[Bug c/53411] New: segfault

[Bug c/53411] New: segfault

[regehr at cs dot utah.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53411

             Bug #: 53411
           Summary: segfault
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: regehr@cs.utah.edu
                CC: chenyang@cs.utah.edu


[regehr@dyson r49]$ current-gcc -v
Using built-in specs.
COLLECT_GCC=current-gcc
COLLECT_LTO_WRAPPER=/uusoc/exports/scratch/regehr/z/compiler-install/gcc-r187663-install/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.8.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../configure --with-libelf=/usr/local --enable-lto
--prefix=/home/regehr/z/compiler-install/gcc-r187663-install
--program-prefix=r187663- --enable-languages=c,c++
Thread model: posix
gcc version 4.8.0 20120518 (experimental) (GCC) 


[regehr@dyson r49]$ current-gcc -O3 small.c -c
small.c: In function 'fn4':
small.c:28:1: internal compiler error: Segmentation fault
 }
 ^
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.


[regehr@dyson r49]$ cat small.c  
int a, b, c, d, e, f, g, h;
void fn1 ();
int fn2 ();
int
fn3 (p1)
{
    return a ? 0 : p1;
}
void
fn4 (char p1)
{
    int i, j, k;
    for (; e; e++)
        if (fn2 ())
        {
            f = 1;
            k = 0;
            for (; k <= 1; k++)
            {
                j = ~p1;
                i = f * j;
                h = (fn3 (i | 0 <= c ^ 9L) != b | d) & 8;
                g = p1 | 1;
                fn1 ();
            }
        }
    c = p1;
}

[Bug middle-end/53411] [4.8 Regression] ICE in move_unallocated_pseudos

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53411

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
           Keywords|                            |ice-on-valid-code, ra
   Last reconfirmed|                            |2012-05-20
          Component|c                           |middle-end
     Ever Confirmed|0                           |1
            Summary|segfault                    |[4.8 Regression] ICE in
                   |                            |move_unallocated_pseudos

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-05-20 19:26:39 UTC ---
Confirmed.
(gdb) p i
$1 = 144
(gdb) l
4004      for (i = first_moveable_pseudo; i < last_moveable_pseudo; i++)
4005        if (reg_renumber[i] < 0)
4006          {
4007        int idx = i - first_moveable_pseudo;
4008        rtx other_reg = VEC_index (rtx, pseudo_replaced_reg, idx);
4009        rtx def_insn = DF_REF_INSN (DF_REG_DEF_CHAIN (i));


144 does not exist in the IR as far as I can tell.

[Bug middle-end/53411] [4.8 Regression] ICE in move_unallocated_pseudos

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53411

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.8.0

[Bug middle-end/53411] [4.8 Regression] ICE in move_unallocated_pseudos

[bernds at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53411

--- Comment #3 from Bernd Schmidt <bernds at gcc dot gnu.org> 2012-05-21 16:52:06 UTC ---
Odd. The following is in 190r.asmcons:

(insn 39 51 141 3 (set (reg:DI 135 [ D.1745 ])
        (sign_extend:DI (reg:SI 132 [ j ]))) regehr.c:22 122
{*extendsidi2_rex64}
     (expr_list:REG_DEAD (reg:SI 132 [ j ])
        (expr_list:REG_UNUSED (reg:DI 135 [ D.1745 ])
            (nil))))

That insn has no purpose. We then run delete_trivially_dead_insns in IRA... but
it happens after find_moveable_pseudos, and probably needs to happen before as
well.

[Bug middle-end/53411] [4.8 Regression] ICE in move_unallocated_pseudos

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53411

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bernds at gcc dot gnu.org

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> 2012-05-21 16:24:58 UTC ---
It is caused by revision 186378:

http://gcc.gnu.org/ml/gcc-cvs/2012-04/msg00329.html

[Bug middle-end/53411] [4.8 Regression] ICE in move_unallocated_pseudos

[bernds at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53411

--- Comment #4 from Bernd Schmidt <bernds at gcc dot gnu.org> 2012-05-25 18:32:40 UTC ---
Looks like an earlier dce pass (during .ce2) leaves a dead insn lying around.
Bug in DCE?

[Bug middle-end/53411] [4.8 Regression] ICE in move_unallocated_pseudos

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53411

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |DUPLICATE

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-08-13 10:55:39 UTC ---
If we want to rely on no dead insns before IRA, it would make no point calling
delete_trivially_dead_insns in it.

*** This bug has been marked as a duplicate of bug 53495 ***

[Bug middle-end/53411] [4.8 Regression] ICE in move_unallocated_pseudos

[bernds at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53411

--- Comment #6 from Bernd Schmidt <bernds at gcc dot gnu.org> 2012-08-13 11:07:27 UTC ---
If the call to delete_trivially_dead_insns is supposed to eliminate only
pre-existing dead insns, then just moving it to the beginning of IRA fixes this
bug.

[Bug middle-end/53411] [4.8 Regression] ICE in move_unallocated_pseudos

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53411

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vmakarov at gcc dot gnu.org

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-08-13 11:24:31 UTC ---
ira itself also removes something, e.g. in
          rebuild_jump_labels (get_insns ());
          if (purge_all_dead_edges ())
            delete_unreachable_blocks ();
so I wouldn't move that
  if (delete_trivially_dead_insns (get_insns (), max_reg_num ()))
    df_analyze ();
too early in the function.  But perhaps it could be moved before the
  /* It is not worth to do such improvement when we use a simple
     allocation because of -O0 usage or because the function is too
     big.  */
  if (ira_conflicts_p)
    find_moveable_pseudos ();
hunk.  Vlad, what do you think?  There is still ira_flattening that tweaks the
RTL in between, dunno if it could create trivially dead insns or not.  Moving
d_t_d_i call before f_m_p call certainly fixes both of the testcases too,
haven't bootstrapped/regtested either of the patches yet.

[Bug middle-end/53411] [4.8 Regression] ICE in move_unallocated_pseudos

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53411

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-08-14 07:43:14 UTC ---
Author: jakub
Date: Tue Aug 14 07:43:09 2012
New Revision: 190376

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=190376
Log:
    PR middle-end/53411
    PR rtl-optimization/53495
    * ira.c (ira): Move delete_trivially_dead_insns call before
    find_moveable_pseudos call.

    * gcc.c-torture/compile/pr53411.c: New test.
    * gcc.c-torture/compile/pr53495.c: New test.

Added:
    trunk/gcc/testsuite/gcc.c-torture/compile/pr53411.c
    trunk/gcc/testsuite/gcc.c-torture/compile/pr53495.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/ira.c
    trunk/gcc/testsuite/ChangeLog