RE: "xbreak" command in GDB ?

[Pierre Muller <muller at cerbere dot u-strasbg dot fr>]

At 09:29 25/01/2002 , Sarnath K - CTD, Chennai. a écrit:
> >Simply try 
> >./gdb ./gdb
> >break main
> >xbreak main
> >disas main
>
>  GDB never exits via the leaving point
>of main() function, I suppose.
>It exits via "quit_command" function.
>I vaguely remember this ( when I was
>browsing GDB source code.) So this test
>might not reflect things correctly.
>Correct me if I am wrong

I didn't want to say that you should run the progream after.
Simply comparing the address of the xbreak with
the position of the ret instruction
in the function disassembly is enough to
show that you are right in saying that this
command is buggy for i386 at least.

Looking into source it apears that this is 
related to function
find_pc_sect_partial_function

because xbreak uses the returned endaddr value.

function description says that
/* Finds the "function" (text symbol) that is smaller than PC but
    greatest of all of the potential text symbols in SECTION.  Sets
    *NAME and/or *ADDRESS conditionally if that pointer is non-null.
    If ENDADDR is non-null, then set *ENDADDR to be the end of the
    function (exclusive), but passing ENDADDR as non-null means that
    the function might cause symbols to be read.  This function either
    succeeds or fails (not halfway succeeds).  If it succeeds, it sets
    *NAME, *ADDRESS, and *ENDADDR to real information and returns 1.
    If it fails, it sets *NAME, *ADDRESS, and *ENDADDR to zero and
    returns 0.  */

The exclusive attribute should be the reason why this works
but the endaddress is simply set by 
               cache_pc_function_high = BLOCK_END (SYMBOL_BLOCK_VALUE (f));
(cache_pc_function_high is copied into endaddr at function end)

But I don't think  that BLOCK_END should 
exclude any instruction, so its probably here that we should 
decrement  but there is no code for 
function_epilogue in i386-tdep.c 



Pierre Muller
Institut Charles Sadron
6,rue Boussingault
F 67083 STRASBOURG CEDEX (France)
mailto:muller@ics.u-strasbg.fr
Phone : (33)-3-88-41-40-07  Fax : (33)-3-88-41-40-99