A couple of cleanups in breakpoint.c. Let me give some background
first; consider the following program:

int counter = 42;

inline void
callee ()
{
  counter = 0; /* set breakpoint in an inlined function.  */
}

void
caller ()
{
  callee ();
}

int
main ()
{
  caller ();
  callee ();
  return counter;
}



When callee is inlined, we have three occurence for the line
"counter = 0;": inlined in caller, inlined in main, and not inlined.
When a breakpoint is set on this line, GDB sets a breakpoint on 3
locations.

(gdb) l p.c:6
1       int counter = 42;
2
3       inline void
4       callee ()
5       {
6         counter = 0;
7       }
8
9       void
10      caller ()
(gdb) b 6
Breakpoint 1 at 0x1800074: file p.c, line 6. (3 locations)


I have recently hit a bug in an assembler which was optimizing out the
prologue line info; it was making GDB think that the line
"counter = 0;" was a part of callee's prologue. And this pointed me to
something strange in GDB.

After having used this bogus assembler to generate my program, if I try
to set a breakpoint at line "counter = 0;", I end up with only one
occurence instead of three:

(gdb) b 6  
Breakpoint 1 at 0x1800074: file p.c, line 6.

The problem was in skip_prologue_sal defined in breakpoint.c. When it
actually skips a prologue, it does not assure that the other sal's
fields (explicit_pc and explicit_line) are left unchanged. In my case,
it was accidently changing explicit_line from 1 to 0. This change
disabled the line sal expansion, and in consequence we ended up with
the breakpoint set in only one location. I think that it's a bug in
skip_prologue_sal, this function should not change mess with these
fields.

Now, if I change skip_prologue_sal to copy explicit_line and
explicit_pc, the line expansion is done; but we should make sure that
prologue is skipped similarly, otherwise we get an assertion failure
when the address returned by resolve_sal_pc cannot be found after
line sal expansion:

(gdb) break p.c:6
../../src/gdb/breakpoint.c:5113: internal-error: expand_line_sal_maybe:
Assertion `found' failed.


Patch attached, tested on x86-linux. OK to apply?


2009-06-02  Jerome Guitton  <guitton@adacore.com>

	* breakpoint.c (expand_line_sal_maybe): When explicit_line,
	skip prologue on each sals.
	(skip_prologue_sal): Return explicit_line and explicit_pc
	unmodified.