[rfc/cp] method stub assertions

Michael Elizabeth Chastain
2004-01-05T00:50:38Z

I'm working on support for hp-ux aCC.

When I call a C++ method, I get this assertion failure:

call class_param.Aptr_a (&g_A)
/house/chastain/gdb/s1/gdb/valops.c:1942: internal-error: Assertion `TYPE_DOMAIN_TYPE (fns_ptr[0].type) != NULL' failed.

This assertion is in find_overload_method:

/* If we are dealing with stub method types, they should have
been resolved by find_method_list via value_find_oload_method_list
above. */
gdb_assert (TYPE_DOMAIN_TYPE (fns_ptr[0].type) != NULL);

The "domain type" is a pointer from the method to the base class
that defines the virtual table for the class that contains this method.

Here is some history about this assertion:

http://sources.redhat.com/ml/gdb-patches/2002-05/msg00413.html

Unfortunately, hpread.c does not set TYPE_DOMAIN_TYPE. As far as I can
tell, only dwarf2read.c and stabsread.c set this field.

Fortunately, it appears that TYPE_DOMAIN_TYPE is really only needed for
calls through member pointers or member function pointers. Such calls
are forbidden with hp-ux som anyways.

This patch adjusts some asserts. I want to change find_overload_method
so that the code asserts that methods are not stubbed (which is what it
really needs), and then change evaluate_subexp_standard so that it
asserts TYPE_DOMAIN_TYPE when it really uses them.

After I do this, gdb gets further, but then crashes anyways in:

evaluate_subexp_standard
find_overload_match
value_virtual_fn_field
gnuv2_virtual_fn_field # WRONG!
value_primitive_field
check_typedef

So the next problem after this is that the the abi type is set to
gnu-v2. When I do "set cp-abi hpaCC", gdb calls the function,
although I see further problems after that.

Anyways, my questions are:

Am I on the right track?
Can I commit this?

Tested with:

native i686-pc-linux-gnu, gcc 2.95.3 3.3.2 HEAD, dwarf-2 stabs+
full regression test
native hppa2.0w-hp-hpux11.11, HP aCC++ B3910B A.03.45
one little test by hand

Michael C

2004-01-04 Michael Chastain <mec.gnu@mindpsring.com>

* valops.c (find_overload_match): Assert that methods are not
stubs. Do not assert that methods have domain types.
* eval.c (evaluate_subexp_standard): Assert basetype and
domain_type as needed.

Index: valops.c
===================================================================
RCS file: /cvs/src/src/gdb/valops.c,v
retrieving revision 1.119
diff -c -3 -p -r1.119 valops.c
*** valops.c 8 Nov 2003 00:13:03 -0000 1.119
--- valops.c 4 Jan 2004 23:05:43 -0000
***************
*** 1,6 ****
/* Perform non-arithmetic operations on values, for GDB.
Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
! 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003
Free Software Foundation, Inc.

This file is part of GDB.
--- 1,6 ----
/* Perform non-arithmetic operations on values, for GDB.
Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
! 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
Free Software Foundation, Inc.

This file is part of GDB.
*************** find_overload_match (struct type **arg_t
*** 1939,1945 ****
/* If we are dealing with stub method types, they should have
been resolved by find_method_list via value_find_oload_method_list
above. */
! gdb_assert (TYPE_DOMAIN_TYPE (fns_ptr[0].type) != NULL);
}
else
{
--- 1939,1946 ----
/* If we are dealing with stub method types, they should have
been resolved by find_method_list via value_find_oload_method_list
above. */
! for (ix = 0; ix < num_fns; ix++)
! gdb_assert (fns_ptr[ix].is_stub == 0);
}
else
{
Index: eval.c
===================================================================
RCS file: /cvs/src/src/gdb/eval.c,v
retrieving revision 1.39
diff -c -3 -p -r1.39 eval.c
*** eval.c 23 Nov 2003 20:41:16 -0000 1.39
--- eval.c 4 Jan 2004 23:05:44 -0000
***************
*** 1,8 ****
/* Evaluate expressions for GDB.

Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
! 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003 Free Software
! Foundation, Inc.

This file is part of GDB.

--- 1,8 ----
/* Evaluate expressions for GDB.

Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
! 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
! Free Software Foundation, Inc.

This file is part of GDB.

***************
*** 36,41 ****
--- 36,42 ----
#include "objc-lang.h"
#include "block.h"
#include "parser-defs.h"
+ #include "gdb_assert.h"

/* Defined in symtab.c */
extern int hp_som_som_object_present;
*************** evaluate_subexp_standard (struct type *e
*** 996,1006 ****
if (METHOD_PTR_IS_VIRTUAL (fnptr))
{
int fnoffset = METHOD_PTR_TO_VOFFSET (fnptr);
! struct type *basetype;
struct type *domain_type =
! TYPE_DOMAIN_TYPE (TYPE_TARGET_TYPE (VALUE_TYPE (arg1)));
int i, j;
! basetype = TYPE_TARGET_TYPE (VALUE_TYPE (arg2));
if (domain_type != basetype)
arg2 = value_cast (lookup_pointer_type (domain_type), arg2);
basetype = TYPE_VPTR_BASETYPE (domain_type);
--- 997,1011 ----
if (METHOD_PTR_IS_VIRTUAL (fnptr))
{
int fnoffset = METHOD_PTR_TO_VOFFSET (fnptr);
! struct type *basetype =
! basetype = TYPE_TARGET_TYPE (VALUE_TYPE (arg2));
struct type *domain_type =
! TYPE_DOMAIN_TYPE (TYPE_TARGET_TYPE (VALUE_TYPE (arg1)));
int i, j;
!
! gdb_assert (basetype != NULL);
! gdb_assert (domain_type != NULL);
!
if (domain_type != basetype)
arg2 = value_cast (lookup_pointer_type (domain_type), arg2);
basetype = TYPE_VPTR_BASETYPE (domain_type);