[Bug tree-optimization/58464] New: [4.9 Regression] Crashes with SIGSEGV (infinite recursion in phi_translate)

[Bug tree-optimization/58464] New: [4.9 Regression] Crashes with SIGSEGV (infinite recursion in phi_translate)

[d.g.gorbachev at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58464

            Bug ID: 58464
           Summary: [4.9 Regression] Crashes with SIGSEGV (infinite
                    recursion in phi_translate)
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: d.g.gorbachev at gmail dot com
              Host: i686-pc-linux-gnu
            Target: i686-pc-linux-gnu
             Build: i686-pc-linux-gnu

Created attachment 30856
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30856&action=edit
Backtrace

GCC 4.9.0 20130915 (experimental). This happens when building GCC itself
(libcpp/lex.c) with -O3.

[Bug tree-optimization/58464] [4.9 Regression] Crashes with SIGSEGV (infinite recursion in phi_translate)

[d.g.gorbachev at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58464

--- Comment #1 from Dmitry Gorbachev <d.g.gorbachev at gmail dot com> ---
Created attachment 30857
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30857&action=edit
Testcase (somewhat minimized). Compile with -O3.

GCC 20130331 (rev. 197291) - works, 20130526 (rev. 199345) - fails.

[Bug tree-optimization/58464] [4.9 Regression] Crashes with SIGSEGV (infinite recursion in phi_translate)

[d.g.gorbachev at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58464

--- Comment #2 from Dmitry Gorbachev <d.g.gorbachev at gmail dot com> ---
Created attachment 30858
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30858&action=edit
Original preprocessed file

[Bug tree-optimization/58464] [4.9 Regression] Crashes with SIGSEGV (infinite recursion in phi_translate)

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58464

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-09-19
                 CC|                            |mpolacek at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Whoops.  Confirmed.

[Bug tree-optimization/58464] [4.9 Regression] Crashes with SIGSEGV (infinite recursion in phi_translate)

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58464

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.9.0

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r198333.

[Bug tree-optimization/58464] [4.9 Regression] Crashes with SIGSEGV (infinite recursion in phi_translate)

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58464

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
Translating {component_ref<cur>,mem_ref<0B>,result_296}@.MEM_407 through

<bb 141>:
goto <bb 63>;

<bb 63>:
# min_size_293 = PHI <min_size_274(62), 8000(141)>
_294 = min_size_293 + 16;
# .MEM_406 = VDEF <.MEM_405>
base_295 = xmalloc (_294);
result_296 = base_295 + min_size_293;
# .MEM_407 = VDEF <.MEM_406>
result_296->cur = base_295;
goto <bb 68>;

recurses via

1774      phitrans = phi_translate_1 (expr, set1, set2, pred, phiblock);
(gdb) call debug_pre_expr (expr)
{pointer_plus_expr,base_295,min_size_293}

1774      phitrans = phi_translate_1 (expr, set1, set2, pred, phiblock);
(gdb) call debug_pre_expr (expr)
{component_ref<cur>,mem_ref<0B>,result_296}@.MEM_407

where {component_ref<cur>,mem_ref<0B>,result_296}@.MEM_407 is the leader
for base_295 and {pointer_plus_expr,base_295,min_size_293} is the leader
for result_296.

So that circumvents

                leader = find_leader_in_sets (op_val_id, set1, set2);
                if (!leader)
                  break;
                /* Make sure we do not recursively translate ourselves
                   like for translating a[n_1] with the leader for
                   n_1 being a[n_1].  */
                if (get_expression_id (leader) != get_expression_id (expr))
                  {

because it's a recursion with two levels ...

[Bug tree-optimization/58464] [4.9 Regression] Crashes with SIGSEGV (infinite recursion in phi_translate)

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58464

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.

[Bug tree-optimization/58464] [4.9 Regression] Crashes with SIGSEGV (infinite recursion in phi_translate)

[Ganesh.Gopalasubramanian at amd dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58464

GGanesh <Ganesh.Gopalasubramanian at amd dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |Ganesh.Gopalasubramanian@am
                   |                            |d.com

--- Comment #9 from GGanesh <Ganesh.Gopalasubramanian at amd dot com> ---
Seems the fix is regressing rnflow of pb11.

Runtime log of rnflow

Before revision 202826
0:35.558 -> Completed program execution

After revision 202826 (after fix)
0:53.023 -> Completed program execution

The suse polyhedron benchmark log also shows this (after sep23).
http://gcc.opensuse.org/c++bench/polyhedron/polyhedron-summary.txt

[Bug tree-optimization/58464] [4.9 Regression] Crashes with SIGSEGV (infinite recursion in phi_translate)

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58464

Bug 58464 depends on bug 58656, which changed state.

Bug 58656 Summary: [4.9 Regression] rnflow regressing after r202826
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58656

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

[Bug tree-optimization/58464] [4.9 Regression] Crashes with SIGSEGV (infinite recursion in phi_translate)

[dominiq at lps dot ens.fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58464

--- Comment #10 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
> Seems the fix is regressing rnflow of pb11.

Confirmed. I have opened pr59487.