Re: c++/6236: ia64 vtable call - Illegal Instruction

[wilson@gcc.gnu.org]

Synopsis: ia64 vtable call - Illegal Instruction

Responsible-Changed-From-To: unassigned->wilson
Responsible-Changed-By: wilson
Responsible-Changed-When: Thu Apr 18 15:03:53 2002
Responsible-Changed-Why:
    IA-64 maintainer
State-Changed-From-To: open->closed
State-Changed-By: wilson
State-Changed-When: Thu Apr 18 15:03:53 2002
State-Changed-Why:
    The program fails because it makes incorrect assumptions about
    the vtable format.
    
    Gcc now uses the new multi-vendor C++ ABI.  See
    http://www.codesourcery.com/cxx-abi/
    
    On IA-64, the vtable format does not include function pointers,
    i.e. an address of a function description.  Instead, the vtable
    includes the actual function descriptor itself.  Thus if you
    pretend the vtable is an array of function addresses, then you
    will get one more dereference than you want, and the program
    will fail.  Your code will need to be updated to handle the new
    vtable format correctly.
    
    See http://www.codesourcery.com/cxx-abi/abi.html#vtable.
    The section on function pointers is out of date, the decision
    was made to use the address/gp pair in the vtable.  You can
    see that if you look through the closed issues list.  The link
    for this is on the first page mentioned above.
    
    I don't know if this is documented anywhere in the Intel
    documentation, but this is the same way that the Intel
    compiler implements vtables, so this isn't a GNU specific
    issue.
    

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=6236