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Re: info frame ADDR internal error
:-(
Was going to commit the patch, but then I tried it on x86 (I was on x86-64 before) ...
(top-gdb) bt
#0 main (argc=1, argv=0xffffd524) at ../../src/gdb/gdb.c:28
(top-gdb) info frame 1
Stack frame at 0x1:
eip = 0x0; saved eip 0xf7f26f59
Breakpoint 1, internal_error (file=0x8314a4f "../../src/gdb/valops.c", line=662,
string=0x8314a19 "%s: Assertion `%s' failed.") at ../../src/gdb/utils.c:972
972 va_start (ap, string);
(top-gdb) bt
#0 internal_error (file=0x8314a4f "../../src/gdb/valops.c", line=662, string=0x8314a19 "%s: Assertion `%s' failed.")
at ../../src/gdb/utils.c:972
#1 0x08116c44 in value_fetch_lazy (val=0x883f960) at ../../src/gdb/valops.c:662
#2 0x0810b766 in value_contents_all (value=0x883f960) at ../../src/gdb/value.c:375
#3 0x081efd43 in frame_register_unwind (frame=0x8421250, regnum=5, optimizedp=0xffc759f4, lvalp=0xffc759e8,
addrp=0xffc759f0, realnump=0xffc759ec, bufferp=0xffc75a40 "...") at ../../src/gdb/frame.c:603
#4 0x081eff19 in frame_unwind_register (frame=0x8421250, regnum=5, buf="...") at ../../src/gdb/frame.c:639
#5 0x081eff3d in get_frame_register (frame=0x84212e4, regnum=5, buf="...") at ../../src/gdb/frame.c:647
#6 0x0809c2b7 in i386_frame_cache (this_frame=0x84212e4, this_cache=0x84212e8) at ../../src/gdb/i386-tdep.c:1306
#7 0x0809c47e in i386_frame_this_id (this_frame=0x84212e4, this_cache=0x84212e8, this_id=0x8421304)
at ../../src/gdb/i386-tdep.c:1369
#8 0x081ef2cb in get_frame_id (fi=0x84212e4) at ../../src/gdb/frame.c:261
#9 0x081f194d in get_frame_base (fi=0x84212e4) at ../../src/gdb/frame.c:1666
#10 0x0814cd44 in frame_info (addr_exp=0x83f5133 "1", from_tty=1) at ../../src/gdb/stack.c:995
#11 0x080d51b7 in do_cfunc (c=0x84187c0, args=0x83f5133 "1", from_tty=1) at ../../src/gdb/cli/cli-decode.c:67
Here's the offender:
int
value_fetch_lazy (struct value *val)
{
gdb_assert (value_lazy (val));
allocate_value_contents (val);
if (VALUE_LVAL (val) == lval_memory)
{
CORE_ADDR addr = VALUE_ADDRESS (val) + value_offset (val);
int length = TYPE_LENGTH (check_typedef (value_enclosing_type (val)));
if (length)
read_memory (addr, value_contents_all_raw (val), length);
}
else if (VALUE_LVAL (val) == lval_register)
{
struct frame_info *frame;
int regnum;
struct type *type = check_typedef (value_type (val));
struct value *new_val = val, *mark = value_mark ();
/* Offsets are not supported here; lazy register values must
refer to the entire register. */
gdb_assert (value_offset (val) == 0);
while (VALUE_LVAL (new_val) == lval_register && value_lazy (new_val))
{
frame = frame_find_by_id (VALUE_FRAME_ID (new_val));
^^^^^^^^^^^^^^^^
regnum = VALUE_REGNUM (new_val);
gdb_assert (frame != NULL);
^^^^^^^^^^^^^^^^^^^^^^^^^^^
(top-gdb) p VALUE_FRAME_ID (new_val)
$1 = {stack_addr = 1, code_addr = 0, special_addr = 0, stack_addr_p = 1, code_addr_p = 1, special_addr_p = 0}
The new frame that create_new_frame created, isn't linked in the
regular ( current_frame->... ) frame chain, it lives in its own chain,
so this frame_find_by_id call isn't going to find it, unless you
get lucky.
This reinforces the bad things I was saying about create_new_frame.
Any suggestions on how this could be fixed?
Before we go farther, is this a valid use case at all? Could
we rip this piece of parse_frame_specification_1 out instead? It's been
broken for years now --- I can reproduce the original internal error
on gdb-6.0:
>./gdb ./gdb
GNU gdb 6.0
Copyright 2003 Free Software Foundation, Inc.
...
(top-gdb) b main
Breakpoint 3 at 0x8077aa4: file ../../gdb-6.0/gdb/gdb.c, line 30.
(top-gdb) r
Starting program: /home/pedro/gdb/ancient/build-6.0/gdb/gdb
Breakpoint 3, main (argc=1, argv=0xffd15254) at ../../gdb-6.0/gdb/gdb.c:30
30 memset (&args, 0, sizeof args);
(top-gdb) info frame 1
Stack frame at 0x1:
eip = 0x0; saved eip
../../gdb-6.0/gdb/dwarf2-frame.c:518: internal-error: dwarf2_frame_cache: Assertion `fde != NULL' failed.
Note that "info frame ADDR" and "frame ADDR" do look for a frame in
the regular chain that matches ADDR, before resorting to hacking up
a new one with create_new_frame.
--
Pedro Alves