Conference turris::decladebug

906.0. "seg fault walking up stack" by DECCXL::OUELLETTE (crunch) Wed Apr 02 1997 14:50

Have you seen this failure footprint before?
If not, I may be able to help you reproduce it.
The thing I was debugging uses shared libraries.
I was walking up the stack to find a place from where
I could make a dnode() work.

cosf> ladebug ~/exx
Welcome to the Ladebug Debugger Version 4.0-33
------------------
object file name: /usr/users/roly/exx
Reading symbolic information ...run t.cxx
done
(ladebug) stop in walk_variable_address
[#1: stop in void walk_variable_address(an_expr_node_ptr, me_expr_result&) ]
(ladebug) run t.c
[1] stopped at [void walk_variable_address(an_expr_node_ptr, me_expr_result&):2165 0x6ff9d7fc]
   2165         edg_var = expr->variant.variable;
(ladebug) n
stopped at [void walk_variable_address(an_expr_node_ptr, me_expr_result&):2167 0x6ff9d808]
   2167     if (DEC_SUPP(*edg_var).cg_var == NULL)
(ladebug) n
stopped at [void walk_variable_address(an_expr_node_ptr, me_expr_result&):2171 0x6ff9d82c]
   2171         *var = DEC_SUPP(*edg_var).cg_var;
(ladebug) n
stopped at [void walk_variable_address(an_expr_node_ptr, me_expr_result&):2173 0x6ff9d83c]
   2173     result.lvalue.base_symbol = var;
(ladebug) dnode(var)
Symbol gem_db_g_debug not visible in current scope.
Error: no value for parameter #1 gem_db_g_debug
(ladebug) print var
0x1409b000
(ladebug) up
>1  0x6ff9d1c4 in walk_expression(expr=0x1406d4a8, result=struct { ... }) /usr/users/roly/cpri/src/edg-meg/me_expr.cxx:1928
   1928         walk_variable_address(expr, result);
(ladebug)
>2  0x6ff9ee8c in walk_operation_expression(expr=0x1406d4c8, result=<bad reference>) /usr/users/roly/cpri/src/edg-meg/me_expr.cxx:2776
   2776             walk_expression(op1, lhs);
(ladebug)
>3  0x6ff9d168 in walk_expression(expr=0x1406d4c8, result=struct { ... }) /usr/users/roly/cpri/src/edg-meg/me_expr.cxx:1914
   1914         walk_operation_expression(expr, result);
(ladebug)
>4  0x6ff9e47c in walk_operation_expression(expr=0x1406d4e8, result=<bad reference>) /usr/users/roly/cpri/src/edg-meg/me_expr.cxx:2492
   2492             walk_expression(op1, lhs);
(ladebug)
>5  0x6ff9d168 in walk_expression(expr=0x1406d4e8, result=struct { ... }) /usr/users/roly/cpri/src/edg-meg/me_expr.cxx:1914
   1914         walk_operation_expression(expr, result);
(ladebug)
>6  0x6ffa95c8 in walk_return_statement(stmt=0x1406d430) /usr/users/roly/cpri/src/edg-meg/me_stmt.cxx:467
    467         walk_expression (stmt->expr, return_value);
(ladebug)
>7  0x6ffab3c0 in walk_statement(stmt=struct { ... }) /usr/users/roly/cpri/src/edg-meg/me_stmt.cxx:1491
   1491         walk_return_statement(&stmt);
(ladebug)
>8  0x6ffa8dd4 in walk_statement_list(stmt=0x1406d430) /usr/users/roly/cpri/src/edg-meg/me_stmt.cxx:173
    173         walk_statement(*stmt);
(ladebug)

Ladebug Debugger Version 4.0-33 caught signal "Segmentation fault" (11).
This is an unexpected condition and may indicate the presence of a defect.
If you wish to report this, please include the stack trace that follows.
Diagnostic stack trace ...
0x123d2448
0x12525edc
0x12469048
0x124587f8
0x1246aaa4
0x12469a40
0x1246c080
0x12468428
0x1245d56c
0x1245cdf4
0x1245817c
0x12457b20
0x12457124
0x12455f18
0x1258e464
0x125728f8
0x123afba8
0x123b0010
0x12439f30
0x124366d8
0x1238642c
0x12238a10
0x123862a8
0x1228d408
0x1228e130
0x12222a04
0x12226f50
0x12216b5c
0x12213c0c
end of diagnostic stack trace.
Fatal error: Segmentation fault

    See note 899.
    
    							- Matt

I've added this to my tracking list of C++ problems.