[Bug middle-end/48016] New: Inconsistency in non-local goto save area

[Bug middle-end/48016] New: Inconsistency in non-local goto save area

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48016

           Summary: Inconsistency in non-local goto save area
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: hjl.tools@gmail.com


We have

void
emit_stack_save (enum save_level save_level, rtx *psave)
{
  rtx sa = *psave;
  /* The default is that we use a move insn and save in a Pmode object.  */
  rtx (*fcn) (rtx, rtx) = gen_move_insn;
  enum machine_mode mode = STACK_SAVEAREA_MODE (save_level);
....

void
update_nonlocal_goto_save_area (void)
{
  tree t_save;
  rtx r_save;

  /* The nonlocal_goto_save_area object is an array of N pointers.  The
     first one is used for the frame pointer save; the rest are sized by
     STACK_SAVEAREA_MODE.  Create a reference to array index 1, the first
     of the stack save area slots.  */
  t_save = build4 (ARRAY_REF, ptr_type_node, cfun->nonlocal_goto_save_area,
                   integer_one_node, NULL_TREE, NULL_TREE);
  r_save = expand_expr (t_save, NULL_RTX, VOIDmode, EXPAND_WRITE);

  emit_stack_save (SAVE_NONLOCAL, &r_save);
}

The mode of PSAVE passed to emit_stack_save is the mode of
ptr_type_node, which may not be STACK_SAVEAREA_MODE which
is expected by emit_stack_save.

[Bug middle-end/48016] Inconsistency in non-local goto save area

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48016

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-03-07 14:13:10 UTC ---
The gimple middle-end only knows one pointer type mode, ptr_type_mode.  If
we want to save Pmode then we need to use an appropriate integer type
and a proper alias set.

I guess this code should be simply replaced to emit RTL directly instead
of going through expansion of an ARRAY_REF.

[Bug middle-end/48016] Inconsistency in non-local goto save area

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48016

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> 2011-03-07 14:40:35 UTC ---
(In reply to comment #1)
> The gimple middle-end only knows one pointer type mode, ptr_type_mode.  If
> we want to save Pmode then we need to use an appropriate integer type
> and a proper alias set.
> 
> I guess this code should be simply replaced to emit RTL directly instead
> of going through expansion of an ARRAY_REF.

For x32 target, we expand function h in:

extern void foo (void) __attribute__((noreturn));
int n;

void
g (void)
{
  __label__ lab;
  void h (void) { if (n == 2) goto lab; }
  void (*f1) (void) = foo;
  void (*f2) (void) = h;

  f2 ();
  if (n)
    f1 ();
  n = 1;
 lab:
  n++;
}

to

h ()
{
  int n.3;
  long long unsigned int[3] * D.2708;

  # BLOCK 2
  # PRED: ENTRY (fallthru)
  n.3_1 = n;
  if (n.3_1 == 2)
    goto <bb 3>;
  else
    goto <bb 4>;
  # SUCC: 3 (true) 4 (false)

  # BLOCK 3
  # PRED: 2 (true)
  D.2708_3 = &CHAIN.5_2(D)->__nl_goto_buf;
  __builtin_nonlocal_goto (&<L2>, D.2708_3);
  # SUCC:

  # BLOCK 4
  # PRED: 2 (false)
  return;
  # SUCC: EXIT

}

I am checking this patch as a workaround on x32 branch.

diff --git a/gcc/ChangeLog.x32 b/gcc/ChangeLog.x32
index f39563b..3f1f953 100644
--- a/gcc/ChangeLog.x32
+++ b/gcc/ChangeLog.x32
@@ -1,3 +1,8 @@
+2011-03-07  H.J. Lu  <hongjiu.lu@intel.com>
+
+    PR middle-end/48016
+    * explow.c (emit_stack_save): Adjust mode of stack save area.
+
 2011-03-06  H.J. Lu  <hongjiu.lu@intel.com>

     * config/i386/predicates.md (aligned_operand): Check SUBREG_REG
diff --git a/gcc/explow.c b/gcc/explow.c
index 3401e49..460af1f 100644
--- a/gcc/explow.c
+++ b/gcc/explow.c
@@ -1008,6 +1008,14 @@ emit_stack_save (enum save_level save_level, rtx *psave)
   do_pending_stack_adjust ();
   if (sa != 0)
     sa = validize_mem (sa);
+  /* FIXME: update_nonlocal_goto_save_area may pass SA in the wrong mode.  */
+  if (GET_MODE (sa) != mode)
+    {
+      gcc_assert (ptr_mode != Pmode
+          && GET_MODE (sa) == ptr_mode
+          && mode == Pmode);
+      sa = adjust_address (sa, mode, 0); 
+    }
   emit_insn (fcn (sa, stack_pointer_rtx));
 }

[Bug middle-end/48016] Inconsistency in non-local goto save area

[hjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48016

--- Comment #3 from hjl at gcc dot gnu.org <hjl at gcc dot gnu.org> 2011-03-07 14:44:49 UTC ---
Author: hjl
Date: Mon Mar  7 14:44:45 2011
New Revision: 170735

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=170735
Log:
Adjust mode of non-local goto stack save area.

2011-03-07  H.J. Lu  <hongjiu.lu@intel.com>

    PR middle-end/48016
    * explow.c (emit_stack_save): Adjust mode of stack save area.

Modified:
    branches/x32/gcc/ChangeLog.x32
    branches/x32/gcc/explow.c

[Bug middle-end/48016] Inconsistency in non-local goto save area

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48016

--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> 2011-03-16 16:40:31 UTC ---
Another problem.  expand_function_start has

      t_save = build4 (ARRAY_REF, ptr_type_node,
                       cfun->nonlocal_goto_save_area,
                       integer_zero_node, NULL_TREE, NULL_TREE);
      r_save = expand_expr (t_save, NULL_RTX, VOIDmode, EXPAND_WRITE);
      r_save = convert_memory_address (Pmode, r_save);

      emit_move_insn (r_save, targetm.builtin_setjmp_frame_value ()); 

For

Breakpoint 4, expand_function_start (subr=0x7ffff0cebf00)
    at /export/gnu/import/git/gcc-x32/gcc/function.c:4765
4765          r_save = convert_memory_address (Pmode, r_save);
(gdb) call debug_rtx (r_save)
(mem/s/f/j/c:SI (plus:DI (reg/f:DI 54 virtual-stack-vars)
        (const_int -32 [0xffffffffffffffe0])) [0 FRAME.0.__nl_goto_buf+0 S4
A64])
(gdb) next
4767          emit_move_insn (r_save, targetm.builtin_setjmp_frame_value ());
(gdb) call debug_rtx (r_save)
(reg:DI 61)
(gdb)

we generate

(insn 3 2 4 2 (set (reg:DI 61)
        (zero_extend:DI (mem/s/f/j/c:SI (plus:DI (reg/f:DI 54
virtual-stack-vars)
                    (const_int -32 [0xffffffffffffffe0])) [0
FRAME.0.__nl_goto_buf+0 S4 A64]))) x.c:2 -1
     (nil))

(insn 4 3 5 2 (set (reg:DI 61)
        (reg/f:DI 54 virtual-stack-vars)) x.c:2 -1
     (nil))

Instead of

(insn 3 2 4 2 (set (mem/s/f/j/c:SI (plus:DI (reg/f:DI 54 virtual-stack-vars)
                (const_int -32 [0xffffffffffffffe0])) [0
FRAME.0.__nl_goto_buf+0 S8 A64])
        ((subreg:SI reg/f:DI 54 virtual-stack-vars)) x.c:2 -1
     (nil))

[Bug middle-end/48016] Inconsistency in non-local goto save area

[hjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48016

--- Comment #5 from hjl at gcc dot gnu.org <hjl at gcc dot gnu.org> 2011-04-02 05:27:14 UTC ---
Author: hjl
Date: Sat Apr  2 05:27:09 2011
New Revision: 171869

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=171869
Log:
Properly store frame pointer for non-local goto.

2011-03-16  H.J. Lu  <hongjiu.lu@intel.com>

    PR middle-end/48016
    * function.c (expand_function_start): Properly store frame
    pointer for non-local goto.

Modified:
    branches/x32/gcc/ChangeLog.x32
    branches/x32/gcc/function.c

[Bug middle-end/48016] Inconsistency in non-local goto save area

[hjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48016

--- Comment #6 from hjl at gcc dot gnu.org <hjl at gcc dot gnu.org> 2011-06-20 13:58:03 UTC ---
Author: hjl
Date: Mon Jun 20 13:57:59 2011
New Revision: 175210

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=175210
Log:
Use proper mode for stack save area.

2011-06-15  H.J. Lu  <hongjiu.lu@intel.com>

    PR middle-end/48016
    * explow.c (emit_stack_save): Don'ty adjust mode of stack save
    area.
    (update_nonlocal_goto_save_area): Use proper mode for stack save
    area.

Modified:
    branches/x32/gcc/ChangeLog.x32
    branches/x32/gcc/explow.c

[Bug middle-end/48016] Inconsistency in non-local goto save area

[hjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48016

--- Comment #7 from hjl at gcc dot gnu.org <hjl at gcc dot gnu.org> 2011-07-01 12:57:15 UTC ---
Author: hjl
Date: Fri Jul  1 12:57:11 2011
New Revision: 175756

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=175756
Log:
Use proper mode for stack save area.

2011-07-01  H.J. Lu  <hongjiu.lu@intel.com>

    PR middle-end/48016
    * explow.c (update_nonlocal_goto_save_area): Use proper mode
    for stack save area.
    * function.c (expand_function_start): Likewise.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/explow.c
    trunk/gcc/function.c

[Bug middle-end/48016] Inconsistency in non-local goto save area

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48016

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.7.0

--- Comment #8 from H.J. Lu <hjl.tools at gmail dot com> 2011-07-01 13:00:11 UTC ---
Fixed.