[Bug debug/19192] [4.3/4.4/4.5 Regression] Current development gcc generates inaccurate line info for example code

["rguenth at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #11 from rguenth at gcc dot gnu dot org  2010-03-23 13:37 -------
Unassinging Andrew.  Raising priority to P2.

At -O2 we now optimize main () to

main ()
{
<bb 2>:
  # DEBUG a => 2
  # DEBUG b => 3
  # DEBUG c => 4
  # DEBUG a => 3
  # DEBUG b => 4
  [t.c : 13:22] printf ([t.c : 13] &[t.c : 13] "%d\n"[0], 9); [tail call]
  [t.c : 14:13] return;

}

at -O1 we get

<bb 2>:
  # DEBUG a => 2
  # DEBUG b => 3
  # DEBUG c => 4
  [t.c : 8:32] D.2741_4 = add2 (3, 4);
  [t.c : 8:15] D.2740_5 = D.2741_4 + 2;
  [t.c : 13:22] printf ([t.c : 13] &[t.c : 13] "%d\n"[0], D.2740_5);
  [t.c : 14:13] return;

which seems to be close to the reported case.  the + 2 has line 8 and thus
is ok before TER.  We still expand to

(insn 12 11 13 t.c:13 (parallel [
            (set (reg:SI 61)
                (plus:SI (reg:SI 58 [ D.2741 ])
                    (const_int 2 [0x2])))
            (clobber (reg:CC 17 flags))
        ]) -1 (nil))

(insn 13 12 14 t.c:13 (set (reg:SI 4 si)
        (reg:SI 61)) -1 (nil))

(insn 14 13 15 t.c:13 (set (reg:DI 5 di)
        (symbol_ref/f:DI ("*.LC0") [flags 0x2] <string_cst 0x7ffff5b36820>)) -1
(nil))

(insn 15 14 16 t.c:13 (set (reg:QI 0 ax)
        (const_int 0 [0x0])) -1 (nil))

(call_insn 16 15 0 t.c:13 (set (reg:SI 0 ax)
        (call (mem:QI (symbol_ref:DI ("printf") [flags 0x41] <function_decl
0x7ffff7efc000 printf>) [0 S1 A8])
            (const_int 0 [0x0]))) -1 (nil)
    (expr_list:REG_DEP_TRUE (use (reg:QI 0 ax))
        (expr_list:REG_DEP_TRUE (use (reg:DI 5 di))

thus expanding a TERd expression does not properly reset location infromation.

CC'ing Micha.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|amacleod at redhat dot com  |unassigned at gcc dot gnu
                   |                            |dot org
             Status|ASSIGNED                    |NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19192