core dump

core dump

[Tom Tromey]

Insight once again got a segv while I had the watch window up.  This
time (as before, I think) it died when I re-ran my program (gcj).  I
had rebuilt the program and gdb had to reload it; I don't know whether
this happened or not.

I avoid the watch window because it causes so many problems :-(

Stack trace appended.  This is on my x86 Debian 2.0 box.

Tom

#0  check_typedef (type=0xea7) at ../../src/gdb/gdbtypes.c:1115
#1  0x80ae051 in check_typedef (type=0x881e088)
    at ../../src/gdb/gdbtypes.c:1191
#2  0x8081e5d in allocate_value (type=0x881e088) at ../../src/gdb/values.c:84
#3  0x80881f2 in value_zero (type=0x881e088, lv=not_lval)
    at ../../src/gdb/valops.c:412
#4  0x80cf7da in varobj_get_type (var=0x8dd1170) at ../../src/gdb/varobj.c:727
#5  0x80d0569 in value_of_root (var_handle=0xbfff9014, type_changed=0xbfff9008)
    at ../../src/gdb/varobj.c:1649
#6  0x80cfa5c in varobj_update (var=0x8dd1170, changelist=0xbfff902c)
    at ../../src/gdb/varobj.c:908
#7  0x80c37c0 in variable_update (interp=0x8323848, var=0x8dd1170)
    at ../../src/gdb/gdbtk/generic/gdbtk-varobj.c:463
#8  0x80c34f7 in variable_obj_command (clientData=0x8dd1170, interp=0x8323848, 
    objc=2, objv=0x8324540) at ../../src/gdb/gdbtk/generic/gdbtk-varobj.c:273#9  0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8df7f28)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#10 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8be4980)    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#11 0x81892fa in Itcl_EvalMemberCode (interp=0x8323848, mfunc=0x8de5458, 
    member=0x8de5470, contextObj=0x8dba400, objc=1, objv=0x8324534)
    at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_methods.c:1029
#12 0x8189b8d in Itcl_ExecMethod (clientData=0x8de5458, interp=0x8323848, 
    objc=1, objv=0x8324534)
    at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_methods.c:1546
#13 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8dec628)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#14 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x89dbca0)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#15 0x81892fa in Itcl_EvalMemberCode (interp=0x8323848, mfunc=0x8dd59d8, 
    member=0x8dd59f0, contextObj=0x8dba400, objc=1, objv=0x8324530)
    at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_methods.c:1029
#16 0x8189b8d in Itcl_ExecMethod (clientData=0x8dd59d8, interp=0x8323848, 
    objc=1, objv=0x8324530)
    at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_methods.c:1546
#17 0x818f9f2 in Itcl_EvalArgs (interp=0x8323848, objc=1, objv=0x8324530)
    at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_util.c:1337
#18 0x818b42b in Itcl_HandleInstance (clientData=0x8dba400, interp=0x8323848, 
    objc=2, objv=0x832452c)
    at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_objects.c:658
#19 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8832368)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#20 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8bab498)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#21 0x8254d93 in Tcl_UplevelObjCmd (dummy=0x0, interp=0x8323848, objc=4, 
    objv=0x832451c) at ../../../src/tcl/unix/../generic/tclProc.c:612
#22 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x84a6c28)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#23 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8417500)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#24 0x82552d1 in TclObjInterpProc (clientData=0x84550c8, interp=0x8323848, 
    objc=2, objv=0x8324514) at ../../../src/tcl/unix/../generic/tclProc.c:996
#25 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x84fa2f0)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#26 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x841a4d8)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#27 0x82552d1 in TclObjInterpProc (clientData=0x8451b48, interp=0x8323848, 
    objc=1, objv=0x8324510) at ../../../src/tcl/unix/../generic/tclProc.c:996
#28 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x84cbb28)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#29 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8417650)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#30 0x82552d1 in TclObjInterpProc (clientData=0x845e880, interp=0x8323848, 
    objc=1, objv=0x832450c) at ../../../src/tcl/unix/../generic/tclProc.c:996
#31 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x88a3218)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#32 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8be5fc8)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#33 0x821ce8a in Tcl_Eval (interp=0x8323848, string=0x8277bb2 "gdbtk_tcl_idle")
    at ../../../src/tcl/unix/../generic/tclBasic.c:2453
#34 0x80c2b38 in gdbtk_call_command (cmdblk=0x8318100, arg=0x0, from_tty=0)
    at ../../src/gdb/gdbtk/generic/gdbtk-hooks.c:516
#35 0x80db1d8 in execute_command (p=0x8a97b43 "", from_tty=0)
    at ../../src/gdb/top.c:1544
#36 0x80bdc4d in gdb_immediate_command (clientData=0x80bdba0, 
    interp=0x8323848, objc=2, objv=0x8324504)
    at ../../src/gdb/gdbtk/generic/gdbtk-cmds.c:906
#37 0x80bd7c8 in wrapped_call (opaque_args=0xbfffbf48)
    at ../../src/gdb/gdbtk/generic/gdbtk-cmds.c:550
#38 0x80da49b in catch_errors (func=0x80bd7b0 <wrapped_call>, args=0xbfffbf48, 
    errstring=0x82772c8 "", mask=6) at ../../src/gdb/top.c:615
#39 0x80bd6f4 in call_wrapper (clientData=0x80bdba0, interp=0x8323848, objc=2, 
    objv=0x8324504) at ../../src/gdb/gdbtk/generic/gdbtk-cmds.c:488
#40 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8a92058)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#41 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8417818)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#42 0x82552d1 in TclObjInterpProc (clientData=0x845a678, interp=0x8323848, 
    objc=1, objv=0x8324500) at ../../../src/tcl/unix/../generic/tclProc.c:996
#43 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8a8c578)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#44 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8417968)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#45 0x82552d1 in TclObjInterpProc (clientData=0x841fc50, interp=0x8323848, 
    objc=1, objv=0x83244fc) at ../../../src/tcl/unix/../generic/tclProc.c:996
#46 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8a8c4f8)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#47 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x89e0340)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#48 0x8227afd in Tcl_SwitchObjCmd (dummy=0x0, interp=0x8323848, objc=3, 
    objv=0x83244f0) at ../../../src/tcl/unix/../generic/tclCmdMZ.c:1732
#49 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8a69c38)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#50 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x842b2e8)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#51 0x81892fa in Itcl_EvalMemberCode (interp=0x8323848, mfunc=0x84c2898, 
    member=0x84c28b0, contextObj=0x84de818, objc=2, objv=0x83244e8)
    at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_methods.c:1029
#52 0x8189b8d in Itcl_ExecMethod (clientData=0x84c2898, interp=0x8323848, 
    objc=2, objv=0x83244e8)
    at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_methods.c:1546
#53 0x818f9f2 in Itcl_EvalArgs (interp=0x8323848, objc=2, objv=0x83244e8)
    at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_util.c:1337
#54 0x818b42b in Itcl_HandleInstance (clientData=0x84de818, interp=0x8323848, 
    objc=3, objv=0x83244e4)
    at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_objects.c:658
#55 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8dcff58)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#56 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8bab768)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#57 0x824e173 in NamespaceInscopeCmd (dummy=0x0, interp=0x8323848, objc=4, 
    objv=0x83244d4) at ../../../src/tcl/unix/../generic/tclNamesp.c:3277
#58 0x824d7b9 in Tcl_NamespaceObjCmd (clientData=0x0, interp=0x8323848, 
    objc=4, objv=0x83244d4)
    at ../../../src/tcl/unix/../generic/tclNamesp.c:2498
#59 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8dfb350)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#60 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8bab660)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#61 0x821ce8a in Tcl_Eval (interp=0x8323848, 
    string=0xbfffe4d0 "namespace inscope ::GDBSrcBar {::.srcwin0.srcwin inferior run}") at ../../../src/tcl/unix/../generic/tclBasic.c:2453
#62 0x821e5bc in Tcl_GlobalEval (interp=0x8323848, 
    command=0xbfffe4d0 "namespace inscope ::GDBSrcBar {::.srcwin0.srcwin inferior run}") at ../../../src/tcl/unix/../generic/tclBasic.c:3983
#63 0x820e214 in TkCopyAndGlobalEval (interp=0x8323848, 
    script=0x8dfc420 "\207") at ../../../src/tk/unix/../generic/tkBind.c:4547
#64 0x81d469a in TkInvokeButton (butPtr=0x868df88)
    at ../../../src/tk/unix/../generic/tkButton.c:1136
#65 0x81d3ca4 in ButtonWidgetCmd (clientData=0x868df88, interp=0x8323848, 
    argc=2, argv=0xbfffe5f0) at ../../../src/tk/unix/../generic/tkButton.c:543
#66 0x821c7b6 in TclInvokeStringCommand (clientData=0x869d380, 
    interp=0x8323848, objc=2, objv=0x83244cc)
    at ../../../src/tcl/unix/../generic/tclBasic.c:1745
#67 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8dbfe88)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#68 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x84cf510)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#69 0x8254d6d in Tcl_UplevelObjCmd (dummy=0x0, interp=0x8323848, objc=3, 
    objv=0x83244c0) at ../../../src/tcl/unix/../generic/tclProc.c:609
#70 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8a97838)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#71 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x84cf420)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#72 0x82552d1 in TclObjInterpProc (clientData=0x869e290, interp=0x8323848, 
    objc=2, objv=0x83244b8) at ../../../src/tcl/unix/../generic/tclProc.c:996
#73 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8e06030)
    at ../../../src/tcl/unix/../generic/tclExecute.c:955
#74 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x840fcc0)
    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
#75 0x821ce8a in Tcl_Eval (interp=0x8323848, 
    string=0xbffff6b8 "TOOLBAR_button_up .srcwin0.srcwin.container.pane0.childsite.con.t.stop") at ../../../src/tcl/unix/../generic/tclBasic.c:2453
#76 0x821e5bc in Tcl_GlobalEval (interp=0x8323848, 
    command=0xbffff6b8 "TOOLBAR_button_up .srcwin0.srcwin.container.pane0.childsite.con.t.stop") at ../../../src/tcl/unix/../generic/tclBasic.c:3983
#77 0x820af5d in Tk_BindEvent (bindingTable=0x83427b0, eventPtr=0x8e00e48, 
    tkwin=0x869e5b0, numObjects=0, objectPtr=0xbffff7b8)
    at ../../../src/tk/unix/../generic/tkBind.c:1731
#78 0x820ed9c in TkBindEventProc (winPtr=0x869e5b0, eventPtr=0x8e00e48)
    at ../../../src/tk/unix/../generic/tkCmds.c:242
#79 0x81bd708 in Tk_HandleEvent (eventPtr=0x8e00e48)
    at ../../../src/tk/unix/../generic/tkEvent.c:657
#80 0x81bda79 in WindowEventProc (evPtr=0x8e00e40, flags=-3)
    at ../../../src/tk/unix/../generic/tkEvent.c:983
#81 0x824eb50 in Tcl_ServiceEvent (flags=-3)
    at ../../../src/tcl/unix/../generic/tclNotify.c:444
#82 0x824ed66 in Tcl_DoOneEvent (flags=0)
    at ../../../src/tcl/unix/../generic/tclNotify.c:683
#83 0x81bdae4 in Tk_MainLoop ()
    at ../../../src/tk/unix/../generic/tkEvent.c:1041
#84 0x80c290c in tk_command_loop ()
    at ../../src/gdb/gdbtk/generic/gdbtk-hooks.c:383
#85 0x807cdb2 in captured_command_loop (data=0x0) at ../../src/gdb/main.c:104
#86 0x80da49b in catch_errors (func=0x807cd90 <captured_command_loop>, 
    args=0x0, errstring=0x8262a4e "", mask=6) at ../../src/gdb/top.c:615
#87 0x807da03 in captured_main (data=0xbffffb58) at ../../src/gdb/main.c:749
#88 0x80da49b in catch_errors (func=0x807cde0 <captured_main>, 
    args=0xbffffb58, errstring=0x8262a4e "", mask=6) at ../../src/gdb/top.c:615
#89 0x807da37 in main (argc=2, argv=0xbffffb7c) at ../../src/gdb/main.c:761

Re: core dump

[Fernando Nasser]

Tom Tromey wrote:
> 
> Insight once again got a segv while I had the watch window up.  This
> time (as before, I think) it died when I re-ran my program (gcj).  I
> had rebuilt the program and gdb had to reload it; I don't know whether
> this happened or not.
 

Despite the core happening when inside the update code for watched variables, the problem is
unrelated to it.  There is no excuse for gdb's value_zero to dump core, but it seems that some
variable (whatever you are whatching) had a bad formed type.  I would bet it is probably a bug in
the gdb symbol reading or some compiler debug info malformation.

Unless someone knows of some limitation when calling value_zero().  There is nothing in the code
that indicates that.  And it seems that it worked once, before Tom reloaded his program

Here is how Insight gets the type of a variable:

  /* To print the type, we simply create a zero value_ptr and
     cast it to our type. We then typeprint this variable. */
  val = value_zero (var->type, not_lval);
  type_print (VALUE_TYPE (val), "", stb, -1);

Inside value_zero() allocate_value() is called and in its turn calls check_typedef().  The latter
tries to recurse with TYPE_TARGET_TYPE (type), but that is not valid.  Why?  Nothing to do with
Insight.

> 
> I avoid the watch window because it causes so many problems :-(
>

I don't think you are being fair.  Anyway, it is not to blame in this case.

> Stack trace appended.  This is on my x86 Debian 2.0 box.
> 
> Tom
> 
> #0  check_typedef (type=0xea7) at ../../src/gdb/gdbtypes.c:1115
> #1  0x80ae051 in check_typedef (type=0x881e088)
>     at ../../src/gdb/gdbtypes.c:1191
> #2  0x8081e5d in allocate_value (type=0x881e088) at ../../src/gdb/values.c:84
> #3  0x80881f2 in value_zero (type=0x881e088, lv=not_lval)
>     at ../../src/gdb/valops.c:412
> #4  0x80cf7da in varobj_get_type (var=0x8dd1170) at ../../src/gdb/varobj.c:727
> #5  0x80d0569 in value_of_root (var_handle=0xbfff9014, type_changed=0xbfff9008)
>     at ../../src/gdb/varobj.c:1649
> #6  0x80cfa5c in varobj_update (var=0x8dd1170, changelist=0xbfff902c)
>     at ../../src/gdb/varobj.c:908
> #7  0x80c37c0 in variable_update (interp=0x8323848, var=0x8dd1170)
>     at ../../src/gdb/gdbtk/generic/gdbtk-varobj.c:463
> #8  0x80c34f7 in variable_obj_command (clientData=0x8dd1170, interp=0x8323848,
>     objc=2, objv=0x8324540) at ../../src/gdb/gdbtk/generic/gdbtk-varobj.c:273#9  0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8df7f28)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #10 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8be4980)    at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #11 0x81892fa in Itcl_EvalMemberCode (interp=0x8323848, mfunc=0x8de5458,
>     member=0x8de5470, contextObj=0x8dba400, objc=1, objv=0x8324534)
>     at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_methods.c:1029
> #12 0x8189b8d in Itcl_ExecMethod (clientData=0x8de5458, interp=0x8323848,
>     objc=1, objv=0x8324534)
>     at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_methods.c:1546
> #13 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8dec628)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #14 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x89dbca0)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #15 0x81892fa in Itcl_EvalMemberCode (interp=0x8323848, mfunc=0x8dd59d8,
>     member=0x8dd59f0, contextObj=0x8dba400, objc=1, objv=0x8324530)
>     at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_methods.c:1029
> #16 0x8189b8d in Itcl_ExecMethod (clientData=0x8dd59d8, interp=0x8323848,
>     objc=1, objv=0x8324530)
>     at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_methods.c:1546
> #17 0x818f9f2 in Itcl_EvalArgs (interp=0x8323848, objc=1, objv=0x8324530)
>     at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_util.c:1337
> #18 0x818b42b in Itcl_HandleInstance (clientData=0x8dba400, interp=0x8323848,
>     objc=2, objv=0x832452c)
>     at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_objects.c:658
> #19 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8832368)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #20 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8bab498)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #21 0x8254d93 in Tcl_UplevelObjCmd (dummy=0x0, interp=0x8323848, objc=4,
>     objv=0x832451c) at ../../../src/tcl/unix/../generic/tclProc.c:612
> #22 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x84a6c28)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #23 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8417500)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #24 0x82552d1 in TclObjInterpProc (clientData=0x84550c8, interp=0x8323848,
>     objc=2, objv=0x8324514) at ../../../src/tcl/unix/../generic/tclProc.c:996
> #25 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x84fa2f0)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #26 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x841a4d8)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #27 0x82552d1 in TclObjInterpProc (clientData=0x8451b48, interp=0x8323848,
>     objc=1, objv=0x8324510) at ../../../src/tcl/unix/../generic/tclProc.c:996
> #28 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x84cbb28)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #29 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8417650)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #30 0x82552d1 in TclObjInterpProc (clientData=0x845e880, interp=0x8323848,
>     objc=1, objv=0x832450c) at ../../../src/tcl/unix/../generic/tclProc.c:996
> #31 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x88a3218)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #32 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8be5fc8)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #33 0x821ce8a in Tcl_Eval (interp=0x8323848, string=0x8277bb2 "gdbtk_tcl_idle")
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2453
> #34 0x80c2b38 in gdbtk_call_command (cmdblk=0x8318100, arg=0x0, from_tty=0)
>     at ../../src/gdb/gdbtk/generic/gdbtk-hooks.c:516
> #35 0x80db1d8 in execute_command (p=0x8a97b43 "", from_tty=0)
>     at ../../src/gdb/top.c:1544
> #36 0x80bdc4d in gdb_immediate_command (clientData=0x80bdba0,
>     interp=0x8323848, objc=2, objv=0x8324504)
>     at ../../src/gdb/gdbtk/generic/gdbtk-cmds.c:906
> #37 0x80bd7c8 in wrapped_call (opaque_args=0xbfffbf48)
>     at ../../src/gdb/gdbtk/generic/gdbtk-cmds.c:550
> #38 0x80da49b in catch_errors (func=0x80bd7b0 <wrapped_call>, args=0xbfffbf48,
>     errstring=0x82772c8 "", mask=6) at ../../src/gdb/top.c:615
> #39 0x80bd6f4 in call_wrapper (clientData=0x80bdba0, interp=0x8323848, objc=2,
>     objv=0x8324504) at ../../src/gdb/gdbtk/generic/gdbtk-cmds.c:488
> #40 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8a92058)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #41 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8417818)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #42 0x82552d1 in TclObjInterpProc (clientData=0x845a678, interp=0x8323848,
>     objc=1, objv=0x8324500) at ../../../src/tcl/unix/../generic/tclProc.c:996
> #43 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8a8c578)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #44 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8417968)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #45 0x82552d1 in TclObjInterpProc (clientData=0x841fc50, interp=0x8323848,
>     objc=1, objv=0x83244fc) at ../../../src/tcl/unix/../generic/tclProc.c:996
> #46 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8a8c4f8)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #47 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x89e0340)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #48 0x8227afd in Tcl_SwitchObjCmd (dummy=0x0, interp=0x8323848, objc=3,
>     objv=0x83244f0) at ../../../src/tcl/unix/../generic/tclCmdMZ.c:1732
> #49 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8a69c38)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #50 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x842b2e8)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #51 0x81892fa in Itcl_EvalMemberCode (interp=0x8323848, mfunc=0x84c2898,
>     member=0x84c28b0, contextObj=0x84de818, objc=2, objv=0x83244e8)
>     at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_methods.c:1029
> #52 0x8189b8d in Itcl_ExecMethod (clientData=0x84c2898, interp=0x8323848,
>     objc=2, objv=0x83244e8)
>     at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_methods.c:1546
> #53 0x818f9f2 in Itcl_EvalArgs (interp=0x8323848, objc=2, objv=0x83244e8)
>     at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_util.c:1337
> #54 0x818b42b in Itcl_HandleInstance (clientData=0x84de818, interp=0x8323848,
>     objc=3, objv=0x83244e4)
>     at /x2/egcs-stuff/gdb/src/itcl/itcl/generic/itcl_objects.c:658
> #55 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8dcff58)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #56 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8bab768)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #57 0x824e173 in NamespaceInscopeCmd (dummy=0x0, interp=0x8323848, objc=4,
>     objv=0x83244d4) at ../../../src/tcl/unix/../generic/tclNamesp.c:3277
> #58 0x824d7b9 in Tcl_NamespaceObjCmd (clientData=0x0, interp=0x8323848,
>     objc=4, objv=0x83244d4)
>     at ../../../src/tcl/unix/../generic/tclNamesp.c:2498
> #59 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8dfb350)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #60 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x8bab660)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #61 0x821ce8a in Tcl_Eval (interp=0x8323848,
>     string=0xbfffe4d0 "namespace inscope ::GDBSrcBar {::.srcwin0.srcwin inferior run}") at ../../../src/tcl/unix/../generic/tclBasic.c:2453
> #62 0x821e5bc in Tcl_GlobalEval (interp=0x8323848,
>     command=0xbfffe4d0 "namespace inscope ::GDBSrcBar {::.srcwin0.srcwin inferior run}") at ../../../src/tcl/unix/../generic/tclBasic.c:3983
> #63 0x820e214 in TkCopyAndGlobalEval (interp=0x8323848,
>     script=0x8dfc420 "\207") at ../../../src/tk/unix/../generic/tkBind.c:4547
> #64 0x81d469a in TkInvokeButton (butPtr=0x868df88)
>     at ../../../src/tk/unix/../generic/tkButton.c:1136
> #65 0x81d3ca4 in ButtonWidgetCmd (clientData=0x868df88, interp=0x8323848,
>     argc=2, argv=0xbfffe5f0) at ../../../src/tk/unix/../generic/tkButton.c:543
> #66 0x821c7b6 in TclInvokeStringCommand (clientData=0x869d380,
>     interp=0x8323848, objc=2, objv=0x83244cc)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:1745
> #67 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8dbfe88)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #68 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x84cf510)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #69 0x8254d6d in Tcl_UplevelObjCmd (dummy=0x0, interp=0x8323848, objc=3,
>     objv=0x83244c0) at ../../../src/tcl/unix/../generic/tclProc.c:609
> #70 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8a97838)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #71 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x84cf420)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #72 0x82552d1 in TclObjInterpProc (clientData=0x869e290, interp=0x8323848,
>     objc=2, objv=0x83244b8) at ../../../src/tcl/unix/../generic/tclProc.c:996
> #73 0x8236cf2 in TclExecuteByteCode (interp=0x8323848, codePtr=0x8e06030)
>     at ../../../src/tcl/unix/../generic/tclExecute.c:955
> #74 0x821d0cc in Tcl_EvalObj (interp=0x8323848, objPtr=0x840fcc0)
>     at ../../../src/tcl/unix/../generic/tclBasic.c:2645
> #75 0x821ce8a in Tcl_Eval (interp=0x8323848,
>     string=0xbffff6b8 "TOOLBAR_button_up .srcwin0.srcwin.container.pane0.childsite.con.t.stop") at ../../../src/tcl/unix/../generic/tclBasic.c:2453
> #76 0x821e5bc in Tcl_GlobalEval (interp=0x8323848,
>     command=0xbffff6b8 "TOOLBAR_button_up .srcwin0.srcwin.container.pane0.childsite.con.t.stop") at ../../../src/tcl/unix/../generic/tclBasic.c:3983
> #77 0x820af5d in Tk_BindEvent (bindingTable=0x83427b0, eventPtr=0x8e00e48,
>     tkwin=0x869e5b0, numObjects=0, objectPtr=0xbffff7b8)
>     at ../../../src/tk/unix/../generic/tkBind.c:1731
> #78 0x820ed9c in TkBindEventProc (winPtr=0x869e5b0, eventPtr=0x8e00e48)
>     at ../../../src/tk/unix/../generic/tkCmds.c:242
> #79 0x81bd708 in Tk_HandleEvent (eventPtr=0x8e00e48)
>     at ../../../src/tk/unix/../generic/tkEvent.c:657
> #80 0x81bda79 in WindowEventProc (evPtr=0x8e00e40, flags=-3)
>     at ../../../src/tk/unix/../generic/tkEvent.c:983
> #81 0x824eb50 in Tcl_ServiceEvent (flags=-3)
>     at ../../../src/tcl/unix/../generic/tclNotify.c:444
> #82 0x824ed66 in Tcl_DoOneEvent (flags=0)
>     at ../../../src/tcl/unix/../generic/tclNotify.c:683
> #83 0x81bdae4 in Tk_MainLoop ()
>     at ../../../src/tk/unix/../generic/tkEvent.c:1041
> #84 0x80c290c in tk_command_loop ()
>     at ../../src/gdb/gdbtk/generic/gdbtk-hooks.c:383
> #85 0x807cdb2 in captured_command_loop (data=0x0) at ../../src/gdb/main.c:104
> #86 0x80da49b in catch_errors (func=0x807cd90 <captured_command_loop>,
>     args=0x0, errstring=0x8262a4e "", mask=6) at ../../src/gdb/top.c:615
> #87 0x807da03 in captured_main (data=0xbffffb58) at ../../src/gdb/main.c:749
> #88 0x80da49b in catch_errors (func=0x807cde0 <captured_main>,
>     args=0xbffffb58, errstring=0x8262a4e "", mask=6) at ../../src/gdb/top.c:615
> #89 0x807da37 in main (argc=2, argv=0xbffffb7c) at ../../src/gdb/main.c:761

-- 
Fernando Nasser
Cygnus Solutions (a Red Hat company)    E-Mail:  fnasser@cygnus.com
2323 Yonge Street, Suite #300           Tel:  416-482-2661 ext. 311
Toronto, Ontario   M4P 2C9              Fax:  416-482-6299

Re: core dump

[Keith Seitz]

Fernando Nasser wrote:
> 
> Tom Tromey wrote:
> >
> > Insight once again got a segv while I had the watch window up.  This
> > time (as before, I think) it died when I re-ran my program (gcj).  I
> > had rebuilt the program and gdb had to reload it; I don't know whether
> > this happened or not.
> 
> 
> Despite the core happening when inside the update code for watched variables, the problem is
> unrelated to it.  There is no excuse for gdb's value_zero to dump core, but it seems that some
> variable (whatever you are whatching) had a bad formed type.  I would bet it is probably a bug in
> the gdb symbol reading or some compiler debug info malformation.
> 
> Unless someone knows of some limitation when calling value_zero().  There is nothing in the code
> that indicates that.  And it seems that it worked once, before Tom reloaded his program
> 
> Here is how Insight gets the type of a variable:
> 
>   /* To print the type, we simply create a zero value_ptr and
>      cast it to our type. We then typeprint this variable. */
>   val = value_zero (var->type, not_lval);
>   type_print (VALUE_TYPE (val), "", stb, -1);
> 
> Inside value_zero() allocate_value() is called and in its turn calls check_typedef().  The latter
> tries to recurse with TYPE_TARGET_TYPE (type), but that is not valid.  Why?  Nothing to do with
> Insight.
> 

I think that this kind of thing can also occur because re-running (and
reloading symbols) invalidates all of the variable code. The trees that
the variable object interface maintain contain LOTS of references to
transient memory which is invalidated whenever an executable is re-run
or symbols are reloaded. This is what makes it so fast compared to other
solutions. The side effect is, though, that gdbtk must be REALLY careful
about these buggers pointing to garbage because an objfile has been
reread.

I seem to recall adding something to gdbtk to catch this: whenever the
no_inferior hook is run, it should deletes all variables. Srctextwin,
watch, and locals windows should all do this... If not, you get
seemingly random crashes like this.

Keith
-- 
Why chat when you can Firetalk?
Firetalk ID: Keith (10320)
www.firetalk.com

Re: core dump

[Fernando Nasser]

Keith Seitz wrote:
> 
> I think that this kind of thing can also occur because re-running (and
> reloading symbols) invalidates all of the variable code. The trees that
> the variable object interface maintain contain LOTS of references to
> transient memory which is invalidated whenever an executable is re-run
> or symbols are reloaded. This is what makes it so fast compared to other
> solutions. The side effect is, though, that gdbtk must be REALLY careful
> about these buggers pointing to garbage because an objfile has been
> reread.
> 
> I seem to recall adding something to gdbtk to catch this: whenever the
> no_inferior hook is run, it should deletes all variables. Srctextwin,
> watch, and locals windows should all do this... If not, you get
> seemingly random crashes like this.
> 

This makes sense. But no_inferior (the callback you are refering to) is called and deletes all
variable objects.

So, the code in VariableWin and WatchedWin is doing the right thing.

Unless the hook is not being run...

Tom, can you invoke Insight with the debug window and see if "deleteTree" is printed in there when
you reload your file?

Thanks.


-- 
Fernando Nasser
Cygnus Solutions (a Red Hat company)    E-Mail:  fnasser@cygnus.com
2323 Yonge Street, Suite #300           Tel:  416-482-2661 ext. 311
Toronto, Ontario   M4P 2C9              Fax:  416-482-6299

Re: core dump

[Tom Tromey]

Fernando> Tom, can you invoke Insight with the debug window and see if
Fernando> "deleteTree" is printed in there when you reload your file?

I don't see how this can work.
Insight crashes when I do this.  I won't be able to read the debug
window.

T

Re: core dump

[Fernando Nasser]

Tom Tromey wrote:
> 
> Fernando> Tom, can you invoke Insight with the debug window and see if
> Fernando> "deleteTree" is printed in there when you reload your file?
> 
> I don't see how this can work.
> Insight crashes when I do this.  I won't be able to read the debug
> window.
> 
Hum, it can scroll out of the window and you you lose it.

Why don't you leave the Watch window without any entries.  We just want to know if the deleteTree is
called.  It is done (or not) regardless of you having any expression or not in the Watch window.


-- 
Fernando Nasser
Cygnus Solutions (a Red Hat company)    E-Mail:  fnasser@cygnus.com
2323 Yonge Street, Suite #300           Tel:  416-482-2661 ext. 311
Toronto, Ontario   M4P 2C9              Fax:  416-482-6299

Re: core dump

[Tom Tromey]

Fernando> Hum, it can scroll out of the window and you you lose it.

I discovered "debug::log_file stdout".  The debug module sure has
grown.

Fernando> Why don't you leave the Watch window without any entries.
Fernando> We just want to know if the deleteTree is called.  It is
Fernando> done (or not) regardless of you having any expression or not
Fernando> in the Watch window.

I did this.
deleteTree is not called.

Tom

Re: core dump

[Fernando Nasser]

Tom Tromey wrote:
> 
> Fernando> Why don't you leave the Watch window without any entries.
> Fernando> We just want to know if the deleteTree is called.  It is
> Fernando> done (or not) regardless of you having any expression or not
> Fernando> in the Watch window.
> 
> I did this.
> deleteTree is not called.
> 

Just to make sure, your sources are newer than 1999-09-23, isn't it?
I noticed that the lines in the stack trace are different from the current sources, are you working
on a branch?

-- 
Fernando Nasser
Cygnus Solutions (a Red Hat company)    E-Mail:  fnasser@cygnus.com
2323 Yonge Street, Suite #300           Tel:  416-482-2661 ext. 311
Toronto, Ontario   M4P 2C9              Fax:  416-482-6299

Re: core dump

[Tom Tromey]

Fernando> Just to make sure, your sources are newer than 1999-09-23,
Fernando> isn't it?  I noticed that the lines in the stack trace are
Fernando> different from the current sources, are you working on a
Fernando> branch?

I updated and rebuilt yesterday.
I believe I'm using the trunk gdb.
I have no explanation why the line numbers might be different.

I can't do a clean rebuild right now.
Debugging the debugger is only incidental to what I'm doing...

Tom

Re: core dump

[Fernando Nasser]

Tom Tromey wrote:
> 
> Fernando> Hum, it can scroll out of the window and you you lose it.
> 
> I discovered "debug::log_file stdout".  The debug module sure has
> grown.
> 
> Fernando> Why don't you leave the Watch window without any entries.
> Fernando> We just want to know if the deleteTree is called.  It is
> Fernando> done (or not) regardless of you having any expression or not
> Fernando> in the Watch window.
> 
> I did this.
> deleteTree is not called.
> 


OK, congrats.  You just found a bug.

The hook Keith was referring too is just run if you use (explicitly) the "detach" command.

Gdb must run it whenever the inferior is gone, maybe in generic_mourn()

I will try to fix it tomorrow.  Will you be willing to retest it with my patch if I mail it to you? 

-- 
Fernando Nasser
Cygnus Solutions (a Red Hat company)    E-Mail:  fnasser@cygnus.com
2323 Yonge Street, Suite #300           Tel:  416-482-2661 ext. 311
Toronto, Ontario   M4P 2C9              Fax:  416-482-6299