,
  java-gnats@sourceware.cygnus.com, mdw@cs.berkeley.edu
Cc:  
Subject: Re: gcj/107
Date: 28 Nov 1999 18:28:23 -0000

 Synopsis: Bad array or type conversion bug when compiling bytecode
 
 State-Changed-From-To: open->feedback
 State-Changed-By: green
 State-Changed-When: Sun Nov 28 10:28:22 1999
 State-Changed-Why:
     
     I've attached a patch.  Please try it and let me know if
     it works for you.
 
 http://sourceware.cygnus.com/cgi-bin/gnatsweb.pl?cmd=view&pr=107&database=java
State-Changed-From-To: feedback->closed
State-Changed-By: apbianco
State-Changed-When: Tue Mar  7 19:13:58 2000
State-Changed-Why:
    I checked in Anthony's patch to fix this PR:
    
      http://gcc.gnu.org/ml/gcc-patches/2000-03/msg00239.html

From: apbianco@cygnus.com
To: apbianco@cygnus.com, bryce@albatross.co.nz,
  java-gnats@sourceware.cygnus.com, mdw@cs.berkeley.edu
Cc:  
Subject: Re: gcj/107
Date: 8 Mar 2000 03:13:58 -0000

 Synopsis: Bad array or type conversion bug when compiling bytecode
 
 State-Changed-From-To: feedback->closed
 State-Changed-By: apbianco
 State-Changed-When: Tue Mar  7 19:13:58 2000
 State-Changed-Why:
     I checked in Anthony's patch to fix this PR:
     
       http://gcc.gnu.org/ml/gcc-patches/2000-03/msg00239.html
 
 http://sourceware.cygnus.com/cgi-bin/gnatsweb.pl?cmd=view&pr=107&database=java
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