On Mon, Sep 10, 2018 at 04:40:58PM +0100, Jason Merrill wrote:
On Mon, Sep 10, 2018 at 3:42 PM, John Darrington
<j...@darrington.wattle.id.au> wrote:
> On Mon, Sep 10, 2018 at 03:36:26PM +0100, Jason Merrill wrote:
> On Mon, Aug 27, 2018 at 8:20 PM, John Darrington
> <j...@darrington.wattle.id.au> wrote:
> > * include/dwarf2.h (enum dwarf_unit_type)
[DE_EH_PE_udata3]: New member.
>
>
> What's the rationale? Do you have a separate patch that uses this
new macro?
>
> Yes. I there is an upcoming patch for GDB. See
> https://sourceware.org/ml/gdb-patches/2018-08/msg00731.html
This looks like support for reading fixed 3-byte values from the
exception handling unwind information. Do you expect this information
to ever need to store 3-byte values?
Yes, I've already come across that (which is why I created the patch).
Without this patch, GDB will barf. See the attached backtrace.
The offsets in the unwind info
don't need to correspond exactly to target word sizes,
So far as I can tell, the dwarf-unwinder assumes that they do. Chaning
it would require a rewrite. I doubt the GDB team would be happy with
that.
and if you use
an assembler that supports it (such as GNU as), the table will use
variable-length encoding anyway.
I must admit I don't understand what you are saying here. I was using
GNU as. To what table are you refering?
J'
(top-gdb) bt
#0 internal_error (file=0x100afeac0 <_ZN3gdbL8in_placeE+86>
"/home/john/binutils-gdb/gdb/dwarf2-frame.c", line=1535,
fmt=0x100aff05b <dwarf2_frame_base+219> "Unsupported address size %d") at
/home/john/binutils-gdb/gdb/common/errors.c:54
#1 0x000000010055bce1 in encoding_for_size (size=3) at
/home/john/binutils-gdb/gdb/dwarf2-frame.c:1535
#2 0x000000010055be64 in read_encoded_value (unit=0x60086bf80, encoding=0
'\000', ptr_len=3, buf=0x60087c300 "",
bytes_read_ptr=0xffffb82c, func_base=0) at
/home/john/binutils-gdb/gdb/dwarf2-frame.c:1590
#3 0x000000010055cd63 in decode_frame_entry_1 (unit=0x60086bf80,
start=0x60087c2f8 "", eh_frame_p=0, cie_table=0xffffb970,
fde_table=0xffffb960, entry_type=EH_CIE_OR_FDE_TYPE_ID) at
/home/john/binutils-gdb/gdb/dwarf2-frame.c:2046
#4 0x000000010055cefd in decode_frame_entry (unit=0x60086bf80,
start=0x60087c2f8 "", eh_frame_p=0, cie_table=0xffffb970,
fde_table=0xffffb960, entry_type=EH_CIE_OR_FDE_TYPE_ID) at
/home/john/binutils-gdb/gdb/dwarf2-frame.c:2101
#5 0x000000010055d3fc in dwarf2_build_frame_info (objfile=0x60068a300) at
/home/john/binutils-gdb/gdb/dwarf2-frame.c:2297
#6 0x000000010055c355 in dwarf2_frame_find_fde (pc=0xffffbac0, out_offset=0x0)
at /home/john/binutils-gdb/gdb/dwarf2-frame.c:1719
#7 0x000000010055b97c in dwarf2_frame_sniffer (self=0x100afef00
<dwarf2_frame_unwind>, this_frame=0x600810530, this_cache=0x600810548)
at /home/john/binutils-gdb/gdb/dwarf2-frame.c:1349
#8 0x00000001005cbd78 in frame_unwind_try_unwinder (this_frame=0x600810530,
this_cache=0x600810548,
unwinder=0x100afef00 <dwarf2_frame_unwind>) at
/home/john/binutils-gdb/gdb/frame-unwind.c:106
#9 0x00000001005cbf35 in frame_unwind_find_by_frame (this_frame=0x600810530,
this_cache=0x600810548)
at /home/john/binutils-gdb/gdb/frame-unwind.c:165
#10 0x00000001005ca77c in get_frame_type (frame=0x600810530) at
/home/john/binutils-gdb/gdb/frame.c:2623
#11 0x00000001006cb9c7 in print_frame_info (frame=0x600810530, print_level=0,
print_what=SRC_AND_LOC, print_args=1, set_current_sal=1)
at /home/john/binutils-gdb/gdb/stack.c:795
#12 0x00000001006ca373 in print_stack_frame (frame=0x600810530, print_level=0,
print_what=SRC_AND_LOC, set_current_sal=1)
at /home/john/binutils-gdb/gdb/stack.c:176
#13 0x0000000100611c8f in print_stop_location (ws=0xffffbec0) at
/home/john/binutils-gdb/gdb/infrun.c:8042
#14 0x0000000100611ceb in print_stop_event (uiout=0x6006784d0) at
/home/john/binutils-gdb/gdb/infrun.c:8059
#15 0x000000010041b911 in tui_on_normal_stop (bs=0x0, print_frame=1) at
/home/john/binutils-gdb/gdb/tui/tui-interp.c:98
#16 0x00000001009a8986 in std::_Function_handler<void (bpstats*, int), void
(*)(bpstats*, int)>::_M_invoke(std::_Any_data const&, bpstats*&&,
int&&) (__functor=..., __args#0=<unknown type in
/home/john/bb/gdb/gdb, CU 0x546d40, DIE 0x65b331>,
__args#1=<unknown type in /home/john/bb/gdb/gdb, CU 0x546d40, DIE 0x65b340>)
at /usr/lib/gcc/x86_64-linux-gnu/7.3.0/include/c++/bits/std_function.h:316
#17 0x00000001009273ed in std::function<void (bpstats*,
int)>::operator()(bpstats*, int) const (this=0x600155a30, __args#0=0x0,
__args#1=1)
at /usr/lib/gcc/x86_64-linux-gnu/7.3.0/include/c++/bits/std_function.h:706
#18 0x00000001008c891f in gdb::observers::observable<bpstats*, int>::notify
(this=0x100cf2aa0 <gdb::observers::normal_stop>, args#0=0x0,
args#1=1) at /home/john/binutils-gdb/gdb/common/observable.h:106
#19 0x00000001006123f9 in normal_stop () at
/home/john/binutils-gdb/gdb/infrun.c:8339
#20 0x0000000100607bf1 in start_remote (from_tty=1) at
/home/john/binutils-gdb/gdb/infrun.c:3236
#21 0x000000010068fdcf in remote_target::start_remote (this=0x600850d00,
from_tty=1, extended_p=0)
at /home/john/binutils-gdb/gdb/remote.c:4767
#22 0x0000000100691278 in remote_target::open_1 (name=0x600051cde ":2159",
from_tty=1, extended_p=0)
at /home/john/binutils-gdb/gdb/remote.c:5638
#23 0x0000000100690005 in remote_target::open (name=0x600051cde ":2159",
from_tty=1) at /home/john/binutils-gdb/gdb/remote.c:4862
#24 0x00000001006ed810 in open_target (args=0x600051cde ":2159", from_tty=1,
command=0x60063e800)
at /home/john/binutils-gdb/gdb/target.c:338
#25 0x00000001007583ff in do_sfunc (c=0x60063e800, args=0x600051cde ":2159",
from_tty=1)
at /home/john/binutils-gdb/gdb/cli/cli-decode.c:122
#26 0x000000010075b2a9 in cmd_func (cmd=0x60063e800, args=0x600051cde ":2159",
from_tty=1)
at /home/john/binutils-gdb/gdb/cli/cli-decode.c:1856
#27 0x000000010070e654 in execute_command (p=0x600051ce2 "9", from_tty=1) at
/home/john/binutils-gdb/gdb/top.c:630
#28 0x00000001005b6ebb in command_handler (command=0x600051cd0 "") at
/home/john/binutils-gdb/gdb/event-top.c:583
#29 0x00000001005b72a5 in command_line_handler (rl=0x600765110 "") at
/home/john/binutils-gdb/gdb/event-top.c:774
#30 0x00000001005b6674 in gdb_rl_callback_handler (rl=0x600765110 "") at
/home/john/binutils-gdb/gdb/event-top.c:213
#31 0x000000010079450b in rl_callback_read_char () at
/home/john/binutils-gdb/readline/callback.c:220
#32 0x00000001005b6599 in gdb_rl_callback_read_char_wrapper_noexcept () at
/home/john/binutils-gdb/gdb/event-top.c:175
#33 0x00000001005b6601 in gdb_rl_callback_read_char_wrapper
(client_data=0x600051cf0) at /home/john/binutils-gdb/gdb/event-top.c:192
#34 0x00000001005b6d4a in stdin_event_handler (error=0,
client_data=0x600051cf0) at /home/john/binutils-gdb/gdb/event-top.c:511
#35 0x00000001005b55c2 in handle_file_event (file_ptr=0x600689070,
ready_mask=1) at /home/john/binutils-gdb/gdb/event-loop.c:733
#36 0x00000001005b5950 in gdb_wait_for_event (block=1) at
/home/john/binutils-gdb/gdb/event-loop.c:859
#37 0x00000001005b4a57 in gdb_do_one_event () at
/home/john/binutils-gdb/gdb/event-loop.c:347
#38 0x00000001005b4a92 in start_event_loop () at
/home/john/binutils-gdb/gdb/event-loop.c:371
#39 0x00000001006338cf in captured_command_loop () at
/home/john/binutils-gdb/gdb/main.c:330
#40 0x0000000100634e93 in captured_main (data=0xffffcb50) at
/home/john/binutils-gdb/gdb/main.c:1173
#41 0x0000000100634f52 in gdb_main (args=0xffffcb50) at
/home/john/binutils-gdb/gdb/main.c:1189
#42 0x00000001004010d0 in main (argc=2, argv=0xffffcbc0) at
/home/john/binutils-gdb/gdb/gdb.c:32
(top-gdb)
